Phosphoryl oligosaccharides of calcium enhance mineral availability and fluorapatite formation

Abstract

ObjectivesPhosphoryl oligosaccharides of calcium (POs-Ca) are a highly soluble calcium source and can keep the solubility of calcium and fluoride ions. The aim of this study was to investigate the effect of calcium (from POs-Ca) and fluoride ions penetrate into subsurface enamel lesions in vitro. DesignDemineralized bovine enamel slabs were remineralizedin vitro for 24 h at 37 °C with artificial saliva (AS) containing POs-Ca and various fluoride concentrations (0–100 ppm), or AS containing different levels of POs-Ca adjusted to a Ca/P ratio of 0.4–3.0 and fluoride, then were analyzed using Transversal microradiography. From those results, remineralization effects with optimal conditions were compared between POs-Ca and calcium chloride (CaCl2). To determine the form of incorporated fluoride, we analyzed the chemical state and local structure of fluorine atoms integrated into enamel subsurface lesions using micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. ResultsA significant mineral recovery rate was observed with POs-Ca and fluoride at 0.5 or 1.0 ppm (n = 6, p < 0.05), as well as a Ca/P molar ratio of 1.67 (n = 5, p < 0.05). Under those conditions, the mineral recovery rate of AS containing POs-Ca (37.9 ± 7.3%) was significantly greater than that of CaCl2 (15.0 ± 9.6%) (n = 5, mean ± SD, p < 0.05). μ-XANES spectra analysis of the samples indicated that the dominant form of fluorine atoms in enamel subsurface lesions was fluorapatite. ConclusionsPOs-Ca with fluoride-derived diffusion into subsurface enamel lesions facilitated formation of fluorapatite phases.