Smart resin composite with acid-activated antibacterial monomers and calcium phosphate nanoparticles to resist dental caries.

OBJECTIVE

To develop a smart resin composite with acid-activated antibacterial effect and controlled release of calcium (Ca) and phosphate (P) ions to prevent secondary caries.

METHODS

Dodecylmethylaminoethyl methacrylate (DMAEM) and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into resin composite. Mechanical strength, cytotoxicity, Ca/P ion release, and the antibacterial effect in acidic and neutral medium were tested. The antibiofilm effect before and after 30-d microbial aging was investigated. The enamel hardness by enamel-restoration margins was measured under a 7-d biofilm model.

RESULTS

3% or 4% DMAEM and 20% NACP modified resin composite demonstrated similar flexural strength, elastic modulus and cytotoxicity with the control group (p > 0.05). The Ca/P ion release of DMAEM + NACP groups at pH 4 was over 4-fold greater than that at pH 7. The Streptococcus mutans biofilm activity and acid production of DMAEM + NACP groups in acidic medium was decreased by 95% (p < 0.05), while in neutral medium, the effect was attenuated. The DMAEM+NACP resin composite inhibited the saliva-derived biofilm activity and acid production, and reduced the CFU counts, both before and after aging (p < 0.05). After biofilm demineralization, enamel micro-hardness of DMAEM + NACP groups was twice that of control groups (p < 0.05).

CONCLUSION

The novel DMAEM + NACP resin composite showed persistent acid-activated antibacterial effect and Ca/P ion release, with good mechanical strength and low cytotoxicity. It also preserved the enamel micro-hardness at the restoration margins.

CLINICAL SIGNIFICANCE: The study on the smart multifunctional resin composite provides a promising strategy to inhibit secondary caries.