Self-determination theory guided oral self-care training for adolescents-A cluster randomised controlled trial.

Quality oral self-care is a key element in maintaining oral health, which is important for students' general health, their overall well-being and learning. The cluster randomised controlled trial tested the following hypotheses: (1) self-determination theory (SDT)-guided dental education is superior to conventional dental instruction in modifying oral self-care in adolescents; (2) after the discontinued dental education, improved oral self-care is only maintained for short rather than long term and (3) multiple predictors explain variations in adolescents' oral self-care at different observation periods. The intervention group (N = 97) received three face-to-face educational sessions to facilitate adolescents' intrinsic motivation, while the control group (N = 99) had one conventional dental instruction session. Dental plaque scores (% of tooth area covered by dental plaque) indicated a lack of oral self-care. Linear multivariable models tested the following predictors of oral self-care at different observation periods: socio-demographics (sex, socio-economic status, school) and self-determination attributes (autonomy, relatedness, competence). Results indicated that from baseline to the 6-month follow-up, dental plaque scores decreased (oral self-care improved) in the intervention group but not in the control group. At the 12-month follow-up point, there were no significant differences in mean plaque scores between the study groups. Baseline plaque levels (β = 0.807), the type of dental instruction (theory guided vs. conventional) (β = 0.208), relatedness (β = 0.106) and competence (β = 0.102) were significant predictors that explained 67.6% of the variance in dental plaque scores at the 12-month follow-up point. The theory-guided education was superior to conventional verbal instruction in improving adolescent oral self-care; however, this improvement was only maintained short term. Variations in adolescent oral self-care at short- and long-term observation points were explained by baseline oral self-care levels and two SDT components: relatedness and competence.