Transverse maxillary expansion in the nonsurgical orthodontic treatment of adolescent Class III malocclusion: a case report

Skeletal Class III malocclusion presents a complex therapeutic challenge, particularly in adolescent patients with concomitant transverse maxillary deficiency and facial asymmetry who decline orthognathic surgery. This case report describes the nonsurgical management of a 13-year-old male patient with a clinically complex Class III malocclusion associated with a relatively mild-to-moderate sagittal skeletal discrepancy, characterized by maxillary retrusion, mandibular prognathism, transverse maxillary constriction, anterior and posterior crossbite, and facial asymmetry. Comprehensive three-dimensional diagnosis, including cone-beam computed tomography, confirmed a clinically significant transverse discrepancy with a Penn index of −8 mm, suggesting a functional contribution to mandibular deviation. Treatment was performed using maxillary skeletal expansion followed by fixed orthodontic appliances and Class III intermaxillary elastics. Maxillary expansion resulted in a 6-mm increase in transverse width and a substantial improvement in the transverse maxillomandibular relationship, accompanied by spontaneous improvement in mandibular positioning and facial symmetry. Post-treatment cephalometric analysis demonstrated improvement of the skeletal Class III relationship, with the ANB angle increasing from −2.42° to −0.49°, while vertical skeletal parameters remained stable. These changes were interpreted cautiously and were considered to reflect a combination of transverse correction, elimination of occlusal interferences, and dentoalveolar adaptation rather than major sagittal skeletal modification. Although mild additional proclination of the maxillary incisors was observed as part of orthodontic camouflage, satisfactory occlusal relationships, functional improvement, and enhanced facial balance were achieved. This case highlights the importance of identifying and addressing transverse maxillary deficiency as a key component in the nonsurgical management of selected adolescent patients with Class III malocclusion, and suggests that maxillary skeletal expansion may enhance the effectiveness of orthodontic camouflage when surgical intervention is not accepted, while emphasizing that such outcomes should not be extrapolated to patients with truly severe skeletal Class III discrepancies.