Effect of adding soluble calcium and pyrophosphate to fluoride toothpaste on enamel remineralization: An in vitro study

Abstract

Objectives

To compare the remineralization ability of a fluoride, soluble calcium, and pyrophosphate (FCaP) toothpaste with that of a fluoride-only toothpaste.

Design

Three toothpastes with identical base compositions were prepared: 1450 ppm fluoride (F = 76 µmol/g), 1450 ppm FCaP (F = 76 µmol/g, Ca = 23 µmol/g, P = 23 µmol/g), and 5000 ppm fluoride (F = 263 µmol/g). Soluble fluoride and calcium levels were evaluated by diluting each toothpaste with water (100 mg/10 mL). Bovine enamel specimens with artificially induced subsurface lesions underwent a 21-day pH cycling regimen, with continuous remineralization involving daily 2-hour demineralization and 3-minute toothpaste treatment. Post-pH cycling, quantitative light-induced fluorescence measurement, microhardness testing, and elemental composition analysis were performed (n = 10).

Results

The 1450 ppm FCaP toothpaste retained over 95 % soluble fluoride and 30 % soluble calcium. pH cycling test results revealed significantly higher remineralization and fluoride penetration in the 1450 ppm FCaP group than those in the 1450 ppm fluoride-only group (p < 0.05, Steel–Dwass multiple comparison test). No significant differences in enamel calcium-to-phosphorus ratios were observed among the three toothpastes. Interestingly, the 5000 ppm fluoride-only group showed significantly higher fluoride penetration but no improvement in remineralization than that in the other two groups.

Conclusions

The 1450 ppm FCaP toothpaste enhanced enamel remineralization more effectively than the fluoride-only toothpaste did. Clinically, FCaP toothpaste can help control dental caries, especially in individuals with low salivary calcium levels.