Shear bond strength of three CAD/CAM ceramics treated by Nd:YAG laser and HF

Abstract

The main purpose of this study is to evaluate the influence of different types of ceramics and surface treatment methods on the shear bonding strength(SBS). Three different CAD/CAM ceramics were divided into 4 groups, respectively according to the following surface treatments: no treatment; etching with 4.5% HF acid; Nd:YAG laser irradiation; Nd:YAG laser followed by HF acid etching and then a silane-coupling agent and resin cement (Variolink N) were applied to each block. All specimens were stored in water for 24 h. Surface morphology of each specimen was evaluated and the SBS value was measured. The data were statistically analyzed by two-way ANOVA and LSD’s multiple comparison test (p < 0.05). Among Celtra Duo, highest SBS values were obtained in NY groups (14.80 MPa), followed by NY + HF group and HF group; the significantly highest SBS values of IPS Empress CAD specimens were obtained in HF group (13.54 MPa) (p < 0.05) and the remaining groups were not observed significant differences (p > 0.05). Among IPS e.max CAD, the HF group (14.70 MPa) showed the highest bond strength, followed by NY + HF and NY groups. There were no significant differences between NY and NY + HF group (p > 0.05). Nd:YAG laser irradiation significantly improved the surface of Celtra Duo and IPS e.max materials, but this setting of Nd:YAG laser was not appropriate for IPS Empress CAD.