Efficiency of Application Er:YAG Laser by Contact and Non- Contact Modes in Debonding of Porcelain Laminate Veneers (In-Vitro Study)

This study aimed to test the efficiency of debonding porcelain laminate veneers (PLV) by using two application modes of Er:YAG laser (contact and non-contact mode), and testing the change in dental pulp temperature for both application modes. Sixteen extracted, non-carious human maxillary premolars, prepared for receiving PLV, which fabricated of e.max and bonded by light cured resin cement. They divided into two groups, each of them had 8 samples based on the application mode; group A with noncontact mode, and group B with contact mode. Veneers of both groups debonded by the same laser parameters (360mJ, 15Hz) during loading of a 20newton force on a specially fabricated cervical margin of veneers. Debonding time and change of temperature was recorded, then entered into SPSS V.19 and T-test for independent samples was applied. All veneers were debonded, samples of non-contact mode group had much lower debonding time (12.6 second) than contact mode samples (96.3 second), but with higher change of temperature in non-contact (4.2 centigrade) than in contact mode (2.9 centigrade).p value was much less than 0.05%. Within limits of this study, we can conclude that non-contact application mode was more efficient in reducing debonding time than contact application mode at same laser energy and frequency parameters, but with a higher change in pulp temperature.