Effect of Different NaOCl Concentrations on MTBS of a Dual-curing Dentin Adhesive

Objectives: The aim was to evaluate the effect of different concentrations of NaOCl on microtensile bond strength (mTBS) of a dual-curing total-etch adhesive (LuxaBond-Total Etch) in combination with a dual-curing composite (Luxacore Z-Dual) on pulpal dentin in vitro. Material and Methods: Seventy-two extracted third molars were included. Dentin specimens of the pulp chamber were obtained under standardized conditions. The specimens were randomly assigned to one of the six groups of twelve samples each: L-C: Luxabond/Luxacore (light-curing), control (no NaOCl-application); L-1: immersion in 1% NaOCl (24 hours) before bonding, L-5: immersion in 5% NaOCl (24 hours) before bonding; groups C-C, C-1, C-5 followed the same procedure using the self-curing mode. Results: After light-curing following mTBs could be observed (MPa): L-C: 30.9 (±3.7); L-1 26.6 (± 4.8); L-5: 19.8 (± 2.0). After using the self-curing mode mTBS was as followed: C-C:23.1 (± 4.4); C-1: 21.5 (4.6); C-5: 18.3 (2.1). Statistical analysis showed a significant influence of the used curing method and the different NaOCl concentrations (p0.001, ANOVA). The application of 1% and 5% NaOCl before bonding resulted in a reduction of mTBS. In the case of 5%, this difference was significant. Pairwise comparison between both curing groups showed no significant differences between L-C/C-C and L-1/C-1 (p 0.05, Tukey's test). Conclusions: It can be concluded that the curing method might have an influence on mTBS. The application of higher concentrations of NaOCl prior to bonding decreases mTBS. Clinical relevance: NaOCl is commonly used in endodontic treatment and might have an influence on mTBs. Keywords: microtensile bond strength, NaOCl, dentin adhesive