Novel rechargeable calcium phosphate nanoparticle-filled dental cement

The objectives were to develop a novel rechargeable cement containing amorphous calcium-phosphate nanoparticles (nanoACP) to suppress tooth decay. Five cements were made with: (1) 60% glass particles (experimental control); (2) 40% glass+20% nanoACP; (3) 30% glass+30% nanoACP; (4) 20% glass+40% nanoACP; (5) 10% glass+50% nanoACP. Groups 1-4 had enamel bond strengths similar to Transbond XT (3M) and Vitremer (3M) (p>0.1). The nanoACP cement had calcium and phosphate ion release which increased with increasing nanoACP fillers. The recharged cement had substantial ion re-release continuously for 14 days after a single recharge. Ion re-release did not decrease with increasing recharge/re-release cycles. Groups 3-5 maintained a safe pH of medium (>5.5); however, control cements had cariogenic pH of medium (<4.5) due to biofilm acid. Therefore, nanoACP cement (1) had good bond strength to enamel, (2) possessed calcium and phosphate ion recharge/re-release capability, and (3) raised biofilm pH to a safe level to inhibit caries.