The Protective Effect of Breastfeeding on Dental Fluorosis Among Children in Rural Fluoride-Endemic Areas.

Background: Living in fluoride-endemic areas and the inevitable use of groundwater for consumption have imposed children at high risk of dental fluorosis. To mitigate exposure to excessive fluoride at age of developing dentition, breastfeeding might serve as a natural public health intervention against dental fluorosis in that socially disadvantaged context. Objective: This study aimed to evaluate the preventive effect of breastfeeding against dental fluorosis in children living in fluoride-endemic areas in Nakhon Pathom Province, Thailand. Evaluation of the association through several epidemiological models depicted by a directed acyclic graph (DAG) was undertaken. Methods: A case-control study of 127 cases of dental fluorosis and 85 controls was conducted. Independent factor of breastfeeding, along with other past exposure variables, were traced backwardly since infancy by caregiver history taking. Fluoride concentrations in groundwater utilized for household supply matching to residence and number of years by age of each child were collected from 2008 to 2015. Multivariable Poisson regression with robust standard errors was sequentially executed to estimate prevalence ratio (PR) according to models in DAG. Results: Breastfeeding was significantly higher (95.3%) among controls compared to cases (84.2%), p = 0.014. Contrastingly, prevalence of using toothpaste larger than pea-sized and having fluoride ≥1.5 ppm in household water supply was higher among cases. Univariable and subsequent five multivariable regression models according to DAG consistently unveiled significant protective effect of breastfeeding on dental fluorosis with PR ranging from 0.66 to 0.75. Conclusions: Breastfeeding for at least 6 months had preventive effect against dental fluorosis among children living in fluoride-endemic areas.

Hydrogeogenic fluoride in groundwater and dental fluorosis in Thai agrarian communities: a prevalence survey and case-control study.

BACKGROUND: Dental fluorosis can be a disease of social inequity in access to safe drinking water. This dental public health issue becomes prominent in socially disadvantaged agrarian communities in fluoride endemic areas where the standard irrigation system is unavailable and groundwater containing natural fluoride is the major drinking water source. This study aimed to determine the prevalence and severity of dental fluorosis in children and to evaluate its association with fluoride in groundwater in the aforementioned setting in Thailand. METHODS: A cross-sectional survey of 289 children in Nakhon Pathom Province was conducted in 2015. Children with very mild to severe fluorosis were regarded as 'cases' while their counterparts were 'controls' for a subsequent case-control study. Records of fluoride concentrations in groundwater used for household supply corresponding to resident and number of years by age of each child during 2008-2015 were retrieved. Other exposure variables were measured using a questionnaire. Prevalence ratio (PR), a measure indicating the relative effect of different levels of fluoride on dental fluorosis, was obtained from Poisson regression with robust standard error. RESULT: There were 157 children with very mild to moderate dental fluorosis (54.3% prevalence). The univariable analysis revealed that the prevalence of dental fluorosis among children with fluoride concentrations in water sources of 0.7-1.49 (index category 1) and ≥ 1.5 ppm (index category 2) was 1.62 (95% CI; 0.78, 3.34) and 2.75 (95% CI; 1.42, 5.31) times the prevalence among those with fluoride < 0.7 ppm (referent category). After adjusting for all covariates, the adjusted prevalence ratios in both index categories were 1.64 (95% CI; 0.24, 11.24) and 2.85 (95% CI; 0.44, 18.52) which were close to their corresponding crude estimates. Since the magnitude of confounding, measured by (PRcrude-PRadjusted)/PRadjusted, were less than 10% for both index categories; this indicated the limited confounding effect of all covariates. CONCLUSIONS: In fluoride endemic areas, groundwater containing natural fluoride utilized for household consumption resulted in high dental fluorosis prevalence, particularly in the groundwater with fluoride concentrations of ≥ 1.5 ppm.