CaF₂ Formation: Cariostatic Properties and Factors of Enhancing the Effect

Abstract

CaF₂ or a CaF₂-like material/phosphate-contaminated CaF₂ is a major reaction product during topical treatment of dental hard tissues. Recently, evidence has suggested that CaF₂ is formed not only on surfaces but also to some extent in the enamel. The minimum concentration of fluoride required for CaF₂ formation is not well known and may depend on whether calcium is available from plaque fluid or only through dissolution of the dental hard tissue. Furthermore, surface adsorption of fluoride to crystals may cause local concentrations necessary for CaF₂ formation. It has been suggested that CaF₂ acts as a pH-controlled reservoir of fluoride. The rate-controlling factor appears to be phosphate, which controls the dissolution rate of CaF₂ at high pH. Increasing fluoride concentration, prolonging the exposure time or using a fluoride solution with low pH can increase CaF₂ formation. CaF₂ formed at low pH contains less internal phosphate which has been shown to be less soluble. This may be of clinical significance for fluoride applied topically a few times per year.

Effects of zinc fluoride on inhibiting dentin demineralization and collagen degradation <i>in vitro</i>: A comparison of various topical fluoride agents

“…The acidic ZnF 2/HCl solution would be neutralized when applied to the dentin surface. Thus, ZnF2/HCl was expected to produce precipitations of Zn 2+ -containing compounds, such as phosphate and fluoride, and CaF2-like materials 26) . These compounds are inherently less soluble at a range of neutral pH, providing a reservoir for zinc and fluoride.…”

TiF4 Varnish-A 19F-NMR Stability Study and Enamel Reactivity Evaluation

“…However, the decrease in CaF 2 formation could interfere in inhibition of the dynamic of caries process, due to its capacity to act as a pH-controlled reservoir of ions on enamel and dental plaque that can be released during cariogenic challenges. 17,18) …”

Effect of Polyols on Phosphorus-Containing Calcium Fluoride Deposition on Hydroxyapatite Surfaces

“…Two different types of F -uptake have been shown to occur on the surface of enamel: firmly-bound and loosely-bound F -(as CaF 2 ) 10) . CaF 2 can work as a reservoir of F -in enamel and support remineralization of firmly-bound F -because CaF 2 shows higher solubility and provides F -at a neutral or lower pH 26) . Recently, it has been revealed that CaF 2 nanoparticles are also eff ective at suppressing formation of Streptococcus mutans biofi lms 27) .…”