Effect of Antioxidant/NaOCl.Treatment on Bonding to Caries-Affected Dentin

Objectives: The aim of this study was to evaluate effect of antioxidant on the microtensile bond strength to normal and caries-affected dentin after treatment with NaOCl. Methods: Twenty extracted human molars with occlusal caries were used. The occlusal dentin surface was ground flat to expose normal and caries-affected dentin using #600 SiC paper under running water. The dentin surface including caries-affected dentin was treated with 6 % NaOCl solution for 30 s followed by application with aromatic sulfinate solution (Accel; SunMedical Co) for 0, 10, 30 s, or none (control). After rinsing off, the treated dentin surface was applied with Clearfil Protect Bond (Kuraray Medical Inc) according to the manufacturer's instruction and the crown was built up with resin composite. After water storage for 24 hours, the bonded specimens were serially sectioned into 0.7 mm-thick slabs and trimmed to hour-glass shape with 1 mm2 cross-section isolated by normal or caries-affected dentin, and then subjected to micro-tensile bond test. Data were analyzed by one and two-way ANOVA, and post hoc test (Dunnett T3 and T-test) (p<0.05). (mean±SD, MPa; N=10)

Results:

Normal Caries-affected

Control 42.0±8.1a p<0.05 29.4±7.5A

NaOCl 33.4±3.0b NS 32.6±5.1A

NaOCl/Accel(10) 41.3±6.7a p<0.05 32.7±6.2A

NaOCl/Accel(30) 38.7±3.7a NS 41.6±5.8B

Different letters indicate statistically significant differences. NS = no significant difference

Conclusion: For the control group, caries-affected dentin was significantly lower bond strength of self-etch system than normal dentin. However, after NaOCl treatment to dentin surface, antioxidant application before bonding can improve bond strength to caries-affected dentin, in which there was no significant difference between bond strength of normal and caries-affected dentin. The effect of antioxidant on bonding to caries-affected dentin treated with NaOCl was dependent upon the application time.