Pilot study of conditioner/primer effects on resin-dentin bonding after provisional cement contamination using SEM, energy dispersive x-ray spectroscopy, and bond strength evaluation measures

Abstract

Statement of problem. Previous studies have shown that provisional cement cannot be completely removed from the dentin surface and the remnants inhibit adhesion of resin cement to dentin. Purpose. This study investigated the effects of dentin conditioners on resin-dentin bonding after provisional cement contamination. Material and methods. A total of 216 bovine dentin specimens were divided into 2 groups with and without provisional cement coating on the dentin surface. Each group was further divided into 3 subgroups with 2 conditioning methods and without dentin conditioning (36 specimens per subgroup). The 2 methods applied were (1) phosphoric acid etching and (2) phosphoric acid etching, followed by sodium hypochlorite gel. Provisional cement was completely removed with a curette before dentin conditioning. Stainless steel rods were luted to dentin surfaces with Panavia 21 resin cement. Tensile bond strengths were measured before and after thermocycling. The dentin surface was analyzed by SEM and energy dispersive x-ray spectroscopy. Three-way ANOVA and Scheffe’s comparison test were performed ( P =.05). Results. Bond strength was significantly influenced by provisional cement application, type of dentin conditioning, and thermocycling. Bond strength decreased when treated with provisional cement, but the decreased strengths were restored to their original values or higher by both dentin conditioners used. Specimens treated with sodium hypochlorite gel applied after phosphoric acid etching demonstrated the highest bond strengths with good stability after thermocycling. Conclusion. Application of sodium hypochlorite gel after phosphoric acid etching was more effective than etching with phosphoric acid alone to eliminate the inhibitory effect of provisional cement remnants on adhesion between resin cement and dentin. (J Prosthet Dent 2000;83:349-55.)