Stress and damage at the bur-prosthesis interface in dental adjustments of a leucite-reinforced glass ceramic

Abstract

This article reports on the effects of dental adjustment parameters on stress and damage induced in a leucite-reinforced glass ceramic using a high-speed dental handpiece and coarse diamond burs. As one of machinable dental ceramics for prosthetic restorations, a leucite-reinforced glass ceramic has higher fracture toughness than feldspar porcelains. However, the extent of subsurface damage and stress induced in clinical dental adjustments is unknown. Tensile, shear, compressive and von Mises stresses at the bur-ceramic interface were investigated as functions of dental adjustment parameters using finite element analysis (FEA). The depths of subsurface damage were predicted using FEA according to the maximum principal stress criterion and experimentally measured using scanning electron microscopy (SEM). The resulting predicted subsurface damage depths agree well with the experimentally measured data. Both adjustment parameters, depth of cut and feed rate, were found to have significant influences on adjustment-induced stresses (P < 0.01) and subsurface damage (P < 0.01). It is also found that the predicted and measured subsurface damage depths increased linearly with the diamond grit depth of cut.