MEDSCAPE. The government’s dental recovery plan, published last week, includes new legal powers for expansion of water fluoridation. NHS England described this as a “first time ever” roll out, and said the proposals “could reduce the number of tooth extractions due to decay in the most deprived areas of the country”. However, the programme is likely to attract controversy. Medscape News UK looked at different perspectives on what is often a polarised debate.

Water fluoridation is known to reduce tooth decay among children, a particular problem in areas of socioeconomic deprivation. A 2015 Cochrane Review found 20 studies showing that fluoridation was associated with 35% fewer decayed, missing, and filled baby teeth, and 26% fewer decayed, missing, and filled permanent teeth. Fluoridation led to a 15% increase in children with no decay in their baby teeth, and a 14% increase in children with no decay in their permanent teeth.

However, the review cautioned that results were based predominantly on old studies, often predating the introduction of fluoride toothpaste, and might no longer be applicable. It had concerns about the methods or results of almost all (97%) studies, and found no evidence of benefits of fluoridated water in adults. But it did say that where water fluoride levels were 0.7 ppm or higher, there was a 12% chance of people having dental fluorosis leading to cosmetic concerns.

Conflicting Evidence on Health Harms

The NHS says that, apart from dental fluorosis, there is “so far no convincing evidence” to support concerns about adverse health effects. However, some studies have suggested that fluoride is a potential developmental neurotoxin associated with reduced IQ in children of exposed pregnant women. Investigations of a suggested link with Down’s syndrome incidence have yielded conflicting evidence.

A 2021 report by the UK’s chief medical officers acknowledged a “small risk” of dental fluorosis from levels used in public health, but dismissed “weaker studies” suggesting associations with hip fracture, Down’s syndrome, kidney stones, bladder cancer, and osteosarcoma, saying that “prevailing public health opinion is now that there is no significant association between water fluoridation and these conditions”.

Dr Ray Lowry, a retired doctor, dentist, and academic, is secretary/treasurer of the British Fluoridation Society. He told Medscape News UK that water fluoridation offers additional benefits over and above tooth brushing with fluoride toothpaste and other dental health interventions including fluoride tablets, rinses, sealants, gels, and oral hygiene lessons.

Avoiding Tooth Decay “Almost Impossible” in Modern Life

He acknowledged that humans would not be subject to tooth decay if they had a perfect, noncariogenic diet, exemplary oral hygiene, and ideal parenting, “but this is almost impossible these days”.

“Our view is that water fluoridation is the best intervention, but it works well with other interventions to complete the preventive portfolio,” he said. “Fluoride in water mimics the case of vitamins that are needed for health development: it can be obtained in other ways, but the water route (strictly controlled as it is) is the best.”

Fluoridation Linked With Hypothyroidism

In 2015, the Journal of Epidemiology & Community Health published a population level study that raised concerns about a correlation between fluoride levels in water supplies and the prevalence of hypothyroidism.

The study showed that general practices in the West Midlands, a wholly fluoridated area, were almost twice as likely to report high hypothyroidism prevalence as those in nonfluoridated Greater Manchester. It concluded that there were “particular concerns about the validity of community fluoridation as a safe public health measure”.

Attacks on Experts Who Raise Concerns

The study generated vitriolic attacks on the authors, as have others that have not unconditionally supported community water fluoridation. It has been noted that people who question the safety of water fluoridation may be “quickly dismissed as zealots or anti-science fanatics” without examination of the evidence. Yet numerous studies  since have also found links with hypothyroidism.

The lead author of the study, professor of health policy at the University of Kent, Stephen Peckham, told Medscape News UK that the US Environmental Protection Agency had confirmed the link between fluoride and thyroid disease, while many studies have linked fluoride to lowered IQ levels in children and a cognitive development hazard, an issue subject to a current court case.

He said: “The claimed benefits of water fluoridation continue to be overstated”, with two recent high-quality studies showing that the evidence of benefit in preventing decay “is very limited and may not be clinically significant”. Peckham added: “The dental health policymakers also continue to ignore high-quality studies demonstrating harm, often simply dismissing these as irrelevant.”

Meanwhile, a study published last month from the University of Manchester also showed that the benefits of fluoridation were minimal, with “no compelling evidence that water fluoridation reduced social inequalities in dental health”.

The British Dental Association told Medscape News UK that it believes that “a multipronged approach is required to tackle oral health inequalities”, and “there’s no silver bullet”.

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