Formation of alkali-soluble fluoride on the surface of human dental enamel after treatment with fluoridated gels: influence of the pH variation and of the treatment time

The aim of this study was to quantify, in vitro, the formation of CaF2 after the application of three fluoridated gels: one neutral, one acidulated and another highly acidulated, on a bovine enamel dental surface treated with a Dijkman's demineralizing solution (1990). 145 sections were utilized, obtained from 145 sound teeth and divided into seven groups: C (enamel without treatment); FN1 (enamel demineralized and treated with neutral gel for 1 minute); FN4 (enamel demineralized and treated with neutral gel for 4 minutes); FFA1 (enamel demineralized and treated with acidulated gel for 1 minute); FFA4 (enamel demineralized and treated with acidulated gel for 4 minutes); FAA1 (enamel demineralized and treated with highly acidulated gel for 1 minute) and FAA4 (enamel demineralized and treated with highly acidulated gel for 4 minutes). The formation of CaF2 was analyzed by SEM and chemically by Caslavska's method (1975). The average and standard deviations from the groups studied were respectively: C-0.63; 0.38; FN1-23.06; 16.52; FFA1-54.11; 49.00; FAA1-43.87; 32.66; FN4-34.92; 23.00; FFA4-67.91; 42.36; FAA4-56.03; 38.96. (Mann-Whitney non-parametric test). The time of application did not interfere in the CaF2 formation from the acidulated and highly-acidulated gels. A minor concentration of fluoride and amount of pH from highly-acidulated gel did not affect the higher formation from the CaF2 in relation to the acidulated gel in both cases when the application was evaluated.

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