COMPARATIVE EVALUATION OF THE EFFECT OF ER, CR: YSGG LASER DEBONDING OF DIFFERENT TRANSLUCENT CERAMIC MATERIALS ON MODE OF FAILURE IN VITRO STUDY

Background: In recent years, ceramic materials have been developed to offer both the mechanical strength and aesthetic qualities required for contemporary dental restorations. Among these, lithium disilicate glass-matrix ceramics have
gained significant popularity for applications.
Objectives: This study aimed to evaluate the efficacy of the Er,Cr:YSGG laser as a non-destructive tool for debonding lithium disilicate laminate veneers of varying thicknesses and to determine the associated failure modes.
Materials and Methods: Thirty extracted human maxillary first premolars of comparable dimensions were selected and randomly allocated into two groups (n = 15 each). Group 1 received high-translucency lithium disilicate glass-ceramic veneers, while Group 2 received low-translucency lithium disilicate glass-ceramic restorations. All veneers were bonded using RelyX Veneer resin cement (shade A1, 3M ESPE, USA). Following cementation, the specimens were stored in distilled water at 37 °C for 24 hours to simulate intraoral conditions. Debonding was performed using an Er,Cr:YSGG
laser (Waterlase iPlus, Biolase, USA) equipped with a turbo handpiece and MX7 sapphire tip.
Results: The longest debonding time was recorded for veneers with a thickness of 1.0 mm (5.960 ± 0.723 minutes), while the shortest time was observed for 0.5 mm thick veneers (5.653 ± 0.875 minutes). However, the differences in debonding times between groups were not statistically significant. Failure analysis revealed that debonding
predominantly occurred at the veneer–cement interface, with minimal impact on the underlying enamel.
Conclusion: These findings suggest that veneer thickness influences laser debonding efficiency, with thinner veneers being removed more rapidly.