School-based epidemiological surveys and the impact of positive consent requirements.

A requirement to obtain positive consent for participants in school-based dental epidemiological surveys was introduced in 2006. Concern has been expressed about the impact of the changes on the validity of results as the need to obtain positive consent is likely to reduce the numbers participating. An additional concern is that the new requirement may also lead to samples that are biased, resulting in them being unrepresentative of the population from which they are drawn. This paper aims to discuss the implications of the changes on the quality of future school-based dental epidemiological surveys, and whether they threaten the validity of survey findings at a time when such information is critical in informing the local commissioning of dental services.