No abstract

Two methods of evaluating the in vivo wear of posterior composite restorations are described and compared with the USPHS direct clinical evaluation system. The three methods were consistent among themselves and over the two years of the study. In order of increasing sensitivity, the methods were: USPHS, total ranking of models, and categorizing of models according to a set of standards. The last procedure identified statistically significant differences (p less than 0.05) between the composite formulations as early as the nine-month recall. All formulations experienced increasing wear with time, but at a decreasing rate.

In a clinical evaluation of marginal deterioration, 475 amalgram restorations were equally distributed in a 6 X 4 X 2 X 3 factorial design, based on alloy, operator, tooth, and number of restored surfaces. All factors except the last had a statistically significant effect after 6, 12, and 18 months. There were no consistent two-way interactions over time.

A comprehensive clinical investigation of amalgam restorations was undertaken to evaluate the performance of "high copper' amalgams and the methods used to examine the marginal integrity of restorations. Six alloys, Aristaloy CR (A), Dispersalloy (D), Indiloy (I), an experimental "high copper' amalgam (E), Tytin (T), and New True Dentalloy (N) as a control, were randomly placed by four operators in 435 Class 1 and Class II restorations. Black and white 1 x photographs were taken at baseline, 6, 12 and 18 months and evaluated using the method described by Mahler & Marantz (1979). In addition, the U.S. Public Health Service system (Cvar & Ryge, 1971) was used at each recall. An analysis of variance based on photographic scoring indicated significant differences (P less than 0.05) among alloys at each recall. The use of Duncan's multiple range test resulted in two homogeneous subsets at 18 months: D, I, E and T, N, A. Six and 12 months recall data showed a close similarity in the rank order of the six alloys. The U.S.P.H.S. system showed no statistically significant differences between the alloys using the chi-square test, however, at each recall the rank order was comparable to that obtained with the photographic method.