Influence of provisional cements on ultimate bond strength of indirect composite restorations to dentin.

PURPOSE The aim of this study was to evaluate the effect of provisional cements on the adhesion of resin bonded indirect restorations and determine the best method for avoiding adverse effects. MATERIALS AND METHODS Forty-five bovine incisors were selected, and the enamel removed with a 600-grit SiC abrasive disk to expose superficial dentin. Provisional restorations of acrylic resin were cemented with three different provisional cements: calcium hydroxide cement, Dycal (HC); cement containing zinc oxide-eugenol, Provy (ZOE); zinc oxide eugenol-free cement, TempBond NE (ZNE). The specimens were stored at 100% humidity, 37 degrees C. Then provisional restorations were removed with: (1) hand scaler for 10 s; (2) pumice-water slurry for 10 s; (3) aluminum oxide sandblasting for 10 s. The indirect restorations were subsequently cemented with Single Bond and Rely-X ARC. The teeth were sectioned, 4 slices per tooth (n = 16), and each slice trimmed with a diamond bur to obtain an adhesion area of 1 mm2. The microtensile bond strength test was performed with a universal testing machine (Instron-4411) at a crosshead speed of 0.5 mm/min. The results were analyzed with ANOVA, followed by Tukey's test (p < 0.05). RESULTS ANOVA showed significant differences in the interaction between provisional cement and dentin cleaning method; in general, aluminum oxide sandblasting provided the highest values of bond strength and calcium hydroxide the lowest. CONCLUSION The type of provisional cement and its method of removal can affect the adhesion of resin-bonded indirect restorations.