A SEM and TEM study of the stability of CaF 2-like precipitates formed on dental enamel surfaces

Treatments of human tooth surfaces with fluoride-containing tooth pastes and rinses cause the formation of CaF2-like globular precipitates acting as fluoride reservoirs and, thus increasing the efficacy of dental prophylaxis products with respect to caries inhibition. The aim of the investigation was to study the stability and microstructure of the deposited material during demineralization / remineralization cycling and under in situ oral conditions by electron microscopy. It was shown that a consideral number of fluoride containing deposits was still present at the tooth surface after demin/remin cycling up to 24 h and after in situ treatments of up to 10 days while no significant changes in the chemical composition were found. The electron microscopy results indicate that saliva contributes to enhance the chemical stability of CaF2 globules under in situ conditions.