: Various studies have revealed that the Er:YAG laser is effective in endodontic, periodontal and surgical treatments, and it is used in actual clinical practice. In particular, the Er:YAG laser shows excellent clinical effects when cutting hard tooth tissue, and there have been many studies on adhesive restoration involving teeth irradiated with Er:YAG laser. In this study, focusing on the one-bottle one-step bonding system, we performed tensile bond and marginal leakage tests to evaluate its adhesive properties to enamel and dentin irradiated with Er:YAG laser. Experiment 1Flat bovine enamel or dentin surfaces were prepared using a model trimmer and water-resistant polishing paper (#600) , and were irradiated with Er:YAG laser (100mJ, 10pps) . Non-irradiated specimens were used as a control. After bonding procedures were performed on these adherent surfaces of 3mm in diameter, the specimens were stored in 37℃ distilled water for 24 hours, and were divided into two experimental groups : the 24-hour storage group and the thermal stress group. In the thermal stress group, the specimens were subjected to 2,000 or 5,000 thermocycling in water from 5℃ to 55℃ with a dwell time of 30s at each temperature. Thereafter, a tensile bond test was performed in each group (n ＝ 10) . Experiment 2Saucer cavities (3mm in length, 2mm in width, and 1.5mm in depth) in extracted human molars were prepared setting the