Morphological Evaluation of the Bovine Dentin prepared with High-speed Turbine or Er:YAG Laser and submitted to Different Adhesive Systems after Laser Etching

Abstract

ABSTRACT This study evaluated the effect of the Er:YAG laser at different settings on the surface of bovine dentin as well as adhesive systems. A total of 21 bovine teeth had their apexes embedded in chemically activated acrylic resin to allow sectioning of a dentin slice parallel to the buccal aspect of each tooth. Thus, group A (12 slices), prepared with the high-speed turbine, being four for analysis of the dentin surface, four for analysis of the interface and four for analysis of resin tags. Group B (9 slices) prepared with the Er:YAG laser, being three for analysis of the surface, three for analysis of the interface and three for analysis of resin tags. Each slice received a different treatment: etching with phosphoric acid, Er:YAG laser (60 mJ/10 Hz), conventional adhesive Excite (Vivadent) and self-etching adhesive One-Up Bond F (Tokuyama). For analysis of the interface, all slices were fractured for exposure of the resin/dentin bond. All slices were processed to allow evaluation by scanning electron microscopy. The results revealed that the Er:YAG laser employed both for preparation and dentin etching removed the smear layer, opened the dentinal tubules and yielded surface cracks; there was formation of a large amount and deep tags in the study groups, except for the slice prepared with diamond bur at high-speed and self-etching adhesive systems; the interfaces revealed adequate adaptation of the adhesive system/composite resin to the dentin, with little evidence of hybrid layer; also, the slice prepared with diamond bur, etched with phosphoric acid and receiving the Excite adhesive system displayed a porous hybrid layer.