Effect of imaging powders on the bond strength of resin cement

The application and incomplete removal of a computer-aided design/computer-aided manufacture imaging powder may affect the dentin surface prior to bonding a ceramic restoration. The purpose of this study was to compare the effect of imaging powder residue on the shear bond strength of a self-adhesive resin cement to dentin. Mounted human third molars were sectioned coronally with a diamond saw to expose the dentin, which was then prepared with a diamond bur mounted in a custom jig. The dentin surface was sprayed with 3 different imaging powders. The 3 powder groups were then divided into 3 subgroups based on the method of powder removal: no rinse, 1-second rinse, and 10-second rinse. A control group was created that had no application of imaging powder. A self-adhesive resin cement was bonded to the surfaces and loaded to failure in a universal testing machine after 24 hours of storage. Data was analyzed with Kruskal-Wallis and Mann-Whitney nonparametric tests. The bonding to dentin surfaces of the powder groups that were rinsed for 1 or 10 seconds were not significantly different from each other or the nonpowdered control. The type of imaging powder did not significantly affect the bond strength. The nonrinsed powdered dentin surface had a significant reduction in bond strength compared to both the control and the rinsed powdered surfaces.