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PubMed1994

Fluoride release and effect on enamel softening by fluoride-treated and fluoride-untreated glass ionomer specimens.

The effect of fluoride application on fluoride release and enamel protection was studied using conventional and light-activated glass ionomers and composite. The specimens prepared from the materials were tested as (1) freshly mixed, (2) aged (29 days), (3) aged and fluoride treated, and (4) aged, fluoride treated, and aged (29 days). For fluoride application, the specimens were immersed in 1.2% NaF solution for 10 min and washed. After handling, the specimens were glued on polished bovine enamel slabs and immersed in lactic acid (pH 5.0) for 3 h. The microhardness of the enamel was measured before and after the acid immersion. Freshly mixed glass ionomers significantly prevented enamel softening. The effect disappeared (conventional glass ionomer) or decreased (light-activated glass ionomer) during aging, but was reestablished by fluoride application. After the subsequent 4 weeks of aging, no significant protective effect could be seen for either of the glass ionomers. The fluoride release, which was greatly increased by fluoride application, was still elevated after 4 weeks of aging for both materials.

Animals↗
PubMed1987

The influence of incorporated and adsorbed fluoride on the dissolution of powdered and pelletized hydroxyapatite in fluoridated and non-fluoridated acid buffers.

The effects of fluoride (F) incorporated into hydroxyapatite (HA), adsorbed onto the HA surface, and fluoride in solution were studied during HA dissolution. Dissolution rates at pH 5.0 and 25 degrees C were determined in fluoridated (0.1, 5.0 micrograms/mL) and non-fluoridated buffers for the following powdered and pelletized synthesized HAs: non-fluoridated HA, partially-fluoridated (100, 1000, 37,000 micrograms/g) HA, and surface-adsorbed fluoridated (100, 1000 micrograms/g) HA. The dissolution rate curves were used to derive two components we have called 'diffusion' and 'surface chemical reactivity'. With powders, the rate-determining factor was surface chemical reactivity during the first 60 min. Diffusion was reduced by increasing the F levels in the apatite or buffer. In non-fluoridated buffers, diffusion was reduced 29% for apatite with 100 micrograms/g incorporated F and 99% with 37,000 micrograms/g. Diffusion was reduced by 37% and 81% by 0.1 and 5.0 micrograms/mL F, respectively, in the buffer. With pelletized HA, the rate-determining factor during the first 10 min was surface chemical reactivity. Diffusion then became relatively more important, but the diffusion rate was independent of F content. During the dissolution of powdered apatites, F was taken up by the remaining apatite solid, as evidenced by the lower F concentration in solution than that calculated to be released during dissolution. There was also a decrease in the F concentration of the 0.1 microgram/mL buffer as reaction progressed. Pelletized apatites did not release enough F to influence dissolution significantly. Surface-adsorbed F was more effective than incorporated F in reducing HA dissolution.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗
PubMed2004

Assessment of malignant skeletal disease: initial experience with 18F-fluoride PET/CT and comparison between 18F-fluoride PET and 18F-fluoride PET/CT.

UNLABELLED: 18F-fluoride PET/CT was performed on 44 oncologic patients to evaluate its diagnostic accuracy in assessing malignant osseous involvement and in differentiating malignant from benign bone lesions. METHODS: (18)F-fluoride PET and (18)F-fluoride PET/CT were interpreted separately. Lesions showing increased (18)F-fluoride uptake were categorized as malignant, benign, or inconclusive. The final diagnosis of lesions was based on histopathology, correlation with contemporaneous diagnostic CT or MRI, or clinical follow-up of at least 6 mo (mean, 10 +/- 3 mo). RESULTS: Increased (18)F-fluoride uptake was detected at 212 sites, including 111 malignant lesions, 89 benign lesions, and 12 lesions for which the final diagnosis could not be determined. In a lesion-based analysis, the sensitivity of PET alone in differentiating benign from malignant bone lesions was 72% when inconclusive lesions were considered false negative and 90% when inconclusive lesions were considered true positive. On PET/CT, 94 of 111 (85%) metastases presented as sites of increased uptake with corresponding lytic or sclerotic changes, and 16 of the 17 remaining metastases showed normal-appearing bone on CT, for an overall sensitivity of 99% for tumor detection. For only 1 metastasis was PET/CT misleading, suggesting the false diagnosis of a benign lesion. The specificity of PET/CT was significantly higher than that of PET alone (97% vs. 72%, P < 0.001). PET/CT identified benign abnormalities at the location exactly corresponding to the scintigraphic increased uptake for 85 of 89 (96%) benign lesions. In a patient-based analysis, the sensitivity of PET and PET/CT was 88% and 100%, respectively (P < 0.05) and the specificity was 56% and 88%, respectively (not statistically significant). Among the 12 patients referred for (18)F-fluoride assessment because of bone pain despite negative findings on (99m)Tc-methylene diphosphonate bone scintigraphy, (18)F-fluoride PET/CT suggested malignant bone involvement in all 4 patients with proven skeletal metastases, a potential benign cause in 4 of 7 patients who had no evidence of metastatic disease, and a soft-tissue tumor mass invading a sacral foramen in 1 patient. CONCLUSION: The results indicate that (18)F-fluoride PET/CT is both sensitive and specific for the detection of lytic and sclerotic malignant lesions. It accurately differentiated malignant from benign bone lesions and possibly assisted in identifying a potential cause for bone pain in oncologic patients. For most lesions, the anatomic data provided by the low-dose CT of the PET/CT study obviates the performance of full-dose diagnostic CT for correlation purposes.

Bone Neoplasms↗
PubMed1994

Fluoride profiles in different surfaces of human permanent molar enamels from a naturally fluoridated and a non-fluoridated area.

The surfaces, sites and depths of fluoride profiles of enamel from a naturally fluoridated area (West Hartlepool, WHP, 1.9 parts/10(6) F in drinking water) and a non-fluoridated area (Leeds, LDS, < 0.1 parts/10(6) F in drinking water) were examined in detail. Using a regression curve, y = ax-b, comparisons of fluoride concentrations were made at depths of 1, 3, 5, 10, 20 and 30 microns at occlusal, middle and cervical sites of buccal, lingual, mesial and distal molar enamel surfaces. In the outermost enamels (< 10 mu in depth), fluoride concentrations tended to be lower in the occlusal sites than in the cervical sites. In interior enamels (> 20 microns in depth), the fluoride concentrations of molars from WHP were statistically higher than those from LDS, while few significant differences were found in the outermost layers. In the mesio- and disto-occlusal sites of approximal surfaces, there were some significant differences in the exponential regression coefficients of fluoride profiles between the two groups of molars.

Dental Enamel↗
PubMed2004

Salivary fluoride levels following application of fluoride varnish or fluoride rinse.

OBJECTIVES: This study examined the concentration of fluoride in whole saliva over time following the application of a fluoride varnish or a single rinse with a fluoride solution. METHODS: A two-period, two-treatment randomized cross-over experimental trial with a 2-week washout period was used with 16 adult subjects. In the first period, eight subjects rinsed once with a 0.05% NaF solution and 8 subjects had 5.0% NaF varnish applied to facial and lingual surfaces of 20 teeth. Stimulated whole saliva was collected at baseline, 5 and 15 min, 1, 2, 4, 8, 12, 24, 32, 48, 56, 72, 80, 96, 104 h. After the washout period each subject was switched to the other treatment and saliva was collected at the same intervals. Salivary fluoride content was measured with the micro-diffusion method. RESULTS: The NaF levels peaked at 5 min after application for both varnish (mean +/- SE 24.5 +/- 5.0 ppm) and rinse (3.2 +/- 0.8 ppm). Mean NaF levels returned to baseline, on average, within 2 h for the rinse and within 24 h for the varnish. The maximum fluoride levels were significantly greater (P < 0.01) with the varnish than with the rinse and remained above baseline levels for a longer duration. CONCLUSIONS: Salivary fluoride levels with the rinse returned to baseline, on average, in 2 h while they remained elevated for, on average, 24 h with the varnish. Salivary fluoride levels from the varnish were found to be comparable with those in previous studies for 1.1% neutral NaF.

Administration, Topical↗
PubMedDate not supplied

Enamel fluoride content after using amine fluoride- or monofluorophosphate-sodium fluoride-dentifrices.

The fluoride retention in enamel was determined in vivo comparing the short-term unsupervised use of amine fluoride- and monofluorophosphate-sodium fluoride-dentifrices. Acid-etch enamel biopsies in the double-blind study showed that the fluoride content in enamel was significantly higher following use of the amine fluoride dentifrice, 959 ppm F vs 330 ppm F. Both dissolution of the enamel, determined by the amount of phosphorus (33.9 micrograms vs 50.9 micrograms) and the depth of etch (6.2 microns vs 9.6 microns) were significantly reduced after use of the amine fluoride compared to the monofluorophosphate-sodium fluoride combination.

Amines↗
PubMed1992

The prevalence of developmental defects of enamel in 15-16-year-old children residing in three districts (natural fluoride, adjusted fluoride, low fluoride) in the north east of England.

Developmental defects of enamel were assessed in 15-year-old children born and continuously resident in three communities in the north east of England. In naturally fluoridated Hartlepool (F = 1.0-1.3 ppm), artificially fluoridated Newcastle (F = 1.0 ppm) and non-fluoridated Middlesbrough (F < 0.2 ppm) 361, 356 and 376 children respectively were examined. Conventional clinical recording and a photographic technique where colour slides are assessed at random were used and compared. Scoring in both assessments was done by using a modified version of both the Murray and Shaw index and the developmental defects of enamel index. In the clinical assessment more white lines and diffuse opacities were found in the fluoridated areas than in the non-fluoridated area. More opacities were recorded using the photographic assessment than with the clinical assessment, but a similar trend of an increased prevalence of white lines and diffuse opacities was observed using the photographic method. Overall, there was only a small increase in the prevalence of milder forms of enamel defects in fluoridated compared with non-fluoridated areas.

Adolescent↗
PubMed1983

Studies on dental fluoride-releasing polymers. IV: Fluoridation of human enamel by fluoride-containing sealant.

An experimental fluoride-containing acrylic sealant was prepared using methacryloyl fluoride-methyl methacrylate copolymer as powder component. The in vitro fluoride acquisition by human enamel coated with the sealant after 11, 21, 41 and 84 days of incubation in a phosphate buffer of pH7 at 37 degrees C was determined. Fluoride penetration and uptake were increased by prolonging the exposure time of enamel to the sealant. Most of the fluoride retained in enamel was found to be present as fluorapatite. The discharge of fluoride in the sealant was about 12% of initial load after 84 days of immersion.

Apatites↗
PubMed1981

Resonance Raman and absorption spectroscopic detection of distal histidine--fluoride interactions in human methemoglobin fluoride and sperm whale metmyoglobin fluoride: measurements of distal histidine ionization constants.

The pH dependence of the resonance Raman and absorption spectra of human methemoglobin fluoride (HbIIIF) and sperm whale metmyoglobin fluoride (MbIIIF) has been examined. Both the Raman and absorption spectra of HbIIIF and MbIIIF indicate the existence at alkaline pH of an equilibrium between the hydroxide and fluoride complexes. The absorption maxima of HbIIIF and MbIIIF solutions shift to longer wavelengths as the pH is decreased from neutrality. The Raman data show a corresponding shift of the 461- and 468-cm-1 Fe-F vibrational stretching peaks at pH 7.0 [Asher, S. A., & Schuster, T. M. (1979) Biochemistry 18, 5377] to 399 and 407 cm-1 at acid pH in MbIIIF and HbIIIF, respectively. These shifts are interpreted to result from protonation of the distal histidine and the formation of a hydrogen bond to the fluoride ligand. Measurements of the pH dependence of the absorption and resonance Raman spectra give distal histidine ionization constants (apparent) corresponding to pK = 5.1 (+/- 0.1) for HbIIIF and pK = 5.5 (+/- 0.1) for MbIIIF. An examination of the distal histidine pK values and the frequency of the hydrogen-bonded Fe--F stretching vibration at pH 5.0 of HbIIIF with and without inositol hexaphosphate indicates little difference in the distal histidine--heme distance between the so-called R and T quaternary forms of HbIIIF. These results indicate that the changes in the electronic spectrum of HbIIIF that occur upon switching from the R to the T form do not result from alterations in (1) the iron--fluoride bond distance, (2) the iron out-of-heme plane distance, or (3) the distal histidine--fluoride distance.

Animals↗
PubMed1975

Fluoride retention after rinsing with sodium fluoride and amine fluoride.

Fluoride retention from fluoride rinses (250 ppm F), calculated from F-concentrations and volumes of expectorates, and fluoride clearance, determined in whole saliva samples collected 1, 5 and 10 minutes after rinsing, were studied in 70 adults. F-retention from a 1:1 oleylamine-cetylaminefluoride rinsing solution (15 ml. 15 sec) was 410 mjg F, from a sodium fluoride rinse 343 mug F. 563 mug F were retained from a 30-sec amine fluoride rinse. Fluoride clearance was significantly slower after cetylaminefluoride rinses than after NaF rinses. Prerinsing with sodium lauryl sulfate or cetylaminechloride annihilated the F clearance superiority of cetylaminefluoride over NaF.

Adult↗
PubMedDate not supplied

Plaque fluoride concentrations in a community without water fluoridation: effects of calcium and use of a fluoride or placebo dentifrice.

The results of a recent study by Whitford et al. [Caries Res 2002;36:256-265] with subjects whose drinking water was fluoridated led to two major conclusions: (1) Compared to the use of a placebo dentifrice, plaque fluoride concentrations ([F]) throughout much of the day are not significantly increased by the use of an F dentifrice but (2) they are positively related to plaque [Ca] (p = 0.0001). The present double-blind, double-crossover study with 16 subjects used the same protocol and was done to: (1) determine the effects of the use of an F dentifrice on salivary and plaque [F] in a community without water fluoridation and (2) further examine the relationship between plaque [Ca] and [F]. Following the use of an F dentifrice or placebo for one week, whole saliva and plaque were collected 1.0 and 12 h after the last use of the products. The study was repeated to include rinsing with a 20 mmol/l CaCl(2) solution immediately before the use of the dentifrices. The CaCl(2) rinse had only minor effects on salivary [Ca] and [F] and none on the plaque concentrations. Unlike the results found in the fluoridated community, all salivary and plaque [F] associated with the use of the F dentifrice were significantly higher than those associated with the use of the placebo. The results suggest that the cariostatic effectiveness of an F dentifrice should be greater in areas without water fluoridation. As noted previously, plaque [F] were positively related to plaque [Ca] (p = 0.0001).

Adolescent↗
PubMedDate not supplied

Intra-oral fluoride retention 3 minutes after fluoride mouthrinsing in 4- to 5-year-old children: effects of fluoride concentration and rinsing time.

This study was undertaken to explore the site-specific retention rate and the possibility of shortening fluoride (F) mouthrinsing time of kindergarten children. Fluoride retention after 10-, 20- and 30-second mouthrinsing was determined in 43 kindergarten children aged 4-5 years. Tooth surfaces were sampled by a paper point method. Fluoride concentrations in the salivary film on tooth surfaces increased from primary molars to primary incisors in the maxilla and decreased from primary molars to primary incisors in the mandible. The fluoride solution reached the primary molars even after a 10-second rinse, but F concentrations were higher after 20 s than after 10 s and significantly higher after 30 s than after 10 s. No significant difference was observed between 20 and 30 s. The average total F retained in the mouth was 0.13 mg after 20 s and 0.17 mg after 30 s. It was concluded that 30-second mouthrinsing, which is used extensively in Japanese kindergartens, can be shortened to 20 s.

Analysis of Variance↗
PubMed2004

Distinct natures of beryllium fluoride-bound, aluminum fluoride-bound, and magnesium fluoride-bound stable analogues of an ADP-insensitive phosphoenzyme intermediate of sarcoplasmic reticulum Ca2+-ATPase: changes in catalytic and transport sites during phosphoenzyme hydrolysis.

The structural natures of stable analogues for the ADP-insensitive phosphoenzyme (E2P) of Ca(2+)-ATPase formed in sarcoplasmic reticulum vesicles, i.e. the enzymes with bound beryllium fluoride (BeF.E2), bound aluminum fluoride (AlF.E2), and bound magnesium fluoride (MgF.E2), were explored and compared with those of actual E2P formed from P(i) without Ca(2+). Changes in trinitrophenyl-AMP fluorescence revealed that the catalytic site is strongly hydrophobic in BeF.E2 as in E2P but hydrophilic in MgF.E2 and AlF.E2; yet, the three cytoplasmic domains are compactly organized in these states. Thapsigargin, which was shown in the crystal structure to fix the transmembrane helices and, thus, the postulated Ca(2+) release pathway to lumen in a closed state, largely reduced the tryptophan fluorescence in BeF.E2 as in E2P, but only very slightly (hence, the release pathway is likely closed without thapsigargin) in MgF.E2 and AlF.E2 as in dephosphorylated enzyme. Consistently, the completely suppressed Ca(2+)-ATPase activity in BeF-treated vesicles was rapidly restored in the presence of ionophore A23187 but not in its absence by incubation with Ca(2+) (over several millimolar concentrations) at pH 6, and, therefore, lumenal Ca(2+) is accessible to reactivate the enzyme. In contrast, no or only very slow restoration was observed with vesicles treated with MgF and AlF even with A23187. BeF.E2 thus has the features very similar to those characteristic of the E2P ground state, although AlF.E2 and MgF.E2 most likely mimic the transition or product state for the E2P hydrolysis, during which the hydrophobic nature around the phosphorylation site is lost and the Ca(2+) release pathway is closed. The change in hydrophobic nature is probably associated with the change in phosphate geometry from the covalently bound tetrahedral ground state (BeF(3)(-)) to trigonal bipyramidal transition state (AlF(3) or AlF(4)(-)) and further to tetrahedral product state (MgF(4)(2-)), and such change likely rearranges transmembrane helices to prevent access and leakage of lumenal Ca(2+).

Adenosine Diphosphate↗
PubMed1989

Effect of an acute maternal fluoride dose on fetal plasma fluoride levels and enamel fluoride uptake in guinea pigs.

We conducted this study to measure maternal plasma, fetal plasma, and fetal enamel fluoride concentrations for four hours following an oral F dose to near-term pregnant guinea pigs. We placed female guinea pigs on de-ionized (Group I) or 3-ppm-F (Group II) drinking water prior to breeding and during gestation. On the 57th day of gestation, we administered a maternal dose of NaF solution (0.6 mg F/kg) by stomach tube. We collected samples of maternal plasma, fetal plasma, and fetal enamel at baseline, at 15 and 30 min, and at one, two, and four h after administration of the dose. We assayed samples for F using a modification of the micro-diffusion and ion-specific electrode method. Group I mean baseline F values were: maternal plasma, 0.016; fetal plasma, 0.002; and fetal enamel, 7.0 ppm. Group II mean values were: 0.055, 0.004, and 19.0 ppm. After the maternal fluoride dose, the mean maternal plasma [F] rose sharply for 30 to 60 min and declined to about 50% of peak values by four h. Fetal plasma [F] changed less in absolute values, but similarly to maternal changes relative to baseline. Fetal enamel mean [F] rose more in Group II than in Group I. Baseline F status had an important effect on F uptake in fetal enamel following an acute maternal fluoride dose.

Administration, Oral↗
PubMedDate not supplied

Fluoride in dog parotid saliva after intravenous administration of sodium fluoride, sodium monofluorophosphate, and calcium fluoride.

Sodium fluoride, sodium monofluorophosphate, or calcium fluoride, in amounts equivalent to 0.5 mg/kg, were given intravenously to dogs and the effect on parotid saliva F was determined. Significant (P less than 0.01) differences in saliva F levels were related to the ionization of NaF, the hydrolysis of the PO3F ion, and the insolubility of CaF2.

Animals↗
PubMed1981

Differences in iron-fluoride bonding between the isolated subunits of human methemoglobin fluoride and sperm whale metmyoglobin fluoride as measured by resonance Raman spectroscopy.

The heme geometries of the isolated alpha and beta subunits of human methemoglobin fluoride (HbIIIF) and sperm whale metmyoglobin fluoride (MbIIIF) have been examined by exciting their Raman spectra within their ca. 6000-A charge-transfer absorption bands. The Fe-F stretching vibration at 471 cm-1 in the beta subunits shifts to 466 cm-1 in the alpha subunits and to 461 cm-1 in MbIIIF. The Fe-F bond is estimated to elongate by 0.02 A in the alpha subunits and 0.03 AZ in MbIIIF compared with that in the beta subunits. This bond elongation is interpreted to result from an increased iron displacement toward the proximal histidine side of the heme in the series MbIIIF greater than alpha greater than beta. A comparison of the isolated subunit spectra with that of tetrameric HbIIIF indicates little change occurs in isolated subunit heme geometry upon association into tetrameric HbIIIF. A correlation is found between the gamma max of the 600-A charge-transfer absorption band and the Fe-F bond length. Elongation of the Fe-F bond is associated with a shift of the absorption spectral maximum to a longer wavelength. However, the absorption spectral shift induced by the inositsol hexaphosphate induced R leads to T conversion does not result from a change in the Fe-F stretching frequency (+/- 0.5 cm-1). In contrast, frequency shifts are observed for heme macrocyclic vibrational modes. The data are interpreted to indicate that the effect of the R leads to T conversion in HbIIIF is to perturb heme macrocycle conformation without altering the heme out-of-plane iron distance or the Fe-F bond length.

Animals↗