Acid-susceptibility of lesions in bovine enamel after remineralization in the presence of fluoride and/or carbonate.

After de- and subsequent remineralization at 0.03 and 1.0 ppm fluoride and either 0, 1, 10, 20 or 25 mM carbonate, artificial lesions in bovine enamel were demineralized again. The amount of secondary demineralization was determined after 15, 30 and 70 h of demineralization by means of quantitative microradiography. The results showed that fluoride incorporated during the remineralization period retards lesion formation during secondary demineralization. Carbonate incorporated during the remineralization period enhances secondary demineralization. An interaction between both ions was observed.

Influence of fluoride and pH on in vitro remineralization of bovine enamel.

Subsurface lesions in bovine enamel slices were remineralized. The remineralization solutions contained either 0.03, 0.3, or 1.0 ppm fluoride at either pH 5.5 or 6.8. The amount of remineralization was determined after periods of up to 610 h, using quantitative microradiography. The results showed that after 126 h of remineralization in the presence of 0.03 ppm fluoride significantly (p less than 0.05) more remineralization occurred at pH 6.8 than at pH 5.5. At 0.3 and 1.0 ppm fluoride no significant differences between pH 5.5 and pH 6.8 were observed. An interaction between fluoride and pH was observed. The observed differences in the rates of remineralization are explained by the formation and subsequent transformation of the precursors octacalcium phosphate (pH 6.8) and brushite (pH 5.5) into (fluor)apatites.

Acid-susceptibility of lesions in bovine enamel after remineralization at different pH values and in the presence of different fluoride concentrations.

Artificial caries lesions were created in sound bovine enamel slices demineralized at pH 5.0. The lesions were then remineralized at either pH 5.5 or pH 6.8 in solutions containing either 1.5, 15, or 50 mumol/L fluoride. The remineralized slices were then demineralized at pH 5.0 for investigation of acid-susceptibility by means of quantitative microradiography. The results indicated that fluoride, incorporated during the preceding remineralization, had a retarding effect on the demineralization after remineralization, and that for the lowest concentration of fluoride in the remineralizing solution, the inhibitory influence of fluoride depended on the pH of the remineralization solutions used.

Influence of fluoride and carbonate on in vitro remineralization of bovine enamel.

The influence of fluoride, carbonate, and fluoride in combination with carbonate on the in vitro remineralization of bovine enamel was investigated with the use of a sandwich technique. After demineralization, enamel slices were subjected for 610 h to remineralizing solutions with 0.03 or 1.0 ppm fluoride. At each fluoride level, either 0, 1, 10, 20, or 25 mmol/L carbonate was tested. After 0, 22, 62, 126, 192, 329, and 610 h of remineralization, contact microradiographs were made by Cu K alpha-radiation. At 0.03 ppm fluoride, carbonate had an inhibiting influence on remineralization. At 1.0 ppm fluoride, the inhibiting influence of carbonate changed into a stimulation of remineralizatization at 20 and 25 mmol/L carbonate. At 0, 1, and 10 mmol/L carbonate, fluoride had an inhibiting influence on remineralization. The differences in remineralization between the groups were explained by events concerning crystal growth, i.e., different types of minerals might have precipitated with differences in precipitation rates, and retardation of a precipitation step might have occurred under the various remineralization conditions. There was a mutual influence of fluoride and carbonate on the remineralization process. We conclude that the composition of the remineralizing solution with respect to fluoride and carbonate concentrations is important for the remineralization process.

In vitro remineralization of caries lesions treated with surface-active phosphates.

Intact human enamel was demineralized in vitro to obtain artificial caries lesions. Part of the lesions was then treated with different surface-active compounds and remineralized with a remineralizing solution. The other part of the lesions was de- and remineralized in the same way, but was not treated with a surface-active compound. The results indicate that none of the surface-active compounds do affect the remineralization of the caries lesions. Possible applications of the tested compounds in combination with fluoride, for the prevention of dental caries, are discussed.

Influence of fluoride on in vitro remineralization of artificial subsurface lesions determined with a sandwich technique.

Remineralization experiments of bovine enamel with subsurface lesions were carried out with the use of a sandwich technique. The remineralizing solutions contained no or 2 ppm fluoride added to the solution. The amount of remineralization was determined after remineralization periods up to 324 by means of quantitative microradiography. After 84 h the group with fluoride showed significantly (p less than 0.05) less remineralization than the nonfluoride group. This inhibition of fluoride on the remineralization may be explained by the inhibiting effect that fluoride at certain concentrations has on the crystal growth of apatites.

The influence of fluoride on in vitro remineralization of bovine enamel.

Remineralization experiments using bovine enamel were carried out with 2 ppm fluoride or no fluoride added to the remineralizing solutions. The group without fluoride showed (quantitative microradiography) significantly more remineralization in the first 50 microns of the lesion than the fluoride group. It is suggested that fluoride may inhibit remineralization.