Effect of Er-YAG Laser on Dentin Bonding Durability Under Simulated Pulpal Pressure

Purpose: To evaluate the effects of Er:YAG laser ablation on the microtensile bond strength and the nanoleakage of Er:YAG-lased dentin bonded to a self-etching adhesive system with and without pulpal pressure. Materials and Methods: Twenty flat dentin surfaces were obtained from extracted molars. Ten specimens were irradiated by Er:YAG laser, other specimens (control group) were ground using #600 SiC paper. Direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cementoenamel junction and parallel to the occlusal surface. The experimental groups were exposed to a simulated pulpal pressure of 15 cm H2O. Each specimen was restored using an adhesive and a photocured composite. The specimens were then sectioned vertically to obtain dentin/adhesive slabs. Ninety-six slabs were prepared for microtensile bond testing. Sixty-four slabs were immersed in ammoniacal silver nitrate tracer solution for 18 h, then rinsed thoroughly, and immersed in photodeveloping solution for 6 h prior to their examination by FE-SEM. Results: The method of dentin preparation and the pulpal pressure storage condition significantly affected the µTBS, while the storage duration did not (p 0.05). The nanoleakage patterns observed in the dentin/bond interface differed depending on whether the dentin was conventionally prepared or ablated by Er:YAG laser. Conclusion: Er:YAG laser ablation to dentin adversely affected the µTBS and the sealing ability of SE Bond bonded to dentin under simulated pulpal condition. Keywords: Er:YAG Laser, simulated pulpal pressure, microtensile bond strength, nanoleakage, resin-dentin interface