Objectives : The aim of this study was to evaluate, using finite element analysis, the risk of debonding at the post/resin cement interface and root fracture in teeth restored with a metallic cast post (MCP) or glass fiber post (GFP). The hypothesis was that GFP would present a lower risk of debonding and/or of root fracture.
Materials and methods : 3D finite element models of premolars with oval root canals restored with MCP or GFP were created. Two post/cement interface conditions were simulated: bonded (B) and non-bonded (nB). The risk of fracture indexes (RFI) for the dentin, post and core were calculated by dividing the top 5% maximum principal stress registered in each material ( σ 5% ) by its tensile strength (TS) reported in the literature. The RFI calculated for the intact tooth ( I ) was considered the control. The risk of debonding was analyzed only for models with bonded interface. Tensile (maximum principal) and shear stresses in the post/resin cement interface were analyzed to determine the risk of debonding. The two post types had different cross-sections and resin cement thicknesses. In order to isolate the effect of the elastic modulus of the posts on the risk of debonding, metallic cast posts with a circular cross sectional area (bonded circular metallic posts: CMP-B) and glass fiber posts in the anatomic shape (bonded anatomic glass fiber post: AFP-B) were also simulated.
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