Most public water supplies here in the US have fluoride added in the belief that it will prevent tooth decay. Despite that – and the fluoride in toothpastes, mouthwashes, and other products – caries remains the most common infectious childhood disease and one that nearly every American will experience at some point in their life. (“Caries” is the clinical term for tooth decay.)

And that brings us to a new study out of the UK, which sought to evaluate the cost effectiveness of water fluoridation for improving oral health and preventing dental treatment in teens and adults. The study appeared earlier this month in the journal Community Dentistry and Oral Epidemiology.

For their analysis, the research team drew on 10 years of dental claims data from the National Health Service (NHS) – claims involving millions of patients. Residential locations were used to match individuals who were exposed to water with a fluoride concentration of at least 0.7 mg/L to those who were not exposed. (That concentration – 0.7 mg/L – is the current public health recommendation.)

The researchers compared the number of invasive dental treatments received between these two groups, as well as their DMFT scores – decayed, missing, or filled teeth. They also calculated treatment costs and cost per each invasive treatment avoided. Among their findings:

  • People who were routinely exposed to fluoride in their drinking water had only 3% fewer invasive dental treatments than those who were not exposed to fluoride.
  • Their DMFT was just 2% lower.
  • “No compelling evidence” was found to suggest “that water fluoridation reduced social inequalities in dental health,” a common justification for adding fluoride to public water supplies.

“This study,” the authors wrote,

suggests that exposure to optimal water fluoridation between 2010 and 20 resulted in ‘exceedingly small’ health effects, ‘very small’ reductions in NHS dental service utilization, and no meaningful reduction in social inequalities, in adult and adolescent users of NHS dental services.

“In high income countries,” the authors suggested, “we may be reaching the limit of what can be achieved through fluorides alone.”

A dose–response relationship between free-sugars and dental caries is evident at all levels of intake above zero and fluorides merely attenuate this relationship.

And there’s where we get to the heart of the matter: Effective oral hygiene starts with the food that we eat – and in high income countries like the UK and US, that food is often highly processed and sugar-laden.

Reduce consumption of sugars – which include all fermentable carbs, such as foods made from white flour or refined starches – and you go a long, long way toward preventing decay. Increase consumption of real food rich in the vitamins and minerals needed to support ongoing natural remineralization of tooth enamel, and you go even further.

And you have none of the very real systemic health risks that come with swallowing fluoride.

Truth be told, it takes very little sugar to raise your risk of tooth decay – a process that happens because sugar is the favorite food of the bacteria that do the damage, courtesy of the extremely acidic metabolic waste they generate. One study determined that to remain caries-free no more than 3% of your daily calories should come from sugar.

For the average person, that’s just 15.5 grams a day, which is roughly one-third of a bag of Skittles or one-quarter of a 20-ounce Coke. In other words, it’s not much.

Yet as the author of a 2015 paper in the Journal of Dental Research succinctly put it, “Without sugars, the chain of causation is broken, so the disease does not occur.”

So why have we not been focusing on diet all along? Because the sugar industry wanted it that way, as was shown several years ago by researchers at UC San Francisco after studying hundreds of industry documents. Big Sugar didn’t want dentists to dissuade their patients from eating sugar, so they threw money and influence around to encourage dental researchers to focus on “harm reduction” rather than actual prevention.

Which is another good sign of just how powerful an influence on oral health diet really is.