effects of 810 and 970 nm diode laser on microtensile bond strength of universal adhesives to tooth dentin

Background: some previous studies have suggested that laser irradiation improves the bond strength of composite to dentin. this study aimed to assess the effect of 810 and 970 nm diode laser on microtensile bond strength (µtbs) of universal adhesives to dentin. methods: in this in vitro, experimental study, the occlusal third of 54 extracted third molars was cut, and they were randomly divided into 9 groups (n=18). in groups 1-3, tetric n-bond universal (tnb), g-premio bond (gpb), and single bond universal (sbu) adhesives were applied, respectively and the teeth were built-up by applying three 1-mm thick composite increments. the same was performed for groups 4-6 and 7-9 with the difference that they underwent 810 and 970 nm diode laser irradiation (0.8 w, 20 s), respectively, prior to light curing. all the teeth were then sectioned into 1×1 mm blocks and their µtbs was measured. data were analyzed by two-way anova and tukey test.results: the interaction effect of type of bonding agent and laser irradiation on µtbs was not significant (p=0.79). there was a statistical difference between the bond strength of the adhesive systems used (p=0.009).conclusion: laser irradiation of universal adhesives applied by the etch and rinse (e&r) technique using 810 and 970 nm diode laser (0.8 w, 20 s) prior to their polymerization did not increase their µtbs to dentin.