A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Abstract ASSESSMENT OF THE ROLE THAT SECOND MOLARS PLAY IN BITE-OPENING DURING ORTHODONTIC TREATMENT IN ADOLESCENTS: A RETROSPECTIVE, CEPHALOMETRIC STUDY DEGREE DATE: DECEMBER 6, 2013 Christopher B. Trockel, D.D.S. COLLEGE OF DENTAL MEDICINE NOVA SOUTHEASTERN UNIVERSITY Thesis Directed By: Shiva Khatami D.D.S., Ph.D, Committee Chair Mark Hall, D.D.S., Committee Member Abraham Lifshitz, Committee Member Objectives: This study aimed to investigate the role that second molars play in increasing the facial vertical dimension by comparing vertical changes experienced in growing patients, who had their second molars incorporated into the orthodontic appliance, with those that did not. The study investigated associations between the vertical changes experienced through treatment and the initial vertical classification of the patients (normo-, hypo-, and hyperdivergent). Background: Many studies have investigated the changes in the vertical dimensions that occur in orthodontic treatment. It has been shown that almost all orthodontic appliances produce extrusion whether desired or not. In theory, this extrusion may lead to an increase of the skeletal vertical dimension. Conventional wisdom says that second molars play a significant role in vertical control during treatment. Therefore, some practitioners advocate viii incorporating the second molars as soon as possible in treatment to help open the bite. It is also thought that it may be wise to not incorporate the second molars during treatment at all in cases with an open bite tendency. Methods: Eighty de-identified pre-treatment cephalometric radiographs (40 with second molars bonded and 40 without second molars bonded) from growing patients treated at the orthodontic clinic at Nova Southeastern University were analyzed and compared to their post-treatment analogs. Twelve linear and angular measurements were made (overbite, maxillary molar to palatal plane, mandibular molar to mandibular plane, upper anterior dentoalveolar height, lower anterior dentoalveolar height, upper anterior facial height, lower anterior facial height, total posterior facial height, lower posterior facial height, UAFH/LAFH ratio, mandibular plane angle, and Y-axis). Results: The results indicated that the vertical dimension was not significantly altered based solely on whether or not the second molars were incorporated into the orthodontic appliance. Changes experienced by both groups (bonded and non bonded) and all three subgroups (hypo-, normo-, and hyperdivergent) were consistent with what would be expected for growth alone. Conclusion: Bonding second molars in a growing population during orthodontic treatment does not significantly affect the vertical dimension, regardless of the patient's initial skeletal vertical classification.

Objectives: More than 30 states use the Salzmann Index or the Handicapping Labiolingual Deviation Index to determine which patients receive tax-supported orthodontic treatment. The indexes use a criterion which produces a numerical value reflective of the severity of the malocclusion. The aim of the study is to evaluate the validity of these indexes by comparing subjective evaluations of orthodontic treatment need to objective scores produced by indexes of malocclusion. Methods: 20 orthodontic faculty and residents (VAS Group) were asked to evaluate the severity of malocclusion of 20 patients, prior to beginning orthodontic treatment, using a subjective scale, a Visual Analog Scale (from “No need for treatment” to “Severe need for treatment”). The 20 patients consisted of a variety of malocclusions including Class I, Class II, Class III, anterior crossbite, posterior crossbite, impaction. A separate group of 3 residents (IS Group) evaluated the same patient malocclusions using the aforementioned indexes of malocclusion. The results were analyzed to identify a correlation between the subjective scale (VAS) and objective scales (IS). Results: In total, 20 residents and faculty evaluated the severity of malocclusions. There was a weak correlation between the Salzmann scores and the Visual Analog Scale scores (Correlation Coefficient, R2=0.2359). There was a moderate correlation between the Handicapped Labiolingual Deviation index scores and the Visual Analog Scale scores (Correlation Coefficient, R2=0.4486). When comparing the faculty versus the residents in the VAS Group there was a strong correlation between them (Correlation Coefficient, R2=0.7901). Although, there was a strong correlation, on average the faculty scored the malocclusions with 15% more severe need for treatment than did the residents. Conclusion: Overall, there was a weak correlation for the Salzmann Index and a moderate correlation for the Handicapped Labiolingual Deviation Index, indicating neither indexes are optimal for evaluation of malocclusions. More emphasis has to be placed on identifying an objective method to evaluating the severity of malocclusions. / Oral Biology

Objectives: This study aimed to three-dimensionally analyze the effects of pre-surgical nasoalveolar molding in unilateral cleft lip and palate patients. Methods: The sample was collected from three centers and consisted of 132 digital dental casts of patients pre- and post- NAM. Landmarks and measurements were identified on each cast and the changes from pre- to post-NAM were recorded and analyzed. Results: Post-NAM, we observed a mean decrease of 5.18mm in 3D cleft width, 1.78mm decrease in sagittal cleft gap, 1.34mm decrease in the anterior arch width, 2.27mm increase in the posterior arch width, a greater inward rotation of the greater segment (8.50°) compared to the lesser segment (3.09°), and an increase in arch depth (1.74mm) and internal flexion (9.20°) of the lesser segment. No statistically significant changes in the arch depth and internal flexion of the greater segment were observed. The morphological changes between pre- and post-NAM therapy were visualized by closest distance colormaps and 3D superposition assessments. Conclusions: Unilateral cleft lip and palate patients were successfully treated with traditional NAM therapy. The obtained data may serve as a foundation for a regression algorithm for the closure of cleft, allowing future fabrication of semi-automated 3D-printed NAM plates.

Objectives: The purpose of this study is to determine the skeletal and dental contributions in the orthodontic correction of Class II subdivision malocclusions using cone-beam computed tomography (CBCT) analysis. Methods: 50 Patients that completed non-surgical orthodontic treatment at the University of the Pacific Graduate Orthodontic Clinic with initial Class II subdivision malocclusions were identified. Patients were classified as growing or non-growing, and further categorized if a skeletal asymmetry was present. Final records were assessed with 3-dimensional CBCT. Wilcoxon signed-rank tests were used to compare linear skeletal, angular, and dental measurement differences between pre- and post-treatment CBCTs on Class I and Class II sides. Results: Of 50 patients, 40 were treated with fixed appliances and 10 with clear aligners. Elastics were the most common Class II correction modality utilized. In growing patients on the class II side, the lower first molar (L6) mesialized by 1.57mm and extruded by 1.21mm (P< .005). In nongrowing patients on the Class II side, the L6 mesialized by .73mm (NS), and the upper first molar (U6) distalized by .52mm (P=.006). The results of a multiple regression analysis for growing patients revealed that only changes in U6 and L6 anterior-posterior positions on the Class II side had a statistically significant relationship with the amount of Class II correction. However, a positive correlation was observed between mandibular growth and L6 mesial movement (P= .0006) on the Class II side in growing group, suggesting that mandibular growth on Class II side contributed to Class II correction. Mandibular total length change between Class I and Class II sides did not show a statistically significant difference in both the growing group (P = .413) and total sample (P= .231). Conclusion: In patients with a Class II subdivision malocclusion with and without skeletal asymmetry, the Class I and Class II sides display differences that are mainly dentoalveolar. In growing patients, the Class II molar relationship was largely corrected by the mesialization of the L6. Growing patients with a skeletal asymmetry did not tend to grow more asymmetric. In non-growing patients, the Class II relationship was corrected by distalization of the U6 and mesialization of the L6. The correction of Class II subdivision malocclusion with and without skeletal asymmetry was achieved primarily by dentoalveolar effects.

OBJECTIVES. Studies on quantitative relationships between magnitude of force applied to a tooth root and formation of gingival crevicular fluid (GCF) biomarkers (volume, concentrations of cytokines, enzymes, etc.) in clinical settings are lacking. This study aims to answer the question: What can analysis of GCF flow dynamic characteristics inform us about orthodontic tooth movement in a patient treated by Invisalign? METHODS. In three participants, two GCF samples were collected from five maxillary and five mandibular teeth during start, middle and end of Invisalign treatment. Plaque index and pocket depths were determined. Periopaper strips (Oraflow) were used for collection of GCF, volume was measured by Periotron 8000 (Oraflow). All collections of GCF (1200 periostrips) were performed by the same person at the same time in the week and day (IRB#2021-61). Patients were examined by CBCT before start of treatment, one patient also at the end. iTero digital models were obtained at the start and end of treatment. Aligners were changed every week. RESULTS. Predictors of force applied to tooth roots were obtained from ClinCheck website and crown movements were directly measured on iTero digital model. GCF volume dynamics was described by two variables – normalized GCF flow and aligner ratio. Significant differences were found between unmoved and moved teeth in the same patient. Magnitude of variables increased at the start and duration of Invisalign treatment and declined back at the end of treatment corresponding with the start and end of force application to a tooth. CONCLUSIONS. Our results suggest that there is a quantitative relationship between normalized GCF flow and aligner ratio variables and applied orthodontic force by Invisalign. Analysis of GCF flow and aligner ratio dynamics can contribute to deeper understanding of a quantitative relationship between force and PDL tissue responses in patients treated with Invisalign.

Objectives: This retrospective cohort study compared vertical and transverse changes in mixed dentition patients treated with Invisalign First System (IFS) to those treated with rapid maxillary expansion and fixed appliances (RME), as well as control groups. We also assessed the efficiency of dental arch expansion with IFS. Methods: The study included 80 mixed dentition patients, with 40 in each group (IFS and RME) and 40 controls from the AAOF Legacy Collection. We analyzed skeletal and dental vertical dimension changes from lateral cephalometric radiographs and arch width changes on study casts between pre-treatment (T1) and post-treatment (T2). Results: Age at T1, time interval (T1-T2), sex, and Angle class did not significantly differ among the groups. Mandibular plane angle changes (measured by SNMPA and FMA) showed similar degrees of reduction for the control and IFS groups, with no changes in the RME group. However, these differences among the three groups did not reach statistical significance (p=0.06). The RME group showed a significantly greater expansion in maxillary intermolar width compared to the IFS group (p<0.001). In the IFS group, the efficiency of expansion ranged from 52.3% to 76.87% in the maxilla and 64.25% to 79.95% in the mandible. Higher expansion efficacies were observed in the anterior regions of both the maxillary and mandibular arches compared to the posterior regions in the IFS group. Conclusions: During the mixed dentition stage, no statistically significant changes occurred in the skeletal vertical dimensions among the control, RME, and IFS groups. Although there was a trend suggesting a greater reduction in the mandibular plane angle in the IFS group compared to the RME group, this difference may not be clinically significant given the less than 1-degree discrepancy. IFS can be a viable option for addressing mild to moderate arch width deficiencies, with a predictable increase in intermolar width of approximately 2.5mm.

Objectives: This study aimed to examine the treatment outcome of correcting class II malocclusion with maxillary molar distalization using clear aligners in both growing and nongrowing patients. Material and Methods: Total of 42 patients (31 growing and 11 non-growing) who underwent non-extraction clear aligner therapy with maxillary molar distalization were selected and compared to 20 subjects who did not undergo orthodontic treatment were selected from American Association of Orthodontists Foundation (AAOF) legacy collection. Thirteen cephalometric measurements and molar relationships on the digital casts at pre-treatment (T1), end -of-active-treatment (T2) for the treatment group (growing and non-growing) and control group were obtained. Results: There were no statistical significance in the skeletal changes (SNA, SNB, and ANB) between the growing treatment group and the control group. Wits decreased significantly (p<0.05) and the upper incisor retroclined significantly (p>0.05) for the growing treatment group. The average molar correction for the whole treatment group were - 1.76mm and -1.43mm for the right and the left side respectively (negative sign indicates correcting to class I) The average molar corrections for the growing treatment group were - 1.92mm and -1.47mm for right and left side respectively. For the control group, the right side became more class II (+0.58mm) and left side maintained (-0.08mm). Conclusions: Maxillary molar distalization using clear aligner therapy successfully corrected class II malocclusion in both growing and non-growing patients predominantly due to dentoalveolar changes. For the growing patients, the treatment corrected class II malocclusion which would not have corrected on its own without treatment intervention.

Objectives: The aim of this study was to assess the accuracy and reliability of a fully automated landmark identification (ALI) system in automatically locating landmarks, in comparison to assessments made by human judges. Materials and Methods: We collected a total of 76 cone-beam computed tomography (CBCT) images. Following a calibration process, two human judges utilized In Vivo7 Software (Anatomage, San Jose, California) to locate 31 landmarks in the x, y, and z coordinate planes on the CBCT images. A ground truth dataset was created by averaging the landmark coordinates identified by the two human judges for each landmark. The accuracy of the ALI system was assessed by determining the mean absolute error (mm) for the x, y, and z coordinates, as well as the mean error distance (mm) between the human landmark identifications and those made by the ALI system. Additionally, the successful detection rate was calculated for each landmark. Results: In general, the ALI system demonstrated a similar level of success in landmark identification as the human judges. The average mean absolute error for all coordinates by the ALI system was 0.94 mm. Across all three coordinate planes, 94% of the landmarks had a mean absolute error of less than 3 mm. The mean error distance for all 31 landmarks was 1.99 ± 1.26 mm. When applied to the 31 landmarks across 76 CBCT images, the ALI system achieved a 91.85% success rate in detecting landmarks within a 2.5-mm error distance range. Conclusions: Overall, the ALI system yielded clinically acceptable mean error distances, with only a few exceptions. Notably, the ALI system demonstrated greater reliability than humans when identifying landmarks on the same image at different times. This study underscores the potential of ALI in assisting orthodontists with landmark identification on CBCT images. Introduction

Introduction: The objective of this study was to investigate the cephalometric and dental changes observed in nongrowing, deep overbite patients of varying mandibular planes treated with Invisalign® (Align Technology, San Jose, CA). Methods: This retrospective study included 51 patients (27 females and 24 males, aged 33.01 ± 14.74; initial overbite of 4.6 ± 0.83 mm; average treatment period of 1.89 ± 0.85 years; average refinements of 2 ± 1.51). The sample was consecutively treated at the University of the Pacific Resident Orthodontic Clinic and one private practice from 2014-2023. The sample was further divided into 2 groups: patients with an FMA ≥ 20° (Group 1, n = 26; 14 females and 12 males; aged 33.52 ± 14.85) and a hypodivergent FMA <20° (Group 2, n=25; 13 females and 12 males; aged 32.47 ± 14.09). Smart Track materials, bite-turbos, and the G5-G8 interface were used for all patients. The initial (T1) and final (T2) overbite, overjet, inter-canine width, and intermolar width were measured on models using OrthoCAD (v 5.9.1.50). The T1 and T2 curve of Spee was measured on 3Shape (Niels Juels Gade, Copenhagen, Denmark). Lateral cephalometric radiographs at T1 and T2 were traced superimposed, and 37 measurements were analyzed on Dolphin (v 12.0.0.55). Descriptive statistics, paired student t-tests, and Pearson correlation analyses were performed. Results: An average overbite correction of – 1.95 mm (p < 0.001), -1.84 mm (p < 0.001), and -2.05 mm (p < 0.001) were observed for the whole sample, Group 1 and Group 2 respectively. Lower incisor intrusion was reported for the whole sample, Group 1, and Group 2 as - 0.77 mm (p < 0.001), -0.72 mm ((p < 0.5), and -0.82 (p < 0.001). Lower molar extrusion was calculated as 0.3 mm (p < 0.05) in Group 1 and 0.35 mm (p < 0.05) in Group 2. Group 1 did not have a statistically significant change in FMA or LAFH, while Group 2 reported a minimal increase in LAFH on an average of 0.35 mm (p < 0.05). Conclusions: Invisalign® can reduce overbite in patients with deep bite malocclusion and varying vertical skeletal patterns. Correction occurs mainly through lower incisor intrusion, lower incisor proclination, and lower molar extrusion. The effects of deep overbite treatment with Invisalign® are largely dental and do not significantly alter a patient’s FMA or LAFH, regardless of the patient’s vertical skeletal pattern.

The timing and necessity of Phase I mixed dentition treatment in orthodontics have long been subjects of debate. This study aims to explore the level of agreement among clinicians in recommending Phase I treatment, the rationales behind such decisions, and the implications for Phase II treatment. MATERIALS and METHODS: A series of three surveys were administered to faculty members at the University of the Pacific, focusing on various aspects of Phase I and Phase II treatments. RESULTS: The study found a mild level of agreement among clinicians in recommending Phase I treatment, with transverse issues being the most cited reason. Despite this, the success of Phase I treatment did not consistently influence recommendations for Phase II treatment. The study also revealed that clinical practice, rather than educational background, significantly influences clinicians' decisions. CONCLUSION: These findings highlight the complexity and subjectivity involved in clinical decision-making for Phase I treatment and underscore the need for further research to establish more definitive guidelines. Limitations of the study include a lack of diversity among the judges, suggesting the need for more inclusive future research.