In vitro enamel fluoride uptake from topical fluoride agents

The F acquired by enamel from APF, Duraphat and Fluor Protector was evaluated in this in vitro study. The topical F agents were applied to the tooth surfaces for 4 min, the teeth were suspended in synthetic saliva and the topical F agents removed after 2 h or 4 h. The teeth were resuspended in synthetic saliva for 1, 3 and 6 months, respectively. Three successive enamel biopsies were done on the control and experimental tooth halves and the F and P content of the etching solutions determined. The fluoride concentrations were adjusted to standardized depths of 3.0, 6.0 and 9.0 μm, respectively. Enamel acquired significantly more F from Fluor Protector and Duraphat than from APF. The fluoride acquired by enamel from the topical F agents was inversely related to the enamel F concentration prior to topical F application.     

Fluoride uptake in bovine enamel and dentin from a fluoride-releasing composite resin

To determine the fluoride uptake in enamel and dentin, a fluoridating composite resin was fixed at a 100-microns distance from bovine enamel and dentin for 2 weeks. The results revealed a substantial increase in the level of fluoride in both enamel and dentin. This model investigation showed that the fluoride released by the composite resin was effectively taken up by the surrounding tissues. The fluoride released from the composite resin and the subsequent uptake by the tissues would be expected to protect against secondary caries.     

In vitro fluoride uptake by bovine enamel from aesthetic restorative materials

Objectives.  The purposes of this in vitro study were to determine whether different types of fluoride-containing restoratives produce differing levels of fluoride uptake by bovine enamel, and to determine the effect of time on this uptake.
Methods.  Seven aesthetic restorative materials were evaluated. Forty bovine enamel slabs were prepared for each tested material, five of which were used to determine baseline fluoride concentrations. Each slab was attached to a disc of the tested material and suspended in synthetic saliva for up to 64 days. After removal, the specimens were acid etched with perchloric acid, and the dissolved enamel was analysed for fluoride and calcium. Fluoride was determined by direct potensiometric analysis, whereas the amount of calcium was evaluated by means of atomic absorption spectrophotometry.
Results.  Higher values of fluoride uptake, not significantly different, were recorded in the first two groups. A statistically significant difference was found in fluoride uptake between Fuji II LC and the three compomers in all test intervals. No significant differences were found in the amounts of fluoride uptake between the three compomers. The highest fluoride uptake from all compomers was recorded by F2000.
Conclusion.  Enamel acquired significant amounts of fluoride from all materials with variations during the test intervals.     

Comparative uptake of fluoride ion into enamel from various topical fluorides in vitro

Background : There are many forms of topical fluoride available today, making the decision as to which is most effective to manage the immediate caries risk problem at hand, very difficult. The objective of this project was to determine the concentration and pattern of fluoride ion uptake into enamel from a variety of categories of topical fluoride recently available in Australia.
Methods : Extracted, intact molar teeth were sectioned to provide six plates of smooth surface enamel. Windows of enamel 2 times 6mm were exposed to a variety of topical fluorides for periods simulating those used in vivo. Following drying, the slates of enamel were exposed to 2ml of 0.1M HCl as a chemical biopsy agent for incremental periods of time. The concentrations of fluoride ion in the biopsy solutions for both test and background (control) slates of enamel were determined directly using a fluoride combination selective electrode in conjunction with a high impedance pH meter. Cumulative amounts of fluoride were determined for each topical fluoride agent.
Results : The concentrations of fluoride ion taken up into enamel were generally proportional to those present in each agent. However, those from APF gel greatly exceeded the amounts taken up from NaF gel. Also, the concentrations taken up from some of the highly concentrated metal fluorides were surprisingly low. Prior etching of enamel increased uptake and prolonged application of APF gel provided no extra benefit.
Conclusions : Some topical fluorides, e.g., APF gel, provided a greatly increased uptake and to a greater depth than other self-application products. However, the frequency of its use should be considered with caution where patients have glass-based restorations.     

Fluorine and tin uptake by enamel studied by x-ray photoelectron spectroscopy (ESCA).

ESCA has been combined with argon-ion etching to obtain depth profiles for SnF2-treated enamel. Three zones of products from the topical treatment are detected: a layer of tin oxide on the surface; fluoroapatite + hydroxyapatite at depths below about 0.2 micron; an intermediate layer CaF2, Sn(OH)2, Sn2PO4OH, and fluoroapatite between the two. Sn3F3PO4 was not detected.     

In vivo bovine enamel remineralization and fluoride uptake from two dentifrices containing different fluoride concentrations

In this study, the differences in lesion remineralization and fluoride uptake after brushing with a 300 ppm F or a 1000 ppm F dentifrice (as NaF) were investigated. Twenty volunteers with partial dentures in their lower jaws were divided into two groups. Bovine enamel slabs with artificial lesions were mounted in the dentures. After a test period of six weeks, the slabs were taken out and analyzed. There was no statistically significant difference between the two groups, in F-uptake and susceptibility of the enamel to demineralization, although the findings favored the 1000 ppm F toothpaste. The microradiograms in the 300 ppm F group showed lesions more pronounced than those in the 1000 ppm group. The present study cannot support the presumption that the fluoride content of regular NaF dentifrices can be lowered to 300 ppm F without undesirable effects on lesion arrest and remineralization.     

Distribution and uptake of magnesium by developing deciduous bovine incisor enamel

Magnesium concentrations determined in deciduous bovine enamel at different stages of development were similar to those previously published for human and rat enamel ranging from 0.1 to 0.4 per cent. Highest concentrations, i.e. greatest uptake, occurred after secretion, in the transitional and maturing enamel. Uptake had occurred throughout the tissue thickness and was not confined to the surface. Magnesium probably enters enamel in the tissue fluid which replaces the organic matrix. Some magnesium is lost as fluid is replaced by calcium and phosphate but part is retained probably on or near crystal surfaces.     

The in vitro uptake of fluoride by secretory and maturation stage bovine enamel

The objectives of this study were to determine the specific surface area of secretory-stage and of maturation-stage enamel, to compare the fluoride uptake by isolated enamel at these two stages on a surface-area basis, and to examine the effect of the organic matrix on the fluoride uptake by whole enamel. Fetal bovine secretory and maturation stage enamel samples were collected, and a portion of the enamel at each developmental stage was treated with hydrazine for removal of the organic matrix. The specific surface areas of the enamel mineral, as determined by the multi-point BET method, were 59.3 m2/g in the secretory stage and 37.9 m2/g in the maturation stage. Whole and deproteinated enamel samples were equilibrated in buffered solutions containing 10(-5) to 10(-3) mol/L fluoride, and the uptake was measured with a fluoride specific electrode. The results indicate that the in vitro fluoride uptake was controlled solely by the surface area of the apatitic mineral and that the organic matrix did not contribute to the fluoride uptake.     

Fluoride uptake by enamel and dentin from bonding agents and composite resins: a comparative study

The present study was performed to compare the amount of in vitro fluoride uptake by enamel and dentin from fluoridated bonding agent with non-fluoridated composite (Group I), non-fluoridated bonding agent with fluoridated composite (Group II) and fluoridated bonding agent with fluoridated composite resin (Group III). Sixty extracted premolars were selected and divided into three groups of 20 teeth each. Restorative materials were applied according to manufacturer's instructions into standard windows created in the teeth, cured and placed in de-ionised water for three months. The fluoride content of successive acid etch biopsy was determined by specific ion-electrode analysis. Although significant amount of fluoride uptake occurred in all the test groups, fluoride uptake was found to be highly significant in dentin when compared to enamel in Group, I, II and III (P<0.001). The fluoride uptake was greater by both enamel and dentin in Group III ie fluoridated bonding agent with fluoridated composite resin.     

氟以及表面活性剂对牛牙釉质脱矿的影响

本研究旨在进一步了解氟化物以及表面活性剂（SAA）对牛牙釉质脱矿的影响。在体外模拟酸蚀模型，采用自制的钙离子选择性微电极测试不同处理组的钙离子浓度，并进行分析评价。结果显示：①牙釉质经氟化钠处理后其脱矿率明显低于单用酸蚀液组（P＜0．01）；②SAA和氟化钠合用与单用氟化钠组之间无显著差异（P＞0.05）。提示氟可通过增强牙齿组织的抗酸性，降低釉质表面的溶解度而抗龋；SAA的抗龋作用有待进一步研究。     

Fluoride uptake and retention at various stages of rat molar enamel development

Suckling rat pups were given intraperitoneal fluoride injections at selected ages so that we could study fluoride uptake in the enamel of the maxillary first molar at various stages of enamel development. Plasma fluoride levels in six-day-old and 11-day-old pups were monitored following the intraperitoneal injection of fluoride. The findings indicate that: (1) fluoride was more easily taken up and retained during the early stages of enamel formation, but fluoride uptake can occur during all stages of enamel formation; (2) when injections were started early in enamel formation, more fluoride was contained in the enamel of the maxillary first molar at 13 days of age; and (3) the same dose of fluoride per gram body weight resulted in greater exposure to elevated plasma fluoride levels in six-day-old pups than in 11-day-old pups.     

Effect of various aliphatic amines on the permeability of bovine dental enamel

Aliphatic amines with chain lengths from C2 to C18 were investigated for their effect on the diffusion of [3H]-sorbitol, [14C]-glycerol, 36Cl- and 86Rb+. Before amine application, enamel was pretreated with a phytate solution. C12-C18 amines reduced the rate of diffusion to values of about 20-30 per cent of the values found before treatment. Amines with chain lengths below C12 were less effective. The presence of an unsaturated carbon-carbon bond (C18:1) seems to promote the absorbance of the amine to enamel.     

In-vivo fluoride uptake by enamel of teeth of human adults from various topical fluoride procedures

Participants were 40 inmates of a Federal prison, ages 23–39, who required extraction of three or more pairs of homologous teeth. Subjects were randomly divided among four groups and each received half-mouth control and test procedures on randomly designated sides of the mouth. On the test side: Group 1 received a prophylaxis with an inert paste followed by an application of an acidulated phosphate-fluoride solution (1.23 per cent F); Group II, a prophylaxis with the inert paste followed by an application of a 10 per cent stannous fluoride solution (2.42 per cent F); Group III, a prophylaxis with an acidulated phosphate fluoride-silicon dioxide paste (1.2 per cent F); and Group IV, a prophylaxis with a 9 per cent stannous fluoride zirconium silicate paste (4.8 per cent F). Treatments were operator-applied according to recommended techniques. Control teeth were given the test procedure minus the active agent. Applications of fluoride were made after teeth on the control side had been treated and extracted. All teeth were extracted one week after treatment. Determination of fluoride concentrations was made blindly in 204 teeth selected for analysis. At a depth of 5 μ, a comparison of fluoride levels in homologous pairs of teeth (test minus control) showed an average net change per individual of +190 ppm in Group 1, +30 ppm in Group II, +91 ppm in Group III and −4 ppm in Group IV. Only the gains in fluoride uptake in Groups 1 and III were statistically significant. There was virtually no acquisition of fluoride by subsurface layers of enamel. These data suggest that the acidulated phosphate-fluoride solution and the prophylaxis paste may have potential for combating decay in the teeth of adults. Definitive evidence of effectiveness of the agents tested, however, must come from the results of clinical trials.     

Fluoride uptake from a composite restorative by enamel

The purpose of the study was to determine the in vitro uptake of fluoride by enamel adjacent to a fluoride-releasing composite restorative material containing 11.2 mg/g of fluoride. Blocks of human enamel were placed close to cured discs of the composite in synthetic saliva for periods of up to 24 hours. The fluoride content of successive acid-etch biopsy layers of the enamel blocks was determined by specific ion-electrode analysis, and atomic absorption analysis for calcium was used to determine the layer thickness. After 24 hours, a fluoride content of 5400 ppm was found for the outermost 10-micron layer of enamel. Based on the in vitro demonstration of appreciable fluoride uptake by adjacent enamel, the fluoride-releasing composite gives promise of having anticariogenic properties in vivo.