Influence of irradiation with Er:YAG laser on the shear bond strength of a resin cement to feldspathic ceramic - in vitro study

Although several conventional surface treatments have been used on feldspathic ceramic, a few studies investigated the effects of the irradiation with Er: YAG laser using different parameters. The aim of this in vitro study was to evaluate the shear bond strength of a resin cement to feldspathic ceramic, after the application of different surface treatments, especially the irradiation with Er:YAG laser. Forty-two discs made of a feldspathic ceramic were divided into six groups (n = 7): G1: control group - 10% hydrofluoric acid (HF), G2: Air abrasion with Al2O3 + HF; G3: Er: YAG laser with 500 mJ/4Hz, G4: Er: YAG laser with 500 mJ/4Hz: + HF; G5: Er: YAG laser with 400 mJ/6Hz and G6: Er:YAG laser with 400 mJ/6Hz + HF. After this, all the specimens were treated with silane, and then a resin cement cylinder was built on the treated ceramic surface. After 24 h at 37 oC, specimens were submitted to the shear bond strenght test and stereoscopic evaluation to determine the type of failure. The mean bond strength values (MPa) obtained were: G1 - 17.55, G2 - 18.80, G3 - 21.80, G4 - 12.62, G5 - and 15.81 G6- 11.59. After performing the ANOVA and Tukey's test, it was concluded that the group irradiated with Er:YAG laser at 500mJ/4Hz performed similarly to the groups that received the conventional treatments, such as hydrofluoric acid etching and the combination of air abrasion plus hydrofluoric acid, and was higher than the other groups irradiated with Er:YAG laser.