Relationship between subsurface damage and wear of dental restorative composites

Pin and disc wear measurements were made on a commercial dental composite over a stress range from 2.5 to 20 MPa. The wear rates were found to increase suddenly during wear at times which tended to decrease with increasing stress. The results are interpreted in terms of wear mode conversion which results from the build-up of subsurface damage during wear. Micrographs showing damaged layers are compared with those from restorations worn in vivo.