Craniofacial Changes Related to Maxillary Protraction Therapy in Mandibular Prognathism Associated With a...

Mandibular prognathism results from a complex interplay of genetic predisposition and environmental influences. In this study, we aimed to report the successful orthodontic management of a pediatric patient with mandibular prognathism that was potentially associated with a thyroglossal duct cyst in the floor of the mouth. This condition was treated with maxillary protraction therapy to improve the craniofacial morphology. A 9-year-5-month-old male patient presented with a major complaint of an anterior crossbite. Medical history revealed a congenital thyroglossal duct cyst in the floor of the mouth, which was surgically excised 8 months before the initial orthodontic consultation. Clinical and radiographic examination revealed severe mandibular prognathism characterized by maxillary hypoplasia and relative mandibular prognathia. We initiated maxillary protraction therapy using a protractor with a chin cup. Furthermore, significant skeletal improvements were observed following 30 months of active treatment: The SNA angle increased by 4.3°, the SNB angle decreased by 2.8°, the ANB angle increased by 7.1°, and the Wits appraisal improved by 14.1 mm. Long-term follow-up showed stable maintenance of these skeletal corrections at 4 years posttreatment. This case report suggested that a thyroglossal duct cyst in the floor of the mouth may be an environmental factor in mandibular prognathism pathogenesis. In addition, it demonstrates the clinical efficacy of maxillary protraction therapy in the orthopedic correction of Class III malocclusion during the active growth period.