Novel Rechargeable Dental Adhesive With Antibacterial and Remineralizing Properties

Objectives: Nanoparticles of amorphous calcium phosphate (NACP) were shown to inhibit caries and promote remineralization. Incorporating dimethylaminododecyl methacrylate (DMAHDM) to adhesives provided antibacterial properties. The objectives of this study were to develop a novel rechargeable adhesive with antibacterial and remineralizing properties for the first time, and investigate physical and antibacterial properties, and calcium (Ca) and phosphate (P) ion release and recharge.
Methods: PMGDM (pyromellitic glycerol dimethacrylate), EBPADMA (ethoxylated bisphenol A dimethacrylate), HEMA (2-hydroxyethyl methacrylate), and BisGMA (bisphenol A glycidyl dimethacrylate) formed the parent adhesive (PEHB). Two adhesives were tested: (1) PEHB with 30% NACP (control); (2) PEHB with 30% NACP and 5% DMAHDM (experimental). Specimens were tested for shear bond strength, Ca and P ions release, and Ca and P recharge and re-release. A human saliva biofilm model was used to analyze live/dead bacteria, lactic acid production and colony forming units (CFU).
Results: PEHB had a dentin shear bond strength of (22.6±5.5)MPa, while PEHB+NACP had (24.0±4.8)MPa, and PEHB+NACP+DMAHDM had (21.7±5.7)MPa (p>0.05). Ca ion release was (4.40±0.18)mmol/L for control and (3.76±0.44)mmol/L for experimental group (p<0.05). P ion release was (1.91±0.08) and (1.47±0.2)mmol/L, respectively (p<0.05). Recharged specimens showed Ca re-release of (2.45±0.02) for control and (2.27±0.03) for experimental adhesive (p>0.05). P ion re-release was (1.35±0.03) and (1.24±0.03), respectively (p<0.05). Adding DMAHDM reduced Ca release by 15%, P release by 23%, and Ca and P re-release by 8%. Compared to the control, specimens with DMAHDM showed reduced lactic acid production by 85%, total microorganism by 4 logs, total streptococci by 3 logs, and mutans streptococci counts by 6 logs.
Conclusions: Adding DMAHDM to PEHB+NACP yielded an adhesive with antibacterial activities, as well as calcium and phosphate ion release, that can be recharged for long-term remineralization. PEHB+NACP+DMAHDM adhesive achieved both durable and rechargeable Ca and P ion release and strong antibacterial function.