RESUMEN
PURPOSE: This study was conducted to evaluate the shear bond strength of composite resin to dentin when etched with laser instead of phosphoric acid. MATERIAL AND METHODS: Recently extracted forty molars, completely free of dental caries, were embedded into acrylic resin. After exposing dentin with diamond saw, teeth surface were polished with a series of SiC paper. The teeth were divided into four groups composed of 10 specimens each; 1) no surface treated group as a control 2) acid-etched with 35 percent-phosphoric acid 3) Er:YAG laser treated 4) Er,Cr:YSGG laser treated. A dentin bonding agent (Adapter Single Bond2, 3M/ESPE) was applied to the specimens and then transparent plastic tubes (3 mm of height and diameter) were placed on each dentin. The composite resin was inserted into the tubes and cured. All the specimens were stored in distilled water at 37degree C for 24 hours and the shear bond strength was measured using a universal testing machine (Z020, Zwick, Germany). The data of tensile bond strength were statistically analyzed by one-way ANOVA and Duncan's test at alpha = 0.05. RESULTS: The bond strengths of Er:YAG laser-treated group was 3.98 +/- 0.88 MPa and Er,Cr:YSGG laser-treated group showed 3.70 +/- 1.55 MPa. There were no significant differences between two laser groups. The control group showed the lowest bond strength, 1.52 +/- 0.42 MPa and the highest shear bond strength was presented in acid-etched group, 7.10 +/- 1.86 MPa (P < .05). CONCLUSION: Laser- etched group exhibited significantly higer bond strength than that of control group, while still weaker than that of the phosphoric acid-etched group.