'The YORK REVIEW' (an idiot's guide to...)

A systematic review to assess the evidence on the positive and negative effects of population wide drinking water fluoridation strategies to prevent caries

Objectives set by DoH:

• Objective 1. What are the effects of fluoridation of public water supplies on the incidence of caries?
• Objective 2. If water fluoridation is shown to have beneficial effects, what is the effect over and above that offered by the use of alternative interventions and strategies?
• Objective 3. Does water fluoridation result in a reduction of caries across social groups and between geographical locations, bringing equity?
• Objective 4. Does water fluoridation have negative effects?
• Objective 5. Are there differences in the effects of natural and artificial fluoridation?

Levels of evidence:

• A. Highest quality, minimal risk of bias                               NONE FOUND
• B. Moderate quality, moderate risk of bias
  Admitted for Objectives 3. and 4. only:
• C. Lowest quality, high risk of bias.

3,246 papers found. 735 relevant. 254 met inclusion criteria.

Primary studies only (i.e. not reviews); Water fluoridation only (i.e. not total fluoride burden); Humans only (i.e. no animal studies); World-wide literature.

[Comment: A Rolls-Royce exercise - "best evidence" only (none of it very good - no randomised controlled trials), therefore very many studies excluded.]

Objective 1.

26 studies. All Level B (ave. score 5/8).

Studies suggest on average fluoridation reduces caries by some 15%.

Objective 2.

10 studies. All Level B (ave. score 5/8).

Water fluoridation probably has an effect over and above toothpaste and other sources of fluoride.

Objective 3.

15 studies. 2 Level B, 13 Level C (ave. 1.6 / 8).

Possible reduction of inequality among 5-year-olds only.

Objective 4.

DENTAL FLUOROSIS

88 studies. 1 Level B, 87 Level C (ave. 2.8 / 8).

Estimated 48% of fluoridated population fluorosed @ 1 ppm, 12.5% with fluorosis of aesthetic concern. For every 22 additional people treated with fluoridated water, at least 3.1 may have a caries-free mouth, 3.7 may have a mildly fluorosed mouth, and 1 may have fluorosis of aesthetic concern.

BONE PROBLEMS

29 studies. 1 Level B, 28 Level C (ave. 3.4 / 8).

No clear pattern.

CANCER

26 studies. 5 Level B, 21 Level C (ave. 3.8 / 8).

No clear pattern.

OTHER

33 studies. All Level C (ave. score 2.7 / 8).

No clear pattern.

Objective 5.

Very few of the above-mentioned studies allowed comparison to be made between naturally and artificially fluoridated areas.

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