Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces

Objectives: The aim of this study was to evaluate the bonding of four commercially available adhesive systems to ground and intact enamel surfaces. Methods: Extracted human teeth were used to measure the microtensile bond strength to enamel and a field-emission scanning electron microscopy (FE-SEM) was used to observe the bonded interface and the effect of the surface conditioning of each material. Intact buccal enamel surfaces were cleansed with tooth paste using a rotary dental brush, and the ground enamel surfaces were prepared by reducing approximately 0.5 mm from the buccal enamel surfaces using a high-speed diamond bur. One-Step (OS, Bisco), Single Bond (SB, 3M), Clearfil Liner Bond II (LBII, Kuraray), and Tokuso Mac Bond B (MBII, Tokuso) were evaluated for their ability to bond to enamel. Results: There was no significant difference in bond strengths between the materials when they were applied to ground enamel surfaces (p > 0.05). However, the bond strengths of the self-etching systems, LBII and MBII, had significantly lower bond strengths to intact enamel than the bonding systems OS and SB using phosphoric acid etching (p < 0.05). FE-SEM revealed that the etching pattern of self-etching primers was not deep enough to obtain good penetration of bonding resin when applied to intact enamel surfaces. Conclusions: Phosphoric acid etching produced good resin adhesion to ground and intact enamel. The self-etching/self-priming systems also produced good adhesion to ground enamel, but had lower bond strengths to intact enamel. (C) 1999 Elsevier Science Ltd. All rights reserved.