Proximal wear rates by tooth position of resin composite restorations

Objective: The purpose of this study was to evaluate restorations, previously placed in clinical trials, for the rate of wear of the proximal surfaces, by tooth position. Materials and methods: Seventy resin composite restorations were evaluated in bicuspids and molars. Fifty restorations were direct placement restorations and 20 were indirect placement restorations. Thirty-five bicuspids and 35 molars were evaluated for proximal wear rate. All restorations were opposing unrestored enamel proximal surfaces. Ten enamel to enamel proximal surfaces were chosen as controls. At baseline, contacts were judged to be closed visually and with thin, unwaxed dental floss. Impressions were taken at baseline and after 6, 12 and 24 months for the fabrication of models. Measurements for proximal wear, as determined by a loss of space between indexed transfer copings, were made under a zoom stereomicroscope by two independent evaluators. A parametric ANOVA, Student-Newman-Keuls, and log curve fit were applied to the data. Results: When all data were pooled regardless of material, there were no significant differences (P < 0.05) in wear values for 1st and 2nd bicuspids and 1st and 2nd molars. Wear rates showed a high correlation (log curve fit R2 > 0.950) regardless of actual amount of wear. Conclusions: Regardless of composites examined, there were no differences in the amount of proximal wear with regard to tooth position in the arch.