Congenital craniofacial disorders represent approximately 20% of all birth defects. One of these disorders is syngnathia, of which only 24 cases have been reported since 1936. Twenty cases involved fusion of the alveolar processes of the maxilla and mandible. Only four are similar to the presented case, which includes bony fusion of the ascending ramus of the mandible to the zygomatic complex and the posterior part of the maxilla. This case report will present details from the 23rd week of gestation to 8 months of age when the infant underwent the first attempt to free the syngnathia. The literature is discussed and a causative mechanism and new classification are proposed.