Staged approach for correction of midface hypoplasia and skeletal Class III malocclusion in a growing patient with Crouzon syndrome

Abstract

The purpose of this case report was to introduce the concept of a staged approach for correcting midface hypoplasia and skeletal Class III malocclusion in a growing patient with Crouzon syndrome (CS). An 8-year-old boy with CS exhibited midface hypoplasia (SNA, 65.7°), a normally positioned mandible (SNB, 82.4°), and skeletal Class III malocclusion (ANB, −16.7°; overjet, −15.1 mm). In phase 1, fixed treatment for alignment of the maxillary anterior teeth was started at 8 years old. Facemask therapy with skeletal anchorage was started at 10 years old and continued until the pubertal growth peak (ΔSNA, 4.9°; ΔSNB, −3.0°; Δoverjet, 9.0 mm). After the pubertal growth peak (16 years old), phase 2 treatment was conducted with Le Fort III distraction osteogenesis using a rigid external distraction device (ΔSNA, 13.3°). After completion of growth (19 years old), phase 3 treatment was performed with orthognathic surgery, including Le Fort I osteotomy for anterior elongation (4.5 mm) and posterior impaction (5.0 mm) of the maxilla and sagittal split ramus osteotomy for correction of aysmmetry the mandible. Improvement of the facial profile (SNA, 85.6°; SNB, 80.2°), Class I canine and molar relationships, and normal overbite/overjet (1.9 mm; 3.3 mm) were obtained. The total treatment duration was 10 years 11 months. Treatment outcomes were well maintained at 2-year retention. A treatment flowchart was suggested as a basic guideline for selecting appropriate treatment modalities. The individualized staged approach based on the patient's growth status and degree of midface hypoplasia might help clinicians obtain good treatment outcomes in growing patients with CS.