False confidence

29 October 2014
Volume 30 · Issue 3

Alexander Holden asks how certain we can be of our advice to patients.

What’s the greatest dental public health measure we could implement? This question might elicit some interesting responses, but many I might imagine would say water fluoridation. As we are all aware, fluoridation has a big anti-lobby that usually acts vociferously to any introduction to a new area and even challenges the continued use in areas already fluoridated. When I was a humble dental student, I remember having it drilled into me (pardon the pun) that water fluoridation would be the single best thing to happen in dentistry since the introduction of fluoride toothpaste. We were told that those who stood against it were philistines and ignorant, ill-informed and looking to make issue. There was also the irritating fact that those who objected to the use of fluoridation are also those who are likely to have good oral health and they wouldn’t be the ones who would primarily benefit.

 

We as dentists and dental care professionals are slightly guilty of going along with this; we blindly sign-up to the belief that is given to us early in our careers. Has anyone ever questioned whether this is right? Have we been conned to some extent? Where is the evidence that fluoridation is the answer to our problems? This must seem sacrilegious - a dentist questioning the benefits of fluoridation! Have no fear, I am just as much a convert to the idea of fluoridation as the next GDC registrant, my reason for writing this article is that I have always been disconcerted about the idea of being challenged about fluoridation and having to defend it. The issue is that when challenged, the burden of proof is placed upon the expert (us) and those that challenge us have relatively little to defend or prove in return. “The studies show that fluoridation (swap for amalgam and any other dental material/ intervention you may need to defend) is perfectly safe and effective.” Does that sound familiar? If I’ve said this once, then I’ve said it a thousand times. In the case of fluoridation then what is the evidence?

Those readers who are more interested might reference the most famous study on water fluoridation, The NHS Centre for Reviews and Dissemination’s, “A Systemic Review of Water Fluoridation” more commonly known as The York Report. Since its publication in September 2000, there have been three other studies, but they haven’t really contributed to the literature base in any great way so I’m going to stick to The York Report.

 

We tend to use this report as the basis to refute any claims that fluoridation isn’t beneficial or might actually be harmful, the big question is, should we? It wasn’t until I sat down and read The York Report that I realised that perhaps I shouldn’t be so confident with my claims that fluoridation is so well supported.

 

The York Report is a systematic review including 214 studies that met the inclusion criteria. None of these studies were above level B meaning that all included studies were of moderate quality or lower. The York Report has five objectives, objective one looks at the effects of fluoridation on the incidence of caries. The report does indeed suggest that fluoridation reduces caries incidence, but is uncertain as to what extent this is true. There are also issues with bias and confounding factors. Objective two looked at whether fluoridation had any beneficial effects, as well as if there were any benefits over and above the use of alternative interventions. This objective struggled for the same reasons as in objective one; a lack of good quality studies and confounding variables. Objective three looked at whether water fluoridation brought a reduction in caries across social groups contributing to equity. Objective three found that there was a reduction in inequalities, however, the evidence was low in both quantity and quality, leading to the report suggesting that these results should be interpreted with caution. Objective four looked at the potential harmful effects. Out of the associations looked at, there was only correlation between fluoridation and fluorosis; there was no correlation found between bone issues, cancer or other harmful effects. With regards to fluorosis, there wasn’t much precision with regards to what percentage of the population would suffer from fluorosis of aesthetic concern. The final objective, objective five, was tasked with looking at whether there was any difference between the effects of artificial and natural fluoridation. Again, whilst the general premise that there is no difference was supported, the evidence was not adequate to make a conclusion regarding this objective. Still fancy relying on The York Report?

 

The thing is, despite the fact that The York Report is poor with regards to its quality of evidence, we know that water fluoridation would be a good thing. Water fluoridation is difficult to study and there is a definite need for more research on the topic. It comes to the point that we as a profession could spend a long time arguing with the nonbelievers in water fluoridation, wasting a lot of time and energy. Why is it a waste of time? Because no matter how articulate we are, and no matter how well we research the topic and improve the evidence base, we won’t convince those who don’t want to be convinced. At the end of the day, it’s much easier to argue against fluoridation than it is to argue for it, especially as we as professionals need to maintain our level heads whilst those around us are fully able to lose theirs. The way forward with regards to promoting water fluoridation is to address the need to build and maintain relationships with politicians, water companies, the general public and others in other relevant sectors who can move us forward with plans to fluoridate the water supply. Attacking and entering into dialogue with the anti-fluoride lobby is as ineffective as they claim fluoridation is. As much as we want these individuals to be on-side, it isn’t going to happen anytime soon.