U.S. Department of Health and Human Services Federal Panel on Community Water Fluoridation. U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries

Effect of Fluoride Concentration in Drinking Water on Dental Fluorosis in Southwest Saudi Arabia

This study was intended to evaluate the fluoride concentration in drinking water and its effect on dental fluorosis in Southwest Saudi Arabia. Water samples were gathered rom wells, filtration plants and commercial brands (bottled water) in distinct urban and rural areas of Asir region of the Kingdom of Saudi Arabia (KSA). Overall, 63 water samples were collected from 12 locations and 9 brands of bottled water. ExStik^® FL700Fluoridemeter was used in the analysis of water samples for fluoride levels. The total number of screened patients for dental fluorosis, aged between 9 and 50 years, was 1150; among them, 609 were males and 541 were females. Dean's index criteria were used to examine the patients for dental fluorosis. The results revealed that fluoride levels varied between 0.03 and 3.8 ppm. People who drank well water displayed increased fluoride levels (>0.81 ppm). The prevalence of dental fluorosis was established to be 20.43% among the total number of examined patients. The findings of this study show very mild to moderate dental fluorosis prevail among the patients who consume well water in the Asir region.

Histone acetyltransferase promotes fluoride toxicity in LS8 cells

Previously we demonstrated that fluoride increased acetylated-p53 (Ac-p53) in LS8 cells that are derived from mouse enamel organ epithelia and in rodent ameloblasts. However, how p53 is acetylated by fluoride and how the p53 upstream molecular pathway responds to fluoride is not well characterized. Here we demonstrate that fluoride activates histone acetyltransferases (HATs) including CBP, p300, PCAF and Tip60 to acetylate p53. HAT activity is regulated by post-translational modifications such as acetylation and phosphorylation. HAT proteins and their post-translational modifications (p300, Acetyl-p300, CBP, Acetyl-CBP, Tip60 and phospho-Tip60) were analyzed by Western blots. p53-HAT binding was detected by co-immunoprecipitation (co-IP). Cell growth inhibition was analyzed by MTT assays. LS8 cells were treated with NaF with/without HAT inhibitors MG149 (Tip60 inhibitor) and Anacardic Acid (AA; inhibits p300/CBP and PCAF). MG149 or AA was added 1 h prior to NaF treatment. Co-IP results showed that NaF increased p53-CBP binding and p53-PCAF binding. NaF increased active Acetyl-p300, Acetyl-CBP and phospho-Tip60 levels, suggesting that fluoride activates these HATs. Fluoride-induced phospho-Tip60 was decreased by MG149. MG149 or AA treatment reversed fluoride-induced cell growth inhibition at 24 h. MG149 or AA treatment decreased fluoride-induced p53 acetylation to inhibit caspase-3 cleavage, DNA damage marker γH2AX expression and cytochrome-c release into the cytosol. These results suggest that acetylation of p53 by HATs contributes, at least in part, to fluoride-induced toxicity in LS8 cells via cell growth inhibition, apoptosis, DNA damage and mitochondrial damage. Modulation of HAT activity may, therefore, be a potential therapeutic target to mitigate fluoride toxicity in ameloblasts.

Toxicity of fluoride: critical evaluation of evidence for human developmental neurotoxicity in epidemiological studies, animal experiments and in vitro analyses

Recently, epidemiological studies have suggested that fluoride is a human developmental neurotoxicant that reduces measures of intelligence in children, placing it into the same category as toxic metals (lead, methylmercury, arsenic) and polychlorinated biphenyls. If true, this assessment would be highly relevant considering the widespread fluoridation of drinking water and the worldwide use of fluoride in oral hygiene products such as toothpaste. To gain a deeper understanding of these assertions, we reviewed the levels of human exposure, as well as results from animal experiments, particularly focusing on developmental toxicity, and the molecular mechanisms by which fluoride can cause adverse effects. Moreover, in vitro studies investigating fluoride in neuronal cells and precursor/stem cells were analyzed, and 23 epidemiological studies published since 2012 were considered. The results show that the margin of exposure (MoE) between no observed adverse effect levels (NOAELs) in animal studies and the current adequate intake (AI) of fluoride (50 µg/kg b.w./day) in humans ranges between 50 and 210, depending on the specific animal experiment used as reference. Even for unusually high fluoride exposure levels, an MoE of at least ten was obtained. Furthermore, concentrations of fluoride in human plasma are much lower than fluoride concentrations, causing effects in cell cultures. In contrast, 21 of 23 recent epidemiological studies report an association between high fluoride exposure and reduced intelligence. The discrepancy between experimental and epidemiological evidence may be reconciled with deficiencies inherent in most of these epidemiological studies on a putative association between fluoride and intelligence, especially with respect to adequate consideration of potential confounding factors, e.g., socioeconomic status, residence, breast feeding, low birth weight, maternal intelligence, and exposure to other neurotoxic chemicals. In conclusion, based on the totality of currently available scientific evidence, the present review does not support the presumption that fluoride should be assessed as a human developmental neurotoxicant at the current exposure levels in Europe.

Associations of fluoride exposure with sex steroid hormones among U.S. children and adolescents, NHANES 2013-2016

Fluoride mediated disruption of sex steroid hormones has been demonstrated in animals. However, evidence from humans was limited and contradictory, especially for children and adolescents. Based on data of the National Health and Nutrition Survey (NHANES) 2013-2016, a total of 3392 subjects aged 6-19 years were analyzed in this cross-sectional study. Both plasma and water fluoride levels were quantified electrometrically using the ion-specific electrode. Sex steroid hormones of total testosterone, estradiol and sex hormone-binding globulin (SHBG) were tested in serum. Percent changes and 95% confidence intervals (CIs) in sex steroid hormones associated with tertiles of fluoride levels (setting the first as reference) were estimated using adjusted linear regression models by stratification of gender and age. Compared with subjects at the first tertile of plasma fluoride, percent changes (95% CIs) in testosterone were -8.08% (-17.36%, 2.25%) and -21.65% (-30.44%, -11.75%) for the second and third tertiles, respectively (P _trend <0.001). Male adolescents at the third tertile of plasma fluoride had decreased levels of testosterone (percent change = -21.09%, 95% CIs = -36.61% to -1.77%). Similar inverse associations were also found when investigating the relationships between plasma fluoride and estradiol. Besides, the data indicated decreased levels of SHBG associated with water and plasma fluoride among the male adolescents (percent change of the third tertile = -9.39%, 95% CIs = -17.25% to -0.78%) and female children (percent change of the second tertile = -10.78%, 95% CIs = -17.55% to -3.45%), respectively. The data indicated gender- and age-specific inverse associations of fluoride in plasma and water with sex steroid hormones of total testosterone, estradiol and SHBG in U.S. children and adolescents. Prospective cohort studies are warranted to confirm the causality.

Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California

BACKGROUND

Previous studies have shown a correlation between fluoride concentrations in urine and community water fluoride concentrations. However, there are no studies of the relationship between community water fluoridation, urine, serum, and amniotic fluid fluoride concentrations in pregnant women in the US. The aim of this study was to determine the relationship between maternal urine fluoride (MUF), maternal urine fluoride adjusted for specific gravity (MUF_SG), maternal serum fluoride (MSF), amniotic fluid fluoride (AFF) concentrations during pregnancy, and community water fluoridation in Northern California.

METHODS

Archived samples of urine, serum and amniotic fluid collected from second trimester pregnant women in Northern California from 47 different communities in Northern California and one from Montana (n = 48), were analyzed for fluoride using an ion specific electrode following acid microdiffusion. Women's addresses were matched to publicly reported water fluoride concentrations. We examined whether fluoride concentrations in biospecimens differed by fluoridation status of the community water, and determined the association between water fluoride concentrations and biospecimen fluoride concentrations using linear regression models adjusted for maternal age, smoking, Body Mass Index (BMI), race/ethnicity, and gestational age at sample collection.

RESULTS

Fluoride concentrations in the community water supplies ranged from 0.02 to 1.00 mg/L. MUF, MSF , and AFF concentrations were significantly higher in pregnant women living in communities adhering to the U.S. recommended water fluoride concentration (0.7 mg/L), as compared with communities with less than 0.7 mg/L fluoride in drinking water. When adjusted for maternal age, smoking status, BMI, race/ethnicity, and gestational age at sample collection, a 0.1 mg/L increase in community water fluoride concentration was positively associated with higher concentrations of MUF (B = 0.052, 95% CI:0.019,0.085), MUF_SG (B = 0.028, 95% CI: -0.006, 0.062), MSF (B = 0.001, 95% CI: 0.000, 0.003) and AFF (B = 0.001, 95% CI: 0.000, 0.002).

CONCLUSIONS

We found universal exposure to fluoride in pregnant women and to the fetus via the amniotic fluid. Fluoride concentrations in urine, serum, and amniotic fluid from women were positively correlated to public records of community water fluoridation. Community water fluoridation remains a major source of fluoride exposure for pregnant women living in Northern California.

How Fluoride Protects Dental Enamel from Demineralization

Introduction:

How fluoride (F^–) protects dental enamel from caries is here conveyed to dental health-care providers by making simplifying approximations that accurately convey the essential principles, without obscuring them in a myriad of qualifications.

Materials and Methods:

We approximate that dental enamel is composed of calcium hydroxyapatite (HAP), a sparingly soluble ionic solid with the chemical formula Ca₁₀(PO₄)₆(OH)₂.

Results:

The electrostatic forces binding ionic solids together are described by Coulomb’s law, which shows that attractions between opposite charges increase greatly as their separation decreases. Relatively large phosphate ions (PO₄^3–) dominate the structure of HAP, which approximates a hexagonal close-packed structure. The smaller Ca²⁺ and OH^– ions fit into the small spaces (interstices) between phosphates, slightly expanding the close-packed structure. F^– ions are smaller than OH^– ions, so substituting F^– for OH^– allows packing the same number of ions into a smaller volume, increasing their forces of attraction. Dental decay results from tipping the solubility equilibrium Ca₁₀(PO₄)₆(OH)₂ (s) ⇔ 10Ca²⁺ (aq) + 6PO₄^2– (aq) + 2OH^– (aq) toward dissolution. HAP dissolves when the product of its ion concentrations, [Ca²⁺]¹⁰×[PO₄^3–]⁶×[OH^–]², falls below the solubility product constant (Ksp) for HAP.

Conclusion:

Because of its more compact crystal structure, the Ksp for fluorapatite (FAP) is lower than the Ksp for HAP, so its ion product, [Ca²⁺]¹⁰×[PO₄^3–]⁶×[F^–]², must fall further before demineralization can occur. Lowering the pH of the fluid surrounding enamel greatly reduces [PO₄^3–] (lowering the ion products of HAP and FAP equally), but [OH^–] falls much more rapidly than [F^–], so FAP better resists acid attack.

Principles of fluoride toxicity and the cellular response: a review

Fluoride is ubiquitously present throughout the world. It is released from minerals, magmatic gas, and industrial processing, and travels in the atmosphere and water. Exposure to low concentrations of fluoride increases overall oral health. Consequently, many countries add fluoride to their public water supply at 0.7-1.5 ppm. Exposure to high concentrations of fluoride, such as in a laboratory setting often exceeding 100 ppm, results in a wide array of toxicity phenotypes. This includes oxidative stress, organelle damage, and apoptosis in single cells, and skeletal and soft tissue damage in multicellular organisms. The mechanism of fluoride toxicity can be broadly attributed to four mechanisms: inhibition of proteins, organelle disruption, altered pH, and electrolyte imbalance. Recently, there has been renewed concern in the public sector as to whether fluoride is safe at the current exposure levels. In this review, we will focus on the impact of fluoride at the chemical, cellular, and multisystem level, as well as how organisms defend against fluoride. We also address public concerns about fluoride toxicity, including whether fluoride has a significant effect on neurodegeneration, diabetes, and the endocrine system.

Fluoride exposure alters Ca2+ signaling and mitochondrial function in enamel cells

Fluoride ions are highly reactive, and their incorporation in forming dental enamel at low concentrations promotes mineralization. In contrast, excessive fluoride intake causes dental fluorosis, visually recognizable enamel defects that can increase the risk of caries. To investigate the molecular bases of dental fluorosis, we analyzed the effects of fluoride exposure in enamel cells to assess its impact on Ca2+ signaling. Primary enamel cells and an enamel cell line (LS8) exposed to fluoride showed decreased internal Ca2+ stores and store-operated Ca2+ entry (SOCE). RNA-sequencing analysis revealed changes in gene expression suggestive of endoplasmic reticulum (ER) stress in fluoride-treated LS8 cells. Fluoride exposure did not alter Ca2+ homeostasis or increase the expression of ER stress-associated genes in HEK-293 cells. In enamel cells, fluoride exposure affected the functioning of the ER-localized Ca2+ channel IP3R and the activity of the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump during Ca2+ refilling of the ER. Fluoride negatively affected mitochondrial respiration, elicited mitochondrial membrane depolarization, and disrupted mitochondrial morphology. Together, these data provide a potential mechanism underlying dental fluorosis.

Synthesis of alumina-based cross-linked chitosan–HPMC biocomposite film: an efficient and user-friendly adsorbent for multipurpose water purification

Novel alumina-based cross-linked chitosan–HPMC biocomposite is synthesized and its detailed characteristics with potential applications in water purification from both organic and inorganic contaminants elucidated.

Princípios invocados numa política intersetorial de saúde: o caso da fluoretação da água no Brasil

Resumo O objetivo foi identificar princípios invocados numa política intersetorial de saúde, tomando como caso uma proposta legislativa de revogação da fluoretação da água no Brasil apresentada em 2003. Realizou-se estudo descritivo por meio de pesquisa documental, na qual foram selecionados registros gerados na tramitação do Projeto de Lei nº 510/2003 na Câmara dos Deputados. Buscou-se destacar estratégias discursivas utilizadas pelos atores conforme o jogo de interesses e o contexto conflitivo, utilizando-se o institucionalismo histórico como referencial teórico. O Projeto de Lei tramitou 13 meses, passando pelo Plenário, por três comissões, e sendo arquivado. Três deputados de partidos distintos, órgãos do Poder Executivo federal, agências reguladoras e entidades representativas da categoria odontológica, da saúde pública/coletiva, da engenharia sanitária e das empresas de saneamento participaram diretamente do debate em que emergiram os princípios da segurança da intervenção, dos custos econômicos e do direito à saúde. Em relação às estratégias discursivas utilizadas, os principais elementos invocados no debate da política intersetorial de saúde foram o princípio da incerteza, criando-se falsas categorias científicas a fim de sobrevalorizar os efeitos desfavoráveis e sustentar a implementação de medidas individualizantes; e os princípios morais que definem diferentes tipos de bens econômicos e dimensões de liberdade associadas ao exercício de direitos.

Fluoride exposure from infant formula and child IQ in a Canadian birth cohort

BACKGROUND

Infant consumption of formula reconstituted with fluoridated water can lead to excessive fluoride intake. We examined the association between fluoride exposure in infancy and intellectual ability in children who lived in fluoridated or non-fluoridated cities in Canada.

METHODS

We examined 398 mother-child dyads in the Maternal-Infant Research on Environmental Chemicals cohort who reported drinking tap water. We estimated water fluoride concentration using municipal water reports. We used linear regression to analyze the association between fluoride exposure and IQ scores, measured by the Wechsler Primary and Preschool Scale of Intelligence-III at 3-4 years. We examined whether feeding status (breast-fed versus formula-fed) modified the impact of water fluoride and if fluoride exposure during fetal development attenuated this effect. A second model estimated the association between fluoride intake from formula and child IQ.

RESULTS

Thirty-eight percent of mother-child dyads lived in fluoridated communities. An increase of 0.5 mg/L in water fluoride concentration (approximately equaling the difference between fluoridated and non-fluoridated regions) corresponded to a 9.3- and 6.2-point decrement in Performance IQ among formula-fed (95% CI: -13.77, -4.76) and breast-fed children (95% CI: -10.45, -1.94). The association between water fluoride concentration and Performance IQ remained significant after controlling for fetal fluoride exposure among formula-fed (B = -7.93, 95% CI: -12.84, -3.01) and breastfed children (B = -6.30, 95% CI: -10.92, -1.68). A 0.5 mg increase in fluoride intake from infant formula corresponded to an 8.8-point decrement in Performance IQ (95% CI: -14.18, -3.34) and this association remained significant after controlling for fetal fluoride exposure (B = -7.62, 95% CI: -13.64, -1.60).

CONCLUSIONS

Exposure to increasing levels of fluoride in tap water was associated with diminished non-verbal intellectual abilities; the effect was more pronounced among formula-fed children.

Fluoride exposure and sleep patterns among older adolescents in the United States: a cross-sectional study of NHANES 2015-2016

BACKGROUND

Fluoride from environmental sources accumulates preferentially in the pineal gland which produces melatonin, the hormone that regulates the sleep-wake cycle. However, the effects of fluoride on sleep regulation remain unknown. This population-based study examined whether chronic low-level fluoride exposure is associated with sleep patterns and daytime sleepiness among older adolescents in the United States (US).

METHOD

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2015-2016). We analyzed data from adolescents who had plasma fluoride (n = 473) and water fluoride (n = 419) measures and were not prescribed medication for sleep disorders. Relationships between fluoride exposure and self-reported sleep patterns or daytime sleepiness were examined using survey-weighted linear, binomial logistic or multinomial logistic regression after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.

RESULTS

The average age of adolescents was 17 years (range = 16-19). Median (IQR) water and plasma fluoride concentrations were 0.27 (0.52) mg/L and 0.29 (0.19) μmol/L respectively. An IQR increase in water fluoride was associated with 1.97 times higher odds of reporting symptoms suggestive of sleep apnea (95% CI: 1.27, 3.05; p = 0.02), a 24 min later bedtime (B = 0.40, 95% CI: 0.10, 0.70; p = 0.05), a 26 min later morning wake time (B = 0.43, 95% CI: 0.13, 0.73; p = 0.04), and among males, a 38% reduction in the odds of reporting snoring (95% CI: 0.45, 0.87, p = 0.03).

CONCLUSIONS

Fluoride exposure may contribute to changes in sleep cycle regulation and sleep behaviors among older adolescents in the US. Additional prospective studies are warranted to examine the effects of fluoride on sleep patterns and determine critical windows of vulnerability for potential effects.

Exposure of Fluoride with Streptozotocin-Induced Diabetes Aggravates Testicular Damage and Spermatozoa Parameters in Mice

Diabetes mellitus is the most common chronic disease worldwide that causes numerous complications, including male infertility. The prevalence of DM is 451 million people and estimated that would increase to 693 million in 2045. Fluorosis caused by drinking water contaminated with inorganic fluoride is a public health problem in many areas around the world. Previous studies have shown that fluoride exposure damages the male reproductive function. This study aimed to evaluate the fluoride sub-chronic exposure on the spermatozoa function in streptozotocin (STZ)-induced diabetic mice. After confirming diabetes by measuring blood glucose levels, the male mice received 45.2 ppm of fluoride added or deionized water. We evaluated several parameters in diabetic mice exposed to fluoride: standard quality analysis, the mitochondrial transmembrane potential (ψm), the caspase activity in spermatozoa, urinary fluoride excretion, and histological evaluation in the testes. After 60 days of fluoride-exposure, diabetic mice, significantly decreased sperm quality (motility, viability, and concentration). Spermatozoa from fluoride-exposure in diabetic mice presented a significant decrease in ψm and a significant increase in activity caspase 3/7. Urinary fluoride excretion was decreased in diabetic mice exposed to fluoride. Subchronic fluoride exposure of mice with STZ-induced diabetes aggravated testicular damage and the spermatozoa function.

Dental health status and its indicators in adult Brazilian Indians without exposition to drinking water fluoridation: a cross-sectional study

Water fluoridation is considered a cost-effective and practical method for controlling and preventing dental caries in the general population. The objective of this study was to evaluate the dental health status and risk indicators for dental caries in adult Brazilian Indians without exposition to dental caries-preventive effects of water fluoridation. Decayed (DT), missing (MT), and filled (FT) permanent teeth (DMFT), as well as plaque index, unstimulated salivary flow rate, salivary buffering capacity, and fasting blood glucose were examined in 225 adult Indians. Smoking habits and sociodemographic data were evaluated using a structured questionnaire. Drinking water samples from 10 Indian villages were analyzed for the natural fluoride concentration. The mean DMFT was 10.33 ± 6.91 (DT, 4.19 ± 3.99; MT, 4.99 ± 5.64; FT, 1.14 ± 1.75). DMFT index ≥ 9 was associated with age ≥ 35 years (p = 0.000), lower education (p = 0.03), and plaque index > 40% (p = 0.003). DT was associated only with plaque index (p = 0.03). MT was associated with age (p < 0.001) and plaque index (p = 0.01). FT was negatively associated with age (p = 0.02) and income (p = 0.02). Fluoride concentration varied from 0.01 to 0.07 mg/L and was not associated with dental health status (p ≥ 0.29). In conclusion, poorer dental health status was associated with older age, higher plaque index, and lower education and income levels. The fluoride level in the drinking water of Kiriri villages was lower than the level recommended for preventing dental caries. Water fluoridation may be recommended for this population.

Fluoride exposure and kidney and liver function among adolescents in the United States: NHANES, 2013-2016

BACKGROUND

Hepato- and nephrotoxicity of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. This population-based study examines the relationship between chronic low-level fluoride exposure and kidney and liver function among United States (U.S.) adolescents. This study aimed to evaluate whether greater fluoride exposure is associated with altered kidney and liver parameters among U.S. youth.

METHODS

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2013-2016). We analyzed data from 1983 and 1742 adolescents who had plasma and water fluoride measures respectively and did not have kidney disease. Fluoride was measured in plasma and household tap water. Kidney parameters included estimated glomerular filtration rate (calculated by the original Schwartz formula), serum uric acid, and the urinary albumin to creatinine ratio. Liver parameters were assessed in serum and included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, gamma-glutamyl transferase, and albumin. Survey-weighted linear regression examined relationships between fluoride exposure and kidney and liver parameters after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.

RESULTS

The average age of adolescents was 15.4 years. Median water and plasma fluoride concentrations were 0.48 mg/L and 0.33 μmol/L respectively. A 1 μmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate (95% CI: -17.50, -3.22; p = 0.05), a 0.29 mg/dL higher serum uric acid concentration (95% CI: 0.09, 0.50; p = 0.05), and a 1.29 mg/dL lower blood urea nitrogen concentration (95%CI: -1.87, -0.70; p < 0.001). A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration (95% CI: -1.44, -0.42; p = 0.007).

CONCLUSIONS

Fluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.

Nitrate and Phosphate Transporters Rescue Fluoride Toxicity in Yeast

Organisms are exposed to fluoride in the air, water, and soil. Yeast and other microbes utilize fluoride channels as a method to prevent intracellular fluoride accumulation and mediate fluoride toxicity. Consequently, deletion of fluoride exporter genes (FEX) in S. cerevisiae resulted in over 1000-fold increased fluoride sensitivity. We used this FEX knockout strain to identify genes, that when overexpressed, are able to partially relieve the toxicity of fluoride exposure. Overexpression of five genes, SSU1, YHB1, IPP1, PHO87, and PHO90, increase fluoride tolerance by 2- to 10-fold. Overexpression of these genes did not provide improved fluoride resistance in wild-type yeast, suggesting that the mechanism is specific to low fluoride toxicity in yeast. Ssu1p and Yhb1p both function in nitrosative stress response, which is induced upon fluoride exposure along with metal influx. Ipp1p, Pho87p, and Pho90p increase intracellular orthophosphate. Consistent with this observation, fluoride toxicity is also partially mitigated by the addition of high levels of phosphate to the growth media. Fluoride inhibits phosphate import upon stress induction and causes nutrient starvation and organelle disruption, as supported by gene induction monitored through RNA-Seq. The combination of observations suggests that transmembrane nutrient transporters are among the most sensitized proteins during fluoride-instigated stress.

Review of Fluoride Intake and Appropriateness of Current Guidelines

Since the classical epidemiological studies by Dean, it has been known that there should be an optimum level of exposure to fluoride that would be able to provide the maximum protection against caries, with minimum dental fluorosis. The "optimal" daily intake of fluoride for children (0.05-0.07 mg per kilogram bodyweight) that is still accepted worldwide was empirically determined. In the present review, we discuss the appropriateness of the current guidance for fluoride intake, in light of the windows of susceptibility to caries and fluorosis, the modern trends of fluoride intake from multiple sources, individual variations in fluoride metabolism, and recent epidemiological data. The main conclusion is that it is very difficult to think about a strict recommendation for an "optimal" range of fluoride intake at the individual level in light of existing knowledge of 1) the mechanisms of action of fluoride to control caries, 2) the mechanisms involved in dental fluorosis development, 3) the distinct factors that interfere in the metabolism of fluoride, and 4) the windows of susceptibility to both dental caries and fluorosis development. An "optimal" range of fluoride intake is, however, desirable at the population level to guide programs of community fluoridation, but further research is necessary to provide additional support for future decisions on guidance in this area. This list includes the effect of factors affecting fluoride metabolism, clinical trials on the effectiveness of low-fluoride dentifrices to prevent caries in the primary dentition, and validation of biomarkers of exposure to fluoride.

Monitoring, mapping and health risk assessment of fluoride in drinking water supplies in rural areas of Maku and Poldasht, Iran

The aim of this study was to investigate and determine fluoride concentrations in drinking water supplies in rural areas of Maku and Poldasht in West Azerbaijan Province, the northwest of Iran. Fluorosis risk assessment and characterization was also investigated. Fluoride concentrations mapping was accomplished by using the GIS system. Totally, 356 water samples, including one sample in each season, were collected from 89 water supplies providing water for 95 and 61 rural areas of Maku and Poldasht, respectively. According to the results, in Maku and Poldasht, 25 and 30 rural areas had contaminated water sources, respectively. Average annual fluoride concentrations ranged from 3.04 to 7.31 mg/l in the contaminated villages of Maku, which is about 2-4.8 times higher than the maximum standard level of the Iranian drinking water standard, and 4.52-8.21 mg/l in the contaminated areas of Poldasht, which is about 3-5.47 times higher than the maximum standard level. The maximum fluoride level was determined 11.12 mg/l and 10.98 mg/l in one of villages of Maku and Poldasht Counties in summer, respectively. Neither in Maku nor in Poldasht, water resources showed dental cavity risk, while dental fluorosis risk and skeletal fluorosis risk were very significant in some villages of both cities. Children were at most risk of fluorosis. New alternative water supplies for the contaminated villages if possible, consumption of bottled water and application of reverse osmosis are recommended as remedial actions in the contaminated areas.

Chronic Fluoride Exposure and the Risk of Autism Spectrum Disorder

The continuous rise of autism spectrum disorder (ASD) prevalent in the past few decades is causing an increase in public health and socioeconomic concern. A consensus suggests the involvement of both genetic and environmental factors in the ASD etiopathogenesis. Fluoride (F) is rarely recognized among the environmental risk factors of ASD, since the neurotoxic effects of F are not generally accepted. Our review aims to provide evidence of F neurotoxicity. We assess the risk of chronic F exposure in the ASD etiopathology and investigate the role of metabolic and mitochondrial dysfunction, oxidative stress and inflammation, immunoexcitotoxicity, and decreased melatonin levels. These symptoms have been observed both after chronic F exposure as well as in ASD. Moreover, we show that F in synergistic interactions with aluminum's free metal cation (Al3+) can reinforce the pathological symptoms of ASD. This reinforcement takes place at concentrations several times lower than when acting alone. A high ASD prevalence has been reported from countries with water fluoridation as well as from endemic fluorosis areas. We suggest focusing the ASD prevention on the reduction of the F and Al3+ burdens from daily life.

Fluoride Intake of Infants from Formula

OBJECTIVE

This study aimed to assess fluoride intake in infants from formula reconstituted with water, with fluorosis risk in mind.

STUDY DESIGN

Data on water source, formula brand/type, volume of formula consumption and infant weight were collected for infants at two-, four-, six-, nine- and twelve-month pediatrician well child visits. Identified formula brands and water types were reconstituted and analyzed for fluoride concentration. Patient body mass and volume consumed/day were used to estimate fluoride intake from reconstituted formula. Descriptive statistics, one-way analysis of variance and chi-square tests were utilized.

RESULTS

All infants consumed formula reconstituted with minimally fluoridated water (0.0- 0.3 ppm). 4.4% of infants exceeded the recommended upper limit (UL) of 0.1mg/kg/day. Although mean daily fluoride consumption significantly differed among all groups, the proportion of infants at each visit milestone that exceeded daily fluoride intake of 0.1mg/kg/day was not statistically significantly different (p>0.05) for any age group. Predicted values calculated with optimally fluoridated water (0.7ppm) resulted in 36.8% of infants exceeding the UL.

CONCLUSIONS

Optimally fluoridated water may increase fluorosis risk for patients younger than six months. Future investigation should include multiple sites and multi-year follow-up to assess actual fluorosis incidence.

Fluoride Revolution and Dental Caries: Evolution of Policies for Global Use

Epidemiological studies over 70 y ago provided the basis for the use of fluoride in caries prevention. They revealed the clear relation between water fluoride concentration, and therefore fluoride exposure, and prevalence and severity of dental fluorosis and dental caries. After successful trials, programs for water fluoridation were introduced, and industry developed effective fluoride-containing toothpastes and other fluoride vehicles. Reductions in caries experience were recorded in many countries, attributable to the widespread use of fluoride. This is a considerable success story; oral health for many was radically improved. While previously, water had been the only significant source of fluoride, now there are many, and this led to an increase in the occurrence of dental fluorosis. Risks identified for dental fluorosis were ingestion of fluoride-containing toothpaste, water fluoridation, fluoride tablets (which were sometimes ingested in areas with water fluoridation), and infant formula feeds. Policies were introduced to reduce excessive fluoride exposure during the period of tooth development, and these were successful in reducing dental fluorosis without compromising caries prevention. There is now a much better understanding of the public perception of dental fluorosis, with mild fluorosis being of no aesthetic concern. The advantages of water fluoridation are that it provides substantial lifelong caries prevention, is economic, and reduces health inequalities: it reaches a substantial number of people worldwide. Fluoride-containing toothpastes are by far the most important way of delivering the beneficial effect of fluoride worldwide. The preventive effects of conjoint exposure (e.g., use of fluoride toothpaste in a fluoridated area) are additive. The World Health Organization has informed member states of the benefits of the appropriate use of fluoride. Many countries have policies to maximize the benefits of fluoride, but many have yet to do so.

Rodent Dental Fluorosis Model: Extraction of Enamel Organ from Rat Incisors

Chronic fluoride overexposure can cause dental fluorosis. Dental fluorosis is characterized by porous and soft enamel that is vulnerable to erosion and decay. Animal models often contribute to clinical applications by addressing pathogenic questions of disease. To study dental fluorosis, rodent models have been employed because rodent incisors erupt continuously and every stage of enamel development is present along the length of the rodent incisor. Here we present a protocol to induce dental fluorosis in mouse and rat and describe the procedure for extraction of stage specific enamel organ from rat mandibular incisors.

MDM2-Mediated p21 Proteasomal Degradation Promotes Fluoride Toxicity in Ameloblasts

Fluoride overexposure is an environmental health hazard and can cause enamel and skeletal fluorosis. Previously we demonstrated that fluoride increased acetylated-p53 and its downstream target p21 in ameloblast-derived LS8 cells. However, p21 function in fluoride toxicity is not well characterized. This study seeks to gain a better understanding of how p53 down-stream mediators, p21 and MDM2, respond to fluoride toxicity. LS8 cells were treated with NaF with/without MG-132 (proteasome inhibitor) or Nutlin-3a (MDM2 antagonist). NaF treatment for 2-6 h increased phospho-p21, which can inhibit apoptosis. However, phospho-p21 and p21 were decreased by NaF at 24 h, even though p21 mRNA was significantly increased at this time point. MG-132 reversed the fluoride-mediated p21 decrease, indicating that fluoride facilitates p21 proteasomal degradation. MG-132 suppressed fluoride-induced caspase-3 cleavage, suggesting that the proteasome plays a pro-apoptotic role in fluoride toxicity. NaF increased phospho-MDM2 in vitro and in mouse ameloblasts in vivo. Nutlin-3a suppressed NaF-mediated MDM2-p21 binding to reverse p21 degradation which increased phospho-p21. This suppressed apoptosis after 24 h NaF treatment. These results suggest that MDM2-mediated p21 proteasomal degradation with subsequent phospho-p21 attenuation contributes to fluoride-induced apoptosis. Inhibition of MDM2-mediated p21 degradation may be a potential therapeutic target to mitigate fluoride toxicity.

Reasons why low-income people in urban areas do not drink tap water

BACKGROUND

Despite its higher cost and potential environmental effect compared with those of tap water, bottled water consumption has been increasing over the past decade, especially in low-income communities in which children are at a higher risk of developing caries.

METHODS

The authors used a systematic sequential sampling design for the Water Consumption Survey to collect information about water consumption beliefs and practices from clients attending 4 public health centers in Los Angeles County (LAC). The authors used health belief model constructs to examine why some low-income residents in LAC do not drink tap water.

RESULTS

From October through December 2013, 1,230 participants completed the Water Consumption Survey (86% response rate); the authors included 1,171 participants in the final analysis. Hispanic and African-American participants accounted for the largest proportions (38% and 37%, respectively). Overall, 48% of participants reported drinking tap water daily compared with 58% who reported drinking bottled water daily. The health belief model construct of perceived health risks (that is, perceived threats) significantly predicted why survey participants did not drink tap water. Other results revealed several misconceptions about tap water fluoridation and differences in beliefs about tap water safety according to income level.

CONCLUSIONS

Fluoridated tap water is a low-cost, ecologically friendly resource that provides health benefits seldom found in bottled water. However, mistrust about the quality and safety of tap water may make those in low-income communities more vulnerable to the effects of not receiving adequate fluoride and thus at higher risk of developing caries.

PRACTICAL IMPLICATIONS

Future interventions should encourage tap water use by dispelling misconceptions and educating low-income people in urban areas of LAC about the health benefits of fluoridated tap water and the safety of its sources. In addition, patient encounters could be an opportunity for pediatric dentists, general dentists, and other health care providers to reinforce the health benefits of tap water fluoridation and its use.

Fluoridation and county-level secondary bone cancer among cancer patients 18 years or older in New York State

The decision whether to fluoridate drinking water continues to be controversial in some communities. Dental and skeletal fluorosis in response to chronic fluoride overexposure are cited as reasons to avoid community water fluoridation in spite of evidence of the oral and skeletal health benefits fluoridation confers. Community fluoridation of ~ 1 mg/L fluoride has not been found to be associated with primary bone cancer but is associated with improved bone strength. No studies have examined fluoride exposure and secondary bone cancer, a common metastasis with significant morbidity. We hypothesize that fluoridation could diminish the likelihood of secondary bone cancer due to its role in bone fortification. We examined the association between community water fluoridation category and prevalence of secondary bone cancer from 2008 to 2010 among cancer patients of 18 years of age or older in counties in New York State. Relative to counties with less than 25% of the water supply fluoridated, we report no association between secondary bone cancer among cancer patients in counties with 25-75% of the water supply fluoridated (β = 0.02, p = 0.96) and among those in counties with > 75% fluoridated (β = 0.02, p = 0.97). We found no evidence of an association between community water fluoridation category and secondary bone cancer from 2008 to 2010 at the county level in New York State.

Evaluation of Physicochemical Characteristics in Drinking Water Sources Emphasized on Fluoride: A Case Study of Yancheng, China

In this study, the concentration of fluoride and the associated health risks for infants, children, and adults were analyzed and compared for three drinking water sources in Yancheng City, Jiangsu Province, China. To analyze the relationship between the water quality parameters of pH, fluoride (F⁻), sulfate (SO₄²⁻), chloride (Cl⁻), total dissolved solids (TDS), total alkalinity (TAlk), sodium (Na⁺), and potassium (K⁺), statistical analyses including correlation analysis, R-mode cluster analysis and factor analysis were performed based on monthly data from the year 2010 to 2015. The results indicated: (1) Fluoride concentrations in the drinking water sources ranged from 0.38 to 1.00 mg L⁻¹ (mean = 0.57 mg L⁻¹) following the order of Tongyu River > Yanlong Lake > Mangshe River; (2) fluoride concentrations in 22.93% of the collected samples were lower than 0.5 mg L⁻¹, which has the risk of tooth cavities, especially for the Mangshe River; (3) the fluoride exposure levels of infants were higher than children and adults, and 3.2% of the fluoride exposure levels of infants were higher than the recommended toxicity reference value of 122 μg kg⁻¹ d⁻¹ as referenced by Health Canada, which might cause dental fluorosis issues; (4) the physico-chemical characteristics are classified the into four groups reflecting F⁻- TAlk, Na⁺-K⁺, SO₄²⁻-Cl⁻, and pH-TDS, respectively, indicating that fluoride solubility in drinking water is TAlk dependent, which is also verified by R-mode cluster analysis and factor analysis. The results obtained supply useful information for the health department in Yancheng City, encouraging them to pay more attention to fluoride concentration and TAlk in drinking water sources.

Advocating for Oral Health Through Fluoridation

Eight school nurses attended the American Academy of Pediatrics' Campaign for Dental Health meeting in March 2018, which focused on community water fluoridation programs. Because of aging infrastructure and antifluoridation community activists, some communities are considering stopping fluoridation programs. The benefits of water fluoridation have been demonstrated since the 1950s. School nurses can play a vital role in advocating for evidence-based fluoridation programs within their community. This article informs the school nurse on the benefits of water fluoridation for promoting community health and methods to advocate for those measures-key practice components of the leadership and community/public health principles of "Framework for 21st Century School Nursing Practice™."

Dental Fluorosis Trends in US Oral Health Surveys: 1986 to 2012

Introduction:

Dental fluorosis has been assessed only 3 times in nationally representative oral health surveys in the United States. The first survey was conducted by the National Institute of Dental Research from 1986 to 1987. Subsequently, the National Health and Nutrition Examination Survey (NHANES) conducted fluorosis assessments from 1999 to 2004 and more recently from 2011 to 2012. A large increase in prevalence and severity of fluorosis occurred between the 1986–1987 and 1999–2004 surveys.

Objectives:

To determine whether the trend of increasing fluorosis continued in the 2011–2012 survey.

Methods:

We analyzed publicly available data from the 2011–2012 NHANES, calculating fluorosis prevalence and severity using 3 measures: person-level Dean’s Index score, total prevalence of those with Dean’s Index of very mild degree and greater, and Dean’s Community Fluorosis Index. We examined these fluorosis measures by several sociodemographic factors and compared results with the 2 previous surveys. Analyses accounted for the complex design of the surveys to provide nationally representative estimates.

Results:

Large increases in severity and prevalence were found in the 2011–2012 NHANES as compared with the previous surveys, for all sociodemographic categories. For ages 12 to 15 y—an age range displaying fluorosis most clearly—total prevalence increased from 22% to 41% to 65% in the 1986–1987, 1999–2004, and 2011–2012 surveys, respectively. The rate of combined moderate and severe degrees increased the most, from 1.2% to 3.7% to 30.4%. The Community Fluorosis Index increased from 0.44 to 0.67 to 1.47. No clear differences were found in fluorosis rates among categories for most of the sociodemographic variables in the 2011–2012 survey.

Conclusion:

Large increases in fluorosis prevalence and severity occurred. We considered several possible spurious explanations for these increases but largely ruled them out based on counterevidence. We suggest several possible real explanations for the increases.

Knowledge Transfer Statement:

The results of this study greatly increase the evidence base indicating that objectionable dental fluorosis has increased in the United States. Dental fluorosis is an undesirable side effect of too much fluoride ingestion during the early years of life. Policy makers and professionals can use the presented evidence to weigh the risks and benefits of water fluoridation and early exposure to fluoridated toothpaste.

Use of Toothpaste and Toothbrushing Patterns Among Children and Adolescents - United States, 2013-2016

Fluoride use is one of the main factors responsible for the decline in prevalence and severity of dental caries and cavities (tooth decay) in the United States (1). Brushing children's teeth is recommended when the first tooth erupts, as early as 6 months, and the first dental visit should occur no later than age 1 year (2-4). However, ingestion of too much fluoride while teeth are developing can result in visibly detectable changes in enamel structure such as discoloration and pitting (dental fluorosis) (1). Therefore, CDC recommends that children begin using fluoride toothpaste at age 2 years. Children aged <3 years should use a smear the size of a rice grain, and children aged >3 years should use no more than a pea-sized amount (0.25 g) until age 6 years, by which time the swallowing reflex has developed sufficiently to prevent inadvertent ingestion. Questions on toothbrushing practices and toothpaste use among children and adolescents were included in the questionnaire component of the National Health and Nutrition Examination Survey (NHANES) for the first time beginning in the 2013-2014 cycle. This study estimates patterns of toothbrushing and toothpaste use among children and adolescents by analyzing parents' or caregivers' responses to questions about when the child started to brush teeth, age the child started to use toothpaste, frequency of toothbrushing each day, and amount of toothpaste currently used or used at time of survey. Analysis of 2013-2016 data found that >38% of children aged 3-6 years used more toothpaste than that recommended by CDC and other professional organizations. In addition, nearly 80% of children aged 3-15 years started brushing later than recommended. Parents and caregivers can play a role in ensuring that children are brushing often enough and using the recommended amount of toothpaste.

Early childhood caries and oral health care of Hong Kong preschool children

Surveys have shown that the prevalence of early childhood caries (ECC) among 5-year-old children decreased from 63% in 1993 to 55% in 2017. Caries experience was unevenly distributed; 81% of the caries lesions were found in 26% of the children. Risk factors, including oral hygiene practice behaviors, sugar consumption, parental oral health-related knowledge, and sociodemographic backgrounds, were significantly related to ECC. Oral health promotion aimed at managing the burden of ECC has been implemented. Water fluoridation was launched in 1961, and the fluoride concentration has been adjusted to 0.5 ppm since 1988. It is considered an important dental public health measure in Hong Kong. The Department of Health set up the Oral Health Education Unit in 1989 to deliver oral health education to further improve the oral health of preschool children. Other nongovernmental organizations also launched short-term oral health promotion programs for preschool children. However, no significant change in the prevalence of ECC has been observed in the recent two decades. There is a necessity to revisit dental public health policies and develop effective evidence-based strategies to encourage changes in oral health-related behaviors to forestall the impending epidemic of ECC in Hong Kong.

Global oral health in the framework of the Global Charter for the Public's Health

Oral diseases are a neglected epidemic affecting all ages globally and can substantially impact overall health and well-being. Even though most oral diseases are preventable and share major risk factors with other non-communicable diseases, integration of oral health into public health systems is still limited in both clinical and health policy perspectives. This Viewpoint aims to highlight oral health from a global health perspective, calling for all public health leaders to advocate for oral health of all. We strongly recommend oral health as an essential part of public health policy and oral health-related activities to be aligned with the Global Charter for the Public's Health Framework.

Fluoride and Thyroid Function in Children Resident of Naturally Fluoridated Areas Consuming Different Levels of Fluoride in Drinking Water: An Observational Study

Background:

Literature shows association between systemic fluorides and endocrine disorders especially related to thyroid, with lack of clarity.

Aims and Objectives:

The aim and objective of this study was to estimate serum triiodothyronine (T3), thyroxin, thyroid-stimulating hormone (TSH), fluoride, calcium, phosphate, and alkaline phosphatase levels among children with normal nutritional status and optimal iodine intake residing in three different ranges of drinking water fluoride levels.

Materials and Methods:

The present double-blinded, observational trial comprised of 293 children aged between 9 and 13 years consuming naturally fluoridated water of three different ranges: Group I: 0.01–0.6 parts per million (ppm), Group II: 0.7–1.2 ppm, and Group III: 1.3–1.8 ppm. For each child's demographic data, body mass index and Clinical Fluorosis Index were recorded along with serum T3, T4, TSH, fluoride, calcium, phosphate, and serum alkaline phosphatase levels. Data were analyzed using Chi–square test, Kruskal–Wallis test, and repeated measures ANOVA with SPSS 23.

Results:

For serum TSH levels, 40% of children in Group I had deranged levels followed by Group III (20%) and Group II (16%). For serum T4 levels, 24% of children of both Groups I and III had deranged levels followed by Group II (20%). Intergroup correlation of drinking water fluoride levels to the number of deranged serum T3, T4, and TSH of the children showed nonsignificant association. Serum T3, calcium, phosphate, and alkaline phosphatase levels in all children showed values falling within normal range.

Conclusion:

According to the present study results, long-term intake of fluoridated drinking water (0.02–1.4 ppm) did not show effect on the thyroid function in children with normal nutritional status and optimal iodine intake.

Dental Cleaning, Community Water Fluoridation and Preterm Birth, Massachusetts: 2009-2016

Objectives Data on the potential effect of dental cleaning and community water fluoridation (CWF) on pregnancy outcomes are scarce. While numerous studies confirm the cost-effectiveness of fluoride in preventing dental caries, the benefit of CWF during pregnancy has not been well established. Methods This cross-sectional study used data from 2009 to 2016 Massachusetts Pregnancy Risk Assessment Monitoring System and restricted to singleton live births (n = 9234, weighted response rate = 64.3%). Our exposures were: (1) dental cleaning alone during pregnancy; (2) CWF alone; and (3) dental cleaning and CWF combined (DC-CWF). Women without dental cleaning during pregnancy and CWF comprised our reference group. The outcome was preterm birth, (birth < 37 weeks gestation). This study used multivariate logistic regression modeling, controlling for maternal sociodemographic characteristics, previous medical risk and behavioral factors, and calculated adjusted risk ratios (aRRs) and 95% confidence intervals (CIs). Results During 2009-2016, the prevalence of preterm birth among women with a singleton live birth was 8.5% in Massachusetts. Overall, 58.7% of women had dental cleaning during pregnancy, and 63.6% lived in CWF. After adjusting for potential confounders, the associations between dental cleaning alone and preterm birth (aRR = 0.74 [95% CI 0.55-0.98]), and DC-CWF and preterm birth (aRR = 0.74 [95% CI 0.57-0.95]) were significant, while the association between CWF alone and preterm birth was not significant (aRR = 0.81 [95% CI 0.63-1.05]), compared to women without dental cleaning and CWF. Conclusions for Practice This study shows that the prevalence of preterm birth was lower among women with DC only and DC-CWF.

Consequences of community water fluoridation cessation for Medicaid-eligible children and adolescents in Juneau, Alaska

BACKGROUND

The general aim of this research was to determine whether cessation of community water fluoridation (CWF) increased oral health disparities, as measured by dental caries procedures and restoration costs for children and adolescents.

METHODS

The analysis was based on all Medicaid dental claims records of 0- to 18-year-old patients residing in zip code 99801 (Juneau, Alaska) during an optimal CWF year (2003, n = 853) compared to all claims for the same age group from 2012 (n = 1052), five years after cessation of CWF. A bivariate analysis (Mann-Whitney U test) of the mean number of caries procedures performed per client was conducted in the study groups under both independent CWF conditions. Furthermore, logistic regression was performed using the dependent variables of caries procedures and the cost of caries-related procedures, with adjustments for CWF group, gender, and race.

RESULTS

The statistically significant results included a higher mean number of caries-related procedures among 0- to 18-year-old and < 7-year-old patients in the suboptimal CWF group (2.35 vs. 2.02, p < 0.001; 2.68 vs. 2.01, p = 0.004, respectively). The mean caries-related treatment costs per patient were also significantly higher for all age groups, ranging from a 28 to 111% increase among the suboptimal CWF cohorts after adjusting for inflation. The binary logistic regression analysis results indicated a protective effect of optimal CWF for the 0- to 18-year-old and < 7-year-old age groups (OR = 0.748, 95% CI [0.62, 0.90], p = 0.002; OR = 0.699, 95% CI [0.52, 0.95], p = 0.02, respectively). Additionally, the age group that underwent the most dental caries procedures and incurred the highest caries treatment costs on average were those born after CWF cessation.

CONCLUSIONS

These results expand our understanding of caries epidemiology under CWF cessation conditions and reaffirm that optimal CWF exposure prevents dental decay. These findings can offer fiscal estimates of the cost burden associated with CWF cessation policies and help decision-makers advance oral health, prevent dental caries, and promote equity in oral health outcomes.

Oral Development and Pathology

Background

The mouth is integral in the development of feeding, the initiation of digestion, and for speech and socialization. Signs of systemic disease and nutritional deficiencies often manifest in the mouth, and poor oral health can exacerbate many systemic conditions.

Methods

This review addresses the fetal development of the mouth, major anomalies, common minor physical findings, and pathologic conditions and their management.

Results

Pediatric practitioners have historically been poorly trained in diagnosis and management of oral conditions, so this article provides an overview of oral embryology and pathology, with a focus on hard and soft tissue disease identification, triage, and management. For primary prevention to be effective, pediatric providers must be knowledgeable about the process of dental caries, prevention of the disease, and available interventions, including fluoride.

Conclusion

The embryology and anatomy of the oral cavity are complex, and the mouth is crucial to many physiologic processes. Pediatric primary care providers are uniquely positioned to prevent, identify, and triage dental caries, the most common chronic disease of childhood.

NaF Reduces KLK4 Gene Expression by Decreasing Foxo1 in LS8 Cells

Decreased expression and increased phosphorylation of Forkhead box o1 (Foxo1) in ameloblasts were observed both in vivo and in vitro when treated by fluoride. The present study aims to investigate the possible relationship between Foxo1 and enamel matrix proteinases, matrix metalloproteinase 20 (MMP20), and kallikrein 4 (KLK4), in NaF-treated ameloblasts. Ameloblast-like cells (LS8 cells) were exposed to NaF at selected concentration (0/2 mM) for 24 h. Gene overexpression and silencing experiments were used to up- and down-regulate Foxo1 expression. The expression levels of Foxo1, MMP20, and KLK4 were detected by quantitative real-time PCR and western blot. Dual luciferase reporter assay was performed to evaluate the regulation of Foxo1 on the transcriptional activity of KLK4 promoter. The results showed that KLK4 expression was decreased in LS8 cells treated by NaF, while MMP20 expression was not changed. Foxo1 activation led to significantly up-regulation of KLK4 in LS8 cells under NaF condition. Knockout of Foxo1 markedly decreased klk4 expression in mRNA level, and intensified inhibition occurred in LS8 cells when combined with NaF treatment. However, the variation trend of MMP20 was not clear. Dual luciferase reporter assay showed that Foxo1 activation enhanced the transcriptional activity of KLK4 promoter. These findings suggest that the decrease of Foxo1 expression induced by high fluoride was a cause for low KLK4 expression.

Age-sex specific and sequela-specific disability-adjusted life years (DALYs) due to dental caries preventable through water fluoridation: An assessment at the national and subnational levels in Iran, 2016

We assessed disability-adjusted life years (DALYs) due to dental caries preventable through water fluoridation apportioned by sex, age group, sequela, province, and community type in Iran, 2016. The burden of disease due to dental caries was extracted from the Global Burden of Disease Study 2016 (GBD 2016) and the caries preventive effect of water fluoridation was calculated using a database of fluoride levels in drinking water. All the preventable DALYs were caused by years lived with disability (YLDs) because of the non-fatal character of dental caries. DALYs and DALY rate (per 100,000 people) preventable through water fluoridation at the national level in 2016 were 14,971 (95% uncertainty interval 7348- 24,725) and 18.73 (9.19-30.93), respectively. The national population preventable fraction (PPF) of dental caries by water fluoridation was determined to be as high as 0.176 (0.141-0.189). The share of sequelae in the preventable DALYs at the national level were estimated to be 76.8% for edentulism and severe tooth loss, 21.4% for caries of permanent teeth, and 1.8% for caries of deciduous teeth. The national DALYs and DALY rate preventable through water fluoridation exhibited no difference by sex, but considerably increased by age from 110 (37-223) and 1.5 (0.5-3.1) for the age group 0-4 y to 4331 (2334-6579) and 88.9 (47.9-135.1) for the age group 65 y and older, respectively. Over 80% of the national preventable DALYs occurred in urban areas due to higher population and lower coverage of fluoridated drinking water. The highest provincial DALYs and DALY rate preventable by water fluoridation were observed in Tehran and Gilan to be 3776 (1866-6206) and 37.2 (18.6-60.8), respectively. The results indicated that water fluoridation can play a profound role in the promotion of dental public health and compensate the spatial inequality and increasing temporal trend of health losses from dental caries at the national level.

Existing Regulatory Approaches to Reducing Exposures to Chemical- and Product-Based Risk and Their Applicability to Diet-Related Chronic Disease

We aimed to identify and categorize the types of policies that have been adopted to protect Americans from harmful exposures that could also be relevant for addressing diet-related chronic diseases. This article examines and categorizes the rationales behind government regulation. Our interest in the historical analysis is to inform judgments about how best to address newly emergent risks involving diet-related chronic disease within existing regulatory and information-based frameworks. We assessed exemplars of regulation with respect to harmful exposures from air, water, and food, as well as regulations that are intended to modify voluntary behaviors. Following the comparative analysis, we explored how exposures that lead to diet-related chronic diseases among the general population fit within models of regulation adopted for other comparable risks. We identified five rationales and five approaches that protect people from harmful exposures. Reasons for regulation include: protection from involuntary exposure to risk, high risk of death or chronic illness, ubiquity of risk, counteraction to limit compulsive behaviors, and promotion of population health. Regulatory approaches include: mandatory limits on use, mandatory limits on exposure, mandatory controls on quality, mandatory labeling, and voluntary guidance. In contrast to the use of mandates, the prevention of diet-related chronic diseases thus far has largely relied on information-only approaches and voluntary adoption of guidelines. There is ample precedent for mandatory regulatory approaches that could address harms related to exposure to unhealthy diets, but several barriers to action would need to be overcome.

Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada

BACKGROUND

Fluoride exposures have not been established for pregnant women who live in regions with and without community water fluoridation.

OBJECTIVE

Our aim was to measure urinary fluoride levels during pregnancy. We also assessed the contribution of drinking-water and tea consumption habits to maternal urinary fluoride (MUF) concentrations and evaluated the impact of various dilution correction standards, including adjustment for urinary creatinine and specific gravity (SG).

METHODS

We measured MUF concentrations in spot samples collected in each trimester of pregnancy from 1,566 pregnant women in the Maternal-Infant Research on Environmental Chemicals cohort. We calculated intraclass correlation coefficients (ICCs) to assess variability in MUF concentrations across pregnancy. We used regression analyses to estimate associations between MUF levels, tea consumption, and water fluoride concentrations as measured by water treatment plants.

RESULTS

Creatinine-adjusted MUF values ([Formula: see text]; milligrams per liter) were almost two times higher for pregnant women living in fluoridated regions ([Formula: see text]) compared with nonfluoridated regions ([Formula: see text]; [Formula: see text]). MUF values tended to increase over the course of pregnancy using both unadjusted values and adjusted values. Reproducibility of the unadjusted and adjusted MUF values was modest ([Formula: see text]). The municipal water fluoride level was positively associated with creatinine-adjusted MUF ([Formula: see text], 95% CI: 0.46, 0.57), accounting for 24% of the variance after controlling for covariates. Higher MUF concentrations correlated with numbers of cups of black ([Formula: see text] but not green tea ([Formula: see text]). Urinary creatinine and SG correction methods were highly correlated ([Formula: see text]) and were interchangeable in models examining predictors of MUF.

CONCLUSION

Community water fluoridation is a major source of fluoride exposure for pregnant women living in Canada. Urinary dilution correction with creatinine and SG were shown to be interchangeable for our sample of pregnant women. https://doi.org/10.1289/EHP3546.