Influence of material and loading location on stress distribution of inlays.

PURPOSE: To evaluate the stress distribution of inlays fabricated with restorative materials of different elastic moduli under two functional loading conditions by using three-dimensional (3D) finite element analysis (FEA) models of a second maxillary premolar. METHODS: A 3D model of a sound maxillary left second premolar and its supporting bone was generated in a previous study and reutilized under permission of the authors for the present study. Inlay models obtained from the sound tooth were then assigned according to the type and inherent elastic modulus of the restorative material used, as follows: microhybrid composite (Filtek Z250); indirect resin composite (Paradigm); lithium disilicate reinforced glass ceramic (IPS e.max Press); and type III gold alloy. The geometric models were then exported for 3D FEA. All materials were considered isotropic, homogeneous, and linear-elastic. A static load of 100 N was applied in two conditions: axially at both cusps (axial loading) and at the mesial marginal ridge (proximal loading). Maximum principal and von Mises stresses were used to analyze the stress distribution pattern in inlays and sound premolar models. RESULTS: Under axial loading condition, either resin composite, ceramic or type III gold alloy inlays generated a similar biomechanical behavior, especially in terms of stress distribution in the remaining tooth structure and cusp deflection. However, higher tensile stresses were observed along the proximal gingival margin of the preparation under proximal loading in the Z250 and Paradigm models, as well as a greater cusp deflection. In contrast, a deflection like the sound model was observed in the ceramic and gold inlay models. CLINICAL SIGNIFICANCE: Restorative materials with higher elastic modulus, such as dental ceramics and type III gold alloys, seem to be the best choice for maxillary premolars restored with inlays in the presence of occlusal contact on the marginal ridge.

Influência do material restaurador e da estrutura dental remanescente na distribuição de tensões em restaurações indiretas / The restorative material and remaining tooth influence on the strain distribution into indirect restorations

O presente estudo teve como objetivo analisar, por meio do método de elemetos finitos, a influência do preparo cavitário e do material restaurador na distribuição de tensões em restaurações do tipo inlay. Sete modelos matemáticos bidimensionais foram criados a partir de uma imagem digitalizada de um primeiro molar inferior. A análise foi feita no programa Abaqus (HKS), utilizando-se uma carga estátística de 300N distribuídas em três regiões das superfícies oclusais dos modelos. Os resultados mostraram que o compósito laboratorial (cerômero) foi o que apresentou a melhor distribuição de tensões, gerando um padrão homogêneo das mesmas.