RESUMEN
Water fluoridation is a public health measure to reduce levels of dental caries in populations. A report of the recently completed CATFISH study has been published. This was the first UK evaluation of fluoridation introduction for many years; it was carefully designed and executed and is welcomed. The purpose of this article is to highlight the 180-page report of the study and comment on some aspects to aid interpretation of the findings. Significant features were that two cohorts, from birth and from five years, were followed for six years in a fluoridated and a non-fluoridated area, and clinical and cost analyses were reported. Areas of the report which deserve comment are: a) interruption of fluoridation for a year for half the children in the intervention area and its effect; b) clinical results were reported as absolute reduction in caries prevalence, with the preventive fraction for caries severity downplayed; c) the power of the study was diminished by an unexpected lower caries increment; and d) control for differences in diet was not possible. Nevertheless, this major UK study showed clinical and cost benefits of water fluoridation. The risk of cessation of water fluoridation is highlighted in examples of three recently published studies.