Objective: The aim of this study was to compare the shear bond strength (SBS), enamel surface characteristics, and the adhesive remnant index (ARI) scores of different etching methods.
Background data: Laser etching changes the physical characteristics of the enamel surface and these alterations hold promise for the conditioning of enamel for bonding procedures. A new Er:YAG laser handpiece is unique in its ability to digitally control size, shape, and depth of irradiated enamel area.
Materials and methods: Ninety-eight premolar teeth were used in this study. Eighty of 98 teeth were divided into four experimental groups of 20 teeth each for SBS testing: (1) 37% phosphoric acid, (2) manual Er:YAG laser (120 mJ, 10 Hz, and 1.2 W), (3) manual Er,Cr:YSGG laser (45 mJ, 50 Hz, and 2.25 W), and (4) digitally controlled Er:YAG laser (Xrunner; 100 mJ, 10 Hz, 1 W). The SBS values and ARI scores were recorded. Eighteen teeth were used to evaluate the surface morphology with scanning electron microscopy and atomic force microscopy after etching and following debonding and restoration.
Results: Mean SBS value was 7.75 ± 2.5 MPa for Xrunner and 8.11 ± 3.5, 9.47 ± 3.3, and 7.11 ± 3.7 MPa for the acid, Er,Cr:YSGG, and Er:YAG groups, respectively (p = 0.148). However, the acid etching group demonstrated significantly higher ARI scores (p < 0.001).
Conclusions: All etching methods caused enamel surface irregularities and were effectively restored to its original gloss. Laser etching was found to be an alternative to acid etching; however, the clinical success should be evaluated with further studies.
Keywords: AFM; SEM; laser etching.