Community water fluoridation may reduce dental caries disparities due to income levels, according to a new study published in JAMA Pediatrics. Researchers found low-income children were less likely to experience caries in their primary teeth if they lived in fluoridated counties.
The study investigated various factors that influence caries development, including family income-to-poverty ratio, county fluoridation status, and time since last dental visit.
"By age 11 years, an American child living in poverty has twice the level of dental caries as one living at three times the poverty threshold," wrote the authors, led by Anne Sanders, PhD, from the University of North Carolina at Chapel Hill School of Dentistry, in their research letter (JAMA Pediatrics, January 28, 2019). "We used two nationally representative datasets to investigate whether water fluoridation attenuated income-related inequality in dental caries among U.S. children and adolescents."
Leveling the field
The researchers wanted to know whether community water fluoridation could help improve oral health equity in the U.S. To find out, they conducted a study using county-level water fluoridation and dental caries data from the U.S. Centers for Disease Control and Prevention.
The researchers defined a county as predominantly fluoridated if at least 75% of the population was serviced by fluoridated water. They measured caries incidence through the mean decayed and filled surfaces (dfs) for primary teeth and decayed, missing, filled surfaces (DMFS) for permanent dentition. Their final analysis included data from more than 14,000 children ages 2 to 17.
Children from lower-income families were more likely to experience dental decay than those from higher-income families, the researchers found. Furthermore, the relationship between family income and decay in primary dentition was reduced by 41% for children who lived in fluoridated counties.
The effect of water fluoridation was greatest for children from the lowest income level, the authors noted. However, the results were not significant for permanent teeth.
"The degree of attenuation was less pronounced in the permanent dentition, possibly because the level of decay was about half that of primary teeth," they wrote. "Greater attenuation in the permanent dentition might be seen in early adulthood, as the burden of DMFS doubles between adolescence and early adulthood."
Correlation doesn't always mean causation
The study had a number of shortcomings, including that correlation does not equal causation. The researchers hope future studies will further investigate ways to reduce dental decay disparities between children from various income levels.
"Economic modeling suggests that fluoridation of currently unfluoridated U.S. communities with populations of 1,000 or more would annually save $2.5 billion in costs related to dental caries," the authors wrote. "The current findings provide additional support for water fluoridation as a means toward the Healthy People 2020 goals for achieving health equity, eliminating disparities, and improving the health of all groups."
