Effect of laser debonding on shear bond strength of two CAD/CAM ceramic veneering materials re-cemented to enamel.

Aim: Assess the debonding of different ceramic veneering materials using Er, Cr:YSGG laser on the shear bond strength to enamel upon re-bonding.M&Ms: 28 extracted central incisors were prepared to obtain enamel specimens, which were embedded in resin blocks. 28 CAD/CAM fabricated ceramic discs were produced and assigned to two groups (n = 14): Group T; advanced lithium disilicate ceramic (CEREC Tessera, Dentsply Sirona), and Group S; resin hybrid ceramic (SHOFU Block HC). Each group subdivided according to laser debonding protocol; into bonded (Subgroup B) and laser-debonded/rebonded (Subgroup R) specimens. Surface conditioning and bonding protocols followed the manufacturers’ recommendations. Subgroup R samples were debonded with an Er,Cr:YSGG laser, after which residual cement was removed. Specimens were then re-bonded. Shear bond strength was measured using a universal testing machine. Data underwent normality assessment using Kolmogorov–Smirnov and Shapiro–Wilk tests, followed by one-way ANOVA and Tukey’s post-hoc comparisons when significant differences were found.Results: The highest mean±SD values were registered for (TB) subgroup; (16.078±1.75 MPa) followed by (TR) subgroup mean±SD values; (12.939±1.96 MPa), while the lowest mean±SD values were recorded for (SB) bonded subgroup; (12.508±1.92 MPa). No data was recorded for the (SR) subgroup. The ANOVA test revealed a statistically significant difference among the groups (p = 0.0215 < 0.05). Tukey’s post-hoc analysis indicated no significant difference (p > 0.05) between the SB and TR subgroups.Conclusions: Tessera revealed a higher shear bond strength than hybrid ceramic and re-bonded Tessera. Exposing composite ceramics to Er, Cr:YSGG laser produced damage rather than debonding.