ABSTRACT
This study evaluated the stress distribution on an implant-supported zirconia crown of a mandibular first molar subjected to oblique loading by occlusal contact with the natural maxillary first molar by using the 3D finite element method. Two virtual models were made to simulate the following situations: (1) occlusion between maxillary and mandibular natural first molars; (2) occlusion between zirconia implant-supported ceramic crown on a mandibular first molar and maxillary natural first molar. The models were designed virtually in a modeling program or CAD (Computer Aided Design) (Rhinoceros). An oblique load of 100 N was uniformly applied to the zirconia framework of the crown. The results were obtained by the Von Mises criterion of stress distribution. Replacement of the mandibular tooth by an implant caused a slight increase in stress on portions of the maxillary tooth roots. The crown of the maxillary model in occlusion with natural antagonist tooth showed 12% less stress when compared with the maxillary (model in occlusion with the) implant-supported crown. The mandibular crown of the implant show 35% more stress when compared with the mandibular antagonist crown on the natural tooth. The presence of the implant to replace the mandibular tooth increased the stresses on the maxillary tooth, especially in the region of the mesial and distal buccal roots.
Subject(s)
Molar , Mouth, Edentulous , Humans , Finite Element Analysis , Zirconium , Crowns , Stress, Mechanical , Dental Stress Analysis , Dental Prosthesis, Implant-SupportedABSTRACT
OBJECTIVE: To evaluate the marginal misfit between intermediate and micro-unitmetal cylinder, by varying the angle of the implants, using two different types of material and different molding techniques. METHODS: A model was made with three implants (one perpendicular to the horizontal plane and two inclined) using micro-unit intermediates. A rod attached to the master model served as a control condition to evaluate the suitability of the twenty specimens, carried out with the help of an optical stereomicroscope (Pantec, Brazil; Materials Testing Laboratory, São Leopoldo Mandic, Campinas, São Paulo). RESULTS: Evaluator reliability was assessed using theIntraclass Correlation Coefficient, obtaining 99.6% (excellent). There were significant differences between groups, and the Mann-Whitney test compared groups in pairs for a more accurate result. CONCLUSION: The group which presented the best behavior was open tray and condensation silicone and the worst result, that needed to be cast several times, was closed tray and condensation silicone. .
OBJETIVO: Avaliar a desadaptação marginal entre intermediário micro-unit e cilindro metálicos, variando a angulação dos implantes, com dois tipos de materiais e diferentes técnicas de moldagem. MÉTODO: Modelo com três implantes (um perpendicular ao plano horizontal e dois inclinados) usando intermediários micro-units. Uma barra mestre acoplada ao modelo serviu de situação controle para avaliar a adaptação dos vinte corpos de prova, feitas com estereomicroscópio óptico. RESULTADOS: A confiabilidade do avaliador foi avaliada com Índice de Correlação Intraclasse, obtendo 99,6% (ótimo). Houve diferença estatisticamente significante entre os grupos, e com o teste Mann-Whitney comparou-se os grupos aos pares para um resultado mais preciso. CONCLUSÃO: O grupo que apresentou melhor comportamento foi o de tray aberta e silicone por condensação. O de pior resultado, que foi preciso ser moldado diversas vezes, foi o de tray fechada e silicone por condensação. .
