Effect of Er:YAG Laser Irradiation on Shear Bond Strength of Two Porcelain Laminate Veneers Bonded to Tooth Surface

Background and aim: the conventional procedure for removal of porcelain laminate veneers (plvs) is time-consuming and inconvenient. the purpose of this study was to evaluate the efficacy of er:yag laser for debonding of plvs. materials and methods: forty-eight intact extracted human maxillary anterior teeth received discoid plvs (24 feldspathic and 24 e-max ceramic). the plvs had 0.7 mm thickness and 4 mm diameter. after cementation of all plvs with a light-cure cement, samples were stored at 37ºc distilled water for 48 h. samples of each ceramic were randomly divided into 3 groups of 8 samples. then, laser was irradiated on the cemented plvs as follows: (i) feldspathic plvs without laser irradiation (control group), (ii) feldspathic plvs with laser irradiation (6 s, 10 hz, 200 mj, 2 w), (iii) feldspathic plvs with laser irradiation (6 s, 10 hz, 300 mj, 3 w), (iv) e-max plvs without laser irradiation (control group), (v) e-max plvs with laser radiation (6 s, 10 hz, 200 mj, 2 w), (vi) e-max plvs with laser irradiation (6 s, 10 hz, 300 mj, 3 w). the shear bond strength of all samples was measured using a universal testing machine. we used mann-whitney and kruskal-wallis tests for data analysis (p<0.05). results: laser irradiation decreased the shear bond strength of both ceramics. but this decrease was only significant for the e-max group (p<0.05). no significant difference was found between different laser irradiation powers in the two ceramic groups. conclusion: er: yag laser is effective for debonding of e-max plvs.