Effect of femtosecond laser zirconia surface treatment on cement shear bond strength

It was aimed to evaluate the effects of conventional surface treatment techniques and femtosecond (FS) laser on shear bond strength (SBS) between zirconia and resin cement. 84 zirconia blocks (2 x 10 x 10 mm) (Zirkonzahn, Zirkonzahn USA Inc, USA) were divided into six groups (n = 14): group FS, FS laser application; group SB-FS, sandblasting followed by FS laser treatment; group FS-SB, FS laser treatment followed by sandblasting, group PS, plasma sputtering; group R, tribochemical silica coating; group SB, sandblasting with 110 mu m Al2O3. The resin cement (Panavia F 2.0, Kuraray Medical Inc., Tokyo, Japan) was applied to the samples and polymerized with a LED curing light. SBS test was performed on 72 samples (12 samples from each group) with a universal testing machine. The other two samples of each group were analyzed with SEM and profilometer. For statistical analysis, ANOVA and Tukey HSD tests were used. Although, there were no significant differences between the group SB (7.66 +/- 2.04 MPa), group PS (7.39 +/- 2.98 MPa) and group R (5.62 +/- 1.39 MPa) (p > 0.05), the SBS values of the group FS (13.35 +/- 2.48 MPa), group SB + FS (13.23 +/- 1.84 MPa) and group FS + SB (11.31 +/- 2.07 MPa) were higher than them with a statistically significant difference (p < 0.05). SEM images showed differences in surface morphology among the groups. According to the 3-D profilometer images, the Ra values of Group SB, Group R, Group PS, Group FS, Group FS-SB and Group SB-FS were 0.93, 0.98, 0.16, 6.40, 10.70 and 9.11, respectively. The FS laser surface treatment provided a significantly higher bond strength than the conventional techniques. It is not recommended to combine FS laser treatment with sandblasting.