Measurement and analysis of clinical abrasion--a modified approach

The abrasion of three posterior composites, after three years' clinical service, was measured by use of a calibrated stone step-wedge. The enamel exposure by each cusp was measured, so that the maximum and overall abrasion could be calculated. The results indicated uneven abrasion around the margin, signifying that local factors, acting by each cusp, had a significant effect on abrasion. This differs from the behavior of the earlier composites, where there was uniform abrasion around the margins. The overall abrasion had a nonparametric distribution, and frequency distribution diagrams proved to be the best way of comparing the performances of the individual materials.