An epigallocatechin gallate–amorphous calcium phosphate nanocomposite for caries prevention and demineralized enamel restoration

Biomineralization with amorphous calcium phosphate (ACP) is a highly effective strategy for caries prevention and defect restoration. The identification and interruption of cariogenic biofilm formation during remineralization remains a challenge in current practice. In this study, an epigallocatechin gallate (EGCG)-ACP functional nanocomposite was developed to prevent and restore demineralization by integrating the antibacterial property of EGCG and the remineralization effect of ACP. The synthesized EGCG-ACP showed good biocompatibility with L-929 ​cells and human gingival fibroblasts. Under neutral conditions, the sustained release of ACP from EGCG-ACP restored the microstructure and mechanical properties of demineralized enamel. Under acidic conditions, protonated EGCG released from EGCG-ACP exerted a strong antibacterial effect, and the ACP release rate doubled within 4 ​h, resulting in the prevention of demineralization in the presence of cariogenic bacteria. The pH-responsive features of EGCG-ACP to promote the protonation of EGCG and ACP release facilitated its performance in remineralization effect to overcome the difficulty of restoring demineralized enamel in a cariogenic acidic environment, which was evidenced by the in vivo experiment carried out in a rat oral cariogenic environment. The results of this study indicate the potential of EGCG-ACP for the prevention of enamel demineralization and provide a theoretical basis its application in populations with high caries risk.