Effect of multiple application of a dentin adhesive on contraction gap width of a resin-based composite.

Abstract

PURPOSE: To test the efficacy of the multiple application of a total-etch dentin adhesive was investigated by measuring (1) the contraction gap width of a light-activated resin-based composite in a cylindrical dentin cavity and (2) the early tensile bond strength to a flat dentin surface with the Single Bond Dental Adhesive System. MATERIALS AND METHODS: Contraction gap width was measured in a cylindrical dentin cavity (3 mm x 1.5 mm) treated with a single coat or double coats of the Single Bond adhesive and restored with Silux Plus or Z-100. As control, the cavity was treated with an experimental dentin bonding system consisting of EDTA, 35% GM and Clearfil Photo Bond. Early tensile bond strengths of Silux Plus or Z-100 were measured on the flat dentin surface treated with the three bonding procedures as in the contraction gap study within 10 min. after final cure. RESULTS: The contraction gap of Silux Plus and Z-100 was prevented with the double coats of the Single Bond adhesive, whereas the contraction gap of Z-100 was not prevented with the single coat of the Single Bond and the experimental system. When the film thickness of the Single Bond system was less than 2 microm, the gap could not be prevented. The tensile bond strengths of Silux Plus and Z-100 to flat dentin mediated with the three bonding procedures were not significantly different (P>0.05).