Retention Improvement in Fluoride Application with Cold Atmospheric Plasma.

This study aimed to apply fluoride formulations to enamel with cold atmospheric plasma (CAP) and analyze the fluoride uptake, retention, and acid resistance quantitatively. Human enamel specimens were divided randomly into 2 groups: group APF1, 1.23% acidulated phosphate fluoride (APF) gel; group APF2, 1.23% APF gel with CAP. Fluoride and CAP were applied to the samples 4 times at 1-wk intervals. The specimens were also stored in artificial saliva for 4 wk to evaluate the retention of fluoride. The fluoride content on the fluoride-treated enamel was measured by an electron probe microanalyzer. To detect the resistance to demineralization, the calcium-to-phosphate ratio of the enamel samples was measured after the application of APF gel with or without CAP, followed by soaking in the demineralization solution. In groups APF1 and APF2, the amount of fluoride detected increased depending on the application frequency, and more fluoride was detected in group APF2 than in group APF1. In the experiment examining the maintenance effect, fluoride was not detected in group APF1, whereas fluoride was detected in group APF2 up to the fourth week. As for the resistance to demineralization, the calcium-to-phosphate ratio of the enamel treated with APF and CAP was higher than that treated with APF alone, and it increased with the frequency of treatment. This study suggests that the combination treatment of CAP and fluoride improves retention of fluoride on the enamel and resistance to demineralization when compared with treatment with fluoride alone.

Pharmacokinetic aspects of topical fluorides.

Pharmacokinetic studies have revealed quantitative information about the bioavailability, rate of absorption, distribution, and clearance of fluoride following the use of fluoride-containing dentifrices, gels, varnishes, and solutions. It is concluded that following the use of topical fluoride products, variable amounts of fluoride are swallowed and absorbed into the systemic circulation--amounts which may be sufficient to produce acute or chronic side-effects. Pharmacokinetic data should, therefore, form part of the basis for the optimal and safe use of fluoride products. In addition, there is a need for future research to determine the kinetics of fluoride in the oral fluids after the application of topical fluoride agents and to determine the associated changes in the composition of the mineral components of the oral fluids.

The effect of topical fluoride applications on the surface free energy of human enamel--an in vitro study.

The surface free energy gamma s and its polar and dispersion components gamma Sp and gamma Sd were determined from contact angle measurements on human enamel treated with sodium fluoride, acidulated phosphate fluoride (APF), and aminfluoride solutions. Sodium fluoride solutions only slightly influenced the surface free energy component gamma Sp. The gamma Sp value of the APF-treated human enamel increased from 52 to 66 erg X cm-2. The gamma Sp value after aminfluoride treatment decreased from 52 to 19 erg X cm-2. The gamma Sd values remained about 35 erg X cm-2 for all specimens measured. It is suggested that aminfluoride-treated enamel surfaces may exhibit a reduced tendency for bacterial adhesion.

Microprobe and SEM analysis of surface coatings on caries-like lesions in enamel after metal ion mordanting and APF application.

The production of tenacious surface coatings on enamel after metal ion mordanting followed by APF has been reported to prevent caries-like lesion initiation in vitro. In this study, similar surface coatings, which may be responsible for the inhibition of lesion progression, were examined using SEM and microprobe analysis. Relatively thick, even surface coatings which were in intimate contact with the enamel surface of caries-like lesions were seen after zirconium and iron (ferric) pre-treatment, but a thinner and unevenly distributed coating was seen after titanium pre-treatment. This latter coating was similar to that seen after APF treatment alone. Fluoride concentrations on the surface and in the subsurface of caries-like lesions were similar for all treatment groups. The surface coatings after zirconium and iron mordanting may be responsible for the greater inhibition of lesion progression than that seen after both titanium pre-treatment and APF treatment alone.

Fluoride deposited by topical applications with stannous fluoride in human enamel.

The aim of this study was to quantify the fluoridating effect of a 4% aqueous solution of SnF2 applied for 5 min. and 30 min. resp., and to measure the amounts of KOH soluble fluoride and acquired fluoride separately (APF gel data being included for comparison). Blocks of intact enamel were treated with the topical agents and subsequently exposed to 1 M KOH solutions for 24 h. No significant amount of fluoride was dissolved from control specimens by this treatment. Subsequently, the acquired F in the enamel was determined by the acid etch technique. The amount of fluoride in the KOH solutions after 5 and 30 min. SnF2 application are comparable : 6.2 and 7.4 micrograms . cm(-2) resp. A single topical treatment of SnF2 of 5 and 30 min. did not produce a significant enrichment of fluoride in the enamel. The considerable accumulation of fluoride reaction products on the outer enamel surface was only 1/3 of the amount deposited by APF gels.

The effect of contact time of acidulated phosphate fluoride on fluoride concentration in human enamel.

Polished enamel blocks with known surface areas were obtained from human mandibular incisors. Acidulated phosphate fluoride was applied for 4 min and washed off after additional contact times of 0, 2, 6 and 24 h, respectively. The enamel fluoride concentrations were determined in three successive etch depths before and after extraction in 1 M KOH for 24 h. The predominant reaction product was CaF2. The concentration of the fluoride bound as fluorapatite or fluorhydroxyapatite reached an optimal level after a 6-h contact time.

In vivo enamel fluoride uptake from and caries inhibition by topical fluoride agents.

Acidulated phosphate fluoride (APF), Duraphat or Fluor Protector, was applied to the molar teeth of rats fed a cariogenic diet. The first maxillary molar teeth were subjected to a microbiopsy procedure for fluoride analysis and the mandibular molars scored for caries. All three topical fluoride agents produced a significant increase in the fluoride content of the outermost 5.0 micron of enamel. Only APF produced a significant reduction in caries incidence at all sites.