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PubMed1982

The remineralization of fluoride-treated bovine enamel surfaces.

Various etching methods are examined with respect to their ability to induce the surface nucleation and growth of fluorapatite from solutions of low, sustained supersaturation with respect to hydroxyapatite and fluorapatite. The constant composition kinetics method enables the rates of remineralization to be precisely determined, and the possibility of the direct growth of fluorapatite on calcium fluoride crystals in calcium phosphate solutions of low supersaturation has also been examined.

Acid Etching, Dental↗
PubMed1984

Transitions in Dictyostelium discoideum behaviour: influence of calcium and fluoride on slug phototaxis and thermotaxis.

Phototaxis and thermotaxis by slugs of Dictyostelium discoideum show transitions that result in bimodality in phototaxis and temperature-dependent orientation up or down temperature gradients. New steps in the sensory transduction chain for these kinds of behaviour are elucidated from studies using inorganic salts (Ca2+, EGTA, KF) and several mutants. KF enhances bimodality of phototaxis, improves the accuracy of thermotaxis, and affects the transition temperatures from positive to negative thermotaxis. Changing the Ca2+ concentration has effects on both phototaxis and thermotaxis. At low Ca2+ concentrations phototaxis and thermotaxis are enhanced. In the presence of EGTA or high concentrations of Ca2+ phototaxis becomes bimodal, thermotaxis is impaired and spontaneous turning is suppressed. These results obtained by changing Ca2+ concentrations are analogous to those obtained previously with sensory transduction mutations, which coordinately affect phototaxis and thermotaxis.

Agar↗
PubMed1997

Release of cariostatic agents from a new buffering fluoride- and xylitol-containing lozenge to human whole saliva in vivo.

A new buffering lozenge (sucking tablet) was developed for patients susceptible to dental caries and erosion, in particular for those with reduced salivary secretion. As active ingredients this lozenge comprises of a combination of xylitol, fluoride, calcium, phosphate, zinc and buffering compounds. To test the lozenge's activity in vivo, the release of ingredients was monitored in 19 healthy subjects for 22 min after sucking the lozenge was completed. In subjects with a normal salivary secretion rate the lozenge caused only a slight stimulation of saliva flow, but a significant elevation both in salivary pH and buffer effect was observed. Furthermore, fluoride, calcium and phosphate were effectively released into whole saliva with peak values 2-4 min after use. The same salivary parameters were also quantitated after 1 month's regular use (3 lozenges/day) but no consistent long-term changes were found. Salivary mutans streptococci and total anaerobic microflora did not change significantly during the long-term use. The results show that the buffering fluoride- and xylitol-containing lozenge, which also releases calcium and phosphate, is active in vivo but its serviceability as a remineralizing agent, in particular for elderly patients with reduced salivary flow rate, has to be analysed separately.

Administration, Oral↗
PubMedDate not supplied

In vitro study of remineralization of dentin: effects of ions on mineral induction by decalcified dentin matrix.

We examined the effects of various ions on the mineralization of dentin matrix in vitro. Demineralized dentin matrix was incubated in a metastable calcium phosphate solution with or without silicate, fluoride, calcium, phosphate, magnesium or silver. Insoluble dentin matrix induced mineral formation after incubation for 10.2 h in the metastable solution without added ions. Silicate at 5 microM and fluoride at 40 microM significantly reduced the mineral induction time. At least 200 microM calcium or 100 microM phosphate was required to promote mineral induction. Conversely, magnesium and silver concentrations as low as 10 and 2 microM inhibited mineral induction. The mineral induced by each sample after incubation for 24 h was identified by its X-ray diffraction pattern as apatite. We concluded that silicate is a stronger inducer of remineralization of dentin matrix than fluoride, calcium or phosphate, and that magnesium and silver inhibit the induction of remineralization of dentin matrix.

Animals↗
PubMed1980

Contribution to the physicochemical rationale for the caries reducing effect of fluoride.

The effect of fluoride on the stability of apatites containing Na+ and CO3(2)- ions is described qualitatively. Also the boundaries of the apatite stability field in the quasi-septary system CaO - P2O5 - H2O - Na2O - CO2 - NaF - MX are presented. At these boundaries brushite (or monetite), octocalciumphosphate, calcite and calcium fluoride can become stable solid phases. As a consequence, certain mechanisms for the caries reducing effect of fluoride gain probability over other proposed mechanisms. First, it is likely that endemic fluoride yields more fully mineralized enamel which in turn results in a lower initial rate of the caries process. Second, after eruption the mineral in the tooth superficial layer is bound to accumulate fluoride on the surface of its crystals. This causes a slower rate of the crystal surface dissolution at that site and, hence, a thicker and denser intact superficial layer over the lesion. Finally, the formation of a precipitate of fluorhydroxyapatite and perhaps also of calcium fluoride is promoted in the plaque during cycles of metabolic activity. Subsequent dissolution of the CaF2 and transformation of the fluorhydroxyapatite sets free Ca+ and F- ions. Both of these ions promote the remineralization of the lesion during periods of metabolic rest whereby brushite or monetite are transformed back into apatite.

Apatites↗
PubMed1999

Treating hypersensitivity with fluoride varnish.

Dentinal hypersensitivity results when stimulation causes the fluid in open dentinal tubules to undergo pressure changes, which activates mechanoreceptor nerves and results in pain. Treatment with fluoride varnish forms a protective layer of calcium fluoride that prevents this fluid flow, thereby reducing dentinal sensitivity.

Calcium Fluoride↗
PubMed1999

Cariostatic effect of a two-part fluoride dentifrice in rats.

This study compared the cariostatic effect of a two-part, fluoride-calcium-phosphate-containing prototype dentifrice (containing 1100 ppm F) to a conventional, clinically proven effective "gold standard" (1100 ppm F, USP Standard) and an Enamelon placebo dentifrice (0 ppm F) using a rat model. Three groups of 18 Crl:CDR(SD)BR rats were inoculated with S. sobrinus 27352 and fed MIT-200 for 35 days in a programmed feeder. Double-deionized water (DDW) was given ad libitum. The rats were treated twice daily with one two-part dentifrice. Just prior to treatment, each of the two parts of dentifrice were mixed 1:1 and applied undiluted. The rats were euthanized and their mandibular molars scored for caries using the Keyes quantification method. Shrestha SNP caries scores were then calculated. Non-parametric comparisons were done among treatments at the 0.05 level of significance using analyses based on ranks. The mean Shrestha SNP Caries Scores +/- standard deviations for the prototype dentifrice, USP standard and Enamelon placebo were 84.9 +/- 62.8, 101.3 +/- 66.3, and 181.2 +/- 100.1, respectively. Scores for the 1100 ppm F prototype treatment were significantly lower than the USP Standard and the Enamelon placebo. These results indicate that the new prototype dentifrice, containing fluoride-calcium-phosphate, increased the anti-caries efficacy in a rat model when compared with a fluoride-containing USP Standard dentifrice.

Administration, Topical↗
PubMed1984

The effect of diet calcium on fluoride toxicity in growing rats.

The effect of dietary Ca in response to fluoride (F) treatment was investigated in rats. Rats were maintained on either adequate (0.5%) or high (2.0%) dietary Ca and given for 5 weeks, NaF in drinking water. The minimum NaF levels that inhibited body growth and reduced survival were 300 mg/L with 0.5% diet Ca and 550 mg/L with 2.0% diet Ca. With these toxic F doses, bone histology showed increased formation surfaces and thickened osteoid seams (osteoid index 6-7%). Fluoride doses 30% below toxic levels (200 and 350 mg/L for 0.5 and 2.0% diet Ca, respectively) had no demonstrable effect on bone. Additional diet Ca reduced F absorption from 76 +/- 3 to 47 +/- 3% for 0.5 and 2.0% diet Ca, respectively. Comparable absorbed doses of F produced comparable effects on bone and body growth but, with additional dietary Ca, these effects were observed with 50% lower serum and bone F levels. Variable response to NaF therapy can be produced in rats by alterations in dietary Ca alone. Results indicate that for clinical treatment the NaF dose needs to be adjusted on an individual basis but neither serum nor bone F levels can be used reliably to establish optimal doses.

Animals↗
PubMed1986

Histomorphometric analysis of a calcaneal stress fracture: a possible complication of fluoride therapy for osteoporosis.

Pain and swelling of the large joints of the lower limbs occur in about 33% of patients receiving sodium fluoride, calcium, and vitamin D therapy. In a previous study we described radiographic and scintigraphic features suggesting that these symptoms are due to juxtaarticular stress fractures. We now report the histologic features of one such lesion in a calcaneum of a patient receiving fluoride, calcium, and 1 alpha-vitamin D therapy for postmenopausal osteoporosis. Bone biopsy after tetracycline double labeling showed a trabecular fissure fracture and large intratrabecular resorption cavities surrounded by microcallus. Comparison of the static and dynamic histomorphometric parameters in the calcaneum with those in the simultaneously taken iliac bone biopsy showed a marked regional acceleratory phenomenon in the calcaneum that we ascribe to the microfractures. It cannot be said with certainty whether the microfractures resulted from the osteoporosis, the vitamin D, or the sodium fluoride therapy.

Bone Resorption↗
PubMed1988

Effect of fluoride addition on ionized calcium in salivary sediment and in saliva.

Fluoride was added in increments to pooled whole saliva. The ionized calcium concentration was determined in the saliva and the salivary sediment after centrifugation. The maxima of the ion product with respect to calcium fluoride were for salivary sediment and saliva found at 15 mmol/l and 25 mmol/l of fluoride, respectively. The study indicated that calcium fluoride may precipitate in the plaque matrix during and after topical application of fluoride.

Calcium↗
PubMed1980

[Release of fluoride by fluoridated amalgams and its incorporation by dental enamel].

Liberation of stannous fluoride incorporated in the alloy powder before amalgamation was demonstrated for all the amalgams tested in this study. This liberation was observed for stannous fluoride concentrations of 0.5% and 1%. Clear differences were noted in relation to the type of amalgam studied. Through the use of a non destructive method (activation with charged particles) it was possible to measure the fluoride concentration in enamel before and after the contact with the fluoridated amalgam. This analysis demonstrated that the fluoride liberated from the amalgam was trapped by enamel in contact with alloys containing 0.5% or 1% of stannous fluoride. The enrichment in fluoride was very important in the first weeks and remained high after four months. No significant difference appeared between alloys fluoridated at 0.5% and 1%. The dissolution of calcium fluoride through a KOH treatment showed that the amount of stable fluoride (fluorapatite) formed was important.

Calcium Fluoride↗
PubMed1998

Na+/H+ exchange in vascular smooth muscle cells is controlled by GTP-binding proteins.

This study examines the involvement of GTP-binding proteins (Gps) in the regulation of Na+/H+ exchange and Ca2+ influx, which are increased in vascular smooth muscle cells from spontaneously hypertensive rats. Gp activity was modulated by fluoride, GTPgammaS, GDPbetaS, and antisense oligodeoxynucleotides complementary to conserved regions of the alpha- and beta-subunits of Gps (alpha-comm and beta-comm, respectively). Beta-adrenergic-induced Gs-mediated cAMP production was used as a positive control to estimate the efficiency of these compounds. Na+/H+ exchange, measured as ethylisopropyl amiloride-sensitive 22Na influx, was activated by 5- to 6-fold by a 30-minute preincubation of cells with 10 mmol/L NaF with a K0.5 for NaF of approximately 13 mmol/L. In contrast, no activation of 45Ca influx was observed under preincubation of vascular smooth muscle cells with NaF in Ca2+-free medium, whereas at [Ca2+]o >0.5 mmol/L, simultaneous addition of 45Ca and 10 mmol/L NaF led to sharply increased isotope uptake. NaF-induced 45Ca influx did not reach saturation up to 3 mmol/L [Ca2+]o and 20 mmol/L NaF and was correlated with the formation of calcium-fluoride complexes measured by light scattering. GTPgammaS increased basal cAMP production and Na+/H+ exchange, whereas GDPbetaS decreased isoproterenol-induced cAMP production and Na+/H+ exchange. Alpha-comm reduced whereas beta-comm augmented isoproterenol-induced cAMP production by 70%. Both oligodeoxynucleotides decreased basal Na+/H+ exchange by 40% to 50%. NaF-induced Na+/H+ exchange was not sensitive to alpha-comm but was inhibited by 60% in beta-comm-loaded cells. Neither basal nor NaF-induced 45Ca uptake was affected by GTPgammaS, GDPbetaS, and the oligodeoxynucleotides. Our results show that 45Ca uptake is activated by NaF in vascular smooth muscle cells by nonspecific accumulation of calcium-fluoride complexes and is not related to modification of Gps. On the contrary, the Na+/H+ exchanger is controlled by Gps, and Gp beta-subunits are involved in [Ca2+]o-independent activation of this carrier by NaF.

Aluminum Chloride↗
PubMed1999

Magnesium in drinking water supplies and mortality from acute myocardial infarction in north west England.

OBJECTIVES: To examine whether higher concentrations of magnesium in drinking water supplies are associated with lower mortality from acute myocardial infarction at a small area geographical level; to examine if the association is modified by age, sex, and socioeconomic deprivation. DESIGN: Small area geographical study using 13,794 census enumeration districts. Water constituent concentrations (magnesium, calcium, fluoride, lead) measured at water supply zone and assigned to enumeration districts. SETTING: 305 water supply zones in north west England. SUBJECTS: Resident population of 1,124,623 men and 1,372,036 women (1991 census) aged 45 years or more. MAIN OUTCOME MEASURE: Mortality from acute myocardial infarction, International Classification of Diseases, ninth revision (ICD-9) 410. Subsidiary analysis examined deaths from ischaemic heart disease, ICD 410-414. RESULTS: There were 21,339 male and 17,883 female deaths from acute myocardial infarction in 1990-92. Drinking water magnesium concentrations in water zones ranged from 2 mg/l to 111 mg/l (mean (SD) 19 (20) mg/l, median 12 mg/l); 24% of variation in magnesium concentrations was within zone and 76% was between zone. The relative risk of mortality from acute myocardial infarction (standardised for age, sex, and Carstairs deprivation quintile) for a quadrupling of magnesium concentrations in drinking water (for example, 20 mg/l v 5 mg/l) was 1.01 (95% confidence interval (CI) 0.99 to 1.03). When adjusted for north-south and east-west trends in mortality from acute myocardial infarction and for drinking water calcium, fluoride, and lead concentrations, this relative risk was 1.01 (95% CI 0.96 to 1.06). There was no evidence of a protective effect for acute myocardial infarction even among age, sex, and deprivation groups that were likely to be relatively magnesium deficient. For ischaemic heart disease mortality there was an apparent protective effect of magnesium and calcium (with calcium predominating in the joint model), but these were no longer significant when the geographical trends were incorporated. CONCLUSIONS: No evidence was found of an association between magnesium concentrations in drinking water supplies and mortality from acute myocardial infarction. These results do not support the hypothesis that magnesium is the key water factor in relation to mortality from heart disease.

Age Factors↗
PubMed2003

The effect of resin particle size on the rate of ion release: interactions in mixed bed systems.

The aim of the present study is to evaluate the influence of resin particle sizes on the rate of ions release from a mixture of ion-exchange resins (named NMTD) which supplies calcium, fluoride, and phosphate ions as the main mineral content, and to elucidate the different phenomena taking place through the related ion-exchange process. The final goal of the study, related to dental application (enamel restoration), is to limit the particle size range, since the rate of ion release is a key parameter in the successful achievement of such objective. Weak-type ion-exchange resins, loaded with the appropriate ions, were ground and sieved into granulometric fractions of bead diameters of 0.1-0.075, 0.075-0.063, and 0.063-0.05 mm. Particle size was controlled by a laser diffraction particle distribution analyzer. The experiments on the kinetics of ions release were carried out under batch conditions in artificial saliva desorption solution thermostatized at 37 degrees C. The release of Ca(2+) and F(-) was determined by corresponding ion-selective electrodes automatically controlled, whereas H(2)PO(4)(-) was measured spectrophotometrically by the inductively coupled plasma-optical emission technique (ICP-OES). The results of this study show that the process of ion-exchange for the different particle size fractions of resins is critical for the study of the kinetics release of the ions immobilized in the corresponding mixed bed polymeric matrices. In fact, despite the apparent narrow range of particle sizes of the mixed bed systems studied, appreciable differences in the rate of ions release are obtained. Since the ion release rate is depending on the contact surface, an increase of factor of 2 in particle size represents an increase of an order of magnitude of the resin contact surface due to the resin porosity. In this concern, it has been observed that the rate of ions release increases when particle size decreases. The interactions occurring during the ion release from the mixed bed resins (containing calcium-, fluoride-, and phosphate-loaded resins) can be interpreted by the following phenomena: H(2)PO(4)(-), which hardly modifies its rate of release in the presence of Ca(2+) and F(-) in the mixture, promotes a considerable increase in the rate of Ca(2+) release due to the formation of a calcium dihydrogen phosphate soluble complex. F(-) also produces an acceleration in the rate of Ca(2+) release due to the formation of solid CaF(2 )on the surface of cationic resin particles, which in contrast leads to a decrease in the rate of F(-) release.

Journal Article↗
PubMed1992

Bioavailability of fluoride in postmenopausal women: comparative study between sodium fluoride and disodium monofluorophosphate-calcium carbonate.

Fluoride (F) increases trabecular bone mass and can be used in the treatment of osteoporosis with crush fractures. As the bioavailability of sodium fluoride (NaF) can be impaired by concomitant absorption of calcium, both drugs have to be ingested separately. However, disodium monofluorophosphate-calcium carbonate (MFP-Ca), another F compound, allows a single administration. In a cross-over randomized study, we compared the bioavailability of both drugs under regular conditions of prescription. Ten postmenopausal women (aged 48-77 years) with glomerular filtration rate (GFR) greater than 70 ml/minute and without bone disease entered the study. Each received 25 mg of NaF [i.e., 11.3 mg F ion (F-)] fasting and 100 mg of Na2FPO3-1250 mg CaCO3 (i.e., 13.2 mg F-) with breakfast in a single dose separated by an 8-day washout. After dosing, plasma F levels and fractionated and total urinary F collection were determined during a 24-hour period using a specific electrode. Results show a significant shorter lag time absorption (Tmax = 1.4 +/- 0.2 hour) and a higher maximal concentration (Cmax = 260 +/- 60 ng/ml) for MFP-Ca than for NaF (Tmax = 2.5 +/- 0.4 hour; Cmax = 200 +/- 85 ng/ml). However, areas under curve (AUC) for MFP-Ca (1711 +/- 195 micrograms/liter/hour) and for NaF (1202 +/- 147 micrograms/liter/hour) were not significantly different. The relative bioavailability of both F compounds related to their fluoride content (i.e., 1.22 for AUC ratio) was equivalent, according to the Westlake method. These data provide the first evidence of comparable bioavailability of two F compounds in a population of postmenopausal women.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1981

Fluoride remineralization of demineralized bovine tooth enamel and hydroxyapatite pellets.

Both bovine enamel and hydroxyapatite pellets were remineralized in a fluoride-containing remineralization solution after prior demineralization for various lengths of time. In both the enamel and pellet systems, the degree of remineralization attainable was directly related to the extent of prior demineralization, although the demineralized material was never 100% recovered in remineralization. In some cases, fluoride levels up to several thousand parts per million were found at depths as great as 50 micrometers from the surface. The stoichiometry of the remineralized material and electron microprobe examination were consistent with the formation of fluoridated hydroxyapatite rather than calcium fluoride.

Animals↗
PubMed1990

Fluoride in dental plaque and its effects.

Total plaque fluoride is in the range 5-10 mg/kg (ppm) on a wet-weight basis. The variability of literature data on plaque fluoride is partly ascribed to analytical problems, many assays being close to or below the concentration detection limit of the fluoride electrode. A change in classification of plaque fluoride compartments is necessary, since recent work indicates that there are two pools of plaque F: less than 5% of the total F is in plaque fluid as the free ion, and the large remaining portion of total plaque F is designated as bound F, with the total F being greater than 95% extractable by cold 0.5 mol/L perchloric acid. Sources of plaque fluoride include the diet, saliva, and crevicular fluid; enamel is unlikely to be a regular source for plaque F unless it is either coated daily with labile fluoride compounds, such as calcium fluoride, or released by demineralization. The location and nature of plaque bound F are not established, but the present evidence is consistent with an intracellular location. Bound F may be released by acids produced in plaque during sugar fermentation, but it is unlikely to reach ion concentrations high enough for sufficient time periods to exert significant inhibition of plaque acidogenesis. Epidemiological evidence showing correlations between pooled plaque F concentrations and caries prevalence in the plaque donors does not exclude the possibility of coincidental effects of water F on both caries and plaque F concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Plaque↗