This systematic review has been commissioned by the Chief Medical Officer of the Department Health to ‘carry out an up to date expert scientific review of fluoride and health’ (Paragraph Healthier Nation). Overall, the aim has been to assess the evidence on the positive and negative effects of population wide drinking water fluoridation strategies to prevent caries. To achieve this aim five objectives identified: Objective 1: What are the effects of fluoridation of drinking water supplies on the incidence of Objective 2: If water fluoridation is shown to have beneficial effects, what is the effect over and 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 geographical locations, bringing equity? Objective 4: Does water fluoridation have negative effects? Objective 5: Are there differences in the effects of natural and artificial water fluoridation?