5.11.4 ‘Safe’ snacks
6.5.3 Fluoride in toothpaste 6,9
Fluoride toothpaste is by far the most widely used method of applying fluoride. It is commonly used at home, but has also been used in community
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and school-based preventive programmes. A recent systematic review10con- cluded its use to be associated with a 24% reduction of caries in the per- manent dentition of children and adolescents.10Only one study concerned deciduous teeth, showing a 37% reduction. The evidence to support the effectiveness of fluoride toothpaste is so compelling that it would now be considered unethical to use a non-fluoride toothpaste in a clinical trial.
It is important to remember that most of the above evidence has been gathered in clinical trials lasting 2–3 years. Thus the benefits accrued through a lifetime exposure may be substantially greater and mimic water fluoridation.
A number of factors are important in determining the effectiveness of fluoride toothpaste:
• frequency of use
• fluoride concentration
• rinsing behaviour
• time of day and duration of brushing.
Frequency of use
Those who claims to brush twice a day have lower caries levels than those who brush less frequently. Oral healthcare workers should advise brushing twice per day with a fluoride toothpaste.
Fluoride concentration
The effectiveness of fluoride toothpaste is concentration dependent. There is approximately a 6% reduction in caries for every increase of 500 ppm F and vice versa. Adult toothpastes generally contain 1000–1500 ppm F. However, a desire to reduce the potential risk of fluorosis has prompted the launch of children’s toothpastes containing concentrations around 500 ppm F. These pastes provide less protection.
As a general rule, the author suggests that children under 6 should use an adult-concentration paste, but a small pea-sized portion of it. The child should be encouraged to spit out excess paste and not swallow it. Children’s pastes (500 ppm F or less) could be recommended for children at low risk of caries living in an area where the water contains fluoride.
Today the fluoride agent in most toothpastes is either sodium fluoride or sodium monofluorophosphate. The abrasive used with sodium fluoride is silica, because a calcium abrasive would inactivate the fluoride. On the other hand, chalk-based abrasives can be used with sodium monofluoro- phosphate. Although the superiority of one fluoride agent over the other has been claimed, there is probably very little in it and both can be recommended.
Table 6.1 gives the percentage by weight of sodium fluoride and sodium monofluorophosphate and the equivalent parts per million of fluoride. This is a useful table, because the labelling of the amount of fluoride in a paste may
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be given as % by weight rather than parts per million fluoride. This is confus- ing for the dentist trying to advise a patient, particularly as pastes formulated for children may have variable fluoride concentrations.
High-concentration fluoride pastes are also available (e.g. 2800 ppm F paste in the UK and 5000 ppm F paste in the USA). These products cannot be purchased over the counter but should be prescribed by a dentist on the practice notepaper or sold directly from the surgery. They are indicated for patients at high risk of caries, e.g. those presenting with multiple lesions, patients with root caries, or those with dry mouths. They should neverbe used in children because they will cause fluorosis and when they are pre- scribed for adults, patients should be warned not to allow children to use them.
Rinsing behaviour
There is some evidence that rinsing with large volumes of water after brush- ing reduces the effectiveness of fluoride toothpaste. Patients should therefore be advised to spit rather than rinse vigorously.
Time of day and duration of brushing
There is little evidence-based information on this. However, brushing last thing before bed potentially provides fluoride concentrations in saliva while the patient is asleep. Thus patients should brush before bed and at one other time during the day.
Fluorosis risk
The potential for fluorosis risk is from birth to 6 years with the aesthetically important upper incisors being at greatest risk between the ages of 15 and 30 months. The risk depends on the fluoride concentration of the toothpaste and the amount swallowed. The amount of paste on the brush (and thus potentially swallowed) is very important. Parents should place a small pea- sized smear of paste on the brush and encourage the child to spit out excess paste. Small children do not spit effectively, and the face of a 2-year-old is often level with the basin.
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Table 6.1. Percentage by weight of sodium fluoride and sodium monofluoro- phosphate toothpastes and equivalent parts per million fluoride6
Fluoride (ppm) Sodium fluoride Sodium monofluorphosphate
(% by weight) (% by weight)
1500 0.32 1.14
1000 0.22 0.76
500 0.11 0.38
Toothpastes for patients with dry mouths
Patients with dry mouths find the taste of some pastes too astringent. Where possible, a paste without sodium lauryl sulphate and without a strong pepper- mint taste should be chosen. A high fluoride content may be advised for those developing carious lesions.
Toothpastes without fluoride
Although most toothpaste contains fluoride, it is astonishing to the author how many patients with multiple cavities are not using a fluoride toothpaste.
Some do not brush their teeth. Others, because the cavities have made their teeth sensitive to hot and cold, select a toothpaste specifically formulated and advertised for sensitive teeth. In the UK the original flavour does not, at the time of writing, contain fluoride. Yet others, particularly those with a dry mouth, select a herbal toothpaste because it is not astringent. The paste is made with and without fluoride and sometimes, unluckily and unwittingly, the fluoride-free formulation is bought.
The moral of the story is that the dentist must check what toothpaste is being used, and when in doubt, ask to see it.