Sealant bond strengths of CO₂ laser-etched versus acid-etched bovine enamel

Background and Objective: The purpose of this study was to evaluate sealant shear bond strength on bovine enamel with standard acid etching compared with CO₂ laser etching. Study Design/Materials and Methods: Bovine enamel was prepared either by acid or laser etching and divided into four experimental groups, either acid or laser-etched teeth with or without a primer. A gelatin capsule was used to place the sealant on the prepared enamel surface and the bond tested in shear. Also surface roughness was evaluated by using a surface analyzer and an atomic force microscope. Results: Shear bond strength results were the following: acid etch = 8.8 ± 3.8 MPa, acid etch with primer = 10.3 ± 5.5 MPa, laser etch = 4.0 ± 1.1 MPa, and laser etch with primer = 6.2 ± 2.3 MPa. Analysis of variance statistical analysis found no significant difference in bond strength between the acid-etched groups. However, the laser-etched groups had significantly lower bond strengths from the acid-etched teeth. In addition, a significant difference was observed between the laser-etched groups, where the use of the primer helped to increase the bond strength of the sealants. The surface roughness was significantly greater on the laser-etched teeth at the μm level (by using a surface analyzer) from the acid-etched and the control specimens. No difference in roughness (by using an atomic force microscope) was observed at the nanometer level between the laser and acid-etched teeth. Conclusion: For these particular settings, the laser-etched teeth resuited in lower bond strengths to enamel and the use of a primer increased the bond strength for laser-etched teeth only. (C) 2000 Wiley-Liss, Inc.