Chapter 4- Fluoride


In the later part of the 1800s a dentist named  Fredrick McKay practicing in Colorado Springs in the USA noticed that his patients had very mottled teeth but at the same time fewer cavities than usual. He and no doubt other dentists in the area began to suspect that it was something in the water. The stain was known as Colorado brown stain [present for life].

In 1918 McKay published the first article on the subject theorising that it was the presence of fluoride in the water that caused the mottling.

Since those days there have been hundreds of studies all over the world in different types of populations looking at tooth decay [caries] and it’s relationship with the amount of fluoride in drinking water. Chemical and statistical analysis methods gradually improved over time and in the 1930’s the optimum level of fluoride content in drinking water was determined. A level with maximum reduction in tooth decay for no or minimum mottling [fluorosis]. This is 1ppm [part per million].[ Research lead by a US dental officer and epidemiologist with the wonderful name of H.Trendley Dean]

In 1964 Birmingham City Council decided to fluoridate it’s water supply. This led to a dramatic drop in caries in children in that area.  Today 5 year olds in Birmingham have approx. 34% fewer decayed teeth and 2 year olds 42% decayed teeth than children of the same age in Manchester without fluoride.

There is fluoride in all tap water but it varies with the rainfall and where your water supply comes from so it may not be to the therapeutic level of 1ppm.

10% of the population of England receive drinking water with the optimum level of fluoride! USA 70%, Ireland 70%, Hong Kong and Singapore 100%, Australia 89%.

The WHO considers water fluoridation to be a safe and effective public health measure. Water fluoridation is supported by Public Health England, The British Dental Association, The British Association for the Study of Community Dentistry and The British Medical Association among others. It has cross party political support.

Badly decayed teeth in children leads to pain, abscesses and ultimately extraction. Extraction of badly decayed teeth is the commonest reason for young children to have a general anaesthetic in the UK.

Water fluoridation reaches everyone in the community, as a public health measure it is very cost effective. None of us, the public have to do anything.

Don’t take my word for it- look it up yourself. The British Society of Paediatric Dentistry has a position statement on the subject.

Fluoride in toothpaste.

Now up until the ‘80s it was thought that fluoride produced its effect by being incorporated into tooth enamel as it is formed. That meant it had to be ingested from fluoridated water intake or various other mechanisms that have been tried- tablets, fluoridated salt and fluoridated milk.

We now know that this is not the case.

Over the years research has shown that fluoride produces its effects in a number of ways which combine to slow down and prevent caries.

We now know that it is the fluoride in toothpaste [introduced in the 1970s] left in the mouth incorporated into the oral fluids and taken up by plaque on the teeth that interferes with the demineralisation process of enamel caused by acids [a by-product of the bacteria in plaque metabolising sugar in the diet].

Teeth and bone are composed of a crystalline mineral compound of calcium and phosphate called hydroxyapatite. Carbonated liquids weaken this structure and make it susceptible to acid attack.

Plaque on teeth is composed of food debris, saliva and bacteria all mixed together to produce a slimy paste. These bacteria metabolise sugar in the diet and produce acid. This lowers the pH in the mouth and on the tooth surface underneath the plaque to below the normal pH of the mouth. When this gets to below 5.5 tooth enamel starts to demineralise [this is called the critical pH] losing its calcium and phosphorus ions into the plaque and saliva. When the pH climbs back up to 7 [neutral] this reverses, the ions flow back and the tooth enamel remineralises. If when this is happening fluoride is present it gets incorporated into the hydroxyapatite on the tooth’s surface to form fluorapertite which is more stable and resistant to acid attacks. The pH has to be much lower at 3.5 for fluorapertite to demineralise. The way fluoride works is microscopically and chemically much more complicated than this and subject to ongoing research but I think this will do for now.

All you have to know is that fluoride is A GOOD THING and essential in reducing/ stopping caries. It is at its best applied topically in toothpaste/ varnishes. You need a constant application as in tooth brushing twice a day.

It is not a magic bullet on its own, for caries to be avoided you need;-

Good oral hygiene twice a day, reduction in the amount and frequency of sugar consumption, fluoride.

Two minutes, twice a day, spit don’t rinse.

Too much fluoride.

As with anything beneficial too much is a bad thing, too much fluoride causes fluorosis in developing teeth. An enormous amount would be poisonous.

This is why the amount of toothpaste and the concentration has to be carefully monitored for children.

Don’t leave toothpaste around where small children can get hold of it and eat it out of the tube, even more attractive if it has a sweet fruity flavor!

If someone in the family has been prescribed higher dose fluoride toothpaste by their dentist for added protection for some reason be especially careful not to leave it lying around. This type of tooth paste is a POM [prescription only medicine] and only for the person it was prescribed for.

Make sure you use the right amount and the right dose of fluoride for every age group.

Under 3yrs– a small smear of toothpaste with at least 1,000ppm, twice a day supervised brushing, spit don’t rinse.

3-7yrs– a pea sized amount of toothpaste with more than 1,000ppm, twice a day supervised brushing, spit don’t rinse.

7yrs and upwards- a toothpaste with 1,300- 1,500 ppm, twice a day, spit don’t rinse.


If you think your child might have been eating the toothpaste out of the tube-

A little bit get them to drink a large volume of milk this will neutralise it.

If a 1 year old has eaten 1/3rd of a 100ml tube of adult toothpaste this would be poisonous. For a 5 year old 2/3rds of a tube. If any doubt HOSPITAL STRAIGHT AWAY.

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