Knowledge of wisdom tooth removal: influence of an information leaflet and validation of a questionnaire.

Different methods are now being employed to increase patient's knowledge of operative procedures for the purpose of ensuring informed consent and improving satisfaction with the service provided. Information leaflets are being used as an additional aid in general practice and in hospital units but many are ambiguous and poorly designed. The evaluation of such written information is seldom conducted. Where evaluation has been reported, the measures employed to assess the benefit of the intervention are poorly validated. This study was conducted to help validate a measure of knowledge concerning removal of impacted third molar and to assess in the longer term the effect of the introducing an information leaflet for patients attending the oral surgery clinic at a dental teaching hospital. Predictions were made about how the knowledge scale would perform under certain conditions. These predictions were subsequently tested in a sample of 156 subjects: dental students (n = 55), sixth-formers (n = 50) and relatives of patients attending a dental hospital (n = 51). All the predictions made about the behaviour of the new scale were confirmed, thereby strengthening the validity of the newly designed measure. This approach of conducting preliminary work to gain an understanding of a new measure's behaviour is advocated as an essential first step in the evaluation of initiatives to provide patient information about dental and oral surgical procedures.