Abstract :
Background: Class II malocclusion is the most frequent maxillo–mandibular skeletal discrepancy in preadolescents, typically linked to mandibular retrognathia. Growth?modification appliances are widely used, yet outcomes vary because success hinges on timing, comfort, and sustained compliance. Self?Determination Theory (SDT) highlights that satisfying autonomy, competence, and relatedness needs promotes internal (self?endorsed) motivation, crucial for adherence to removable functional appliances. The Medium Opening Activator (MOA) is a contemporary functional design intended to improve tolerability while simultaneously addressing sagittal discrepancy, deep bite, and lower?incisor control.Case: We describe the two?stage management of a ten?year?old girl treated first with an MOA during the growth?modification phase, followed by comprehensive fixed therapy. High appliance wear was maintained through autonomy?supportive communication, neutral progress benchmarks, individualized micro?goals, and adaptive twin sibling comparison that provided informational feedback and mutual encouragement. These processes likely supported need satisfaction and internalization, contributing to favourable Class II correction, deep?bite improvement, and long?term stability.Conclusion: By operationalizing self?determination principles (autonomy?supportive dialogue, informational benchmarks, individualized micro?goals, prosocial encouragement), this case achieved sustained MOA wear, successful Class II correction, and stability at five?year post?treatment follow?up. Need satisfaction (autonomy, competence, relatedness) remains a crucial determinant of removable appliance outcomes; when present, the MOA functions as an effective first?phase intervention in appropriate growing Class II patients.
Keyword :
Class II malocclusion, Medium opening activator, Patient compliance, Self-Determination Theory, Intrinsic motivation, Orthodontic adherence