Correlation between marginal adaptation of composite resin restorations and bacterial growth in cavities

The purpose of the present study was to correlate the marginal adaptation of composite fillings to the bacterial growth in the cavities. Forty-three cavities prepared in vivo on human third molars were acid etched and filled with the composite resin Concise. After 4 months the teeth were extracted and examined for marginal leakage along the restorations. After histologic preparation an average of 38 sections from each cavity were stained and investigated for bacteria on the cavity walls and in the exposed dentinal tubules. General marginal leakage was found in 14 of the restorations and bacterial growth in 12. For 35 of the 43 restorations there was a agreement between marginal leakage and bacterial growth (P = 0.0002). Based on the results it is concluded that bacteria in a cavity can be used as an indicator of marginal leakage along the restoration.