[A PhD completed. The development and evaluation of a smartphone app for adolescent orthodontic patients].

The primary aim of the dissertation was to develop and evaluate a smartphone app, the WhiteTeeth app, designed to promote good oral health behaviour and oral hygiene among adolescent orthodontic patients between the ages of 12 and 16. The app's development and evaluation was guided methodically by intervention mapping (IM). Development thus starts with an analysis of the health problem and the identification of the psychosocial factors and health behaviour related to it. To identify the psychosocial factors underlying oral health behaviour in our target group, a systematic literature review with meta-analysis was conducted,a cross-sectional clinical study and semi-structured interviews. Then, to target these psychosocial factors and facilitate continuous behavioural support, various behaviour-changing techniques were incorporated into the app. The app provides feedback on users' oral health behaviour and allows users to evaluate and monitor their behaviour. Finally, a randomised controlled trial was conducted. This showed that the app had improved oral hygiene in adolescent orthodontic patients after 12 weeks.