ABSTRACT EVALUATION OF FIT FOR 3D PRINTED RETAINERS AS COMPARED TO THERMOFORM RETAINERS By David Cole, D.M.D. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University Thesis Directors: Eser Tüfekçi, D.D.S., M.S., Ph.D., M.S.H.A. Professor, Department of Orthodontics Sompop Bencharit, D.D.S., M.S., Ph.D. Associate Professor and Director of Digital Dentistry, Department of General Practice Introduction: Despite recent advances in three-dimensional (3D) printing, little information is available on 3D printed retainers Methods: Three reference models were used to fabricate traditional vacuum formed, commercially-available vacuum formed, and 3D printed retainers. For each model, three retainers were made using the three methods (a total of 27 retainers). To determine the trueness, the distances between the intaglio surface of the retainers and the occlusal surface of the reference models were measured using an engineering software. A small difference was indicative of a good fit. Results: Average differences of the traditional vacuum formed retainers ranged from 0.10 to 0.20mm. The commercially-available and 3D printed retainers had a range of 0.10 to 0.30mm and 0.10 to 0.40mm, respectively. Conclusions: The traditional vacuum formed retainers showed the least amount of deviation from the original reference models while the 3D printed retainers showed the greatest deviation.

Purpose: To evaluate the factors that influence potential orthodontic patients choosing between an orthodontist, general dentist, and direct-to-consumer (DTC) aligners for their treatment, and to determine the demand for each provider type. Methods: An electronic survey was administered to 250 individuals among the general population of adults in the United States. Questions were designed to determine the respondent’s level of interest in pursuing orthodontic treatment with each provider type, evaluate their current level of knowledge concerning provider options, and identify factors influencing their selection. Pearson’s chi-squared test and ANOVA were used to evaluate the factors influencing patients in their selection. Results: When asked their preference in provider type, 43.8% of respondents selected orthodontist, 34.1% selected DTC aligners, and 22.1% selected general dentist. Among respondents with the highest level of interest in pursuing orthodontic treatment, 50% selected an orthodontist and 27% selected DTC aligners. For respondents with moderate levels of interest in pursuing treatment, only 21% selected an orthodontist and 48% selected DTC aligners. The biggest perceived advantage of treatment with an orthodontist was quality of treatment, and the biggest disadvantage was cost. For DTC aligners, the biggest perceived advantage was convenience, followed by cost, and the biggest disadvantage was quality of treatment. Among adults with children, 34% selected DTC aligners for themselves and only 16% selected DTC aligners when selecting for their children. Conclusion: Adults in the United States have similar levels of interest in pursuing orthodontic treatment with orthodontists and DTC aligners and, to a lesser degree, general dentists. A significant portion of those who select DTC aligners for their treatment are patients who would not have otherwise undergone treatment with an orthodontist. Patients tend to select orthodontists due to quality of treatment, whereas DTC aligners are selected due to convenience, followed by cost. Even among parents who prefer DTC aligners for their own treatment, parents tend to select an orthodontist for their child’s treatment.

INTRODUCTION Il existe actuellement de nombreuses options esthétiques de traitement pour corriger orthodontiquement les malocclusions dentaires. Le standard de traitement en chirurgie orthognatique est d’utiliser des boîtiers conventionnels fixes. Récemment, une nouvelle technique gagne en popularité en pratique privée : l’utilisation de coquilles d’alignement transparentes comme alternative esthétique. La littérature actuelle sur ce sujet consiste exclusivement de rapports de cas. Ainsi, il semble raisonnable d’affirmer que davantage de recherche est nécessaire sur ce sujet. OBJECTIFS L’objectif principal de cette étude rétrospective est d’évaluer la qualité des résultats obtenus à la suite de traitements combinés d’orthodontie et de chirurgie orthognatique en utilisant le système Invisalign®, en comparaison avec les boîtiers orthodontiques traditionnels. L’objectif secondaire de comparer la durée de traitement entre les deux systèmes. MATÉRIEL/MÉTHODES Quarante-neuf patients ont été recrutés en provenance de deux pratiques orthodontiques privées (24 Invisalign® / 25 contrôles de boîtiers fixes). Les deux groupes étaient initialement similaires, tel que mesuré par le Discrepancy Index de l’American Board of Orthodontics. Les résultats finaux ont été évalués en utilisant l’outil Phase III (Model Grading System) de l’American Board of Orthodontics. RÉSULTATS Les scores moyens de chaque catégorie du Model Grading System étaient supérieurs pour le groupe Invisalign® et une différence significative existait entre les groupes pour les catégories d’alignement, de contacts occlusaux, d’angulation des racines et de score total. Les durées de la préparation pré-chirurgicale et du traitement total se sont révélées plus courtes pour le groupe Invisalign® (p ≤ 0.05). CONCLUSION Invisalign® a produit des traitements combinés d’orthodontie et de chirurgie orthognatique plus courts que les boîtiers traditionnels. Par contre, des scores du Model Grading System supérieurs ont été répertoriés lorsque comparés avec les boîtiers conventionnels, signifiant la production de résultats de qualité inférieure à la technique traditionnelle fixe. / INTRODUCTION Numerous esthetic orthodontic treatment options currently exist to correct dental malocclusions. The gold standard in orthognathic surgery is to use bonded orthodontic brackets. Recently, clear aligners have been proposed as an alternative. The current available literature on this topic consists exclusively of case reports. Therefore, it seems reasonable to assume that further research is needed on this topic. OBJECTIVE The primary objective of this retrospective study aims to evaluate the quality of the outcomes of combined orthodontic and surgical treatments with Invisalign® when compared with conventional orthodontic treatments. The secondary objective is to compare the duration of treatment between Invisalign® and conventional brackets. MATERIAL/METHODS Forty-nine patients were recruited from two orthodontic private practices (24 Invisalign® / 25 bracket controls). Both groups were initially similar, as per the ABO Discrepancy Index. The results were assessed using the ABO Phase III method (MGS). RESULTS The MGS mean scores were consistently higher for Invisalign® and there was a significant difference between the groups regarding alignment, occlusal contacts, root angulations and total score. The duration of pre-surgical preparation and the total treatment time were shorter for the Invisalign® group (p ≤ 0.05). CONCLUSION Invisalign® provided faster combined orthodontic and orthognathic surgery treatment, yet demonstrated inferior quality of results when compared to conventional brackets using the MGS.

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Objectif: Suite aux traitements avec aligneurs, une insuffisance de contacts postérieurs est souvent notée cliniquement: existe-t-elle réellement, se corrige-t-elle spontanément? Cette étude vise à comparer la qualité de l’occlusion statique chez des patients ayant été traités avec boitiers conventionnels ou par aligneurs, dès la dépose des appareils orthodontiques et après six mois de mise en place fonctionnelle. Matériel and Méthodes: La mise en place fonctionnelle de l’occlusion chez des sujets traités par boitiers conventionnels (GB, n=25) ou par aligneurs (GA, n=14) et par a été évaluée par un système d’analyse occlusale informatisée (T-scan 9), au moment de la dépose (T0), puis à 3 et 6 mois de contention (T3 et T6). Les sujets (41% de filles, âge moyenne de 19,38 ± 5,98 ans), étaient traités sans extractions, ni chirurgie, avec pour contention des fils collés ou appareils sans recouvrement occlusal. La symétrie et la simultanéité des contacts ainsi que la position antéro-postérieure du centre de forces (CF) étaient évalués. Résultats : À tout moment (T0, T3, T6), aucune différence statistiquement significative n’a été observée quant à la position antéro-postérieure du CF (p=0,854), la répartition ou la simultanéité des contacts, quelle que soit la modalité de traitement. Le CF était situé antérieurement chez les patients de sexe féminin à tout temps (p=0,002). La mise en place fonctionnelle semblait être terminée dès trois mois pour les deux groupes. Conclusion: La qualité de l’occlusion était comparable dans les deux groupes six mois après la dépose des appareils orthodontiques, signifiant l’absence d’influence du type de traitement à court terme. Le sexe féminin pourrait être associé à un CF plus antérieur même après six mois de mise en place fonctionnelle. / Objective: Following aligner therapy, a lack of posterior contacts is common and is expected to resolve with settling. The aim of the study was to compare the quality of occlusion and settling, immediately after treatment and during a retention period of six months, in patients treated with fixed appliance therapy or clear aligners. Materials and Methods: 25 patients treated with fixed appliances and 14 patients treated with aligners were evaluated by a digital occlusal analysis (T-Scan 9) at time of debonding (T0) and 3 and 6 months later (T3 and T6). Subjects (41% female, average age 19.38 ± 5.98) were treated without extraction or maxillofacial surgery using either bonded wires or removable appliances without occlusal coverage as retainers. Contact symmetry, simultaneity and the antero-posterior position of the Center of Force (COF) were assessed at the time of debonding, and after 3 and 6 months of retention. Results: At all times of evaluation, the COF position was not statistically different for both treatment modalities (p=0.854), but was located more anteriorly in female patients when compared to male patients (p= 0.002). Settling appeared to be completed by 3 months in both groups. Conclusion: The quality of the occlusion was comparable after 6 months of settling when treated with either treatment modality indicating no short-term effect of treatment type. Females maintained a more anterior COF after six months of retention.