‘Calcium fluoride-like’ material formed in partially demineralized human enamel in vivo owing to the action of fluoridated toothpastes

Abstract

In this paper are presented the results of a chemical analysis of partially demineralized enamel lesions positioned under plaque in vivo for 3 weeks. During the experimental period the samples were brushed with fluoridated or non-fluoridated toothpaste systems. After the experiment the fluoride and protein uptake was determined. Furthermore, KOH extractions of the lesions were carried out and the solutions analyzed for calcium, fluoride, and phosphate. The results show that ‘CaF₂-like’ material is most likely formed inside lesions during the in vivo period. This is indicated from chemcial analysis, Raman spectroscopy, and SEM observations. The amount of CaF₂-like material is on the order of 0.1 wt% if we consider its formation all over the enamel lesions, or 1 wt% if we assume its formation in interprismatic regions of the enamel only. About 40% of the fluoride taken up from toothpaste systems is in the form of CaF₂-like material. In vivo there is a substantial influx of proteins (⌣0.3%) and also a very large influx of phosphate ions. The effect of CaF₂-like material is most likely strongly dependent on conditions in the lesion, such as pH change.