Low Fluoride Concentrations Research Articles

Effects of Li<sub>2</sub>O on Properties of Low Fluoride Content Mould Flux for High Speed Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by Li2O in mould flux. The effects of Li2O on properties of low fluoride content mould flux for high speed continuous casting were studied. The properties included melting temperature, viscosity, fluidity, surface tension and Al2O3 inclusion adsorption. The results showed that with the increase of Li2O content, melting temperature and viscosity of mould flux decreased obviously, fluidity increased, surface tension changed little, and Al2O3 inclusion adsorption of mould flux increased. In order to play an effective role, the appropriate Li2O content should be less than 4 per cent. The crystallization state of mould flux changed after slag adsorbed Al2O3. There were some small cuspidine and wollastonite crystals in the sample.

Effects of BaO on Properties of Low Fluoride Content Mould Flux for High Speed Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by BaO in mould flux. The effects of BaO on melting temperature, viscosity, fluidity, surface tension, Al2O3 inclusion and adsorption of low fluoride content mould flux for high speed continuous casting were studied, as well as the effect of basicity on crystallization property. The results showed that with the increase of BaO content, melting temperature, viscosity and surface tension of mould flux decreased obviously, and fluidity and Al2O3 inclusion adsorption increased. Partial fluoride could be replaced by BaO in mould flux. The BaO content should be less than 4 per cent so that it can play an effective role. The basicity had great influence on crystallization property.

Effects of K<sub>2</sub>O on Properties of Low Fluoride Content Mould Flux for High Speed Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by K2O in mould flux. The effects of K2O on melting temperature, viscosity, fluidity, surface tension, Al2O3 inclusion and adsorption of low fluoride content mould flux for high speed continuous casting were studied. The results showed that with the increase of K2O content, melting temperature, viscosity and surface tension of mould flux decreased obviously, and fluidity and Al2O3 inclusion adsorption increased. When basicity was 0.81, 1.03 and 1.22, the suitable content of K2O was 5%, 5% and 4% respectively, which could play an effective role. Partial fluoride could be replaced by K2O in mould flux.

Fluoride-induced death of rat erythrocytes in vitro

Although fluoride (F) in low concentrations is essential for teeth and bone development, its excessive consumption causes numerous deleterious abnormalities in cellular metabolism and physiology often leading to cell death. The present study was performed to establish the toxic F effects inducing the death of rat erythrocytes in vitro. The cells were cultured in the presence of 0.5–16mM NaF for 1, 5 and 24h. The progression of erythrocyte death was monitored by cell viability (calcein assay), membrane integrity (hemolysis assay), alterations in the cell morphology (light microscopy) and size (flow cytometry forward scatter), plasma membrane scrambling (annexin V binding). To elucidate the molecular mechanisms underlying F-induced cell death, the cytosolic Ca2+ activity (Fluo-3 fluorescence) and ceramide formation (binding of FITC-labeled antibodies) were determined. Exposure of the rat erythrocytes to NaF considerably suppressed their viability and caused partial cell hemolysis within 24h. The cells underwent dramatic morphological alterations resulted in appearance of shrunken echinocytes after 1h and swollen spherocytes within 24h. The development of NaF-induced erythrocyte death was accompanied by progressive PS externalization at the outer cell membrane, ∼45% of the cells were annexin V-positive in response to 16mM NaF within 24h with a small cell population exhibiting necrotic features. The cell death was preceded by considerable accumulation of the free cytosolic Ca2+, with statistically significant increase in the number of Fluo-3-positive erythrocytes observed as early as during 1-h incubation with 0.5mM NaF. NaF also induced moderate ceramide formation. Overall, exposure of the rat erythrocytes to NaF triggers rapid progression of their death in a dose- and time-dependent manner, with appearance of apoptotic cells after 1 and 5h and transition to necrosis within 24h. An increase in intracellular [Ca2+] appears to be crucial mechanism implicated in development of NaF-induced apoptosis in rat erythrocytes.

Effects of Na 2CO 3 on properties of low fluoride content mould flux for thin slab continuous casting

To reduce fluorine pollution, partial fluoride could be replaced by Na 2C0 3 in mould flux for continuous casting. The properties including melting temperature, viscosity fluidity, surface tension and A1 20 3 inclusion adsorption of low fluoride content mould flux with addition of Na 2C0 3 for thin slab casting were studied. The results showed that with the increase in Na 2C0 3 content, melting temperature, viscosity and viscous activation energy of mould flux decreased obviously, fluidity increased, surface tension changed little, and A1 20 3 inclusion adsorption of mould flux increased. The Na 2C0 3 could play effective role when its content was less than 9%. The results would play a guiding role in designing of low fluoride content mould flux for thin slab continuous casting.

Effects of B<sub>2</sub>O<sub>3</sub> on Properties of Low Fluoride Content Mould Flux for Thin Slab Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by B2O3 in mould flux. The effects of B2O3 on properties of low fluoride content mould flux for thin slab continuous casting were studied. The properties included melting temperature, viscous characteristics, fluidity, surface tension and Al2O3 inclusion adsorption. The results showed that with the increase of B2O3 content, melting temperature, viscosity, viscous activation energy and surface tension of mould flux decreased obviously, fluidity increased, and Al2O3 inclusion adsorption of mould flux changed little. The B2O3 could play effective role when its content was less than 6%. The results would play a guiding role in designing of low fluoride content mould flux for thin slab continuous casting.

Fluoride concentration in dentine as a biomarker of fluoride intake in European roe deer (Capreolus capreolus) – An electron-microprobe study

ObjectiveFluoride concentration in dentine has been recommended as the best marker for the level of chronic fluoride intake and the most suitable indicator of an individual's total body burden of fluoride. We analysed fluoride concentrations in the dentine of cheek teeth of European roe deer from fluoride-polluted habitats to retrospectively assess the level of fluoride uptake into the tissue. Thereby, we tested the hypothesis of the existence of mechanisms that limit fluoride intake of individuals and fluoride exposure of forming dental hard tissues during the late foetal and early postnatal periods in the species. DesignUsing electron-microprobe analysis, fluoride profiles were obtained on sectioned P4s, M1s, and M3s from individuals exhibiting pronounced dental fluorosis. Fluoride concentrations were compared between early formed (peripheral) and late-formed (juxtapulpal) dentine both within single teeth and amongst the three different teeth studied. ResultsPeripheral dentine of the M1, which is formed during the late foetal and early postnatal periods, exhibited markedly lower fluoride concentrations than juxtapulpal dentine of the same tooth and both, peripheral and juxtapulpal dentine of P4 and M3 that are formed post-weaning. ConclusionsOur study provides strong support for the hypothesis that in the European roe deer the prenatal and early postnatal (pre-weaning) stages of dental development are (largely) protected against exposure to excess fluoride. This is attributed to the operation of certain protective mechanisms during these periods.

The relationship between dental caries and dental fluorosis in low, moderate and high fluoride areas of Udaipur district, India.

Objective: The purpose of the study was to assess the relationship between dental caries and dental fluorosis in Bhil Tribes living in Udaipur district India, known for endemic fluorosis. Method: A total of 420 Bhil tribes selected from areas with low (0-1.5mg/l), moderate (1.5-3.0mg/l) and high (>3mg/l) water fluoride concentration were interviewed and examined for caries and dental fluorosis. Dental caries and fluorosis were recorded according to the DMFT system and Dean Fluorosis index. All the Bhil tribes were exposed to a written questionnaire, constructed in English and translated into local language and – for control purposes – translated back to English. Intra-oral examination was conducted using by two examiners. Result: Bhil, Garasia, Meena and Gameti were most commonly present castes among Bhil tribes. The prevalence of dental fluorosis was 33.1% in low, 33.3% in moderate and 33.6% in high fluoride areas. In the low fluoride area mean number of decayed teeth and mean DMFT was 5.52 and 7.37 respectively while in high fluoride area it was higher, mean decayed and mean DMFT was 9.27 and 12.06 respectively. There was significant difference in mean DMFT between low, moderate andthe high fluoride areas (P = 0.00). DMFT score was 12.04 in severe fluorosis cases while it was 8.67 in normal fluorosis cases. There was significant difference in mean DMFT between all four castes (Bhil, Garasia, Meena and Gameti). Conclusion: Dental caries increases with increasing severity of dental fluorosis in low, moderate and high fluoride areas. Thus, a positive relationship between dental caries and dental fluorosis was observed in all the three areas. Key words: Dental caries, Fluorosis, Bhil tribes.

Fluoride rechargability of a non-resin auto-cured glass ionomer cement from a fluoridated dentifrice: An in vitro study

In addition to their fluoride-releasing properties, glass ionomer cement (GICs) have the ability to reuptake and release fluorides from commonly used sources like fluoridated dentifrices. This property has the potential to provide a continuous low concentration of fluoride in the saliva aiding in caries prevention. The superior fluoride-recharging abilities of resin-modified GICs over conventional GICs have been documented. The manufacturer of a non-resin, auto-cured GIC (GC Fuji VII) claims fluoride release from the product to be about six times that of conventional GIC. It was hypothesized that perhaps this high fluoride release could translate into a high reuptake and release, when exposed to a 1 000 ppm fluoridated dentifrice every day, thus providing increased fluoride levels in saliva. This study therefore examined fluoride-recharging abilities of the non-resin, auto-cured glass ionomer cement from a 1 000 ppm fluoridated dentifrice and compared it with resin-modified glass ionomer cement. Twelve glass ionomer discs each of resin-modified glass ionomer cement (GC Fuji II L C, Group 1) and the non-resin, auto-cured glass ionomer cement (GC Fuji VII, Group 2) were prepared with precise dimensions of 9 x 2 mm. The 12 specimens in each group were further subdivided into two subgroups of six each. Subgroup A involved no fluoride treatment (Control). Subgroup B involved application of a 1 000 ppm dentifrice for 2 minutes twice daily with a soft toothbrush. The disc-specimens were then suspended in airtight plastic bottles containing exactly 20 ml double distilled water. The fluoride concentration of the water in which the specimen discs were immersed was measured by means of a fluoride ion selective electrode connected to an ion selective electrode meter/digital ion analyzer at 1, 2, 7, 15, and 30 days. It was performed using the Kruskal-Wallis Test. Fuji VII, despite a high fluoride release, did not significantly recharge when exposed to a 1 000 ppm fluoridated dentifrice.

Geochemical characteristics of fluoride in groundwater of Gimcheon, Korea: lithogenic and agricultural origins

The occurrence of fluoride in groundwaters can be influenced by many factors. In Korea, the fluoride-rich groundwaters are normally associated with rock types, especially granite and gneiss. In Gimcheon, high-fluoride groundwaters (up to a maximum of 2.15 mg/L) were observed with bimodal distribution of concentrations. The groundwater in this area showed relatively high concentrations of anthropogenic chemicals such as nitrate, chloride, and sulfate. Statistical analysis showed that fluoride is positively correlated with pH, alkalinity, sodium, and lithium, indicating that the interaction with granite is the main cause enriching its concentration. In Gimcheon, δ18O data of groundwater showed a negative correlation with nitrate and can be used as an indicator of groundwater age. The four samples of fluoride-rich groundwater were plotted in the light δD and δ18O region, showing that they were the result of long water–rock reaction. However, other groundwater with a low-fluoride concentration was evenly distributed throughout all δD and δ18O ranges and did not show a statistically significant correlation with nitrate, indicating possible mixing with another source of fluoride. Considering the influence from the surface on the geochemical characteristics of groundwater in this area, anthropogenic sources including phosphate fertilizer containing fluoride and pesticides may also have partly contributed to the concentrations of fluoride in the low-fluoride groundwater. The scattered distribution of fluoride-rich groundwater and the significant correlation with lithium suggest that pegmatite is the main rock type increasing fluoride concentration in this area.

Effects of anodization parameters on the formation of titania nanotubes in ethylene glycol

The effects of fluoride concentration, anodization temperature, and anodization applied potential difference on the formation and dimensions of the titania nanotubes in ethylene glycol/water systems were investigated. It was found that fluoride concentration and anodization temperature were the two critical parameters for controlling the nanotube formation whilst anodization applied potential difference mainly contributes to tuning the dimension of the nanotubes. Electrolytes containing a low fluoride concentration are beneficial for initiating nanotube formation, whilst a higher anodization temperature is helpful to the rapid growth of the nanotubes. It is shown that the current–time curve obtained during the anodization can be used as an effective tool to predict the morphology of titania nanotubes. A model based on the competition between electrochemical oxidation of the titanium and chemical dissolution by fluoride ions is developed to explain the experimental observations.

Groundwater Classification Using Multivariate Statistical Methods: Birimian Basin, Ghana

Groundwater from the aquifers of Birimian system in the northern and southern sections of the country was sampled for the concentrations of the major ions in the area. The objective was to determine the spatial groundwater associations which will in turn be used to infer the position of each groundwater group in the flow system. In addition, this study intended to determine the major sources of variation in the hydrochemistry and the suitability of groundwater from aquifers of the Birimian system for irrigation activities. R-mode factor and Q-mode hierarchical cluster analyses were used together with conventional graphical techniques. This study revealed four groundwater associations (clusters) representing three major groundwater types in the Birimian System: the Ca–HCO3 water types which make up Clusters (groups) 1 and 2 members; the Na-K-Cl water types comprising cluster 3 members, and Mg–HCO3 water types comprising Cluster 4 members. Cluster 2 has the lowest average electrical conductivity of 194 mS/m with total dissolved solids (TDS) ranging between 50 and 250 mg/L. This is the freshest groundwater type in the area and is typical of groundwater in recharge areas of the groundwater flow system. Cluster 1 members range in salinity between 50 and 500 mg/L. The highest average salinity is contained in Cluster 3, with TDS in the range of 300 to 1,000 mg/L, which is characteristic of groundwaters in discharge areas of the groundwater flow system. Members of this group are also characterized by high fluoride concentrations; average fluoride concentration in this group is 4.60 mg/L. Cluster 3 is the least desirable of the four clusters, for domestic water supply. Cluster 4 has TDS in the range of 300 and 1,000 mg/L, with low fluoride content. This study finds that the hydrochemistry of groundwater in the terrain is controlled by three major factors: silicate mineral weathering and cation exchange, carbonate mineral weathering, and chemical fertilizers from farms in the area. All the groundwater clusters have low sodium content and will not pose the sodium hazard when used for irrigation. However, as a result of high permeability indices, all but one of the Cluster 2 members plot within the class III region of the Doneen’s chart and are therefore unsuitable for irrigation on these grounds. Clusters 3 and 4 members are the best water types, while Cluster 1 members are equally distributed between Classes II and III categories.

Experimental studies of Ta2O5 and columbite–tantalite solubility in fluoride solutions from 300 to 550°C and 50 to 100 MPa

It is well established that the fractionation of Li–F granitic magmas at depth leads to the accumulation of flux elements such as F and Li, and metal cations such as Ta and Nb in residual melts. However, it remains to be determined whether magmatic fractionation is sufficient to concentrate Nb and Ta into economically significant quantities, and what role hydrothermal–metasomatic processes play in the formation of such ore deposits. In the literature, reliable data about the solubility of Ta and Nb in hydrothermal solutions is missing or incomplete. This study provides a quantitative experimental estimation of the possible contribution from hydrothermal processes in Ta enrichment in cupolas of albitized and greisenized Li–F granite. Experimental studies of Ta2O5 and columbite–tantalite (Mn,Fe)(Nb,Ta)2O6 solubility were carried out in fluoride solutions consisting of HF, NaF, KF, and LiF. At low fluoride concentrations (0.01 and 0.1 m), Ta2O5 solubility at 550°C and 100 MPa under Co–CoO oxidizing conditions is low (near 10−5–10−4 m) in all fluoride solutions (HF, NaF, KF, LiF). At high fluoride concentrations (1 and 2 m) the highest Ta2O5 concentrations (10−1 m) were detected in HF solutions. In KF, NaF, and LiF solutions, the Ta2O5 solubility is also high (10−3–10−2 m). The dependence of columbite–tantalite (Nb2O5-59 wt. %, Ta2O5-18 wt. %) solubility as a function of solution composition, T, and P has also been investigated. Tantalum and Nb concentrations have the highest values in HF solutions at reduced conditions (up to 10−3 to 10−2 m Ta in 1 m HF). In 1 m NaF solutions, the concentrations of Nb and Ta are, respectively, 2.5 and 3 orders of magnitude less than those in the 1 m HF solutions. Solubility of Ta and Nb in KF solutions has intermediate values. It is established that in NaF and KF solutions the dependence of solubility on pressure is distinctly negative. The Nb and Ta contents increase with increasing concentrations of HF and KF in solution, however, they do not change with increasing NaF concentration. In NaHCO3, Na2CO3, and HCl solutions columbite–tantalite solubility is low. Even in 1 m chloride solutions the content is within the limits of 10−5 m for Nb and 10−6 to 10−8 m for Ta. We conclude that hydrothermal transport of Ta and Nb is possible only in concentrated fluoride solutions.

Monitoring of Fluoride in Groundwater Resources of Iran

Fluoride concentration in groundwater resources that used as the source of drinking water in urban areas of Iran was determined. All of the groundwater wells located in urban areas were monitored in 2008. Fluoride concentration of water samples was measured using SPADNS method. The nationwide mean fluoride concentration in the groundwater resources was found to be 0.47 +/- 0.28 (+/- standard deviation) mg/L. Only in Bushehr Province, the provincial mean fluoride level in the groundwater resources was higher than the WHO guideline value of 1.5 mg/L (1.86 +/- 0.86 mg/L). At nationwide level, the portion of extracted groundwater with fluoride concentration lower than the minimum permissible level of 0.5 mg/L, desirable fluoride range of 0.5-1.5 mg/L and elevated fluoride level was 69.2, 29.3 and 1.4%, respectively. In the areas with low fluoride content drinking water, it is recommended that fluoride is absorbed by use of high fluoride content foods and beverages. The recommendations for the circumstances with excessive fluoride content of drinking water are provision of drinking water from alternative sources and defluoridation of drinking water by point-of-use systems, respectively.

Residual aluminium in water defluoridated using activated alumina adsorption – Modeling and simulation studies

The removal of fluoride from drinking water by the method of adsorption on activated alumina is found superior than other defluoridation techniques mostly due to the strong affinity between aluminium and fluoride. Dissolution of aluminium from the alumina surfaces into its free and hydroxide ions in the aqueous medium is reported to be very low, but the presence of high fluoride concentrations may increase its solubility due to the formation of monomeric aluminium fluoride and aluminium hydroxyl fluoride complexes. An Activated Alumina Defluoridation Model Simulator (AAD) has been developed to represent fluoride adsorption on the basis of the surface complexation theory incorporating aspects of aluminium solubility in presence of high fluoride concentrations and pH variations. Model validations were carried out for residual aluminium concentrations in alumina treated water, by conducting a series of batch fluoride adsorption experiments using activated alumina (grade FB101) treating fluoride concentrations of 1–10 mg/L, at varying pH conditions. The total residual aluminium in the defluoridated water is due to presence of both dissolved and precipitated Al–F complexed forms. The Freundlich adsorption isotherm was found fit for fluoride adsorption capacity versus residual fluoride concentrations for pH = 7.5, and the relationship is given by the linearised equation log ( x/ m) = log k + (1/ n) log C e with values of k = 0.15 mg/g and 1/ n = 0.45 indicating favorable adsorption. The relationship is linear in the region of low fluoride concentrations, but as concentrations of fluoride increased, the formation of the dissolved AlF 3 0 complexes was favored than adsorption on alumina, and hence makes the isotherm nonlinear. The AAD simulations can predict for operating fluoride uptake capacity in order to keep the residual aluminium within permissible limits in the alumina treated water.

Bioassay and use in irrigation of untreated and treated wastewaters from phosphate fertilizer industry

Wastewater from phosphate fertilizer industry that contains essentially a significant amount of both fluoride and phosphate was treated by separative precipitation of fluoride ions with hydrated lime. Thus, a phosphate-rich effluent with low content of fluoride was obtained. The microtoxicity of the treated wastewater was then monitored by LUMIStox and its phytotoxicity was investigated on tomato ( Lycopersicon esculentum), wheat ( Triticum aestivum), maize ( Zea mays), ryegrass ( Lolium perenne), and alfalfa ( Medicago sativa) seed germination and plant growth. The cress ( Lepidium sativum) was used as a standard species for the germination index and phytotoxicity evaluation. Seedlings of four species (namely wheat, maize, ryegrass, and alfalfa) were grown in pots, which were irrigated with untreated wastewater, treated wastewater, aqueous solution of triple superphosphate fertilizer (TSP) or with tap water as control. LUMIStox tests showed that lime treatment allowed a significant toxicity removal. The treated water displayed beneficial fertilizing effect on plants. An increase in the germination index from 100% to 119% was observed. However, the untreated wastewater inhibited the species germination even when diluted 10 times. Neither plants mortality nor growth inhibition was observed after 90 days of treated wastewater application. Moreover, an improvement in plant growth, leaf number and a root development were noticed in these plants when compared with those irrigated with tap water or with fertilizer. In contrast, leaf necrosis and growth inhibition were observed in plants amended with raw wastewater. The irrigation with treated wastewater also improved soil labile P content. Indeed, soils amended with treated wastewater had more a double labile P concentration (38.15 mg kg −1) in comparison with control soil (15.53 mg kg −1).

Effects of synthesis conditions on dimensions, structure, and oxygen content of photocatalytically active titania nanotubes

In this study, we report a method for the formation and characterization of aligned arrays of amorphous titania nanotubes by anodic oxidation in thin titanium films on SiO2 substrates using fluoride-containing electrolytes. Trends in titania nanotube geometries as a function of synthesis conditions were established. A titania nanotube array surface area of approximately 178 m2/g is reported. The titania nanotubes transitioned to the rutile crystal structure when heated in air at 530 °C–705 °C. The degradation of methylene blue under UV light showed that lower fluoride concentrations in the synthesis electrolyte result in higher photocatalytic activity of the titania nanotubes. These results indicate that the synthesis conditions affect the oxygen content of amorphous nanotubes, which determines their physical and chemical properties.

Toward Self-Ordered Silica Nanotubes by Electrochemical Anodization of Si(100)

In the present work, we produce self-ordered silica nanostructures by anodization of p-type Si(100) wafers in dilute fluoride-containing organic electrolytes. The effects of water content, fluoride concentrations, and potential are investigated. In electrolytes containing sufficiently low water and fluoride concentrations, nanoporous and nanotubular structures can be formed. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that the structures consist of . Under optimized conditions, self-ordered nanotubular silica structures can be formed with individual tube diameters of .

Crystal Growth and Dissolution of Calcite in the Presence of Fluoride Ions: An Atomic Force Microscopy Study

Growth and dissolution of calcite {1014} surfaces in aqueous solutions in the presence of fluoride ions have been studied by in situ atomic force microscopy (AFM). Supersaturated and undersaturated solutions with respect to calcite were prepared for the growth and dissolution experiments, respectively. The concentration range of solutions containing fluoride ions varied between 0.025 and 50 mM. The crystal growth rates were measured from the step growth of closing of etch pits along the [010] direction as well as the spreading of two-dimensional growth nuclei in the same direction. Dissolution rates were measured from the time-dependent development of the rhombohedral etch pits along both [010] and [421] directions. Low fluoride concentrations (≤0.33 mM) in the supersaturated solutions did not significantly affect the crystal growth rates of calcite. At higher concentrations (up to 5 mM), the growth rate decreased substantially, reaching 50% of the respective rate in the absence of fluoride for the same...

Natural fluoride levels from public water supplies in Piauí State, Brazil

The aim of this work was to determine the natural fluoride concentrations in public water supplies in Piauí State, Brazil, in order to identify cities in risk for high prevalence of dental fluorosis. For each city, two samples of drinking water were collected in the urban area: one from the main public water supply and another from a public or residential tap from the same source. Fluoride analyses were carried out in duplicate using a specific ion electrode and TISAB II. From a total of 222 cities in Piauí, 164 (73.8%) samples were analyzed. Urban population in these towns corresponds to 92.5% of the whole state with an estimated population of 1,654,563 inhabitants from the total urban population (1,788,590 inhabitants). A total of 151 cities showed low fluoride levels (<0.30 mg/L) and 13 were just below optimum fluoride concentration in the drinking water (0.31-0.59 mg/L). High natural fluoride concentration above 0.81 mg/L was not observed in any of the surveyed cities. As a conclusion, most of the cities in Piauí have low fluoride concentration in the drinking water. The risk for a high prevalence of dental fluorosis in these urban areas due to natural fluoride in the water supplies is very unlikely. Thus, surveys about the dental fluorosis prevalence in Piauí should be related with data about the consumption of fluoridated dentifrices and other fluoride sources.