Effect of Er: YAG Laser on Microtensile Bond Strength of Bleached Dentin to Composite

Introduction: in non-vital tooth bleaching, dentin is in direct contact with the bleaching agent, 1 to 3-week delay is needed to eliminate free radicals from tooth structure. the present study aimed to evaluate the effect of irradiation of er: yag laser on immediate microtensile bond strength of bleached dentin to composite. methods: sixty sounds human teeth were collected and randomly divided into 4 groups (n = 15): no bleaching (nb), opalescence endo hydrogen peroxide (hp) gel bleaching, sodium perborate (sp) bleaching and laser bleaching with heydent gel (lb). the groups were divided into 3 subgroups (n = 5): no surface treatment, er: yag laser irradiation and 10% sodium ascorbate (sa). all samples were restored and underwent microtensile bond strength testing. statistical analysis was carried out using one-way and two-way anova. results: bond strength in nb-sa group had a significant difference with the nb group (p < 0.05) while no significant difference was noted between nb and nb-er groups (p = 0.55). application of sa and er: yag laser after bleaching with sp did not enhance the bond strength (p = 0.07). conclusion: application of sa and er: yag laser after hp gel bleaching significantly enhanced the bond strength. application of er: yag laser after internal bleaching with hp gel could enhance the bond strength.