SUMMARY / CONCLUSIONS
To our knowledge, the York review is the first systematic review to be undertaken on the subject of water fluoridation. It has undertaken a rigorous search of the published and unpublished literature of human epidemiological studies in all languages. The protocol was subject to external review as were all intermediate stages of the review. Throughout the review, progress and intermediate findings were published on the worldwide web.
The review was critical of the body of evidence that was identified. The authors were surprised by the small amount of work identified. In particular, there were very few studies that followed the same individuals longitudinally, there was lack of analysis of confounding variables and there was failure to undertake appropriate statistical analysis. If new schemes were to start, evaluation should include a robust study design that addressed these issues. One or a few good cohort studies with well-chosen objectives that adequately deal with relevant confounding factors and minimise bias in general would add considerably to the current knowledge about efficacy and safety of water fluoridation with regard to dental caries and fluorosis.
In a brief commentary such as this it is only possible to provide the briefest outline of the methodology and findings of a review of such a large body of literature. Interested readers are encouraged to pursue the main report of the review. From the evidence available, it can be concluded that fluoridation of public water supplies does prevent caries and is associated with fluorosis. The data presented suggest that the effect may be greater in those who have higher baseline levels of DMFT/dmft and this fact may be of use to those deciding health policy. It is imperative that future studies of water fluoridation, either new schemes or the discontinuation of fluoridation, should employ the highest methodological standards and appropriate data analysis.