Modified Versus Clear Twin Block for Skeletal Class II Malocclusion

This study aims to evaluate the effectiveness of a modified Twin Block appliance compared to a conventional clear Twin Block appliance in the treatment of skeletal Class II malocclusion caused by mandibular retrusion in growing patients. This is a two-arm randomized controlled clinical trial including patients aged 10-13 years diagnosed with skeletal Class II malocclusion. Participants will be randomly allocated into two equal groups. Skeletal, dental, and soft tissue changes will be assessed using lateral cephalometric analysis and cone-beam computed tomography (CBCT). Additionally, temporomandibular joint (TMJ) health, pain perception, and functional tolerance will be evaluated using standardized clinical indices and patient-reported outcome measures. The study aims to compare the modified appliance with the conventional design in terms of skeletal improvement, TMJ safety, and patient acceptance.

Inclusion Criteria: * Systemically healthy patients. * Patients willing to accept removable functional appliance therapy. * Skeletal Class II malocclusion (Angle Class II Division 1). * Skeletal Class II due to mandibular retrusion (ANB \> 5°, Wits appraisal \> 5 mm, SNB \< 78°, NSAr ≥ 125°, with normal maxillary position). * Normal or horizontal growth pattern (MM angle \< 30° or Björk angle \< 40°). * Growth stage corresponding to MP3 stage or pre-pubertal peak according to hand-wrist radiograph (Björk and Helm, 1967). * No severe dental crowding in the dental arches and no significant maxillary dental protrusion. * Absence of congenital anomalies, trauma, burns, or surgical scars affecting the temporomandibular joint or craniofacial structures. * Absence of systemic or rheumatologic diseases affecting the temporomandibular joint. Exclusion Criteria: * Presence of clinical signs or symptoms of temporomandibular joint disorders. * Functional mandibular deviation. * Presence of unilateral or bilateral posterior crossbite. * Previous orthodontic treatment.