Orthodontic Treatment and 5-year Follow-up in Skeletal Open Bite Case with Congenital Muscular Dystrophy

Congenital muscular dystrophy (MD) is characterized by progressive muscle weakness. Such patients often present distinctive facial features characterized by excessive vertical growth due to increased muscle breakdown in the perioral muscles such as the masticatory and facial muscles, often resulting in skeletal open bite. Orthognathic treatment is one option for improving the maxillofacial morphology and malocclusion in such patients. However, it is often too risky to apply general anesthesia in such cases due to systemic myofunctional deterioration. Therefore, in many instances, the only option is to rely on orthodontic treatment alone to improve malocclusion. Furthermore, there are few reports on changes following orthodontic treatment in congenital MD patients, and many matters remain unclear regarding long-term occlusal stability. The present case was a girl aged 9 years and 3 months at the initial visit. Her chief complaint was masticatory dysfunction and articulation disorder due to open bite. The first phase of treatment delivered expansion of the upper and lower dental arches and myofunctional therapy prior to transition to the second phase. At the start of the second phase of treatment, the patient was aged 15 years and 9 months. It was determined that orthognathic treatment including surgical invasion would be too risky due general problems related to muscular function. This report describes a case of skeletal open bite due to congenital MD in which an orthodontic approach alone was adopted as camouflage treatment involving extraction of the maxillary left and right second deciduous molars and mandibular left and right first premolars. The post-treatment stability of the resulting occlusion is also described.