Comparative Reduction of Enamel Demineralization by Calcium and Phosphate in vitro

Abstract

In theory, calcium and phosphate in the plaque fluid exert a large influence on the demineralization of enamel surface. In order to know the effect of increasing the concentration of either of these factors, the following in vitro experiment was conducted. Three thin sections, about 150 Ìm thick, were cut out from each of 13 human premolars. All surfaces of the sections, except for the original enamel surface, were coated with nail varnish. These sections were immersed into one of two sets of demineralizing solutions for 1 week at 25°C. Each set, the ‘calcium set’ and the ‘phosphate set’, contained three solutions. The composition of these solutions differed mainly in calcium or phosphate concentrations. After 1 week, the degree of demineralization was determined by image analysis of contact microradiograms from each section. The subsurface demineralization in enamel was reduced by 95% by increasing the calcium concentration of the demineralizing solution from 7 to 21 mmol/l. A similar reduction (87%) was observed by increasing the phosphate concentration. However, the amount of phosphate needed was approximately 20 times more than that of calcium. The larger inhibitory effect that calcium has on enamel demineralization was related to the larger effect it has on the degree of saturation of the solution. Even though no statistically significant difference was found between the effect of calcium and phosphate on the demineralization of enamel (when the solutions had the same degree of saturation), the difference in the standard deviation of demineralization suggests the existence of some other factors which have an influence on the demineralization reaction.

The Effect of Fluoride at Plaque Fluid Concentrations on Enamel De- and Remineralisation at Low pH

“…an equivalent effect [Tanaka and Kadoma, 2000]. Our fi ndings indicate that the acid-gel systems are similar to plaque in that calcium activity was a relatively small fraction of total calcium concentration.…”

Influence of Beverage Composition on the Results of Erosive Potential Measurement by Different Measurement Techniques

“…Some authors have observed that a small change in the degree of saturation resulted in a difference in the dissolution of enamel and that it is an important parameter that defines the ability of a solution to demineralize enamel [Barbour et al, 2003;Finke et al, 2000;Margolis et al, 1999;Tanaka and Kadoma, 2000]. Only in a small volume of the beverages would a significant rise in saturation be expected.…”

The relationship between enamel softening and erosion caused by soft drinks at a range of temperatures

“…Although Robinson's and Ribena ToothKind have comparable phosphate concentrations, phosphate has been shown to be less effective at reducing enamel erosion than calcium. 15,18 .…”