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This study evaluated the stress distribution in mandibular full-arch implant-supported fixed dentures with different veneering and metallic infrastructure materials, using three-dimensional finite element analysis. Ten models were obtained from an edentulous human mandible with a complete denture fixed by four implants. Acrylic resin (RES) and porcelain (POR) teeth were associated with infrastructures of titanium (Ti), gold (Au), silver-palladium (AgPd), chrome-cobalt (CoCr) and nickel-chrome (NiCr). A 100-N oblique was applied. The von Mises (σvM) and maximum (σmax) and minimum (σmin) principal stresses were obtained. The RES-AgPd group showed the lowest σvM values, while the RES-Ni-Cr group showed the highest. In the bone tissue, the RES-Au group was the only one that showed different σmax values with a 12% increase in comparison to the other groups which had similar stress values. In the implants, the groups with Ti, Au and AgPd infrastructures, either with porcelain or resin teeth, showed σvM values similar and lower in comparison to the groups with CoCr and NiCr infrastructures. The tooth veneering material influenced the stress values in metallic infrastructures, in which the acrylic resin had the highest values. The veneering and infrastructure materials have influence on stress values of implant-supported dentures, except for the peri-implant bone tissue.

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In 2005, odontogenic cyst was classified as keratocyst odontogenic tumor due to being aggressive and recurrent. The keratocyst odontogenic tumor has characteristics, with slow development, does not cause metastases and provides great bone destruction. The aim of this study was to discuss the aspects regarding the diagnosis, prognosis and treatment of odontogenic keratocyst tumor, through the report of two cases. Both initially underwent decompression of the lesion present proximity of anatomical structures to be great and noble, aiming to prevent pathological fractures. We carried out the clinical-radiographic and after regression of the lesion, patients underwent enucleation total.

El año 2005 quiste odontogénico fue clasificado como un tumor queratoquiste odontogénico (TQO) debido a su agresividad y recurrencia. El TQO tiene las características del tumor: crecimiento lento, no causa metástasis y proporciona una gran destrucción ósea. El objetivo de este estudio fue examinar los aspectos relacionados con el diagnóstico, pronóstico y tratamiento del TQO mediante la presentación de dos casos. Ambos casos fueron inicialmente sometidos a descompresión debido al gran tamaño de la lesión y la proximidad de ésta con estructuras anatómicas importantes, con el objetivo de prevenir las fracturas patológicas. Se llevó a cabo un seguimiento clínico-radiográfico y después de tener una regresión de la lesión postdescompresión, los pacientes fueron sometidos la enucleación total.

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Proposição: Esse estudo comparou a distribuição das tensões em 3 diferentes tipos de próteses fixas implanto-suportadas mandibulares para carregamento imediato com o protocolo convencional de dois estágios cirúrgicos, no que diz respeito à distribuição de tensões, por meio do Método de Elementos Finitos tridimensional não linear. Materiais e Métodos: Quatro modelos de mandíbula humana edêntula suporte de prótese fixa implanto-suportada com quatro implantes foram construídos. Os modelos foram divididos em 4 grupos: Grupo A (controle) – os implantes foram rigidamente esplintados por meio de infraestrutura metálica, e submetidos ao protocolo de carregamento convencional de dois estágios cirúrgicos; no Grupo B – os implantes não foram rigidamente esplintados (esplintagem por meio de resina acrílica), e submetidos ao protocolo de carregamento imediato; no Grupo C – os implantes foram rigidamente esplintados por meio de infraestrutura metálica e submetidos ao protocolo de carregamento imediato; no Grupo D – os implantes não foram rigidamente esplintados (esplintagem por meio de resina acrílica), sendo que foi inserido na região do cantilever uma barra-distal pré-fabricada, e foram submetidos ao protocolo de carregamento imediato.Para simular a condição de carregamento imediato dos implantes (Grupos B, C e D), elementos de contato não linear e friccional foram usados. O coeficiente de fricção de 0,3 μ foi utilizado entre o osso e o implante. No modelo A foi considerado um contato colado na interface osso-implante. Os modelos foram suportados pelos músculos da mastigação e pela articulação temporomandibular. Uma carga de 100 N no sentido oblíquo foi aplicada na região do primeiro molar inferior. As análises de von Mises (σvM), máxima (σmax) e mínima (σmin) tensões principais (em MPa) foram obtidas. Resultados: No modelo geral, o grupo A apresentou os menores valores de tensões (σvM=147, σmax=102 e σmin=-131 MPa), enquanto o grupo D mostrou os maiores valores de...

Purpose: This study compared the stress distribution between 3 different mandibular full-arch implant-supported fixed dentures submitted to immediate loading and conventional full-arch implant-supported fixed denture through three-dimensional finite element analysis. Materials and Methods: Four models of edentulous human mandible were fabricated with 4 implants for restoration with full-arch implant-supported fixed denture. The models were divided into 4 groups: Group A (control) – implants were splinted with metallic framework and submitted to conventional loading protocol after 2 surgical steps, Group B – implants were splinted with acrylic resin and submitted to immediate loading, Group C – implants were splinted with metallic framework and submitted to immediate loading, and Group D – implants were splinted with acrylic resin and submitted to immediate loading with a prefabricated distal bar positioned in the cantilever region. Non-linear and frictional contact elements were used to simulate immediate loading (Groups B, C and D). The coefficient of friction μ=0.3 was established between bone and implant. Direct contact at bone implant interface was assumed in the model A. All models were supported by masticatory muscles and the temporomandibular joint. Oblique load of 100N was applied on mandibular first molar. The values of von Mises (σvM) and maximum (σmax) and minimum (σmin) principal stresses (in MPa) were obtained. Results: Group A presented the lowest stress values (σvM=147, σmax=102 e σmin=-131 MPa) while group D showed the highest values (σvM=904, σmax=685 e σmin=-1481 MPa). In bone tissue, the groups submitted to immediate loading (B, C and D) exhibited the highest stress while the group experiencing conventional loading (A) showed a reduction about 50%. All groups submitted to immediate loading presented similar stress values in peri-implant bone. Conclusion: The loading protocol (immediate vs. conventional) represents a great influence on...

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A demanda por restaurações estéticas tem resultado em um aumento do uso de cerâmicas dentais, constituindo a principal alternativa de material restaurador para a estrutura dental devido as suas propriedades favoráveis. Com isso, o objetivo desse trabalho será estudar, através de uma revisão de literatura, a evolução dos sistemas cerâmicos, envolvendo os diferentes tipos e propriedades, indicações e considerações clínicas. Em uma busca detalhada e avançada no banco de dados PubMed, foram encontrados 98 artigos utilizando os seguintes descritores: dental porcelain, dental ceramic e all-ceramic, de acordo com os critérios de inclusão e exclusão restaram apenas 35 artigos para a revisão. Diversos sistemas cerâmicos estão disponíveis no mercado, fazendo com que os profissionais da área protética necessitem de uma constante reciclagem acerca das suas propriedades e indicações, visto que bons resultados são devidos à seleção do melhor material para determinado caso em conjunto à habilidade do profissional

The demand for esthetic restorations has resulted in an increased use of dental ceramics and is the main alternative restorative material to tooth structure due to its favorable properties. Therefore, the aim of this work is to study the evolution of ceramic systems, involving different types and properties, indications, and clinical issues as aesthetic, cementing and longevity. In a detailed and advanced search in the database PubMed, 98 articles were found using the following key words: dental porcelain dental all-ceramic and ceramic according to the criteria for inclusion and exclusion left only 35 articles for review. Several ceramic systems are available in the market, making the prosthetic professionals need a constant recycling about their properties and directions, since good results are due to the selection of the best material for a particular case in all the skill of the practitioner

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The screw loosening of implant-supported prostheses is a common mechanical failure and is related to several factors as insertion torque and preload. The aim of this study was to evaluate the torque maintenance of retention screws of tapered abutments and cylinders of Morse taper implants submitted to retightening and detorque measurements. Two groups were obtained (n = 12): group I-tapered abutment connected to the implant with titanium retention screw and group II-cylinder with metallic base connected to tapered abutment with titanium retention screw. The detorque values were measured by an analogic torque gauge after 3 minutes of torque insertion. The detorque was measured 10 times for each retention screw of groups I and II, totalizing 120 detorque measurements in each group. Data were submitted to ANOVA and Fisher exact test (P < 0.05). Both groups presented reduced detorque value (P < 0.05) in comparison to the insertion torque in all measurement periods. There was a statistically significant difference (P < 0.05) between the detorque values of the first measurement and the other measurement periods for the abutment screw. However, there was no statistically significant difference (P > 0.05) for the detorque values of all measurement periods for the cylinder screw. In conclusion, the abutment and cylinder screws exhibited torque loss after insertion, which indicates the need for retightening during function of the implant-supported prostheses.

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O objetivo do presente estudo foi realizar uma revisão da literatura científica atual, a fim de discutir o comportamento biomecânico e as características inerentes tanto aos núcleos metálicos fundidos, quanto aos pinos pré-fabricados utilizados na prática restauradora dos dentes endodonticamente tratados. Para a identificação dos estudos dessa revisão, foi realizada uma estratégia de busca detalha e avançada para os bancos de dados PubMed e Medline. Foram utilizados como descritores: endodontically treated teeth, post, core, fiber post e metal post. Os critérios de inclusão foram: artigos clínicos, estudos controlados aleatórios, estudos in vitro, revisões de literatura e revisões sistemáticas com e sem meta-análise dos últimos 10 anos, que abordassem o tema proposto. Os critérios de exclusão foram: artigos sem resumo, estudos em animais, artigos cujo idioma não fosse o inglês e artigos de periódicos que não pertencessem à área odontológica. De um total de 211 artigos, após uma análise segundo o critério de inclusão e exclusão, foram selecionados 65 artigos. A maioria da literatura científica atual indica que os pinos pré-fabricados reforçados por fibras e os pinos cerâmicos deveriam ser indicados para os dentes endodonticamente tratados que apresentem uma altura mínima de 2mm de férula. Já os núcleos metálicos fundidos, juntamente com os pinos pré-fabricados metálicos representam uma boa opção protética, quando os dentes a serem restaurados apresentam-se enfraquecidos por qualquer motivo. Apesar do grande número de pesquisas, ainda há uma carência de estudos prospectivos em longo prazo que avaliem a efetividade desses pinos no tratamento de dentes tratados endodonticamente

The aim of this study was to review the current scientific literature to discuss the biomechanical behavior and characteristics inherent to both cast post and core and the prefabricated posts used in the practice of restoring endodontically treated teeth. To identify studies of this review, it was performed a detailed and advanced search strategy to the databases PubMed and Medline. It was used as descriptors: endodontically treated teeth, post, core, fiber post and metal post. Inclusion criteria were: clinical trials, randomized controlled trials, in vitro studies, literature reviews and systematic reviews with or without meta-analysis of the last 10 years that addressed the theme. Exclusion criteria were: articles without abstracts, animal studies, articles whose language was not English and articles from journals that do not belong to the Dentistry field. Of a total of 35 articles, after an analysis according to inclusion and exclusion criteria, 23 articles were selected. Most of the current scientific literature indicates that the prefabricated fiber reinforced and ceramic posts should be appointed for endodontically treated teeth that have a minimum height of 2mm ferrule. As for the cast metal cores, along with pre-fabricated metal represent a good prosthetic option, when weakened teeth have to be restored for any reason. Despite the large number of studies, there is still a lack of longterm prospective studies that evaluate the effectiveness of these posts in the treatment of endodontically treated teeth

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