Adhesion to dentin after different methods on caries removal

Objectives: To evaluate the efficiency of different methods on root caries removal on the shear bond strength of a conventional glass-ionomer cement to the human dentin. Methods: Seventy-two root dentin slabs (5x5x3 mm) were obtained from human teeth. Specimens were covered with nail varnish except for an area of 3mm x 3mm in the center on the outer surface. Subsequently, root caries was induced using a microbiological model, except for the control group (sound). The specimens were randomly assigned to 6 groups (n=12), according to the process on root caries removal: G1:bur, G2:excavator, G3, G4 and G5 with Er,Cr:YSGG laser (λ=2.78 µm; 20Hz; ϕ=600µm) using power densities - 2.25W; 2.50W and 2.75W, respectively, G6:control (sound dentin). After cavity preparation it was performed the surface treatment. In the sequence, the cavities were restored and a cylinder was prepared for each specimen with glass-ionomer cement (Ketac-Fil Plus, 3M), using a split teflon matrix. The specimens were submitted to the shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min (50 kgf). Data were analyzed by one-way ANOVA and Fisher's test (α=0.05). Results: Means in MPa (SD) of the different groups were: G1 - 6.65 (2.5); G2 - 6.84 (2.4); G3 - 5.16 (1.7); G4 - 5.64 (2.1); G5 - 5.35 (2.1); and G6 - 7.65 (2.2). Statistical analysis revealed that the control group (sound root dentin) had the best result and statistically different from the laser groups and similar to bur and excavator. All experimental groups showed adhesion similar between them (p<0.05). Conclusion: The affected root dentin decreased the adhesion of glass-ionomer cement, mainly in the lased groups. However, the Er,Cr:YSGG showed the same adhesion to dentin than the other methods of caries removal. Supported by Fapesp (grant # 2008/07403-5)