Aspects Regarding Fluoride Treatment for Reinforcement and Remineralization of Apatite Crystals

Abstract

The purpose of the present study was to investigate whether fluoride (F) ions are really capable of the repair (remineralization) of damaged crystals and useful for reinforcing the quality (i.e. modify the crystal structure) of tooth enamel using transmission electron microscopy and Raman microprobe analysis. Additionally, carbonic anhydrase activity was measured in immature enamel tissue to compare the harmfulness of F ions to that of cadmium (Cd) ions during the process of crystal nucleation by means of differential gas pressure analysis. Electron micrographs indicated no signs of remineralization of artificially damaged crystals after incubation in a remineralizing solution and further revealed that treatment with acidulated phosphate fluoride (APF) gel caused crystal dissolution rather than crystal improvement. Regarding crystal structure modification, Raman microprobe analysis revealed that no up-shift of PO 4 3-ν 1 band assigned to human sound enamel crystals occurred when APF gel was used. Furthermore, fluorapatite crystals were not generated by daily intake of F ions in developing rat tooth enamel. A differential gas pressure method demonstrated that the harmfulness of F exposure during the nucleation process of calcified hard tissues was much greater than that of Cd exposure. These results demonstrate that F treatments have no effect on improving crystal quality or remineralization and are inconsistent with the purpose of public health.

Fluoride Exposure May Accelerate the Osteoporotic Change in Postmenopausal Women: Animal Model of Fluoride-induced Osteoporosis

“…This is because F ions are only able to incorporate into the crystal structure through the precursor-octacalcium phosphate (OCP)-mediated pathway, which differs from the CDL pathway, meaning that acid-resistant fluorapatite is never created in tooth enamel by F intake [15]. Regarding this purported phenomenon of acid resistance of fluorosed enamel, their crystals show voids in the centers similar to those of caries lesions; therefore, the acid resistance of fluorosed enamel is merely superficial [15]. The reason for this is that the central areas of sound enamel crystals are less acid resistant than the peripheral areas due to the high content of carbonate ions.…”

“…Regarding whether F ions replace OH in hydroxyapatite in tooth enamel, dentin and bone, the recent findings obtained from Raman microprobe analysis clearly clarified that the incorporation of F ions into the lattice structure of apatite crystal never occurs in calcified hard tissues [15]. This is because F ions are only able to incorporate into the crystal structure through the precursor-octacalcium phosphate (OCP)-mediated pathway, which differs from the CDL pathway, meaning that acid-resistant fluorapatite is never created in tooth enamel by F intake [15].…”

“…Further, the combined effects of Es deficiency and Cd exposure were responsible for greatly increasing amorphous minerals and deceasing trabecular architecture in the bone, resulting in the development of "itai-itai disease" [13]. In the case of fluoride (F) exposure, the detrimental effect of F ions on the crystal nucleation process far exceeded that of Cd ions [14,15]. This led to the assumption that F schemes for caries prevention might leave postmenopausal women exposed to a high risk of developing osteoporosis without any beneficial effects.…”

Anti-carious Effects ofGalla chinensis: A Systematic Review

“…While the anti-carious efficacy of fluoride through inhibition of demineralization and promotion of incipient carious lesion remineralization has been demonstrated, there are still contrasting opinions about the employment of fluoride: fluoride has the risk of fluorosis through overexposure (Li, 2003), and although fluoride presents no problems to the healthy individual when used properly, fluoride exposure should be limited in certain populations who live in the high fluoride areas (Bassin et al, 2006). Further, some findings even raise doubt about fluoride use for caries prevention, suggesting that there is no absolute safe level of fluoride (Kakei et al, 2007;Kakei et al, 2012). These findings motivate a need to seek alternative, effective non-fluoride anticaries agents.…”