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[The caries-protective efficacy of 2 fluoride varnishes in a 2-year controlled clinical trial].

The aim of this randomized, double-blind study was to measure the cariostatic effect of Bifluorid 12 (VOCO GmbH), containing 6% sodium fluoride and 6% calcium fluoride and Laweflour-Schüttellack (LAW), containing 5% sodium fluoride in comparing of placebo varnish. The caries study included 400 schoolchildren, aged 12-14 years. The tests according to the DMFS were carried out by two independent examiners. The 400 children were divided into 3 test and 1 placebo group, each group consisting of 100 subjects. After two years there was a significant inhibition of caries increment in all test groups compared to placebo group. Percentage caries reduction ranged from 25 to 30%. The highest effect was stated at proximal surfaces.

Adolescent↗

Deposition of alkali-soluble fluoride on enamel surface with or without pellicle.

Deposition of alkali-soluble fluoride on enamel in the presence and absence of an acquired pellicle was studied in vitro during a single topical application of a 2% sodium fluoride solution at neutral pH. Five experimental groups of repeated measures design were established. The amount of alkali-soluble fluoride formed on enamel (i.e., calcium fluoride) was measured by chemical assessments and by SEM. The results showed that there were no differences among the groups demonstrating the incapacity of pellicle to interfere with deposition of alkali-soluble fluoride on enamel. The fluoride ions are thus able to reach the enamel in spite of the presence of the pellicle.

Alkalies↗

Formation of CaF2 on sound enamel and in caries-like enamel lesions after different forms of fluoride applications in vitro.

The formation of calcium fluoride (CaF2) was measured on sound enamel (SE) and in caries-like enamel lesions (CL) after treatment in vitro with 2% neutral NaF or Duraphat. The caries-like lesions were created by exposure to acidified gel at pH 4.5 within a 0.07-cm2 window punched in water-repellant tape. The same window area was used in series (n = 10) of SE or CL during the application of NaF for 1 or 5 min or for 18 h or Duraphat for 6 or 18 h. CaF2 was extracted with 1 M KOH for 24 h, and fluoride was determined by gas chromatography. The short-term applications of NaF produced only negligible amounts of CaF2 on SE. The amounts of CaF2 in CL after 5 min application of NaF corresponded to (mean +/- SEM) 27 +/- 2.0 micrograms F/cm2. More than half of this amount was observed after only 1 min exposure to the NaF solution. The quantities of CaF2 in CL were similar after 6 and 18 h application of Duraphat, amounting to 26 +/- 2.2 and 31 +/- 2.2 micrograms F/cm2, respectively, suggesting that the reaction was essentially terminated after 6 h. These amounts were only about one fourth of the quantity obtained after 18 h exposure to the NaF solution. Thus, the conventional 5-min treatment with NaF produced the same amount of CaF2 in CL as 6 or 18 h exposure to Duraphat.

Calcium Fluoride↗

Effects of plasma fluoride and dietary calcium concentrations on GI absorption and secretion of fluoride in the rat.

This 30-day balance study with weanling rats was designed to determine the effects of plasma fluoride and dietary calcium concentration and their interaction on the absorption, balance, and tissue concentrations of fluoride. The three major groups differed according to the total exposure and plasma concentrations of fluoride. One group received fluoride only in the diet and the other two received additional fluoride by continuous infusion from miniosmotic pumps implanted S.C. Each group was divided into two subgroups with dietary calcium concentrations of 0.4% or 1.4%. Fluoride intake with the diet did not differ among the groups. Fecal fluoride excretion was directly related to plasma fluoride concentration. The absorption and balance of dietary fluoride were inversely related to plasma fluoride concentration. These effects were greatest in the groups fed the 1.4% calcium diet. The interactions of plasma fluoride and dietary calcium on these variables were highly significant (P < 0.0001). The balance of dietary fluoride was negative in the four groups that received additional fluoride by infusion. In the two groups that received fluoride only in the diet, the plasma and bone fluoride concentrations were 41% and 59% lower, respectively, in the 1.4% dietary calcium group. The findings indicate that net fluoride secretion into the GI tract can occur when plasma fluoride concentrations and calcium intake are elevated. They suggest that elevated plasma fluoride levels and calcium intake are factors that may diminish the effect of oral fluoride treatment in osteoporotic patients.

Animals↗

[Factors that modify de- and remineralization in dental enamel from the aspect of caries susceptibility].

The course of caries depends on an equilibrium between de- and remineralization of enamel. Epidemiologic studies performed during recent years in Poland have demonstrated a high incidence and severity of caries in children and teenagers. Therefore, the actual program of caries prevention covering the whole population of children and teenagers has not performed to the expectations, possibly because the program protocol does not discriminate between children susceptible and resistant to caries. The aims of this work included: 1. Analysis of tooth groups and surfaces as to their susceptibility to caries; 2. Evaluation of the influence of de- and remineralization modifying factors such as: a) dental plaque and sugars, b) caries-causing bacteria, c) enamel resistance to acids, d) biochemical properties of saliva--on the susceptibility to caries; 3. Evaluation of the uptake of fluorides from chewing gum by enamel in relationship to caries susceptibility. An initial clinical examination of permanent teeth was performed in 292 children aged 12 years. Subsequently, two groups were formed: one with 45 children free from caries and another with 77 children at high risk of caries. Control examinations of permanent teeth in both groups were carried out after one and three years from the initial examination. The clinical examination included a check-up of secondary dentition, counting of erupted teeth, sealed teeth, evaluation of oral hygiene status, gingivae, abnormalities in mineralization and measurement of the rate of microdemineralization. The biochemical analysis of saliva was done to measure the content of fluorides, calcium, phosphorus and magnesium, as well as pH. Microsamples of enamel were collected using acid biopsy and the content of calcium and fluorine in the superficial and underlying layer was assayed. The thickness of both layers obtained by biopsy was also measured. Commercial test kits--Dentocult SM and Dentocult LB, served to determine the amount of caries-causing bacteria in saliva. Additionally, the children and their mothers responded to a questionnaire on the diet, previous diseases, therapies with antibiotics and health habits. The results were analysed using Statgraphics software. Differences between means were checked using Student t-test in its classical form or as modified by B. L. Welch. Linear correlation indices were calculated and Spearman rank correlation test was performed. On the basis of the results obtained the following conclusions were drawn: 1. 12-year old children at high risk of caries need intense dental care due to: a) extensive involvement of masticatory surfaces of molar teeth and contact surfaces of premolar teeth, b) treatment inappropriate to actual needs in this group of children. 2. Effective programs to improve the knowledge and health of children at high risk to caries should be introduced due to the following facts: a) oral hygiene was unsatisfactory in the examined children, b) children consumed large quantities of sweets. 3. Disturbances in the mineralization of enamel and the use of antibiotics in childhood were without influence on the susceptibility of teeth to caries. 4. The content of fluorides, calcium and phosphorus in the saliva of children susceptible to caries could have been below the level necessary to maintain an equilibrium between de- and remineralization of enamel. 5. Susceptibility of teeth to caries could be due to differences in the chemical composition and structure of enamel, as it appears from the content of fluorides and calcium, depth of enamel biopsy and uptake of fluorides from chewing gum. 6. Chewing of fluoride-containing gums is a supportive measure in caries prevention, particularly recommended in children at high risk of caries. 7. Caries prevention should be individualized and matched to caries risk.

Academic Dissertations as Topic↗

[Fluoride bioavailability from sodium fluoride alone or in association with different calcium salts].

Fluoride pharmacokinetics were studied in twelve healthy subjects after oral administration of one tablet of osteofluor-containing 25 mg of sodium fluoride alone or associated with different calcium salts (500 mg Ca element) given as microcrystalline hydroxyapatite compound or powdered tri-calcium phosphate. Fluoride was measured in plasma and urine with a specific electrode and fluoride bioavailability from the three drugs was compared. Calcium absorption after oral load was assessed by measuring variations from the fasting state of plasma calcium and parathyroid hormone and of the urinary calcium to creatinine ratio. The bioavailability of fluoride is significantly decreased by the association to sodium fluoride of hydroxyapatite but not of tri-calcium phosphate. Calcium absorption seems greater after administration of hydroxyapatite compound. The decrease of the fluoride bioavailability is probably dependent on the capacity of calcium absorption from the calcium salts. The association of calcium to fluoride is absolutely required for treatment of osteoporosis. The microcrystalline hydroxyapatite compound seems preferable in view of its greater calcium absorption and of its limited decrease in fluoride bioavailability.

Administration, Oral↗

Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel.

Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.

Dental Enamel↗

Fluoride in workplace air and in urine of workers concentrating fluorspar.

The urinary fluoride concentrations of workers exposed to calcium fluoride (CaF2) during fluorspar processing were measured. Personal dust measurement showed that the mean occupational exposure to fluoride for 12 workers in the most dusty environment was 24.3 mg/m3, which is 9.7 times the threshold limit value (TLV) of 2.5 mg/m3. Exposure was below the TLV for the remaining 23 workers. Urinary fluoride concentrations were measured pre- and postshift. The heavily exposed workers had a mean preshift concentration of 3.3 mg/liter (range 1.4-8.5 mg/liter), only slightly higher than the mean of 2.8 mg/liter (range 1.3-4.2 mg/liter) in the workers with fluoride exposure below the TLV. Four of the preshift concentrations exceeded the recommended upper limit of 4 mg/liter. The mean postshift concentration for workers exposed above the TLV was 4.4 mg/liter (range 2.4-7.1 mg/liter) and the difference between pre- and postshift concentrations was significant (p less than 0.05). Only one urinary concentration exceeded the recommended upper limit of 7 mg/liter. There was poor correlation between intensity of environmental exposure to fluorspar and postshift fluoride concentration in the urine. Eighteen workers provided a urine sample 7-14 hr after the end of a shift. The mean fluoride concentration was 4.7 mg/liter (range 2.4-11.7 mg/liter), which exceeded their postshift concentration by 0.2 mg/liter. These results indicate that the low aqueous solubility of fluorspar reduced the biologic availability of the fluoride ion but that this did not prevent excessive fluoride absorption in some workers.

Air Pollutants, Occupational↗

Calcium deficiency in fluoride-treated osteoporotic patients despite calcium supplementation.

To test the hypothesis that the osteogenic response to fluoride can increase the skeletal requirement for calcium, resulting in a general state of calcium deficiency and secondary hyperparathyroidism, we assessed calcium deficiency, spinal bone density, by quantitative computed tomography, and serum PTH in three groups of osteoporotic subjects. Two of the three groups had been treated with fluoride and calcium (at least 1500 mg/day) for 32 +/- 19 months. Group 1 consisted of 16 fluoride-treated subjects who had shown rapid increases in spinal bone density (+ 3.8 +/- 2.6 mg/cm2 month), group II consisted of 10 fluoride-treated subjects who had shown decreases or only slow increases in spinal bone density (-0.05 +/- 0.6 mg/cm3 month), and group III consisted of 10 age-matched untreated osteoporotic controls. Calcium deficiency was assessed by measurement of calcium retention after calcium infusion. The results of our studies showed that 1) 94% of the subjects in Group I were calcium deficient compared with only 30% in groups II and III (P < 0.01 for each); 2) the subjects in group I retained more calcium (79%) than the subjects in group II (60%, P < 0.001) or the subjects in group III (64%, P < 0.005); 3) calcium retention was proportional to serum PTH (r = 0.37, n = 36, P < 0.03); and 4) calcium retention was proportional to the (previous) fluoride-dependent increase in quantitative computed tomography spinal bone density (in groups I and II, r = 0.48, n = 26, P < 0.02). To test the hypothesis that the calcium deficiency and the secondary hyperparathyroidism that were associated with the positive response to fluoride would respond to concomitant calcitriol treatment, a subgroup of 7 calcium-deficient subjects were selected from group I and treated with calcitriol (plus fluoride and calcium) for an average of 7 months. The calcitriol therapy reduced the calcium deficit in all 7 subjects, decreasing calcium retention from 80% to 62% (P < 0.02), and decreasing PTH from 50 to 28 pg/mL (P < 0.02). Together, these data indicate that fluoride-treated osteoporotic subjects may develop calcium deficiency in proportion to the effect of fluoride to increase bone formation, and this calcium deficit is responsive to calcitriol therapy.

Aged↗