Efeito do uso de ionômero de vidro na câmara pulpar na deformação de cúspides, resistência à fratura e tensões geradas em molares tratados endodonticamente

Abstract

The aim of this study was to evaluate the effect of restorative protocol on the cuspal strain (CS), fracture resistance (FR), residual stress and mechanical properties of the composites at various depths in endodontically treated molars restored with different protocols. Forty five human molars received standardized Class II mesio-occlusal-distal cavity preparations and endodontic treatment followed by direct restorations using three restorative protocols: CR, using only Filtek Supreme, 3M-ESPE; RMGI+CR, using Vitremer, 3M-ESPE to fill pulp chamber and Filtek Supreme to fill MOD cavity; GI+CR, using Ketac Fill, 3M-ESPE to fill pulp chamber and Filtek Supreme to fill MOD cavity. CS was measured using strain gauges, after which the same restored teeth were used to FR. The elastic modulus (E) and Vickers hardness (VH) at different depths were determined from dynamic microhardness indentations. The restorative protocols were simulated in a two-dimensional FEA. The values of CS, E, VH and FR were statistically analyzed using a split-plot analysis of variance and Tukey\'s test (P = 0.05). Residual stresses of contraction influenced by loading were analyzed qualitatively and quantitatively. The CS was higher when using composite resin. The fracture resistance was lower used techniques that used glass ionomer, The E, VH measured on the pulp chamber was significantly lower for glass ionomer. The FEA showed composite resin filling technique resulted in higher stresses at the enamel and at root dentin close to pulp chamber than the filling technique glass ionomer. In conclusion the restorative protocols tested modified significantly the biomechanics behavior of endodontic treated molars. Therefore, it is important to use the glass ionomer to fill the pulp chamber and complete de restoration using incrementally filling technique using composite resin because this combination is beneficial in reducing cuspal strain and increasing the fracture resistance and therefore it is recommended when endodontically treated molar teeth undergo direct restoration with resin composite.