an in vitro comparison of the bond strength of composite to superficial and deep dentin, treated with er:yag laser irradiation or acid-etching

introduction: the aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and erbium-doped yttrium aluminum garnet (er:yag) laser. methods: thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. specimens were ground to expose superficial and deep dentin. samples were assigned to six groups: (1) as (acid etching of superficial dentin); (2) ad (acid etching of deep dentin); (3) ls (er:yag laser irradiation on superficial dentin); (4) ld (er:yag laser irradiation on deep dentin); (5) las (er:yag laser irradiation on superficial dentin followed by acid etching); (6) lad (er:yag laser irradiation on deep dentin followed by acid etching) the adhesive protocol was performed. samples were thermocycled and micro-shear bond strength was tested to failure. the data were submitted to statistical analysis with one-way analysis of variance (anova) and tukey post hoc test. results: the as group, demonstrated the greatest amount of micro-shear bond strength. statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. conclusion: preparation of dentin with laser did not improve bonding to superficial and deep dentin.