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SURGERYFocusing on Dental Implants

Forecasting Bisphosphonate-related OsteonecrosisOf the Jaws

lentoalveolar surgery is the most[frequently observed risk factor

for the development of bisphospho-nate-related Osteonecrosis of thejaws (BRONJ). Some investigatorshave suggested that a reduction inthe C-terminal telopeptide (GTX),a collagen degradation product usedas a measure of bone resorption, canestablish the degree of osteoclastsuppression that may forecast thedevelopment of BRONJ followingdentoalveolar surgery.

Fleisher et al from New York Uni-versity College of Dentistry per-formed a retrospective study toinvestigate whether reduced serumCTX levels (<150 pg/mL) wererelated to BRONJ following den-toalveolar surgery and whether cer-tain radiographic alterations wereassociated with teeth that developBRONJ after dental extraction.Variables that influence CTX lev-els include age, gender, alcoholconsumption, smoking, ovulation,

exercise, drugs (corticosteroids),disease (diabetes) and circadianrhythms. BRONJ is defined as theexistence of exposed necrotic bonefor >8 weeks in a patient without ahistory of radiation therapy to thejaws treated with a bisphosphonate.The clinical picture can be variableand asymptomatic, or exhibit mobil-ity of teeth, soft-tissue inflamma-tion, neurosensory alterations, sinustracts and discharge.

The study design was a retrospec-tive assessment of radiographic and/or serum CTX data from 68 patientswho had a history of treatmentwith a bisphosphonate and whohad received a dental extraction orhad been diagnosed with BRONJ.

Postoperative healing was evaluatedfor 26 patients with diminishedserum CTX levels (<150 pg/mL)who had had a dental extractionor had been treated for BRONJ.Preoperative radiographs were as-sessed for 55 patients whose healingwas within normal limits or whodeveloped BRONJ following dentalextraction.

Results of this study revealedthat 100% of the patients (26 pa-tients) who had serum CTX levels<150 pg/mL healed within normallimits subsequent to dentoalveolarsurgery (20 patients) or followingtherapy for BRONJ (6 patients).Of the 55 patients who had radio-graphic assessment, 24 patients

Summer 2011Inside this issue:• Survival Rate of Replaced Implants

• Management of Impacted Maxillary Canines

• Survival Rate of Immediately vs Delayed Loaded Implants

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SURGERYSummer 2011

with BRONJ (83%) demonstratedperiodontal ligament (PDL) wideningaffiliated with extracted teeth, butonly 3 patients who healed normally(11%) illustrated PDL widening.

PT!Figure 1. PDL widening along the root ofthe mandibular right second molar (A) withlingual bone exposure (B). (Reprinted withpermission from Fleisher KE, Welch C,Kottal S, et al. Predicting risk forbisphosphonate-related osteonecrosis ofthe jaws: CTX versus radiographic markers.Oral Surg Oral Med Oral Pathoi Oral Radio!Endod 201 0; 110:513.)

ConclusionBecause BRONJ is usually not radio-graphically discernable in its earlystages, there may be a delay in es-tablishing a diagnosis. However, lateradiographic manifestations may in-clude osteolysis, osteosclerosis andpersistence of the extraction socketoutline. The data from this study sug-gest that PDL widening viewed ona radiograph may be a more sensitiveand practical indicator than CTX test-ing when attempting to predict therisk of BRONJ (Figure 1). Healing ofpatients having dental extractions ortreatment for BRONJ can occur withlow-serum CTX levels, and periodon-tal alterations may predispose the pa-tient to BRONJ.Fleisher KE, Welch G, Kottal S, et al. Pre-dicting risk for bisphosphonate-related osteo-necrosis of the jaws: CTX versus radiographicmarkers. Oral Surg Oral Med Oral PathoiOral Radiol Endod 2010;! 10:509-516.

Survival Rate ofReplaced Implants

lim et al from Seoul National(University Bundang Hospital,

South Korea, evaluated the survi-val rate and condition of replacedimplants following removal of failedimplants. The researchers recruited49 patients who had had a total of60 implants (39 implants in men,21 implants in women) placed andsubsequently experienced failure ofthe implant, requiring the insertionof a replacement. The mean age ofthese patients was 53.2 ± 10.8 years.These implant failure cases wereselected as a subset of a larger groupof 573 patients.

Within this group of patients, thestudy revealed that the maxillaryfirst molar region was the most fre-quent site of implant failure. Wheninitial implant failure occurred,the failure rate subsequent to afunctional prosthesis (late fail-ure) was 31.7%; the failure rateduring the healing phase afterimplant placement (early failure)was 68.3%. Complications after thefirst implant placement includedosseointegration failure (86.7%),infection (5.0%), implantitis (5.0%),malposition (1.7%) and fracture offixture (1.7%).Immediate replacement of thefailed implant occurred in 48.3%

of the cases; delayed replacementoccurred in 51.7% of the cases.When a delayed placement protocolwas utilized, the average healingperiod was 2.40 ± 3.06 months.However, there was no significantdifference in the failure rate of thereplacement implant when eitherthe immediate or delayed place-ment protocol was used.

Failure rate of the second implantwas 11.7%. In all cases of secondimplant failures, the authorsplaced a third implant. The secondand third implants in all patientssurvived until the final follow-up(22.00 ± 14.56 months followingimplant insertion). The marginalbone loss at the final follow-upwas 0.33 + 0.49 mm, the widthof the attached gingiva was 1.68 ±2.11 mm and the pocket depthwas 3.33 ± 1.21 mm.

ConclusionImplant failure is multifacto-rial, involving the dentist, thepatient and the implant materialused (Table 1). Implant survival inpatients experiencing initial implantfailure can be improved through theplacement of an additional implant.Kim Y-K, Park J-Y, Kim S-G, Lee H-J.Prognosis of the implants replaced after re-moval of failed dental implants. Oral SurgOral Med Oral Pathoi Oral Radiol Endod2010;! 10:281-286.

Table 1. Implant failure factorsDentist Patient* Bone necrosis due to •

overheating •• Contamination .* Inappropriate number, length •

and width of implants* Inappropriate site or

orientation• Prosthesis design•Occlusal interference•Preparation and adjustment of

prosthesis

BruxismParafunctional habitsPoor dental hygieneSmokingDrug therapyRadiation therapyUncontrolled diabetes

implant material• Biocompatibility« Surface treatment• Design

Management ofImpacted MaxillaryCanines

|he role of the practitioner isI critical in the identification

of impacted maxillary canines andthe appropriate and timely referralfrom the orthodontist to the oraland maxillofacial surgeon. If theidentification and suitable referralsof the impacted canines are prop-erly initiated without delay, and theproper uncovering techniques areselected, the eruption process can besimplified. This will result in predict-able stability and esthetics. Kokichfrom the University of Washingtondelineated the approaches to treatlabial and palatal maxillary canineimpactions, orthodontic mechan-ics, and long-term stability, as wellas the rationale for certain surgicalapproaches.

Third molars are the most frequentlyimpacted permanent teeth, followedby impacted canines, of which one-third are situated labially or with-in the alveolus and two-thirds arelocated palatally. Proper timing andsurgical approach to exposure of animpacted canine are dictated by cer-tain criteria.

Labially impacted canineLabial impaction of the maxillarycanine is caused by ectopic migrationof the canine over the lateral incisorroot or a shift of the midline of themaxillary dentition, creating inade-quate space for canine eruption. Onestudy suggested that removal of thedeciduous canine by age 8 to9 years self-corrects the problemand improves the chance of canineeruption. The 3 techniques avail-able for uncovering the labiallyimpacted maxillary canine are theexcisional uncovering (Figure 2),apically positioned flap and closederuption approaches. The criteriautilized to select the most appropri-ate approach included determina-tion of the labiolingual position of

Figure 2. (A) Space created orthodontically.(B) Tooth labiafly positioned, coronal tomucogingiva! junction. (C) Excisional procedureto uncover impacted canine, (D) Afterorthodontic eruption, relationship of gingivaimargins relative to adjacent teeth was normalwith adequate zone of gingiva. (Reprintedwith permission from Kokich VC. Surgicaland orthodontic management of impactedmaxillary canines. Am J Orthod DentofacialOrthop 2004; 126:279.)

the crown of the impacted canine,the vertical position of the toothrelative to the mucogingival junc-tion, the quantity of gingiva in thearea of the impacted canine and themesiodistal position of the caninecrown.

Palatally impacted canineIf radiographs demonstrate that thecrown of the permanent canine ispositioned over the maxillary lateralincisor root but not past the mesialsurface of the root, self-correction ofthe ectopic canine is evident with ahigh level of predictability. When thepermanent canine is situated beyondthe mesial surface of the root of thelateral incisor, self-correction will notoccur, and the impacted canine mustbe exposed by the surgeon and prop-erly positioned in the arch by theorthodontist (Figure 3).

Assessment of the position ofthe impacted canine crownRadiographs are used to assess thecorrect position of the crown. Whenutilizing periapical radiographs,the buccal object rule is appliedto determine the labiolingual posi-tion of the crown of the impactedcanine. This rule posits that whenscreening 2 adjacent periapicalradiographs of the impacted caninetaken at slightly variable horizontalangles, the buccal object will appearto move in the opposite directionof the x-ray beam, and when theimpacted tooth is on the palate, thecrown of the tooth will move in thesame direction as the x-ray beam.

This principle can be rememberedby using the mnemonic S.L.O.B.rule (same lingual, opposite buc-cal). Three-dimensional cone-beamcomputed tomography can alsointerpret buccolingual information,define the extent of root resorp-tion, allow the surgeon to view thesurgical anatomy and permit theorthodontist to plan directionaltraction.

ConclusionThe general dentist's understand-ing of the principles of diagnosisand treatment of the maxillary im-pacted canine is essential for theoverall successful outcome of thesetypes of cases.Kokich VG. Surgical and orthodontic man-agement of impacted maxillary canines. AmJ Orthod Dentofacial Orthop 2004; 126:218-283.

Figure 3. (A) Impacted right canine on palate. (B) Flap reflected. (C) Palatal bone removed downto cementoenamel junction. (D) Hole placed in flap. (E-F) Canine erupted without orthodonticforces. (G) Bracket placed on canine. (H) Symmetry of maxillary right and left canines. (Reprintedwith permission from Kokich VG. Surgical and orthodontic management of impacted maxillarycanines. Am J Orthod Dentofacial Orthop 2004; 126:282.)

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SURGSummer 2011

Survival Rate ofImmediately vsDelayed LoadedImplants

[he original surgical protocolIfor implants established by

Branemark consisted of submergingan implant following placement andmaintaining a nonloaded implantenvironment for 4 to 6 months.The patient's desire to shorten thetreatment period and to avoid anedentulous condition encouragedthe introduction of an immediatelyloading protocol.

Romanos et al from the Universityof Rochester, New York, analyzedhuman and animal histologic andhistomorphometric data, as well asclinical evidence from an immediateloading protocol for variable bonequalities. The authors wanted todetermine the influence of bonequality on conventional delayedloading compared with immediateloading. They assessed the clini-cal outcomes and the peri-implantbone responses to the 2 differentprotocols (delayed and immediate).Analysis of the literature searchrevealed high levels of osseointegra-tion and elevated survival rates ofimmediately loaded implants, alongwith high percentages of bone-to-implant contacts.

Immediately loaded implants wereinitially defined in 2002 at the WorldCongress Consensus Meeting inBarcelona, Spain, as implants thathave been placed in the bone and

have been restored with occlusal con-tacts within 3 to 4 days subsequentto surgery. The advantages of animmediate loading protocol include

1 an abbreviated treatment period

2 improved patient satisfactionand quality of life

3 the avoidance of an edentulousor partially edentulous state

Figure 4. Implant-bone interface intimatelyrelated as seen in immediately loaded anddelayed loaded implants.

The success of immediately loadedimplants is clinically dependent onimplant stability and histologicallydependent on bone response. Otherfactors influencing implant stabilityinclude

1 geometry and length of implant

2 morphology of the surface

3 splinting of implants

4 control of occlusal load

5 quality of bone

6 lack of deleterious patient para-functional habits

The results indicated that immedi-ate implant loading may stimulatebone formation around the implants(Figure 4) as evidenced in animaland human studies. The authorssuggested that there must be satis-factory biomechanical force transferbetween the implant and peri-implant bone for implant osseoin-tegration to occur. Therefore, whenan immediate loading protocol isutilized, the design of the implant isessential for the bone formation totake place. The orthopedic literature

has demonstrated new bone forma-tion with active remodeling of thebone when the bone is mechanicallystimulated.

ConclusionAnalysis of pertinent publicationsfrom 2003 to 2008 revealed thatthe overall survival rate of implantsusing the immediate loading proto-col ranged between 90% and 95%,which is comparable with the tradi-tional 2-stage delayed loading pro-tocol implant survival rate of 92%.Thus, the immediate loading proto-col for dental implants offers manypatient benefits, including long-term outcomes, even in situationswith less-than-ideal bone quality.Romanos G, Froum S, Hery C, et al. Sur-vival rate of immediately vs delayed loadedimplants: analysis of the current literature. ]Oral Implantol 2010;36:315-324.

In the next issue:• Treatment of avulsed teeth• Outcomes of placing short

dental implants in theposterior mandible

• Decompression ofodontogenic cystic lesions

H Osseoperception: active tactilesensibility of osseointegratedimplants

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