Effects of activator use on the articular disc in Class II adolescent individuals using magnetic resonance imaging

Abstract

Aim: This study evaluated the effects of activator-type functional appliance therapy on the articular disc of the temporomandibular joint (TMJ) following forward movement of the mandible in individuals with skeletal Class II malocclusion via magnetic resonance imaging (MRI). Specifically, this study compared individuals with normal growth and development to those who had undergone treatment.

Methodology: This study was conducted using a controlled, randomized, crossover design. The study group consisted of 40 individuals with skeletal Class II malocclusion, whereas the control group included 20 individuals with the same anomalies who did not receive treatment. The treatment group underwent therapy with an activator-type functional appliance for a period of six months, during which MRI scans were obtained from participants. The soft- and hard tissue characteristics of the TMJ were assessed using MRI. Data were analyzed using SPSS software, with a statistical significance level of p<0.05.

Results: In the treatment group, significant changes were observed in the anterior position of the mandibular condyle and TMJ disc angles. With respect to disc position and configuration, an increase in the biconcave structure and in the anterior angle, and a decrease in the posterior angle, were noted in the treatment group. These changes were not statistically significant in the control group. Additionally, improvement in the TMJ disc position was detected in individuals in the treatment group.

Conclusion: Activator-type functional appliance therapy can have positive effects on the mandibular condyle and TMJ disc position in individuals with Class II malocclusion. MRI has been highlighted as an effective method for evaluating soft and hard tissues of the TMJ. This treatment approach supports orthodontic outcomes by promoting TMJ adaptation.