Soft and Hard Tissue Changes Following Treatment of Class Ⅱ Division 1 Malocclusion with Twin-Block and Myofunctional Appliance: A Pilot Study

Background Many cases of Class Ⅱ deformities have been reported to be treated with prefabricated appliances. The aim of this study was to distinguish the clinical effect of traditional custom-made appliances and prefabricated appliances in the treatment of Class Ⅱ division 1 malocclusion. Therefore, soft and hard tissue changes following treatment of Class Ⅱ division 1 malocclusion using the twin-block(TB) appliance was compared to that using the Myofunctional Research Company(MRC) appliance(K1 + K2) combined with oral myofunctional treatment(OMT)(MRC + OMT). Methods The study included 22 children(6 boys and 16 girls aged 9–11 years) with Class Ⅱ division 1 malocclusion along with mandibular retrognathism with a 5–12 mm overjet, basic normal maxillary status, and stage 2 or 3 cervical vertebral maturation(CVM). Participants were randomly assigned into two groups, the TB group and the MRC + OMT group for 12 months. Standardized lateral cephalograms were used to assess skeletal, dental, and soft tissue changes from pre-to post-treatment. Independent t-tests were used to compare the initial and final cephalometric status and tissue changes between the groups. Results The TB and MRC + OMT groups resulted in different degrees of lateral changes; however, improvements of skeletal and soft tissue indices were significantly greater in the TB group than in the MRC + OMT group. Conclusion TB was more effective than MRC + OMT in treating children aged 9–11 years with Class Ⅱ division 1 malocclusion. However, further research using custom-made appliances with OMT is recommended, and further investigations are needed to confirm these findings.