e9JOE — Volume 37, Number 3, March 2011

Abstracts of ResearchTo be presented at the 2011 Annual Session of the American Association of EndodontistsApril 13 – 16, at the San Antonio Convention Center, San Antonio, Texas

Abstracts appear as they were submitted by the presenters. The letters in the upper left corner represent the type of presentation: OR for Oral Research Presentation and PR for Poster Research Presentation.

Please refer to the schedule below to determine when the abstracts will be presented. For example, OR 31 will be presented during the Resident Session on Pain and Trauma, Wednesday, April 13, 3:30 – 5 p.m., in Room 206B.

Schedule of Presentations

Resident SessionsWednesday, april 13, 2011Regenerative EndodonticsRoom 206A10 – 11:30 a.m.Abstracts 1-6

Instrumentation IRoom 206A1:30 – 3 p.m.Abstracts 12-16

Canal Disinfection and Debridement IRoom 206B1:30 – 3 p.m.Abstracts 17-21

Pain and TraumaRoom 206B3:30 – 5 p.m.Abstracts 28-32

Thursday, april 14, 2011Endodontic Technology and Materials IRoom 206B10 – 11:30 a.m.Abstracts 39-43

Endodontic Biology IIRoom 206A1:30 – 3 p.m.Abstracts 44-49

Clinical Aspects in Endodontics IIRoom 206A3:30 – 5 p.m.Abstracts 56-60

Canal Disinfection and Debridement IIRoom 206B3:30 – 5 p.m.Abstracts 61-66

Predoctoral Student, General Practitioner and Endodontist SessionsWednesday, april 13, 2011Endodontic Biology IRoom 206B10 – 11:30 a.m. Abstracts 7-11, 67

Instrumentation IIRoom 206A3:30 – 5 p.m.Abstracts 22-27

Thursday, april 14, 2011Clinical Aspects in Endodontics IRoom 206A10 – 11:30 a.m.Abstracts 33-38

Endodontic Technology and Materials IIRoom 206B1:30 – 3 p.m.Abstracts 50-54

Poster Research Presentations

Thursday, april 14, 2011Resident SessionExhibit Hall C2 – 5 p.m.Abstracts 1-53

saTurday, april 16, 2011Predoctoral Student, General Practitioner and Endodontist SessionExhibit Hall C8:15 – 11:15 a.m.Abstracts 54-82

Table Clinics (no abstracts)Thursday, april 14, 2011Resident SessionExhibit Hall C2 – 5 p.m.

saTurday, april 16, 2011Predoctoral Student, General Practitioner and Endodontist SessionExhibit Hall C8:15 – 11:15 a.m.

Oral Research Presentations Oral Research Presentations, continued

e10 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 01Preclinical Trials of Three Regenerative Endodontic ProceduresM.A. Limosani*, K.N. Namerow, P.E. MurrayNova Southeastern University, Fort Lauderdale, FL

The purpose of this preclinical trial was to compare the regeneration effectiveness of four types of endodontic procedures. Following Institutional Animal Care & Use Committee’s approval, the root canals of 36 maxillary and mandibular teeth in two nonhuman primates (M. fasicularis) were cleaned and shaped to a size 40.04 using ProTaper™ and ProFile™ files (DENTSPLY Tulsa Dental Specialties, Oklahoma City, OK) using standard endodontic techniques. Three types of regenerative procedures were used: Group 1—Stimulate a blood clot; Group 2—Stimulate a blood clot and implant a rigid Collagen scaffold (BD Biosciences, Franklin Lakes, NY); Group 3—Stimulate a blood clot and inject a Pepgen P-15 scaffold (DENTSPLY, York, PA); Group 4—Gutta-percha (negative control). An MTA liner was placed above the blood clot and the access cavity was restored with glass ionomer (Fuji II, GC, Tokyo, Japan). After a postoperative time of 30 or 60 days, teeth were processed for histology and analyzed at x200 magnification according to ISO criteria. Data was analyzed by ANOVA statistical tests (P-values) at a significance of 95%. No regeneration was observed in teeth obturated with gutta-percha. Some cells were observed in the canals of teeth following revascularization. Greater numbers of cells were observed in teeth where a rigid collagen scaffold or an injectable Pepgen P15 scaffold had been implanted (P<0.05). No adverse events were observed. The use of injectable and rigid scaffolds was more successful than using the traditional revascularization procedure to accomplish regenerative endodontic therapy. This study was supported by NSU Health Professions Division.

OR 02The Use of Biosensors to Detect Toll-Like Four Receptor Activators in Root Canal SystemsC. Cosby*, F. Teixeira, K. Hargreaves, A. DiogenesUniversity of Texas at San Antonio, TX

The innate immune response represents the first line of defense. It is responsible for the recognition of patterns of microbial infection and tissue injury to trigger the initiation and maintenance of inflammation. Lipopolysaccharides (aka, endotoxin) are integral constituents of the bacteria cell wall of Gram- bacteria and a known initiator of apical periodontitis. LPS mediates its pro-inflammatory effects by activating its putative receptors (TLR4, CD14 and MD2) in immune cells. However, it has been demonstrated that LPS is not the only activator of TLR4, and that endogenous TLR4 activators (agonists) may be released during inflammation. Therefore, we hypothesized that measurement of TLR4 activators in the human dental pulp will be correlated with clinical diagnosis. To test this hypothesis, we characterized a new methodology (biosensor) based on the expression of a TLR4/CD14/MD2 receptor complex and a reporter gene downstream the promoter for the pro-inflammatory factor NFk-b in HEK cells. Intracanal samples were collected with S1 and S2 ProTaper™ instruments from teeth diagnosed with irreversible pulpitis (IP), necrotic pulp and normal pulp. The biosensor cells were exposed to the debris and to a LPS standard curve. Activators of TLR4-mediated inflammatory signals were detected in all samples, except normal pulp samples. Importantly, samples from teeth with irreversible pulpits had high levels of TLR4 activators. Collectively, these results suggest that this new assay is a sensitive method of detecting physiologically relevant concentrations of TLR4 activators, and that teeth diagnosed with IP express significant levels of endogenous activators of TLR4 that appear distinct from endotoxins. This study was supported by the AAE Foundation.

OR 03Emdogain Inhibits Proliferation and Stimulates Differentiation of Human Dental Pulp Stem CellsM. Yang*1, Q. Zhu1, J. Jiang1, K. Safavi1, S. Shi2, M. Mina1 1University of Connecticut, Farmington, CT, 2University of Southern California, Los Angeles, CA

The goal of this study was to investigate the effects of the purified enamel matrix protein product Emdogain (EMD) on the growth and osteogenic differentiation of human dental pulp stem cells (hDPSCs). The gene expression of collagen α1 (Col1α1), bone sialoprotein (BSP) and osteocalcin (OC) were also analyzed during the differentiation. Cultures of hDPSCs were treated with or without 100 ug/ml EMD for 1, 3, 5 and 7 days. At each time point, cell proliferation was measured by cell counting, crystal violet staining and colorimetric MTS assay. To study the effect of EMD on hDPSCs differentiation, confluent cells were cultured with ascorbic acid and ß-glycerophosphate to induce osteogenesis for up to 3 weeks. At the end of each week, cell differentiation was analyzed by alkaline phosphatase and von-Kossa staining, as well as expressions of Col1α1, BSP and OC mRNAs. The result showed a significant decrease in cell growth in EMD-treated groups at all time points as compared to the controls (t-test, p<0.05). Under osteogenic differentiation conditions, EMD treatment significantly enhanced mineralization as evidenced by extended von-Kossa staining and increased the expression of BSP and OC (one-way ANOVA, p<0.05). This study indicates that EMD inhibits proliferation but promotes differentiation of hDPSCs. This study was supported by the AAE Foundation.

OR 04De Novo Creation of Tooth Constructs Using Stem Cells From Human Exfoliated Deciduous TeethR. Raymond*, P. Murray, K. NamerowNova Southeastern University, Fort Lauderdale, FL

The purpose of this study was to conduct a histological analysis of tooth constructs created from human dental stem cells. Stem cells from human exfoliated deciduous teeth (SHED) were grown to confluence and seeded on three-dimensional tissue engineering scaffolds. Tooth constructs (n=90) were created by seeding SHED on hydroxyapatite-calcium phosphate tissue engineering scaffolds or Collacote™-based scaffolds (collagen, Zimmer Dental, Carlsbad, CA). The negative control was an absence of stem cells. Growth factors utilized included: 100 ng/ml of Stromal-derived factor-1 (SDF-1), Bone morphogenetic protein-7 (BMP-7), and ß-Glycerophosphate (ß-GP) in a solution of 2 mg/ml neutralized rat tail type-1 collagen (R&D, Minneapolis, MN). Tooth constructs were submerged in Dulbecco’s Minimal Essential Media containing 10% fetal calf serum and antibiotics, maintained at 37°C in a 5% CO2 atmosphere for 30 and 60 days. Neutral red dye (0.0016%) was added to the culture media to stain metabolically active cells. Specimens were fixed in formalin, dehydrated and processed for light microscope histology at x200 magnification according to ISO criteria. Data was analyzed by ANOVA statistical tests (P values) at a significance of 95%. SHED survival was observed in all tooth constructs, with and without growth factors SDF-1, BMP-7 and ß-GP, versus the negative control (P<0.05). These in vitro results suggest that scaffolds, growth factors and cell cultures can be used to create tissue-engineered teeth. This technique may allow future endodontists to deliver tooth constructs as an alternative to conventional dental implants. This study was supported by the AAE Foundation and NSU Health Professions Division.

e11JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 05An In Vitro Evaluation of the Growth of Human Periodontal Ligament Fibroblasts Following Exposure to EndoSequence™ BC Sealers™

N.K. Kim*, S.J. Sidow, K. McNally, K. Lindsey, A. ChuangU.S. Army Dental Activity, Fort Gordon, Augusta, GA

EndoSequence™ BC Sealer™ (ESBCS) is a new bioceramic sealer marketed as having biocompatible properties, a short setting time and outstanding sealing properties. During the obturation phase of nonsurgical root canal therapy, sealer can be extruded beyond the apical foramen into the periradicular tissue exposing the human periodontal ligament fibroblasts (hPDL) to the potential cytotoxic effects of the sealer. The purpose of this in vitro study was to evaluate the biocompatibility of ESBCS on human periodontal ligament (hPDL) fibroblasts. Cultures of hPDL cells were challenged with different concentrations of ESBCS, (400, 800, 1200 and 1600 µg/mL). The cytotoxicity was evaluated at 1, 3 and 7 days. Negative controls included untreated cells and cells treated with different concentrations of ethanol. The viability of the PDL cells was assessed using the MTT assay in 24 well plates. Results from MTT assay demonstrated a significant reduction in hPDL fibroblasts at 1600 µg/ml by day 3. By day 7, all concentrations of ESBCS were significantly cytotoxic. The cytotoxicity of EndoSequence™ BC Sealer™ on human periodontal ligament cells increases with both concentration and exposure time.

OR 06Comparison of Two Different Scaffolds Used in the Regeneration of the Pulp-Dentin ComplexR.S. Bose*1, A. Diogenes1, M. Li1, M. Henry1, Z. Khaing2, C. Schmidt2, K. Hargreaves1 1University of Texas at San Antonio, TX, 2University of Texas at Austin, Department of Biomedical Engineering, TX

An emerging area of interest in regenerative studies is related to scaffold selection used to support the growth of proliferating stem cells. Polymer-based scaffolds are attractive since some are made from materials used in absorbable sutures that are United States Food and Drug Administration (FDA) approved. Hydrogels containing FDA-approved hyaluronic acid (HA) also appear promising since they can be self-polymerizing, injectable and the breakdown products promote angiogenesis. The purpose of this study was to compare and characterize regenerated tissues within the canal system containing two different scaffolds: open-cell polylactic acid (OPLA™, BD Biosciences, Franklin Lakes, NJ) or HA hydrogel with collagen and laminin. Scaffolds with human stem cells from apical papilla were placed into the canal system of 16 root tips (1.7 mm canal diameter, 8 mm in length and coronal opening closed with 2 mm of MTA) and implanted into subcutaneous tissues of immunocompromised mice for three months. Samples were decalcified, sectioned and the regenerated tissue within the canal space was characterized with immunohistochemistry and confocal microscopy. Results showed the presence of extensive tissue in the canal space in both groups. The tissue was composed mostly of cells of human origin (expressed human-specific mitochondria protein) and also contained blood vessels of mouse origin (expressed mouse-specific endothelial protein). OPLA remained in all samples and appeared resistant to degradation over this time period. These results suggest HA hydrogel is superior to OPLA as a potential scaffold to support the regeneration of pulpal tissues. This study was supported by the AAE Foundation.

OR 07Histomorphometric and Micro-CT Analysis of Pulpal Response to Geristore™ and Calcium HydroxideH.F. Ounsi*, Z. Salameh, K. Al-HezaimiKing Saud University, Riyadh, Saudi Arabia

Objective: The purpose of this study was to evaluate the thickness and characteristics of reparative hard tissue produced following the application of calcium hydroxide and Geristore™ as direct pulp capping agents. Methods: Sixteen teeth in two baboons were used. Teeth were divided into two groups (n=8). calcium hydroxide and Geristore™ were applied, following a superficial pulp amputation performed with carbide round bur #4. Amalgam restoration was then placed. Animals were sacrificed 16 weeks later and en bloc sections were taken and stained with H&E, Masson’s trichrome and retic. A microcomputed tomography and histological examination were performed to evaluate the presence and thickness of a reparative hard tissue and its characteristics such as presence/absence of tubular structures and tunnel defects. The data were statistically analyzed using Kruskal-Wallis ANOVA and Dunn’s multiple comparison tests, statistical significance was predetermined at α=0.05. Results: Calcium hydroxide showed the formation of a thin, porous, reparative tissue with absence of infection of the pulpal tissue, while Geristore™ reported a complete absence of newly formed reparative tissue with severe inflammation of the pulpal tissue. Conclusion: Direct pulp capping with Geristore™ did not allow pulp tissue repair and failed histopathologically in 100% of the cases.

OR 08Biocompatibility of EndoSequence™ and MTA-Based Materials: An In Vitro AnalysisB.S. Willershausen*, B. Briseño Marroquin, I. WillershausenJohannes Gutenberg University, Mainz, Germany

Aim: The biocompatibility of dental materials is decisive to the success rate of an endodontic performed treatment. In the present study, potential cytotoxic differences of different mineral trioxide aggregate-based compounds were analyzed by means of their effect on the vitality, proliferation rate and cytokine release of human gingival fibroblasts. Materials and Methods: MTA Angelus (Angelus, Londrina, PR, Brazil), white and grey ProRoot™ MTA (DENTSPLY Maillefer, Ballaigues, Switzerland) and EndoSequence™ Root Repair Material (Brasseler USA, Savannah GA) were mixed according to the manufacturers’ recommendations and subsequently incubated with human gingival fibroblasts (4th passage, 104 cells/ml) for up to 96 h. Cells without materials were used as controls. Cell proliferation (RFU) was determined by means of AlamarBlue® labeling (FLX 800/Bio-Tek Instruments, Winooski, VA). The LIVE/DEAD® Viability/Cytotoxicity Kit (Invitrogen, Eugene, OR) was used to distinguish between live and damaged/dead cells. The release of adenylate kinase was also determined. Results: Human gingival fibroblast proliferation seemed to be dependent upon the dental material and cultivation time. After an incubation period of 96 hrs, all MTA-based materials slightly inhibited cellular proliferation when compared to the control group. MTA Angelus, white and grey ProRoot™ MTA inhibited the cellular proliferation significantly more than EndoSequence™ and the control group (p<0.001). Conclusions: The results of this study demonstrate that all MTA-based materials showed a low cytotoxicity and induced a low level of cytokine release. Thus, EndoSequence™ and all MTA-based materials can be rated as biocompatible dental materials and their clinical use recommended.

e12 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 12Impact of Canal Shape on Filled Canal Volume and Remaining Filling Material After RetreatmentD.K. Rechenberg*1, M. Zehnder1, S. Trabold2, F. Paque1

1University of Zürich Dental School, Zürich, Switzerland, 2St. Moritz, Switzerland

Objective: To assess the impact of canal shape on canal volume that can be filled and the root filling material that is left behind after a subsequent retreatment procedure. Methods: Fifteen extracted human maxillary premolars and 15 mandibular first molars were used. Root canals were prepared using ProFile® instruments. Subsequently, canals were filled with gutta-percha and AH-Plus® sealer by cold lateral condensation. Canals were later retreated using the master apical rotary followed by the next two ProFiles® of increasing size. Teeth were viewed in a µCT scanner before and after each treatment step. Defined and validated threshold levels were used to differentiate empty root canal volumes, root dentin and root filling materials from each other. Canal shape was defined as the averaged ratio between long and short canal diameter, determined for each 1 mm of the canal. Data was averaged between the two canals in premolars, only the distal canals were assessed in molars. Appropriate parametric and nonparametric tests were used to statistically compare the data, alpha = 0.05. Results: Canals in premolars had a round shape after preparation (1.0 ± 0.0) distal counterparts in mandibular molars were oval (1.6 ± 0.5). Significantly (p<0.05) more canal volume could be filled, and significantly less filling material remained after retreatment in premolars compared to distal canals of mandibular molars. There was a high correlation between canal shape, filled canal volume and remaining filling material. Conclusion: The instrumenting and filling technique under evaluation is more suitable for round than for oval canals.

OR 09Controlled Calcium Hydroxide Release From PLGA NanoparticlesT. Komabayashi*1, A. Wadajkar2, C. Ahn3, L. Tong3, Q. Zhu4, L.A. Opperman1, P.C.Dechow1, J. Yang2, K.T. Nguyen2

1Baylor College of Dentistry, Dallas, TX, 2Arlington, TX, 3Dallas, TX, 4University of Connecticut, Farmington, CT

Objectives: Calcium hydroxide (CH) is widely used to disinfect root canals. However, research on CH drug delivery systems for deep penetration into dentin tubules has seldom been reported. The aim of this study is to evaluate CH release from poly(lactic-co-glycolic acid) (PLGA) nanoparticles over a specific time period. Methods: CH-loaded PLGA nanoparticles were made from dichloromethane, polyvinyl alcohol, PLGA, deionized water and CH. The PLGA nanoparticles were lyophilized using a freeze-dry system. Two mg particles (n=4) were incubated at 37°C in a tube with 2 mL of phosphate-buffered saline (PBS) solution. At 1, 2, 4, 8 and 14 hours and at 1, 2, 3, 7 and 14 days, samples of PBS solution containing the released CH were collected and PBS volume was reconstituted with 1 mL of fresh PBS solution. Then CH content was quantified using a spectrometer. The percentage of cumulative CH release was calculated. The rate of CH release between adjacent time points was computed by dividing each incremental release by the duration of the release period. Results: Drug loading efficiency was 11.3%. The cumulative CH release (% of loading) at 1, 3, 7 and 14 days was 23.9%, 30.8%, 34.2% and 37.6%, respectively. There was significant incremental CH release per hour until day 3 (72 hours). After that, the significance of incremental CH release per hour disappeared (p=0.364 at day 7; p=0.610 at day 14). Conclusions: CH release was very rapid for the first 3 days (72 hours). Then, slow CH release continued over time. This study was supported by the National Institutes of Health.

OR 10Human Dental Pulps and Periodontal Ligament Fibroblasts Display Distinct CXCL12 Production Patterns Against Enterococcus Faecalis LTA and Escherichia Coli LPSC.R. Sipert*1, A.C.F. Morandini1, A.P. Campanelli1, M.A.A. Machado1, S.H.P. Oliveira2, A.J. Trachtenberg3, W.P. Kuo3, C.F. Santos1

1Bauru, Brazil, 2Aracatuba Dentistry School, Sao Paulo, Brazil, 3Harvard School of Dental Medicine, Boston, MA

Fibroblasts are the most numerous cells of connective tissues, but are not considered as a unique group of cells. Besides structural function, fibroblasts are shown to be active during innate immunity events. This study aimed to investigate the production of the chemokine CXCL12 by human periodontal ligament, permanent and deciduous dental pulp fibroblasts. Primary cultures of fibroblasts were established with explants from human periodontal ligament (PLF), permanent (PPF) and deciduous dental pulps (DPF). After fourth passage, cells were seeded (5x104 cells/well) and medium alone (control) or containing 0.1-10 µg/mL of LTA from Enterococcus faecalis or LPS from Escherichia coli was added to the cells. After 1, 6 and 24 h, cell supernatants were collected for chemokine analysis through ELISA. Additionally, cells were evaluated for microRNA expression through microarray. Comparing with controls, CXCL12 production by DPFs was unaltered by both antigens. However, CXCL12 produced by PPF was highly decreased by LPS and LTA (ANOVA and Tukey post-test, p<0.001). LTA decreased CXCL12 production by PLF at 10 µg/mL at 6 (p<0.01) and 24 h (p<0.001) and under LPS challenge, CXCL12 production by PLF decreased in all experimental conditions (p<0.01). Molecules involved with CXCL12 protein synthesis, such as miR-141 and miR-200a, were overexpressed in PPF and PLF, respectively. PL and PP fibroblasts were able to respond to LPS and LTA, but with a different pattern of CXCL12 production. Deciduous dental pulp fibroblasts did not show the same response. As tissue specific molecules, microRNAs could be involved with the differential CXCL12 production here observed.

OR 11Pulp Revascularization of Necrotic Immature Open Apex Dog Teeth Using Triantibiotic Treatment ProtocolA. Khademi*, O. Dianat, S. RazaviIsfahan Medical University, Isfahan, Iran

Aim: This study was conducted to examine the success rate of a new treatment protocol including root canal disinfection with a mixture of ciprofloxacin, metronidazole and tetracycline antibiotics and blood clot matrix on revascularization, root development and thickening of dentinal wall of immature dog teeth. Methodology: Twenty single- or two-rooted immature teeth from 3 dogs were selected. Three teeth were selected as positive control and 3 teeth as negative control. The canals were infected and periapical lesions were induced. After confirmation of periapical pathosis induction, the canals were disinfected with copious irrigation and a combination of three antibiotics (25mg/ml of each) mentioned. After disinfection, the apex was mechanically irritated to initiate bleeding into the canal to produce a blood clot to the level of cementoenamel junction. The double seal of the coronal access was then made with MTA and a bonding restoration. Radiographic and histologic finding was evaluated after 3- and 6-month follow-ups. Results: Periapical healing and apical closure were observed in 70% of teeth and thickened wall in 40%, confirmed by radiography. Histologic finding was in line with radiographic evaluation. Coronal migration of vascular granular tissue, presence of fibroblasts and occasionally odontoblast-like cells, dentin-like tissue apposition on dentinal walls and remodeling of PDL and bone, as well as a mild to moderate infiltration of chronic inflammatory cells were observed. Conclusion: This protocol can increase the success rate of treatment of immature teeth with revascularization, apical closure and thickening of dentinal walls. This study was supported by Isfahan University of Medical Sciences and consultants Seyed Mohammad Razavi and Omi Dianat.

e13JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 13An In Vitro Comparison of Cyclic Fatigue of ProFile® Vortex™ and EndoSequence™ Rotary Nickel-Titanium FilesF. Al-Foraih*, K.J. Replogle, R.D. Archer, P.C. Moon, A.M. BestVirginia Commonwealth University, Richmond, VA

The purpose of this study was to determine the number of rotations to fracture (cyclic fatigue) of the ProFile® Vortex™ (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) compared to the EndoSequence™ files (Brasseler USA, Savannah, GA) using an in vitro apparatus simulating a curved canal. Two-hundred ProFile® Vortex™ files of 25mm length were divided equally into ten groups, one for each of the ProFile® Vortex files 20/0.04, 20/0.06, 25/0.04, 25/0.06, 30/0.04, 30/0.06, 35/0.04, 35/0.06, 40/0.04 and 40/0.06. Two-hundred EndoSequence™ files of 25mm length were divided equally into ten groups of the same tip and taper sizes analogous to the ProFile® Vortex™ file groups. Files were rotated at 500 rpm in a fixed groove in the metal block of the apparatus. The angle of deflection for all files was fixed at 33 degrees, determined using the Schneider method. The time from initiation of rotation to fracture was recorded and rotations to fracture were calculated. The data collected was analyzed using a two-way ANOVA, followed by specific post hoc contrasts comparing the two brands for each tip and taper combination. The results demonstrated that the ProFile® Vortex™ files required significantly greater rotations to fracture than the EndoSequence™ (p < 0.0001) in all tip sizes in both 0.04 and 0.06 tapers. ProFile® Vortex™ files exhibit a greater resistance to cyclic fatigue than the EndoSequence™ files. This study was supported by the AAE Foundation, VCU Department of Endodontics and DENTSPLY Tulsa Dental Specialties.

OR 14Evaluation of Canal Instrumentation Using GT-Series-X™ Versus Prosystem-GT™

N. Tabatabaei*University of British Columbia, Vancouver, BC, Canada

This study compared the canal center displacement of two rotary file systems by using the Endodontic Cube. Mesial roots of 31 mandibular first and second molar teeth with separate ML and MB canals and curvatures ranging from 15 to 40 degrees were randomly divided into two groups. After access cavity preparation and working length determination, each tooth was embedded in composite resin using the endodontic cube as a mold. 1.5 mm tooth-resin complex slices were made using a Buehler™ slow speed saw. After reassembly of the sections, canals were instrumented with either GT-Series-X™ or ProSystem-GT™ to size 30/06. AutoCad™ software was used to measure root section images of instrumented canals. Data was analyzed using the t-test (p < 0.05). The overall mean canal center displacement of the ProSystem GT™ was 0.08 ± 0.074 mm, while for GT Series-X™ it was 0.064 ± 0.063 mm. Also, based on different canal regions, the canal center displacement above the curve (coronal third) of ProSystem-GT™ and GT-Series-X™ was 0.11 ± 0.061 and 0.08 ± 0.052, respectively. The canal center displacement at the curve region of ProSystem-GT™ and GT-Series-X™ was 0.06 ± 0.0 and 0.05 ± 0.027, respectively. Finally, the canal center displacement below the curve region of ProSystem-GT™ and GT Series-X™ was 0.05 ± 0.052 and 0.03 ± 0.045, respectively. Both rotary NiTi systems tended to move the original canal toward the furcation, but the ProSystem-GT™ caused significantly greater canal center displacement than GT-Series-X™. However, there were no significant differences between the regions of canal center displacement with either GT-Series-X™ or ProSystem-GT™. The study was funded by the AAE Foundation and the Canadian Academy of Endodontics.

OR 15Effects of Manufacturing Techniques on Cyclic Fatigue of Nickel-Titanium Rotary Endodontic FilesA.E. Abide*, V. Himel, J. HaganLouisiana State University, New Orleans, LA

Introduction: Several new methods have been developed for manufacturing nickel-titanium endodontic rotary files. This study evaluates the effects manufacturing techniques have on files’ abilities to resist cyclic fatigue. Methods: A total of 120 NiTi rotary files were used in the study. Ten files of ISO size 25.04 and 10 files of ISO size 40.04 were tested from each of the following six groups: Twisted Files™ (SybronEndo, Orange, CA), ProFile™ Vortex (DENTSPLY Tulsa Dental Specialties, Tulsa, OK), 10 Series™ NiTi, 10 Series™ CM Wire™, Typhoon NiTi and Typhoon CM-wire (DS Dental, Johnson City, TN). The number of cycles to failure was calculated by rotating each file at the manufacturer’s recommended speed in a stainless steel simulated canal of 60 degree curvature with a 5mm radius of curvature. Results: The 10 Series™ CM Wire™ showed significantly more resistance to cyclic fatigue than all other files tested at both size 25 and 40. Conclusion: Manufacturing methods used to create nickel-titanium files can have a significant effect on the files abilities to resist cyclic fatigue. While several of the tested methods produce files with acceptable properties, 10 Series™ CM Wire™ files showed the best resistance to cyclic fatigue. This study was supported by DS Dental.

OR 16Comparison of Autoclaving Effects on Torsional Deformation and Fracture Resistance of Three Innovative Endodontic File SystemsR.B. Casper*1, H.W. Roberts1, M.D. Roberts1, V.T. Himel2, B.E. Bergeron1

181st Medical Group/DS/SGDDT/Keesler Air Force Base, MS, 2Louisiana State University, New Orleans, LA

Introduction: Innovative manufacturing techniques have produced nickel-titanium rotary instruments reporting superior properties. These include: ProFile®; Vortex™ and (PV) M-Wire™ files (DENTSPLY Tulsa Dental Specialties, Tulsa, OK), Twisted Files™ (TF) (SybronEndo, Orange, CA) and 10 Series™ CM Wire™ files (CM) (DS Dental, Johnson City, TN). Sterilization is recommended prior to use and is repeated if files are reused and/or carried forward between cases. Purpose: To compare the effects of multiple autoclaving cycles on the torsional load resistance of these three new rotary endodontic files. Methods: PV, TF and CM files (n=100; size 25/.04) were divided into five groups (n=20). Files were autoclaved for 1, 2, 3 and 7 sterilization cycles. A control group was not subjected to autoclaving. Files were tested in a torsiometer according to ISO 3630-1 standards. Torsional load and rotational degrees to failure were recorded. Mean data were analyzed using Kruskal-Wallace/Dunn post hoc (P=0.05). Results: Autoclave cycles had no effect on file performance within all groups. PV and CM displayed significantly greater resistance to torsional load failure than TF (P<0.001), but were not different from each other (P>0.05). Rotational degrees to failure for TF and CM were significantly higher than PV (P<0.001), with TF demonstrating greater rotational degrees to failure than CM (P<0.05). Conclusion: Under the conditions of this study, repeated autoclaving did not affect torsional resistance for unused files of the systems evaluated. This study also found that CM Wire™ files may have a combined advantage of higher torsional fracture strength and greater deformation prior to failure.

e14 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 17Compositional Changes During Biofilm Formation by Root Canal Bacteria on Human Salivary MUC5B Conditioning FilmL.E. Chávez de Paz*University of Connecticut, Farmington, CT

Introduction: Biofilm communities are formed in root canals after oral organisms invade the pulp chamber, using saliva as a vehicle. Glycoproteins in saliva deposit as conditioning films that will enhance the attachment of microorganisms to the root canal walls. In this study, we investigate the effect of a surface coating of human salivary mucin MUC5B on the species composition of biofilms formed by a community of three oral microorganisms. Methods: The biofilm community used in the present study was composed of L. fermentum, S. mitis and A. naeslundii. Mini-flow chamber systems were coated with human salivary MUC5B overnight and biofilms were allowed to form for 72h. Samples of formed biofilms were retrieved at 24h and 72h and their composition was analyzed by quantitative fluorescence in situ hybridization (FISH). Results: Biofilm communities that formed on surfaces coated with salivary MUC5B had a different composition at the two time-points analyzed. The subpopulation of A. naeslundii predominated at 66% (±3%) in biofilms formed on MUC5B at 24h, while S. mitis and L. fermentum represented 29% (± 3%) and 5% (±1%), respectively. Interestingly, after 72h of biofilm formation, the composition was reverted with a clear predominance of L. fermentum (56% ±3%), followed by S. mitis (33% ±1%) and A. naeslundii (11% ±2%). Conclusion: The salivary glycoprotein MUC5B deposited on a surface as a conditioning film changes the composition over time of the mixed biofilm community. This effect is related to the ability of L. fermentum to use MUC5B as a nutritional source.

OR 18Effect of EndoActivator® System on Antibacterial Efficacy of MTADA.I. Harhash*, S. Shabahang, M. TorabinejadLoma Linda University, Loma Linda, CA

Studies have shown that MTAD is effective against some species of E. faecalis when used as a final irrigant for five minutes. EndoActivator® system is a device to enhance the effectiveness of root canal irrigants. The purpose of this study was to investigate the effect of EndoActivator® system on the time exposure required for antibacterial efficacy of MTAD. One-hundred and forty human-extracted single-rooted teeth were used in this study. After removing their crowns, the roots were incubated with E. faecalis for four weeks under aerobic conditions at 37°C. Each root canal was instrumented using rotary instrumentation to an apical ISO size of 36 and irrigated with 1.3% NaOCl between each instrument size. The samples were then divided into seven equal groups of 20 each: two control groups and five experimental groups. Bacterial samples were collected after instrumentation and irrigation with MTAD with and without EndoActivator® system for different time intervals. Colony-forming units (CFUs) per 1 ml were enumerated in various groups and statistically analyzed using Kruskal-Wallis test. The results showed that activation of MTAD with EndoActivator® system for 1.5 minutes was as effective as the use of MTA for five minutes as a final rinse in completely inhibiting growth of E. faecalis. Based on these findings, it appears that the use of EndoActivator® system effectively reduces the exposure time needed for MTAD to kill E. faecalis. This study was supported by the research committee at the LLU dental school and DENTSPLY.

OR 19A Survey of the Irrigation Protocols Used by Dentists in British Columbia, CanadaH. Abtin*, M. Haapasalo, J. AleksejunieneUniversity of British Columbia, Vancouver, BC, Canada

Objectives: The study aimed 1) to investigate the type, frequency and order of use of irrigants and irrigation techniques used in the chemical cleaning of the root canal and 2) to compare how the aforementioned treatment modalities are used by general practitioners and endodontists. Material and Methods: The survey included general dentists (GP) and endodontists (ENDO) in the province of British Columbia (BC), Canada. Following a phone call, a two-page questionnaire consisting of 49 questions was faxed to 150 GP and to all 42 ENDO in BC, containing questions about the type of irrigants used in case of vital pulp (VP) and nonvital pulp (NVP), concentration of sodium hypochlorite (NaOCl), volume of various irrigants, type and size of irrigation needles, depth of the irrigation needle tip in the canal, and initial and final irrigant used during endodontic treatment. The data were analyzed using one-way ANOVA with post hoc Bonferroni adjustment. Results: The overall response rate was 79.2%. Different irrigants in treating NVP were used as follows: sodium hypochlorite: ENDO 95.74% and GP 94.22% (P= 0.657); EDTA: ENDO 76.24% and GP 36.23% (P= 0.000); chlorhexidine: ENDO 34.06% and GP 14.66% (P= 0.005); and RC-Prep: ENDO 31.97% and GP 71.98% (P= 0.000). There were no significant differences among the two groups of dentists with regard to other solutions. Group ENDO used higher concentration of NaOCl than group GP (P= 0.000). Conclusion: NaOCl was the most common irrigant used by both groups, while EDTA was used mainly by endodontists. This study was supported by the AAE Foundation and the Canadian Academy of Endodontics.

OR 20A Comparison of Apical Negative Pressure System and Standard Needle Root Canal Irrigation: A Prospective Randomized In Vivo StudyR. Pawar*1, A. Alqaied1, J. Stratton2, B. Kaufman1

1University of Connecticut, Farmington, CT, 2University of Connecticut, Storrs, CT

Investigation of the role of different methods of irrigation has yielded mixed results in obtaining microbe-free root canals. Recent in vitro studies using an apical negative pressure irrigation system, EndoVac™, have demonstrated promising results while also preventing potential extrusion of irrigants into the periapical region. The purpose of this randomized, single-blinded, prospective, in vivo clinical study was to compare the efficacy of standard needle irrigation to that of EndoVac™ in obtaining microbe-free canals. Forty patients with single-rooted teeth with pulp necrosis diagnosed by negative cold test and the presence of periapical radiolucency requiring primary endodontic treatment were recruited to this study. Conventional endodontic therapy was provided to patients in both groups in two clinical visits, using NaOCl as the irrigant and EDTA for smear-layer removal. Teeth were randomly assigned to either group. Tooth surfaces were disinfected and surface cultures were obtained prior to access. For each tooth, 2 intra-canal bacterial cultures were obtained before instrumentation and prior to intervisit medication with calcium hydroxide. These samples were monitored for growth in enriched anaerobic culture media over a period of 7 days. Statistical analysis using Fisher’s Exact Test revealed no significant association (p=0.337) between negative microbial cultures and the irrigation method used; neither was there any significant association (p=0.603) between postoperative complications and irrigation method used. We conclude from our clinical investigation that irrigation with EndoVac™ does not necessarily provide an added advantage over standard needle irrigation in producing microbe-free root canal systems. This study was supported by the AAE Foundation.

e15JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 21Histologic Evaluation of Canal and Isthmus Debridement Efficacies of Two Different Irrigant Delivery Techniques in a Closed SystemJ.M. Adcock*1, S. Sidow1, K. McNally1, K. Lindsey1, F.R. Tay2

1U.S. Army Dental Activity, Fort Gordon, Augusta, GA, 2Medical College of Georgia, Augusta, GA

This study compared the canal and isthmus debridement efficacies between side-vented needle irrigation (SNI) and continuous ultrasonic irrigation (CUI) delivery techniques using a simulated, closed-canal design. Microcomputed tomography was utilized to confirm a narrow isthmus in the mesial roots of 20 selected mandibular first molar teeth. Each root was sealed at the apex and embedded in polyvinylsiloxane to simulate the closed canal system. All teeth were instrumented with the same technique. Final irrigation was performed with either the SNI or CUI technique (N=10). Masson trichrome-stained sections were prepared from demineralized roots at 10 canal levels between 1.0 and 2.8 mm from the anatomical apex. The area and debris occupied by the canals and isthmus of each root were measured by the NIH ImageJ software and statistically analyzed using two-way ANOVA. Overall, there was not a significant difference in the amount of debris remaining in the canals between the two groups. There was more debris in the apical 0.2 mm section regardless of irrigation technique when compared to other canal sections. The isthmus contained significantly less debris in the CUI group between isthmus levels 1.0-2.4 mm. Neither technique completely removed debris from the canal or isthmus region. The ProUltra® PiezoFlow™, which utilizes the CUI concept, removed significantly more debris from narrow isthmuses of mandibular mesial roots.

OR 22Incidence of Canal Systems in the Mesiobuccal Roots of Maxillary First and Second Molars in Saudi Arabian PopulationK.S. Alfouzan*, H. Ounsi, K. Merdad, K. Al-HezaimiRiyadh, Saudi Arabia

The aim of this prospective study was to determine the number of canals treated in the mesiobuccal roots of the maxillary first and second molar teeth of a sample of the Saudi Arabian population during a one-year period of a postgraduate endodontic program. The attending endodontic faculty member supervising the case verified the number of canals in the teeth clinically and radiographically. There were 308 maxillary first molars and 162 maxillary second molars, of which 158 (51.3%) and 32 (19.7%) met the criterion of having two canals detected and treated in the mesiobuccal root of the maxillary first and second molars respectively. It was concluded that the occurrence of mesiopalatal canal in the mesiobuccal root of the maxillary first and second molars of the sample of the Saudi Arabian population was high. The fact that more than half the mesiobuccal roots of the maxillary first molars bare two canals is enough reason to always assume that two canals exist until careful examination proves otherwise.

OR 23Root Canal Configuration and Main Foramina Number of Maxillary MolarsB. Briseño Marroquín*, R. Gall, B. WillershausenJohannes Gutenberg University, Mainz, Germany

Successful root canal treatment is enhanced through accurate knowledge of the configuration morphology of the root canal system. The root canal configuration (RCC) of 150 first and 183 second maxillary molars was investigated. Access was gained and radiographs in a mesial projection after having placed instruments (ISO 10) in each root canal were made. RCC was numerically described in the coronal, middle and apical thirds, and the main foramina number (MFN) (4th numerical figure) was recorded and statistically analyzed. The first molar results showed that the apical third RCC and MFN almost always corresponded, or the MFN was seldom lower (11.4% mesial; 4.6% distal roots). The most common RCC/MFN observed in the mesial root were 2-2-2-2 (56.7%), 2-2-1-1 (21.3%), 2-2-2-1 (10.7%), 3-3-2-2 (4.7%), 1-1-1-1 (34.0%), 2-2-1-1 (33.3%) and 2-2-2-2 (18.7%) in the distal root. The second molar results showed that the apical third RCC and MFN almost always corresponded, or the MFN was slightly lower (12.1% mesial; 3.8% distal roots). The most common RCC/MFN observed in the mesial root were 2-2-2-2 (42.6%), 2-2-1-1 (37.2), 2-2-2-1 (11.0%), 1-1-1-1 (65.6%), 2-2-1-1 (15.3), 2-2-2-2 (8.7%) and 2-1-1-1 (6.0%) in the distal root. It can be concluded that the RCC of mandibular molars is quite varied; that the mesial root has predominantly two root canal entrances, yet in 36.6% (first molar) and 55.9% (second molar) only one main foramina and that the apical third RCC/MFN is 1-1 in 76.7% (first) and 91.3% (second) in the distal roots.

OR 24The Effect of Three Rotational Speed Settings on Torque and Apical Force With Vortex™ Rotary Instruments In VitroS.F. Bardsley*, C.I. Peters, O.A. PetersUniversity of the Pacific, San Francisco, CA

In curved canals, both number of rotations and torque relate to fracture resistance of nickel-titanium rotaries via the respective mechanisms of brittle and flexural failure. Increased rotational speed (RPM) may lead to higher cutting ability and could overcompensate for increased fatigue. The impact of three RPM settings on peak torque (Nmm) and apically directed force (N) during root canal preparation were investigated in vitro. S-shaped canals in plastic blocks (n=12/group) were instrumented with Vortex™ rotaries (DENTSPLY Tulsa Dental Specialties, Tulsa, OK), sizes #15-30, .04 taper. Rotaries were used in a manufacturer-recommended sequence. A total of 216 preparation procedures were carried out using a custom testing platform. RPM was set at 200, 400 or 600; automated axial feed mirrored clinical handling, resulting in two in-and-out movements, each to preset insertion depths. Torque and apical force were continuously recorded and peak values statistically contrasted using ANOVAs. No file fractures were observed in any of the three experimental groups. Peak torques and forces varied by instrument size and were highest at 200 RPM for all sizes; torque and force were reduced by 32% and 48%, respectively, at 400 RPM (p<0.001). Increasing RPM to 600 did not result in significant further reductions. The number of discernible peaks for torque (threshold: 0.3Nmm) and force (threshold: 0.2N) significantly decreased from 200 RPM to 400 RPM and did not decrease further with 600 RPM. We conclude that under the present experimental conditions, rotational speed had an impact on preparation with Vortex™ rotaries, with instruments at 400RPM generating less torque and force than at 200RPM.

e16 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 25Influence of Cross-Sectional Design on Cyclic Fatigue Resistance of ProTaper™ InstrumentsD.I.M. Al-Sudani*1, G. Plotino2, N. Grande2, G. Gambarini2

1King Saud University, Riyadh, Saudi Arabia, 2Rome, Italy

Objectives: To compare cyclic fatigue resistance of the old ProTaper™ F2 and the new ProTaper™ Universal F2 that is produced with a different cross-sectional design including less metal mass. Methods: Cyclic fatigue testing was performed in stainless steel artificial canals with a 5 mm radius of curvature and an angle of curvature of 60 degrees constructed to the dimensions of the instruments tested. The middle of the simulated curvature was 5 mm from the tip of the instrument that was placed at full working length. Twelve ProTaper™ F2 files of the previous version and 12 of the new version ProTaper™ Universal files (DENTSPLY Maillefer, Ballaigues, Switzerland) were rotated until fracture occurred and the number of cycles to failure (NCF) were recorded. Data were analyzed by one-way ANOVA test to determine any statistical difference between groups; the significance was determined at the 95% confidence level (p<0.05). Results: The new ProTaper™ Universal F2 showed significantly higher resistance to cyclic fatigue than the old ProTaper™ F2 (p<0.05). The old ProTaper™ F2 resisted fatigue for 72 ± 22 NCF and the new ProTaper™ Universal F2 resisted for 295 ± 22 NCF, which is 4 times more than the old version. Conclusions: The new ProTaper™ Universal F2 had significantly higher fatigue resistance compared to the old ProTaper™ F2, demonstrating that a cross-sectional design including less mass of metal increased the resistance to fracture of instruments that are identical in the other morphological characteristics.

OR 26Torsional Properties of New and Used Revo-S® Rotary Instruments: An In Vitro StudyB.R. Basrani*1, K. Roth1, G. Sas1, A. Kishen1, O. Peters2

1University of Toronto, ON, Canada, 2University of the Pacific, San Francisco, CA

Aim: The purpose of this in vitro study was to investigate the torsional profiles of new and used nickel-titanium Revo-S® rotary instruments. Methodology: Thirty new and 60 used instruments were tested for torsional fracture in three groups according to American National Standards Institute/American Dental Association specification #28. Instruments in Group 1 remained as unused control while the instruments in Group 2 and Group 3 were used 2 and 6 times, respectively, in simulated root canals. Analysis of variance with Bonferroni/Dunn’s post hoc test (α=0.05) was used to compare torque and angle of rotation at fracture between new and used instruments. Results: The angle of rotation at fracture decreased with increasing number of uses (Group 1 to Group 3). There was a significant difference in the angle of rotation at failure between unused instruments (Group 1) and used instruments (Groups 2 and 3). There was no significant difference between the maximum torques at fracture for new instruments when compared to used ones. Conclusion: The repeated use of Revo-S® rotary instruments significantly reduced the angle of rotation at fracture but did not produce significant change in the maximum torque at fracture.

OR 27Accumulated Hard Tissue Debris Levels in Mesial Roots of Mandibular Molars After Sequential Irrigation StepsF. Paque*, C. Boessler, M. ZehnderUniversity of Zürich Dental School, Zürich, Switzerland

Objective: To investigate the impact of sequential irrigation procedures on accumulated hard tissue debris (AHTD) levels in canal systems in mesial roots of human mandibular molars after instrumentation. Methods: Based on prescans in a microcomputed tomography system, 20 extracted human mandibular molars with joining mesial root canals and an isthmus between these of at least 2 mm were selected. Canals were instrumented using the ProTaper™ rotary system until the F3 instrument reached working length. A 1% NaOCl solution was applied during instrumentation, followed by a final 5 mL flush to working length. Subsequently, canals were irrigated with 5 mL of 17% EDTA. Thereafter, passive ultrasonic irrigation (PUI) was performed using 1% NaOCl for 3 times 20 sec. Percent values of total canal system volume filled with AHTD were calculated based on high-resolution scans after each irrigation step. Data was compared using repeated measure ANOVA followed by paired t-test for individual comparisons. Bonferroni’s correction was applied for multiple testing; the alpha-type error was set at 1%. Results: Instrumentation of the root canals in conjunction with 1% NaOCl irrigation left a 6.9 ± 4.2% of the total canal system volume filled with AHTD. This value was significantly (p<0.01) reduced to 4.9 ± 3.6 vol% after EDTA irrigation. Subsequent PUI resulted in a further significant (p<0.01) reduction to 3.7 ± 2.8 vol%. Conclusion: In this quantitative study on AHTD reduction, a significant effect of EDTA and PUI was shown. However, about half of the debris that was accumulated during instrumentation remained in the canal system.

OR 28Identification and Quantification of Microorganisms and Inflammatory Cytokines Following Traumatic InjuriesN.A. Morton*, K. Neiva, C.H. Varella, U. Nair, C. Walker, S. Wallet, R. PileggiUniversity of Florida, Gainesville, FL

Traumatic injuries are a common occurrence and may one day surpass the incidence of caries and periodontal disease. Inflammatory root resorption is one of the main sequelae associated with trauma and has the strongest negative effect on prognosis. One of the main causes of inflammatory root resorption is bacterial infection and its byproducts. To date, there is no study correlating the presence of bacteria and associated cytokines with the type of traumatic injuries. Therefore, the aim of this study was to characterize and quantify inflammatory cytokines and the microbiota present in dental pulp following trauma. Dental pulp fluid was collected from patients receiving root canal therapy after traumatic injury using PerioPaper® and paper points. Teeth extracted for orthodontic reasons were used as control. Cyto-/chemokine profile was determined using Milliplex® technology, which analyzes multiple cytokines in a single sample. Total genomic DNA was extracted and analyzed by real-time PCR. Representative species from common phyla identified in endodontic infections were analyzed: Enterococcus faecalis, Fusobacterium nucleatum, Tannerella forsythia and Treponema denticola. Results demonstrated that expression of IL6, IL8, IL10, IL1ß, MCP1, MIP1α and MIPß were upregulated in subluxation, lateral luxation and avulsion. Notably, MCP1 levels were higher in avulsion. Enterococcus faecalis, Fusobacterium nucleatum, Tannerella forsythia and Treponema denticola were present in subluxation and lateral luxation. Expression of Tannerella forsythia and Treponema denticola were absent in avulsed teeth. In conclusion, cytokines and bacteria have different expression levels and could play a role in the treatment of traumatic injuries.

e17JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 29Effect of the Combination of Preoperative Ibuprofen and Acetaminophen on the Efficacy of the Inferior Alveolar Nerve Block in Patients With Symptomatic Irreversible PulpitisM. Simpson*, M. Drum, J. Nusstein, A. Reader, M. BeckOhio State University, Columbus, OH

The inferior alveolar nerve (IAN) block does not always result in successful pulpal anesthesia. Previous studies have suggested that preoperative medication may increase the success rate of the IAN block, particularly a combination of preoperative ibuprofen and acetaminophen. Recent clinical studies found that giving only ibuprofen preoperatively did not significantly improve the success rate of the IAN block in patients with symptomatic irreversible pulpitis. The purpose of this prospective, randomized, double-blind, placebo-controlled study was to determine the effect of administration of a preoperative ibuprofen/acetaminophen combination on the efficacy of the IAN block in patients with irreversible pulpitis. One-hundred emergency patients diagnosed with irreversible pulpitis of a mandibular posterior tooth and experiencing moderate to severe pain randomly received identical capsules of either a combination of 800 mg ibuprofen and 1,000 mg acetaminophen or a placebo 45 minutes before the administration of a conventional IAN block. Access began 15 minutes after completion of the block and all patients had profound lip numbness. Success was defined as no or mild pain (visual analog scale recordings) on access or instrumentation. The success rate for the IAN block was 32% with the ibuprofen/acetaminophen group and 24% with the placebo group, with no significant difference (p = 0.37) between the two groups. In conclusion, for mandibular posterior teeth, a preoperative dose of a combination of 800 mg of ibuprofen and 1,000 mg of acetaminophen did not result in a statistically significant increase in success of the IAN block in patients with symptomatic irreversible pulpitis.

OR 30Efficacy of Ibuprofen and Ibuprofen/Acetaminophen on Postoperative Pain in Symptomatic Teeth With a Pulpal Diagnosis of NecrosisK. Wells*, M. Drum, J. Nusstein, A. Reader, M. BeckOhio State University, Columbus, OH

The purpose of this prospective, randomized, double-blind study was to determine ibuprofen versus ibuprofen/acetaminophen usage for postoperative endodontic pain in symptomatic patients with a pulpal diagnosis of necrosis, experiencing moderate-to-severe preoperative pain. Additionally, we recorded escape medication usage. Seventy-one adult patients presenting for emergency endodontic treatment with a symptomatic maxillary or mandibular tooth with a pulpal diagnosis of necrosis, a periapical radiolucent area and moderate to severe pain participated in this study. The patients were randomly divided into two groups blinded to both the doctor and patient by random assignment and numerical coding. An emergency debridement of the tooth was completed with hand and rotary instrumentation. At the end of the appointment, the patients were given either 600 mg ibuprofen or 600 mg ibuprofen combined with 1,000 mg acetaminophen (blinded to both the operator and patient). Patients also received a 6-day diary to be completed every morning for five days after anesthesia wore off. Patients were asked to record pain and symptoms and the number of pain medications taken. Patients received escape medication (Vicodin) if the study medication was not controlling their pain. Postoperative data was analyzed by Randomization Test and Step-down Bonferroni method of Holm. There were average decreases in pain levels and analgesic usage over time for the ibuprofen and ibuprofen/acetaminophen groups. There was no statistically significant difference between the two groups for analgesic usage or escape medication usage. Approximately 20% of patients in both groups required escape medication to control pain. The study was supported by the AAE Foundation.

OR 31Anesthetic Efficacy of 1.8 mL Versus 3.6 mL of 4% Articaine With 1:100,000 Epinephrine as a Primary Buccal Infiltration of the Mandibular First MolarM.J. Martin*, J. Nusstein, M. Drum, A. Reader, M. BeckOhio State University, Columbus, OH

No study has compared 1.8 mL and 3.6 mL of 4% articaine with 1:100,000 epinephrine in a mandibular buccal infiltration of the first molar. The authors conducted a prospective, randomized, single-blind, crossover study comparing the degree of pulpal anesthesia obtained with 1.8 mL and 3.6 mL of 4% articaine with 1:100,000 epinephrine as a primary infiltration in the mandibular first molar. Eighty-six asymptomatic adult subjects randomly received a primary mandibular buccal first molar infiltration of 1.8 mL or 3.6 mL of 4% articaine with 1:100,000 epinephrine, in two separate appointments. The authors used an electric pulp tester to test the first molar for anesthesia in 3-minute cycles for 90 minutes after the injections. Compared to the 1.8 mL volume of 4% articaine with 1:100,000 epinephrine, the 3.6 mL volume showed a statistically higher success rate (70% versus 50%). The anesthetic efficacy of 3.6 mL of 4% articaine with 1:100,000 epinephrine is better than 1.8 mL of the same anesthetic solution in a primary mandibular buccal infiltration of the first molar. However, the success rate of 70% is not high enough to support its use as a primary injection technique in the mandibular first molar.

OR 32A Prospective, Randomized, Single-Blind Study to Evaluate the Reversal of Soft Tissue Anesthesia in Asymptomatic Endodontic PatientsS. Fowler*, J. Nusstein, M. Drum, A. Reader, M. BeckOhio State University, Columbus, OH

OraVerse™ has been reported to be an effective local anesthetic reversal agent. The purpose of this prospective, randomized, single-blind study was to evaluate the reversal of soft tissue anesthesia in endodontic patients. Eighty-five adult subjects having a maxillary or mandibular asymptomatic tooth requiring endodontic treatment received either OraVerse™ or sham injection(s) at the end of treatment. Soft tissue anesthesia was monitored by subjects every 15 minutes for 5 hours. Subjects reported postoperative injection site and experimental tooth pain using a Heft-Parker visual analog scale every 30 minutes for the first two postoperative hours and every hour for three hours. There was a statistically significant difference in time to return to normal sensation for the maxillary lip/cheek and mandibular lip. Subjects who received OraVerse™ experienced an 88-minute decrease in time to return to normal maxillary lip/cheek sensation and a 47-minute decrease in time to return to normal mandibular lip sensation. There was a 27-minute decrease in time to return to normal tongue sensation for subjects in the OraVerse™ group which was not statistically significant from the sham group. Subjects who received OraVerse™ did not experience significantly more postoperative discomfort at the injection site or from the endodontically treated tooth. Postoperative complications were minimal and no adverse reactions to the OraVerse™ were reported. OraVerse™ may be beneficial for asymptomatic patients who would like to experience a faster return to normal soft tissue sensation after the administration of local anesthesia for endodontic treatment.

e18 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 33Integration of Immediate Implants Into an Endodontic PracticeM.K. Gopinathan*New York University, New York City, NY

Increasingly, single-tooth implants are being integrated into endodontic practices. Diagnosis and treatment planning considerations are essential components of this new approach. This presentation will focus on specific indications for immediate implant placement when endodontic treatment offers a hopeless prognosis. Clinical cases will be reviewed and discussed from both diagnostic and treatment planning stages using both intra-oral photos of implant placement, bone grafting, use of membranes and implant restoration will be demonstrated. Also discussed are contraindications to immediate implant placement.

OR 34A Clinical Evaluation Comparing Postoperative Pain After Obturation in Vital Pulp, Single-Visit With Resilon™ and Resilon™ Self-Etch SealerE.O. Oya*, M.A.H. FurtadoSão Paulo, Brazil

Resilon/Epiphany™ self-etch sealer was introduced in 2007 to simplify obturation by avoiding the primer step. The purpose of this study was to compare postoperative pain severity in vital pulps of single-visit patients between Resilon/Epiphany™ and Resilon/Epiphany™ self-etch Primer. Material and Methods: Eighty asymptomatic vital teeth from patients aged from 18 to 65 were performed in one appointment. Forty teeth were filled with Resilon/Epiphany™ sealer and 40 were filled with Resilon/Epiphany™ self-etch sealer. The instrumentation technique used was the Hybrid Technique with Crow-Down concept. Hand files used were Lexxicon™, Gates-Glidden™ burs and ProTaper™. The work length was determined with apical locator Root ZxII™; ( J. Morita, Irvine, CA). The irrigation protocol used was: NaOCl 2.5%, EDTA-T 17%, sterile water and Chlorhexidine 1% as final irrigation. Tagger Hybrid Obturation Technique were performed in both materials. Postoperative pain was categorized as follows: if a patient reported no or minimum pain and no analgesics were required, they were classified as Group 1: no pain. If the pain was defined as any discomfort and required a mild analgesic, they were classified as Group 2: mild pain. If the pain required a strong analgesic or severe pain was experienced on biting, they were classified as Group 3: severe pain. Chi-square test 0.5 and Yates’ Continuity Correction was used to determinate statistical significance. Results: Resilon/Epiphany™ sealer: No Pain: 9; Mild Pain: 25 and Severe Pain: 6. Resilon/Epiphany™ self-etch sealer: No Pain: 31; Mild Pain: 7 and Severe Pain: 2. Conclusion: A significantly higher postoperative pain (p<0.05) was found in Resilon/Epiphany™ sealer when compared with Resilon/Epiphany™ self-etch sealer.

OR 35Male and Female Preferences Regarding One-Visit Versus Two-Visit Endodontic TreatmentR.E. Walton*1, K. Vela1, D. Caplan1, M. Trope2

1University of Iowa, Iowa City, IA, 2University of North Carolina, Chapel Hill, NC

Controversy surrounds the optimal number of visits required for successful root canal treatment (RCT) of teeth with necrotic pulps and apical periodontitis. Objective: To compare male versus female patients’ attitudes regarding their preferred number of RCT visits, particularly as related to possible success rates. Hypothesis: Men would be more likely than women to prefer one-visit RCT. Methods: Self-administered surveys were mailed to consecutive patients scheduled for initial RCT appointments in the University of Iowa’s graduate or faculty endodontic clinic. The survey ascertained: 1) patient demographic information; 2) patient preferences for one- versus two-visit RCT given different hypothetical success rate scenarios for the two approaches; and 3) recent dental history. Univariate and bivariate frequency distributions were generated and relationships between sex and patient characteristics were evaluated. Results: As hypothetical success rates for two-visit RCT went from “5% better” to “10% better” to “20% better” than one-visit RCT, the percentage of patients favoring two-visit RCT increased from 34% to 46% to 65%, respectively. Across all three scenarios, the percentage of males who always preferred one-visit RCT was 11%, compared to 26% for females (p=0.032). Conclusions: Contrary to our hypothesis, men were less likely than women to prefer one-visit RCT; this was regardless of the possible difference in success rates between the two approaches. Overall, patient preferences were influenced by perceived treatment outcome. These findings underline the importance of discussing success rates and treatment approaches with patients prior to treatment initiation.

OR 36Presence/Absence of an Endodontic Specialty Program During Dental Education Compared to General Dentist Attitudes Toward Treating or Referring Patients Requiring Endodontic TherapyG.A. Carman1, K.H. Foster2, J.M. Morelli1, R. Caicedo1, S.J. Clark*1

1University of Louisville, KY, 2Knoxville, TN

The primary aim of this study was to compare the opinion of general dentists (GD) trained at schools with or without endodontic specialty programs (ESP) as to whether they would treat or refer to an endodontist patients requiring endodontics. A survey was electronically distributed to the members of the Kentucky Dental Association (KDA) using Surveygizmo®. GD were asked their gender, dental school, graduation year and whether they (1) would treat the patient, (2) refer the patient or (3) were neutral for a list of 18 endodontic procedures or problems. Presence/absence of an ESP during dental education and number of years of practice were calculated from the data provided. Odds ratio was used to assess statistical significance. Surveys were distributed to 955 members of the KDA. 230 dentists (24%) responded with 191 GD completing the survey. 92 (48.2%) trained at a school without an ESP and 95 (49.7%) trained at a school with an ESP. Dentists trained at a school without an ESP were more likely to treat rather than refer (1) calcified canals (23.9% vs. 9.5%, p = .017); (2) significantly curved canals (28.3% vs. 9.5%, p = .001); (3) anterior periapical surgery (16.3% vs. 6.3%, p = .037); and (4) traumatic injuries such as avulsion (52.2% vs. 34.7%, p = .019). The results of this study indicate the presence or absence of an ESP during a student’s dental education may influence subsequent clinical decisions to refer to an endodontist or to treat patients requiring endodontic therapy.

e19JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 37Proximity of the Mandibular Canal to the Root ApexW.R. Bowles*, T. Koivisto, M. AhmadUniversity of Minnesota, Minneapolis, MN

Knowledge of the inferior alveolar nerve (IAN) position is important to avoid nerve damage during invasive dental procedures. As the exact position of the nerve bundle can vary in patients, this study evaluated the distance from the apices of mandibular premolar and molar teeth to the superior border of the mandibular canal. Cone-beam-computed tomography (CBCT) scans from 139 patients were analyzed to evaluate the proximity of the mandibular canal to the root apices of 743 mandibular 2nd premolar and 1st and 2nd molar teeth. Subjects were subgrouped by age and sex. A random intercept model was used to account for multiple measurements (R, L) within a patient. In all groups, root apices of the mandibular 2nd molars were closer to the mandibular canal than other teeth. The mesial root of the 2nd molar was closer to the nerve in female patients compared to males. Root apices in younger patients (<18 years) were generally closer to the mandibular canal than in older patients. The CBCT scan is an accurate, noninvasive method to evaluate the position of the mandibular canal. The variable position of this structure between patients suggests the need for CBCT to determine the proximity of the nerve bundle before invasive treatment in this area. Dental practitioners should consider potential differences of mandibular canal position due to age and sex differences.

OR 38The Influence of Endodontic Infection on the Initial Damage to the Cardiovascular SystemC. Dettori*, C. Dessì, A. Piras, G. Flore, G. Mercuro, E. CottiCagliari, Italy

Introduction: Dental infections may represent a favorable background for atherosclerosis and cardio vascular disease (CVD). Only a few studies have investigated the possible correlation between apical periodontitis (AP) and CVD. The purpose of our study (first part of a cumulative project) is to assess the influence of endodontic infection on the initial damage to the cardiovascular system. Hypothesis: The subjects who are suffering from AP in the absence of other risk factors are more exposed to the pathogenetic mechanisms of the atherosclerotic lesion. Materials and Methods: In this first study we selected 40 healthy male patients aged 20-40 exhibiting no other risk factors for CVD; 20 had AP (study group) and 20 were the control group. The inquiry procedures were dental examination, standard echocardiography and tissue Doppler; the parameters analyzed were ESR, CRP, Fibrinogen, Citokines and ADMA (Asymmetrical-Dymethylarginine). The results were analyzed using the two-tailed Student’s t-test. Results: There was a statistically significant increase in the blood levels of IL1, IL2, IL6, TNF (P<0.05) and of ADMA (p<0.005) in the study group. Discussion and Conclusions: The increased serum levels of cytokines and ADMA in patients with AP can be considered the beginning of an increased risk of developing future CVD. Elevated plasma levels of ADMA are a contributory factor to endothelial dysfunction and insulin resistance and may be responsible for the onset of atherogenic processes.

OR 39Reinforcement of Simulated Immature Roots Filled With Composite, MTA, Gutta-Percha or a Fiber Post After ThermocyclingS.J. Schmoldt*, T.C. Kirkpatrick, J.M. Yaccino, R.E. RutledgeWilford Hall U.S.A.F. Medical Center, San Antonio, TX

The purpose of this study was to evaluate the fracture resistance of simulated immature teeth restored with either a fiber-reinforced composite core build-up material (Build-It® FR™) with or without a fiber post (FibreKor®), Mineral Trioxide Aggregate (MTA), a dual-cured, fluoride-releasing, composite core build-up material (FluoroCore® 2+), or gutta-percha (GP) after thermocycling. Eighty-four primary bovine mandibular incisors were divided into seven groups of 12 teeth each. Negative controls received no treatment. Teeth in all other groups were prepared to an internal diameter of 1.75 mm with LightSpeed LSX™ instruments and ParaPost® drills. After placement of a 4 mm apical barrier of MTA, the canals were filled with their respective test materials to the facial CEJ. For the fiber post group, a 1.375 mm diameter FibreKor® post was fitted to extend from the MTA barrier to 2 mm below the incisal edge and was cemented with Build-It® FR™. The positive controls were left unfilled. The access openings were filled with BisFil™ II composite. All teeth were then thermocycled for 500 cycles at 5°C and 55°C with a 30-second dwell time and five-second transfer time. Each root was then horizontally fractured through the test material using an Instron Universal Testing Machine and the peak load to fracture was recorded. The data was analyzed with ANOVA and Tukey post hoc tests (p<0.05). Thermocycled composite was not significantly stronger than GP and MTA. The only material that significantly strengthened the simulated immature teeth was the fiber-reinforced composite with a fiber post.

OR 40Setting Properties and Cytotoxicity Evaluation of a Premixed Bioceramic Root Canal SealerB.A. Loushine*, T.E. Bryan, S.W. Looney, B.M. Gillen, R.J. Loushine, R.N. Weller, F.R. TayMedical College of Georgia, Augusta, GA

This study investigates the setting time and hardness of a premixed calcium silicate-based sealer (BC Sealer™, Brasseler USA, Savannah, GA) in the presence of different moisture contents (0-9 wt%). Additionally, the cytotoxicity of BC Sealer was compared with an epoxy resin-based sealer (AH Plus™, DENTSPLY Caulk, Milford, DE). The moisture content that produced the most optimal setting properties was employed to prepare set BC Sealer™ for cytotoxicity evaluation. Standardized samples of BC Sealer™ were created along with AH Plus™, Pulp Canal Sealer™ (SybronEndo, Orange, CA) as the positive control and Teflon as the negative control. Samples were placed in transwell inserts, providing indirect contact with MC3T3-E1 cells. Succinate dehydrogenase activity of the cells was evaluated over a six-week period using MTT assay. The cytotoxicity profiles of BC Sealer™ and AH Plus™ were fitted with cubic polynomial regression models. Half-lives for 50% of the cells to survive (T0.5) were statistically analyzed using the Wald method with a two-tailed significance level of 0.05. Knoop hardness testing showed that BC Sealer™ did not have an accelerated setting time when moisture was added and required over 24 h to reach initial setting. Cytotoxicity of AH Plus™ gradually decreased over the six-week period and became noncytotoxic while BC Sealer™ remained moderately cytotoxic. Significant difference (p<0.001) was detected between T0.5 of BC Sealer™ (5.10 weeks; 95% CI 4.69-5.42, S.E. 0.09) and T0.5 of AH Plus™ (0.86 weeks; 95% CI 0.68-1.05, S.E. 0.18). Delayed setting of the BC Sealer™ may allow the release of toxic byproducts over an extended period of time. This study was supported by the AAE Foundation and the Department of Endodontics, Medical College of Georgia.

e20 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 41Alkalized Sodium Hypochlorite: Effects on Soft Tissue and DentinH. Jungbluth*1, M. Marending1, G. De-Deus2, B. Sener1, M. Zehnder1

1Zürich, Switzerland, 2Rio de Janeiro, Brazil

Introduction: Sodium hypochlorite solutions contain different species of chlorine, depending on pH. OCl, which predominates in an alkaline environment, could have a higher proteolytic effect than HOCl. We studied an alkalized 5% NaOCl solution regarding its soft tissue solubilization and effects on mechanical dentin properties. Methods: NaOCl solutions were prepared by mixing (1:1) a 10% stock solution with water (standard) or 2 M NaOH (alkalized solution). Physiological saline and 1 M NaOH served as controls. Chlorine content and alkaline capacity of NaOCl solutions were determined. Standardized porcine palatal soft tissue specimens and human root dentin bars were exposed to test and control solutions for 8 and 30 min, respectively. Weight loss in percentage was assessed in the soft tissue dissolution assay. Three-point bending tests were performed on the root dentin bars to determine modulus of elasticity and flexural strength. Values between groups were compared using one-way analysis of variance (ANOVA) with Bonferroni’s correction for multiple testing (α<0.05). Results: Both solutions contained 5% NaOCl. The standard solution consumed 37.5 mL of a 0.1 M HCl solution before it reached pH 7.5, the alkalized counterpart 140 mL. The alkalized NaOCl dissolved significantly more soft tissue than the standard solution. It also caused a higher loss in elastic modulus and flexure strength (p<0.05) than the control solutions, while the standard solution did not. Conclusion: Alkalized NaOCl solutions appear to be more proeteolytic than standard counterparts.

OR 42Physicochemical Properties of Root Canal Sealers Mixed With AmoxicillinS.D. Shwedel*, K. Namerow, R.J. Seltzer, P.E. Murray, M.A. MarchesanNova Southeastern University, Fort Lauderdale, FL

The addition of amoxicillin (AMX) to root canal sealers can enhance their antimicrobial efficacy, but the physicochemical changes are unknown. This study evaluated the effect of AMX on the physicochemical properties of Pulp Canal Sealer™ (SybronEndo, Orange, CA), AH Plus™ (DENTSPLY International, York, PA) and Real Seal SE™ (Pentron Clinical Technologies LLC., Wallingford, CT). Setting time and flow rate were measured according to the American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57 guidelines. The sealers (n=54) were mixed according to manufactures instructions. AMX (10% of the sealer’s total weight) was added to half the samples. Statistical analysis was performed by using Analysis of Variance and Tukey-Kramer tests at a significance of p<0.05. The addition of AMX to Pulp Canal Sealer increased the setting time from 58.3min ± 2.9 to 281.66 ± 6.4 with AMX (p<0.05) and decreased the setting time of AH Plus™ cement from 703.6 min ± 12.2 to 323 min ± 15.2 with AMX (p<0.05). It also decreased the flow rate of both cements (Pulp Canal Sealer™: from 63.3mm ± 0.5 to 36.6mm ± 1.2 with AMX and AH Plus™: from 36.3mm ± 0.7 to 23.2mm ± 0.6 with AMX; p<0.05). The physicochemical properties of Real Seal SE™ were not influenced by the addition of AMX (p>0.05). The addition of AMX to some sealers can change their physicochemical properties. The change in physicochemical properties caused by AMX is dependent on the chemistry of the sealer. Further research is needed to fully elucidate the clinical benefits and disadvantages of adding AMX to sealers. This study was supported by NSU Health Professions Division.

OR 43Comparison of Vertical Force Resistance Between EndoSequence™ Root Repair Material and Mineral Trioxide Aggregate at Various Setting TimesJ.M. Nelson*, S. Sidow, K. McNally, K. LindseyU.S. Army Dental Activity, Fort Gordon, Augusta, GA

Introduction: EndoSequence™ Root Repair Material (ESRRM) is a newly developed material marketed to accomplish the same goals as its competitor, Mineral Trioxide Aggregate (MTA). Evidence-based literature supports the use of single-visit apexification using MTA. To date, there is minimal research supporting ESRRM as an effective material for single-visit apexification. The ability of MTA and ESRRM to withstand obturation forces immediately after placement is a concern. This study evaluated and compared the ability of white MTA (WMTA) and ESRRM to resist vertical forces at various setting times. Materials and Methods: A standardized open-apex model was created in acrylic blocks to simulate open-ended canals. Samples of ESSRM and WMTA were divided into 6 test groups (n=10) with different setting times (5, 15 and 30 minutes; 2 and 24 hours). Materials were mixed, placed into canals and subjected to a universal testing machine (Instron®) after defined setting times. The maximum force required to penetrate the material 1.0 mm was recorded and compared. Results: The 5, 10, 15 and 30-minute ESRRM groups did not withstand significant vertical forces; WMTA withstood 7, 9, 13 and 22 MPa, respectively. ESRRM withstood 18 and 100 MPa after 2 and 24 hours. WMTA withstood 55 and 67 MPa after 2 and 24 hours. Conclusion: WMTA resisted more vertical force at all time intervals prior to 2 hours when compared to ESRRM.

OR 44Blockade of TLR2 Inhibits P. Gingivalis Suppression of Mineralized Matrix Formation by Human Dental Pulp Stem CellsV. Tom-Kun Yamagishi*1, C. Torneck1, S. Friedman1, G. Huang2, M. Glogauer1

1University of Toronto, ON, Canada, 2Boston University, Boston, MA

Introduction: To regenerate tissue with odontogenic potential in the pulp space of immature infected teeth, human dental pulp stem/progenitor cells (hDPSCs) may be stimulated to form mineralized matrix, marked by high expression of dentin sialophosphoprotein (DSPP) and osteocalcin (OCN). Residual bacterial byproducts in the root canal may suppress this activity. Purpose: This study investigated the effect of P. gingivalis byproduct on expression of DSPP and OCN by stimulated hDPSCs, and the influence of blockade of TLR2-mediated P. gingivalis host recognition. Methods: Stimulated hDPSCs were exposed to varying concentrations of P. gingivalis LPS and expression of DSPP and OCN was measured. Stimulated hDPSCs were exposed to TLR2 blocking agents prior to exposure to LPS and expression of DSPP and OCN was measured. Results: hDPSCs exposed to 5, 10 and 20 µg/ml LPS exhibited a dose-dependent reduction in expression of DSPP and OCN. Expression DSPP and OCN after exposure to 20 µg/ml of LPS were significantly lower than unexposed stimulated cells (P<0.05) using ANOVA and post hoc Tukey tests. Blockade of TLR2 using an extra- and intracellular agent affected DSPP (4.67 ± 0.97, and 5.29 ± 1.66, respectively) and OCN (5.25 ± 1.69, and 5.82 ± 2.38, respectively) expression at levels comparable to stimulated cells unexposed to 20 µg/ml LPS (6.62 ± 2.09). Conclusion: The suppressing effect of P. gingivalis byproduct on the potential of hDPSCs to form mineralized matrix and can be moderated by TLR2 blockade. This study was supported by the Canadian Academy of Endodontics, University of Toronto Faculty of Dentistry Dental Research Institute and Alpha Omega Research Foundation.

e21JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 45Inhibition of Endogenous Dentin Matrix Metalloproteinases by Ethylenediaminetetraacetic AcidJ.M. Thompson*1, K. Agee2, S.J. Sidow1, K. McNally1, K. Lindsey1, J.L. Borke2, M. Elsalanty2, F.R. Tay2, D.H. Pashley2

1U.S. Army Dental Activity, Fort Gordon, Augusta, GA, 2Medical College of Georgia, Augusta, GA

Endogenous dentin matrix metalloproteinases (MMPs) contribute to extracellular collagen matrix degradation in pathologic processes and in hybrid layer degradation following restorative dentin bonding procedures. Ethylenediaminetetraacetic acid (EDTA) is currently used for removal of the inorganic portion of the smear layer. EDTA may chelate zinc and calcium ions from MMPs and thereby alter their 3-D conformation and inactivate their activities. The objective of the present study was to determine the exposure time necessary for EDTA to inactivate endogenous MMP activity in human dentin. Dentin beams (2.0 x 1.0 x 3.0 mm) were prepared from mid-coronal dentin of noncarious extracted third molars. The beams were demineralized in 10 wt% phosphoric acid and divided into four experimental groups based on exposure time to 500 mM (17%) EDTA for 0, 1, 2 or 5 min. Mineralized dentin beams served as negative controls, and demineralized beams not exposed to EDTA were used as positive controls. A generic colorimetric MMP assay measured MMP activity via absorbance at 420 nm. Data was evaluated by one-way ANOVA and pair-wise comparisons by Tukey-Kramer test at α=0.05. Exposure times of 2 and 5 min resulted in significant inhibition of MMP activity compared to non-EDTA-exposed beams (p<0.05), whereas 1 min exposure did not result in significant inhibition. EDTA at 17% concentration significantly inhibits endogenous MMP activity of human dentin which may minimize hybrid layer degradation following resin bonding procedures. Thus, EDTA has therapeutic properties beyond its ability to demineralize dentin smear layers. This study was supported by a National Institute of Dental and Craniofacial Research grant.

OR 46Effects of Inflammatory Cytokines on Odontogenic Differentiation of Dental Mesenchymal Stem CellsC.L. Chung*, S. Mehrazarin, J. Oh, R. Kim, M. KangUniversity of California at Los Angeles, CA

Dental mesenchymal stem cells (dMSCs) may differentiate into odontoblast-like cells to form mineralized tissues in cases of tooth injury and healing. We recently reported that dMSCs undergo replicative senescence and lose their odontogenic differentiation potential. Our recent studies also demonstrate that senescent dMSCs produce large quantities of inflammatory cytokines. Here, we report analyses of phenotypic effects of inflammatory cytokines on dMSCs. Rapidly proliferating dMSCs were cultured with or without inflammatory cytokines, such as interleukin IL-1ß IL-8 or tumor necrosis factor TNF-α. Since transforming growth factor (TGF-ß) is also crucial for dental tissue inflammation and repair, dMSCs were also exposed to TGF-ß alone or in combination with the cytokines. We determined the replication kinetics, cellular morphology, and odontogenic differentiation and mineralization capacities. Exposure of dMSCs to IL-1ß or TNF-α led to significant increase in cell proliferation, while IL-8 had no such effect. The cells maintained the viable and spindle-shape morphology under all cytokine treatments. On the contrary, odontogenic differentiation and mineralization, as revealed by alkaline phosphatase (ALP) activity and Alizarin Red staining respectively, were markedly reduced in cells exposed to IL-1ß or TNF-α, while IL-8 treatment showed no effect. TGF-ß treatment alone yielded moderate reduction of ALP activity, and it triggered no additional phenotypic effects when co-treated with the inflammatory cytokines. These data suggest that inflammatory cytokines, IL-1ß and TNF-α may be responsible for the impaired odontogenic differentiation of dMSCs during pulpal and periradicular disease progression.

OR 47Characterization of Subpopulations of Dental Pulp Stem CellsM.A.I. Al-Habib*, G.T.J. HuangBoston University, Boston, MA

Advancements in stem cell biology have enhanced our understanding of tissue homeostasis, especially its repair and regeneration potential, which has been the fundamental underpinning for regenerative medicine. The discovery of human dental pulp stem cells (hDPSCs) has opened a new page for pulp biology. Not only are hDPSCs capable of self-renewal and forming pulp-/dentin-like tissues, they also possess multi-lineage differentiation potential, including osteogenic, adipogenic, chondrogenic and neurogenic. hDPSCs, like other mesenchymal stem cells (MSCs), are heterogeneous populations of stem/progenitor cells carrying various markers that possess different stem cell properties, including their self-renewal and differentiation capacities. This study was aimed to detect hDPSC subpopulations at the initial seeding of cells when they are released from pulp tissues before passaging. Human dental pulps were extracted from teeth of healthy subjects aged 16-25 years. hDPSCs colonies (<50 cells per colony) at passage 0 were immunocytostained after one week of their initial seeding. These colonies showed positive staining for Stro-1, CD73, CD90, CD105, CD146, Sox2 and Nanog. hDPSC were then expanded and at passage 2 were subjected to flow cytometry analysis with double staining for Stro-1 and CD markers (CD73, CD90, CD105 or CD146). The percentages of the double positive subpopulations were Stro1+CD73+, 54.7%; Stro1+ CD90+, 56.4%; Stro1+ CD105+, 48.8% and Stro1+ CD146+, 11.2 %. The data indicate that approximately half of the cell population are Stro1+/CD73+, CD90+ or CD105+, while only ~10% are Stro1+ CD146+, suggesting the need to study these subpopulations separately for their stem cell properties. This study was supported by the AAE Foundation and the National Institutes of Health.

OR 48Evaluation of C-fos Expression in the Brainstem After Cold Stimulation of the Dental PulpY.F. Chiu*, J. Melnyk, J.L. GibbsUniversity of California at San Francisco, CA

Objective: The transient receptor potential melastatin 8 (TRPM8) receptor is activated by the chemicals menthol and icilin and mediates innocuous and noxious cold. However, the role of TRPM8 in mediating noxious cold pain in pulpal neurons has yet to be assessed. The purpose of this study was to develop an assay to measure nociceptor processing of noxious cold sensitivity in the dental pulp of mice. This will further allow us to determine the molecular transducers of noxious cold pain in pulpal nociceptors, such as TRPM8. Materials and Methods: Under anesthesia, the occlusal surface of maxillary left first molars was stimulated with Endo-Ice® twice at 2.5-minute intervals for a 30-minute period. Cold-evoked c-fos expression was evaluated using immunocytochemical techniques and quantified by an observer blinded to treatment allocation. The unstimulated contralateral side served as control. The anatomical location (caudalis, transition zone, interpolaris, oralis) of neuronal populations within the trigeminal nucleus that responded to noxious stimulation was visualized and quantified. Two-tailed unpaired t-test was used for data analysis. Results: Repeated cold stimulation of the mouse molar resulted in a 50% increase in c-fos expression on the ipsilateral side in the trigeminal nucleus, particularly in the transition zone between the caudalis and interpolaris (p<0.05). Conclusion: We have developed an assay to evaluate nociceptor function in transducing noxious cold stimulation of pulpal neurons. We can now evaluate the function of potential molecular mediators of noxious cold such as the TRPM8 receptor using knock-out mice. This study was supported by the AAE Foundation.

e22 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 49Relationship Between Periapical Lesion Size and the Development of Atheromatous Plaques in a Murine Atherosclerosis ModelT.C. Blattner*, J.R. Revand, R. Nandakumar, A.F. FouadUniversity of Maryland, Baltimore, MD

Chronic infection is thought to initiate a chronic inflammatory response leading to the development and progression of atherosclerosis. The aims of this study were: 1) determine if atheromatous plaques were larger in atherosclerosis-susceptible mice with periapical lesions than those without periapical lesions; 2) determine if periapical lesion size correlated with the degree of atheromatous plaque formation. Two main groups of Apo E-/- mice were analyzed. In Group 1, access openings were made in mandibular first molars and polymicrobial suspension was placed intraorally biweekly for 24 weeks. Group 2 animals had no exposure but were followed for the same period. Additional positive (IV inoculation—Group 3) and negative (pulp exposures without inoculations—Group 4) controls were used. Animals used were housed in sterile conditions, and received oral antibiotics gavage for three days prior to experimentation. After euthanasia, the left mandibles were processed and stained using H&E. The aortic arches were dissected and Oil Red O staining was performed on atheromatous plaques. Analysis of the average plaque size measured in μmol Oil Red O/μg protein revealed that in Group 1, atheromatous plaques were significantly larger than Groups 2 and 4 and not different from Group 3 (ANOVA, p=0.003). Pearson correlation using ORO protein data and lesion area in μm2 at the animal level showed a significant correlation (r = 0.88; p=0.002) between Groups 1 and 2. Exposure to endodontic pathogens and increased periapical lesion area both appear to correlate with an increase in size of atheromatous plaques. This study was supported by the AAE Foundation.

OR 50Cyclic Fatigue Resistance of Reciprocating and Conventional NiTi Endodontic InstrumentsN.M. Grande*, G. Plotino, V. Vincenzi, G. Gambarini, L. TestarelliRome, Italy

New reciprocating nickel-titanium instruments have been recently introduced in the market, designed to be used with a patented reciprocating motion (Reciproc™, VDW-GmbH, Munich, Germany), that makes 10 alternations per second (approx. 300 clockwise and 300 counterclockwise partial rotations per minute). This study aimed to compare the cyclic fatigue resistance of Reciproc™ files used with the patented reciprocating motion with conventional nickel-titanium rotary files used in continuous rotation (300 rpm). The following groups were tested: Reciproc™ R25, tip size #25 and variable taper (.08 apical taper, decreasing coronally), Mtwo™ (VDW-GmbH, Munich, Germany) tip size #25 taper .07 and ProTaper™ F2 (DENTSPLY Maillefer, Tulsa, OK). Ten instruments of each group were driven until fracture using a cyclic fatigue device with a 60° angle of curvature and a 5 mm radius. Time to fracture in seconds was registered. Mean values and standard deviations (SD) were calculated. Data were analyzed by one-way ANOVA and Tukey HSD test. Reciproc™ R25 fractured after a mean of 130 seconds (SD 15,7) while Mtwo™ after 101 sec (SD 12,4) and ProTaper™ after 58 sec (SD 11,2). There were statistical significant differences among all the groups (p<0.05). Since Reciproc™ files are very similar in cross-sectional and flute design to Mtwo™ and very similar in dimensions to ProTaper™, the influence of the reciprocating movement on cyclic fatigue resistance measured in seconds seems to be significant. This could be a relevant clinical issue, if time of instrumentation needed to complete root canal shaping by Reciproc™ is similar to those of conventional nickel-titanium instruments used in continuous rotation.

OR 51Work Hardening of NiTi Rotary Files Determined by NanoindentationJ. Mitchell, M. Wang, T. Svec*Oregon Health & Science University, Portland, OR

Rotary NiTi files when tested after clinical or simulated use should show evidence of what is presumed to be work hardening. This is noted in their significantly reduced resistance to fatigue as well as torsional moment at failure. However, the files are not compared with themselves but with an unused file of the same size. 0.04 taper ISO size 30 25 mm ProFile™ (n=12) were rotated in a stainless steel tube with a 90° curve and a radius of curvature of 5 mm at 300 RPM until failure. Nanoindentation was done immediately adjacent to the fracture site and at > 50 µm from the fracture site to determine any changes in hardness reported in GPa. Differences between the means were analyzed by one-way ANOVA and a post hoc Tukey test at a significance level of p<0.05. Three samples were lost to analysis. They could not be indented due to rollover of the fracture surface. Overall hardness (n=9) < 10 µm from fracture site was 6.86 ± 1.44 GPa. Overall hardness at > 50 µm from the fracture site was 4.85 ± 1.18 GPa. These results were significant at p=0.0001. Nanoindentation was able to detect a change in hardness on the same file.

OR 52Antibacterial Effect of a Novel Root Canal IrrigantS. Stojicic*, Y. Shen, M. HaapasaloUniversity of British Columbia, Vancouver, BC, Canada

This study was aimed to assess the efficacy of a novel root canal irrigant against Enterococcus faecalis and mixed plaque bacteria in planktonic phase and biofilms. In addition, its effect on smear layer was examined. E. faecalis and plaque bacteria were suspended in water and exposed to Qmix (pH=7.5), 2% Chlorhexidine and MTAD for 5 sec, 30 sec and 3 min. Following the exposure, samples were taken, serially diluted and grown aerobically and anaerobically on Tryptic soya agar (TSA) plates or on blood agar plates for 24 and 72 hours. A clinical strain of E. faecalis and plaque biofilms were grown for three weeks on collagen-coated hydroxyapatite (CHA) discs. The biofilms were subjected for 1 and 3 minutes to Qmix, 2% CHX and MTAD. Killing of bacteria was analyzed by confocal microscopy (CLSM) using viability staining. Smear layer removal by the three irrigants was assessed by SEM. Qmix was the most effective solution against planktonic E. faecalis and plaque bacteria, killing all bacteria in 5 sec. CHX and MTAD required more than 30 sec and 3 min to kill plaque bacteria or E. faecalis, respectively. Qmix was superior also in killing biofilm bacteria killing 4-12 times more bacteria than CHX and MTAD at one and three min. Qmix and 17% EDTA were equally effective in smear layer removal, and more effective than MTAD. Qmix was superior to CHX and MTAD in killing planktonic and biofilm bacteria. It also removed smear layer equally well or better than EDTA or MTAD. This study was supported by the Faculty of Graduate Studies University of British Columbia, the Ministry of Advanced Education British Columbia and the Joseph Tonzetich Foundation.

e23JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 53In Vivo Efficacy of Three Different Endodontic Irrigation Systems for Irrigant Delivery to the Apical Third of Mandibular Molars’ Mesial CanalsH.R. Munoz*, K. Camacho CuadraGuatemala City, Guatemala

Many in vitro studies have debated over the ability of different irrigant delivery and/or agitation systems to reach the apical third of root canals; however, little is known about irrigant penetration in vivo. Therefore, the purpose of this study was to compare the efficacy of the Monoject™ syringe, the IrriSafe™ ultrasonic tip and the EndoVac™ system for irrigant delivery into the apical third of mesial canals of mandibular molars. Thirty mesiolingual canals of mandibular first or second molars were randomly assigned into 3 groups (n=10): I) Monoject™ syringe, II) IrriSafe™ ultrasonic tip and III) EndoVac™ system. All canals were treated following the same preparation protocol using 5.25% NaOCl as irrigant during preparation procedure. Prior to canal obturation, 1 ml of a radiopaque solution (Omnipaque™) was placed in the canal using the assigned irrigation system and a digital radiograph was taken using parallelism technique. With the aid of computerized software for image management, distance between working length and maximum irrigant penetration was measured. Mean distances for Monoject™, IrriSafe™ and EndoVac™ groups were 1.51 mm, 0.21 mm and 0.42 mm, respectively. ANOVA test showed statistically significant differences between groups (p<0.001). Tukey HSD test showed statistically significant differences between the Monoject™ group and the other 2 groups (p<0.001), but no significant differences between IrriSafe™ and EndoVac™ groups (p=0.06). It can be concluded that Irrisafe™ and EndoVac™ systems are more effective than Monoject™ syringe in delivering irrigant into the apical third of root canals.

OR 54Bending Properties of NiTi Rotary Instruments Used for Extended Apical EnlargementG. Gambarini*1, D. Omar2, A. Carrillo Varguez3, N.M. Grande1, G. Plotino1, V. Vincenz1, L. Testarelli1

1Rome, Italy, 2Riyadh, Saudi Arabia, 3Tijuana, Mexico

Despite nickel-titanium (NiTi) superlastic properties, flexibility of NiTi rotary instruments is limited by size and taper. This can lead to increased risks of iatrogenic errors (i.e., apical transportation and/or weakening of the root), especially in curved canals, when instruments of greater tapers are used for extended apical enlargement (size 40 or more). The aim of the present study was to compare the bending properties of NiTi instruments of tip 40 and taper 04 of the following five commercially available brands: TF™ (SybronEndo, Orange, CA), EndoSequence™ (Brasseler USA, Savannah, GA), Vortex™, GTX™ and ProFile™ (DENTSPLY Tulsa Dental Specialties, Tulsa, OK). Ten instruments of each brand were tested. Experimental procedures strictly followed testing methodology described in ISO 3630-1. Bending moment was measured when the instrument attained a 45° bend. Data were collected and statistically analyzed (ANOVA and Tukey HSD). Results showed that TF™ were the most flexible instruments (mean values 29 gm/cm), followed by EndoSequence™ (51 gm/cm), Vortex™ (68 gm/cm), GTX™ (103 mr/cm) and ProFile™ (110 gm/cm). Except between ProFile™ and GTX™, statistically significant differences (P < .05) were found when comparing between instruments. The improvement in flexibility shown by TF™ can be influenced both by the instrument’s cross-sectional design and by the unique manufacturing process with proprietary thermal treatments of the alloy. This study was supported by an University Grant from SybronEndo.

OR 55Effects of Treatment Factors and Residual Microbial DNA on Endodontic Treatment Outcomes at Two YearsA.W. Orgel*1, P. Chand1, M.L. Hicks1, R. Nandakumar2, S.M. Barbuto3, B.J. Paster3, A.F. Fouad1

1University of Maryland, Baltimore, MD, 2University of Nebraska, Lincoln, NE, 3Boston, MA

Objectives: To determine the relationship between residual root canal bacteria and changes in periapical radiographic status following two-year follow-up determined using sensitive molecular techniques. Methods: Specimens were obtained from 50 patients presenting with pulp necrosis and a periapical lesion, following two-visit treatment using contemporary chemomechanical preparation techniques. PCR with broad range 16S rDNA bacterial primers was performed. Reaction products were cloned into pCR 2.1-TOPO TA vector and transformed into E. coli One-Shot TOP10. Clonal DNA was purified and sequenced for identification. Sequences <99% similarity with published sequences were excluded. Radiographs taken at 1 and 2 years using polyvinylsiloxane stents were independently scored by two calibrated endodontists. A consensus PAI determined periapical status. Results: Overall, 33 patients presented for follow-up at two years ± 2 months. Twenty-one (64%) healed (PAI: <3), 2 were deemed healing and 12 did not heal. Postoperative specimens contained no detectable bacteria in 15 cases, 13 of which (87%) healed versus 8/18 (44%) of cases with detectable bacteria (Fisher’s Exact, p=0.014). Significantly fewer numbers of different phylotypes were found in healed cases (unpaired t-test, p=0.011). Two phylotypes were associated with nonhealed cases; Enterococcus casseliflavus Oral Taxon 801 and Exiguobacterium aurantiacum (Fisher’s exact, p=0.018 and 0.035, respectively). Teeth obturated precisely to the radiographic apex were more likely to heal and less likely to have detectable bacteria than under/overfilled cases (Fisher’s Exact, p=0.086 and p=0.013, respectively). Conclusions: Using sensitive molecular techniques allowed a reasonable prediction of residual bacterial DNA and treatment outcomes at 2 years.

OR 56Maxillary Sinus Mucositis Associated With Apical Periodontitis of Maxillary Teeth: A Cone-Beam-Computerized Tomography Pilot Study of its Resolution After Endodontic TreatmentB. Nurbakhsh*, S. Friedman, B. Basrani, G. Kulkarni, E. LamUniversity of Toronto, ON, Canada

Problem: Apical periodontitis (AP) is an inflammatory response that can affect adjacent structures such as the maxillary sinus. Objective: This study characterized maxillary sinus mucositis (SIMS) adjacent to teeth with AP and assessed its resolution 3 months after endodontic treatment. Methods: Twenty-nine subjects with AP affecting maxillary posterior teeth were imaged with CBCT. Twenty-five subjects who met inclusion criteria had their maxillary sinuses inspected for presence of SIMS. Any observed SIMS was characterized for thickness and distance from apices of roots with AP before endodontic treatment was provided. Three months post-treatment, resolution of SIMS was assessed with CBCT. Six months post-treatment, periapical healing was assessed using the Periapical Index (PAI). Results: In 14/25 (56%) of subjects with SIMS, a nonsignificant inverse association was observed between the mucosal thickness and the distance from the sinus to root apices with AP. Four noncompliant subjects were discontinued prior to follow-up. Three months post-treatment, SIMS was resolved in 3/10 subjects (30%), unchanged in 6/10 subjects (60%) and expanded in 1/10 subjects (10%). Six months post-treatment, 6/9 subjects (67%; one subject dropped out) had reduced PAI scores indicating healing. The subject with expanded SIMS at 3 months was not healing at 6 months. Conclusions: Within the limited sample of this pilot study, CBCT revealed a lower-than-expected prevalence of maxillary sinus mucositis adjacent to teeth with AP. Resolution of mucositis 3 months after endodontic treatment was not common, suggesting that it might linger beyond the elimination of the endodontic infection in some of the treated teeth. This study was supported by the AAE Foundation and the Canadian Academy of Endodontics Endowment Fund.

e24 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 57Prevalence of Mechanical Allodynia in Endodontic PatientsM.A. Pacheco*, F.B. Teixeira, K.M. Hargreaves, A.R. DiogenesUniversity of Texas at San Antonio, TX

Mechanical allodynia is defined by pain evoked by a nonnoxious mechanical stimulus. In endodontics, mechanical allodynia is characterized by pain evoked by percussion or biting and is the cardinal sign of apical periodontitis (SAP). It has been previously shown that 57% of patients with irreversible pulpitis (IP) also presented with mechanical allodynia (Owatz et al J Endod 2007). We hypothesized that mechanical allodynia predicts spontaneous pain and is correlated to the pulpal diagnosis. To test this hypothesis, we evaluated 3,540 teeth from 1,720 patients and once a clinical diagnosis was made by calibrated evaluators, patients completed a 100mm Visual Analog Scale (VAS) to record the present level of spontaneous pain from that tooth. Data were analyzed by ANOVA and Newman-Keuls MCP. As compared to control patients having a diagnosis of Normal Pulp/Normal Periapical (VAS: 3.6 ± 0.3mm), there was significantly greater pain in patients with diagnoses of IP/SAP (41.9 + 2.8; p<0.001), pulpal necrosis/SAP (31.1 + 3.7; p<0.001), and IP/Normal Periapical (25.1 + 3.2; p<0.001). In contrast, patients with pulpal necrosis/Normal Periapical (7.2 + 1.6; p=NS) did not differ from control patients. Importantly, the presentation of mechanical allodynia to percussion testing was associated with significantly greater spontaneous pain reports in patients with a pulpal diagnosis of either IP (p<0.001) or necrosis (p<0.001). The finding that mechanical allodynia is associated with significant increases in spontaneous pain in patients with either IP or pulpal necrosis suggests that mechanisms triggering allodynia may contribute to the development of persistent spontaneous pain. This study was supported by the AAE Foundation.

OR 58Evaluation of the Resected Root Surface of Mesial and Distal Roots of Mandibular Molars Following Orthograde MTA PlacementJ.B. Carroll*, A.E. Williamson, R.E. Walton, D.R. DrakeUniversity of Iowa, Iowa City, IA

A prior study demonstrated that mineral trioxide aggregate (MTA) placed in an orthograde manner in single-rooted teeth, when resected, showed no significant difference in leakage than MTA placed as root-end filling. The purpose of this study was to examine resected root surfaces following orthograde placement of MTA in mandibular molars. Twenty mandibular molars with two mesial and one distal canal were used. After cleaning and shaping, ten teeth were randomly selected for orthograde MTA obturation (Group 1). Ten teeth were obturated with gutta-percha and AH Plus™ sealer (Group 2). Teeth were stored for 48 hours in a humidor. The apical 3mm of each root was resected perpendicular to its long axis. Comparisons were made between the groups under a stereomicroscope. Root ends of Group 1 were prepared with ultrasonics; MTA root end fillings were placed for further comparison. 11/20 resected mesial roots demonstrated remaining tissue in an isthmus between the two canals. 29/30 canals obturated with MTA showed dense and well adapted fillings at the 3mm level compared to 28/30 GP obturations. The resected root and MTA surfaces of distal canals were comparable to those receiving traditional MTA root end fillings. According to the observations made in this study, it can be concluded that orthograde MTA placement and resection in mesial roots of mandibular molars can leave significant amounts of tissue uninstrumented and unsealed. Distal roots with one canal left similar root and MTA filling surfaces when compared to traditional MTA root-end fillings. This study was supported by the AAE Foundation and Brasseler USA (donated files).

OR 59The Correlation Between Blood Pressure and Postoperative Pain in Endodontic PatientsW. King*, E. Bair, W. Maixner, A. KhanUniversity of North Carolina, Chapel Hill, NC

Preclinical and clinical studies indicate that hypertension is correlated with diminished sensitivity to experimental pain. The correlation between blood pressure and postoperative odontogenic pain is yet to be evaluated. The purpose of this prospective observational study was to test the hypothesis that resting arterial blood pressure is inversely correlated to decreased postoperative pain following endodontic therapy. Written informed consent was obtained from patients (n=52) seeking treatment for teeth diagnosed with pulpal necrosis and periapical periodontitis. Exclusion criteria were: (1) American Society of Anesthesiologists’ physical status of 3 to 5, (2) periodontal pocket greater than 6mm around the tooth (to exclude potential perio-endo lesions), (3) persistent (>7 days) use of medications that might alter their pain report and (4) subjects taking any analgesics in the 6-hour period preceding treatment. The patients first had their blood pressure measured and were asked to rate their preoperative pain intensity on a 10 cm visual analog scale. Nonsurgical root canal therapy was then initiated using a standardized protocol. Prior to dismissal, the patients were given a pain diary in which they recorded their postoperative pain and analgesic intake for the next 7 days. Data were analyzed using the t-test. After controlling for preoperative pain, a significant correlation was noted between preoperative pulse pressure and postoperative pain (p<0.05). This study provides further support for a functional interaction between the cardiovascular and pain regulatory systems. Understanding factors that affect odontogenic pain will advance our progress in the prevention and management of postoperative pain.

OR 60The Impact of the Quality of Coronal Restoration Versus the Quality of Root Canal Treatment on Success: A Systematic Review and Meta-analysisB.M. Gillen*Medical College of Georgia, Augusta, GA

Thorough cleaning and shaping of the root canal system is essential for periapical healing. Restoration of the endodontically treated tooth is also required for the tooth to function and prevent bacterial leakage. This study compared the impact of the quality of endodontic treatment versus the quality of coronal restoration in treatment outcomes. Literature search was conducted with PubMed™ using the search terms “coronal restoration,” “root canal,” “periapical status” and “quality.” Articles that evaluated the effect of the quality of root filling and coronal restoration or both on the success of endodontic treatment were selected. Each of the 9 articles that were identified was reviewed by two investigators and data were collected based on predetermined criteria. Percentages of teeth without apical periodontitis were calculated and recorded for each category: Adequate Endo (AE), Inadequate Endo (IE), Adequate Restoration (AR), Inadequate Restoration (IR). Data were analyzed using meta-analysis for odds ratios (ORs). After adjusting for significant covariates in order to reduce heterogeneity, the results were combined to obtain pooled estimates of the common OR for the comparison of AR/AE vs. AR/IE (OR 2.75, 95% C.I. 2.61-2.88, p<0.001) and AR/AE vs. IR/AE (OR 2.81, 95% C.I. 2.64-2.97, p<0.001). The odds of healing increase with adequate endodontic and adequate restorative treatment. It is very difficult to compare previous studies because of the wide variability of criteria evaluated. Many criteria are similar but no two studies are exactly alike. A standardized set of evaluation criteria would make such analysis more manageable and produce a stronger impact. This study was supported by the AAE Foundation.

e25JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

OR 61A Comparison of the Debridement Efficacy of the EndoVac™ Irrigation System and Conventional Needle Root Canal Irrigation In VivoC. Siu*, J. BaumgartnerOregon Health & Science University, Portland, OR

The purpose of this study was to compare the debridement efficacy of EndoVac™ irrigation versus conventional needle irrigation in vivo. Seven adult patients with a total of 22 matched pairs of single-canaled vital teeth with fully formed apices were recruited. Canals were instrumented to a master apical file size #40/.04 taper. One tooth from each matched pair was irrigated using the EndoVac™ system. The other tooth was irrigated by conventional needle irrigation. Five additional teeth were used as positive controls. A #10 K-file was inserted into the control canals to determine working length (WL) with no other instrumentation or irrigation performed to confirm the presence of debris. The teeth were extracted, fixed and decalcified. Six histologic slides each 6 microns thick were made from sections at 1 and 3mm from WL and stained. The slide with the most debris was photographed at each level for each tooth. A Wilcoxon signed rank test was used to compare the percentage of debris remaining in the canals between the two irrigation techniques. The median amount of debris remaining at 1mm was 0.05% for the EndoVac™ group and 0.12% for the conventional irrigation group (p<0.05). The median amount of debris remaining at 3mm was 0.09% for the EndoVac™ group and 0.07% for the conventional needle irrigation group (p>0.05). EndoVac™ irrigation resulted in significantly less debris at 1mm from WL compared to conventional needle irrigation. There was no significant difference at the 3mm level.

OR 62Evaluation of the Antimicrobial Property of Curcumin on an E. Faecalis Biofilm: An In Vitro StudyA. Deshpande*, C. Walker, R. Pileggi, U. NairUniversity of Florida, Gainesville, FL

E. faecalis is known to be the most recalcitrant microorganism in the root canal system. Eradication of E. faecalis is difficult due to its ability to withstand long periods of starvation and to invade the dentinal tubules. Intracanal medicaments and irrigating solutions have been extensively studied in the endodontic literature to predictably eradicate E. faecalis. Curcumin, the active ingredient in the spice turmeric, has been shown to have antimicrobial properties in addition to being anti-inflammatory, anticancer and antioxidant. The aim of our study was to evaluate the antimicrobial property of curcumin on a mature biofilm of E. faecalis. Pure culture of E. faecalis was used to grow the biofilm on hydroxyapatite (HA) discs to determine the optimal antimicrobial concentration of curcumin. 1 Molar (M) curcumin solution in Dimethyl Sulfoxide (DMSO) demonstrated complete inhibition of the biofilm on the HA discs. The experiment was then repeated with extracted human teeth, which were biomechanically prepared, sterilized and exposed to E. faecalis to form a biofilm on the canal wall. The teeth from the test group were exposed to 1 M solution of curcumin for 24 hours, and a culture was obtained with the use of sterile paper points inserted into the canal and plated on agar plates after a tenfold serial dilution. The colony forming units (CFU) were counted and analyzed with a one-way ANOVA and Tukey Kramer post hoc test. Curcumin was shown to completely eradicate the biofilm at a 1 M concentration (p≤0.05). In conclusion, curcumin proved to be a powerful antibacterial agent against E. faecalis biofilm.

OR 63Comparison of Debris Removal Using Three Different Irrigation TechniquesR.K. Howard*, T.C. Kirkpatrick, J.M. Yaccino, R.E. RutledgeWilford Hall U.S.A.F. Medical Center, San Antonio, TX

The purpose of this study was to compare the effectiveness of debris removal using the EndoVac® the PiezoFlow™, or a Max-i-Probe® in the mesial roots of mandibular first molars. Using a K-Kube, 30 extracted teeth were mounted in resin and then sectioned at 2 and 4 mm from the apex. The specimens were reassembled in the K-Kube and instrumented to size 40/0.04 with K3 rotary files. A standard irrigation protocol using 6% NaOCl and 17% EDTA was used during instrumentation of the PiezoFlow™ and Max-i-Probe® groups while the manufacturer’s recommendation for irrigation was followed during instrumentation of the EndoVac® group. Images of the canals and isthmuses were taken before final irrigation. The resin-mounted specimens were reassembled in the K-Kube for final irrigation with the EndoVac® and PiezoFlow™ following manufacturer’s recommendations and the Max-i-Probe® with a similar volume of irrigants. Images of the canals and isthmuses were taken and used to calculate canal and isthmus cleanliness. Comparisons of canal and isthmus cleanliness before and after final irrigation were made using paired t-tests and the groups were compared with ANOVA (P<0.05). Canal and isthmus cleanliness significantly improved at all levels after the final irrigation regimen in each group, but there were no statistically significant differences in canal and isthmus cleanliness between the three groups at each depth (2 and 4 mm from WL). Using the EndoVac®, the PiezoFlow™ or greatly increasing the volume of irrigant used with the Max-i-Probe® significantly improved canal and isthmus cleanliness.

OR 64Classification of Fusobacterium Nucleatum Using Multilocus Sequence TypingD. Keating*, A. Ferrer, M. Chang, D. Fife, S. Kinder HaakeUniversity of California at Los Angeles, CA

Fusobacterium nucleatum (Fn) is a heterogeneous species, a common endodontic pathogen and plays crucial roles in biofilm formation. Classification using the 16S ribosomal subunit DNA sequence provides limited discrimination for assessment of closely related bacterial strains. Multilocus sequence typing (MLST) is an approach to characterizing bacterial species at the subspecies level using partial DNA sequences from multiple conserved housekeeping genes. The aim of this study is to use MLST to better understand the phylogenetic and evolutionary history of Fn and its closely related species. Forty strains isolated from sites of periodontal health and endodontic disease were analyzed in this study. Genes targeted included hbd, nusA, polC and ftsZ. DNA fragments within the target genes were amplified by PCR and submitted for sequence analysis. The DNA sequences were compiled, aligned and a phylogenetic tree was generated. Analysis has focused on the phylogenetic distribution of genes in comparison to Fn-type strains. Fn strains isolated from necrotic root canals represented a selective subset of Fn subspecies. Most strains demonstrated concordance in the phylogenetic relationship of the housekeeping genes and the rRNA gene sequences. Six strains (15%) demonstrated a lack of concordance between housekeeping genes and the 16S rRNA gene. In five strains, a single housekeeping gene was discordant. These findings suggest the possibility of intraspecies recombination events leading to tractable genotypes among the fusobacterial strains. Further analysis to characterize the allelic profile of the strains is in progress. This study was supported by the National Institutes of Health and the National Institute of Dental and Craniofacial Research.

e26 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

OR 65Effect of Photodynamic Crosslinking and Chitosan Infiltration on the Structural Integrity of Dentin-CollagenA. Shrestha*, S. Friedman, A. KishenUniversity of Toronto, ON, Canada

The structural integrity of the root dentin remaining after endodontic treatment can determine the longevity of the tooth. The dentin-collagen matrix may be stabilized by achieving crosslinks between collagen fibrils, while incorporation of biopolymeric fillers may reinforce collagen matrix. This study investigated the effects of photodynamic crosslinking and carboxymethyl-chitosan (CMCS) infiltration on the structural integrity of dentin-collagen. Demineralized dentin-collagen specimens from extracted human and bovine teeth (N=64) were photodynamically crosslinked with noncoherent light (540 nm) at 20J/cm2 using rose bengal as photosensitizer, with/without CMCS. The ultrastructure of the crosslinked collagen was analyzed using transmission electron microscopy (TEM) and its chemical composition determined using Fourier-transform-infrared (FTIR) spectroscopy. Resistance to degradation by collagenase was evaluated by quantifying the amino acid release. The ultimate-tensile-strength (UTS) and toughness were also measured. TEM of control specimens showed a loose collagen fibrillar network with frayed edges. In all crosslinked specimens, the collagen interfibrillar spaces were smaller and the fibrils arranged in a tight network. FTIR spectroscopy confirmed crosslinks between -NH and -CO groups of collagen and CMCS incorporation into the collagen matrix. All crosslinked collagen specimens showed significantly (ANOVA, post hoc Tukey’s test; p<0.05) less amino acid release than untreated controls when degraded by collagenase. UTS and toughness were significantly higher (p<0.05) in all crosslinked collagen than in controls, with CMCS infiltration enhancing both properties. This study demonstrated that photodynamic crosslinking with simultaneous CMCS infiltration into the collagen microstructure improved both the resistance to enzymatic degradation and the fracture toughness of dentin-collagen. This study was supported by the University of Toronto.

OR 66In Vivo Comparison of an Ultrasonic and Nonultrasonic Irrigation ProtocolC.M. Beus*, J. Stratton, B. KaufmanUniversity of Connecticut, Farmington, CT

The use of irrigation as a method of rendering canals bacteria-free continues to be a source of investigation. Recent data suggests that an activated irrigation protocol such as passive ultrasonic irrigation can result in decreased intracanal bacteria. In addition, studies have shown that the activation of various irrigants such as NaOCl and Chlorhexidine can increase the sum antimicrobial effect. The purpose of this randomized, double-blinded, prospective in vivo clinical study was to compare the results of a nonactivated irrigation protocol (NAI) using only NaOCl 1.5% to a passive ultrasonic irrigation protocol (PUI) using NaOCl 1.5%, EDTA 17% and Chlorhexidine 2% in rendering canals bacteria free. Forty-four patients were recruited with a posterior tooth requiring primary endodontic treatment of a necrotic pulp, diagnosed by negative cold test and periapical radiolucency. Standard nonsurgical endodontic therapy was performed on both groups using micro-tip irrigation syringes. After completion of instrumentation, teeth were randomly treated with NAI or PUI. Bacterial cultures were obtained from the canals prior to instrumentation and after irrigation protocol. These cultures were evaluated for growth after 7 days in enriched anaerobic medium. Statistical analysis was performed on data using the Fisher’s exact test. NAI and PUI rendered canals bacteria free, 77% and 91%, respectively. These differences were not significant (p=0.23). We conclude that although there was no statistical difference between irrigation methods, both protocols resulted in a high frequency of negative cultures, and this is most likely related to increased volume and depth of irrigation. This study was supported by the AAE Foundation.

OR 67The Biocompatibility, Setting Time, Radiopacity and Calcium Release of a New Experimental CementM. Mercade Bellido, A. Gella, A. Ramawarrier, F. Duran-Sindreu*, M. RoigUniversitat Internacional de Catalunya, Barcelona, Spain

The purpose of this study was to analyze the biocompatibility, setting time, radiopacity and calcium release of a new experimental cement and compare them with MTA. Two cement types were used: ProRoot MTA® and a mixture of ElectroLand cement and Portland cement. The setting time of the cements was evaluated using an indentation technique. Biocompatibility of the materials was assessed using MTT assay for indirect test and Alarmar Blue™ dye for direct test. The experimental groups were: G1, MTA; G2, Portland + ElectroLand + bismuth oxide; G3, Portland + ElectroLand + Barium Sulphate; G4, Portland + ElectroLand. The setting time of the experimental cement was 11 min ± 30 sec whereas MTA set in 2.28 h ± 5 min. In the indirect biocompatibility test, cell viability increases when the extract was more concentrated. No significant differences (p > 0.05) were observed between the different cement formulations and the two control groups. The results for the direct biocompatibility revealed slightly high cell viability for cells without cement. However, all the cements exhibited a similar slight inhibitory effect on cell viability (p > 0.05). The radiopacity of the cements was comparable to MTA and similar calcium concentration release was observed between MTA and Portland-ElectroLand mixture (13.1 ± 0.9 and 12.3 ± 0.9 mmol/L, respectively). The addition of ElectroLand cement to Portland cement reduced the setting time. Within the parameters set in this study, the properties of the mixture Portland + ElectroLand were similar and comparable to ProRoot MTA®.

e27JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 01Quantitative Analysis of Inflammatory Mediators and Bacterial Colonization on Necrotic and Inflamed Pulpal TissuesK. Andrus*, R. Pileggi, U. Nair, C. Varella, C. Walker, S. Wallet, K. NeivaUniversity of Florida, Gainesville, FL

Endodontic disease is a condition of inflammatory nature resultant from physical, chemical or bacterial stimuli. Following insult, a range of cytokines is increased. Several bacteria species have been identified in endodontic infections; however, the correlation between inflammatory mediators and bacterial colonization has not been established. The purpose of this study was to determine and quantify inflammatory cytokines and the microbiota present in dental pulp during necrosis and irreversible pulpitis (IP). Dental pulp fluid was collected from patients receiving root canal therapy using PerioPaper® and paper points. Teeth extracted for orthodontic reasons were used as control. Cyto-/chemokine profile was determined using Milliplex® technology, which analyzes multiple cytokines in a single sample. Total genomic DNA was extracted and analyzed by real-time PCR. Representative species from common phyla identified in endodontic infections were analyzed: Enterococcus faecalis, Fusobacterium nucleatum, Tannerella forsythia and Treponema denticola. Results demonstrated that necrotic pulps had significantly more MCP1 and TNFα than normal and IP groups. IP showed significantly higher levels of IL6 and IL1ß than normal and necrotic pulps. Both necrotic and IP presented significantly higher IL8 than normal pulp tissues. Enterococcus faecalis, Fusobacterium nucleatum, Tannerella forsythia and Treponema denticola were present in normal, necrotic and IP groups. However, all bacteria species presented higher expression in necrotic pulpal tissues. In addition, among the species evaluated here, Fusobacterium nucleatum was the bacteria with the highest expression levels. In conclusion, IL8 and Fusobacterium nucleatum demonstrated a higher expression in all disease pulpal tissues.

PR 02The Effect of Sodium Fluorosilicate on the Properties of Mineral Trioxide AggregateK. Appelbaum*, J.T. Stewart, G. HartwellUniversity of Medicine & Dentistry of New Jersey, Newark, NJ

Mineral Trioxide Aggregate (MTA) satisfies many of the ideal properties of a root-end filling material, including being nontoxic, noncarcinogenic, biocompatible, insoluble in tissue fluids, dimensionally stable and promoting cementogenesis. However, MTA has a long setting time, which makes it a difficult material to utilize during endodontic procedures. MTA has similar properties to Portland cement (PC). The concrete industry has used many additives to decrease the setting time of PC. Proprietary formulas of fluorosilicates have been added to PC to decrease its setting time. The purpose of this study was to determine if the addition of sodium fluorosilicate (SF) to PC could decrease the setting time and if this addition affects its compressive strength. Due to the high cost of MTA, PC was used to determine the most appropriate amount of SF. 1%, 2%, 3%, 4% and 5% SF by weight were added to PC and compared to PC without SF. Setting times were measured using a Gilmore Needle and compressive strengths were measured using an Materials Testing System Machine at 24 hours and 21 days. Statistical analysis was performed using analysis of variance with an alpha value of 0.05. SF was not effective in changing the setting time of PC (P>0.05) and did not increase the compressive strength of PC (P>0.05) to a statistically significant degree. Based on the conditions of this study, SF should not be used as an additive to MTA to decrease the setting time of MTA. This study was supported by the AAE Foundation and the University of Medicine & Dentistry of New Jersey.

PR 04Radiopacity Comparison of Six Endodontic SealersA. Barani*1, H.W. Roberts1, M.D. Roberts1, S.J. Hubar2, B.G. Jeansonne2, B.E. Bergeron1

181st Medical Group/DS/SGDDT/Keesler Air Force Base, MS, 2Louisiana State University, New Orleans, LA

Introduction: Radiopacity is considered a critical property of endodontic sealers. The purpose of this study was to compare the radiographic density of six root canal sealers, including Brasseler USA’s new bioceramic EndoSequence™ BC Sealer™, which is marketed as a highly radiopaque product. Methods: Six specimens (1x5 mm) of each sealer (BC Sealer™, Pulp Canal Sealer™ EWT, EndoRez®, 2Seal, RealSeal™ and Roth 811 Elite sealer) were digitally radiographed along with a graduated aluminum stepwedge. A Progeny Preva x-ray tubehead was set at 60 kVp and 4 mA at a distance of 15 cm. A Kodak™ RVG 6100 intraoral digital sensor and Kodak™ Dental Imaging Software were used for radiographic imaging. Data were analyzed using ANOVA and a Tukey-Kramer Multiple Comparison Test (p=0.05). Results: All the sealers evaluated met the minimum radiopacity standards set by ANSI/ADA specification No. 57. BC Sealer™ and 2Seal groups showed greater radiopacity (6.0 and 6.4 mm Al, respectively) followed by RealSeal™ (5.7 mm Al), Pulp Canal Sealer™ EWT (5.2 mm Al), and EndoRez® (5.0 mm Al). Roth 811 showed the lowest radiographic density (3.7 mm Al). The differences between the sealer groups were statistically significant (p<0.05) with the exception of 2Seal vs. BC Sealer™, RealSeal™ vs. BC Sealer™ and Pulp Canal Sealer™ EWT vs. EndoRez®. Conclusion: BC Sealer™ and 2Seal exhibited the highest radiopacity among sealers tested. While the increased radiopacity was statistically significant, this would likely be imperceptible in a clinical setting.

PR 03Complex Regional Pain Syndrome-Like Condition of the Trigeminal Nerve: A Report of Two Distinct CasesI.H. Asghar*, D.C. Thomas, G.M. Heir, G.R. HartwellUniversity of Medicine & Dentistry of New Jersey, Newark, NJ

Chronic Regional Pain Syndrome (CRPS) is a painful neuropathic disorder that develops as a consequence of trauma. This disorder commonly affects upper and lower limbs and is characterized by pain (spontaneous hyperalgesia, allodynia), abnormal regulation of blood flow and sweating, edema of tissues and atrophic changes of tissues. CRPS I (previously Reflex Sympathetic Dystrophy) typically develops after minor trauma. CRPS II (previously Causalgia) develops after a large nerve lesion. CRPS occurring in the orofacial region (Trigeminal system) has rarely been reported. The uniqueness of the Trigeminal system is evident in the fact that this is the only nerve whose terminal branches are destined for programmed natural denervation (as in shedding of deciduous teeth) without developing neuropathic pain. Also there are a disproportionately low number of neuropathic pain cases in the distribution of the trigeminal nerve, although thousands of deafferentation procedures (such as cavity preparation, root canal treatments, tooth extractions) are performed daily in dental clinics around the world. It may very well be true that many dentists are not trained to recognize such an entity as it presents to a dental clinic. Two clinical cases will be presented of patients developing CRPS during the course of endodontic treatment. Conclusion: CRPS do manifest in the orofacial region, although largely undiagnosed.

e28 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 06Influence of BioPure™ MTAD and Ultrasonic Irrigation on the Elimination of Bacteria From Root Canal SystemsP.J. Bellingham*, I. Bennett, E. Romberg, A. FouadUniversity of Maryland, Baltimore, MD

The goal of endodontic treatment is the elimination of bacteria from the root canal system. BioPure™ MTAD (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) is a newer endodontic irrigant that contains doxycycline. The ProUltra™ PiezoFlow® (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) is an ultrasonically activated, 25-guage irrigation needle that was recently introduced to aid in microbial elimination. The purpose of this study was to compare the antimicrobial efficacy of a final rinse of BioPure™ MTAD to 5.25% sodium hypochlorite with supplemental irrigation of these solutions using the ProUltra™ PiezoFlow® needle. Canals in 12 single-rooted teeth with apical periodontitis were prepared with 5.25% sodium hypochlorite and 17% EDTA. Canals were then randomly assigned to receive a final rinse with either BioPure™ MTAD or 5.25% sodium hypochlorite through a 27-gauge needle. The canals then received a supplemental irrigation with their respective final rinse solutions for 1 minute with the 25-gauge ProUltra™ PiezoFlow® needle. Bacterial samples were taken before instrumentation, after the final rinse and after supplemental ProUltra™ PiezoFlow® rinse. Bacteria were cultured anaerobically and enumerated by colony-forming-unit (CFU) counts after 14 days incubation. Results were compared by ANOVA. All initial samples tested positive for bacterial growth. There were no significant differences in residual CFU values after final rinse with BioPure™ MTAD or 5.25% sodium hypochlorite with or without supplemental irrigation via the ProUltra™ PiezoFlow® irrigation (P>0.05). These results suggest there is no added benefit to a final rinse with BioPure™ MTAD or ultrasonic irrigation in single rooted teeth. This study was supported by the AAE Foundation.

PR 07Comparison of the Biocompatibility of Common Types of Endodontic Sealers Using Periodontal Ligament Stem Cells and the Lactate Dehydrogenase AssayY. Blanco*, K.N. Namerow, O. Bolanos, P.E. MurrayNova Southeastern University, Fort Lauderdale, FL

The purpose of this study was to compare the biocompatibility of five different types of endodontic sealers to periodontal ligament stem cells (PLSCs). Sixty-six extracted human nondiseased, single-canal teeth were cleaned and shaped using ProTaper™ and ProFile™ rotary instrumentation in a crown-down manner to an apical ISO size of 35 using common endodontic procedures. The sealers added to the root canals were; AH Plus™ Sealer (De Trey/DENTSPLY, Konstanz, Germany), Apexit™ Sealer (Vivadent, Schaan, FL), Seal Apex Sealer™, RealSeal™ (SybronEndo/Kerr, Romulus, MI), PulpDent™ Sealer (Pulpdent Corp. Watertown, MA), BC Sealer™ (Brasseler USA, Savannah, GA), in addition to a tissue bio-adhesive (BD Cell-Tak, BD Bioscience, San Jose, CA). The sealers were added to the root canals and compacted using a gutta-percha point. The sealers were allowed to set for 48 hours and the instrumented teeth were placed in cell culture with confluent PLSCs for one week. The control treatments were no PLSCs and no sealer. Biocompatibility was measured as the survival of PLSCs using the lactate dehydrogenase assay (CytoTox-ONE™, Promega Corporation, Madison, WI.). The data was analyzed by analysis of variance statistical tests (P-values) at a significance of 95%. We found a difference in the survival of PLSCs between the different types of sealers (P<0.05). The selection of biocompatible endodontic sealer is important to maintain survival of PLSCs. The use of biocompatible endodontic sealers may be beneficial for the healing of the periapical and periodontal tissues. This study was supported by NSU Health Professions Division.

PR 08Cyclic Fatigue Resistance of Size 30 Nickel-Titanium Rotary Instruments with Six Percent TaperJ. Bouska*, A. Williamson, B. Justman, M. GomezUniversity of Iowa, Iowa City, IA

New file sizes have recently been added to the Twisted File™ (TF; SybronEndo, Orange, CA) line of rotary nickel-titanium endodontic files. Previously TF were available in various tapers with a tip size of 25. The new file sizes include size 30 and 35 with a 6% taper and 40 and 50 with a 4% taper. The purpose of this study was to compare cyclic fatigue resistance of the new size 30 TF files with size 30 files of another popular design, EndoSequence™ (ES; Brasseler USA, Savannah, GA). Size 30 files with a constant 6% taper were rotated at manufacturer-recommended speed and torque settings in a simulated canal until failure. The TF files required a greater number of rotations to fracture than ES. The difference between file brands may be due to different manufacturing process or due to differences in file design. Based on a simulated canal model, the new TF files appear to offer greater cyclic fatigue resistance than ES files. This study was supported by the AAE Foundation and SybronEndo.

PR 05Monoblock Formation Using Methacrylate Resin-Based Sealer and a Synthetic Polymer-Based Point: A Comparison of Three Obturating TechniquesR.K. Barfuss*, R.E. Walton, A.E. Williamson, D. DrakeUniversity of Iowa, Iowa City, IA

Bondable sealer has been proposed as creating a monoblock or a gap-free bond between canal wall and a synthetic polymer-based point. Objective: To determine the extent that the polymer-based point, Resilon™, and sealer (Epiphany™) form a complete “monoblock” at three different levels in the canal. Materials and Methods: Compared obturations: 1) single cone; 2) cold lateral; and 3) warm vertical. Forty-five anterior, single-rooted human teeth were decoronated and instrumented with stainless steel and NiTi rotary instruments until a #45 hand file fit at working length. The prepared teeth were divided into three groups of 15 each according to obturation technique. All were obturated using Resilon™ with Epiphany™ sealer. After 2 weeks in 100% humidity, the teeth were grooved and split along the root to expose the canal contents. Materials and canal walls were viewed under magnification. Assessed was: 1) bonding of sealer and point to dentin; 2) voids; and 3) presence of sealer on canal walls. Each of the criteria was scored and grouped as to frequency and statistically analyzed. Results: All three groups showed marked variations. Voids and/or unbonded surfaces were detected in all teeth in at least one level (45/45). Cold lateral was the least uniform while single and warm vertical were the most uniform. Conclusion: The resin bonding obturation system did not show complete evidence of monoblock formation with any of the three obturating techniques. This study was supported by the AAE Foundation.

e29JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 09Identification of Tissues Formed After Pulp Revascularization in a Ferret ModelM.R. Buhrley*, R. Corr, S. Shabahang, M. TorabinejadLoma Linda University, Loma Linda, CA

Increasing evidence demonstrates the possibility for regeneration of vital tissues in teeth with necrotic pulp and open apices. Little is known about the type of new tissues formed during this process. The purpose of this study was to identify the tissues formed in the root canal space after regenerative endodontic procedures in a ferret model. The canals of 12 immature ferret cuspid teeth with open apices were accessed and the pulps were extirpated. After irritation of the periapical tissues, formation of a blood clot and placement of MTA over the clot, the access cavities were sealed. Block sections were obtained three months later and evaluated histologically to identify the phenotypes of the new tissues formed within the root canals. Histological specimens illustrated in-growth of bone that was contiguous with surrounding periapical bone, as well as cementum and periodontal ligament in 8 samples. In four samples, no tissue in-growth was found due to the depth of MTA placement. Statistical analysis of the data showed no significant association between the presence of bone with inflammation, cementum or periodontal ligament. Based on our findings, it was concluded that the tissue formed inside of the root canals under the parameters of this experiment was mainly bone with some cementum and periodontal ligament in-growth continuous with the periradicular tissues. There was no indication of new dentin formation or pulp regeneration.

PR 10Effect of Splint Coverage on Laser Doppler Flow Meter ReadingsP. Challagulla*, M.M. Saad, F.C. Setzer, M. TropeUniversity of Pennsylvania, Philadelphia, PA

Laser doppler flow meters assess pulpal blood flow (PBF). Differences in PBF with single [STI] versus multiple tooth isolation [MTI] were evaluated. PBF was measured in 25 maxillary right central incisors. No restorations or radiographic signs of pathology were present, all teeth tested normal to sensibility and percussion. Two groups were formed: an experimental group (EG; n=20) and a control group (CG; n=5). A VMS-LDF™ laser doppler system (Moor Instruments, Devon, UK) with VP3 probe was used for PBF measurement. Both groups were tested using two types of isolation: STI and MTI (including two teeth each mesial and distal). In CG, participants received local infiltration (LI) with 1.8ml of 2% Lignocaine (1:50,000 epinephrine) as negative control. The probe was inserted buccally 3mm from the gingival margin. Participants lay in supine position, resting 10 minutes before PBF reading. PBF was measured in Perfusion Units (PU) for 4 minutes. T-test was used for statistical analysis. Statistically significant differences existed in EG between mean PBF for STI (8.6 PU) - MTI (5.4 PU), p=0.01; in CG between PBF before LI (9.1 PU [STI] - 5.5 PU [MTI], p=0.006); after LI (4.5 PU [STI] - 5.5 PU [MTI], p=0.003) and between EG and CG after LI (8.6 PU (EG) - 4.5 PU (CG) [STI], p=0.003; 5.4PU (EG) - 1.6PU (CG) [MTI], p<0.001). No significant difference existed between EG and CG before LI for STI or MTI. MTI prevented signal contamination better than STI. STI could differentiate between normal and reduced PBF. LI decreased PBF values by 41% in STI and 70% in MTI.

PR 11Effects of Nitrogen Ions Implanted Nickel-Titanium Rotary Instruments on Canal Shaping in Simulated Root CanalY.F. Chou*1, H.H. Haung1, W.F. Tsai2, C.F. Ai2, S.F. Yang3

1National Yang-Ming University, Taipei, Taiwan, 2Taoyuan, Taiwan, 3Taipei, Taiwan

Implantation of nitrogen ions creates a surface layer of titanium nitride (TiN), which can significantly improve defects and increase cutting efficiency and wear resistance. The purpose of this study was to evaluate the effects of nitrogen ions implanted nickel-titanium rotary instruments on canal shaping in simulated root canals. The NiTi rotary instruments (ProFile® and ProTaper™ universal) had undergone a process of plasma immersion ion implantation (PIII) with low and high dose nitrogen. A sequence of instruments were used to prepare five simulated root canals. Ninety simulated root canals were divided into six sub-groups. The pre- and postimages of longitudinal section of root canal were recorded by the stereomicroscope accompanied with a digital camera. The change of root canal at nine different points was assessed with Image-Pro® Plus from the apex. The Kruskal-Wallis test was used for assessment. Numbers of instrument fracture incidences and completed simulated root canals were recorded. In ProFile® groups, 44 simulated canals were completely prepared and only one instrument (0.06/#30) fractured. In ProTaper™ universal groups, 32 simulated canals were completely prepared and six F3 instruments fractured. In root canals shaping, all treated ProFile® and ProTaper™ universal instruments were effective in maintaining the original canal path of curved simulated root canals. There were no significant differences on canal wall reduction between 1 to 7mm from the apex among treated and untreated ProFile® and ProTaper™ universal instruments. In conclusion, there were no adverse effects in canal shaping of nitrogen ion implanted NiTi rotary instruments - ProFile® and ProTaper™ universal.

PR 12A Comparison of the Cytotoxicity and Proinflammatory Cytokine Production of EndoSequence™ Root Repair Material and ProRoot® MTA in Human Osteoblast Cell Culture Using Reverse Transcriptase-PCRM. Ciasca*, A. Mickel, G. Jin, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

It is estimated that more than 24 million endodontic procedures are performed annually, and up to 5.5% of these procedures are apical surgery, perforation repair and apexifications (Nash KD, Brown J, Hicks ML J Endod 2002). Many materials have been used as retrograde fillings, such as amalgam, IRM®, Super EBA® and MTA; however, we are still seeking materials that fulfill Grossman’s ideal properties. The purpose of this study was to compare the cytotoxicity of EndoSequence™ Root Repair material (ERRM) putty, ERRM flowable and ProRoot® MTA (Mineral Trioxide Aggregate) utilizing osteoblast cells (MG-63). Four mm of each material was placed in the center of a 6-well culture plate and a 2 mL suspension (105 cells/mL) of human osteoblasts was seeded in each well. Photomicrograph images were used to evaluate cytotoxicity as evidenced by the lack of osteoblast growth in relation to the materials. In addition, RT-PCR was used to evaluate IL-1ß, IL-6, IL-8 and TNF-α production. LPS (negative) and AH-26 (positive) were used as controls. RT-PCR results were normalized by the expression of the housekeeping gene ß-Actin and were used to measure cytokine production. We hypothesized that MTA and ERRM would demonstrate comparable cytotoxicity and cytokine production. Statistical analysis was performed using T-test. Results showed production of IL-1ß, IL-6 and IL-8 in all samples but minimal TNF-α production. Only the production of IL-1ß was statistically significant (p<0.05). ERRM flow and MTA exhibited minimal levels of cytotoxicity, but ERRM putty was slightly more cytotoxic (not statistically significant). Therefore, we conclude that ERRM and MTA demonstrate similar and negligible cytotoxicity.

e30 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 14A Retrospective Clinical Study of the Incidence of Root Canal Therapy Versus Tooth Extraction on Previously Restored Teeth Using Pin Placement in a Dental School ProgramN. Dejbod*, K. Kandel, B. KarabucakUniversity of Pennsylvania, Philadelphia, PA

Restorative pins can provide retention and resistance for complex amalgam restorations replacing at least one cusp, yet the procedure can be invasive. This study investigates the incidence of root canal therapy versus tooth extraction procedures after failed, pin-retained restorations in vital teeth. A query into the University of Pennsylvania School of Dental Medicine revealed that 625 restorative pins were placed since 2002. The majority of pin-retained restorations were placed in molar (49.0%) followed by anterior (29.7%) and lastly premolar (21.3%) teeth. Of these 625 pin-retained restorations, 109 teeth (17.3%) were referred for either root canal treatment or extraction at the University of Pennsylvania, with a greater percentage of teeth referred for root canal therapy than for extraction. The highest percentage of pin-retained restorations that were referred to either the endodontic or oral surgery departments were pins placed in the anterior (21.5% out of 186 teeth) followed by premolar (18.8% out of 133 teeth) and molar (14.0% out of 306 teeth) teeth. Sixty charts were randomly selected from the 17.3% of teeth that required subsequent treatment following pin placement. Each pin procedure has been examined for differences in the location of the pin, number of pins, condition of the tooth prior to pin placement and restorative material used in the treatment. The causative and predisposing periodontal and restorative factors were investigated. A detailed report of the data indicates that several factors examined have directed dentists to treatment plan for either root canal therapy or surgical extraction after a restorative pin procedure.

PR 15Irrigation Trends Among AAE Members: A Web-Based SurveyJ.M. Dutner*, P. Mines, A. AndersonU.S. Army Dental Activity, Fort Bragg, Fayetteville, NC

Introduction: The purpose of this study was to determine current trends in irrigation selection among endodontists. Methods: An invitation to participate in a Web-based survey (QuestionPro™) was e-mailed to 3,844 members of the American Association of Endodontists. Survey participants were asked between 10 and 14 questions based on their individual responses. Among other questions, participants were asked about their irrigant selection, irrigant concentration, smear layer removal and use of adjuncts to irrigation. Results: A total of 3,707 survey invitations were successfully delivered by e-mail after accounting for several undeliverable e-mail invitations. There were 1,102 participants, with an overall completion rate of 28.5% (n=1,054). Our data indicates that over 90% of respondents primarily utilize sodium hypochlorite, with 57% of them using it at a concentration greater than 5.0%. 77% of respondents aim to remove the smear layer during endodontic treatment. At least 45% of respondents reported using an adjunct to irrigation. Conclusions: Most of the respondents are utilizing full-strength sodium hypochlorite and are routinely removing the smear layer during endodontic treatment. In addition, almost half of the respondents are utilizing an adjunct, such as ultrasonic activation, to aid in their irrigation technique.

PR 16Epidemiological and Diagnostic Variables Among Diabetics Within an Endodontic Patient PopulationJ.E. Fein*, A.F. FouadUniversity of Maryland, Baltimore, MD

Diabetes is an ever-growing disease, now affecting 23.6 million or 7.8% of people in the United States. The purpose of this study was to examine the demographics and treatment variables of diabetic patients in a postgraduate endodontics clinic. Diagnostic and treatment data were entered into an electronic system for all patients between July 2005 and October 2010. 3,907 patients were seen by postgraduate endodontic students during this time period, 234 of whom (6%) indicated that they were diabetics. Chi-square was used to analyze the data where variables had more than two groups, and Fisher’s Exact test was performed to analyze all two-by-two tables. There was no significant difference between diabetics and nondiabetics in terms of race (p=0.17), but diabetics were statistically more likely to be male than nondiabetics (p=0.003). Diabetics were significantly more likely to have a diagnosis of previously treated pulp (p=0.001). Pulp necrosis also constituted a higher proportion of diagnosis in diabetics, but this was not statistically significant (p=0.12). Diabetics were significantly more likely to have a diagnosis of Asymptomatic Apical Periodontitis than nondiabetics (p=0.002) and were also more likely to have an acute abscess, but this was not statistically significant (p=0.24). Flare-ups were more prevalent in diabetics, but this was also not statistically significant (p=0.32). No significant differences were present between Type I and Type II Diabetics for any diagnosis. Diabetics appear to be more likely to suffer from some determinants of advanced endodontic disease than nondiabetics. This study was supported by the AAE Foundation.

PR 13Measurement of the Survival of Stem Cells From Human Exfoliated Deciduous Teeth With Tissue-Engineered Pulp Construct in the Presence of Irrigants, Disinfectants and AntibioticsM.M. Cielecki*, K.N. Namerow, P.E. MurrayNova Southeastern University, Fort Lauderdale, FL

The objective of this study was to investigate the role of endodontic irrigants, disinfectants and antibiotics on endodontic tissue regeneration. Stem cells from human exfoliated deciduous teeth (SHED) were grown to confluence and seeded on polymer scaffolds (BD Biosciences, Franklin Lakes, NJ) to create tissue-engineered pulp constructs (n=270). The pulp constructs were submerged in Dulbecco’s Minimal Essential Media containing 10% fetal calf serum at a temperature of 37˚C in a 5% CO

2 atmosphere for 1, 7 and 14 days. Neutral red dye (0.0016%) was added

to the culture media to stain metabolically active SHED. The effects of Penicillin/Streptomycin, Doxycycline Hydrochloride, Triple Antibiotic Paste (Ciprofloxacin, Metronidazole and Minocycline), Sodium hypochlorite (Clorox, Oakland, CA), EDTA and Chlorhexidine gluconate (CHX, Vista Dental Products, Racine, WI) solutions were tested by adding them (10%) to the culture media of pulp constructs. The specimens were fixed in formalin, dehydrated and processed for histology. A light microscope at x200 magnification was used to visualize SHED within the dental pulp constructs. Data was analyzed by Chi-square statistical tests (P-values) at a significance of 95%. SHED survival was optimal in the presence of antibiotics, but not irrigants or disinfectants (P<0.05) especially over longer time periods (P<0.05). These in vitro results suggest that irrigants and disinfectants are harmful for endodontic tissue regeneration. The use of reduced doses, flushing irrigants and antibiotics in the root canal could be beneficial for patients of regenerative endodontic procedures. This study was supported by NSU Health Professions Division.

e31JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 17An In Vitro Biocompatibility Comparison of Commonly Used Retrofill Materials and two New Materials: A MTA/IRM® Mixture and EndoSequence™ Root Repair MaterialM. Galsterer*, C. Sykes, A. Mickel, G. Jin, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Different materials have been used for root-end fillings. Ideal retro-fill materials should be biocompatible. We hypothesized that there is no difference in cytotoxicity when MTA/IRM® is compared to a new bioceramic material EndoSequence™ Root Repair Material® (ERRM). The purpose of this study was to evaluate the biocompatibility of various retro-fill materials, MTA/IRM® mixture and ERRM®. Fibroblast morphology and viability in the presence of root-end filling materials was evaluated at 4-, 24- and 72-hr periods. The following materials were tested: MTA® (Group 1), IRM® (Group 2), Super EBA™(Group 3), Geristore® (Group 4), ERRM® Flow(Group 5), ERRM® Putty(Group 6), MTA/IRM® mixture(Group 7), and AH 26™ (positive control), cell suspension (negative control). Photomicrograph images of the cells in the mid-well position were graded on cellular appearance. Cell viability index was evaluated as follows: Grade 1 indicated the cellular appearance was closest to the negative control (complete cell growth). Grade 4 was indicative that cellular appearance was closest to the positive control (complete cell death). Grades 2 or 3 were indications of variations of cellular morphology (indicating different levels of cell viability). A spindle shape was indicative of a lack of cytotoxic effects of the material on the cells. A round shape indicated cell death had occurred with the cells in contact with the materials. Data was analyzed with Chi-Square tests. Results indicated no statistical significance between MTA® and ERRM® Flow(p>.05), each showing negligible cytotoxicity; however, all other groups were significantly more cytotoxic. We conclude that EndoSequence™ Root Repair Material and MTA® demonstrated similar and negligible cytotoxicity.

PR 18A Comparative Evaluation of the Sealing Ability of two Root-End Filling Materials: An In Vitro Leakage Study Using Enterococcus FaecalisS.M. Ghattas*1, C. Walker2, R. Pileggi2, U. Nair2

1University of Detroit Mercy, Detroit, MI, 2University of Florida, Gainesville, FL

Adequate sealing ability of retrograde filling materials is essential for the success of surgical endodontics. The purpose of this study was to evaluate the sealing property of EndoSequence™ Root Repair™ (BCRR) material when compared to white MTA (WMTA) when used as a retrograde filling material. Forty single-rooted teeth were instrumented, obturated with gutta-percha, root-end resected and retrofilled with two different materials: white ProRoot MTA™ (WMTA) (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) (n=15) and BCRR: EndoSequence™ BioCeramic Root-end Repair™ (Brasseler USA, Savannah, GA) (n=15). Unfilled specimens (n=10) received no retrofill and were used as controls. All groups received E. faecalis in a created reservoir coronal to the root filling and microleakage was evaluated by counting the colony forming units (CFU) from each specimen. The results were analyzed with One-Way Analysis of Variance. There was no significant difference on the CFU counts between the two experimental groups, but there was a significant difference with the control (p≤0.05). This study suggests that BCRR™ is equivalent in sealing ability to WMTA when used as root-end filling material in vitro.

PR 19Solvent Effect on Pushout Strength When a Compomer Cement is Used for Post CementationM.E. Hatfield*, N.T. Decker, J. Stewart, G. HartwellUniversity of Medicine & Dentistry of New Jersey, Newark, NJ

The purpose of this study was to determine how different gutta-percha solvents used during post space preparation affect the bond strength of FugiPlus™ cement to root dentin. Twenty single canal extracted teeth were decoronated and instrumented to the apex with a size 50/.06 EndoSequence™ rotary file and then enlarged to a size 0.036 Parapost™ drill. The prepared roots were then divided into four groups based upon the solvent used: EndoSolve®, sodium hypochlorite, chloroform and orange solvent. The samples were left in contact with the different solvents for five minutes, then irrigated with sterile water, dried, conditioned with the FugiPlus™ conditioner and completely filled with FugiPlus™ cement. After allowing the cement to set for 48 hours, samples were embedded in clear acrylic and sectioned into thicknesses that varied between 1 and 4mm. The force necessary to dislodge the cement from the canal wall was measured using the Material Testing System Machine. Using the force values, sample thickness and diameter, the push-out strength was calculated and the results analyzed using a two-way ANOVA with the PAWS Statistics Software™, Version 18. A p-value of 0.318 was found indicating that there is no significant difference between the different solvents used during the preparation of a post space. The results of this in vitro study indicate that it is safe to use any of the four solvents during post space preparation without having any adverse affects on the bonding of FugiPlus™ cement to root dentin.

PR 20Effect of Dietary Vitamin A on RANKL-Expressing T Lymphocytes-Mediated Bone Resorptive Lesion of Apical Periodontitis in MiceJ.J. Hong*1, M.J.B. Silva2, M. Kajiya3, E. Alshwaimi1, H. Sasaki3, P.S. Ok1, T.C. Pagonis1, R.R. White1, B.J. Paster3, P. Stashenko3, T. Kawai3

1Harvard School of Dental Medicine, Boston, MA, 2Uberlandia, Brazil, 3Cambridge, MA

Receptor activator of nuclear factor K B-ligand (RANKL) produced from activated T lymphocytes induces osteoclastogenesis in bone destructive diseases. However, it is uncertain whether T lymphocytes produce RANKL in periapical lesions. Furthermore, while vitamin A is known to possess a regulatory effect on adaptive immune responses, its influence on RANKL production from T cells and resulting periapical bone resorption remains unclear. Using a mouse model of apical periodontitis, we examined: 1) the localization of RANKL-expressing T cell in periapical lesion in mice and 2) the effect of vitamin A deficiency on osteoclastogenesis. The mice fed with normal diet (sufficient in vitamin A) or vitamin A-depleted diet received pulp exposure in mandibular first molars. Exposed pulps were left open to the oral environment until day 0 (unexposed group), 3, 7 and 14 (n=5, each group). Two-color fluorescent immunohistochemistry was performed to identify RANKL-positive T cells in the periapical region, using a confocal microscope. Osteoclastogenesis was assessed by in situ TRAP staining. Infiltration of RANKL-positive T cells in periapical tissue was observed on days 3 and 7 after pulp exposure. Furthermore, the number of TRAP-positive osteoclast-like cells induced in the periapical lesion increased significantly in vitamin A-deficient group compared to control group (Student’s t-test, P<0.05). These findings indicated that the pulp exposure elicits the infiltration of RANKL-positive T cells in periapical lesion in conjunction with the induction of local osteoclastogenesis, and that dietary vitamin A appeared to down-regulate the pathological bone resorption, possibly by its immune suppressive effect.

e32 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 23Cyclic Fatigue Resistance of Rotary Nickel-Titanium Instruments in a Novel Custom-Designed Testing DeviceN. Karney*, F.C. Setzer, B. KarabucakUniversity of Pennsylvania, Philadelphia, PA

A novel custom-designed testing device was constructed. The device consisted of a center rotational platform that allowed file rotation between two grooved stainless steel pins at variable curvatures from 0 to 90 degrees. An electric motor handpiece with 16:1 contra-angle was used at operating speeds recommended by file manufacturers. Reciprocal file movement over 2 mm at 0.0625 Hz was initiated by connecting the handpiece to a horizontal staging platform moved by a motorized micrometer (Z612, Thorlabs Inc., Newton, NJ), geared by a computer-programmable servo-controller (TDC001, Thorlabs Inc., Newton, NJ). Four systems were tested: Revo-S™ [RS] (Micro-Mega, Besancon, France), Typhoon CM™ [TY] (Guidance Endodontics, Albuquerque, NM), Vortex™ [VO] and ProFile™ [PF] (DENTSPLY, York, PA) of tip sizes 25 and 35, resulting in a total of eight experimental groups. All files were 25 mm length, taper 0.04 and were tested at 30 degrees of curvature. All groups consisted of ten new files each. Time of fracture was recorded by an electronically connected stop watch and transferred to number of cycles at time of fracture [CTF]. One-way ANOVA was used for statistical analysis. Mean CTF were: Size 25 - VO(1101.7) > TY(947.3) > PF(499.0) > RS(225.5)(pTY(503.3) > PF(495.5) > RS(115.0)(p<0.001). For both sizes, the differences between the files were statistically significant. Statistically significant differences existed between files with different geometries under cyclic fatigue with reciprocal movement in a novel device at tip sizes 25 and 35. ProFile™ and Vortex™ had the highest mean CTF.

PR 24Physical Effects of Sodium Hypochlorite on Bone: An Ex Vivo StudyF.M. Kerbl*, P. DeVilliers, M. Litaker, P. EleazerUniversity of Alabama at Birmingham, AL

Sodium hypochlorite accidents during endodontic therapy require accurate and speedy action. Understanding the physical properties of bone changes and evaluating damage at the cellular level can improve management of these accidents. This study assessed the physical and histologic properties of dog femurs exposed to sodium hypochlorite at 30 minutes post injection. Four fresh dog femurs were dissected and frozen, and then twelve 40mm long sections were obtained and again cut into 20mm paired sections. Adjacent surfaces were randomly selected for a shallow injection of sodium hypochlorite or saline. Structural integrity of the cancellous bone was measured by micro-indentation testing using a Gilmore needle. A paired t-test revealed a statistically significant difference between groups, p= 0.0397. Histologic evaluation of the sodium hypochlorite specimens, when compared with the samples exposed to saline, showed degradation and necrosis of the fibro, fatty marrow elements and breakdown of the cancellous trabeculae, while the cortical bone appeared unaffected. Therefore, sodium hypochlorite compromises the integrity of cancellous bone and marrow elements.

PR 22A Comparison of the Antimicrobial Effectiveness of Hoshino’s Triple Antibiotic Paste With and Without Barium Sulfate Against an Enterococcus Faecalis Biofilm Using Scanning Electron MicroscopyM. Johnson*, A. Mickel, R. Jurevic, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Hoshino’s triple antibiotic paste has been used as part of a disinfection protocol to regenerate immature, necrotic permanent teeth (Trope, 2004). Barium sulfate is added to Ca(OH)

2 to provide radiopacity aiding in determining its location

in the canal space. Currently, triple antibiotic paste is void of any opacifier and therefore cannot be adequately visualized within the canal. The aim of this study was to compare the antimicrobial effectiveness of Hoshino’s paste with and without barium sulfate against an Enterococcus faecalis biofilm using SEM. We hypothesized that there would be no difference in antimicrobial efficacy between conventional Hoshino’s paste and Hoshino’s paste with barium sulfate against an E. faecalis biofilm. A reproducible model of E. faecalis biofilm grown on dentin from extracted teeth was used to determine the antimicrobial efficacy of 6 medicaments: group 1, Hoshino’s paste; group 2, Hoshino’s paste and barium sulfate; group 3, propylene glycol (carrier); group 4, phosphate buffered saline (negative control); group 5, NaOCl 6% (positive control); and group 6, barium sulfate. Each medicament was evaluated three times against the biofilm. SEM was used to detect viability of colonies on the biofilm through quantification of pre- and post-treatment biofilm volumetric dimensions (Pictzar Calibrated Digital Measurement Planimetry Software). Statistical analysis using Chi-square tests revealed no statistically significant (p>.05) difference between Hoshino’s paste with or without barium sulfate. In conclusion, the use of barium sulfate would aid in radiographic visualization without compromising the antimicrobial properties of Hoshino’s paste.

PR 21A Comparison of the Effectiveness of Three Different Irrigation Methods in the Removal of Bacteria From the Root Canal System Following InstrumentationK.L. Johnson*, E.M. Rivera, D. DugganUniversity of North Carolina, Chapel Hill, NC

Proper cleaning of the root canal system involves both chemical and mechanical methods. Furthermore, proper irrigation acts as a bactericidal agent, tissue solvent and lubricant, and removes organic and inorganic debris. Since it has been proven that the success of root canal therapy is related to the reduction of bacteria in the pulp canal space, then it is important to find the most effective method to eliminate these bacteria. The purpose of this study is to investigate the antimicrobial efficacy of sodium hypochlorite when used with the traditional irrigation technique using a 30 gauge side-vented needle, the EndoVac™ system, and the PiezoFlow™ Ultrasonic Irrigation Needle. It was hypothesized that both the EndoVac™ system and the PiezoFlow™ Ultrasonic Irrigation Needle would provide greater antimicrobial efficacy than the traditional irrigation technique with a 30 gauge needle. After obtaining informed consent, teeth were randomly divided into three treatment groups (N=30), and samples were collected following instrumentation and irrigation using one of the three irrigation techniques. The samples were cultured under aerobic and anaerobic conditions, and bacteria growth was measured by direct counting of colonies and grid specific calculations. Preliminary data indicated no significant difference in the antimicrobial efficacy between the three irrigation techniques. This study was supported by the AAE Foundation.

e33JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 25Evaluation of Pain Qualities and Descriptors in Patients With Acute Odontogenic PainS. Kim*, J.H. Lee, N. Heaivillin, D. Du, K. Schroeder, J. GibbsUniversity of California at San Francisco, CA

Objectives: In order to elucidate the association of a unique pain qualities and descriptors (PQ&D) with pulpal status in acute odontogenic pain, this prospective cross-sectional study is in progress. Study Design: PQ&D and results of standard endodontic diagnostic tests (EDT) will be obtained from 200 patients recruited at UCSF Dental Clinics. A main inclusion criterion is acute odontogenic pain of an intensity >3/10. PQ&Ds are largely categorized into: (1) Paroxysmal/intermittent; (2) Paresthesia/dysesthesia; (3) Evoked; and (4) Constant. Hierarchical cluster analysis will be performed to determine whether EDT and PQ&D results cluster based on clinical diagnosis. A diagnosis of vital or nonvital pulp is made according to cold and electric pulp test (EPT) results. Vital pulp is diagnosed when there is a positive response to cold or EPT. For preliminary analysis, we compared the frequency of PQ&D used to describe pain with a vital pulp versus pain with a nonvital pulp. Chi-squared test was performed. Results: We have recruited 32 subjects (mean age=40.7, 53% female) with a response rate of 64%. We compared PQ&D of vital pulp (n=25) versus nonvital pulp (n=7). Subjects with a vital pulp more frequently used PQ&D from the paroxysmal/intermittent domain (shooting (60.0%, P<0.05)). However, pain with nonvital pulp was more frequently described with constant PQ&Ds (throbbing [85.7%, P = 0.051], and heavy [83.3%, P<0.05]) and deep pain (100%, P<0.05). Conclusions: Patients used unique PQ&D to describe their odontogenic pain depending upon the pulpal status. The final outcome of this ongoing study could contribute the development of a novel diagnostic measure for odontogenic pain.

PR 27Evaluation of Splint Flexibility and Tooth Mobility After Avulsion Injuries Using a Cadaveric ModelS.C. Kwan*, J.D. Johnson, N. CohencaUniversity of Washington, Seattle, WA

Although current guidelines for treatment of traumatic injuries recommend the use of “flexible” splints, the precise definition of what is considered flexible versus rigid has not been rigorously defined, thus leaving the clinician with a wide range of options for this critical factor. Recent studies failed to provide convincing evidence due to severe limitations on the research model. The purpose of this study was to quantify and compare the effect of eight different splints on tooth mobility after avulsion and replantation using a human cadaveric model. Following strict criteria, including complete root maturation, lack of periodontal disease, normal bone levels and crown integrity, a maxillary central incisor was atraumatically extracted and splinted with eight different splints. The experimental groups included a 30 pound-test monofilament nylon-composite splint and six wire-composite splints made of wires of 0.012”, 0.016” or 0.020”; diameter stainless steel (SS) or nickel-titanium (NT). A direct composite splint was used as a positive control. These eight splints were applied five times each. The average splint effect, defined as the difference between the presplint and postsplint measurements quantified using the Periotest, calculated for each splint and compared. No significant differences were found among the nylon-composite and wire-composite splints. The direct composite splint was significantly more rigid than all other splints. In conclusion, the results of the present study suggest that nylon and SS or NT wires up to 0.020” diameter are consistent with “flexible” splints and thus, may be used for the splinting and management of traumatized teeth.

PR 28Preliminary Clinical Trial for Leakage Testing After Rubber Dam IsolationE. Lee*, Y. JouUniversity of Pennsylvania, Philadelphia, PA

The use of a rubber dam is an essential prerequisite for nonsurgical root canal therapy. Its routine use enhances every aspect of endodontic treatment. Although rapid, simple and effective methods of rubber dam applications have been developed, few studies have examined and/or reported clinical testing of the incidence of rubber dam leakage. This study presents a new clinical method for leakage testing after rubber dam application. An additional aim was to compare this result with our previous study on the preclinical test (2002). Two different rubber dam application techniques were used in a total of 200 cases. For 145 molar teeth, the placements of the dam, clamp and frame (DCF) were done in one motion. For 55 anterior and premolar teeth, the rubber dam and frame complex were placed first, followed by the clamps (DF+C). A water pooling test was performed to determine dam-tooth complexes while an operator and an assistant observed the water level change for 10 to 15 seconds. The overall rubber dam leakage rate was 7.50%. There was no statistically significant difference between the two rubber dam leakage rates (DCF, 7.27% versus DF+C, 7.59%, P>0.05, t-test). This result was different from our previous preclinical study. When properly placed, the rubber dam has a significant isolation effect (greater than 90%) on the reduction of leakage for nonsurgical root canal therapy.

PR 26In Vitro Comparison of the Push-Out Bond Strength of Three Endodontic Sealers With and Without AmoxicillinB.S. Kleinman*, D.W. BerzinsMarquette University, Milwaukee, WI

Introduction: The purpose of this in vitro study was to compare the push-out bond strengths of three endodontic sealers with and without amoxicillin. Methods: Thirty single-rooted extracted human teeth were used for this study. Each tooth was instrumented and irrigated with 5.25% NaOCl and 17% EDTA. The teeth were then divided into six test groups: group 1: gutta-percha (GP)/AH Plus®; group 1a: GP/AH Plus® with 10% by weight amoxicillin; group 2: GP/Pulp Canal Sealer EWT™; group 2a: GP/Pulp Canal Sealer EWT™ with amoxicillin; group 3: Resilon®/RealSeal SE™; and group 3a: Resilon®/RealSeal SE™ with amoxicillin. After the sealer was set, the entire root was sectioned into 1mm thick slices. A push-out bond strength test was preformed using a universal testing machine. The Mann Whiney and Student’s t-test were used to compare the sealer bond strength within the specific sealer test groups overall and within each sealer at apical, middle and coronal root levels. Results: There was no significant difference between test groups within each sealer, group 1 vs. group 1a (p=.85), group 2 vs. group 2a (p=.59) or group 3 vs. group 3a (p=.52). There was no significant difference (p>.05) in push-out bond strength within each sealer with or without amoxicillin at the same root level. Conclusion: The addition of 10% by weight of amoxicillin does not significantly change the push-out bond strength of GP/AH Plus® (p=.85), GP/Pulp Canal Sealer EWT™ (p=.59) or Resilon®/RealSeal SE™ (p=.52) overall or when compared at the apical, middle and coronal tooth level (p>.05).

e34 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 32Scanning Electron Microscopic Examination of the Antimicrobial Efficacy of Various Endodontic Irrigants and Their Associated pH Changes due to the Presence or Absence of DentinD. Morris*, A. Mickel, R. Jurevic, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Antimicrobial irrigants can be highly effective against microorganisms in vitro in a test tube; however we see a reduced effectiveness in vivo. It is likely that the mechanism behind this discrepancy is multifactorial. One of these factors is the reduced antimicrobial efficacy of endodontic irrigants in the presence of dentin (Haapasalo). The aim of this study was to evaluate the buffering capacity of dentin on endodontic irrigants with the resultant change in pH. We subsequently examined the antimicrobial efficacy of the irrigants using scanning electron microscopy (SEM) in an E. faecalis biofilm model. We hypothesized that dentin powder would act as a buffer to modify the pH of the irrigants and reduce their antimicrobial efficacy. SEM was performed and Pictzar Calibrated Digital Measurement software was used to quantify pre- and post-treatment biofilm volume indicating antimicrobial efficacy of Group1: 6% NaOCl, Group2: 17% EDTA, Group3: 2% Chlorhexidine and Group4: .9% NaCl saline (negative control). The pH of irrigants was measured with a pH meter (Accumet AB15) before and after adding 1.8% weight by volume dentin powder. Acidic irrigants (saline and chlorhexidine) showed the greatest pH changes in the presence of dentin with a statistically significant (p<.05) elevation of pH. Basic irrigants showed a slight reduction in pH that was not statistically significant(p>.05). Dentin powder showed an inhibitory effect on antimicrobial activity of all irrigants tested. Understanding the pH changes associated with the addition of dentin to endodontic irrigants could aid in determining the ideal formulation of endodontic irrigants in order to optimally reduce the microbial load in infected root canals.

PR 31Retrospective Outcome Assessment of Endosseous Implants Depending on Different Success CriteriaG. Marangou*, N.D. Tran, F.C. SetzerUniversity of Pennsylvania, Philadelphia, PA

The question of retention of teeth versus extraction and implant placement has become an issue of long-term predictability. Endodontic success was reported to range from 68%-85%. Many implant studies assessed outcome in strictly controlled populations and applied survival evaluation rather than strictly defined success criteria. From the University of Pennsylvania SDM database, 50 implants with at least 3 years of follow-up were selected randomly. Periapical radiographs from after implant loading and follow-up were digitalized. Two calibrated reviewers measured the radiographic bone levels and calculated vertical bone loss using CAD software (AutoCAD, Autodesk, Cupertino, CA). Implant success, survival and failure were evaluated using Albrekktson’s Criteria from 1986 (success = < 0.2 mm annual bone loss) and ICOI Criteria from 2007 (success, satisfactory survival, compromised survival and failure depending on the level of vertical bone loss). A nonparametric Wilcoxon signed-ranks test was used to test for statistically significant differences in the outcome of success between the criteria. Mean follow-up time was 4.1 years: of 50 implants, 49 survived at follow-up (96%). Mean vertical bone loss was 1.48 mm. After Albrekktson’s Criteria, there were 14 successes (28%) and 36 failures (72%); following ICOI Criteria, 35 successes (70%), 14 satisfactory survivals (28%), 1 compromised survival (2%) and 1 failure (2%). The difference in successful outcome was statistically significant (p<0.001). If assessment of dental implants is based on established implant success criteria rather than survival, true success rates are lower than for endodontically treated teeth. Significant differences also exist between different implant criteria.

PR 30Comparison of the Efficacy of 2% Lidocaine With 1:100,000 Epinephrine and 4% Articaine With 1:100,000 or 1:200,000 Epinephrine Regarding Onset of Pulpal Anesthesia, Paresthesia and use as a Supplemental Anesthetic: A Systematic ReviewM. Malek*, D. Marinescu, M. Delgado, K. Thurman, E. Khalili-Araghi, R. McGowan, L.M. Lin, P.A. RosenbergNew York University, New York, NY

Due to varied and sometimes contradictory reports, we completed a systematic review of randomized clinical trials concerning the efficacy of 2% Lidocaine and 4% Articaine. We considered: 1) onset of pulpal anesthesia after primary injections including: inferior alveolar nerve block, maxillary or mandibular infiltration, or intraligamentary injections; 2) incidence of paresthesia; and 3) use as a supplemental anesthetic after incomplete primary anesthesia. The literature was searched using MEDLINE, Embase, Web of Science, the Cochrane Database and Google Scholar, as well as hand-searching bibliographies of articles. Three-hundred and thirteen relevant papers were identified. Based on our inclusion/exclusion criteria, eleven papers were selected for review regarding onset of pulpal anesthesia, one paper was selected regarding supplemental anesthesia and there were no papers that met our criteria for review concerning paresthesia. Levels of evidence were assigned to each paper. The results of our review demonstrated significant variations in methodologies and findings, which posed a problem in performing a meaningful meta-analysis. There was insufficient research with a high level of evidence indicating overall superiority of either 2% Lidocaine with 1:100,000 Epinephrine or 4% Articaine with 1:100,000 or 1:200,000 Epinephrine when used as a primary or supplemental anesthetic. However, there was some evidence indicating that the efficacy of 4% Articaine is superior to 2% Lidocaine when used as a primary maxillary or mandibular infiltration technique in molar teeth.

PR 29The Effects of Lighting Conditions on Intra- and Inter-Interpreter Agreement for Digital RadiographsN. Lund*, P. Mines, A. AndersonU.S. Army Dental Activity, Fort Bragg, Fayetteville, NC

Background: In the past, conventional radiography has shown that using a viewing box and limiting other external light sources improves visibility and diagnosis. However, with the advent of digital radiography, using conventional film with the viewing box is being replaced with computer monitors or LCD screens. The objective of this study was to examine the effects of lighting conditions on the interpretation of digital radiographs viewed on an LCD monitor. Materials: A total of 2,400 periapical endodontic radiographs were viewed by four endodontic residents. Each examiner viewed 100 PA radiographs under normal lighting conditions and another 100 PA radiographs under darkened conditions per iteration. This was done for three iterations at one-month intervals. The examiners marked each radiograph as normal tissues or apical lesion present. Results: Our results showed that overall agreement between 4 examiners for lighted conditions was 71%. For darkened conditions it was 66.3%. This was shown not to be statistically significant p=0.40. The intra-interpreter agreement was averaged at 81.75% for light and 81.5% for dark conditions. This was also not statistically significant p=0.89. Conclusion: The lighting conditions of the viewing environment have no statistically significant effect on the inter- or intra-interpreter agreement when diagnosing periapical lesions on LCD screens.

e35JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 33Comparative Evaluation of Cone-Beam-Computed Tomography to Root Canal Staining and Clearing in the Study of Root Canal MorphologyP. Narayana*1, F. Vertucci2, M. Nair2, G.R. Hartwell1, U. Nair2

1University of Medicine & Dentistry of New Jersey, Newark, NJ, 2University of Florida, Gainesville, FL

Failure of root canal therapy has been attributed to the inability to cleanse and shape the complex root canal system present in many teeth. Historically, many different methods have been employed to study root canal morphology. The use of cone-beam-computed tomography (CBCT) for studying root canal anatomy has shown promising results and could become a useful tool in the diagnosis of challenging cases. The aim of this study was to compare CBCT images with a tooth-clearing technique for determining the root canal morphology of permanent teeth. The roots of 42 freshly extracted teeth, in groups of 3-6 teeth, were first covered with a putty impression material and then mounted in an acrylic block to simulate the clinical scenario. CBCT images of these blocks were obtained using a Kodak™ 9000 unit. After the images were taken, the teeth were removed from the blocks, root canals stained and roots cleared. Two separate examiners evaluated the CBCT scans and cleared teeth and identified the root canal morphology using Vertucci’s classification. Using the number of root canal systems identified in the stained, cleared group as the control, the CBCT scans identified all of the root canal systems in 39 of 42 teeth (92.8%). The inter-examiner agreement was 100%. Conclusion: The CBCT technology appears to be an effective method for identifying root canal morphology, and in this ex vivo study it was comparable to the results obtained with the staining and clearing technique.

PR 35An In Vitro Spectroscopic Analysis to Determine the Chemical Composition of the Precipitate Formed by Mixing Sodium Hypochlorite and ChlorhexidineJ.B. Nowicki*, D.S. SemMarquette University, Milwaukee, WI

Introduction: The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and chlorhexidine (CHX) and relative molecular weight of the components. Methods: Using commercially available chlorhexidine gluconate, a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate, as well as a mixture of precipitate and pure chlorhexidine diacetate, was then analyzed using 1D and 2D NMR spectroscopy. Results: The 1D and 2D NMR spectra were fully assigned in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of CHX breakdown products, including a lower molecular weight component of CHX that contained a parasubstituted benzene that was not parachloroaniline and contained no aliphatic linker. Conclusions: Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX, neither of which are parachloroaniline.

PR 36Adenosine Receptor Agonists Suppress sRANKL Production From Activated T CellsP.S. Ok*1, M.J.B. Silva2, M. Kajiya3, H.E. Mackler1, J. Hong1, R.R. White1, T.C. Pagonis1, M.A. Taubman3, T. Kawai3

1Harvard School of Dental Medicine, Boston, MA, 2Uberlândia, Brazil, 3Cambridge, MA

Background: Receptor activator of nuclear factor K B-ligand (RANKL) produced from activated T cells is implicated as a cause of pathogenic apical bone resorption. Recent studies revealed that extracellular adenosine (ADO) can down-modulate the T cell-mediated immune responses. Objective: The aim of this study was to investigate the effects of chemical agonists for four types of ADO-receptors (A1, A2a, A2b and A3), in comparison to ADO, on the production of soluble RANKL (sRANKL) from the in vitro-activated mouse T cells. Method: ADO and chemical agonists for ADO-receptors were applied to the T cells stimulated in vitro with immobilized anti-TCR and anti-CD28 monocloncal antibodies. After 3 days of incubation, sRANKL produced in the culture supernatant and proliferation of activated T cells was monitored by ELISA and 3H thymidine incorporation assay, respectively. Results: The extracellularly applied ADO (1 and 10 µM) inhibited the production of sRANKL from activated T cells by TCR/CD28 engagement. The A2b agonist (10 µM) showed the significantly higher inhibition of sRANKL production (Student’s t, p<0.05) compared to ADO and the other agonists tested, reaching 80% of inhibition compared to the no-drug control. All tested ADO-receptor agonists and, to a lesser extent, extracellular ADO suppressed the proliferation of TCR/CD28-activated T cells. Conclusion: The ADO-receptor agonists, especially A2b agonist, can suppress sRANKL production from the TCR/CD28-activated T cells as well as their proliferation, suggesting that ADO-receptor agonists may potentially lead to the development of novel therapeutic regimens for periapical bone resorption caused by T cell activation.

PR 34The use of Guided Tissue Regeneration Techniques Among Endodontists: A Web-Based SurveyJ.N. Naylor*, P. Mines, A. Anderson, D. KwonU.S. Army Dental Activity, Fort Bragg, Fayetteville, NC

Introduction: The purpose of this study was to determine the factors and clinical situations that influence an endodontist’s decision to use guided tissue regeneration (GTR) techniques during endodontic root-end surgery. Methods: An invitation to participate in a QuestionPro™ Web-based survey was e-mailed to 3,750 endodontic members of the American Association of Endodontists. The number of questions encountered varied from as little as 3 to as many as 11 depending on individual responses. Results: 33% (n=1,238) of recipients started the survey and with an 8.8% (n=109) drop-out rate, the survey had an overall 30.1% (n=1,129) completion rate. Our data indicates that 40.7% of respondents who perform root-end surgeries also utilize GTR techniques. Based on survey responses, the clinical situation in which GTR techniques are used most often is for through-and-through transosseous lesions. Barrier membranes and bone replacement grafts are each used by more than 85% of those respondents using GTR techniques. Insufficient training and insufficient evidence in support of its use were selected as the predominant reasons for not using GTR techniques at 42.4% and 32% respectively. Conclusions: While over 40% of respondents are currently using GTR techniques in conjunction with their root-end surgeries, a majority of those who do not utilize GTR indicated that they would consider using these techniques with better evidence and available training.

e36 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 39Assessment of Microbial Biofilm Proliferation Within Sealer-Root Dentin InterfacesK. Roth*, S. Friedman, C.M. Levesque, B. Basrani, Y. FinerUniversity of Toronto, ON, Canada

Background: The root canal filling is intended to prevent bacterial invasion and proliferation in the canal after treatment. Current endodontic sealers’ interfaces with dentin are not impervious to bacterial invasion and may degrade over time. Objective: To compare the quality of seal and degradation of the sealer-dentin interface of two methacrylate resin-based systems, self-etch (SE; RealSeal SE™, SybronEndo, Orange, CA) and total-etch (TE; Scotchbond™ MP, 3M, St. Paul, MN, Bisfil™ 2B, Bisco, Schaumburg, IL), and an epoxy resin-based sealer (EP; AH Plus™, DENTSPLY/DeTrey, Skarpnäk). Methods: Standardized specimens (n=45) comprising the coronal portion of human root dentin (the first challenged by bacteria invading the canals) were filled with the test materials and gutta-percha. Specimens were either not preincubated (control), or incubated for 7, 30, 90 or 180 days in sterile saline (n=3/group). Subsequently monoclonal biofilms of Enterococcus faecalis were grown on the specimens and sustained for 7 days in continuous media reactor mimicking pathogenic oral conditions. The quality of the sealer-dentin interface for each material at each incubation period was assessed by measuring the extent of biofilm proliferation within the interface using fluorescence microscopy of dihydroethidium-stained specimens. Results: Biofilms and bacterial cells within the sealer-dentin interface were identified for all materials. Biofilm proliferated significantly less (ANOVA/Scheffé, p<0.05) in TE than in SE and EP specimens. Incubation period significantly affected (ANOVA/Scheffé, p<0.05) bacterial invasion only for EP. Conclusion: Within the test model used, the self-etch and epoxy resin-based sealers were more susceptible to biofilm proliferation within the dentin interface than the restorative “gold standard” total-etch system. This study was supported by the AAE Foundation, Alpha Omega Fraternity, the Canadian Academy of Endodontics and EndoTech.

PR 40Evaluation of the Seal Provided by RealSeal™ and a New Experimental Sealer in Roots Filled With Resilon™

M.M. Saad*, P. Challagulla, F.C. Setzer, B. Karabucak, M. TropeUniversity of Pennsylvania, Philadelphia, PA

One desired property of an ideal sealer would be to provide a complete adhesive bond over the entire root length between the dentinal wall and the root filling material. The purpose of this study was the observational comparison of the seals created by Resilon™ with RealSeal™ and Resilon™ with a new experimental sealer (NES). Twenty single-rooted teeth were decoronated, roots prepared to a length of 15mm and instrumented to ISO #50. The roots were randomly divided into 4 groups and subsequently filled using lateral and vertical compaction techniques with Resilon™ and RealSeal™ (groups RRL and RRV) or Resilon™ and NES (groups RNL and RNV). Roots were left at 37°C in a humidified atmosphere of 5% CO

2 and air for 30 days. Two roots of each group were

then sectioned using a split tooth technique. For phase I, the split roots were examined for gaps along the canal walls and the core/sealer junction using a scanning electron microscope (SEM, JEOL JSM-T330A) at 25kV under varying magnifications (500x, 1000x) after 30 days. The remaining roots were left in 100% humidity for additional 120 days for scheduled examination under the SEM during phase II of the investigation. Preliminary results from phase I indicate the presence of a hybrid layer interface in all four groups. RNL and RNV showed better adaptation in the apical third compared to groups RRL and RRV. NES demonstrated good marginal adaptation and promises a superior seal over the entire root length.

PR 38Antibacterial Effectiveness of Triple Antibiotic Paste, 2% Chlorhexidine Gel and Calcium Hydroxide Against E. Faecalis in the Presence of Dentin Powder Using the Radial Diffusion Assay TechniqueR. Reese*, R. Duval, A. Mickel, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Implementation of endodontic irrigants and interappointment medicaments have significantly increased success rates of root canal treatment; however, antimicrobial efficacy of these materials decreases in the presence of dentin (Haapasalo, 2000). Triple antibiotic paste (TAP) has been used as a disinfectant and in regenerating procedures. We hypothesized that TAP would have greater antimicrobial efficacy in the presence of dentin compared with 2% Chlorhexidine gel (CHX) and calcium hydroxide (CH). The aim of this study was to compare the antimicrobial effectiveness of TAP, CHX and CH against Enterococcus faecalis and the inhibitory effects of dentin on the antimicrobial activity. Radial diffusion assay was used to determine zones of inhibition of E. faecalis in 144 samples. Antimicrobial efficacies of medicaments were tested individually and in combination with dentin powder (1.8%weight/volume). The medicaments were divided into: Group 1: TAP; Group 2: CHX; Group 3: CH; Group 4: phosphate-buffered saline (negative control); and Group 5: NaOCl 5.25% (positive control). Mean zones of inhibition were statistically analyzed with pair-wise comparison and two-way ANOVA. Results showed that TAP demonstrated significantly greater zones of inhibition (63.83mm) than CHX (37.81mm) and CH (14.90mm) (p<.0001). When mixed with dentin, TAP showed the greatest zone of inhibition (63.24mm) compared with all other groups (CHX 36.32mm, CH 14.27mm) (p<0001), there was no significant difference between TAP and the positive control (p>.05). Dentin powder inhibited the antimicrobial efficacy of all medicaments. TAP showed the greatest antimicrobial efficacy against E. faecalis compared to other medicaments. TAP may prove beneficial in cases where E. faecalis contributes to the persistence of periradicular pathosis and may be a suitable alternative to CHX and CH in these cases.

PR 37Comparison of Sealer Penetration and Adhesion of Gutta-Percha/AH-Plus® and Resilon/Epiphany® SE™ After a Final Rinse With EthanolS. Paravyan*, K.C. Jordan, S.A. Black, K.J. Replogle, A.M. Best, P.C. MoonVirginia Commonwealth University, Richmond, VA

The purpose of this study was to evaluate the effect of a final rinse of ethanol on bond strength and depth of sealer penetration in teeth obturated with gutta-percha (GP)/AH-Plus® (DENTSPLY, De Trey GmbH, Konstanz, Germany) or Resilon/Epiphany® SE™ (Pentron Clinical Technologies, LLC, Wallingford, CT). Extracted human anterior teeth (n= 32) were shaped to size 30, 0.06 taper using nickel-titanium rotary files and subjected to an identical irrigation protocol. Specimens were randomly divided into eight groups according to final irrigating solution (saline, 70%, 95% or 100% ethanol) and obturation material (GP/AH-Plus® or Resilon/Epiphany® SE™). A 2mm-thick slice was obtained by sectioning each obturated root at 3 and 5mm from the anatomic apex. The bond strength was determined using a micropush-out assay. Sealer penetration of AH-Plus® or Epiphany® SE™ was assessed using scanning electron microscopy. Data was analyzed using Student’s t-test. Regardless of the final rinse, the average push-out bond strength was significantly greater when using GP/AH Plus®. Among or Resilon/Epiphany® SE™ groups, a final rinse with 100% ethanol resulted in a significantly weaker bond strength than did a final rinse with 70% ethanol (p<0.001). Conclusions: 1) GP/AH-Plus® forms a stronger bond than does Resilon/Epiphany® SE™ under conditions of this study; 2) a final rinse with ethanol prior to obturation does not appear to enhance push-out bond strength with GP/AH-Plus®; and 3) push-out bond strength of Resilon/Epiphany® SE™ decreases with increased ethanol concentration in the final rinse. This study was supported by the AAE Foundation and Virginia Commonwealth University Department of Endodontics.

e37JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 41Feasibility Study of the Association of Endodontic Pathosis and AtherosclerosisJ. Seltzer*, M. Macek, A.F. FouadUniversity of Maryland, Baltimore, MD

Previous studies have shown that endodontic infection can accelerate the progression of atherosclerosis in a mouse model. The purpose of this study was to determine the feasibility of a clinical study to show the association of chronic endodontic infections and atherosclerosis. Collaboration with experts in vascular surgery, periodontics and epidemiology were necessary to undertake such a study. Patients of interest are those undergoing carotid endartectomy procedures. Two different power analyses were performed for a case-control design to determine the appropriate sample size, one based on a 1:1 and one on a 1:5 case:control ratio. The effect size used was based on epidemiological studies showing the association of cardiovascular disease and endodontic pathosis. Different control groups were considered: age-, race- and gender-matched dental patients or patients with arrhythmia, pacemakers, aneurysm, congenital heart defects or venous disease. The data supported the use of the latter group. The literature reviewed supported the use of the following confounding variables: education, income, body mass index, smoking, diabetes, hypertension, total cholesterol, missing teeth and periodontal health. Cases and controls must be examined for periapical lesions by clinical and radiographic examination to avoid using inadequate surrogates of disease. A 1:1 (case:control) power analysis was selected because of the equivalent difficulty in locating both cases and controls. The total sample size required would include 1,168 patients divided evenly between the cases and controls assuming a 1.4 odds ratio, alpha error 0.05 and power of 80%. Partaking in such a study would require significant resources and collaboration with appropriate expertise.

PR 44Prevalence and Accuracy of the Clinical Diagnosis of Vertical Root Fracture in Endodontically Treated Teeth: A Prospective StudyM.W. Tanious*, M. Goralczyk, D. Schulman, L. Fleisher, L. Busch, I. Shergill, L. Lin, G. Fisch, P.A. RosenbergNew York University, New York, NY

Vertical root fracture is a complication that may be associated with endodontically treated teeth. This prospective study was directed at determining the prevalence and accuracy of the clinical diagnosis of vertical root fracture in endodontically treated teeth. Teeth with a history of root canal therapy and designated for extraction were eligible for this study. Faculty determined the reason for extraction to be endodontic, periodontal, prosthetic or vertical root fracture. The extracted teeth were placed in sealed vials with sodium hypochlorite 5.2% for two weeks and then evaluated for vertical root fracture by an oral pathologist using an operating microscope with 8X magnification. We determined that the prevalence of vertical root fractures in failed endodontic cases was 7 out of 71 teeth (10%). Three teeth diagnosed clinically with vertical root fractures (VRF) prior to extraction were confirmed by microscopic examination. Fifty-five of 64 teeth were clinically diagnosed as not fractured, the diagnosis of which was confirmed by microscopic examination. Nine teeth were clinically diagnosed as fractured, but the diagnosis was not confirmed microscopically. Four teeth included in the study were not diagnosed as fractured prior extraction; however, on microscopic examination, a vertical root fracture was observed. Diagnostic sensitivity for VRF was 42%; specificity was 86%. Overall accuracy in diagnosis was 82%.

PR 42Reduction of Cultivable Bacteria in Root Canals After Sonic and Ultrasonic Adjunctive IrrigationA. Sethi*University of Pennsylvania, Philadelphia, PA

Sonic and ultrasonic agitation of irrigants after root canal instrumentation has been proposed as a method of further reducing intracanal microbes before root canal filling. This study tested the effectiveness of these methods in the reduction of intracanal microbes. Sixty teeth (30 per group) with confirmed necrotic pulps and apical periodontitis were used in the study. All teeth were instrumented and irrigated with NaOCl with a standard technique until predetermined final sizes were obtained. After instrumentation the canals were filled with 2.5% NaOCl and either sonic (Vibringe) or ultrasonic (Satalec) agitation was performed for 1 minute. After neutralizing the sodium hypochlorite, cultures were taken when the canal was opened (S1) after instrumentation (S2) and after sonic/ultrasonic agitation (S3). Instrumentation with sodium hypochlorite significantly reduced the number of bacteria in the canal (S1-S2). Both sonic and ultrasonic agitation further reduced the microbial count (S2-S3). Additional cases will be performed to evaluate any differences between sonic and ultrasonic agitation in regards to bacterial reduction.

PR 43Effect of Docosahexaenoic Acid, an Omega-3 Fatty Acid, on the Expression of IL-1ß, IL-6, IL-8, and TNFα in Normal and LPS-Treated MG-63 Human Osteoblasts Using Reverse Transcriptase-PCRP.D. Solanki*, A. Mickel, G. Jin, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Destruction of bone by osteoclasts is a major event in the pathogenesis of apical periodontitis. Their structure, regulation and coupling with osteoblasts (OBs) have been extensively studied. Osteoclastic activity can be mediated by pro-inflammatory cytokine production by osteoblasts. IL-1ß, TNFα, IL6 and IL8 are associated with human periapical lesions. Reducing the production of these cytokines may be beneficial for the treatment of periapical lesions. Oils rich in omega-3 fatty acids like DHA have been linked with anti-resorptive effects (Sun 2003) and bone-protective effects. The purpose of this study was to compare the effect of DHA on the expression of these cytokines by normal and LPS-treated OBs. We hypothesized that pretreatment of OBs with DHA decreases the expression of pro-inflammatory cytokines in normal and LPS-treated OBs. MG-63 human OBs were cultured. DHA (10 mg/ml dissolved in 100% EtOH) was added to OBs in a dose-dependent manner. OBs samples were added to the following groups (Gr) Gr 1: EtOH alone (negative solvent control); Gr 2: LPS alone (positive control); Gr 3: DHA(5 μg/ml); Gr 4: DHA(5 μg/ml) +LPS; Gr 5: DHA(10 μg/ml); Gr 6: DHA(10 μg/ml) +LPS. RT-PCR, normalized by expression of house-keeping gene ß-actin was used to measure cytokine expression. Results: DHA decreased basal expression of IL-1ß, IL6 and TNFα. In LPS treated OBs, DHA decreased production of IL-1ß, and IL 6 at 10 μg/ml. Paired t-test was used for statistical analyses, p<0.05. DHA decreased IL-1ß in: Gr 3 (p=0.005), Gr 5 (p=0.012) and Gr 6 (p=0.049). DHA decreased IL6 in: Gr 4 and Gr 6(p=0.013). Conclusion: DHA at higher concentrations may inhibit bone resorption by decreasing proinflammatory cytokine production and may have a therapeutic use for treating apical periodontitis.

e38 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 48Study of Spatial Relationships Between the Root Apices of Maxillary Anterior Teeth and the Floor of the Nasal Cavity Using Cone-Beam-Computed TomographyJ. Wilde*, T. Ahmad, A. Mickel, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

Cone-beam-computed tomography (CBCT) provides three-dimensional images in a single 360° rotation and is more accurate than periapical and panoramic films. Due to the close proximity of apices of the maxillary anterior teeth to the floor of the nasal cavity (da Silva 1982), there is a potential danger involved in the perforation of the nasal cavity during periradicular surgery. The purpose of this study was to utilize CBCT to study the spatial relationships between the apices of maxillary anterior teeth and the floor of the nasal cavity. It was hypothesized that CBCT can be used to measure the distances between the apices of the maxillary anterior teeth and the floor of the nasal cavity and there would be no significant differences between gender- and age-specific groups of subjects. Data was collected from existing tomograms of 140 subjects at the dental school. Each patient had measurements from the apex to the floor of the nasal cavity for the 6 maxillary anterior teeth. Male and female subject between the ages 14 and 40+ were compared using two sided t-tests. Results showed the mean distance between the floor of the nasal cavity and apices to be: maxillary centrals (6.41mm), maxillary laterals (7.02mm), and maxillary canines (5.25mm). There was a statistically significant difference between 14-year-old group (5.16mm) and 40+-year-old group (7.29mm) (p<0.0001), and between the males (6.94mm) and females (7.65mm) in the 40+ group (p<0.0001). In conclusion, CBCT is a useful tool for presurgical planning of maxillary anterior teeth.

PR 47A Comparison of Cone-Beam-Computed Tomography Scans and Direct Digital Radiography in Detecting Experimental Lesions on Radicular Tooth StructureB. Webb*, J. Ferrari, A. Mickel, A. Aminoshariae, T. MontagneseCase Western Reserve University, Cleveland, OH

External resorption is often first detected radiographically. Early detection leads to timely intervention and improvement of treatment outcome. The purpose of this study was to assess the diagnostic ability of cone-beam-computed tomography (CBCT) scans and direct digital radiography (DDR) to detect the size, buccal-lingual location and coronal-apical position of experimental lesions on radicular tooth structure. We hypothesized that CBCT scans are more accurate in determining size and location of radicular lesions than DDR. One-hundred and twenty lesions were created on 60 extracted human premolar teeth, using a high-speed handpiece with a ½, 2 or 4 round bur. Teeth were secured on sawdust mandibles and radiographic images were obtained using CBCT and DDR. Three blinded observers independently evaluated the images. Positive predictive value and accuracy of CBCT and DDR radiographic imaging systems were calculated and reported. A Chi-square test was used to test for difference between the systems. Observer accuracy was calculated and the inter-observer agreement was assessed using kappa statistics. Overall accuracy of CBCT (93.71%) in detecting radicular lesions was statistically significant (p<0.001) versus DDR, which was 71.94%. Overall accuracy for location and position of the lesions detected using CBCT was 97.62% and 99.40%; while using DDR, percentages were 70.48% and 89.10% respectively. These findings were also statistically significant (P<0.001). Comparing the accuracy of measurement, matched pair t-test showed that CBCT was significantly more accurate than DDR (p<0.0001). We concluded that CBCT demonstrated a significantly higher accuracy in determining the size, location and position of artificially created lesions on radicular tooth structure.

PR 46Comparison of Fracture Resistance in Simulated Immature Root Canals After Filling With Various Obturating MaterialsB.J. Vos*, A.E. Williamson, J.L. Kolker, D.R. DrakeUniversity of Iowa, Iowa City, IA

Immature anterior teeth needing root canal treatment have been shown to be susceptible to horizontal fracture. Different materials: composite resin, GP and MTA have been suggested to increase a tooth’s resistance to horizontal fracture when used as an obturating material. EndoSequence™ Root Repair Material Putty™ (ERRMP, Brasseler USA, Savannah, GA) has a chemical composition similar to MTA, but has yet to be tested as a standalone obturating material. This study aimed to evaluate the influence various obturating materials have on fracture resistance in endodontically treated, immature teeth. Forty extracted maxillary anterior teeth were collected. Standard root lengths gained by resecting the apical thirds 10mm from the facial CEJ. Teeth were accessed and instrumented with GG 2-6, simulating immature root structure. Groups obturated as follows: 1) Unobturated—positive controls, 2) GP, 3) Apical 1/3 with MTA and remaining canal filled with resin composite, 4) ERRMP™ and 5) MTA. Access openings in Groups 2-5 restored with resin composite. Teeth were stored in distilled water at 25°C for 14 days to allow setting of obturating materials. After setting, samples were mounted in cylindrical acrylic blocks and tested for fracture strength at the cervical area in a Zwick™ (Zwick/Roell, Ulm, Germany) testing machine. Preliminary results showed increased force to fracture in Groups 3-5 compared to 1 and 2. Group 3 required the most force to fracture. When endodontically treating immature anterior teeth, obturations with an MTA plug and resin composite, or complete obturation with MTA or ERRMP™ may increase the tooth’s resistance to horizontal fracture. This study was supported by the AAE Foundation and Brasseler USA.

PR 45Is Revascularization a Predictable Procedure?F.T. Tayebaty*, P.A. Rosenberg, L.M. LinNew York University, New York, NY

The goal of revascularization of immature permanent teeth with apical periodontitis/abscess is to induce thickening of the canal walls and continued root development. Twenty immature permanent teeth with apical periodontitis/abscess were included in this case series study. The patients’ ages ranged from 8-21 years of age. After access opening, canals were irrigated with 3.25% sodium hypochlorite without mechanical instrumentation. A triple antibiotic mixture (Ciprofloxacin, Metronidazol and Minocycline) was used in 3 cases and calcium hydroxide was used in 17 cases as an intracanal medication between visits. Following induction of bleeding into the canals, the coronal portion of the canals were sealed with Mineral Trioxide Aggregate (MTA) and composite resin. The cases were followed up from 3 to 26 months. All 20 teeth showed radiographic evidence of periapical wound healing and clinical evidence of disappearance of signs and symptoms. Seventeen teeth (14 teeth treated with Ca(OH)

2 and 3 teeth treated with triple antibiotic mixture)

showed radiographic evidence of increased thickening of the canal walls. However, 6 of those teeth did not demonstrate significant continued root development. Four of those teeth exhibited almost complete pulp canal obliteration. Neither increased thickening of the canal walls, nor continued root development were observed in 3 teeth in adult patients (all treated with Ca(OH)

2). Under the conditions of this

case series, revascularization of immature permanent teeth was found to be an unpredictable procedure. It is possible that a larger sample or longer follow-up period might alter these findings.

e39JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 49Endodontic Treatment Outcomes: Five-Year Follow-up of Teeth Obturated With Resilon™ and Gutta-PerchaD. Worrell*, P. Mines, A. AndersonU.S. Army Dental Activity, Fort Bragg, Fayetteville, NC

Introduction: The purpose of this retrospective study was to evaluate the five-year treatment outcome of root canal systems obturated with gutta-percha and AH Plus™ sealer compared with Resilon™ and Epiphany™ sealer. Methods: Clinical data was obtained using a retrospective chart review of over 400 teeth endodontically treated by a single, experienced resident. The same contemporary instrumentation techniques were utilized for each tooth. The data was separated into Resilon™- and gutta-percha-obturated groups. Survival was defined as radiographic evidence of the treated tooth being present in the mouth at least 60 months after initial treatment. The effects of variables such as age, race, sex and presence of a preoperative lesion on treatment outcome were examined. Additionally, the outcomes of single- and multiple-visit treatment were compared. Finally, the difference between treatment outcomes with Resilon™ compared to gutta-percha was analyzed using the χ2 test. Results: There was an overall five-year survival rate of 89% with the gutta-percha group as compared to 88% in the Resilon™ group. The hypothesis that there was a difference in survival between teeth treated with gutta-percha and Resilon™ was rejected (χ2 = 0.0201, P>.05). Conclusion: There was no statistically significant difference found in the five-year survival of root canal systems obturated with gutta-percha and AH Plus™ sealer and Resilon™ and Epiphany™ sealer.

PR 51Comparing Canal Transportation and Centering Ability of Vortex and Sequence Rotary Files Using Microcomputed TomographyB.T. Yamamura*, J.D. Johnson, N.M. Flake, A. ParanjpeUniversity of Washington, Seattle, WA

Maintaining canal morphology during rotary instrumentation is a critical aspect in endodontics that could possibly influence treatment outcome. Many different rotary file systems have been introduced in the past decade, two of which are the nickel-titanium Sequence™ files and the M-wire ProFile Vortex™ files. The purpose of this study was to compare canal transportation and centering ability of the Vortex™ and EndoSequence™ files in the mesial roots of extracted mandibular molars with curvatures between 20-30 degrees. Preoperative microcomputed tomography (Micro-CT) scans of 16 mandibular molars were recorded and randomly assigned to two groups. In group 1, the mesiobuccal (MB) canals were instrumented with Vortex™ files and the mesiolingual (ML) canals instrumented with Sequence™ files. In group 2, the MB canals were instrumented with Sequence™ files and the ML canals with Vortex™ files. All canals were instrumented to size 30.04, then 40.04 and scanned at each size. The reconstructed 3-D images before and after instrumentation were superimposed on each other and canal transportations and centering abilities were calculated at 1, 3, 5 and 7mm for both mesial canals. The results demonstrated no statistically significant differences between the Vortex™ and Sequence™ files in centering ability or canal transportation at any of the measured levels, except at 7mm where the Vortex™ 40.04 files had less transportation (.0909mm) than the Sequence 40-0.04 files (0.16mm) (p<0.05). Overall, the results of this study indicate that there is no difference in centering ability or amount of transportation between the 30.04 or 40.04 Vortex™ and Sequence™ rotary files in curved mandibular mesial canals.

PR 50The Antimicrobial Efficacy of Berberine Against Endodontic Pathogens in a Multi-Species Biofilm Tooth ModelQ. Xie*, B. Johnson, C. WuUniversity of Illinois at Chicago, IL

Berberine is an isoquinoline derivative alkaloid isolated from medicinal herbs. Our previous study has shown that berberine, when used as an endodontic irrigant, exhibited bactericidal effect against Enterococcus faecalis biofilm in an in vitro tooth model. The purpose of this investigation was to evaluate the antimicrobial efficacy of berberine against selective endodontic pathogens using a multi-species biofilm tooth model. Methods: The bacterial species used in the multi-species biofilm tooth model were Fusobacterium nucleatum, Enterococcus faecalis, Porphyromonas gingivalis and Prevotella intermedia. Seventy-five extracted human anterior teeth were collected and standardized to 13.0mm length. Teeth were cultured in Schaedler Broth with the 4 test bacteria for 20 days and randomly assigned to 5 treatment groups according to the irrigants (sterile saline, 5.25% NaOCl, 1% CHX, 2mg/ml Berberine, and 2mg/ml Berberine plus 1% CHX). Teeth were instrumented to ISO size 40 and irrigated with 5ml of irrigant for 2 minutes and survival bacterial were sampled before and after instrumentation. Data were analyzed using ANOVA (p<0.05), followed by the Scheffé test. The MIC of Berberine against F. nucleatum, P. gingivalis, P. intermedia and E. faecalis was 31.25 µg/ml, 3.8µg/ml, 2µg/ml and 500µg/ml, respectively. Instrumentation and irrigation resulted in 99% bacterial reduction in all groups, with Berberine=NaOCl=CHX with regard to reduction in canal bacteria; while Berberine +CHX>NaOCl>CHX>Berberine in terms of bacterial reduction in dentin. Berberine is effective as an endodontic irrigant against selective endodontic pathogens in vitro, and when combined with CHX is comparable to NaOCl in its bactericidal efficacy.

PR 52microRNAs: Novel Players in the Regulation of Endodontic DiseasesS. Zhong*, S. Nares, K. Moss, A. KhanUniversity of North Carolina, Chapel Hill, NC

microRNAs are regulators of gene expression and are thought to play an important role in modulating inflammation. To date, there are no published studies evaluating the expression of microRNAs in the human pulp and periapical tissues. The purpose of this study is to investigate the existence of microRNAs in healthy and diseased pulpal and periapical tissues, and then to explore the functional gene targets. We hypothesize that inflamed pulp and periapical tissues will differentially express microRNAs compared to normal pulp and periodontal tissues. After obtaining informed consent, we collected samples of normal and inflamed pulp and periodontal tissues from endodontic patients (N=40). Microarray and molecular biology techniques were then used for gene profiling and identifying functional gene targets. Our preliminary data showed differential expressions of microRNAs between normal and inflamed pulp and periapical tissues. Association between dental pain and microRNAs expression will eventually be explored by logistic regression. These data provide new insights into the pathogenesis of endodontic diseases and may facilitate the development of new pathways of prevention and treatment.

e40 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 56Healing of Apical Periodontitis After Endodontic Treatment: A Comparison Between a Silicone-Based and a Zinc Oxide-Eugenol-Based SealerR. Caicedo*1, S.J. Clark1, D. Ørstavik2

1University of Louisville, KY, 2University of Oslo, Norway

The purpose of this research was to assess the treatment results up to 1 year after endodontic treatment of apical periodontitis using GuttaFlow™, (GF) in comparison with RoeKoSeal™, (RS) and Grossman’s sealer (GS), and to compare the results at 3 months after treatment with the 12-month follow-up to assess the prognostic value of a 3-month control. A total of 225 teeth were treated at four centers. The method of instrumentation was at the discretion of the operator, but with minimum ISO 35 for apical instrumentation. A standardized 0.4 gutta-percha master point was used with a sealer and cold lateral condensation. The quality and extension of the root filling was assessed radiographically. Periapical status was evaluated using the periapical index (PAI). Statistical analyses were done by the use of simple, nonparametric analyses including Chi-square and ridit analysis. Average PAI scores decreased from 3.5 preoperatively to 2.3 at 12 months for GS, 3.5 to 2.35 for the RS, and from 3.6 to 2.0 for GF. The 3-month control was adequate in establishing significant healing in all groups. Ridit and average PAI values indicate better healing with GF, whereas results with improvement/success are identical. Root filling after a standard treatment protocol of teeth with apical periodontitis is as successful using GF compared with RS and GS. This study was supported the Nordic Institute of Dental Materials.

PR 55Comparison of Gene Expression Profiles of Human Pulp Cells Treated With Mineral Trioxide Aggregate and Calcium HydroxideK. Bae*1, S. Yang2, Y. Kim1

1Seoul National University, Seoul, South Korea, 2Seoul, South Korea

This study investigated changes in gene expressions concerning differentiation, proliferation, mineralization and inflammation using Human-8 expression bead arrays™ (Illumina, Inc., San Diego, CA) when white Mineral Trioxide Aggregate™ (WMTA; DENTSPLY Tulsa Dental Specialties, Tulsa, OK) and calcium hydroxide-containing cement (Dycal™; DENTSPLY Caulk, Milford, DE) were applied in vitro to human dental pulp cells (HDPCs). WMTA and Dycal™ in a Teflon tube (inner diameter 10mm, height 1mm) were applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 3, 6, 9 and 24 hrs after WMTA and Dycal™ application. The results of microarray were confirmed by RT-PCR. Out of the 24,546 genes, 43 genes (e.g., BMP2, FOSB, THBS1, EDN1, IL11, COL10A1, TUFT1 and HMOX1) were upregulated greater than twofold and 25 genes (e.g., SMAD6, TIMP2, DCN, SOCS2, CEBPD and KIAA1199) were downregulated below 50% by WMTA. Two-hundred thirty-nine genes (e.g., BMP2, BMP6, SMAD6, IL11, FOS, VEGFA, PlGF, HMOX1, SOCS2, CEBPD and KIAA1199) were upregulated greater than twofold and 358 genes (e.g., EDN1 and FGF) were downregulated below 50% by Dycal™. Both WMTA and Dycal™ induced changes in gene expressions related with differentiation and proliferation of pulp cells. WMTA induced changes in gene expressions related with mineralization, and Dycal™ induced those related with angiogenesis. The genes related with inflammation were more expressed by Dycal™ than by WMTA. It was confirmed that both WMTA and Dycal™ were able to induce gene expression changes concerned with the repair of the pulp and they may affect the repair in different ways.

PR 54Evaluation of Mechanical Allodynia Using the Bite Fork™ in Patients With Irreversible Pulpitis and Acute Periradicular Periodontitis: Anesthetic Efficacy and the Effect of AnxietyD. Vazemiller, E.H. Bae*, R. Ortiz, P.A. RosenbergNew York University, New York, NY

A digital force transducer (Bite Fork™) has been shown to reliably measure mechanical pain thresholds of teeth. Normal teeth contralateral to teeth with irreversible pulpitis (IP) and acute periradicular periodontitis (APP) were found to have lower mechanical pain thresholds than those observed in healthy volunteers, providing evidence that central sensitization occurs during this type of odontalgia. This study examined the hypothesis that anxiety, local anesthesia, age, gender and ethnicity could affect mechanical allodynia in teeth with IP with and without APP (n=57). This study found no statistically significant difference in bite force due to gender, ethnicity or age. There was a statistically significant difference in the bite force of patients with IP (with or without APP) and contralateral healthy teeth, as well as between IP teeth and normal teeth of healthy volunteers (p<0.001 all pairs). After successful local anesthesia, both inflamed teeth and contralateral healthy teeth demonstrated significantly stronger bite forces when compared to the bite forces prior to local anesthesia (both p<0.001). The mean bite force of inflamed teeth after local anesthesia remained significantly lower by 31% when compared with the bite force of contralateral healthy teeth (p<0.001). Furthermore, subjects with lower 100-mm VAS anxiety levels, bit significantly harder with their contralateral healthy teeth than subjects with higher VAS levels (p<0.04). As pain from an inflamed pulp increases, the patient’s anxiety level increases and influences the biting force and the presence of allodynia. This study indicates that anxiety and central sensitization may be factors in mechanical allodynia.

PR 53A Comparative Study of Rotary Instrumentation of the Maxillary First Premolar Buccal Root Utilizing Cone-Beam-Computed TomographyS.J. Zigo*, K.J. Replogle, S.A. Black, A.M. BestVirginia Commonwealth University, Richmond, VA

Introduction: The objective of this study was to determine dentinal wall thickness on the lingual aspect of the buccal root in maxillary bifurcated first premolars after preparation with three successively larger, 0.04 tapered, nickel-titanium rotary files and to relate the amount of remaining dentin to the presumed standard for minimal dentinal wall thickness. Methods: Ten extracted human teeth were accessed and mounted in a custom mounting jig. A preoperative series of images were obtained using cone-beam-computed tomography. The dentinal wall thickness along the furcation groove of each tooth was recorded at three specific locations. Each tooth was instrumented with three 0.04 taper file sizes (30, 35 and 40). Teeth were scanned and residual dentinal wall thickness was recorded for each file size at the specified locations. Data was analyzed using ANOVA. Results: Instrumentation resulted in a significant reduction in the residual dentinal wall thickness (p<.001). At mid-groove, the predicted wall thickness (95% CI) was 0.50mm, 0.39mm and 0.30mm for file sizes 30, 35 and 40, respectively. The predicted dentinal wall thickness was equal to or less than the presumed adequate standard (0.50mm). Conclusions: Instrumentation of the buccal root in bifurcated maxillary first premolars mid-root reduces dentinal wall thickness to levels which may be insufficient to ensure tooth integrity. This study was supported by the AAE Foundation and the Virginia Commonwealth University Department of Endodontics.

e41JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 58Evaluation of the Correlation of Images of Positron Emission Tomography With the Periradicular Alterations of the Oral CavityH. Davidowicz*, A.P. Carvalho, A.A.M. MouraSão Paulo, Brazil

The present study evaluated the correlation of images of positron emission tomography (PET/CT) with the periradicular alterations of oral cavity observed or not observed in radiograph exams. Two-hundred and fifty-six dental upper and lower areas were analyzed trough clinical exam, panoramic and periapical radiograph exam followed by PET/CT. In all patients, image was obtained 30 min after intravenous administration of 370 MBq of 18F-Fluoride (adult patient with approximately 70Kg). The image protocol included images from the top of the head to the neck. A nuclear physician and an endodontist analyzed the images. After the image analyzes, statistics were done. In the results obtained through radiograph exams with the panoramic technique 6 positive images were found, in a total of 2.34% of the total sample. The intrabuccal radiograph exam by the periapical technique showed 7 positive images in a total of 2.73% of the total sample and PET exam revealed 39 positive images, corresponding to 15.23% of the total studied areas, showing statistical significance by the level of 5% of variance analyses when compared the results obtained through PET/CT with the radiograph exams and the panoramic and periapical techniques. PET allowed us to indentify endodontic infections in a larger number when compared with the radiograph exams; the radiograph exams by the periapical technique identified endodontic infections in a larger number when compared with the panoramic technique and PET/CT, which allowed the union of precocity diagnosis with the image detail, presenting the exact location of inflammatory/infectious alterations due to the presence of the CT.

PR 60In Vitro Assessment of the Endodontic Auxiliary Chemical Substances Influence on the Immediate and Mediate Bond Strengths Between Adhesive and Root Canal DentinS.T. Kawagoe, J.F.A. Almeida, B.P.A. Gomes, A.A. Zaia, C.C.R. Ferraz*UNICAMP-Piracicaba, São Paulo, Brazil

Adhesively luted fiber-reinforced composite posts have been increasingly used for the restoration of endodontically treated teeth. However, the influence of the auxiliary chemical substances used during the root canal treatment on the adhesive strength need greater clarification. The objective of the present study was to examine the immediate and mediate adhesive strength of 2 adhesive systems (Scotchbond Multi Purpose™, 3M, St. Paul, MN and Clearfil SE Bond™, Kureray Co., Ltd., Osaka, Japan) applied in radicular dentin treated with different auxiliary chemical substances (2% chlorhexidine gel, EDTA 17% and 5.25% sodium hypochlorite (NaOCl) associated or not to sodium ascorbate 10%), and evaluate the importance of the collagen fibers in adhesion process. The shear bond strength was assessed after 1 day or 1 year in water immersion. As longevity control, part of the sample was kept submerged in mineral oil for 1 year. Shear bond strength was analyzed by ANOVA and Tukey comparison at 0.05 significance level. Subsequently, the fracture pattern was analyzed using a stereomicroscope (25 X), and classified as: adhesive (dentin/resin interface), cohesive (in dentin, layer hybrid resin or post) or mixed (involving 2 or more substrates). After the data analysis it was concluded that: the Scotchbond Multi Purpose™ presented the highest adhesive resistance. The NaOCl reduced the immediate adhesive resistance when used as an endodontic auxiliary chemical substance or when employed in deproteinization. The use of sodium ascorbate after using the NaOCl re-established the adhesion values. The deproteinization and chlorhexidine use kept the adhesive strength values unchanged after 1 year. This study was supported by Fundacão de Amparo ã Pesquisa do Estado de São Paulo.

PR 59Inhibitory Signals Mediated by Programmed Death-1 are Involved With T-cell Function in Chronic Periapical PeriodontitisR.J.R. Delgado*, T.H. Gasparoto, C.R. Pinheiro, C.R. Sipert, I.G. Moraes, R.B. Garcia, C.M. Bramante, N. Bernardineli, G.P. Garlet, J.S. Silva, A.P. CampanelliUniversity of São Paulo-Bauru, Brazil

Inhibitory signals mediated by programmed death-1 involved with T-cell function in chronic periapical periodontitis. Inhibitory signals mediated via molecules such as programmed death-1 (PD-1) play a critical role in downmodulating immune responses and maintaining peripheral tolerance. We investigated the involvement of cytokines and PD-1 engagement in mediating the T-cell activation in chronic periapical diseases. Gingival samples from healthy individuals and patients with chronic periapical periodontitis were collected and used for the subsequent assays. The leukocytes in the lesion site were evaluated using flow cytometry. The production of interferon-gamma (IFN-Y), interleukin (IL)-10 and transforming growth factor-beta (TGF-ß) proteins was evaluated by ELISA. T-cells from patients expressed significantly higher levels of PD-1. In addition, CD4+ and CD8+ T-cells expressing PD-1 accumulated in lesions with chronic periapical periodontitis. Moreover, PD-L1 expression was intense in macrophage from patients. Our data clearly showed that lesions samples contained elevated amounts of TGF-ß, IL-10 and IFN-Y when compared with healthy gingival tissue from control individuals. These data show that PD-1 engagement could be involved in the modulation of T-cell activation in patients with chronic periapical periodontitis.

PR 57The Outcomes of Replanted Permanent Teeth After Avulsion InjuryY. Chen*, S. Yang, Y. Sun, Y. Ho, Y. HsuTaipei, Taiwan

Avulsed permanent teeth following replantation are at risk for root resorption. The aim of this retrospective study was to analyze the outcomes of replanted permanent teeth after avulsion injury using patients from Taipei Veterans General Hospital. Thirty permanent teeth in 24 patients aged 9 to 73 years (mean 24 years) were replanted after avulsion injury with follow-up visits conducted up to 6 months. Standard radiographs and clinical examinations were given at both root canal sealing and follow-up visits. The outcomes from combined clinical and radiographic findings included normal periodontal healing, replacement resorption and inflammatory resorption. The results at root canal sealing included 11 teeth (36.7%), 2 teeth (6.7%), 14 (46.7%) and 3 teeth (10%) for normal periodontal healing, replacement resorption, inflammatory resorption, and combination of inflammation and replacement resorption, respectively; during follow-up visits, the outcomes were 16 teeth (53.3%), 5 teeth (16.7%), 5 teeth (16.7%) and 4 teeth (13,3%) for conditions in the same order. After 6-month recall, inflammatory root resorption in the replanted permanent teeth after avulsion injuries tended to decrease. This study was supported by the Taipei Veterans General Hospital.

e42 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 62Propolis Inhibits Osteoclastic Activity via Cyclooxygenase PathwayA. Harris*, L. Holliday, R. PileggiUniversity of Florida, Gainesville, FL

Propolis has been demonstrated to exert biological effects by inhibiting expression of osteoclastic activity. However, the mechanisms of this inhibitory activity is still unclear. This study evaluated the effects of propolis on osteoclast formation and activity and whether propolis affects the inhibition of osteoclast maturation via the cyclooxygenase (COX) pathway. Osteoclasts were generated by stimulating mouse marrow with calcitriol. Osteoclasts were identified by staining for tartrate-resistant acid phosphatase (TRAP) activity. Resorption activity was monitored by formation of actin rings and by the formation of pits on bone in the presence or absence of propolis. Additionally, an EP4 agonist was used to bypass the cyclooxygenase pathways. Results demonstrated that osteoclastogenesis stimulated by calcitriol was sharply reduced in the presence of COX inhibitors. Addition of prostaglandin to the COX inhibitor treatment rescued the osteoclast formation. Notably, propolis reduced calcitriol-stimulated osteoclastogenesis (P<0.05). Treatment with prostaglandin and COX inhibitor failed to rescue osteoclast formation in the presence of propolis. Treatment of pure osteoclast precursors with propolis reduced the growth rate and giant cell formation (P<0.05). In addition, propolis inhibited the formation of actin rings which is a marker for osteoclastic bone resorption and pit formation. In conclusion, these data indicate that propolis contains elements that block osteoclastogenesis and osteoclast activity downstream of COX activity.

PR 61Bacteria and Endotoxin Detected in Primary Endodontic Infection With Apical PeriodontitisF.C. Martinho, A.A. Zaia, C.C.R. Ferraz, J.F.A. Almeida, B.P.A. Gomes*UNICAMP-Piracicaba, São Paulo, Brazil

Gram-negative bacteria and endotoxins are implicated in the development of clinical symptomatology and bone destruction in apical periodontitis. The objectives were to investigate Gram-negative bacteria species and the levels of endotoxin in primary endodontic infection, correlating both with the clinical symptomatology and bone destruction. Samples were taken from 21 root canals with paper points. PCR technique (16S rDNA) was used for the detection of 11 Gram-negative and 2 Gram-positive target species. Limulus Amebocyte Lysate was used to measure endotoxin. Prevotella nigrescens (13/21), Porphyromonas endodontalis (6/21) and Treponema socranskii (6/21) were frequently detected. Positive associations were found between P. endodontalis and Treponema denticola; Parvimonas micra and Filifactor alocis (Pearson’s Chi-squared: all p<0.05). Teeth with exudate (12/21) were related to the detection of P. nigrescens (Pearson’s Chi-square test: p<0.05). The LAL assay indicated that endotoxin was present in 100% of the root canals samples (21/21) with the median value of 7,490 pg/mL (27 pg/mL to 289.000 pg/mL). A higher median value of endotoxin contents was detected in teeth with radiolucent area ≥ 2 mm - 9.190 pg/mL (n=11) than <2 mm - 3,480 pg/mL (n=10) (Pearson’s correlation coefficient - p<0.05). Teeth with exudation presented higher median levels of endotoxins (9.190 pg/mL) than teeth with no exudation (3.480 pg/mL). Our findings indicate an additive effect between Gram-negative bacteria species involved in primary endodontic infection regarding the presence of clinical symptomatology. Moreover, higher levels of endotoxin were related to bone destruction. This grant was supported by the Fundacão de Amparo ã Pesquisa do Estado de São Paulo and the Counselho Nacional de Desenvolvimento Científico e Tecnológico.

PR 64A Histological Study on Nanobacteria-Like Organisms in Calcific Substances of Dental PulpN. Hosoya*, T. Ishibashi, T. Yoshida, S. Shimoda, T. AraiTsurumi University School of Dental Medicine, Yokohama, Japan

The ectopic calcifications in dentistry are manifested as pulp stones or denticles. However, in most cases their origin is still not clearly identified. Since nanobacteria-like organisms (NLO) have been implicated in various kinds of calcification lesions caused, there is a possibility that NLO may have a role in the formation of pulp stones or the denticles. The purpose of this study was to investigate participation of NLO in pulp stones or denticles by observation with a transmission-electron microscope. Having obtained the consent from the human subjects, pulp chambers or root canals of 122 extracted teeth were observed by a micro-CT. A total of 49 teeth that showed calcific substance in pulp chambers or root canals, were selected as samples for this study. The sample teeth were divided for observation of the pulp tissue. After embedding in epoxy resin, histological observation was performed with a transmission-electron microscope. Calcifications were found in 49 teeth that were examined with micro-CT. The ectopic calcifications showed various kinds of forms. The pulp tissue exhibited a range of histological features, from normal to pulp tissue with degenerative changes. In the denatured necrotic pulp tissue, most of the pulp cells and the collagen fibers could not be recognized and images with many oval-shaped NLO structures and electron dense granules were scattered in a ring shape having diameters of 10-30 nm. It was suggested that calcification mechanism by NLO participated in the calcification denaturation of the dental pulp and the pulp stone.

PR 63Light Attenuation of Fiber Post SystemsY.C. Ho*1, S.F. Yang2, S.F. Pai1, S.Y. Lee1

1National Yang-Ming University, Taipei, Taiwan, 2Taipei, Taiwan

Fiber posts consist of unidirectional fibers embedded in a resin matrix. The aim of this study was to analyze the influence of the composition of fiber post on light attenuation. Six post systems (n=10/group), similar in geometric properties and length, were enrolled. After embedding the post in custom-made black box, the irradiances, with LED light-curing unit, were measured by a photoconductive cell at 1 mm intervals along the post laterally as well as vertically. Digital photographs of each irradiated post were also taken in a completely dark environment. There was a good exponential relationship (regression analysis, R2>0.95) between the depth and light irradiance in every post laterally and vertically. The post type and post level were significant factors for light attenuation (p<0.05, two-way ANOVA). The quasi attenuation coefficient laterally and vertically were: Parapost® Fiber Lux™ (0.59, 0.31), FRC Postec® Plus™ (0.61, 0.21), FibreKor™ (1.05, 0.72), Parapost® Fiber White™ (1.16, 0.63), D.T. LIGHT-POST™ (0.26, 0.08), and X·post™ (0.40, 0.12), respectively. The results showed that light attenuated from coronal to apical level, and lateral attenuation along the post was faster than vertical attenuation. Within the limitation of this study, the post systems which consist of quartz fiber and epoxy resin showed less light attenuation. The light attenuation of fiber posts is related to the variety of optical properties of fiber and resin matrix. The dramatically light attenuation along the post laterally may impair the polymerization of surrounding dual-cured resin cement. This study was supported by National Health Research Institutes, Taiwan.

e43JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 66An In Vitro Evaluation of Resin-Based Sealers on Proliferation and Osteogenic Differentiation of Human Periodontal Ligament CellsH. Maeda*Fukuoka, Japan

Resin-based sealers exhibit high sealing ability; thus, they are useful for endodontic treatment. Some reports concerning cytotoxicity of the eluent from these sealers, however, have been presented. The purpose of this study was to evaluate the effects of a polymethyl methacrylate resin-based sealer (Superbond Sealer™, SB) on proliferation and osteogenic differentiation of human periodontal ligament cells (HPLCs) in vitro, compared with an epoxy resin-based sealer (AH Plus™, AH). HPLCs were obtained from two patients with informed consent. SB or AH discs washed for 7 days after setting (washed) or unwashed discs just after setting for 24 hr (unwashed) were prepared. Cells cultured on these discs were evaluated by scanning electron microscopy (SEM) and WST-1 proliferation assays. The osteogenic differentiation of HPLCs cultured on these discs was examined by gene expression analysis of osteopontin (OPN) and osteocalcin (OCN) by quantitative RT-PCR. HPLCs exhibited growth on washed SB discs, whereas unwashed SB and AH discs and washed AH discs inhibited their proliferation. SEM observation revealed that HPLCs tightly attached onto the surface of washed SB discs, although few cells were observed on other discs. HPLCs significantly upregulated gene expression of OPN and OCN when cultured on washed SB discs in osteogenic differentiation medium for 2 weeks whereas other discs did not induce their differentiation. These results indicate that, although SB initially exerted cytotoxic effects on HPLCs, these effects reduced during washing for 7 days compared to AH. Washed SB might allow HPLCs to differentiate into osteogenic cells under the osteogenic environment. This study was supported by the Ministry of Education, Culture, Sports, Science and Technology in Japan.

PR 68Primary Endodontic Infection: Bacterial Investigation, Endotoxins Quantification and Antigenicity AnalysisF.C. Martinho*, L.M.M. Nobrega, A.A. Zaia, C.C.R. Ferraz, J.F. Almeida, B.P.A. GomesUNICAMP-Piracicaba, São Paulo, Brazil

The objectives of this study were to investigate Gram-negative bacterial species and endotoxin in primary endodontic infection (PEI) determining their antigenicity against macrophages in levels of IL-1ß/ TNF-α and PGE

2 and to evaluate the

ability of chemomechanical preparation (CMP) with 2.5% NaOCl + 17% EDTA in removing endotoxin. Samples were taken from 21 root canals with PEI before (s1) and after CMP (s2) using paper points. PCR technique (16S rDNA) was used for bacterial detection. The Limulus Amebocyte Lysate assay (LAL) was used to quantify endotoxins. The amounts of IL-1ß and TNF-α and PGE

2 were measured

by enzyme-linked immunosorbent assay-Duoset-kit (ELISA). Prevotella nigrescens (13/21), Fusobacterium nucleatum (6/21) were the most frequently species detected. A correlation was found between number of Gram-negative bacterial species and levels of endotoxin, IL-1ß and TNF-α and PGE

2 (Pearson’s correlation

coefficient - p<0.05). Higher levels of endotoxin and cytokines were related to the development of clinical symptomatology. Increased levels of endotoxin were followed by TNF-α release (Pearson’s coefficient - p<0.05). Analyses of the quantitative data revealed that the endotoxins content after chemomechanical preparation (S2) was significantly reduced (98.06%) in comparison with s1 (Friedman test/Wilcoxon test p<0.05). Overall, the complex antigenicity (IL-1ß and TNF-α and PGE

2 secretion) of

PEI has to do with the number of different Gram-negative bacterial species as well as with the levels of endotoxin. Moreover, chemomechanical preparation was effective in reducing but not eliminating endotoxin from infected root canals. This study was supported by the Fundacão de Amparo ã Pesquisa do Estado de São Paulo and the Counselho Nacional de Desenvolvimento Científico e Tecnológico.

PR 67Comparison of Cutting Aspect of Gates-Glidden™ Bur and Peeso™ ReamerM. Maeda*, Y. Ogura, I. KatsuumiNippon Dental University, Tokyo, Japan

Stainless steel Gates-Glidden™ burs and Peeso™ reamers were designed to prepare the coronal and middle third of the canals. The purpose of this study was to compare the generated cutting torque at different rotational speeds (750 rpm and 1,500 rpm), and at different insertion speeds into the root canal (0.5mm/sec and 1.0mm/sec). The Gates-Glidden™ burs of size No.2 (Gates Drill™, Mani, Japan) and the Peeso™ reamers of size No.1 (Peeso™ Reamer, Mani, Japan) were used in this study. A computer-controlled torque-testing device was specially designed for this experiment. Instruments were inserted to a depth of 8mm into the standardized straight canal models. The torque generated under each experimental condition was recorded. Three root canal models were used for each group (n=24). The cutting efficacy is analyzed based on the torque-insertion distance and the calculation of the variation in torque ΔT. Despite differences in experimental conditions, torque generation during cutting tended to increase in proportion to the insertion depth of the instrument. No instrument separation occurred during enlarging. As for each instruments, ΔT showed the tendency to decrease when rotational speeds declined. The mean ΔT for the Peeso™ reamer was smaller compared to the Gates-Glidden™ bur in each experimental condition (p<0.05). These results suggested that the blade design influence the generation of torque.

PR 65Mass Spectrophometric Analysis of Parachloroaniline After Chemical Interaction Between Alexidine and Sodium HypochloriteK. Kum*, H. Kim, E. KimSeoul National University, Seoul, South Korea

Recent studies demonstrated that the combination of chlorhexidine (CHX) and sodium hypochlorite (NaOCl) resulted in the formation of red-colored precipitates, parachloroaniline (PCA), which was known as a carcinogen. Alexidine (ALX) is a kind of bisguanides-like CHX, and has stronger detoxification effect against the bacterial virulence factors such like lipoteichoic acid and lipopolysaccharide compared with CHX. The purpose of this study was to determine whether PCA was formed after chemical interaction between ALX and NaOCl using mass spectrometry. Mass spectrometry was performed for the mixture of five different concentrations of ALX (1, 0.75, 0.5, 0.25, 0.125%) and 4% NaOCl. Results showed that the molecular peak of PCA (m/w=128) was not detected in the all mixed solutions of ALX and NaOCl. The color of the mixed solution of ALX and NaOCl after chemical interaction was light yellow to white, but no precipitation was found.

e44 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 70A Survey on Cone-Beam-Computed Tomography in EndodonticsK. Nakano*, H. Ishimura, A. Ebihara, H. SudaTokyo Medical and Dental University, Tokyo, Japan

Recently, cone-beam-computed tomography (CBCT) has been utilized in endodontic treatment. However, guidelines for using CBCT in endodontics to minimize X-ray exposure have not yet been established. The aim of this study was to survey the current use of CBCT in endodontic treatment, including purposes and clinical phases of its use and to establish the guidelines for taking CBCT images in endodontic treatment. A total of 35 cases treated by seven dentists at the endodontic clinic at the Tokyo Medical and Dental University Hospital were collected and evaluated. Results: Purposes of taking CBCT images in answer to multiple choice questions were to diagnose: (1) extent of periapical lesions (65.7%); (2) morphology of root canals (37.1%); (3) suspected root fractures (25.0%); (4) root resorptions (9.3%); (5) presence of lateral canals (3.1%); (6) location of fenestrations (3.1%); and (7) pain before or after endodontic treatment (3.1%). In addition, CBCT images had been taken to confirm the adjacent oral structures, such as the maxillary sinus, mental foramen, Canalis incisivus and neighboring teeth, for planning periapical surgery (15.6%). The survey also showed that a variety of unexpected and useful findings such as mucosal thickening of the sinus and the second palatal root canal of a second molar. CBCT was confirmed to be a very useful diagnostic method in endodontic treatment. The results obtained in this survey may help establish the guidelines for case selections when taking CBCT images in endodontic treatment.

PR 69Incidence of File Separation in an Endodontic Postgraduate Program: A Retrospective Cohort StudyK.D. Brown, J.M. Morelli*, R. Caicedo, G.A. Crim, S.J. ClarkUniversity of Louisville, KY

The primary aim of this study was to determine the incidence of file separation in teeth treated by first- and second-year endodontic residents in a University postgraduate endodontic program. Four thousand nine-hundred and sixty-five teeth with 13,055 canals receiving root canal therapy over a 4-year period were evaluated for file separation. One-hundred and nineteen instruments were separated with 111 separations during initial treatment and 8 during retreatment. Incidence of file separation for number of teeth treated was 2.4% (2.5% for initial treatment, 1.6% for retreatment) and the incidence of file separation for number of canals treated was 0.91% (0.93% for initial treatment, 0.71% for retreatment). There was no significant difference in incidence of file separation between initial treatment and retreatment (p=0.279). Fisher’s Exact test indicated a significant difference for incidence of separation between individual residents. No significant difference was found for incidence of file separation between first year of training (3.12%) and second year of training (2.69%) (p=0.479). Files were found to separate more often in the apical third of the canal (58.3%) than the middle third (34%) or coronal third (7.8%) (p=0.0001). Grouped by tooth type, there was a significant trend for file separation in posterior teeth (p<0.00001). A higher incidence of file separation was found in maxillary teeth than in mandibular teeth (p=0.0142). The results of this study reveal an incidence of file separation and a trend for location of file separation that is consistent with previous reports in the literature.

PR 72Propolis Effects Inflammatory Cytokine Expression in Pulp Cells and OsteoclastsK. Neiva*1, T.M. Botero2, L. Holliday1, S. Wallet1, R. Pileggi1

1University of Florida, Gainesville, FL, 2University of Michigan, Ann Arbor, MI

To effectively inhibit bone resorption and prevent failure of endodontically treated teeth, an ideal intracanal medicament would decrease inflammation along with osteoclast-mediated bone resorption. Bacterial components such as lipopolysaccharides (LPS) are implicated in the development of pulpal and periapical inflammation and inducing osteoclastogenesis. Propolis is a natural, nontoxic substance collected from beeswax that has been used for many years in folk medicine. Propolis has been demonstrated to have antibacterial properties along with anti-inflammatory affects on macrophages. In addition, our previous studies have shown that propolis inhibits osteoclast maturation. However, the effect of propolis on the inflammatory response of pulp cells and osteoclasts function has not been explored. The purpose of this study was to evaluate whether propolis alters the inflammatory response of four endodontically relevant cell lines: mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), macrophages (RAW264.7) and osteoclasts. Cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM) containing 10% fetal bovine serum, penicillin/streptomycin. Osteoclasts were treated with 100 ng/ml RANKL. Cells were exposed to 0-20 ug/ml LPS to induce an inflammatory response, in the presence of propolis or vehicle control. Culture supernatants were collected and used to quantify expression of multiple soluble mediators using Luminex® technology. Propolis had no effect on the baseline expression of most inflammatory cytokines measured. However, propolis was effective in reducing the secretion of LPS-induced inflammatory cytokines. Our results suggest that propolis suppresses the inflammatory response of key cells within the canal, allowing it to be used as an anti-inflammatory intracanal medicament in endodontics.

PR 71A Comparison of Two Gutta-Percha Obturation Techniques to Replicate Canal Irregularities in a Split Tooth ModelM. Natera*, R. Pileggi, U. NairUniversity of Florida, Gainesville, FL

The root system contains irregularities composed of fins, deltas isthmuses and accessory canals that make thorough cleaning and obturation a challenge. The purpose of this study was to compare a Modified Injectable Thermoplasticized Gutta-Percha technique (IT) with Continuous Wave technique (CW) for the ability to fill root canal system (RCS) and replicate artificially created intracanal defects using a split-tooth model. A maxillary canine was used to build a split-tooth model. The root canal was cleaned and shaped using crown-down technique with rotary files to a size of #40 at the apex. Intracanal defects were created in the dentin of the root canal walls with a half-round bur. The canal was obturated 20 times with gutta-percha and sealer. Ten obturations were performed for each technique, injectable thermoplasticized (IT) (n=10) and continuous wave (CW) (n=10). After each obturation the model was separated in two halves; buccal and lingual. Each obturation was examined and photographed under operating microscope at 32x magnification. The images were blindly evaluated by two endodontists for the length of gutta-percha fill, ability to fill the RCS, presence of voids and replication of the canal defects. Results were analyzed using Mann Whitney U test and showed no statistical difference between the two groups in the quality of the obturation (P>0.05). Both groups demonstrated replication to working length equally. Although the injectable thermoplasticized gutta-percha technique appeared to replicate the canal defects better with lesser number of voids, the results were not statistically significant.

e45JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 74Comparison of Removal Preparation of Calcium HydroxideY. Ogura*, M. Maeda, I. KatsuumiNippon Dental University, Tokyo, Japan

Calcium hydroxide is commonly used for intercanal medication. However, it is difficult to remove. The purpose of this study was to compare the different methods of removal preparation. Nine canal clear plastic blocks which enlarged the apical size #40/06 were used. 0.5 g of Calcium Hydroxide were mixed with 0.15 ml of 1% methylene blue dye solution and filled into canal by lenturo. After 24 hours, the specimens were divided into 3 groups of 3 each; group 1 used F File™ for 30 seconds with 4 ml of purified water, group 2 used irrigation with 2 ml of 5% NaOCl and 2 ml of H

2O

2 for 30 seconds and group 3 used irrigation with 4 ml of purified water for

30 seconds. All specimen images were captured and calculated the area that the dye remained. Data were analyzed using one-way ANOVA. F File™ showed the smallest area, followed by the combination of NaOCl/H

20

2 and only purified water. But there

was no statistically significant difference (p<0.05) in these 3 groups. In conclusion, mechanical removing preparation is effective to remove dried hardened calcium hydroxide paste, but it needs enough time to be effective.

PR 76Toll-Like Receptor 4 is Expressed in Pulp Fibroblasts After Stimulation With Candida AlbicansC.R. Pinheiro*1, C.R. Sipert1, T.H. Gasparoto1, C.E. Oliveira1, M.S. da Silva2, A.C. Morandini1, G.P. Garlet1, C.F. Santos1, J.S. Silva3, A.P. Campanelli1

1University of São Paulo-Bauru, Brazil, 2State University of São Paulo-UNESP, Bauru, Brazil, 3University of Sao Paulo, Medical School of Robeirão Preto-FMRP, Sao Paulo, Brazil

Pulp fibroblasts express various proinflammatory mediators that are released during pulpitis. Although pulp fibroblasts are prominent cell type in dental pulp, their roles in microbial recognition and pulpal inflammation are essential yet not well understood. In this study, the function of TLR4 in the recognition of Candida albicans (C. albicans) by murine fibroblasts was evaluated. Briefly, gingival tissues were collected from C57BL/6 mice and fibroblasts were grown from gingival explants and cultured in Dulbecco’s Modified Eagle Medium (DMEM). Also, mouse fibroblasts were studied between passages 4 and 5. For cytokine production and TLR4 expression, cells were either treated for 48 hours with live or heat-killed C. albicans. The addition of living C. albicans to mouse fibroblast resulted in an increase in the number of cells that expressed TLR4 and decreased the number of cells expressing ICAM. In contrast, heat-killed C. albicans did not affect the expression of TLR4 and CD54. Furthermore, C. albicans diminished IL-13 production. These data showed the possible role of TLR4 in the recognition of C. albicans by murine fibroblasts. This study was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.

PR 75The Effect of Statins on Calcification of the Dental PulpM.T. Pettiette*, S. Zhong, A.A. KhanUniversity of North Carolina, Chapel Hill, NC

In recent years, endodontists have noted an increase in pulp chamber calcification (PCC), which makes the diagnosis and treatment of these teeth more challenging. To date, there are no studies examining the underlying etiology for this increased incidence of pulpal calcification. Simvastatin, an HMG-CoA reductase inhibitor, has been shown to enhance the differentiation of human dental pulp cells by upregulating mineralization nodules and odontogenic markers. It has also been shown to promote osteoblastic differentiation. As simvastain and other statins are commonly used in the treatment and prevention of atherosclerosis, we hypothesize that the systemic administration of statins results in an increase in pulpal calcification. We are conducting a retrospective study comparing pulpal calcification in patients using statins to those of controls (age-matched patients not taking any medications on a regular basis). Bite wing radiographs taken using a standardized technique were transferred to the Image J™ software (version 1.32; National Institutes of Health, Bethesda, MD). The dimensions of the pulp chamber were measured using a standardized method by 2 examiners who were blinded to the study groups and the data analyzed using the t-test. Preliminary analysis of our data indicate that the mesiodistal and vertical dimension of the pulp chamber of molars in patients taking statins are significantly smaller than those in the controls (p<.05), thus demonstrating a correlation between the systemic use of statins and PCC. Data from this study will be used to design further prospective studies on PCC to enhance endodontic clinical practice and outcomes.

PR 73Culture and Clonal Analysis of Bacteria Found in Primary Endodontic Infection With Periapical LesionsL.M.M. Nóbrega*, F.C. Martinho, A.A. Zaia, C.C.R. Ferraz, J.F.A. Almeida, B.P.A. GomesUNICAMP-Piracicaba, São Paulo, Brazil

Different from the phenotypic methods, molecular analysis of 16S rRNA genes allows a better identification of microorganisms, providing a wider view of the microbiota. The aim of this study was to investigate the microbiota of primary endodontic infection with periapical lesions by means of culture, biochemical methods (phenotypic methods) and clonal analysis of 16S rRNA genes. Microbial samples were taken from 9 root canals using sterile paper points and immediately placed into the VMGA III transport medium. Strict anaerobic techniques were used for serial dilution, plating, incubation and biochemical identification. From 167 microorganisms isolated, a total of 25 different bacterial species were identified by biochemical tests. Individual root canals yielded an average of 6 species. The species most frequently isolated by culture were: Gemella morbilorum (7/10), Prevotella buccae (7/10), Prevotella oralis (7/10) and Parvimonas micra (6/10). Using the clonal analysis, performed with TOPO TA Cloning® kit into Escherichia coli, a total of 89 different bacteria were identified in an average of 15 different species per canal. The species most frequently recovered by clonal analysis were: Olsenella profusa (5/10), Parvimonas micra (5/10), Pseudoramibacter alactolyticus (5/10) and Dialister sp (5/10). Our findings indicate that microbiota present in the root canals is complex and that the association of methods (culture and clonal analysis) allows a more accurate identification of the microorganisms found in primary endodontic infection. This study was supported by the Fundacão de Amparo ã Pesquisa do Estado de São Paulo and the Counselho Nacional de Desenvolvimento Científico e Tecnológico.

e46 JOE — Volume 37, Number 3, March 2011 * — Abstract Presenter

PR 78Retrospective Outcome Assessment of Endodontically Retreated Teeth in an Elderly Urban North American PopulationC.A. Speirs*, J.A. Goldfein, F.C. SetzerUniversity of Pennsylvania, Philadelphia, PA

Weighted pooled success rates for endodontically retreated teeth [ERT] were reported as high as 77.5% for nonsurgical retreatment [RTX] and 93.5% for root-end surgery [RES]. The long-term prognosis of endodontically treated teeth is directly correlated with definitive restoration and the periodontal status. This reported outcome data is, however, deriving largely from controlled investigations. Little is known about the fate of retreated teeth in an elderly low-income urban population. From the University of Pennsylvania SDM database, 100 retreated teeth with at least 3 years of follow-up were randomly selected. The cases were analyzed for survival, extraction, second retreatment, presence of definitive restoration [PDR], presence of apical periodontitis [PAP], periodontal situation of the retreated tooth and the adjacent teeth. Spearman Rank-Order Correlation Coefficient was used for statistical analysis. Of all teeth, 51 were in female, 49 in male patients, mean age 59.0 years, 77 were RTX, 23 RES. Mean follow-up was 5.4 years for RTX and 5.0 years for RES. In RTX 4 (5.2%) had second retreatments, 17 (22.1 %) were extracted, 3 (3.9%) implants. In RES 9 (39.1 %) were extracted, 2 (8.7%) implants. Statistically significant correlations were found between: RTX: Extraction-PDR (p<0.001), Extraction-PAP (p=0.002); RES: Extraction-PDR (p<0.001), Extraction-PAP (p=0.002). No correlation was found between tooth loss and the periodontal status in general or the periodontal status of the individual tooth. Survival of ERT in an elderly low-income population was higher for RTX than RES. Survival was statistically significantly correlated with PDR and the PAP.

PR 77Outcomes of Endodontic Micro-Resurgery: A Prospective Clinical StudyM. Song, S. Shin*, H. Shin, Y. Kim, E. KimYonsei University, Seoul, South Korea

This prospective clinical study examined the outcomes of endodontic resurgery with microsurgery technique of failed teeth with previous endodontic surgery. In addition, the significant outcome predictors for endodontic surgery were investigated by determining the causes of failure of the first endodontic surgery. The data was collected from patients in the Department of Conservative Dentistry at the College of Dentistry, Yonsei University in Seoul, Korea between March 2001 and May 2009. All 54 teeth that required surgical retreatment were included in this study. All surgical procedures were performed using an operating microscope (OPMI PICO; Carl Zeiss, Göttingen, Germany), and biocompatible root-end filling materials, such as MTA or Super EBA. The patients were recalled every 6 months for 2 years and every year thereafter to assess the clinical and radiographic signs of healing. The recall rate was 77.8% (42 out of 54 patients). Of the 42 cases recalled, 39 cases were included in the success category giving an overall success rate of 92.9%. The most common possible causes of failure in previous surgery were no root-end filling and incorrect root-end preparation. The use of microsurgical techniques and biocompatible materials, such as MTA and Super EBA, resulted in a high clinical success rate, even in endodontic resurgery.

PR 80Root Canal Treatment of Oculo-Fasio-Cardio-Dental SyndromeR. Wadachi*, H. SudaTokyo Medical and Dental University, Tokyo, Japan

Oculo-fasio-cardio-dental (OFCD) syndrome was summarized by Gorlin, et al (1996) as a disease mainly characterized by ocular, facial, cardiac and dental disorders. Inheritance may be X-linked dominant and lethal in males. Regarding dental disorders, macrodontia, microdontia and long tooth roots have been reported. Although several orthodontists had reported its morphological features in the dentofacial region, there are no reports on the root canal treatment. The aim of this case report is to show the root canal treatment of an OFCD syndrome patient with the extraordinary long root. The patient was a 21-year-old Japanese woman referred from her orthodontist. One month before, spontaneous pain, percussion pain and swelling had appeared at the upper right lateral incisor. A general dentist incised the buccal gingiva for drainage, and a repeated root canal medication was performed. At the first examination, there were no symptoms except redness of the buccal gingiva. Custom-made K files and a hand spreader were manufactured because the root was too long to reach the apex. The working length was 34 mm and master apical file size was #50. After redness of the gingiva disappeared, the apical portion of the root canal was obturated using the cold lateral condensation technique with a mainpoint and elongated accessory points using gutta-percha solvent. Then, the coronal portion was downpacked using the continuous wave compaction technique with a system B and backpacked with an Obtura II. This case report showed a long root canal was successfully treated with specially designed long files and a long spreader.

PR 79Radiographic Evaluation of Endodontically Treated Mandibular First Premolar in a Chinese PopulationY. Sun*1, S.F. Yang1, C.Y. Chen1, H.C. Lin1, Y.C. Ho2, Y.Y. Hsu1

1Taipei Tzu Chi General Hospital, Taipei, Taiwan, 2National Yang-Ming University, Taipei, Taiwan

The purpose of this study was to correlate the radiographic features of mandibular first premolars with root canal morphology in a Chinese population. The periapical radiographs and clinical records of mandibular first premolars that had been first treated endodontically from January 2005 to December 2007 were reviewed. A total of 235 teeth were included in this study. The number and outline figure of the roots, the number of canals and canal configurations of the preoperative and interoperative radiographs were recorded and analyzed. The roots were classified into simple conical, blunt, bulge, double PDL on the proximal surfaces or bifurcate root. The canal configurations were classified into simple one canal, sudden disappearance of canal space, canal apical bifurcation or two-canal systems. The complicated canal pattern was defined as more than one simple canal on the postobturation radiographs. Of the 235, first mandibular first premolars in this study, 233 teeth (99.1%) had 1 root. Ninety-five teeth (40.4%) had complicated canal patterns were further confirmed from postobturation radiographs. The incidences of complicated canal patterns in simple conical, blunt, bulge, double PDL root, simple one canal and sudden disappearance of canal space were 15.3%, 46.5%, 73.3%, 85.7%, 10.6% and 80.6%, respectively. When reading radiographic films of mandibular first premolars, findings like bulge-root, double PDL, sudden disappearance of canal space and bifurcation indicate greater chances of complicated canal system. This study was supported by the Taipei Veterans General Hospital.

e47JOE — Volume 37, Number 3, March 2011 Key:

* — Abstract Presenter

PR 81Change of Fatigue Property of NiTi Rotary Instruments Through Heat TreatmentY. Yahata*, K. Miyara, A. Jamleh, Y. Hayashi, A. Ebihara, H. SudaTokyo Medical and Dental University, Tokyo, Japan

It is known that the mechanical behavior of NiTi rotary instruments is strongly affected by heat treatment. The aim of this study was to investigate the effect of heat treatment on fatigue property of NiTi rotary instruments. Raw NiTi alloy wire processed into a conical shape of 0.06 taper with a tip diameter of 0.30 mm was served for a total of 56 specimens. After dividing them into four groups of 14 specimens each, they were heat-treated for 30 minutes at 400° (Group 400), 450° (Group 450) and 500° (Group 500) centigrade. Nonheat-treated specimens were used as control. The rotational bending test was performed at a rate of 250 rpm until fracture. At 2 mm from the tip, each specimen was deflected horizontally to 1.0 or 1.5 mm. All specimens were tested under each deflection. The number of cycles until fracture (NCF) was counted and statistically analyzed by Steel-Dwass test (Alpha=0.05). Compared to the control group, Group 500 showed a higher NCF under 1.0 and 1.5 mm deflection, whereas Group 450 showed a higher NCF only under 1.5 mm deflection (p<0.05). On the other hand, Group 400 did not show any significant difference compared to control (p>0.05). In conclusion, it was suggested that the fatigue resistance of NiTi rotary instruments could be improved through appropriate heat treatment.

PR 82Revitalization of the Pulp Space in Mature Dog’s Teeth: Is it an Anatomical Problem?A.A. Zaia*, J.F.A. Almeida, B.P.F. Gomes, C.C.R. FerrazUNICAMP-Piracicaba, Piracicaba, Brazil

Revitalization/revascularization of the pulp space has been reported in immature teeth with open apices. As of yet, evidence has not been provided for mature teeth. The present study was to evaluate the revitalization of the pulp space in mature teeth of adult dogs. Twenty premolars from two 5-year-old dogs were used (20 root canals). After the coronal access, the dental pulps were removed aseptically by K-files. The apex was created and enlarged with #2 Gates-Glidden™ burs. 5 mL of saline solution (SS) were used between each instrument. The root canals received a final flush with 10 mL of SS and a blood clot from the periapical tissues were created up to the enamel-cement junction. Mineral Trioxide Aggregate (MTA, Angelus) coronally capped the blood clot and teeth were sealed with resin composite Z-250 (3M/ESPE). Two root canals were not fulfilled with blood clot to be used as controls. The animals were euthanized after 90 days. Teeth were decalcified in 5% EDTA and stained with hematoxylin and eosin. The results show a complete filling of the root canal with a healthy connective tissue presenting calcification islands. No specialized cells were identified. The dentin walls were partially covered by a cementum-like tissue. The formation of a blood clot might serve as a protein scaffold, permitting an ingrowth of tissue even in mature teeth. The enlargement of the apical foramen together with blood clot, as well as absence of contamination, seem to be important for the revascularization of the pulp space, even in mature teeth. This study was supported by the Counselho Nacional de Desenvolvimento Científico e Tecnológico.