Inhibition of Dentin Demineralization by Fluoride in vitro

Abstract

Compared with the knowledge accumulated on enamel-fluoride interactions, relatively little data is available regarding fluoride effects on dentin. This applies to both laboratory and clinical studies into the efficacy of fluoride schemes for the prevention of root surface caries. This study aimed to determine the effects of fluoride and pH on the demineralization of dentin, such as to provide information necessary to develop preventive programmes. Bovine dentin blocks were subjected to undersaturated calcium- and phosphate-containing solutions in the pH range 4.0–6.0 with fluoride added at concentrations between 0.5 and 10 ppm. Non-fluoride solutions served as controls. Mineral loss was assessed chemically and by transversal microradiography. Comparisons were made with similar studies on enamel demineralization. The results showed that demineralization of dentin depends on both pH and fluoride concentration in the demineralizing solution. Inhibition of demineralization that could be relevant from a clinical point of view was found at fluoride values 5–10 times the corresponding values for enamel. Also rapid depletion of fluoride from the solutions was observed, indicating the high uptake capacity of dentin for fluoride. Lesion depth depended on pH of the solution while the fluoride levels were associated with the surface layer, both in mineral content and depth. For dentin we propose a demineralization mechanism where acid penetrates rapidly into the tissue, presumably through the tubules, after which the released calcium and phosphate is partly trapped by the inward diffusing fluoride. This leads to the formation of a surface layer, which may even be hypermineralized compared to sound dentin.

Fluoride release and recharge characteristics of denture base resins containing surface pre-reacted glass-ionomer filler

“…According to ten Cate et al 26,27) , demineralization inhibition depends on fluoride concentration, and microradiographic data in vitro showed that 2 ppm fluoride in artificial saliva containing calcium and phosphate at pH 4.5 inhibited demineralization of enamel lesions, while dentin demineralization was inhibited in clinically relevant percentages (40％) at fluoride levels above 1 ppm. However, these fluoride concentrations would be toxic in clinical situations 28) . In our study, the total amounts of fluoride released were 5.61, 9.86, 18.1 and 30.4 ppm/3 ml/ day of the 5, 10, 20 and 30 wt％ specimens respectively on day 16.…”

Effects of resin-based temporary filling materials against dentin demineralization

“…LD, however, may be controlled by the pH of the solution rather than by the fluoride ion concentration 25) , suggesting that LD may not be an accurate parameter for measuring demineralization.…”

Evaluation of a new hardness tester (Cariotester): Comparison with transverse microradiography for assessing the inhibitory effect of fluoride application on bovine root dentin demineralization

“…This was consistent with previous studies showing the existence of linear relationships between the square root of the duration of demineralization and various parameters for quantifying the degree of demineralization (elution of calcium ions or phosphate ions) when specimens are demineralized under consistent demineralization conditions 21) . It is widely known that fluoride inhibits dentin demineralization and arrests caries progression 18,22,23) . In the present investigation, significant differences in CT depth between both fluoride and control groups were evident after the first day of demineralization ( Table 1).…”

“…Five microliters of the fluoride solution concerned was dropped onto the specimen surfaces in the NaF and APF groups and left for 5 min, after which the specimens were rinsed with distilled water and the remaining water was wiped off. The specimens were then immersed in demineralizing solution (2.2 mM CaCl 2, 2.2 mM KH2PO4, 50 mM CH3COOH, 3.1 mM NaN3, pH 5.02) 18,19) , and 10 specimens in each group were left in the demineralization solution at a constant temperature of 37ºC for 1, 3, 7, 14 and 21 days each. The demineralization solution was replaced with fresh solution at 7-day intervals 20) .…”