BONDING OF RESIN COMPOSITE TO CARBON-DIOXIDE LASER-MODIFIED HUMAN ENAMEL

Objectives. Irradiation of enamel with carbon dioxide (CO2) laser energy alters physical and chemical properties of the enamel surface, and these lasers hold promise for conditioning enamel for bonding of adhesive restorations. This laboratory study examined the influence of laser irradiation parameters on the shear bond strength obtained for laser etching using a hybrid composite. Methods. Standardized surfaces prepared on 110 non-carious intact extracted anterior teeth were exposed to CO2 laser energy (9 different laser exposure parameters) or etched with orthophosphoric acid. Results. Laser treatment under defined conditions (power density 2380 W/cm(2), energy density 23.8 J/cm(2)) resulted in a bond strength of 30.0 +/- 4.7 MPa, which exceeded that obtained for acid etching (17.9 +/- 4.3 MPa, p < 0.0001). Cohesive failure occurred within the bonding resin in this group. Significance. These data indicate that CO2 laser etching may enhance the bonding of resin composite to human enamel.