Marginal deterioration as a predictor of failure of a posterior composite

The purpose of the present study was to undertake a retrospective analysis of the findings of a multicentre clinical trial to test the hypothesis that marginal deterioration and cavomarginal discoloration may be a predictor of the failure of posterior composite restorations. Longitudinal 5-yr data from the multicentre trial of Occlusin were analysed (modified USPHS criteria data were available in respect of 1018 of the 1242 restorations included in the study). The 5-yr failure rate was calculated using three different methods. The various failure rates (maximum 18.8%) and the data pertaining to marginal deterioration and cavomarginal discoloration were then compared and contrasted by means of chi2 test. The analysis revealed that restorations with marginal deterioration at 3 yr were 5.3 times more likely to have failed by 5 yr than restorations with A (Alfa) rated marginal adaptation at 3 yr. Similarly restorations with cavomarginal discoloration at 3 yr were found to be 3.8 times more likely to have failed at 5 yr than restorations with no cavomarginal discoloration at 3 yr. Moreover, restorations with both marginal deterioration and cavomarginal discoloration at 3 yr failed 8.7 times more frequently than restorations with sound margin at 3 yr. It is concluded that clinical investigations of present-day materials for posterior composite should seek to determine if marginal deterioration and cavomarginal discoloration is an important predictor of the failure of posterior composites, especially when marginal deterioration and cavomarginal discoloration occur simultaneously.