Treatment of A Class III Patient with Quad Helix Appliance and Chin Cup: A Case Report

The mixed dentition stage provides a valuable opportunity for early orthopedic intervention in Class III malocclusion. The quad helix appliance, combined with a chin cup, may be used for maxillary expansion and sagittal control of mandibular growth during the early growth period. The purpose of this case report is to present the early treatment of a Class III malocclusion primarily associated with mandibular prognathism and transverse maxillary deficiency using a quad helix–chin cup combination. A 9-year-10-month-old girl presenting with Class III malocclusion, anterior crossbite, transverse maxillary deficiency, and a concave profile was treated with a quad helix appliance and chin cup therapy. The bite was raised with a mandibular acrylic plate to eliminate occlusal interferences, allowing maxillary expansion. Mandibular growth was controlled with a chin cup. After 25 months of treatment, positive overjet and overbite, improvement in the ANB angle, and a more balanced soft tissue profile were achieved. In prepubertal patients, particularly when cooperation is limited, a quad helix appliance that does not depend on patient compliance, combined with chin cup therapy, may contribute to favorable skeletal and dentoalveolar outcomes. However, the findings of this case report should be interpreted within the limitations inherent to single-case observations.