Calcium Fluoride Precipitation and Deposition From 12mmol/L Fluoride Solutions With Different Calcium Addition Rates

Published

October 1, 2009

Author(s)

Milenko Markovic, Shozo Takagi, Laurence C. Chow, Stanislav A. Frukhtbeyn

Abstract

A model system was used to study the potential improved efficacy of fluoride (F) rinses with a built-in mechanism for continuous calcium (Ca) release. The effects of different Ca addition rates on calcium fluoride (CaF2) formation and deposition were determined. Precipitation kinetics of CaF2 and deposition into a model substrate were investigated in 12 mmol/L sodium fluoride (NaF) solutions to which 0.1 mol/L calcium chloride (CaCl2) solution was continuously added at average rates of (0, 5, 7.5, 10, 12.5, 15 or 20) mmol L 1 min-1 during 1 min time interval. The changes in ionic fluoride (F-) and calcium (Ca2+) concentrations, as well as turbidity, were continuously recorded by F and Ca electrodes, and a fiber optic based spectrophotometer, respectively. The F- concentration decreased and turbidity increased with time indicating precipitation of CaF2.The turbidity induction times were from 0 s to 15 s for the systems with Ca increase rates from 20 mmol L 1 min-1 to 5 mmol L 1 min-1 indicating inverse correlation. For the systems with Ca addition rates of (0, 5, 7.5, 10, 12.5, 15, and 20) mmol L 1 min 1, the 1 min CaF2 depositions in the model substrate (cellulose filter paper, pores 0.2 m) expressed as mean SD of deposited F per substrate surface area (in g/cm2) were 0.11 0.02, 3.78 0.31, 11.45 0.89, 9.31 0.68, 8.20 0.56, 6.63 0.43, and 2.09 0.28, respectively (n = 10 for each group). The largest F depositions were obtained from the system with Ca addition rates of 7.5 mmol L-1 min-1 to 12.5 mmol L-1 min-1 indicating that Ca addition rate could be a critical factor for the efficacy of such rinses. The F deposition was greatly enhanced in comparison with the control systems that did not have continuous Ca release.

Citation

Caries Research

Volume

114

Issue

5

Pub Type

Journals

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Keywords

calcium addition rate, calcium fluoride, fluoride deposition, model substrate, precipitation, sodium fluoride

Citation

Markovic, M. , Takagi, S. , Chow, L. and Frukhtbeyn, S. (2009), Calcium Fluoride Precipitation and Deposition From 12mmol/L Fluoride Solutions With Different Calcium Addition Rates, Caries Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852521 (Accessed October 16, 2025)