The Application of Resin Infiltration Combined with Nano-Hydroxyapatite in the Treatment of Post-Orthodontic White Spot Lesions

Abstract

This study aims to investigate whether the combination of resin infiltration and nanohydroxyapatite (nHA) can provide a synergistic treatment for post-orthodontic white spot lesions (WSL), thus establishing an experimental basis for its treatment. For this study, a total of 60 bicuspid teeth that required extraction due to orthodontics were collected. Orthodontic models were established for each tooth sample, and demineralization staining was conducted using Coca-Cola. The dental samples were randomly divided into 4 groups: control group, nHA group, resin infiltration group, and resin infiltration+nHA group. The demineralized samples were remineralized with 10% nHA and Icon resin infiltration, respectively. The samples were subjected to color difference observation, microhardness test, energy-dispersive X-ray spectrum analysis, and surface roughness detection. The results showed that the tooth surface of the control group was rough and dull after demineralization. The area around the bracket exhibited a brown color, greatly contrasting with the color of the surrounding tooth enamel. After the remineralization treatment with nHA and resin infiltration, the color difference decreased significantly and the microhardness increased. A significant difference was observed between the nHA group and the resin infiltration group (P < 0.05). However, the combination of resin infiltration and nHA exhibited superior staining resistance and improved WSL microhardness value. Additionally, nHA was found to enhance the mass ratio and molar ratio of calcium to phosphorus in WSL samples, while also reducing the surface roughness Ra, demonstrating a greater effectiveness compared to resin infiltration. The use of nHA following resin infiltration led to a significant improvement in mineral deposition and a substantial reduction in surface roughness. In conclusion, both resin infiltration and nHA play a crucial role in promoting enamel remineralization, offering their respective advantages in reducing color difference, increasing microhardness and calcium and phosphorus content, and reducing surface roughness in WSL samples. Remarkably, the combined application of resin infiltration and nHA enables resin infiltration to improve the remineralization and anti-coloring ability in WSL, while preserving its aesthetic effects. This combination demonstrates a positive application outcome.