You may have heard the expression that “an ounce of prevention is worth a pound of cure” This quotation comes from Benjamin Franklin in 1736. And he was right – when it comes to fire prevention – which is what he was talking about. It’s also true for dentistry, where a bad tooth ache can feel like your whole mouth is on fire. Our poor suffering patients then have to seek dental care in these acute times of crisis. However, many people are unaware that the seeds of this dreadful disease and suffering were cast months or even years beforehand, quietly and with the stealth of a skillful thief. Up until 1940, we really had every excuse for genuine surprise and resignation when the supposedly inevitable dental destruction struck. Decay and gum disease were facts of life, and had to be tolerated. Everyone had their terrible tooth ache story to tell; of the terrible pain on cold, then the waves of dull aches up into their faces, and finally the fat swollen red cheek. But in 1940 that changed.

So what happened in 1940 that totally invalidated our previous expectation that dental decay was unavoidable? Well, Dr Robert Stephan, a dentist and researcher in New York, published his experimental study. (Stephan RM (1940. Changes in the hydrogen ion concentration on tooth surfaces and in carious lesions. J Am Dent Assoc 27:718-723.)

Could just one paper change our understanding of dentistry that much? Well, yes. It was experimental proof that sugar in the diet is associated with an increase in acidity in the mouth, which then causes the hard beautiful enamel and dentine that make up teeth to leach out their calcium, discolour and develop cavities. Such was the precision of this experiment with even the very rudimentary pH meters of the day, that the acidity increase could be charted over some minutes. While no scientist will jump to conclusions of causality so easily, it is today generally accepted that frequent dietary sugars are the only cause of tooth decay (Sheiham A, James W. Journal of Dental Research 2015, Vol. 94(10) 1341–1347).


So it’s simple. No sugar in the diet (like jam) – and no decay can happen. But is there anyone who doesn’t like jam! No more sweet foods and drinks, then? Sounds a bit grim. Well, it turns out that we don’t have to avoid all sugar in the diet, at all times; just most of the time. So when armed with the science, we can be cleverer than that.

It’s the frequency and duration of the sugar attacks which are most strongly related to the amount of decay experienced. So we don’t have to avoid all sweet foods and drinks – there’s a threshold under which no decay happens. OK, well you might ask what’s the threshold. This of course is variable, as most things are in biology. But there are some rules of thumb. If you avoid having sweet foods and drinks every day, especially between meals, then the damage to the teeth is much reduced. Indeed my recommendation is only to intentionally have sugar in food and drinks just perhaps two or three times per week, to be sure you’re below your personal decay threshold. If you had fluoride in the drinking water supply as a child, then you have some decay protection and do not have to be so strict. But if you’re not fluoridated while growing up then you’ll need to be stricter. Of course brushing and flossing help to reduce the plaque levels and minimize the harm too, but even excellent cleaning will not reach into fissures and crevices where decay can still happen. So our diet has to be good to avoid decay, even with good cleaning. Don’t forget that naturally occurring sugars are just as damaging as refined sugar (which is actually a natural sugar too – it comes out of a plant called… sugar cane!) Even honey will cause decay when eaten frequently. Its 86% sugar, which is why it tastes sweet. Obvious isn’t it, really! There’s a reason bees don’t have teeth!

Bees don’t have teeth so they can have as much nectar and honey as they like with no tooth decay. We can’t!