TENSILE BOND STRENGTH OF DENTAL ADHESIVES BONDED TO SIMULATED CARIES-EXPOSED DENTIN

This study investigated the possibility of resin bonding to carious dentin. The study was divided into two parts, to determine first whether an in vitro model for caries could be developed for testing bond strength and second whether chemical modification of the caries model dentin surface, instead of mechanical removal of the carious layer, would enhance resin bond strengths. Dentin samples were exposed to an artificial caries decalcification solution (lactic acid + nitrocellulose) for 7 days. The depth of the decalcified surface was determined by microhardness and the nature of the surfaces analyzed by use of the scanning electron microscope. After bur removal of the decalcified dentin, samples were bonded with three different dentin bonding systems and the tensile bond strengths were determined. Control specimens were prepared and bonded with no decalcification or bur prepartion. These values were compared with specimens prepared by decalcification but with no mechanical removal of the decalcified surface layer before bonding. Additional decalcified samples were treated with phosphoric acid to modify the decalcified surface before dentin bond testing. Bond strengths were significantly higher (p < 0.05) for the decalcified and mechanically prepared dentin as compared with either the unmodified or the phosphoric acid modified decalcified dentin. The highest bond strengths for all systems were found for the undecalcified control group. These results suggest that it may be possible to bond to the collagenous structures remaining in carious dentin. This could lead to conservation of tooth structure and rethinking of cavity preparation design.