Direct and indirect evaluation of posterior composite restorations at three years

The purpose of this study was to compare the use of direct (USPHS) and indirect (M-L) systems of evaluating the occlusal wear of posterior composite restorations. Additionally, this study has utilized the USPHS method to compare the in vivo performance of posterior resin composite restorations made from four different visible-light-cured materials. Of the 202 restorations placed for this randomized clinical trial, only those restorations that were scored by both direct and indirect evaluation systems were included in these comparisons. Restorations were evaluated by two calibrated examiners from baseline to 36 months. While there were some differences noted among the four materials, the majority (99%) of the restorations evaluated in this study received "alpha" or "bravo" scores for all USPHS parameters, indicating acceptable in vivo performance. The results of this study also indicate that there was a consistent relationship between the direct (USPHS) and indirect (M-L scale) scoring systems. For those restorations that changed anatomic form scores, the mean wear at the alfa/bravo transition was 100 +/- 80 microns. By the 24-month recall examination, the use of the USPHS evaluation system category of anatomic form enabled examiners to differentiate restorations and materials that had experienced little occlusal wear from those that had experienced greater amounts of wear.