The Effect of Laser Etching Alone or Combined With Acid Etching on the Surface Morphology of Enamel: A Scanning Electron Microscopic Study

Background Objective: Laser use and applications in dentistry has increased dramatically in the last years. Laser etching of enamel may provide an alternative for conventional acid etching. The aim of this study was to evaluate, under Scanning Electron Microscope(SEM), enamel surface morphology after laser irradiation with or without the addition of photoabsorber (black ink); with or without acid etching. Materials Methods: The buccal surface of twenty freshly extracted human molars was made flat by diamond abrasive discs and the teeth were randomly divided into four groups: Group 1: Laser only, Group 2: laser + acid etching (10 seconds), Group 3: Black ink + laser, Group 4: Black ink + laser + acid etching (10 seconds). All the groups were irradiated with Nd:YAG laser using the following parameters: 160 mj, 35 pulse/second., 5.6 watts for a total irradiation time of 15 seconds. The treated surfaces were examined with SEM using different magnification powers. Results: Laser exposure of enamel produced surface alterations and irregularities that differed among treatment groups. More surface roughness resulted when black ink was used in group 3 compared with group 1. Acid etching after laser irradiation in groups 2 and 4 showed, in addition to the surface irregularities found in groups 1 and 3, areas of conventional etching pattern of enamel prisms. Conclusions: laser enamel etching produced surface roughness that might be used for the infiltration and subsequent mechanical retention of resin.