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 t ‐test was used to compare debonding time, and a chi‐square test was applied to analyze failure modes. Results Statistically significant differences were found in the debonding time of veneers using the Er:YAG laser between the two groups ( p < 0.05). The hydrofluoric acid group showed a shorter mean debonding time 114.2 ± 37.22 s compared to the Er:YAG laser group 187.3 ± 64.49 s. Additionally, no statistically significant differences were observed in the frequencies of bonding failure modes of veneers between the two groups ( p > 0.05) with adhesive failure at the veneer–cement interface being the most common type. 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.