μTBS of pre-treated demineralized dentin and a self-etching adhesive system

Abstract

Purpose: The aim of this study was to evaluate the effect of MI PasteTM and 0.2% NaF treatment on demineralized dentin on the microtensile bond strength ( TBS) of a etch and rinse adhesive system (Adper Single Bond 2-SB). Methods and materials: Twenty-four human third permanent molars withmid-coronal portion of dentin exposed were randomized in 4 groups (n=6) according dentin treatment: G1. SD-Sound Dentin/SB; G2. DD – Demineralized Dentin/SB; G3. RD/NaF – Dentin pre-treated with 0.2% NaF for 1min/SB; and G4. RD/CPP – Dentin pre-treated with MI PasteTM for 1min/SB. Before dentin treatment and bond procedures it was applied acid gel (6% carboxymethylcellulose and 0.1M lactic acid with KOH concentrated solution at pH 5.0) on 18 dentin surfaces producing a simulated caries-affected dentin. Adhesive/restorative procedure was performed constructing resin composite (Filtek Z350XT) blockswith 4mmheight. Theywere stored in deionized water for 24h, sectioned in beams (1mm2) and submitted to TBS test at 1.0mm/min and load of 50kgf. SEM (50× and 150×) evaluated the types of fracture. TBS data (MPa) were submitted to one-way ANOVA and Tukey tests and Kruskall–Wallis test for failure sites analyses (p<0.05). Results: RD/CPP showed the highest (45.25a) TBS values followed by SD (40.8b), and RD/NaF (33.4c). The lowest TBS were found for demineralized dentin (DD) – 26.4d. There was a predominance of adhesive (DD/SB), mixed (RD/NaF, DR/CPP), cohesive/composite (DH/SB). Conclusion:The pre-treatment of DDwith 0.2%NaF did not recover the TBSwhen SBwas used, but increased the TBS of DD. The highest TBS was obtained when DD was pre-treated with MI PasteTM (CPP/ACP). Dentin pre-treatment procedure showed to be a great approach for enhancing bond strength of etch and rinse adhesive system to demineralized dentin.