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



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


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.
Caries Research


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


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], (Accessed November 28, 2023)
Created October 1, 2009, Updated February 17, 2017