Chapter 11

Fluoride

WHAT IS FLUORIDE?

Fluoride is a compound of the naturally occurring element fluorine and is a part of a group of chemicals known as halogens.

Where is it found?

Fluoride is found in low concentrations in water, soil, rock, air, plants and food (e.g. fish bones, tea and beer). It is also an essential component of body fluids and soft tissues, mainly deposited in the bones and teeth.

Fluoride is added to most toothpastes and has been proven to reduce the incidence of tooth decay dramatically over the last 40 years in the United Kingdom [1]. The addition of fluoride to toothpaste has been the biggest single development in the prevention of dental caries, causing a reduction in incidence by 20–30% in children [2].

Research has also shown that a reduction in caries is found when toothpaste is regularly used at 1500 ppm [3].

Facts about fluoride

Here are some useful facts about fluoride:

• Calcium fluoride is the form that often occurs naturally in water supplies.
• Sodium fluoride is the form used to artificially raise levels in drinking water.
• The fluoridation of water is the adjustment, either up or down, of the amount of fluoride in water supplies to an optimum of 1 ppm. The maximum permitted value of fluoride in drinking water in the United Kingdom is 1.5 ppm.
• Fluoride is readily absorbed from the stomach and rapidly excreted via the kidneys, mostly in urine, and also through sweat and faeces. Traces can be found in hair, tears, breast milk and saliva.
• Fifty per cent of fluoride in the body is stored in the bones and teeth [3]. It can help alleviate conditions such as osteoporosis and helps developing teeth become more resistant to caries.

History of fluoride

It is useful for oral health educators (OHEs) and other health professionals to know a little about the history of fluoride.

1892 (UK)

Sir James Crichton Browne was the first dentist recorded to remark upon the possible connection between fluoride and the incidence of caries [2].

1901 (Colorado Springs, USA)

Dr. F. McKay observed ‘mottled enamel’ in patients, characterised by minute white, yellow or brown spots scattered over tooth surfaces. In certain American states, a relationship between tooth staining and the presence of naturally occurring fluoride in water was observed [3].

1930s (USA)

McKay and Black associated the mottled effect of enamel and low incidence of caries with high levels of fluoride in drinking water [3]. The term dental fluorosis was applied to the condition of intrinsic staining caused by fluoride ingestion at over 2 ppm during tooth formation.

Dr. H. Trendley-Dean carried out research in South Dakota, Wisconsin and Colorado. He showed that the severity of tooth mottling was affected by the concentration of fluoride in the water, and that a near-maximum reduction in caries occurred when water contained 1 ppm fluoride [2]. He therefore deduced that 1 ppm fluoride was the optimum level to prevent tooth decay in drinking water.

1945 (Michigan, USA)

Sodium fluoride was added to drinking water in Grand Rapids (Michigan), and resulted in a 50% reduction in caries incidence [2].

1955 (UK)

Kilmarnock, Watford and part of Anglesey had 1 ppm fluoride added to the drinking water. After 5 years, a 50% reduction in caries was found [2]. However, local opposition in Kilmarnock halted fluoridated water, and the caries rate rose steadily to previous levels.

1964 (UK)

In 1964, water in the West Midlands and Newcastle was fluoridated.

1978 (UK)

Strathclyde decided to fluoridate its water supply, but this was opposed (partly on the grounds that it could cause cancer), and in a famous case the High Court of Scotland ruled that although water fluoridation was safe and effective, due to a legal technicality, Lord Jauncy found in favour of the opponent [4].

Remember! The term Jauncy used in the trial was ultra vires, meaning outside of his power.

1985 (UK)

The Strathclyde case led to the establishment of a committee, led by Professor Knox, to investigate the possible harmful effects of fluoride. The Knox report, published in 1985, found no evidence that fluoride, when added to water, causes cancer [5].

2000 (UK)

A systematic review (carried out by the University of York) was commissioned by the chief medical officer of the Department of Health, who requested ‘an up-to-date expert scientific review of fluoride and health’.

The main conclusions of this review were:

• Fluoride reduces the prevalence of caries.
• A beneficial effect was still evident in nine studies conducted after 1974 (when fluoride was first added to toothpaste).
• Evidence from 15 studies showed that water fluoridation reduces inequalities in dental health across social classes in 5–12 year olds, using the decayed, missing, filled teeth (dmft/DMFT) index (see Chapter 29).
• The prevalence of dental fluorosis increases with the concentration of fluoride in the water.
• No association was found between fluoridated water and bone fractures or bone development problems (29 studies).
• No association was found between water fluoridation and bone, thyroid and all other cancers (26 studies).

The authors of the review were surprised that, given the level of interest surrounding the issue of public water fluoridation, little high-quality research had been undertaken. They concluded that any future research into the safety and efficacy of water fluoridation should be carried out with appropriate research methods to improve the quality of the existing evidence base [6].

2005 (UK)

The British Dental Association (BDA), together with the British Medical Association (BMA) and the British Fluoridation Society, responded to a Primary Care Trust survey of patients in 2005 by asking the House of Lords to amend a bill on the fluoridation of water supplie/>