Purpose: To evaluate composite/dentin tensile bond strength on pretreated dentin surfaces using 2940-nm Er:YAG laser operating under a microsecond pulsed regime with different laser pulse repetition rates, followed by a re-wetting dentin solution. Materials and Methods: Forty extracted human third molars were randomly distributed into four groups, according to dentin pretreatment: G1: (control) 37% phosphoric acid + adhesive; G2: Er:YAG laser irradiation with 80 mJ energy for 20 s at a repetition rate of 5 Hz + acid + re-wetting agent + adhesive; G3: irradiation at 10 Hz + acid + re-wetting agent + adhesive; G4: irradiation at 15 Hz + acid + re-wetting agent + adhesive. The adhesive system was Adper Single Bond (3M ESPE) and the hybrid composite resin was Z100 (3M ESPE). The obtained values from tensile bond strength test in MPa were submitted to statistical analysis with ANOVA followed by the Tukey test. Results: G2 showed the best results of the lasered groups, demonstrating significant bond strength resistance similar to that of the control group. Conclusion: Varying the laser pulse repetition rate (pps) can lead to different composite/dentin tensile bond strengths, even followed by re-wetting HEMA solution. The lowest pulse repetition rate (5 Hz) promoted the highest tensile bond strength between the adhesive restoration and irradiated dentin.
Keywords: Er:YAG laser, re-wetting agent, dentin, repetition rate, tensile bond strength