A fluoride rechargeable resin adhesive with long-term antibacterial effect for improved dental treatment

Polymerization shrinkage of composite resin during curing can form microcracks between the restoration and tooth tissue, facilitating bacterial colonization at the bonding interface and increasing the risk of secondary caries. Thus, developing antibacterial adhesives is crucial. This study synthesized a fluoride-containing dimethylaminohexadecyl methacrylate salt (DMAHDM-F) as a co-monomer to create a fluoride-rechargeable resin adhesive (FD-A) with long-term antibacterial properties. FD-A exhibits stable shear bonding strength, curing kinetics, high mechanical properties, and excellent biocompatibility. Its fluoride release can be sustained for over 1 year, achieving efficient antibacterial effect associated with the quaternary ammonium groups, being superior to those adhesives containing only NaF nanoparticles or quaternary ammonium groups. Of note, the FD-A adhesive is recharged with 10 ppm NaF solution after the one-year release test, and the re-fluorinated sample continues to release more fluoride ion, maintaining its antibacterial efficacy for extended period, which is a welcomed feature for dental applications. In summary, the photopolymerizable fluorinated quaternary ammonium salt provides a potential solution for making dental resin adhesives and composites with stable antibacterial effect to enhance the longevity of dental restorations.