Influência do tipo de reconstrução coronoradicular e remanescente dentário no comportamento biomecânico de incisivos tratados endodonticamente

Abstract

The aim of this study was to evaluate the influence of the crown, post type and amount of remaining coronal in stress distribution, strain, fracture resistance and mode of failure root filled incisors. A sound maxillary central incisor was selected to generate the 3D model. Enamel and dentin geometry was scanned with 3D-contact scanner. The dentin was longitudinally sectioned in the mesiodistal direction and the scanning was performed in negative space on the pulp. The *.STL files were exported to Bio-CAD program (Rhinoceros-3D) for NURBS modeling. The models were exported to the finite element software (FEMAPNeiNastran) for mesh generation, mechanical properties insertion and boundary conditions. It were generated 13 models: Sound tooth and 12 models according to 3 factors under study: post type: glass fiber post (GFP) and Cast post-andcores (CPC); Crown type: ceramic crown (Cc) or metal crown (Mc) and remaining coronal structure: Without remaining coronal structure (W); 1.0 mm of remaining coronal structure (R1); and 2.0 mm of remaining coronal structure (R2). It was simulated 100N loading application on the palatal surface.The results were evaluated by the von Mises criteria and maximum principal stress. 120 Bovine roots were endodontically treated and divided into 12 groups (n= 10) according to the same factors of finite element analysis. A continuous loading from 0 to 100 N was applied in 5 samples on the palatal surface at an angle of 135° to measure the strain on buccal and proximal root surface followed by loading until fracture (n = 10). Data were analyzed by three-way ANOVA and Tukey HSD test (p <0.05). The Cc and Mc associated with the glass fiber post showed homogeneous stress distribution for root dentin. The Cpc showed high stress concentrations within the root canal. Significant differences were found between the values of fracture resistance: CcGFP W: 607,2±64,9 B,b; R1:890,4±180,9 A,a; R2:922,7±106,2 A,a; Cc-CPC W:724,5±82,3 AB,b; R1:916,2±104,7 A,a; R2:1026,1±240,6 A,a; McGFP W: 653,6±150,8 AB,b; R1:670,7±123,54 B,ab; R2:793,8±133,3 B,a; Mc-CPC W:749,7±179,0 A,b; R1:829,9±179,03 A,a; R2:913,6±220,0 A,a The teeth restored with Cc associated with PFV showed favorable mode of failure. The absence of remaining coronal structure increased values of micro-strain on the buccal surface. Smallest micro-strain values were observed in proximal surface on the presence of R2. The micro-strain values on proximal surface were not influenced by the height of the remaining in Cc-CPC groups. It can be concluded that the presence of R1 and R2 had a positive effect on pattern of stress distribution, strain, fracture resistance and mode of failure regardless the crown and post type. In the absence of remaining coronal, the association between Cc and GFP showed better biomechanical behavior. PFV associated with composite resin showed homogeneous stresses distribution by root dentin. The use of CPC associated with metallic or ceramic crowns promoted high stress concentrations within the root canal.