An in vivo experiment to determine the wear of restorative materials (gold, ceramic, and microfilled resin) was performed in a patient with bruxism. Telescopic crowns were placed on teeth 35, 36, and 37. The opposing surfaces were all made from ceramic material. The weight loss of the materials was recorded after 30, 60, and 90 days and converted to volume loss. Replicas for scanning electron microscopic studies were obtained. Gold and ceramic material wore equally, while the wear of microfilled resin was two and a half times as much. The ceramic material and the microfilled resin chipped and fractured, but the gold did not. Mainly abrasive and fatigue types of wear were found in all materials.