Comparative In Vitro Study of the Effect of Er:YAG Laser on the Debonding of Lithium Disilicate Veneers With Two Different Surface Treatments.

Aim: To conduct a comparative study of lithium disilicate veneers treated with two different methods, hydrofluoric acid and Er:YAG laser, and to evaluate the role of the Er:YAG laser in their debonding time. Additionally, to examine bonding failure modes of veneers after debonding by both methods. Methods and Materials: The research sample consisted of 20 permanent human maxillary central incisors; they were divided randomly into two equal groups and prepared to receive lithium disilicate veneers. The surfaces of the veneers in the first group were treated with 9.5% hydrofluoric acid for 90 s, while those in the second group were treated with the Er:YAG laser with a wavelength of 2940 nm, a frequency of 15 Hz, an energy of 400 mJ, and a water/air cooling ratio of 8:4 for 20 s. Subsequently, veneers in both groups were bonded with resin cement. The Er:YAG laser (with a wavelength of 2940 nm, a frequency of 10 Hz, an energy of 400 mJ, and a water/air cooling ratio of 1:1) was used in a non-contact mode to debond the veneers, recording the time from the start of laser application until debonding. The bonding failure modes for all samples were then evaluated using a stereomicroscope under a 20× magnification. Data were analyzed with SPSS, a Results: Statistically significant differences were found in the debonding time of veneers using the Er:YAG laser between the two groups ( Conclusions: Lithium disilicate veneers treated with an Er:YAG laser require a longer time to debond compared to those treated with hydrofluoric acid when using the non-contact mode of the Er:YAG laser. The bonding failure mode was similar for both methods, showing adhesive failure between the veneer's internal surface and the resin cement.