EFFECT OF DENTIN SURFACE-ROUGHNESS ON SHEAR BOND STRENGTH

The aim of this investigation was to evaluate the effect of dentin surface roughness on the shear bond strength of a dentin bonding agent. Seventy-five dentin samples were divided into five surface preparation groups: (1) 60-grit SiC; (2) 320-grit SiC; (3) 600-grit SiC; (4) 600-grit SiC followed by Al2O3; and (5) 320-grit SiC followed by a #245 carbide bur. The prepared dentin was treated with a dentin primer, and one coat of dentin bonding agent was applied and light-cured for 30 s. Each dentin specimen was mounted in a device with a split Teflon mold (I.D. = 3.5 mm, depth = 5.0 mm). Three increments of a restorative composite were placed, compressed firmly, and light-cured for 30 s in the mold. After 24 h of storage, the bonds were stressed to failure in a mechanical testing machine at a cross-head speed of 0.5 mm/min. Weibull analysis was used to obtain a shape factor and characteristic level for each group. The results showed that, with the possible exception of the 600-grit SiC and Al2O3 group, the grit size used for preparation of dentin specimens for shear bond strength testing in this study did not significantly affect bond strength. © 1990.