The trace element fluoride can be beneficial for oral health by preventing dental caries. However, fluoride is also known as an environmental pollutant. Fluoride pollution can lead to fluoride over-ingestion and can cause health issues, including dental fluorosis. Curcumin attenuated fluoride-induced toxicity in animal models, however the molecular mechanisms of how curcumin affects fluoride toxicity remain to be elucidated. We hypothesized that curcumin attenuates fluoride toxicity through modulation of Ac-p53. Here we investigated how curcumin affects the p53-p21 pathway in fluoride toxicity.LS8 cells were treated with NaF with/without curcumin. Curcumin significantly increased phosphorylation of Akt [Thr308] and attenuated fluoride-mediated caspase-3 cleavage and DNA damage marker γH2AX expression. Curcumin-mediated attenuation of caspase-3 activation was reversed by Akt inhibitor LY294002 (LY). However, LY did not alter curcumin-mediated γH2AX suppression. These results suggest that curcumin inhibited fluoride-mediated apoptosis via Akt activation, but DNA damage was suppressed by other pathways. Curcumin did not suppress/alter fluoride-mediated Ac-p53. However, curcumin itself significantly increased Ac-p53 and upregulated p21 protein levels to suppress cell proliferation in a dose-dependent manner. Curcumin suppressed fluoride-induced phosphorylation of p21 and increased p21 levels within the nuclear fraction. However, curcumin did not reverse fluoride-mediated cell growth inhibition. These results suggest that curcumin-induced Ac-p53 and p21 led to cell cycle arrest, while curcumin attenuated fluoride-mediated apoptosis via activation of Akt and suppressed fluoride-mediated DNA damage.By inhibiting DNA damage and apoptosis, curcumin may potentially alleviate health issues caused by fluoride pollution. Further studies are required to better understand the mechanism of curcumin-induced biological effects on fluoride toxicity.

Fluoride is a well-known compound for its usefulness in healing dental caries. Similarly, fluoride is also known for its toxicity to various tissues in animals and humans. It causes skeletal fluorosis leading to osteoporosis of the bones. We hypothesized that when bones are affected by fluoride, the skeletal muscles are also likely to be affected by underlying molecular events involving myogenic differentiation. Murine myoblasts C2C12 were cultured in differentiation media with or without NaF (1 ppm-5 ppm) for four days. The effects of NaF on myoblasts and myotubes when exposed to low (1.5 ppm) and high concentration (5 ppm) were assessed based on the proliferation, alteration in gene expression, ROS production, and production of inflammatory cytokines. Changes based on morphology, multinucleated myotube formation, expression of MyHC1 and signaling pathways were also investigated. Concentrations of NaF tested had no effects on cell viability. NaF at low concentration (1.5 ppm) caused myoblast proliferation and when subjected to myogenic differentiation it induced hypertrophy of the myotubes by activating the IGF-1/AKT pathway. NaF at higher concentration (5 ppm), significantly inhibited myotube formation, increased skeletal muscle catabolism, generated reactive oxygen species (ROS) and inflammatory cytokines (TNF-α and IL-6) in C2C12 cells. NaF also enhanced the production of muscle atrophy-related genes, myostatin, and atrogin-1. The data suggest that NaF at low concentration can be used as muscle enhancing factor (hypertrophy), and at higher concentration, it accelerates skeletal muscle atrophy by activating the ubiquitin-proteosome pathway.

Studies have shown that domestic waste collectors are exposed to toxicants including infectious pathogens, which may be linked to their oral health conditions. This cross-sectional study evaluated the dental caries and its associated factors among domestic waste collectors. A total of 301 adult men who worked for a waste collection corporation were included; 171 men worked in direct contact with domestic solid waste and 130 did not. Sociodemographic data, working, and medical history were assessed. The decayed, missing, and filled permanent teeth (DMFT) index was examined. Logistic regression analysis was used to identify factors associated with dental status with a significance level of 5%. The overall mean DMFT score was 8.36±5.64. The mean DMFT, missing teeth (MT), and filled teeth (FT) were significantly higher in workers who did not have any direct contact with waste (p≤0.04). In the logistic analysis, DMFT ≥8 was only associated with older age (OR=8.41 [95% confidence interval (95%CI), 5.01–14.12], p<0.001). Decayed teeth (DT) ≥2 was associated with no previous oral hygiene instruction (OR=2.70 [1.50–4.81], p=0.001) and no daily dental flossing (OR=4.26 [1.92–9.43], p<0.001). MT ≥9 was associated with lower education level (OR=3.33 [1.57–7.10], p= 0.002). FT≥3 had a negative association with low income (OR= 0.42 [0.25–0.70], p<0.001) and no daily flossing (OR=0.42 [0.23–0.76], p=0.004). In conclusion, occupational exposure to domestic solid waste was not associated with poor dental status. Instead, age, education, income level, and oral hygiene were associated with dental health status. Missing teeth constituted the major component of the DMFT index. Therefore, prevention and oral rehabilitation programs are necessary to improve dental health.

The aim of the present study was to compare the prevalence of dental caries between crack cocaine users and a control group. The study included 106 participants in each group matched for age, sex, and exposure to tobacco. Crack cocaine users were selected from institutions for the treatment of chemical dependency, and the control group was recruited from a public school and among patients who sought dental care. A calibrated examiner determined dental caries experience [Decayed, Missing and Filled Teeth (DMFT) index]. The severity of tooth decay was determined using the Significant Caries Index (SiC). The prevalence of dental caries (DMFT ≥ 1) was 96.2 and 81.1% among the crack cocaine users and nonusers, respectively. Crack users had higher mean DMFT values (7.16 versus 4.92) for the decayed and missing components as well as a higher percentage of individuals with highly severe caries compared to nonusers. After the adjustments in the multivariate model, the prevalence of caries was 18% higher among the crack users (prevalence ratio: 1.18; 95% confidence interval: 1.08–1.30). Age, family income, crack cocaine use, and dental calculus were associated with the occurrence of dental caries. In conclusion, the prevalence of caries was higher among the crack users compared with the control group and remained associated with dental caries in the multivariate analysis.

Fluoride intake, fluorosis, and dental caries could affect quality of life and disease burden worldwide. As a part of the National and Sub-national Burden of Disease Study (NASBOD) in Iran, we conducted a systematic review to evaluate province-year-specific mean drinking water fluoride concentrations and prevalence of fluorosis and of decayed, missed, and filled teeth (DMFT) in Iran from 1990 to December 2015. We did electronic searches of all English and Persian publications on PubMed, ScienceDirect, Google Scholar, and Iranian databases. Results revealed that the weighted mean drinking water fluoride concentration in Iran from 1990 to 2015 has been about 0.65 ± 0.38 mg/l. However, based on the WHO guideline value (1.50 mg/l) and the maximum permissible Iranian national fluoride standard (1.40 to 2.40 mg/l depending on the region's climate), there have been some regions in Iran with non-optimum fluoride concentrations in their drinking water (up to 7.0 mg/l). Overall, concentrations have been higher in southern parts of Iran and in some areas of Azerbaijan-e-Gharbi Province in the northwest and lower in the rest of the northwest and central parts of Iran. In addition, some hotspots have been found in Bushehr Province, southwest of Iran. The highest prevalence of dental flourosis has been reported in normal index while the lowest prevalence has been expressed in severe index. The lowest DMFT (about 0.1) was in Arsanjan City in Fars Province, and the highest (about 6.7) was for Najaf Abad City in Isfahan Province. Prevalence of fluorosis has been rather high in studied areas of Iran (e.g. 100 % in Maku City in Azarbaijan-e-Gharbi Province), and there was discrepancy for DMFT, but a lack of studies renders the results inconclusive. Further studies, health education and promotion plans, and evidence-based nutrition programs are recommended.

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 is an important element for humans. It inhibits initiation and progression of dental caries and stimulates bone formation. However, excessive intake may lead to the appearance of dental and/or skeletal fluorosis and a decrease in intellectual coefficient in child populations. This study evaluates exposure to fluoride in the child population of Chaco province (Argentina) by analysis of drinking water, food and its bioaccessible fraction (quantity of fluoride solubilised by gastrointestinal digestion and available for intestinal absorption) and urine as a biomarker of internal dose. The concentration of fluoride in drinking water varied between 0.050 and 4.6 mg L⁻¹, and 80% of the samples exceeded the WHO drinking-water guideline value (1.5 mg L⁻¹). Fluoride concentrations in food ranged between 0.80 and 3.0 mg kg⁻¹ fresh weight (fw), being lower in bioaccessible fraction (0.43–1.9 mg kg⁻¹, fw). On the basis of the consumption data declared for the young child population, fluoride intake varies between 4.1 and 6.5 mg day⁻¹, greater than the level recommended for this age group. Moreover, in some cases, concentrations of fluoride found in urine (0.62–8.9 mg L⁻¹) exceeded those reported in areas with declared fluorosis. All data obtained show the worrying situation of child population in this area of Argentina.

Environmental lead (Pb) exposure can induce dysbacteriosis, impair oral health, and is associated with the development of dental caries. However, the mechanism is unclear. The aim of this study was to explore the effects of Pb toxicity on oral antimicrobial activity in children in an e-waste area. Results showed higher blood Pb levels in e-waste-exposed group children, accompanied by decreased saliva SAG (salivary agglutinin) concentrations, increased peripheral WBC (white blood cell) counts and monocyte counts, and elevated peripheral monocyte percentage. LnPb (natural logarithmic transformation of blood Pb level) was negatively correlated with saliva SAG concentration, while positively correlated with peripheral monocyte percentage. Saliva SAG concentration played a complete mediating role in the correlation of LnPb to peripheral monocyte percentage. To our knowledge, this is the first study on the relationship of environmental Pb exposure and oral antimicrobial activity in children, showing that environmental Pb exposure may weaken oral antimicrobial activity through reducing saliva SAG concentration, which may raise the risk of oral dysbacteriosis and ultimately pathogen infection.

This cross-sectional study evaluated the saliva profile in crack-cocaine-addicted males and its relationship with dental caries, periodontal disease, and oral mucosal lesion (OML) using 148 adult male volunteers (37 addicted; 111 non-addicted) at the School of Dentistry, Federal University of Bahia. Data on decayed, missing and filled teeth (DMFT), periodontal disease and OML were collected from the clinical examination of the participants. Samples were analysed for the salivary flow rate (SFR) of unstimulated and wax-stimulated whole saliva and the saliva buffer capacity. Bivariate and regression analyses were conducted to assess the salivary profile and its association with the oral status of addicted participants (α = 0.05). The mean buffer capacity of stimulated saliva was significantly lower in the addicted participants (pH 5.2 ± 1.7) than in the non-addicted group (pH 5.8 ± 1.3, p = 0.03). In the addicted group, OML was associated with a stimulated SFR < 1.0 mL/min (OR = 11.98, 95% CI = 1.30–27.10, p = 0.04). The DMFT index and periodontal disease were not associated with the salivary profile, but with older age (OR = 7.20, 95% CI = 1.51–31.14, p = 0.01) and lower education levels (OR = 24.00, 95% CI = 1.68–341.00, p = 0.02), respectively. In conclusion, addiction was associated with the lower buffer capacity of stimulated saliva, and OML was associated with lower-stimulated salivary flow rate. Periodontal disease or DMFT was not associated with salivary factors in addicted males. Therapy approaches dealing with saliva status may be important for use with addicted males to reduce OMLs.