Skeletal characteristics and treatment outcome of five patients with Robin sequence.

OBJECTIVE: To examine the variation in the precise skeletal characteristics and the treatment outcomes of five Japanese Robin sequence cases. MATERIALS AND METHODS: The birth histories and orthodontic records of five Japanese Robin sequence patients were collected and analyzed. RESULTS: All cases had a retrognathic appearance with small SNA and SNB angles. They had significantly steep mandibular planes with lingual tipped incisors in both arches. The gonial angles in two cases were within the Japanese norm, whereas the remaining three showed significantly enlarged angles. Moreover, all cases showed a significantly shorter ramus length, but the mandibular body was short in only two cases. All had moderate or severe crowding in both arches, and therefore extraction of lateral dentition or lateral incisors was performed in conjunction with orthodontic treatment. An edgewise multibracket appliance was placed, and labial tipping of the lower incisors was performed in all cases. All obtained normal functional occlusion after active treatment, but the retrognathic appearance remained in most cases. CONCLUSIONS: The present cases with Robin sequence showed variation in the gonial angle and mandibular body length, although all commonly exhibited smaller SNA and SNB angles with significantly steep mandibular planes. Significant labial tipping of the lower incisors was required during the active treatment, and all cases finally obtained functional occlusion, indicating the relatively good prognosis on the occlusion of this sequence.