Effect of occlusal restoration on stresses around class V restoration interface: A finite-element study

Abstract

Causes of failures in class V restorations have always been controversial until now, since the biomechanical aspects of these restorations have been understood. This study was aimed to verify the hypothesis that eccentric forces are the cause of cuspal flexure, which lead to excessive stresses at the periphery of a class V restoration, further it identifies the amount of the stress and the flexure increase in the presence of an occlusal restoration using different restorative materials to restore (both cervical and occlusal) along with their comparison with respect to amount of stresses around the cervical restorations. The study was done by modeling a mandibular first premolar which was sectioned bucco-lingually, in the NISA, EMRC II finite element software. A 100N eccentric load was applied on the tooth structure and stresses were observed at the peripheries of the class V restoration when it was restored with composite and with glass ionomer cement. The stresses were further analyzed in the presence of occlusal restorations with different materials and configurations. It was seen that the stresses at the gingival wall interface in case of class V glass ionomer cement was more than that for composite. In the presence of an occlusal amalgam restoration, the cuspal flexure was more than that of occlusal composite and the stresses at the class V peripheries were also statistically significant. It was suggested that lower modulus composites can flex with the tooth structure decreasing the bond failure and that the stresses are much lesser when there is absence of an occlusal restoration. Occlusal composite restorations reinforce the tooth structure and reduce the cuspal flexure as compared to silver amalgam.