Evaluation of antibacterial and fluoride-releasing adhesive system on dentin bonding

Objectives: The aim of this study was to evaluate the influence of an acidic primer containing antibacterial monomer (MDPB) and fluoride containing adhesive on the microtensile bond strength (µTBS) in dentin, and to analyze the ultra-structure of the dentin-adhesive interface after acid-base challenge. Methods: The appraised groups were: G1-Clearfil SE Bond (SE); G2-Clearfil Protect Bond (PB); G3-Primer[SE]/Adhesive[PB]; and G4-Primer[PB]/Adhesive[SE]. For μTBS, eight dentin flat surfaces obtained from third molars were ground using 600-grit SiC paper. After applying each adhesive system according to the manufacturer's instructions, composite resin crown was incrementally built up, and the restored teeth were stored in distilled water at 37^oC for 24h. The specimens were sectioned in 0.8-mm² beams and tested to μTBS. In order to observe the dentin-adhesive interfaces, sixteen 1.5-mm dentin disks were ground using 600-grit SiC paper, the adhesive system was applied, and a low viscosity resin was placed between the 2 prepared dentin disks. The specimens were immersed in a buffered demineralizing solution (pH 4.5) for 90min and in 5% NaOCl for 20 min. After sectioning and polishing, the specimens were etched with argon-ion for 7min, and observed by SEM. Results: For μTBS, the data showed no statistical significant difference among the groups (G1-51.3MPa; G2-47.6MPa; G3-55.0MPa; and G4-53.9MPa). For interface analysis, an acid-base resistant zone was observed in all groups. The thick acid-base resistant zone adjacent to the hybrid layer was created only when the fluoride-releasing adhesive was used (PB). Conclusions: The presence of fluoride in the self-etching primer adhesive system demonstrated significant effects on preventing secondary caries, and did not interfere in the bond strength values.