The Efficacy of Riboflavin for Collagen Cross-Linking and Optimizing the Bond Strength of an Etch and Rinse Adhesive System to Dentin

Background and Objectives: Previous studies have shown that increasing collagen resistance to degradation stabilizes the resindentin interface and collagen cross-linkers can prevent the degradation of collagen fibrils as such. This study sought to assess the efficacy of light-activated riboflavin for collagen cross-linking and optimizing the micro tensile bond strength (µTBS) of an etch and rinse adhesive system to dentin. Methods: Occlusal surfaces of 12 sound premolars were ground in order to expose dentin. The teeth were randomly divided into two groups. Adper single bond was applied on etched dentin and light cured in the control group and Composite was then applied. In the test group, all the steps were done in a similar manner to the control group with the difference that after acid etching, 0.1% riboflavin solution was applied on dentin surface and was activated by blue light irradiation for 2 minutes. After thermocycling, the teeth were sectioned in 2 directions in such a way that 14 resin-dentin sticks with 1 mm2 cross-section were prepared in each group (n = 14). The µTBS of samples was then measured and analyzed with independent t-test. The statistical analyses’ significance level was set at α = 0.05. Mode of failure was determined under a stereomicroscope at × 40 magnification. Moreover, the crosslinking effect of light-activated riboflavin solution on type I collagen was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and resin-dentin interface was photographed under a scanning electron microscope (SEM). Results: In gel electrophoresis, bands were formed in wells in the test group (and not in the negative control group). T-test found no significant difference in the mean µTBS of the test and the control groups (P = 0.9). Conclusions: Based on the results, light-activated riboflavin was capable of collagen cross-linking, but its application as a collagen cross-linker on etched dentin had no significant effect on µTBS of Single Bond dentin bonding agent to dentin.