Is the fluoride intake by diet and toothpaste in children living in tropical semi-arid city safe?

Fluoride Intake Through Dental Care Products: A Systematic Review

Fluoride (F) is added to many dental care products as well as in drinking water to prevent dental decay. However, recent data associating exposure to F with some developmental defects with consequences in many organs raise concerns about its daily use for dental care. This systematic review aimed to evaluate the contribution of dental care products with regard to overall F intake through drinking water and diet with measurements of F excretion in urine used as a suitable biomarker. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using keywords related to chronic exposure to F in the human population with measurements of F levels in body fluids, 1,273 papers published between 1995 and 2021 were screened, and 28 papers were finally included for data extraction concerning daily F intake. The contribution of dental care products, essentially by toothbrushing with kinds of toothpaste containing F, was 38% in the mean regardless of the F concentrations in drinking water. There was no correlation between F intake through toothpaste and age, nor with F levels in water ranging from 0.3 to 1.5 mg/L. There was no correlation between F intake and urinary F excretion levels despite an increase in its content in urine within hours following exposure to dental care products (toothpastes, varnishes, or other dental care products). The consequences of exposure to F on health are discussed in the recent context of its suspected toxicity reported in the literature. The conclusions of the review aim to provide objective messages to patients and dental professionals worried about the use of F-containing materials or products to prevent initial caries or hypomineralized enamel lesions, especially for young children.

Chemical Aspects of Human and Environmental Overload with Fluorine

Over the last 100-120 years, due to the ever-increasing importance of fluorine-containing compounds in modern technology and daily life, the explosive development of the fluorochemical industry led to an enormous increase of emission of fluoride ions into the biosphere. This made it more and more important to understand the biological activities, metabolism, degradation, and possible environmental hazards of such substances. This comprehensive and critical review focuses on the effects of fluoride ions and organofluorine compounds (mainly pharmaceuticals and agrochemicals) on human health and the environment. To give a better overview, various connected topics are also discussed: reasons and trends of the advance of fluorine-containing pharmaceuticals and agrochemicals, metabolism of fluorinated drugs, withdrawn fluorinated drugs, natural sources of organic and inorganic fluorine compounds in the environment (including the biosphere), sources of fluoride intake, and finally biomarkers of fluoride exposure.

Socioeconomic inequalities explain the association between source of drinking water and dental caries in primary dentition

OBJECTIVE

To evaluate the association between source of drinking water and dental caries at age 5 and to test whether socioeconomic conditions act as confounding factors in such association.

METHODS

The study was carried out in a sub-sample of the 2004 Pelotas Birth Cohort, which comprised the application of a questionnaire and clinical oral examination. The exposure was source of drinking water, collected through a question to the primary caregiver. The outcome was dental caries in primary dentition, measured through several standardized indicators of the decayed, missing and filled teeth index (dmft), assessing past and present dental caries. Socioeconomic indicators (family income and maternal education) were identified as potential confounding factors. After descriptive analysis, the association between source of water and measures of dental caries was assessed by Regression models.

RESULTS

1,084 children were evaluated and had complete information in all variables (83.2 % of the targeted sample). Dental caries experience was observed in 48.7 % of the children, with a mean of 1.9 decayed, missing or filled teeth. Most children consumed water from public water supply (76.0 %), and a socioeconomic pattern was observed, with children from lower income more likely to drink water from public supply. In crude analysis, children who consumed bottled water had a lower risk of decayed teeth, lower experience of dental caries and less severe disease. No associations were observed after adjustments for socioeconomic conditions.

CONCLUSION

Underlying socioeconomic inequalities explained the association between prevalence and severity of dental caries in primary dentition and source of drinking water.

CLINICAL SIGNIFICANCE

Drinking fluoridated tap water is as effective in dental caries prevention as bottled water with acceptable levels of fluoride, with the advantage of being accessible to all. Oral health prevention and treatment should be implemented as early in life as possible and should take into consideration the family's socioeconomic context.

Effect of fluoride in drinking water on the level of 5-methylcytosine in human and rat blood

DNA methylation is an epigenetic modification of genome that is involved in many human diseases. Recent studies revealed DNA methylation may be associated with fluorosis. This study was aimed to evaluate the dose-response effect of fluoride on DNA methylation in human and rat blood. A commercial ELISA kit was employed to evaluate 5-methylcytosine (5-mC) level of genome in human and rat blood. A total of 281 subjects were enrolled in this study and divided into four equal-size groups by the quartile of fluoride in drinking water. The difference of 5-mC among the four groups was significant. The U-shaped relationship was found between fluoride and 5-mC in the population. The U-shaped curve was also observed in the rats with three months of fluoride treatments. Taken together, these results clue the disruption of DNA methylation in mammals may has a certain association with fluoride in natural exposures.