The relationship between dental fluorosis and alterations in the salivary proteome remains inadequately elucidated. This study aimed to investigate the salivary proteome and fluoride concentrations in urine and drinking water among Thai individuals afflicted with severe dental fluorosis. Thirty-seven Thai schoolchildren, aged 6-16, were stratified based on Thylstrup and Fejerskov fluorosis index scores: 10 with scores ranging from 5 to 9 (SF) and 27 with a score of 0 (NF). Urinary and water fluoride levels were determined using an ion-selective fluoride electrode. Salivary proteomic profiling was conducted via LC-MS/MS, followed by comprehensive bioinformatic analysis. Results revealed significantly elevated urinary fluoride levels in the SF group (p = 0.007), whereas water fluoride levels did not significantly differ between the two cohorts. Both groups exhibited 104 detectable salivary proteins. The NF group demonstrated notable upregulation of LENG9, whereas the SF group displayed upregulation of LDHA, UBA1, S100A9, H4C3, and LCP1, all associated with the CFTR ion channel. Moreover, the NF group uniquely expressed 36 proteins, and Gene Ontology and pathway analyses suggested a link with various aspects of immune defense. In summary, the study hypothesized that the CFTR ion channel might play a predominant role in severe fluorosis and highlighted the depletion of immune-related salivary proteins, suggesting compromised immune defense in severe fluorosis. The utility of urinary fluoride might be a reliable indicator for assessing excessive fluoride exposure.

OBJECTIVE: To identify the potential metabolic biomarkers of fluorosis and the pathogenesis of fluorosis.
METHODS: Sprague Dawley rats in this study were randomly divided into fluoride exposure and control groups. In the fluoride exposure group, six offspring rats without dental fluorosis were defined as group A, and six offspring rats with dental fluorosis were defined as group C. Eight offspring rats in the control group were defined as group B. The metabolites in plasma were determined using GC-MS, with differential metabolites (DMs) identified using VIP > 1, and P < 0.05. Cluster analysis, KEGG pathway enrichment analysis and Receiver Operating Characteristic (ROC) analysis were subsequently performed. The DMs which were caused by fluoride exposure in the previous study were used to verify our results. The GSE70719 from GEO database were used to support this research at the mRNA level and in vitro experiment were selected to verify above results.
RESULTS: The 13 up-regulated and 4 down-regulated DMs were identified in the group A + C, the 18 up-regulated and 4 down-regulated DMs were identified in group A, and the 12 up-regulated and 2 down-regulated DMs were identified in group C. All groups showed enrichment in Aminoacyl-tRNA synthesis, D-glutamine and D-glutamate metabolism, Nitrogen metabolism, and Purine metabolism pathways. ROC analysis revealed that L-glutamine had excellent diagnostic ability for fluorosis (AUC > 0.85, P < 0.05). Changes in major DMs (L-glutamine, 4-hydroxyproline and L-alanine) were consistent with previous findings. Transcriptomic results showed the significant alteration of GLS gene in the fluoride exposure group. In vitro experiments confirmed decreased GLS and SLC1A5 genes expression.
CONCLUSIONS: L-glutamine emerges as a potential biomarker for fluorosis. Glutamine metabolism was involved in the pathogenesis of fluorosis.

BACKGROUND: Numerous approaches have been adopted to evaluate limited freshwater resources and the associated health hazards due to excessive amounts of fluoride in drinking water. The study aims to assess the degree and severity of dental and skeletal fluorosis and examine the broader effects of fluorosis on human health and society in the Manbhum-Singhbhum Plateau region, India.
METHODS: The Community Fluorosis Index (CFI) and Dean\'s Index have been used to measure the magnitude and severity of dental and skeletal fluorosis. Questionnaire surveys, Focus Group Discussions (FGDs), and appropriate statistical methods have been applied to identify the social impacts. Risk-prone zones have been identified through overlay analysis using geoinformatics.
RESULTS: About 54.60% of people in 67 villages of this part of the Manbhum-Singhbhum Plateau are affected in varying degrees of fluorosis ranging from very mild to mild, moderate, and severe dental fluorosis. Among these 67 villages, Janra (Manbazar I) and Hijla (Barabazar) have the most severely affected people. School dropout (n = 426), social isolation (n = 149), remarriage (n = 21), and physically disabled (n = 75) have also been reported. The study shows that about 414.29 km2 of the Manbhum-Singhbhum Plateau comes under the high-risk-prone category.
CONCLUSIONS: The societal and environmental awareness of the fluorosis-affected individuals is almost absent in this region. Economic hardships, lack of education, inadequate health care facilities, water scarcity, and lack of awareness increase the magnitude of health hazards and societal vulnerability of the people in this region, who are largely dependent on natural resources.

OBJECTIVE: This study aimed to compare the impact of case-based learning (CBL) versus lecture-based learning (LBL) on dental students\' clinical decision-making regarding DF severity using Visual Analog Scale (VAS) scoring.
METHODS: Eighty first-year graduate dental students were randomly assigned to either the CBL (n = 38) or LBL (n = 42) groups. Both groups received instruction on DF diagnosis, with CBL involving small group sessions analyzing real cases and LBL involving traditional lectures. Effectiveness was assessed by presenting 32 dental fluorosis cases with Thylstrup-Fejerskov Index (TSIF) scores ranging from 0 to 7 through slide presentations to both groups for VAS assessment. Five evaluators of each group randomly selected were asked to repeat the rating 2 weeks later. Statistical analysis included two-way ANOVA for group and gender differences, intra-class correlation coefficient (ICC) for reliability, and Spearman correlation coefficients for validity.
RESULTS: Variations in VAS scores were observed between CBL and LBL groups, with no significant gender impact. Excellent inter- and intra-evaluator agreement was found for VAS scoring in both groups, indicating its reliability. Validation against established indices (such as DI and TSIF) demonstrated strong correlations, with CBL students exhibiting higher correlations.
CONCLUSIONS: CBL enhances students\' clinical decision-making and proficiency in DF diagnosis, as evidenced by more consistent and accurate VAS scoring compared to LBL. These findings highlight the importance of innovative educational strategies in dental curricula, with implications for improving training quality and clinical outcomes.
BACKGROUND: The study was registered at the Clinical Research Center, Hospital of Stomatology, Wuhan University (Registration code: HGGC-036).

OBJECTIVE: To study the damage and the expression of LC3 and p62 of condylar cartilage in fluorosis mouse.
METHODS: Thirty 4-week-old male C57BL/6 mice were randomly divided into control group and the experimental group with 15 animals in each group. The control group received regular drinking water and the experimental group received a fluoride concentration of 75 mg/L drinking water for 8 weeks. The structure of condylar cartilage was observed through modified safranine O-fast green FCF cartilage stain kit. Immunohistochemistry was used to detect the expression of MMP-13, type Ⅱ collagen and LC3 and p62. Two-way analysis of variance test was conducted for analysis of semi-quantitative results of immunohistochemistry using SPSS 22.0 software package.
RESULTS: Compared with the control group, the fibrocartilage layer of the experimental group became thinner, the condrocytes were smaller, and the staining became deeper.Immunohistochemistry results showed that the expression of MMP-13 and LC3 increased; the expression of type Ⅱ collagen and p62 decreased in the experimental group.
CONCLUSIONS: There was degeneration of the condylar cartilage and autophagy in mice with drinking water containing 75 mg/L fluoride.

Consumption of fluoride-contaminated water is a worldwide concern, especially in developing countries, including Iran. However, there are restricted studies of non-single-value health risk assessment and the disease burden regarding fluoride intake nationwide. Prolonged exposure to excessive fluoride has been linked to adverse health effects such as dental and skeletal fluorosis. This can lead to under-mineralization of hard tissues, causing aesthetic concerns for teeth and changes in bone structure, increasing the risk of fractures. As such, we aimed to implement probability-based frameworks using Monte Carlo methods to explore the potential adverse effects of fluoride via the ingestion route. This platform consists of two sectors: 1) health risk assessment of various age categories coupled with a variance decomposition technique to measure the contributions of predictor variables in the outcome of the health risk model, and 2) implementing Monte Carlo methods in dose-response curves to explore the fluoride-induced burden of diseases of dental fluorosis and skeletal fractures in terms of disability-adjusted life years (DALYs). For this purpose, total water samples of 8053 (N=8053) from 57 sites were analyzed in Fars and Bushehr Provinces. The mean fluoride concentrations were 0.75 mg/L and 1.09 mg/L, with maximum fluoride contents of 6.5 mg/L and 3.22 mg/L for the Fars and Bushehr provinces, respectively. The hazard quotient of the 95th percentile (HQ>1) revealed that all infants and children in the study area were potentially vulnerable to over-receiving fluoride. Sobol\' sensitivity analysis indices, including first-order, second-order, and total order, disclosed that fluoride concentration (Cw), ingestion rate (IRw), and their mutual interactions were the most influential factors in the health risk model. DALYs rate of dental fluorosis was as high as 981.45 (uncertainty interval: UI 95 % 353.23-1618.40) in Lamerd, and maximum DALYs of skeletal fractures occurred in Mohr 71.61(49.75-92.71), in Fars Province, indicated severe dental fluorosis but mild hazard regarding fractures. Residents of the Tang-e Eram in Bushehr Province with a DALYs rate of 3609.40 (1296.68-5993.73) for dental fluorosis and a DALYs rate of 284.67 (199.11-367.99) for skeletal fractures were the most potentially endangered population. By evaluating the outputs of the DALYs model, the gap in scenarios of central tendency exposure and reasonable maximum exposure highlights the role of food source intake in over-receiving fluoride. This research insists on implementing defluoridation programs in fluoride-endemic zones to combat the undesirable effects of fluoride. The global measures presented in this research aim to address the root causes of contamination and help policymakers and authorities mitigate fluoride\'s harmful impacts on the environment and public health.

Fluoride is a double-edged sword. It was widely used for early caries prevention while excessive intake caused a toxicology effect, affected enamel development, and resulted in dental fluorosis. The study aimed to evaluate the protective effect and mechanism of Epigallocatechin-3-gallate (EGCG) on the apoptosis induced by fluoride in ameloblast-like cells. We observed that NaF triggered apoptotic alterations in cell morphology, excessive NaF arrested cell cycle at the G1, and induced apoptosis by up-regulating Bax and down-regulating Bcl-2. NaF activated the insulin-like growth factor receptor (IGFR), and phosphatidylinositol-3-hydroxylase (p-PI3K), while dose-dependently down-regulating the expression of Forkhead box O1 (FoxO1). EGCG supplements reversed the changes in LS8 morphology, the cell cycle, and apoptosis induced by fluoride. These results indicated that EGCG possesses a protective effect against fluoride toxicity. Furthermore, EGCG suppressed the activation of p-PI3K and the down-regulation of FoxO1 caused by fluoride. Collectively, our findings suggested that EGCG attenuated fluoride-induced apoptosis by inhibiting the PI3K/FoxO1 signaling pathway. EGCG may serve as a new alternative method for dental fluorosis prevention, control, and treatment.

This is an update of a review first published in 2010. Use of topical fluoride has become more common over time. Excessive fluoride consumption from topical fluorides in young children could potentially lead to dental fluorosis in permanent teeth.
To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis in permanent teeth.
We carried out electronic searches of the Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase, three other databases, and two trials registers. We searched the reference lists of relevant articles. The latest search date was 28 July 2022.
We included randomized controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies, and cross-sectional surveys comparing fluoride toothpaste, mouth rinses, gels, foams, paint-on solutions, and varnishes to a different fluoride therapy, placebo, or no intervention. Upon the introduction of topical fluorides, the target population was children under six years of age.
We used standard methodological procedures expected by Cochrane and used GRADE to assess the certainty of the evidence. The primary outcome measure was the percentage prevalence of fluorosis in the permanent teeth. Two authors extracted data from all included studies. In cases where both adjusted and unadjusted risk ratios or odds ratios were reported, we used the adjusted value in the meta-analysis.
We included 43 studies: three RCTs, four cohort studies, 10 case-control studies, and 26 cross-sectional surveys. We judged all three RCTs, one cohort study, one case-control study, and six cross-sectional studies to have some concerns for risk of bias. We judged all other observational studies to be at high risk of bias. We grouped the studies into five comparisons. Comparison 1. Age at which children started toothbrushing with fluoride toothpaste Two cohort studies (260 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing at or before 12 months versus after 12 months and the development of fluorosis (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.81 to 1.18; very low-certainty evidence). Similarly, evidence from one cohort study (3939 children) and two cross-sectional studies (1484 children) provided very uncertain evidence regarding the association between children starting to use fluoride toothpaste for brushing before or after the age of 24 months (RR 0.83, 95% CI 0.61 to 1.13; very low-certainty evidence) or before or after four years (odds ratio (OR) 1.60, 95% CI 0.77 to 3.35; very low-certainty evidence), respectively. Comparison 2. Frequency of toothbrushing with fluoride toothpaste Two case-control studies (258 children) provided very uncertain evidence regarding the association between children brushing less than twice per day versus twice or more per day and the development of fluorosis (OR 1.63, 95% CI 0.81 to 3.28; very low-certainty evidence). Two cross-sectional surveys (1693 children) demonstrated that brushing less than once per day versus once or more per day may be associated with a decrease in the development of fluorosis in children (OR 0.62, 95% CI 0.53 to 0.74; low-certainty evidence). Comparison 3. Amount of fluoride toothpaste used for toothbrushing Two case-control studies (258 children) provided very uncertain evidence regarding the association between children using less than half a brush of toothpaste, versus half or more of the brush, and the development of fluorosis (OR 0.77, 95% CI 0.41 to 1.46; very low-certainty evidence). The evidence from cross-sectional surveys was also very uncertain (OR 0.92, 95% CI 0.66 to 1.28; 3 studies, 2037 children; very low-certainty evidence). Comparison 4. Fluoride concentration in toothpaste There was evidence from two RCTs (1968 children) that lower fluoride concentration in the toothpaste used by children under six years of age likely reduces the risk of developing fluorosis: 550 parts per million (ppm) fluoride versus 1000 ppm (RR 0.75, 95% CI 0.57 to 0.99; moderate-certainty evidence); 440 ppm fluoride versus 1450 ppm (RR 0.72, 95% CI 0.58 to 0.89; moderate-certainty evidence). The age at which the toothbrushing commenced was 24 months and 12 months, respectively. Two case-control studies (258 children) provided very uncertain evidence regarding the association between fluoride concentrations under 1000 ppm, versus concentrations of 1000 ppm or above, and the development of fluorosis (OR 0.89, 95% CI 0.52 to 1.52; very low-certainty evidence). Comparison 5. Age at which topical fluoride varnish was applied There was evidence from one RCT (123 children) that there may be little to no difference between a fluoride varnish application before four years, versus no application, and the development of fluorosis (RR 0.77, 95% CI 0.45 to 1.31; low-certainty evidence). There was low-certainty evidence from two cross-sectional surveys (982 children) that the application of topical fluoride varnish before four years of age may be associated with the development of fluorosis in children (OR 2.18, 95% CI 1.46 to 3.25).
Most evidence identified mild fluorosis as a potential adverse outcome of using topical fluoride at an early age. There is low- to very low-certainty and inconclusive evidence on the risk of having fluorosis in permanent teeth for: when a child starts receiving topical fluoride varnish application; toothbrushing with fluoride toothpaste; the amount of toothpaste used by the child; and the frequency of toothbrushing. Moderate-certainty evidence from RCTs showed that children who brushed with 1000 ppm or more fluoride toothpaste from one to two years of age until five to six years of age probably had an increased chance of developing dental fluorosis in permanent teeth. It is unethical to propose new RCTs to assess the development of dental fluorosis. However, future RCTs focusing on dental caries prevention could record children\'s exposure to topical fluoride sources in early life and evaluate the dental fluorosis in their permanent teeth as a long-term outcome. In the absence of these studies and methods, further research in this area will come from observational studies. Attention needs to be given to the choice of study design, bearing in mind that prospective controlled studies will be less susceptible to bias than retrospective and uncontrolled studies.

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.
CONCLUSIONS: 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.

METHODS: Human, animal, and in vitro studies. Extensive literature search of multiple bibliographic databases, trial registries, major grey literature sources and bibliographies of identified studies.
METHODS: The authors aimed to identify studies which could be used to determine the maximum safe level for fluoride in drinking water. To identify new studies published since a 2016 Australian review, the search period was 2016 to July 2021. Studies which evaluated the association between either naturally or artificially fluoridated water (any concentration) and any health outcomes were included. No restrictions on study design or publication status. Articles published in a \'non-Latin language\' were excluded. Screening of abstracts and full texts was in duplicate. For IQ and dental fluorosis, a top-up search was conducted between 2021 and Feb 2023.
METHODS: Extensive data extraction. Risk of bias assessment using the OHAT tool. A narrative synthesis of the results was carried out.
RESULTS: The review included 89 studies in humans, 199 in animals and 10 reviews of in vitro studies. Where there was consistent evidence of a positive association, in relation to a water fluoride concentration of <20 ppm (mg F/L), and where studies were judged to be acceptable or high quality, health effects were taken forwards for further examination of causality using Bradford Hill\'s 9 criteria. Of the 39 health outcomes reviewed, 4 were further assessed for causality. The authors reported \'strong\' evidence of causality for dental fluorosis and reductions in children\'s IQ scores, \'moderate\' strength evidence for thyroid dysfunction, \'weak\' for kidney dysfunction, and \'limited\' evidence for sex hormone disruption.
CONCLUSIONS: The authors conclude that moderate dental fluorosis and reductions in children\'s IQ scores are the most appropriate health outcomes to use when setting an upper safe level of fluoride in drinking water. For reductions in children\'s IQ, the authors acknowledge a biological mechanism of action has not been elucidated, and the dose response curve is not clear at lower concentrations, limiting the ability to set an upper safe threshold.