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.

AIM: 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. METHODS: The present cross­sectional 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. RESULTS: 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). CONCLUSION: 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.

[Development of the capacity to communicate risks related to childhood exposure to fluorides through an online educational strategy]. / Desarrollo de la capacidad de comunicar riesgos relacionados con la exposición infantil a fluoruros, a través de una estrategia educativa en línea.

Fluorides are contaminants that occur frequently and, generally, naturally in groundwater, affecting countries that depend on these waters for irrigation and human consumption. Chronic exposure to fluorides generates various health effects; therefore, this research was based on education and risk communication to contribute to the resolution of the problem of fluoride exposure in the population. The objective was to develop the capacity to design risk communication programs for personnel involved in the response and management of environmental health risks, with emphasis on fluoride exposure. An online pilot training course on risk communication and fluoride exposure was designed and implemented. For the analysis of the risk perception and knowledge of the participants, before and after the course, a questionnaire was applied and a focus group was conducted. In addition, the participants carried out a series of activities and designed a risk communication program to assess the degree to which the capacity to develop risk communication programs was achieved. To improve the pilot course, two satisfaction surveys were designed and implemented, and a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis was conducted. The results showed an increase in the level of knowledge and changes in the participants' perception; regarding the ability to design risk communication programs, two participants were able to design them excellently. Previous experience, motivation, commitment to learn and the feedback provided during the course influenced the development of this ability.

Los fluoruros son contaminantes presentes con frecuencia y generalmente de forma natural en aguas subterráneas, y afectan a países que dependen de estas aguas para el riego y el consumo humano. La exposición crónica a fluoruros genera diversos efectos a la salud; por lo anterior, esta investigación se basó en la educación y la comunicación de riesgos para contribuir a la resolución del problema de exposición a fluoruros en la población. El objetivo fue desarrollar la capacidad de diseñar programas de comunicación de riesgos del personal involucrado en la respuesta y manejo de los riesgos ambientales para la salud, con énfasis en la exposición a fluoruros. Se diseñó e implementó un curso piloto de formación en línea sobre comunicación de riesgos y exposición a fluoruros. Para el análisis de la percepción de riesgos y conocimientos de los participantes, antes y después del curso, se aplicó un cuestionario y se llevó a cabo un grupo focal. Además, los asistentes realizaron una serie de actividades y diseñaron un programa de comunicación de riesgos con el que se valoró el grado en que se alcanzó la capacidad de desarrollar programas de comunicación de riesgos. Para mejorar el curso piloto se diseñaron y aplicaron dos encuestas de satisfacción y se realizó un análisis FODA (Fortalezas, Oportunidades, Debilidades, Amenazas). Los resultados mostraron un incremento en el nivel de conocimientos y cambios en la percepción de los participantes; en cuanto a la capacidad de diseñar programas de comunicación de riesgos, dos participantes lograron diseñarlo de manera excelente. La experiencia previa, la motivación, el compromiso para aprender y la retroalimentación brindada durante el curso, influyeron en el desarrollo de esta capacidad.

Os fluoretos são contaminantes que ocorrem com frequência e, geralmente, de forma natural nas águas subterrâneas, afetando os países que dependem dessas águas para irrigação e consumo humano. A exposição crônica aos fluoretos gera vários efeitos à saúde; portanto, esta pesquisa baseou-se na educação e na comunicação de riscos para contribuir com a solução do problema da exposição ao fluoreto na população. O objetivo foi desenvolver a capacidade de elaborar programas de comunicação de risco para o pessoal envolvido na resposta e no gerenciamento de riscos ambientais à saúde, com ênfase na exposição à fluoretos. Foi elaborado e implementado um curso piloto de treinamento online sobre comunicação de riscos e exposição. Para a análise da percepção de risco e do conhecimento dos participantes antes e depois do curso, foi aplicado um questionário e aplicado um grupo de foco. Além disso, os participantes realizaram uma série de atividades e elaboraram um programa de comunicação de riscos para avaliar até que ponto a capacidade de desenvolver programas de comunicação de riscos foi alcançada. Para aprimorar o curso piloto, foram duas pesquisas de satisfação foram desenvolvidas e implementadas e uma análise FOFA (Forças, Oportunidades, Fraquezas e Ameaças) foi aplicada. Os resultados mostraram um aumento no nível de conhecimento e mudanças nas percepções dos participantes; em termos da capacidade de elaborar programas de comunicação de riscos, dois participantes conseguiram elaborar excelentes programas de comunicação de riscos. A experiência prévia, a motivação, o compromisso com o aprendizado e o feedback fornecido durante o curso influenciaram o desenvolvimento dessa capacidade.

Association between fluoride intake from drinking water and severity of dental fluorosis in Northern and Western Mexico: systematic review and meta-analysis.

BACKGROUND: Dental fluorosis (DF) is caused by excessive exposure to fluoride during odontogenesis and leads to various changes in the development of tooth enamel. Some regions in Mexico are considered endemic fluorosis zones due to the high fluoride content in drinking water. The objective of this study was to perform a systematic review and meta-analysis to identify the association between the concentration of fluoride in drinking water and the severity of dental fluorosis in northern and western Mexico. METHODS: This protocol was registered in the PROSPERO database (ID: CRD42023401519). The search for information was carried out in the PubMed/Medline, Scopus, SpringerLink, and Google Scholar databases between January 2015 and October 2023. The overall relative risk was calculated using the inverse of variance approach with the random effects method. The RoB 2.0 tool was used to construct risk plots. RESULTS: Eleven articles were analyzed qualitatively, and most of the included studies presented at least one level of DF severity; six articles were analyzed quantitatively, dividing them into two regions. In North region it was observed a higher prevalence of severe TF cases, corresponding to ≥ TF 5 category (4.78) [3.55, 6.42]. In the West region, most of the included studies presented a higher prevalence of less severe cases, corresponding to ≤ TF 4, in comparison with the North region (0.01) [0.00, 0.52], interpreted as a protective effect. CONCLUSION: The concentrations of fluorides in drinking water are reportedly high in these regions and are directly related to the severity of dental fluorosis experienced by the inhabitants. In the Northern region exists a major concentration of fluoride in drinking water compared with the Western region as well as a prevalence of higher severity cases of dental fluorosis.

Is there any association between fluoride exposure and thyroid function modulation? A systematic review.

Numerous pre-clinical and observational studies have explored the potential effects of fluoride (F) at varying concentrations on diverse systems and organs. While some have assessed the endocrinological conditions of children and adults, a consensus regarding the interaction between F and the thyroid remains elusive. This systematic review aimed to gather primary evidence on the association between F and changes in the thyroid at optimal and high levels in water supply as stipulated by the World Health Organization. A search strategy, incorporating terms pertinent to the studies, was employed across PubMed, Scopus, Web of Science, Lilacs, and Google Scholar. Following the review of studies, data were extracted and analyzed using the Grading of Recommendations, Assessment, Development, and Evaluations to assess the quality of the evidence. Our results yielded 3,568 studies, of which seven met the inclusion criteria for this review. Five of the seven studies identified an association between high F exposure and thyroid function. In the analysis of methodological quality, every study was found to have major or minor methodological issues and significant risk of bias. The overall confidence in the evidence was deemed low for all outcomes in the seven studies. The evidence compiled in this review suggests a potential association between chronic high levels of F exposure and thyroid damage. Nonetheless, further studies with robust design and high methodological quality are required to provide evidence for policy makers and health care practitioners.

Susceptibility of fluorotic enamel to dental erosion-abrasion.

Dental hard tissue conditions can be of pre- or post-eruptive nature, such as enamel fluorosis and erosive tooth wear (ETW), respectively. Dental enamel fluorosis is caused by the chronic and excessive intake of fluoride during enamel development, leading to increased fluoride concentration and increased porosity. ETW has become a common clinical condition and often impairs dental function and aesthetics. This in vitro study tested the hypothesis that fluorotic enamel presents different susceptibility to dental erosion-abrasion. It consisted of a 3×3×2 factorial design, considering a) fluorosis severity: sound (TF0), mild (TF1-2), moderate (TF3-4); b) abrasive challenge: low, medium, and high; and c) erosive challenge: yes or no. A total of 144 human teeth were selected according to the three fluorosis severity levels (n=48), and subdivided into six groups (n = 8) generated by the association of the different erosive and abrasive challenges. Enamel blocks (4×4 mm) were prepared from each tooth and their natural enamel surfaces subjected to an erosion-abrasion cycling model. After cycling, the depth of the lesions in enamel was assessed by profilometry. ANOVA showed that the three-way and two-way interactions among the factors were not significant (p > 0.20). Enamel fluorosis level (p=0.638) and abrasion level (p = 0.390) had no significant effect on lesion depth. Acid exposure caused significantly more enamel surface loss than water (p < 0.001). Considering the limitations of this in vitro study, fluorosis did not affect the susceptibility of enamel to dental erosion-abrasion.

Health Risk Assessment in Mexican Children Exposed to Fluoride from Sweetened Beverages.

The primary source of fluoride exposure is groundwater, but evidence suggests that beverages and food are additional fluoride sources. Intake of these products at an early age affects the optimal functioning of soft organs. An increase in sweetened beverage consumption by the pediatric population has been reported, suggesting an increase in fluoride exposure. The objectives of this study were to determine the fluoride concentrations in beverages and analyze the risk to human health from fluoride exposure to sweetened beverages consumed by children. Eighty-two sugar-sweetened beverages produced in different Mexican states were analyzed. The fluoride determination was carried out with an ion-selective electrode. The highest fluoride concentration was 1.92 mg/L; 73.2% of beverages showed fluoride values above permitted limits. Low-cost beverages had the highest fluoride values, suggesting that the water used for their production does not comply with fluorine regulations. According to the risk assessment in children from 3 to 6 years, the daily consumption of juices and sodas with concentrations that exceeded the normative of 0.7 mg/L could represent a risk to dental fluorosis development. It is crucial to control fluoride and regulate its concentrations in beverages for children to ensure food safety, especially in areas of endemic hydrofluorosis.

Fluoride in drinking groundwater and prevalence of fluorosis in children and adolescents: A systematic review.

Fluorosis is a worldwide public health problem. One of the factors related to it is the type of water consumed, such as groundwater. High fluoride concentration in groundwater may be explained by contamination from local industries. Since fluoride and arsenic are the main pollutants of groundwater, some studies correlate groundwater consumption with high prevalence of fluorosis. Aim: The aim of this study was to conduct a systematic review to determine whether children's risk of fluorosis is related to drinking groundwater. Materials and Method: The protocol for this systematic review was registered at the National Institute of Health Research Database (CRD42021227298). A comprehensive search was conducted to identify potentially relevant studies by exploring a range of electronic databases (Medline via PubMed, Scopus, Cochrane Library, Science Direct, Web of Science Core Collection, Medline via Ovid, Lilacs, Embase, and grey literature). Results: A total 2189 articles were found. After reading titles and abstracts, 63 were selected for screening, and the final data was extracted from 15 articles. Conclusion: A relationship was identified between drinking fluoridated water from wells and the prevalence of fluorosis in individuals up to 18 years old. This is the first study to assess the issue systematically worldwide.

La fluorosis es un problema de salud pública a nivel mundial y el tipo de agua consumida es uno de los factores relacionados con ella, como el consumo de aguas subterráneas. La alta concentración de fluoruro en estas aguas puede justificarse por la contaminación por industrias locales y las características del suelo, donde algunos estudios correlacionan el consumo de aguas subterráneas con una alta prevalencia de fluorosis, ya que el fluoruro, junto con el arsénico, se consideran los principales contaminantes de estas aguas. Objetivo: El objetivo es realizar una revisión sistemática que relacione el riesgo de fluorosis en niños expuestos al consumo de agua procedente de pozos. Materiales y Método: El protocolo de esta revisión sistemática fue registrado en el National Institute of Health Research Database (CRD42021227298). Se realizó una búsqueda bibliográfica de estudios primarios explorando diversas bases de datos electrónicas (Medline vía PubMed, Scopus, Cochrane Library, Science Direct, Web of Science Core Collection, Medline vía Ovid, Lilacs, Embase y literatura gris). Resultados: Se encontraron 2189 artículos, tras la lectura de títulos y resúmenes se seleccionaron 63 referencias para examinar y, finalmente, se extrajeron los datos de 15 artículos. Conclusiones: Se identificó una relación entre el consumo de agua fluorada de pozo y la prevalencia de fluorosis en individuos de hasta 18 años, siendo este estudio el primero en evaluarlo sistemáticamente a nivel mundial.

Maternal urinary fluoride during pregnancy and birth weight and length: Results from ELEMENT cohort study.

Epidemiological studies assessing prenatal fluoride exposure and anthropometry at birth are scarce, inconsistent and with methodological limitations. The aim of this study was to evaluate associations between maternal urinary fluoride (MUF) at each trimester of pregnancy and birth weight and length in 536 mother-child pairs in the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort study. MUF (mg/L) was measured using microdiffusion/fluoride-specific electrode from at least one trimester of pregnancy. Non-linear associations were assessed through segmented regression models (MUF and birth weight Z-score) and we used linear regression models for MUF and birth length Z-score. Models were adjusted for potential confounders including urinary creatinine concentrations as a covariate. Non-creatinine adjusted MUF levels at each trimester of pregnancy were 0.81, 0.86, and 0.82 mg/L, mean concentrations for first, second and third trimester, respectively. For birth weight, we identified a MUF breakpoint at 0.99, 0.68 and 0.58 mg/L, for first, second and third trimester of pregnancy, respectively. In the first trimester, an increase of 1 mg/L in MUF concentrations ≥0.99 mg/L was associated with an increase in weight Z-score at birth (ß = 0.79; 95% CI: 0.10, 1.48; p = 0.02). Second trimester MUF (≥0.68 mg/L) was marginally associated with birth weight decrease (ß = -0.25; 95% CI: -0.55, 0.04; p = 0.09) and third trimester MUF (≥0.58 mg/L) was significantly associated with birth weight decrease (ß = -0.33; 95% CI: -0.63, -0.03; p = 0.03). We observed a linear and significant association between MUF and Z-score of length at birth only for the first trimester of pregnancy (ß = 0.55; 95% CI: 0.07, 1.04; p < 0.02). Prenatal fluoride exposure was associated with birthweight z-score with different susceptibility windows. Our findings reinforce the hypothesis that maternal fluoride exposure may affect birth anthropometry.

Fluoruros en agua de consumo al norte y occidente de México / Fluorides in water for consumption in northern and western Mexico

La cantidad de fluoruros en el agua en algunas regiones de México representa un problema de salud pública. El objetivo de este trabajo fue realizar una revisión sistemática de estudios originales que reportaran niveles de fluoruros en agua corriente y embotellada de la región norte y occidente de México. Esta revisión sistemática se elaboró utilizando el sistema PRISMA en las bases de datos de PubMed, Scopus, Medigraphic y Scielo. Se implementaron las palabras clave de fluoride OR fluorosis AND water AND Mexico, y se incluyeron y excluyeron registros de acuerdo con los criterios previamente establecidos. Fueron revisados aquellos artículos publicados entre el 1 de enero del 2010 y el 30 de marzo del 2021. Se identificaron 36 registros en total. La mayoría mostraban datos encontrados en la región occidente del país (n = 23) mientras que los restantes fueron realizados al norte. Ambas regiones se mostraron con rangos máximos y medias muestrales por encima de lo sugerido por la Organización Mundial de la Salud y los organismos reguladores nacionales. De acuerdo con los estudios aquí analizados en México, las regiones Norte y Occidente del país muestran una situación preocupante por los elevados niveles de fluoruros que reportan los autores en agua corriente y embotellada, los niveles se encuentran casi en su totalidad por encima de los recomendados a nivel nacional e internacional lo cual significa un problema de salud pública que requiere de atención.

The amount of fluoride in water in some regions of Mexico represents a public health problem. The aim of this study was to conduct a systematic review of original studies that report fluoride levels in tap and bottled water from the northern and western regions of Mexico. A systematic review was conducted using the PRISMA method in PubMed, Scopus, Medigraphic and Scielo databases. The keywords fluoride OR fluorosis AND water AND Mexico were used for the search and the records found were included and excluded according to the previous established criteria. We reviewed data in articles published between January 1st, 2010 and March 30th, 2021. We identified a total of 36 records. Most showed data found in the western region (n = 23), while the rest reported data found in the north. Both regions reported maximum and mean sample ranges above those suggested by the World Health Organization and national regulations. According to the analyzed data, in Mexico, the northern and western regions of the country show a concerning situation due to the high levels of fluoride reported by many authors in tap and bottled water. Almost all authors reported data above those recommended for national and international regulations, which represent an important public health problem that requires attention.

Prolonged fluoride exposure alters neurotransmission and oxidative stress in the zebrafish brain.

Fluoride is an essential chemical found in dental preparations, pesticides and drinking water. Excessive fluoride exposure is related to toxicological and neurological disruption. Zebrafish are used in translational approaches to understand neurotoxicity in both biomedical and environmental areas. However, there is no complete knowledge about the cumulative effects of fluoride on neurotransmission systems. Therefore, the aim of this study was to evaluate whether prolonged exposure to sodium fluoride (NaF) alters cholinergic and glutamatergic systems and oxidative stress homeostasis in the zebrafish brain. Adult zebrafish were used, divided into four experimental groups, one control group and three groups exposed to NaF at 30, 50 and 100 mg.L-1 for a period of 30 days. After NaF at 30 mg.L-1 exposure, there were significant decreases in acetylcholinesterase (29.8 %) and glutamate uptake (39.3 %). Furthermore, thiobarbituric acid-reactive species were decreased at NaF 50 mg.L-1 (32.7 %), while the group treated with NaF at 30 mg.L-1 showed an increase in dichlorodihydrofluorescein oxidation (41.4 %). NaF at 30 mg.L-1 decreased both superoxide dismutase (55.3 %) and catalase activities (26.1 %). The inhibitory effect observed on cholinergic and glutamatergic signalling mechanisms could contribute to the neurodegenerative events promoted by NaF in the zebrafish brain.

A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders.

Different studies have suggested that fluoride is related to neurological disorders in children and adolescents, but clinical evidences of which neurological parameters associated to fluoride exposure are, in fact, still controversial. In this way, this systematic review and meta-analysis aimed to show if there is an association between fluoride exposure from different sources, doses and neurological disorders. Terms related to "Humans"; "Central nervous system"; "Fluorides"; and "Neurologic manifestations" were searched in a systematic way on PubMed, Scopus, Web of Science, Lilacs, Cochrane and Google Scholar. All studies performed on humans exposed to fluoride were included on the final assessment. A meta-analysis was then performed and the quality level of evidence was performed using the GRADE approach. Our search retrieved 4,024 studies, among which 27 fulfilled the eligibility criteria. The main source of fluoride was naturally fluoridated water. Twenty-six studies showed alterations related to Intelligence Quotient (IQ) while only one has evaluated headache, insomnia, lethargy, polydipsia and polyuria. Ten studies were included on the meta-analysis, which showed IQ impairment only for individuals under high fluoride exposure considering the World Health Organization criteria, without evidences of association between low levels and any neurological disorder. However, the high heterogeneity observed compromise the final conclusions obtained by the quantitative analyses regarding such high levels. Furthermore, this association was classified as very low-level evidence. At this time, the current evidence does not allow us to state that fluoride is associated with neurological damage, indicating the need for new epidemiological studies that could provide further evidences regarding this possible association.

Fluoride Exposure through Different Drinking Water Sources in a Contaminated Basin in Guanajuato, Mexico: A Deterministic Human Health Risk Assessment.

Water fluoride levels above the World Health Organization's guideline (1.5 mg/L), common in overexploited aquifers, represent a health hazard. Our objective was to assess the health risks posed by exposure to fluoride in different drinking water sources in a contaminated basin in Mexico. Fluoride was measured in mutual drinking water sources and in the urine of 39 children and women. Risks were estimated through hazard quotient (HQ) by drinking water source. Dental fluorosis was assessed in the children. Mean fluoride water concentrations (mg/L) were: well, 4.2; waterhole, 2.7; bottled, 2.1; rainwater, 0.4. The mean urinary fluoride concentrations (specific gravity adjusted) were 2.1 mg/L and 3.2 mg/L in children and women, respectively. Our multiple linear regression model showed children's urinary fluoride concentrations increased 0.96 mg/L for every 1 mg/L increase in water fluoride (p < 0.001). Dental fluorosis was diagnosed in 82% of the children, and their HQ according to drinking water source was: well, 1.5; waterhole, 1.1; bottled, 0.8; harvested rainwater, 0.3. The pervasive dental fluorosis indicates a toxic past fluoride exposure; urinary fluoride levels and HQs indicate high exposure and current health risks for most children. Drinking harvested rainwater will likely prevent most of the local fluoride exposure.

Dietary fluoride intake during pregnancy and neurodevelopment in toddlers: A prospective study in the progress cohort.

Foods and beverages provide a source of fluoride exposure in Mexico. While high fluoride concentrations are neurotoxic, recent research suggests that exposures within the optimal range may also pose a risk to the developing brain. This prospective study examined whether dietary fluoride intake during pregnancy is associated with toddlers' neurodevelopment in 103 mother-child pairs from the PROGRESS cohort in Mexico City. Food and beverage fluoride intake was assessed in trimesters 2 and 3 using a food frequency questionnaire and Mexican tables of fluoride content. We used the Bayley-III to evaluate cognitive, motor, and language outcomes at 12 and 24 months of age. Adjusted linear regression models were generated for each neurodevelopment assessment time point (12 and 24 months). Mixed-effects models were used to consider a repeated measurement approach. Interactions between maternal fluoride intake and child sex on neurodevelopmental outcomes were tested. Median (IQR) dietary fluoride intake during pregnancy was 1.01 mg/d (0.73, 1.32). Maternal fluoride intake was not associated with cognitive, language, or motor outcomes collapsing across boys and girls. However, child sex modified the association between maternal fluoride intake and cognitive outcome (p interaction term = 0.06). A 0.5 mg/day increase in overall dietary fluoride intake was associated with a 3.50-point lower cognitive outcome in 24-month old boys (95 % CI: -6.58, -0.42); there was no statistical association with girls (ß = 0.07, 95 % CI: -2.37, 2.51), nor on the cognitive outcome at 12-months of age. Averaging across the 12- and 24-month cognitive outcomes using mixed-effects models revealed a similar association: a 0.5 mg/day increase in overall dietary fluoride intake was associated with a 3.46-point lower cognitive outcome in boys (95 % CI: -6.23, -0.70). These findings suggest that the development of nonverbal abilities in males may be more vulnerable to prenatal fluoride exposure than language or motor abilities, even at levels within the recommended intake range.

Association of Dietary Fluoride Intake and Diet Variables with Dental Caries in Adolescents from the ELEMENT Cohort Study.

To examine the association of dietary fluoride intake, total carbohydrate consumption and other key dietary variables with dental caries experience among adolescents, a cross-sectional analysis was conducted in a sample of 402 participants from the Early Life Exposures in Mexico to Environmental Toxicants cohort. The presence and severity of dental caries were assessed using the International Caries Detection and Assessment System (ICDAS) to calculate the number of decayed, missing, and filled teeth or surfaces (D1MFT/D4MFT). The dietary intake of fluoride, energy, carbohydrates, and food groups was estimated using a validated food frequency questionnaire (FFQ). Multivariate zero-inflated negative binomial regression models and negative binomial regression models were run to estimate the association of fluoride intake (mg/day) and total carbohydrate intake (g/day) with the D1MFT/D4MFT index. We found that 80% of the adolescents experienced dental caries (D1MFT >0), with 30% presenting cavitated lesions (D4MFT >0). The mean scores for D1MFT and D4MFT were 6.2 (SD 5.3) and 0.67 (SD 1.3), respectively. The median intake of fluoride estimated by the FFQ was 0.015 mg/kg/day. This intake was statistically higher in participants with a D4MFT = 0 compared to those with a D4MFT >0 (0.90 vs. 0.82 mg/day; 0.016 vs. 0.014 mg/kg/day; p < 0.05). For D1MFT, D1MFS, D4MFT, and D4MFS scores, a higher fluoride consumption (mg/day) from foods and beverages was associated with a statistically significant reduction in the number of lesions. The reported frequency of consumption of sugary foods in a whole day was statistically higher in those with D1MFT >0 than in those with D1MFT = 0 (p < 0.05). The total carbohydrate intake (g/day) was positively associated with dental caries experience. We conclude that a higher fluoride intake through foods and beverages is associated with a lower dental caries experience among adolescents; this effect was seen even when the dietary intake of fluoride was 0.015 mg/kg/day, which is lower than the average intake recommendation. In contrast, a higher total carbohydrate intake and the frequency of intake of sugary foods were associated with a higher dental caries experience, with no apparent threshold for the effects.

Molar-incisor hypomineralization (MIH), dental fluorosis, and caries in rural areas with different fluoride levels in the drinking water.

AIM: This study determined the prevalence of molar-incisor hypomineralization (MIH) and its association with dental fluorosis and caries in children living in rural areas in north-eastern Brazil who are exposed to residual fluoride (F) levels in the drinking water. DESIGN: A census was carried out with 610 schoolchildren aged 6 to 12 years. The European Academy of Paediatric Dentistry criteria, Thysltrup and Fejerskov index, and World Health Organization index were used for diagnosis of MIH, dental fluorosis, and caries detection, respectively. The association between the outcome and exposure variables was determined by robust Poisson regression (P < .05). RESULTS: Water F-levels varied from 0.06 to 1.98 ppm. MIH was not related to fluoride levels in the drinking water, but it showed an inverse and direct correlation with dental caries and fluorosis, respectively. Children with MIH had a higher DMFT, and severe MIH cases were most frequent in children with dental fluorosis. CONCLUSION: Drinking water F-levels were not directly related to the occurrence of MIH in schoolchildren. The severity of MIH, however, was likely to be associated with dental fluorosis in areas with moderate to high fluoride levels in the drinking water.

Effects of Fluoride Long-Term Exposure over the Cerebellum: Global Proteomic Profile, Oxidative Biochemistry, Cell Density, and Motor Behavior Evaluation.

Although the literature does not provide evidence of health risks from exposure to fluoride (F) in therapeutic doses, questions remain about the effects of long-term and high-dose use on the function of the central nervous system. The objective of this study was to investigate the effect of long-term exposure to F at levels similar to those found in areas of artificial water fluoridation and in areas of endemic fluorosis on biochemical, proteomic, cell density, and functional parameters associated with the cerebellum. For this, mice were exposed to water containing 10 mg F/L or 50 mg F/L (as sodium fluoride) for 60 days. After the exposure period, the animals were submitted to motor tests and the cerebellum was evaluated for fluoride levels, antioxidant capacity against peroxyl radicals (ACAP), lipid peroxidation (MDA), and nitrite levels (NO). The proteomic profile and morphological integrity were also evaluated. The results showed that the 10 mg F/L dose was able to decrease the ACAP levels, and the animals exposed to 50 mg F/L presented lower levels of ACAP and higher levels of MDA and NO. The cerebellar proteomic profile in both groups was modulated, highlighting proteins related to the antioxidant system, energy production, and cell death, however no neuronal density change in cerebellum was observed. Functionally, the horizontal exploratory activity of both exposed groups was impaired, while only the 50 mg F/L group showed significant changes in postural stability. No motor coordination and balance impairments were observed in both groups. Our results suggest that fluoride may impair the cerebellar oxidative biochemistry, which is associated with the proteomic modulation and, although no morphological impairment was observed, only the highest concentration of fluoride was able to impair some cerebellar motor functions.

Does fluoride cause neurotoxic effects in humans? The importance of critically analyzing the scientific evidence / O fluoreto tem efeito neurotóxico? A importância da análise crítica da informação

The lack of critical interpretation of scientific information resulting from foundational data and evidence can jeopardize the shared decision between a clinical practitioner and the patient. This commentary analyzes the scientific evidence of a systematic review about the neurotoxic effect of fluoride in humans. The systematic review included observational studies from Chinese and Iranian populations exposed to a high-fluoridated water supply. The meta-analysis indicated that these populations had lower scores of the intelligence coefficient (IQ). However, the review is limited by the lack of methodological quality and the certainty of the scientific evidence. To critically analyze the evidence, we should avoid the "wireless phone effect" that considers the information without checking the original data source. Moreover, we should always base our analysis on the full text and never on the abstract alone.

The association between the prevalence of dental fluorosis and the socio-economic status and area of residence of 12-year-old students in Uruguay.

Objective: This study investigates the association between the prevalence and severity of dental fluorosis, the socio-economic status (SES) and area of residence among 12-year-old schoolchildren in Uruguay.Material and methods: The study was descriptive, cross-sectional, explanatory and observational. Subjects considered eligible were born in 1999 and had their parents' or guardian's prior consent. A questionnaire was used to identify SES according to Centro de Investigaciones Económicas Institute on four levels. Dental fluorosis was determined using the Thylstrup-Fejerskov (TF) index.Results: Of the 1544 students examined, 45.0% showed dental fluorosis. A TF index 1-2 was recorded in 29.3% of the subjects, TF 3 in 20.9%, TF 4 in 6.7% and TF 5-9 in 2.1%. In area 1 (the capital Montevideo city), 84.8% of the subjects had dental fluorosis, a value that was significantly higher than in the inland region (area 2, 24.4%) and border departments (area 3, 22.5%) (x2 = 27.92, p < .0001). Students from families with a low socio-economic level showed less prevalence of dental fluorosis than those with a high level (x2 = 14.58, p = .002).Conclusion: Significant differences exist in the prevalence of dental fluorosis in relation to place of residence and socio-economic level.

Association between fluoride exposure and cardiometabolic risk in peripubertal Mexican children.

BACKGROUND: Several animal studies have suggested that fluoride exposure may increase the levels of cardiometabolic risk factors, but little is known about whether fluoride exposure is associated with such risk in humans. OBJECTIVES: We examined the cross-sectional association between peripubertal exposure to fluoride and markers of cardiometabolic risk in 280 girls and 256 boys at age 10-18 years living in Mexico City. METHODS: We measured plasma fluoride concentration using a microdiffusion method. We collected data on anthropometry including BMI, waist circumference (WC) and trunk fat percentage. We measured serum markers of cardiometabolic risk, including fasting glucose, insulin and lipids. All the indicators of outcome were converted to age- and sex-specific z-scores. We also calculated a summary cardiometabolic risk score for each participant. Multivariable linear regression models were used to examine these associations. RESULTS: The geometric mean (95% confidence interval (CI)) of plasma fluoride was 0.21 µmol/L (0.20, 0.23 µmol/L) in the total sample. In girls, plasma fluoride concentrations were associated with higher z-scores for all the individual markers (except for lipids) and for the combined cardiometabolic risk score (risk score: ß = 1.28, 95% CI: 0.57-2.00, p-sex interaction = 0.02)), adjusting for covariates. No associations were found in boys. CONCLUSIONS: We found that higher peripubertal fluoride exposure at the levels observed in this study population was significantly associated with increased levels of cardiometabolic risk factors in Mexican girls but not boys. Future studies with a longitudinal design are needed to confirm our findings and further elucidate the role of fluoride in cardiometabolic risk.

Fluoride exposure is associated with altered metabolism of arsenic in an adult Mexican population.

Arsenic (As) and fluoride (F) are two common groundwater toxicants. The toxicity of As is closely related to As metabolism, and several biological and environmental factors have been associated with As modification. However, limited information about the effect of F exposure on the modification of the As metabolism profile has been described. The aim of this study was to assess the interaction effect of AsF coexposure on the As metabolism profile in an adult population environmentally exposed to low-moderate As levels. A cross-sectional study was conducted in 236 adults from three Mexican communities. F and As concentrations were quantified in water samples. The concentrations of urinary F and As species [inorganic arsenic (iAs), monomethylated arsenic (MAs) and dimethylated arsenic (DMAs)] were also determined and used as exposure biomarkers. As species percentages and methylation indices were estimated to evaluate the As methylation profile. Our results showed a relationship between the water and urine concentrations of both contaminants and, a significant correlation between the As and F concentrations in water and urine samples. A statistically significant interaction of F and As exposure on the increase in MAs% (ß = 0.16, p = 0.018) and the decrease in DMAs% (ß = -0.3, p = 0.034), PMI (ß = -0.07, p = 0.052) and SMI (ß = -0.13, p = 0.097) was observed. These findings indicate that drinking water is the main source of AsF coexposure and suggest that F exposure decreases As methylation capacity. However, additional large and prospective studies are required to confirm our findings, and to elucidate the involved mechanisms of interaction and their implications in adverse health effects.