effect of er:yag and er,cr:ysgg lasers on ceramic bracket debonding from composite blocks

Objectives: this study aimed to assess the effect of erbium-doped yttrium aluminum garnet (er:yag) and erbium, chromium: yttrium, scandium, gallium, garnet (er,cr:ysgg) lasers on the shear bond strength (sbs) of ceramic brackets debonding from the surface of composite blocks. materials and methods: thirty-six composite blocks were fabricated using filtek z250 light-cure composite. block surfaces were etched with 37% phosphoric acid for 30 seconds and then rinsed with water for 20 seconds and dried. maxillary right central incisor ceramic orthodontic brackets were bonded to the surfaces of composite blocks using transbond xt adhesive and were cured for 40 seconds. twelve samples were irradiated with er:yag laser, while 12 samples were irradiated with er,cr:ysgg laser, and the brackets were then debonded using a universal testing machine. twelve samples served as controls (debonding using the universal testing machine without using a laser). the adhesive remnant index (ari) score and bracket or composite cracks were evaluated under a stereomicroscope. one-way analysis of variance (anova) was used for the comparison of the three groups. kruskal-wallis test was used to compare the ari scores. results: the mean sbs was 17.01±5.22 mpa with er:yag laser, 18.03±6.46 mpa with er,cr:ysgg laser, and 16.61±6.73 mpa in the control group; the difference of the three groups was not significant (p=0.835). the difference in the ari scores and enamel and composite cracks was not significant either (p>0.05). conclusion: this study did not show any reduction in the bond strength of ceramic bracket to composite blocks after er:yag and er,cr:ysgg laser irradiation.