Novel Rechargeable Dental Nanocomposite With Antibacterial and Durable Remineralization Properties

Objectives: The incorporation of nanoparticles of amorphous calcium phosphate (NACP) and antibacterial dimethylaminohexadecyl methacrylate (DMAHDM) into composite showed improved caries-inhibition, remineralization, and antibacterial effects. There has been no report investigating the rechargeability of nanocomposite containing NACP and DMAHDM. The objectives were to develop a rechargeable NACP-DMAHDM composite, and evaluate mechanical properties, antibacterial effects, calcium (Ca) and phosphate (P) ion release and rechargeability.
Methods: Two nanocomposites were fabricated using pyromellitic glycerol dimethacrylate and ethoxylated bisphenol A dimethacrylate. The first composite contained no DMAHDM (control); the second composite contained 3% of DMAHDM (DMAHDM group). Both contained 20% NACP and 50% glass fillers. Specimens were tested for flexural strength and elastic modulus, biofilm colony-forming units (CFU), live/dead, metabolic activity, lactic acid production, and Ca and P ions release and rechargeability.
Results: Flexural strengths in MPa were 72.5±10.2 (control) and 70.6±4.4 (DMAHDM), comparable to commercial control composite 70.2±9.3 (p>0.1). DMAHDM group showed strong antibacterial potency by inhibiting biofilm metabolic activity, lactic acid and CFU, compared to control (p<0.05). Control and DMAHDM composites showed high Ca ion release in mmol/L of (6.82±1.10) and (7.91±0.69), and P ions (2.43±0.43) and (2.70±0.20), respectively, at 70 days; the two composites are not significantly different (p>0.1). After the 3rd recharge and re-release cycle, Ca release were (0.47±0.03) for control and (0.46±0.00) for DHAHDM, and P ions were (0.14±0.03) and (0.11±0.00), respectively; the two composites are similar (p>0.1).
Conclusions: Both composites had high Ca and P ion recharge and durable re-release which did not decrease with increasing the recharge cycles. The incorporation of DMAHDM into rechargeable composite did not adversely affect Ca and P ion release and rechargeability as well as mechanical properties. Therefore, strong antibacterial activity can be obtained for rechargeable composite without compromising Ca and P ion release and rechargeability, to achieve both antibacterial and durable remineralization capabilities.