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

Objectives. Irradiation of enamel with carbon dioxide (CO2) laser ener gy alters physical and chemical properties of the enamel surface, and these lasers hold promise for conditioning enamel for bonding of adhes ive restorations. This laboratory study examined the influence of lase r irradiation parameters on the shear bond strength obtained for laser etching using a hybrid composite. Methods. Standardized surfaces prep ared on 110 non-carious intact extracted anterior teeth were exposed t o CO2 laser energy (9 different laser exposure parameters) or etched w ith orthophosphoric acid. Results. Laser treatment under defined condi tions (power density 2380 W/cm(2), energy density 23.8 J/cm(2)) result ed in a bond strength of 30.0 +/- 4.7 MPa, which exceeded that obtaine d for acid etching (17.9 +/- 4.3 MPa, p < 0.0001). Cohesive failure oc curred within the bonding resin in this group. Significance. These dat a indicate that CO2 laser etching may enhance the bonding of resin com posite to human enamel.