influence of different power outputs of er:yag laser on shear bond strength of a resin composite to feldspathic porcelain

statement of the problem: porcelain may fracture or chip if exposed to any traumas and can be repaired by using a resin composite. purpose: this study was aimed to evaluate the influences of er:yag laser on shear bond strength (sbs) of resin composite to feldspathic porcelain. materials and method: seventy-two porcelain blocks were divided into six groups (n=12): g1: no treatment (control group); g2: 9% hydrofluoric acid (hf); g3-6 were separately irradiated with er:yag laser using four energy parameters: 2w, 100mj (g3); 3w, 150mj (g4); 4w, 200mj (g5) and 5w, 250mj (g6), respectively; and 20 hz frequency in long-pulse mode. after silane treatment, a resin composite rod was bonded to each of the porcelain block. the sbs was measured following storage and thermocycling. data were analyzed by one-way anova, tamhane and chi-square tests. results: the highest sbs (12.29±3.04 mpa) was obtained with hf (g2). the lowest sbs (2.23±0.60 mpa) was observed in g4, followed by g3 (1.96±0.76 mpa). g6 had a significantly higher sbs (8.00±2.22 mpa) than other laser irradiation groups. conclusion: although, er:yag laser irradiation at 5w, 250mj/20 hz was effective in promoting adhesion of resin composite to feldspathic porcelain compared with the control group, it cannot be used as a safe alternative method to hf acid. laser irradiation with the evaluated parameters in this study does not promote an effective adhesion on porcelain surface to create adequate bond for clinical use.