Subsurface damage layer of in vivo worn dental composite restorations.

Dental composite restorations have been examined using a silver staining method to elucidate in vivo wear mechanisms. Emphasis was placed on examination of material immediately beneath the wearing surfaces. Several in vitro tests were also investigated for their ability to generate in vivo-like surface defects. For all the clinically worn composite restorations, a porous layer has been observed beneath those surfaces exposed to the oral environment. A laboratory test using certain substances to simulate the oral environmental effects can reproduce this porous layer. These results suggest that the in vivo wear process of dental composites is one accelerated by environmental softening of the composites.