Syngnathia refers to congenital fusion of the maxilla and mandible. The fusion can be classified depending on the nature of the connecting tissue as either fibrous or bony fusion. Laster et al. (2001) proposed a classification for bony syngnathia into 4 types. Type 1a is simple anterior syngnathia characterized by bony fusion of the alveolar ridge only; type 1b is complex anterior syngnathia characterized by bony fusion of the alveolar ridges and also associated with other congenital malformations in the head and neck region; type 2a is simple mandibulozygomatic syngnathia characterized by bony fusion of the mandible to zygoma; and type 2b is complex mandibulozygomatic syngnathia characterized by bony fusion of the mandible to the zygoma and associated with cleft palate and/or temporomandibular joint ankylosis. [from
OMIM]