Shear bond strength of resin-modified glass ionomer cements to Er:YAG laser-treated tooth structure.

This study evaluated the effect of Er:YAG laser irradiation of enamel and dentin on the shear bond strength of resin-modified glass ionomer cements (RMGIC). Twenty molars were selected and the roots removed. The crowns were bisected, embedded in polyester resin and ground to plane the enamel or expose the dentin. The bonding site was delimited, and samples were randomly assigned according to the cavity preparation device: I--Er.YAG laser (350mJ/2Hz); II--Carbide bur (control group). They were subdivided according to the restorative material employed: A) Fuji II LC (GC); B) Vitremer (3M). Samples were then fixed to a metallic device where ionomer cylinders were prepared. Sequentially, the molars were stored for 24 hours and subjected to a shear bond strength test (50Kgf at 0.5 mm/minute). Means in MPa were: Enamel--IA) 4.77 (+/- 1.12); IB) 4.36 (+/- 1.50); IIA) 7.70 (+/- 1.53); IIB) 7.34 (+/- 1.52) and Dentin--IA) 3.13 (+/- 1.15); IB) 2.67 (+/- 0.74); IIA) 6.38 (+/- 1.44); IIB) 5.58 (+/-2.09). Data were submitted to statistical analysis by ANOVA. Adhesion for enamel was more efficient than for dentin (p < 0.01). The cavities prepared with a conventional bur (control group) presented higher bond strength values than those recorded for Er:YAG laser (p < 0.01). No significant differences were observed between the restorative materials. Based on these results, it was concluded that Er:YAG laser adversely affected the shear bond strength of RMGIC for both enamel and dentin.