Abstract
This in vitro study was performed to investigate effect of delayed composite application on dentin bonding durability of water-based all-in-one self-etch adhesive system using micro-tensile bond strength (MTBS) testing. Fifteen freshly extracted, non-carious premolar teeth were randomly selected. After removing the roots, the teeth were occlusally trimmed to expose superficial dentin. Then, the exposed occlusal dentin was bonded with a self-etching adhesive (Tetric-N Bond self-etch; Ivoclar/Vivdent) according to the manufacturer's instructions. After that, the samples were divided equally into 3 groups based on the time of application of Tetric-N Ceram composite resin (Ivoclar/Vivdent, Liechtenstein). In group 1, the composite build-up was carried out immediately after curing the adhesive, and polymerized according to the manufacturer instructions. In groups 2 and 3, the samples were restored after 1 and 5 min following adhesive curing, respectively. After 24 h storage, each bonded sample was sectioned into beams (0.7 mm × 0.7 mm) for MTBS testing. Results of the MTBS were analysed and tested using one-way ANOVA and post hoc Tukey test at significance level of 5%. The results showed that applying composite restoration immediately after adhesive curing gave strength of 11 ± 6 MPa. Composite application after curing the adhesive by 1 and 5 min showed 16 ± 8 MPa and 11 ± 5 MPa, respectively. The 1 min delayed application group had significantly higher bond strength than the other tested groups (p > 0.05). In conclusion, delaying the composite application after polymerization of water-based all-in-one adhesive for 1 min showed better bond strength.