Long-term stability of surgical-orthodontic open bite treatment: Le Fort I versus 4-piece segmental Le Fort I osteotomy Introduction: This vertical malocclusion has the potential of causing functional and esthetic impairment, impacting patients´ quality of life negatively. The long-term stability of anterior open bite surgical-orthodontic treatment is an important and controversial issue. A variety of factors such as surgery type, surgery fixation, and the anteroposterior discrepancy is related to and can influence long-term overbite stability. The controversy of stability arises in the inherent difficulty of collecting a homogeneous sample, with considerable sample size and adequate long-term followup, leading the current literature to an inconclusive status. Therefore this thesis aimed to test 2 null hypotheses: 1-There is no difference in the long-term stability of the surgical-orthodontic correction of anterior open bite when comparing Le Fort I to 4-piece segmental Le Fort I osteotomies. 2-To test the null hypothesis that there is no difference in the long-term stability of the surgical-orthodontic correction of anterior open bite when comparing Class II to Class III patients. Materials and Methods: The sample of the first investigation comprised the lateral cephs of 29 open bite subjects treated with 1-piece Lefort I osteotomy compared to the lateral cephs of 24 open bite subjects treated with 4-piece Lefort I osteotomy; in both groups Class I, II and III subjects were included. The groups were matched regarding age and were compared with t-tests. To test the second null hypothesis, lateral cephs of 21 Class II open bite subjects were compared to lateral cephs of 25 Class III open bite subjects. Overbite changes were compared at 3-time points: T1 (pretreatment), T2 (posttreatment) and T3 (follow-up) by using t-test. Overbite clinical stability percentage at T3 was assessed with the chi-square test. Results: In 1-piece Le Fort I Group 65.52% of patients presented with clinically significant overbite stability, while in 4-piece Group 83.33% remained stable in the long-term, however it was not statistically significant. In Class II Group 57.14% of patients presented with clinically significant overbite stability, while in Class III Group 88% remained clinically stable, and it was statistically significant. Conclusions: The first null hypothesis regarding maxillary segmentation was accepted because there was no significant intergroup difference regarding the percentage of clinically stable patients. The type of fixation seems to influence the long-term stability of open bite surgical-orthodontic correction more than maxillary segmentation. The second null hypothesis was rejected because clinical stability of Class II malocclusion open bite surgical-orthodontic treatment was significantly smaller than in Class III malocclusions.

Composite resins are an indispensable item in restorative dentistry. This is because it is an accessible material, which allows less dental wear, in addition to providing excellent aesthetics and good mechanical properties. During the last decades, technology has been promoting a wide evolution in the field of dental resin materials. Not only research on physical, but also mechanical and optical properties has been carried out, increasing the load size, finish and polishability. Recently, methods have been developed to reduce polymerization shrinkage and polymerization stress. Both nanoparticulate resins and "bulk fill" resins are already consolidated in the market, bringing advantages such as greater mechanical resistance and reduction of clinical steps, in addition to unichromatic composites that facilitated the selection of colors. This study aimed to review the literature on composite resins and describe its evolution and perspectives. Based on this literature review, the use of nanotechnology increased the durability of restorations, making them more aesthetic and with better physical-mechanical resistance. Materials with differentiated viscosity for each specific case and unique increments with bulk fill resins result in less stressful procedures for dentists. The research is focused on unichromatic resins, which can mimic the dental substrate, facilitating the color taking. Self-adhesive resins (under study) still have room for improvement in their performance, which will result in a significant decrease in steps, as well as remineralizing materials that can increase the lifespan of restorations.

No abstract