Novel nanostructured resin infiltrant containing calcium phosphate nanoparticles to prevent enamel white spot lesions.

OBJECTIVES: The objective of this study was to develop a novel nanostructured resin infiltrant containing nanoparticles of amorphous calcium phosphate (NACP) to treat enamel white spot lesions (WSLs). Physical properties and the therapeutic effect of the new resin infiltrant were investigated for the first time.

METHODS: NACP was incorporated into ICON (Icon caries infiltrant, DMG, Germany) with different mass fractions. Cytotoxicity, degree of conversion, surface hardness, calcium (Ca) and phosphorus (P) ions release concentrations were tested. After application to the demineralized enamel samples, the color changes were determined. Surface and cross-sectional hardness were measured, scanning electron microscopy (SEM) images were taken on the cross-section of samples to observe microstructure changes after 14-day pH cycling.

RESULTS: Incorporating 10%-30% of NACP did not compromise the biocompatibility and physical properties of the resin infiltrant. ICON + 30% NACP group had long-lasting and high level of Ca and P ion release. After 14-day pH cycling, enamel surface hardness of ICON + 30% NACP group was 1.83 ± 0.21 GPa, significantly higher than the control group (1.32 ± 0.18 GPa) (p < 0.05). ICON + 30NACP group had the highest cross-sectional enamel hardness among all groups (p < 0.05), especially at 50 μm and 100 μm depth. SEM images showed that apparent enamel prism and inter-prism gaps in negative control were masked by mineral deposition in ICON + 30% NACP group.

SIGNIFICANCE: The novel ICON+30% NACP infiltrant is promising to inhibit enamel WSLs, protect the enamel and increase its hardness.