Statement of Problem:
Erbium-doped yttrium aluminum garnet (Er:YAG) laser debonding has recently emerged as an alternative method for removing zirconia and lithium disilicate restorations. The optical and mechanical properties are critical factors influencing the success of ceramic restorations. However, limited research has focused on how the Er:YAG laser impacts the optical and mechanical properties of these ceramic materials.

Objectives:
To investigate the effect of Er:YAG laser debonding treatment on the inherent optical and mechanical properties and surface roughness of different zirconia and lithium disilicate ceramic materials.

Materials and Methods:
Forty disc-shaped specimens (14 × 1.2 mm) were fabricated of three different tetragonal zirconia polycrystal (TZP) materials based on their yttria (Y) concentration (3Y-TZP, 4Y-TZP, and 5Y-TZP) and lithium disilicate (IPS E.max) as a control group (n = 10 per group). Each specimen was irradiated with the Er:YAG laser at 335 mJ, 15 Hz, 5.0 W, and 50-μs pulse duration (super short pulse mode). Color change (ΔE00), translucency parameter (TP), biaxial flexural strength (MPa), and surface roughness (Ra) values were measured before and after laser irradiation. Data were statistically analyzed using ANOVA and Tukey HSD post hoc tests (p < 0.05) at the 95% level of confidence.

Results:
For ΔE00, except for 3Y-TZP, all groups displayed an increase in color change beyond the defined acceptability threshold of 1.8. No significant changes in the mean values were observed following Er:YAG laser treatment, except for the 3Y-TZP zirconia group (p < 0.05). TP values showed no significant differences (p > 0.05), except for the IPS E.max group, where TP increased significantly after laser treatment (p < 0.05). Regarding biaxial flexural strength, mean values revealed a significant increase in the 5Y-TZP zirconia and IPS E.max groups (p < 0.05). No significant change in surface roughness values was reported (p > 0.05).

Conclusion:
Er:YAG laser debonding treatment altered some optical and mechanical properties of certain dental ceramics. Nevertheless, the reuse of ceramic restorations remains a feasible and clinically valuable option in dental practice.