A finite element analysis of the stress at the restoration-tooth interface, comparing inlays and bulk fillings

A finite element investigation comparing bonded inlays and directly placed restorations is presented. The stress build-up due to the contraction of the restorative composite and the composite luting cement was computed using a finite element model accounting for the time-dependent, elasto-visco-plastic behaviour of the composite. In addition, the stresses generated in the restoration due to occlusal loading were computed. It was found that inlays, in general, generate higher stresses during curing, particularly along the interface between the cement and the dentine at the base of the cavity. This is probably due to a reduced capacity for stress relief through viscous flow during the early stages of the curing reaction. Under occlusal load, restorations placed using both techniques perform similarly, from a purely mechanical point of view.