MANCHESTER, UK: Researchers from the University of Manchester have conducted a pioneering study in the UK focusing on the oral health and economic impacts of water fluoridation on adults and adolescents, considering populations with widespread access to topical fluoride. While the findings indicate that water fluoridation remains beneficial, the advantages are not substantial. Therefore, in high-income countries, the potential benefits of fluoride treatment alone may have reached its zenith and other measures—such as fostering environments that support healthier food choices—may be more effective.

Initial research on the implementation of community water fluoridation to combat caries indicated a reduction of up to two-thirds in the average number of teeth affected. “Fluoridation of drinking water is justifiably recognised as one of the twentieth century’s greatest public health achievements,” said project lead Dr Deborah Moore, a research associate at the University of Manchester, in a press release.

Like with any public health intervention, continued monitoring is required, as the implementation context evolves over time. “[As] fluoride toothpastes became available in the mid-1970s—considered to be the key factor in the dramatic decline in the prevalence and severity of dental decay—the context of water fluoridation has changed,” explained Dr Moore.

Even though the broader adoption of water fluoridation is considered an effective, cost-efficient public health strategy for lifelong protection against the gradual onset of caries, there is limited published evidence on its efficacy in adults. In high-income countries, the nature of caries has transformed from a fast-progressing childhood disease leading to early tooth loss to a more slowly advancing condition, and adults now bear the majority of its burden. Given the widespread use of fluoride toothpaste and the increasing number of individuals retaining their natural teeth into later life, in this new study, the research team sought to assess the dental health benefits for adults.

The researchers used routinely collected National Health Service (NHS) dental treatment data submitted between 2010 and 2020. The study included individuals aged 12 years and older who were receiving care from NHS primary dental services in England, totalling 17.8 million patients. The analysis involved matching individuals with exposure to optimally fluoridated drinking water to those without, resulting in a sample of 6.4 million patients.

The findings showed that the average number of invasive NHS dental treatments, such as restoration and extraction, was 3% lower in the group with optimal water fluoridation, compared with the control group. Additionally, the average number of decayed, missing and filled teeth was 2% lower in the group with optimal water fluoridation. There was no notable difference in the average number of missing teeth per individual, and the data did not provide strong evidence that water fluoridation significantly influenced social disparities in dental health.

“Managing sugar consumption is another area of policy that needs to be investigated.”

Implications for health economics

Between 2010 and 2020, the estimated cost of optimal water fluoridation in England was £10.30 (€12) per individual. During this period, NHS dental treatment expenses for patients in areas with optimal fluoridation were reduced by 5.5%, equating to a saving of £22.26 per person.

“The patients who received optimal water fluoridation had very small positive health effects. But as the costs of NHS dentistry are much higher than the costs of water fluoridation, the relatively small observed reductions in visits to the dentist still resulted in a positive return for the public sector. This return should be evaluated against the projected costs and lifespan of any proposed capital investment in water fluoridation, including new programmes,” said Dr Moore.

Fluoride only mitigates sugar intake

“There is no doubt that population-level, mass preventive interventions for tooth decay are still required. Tooth decay remains almost universal by adulthood, even in populations that have had access to fluoride toothpastes and fluoridated water from birth. However, in high-income countries, we may be reaching the limit of what can be achieved through fluorides alone,” commented Dr Moore.

The researchers emphasised that a dose–response relationship between dietary intake of free sugars and caries is evident, and fluorides merely mitigate this association. “The relationship between sugar consumption and tooth decay is very clear: average consumption of sugars in the UK is more than double the recommended level for adolescents and is almost double for adults. Managing sugar consumption is another area of policy that needs to be investigated,” highlighted Dr Moore.

The study authors concluded that water fluoridation has made an unparalleled contribution to oral health in the twentieth century; however, for the twenty-first century, greater impact may be achieved by advocating healthy food intake.

The study, titled “How effective and cost-effective is water fluoridation for adults and adolescents? The LOTUS 10-year retrospective cohort study”, was published on 8 January 2024 in Community Dentistry and Oral Epidemiology, ahead of inclusion in an issue.

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