Fluoridation Research Articles

Picking a bone with fluoride – dose-response meta-analysis on exposure to fluoride and bone density

Abstract There are still uncertainties around the effects, beneficial and adverse, of water fluoride exposure on bone density and strength. We selected bone mineral density (BMD) for investigation as it is recognized as the major non-invasive indicator of bone strength, representing its clinical assessment standard. The aim of this systematic review and meta-analysis was to characterize for the first time the relation between fluoride exposure and BMD through a dose-response approach, using a one-stage dose-response meta-analysis based on a cubic spline random-effects model. Out of 1201 potentially relevant literature records retrieved, after removing duplicates, title/abstract screening, and full-text evaluation, 16 studies were eligible for this review, 12 of which were also suitable for the dose-response meta-analysis. We observed an almost linear association between fluoride and BMD, yielding a mean difference of 2.60 (95% CI 0.17 to 0.40) at 4 mg/L of fluoride exposure. This pattern was also confirmed for hip BMD (MD = 2.83; 95% CI 0.11 to 0.40 at 4 mg/L). However, sex-specific analyses showed different patterns of association. In males, the relation between fluoride exposure and BMD was almost linear until 0.75 mg/L (MD = 0.24; 95% CI -0.22to 0.37), after which it plateaued. Females showed a slight increased BMD at 1 mg/L (MD = 0.05; 95% CI -0.02 to 0.16) but decreasing values above 2.5 mg/L (MD=-0.22; 95% CI -2.72 to 2.38 at 4 mg/L), with an indication of an inverted U-shaped association. This pattern was clearer when we restricted our analysis to hip BMD (MD=-0.56; 95% CI -2.98 to 1.85 at 4 mg/L). Sensitivity analyses examining both bone-specific BMD and conducting risk of bias assessments are currently underway. Moreover, imprecision of the estimates, especially in stratified analyses, and potential for residual confounding, underscore the need for further prospective studies, to more adequately assess the relation between fluoride exposure and bone density and strength. Key messages • At fluoride exposure below 1 mg/L, we observed a linear correlation between fluoride exposure and increase bone density in the overall pooled dose-response analysis of eligible studies. • Sex-specific patterns: males show positive response until certain exposure threshold; while females demonstrate an increase only at low doses of exposure and a downward trend at higher exposures.

Impact of dental fluorosis on the oral health-related quality of life: a systematic review.

The aim of this systematic review is to investigate the literature to assess the effect of dental fluorosis on the Oral Health-Related Quality of Life (OHRQoL). Included studies were epidemiological investigations, clinical trials, or human studies that directly compared the impact on OHRQoL between individuals with dental fluorosis and those without, utilizing valid OHRQoL assessment tools. The searches were conducted up to March 2024 in databases, including PubMed, Scielo, LILACS, Scopus, Web of Science, Embase, and the Virtual Health Library. Additionally, gray literature sources such as Google Scholar, OpenGrey, Ibict/BDTD, and ProQuest were searched. Reference lists were also manually reviewed for potential eligible studies. The risk of bias in cohort studies was assessed using the Newcastle-Ottawa Scale (NOS), while its modified version was employed for cross-sectional studies. A narrative synthesis of the results was conducted. 16 studies were included in this Systematic Review. In total, 16,314 participants, aged 8 to 18, were assessed across the studies. Most of the included studies were cross-sectional, except for one cohort study. In assessing OHRQoL across different age groups and severities of dental fluorosis, the impact varied. A negative association between dental fluorosis and OHRQoL was found in 9 of the included studies, a positive association was found in 1 study, and no significative association was identified in 6 studies. Limitations in the included studies primarily pertained to cross-sectional designs, with significant issues such as the absence of sample size calculations, lack of non-response rate reporting, limited consideration of confounding factors, and substantial heterogeneity stemming from diverse diagnostic methods and assessment tools. The findings of the systematic review demonstrate a complex and varied relationship between dental fluorosis and OHRQoL in children and adolescents. These conclusions may have limitations in scientific evidence. The findings emphasize the need for further investigations to explore the intricate aspects of this relationship and identify contributing factors to varying outcomes. Dental caries preventive fluoridated measures might be indicated even if there would be a risk for mild dental fluorosis as the fluoridated public water. This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under number: CRD42020186552.

Performance evaluation on recycling metals from lithium cobaltate by supercritical water combining with leaching-precipitation methods

The recycling of metals from spent lithium-ion batteries is currently a hotspot of research. This paper introduces a novel recovery method that integrates supercritical water and leaching-precipitation techniques to efficiently extract metals from lithium cobaltate electrodes. This study investigates the dissolution behavior of lithium cobaltate in supercritical water, and the interaction between lithium cobaltate and organic impurity (Polyvinylidene Fluoride and N-methylpyrrolidone) during the supercritical water treatment process. Lithium cobaltate reacts with supercritical water to form cobaltous hydroxide and reacts with polyvinylidene fluoride to form cobalt oxide. During the reaction of supercritical water with polyvinylidene fluoride and N-methylpyrrolidone in supercritical water, lithium cobaltate is reduced to cobalt oxide. The addition of N-methylpyrrolidone promotes the reduction of cobalt ion and the decomposition of polyvinylidene fluoride. Subsequently, the cathode materials treated with supercritical water are leached by using hydrochloric acid and sulfuric acid respectively. Cobalt and lithium ions in the leaching solution are precipitated by adding sodium hydroxide and sodium carbonate. The maximum recovery efficiencies of lithium and cobalt are 73 % and 79.60 %, respectively.

Associations between Dietary Patterns, Fluoride Intake and Excretion in Women Exposed to Fluoridated Salt: A Preliminary Study

Abundant information exists on fluoride intake and excretion in populations exposed to fluoridated water, but not fluoridated salt, where fluoride is eaten through a combination of foods and beverages. This study assessed associations between dietary patterns, fluoride intake and excretion in Mexican women exposed to fluoridated salt. We estimated dietary fluoride intake and excretion (mg/day) from 31 women using 24-h recalls (ASA24) and 24-h urine collections (HDMS diffusion method) and assessed agreement among both estimates of exposure with a Bland-Altman plot. Dietary patterns among the sample were explored by Principal Component Analysis and associations between these patterns and both fluoride intake and excretion were estimated. using Quantile Regressions. Median dietary fluoride intake and excretion were 0.95 and 0.90 mg/day, respectively, with better agreement at values below 1.5 mg/day. We identified three dietary patterns: “Urban Convenience”, “Plant-based” and “Egg-based”. The “Urban Convenience” pattern, characterized by dairy and convenience foods was associated with an increase of 0.25 mg and 0.34 mg of F in the 25th and 50th percentiles of intake respectively, (p < 0.01), and a marginal 0.22 mg decrease in urinary fluoride (p = 0.06). In conclusion, in this sample of Mexican women, a dietary pattern rich in dairy and convenience foods, was associated with both fluoride intake and excretion.

Unraveling the impact of high arsenic, fluoride and microbial population in community tubewell water around coal mines in a semiarid region: Insight from health hazards, and geographic information systems

High arsenic (As), fluoride (F-), and microbial pathogens coexist in semiarid conditions afflicting > 240 million people worldwide including Pakistan. Groundwater quality has declined due to geogenic and manmade activities providing suitable ground for ubiquity, bioavailability, and toxicity of contaminants. We tested the health hazard, distribution, and apportionment of As, F-, and microbes in groundwater around coal mines in Quetta, Pakistan. The range of As, and F- concentrations in groundwater were 0.2–16.6 µg/L, 0.4–18.5 mg/L. Both, As and F- correlate with high HCO3-, pH, Na+, SO42-, Fe, and Mn, and negatively with Ca2+ water. The coalfield showed many folds higher As 15.8–28.5 µg/L, and F- 10.8–34.5 mg/L compared to groundwater-wells. Geochemical phases revealed saturation of groundwater with calcite, dolomite, fluorite, gypsum, and undersaturation with halite-mirabilite, and arsenopyrite minerals. The positive matrix factorization (PMF) model assessed five-factor solutions: geogenic, industrial, coal mining, sulfide & fluoride-bearing mineral-dissolution, and agriculture pollution delivered As, F-, and microbial contamination. About 24.6 % and 64.4 % of groundwater samples exceeded the WHO guidelines of As 10 µg/L, F- 1.5 mg/L. The carcinogenicity, and non-carcinogenicity of As, and F- were higher in children than adults. Therefore, health hazards in children are of great concern in achieving sustainable management goals.

Hydro-geochemistry and age-dependent health risk assessment of nitrate, nitrite, and fluoride in health facilities water: a multivariate analysis.

Groundwater from alluvial fan plains is the prevailing water source, especially for arid/semiarid regions, but its contamination poses substantial risks to water supply and public health. The recent study aims to assess the hydro-geochemistry, distribution, and potential health risks of NO3-, NO2-, and F- concentrations in the groundwater of previously unexplored health facilities in District Vehari, Punjab, Pakistan. In total, 75 groundwater samples were evaluated for NO3-, NO2-, and F- levels as well as pH, EC, TDS, CO32-, HCO3-, Cl-, Na+, Fe, K+, Ca2+, Mg2+, taste, odor, color, and turbidity. The Durav graph shows that the water type is Na-HCO3-Ca, with Na and HCO3 dominant, weak acids > strong acids, and alkaline ions > alkalis. Results revealed that drinking water samples (21.73% and 20%) taken from Tehsil Mailsi, and the Basic Health Unit (BHU) exceeded the WHO standard (1.5mg/L) for F- concentration, respectively. Moreover, the mean chronic daily intake (CDI) of F- was 0.044, 0.018, and 0.02mg/kg/day in children, men, and women, respectively. Similarly, the average CDI of NO3- was 0.113, 0.046, and 0.050 in children, men, and women, respectively, and the respective values of NO2- were 0.004, 0.001, and 0.001. The NO2- shows a significant range of hazard quotient (HQ) (0.0-1.172) in children. The range of HQ for F- was 0.0-3.114, 0.0-1.290, and 0.0-1.389 in children, men, and women, respectively. Additionally, the health risks analysis revealed an HQ > 1.0 for children in groundwater, indicating a potential carcinogenic risk from the F-. Pearson correlation and PCA analysis found a significant positive correlation (0.8) between NO3- and NO2- and a negative correlation (0.3) between F- and HCO3-. These findings highlight the need for groundwater treatment in healthcare facilities prior to water consumption. Enforcing international and national drinking water standards in healthcare units is vital to strengthening services and providing equitable access to safe drinking water. Legislative and efficient water management measures must be taken for the protection of public health.

Association of fluoride exposure with disease burden and neurodevelopment outcomes in children in South Korea.

Community water fluoridation is an effective public health strategy for preventing dental caries, yet. Concerns exist about potential health problems. This study explores associations between tap water fluoride levels and pediatric disease burden, as well as neurodevelopmental outcomes at 6years of age. This nationwide population-based cohort study included children born in Korean cities with and without tap water fluoridation projects, between 2006 and 2012, aiming for a fluoride concentration of 0.8 ± 0.2mg/L in treated tap water. Data from the National Health Insurance Service were used, spanning from birth to 2018. The relationship between exposure to fluoridated tap water and incidence of 16 childhood diseases that were previously identified as potentially linked to fluoride exposure were examined. Additionally, we evaluated the neurodevelopmental outcomes across various domains, including gross motor, fine motor, cognition, language, social skills, and self-help functions. These assessments were performed using data from a comprehensive national health screening program for children aged six years. A fluoride-unexposed group included 22,881 children, whereas a fluoride-exposed group comprised 29,991 children (52% males). Children in the fluoride-exposed group had a decreased risk of dental caries and bone fractures [hazard ratio (95% confidence interval, CI), 0.76 (0.63-0.93) and 0.89 (0.82-0.93), respectively] and increased risk of hepatic failures [1.85, (1.14-2.98)] compared to those in the unexposed group. Additionally, the risk ratio of abnormal neurodevelopmental screening outcomes increased by 9%, but this was statistically uncertain (95% CI, 0.95-1.26). Fluoridated tap water was associated with an increased risk of hepatic failure but a decreased risk of bone fractures in children. The association between fluoridated tap water and neurodevelopmental screening outcomes at 6years remains unclear, highlighting the need for further studies to clarify this association.

What’s in the water? Long-run effects of fluoridation on health and economic self-sufficiency

Community water fluoridation has been named one of the 10 greatest public health achievements of the 20th century for its role in improving dental health. Fluoride has large negative effects at high doses, clear benefits at low levels, and an unclear optimal dosage level. I leverage county-level variation in the timing of fluoride adoption, combined with restricted U.S. Census data that link over 29 million individuals to their county of birth, to estimate the causal effects of childhood fluoride exposure. Children exposed to community water fluoridation from age zero to five are worse off as adults on indices of economic self-sufficiency (−1.9% of a SD) and physical ability and health (−1.2% of a SD). They are also significantly less likely to graduate high school (−1.5 percentage points) or serve in the military (−1.0 percentage points). These findings challenge existing conclusions about safe levels of fluoride exposure.

Tap water filtration and purification usage and their impact on the concentrations of fluoride and other minerals – A community-based study

ObjectiveThis study investigated the prevalence of water filtration and purification system (WFPS) use among residents of central Indiana (USA) and determined the effects of WFPS on the concentrations of fluoride, calcium, magnesium, potassium, and sodium in tap water. MethodsA census-based questionnaire collected data on demographics, water use, and water sources. Participants were also asked to provide water samples from their tap water or the WFPS they used. Water samples were analyzed using ion-specific electrodes (fluoride) and atomic absorption spectrometry (metals). Mineral concentration comparisons between water sources used nonparametric tests; questionnaire associations were testing using correlations, chi-square tests, and nonparametric tests. ResultsOne hundred and one participants completed the study, of which 71 % used some type of WFPS. Blacks were less likely to use WFPS than Asian or White participants (p = 0.045). Those with bachelor's degrees or higher were more likely to use WFPS (p = 0.003). The most used WFPS were pitcher filters (31 %), water softeners (21 %), reverse osmosis systems (11 %), faucet-mounted filters (4 %), and whole-house carbon filters (1 %). Reverse osmosis systems resulted in the lowest mineral concentrations (median, ppm; F-0.08, Ca-2.30, Mg-0.46, Na-4.60, P-0.35). Pitcher filters were largely comparable to unfiltered tap water. Water softeners resulted in the highest sodium concentrations (78.40 ppm). ConclusionA large proportion of study participants use WFPS, with pitcher filters being the most common. Reverse osmosis systems had the most significant impact on reducing mineral levels in tap water, while pitcher filters do not adversely affect mineral concentrations. Clinical SignificanceUnderstanding how different WFPS affect the various minerals in tap water is essential for helping consumers in choosing the right system and for oral care providers to guide patients on water consumption and the need for fluoride supplementation, especially for those at high risk of dental caries.

Utilization of organic waste from Chinar leaves as sustainable and eco-friendly adsorbent for fluoride removal.

Due to concerns about high water fluoride concentrations and their detrimental consequences on health, particularly dental and skeletal fluorosis, dependable and cost-effective defluoridation techniques are needed. Chinar leaves (Platanus orientalis), a common waste, might be utilized for the production of activated carbon. For Chinar leaf activated carbon (CLAC) manufacturing, two pre-pyrolysis chemical modification procedures were used: acidic HCl (H-activation) and alkaline NaOH (OH-activation). The success of fluoride removal suggests further research and implementation in locations with fluoride-related water quality issues. This study examines how CLAC dosage, fluoride concentration, temperature, pH, and contact exposure effect defluoridation efficiency. The pseudo-second-order non-linear kinetic model and Freundlich non-linear isotherm model with R2 = 0.99 fit the data, resulting in a peak adsorption capacity of 30.3mg/g for 0.3g CLAC. In the present work, the adsorption mechanism was regulated by more than intraparticle diffusion. Adsorption occurred spontaneously as exothermic monolayer chemisorption, according to thermodynamic studies. Adsorbent activated with HCl (H-activated) showed promising results, with 73% F- removal efficiency for OH-activated and 91% for H-activated CLAC.

Effects of community water fluoridation on child dental caries in remote Northern Territory, Australia: a difference-in-difference analysis.

Community water fluoridation (CWF) is a cost-effective intervention to reduce dental caries at population level. This Australian study used a difference-in-difference (DiD) analysis to measure dental caries in children exposed to CWF in the Northern Territory (NT), Australia. Oral health data obtained from the NT Department of Health contained 64 399 person-year observations from 2008 to 2020, totalling 24 546 children aged 1-17 years. Drinking water quality data for fluoride levels, held by the Power and Water Corporation, were obtained for 50 remote communities and linked to the oral health dataset. The DiD analysis used a treatment group and two control groups to compare the effects of CWF on dental caries outcomes in children, measured using the decayed, missing and filled teeth (dmft/DMFT) index. The treatment group consisted of records from children residing in five remote NT communities that implemented CWF in 2014.The control 1 group included records of children residing in communities with naturally occurring fluoride in drinking water supplies at levels at or above the Department of Health policy threshold of 0.5 mg/L. The control 2 group included records of children residing in communities with naturally occurring fluoride in drinking water supplies below the level recommended by the Department of Health policy (<0.5 mg/L). The data were grouped into time periods prior to the inception of CWF in five remote communities in 2014 (pre-intervention) and after 2014 (post-intervention). Our results demonstrated that dental caries was significantly decreased for children in the treatment group following the implementation of CWF at a greater magnitude than both control groups for the same time period. Overall, children assigned to the treatment group exhibited a decline in the number of teeth affected by caries by an average of 0.28 (p=0.001). Notably, children of ages 7-10 years and 11-17 years experienced significantly greater post-intervention declines in average dmft/DMFT, by 0.32 (p=0.051) and 0.40 (p=0.012) fewer affected teeth respectively. While dental caries disproportionately impacts Aboriginal children in remote and very remote NT, it is clear that CWF produces population-level reductions in overall dental caries for these populations. Additionally, our study demonstrates the application of the DiD method in a public health policy evaluation. Our findings suggest that the longstanding policy position of the NT Department of Health on CWF has supported improvements in oral health among child populations that experience high levels of dental caries in remote NT communities.

Tooth loss from the perspective of studies employing a life course approach: a systematic review.

The life course approach scrutinizes factors that shape the development of diseases over time. Tooth loss, which is influenced by social, behavioral and biological factors, can occur at various stages of life and tends to become more prevalent in later years. This systematic review examined the influence of socioeconomic, psychosocial, biological and behavioral adversities in life on the likelihood of tooth loss. Searches were conducted in the Embase, PubMed, Web of Science, Ovid, PsycINFO, Scopus and LILACS databases. Reference management was performed using EndNote online. The risk of bias was appraised using the Newcastle-Ottawa Scale (NOS). The electronic searches yielded 1366 records, 17 of which (13 cohort and four cross-sectional studies) met the inclusion criteria. According to the NOS, all studies had a low risk of bias. Two studies found a link between a lower education and higher incidence of tooth loss and socioeconomic status exerted a significant influence in 47% of the studies. Disadvantaged socioeconomic trajectories and health-related factors, such as smoking, general health perception and oral health behaviors, increased the likelihood of tooth loss. Factors such as dental visits, a history of toothache and exposure to fluoridated water influenced the likelihood of tooth loss. Individuals who experienced adversities in socioeconomic, behavioral and biological aspects throughout their life course were more prone to tooth loss.

Electrodialysis reversal (EDR) technology: a viable solution for addressing water quality challenges in the dry zone, Sri Lanka

ABSTRACT Chronic Kidney Disease of Unknown Etiology (CKDu) affects rural Sri Lankan agricultural populations, with poor-quality ground and surface water suspected as the root cause. Hence, we conducted this study to explore the effectiveness of Electrodialysis Reversal (EDR) technology in treating water quality issues related to CKDu in dry zone of Sri Lanka. The EDR plant in Kahatagasdigiliya, Anuradhapura district, managed by the National Water Supply and Drainage Board (NWS&amp;DB) was selected. We measured both physical (colour, turbidity, pH) and chemical (electrical conductivity, total dissolved solids, chloride, alkalinity, hardness, nitrate, nitrite, sulfate, fluoride, total phosphate, iron, manganese) parameters of the EDR process. The parameters of the permeate stage of the EDR plant were validated by comparison with data from SLS 614:2013, and removal efficiencies were assessed. The results revealed that all parameters consistently fell within the permissible limits in the permeate stage of the EDR plant. Turbidity (62.65%), sulfate and manganese (50%), colour (47.37%), fluoride (44.19%), and hardness (35.71%) showed high removal efficiencies in the EDR process. The study demonstrated the effectiveness of EDR technology in addressing water quality challenges, validating its potential for groundwater treatment and this contributes to the improvement of groundwater quality in CKDu-prevalent areas.

Fluoride Removal from Aqueous Solutions by Using Super-Adsorbents of Chitosan/Orange Peels/Activated Carbon@MgO: Synthesis, Characterization, and Adsorption Evaluation

Exposure to excessive concentrations of fluoride in potable water is harmful to human health; therefore, its limitation is deemed necessary. Among the commonly applied technologies, adsorption is selected, as it is a highly effective, simple, and economically efficient treatment. In the present study, several combinations of chitosan (CS), orange peels (OP), activated carbon (AC), and MgO were synthesized and tested as adsorbents in order to find the most effective derivative for fluoride extraction. The impact of the adsorbent dosage, pH level, contact time, and initial concentration was investigated to assess the feasibility of the chitosan/orange peels/activated carbon@MgO composite. According to the results, the modification of chitosan with AC, OP, and MgO in a unique adsorbent (CS/OP/AC@MgO), especially in acidic conditions (pH 3.0 ± 0.1) by using 1.0 g/L of the adsorbent, demonstrated the highest efficiency in F removal, up to 97%. The pseudo-second (PSO) order model and Langmuir isotherm model fit better to the experimental results, especially for CS/OP/AC@MgO, providing a Qm = 26.92 mg/g. Thermodynamic analysis confirmed the spontaneous nature of the adsorption process. The structure and morphology of the modified OP/CS@AC-Mg were extensively characterized using BET, XRD, FTIR, and SEM techniques.

The effect of cessation of drinking water fluoridation on dental restorations and crowns in children aged 3–5 years in Israel – a retrospective study

BackgroundCommunity water fluoridation began in the 1945 as a public health measure to prevent and control caries and was implemented in Israel in 1981. Community water fluoridation reduced caries significantly, but in 2014, the Ministry of Health decided to stop Community water fluoridation in Israel. The aim of our study was to examine the effect of fluoridation cessation on the dental health of children aged 3–5, treated in “Assuta Tel Aviv” dental clinics, under general anesthesia or deep sedation.MethodsThe computerized Maccabi-Dent database provided data for this retrospective study. Records from the years 2014–2019 including treatment codes for procedures relevant to the study, the number of stainless-steel crowns and restorations of all types were examined. Kruskal-Wallis test was performed to compare the results from before and after fluoridation cessation.ResultsA statistically significant increase in the mean number of treatments in the years after fluoridation cessation (P < 0.05) was found. There was approximately a two-fold increase in the number of all treatments for all ages.ConclusionThe results of the study emphasize the advantages of water fluoridation and are further proof of the need to restore community water fluoridation in Israel.

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Fluoride Exposure from Drinking Water Increases the Risk of Stroke: An Ecological Study in Changwu Town, China.

Stroke is a major cause of death globally and the leading cause in China. Excessive fluoride exposure has been linked to cardiovascular conditions related to stroke risk factors such as hypertension, atherosclerosis, dyslipidemia, and cardiomyopathy. However, evidence supporting the association between fluoride exposure and stroke risk is limited. We constructed an ecological study in Changwu Town, Heilongjiang Province, China, a typical endemic fluorosis area caused by excessive fluoride exposure from drinking water. We collected demographic data, stroke prevalence, and mortality information from 2017 to 2021. Fluoride exposure data were obtained from the national monitoring project on endemic fluorosis. Water fluoride concentrations were measured using the standardized methods. Trend changes in stroke rates were assessed using annual percentage change (APC). Differences in stroke rates among fluoride exposure groups were analyzed using chi-square tests. From 2017 to 2021, the all-ages and age-standardized stroke prevalence rates of permanent residents in Changwu Town increased year by year, while the all-ages and age-standardized mortality rates did not change significantly. The prevalence rates of stroke were significantly higher in endemic fluorosis areas compared to non-endemic areas (p < 0.001). Stratifying the population into tertile groups based on the water fluoride cumulative exposure index (WFCEI) revealed statistically significant differences in stroke prevalence rates (p < 0.001), showing a dose-response relationship with the WFCEI. However, the all-ages and age-standardized mortality rates of stroke were not found to be related to fluoride exposure. Long-term excessive fluoride exposure from drinking water may increase the risk of stroke prevalence, indicating fluoride overexposure as a potential risk factor for stroke.

An inverse relationship between dental fluorosis and Molar Incisor Hypomineralization in Mexican schoolchildren in an area with a high concentration of fluoride in drinking water: A cross-sectional study.

To evaluate the association between the frequency and severity of dental fluorosis and Molar Incisor Hypomineralization (MIH) in 8-12-year-old schoolchildren living in an area with a high concentration of fluoride in the drinking water. The present cross‑sectional study was conducted on Mexican children (n = 573) selected from one community presenting a drinking water fluoride concentration of 1.39 ppm/F. The prevalence of dental fluorosis was ascertained using the Thylstrup and Fejerskov Index (TFI). The presence and severity of MIH was evaluated using the European Academy of Pediatric Dentistry (EAPD) criteria. A multinomial regression model was used to estimate the odds ratio (OR) and the 95% confidence intervals (CI), using the severity of MIH as the result. The prevalence of MIH was 37.7% and, by severity, was 16.1% mild, 14.3% moderate, and 7.3% severe. The prevalence of dental fluorosis in permanent dentition was 70.9% (TFI ≥1) and, by severity, was 29.2% (TFI = 0), 45.6% (TFI 1-3) and 25.3% (TFI ≥4), while 54.5% of subjects were found to have poor oral hygiene. Schoolchildren with fluorosis (TFI ≥4) were 49% less likely [OR = 0.51; p = 0.025] to present mild MIH than children with fluorosis (TFI <4). Similarly, children with fluorosis (TFI ≥4) were 53% [OR = 0.47; p = 0.019] and 62% [OR = 0.38; p = 0.036] less likely to present moderate and severe MIH than children with fluorosis (TFI <4). An inverse relationship between the presence of fluorosis and MIH was found. The results obtained by the present study may contribute to both the early identification of disorders affecting the enamel and the creation and implementation of long-term oral health prevention, promotion, and intervention programs in the affected population.

Efficient and simultaneous immobilization of fluoride and lead in water and tea garden soil by bayberry tannin foam loaded zirconium

Nowadays, human activities intensified the combined pollution of fluoride and lead in acidic tea garden soil. The key to eliminating this combined pollution is to immobilize pollutants simultaneously, thus preventing their migration from tea garden soil to tea trees. In this paper, the natural product bayberry tannin was employed as raw material to fabricate functional materials (TF-Zr) for simultaneous adsorption of fluorine (F) and lead (Pb) in water and soil by the reactivity of tannin with Pb2+ and the affinity of Zr with F. SEM-Mapping, EDS, FT-IR, XPS were utilized to probe the immobilization mechanisms. The results showed that TF-Zr could simultaneously and efficiently adsorb F– and Pb2+ from water with the adsorption capacity of 5.02 mg/g (Pb) and 4.55 mg/g (F). The adsorption processes were both in accordance with the proposed secondary kinetic adsorption model. Besides, the presence of F– promoted the adsorption of Pb2+ by TF-Zr. The materials were applied into tea garden soil to explore its effect on the variation of F and Pb forms in the soil. It was found that the proportion of water-soluble fluorine, exchangeable fluorine and exchangeable lead in the tea garden soil decreased significantly, while the proportion of residual fluorine and lead increased evidently, illustrating TF-Zr possessed eximious fixation effect on the highly reactive fluorine and lead in the soil and facilitated their conversion to the more stable residue state. Therefore, TF-Zr can be used for the efficient and simultaneous immobilization of fluorine and lead in water and tea garden soil.

Gut microbiome and function are altered for individuals living in high fluoride concentration areas in Pakistan

BackgroundEndemic fluorosis refers to the condition when individuals are exposed to excessive amounts of fluoride ion due to living in a region characterized by elevated levels of fluorine in the drinking water, food, and/or air. In Pakistan, a substantial proportion of the population is thereby affected, posing a public health concern. ObjectivesAssessing how the gut microbiota and its metabolic profiles are impacted by chronic exposure to fluoride in drinking water (that caused Dental Fluorosis) as well as to perceive how this microbiota is connected to adverse health outcomes prevailing with fluoride exposure. MethodsDrinking water (n=27) and biological samples (n=100) of blood, urine and feces were collected from 70 high fluoride exposed (with Dental Fluorosis) and 30 healthy control (without Dental Fluorosis) subjects. Water and urinary fluoride concentrations were determined. Serum/plasma biochemical testing was performed. Fecal DNA extraction, 16S rRNA analysis of microbial taxa, their predicted metabolic function and fecal short chain fatty acids (SCFAs) quantification were carried out. ResultsThe study revealed that microbiota taxonomic shifts and their metabolic characterization had been linked to certain host clinical parameters under the chronic fluoride exposure. Some sets of genera showed strong specificity to water and urine fluoride concentrations, Relative Fat Mass index and SCFAs. The SCFAs response in fluoride-exposed samples was observed to be correlated with bacterial taxa that could contribute to adverse health effects. ConclusionsMicrobial dysbiosis as a result of endemic fluorosis exhibits a structure that is associated with risk of metabolic deregulation and is implicated in various diseases. Our results may form the development of novel interventions and may have utility in diagnosis and monitoring.