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PubMed2004

Fluoride release from varnishes in two in vitro protocols.

BACKGROUND: The authors conducted a study to evaluate fluoride released from fluoride varnishes that had been applied with two different protocols. Fluoride release information for these two approaches may allow clinicians to vary application intervals to better meet the needs of their patients. METHODS: The authors painted enamel slabs from exfoliated primary molar teeth either in a single application (five samples) or three times within a single week (five samples) with fluoride varnish (Duraphat, Colgate-Palmolive, New York). The samples were immersed in buffered calcium phosphate solution (pH 6) to simulate the oral environment; the amount of fluoride released was measured during a span of six months. RESULTS: The total release of fluoride was significantly higher in the three-application regimen (34.9 micromoles) than in the single application (23.7 micromol). The rate of release was slower using the three-application regimen. Thus, applying fluoride-release varnish three times in a single week produced greater and longer release of fluoride than did one application. CLINICAL IMPLICATIONS: Massed application of fluoride varnish during a single period during the year may be as effective as spaced single applications. This method can be a good alternative to delivering fluoride varnish to high-caries-risk patients who are mobile or difficult to recall.

Buffers↗
PubMed1992

Effect of a fluoride solution on dentinal hypersensitivity.

This two-phase experiment assessed the effects over time of a solution containing 1.09% sodium fluoride, .40% stannous fluoride, and .14% hydrogen fluoride (.717% fluoride solution, DentinBloc) on pain associated with dentinal hypersensitivity. During phase I, 30 subjects demonstrating dentinal hypersensitivity to a blast of cool air were divided into three double blind experimental groups. After baseline data were collected for all subjects, one group was instructed to apply the .717% fluoride solution twice a day. A second group was instructed to apply a gel containing .04% stannous fluoride (Gel-Kam) twice a day. A third group was instructed to apply distilled water. Each subject was assessed at 2, 4, 8, and 16 weeks utilizing the "method of limits" with a standardized, repeatable cold thermal stimulus. The results of a two factor repeated ANOVA indicated that those subjects who applied the .717% fluoride solution reported significantly less sensitivity at the 2-week period than the other groups (P < .05). In addition, those subjects whose solution contained the 0.4% stannous fluoride reported significantly less sensitivity at the 4- to 8-week periods (P < .05). Phase II of the study assessed the .717% fluoride solution on a more precise time course. These included: immediately, 15 minute, 1 day, 1 week and 2 weeks. A one factor repeated ANOVA revealed that this effect presented 15-minute post application (P < .05) and continued throughout the testing periods. It was concluded that the fully active 0.717% fluoride solution was an effective agent in the control of dentinal hypersensitivity after two 1-minute applications.

Analysis of Variance↗
PubMed1983

[Local effect of various fluoridation substances].

The topical fluoride application is a caries-preventive treatment. The fluoride uptake in surface and subsurface sound human enamel differs, depending on the fluoride preparation. Fluoride tablets, solutions, gels, tooth pastes and varnishes are widely used as anticaries agents. The rate of fluoride uptake by the surface enamel from three different fluoride applications (sodium fluoride, amine fluoride and fluorosilicate) was determined. When enamel war treated with amine fluoride the highest and most stable fluoride concentrations were obtained.

Amines↗
PubMed1986

Crystallinity and solubility behavior of iron-containing fluoridated hydroxyapatites.

Iron-containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80 degrees C and pH 7.4 using FeCl2 X nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites at low fluoride content.

Biocompatible Materials↗
PubMed1997

Electrokinetic Behavior of Fluoride Salts as Explained from Water Structure Considerations

Unlike the other silver halides, silver fluoride is positively charged in its saturated solution as determined by nonequilibrium electrophoresis measurements. In the absence of surface hydrolysis reactions, other fluoride salts (LiF, CaF2 , and MgF2 ) also are positively charged in their saturated solutions. Furthermore, the electrokinetic behavior of these fluoride salts is rather insensitive to the fluoride ion activity in neutral or acidic solutions, and reversal of the sign of the surface charge by fluoride addition is not possible. Based on FTIR transmission spectra to describe the water structure of ionic solutions, in situ FTIR/internal reflection spectroscopy (FTIR/IRS) has been used to spectroscopically characterize interfacial water at fluoride salt surfaces. The experimental spectra were examined by consideration of the O-H stretching region (3000-3800 cm-1 ) associated with the vibrational spectra of interfacial water. These results reveal a unique hydration state for fluorides and explain the anomalous electrokinetic behavior of fluoride salts such as LiF, CaF2 , and MgF2 , which show an unexpected insensitivity to the fluoride ion concentration in solution. It appears that this insensitivity is due to the formation of strong hydrogen bonding of the fluoride ions with water molecules. This hydration state prevents the accommodation of excess fluoride ions at surface lattice sites and accounts for the observed electrokinetic behavior.

Journal Article↗
PubMed2003

Quantitative measure for the "nakedness" of fluoride ion sources.

A quantitative measure for the donor strength or "nakedness" of fluoride ion donors is presented. It is based on the free energy change associated with the transfer of a fluoride ion from the donor to a given acceptor molecule. Born-Haber cycle calculations were used to calculate both the free energy and the enthalpy change for this process. The enthalpy change is given by the sum of the fluoride ion affinity of the acceptor (as defined in strict thermodynamic convention) and the lattice energy difference (DeltaU(POT)) between the fluoride ion donor and the salt formed with the acceptor. Because, for a given acceptor, the fluoride affinity has a constant value, the relative enthalpy (and also the corresponding free energy) changes are governed exclusively by the lattice energy differences. In this study, BF(3), PF(5), AsF(5), and SbF(5) were used as the acceptors, and the following seven fluoride ion donors were evaluated: CsF, N(CH(3))(4)F (TMAF), N-methylurotropinium fluoride (MUF), hexamethylguanidinium fluoride (HMGF), hexamethylpiperidinium fluoride (HMPF), N,N,N-trimethyl-1-adamantylammonium fluoride (TMAAF), and hexakis(dimethylamino)phosphazenium fluoride (HDMAPF). Smooth relationships between the enthalpy changes and the molar volumes of the donor cations were found which asymptotically approach constant values for infinitely large cations. Whereas CsF is a relatively poor F(-) donor [(U(POT)(CsF) - U(POT)(CsSbF(6))) = 213 kJ mol(-)(1)], when compared to N(CH(3))(4)F [(U(POT)(TMAF) - U(POT)(TMASbF(6))) = 69 kJ mol(-)(1)], a 4 times larger cation (phosphazenium salt) and an infinitely large cation are required to decrease DeltaU(POT) to 17 and 0 kJ mol(-)(1), respectively. These results clearly demonstrate that very little is gained by increasing the cation size past a certain level and that secondary factors, such as chemical and physical properties, become overriding considerations.

Journal Article↗
PubMed1984

The effect of fluoride on fertilized eggs of a freshwater fish, Catla catla (Hamilton).

The eggs of Catla catla were exposed to 2 fluoride media, (1) effluent dilutions containing 1.86, 3.21, 7.12, 9.56, and 16.23 ppm fluoride, and (2) fluoride (NaF) solutions containing 1.86, 3.56, 7.34, 10.01, and 16.68 ppm fluoride. The eggs exposed to 1.86 ppm fluoride (in both media) hatched at the end of 6 h, while in rest of the fluoride concentrations hatching was delayed by 1-2 h. The eggs showed decreases in water and protein and increase in fluoride contents. Toxicity of fluoride to eggs was more related to the availability of fluoride ions, than to the total fluoride in the media.

Animals↗
PubMed1999

Magnesium fluoride-dependent binding of small G proteins to their GTPase-activating proteins.

GTPase-activating proteins (GAPs) enhance the intrinsic GTPase activity of small G proteins, such as Ras and Rho, by contributing a catalytic arginine to the active site. An intramolecular arginine plays a similar role in heterotrimeric G proteins. Aluminum fluoride activates the GDP form of heterotrimeric G proteins, and enhances binding of the GDP form of small G proteins to their GAPs. The resultant complexes have been interpreted as analogues of the transition state of the hydrolytic reaction. Here, equilibrium binding has been measured using scintillation proximity assays to provide quantitative information on the fluoride-mediated interaction of Ras and Rho proteins with their respective GAPs, neurofibromin (NF1) and RhoGAP. High-affinity fluoride-mediated complex formation between Rho.GDP and RhoGAP occurred in the absence of aluminum; however, under these conditions, magnesium was required. Additionally, the novel observation was made of magnesium-dependent, fluoride-mediated binding of Ras.GDP to NF1 in the absence of aluminum. Aluminum was required for complex formation when the concentration of magnesium was low. Thus, either aluminum fluoride or magnesium fluoride can mediate the high-affinity binding of Rho. GDP or Ras.GDP to GAPs. It has been reported that magnesium fluoride can activate heterotrimeric G proteins. Thus, magnesium-dependent fluoride effects might be a general phenomenon with G proteins. Moreover, these data suggest that some protein.nucleotide complexes previously reported to contain aluminum fluoride may in fact contain magnesium fluoride.

Aluminum↗
PubMed2004

Attitudes to water fluoridation in general dental practice in the North East of England.

OBJECTIVE: To find out the knowledge of, and attitudes towards, water fluoridation of a sample of general dental practitioners working in the North East of England. DESIGN: Anonymous, self-completed postal questionnaire. SETTING: North East of England, both a fluoridated and non-fluoridated area. SUBJECTS AND METHODS: Following a small pilot survey, questionnaire to 79 general dental practitioners (44 in a non-fluoridated area, 35 in an area supplied with fluoridated water at one part per million) contracted to provide National Health Service (NHS) treatment in the North East of England. RESULTS: Fifty-five general dental practitioners returned questionnaires (a 70% response rate). Most respondents supported the principle of water fluoridation. Over half of the respondents indicated that they would benefit from more information and training on the issue of water fluoridation. There were marked differences in knowledge and attitudes to fluoridation between dental principals and associates. The sample was evenly split about what to do with a parent who was unsure about (whether to support) fluoridation even after the dentist had discussed the issue and answered questions. CONCLUSIONS: The majority of general dental practitioners support water fluoridation although some lack knowledge and expertise which might inhibit advocacy of it.

Attitude of Health Personnel↗
PubMed1986

Contribution of fluoride vehicles to change in caries severity in Australian adolescents.

The contribution of a fluoride vehicle to change in caries severity in a population depends on the importance of its association with caries severity and the population's exposure to the vehicle. The present study aimed to quantify population trends in Australian adolescents' exposure to fluoridated water supplies, fluoride supplements and fluoride-containing dentifrice between 1965 and 1978, and conditionally up to 1990; to predict changes in caries severity; and to indicate the change attributable to each fluoride vehicle. At a population level, proportion of lifetime exposure to fluoridated water supplies and market-share held by fluoride-containing dentifrice increased over the period 1965 to 1990. Regular use of fluoride supplements first increased, then decreased over the period. Caries severity was predicted to have decreased markedly for Australian adolescents over the period 1965 to 1990, with the rate of change over the period varying by age. Fluoridated water supplies, followed by fluoride-containing dentifrice contributed most to the change in caries severity.

Adolescent↗
PubMed1999

Dental fluorosis among persons exposed to high- and low-fluoride drinking water in western Norway.

The aim of this project was to study the prevalence and severity of dental fluorosis among persons exposed to moderate- to high- or low-fluoride drinking water in western Norway, and to assess the risk factors involved. Subjects aged 5 to 18 years who had been lifelong consumers of moderate- to high-fluoride groundwater (> or = 0.50 mg F/L) were selected for the study (n = 113). A comparison group (n = 105) was chosen among consumers of low-fluoride surface water (approximately 0.10 mg F/L) in the same district. The Thylstrup-Fejerskov (TF) Index was used to score dental fluorosis. A questionnaire was used to obtain information on fluoride exposure and other relevant factors. Among the consumers of low-fluoride water 14.3% showed dental fluorosis (TF score 1-2) as compared to 78.8% in the group consuming moderate- to high-fluoride water (TF scores 1-7). Premolars were most frequently affected, but severe cases (TF scores 3-7) were equally prevalent in maxillary central incisors and first molars. In logistic regression analysis with TF score 0 or TF score > or = 1 as the dependent variable, only fluoride concentration in the drinking water was associated with a statistically increased risk of dental fluorosis (odds ratio: 18.9; 95% CI: 8.85-40.44). In the study area, which was characterised by multiple fluoride sources, uncontrolled groundwater with moderate to high fluoride content was the most important factor in the development of dental fluorosis. In order to prevent dental fluorosis, groundwater wells should routinely be analysed for fluoride.

Adolescent↗
PubMed1995

Associations between exposure to fluoridated drinking water and dental caries experience among children in two Australian states.

OBJECTIVES: This study assessed associations between exposure to fluoride in water and dental caries experience among children in two Australian states. METHODS: Cross-sectional data were obtained from 9,690 South Australian children aged 5-15 years and 10,195 Queensland children aged 5-12 years. School dental service practitioners recorded DMFS and dmfs data. A questionnaire to parents gained information about residential history that was used to calculate children's percent of lifetime exposed to fluoridated water. RESULTS: Greater exposure to fluoride in water was associated with lower dmfs and DMFS in both states (P < .01), although in South Australia the effect for DMFS was statistically significant only after controlling for extent of unknown fluoridation exposure and for fluoride supplements. Caries-fluoridation associations were stronger for dmfs compared with DMFS and for Queensland (5% of population fluoridated) compared with South Australia (70% of population fluoridated). Effects for DMFS persisted after controlling for socioeconomic factors. CONCLUSIONS: Fluoridation was associated with lower caries experience. The weaker association with DMFS in South Australia may be due to less caries and more fissure sealants in that state, and is consistent with a "diffusion" effect, whereby a high proportion of the population exposed to fluoridation diminishes differences among exposure groups.

Adolescent↗
PubMed1996

The effectiveness of community water fluoridation in the United States.

Grand Rapids, the first city in the world to implement controlled water fluoridation, has served as a model for thousands of other communities. Fluoridation is one of the greatest public health and disease-preventive measures of all time. Its advantages include effectiveness for all, ease of delivery, safety, equity, and low cost. Today, nearly 56 percent of the US population lives in fluoridated communities (62% of those on central water supplies). Previously observed caries reductions of one-half to two-thirds are no longer attainable in the United States because other fluoride methods and products have reduced the caries prevalence in all areas, thus diluting the measurement of effectiveness, and because benefits of fluoridation are dispersed in many ways to persons in nonfluoridated areas. Water fluoridation itself, however, remains as effective as it ever was among groups at high risk to dental caries. Contrary to early beliefs that stressed the importance of preeruptive fluoride exposure, fluoridation also provides an important source of topical fluoride and facilitates remineralization. Although data on effectiveness and safety are compelling, future progress of water fluoridation will be affected by economic, political, and public perception factors.

Cariostatic Agents↗
PubMed1997

Prior fluoridation in childhood affects dental caries and tooth wear in a south east Queensland population.

Fluoride exposure in early life has an effect on dental caries experience, but does it affect tooth wear in later life? Ninety-six South East Queensland subjects were studied. Their histories revealed three groups; a fluoride (F-) in water supply, a F- by supplement, and a non-fluoridated (non F-) group. Significantly higher caries experience was found in the non-F- group compared with F- in water group and the F- supplement group. No statistically significant difference in caries experience was found between the F- in water and F- supplement groups. Overall, tooth wear affected more sextants of the dentitions of non-fluoridated, high-caries subjects than of fluoridated low-caries subjects. Comparisons of wear patterns on sextants of the dentitions, between the fluoridated and non-fluoridated groups, revealed that in sextants where attrition was present no marked differences were discernible between the two groups. However, in most sextants where incisal, palatal, occlusal or non-occlusal erosion was found, this type of wear was commoner in non-fluoridated subjects. The exceptions were the mandibular molar sextants, where prior fluoride-exposure did not appear to protect against occlusal erosion patterns. This study showed that fluoride exposure during the first 12 years of life, which reduced dental caries in this population, may also protect teeth from wear to some extent.

Adolescent↗
PubMed2000

In vitro fluoride release from aesthetic restorative materials following recharging with APF gel.

In this in vitro study, the fluoride ion release from three more-viscous conventional glass ionomer cements (GICs)--ChemFlex, Fuji IX GP, Ionofil Molar--four polyacid-modified resin composites (compomers)--Dyract AP, Compoglass F, Freedom, F2000--and a hybrid resin composite--Ariston pHc--were compared. The amounts of fluoride release from 3 x 2.7 mm specimens were measured over six weeks using a fluoride ion-selective electrode. After six weeks, the specimens were recharged with 2 ml of 1.23 per cent acidulated phosphate fluoride (APF) gel for four minutes. The recharged specimens were then assessed for the amounts of fluoride release over another six weeks. Statistical analyses were performed using one-way and repeated measures ANOVA. The GICs and Compoglass F showed significantly higher initial fluoride release rates during the first two days (p < 0.05). After the first two days, fluoride release rates from all materials dropped quickly and became essentially stabilized within three-five weeks, in an exponential mode. The recharging of the specimens with APF gel caused a brief, but significant, increase in fluoride release for all materials (p < 0.05), before decreasing to previous comparable rates. Compoglass F released relatively more fluoride, and Ariston pHc relatively less, after APF gel application than before. The lowest total amounts over the study were released by Dyract AP and Freedom. The newer compomers, as well as the newer more-viscous GICs, appear to act as fluoride reservoirs to varying extents.

Acidulated Phosphate Fluoride↗
PubMed1999

Caries and fluorosis prevalence in communities with different concentrations of fluoride in the water.

The need to defluoridate and fluoridate the water supplies in areas with drinking water naturally containing above-optimal (>/=2.5 mg/l) and suboptimal (</=0.3 mg/l) fluoride concentration and caries and fluorosis prevalence of 12-year-old schoolchildren were assessed in Italy. In the low-fluoride area, 48.4% children were caries-free (DMFT = 0) and the DMFT and DMFS were 1.5 and 2.6; in the high-fluoride area, 46.8% had a DMFT = 0 and the values of the indices were 1.4 and 1.6, respectively. Multiple logistic regression analysis showed a significant association in the caries-free status according to parents' employment status (OR = 1.2, 95% CI = 1.1-1.3) and children's sweets consumption, since children who consumed sweets at least once a day had an adjusted odds ratio of 1.8 (95% CI = 1.4-2.3) compared to those with a lower consumption. Multiple linear regression analysis showed that DMFT and DMFS were significantly higher in children with a lower socioeconomic status and in those who consumed sweets at least once a day, with the DMFS significantly associated also with the area of residence. DT and FT scores were higher in the high- and low-fluoride areas, respectively. No evidence of fluorosis was reported in 94.5 and 55.3% of children in the low- and high-fluoride areas, respectively. The Community Fluorosis Index (CFI) for all permanent teeth was significantly higher in the high-fluoride area, 0.8, than the value, 0.1, found in the low-fluoride community. Our results substantiate the difficulties in defining universal guidelines for the fluoridation or defluoridation of drinking water and the need for an epidemiological approach to the decision as to fluoridate and defluoridate the water supply.

Analysis of Variance↗
PubMedDate not supplied

Systemic versus topical fluoride.

The actual mechanism of fluoride action is still a subject of debate. A dogma has existed for many decades, that fluoride has to be ingested and acts mainly pre-eruptively. However, recent studies concerning the systemic effect of fluoride supplementation concluded that the caries-preventive effect of fluoride is almost exclusively posteruptive. Moreover, epidemiologists have cast doubt on the validity of the 'old' studies dealing with fluoride use. The concept of the posteruptive fluoride effect is supported by in vitro and in situ investigations demonstrating that the mode of action of fluoride can be attributed mainly to its influence on de- and remineralization kinetics of dental hard tissues. Therefore, topical fluoride application (e.g. in the form of fluoridated dentifrices) should be encouraged. There are still important questions open that need to be answered despite existing knowledge about the caries-preventive effect of fluoride.

Administration, Oral↗
PubMedDate not supplied

Fluoride varnishes in caries prevention.

The first fluoride varnishes were developed during the 1960s (Duraphat) sodium fluoride varnish) and 1970s (Fluor Protector) silane fluoride varnish) to prolong the contact time between fluoride and enamel. Fluoride varnishes adhere to enamel, and calcium fluoride formed after application acts as a long-term reservoir of fluoride. Currently Duraphat varnish is the most widely used topical fluoride for professional application in Europe, and the use of fluoride varnishes is increasing in the USA. Duraphat varnish has been effective in three decades of clinical studies, but the results of Fluor Protector varnish are inconclusive. The percent caries reductions found in the 1990s have generally been lower than those reported in earlier studies, probably because of the higher exposure to other preventive measures in the more recent studies. In studies comparing Duraphat varnish and APF gel, Duraphat varnish was equally or more effective than APF gel. Sealants were most effective in preventing occlusal caries. Four applications per year, or three weekly applications once a year, have been found to be effective. However, several studies have shown that two applications per year may provide comparable results. Application is fast and easy. Professional prophylaxis is not necessary, and the patient can leave immediately after the treatment. No acute toxicity has been reported after using any fluoride varnish.

Acidulated Phosphate Fluoride↗