Frictional behavior and surface failure of human enamel.

Historically, the study of the wear of hard dental tissues in modern man has been limited to clinical observation of physiologic and pathologic conditions that lead to wear, and to attempts to duplicate the effects of hygienic procedures such as the use of toothbrush and dentifrice on hard dental tissues in the laboratory. However, several fundamental investigations have been reported in which the wear of enamel and dentin under conditions of abrasion,1 and the damage done to enamel during preparative techniques such as grinding with highor low-speed diamond stones or carbide burs,2,3 were examined. A different approach to characterizing wear has been to examine a material under conditions of single-pass sliding. Such an approach has proven successful in studying the effects of sliding direction and environment on the frictional behavior and surface failure of natural fluorapatite single crystals.4 The purpose of the present study was to examine the frictional behavior and surface failure of human enamel and to determine the presence of a ductile-to-brittle transition (DBT) for human enamel.