In patients with skeletal maxillary protrusion caused by severe mandibular deficiency, surgical orthodontics involving mandibular body distraction osteogenesis are sometimes selected depending on the amount of forward displacement of bone fragments and the severity of temporomandibular joint symptoms. Distraction osteogenesis can accelerate new bone formation at the lengthened portion and extension of the surrounding soft tissue, however, there are few reports of long-term follow-up cases. Here we report on the 10-year follow-up of a patient with severe mandibular deficiency and mandibular deviation toward the left side, who underwent mandibular body distraction osteogenesis followed by retention.
The patient was a 21-year-old Japanese female. After pre-surgical orthodontic treatment for 1 year and 6 months, distraction osteogenesis and genioplasty were performed. The mandibular body was lengthened by 7.0mm on the right side and 9.5mm on the left side. Postsurgical orthodontic treatment was combined with the use of intermaxillary elastic for approximately 8 months.
The duration of active treatment was 2 years and 4 months and the Angle Class I relationship was obtained with appropriate incisal relationships. Mandibular body distraction osteogenesis and genioplasty improved anteroposterior disharmony between the maxilla and the mandible, chin recession, and mandibular shift to the left side. The patient underwent approximately 6 years of mechanical retention followed by natural retention. Ten years after starting retention, the mandibular midline had shifted 1.5mm to the left and only slight relapse of the mandibular position was recognized. Occlusal relationships were maintained with few changes in overjet of 0.5mm. No marked morphological changes were recognized in the mandibular condyle. Stable occlusion obtained from the active treatment and less change in the condylar morphology during the retention seem to contribute to the long-term stable treatment results.
