Congenital fusion of the maxilla and mandible.

Congenital fusion of the maxilla and mandible (syngnathia) is rare and can present in a wide range of severity from single mucosal bands (synechiae) to complete bony fusion (synostosis). Congenital synostosis of the mandible and maxilla is even less common than synechiae, with only 25 cases reported in the literature. Most of them presented as an incomplete, unilateral fusion. A 4-year-old boy was referred to the authors' emergency unit with asphyxia after vomiting. The authors found the child could not open his mouth. His upper and lower jaws were fused, with only a 2- to 3-mm gap in the anterior part. X-rays and computed tomography scans showed that there was a bony fusion of the ramus of the mandible to the zygomatic complex and the posterior part of the maxilla. In addition, there was significant mandible hypoplasia. After performing an osteotomy (to treat the fusion between the bilateral ramus mandible, maxilla, and zygoma), the authors performed a temporomandibular joint reconstruction using a silicon block. After the completion of these procedures, they observed that the mouth could be opened 32 mm. After 2 years of mandibular lengthening performed with an external distracter, the patient's facial appearance and occlusion became more acceptable. An extremely rare case is described, and the existing literature is reviewed.