Effect of Er:YAG laser on bond strength of glass ionomers

Objective: The aim of this study was to assess the effect of Er:YAG laser irradiation in the shear bond strength of resin-modified glass ionomer cements to dental enamel. Methods: Twenty sound human molars were selected and roots were removed. Crowns were bisected in half, embedded in polyester resin and grounded to plan the superficial enamel. The bonding site was delimited (3 mm-diameter) and samples were randomly assigned according to the cavity preparation device: I- Er:YAG laser (350mJ/2Hz); II - Carbide bur (control group); and subdivided depending on the restorative material employed: A) Fuji II LC (GC); B) Vitremer (3M). Sequentially, samples were fixed to metallic clamping devices and the ionomers cilinders were prepared using a split bisected matrix and Centrix injector, following the manufacturer¢s instructions. After a 24-h storage in distilled water at 37ºC, the specimens were subjected to a shear bond strength test (50Kgf at 0.5mm/min). Means in MPa were: IA) 4.77(±1.12); IB) 4.36(±1.50); IIA) 7.70(±1.53); IIB) 7.34(±1.52). Data were submitted to statistical analysis by ANOVA. Results: Cavities prepared with conventional bur (control group) presented higher bond strength values than those recorded for Er:YAG laser-prepared group (p<0.01). No statistically significant difference was found between the restorative materials. Conclusion: Er:YAG laser irradiation adversely affected the adhesion of resin-modified glass ionomer cements to dental enamel.