A comparative 3D finite element analysis of mandibular advancement with clear aligners and twin block appliances.

BACKGROUND

The aim of this study was to compare the effects of two commonly used functional orthodontic appliances, Twin Block and Mandibular Advancement appliances with clear aligners, on dentoskeletal structures and the temporomandibular joint in individuals with Class II malocclusion using a three-dimensional finite element method.

METHODS

Separate three-dimensional finite element models were created for each appliance using ANSYS SpaceClaim software (Version 22.0). The maxillomandibular complex, craniofacial sutures, TMJ structures, and dentition were modeled. 12 N force value for temporalis muscle activity during mandibular advancement was applied to simulate forward mandibular positioning in both models. Displacement and stress distribution values were analyzed in various anatomical regions, including maxillary and mandibular bones, dental arches, and TMJ components.

RESULTS

The Twin Block appliance produced greater displacement in mandibular incisors and resulted in increased skeletal changes, particularly in the mandibular body and condylar regions. It also caused higher stress levels in the TMJ disk and condyle compared to Mandibular Advancement appliance with clear aligners. Additionally, greater displacement was observed at craniofacial suture points in the Twin Block group.

CONCLUSIONS

While both appliances demonstrated orthopedic and orthodontic effects beneficial for Class II correction, the Twin Block appliance exhibited stronger skeletal influence and more favorable TMJ stress patterns. The MA appliance, however, may offer more controlled dentoalveolar effects and improved patient comfort, making it a practical alternative in cases requiring esthetic and compliance-focused treatment strategies.