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Dentre os fatores etiológicos das Disfunções Temporomandibulares (DTMs) merecem destaque os hábitos parafuncionais, que muitas vezes são responsáveis pela manutenção da dor, perda de estrutura dental, como as facetas de desgaste, abfrações e por alterações na mucosa jugal e língua. Uma das terapêuticas mais utilizadas para o tratamento da DTM, está relacionada ao uso da placa estabilizadora oclusal (PEO). Apesar de seu uso ser estudado em vários artigos, não são encontrados relatos sobre as marcas encontradas nesse dispositivo devido ao atrito sofrido pelos dentes tampouco quais são os parâmetros e variáveis que poderiam estar relacionados à estas marcas. O presente estudo procurou reproduzir as marcas observadas na PEO, em 36 corpos de prova de resina acrílica ativada quimicamente, em ambiente controlado e analisou os parâmetros e variáveis para avaliação entre marcas fracas e fortes. Para reprodução das marcas nas amostras, foram utilizadas esferas de aço com diâmetros de 3 mm, 4 mm e 5 mm. Para cada diâmetro de esfera foram utilizados os seguintes parâmetros: carga de 2 kgf e 65 kgf e ciclos de repetições de 600 e 1200 vezes. As amostras foram randomizadas com números aleatórios e estabelecido padrão entre marcas fracas e fortes para cada diâmetro de esfera, com apenas uma amostra de cada triplicata. Na sequência, 3 observadores cegos fizeram suas classificações para correlação do padrão. Para correlação do padrão vs. observadores e observadores entre observadores, foi realizado o teste kappa de Fleiss. Foram obtidos níveis excelentes em todos os testes, quando não havia mistura de diâmetro de esfera, e nível razoável quando os observadores avaliaram as amostras com os diâmetros de esferas misturados. Relacionado aos resultados, as variáveis consideradas foram, diâmetro da calota impressa e profundidade calculada da calota com a fórmula da dureza Brinell. As variáveis, dureza e diâmetro de calota impressa, não demostraram robustez para estabelecer critério na avalição entre marca forte e fraca. Já a variável \"profundidade calculada de calota\" demostrou que ao passo que aumentava a profundidade calculada da calota, a marca tinha maior tendência a ser classificada como forte. Desta forma, pode-se concluir que o parâmetro carga foi o fator de maior relevância na classificação entre as marcas fracas e fortes. A variável profundidade calculada da calota mostrou relevância na classificação das marcas fortes e fracas e os diâmetros de esferas diferentes, com mesma carga e quantidade de ciclos geraram marcas diferentes. / Among the etiological factors of TMDs is the parafunctional habits, which are often responsible for the loss of dental structure, such as the wear facets and abfraction and changes in the oral mucosa, such as cheeks and tongue. One of the most used therapies for the treatment of TMD is related to the use of the occlusal splint (OS). Although its use is reported in several articles, no reports are found on the marks found in this device due to the friction suffered by the teeth, nor are the parameters and variables that are related to these marks. The present study reproduced the observed marks in the OS in 36 chemically activated acrylic resin samples in a controlled environment and analyzed the parameters and variables for evaluation between weak and strong marks. For the reproduction of the marks in the samples, stainless steel sphere with different diameters of 3 mm, 4 mm and 5 mm were used. For each sphere diameter the following parameters were used: load of 2 kgf and 65 kgf and repetition cycles of 600 and 1200 times. Samples were randomized with random numbers and established pattern between weak and strong marks for each sphere diameter, with only one sample from each triplicate. Subsequently, 3 observers made their classifications for pattern correlation. For correlation of the Standard vs. Observers and Between Observers, the Fleiss kappa test was performed. Excellent levels were obtained in all tests, when there was no sphere diameter crossing, and fair level when observers evaluated the samples with the sphere diameters crossed. Regarding the results, the variables considered were Brinell hardness, diameter of the printed cap and depth of the cap. The variables, hardness and diameter of printed cap, did not demonstrate the robustness to establish standard in the evaluation between weak and Strong marks. The variable depth of printed cap proves that while the depth of the printed cap increased, the mark had a more tendency to be classified as strong. In this way, we can conclude that the load parameter is the factor of greater relevance in the classification between the weak and strong marks. The variable depth of the printed cap demonstrated relevance in the classification of the weak and strong marks, and finally the diameters of different spheres with the same load and number of cycles created different marks.

Loss of bone in the mandible as a result from for example resection of bone tumors or trauma, can in more complex cases be reconstructed using a reconstruction plate to provide stability between the remaining mandible stumps. Different studies on reconstruction plates present a fracture rate of 2.8-9.8 %. The rate of plate fracture and plate loosening increases the need to improve the design of the reconstruction plate. A useful tool to find new designs for structures is topology optimization. Topology optimization is a mathematical based method where it is possible to define an optimization problem for a specific load case. Based on the defined problem, the solver calculates the most appropriate design to reach the final goal. The aim of this work is to investigate, describe, and discuss how new designs for reconstruction plates used for bridging large mandibular defects can be achieved by using topology optimization as a tool.   Two software programs handling topology optimization from Altair Engineering were used: SimLab 14.0 and HyperMesh 14.0. Both of them uses the solver OptiStruct to solve the defined topology optimization problem. The topology optimization problem was defined to minimize the compliance of the structure with an upper limit of the allowed volume fraction used for the new design. Three different clenching tasks were examined: right unilateral clench, clenching in the intercuspal position, and incisal clench. All three load cases resulted in different designs, the designs were also affected by the initial amount of screws used, and by the defined value on the allowed thickness of the created parts in the new design. The results gave an initial understanding of topology optimization, and indicated the possibilities a design process with topology optimization has to achieve new designs for reconstruction plates used for large mandibular fractures.

Purpose: The present study aimed to evaluate the impact of bruxism on dental implant failure rates andmarginal bone loss (MBL), based on a systematic review of the literature. Materials and methods: An electronic search without time restrictions was undertaken (last updated in September2021) in three databases, plus handsearching. Only studies that provided enough informationon the criteria used for the diagnosis of at least ‘probable bruxism’ (self-report + clinicalexamination) were considered for inclusion. Meta-analyses were performed besides meta-regressions, in order to verify how the odds ratio (OR) was associated with follow-up time. Results: The review included 23 publications. Altogether, there were 1,991 and 9,438 implants placedin bruxers and non-bruxers, respectively. Pairwise meta-analysis including only the studiesthat provided enough information on the criteria used for the diagnosis of at least ‘probablebruxism’ resulted in significant failure rate difference between the groups (OR 1.987, p =0.015). There was an estimated increase of 0.010 in OR for every additional month of follow-up (p = 0.209). None of the included studies reported results on MBL separated betweenbruxers and non-bruxers. Conclusion: Implants placed in bruxers present a significant higher risk of failure than in non-bruxers.Studies comparing MBL between the groups are still lacking. / Syfte Den aktuella studien syftade till att utvärdera effekten av bruxism på dentala implantats misslyckandefrekvens och marginell benförlust (MBL), baserat på en systematisk översikt av litteraturen. Material och metod: En elektronisk sökning utan tidsbegränsningar gjordes (senast uppdaterad i september 2021) i tre databaser, plus handsökning. Endast studier som gav tillräckligt med information om de kriterier som användes för diagnos av åtminstone ’trolig bruxism’ (självrapportering + klinisk undersökning) övervägdes för inkludering. Metaanalyser utfördes förutom metaregressioner, för att verifiera hur oddskvoten (OR) var associerad med uppföljningstid. Resultat: Översikten omfattade 23 publikationer. Sammanlagt fanns det 1 991 och 9 438 implantat placerade i bruxare respektive icke-bruxare. Parvis metaanalys som endast inkluderade studierna som gav tillräckligt med information om kriterierna som användes för diagnosen av åtminstone ’probable bruxism’ resulterade i signifikant skillnad i felfrekvens mellan grupperna (OR 1,987, p = 0,015). Det var en uppskattad ökning med 0,010 i OR för varje ytterligare månad av uppföljning (p = 0,209). Ingen av de inkluderade studierna rapporterade resultat på MBL separerade av bruxare och icke-bruxare. Slutsats: Implantat placerade i bruxare innebär en signifikant högre risk för misslyckande än hos icke-bruxare. Studier som jämför MBL mellan grupperna saknas fortfarande.

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