Wear patterns in two amalgams and three posterior composites after 5 yearsʹ clinical service

Objectives: The purpose of this research was to evaluate the wear patterns of three posterior composites (Clearfil Posterior. Occlusin and P-30) and two amalgams (New True Dentalloy, Solila Nova) after 5 yearsʹ clinical service. Methods: Marginal wear was measured using the stepwedge technique which determines the maximal marginal wear by any one cusp together with the mean marginal value. The overall maximum depth of wear, occurring at any site on the occlusal surface, was determined using an impression technique with epoxy models. Results: The mean values (± standard deviations) for the overall maximum wear were; New True Dentalloy. 203 ± 98 μm; Solila Nova. 200 ± 96 μm; Clearfil Posterior. 252 ± 141 μm; Occlusin, 324 ± 189 μm; P-30, 380 ± 273 μm. These values were significantly different (ANOVA F = 2.86 P = 0.05). There was no correlation between the marginal scores and the overall maximum depth of wear (P > 0.05). With some restorations the maximum wear occurred at the margins, marginal ridges or cavity extensions rather than sites of occlusal contact. Conclusions: After 5 yearsʹ service the overall wear of three posterior composites exceeded that of two amalgams; however, for a number of restorations the difference was not significant. Marginal wear values cannot be used to predict the overall maximal depth of wear.