Avaliação da distribuição de tensões em diferentes topografias residuais de molares restaurados com “Endocrown”

Abstract

The aim of this study was to evaluate with the finite element method (MEF), the stress distribution under simulated functional loading in different cavity preparations using the pulp chamber of an endodontically-treated second mandible left molar to observe the stability and retention of the Endocrown. Computer tomography data of the tooth was obtained to generate a 3D volumetric model. In this 3D digital tooth, different cavity preparations without (Wo) and with (W) cusp coverage were modeled and edited, as well as a restoration and luting layer. All cavity preparations with cusp coverage had a mesio-occlusal-distal extension. To obtain the Poisson ratio and the elastic modulus of the restorative material used in the MEF, ceramic specimens were subjected to flexural tests. The following groups were obtained according to the cavity preparation: intact tooth (control) [IT]; occlusal-distal extension [WoOD], mesioocclusal- distal extension [WoMOD]; with buccal cusp coverage [WB], with lingual cusps coverage [WL]; with coverage of all cusps [WT]; and remnant of 2 mm above of the cement-enamel junction [Rm]. All groups were subjected to a 200 N loading in the Ansys Workbench v12 software and the stress distribution was analyzed by Rankine principal stresses criteria. "None" experimental group simulated stress distribution as the "IT". "WoOD" showed lowest stress levels at the internal angles. Stress levels were higher at internal angles for "W" and "WoMOD". No difference was observed between the other groups when compared to "Wo" and "W" with "MOD" extension. Within the limits of this in vitro study, it was concluded that the presence of a proximal wall was an important biomechanical factor for the remaining dental tissue and that the cusps coverage did not show any advantages for the stress distribution when compared to the more conservative cavity preparations.