Dental and social effects of malocclusion and effectiveness of orthodontic treatment: a strategy for investigation.

Study of the effectiveness of orthodontic treatment is complicated by a variety of factors, including the need for longitudinal, multidisciplinary appraisal and difficulties of randomisation, control and sample composition. This report outlines a recent initiative adopting a longitudinal, observational approach with a cohort of approximately 1000 12-yr-olds, selected by disproportionate stratified sampling in order that occlusal features of low prevalence, but high orthodontic interest, would be well represented. In the event, 4810 subjects were listed and after certain exclusions, 3420 children were screened. Using preselected screening criteria, 663 with specific occlusal features were selected and an additional 355 children with nonspecific features were randomly allocated on a pro-rata basis. This gave a final study population of 1018. Baseline dental data included the recording of caries, periodontal status and mandibular function. Study models were obtained and analysed using a new standardised technique for recording the alignment of individual teeth. Photographs of the face and dentition were collected and a rating system developed to score dental and facial attractiveness. Social-psychological data were recorded via self-rating questionnaires, interviews, parental questionnaires, teacher questionnaires and peer ratings.