Efficiency of Er: YAG Laser in Veneers Debonding with Two Materials & Thicknesses-An in Vitro Study

Objective: To evaluate shear bond strength of laminate veneers after debonding attempt using: Er:YAG laser on two different ceramic materials: Lithium disilicate glass ceramic material and cubic zirconia, in two thicknesses: 0.3mm. 0.7mm. Materials and Methods: Fifty-six freshly extracted maxillary premolars were collected, examined and those with cracks or structural defects were discarded. The premolars were stored in saline during the study. The extracted teeth were embedded in acrylic resin blocks for fixation. Using IsometTM 4000, IPS E-max CAD and cubic zirconia specimens were sectioned with dimensions 4x4 mm and thicknesses 0.3 mm and 0.7mm under copious cooling. Cubic zirconia Samples were prepared so as to be 25% larger than the final required size. Results: Regardless of the ceramic thickness, E-max samples had statistically significant higher shear bond strength values than cubic zirconia samples in laser treated group. Regardless of the ceramic thickness, E-max samples had statistically significant higher shear bond strength values than cubic zirconia samples in control group.  It was found that Regardless of treatment, there was no significant difference between both groups. It was found that there was significant difference between both groups. Conclusion: Er:YAG laser is effective in glass ceramic veneer debonding. However, the effect is material dependant since lithium disilicate had superior laser transmission than cubic zirconia.  Ceramic thickness had a direct effect on debonding of veneers in E-max while showed no effect in the zirconia specimens due to it lower laser transmission. E-max showed higher bonding strength to enamel than with cubic zirconia.