Dr Robin Whyman – Clinical Director Oral Health Services at Hawke’s Bay District Health Board, Chair of the NZ Dental Council and past Chief Oral Health Advisor.

Transcript of Talk at Hamilton City Council 28th May 2013

“How does this actually work, basically the process of decay once you get the acid forming around the outside of the tooth is to drag mineral out of the tooth and that’s what the process of decay wants to do. It wants to pull that calcium and phosphate out of the tooth. But fortunately for us it doesn’t pull it out from the very surface first, it actually pulls it out from underneath the surface [sounds like the cause of fluoride bombs – ED] and what fluoride does is it actually changes the chemical composition of what is going on at that level and changes the balance of the equation to push the mineral back in again. It doesn’t completely work so you can completely overwhelm this if you put enough sugar into the equation and that is why we do see children and adults with very high levels of dental decay that have overwhelmed the system.

But at a day to day level for most people the fluoride is actually helping to tip that balance back in favour of remineralisation of the tooth.

Do we have any common ground between the people who are proponents and people saying we shouldn’t have community water fluoridation – we are agreeing that this is a topical effect, this is largely occurring by a topical benefit. So the question becomes why drink it if it becomes a surface effect?

And I can hear people saying yes I agree with that question. But basically this model is trying to show you what is going on when fluoride is coming through the drinking water. So Fluoride is added to water and comes into the first box there and there is a layer of saliva there around the mouth. This was represented to you earlier as just being the fluoride bypasses the teeth and goes down into the body. It’s much more complicated than that. Sitting over the surface of the tooth is what is called a bio-film or a pellicle which immediately after you have cleaned your teeth starts to form back onto the teeth again and that holds fluoride at the level of the tooth surface. You then swallow the fluoride and it comes down into the blood supply. Some of it is actually moves across to bone, we don’t disagree with that at all, and some of it will go to soft tissue. A proportion of it you will excrete in the urine and some of it will come back again in your salivary glands and then come back in the saliva and continue to keep a constant level sitting in the mouth.

So basically what we are doing with community water fluoridation is helping to keep that bio-film with a higher level of fluoride sitting there on a day to day basis and one of the other points that was made earlier in the morning is that this is not a constant system there is no regulatory mechanism to keep it going and that’s also true. Once the community water fluoridation stops that regulatory system will slow down and basically not work. There won’t be fluoride sitting there in the saliva because you haven’t taken it in through the community water supply unless you get it another way and the other key way is through fluoride toothpaste. So toothpaste and community water fluoridation work together with one another to keep that biofilm at a level high enough fluoride to tip the balance back in favour of remineralising the teeth.

And I guess in finishing I would say that it is easy to say, so why don’t we just brush our teeth. The last Oral Health Survey told us that the proportion of people that honestly answered the question that said they brushed their teeth one of more times a day with a fluoride toothpaste, was only around two thirds of the population. And before you say that’s shocking and maybe people should do better, I just leave you with the thought that the last time you went to the doctor and he gave you a prescription for antibiotics, did you take them all on time, and finish the prescription? Or do you actually need the benefit of an environment like this which helps to keep the whole system working better?”

Watch Video

Critique of Saliva Theory