fiber density (32%), BV/TV (51%), mineral appositionrate of the 1st-11th days (33%) and mineralized bonepercentage (37%) compared to placebo-treated speci-mens, while number of osteoblasts and mean fiber diam-eter were unchanged. Signs of Wallerian degenerationwere less in the distracted IANs of hNGF-treated sides. Inthe 28 day consolidation experiment, hNGF beta signif-icantly increased maximum load (23%), fiber density(20%), BV/TV (26%), mineral apposition rate of the 1st-11th days (29%) and mineralized bone percentage (19%)compared to placebo-treated specimens, while numberof osteoblasts, mean fiber diameter and mineral apposi-tion rate of the 12th-22nd days were unchanged.

Conclusion: Our data demonstrates that locally ap-plied hNGF beta can accelerate callus maturation andIAN injury recovery in a rabbit model of mandibular DO.It may therefore play a role in shortening the consolida-tion period and repairing/protecting IAN in mandibularDO clinically.

References

Eppley BL, Snyders RV, Winkelmann TM, et al: Efficacy of nervegrowth factor in regeneration of the mandibular nerve: A preliminaryreport. J Oral Maxillofac Surg 49:61, 1991

Letic-Gavrilovic A, Piattelli A, Abe K: Nerve growth factor beta (NGFbeta) delivery via a collagen/hydroxyapatite (Col/HAp) composite andits effects on new bone ingrowth. J Mater Sci Mater Med 14:95, 2003

Wang L, Sun MY, Jiang YG, et al: Nerve growth factor and tyrosinekinase A in human salivary adenoid cystic carcinoma: Expression pat-terns and effects on in vitro invasive behavior. J Oral Maxillofac Surg64:645, 2006

Apical Root Resorption of Anterior TeethFollowing Orthognathic SurgeryJeffrey Watson, DDS, 6274 Allan Street, Halifax, NovaScotia B3L 1G9, Canada (Powell J; Morrison A)

Statement of the Problem: External apical root resorp-tion (EARR) is a known risk factor of orthodontic treat-ment. The etiology appears to be multi-factorial withnumerous factors contributing to the problem. Variousarticles have suggested that the combination of bothorthodontic therapy and orthognathic surgery may in-crease the degree of resorption while others have ques-tioned whether there is any true relationship. Therefore,the association of orthognathic surgery and EARR isunclear and no study to date has specifically examinedthis relationship.

Purpose: 1) To compare the measured EARR of agroup of orthodontic patients to a patient group that hadundergone a combination of orthodontics and orthog-nathic surgery. 2) Evaluate factors in the surgery groupthat may affect EARR.

Materials and Methods: A retrospective study was con-ducted at the Department of Oral and Maxillofacial Sur-gery, Dalhousie University. Records from a single or-thodontist were reviewed. A total of 82 patients met

inclusion criteria; 39 as the non-surgical control groupand 43 in the surgery group. Periapical radiographs weredigitally scanned and measured by two separate exam-iners in a blinded fashion using computer software. Forall study patients, 2 sets of radiographs were measuredand analyzed. The first set was taken prior to initiation ofactive treatment (T0) and the second set was post-orth-odontic treatment following fixed appliance removal(T2). In the orthodontic/orthognathic surgery group, apresurgery set were also analyzed (T1).

Method of Data Analysis: Measurement reliability wascalculated via the intra-class correlation coefficients(ICC) for each examiner. Root resorption of the 2 groupswas compared on a tooth-by-tooth basis using anANCOVA test, controlling for demographic variables thatdiffered between groups. The ANOVA and Pearson cor-relation coefficient tests were used to evaluate the effectof pre-treatment and treatment variables on root resorp-tion in the surgery group.

Results: Inter-examiner (ICC 0.92-0.97) and intra-ex-aminer (ICC 0.97-1.00) reliability were highly correlatedand there were no systematic differences. ANCOVA re-sults showed that patients who had undergone surgerydid show statistically significant increased resorption,primarily in the maxillary lateral incisors. Average re-sorption for all maxillary lateral incisors in the controlgroup was 1.1 mm while it was 2.3 mm in the surgerygroup (p � 0.01). ANOVA and Pearson correlation co-efficient tests showed no significant effect for the vari-ables in the surgery group with respect to resorption (p� 0.11-0.86).

Conclusion: External root resorption is a frequent con-sequence of orthodontic treatment and it appears thatthe combination of orthodontic treatment and orthog-nathic surgery may increase the amount of root resorp-tion. Fortunately, this differential resorption was quitesmall and of questionable clinical significance. Analysisof the surgery group failed to reveal any meaningfulrelationship of resorption to patient age, duration oforthodontic treatment, specific type of surgery includinginterdental osteotomies, use or duration of a surgicalsplint, type or duration of MMF, or the particular dento-facial deformity being treated.

References

Travess H, Roberts-Harry D, Sandy J: Orthodontics. Part 6: Risks inorthodontic treatment. Br Dent J 196:71, 2004

Mirabella AD, Artun J: Risk factors for apical root resorption ofmaxillary anterior teeth in adult orthodontic patients. Am J OrthodDentofacial Orthop 108:48, 1995

The Effect of Sensory Retraining onPatient’s Perception of Altered SensationFollowing Orthognathic SurgeryJohn R. Zuniga, DMD, MS, PhD, Department ofSurgery, Division of Oral and Maxillofacial Surgery,

Oral Abstract Session 3

52 AAOMS • 2006