The wear of a posterior composite in an artificial mouth: a clinical correlation

The wear of a posterior composite against a maxillary palatal cusp was studied in an artificial mouth. The coefficient of wear for the composite was 2.58×10^-5. A retrospective clinical correlation with composite wear in the artificial mouth showed a correlation coefficient of 0.84 at 1 year of wear. The artificial mouth studies support a parabolic relationship between depth of composite wear and time. The ratio of 6 months depth of wear compared to 3 years was found to be 41% which supports the Leinfelder finding (5) of 49%. However, the correlation with the linear studies of Braem (2,3) was good as far as the mean depth of wear at 1 year was concerned. The disagreement between the linear and parabolic studies is small during the early wear process, but becomes serious during a longer term. It is important for future clinical wear studies to resolve the question of the nature of the wear rate curve in posterior composites, if accurate prediction of long term performance is to be achieved.