Development of novel dental adhesive with double benefits of protein-repellent and antibacterial capabilities

• The new adhesive containing 7.5% MPC + 5% DMAHDM had protein adsorption that was nearly 20-fold less than that of commercial SBMP control.
• Adding MPC or DMAHDM each alone greatly decreased the biofilm viability, CFU and lactic acid production, compared to SBMP control.
• Adding MPC and DMAHDM together in adhesive achieved antibacterial effects much stronger than each alone, reducing biofilm CFU by four orders of magnitude.
• Incorporation of 7.5% MPC and 5% DMAHDM into primer and adhesive to obtain protein-repellent and antibacterial activities did not compromise dentin bond strength.
• The use of double agents (protein-repellent MPC + antibacterial DMAHDM) in dental adhesive achieved much stronger inhibition of biofilms than using each agent alone.
• The novel protein-repellent and antibacterial bonding agent is promising to reduce biofilm/plaque buildup and reduce recurrent caries at the tooth-restoration margins.

ObjectivesSecondary caries at the tooth-restoration margins remains a main reason for restoration failure. The objectives of this study were to: (1) combine protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM) to develop a new dental adhesive with double benefits of protein-repellent and antibacterial capabilities for the first time; and (2) investigate the effects on protein adsorption, anti-biofilm activity, and dentin bond strength.MethodsMPC and DMAHDM were incorporated into Scotchbond Multi-Purpose (SBMP) primer and adhesive. Dentin shear bond strengths were measured using extracted human molars. Protein adsorption onto the adhesive resin surfaces was determined by the micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production and live/dead staining of biofilms on resins.ResultsIncorporation of 7.5% MPC and 5% DMAHDM into primer and adhesive did not adversely affect the dentin shear bond strength (p > 0.1). The resin with 7.5% MPC + 5% DMAHDM had protein adsorption that was nearly 20-fold less than SBMP control (p < 0.05). The resin with 7.5% MPC + 5% DMAHDM had much stronger antibacterial effects than using MPC or DMAHDM alone (p < 0.05). Biofilm CFU counts on the resin with 7.5% MPC + 5% DMAHDM were reduced by more than 4 orders of magnitude, compared to SBMP control.SignificanceThe use of double agents (protein-repellent MPC + antibacterial DMAHDM) in dental adhesive achieved much stronger inhibition of biofilms than using each agent alone. The novel protein-repellent and antibacterial bonding agent is promising to reduce biofilm/plaque buildup and reduce recurrent caries at the tooth-restoration margins.