The abrasion of dental composite by cobalt-chromium clasps.

In cases where there are no suitable natural undercuts on the teeth which can be used to provide clasp retention for a partial denture artificial undercuts can be created by the application of a composite filling material. An in-vitro investigation was undertaken to assess the surface integrity of three different composite restorative materials following repeated cycles of movement of cobalt-chromium I-bar clasps over artificial undercuts created using the composite materials. A laser reflection confocal microscope was used to quantify surface changes in the composite specimens. Simulation of the equivalent of 5 years of clinical usage showed that a composite resin with the smallest particle size exhibited the least surface wear.