A study on the treatment of enamel white spot lesions using chitosan-calcium phosphate microgels loaded with EGCG-NPs

Background During orthodontic treatment, fixed orthodontic appliances complicate optimal oral hygiene maintenance, frequently causing white spot lesions (WSLs). Clinically, WSLs are typical chalky-white opacities on the enamel surface, recognized as the early reversible stage of dental caries. In this study, a novel antibacterial and remineralizing material—CEN composites (Chitosan-Ca 3 (PO 4 ) 2 , CS-CaP) microgels loaded with EGCG nanoparticles (NPs)—was designed to treat enamel white spot lesions. Methods Material characterization experiments were conducted on EGCG-NPs, chitosan-calcium phosphate microgels and CEN composites; the dialysis bag diffusion method was used to determine the composite drug release rate. Enamel blocks were prepared, an acid-etched demineralization model was established, and in vitro remineralization experiments were performed to screen the optimal CEN composite concentration for enamel remineralization and confirm the synergistic effect of EGCG-NPs on remineralization. The CCK-8 method was employed to assess the cytotoxicity of the CEN complex. Conclusion Material characterization experiments confirmed the successful synthesis of CEN composites. Drug release tests showed EGCG-NPs release rate reached 50% at 10 h and 80% at 70 h. In vitro remineralization experiments confirmed that the CEN-5 group was the optimal concentration for remineralization. In vitro experiments of the CEN-5 group demonstrated that EGCG-NPs significantly enhanced the gel’s remineralization efficacy. The CCK-8 assay demonstrated that the CEN composite possessed no cytotoxic effects.