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#67 Orthognathic Surgical Simulation of Class III Patients using Cone Beam CT imagesS. TUCKER, L. CEVIDANES, M. STYNER, and R. WHITEDepartments of Orthodontics, Computer Science, and Oral SurgeryObjective: Our aim is to determine if virtual surgery performed on 3-D cone beam CT models can correctlysimulate the actual surgical outcome of Class III orthognathic surgical patients. Our Null hypothesis is that: Themean surface distance of the simulated surgical models when superimposed on the actual cone beam CT oforthognathic surgical patients at UNC is zero. Methods: The study involves data analysis of Cone beam CTs fromten Class III surgical patients. All data was acquired from the University of North Carolina orthognathic surgerystability studies. (DE 005215) We created segmentations of the maxillofacial hard tissues of ten patients whoreceived combined maxillary advancement and mandibular setback surgery. Using the presurgical cone beam CTmodels we performed virtual surgeries using the academic software CranioMaxilloFacial Application (CMF).Results: The virtual surgical models were superimposed on the models of the actual surgical outcomes. Thisgenerated visual displays of magnitude, direction, and location of disagreement between models. We alsocalculated difference measurements such as mean surface distance between models. Conclusions: This technologycan be very useful because it will allow surgeons to simulate surgeries in three dimensions prior to the operatingroom. This may be very helpful for training programs as well as for surgical planning of procedures. It also canbe very useful in generating predictions of surgical outcomes. Future research could involve linking the hard tothe soft tissues for soft tissue planning and patient education purposes. Supported by NIDCR DE 005215#68 Physiologic Adaptation to Lingual Appliances During the Initial Eight Weeks of TreatmentR. SANBORN III, R.SHEATS, D. ZAJAC and A. BASILDepartments of Orthodontics and Dental ResearchObjective: A prospective pilot study of adult patients treated with customized lingual orthodontic appliances(iBraces, Bad Essen, Germany) was undertaken to measure the intensity and duration of soft tissue discomfort,orthodontic tooth pain and speech impairment. Methods: Six patients, fully banded and bonded in both arches atUNC School of Dentistry, completed a standardized questionnaire pre-treatment, within 24 hours after applianceplacement, days 2, 3, 5 and weekly for eight weeks. Intraoral discomfort and speech impairment were reportedusing both a 5-point Likert and Numerical Rating Scale. Results: By the conclusion of the first week, patientsreported little to no soft tissue discomfort. At week 2 orthodontic tooth pain subsided, followed by speechimpairment at 3 – 4 weeks. Conclusions: The results of this investigation may help orthodontists provide patientswith detailed information about the expected adaptation periods for customized lingual orthodontic appliances.Supported by SAO and DFNC42
#69 Evaluation of Stress Generation in Alveolar Bone During Orthodontic Miniscrew UseUnder Varied Conditions: A Finite Element AnalysisJ.K. POLLEI, C-C. KO, and J.F.C. TULLOCHDepartment of OrthodonticsObjective: Stress may be associated with loosening and instability of orthodontic miniscrews, thereby contributing tominiscrew failure. This study used finite element analysis (FEA) to evaluate stress in alveolar bone when loads areapplied to miniscrews of varying angulations, designs and material types. Methods: Models of the maxillary leftposterior dentoalveolar complex were constructed from μCT data with Solidworks®. Computer aided design models ofTOMAS® and IMTEC® orthodontic miniscrews were inserted buccally between the second premolar and first molar atangulations of 45°, 60°, and 90° to the cortical bone surface. A 150g retraction load was placed. Miniscrew compositionwas varied from titanium (Ti) to stainless steel (SS) to composite (Comp) materials. Cortical bone modulus was variedfrom low to high (5-20GPa). Models were solved with ANSYS 10.0 and stress components were compared betweenangulations. Results: In all models stress patterns were similar in location and magnitude. Maximum principle stresses(MPS) were located distal to the miniscrews. Greatest von Mises stresses were diffused around the miniscrew/boneinterface. Tensile stress was greatest at 45° and least at 90°, and did not exceed ultimate tensile strength values ofcortical bone at any angulation. Von Mises stress was lowest in TI, and slightly higher in Comp and SS. At low corticalbone modulus, MPS was greater for TOMAS than IMTEC models while Von Mises stress was similar for both. Athigher cortical bone modulus both MPS and von Mises stress decreased in the TOMAS model and increased in theIMTEC model. Conclusions: Miniscrew angulation, when using clinically accepted loads, does not appear to be a factorthat contributes to tensile failure in bone. Maximum stress in every model was far below the ultimate tensile strength ofcortical bone or any material tested. The stress properties of SS and Comp miniscrews compare favorably to Ti,indicating these materials may be feasible alternatives in clinical use. Differing miniscrew designs may account fordifferences in alveolar bone stress patterns, but no clinically appreciable difference exists between miniscrewsevaluated. Supported by: SAO, NIDCR, NC Biotech Center, AAOF#70 Relationship of Mandibular Canal and Fixation Placement to Sensory Alteration FollowingOrthognathic SurgeryG. TUCKER, C. PHILLIPS, L. CEVIDANES, and G. BLAKEYDepartments of Orthodontics and Oral & Maxillofacial SurgeryObjectives: Altered sensation is a common sequelae of orthognathic surgery involving the mandible. The etiology ofaltered sensation following this surgery has been attributed to injury during tissue dissection, direct trauma from the split,stretching or compression of the nerve during and following surgical manipulation as well as compression of the nervefollowing fixation. The objective of this pilot study was to assess the association of morphological and surgical factorsrelated to mandibular canal location and post-surgical neurosensory alteration over 2 years as quantified by contactdetection in patients having a BSSO. Methods: 3D side-specific measurements were obtained from cone Beam CT(CBCT) scans taken before and after orthognathic surgery: pre-surgery, distance from the buccal and lingual corticalplates to the mandibular nerve canal; post-surgery, distance from the nerve canal to the nearest fixation screw, thedistance the osteotomy and nerve canal were coincident, and the amount of mandibular advancement. Contact detectionwas performed with nylon monofilaments representing multiple force levels before and 1,3,6,12, and 24 months aftersurgery. Results: The mean age at the time of surgery was 31.14 years old. Eighty three percent of the subjects werefemale. On both the right and left sides the average minimum distance from the lingual cortical plate to the inferioralveolar canal (IAC) was less than the distance from the IAC to the buccal cortical plate. The average distance from thesurgical fixation screws to the IAC was approximately 1mm less on the left side. There were no consistent statisticallysignificant correlations between the anatomical or surgical measured distances and the impairment in contact detectionfollowing orthognathic surgery. Conclusions: Our preliminary study indicates that quantitative 3D assessment of theIAC trajectory and position in relation to pre-surgical anatomical factors and post-surgical fixation position is plausibleusing CBCT. This methodology will allow for future in depth analysis of anatomical relationships and surgery relatedfactors and their effects on sensory alterations following orthognathic surgery. Supported by NIH Grants DE005215 andDE01367 and the SAO43
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Page 22 and 23: #15 The Effects of Standardized Pat
Page 24 and 25: #19 Effect of Phenytoin on MMP Prod
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Page 30 and 31: #31 Hypoxia-mediated Gene Regulatio
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Page 34 and 35: #39 The Effects of Epidermal Growth
Page 36 and 37: #43 The Impact of Removal of Third
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Page 42 and 43: #55 Dentinogenesis Imperfecta: Rela
Page 44 and 45: #59 Comparison among CPP-ACP, Fluor
Page 46 and 47: #63 Outcome Study of Gutta-Percha a
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