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Caries-preventive effect of fluoride varnish with different fluoride concentrations.

Based on the current concept of the caries-preventive mechanism of fluoride, the fluoride concentration of some professionally applied fluoride preparations appears unnecessarily high. The aim of this trial was to study whether reducing the fluoride concentration of the sodium fluoride varnish Duraphat from the present 2.3% to 1.1% affects its clinical efficacy. A total of 274 children aged 12-14 years and having high past caries experience were randomly divided into two groups. The participants received 3 annual applications of either 2.3% or 1.1% varnish for 3 years. Clinical and radiographical examinations were performed at baseline and at the end of the follow-up. The mean total DMFS increments of the 2.3% and 1.1% varnish groups were 5.5 (SD 5.7) and 5.7 (5.3), respectively, when initial caries was excluded, and 14.3 (12.0) and 14.9 (12.9) when initial caries was included. The differences were statistically non-significant. There were no significant differences in the surface-specific DMFS increments between the groups either. The 95% confidence interval for the difference between the groups in total mean DMFS increment (initial caries excluded) was calculated at -1.21 to + 1.54, i.e. at this level of confidence at most 0.5 surfaces per year would have been saved using the more concentrated varnish. Consequently, it can be stated at a reasonable level of certainty that if a difference in the efficacy of the two varnishes exists, it probably is minute. Lowering the fluoride concentration of Duraphat is worth considering at least when used for children.

Adolescent↗

Reversal of fluoride induced cell injury through elimination of fluoride and consumption of diet rich in essential nutrients and antioxidants.

The objective of the present communication is to address the issues concerning reversal of fluoride induced cell injury and disease (i.e. fluorosis) through the elimination of fluoride and consumption of a diet containing essential nutrients and antioxidants. Humans afflicted with fluorosis, as a result of consuming fluoride contaminated water or food, have been investigated. Hospital based diagnostic procedure for early detection of fluorosis, through retrieval of history, clinical complaints, testing of blood, urine and drinking water for fluoride using ion selective electrode technology, along with X-ray of the forearm have been carried out. Confirmed cases of fluorosis were introduced to an intervention protocol consisting of (1) provision of safe drinking water with fluoride levels less than 1 mg/L and (2) counselling on nutritional supplementation with focus on adequate intake of calcium, vitamins C, E and antioxidants. The patients were monitored at frequent intervals up to one year and the results are reported. With a standardized early diagnosis, elimination of fluoride intake and supplementation of a diet rich in essential nutrients and antioxidants, we have shown that the fluorosis can be reversed.

Adolescent↗

Effect of fluoridated dentifrice and acidulated phosphate fluoride application on early artificial carious lesions.

PURPOSE: To evaluate the effect of a combination of fluoride dentifrice and acidulated phosphate fluoride (APF) on enamel with incipient caries lesions. MATERIALS AND METHODS: Bovine dental enamel blocks with artificial caries lesions were divided into four treatment groups and submitted to a pH-cycling model: (1) Placebo non-fluoridated dentifrice (PD); (2) Fluoridated dentifrice (FD), 1,100 ppm F; (3) APF (12,300 ppm F, pH 3.5) + PD; 4) APF+FD. APF was applied to enamel blocks of groups APF+PD and APF+FD before the pH-cycling regimen and all of them were exposed to dentifrice during the cycling. RESULTS: The results showed that 61-81% of the fluoride previously deposited in enamel by APF was released to the media during the pH-cycling. The final concentration of fluoride in enamel in the group APF+PD was lower than that before the cycling (P < 0.05), but in the group APF+FD the reduction was not significant (P> 0.05). FD treatment was significantly more efficient than PD in rehardening the enamel surface and increasing the hardness of the caries lesions. APF+PD treatment was not more efficient than PD in increasing enamel hardness and an additive effect of APF+FD was not observed.

Acidulated Phosphate Fluoride↗

[An investigation of fluoride pollution caused by burning coal containing fluoride in Xiushan and Baojing].

This paper reports an investigation of contents of soluble fluoride in the environment and foods in Xiushan and Baojing. On the basis of measuring concentrations of soluble fluoride in drinking water, soil, coal, air, fly ash, maize, chilli, and other kinds of vegetables, it is first to expand the pathway of fluoride migrating from coal into human body is through pollution of air by fluoride contained in fly ash on burning of coal, and then via consumption of polluted maize by air. The significant correlation between both the concentrations of fluoride in maize and in fly ash is proved. It is suggested to select the concentration of fluoride in fly ash or in air as the quality index of indoor air and the control target to prevent fluorosis.

Air Pollutants↗

The prevalence of fluorosis-like lesions associated with topical and systemic fluoride usage in an area of optimal water fluoridation.

The frequency of using self-applied (over-the-counter) fluoride products and prescribed supplemental fluorides, and the prevalence of fluorosis-like enamel lesions in the permanent dentitions of children living in an optimally fluoridated urban community were investigated. Subjects were selected randomly, and consent forms and questionnaires concerning fluoride usage and residency status were provided to guardians prior to examination. After a supervised tooth brushing event, 300 consenting subjects were examined by the principal investigator using Dean's index to assess levels of fluorosis-like lesions. The principal investigator was standardized with another investigator prior to the examinations to obtain an interexaminer agreement level of 97%, and an intraexaminer agreement level of 96%. Portable dental equipment was used during all examinations. Chi-square analysis indicated no statistically significant difference between the frequency of tooth brushing with a fluoridated dentifrice at an early age and the prevalence of fluorosis-like enamel lesions. However, there was a significant difference (P less than 0.05) between the prevalence of fluorosis-like lesions, and the frequency of using prescribed fluoride supplements and gels, and over-the-counter rinses.

Adolescent↗

Placental transfer of fluoride in pregnant women consuming optimum fluoride in drinking water.

The study was conducted on 25 healthy women residing in optimum fluoride areas, who were to deliver normally through vaginal route, to correlate the maternal and cord plasma fluoride levels and evaluate the placental transfer of fluoride. A wide variation was found in the maternal and cord plasma fluoride levels. In only 8 percent of the cases the fluoride levels in cord plasma were higher than maternal plasma. It was deduced that the placenta allows passive diffusion of fluoride from mother to foetus and does not act as a barrier.

Female↗

Fluoride uptake in plaque-covered enamel after treatment with the fluoride lacquer Duraphat.

The amount of alkali-soluble and alkali-insoluble fluoride was determined in human enamel after one- and six-hour treatments with Duraphat. The application was carried out on: (1) slightly demineralized enamel covered with artificial plaque, (2) cleaned, slightly demineralized enamel, and (3) sound enamel without pre-treatment. After a single Duraphat treatment lasting six hours, fluoride uptake was higher than after Duraphat treatment for just one hour in all experimental groups. More fluoride was acquired in both slightly demineralized, plaque-covered and slightly demineralized, cleaned enamel than in sound enamel. Plaque significantly hampered the formation of alkali-soluble fluoride precipitation on demineralized enamel, but its influence on the amount of fluoride taken up by the enamel was minor.

Calcium Fluoride↗

Fluoride uptake by enamel in vitro following application of various topical fluoride preparations.

Two conventional topical fluoride preparations; APF and neutral 2% NaF gel and two fluoride varnishes; Duraphat and Fluor Protector, were applied to 60 permanent and 20 primary teeth. The teeth were halved to provide test and control groups, and the fluoride uptake was measured using a micro acid etch technique, after 30 seconds and 60 seconds etching periods. All topical fluoride preparations in our study caused some fluoride uptake in permanent and primary tooth enamel compared to the control groups. Duraphat and APF were found to be more effective than the other agents.

Acidulated Phosphate Fluoride↗

Novel fluorogenic probe for fluoride ion based on the fluoride-induced cleavage of tert-butyldimethylsilyl ether.

A highly sensitive and selective fluorogenic probe for fluoride ion, 4-methylumbelliferyl tert-butyldimethylsilyl ether (4-MUTBS), was designed and synthesized. 4-MUTBS was a weakly fluorescent compound and was synthesized via the one-step reaction of 4-MU with tert-butyldimethylsilyl chloride. Upon incubation with fluoride ion in acetone-water solution (7:3, v/v), the Si-O bond of 4-MUTBS was cleaved and highly fluorescent 4-methylumbelliferone (4-MU) was released, hence leading to the fluorescence increase of the reaction solution. The fluorescence increase is linearly with fluoride concentration in the range 50-8000 nmol l(-1) with a detection limit of 19 nmol l(-1) (3sigma). Because of the high affinity of silicon toward fluoride ion, the proposed probe shows excellent selectivity toward fluoride ion over other anions. The method has been successfully applied to the fluoride determination in toothpaste and tap water samples.

Fluorescent Dyes↗

Fluoridated apatite synthesized using a multi-step fluoride supply system.

Fluoridated apatite was synthesized at 80 +/- 1 degrees C, pH 7.4 +/- 0.2, using a 5-step fluoride supply system. During the synthesis experiment, 0, 5, 10, 15 and 20 mmol/l of fluoride were each supplied for one-fifth of the experimental period with calcium and phosphate. X-ray diffraction analysis showed a typically apatitic pattern, although the (3 0 0) reflection was broader than that of homogeneous fluorapatite. Scanning electron micrographic observation indicated that the apatite was composed of needle-like crystals similar to hydroxyapatite and fluorapatite. High-resolution transmission electron microscopy showed a slender hexagonal shape similar to homogeneous hydroxyapatite in cross-sections perpendicular to the c-axis and the structural damage in the core of the crystal, although no boundary of step-like layers was observed. The apparent solubility in 0.5 mol/l acetate buffer solution (37 degrees C and pH 4.0) was 12.1 +/- 0.2 mmol/l, much less than that of homogeneous hydroxyapatite 32.3 +/- 1.9 mmol/l, and similar to that of heterogeneous two-layer fluoridated apatite with an outer fluoride-rich layer 12.5 +/- 0.6 mmol/l, which was synthesized previously by supplying fluoride during the latter half of the experimental period.

Apatites↗

Dental preservation in patients irradiated for head and neck tumours: A 10-year experience with topical fluoride and a randomized trial between two fluoridation methods.

Since 1972, the dentures of 935 patients irradiated for head and neck carcinoma have been preserved after careful selection and according to well-defined criteria, using a prospective programme of daily applications of topical sodium fluoride gel. The results of 1-10 years follow-up are given. Four percent of the patients developed a diffuse dental decay and 1% a bone necrosis which can be related to the dental preservation. None of these complications occurred with careful patient selections nor when programme compliance was maintained. Post-irradiation dental extractions were performed in 29 cases with subsequent healing in all cases but one. The surgical technique of such extractions is described. In March 1980, a randomized protocol was activated to compare the use of the sodium fluoride gel to high content fluoride toothpaste (1350 ppm F-). Two hundred and twenty patients were entered. At 12-36 months follow-up, dental caries were observed in 3% of the patients receiving the fluoride gel as compared to 11% receiving the toothpaste (p = 0.1). However, none of the patients adhering to the programme instructions failed in either arm. Currently, it seems reasonable to state that preservation of teeth in irradiated patients should be the rule and not the exception, given good dental condition prior to treatment and patient cooperation. The 5 min daily application of fluoride gel is the most reliable method for prevention of post-irradiation dental caries. The twice daily use of high content fluoride toothpaste is a good alternative provided its limitations are well understood by the clinician and patient.

Administration, Topical↗

Risk of enamel fluorosis associated with fluoride supplementation, infant formula, and fluoride dentifrice use.

Eight hundred fifty 11- to 14-year-old residents of nonfluoridated communities in Massachusetts and Connecticut, who were born between 1972 and 1975, were investigated in a case-control study of the possible association between enamel fluorosis and exposure to fluoride supplements, infant formula, and/or fluoride dentifrice. The effect of median household income, an indicator of socioeconomic status, was also examined. Clinical examination, using the Fluorosis Risk Index, a fluorosis index developed for this project, allowed cases and controls to be identified based upon the specific time period of exposure to the various sources of ingested fluoride. Risk factor exposure was assessed via a mailed questionnaire with a response rate of 80%. Mild-to-moderate enamel fluorosis was strongly associated with fluoride supplementation during the first six years of life (odds ratio = 4.0) and with median household income (odds ratio = 6.6). Subjects in the middle median household income group who had used fluoride supplements through the first six years of life had a 28-fold increase in the risk of fluorosis compared with unexposed subjects in the lower median household income group. An odds ratio of 1.7 associated with infant formula use was suggestive of an increased risk of enamel fluorosis as was an odds ratio of 2.9 associated with fluoride dentifrice use.

Adolescent↗

Fluoride, fluoride resistance and glycolysis in cultured cells.

Long-term (several years) exposure to fluoride induced decreased production of lactate in cultured, fluoride resistant LS cells. In intact, sensitive cells, 6 mM NaF had no effect on glycolysis, whereas in homogenates, from both resistant and sensitive cells, lactate production was blocked by 6 mM NaF, indicating the cell membrane to be a barrier to fluoride. A lower intracellular rather than extracellular fluoride concentration was found in the sensitive cell with a ratio of 0.4, whereas fluoride resistant cells excluded fluoride from their intracellular milieu.

Animals↗

Enolases from fluoride-sensitive and fluoride-resistant streptococci.

The enolase from a highly fluoride-sensitive strain of Streptococcus salivarius and its fluoride-resistant mutant, as well as those from strains of Streptococcus sanguis and Streptococcus mutans with intermediate and low sensitivities to fluoride have been shown to be inhibited by fluoride. Comparisons of the purified, strain-specific enzymes showed a high degree of similarity for all preparations. The Michaelis constants for the substrate 2-phosphoglycerate were 1.3 x 10(-4) to 2.4 x 10(-4) M, pH optima were 7.3 to 7.7, and Mg2+ optima were 2 mEq/liter for all. Inhibition by fluoride required the presence of inorganic phosphate and was competitive in nature, and the calculated modified inhibition indices were found to be in the range from 3.3 x 10(-14) to 5.8 x 10(-14) M4. Percent inhibitions were determined under standardized conditions (0.16 mM NaF, 2 mM MgSO4, 0.5 mM Pi, and 0.5 mM 2-phosphoglycerate) and were found to range from 53.3 to 65.9% for all of the purified enzymes. The differences do not appear to be meaningful metabolically. Inhibition was reduced to about 14% at pH 6.0. From the similarities in the behavior of the strain-specific enzymes it is concluded that the differences in the glycolytic sensitivities of the different strains of streptococci to fluoride are not the consequence of any kinetic differences between the respective enolases.

Drug Resistance, Microbial↗

Systematic review of studies comparing the anti-caries efficacy of children's toothpaste containing 600 ppm of fluoride or less with high fluoride toothpastes of 1,000 ppm or above.

OBJECTIVE: To determine the clinical effectiveness of low fluoride (F) toothpastes, containing 600 ppm or less, with toothpaste containing 1,000 ppm or more fluoride in preventing dental caries. DESIGN: Systematic review of randomised controlled trials comparing low fluoride toothpastes containing 600 ppm F or less with toothpastes containing 1,000 ppm or more in children or adults. RESULTS: Seven randomised controlled trials were included. These were categorised into two groups depending on the fluoride concentration in the low fluoride group (250 and 500 ppm) and analysed separately. 250 PPM: Results of the meta-analysis were statistically significant (p = 0.002 and 0.0005) and in favour of the control group (1,000 ppm). DFS increments in the 250-ppm group were 0.6-0.7 greater than the 1,000-ppm group. 500 PPM: Only two studies were in this category, and one of them failed to present the baseline caries levels, so a meta-analysis was not carried out. CONCLUSION: 250 ppm fluoride dentifrice was not as effective in caries prevention in permanent dentition as dentifrice containing 1,000 ppm F or more. More studies have to be carried out to test the anticaries efficacy of 500 against 1,000 ppm and above.

Adolescent↗

Studies on fluoride excretion in human whole saliva and its relation to flow rate and plasma fluoride levels.

Five volunteers participated in two separate experiments where whole saliva was collected without stimulation or with stimulation by chewing on paraffin wax. The saliva was collected continuously for 120 min after ingestion of 1 mg fluoride as NaF. Blood was collected at intervals throughout the experiments. The results showed that the concentration of fluoride in whole saliva mirrored the fluoride concentration in plasma, but at a lower level. Variations in salivary flow rate (0.34 +/- 0.15 ml/min for unstimulated and 1.06 +/- 0.28 ml/min for stimulated) did not affect the salivary fluoride concentration. The amount of fluoride excreted into stimulated whole saliva was significantly correlated with the salivary flow rate, with a correlation coefficient of 0.98. The fraction of the ingested fluoride dose recovered in whole saliva within 2 h was 0.05 +/- 0.02 and 0.18 +/- 0.09% for the unstimulated and the stimulated whole saliva, respectively.

Administration, Oral↗

Enamel defects in 8-year-old children in fluoridated and non-fluoridated parts of Cheshire.

The aim of this study was to compare the prevalence of developmental defects of enamel in fluoridated (1 ppm F) and non-fluoridated (less than 0.2 ppm F) communities in Cheshire, England. Eight-year-old children were examined under blind conditions. Only lifetime residents were included and only children with no history of dietary fluoride supplements. Significantly more children living in the fluoridated community (60%) had enamel defects compared to those in the non-fluoridated community (44%). In the fluoridated community, significantly more children whose parents claimed to begin brushing at an early age exhibited enamel defects.

Child↗

Enamel fluoride concentrations in unerupted third molars and the influence of fluoridated water on caries scores.

Enamel fluoride concentrations in buccal and lingual surfaces were determined in successive layers obtained by the acid etch method. The 48 unerupted third molar teeth were from subjects who had lived continuously since birth in two Brazilian towns (Barretos and Ribeirão Pr-eto) with different fluoride levels in the drinking water but with similar socioeconomic conditions. The DMFT index was determined for children 7-12 years old living in the two towns. Enamel fluoride concentrations were significantly higher in the teeth from the town with higher fluoride levels in drinking water. The children residing in the community with near-optimum fluoride concentration in the water had mean DMFT scores that were less than half those found in the community with a low level of fluoride in the drinking water.

Acid Etching, Dental↗