Bonding efficacy of highly translucent zirconia and lithium disilicate glass ceramics after femtosecond laser irradiation.

Purpose: This study investigated the effects of femtosecond laser (FL) irradiation on the surface roughness and shear bond strength of high-translucency zirconia (6 mol% yttria-partially stabilized zirconia [6Y-PSZ]) and lithium disilicate (LiSiO) glass ceramics.

Methods: Fully sintered square-shaped specimens of 6Y-PSZ (7 groups; 20 specimens/group) and LiSiO (8 groups; 20 specimens/group) were surface-treated via sandblasting (50-μm alumina sand or glass beads) or FL irradiation (20- or 40-μm dot or cross-line patterns) or using Monobond Etch & Prime (Ivoclar Vivadent AG; only for LiSiO specimens). The surface roughness (arithmetic average [Sa] and developed interfacial area ratio [Sdr]) and shear bond strength after 24 h and 10,000 thermal cycles were measured and statistically analyzed.

Results: The surface roughness of both ceramics significantly increased after 40-μm cross-line FL irradiation. The Sdr also significantly increased after FL irradiation. The 20- and 40-μm cross-line laser-irradiated 6Y-PSZ samples showed the highest shear bond strength after 24 h and 10,000 thermal cycles, respectively. LiSiO glass-ceramic specimens showed the highest shear bond strength after Monobond Etch & Prime treatment for both groups. The 40-μm cross-line laser-irradiated LiSiO glass-ceramic specimens exhibited high shear bond strength after thermal cycling.

Conclusions: FL significantly increases the bonding efficacy of 6Y-PSZ and LiSiO glass ceramics. Furthermore, Monobond Etch & Prime is effective for the surface treatment of LiSiO glass ceramics. Therefore, FL can be used to effectively treat the surfaces of dental restorations in clinical settings, facilitating enhanced adhesion between the restoration and the tooth.