The effect of dentin pre-treatment with activated riboflavin on the bond strength of a two-step self-etch adhesive system

Abstract

Background. The cross-linking of collagen fibers in the hybrid layer has been suggested as a way to create more durable bonds. Objectives. This study evaluated the effect of visible light-activated riboflavin (RF) as a cross-linking agent on the durability of the dentin microtensile bond strength (μTBS) in a 2-step self-etch (SE) adhesive system. Material and methods. The occlusal surfaces of 21 human premolar teeth were ground down to expose the dentin, and were then randomly divided into 3 groups. The Clearfil® SE Bond was used in the control group. In the RF/BL group, a 0.1 wt% aqueous solution of RF was applied to the dentin surface before applying the adhesive and irradiating with blue light (BL) for 2 min. In the 3rd group, the RF-P/BL group, the RF powder was added to the adhesive primer (P) at a concentration of 0.1 wt%. The teeth were built up using composite resin. After thermocycling, 14 resin–dentin beams from each group were prepared and stored in water for 3 months. The μTBS was determined and the data was analyzed using a linear model with a generalized estimating equation (GEE) (p = 0.05). Results. The highest and the lowest μTBS belonged to the control group (41.15 ±3.50 MPa) and the RF-P/BL group (19.84 ±3.80 MPa), respectively. The mean μTBS in the control group was significantly higher than in the RF/BL and RF-P/BL groups (p < 0.001), but no significant difference was found between the RF/BL and RF-P/BL groups (p = 0.598). Conclusions. Pre-treatment of dentin surfaces with RF activated with BL had a negative impact on the μTBS of the Clearfil SE Bond as a 2-step SE adhesive.