Syngnathia consists in a congenital fusion of maxilla and mandible. It is a rare condition and it may be present in a wide range of severity, from a single mucosal band (synechiae) to a complete bony fusion (synostosis). In this report we present 3 cases of complete congenital bony fusion of the maxilla and mandible with different treatments and outcomes. We discuss the boundaries of the current classification for oromandibular limb hypogenesis syndrome (OLHS) and embryological/developmental aspects related to these conditions. The first case is associated with the cleft palate, hypo development of the tongue, micrognathia and malformations in the 4 limbs and other 2 cases with congenital maxillomandibular fusion without any limbs malformations. In these particularly cases, 2 of them, show complete zygomatic-maxillomandibular fusion. These 3 cases might arouse a discussion about the boundaries of the current classification for OLHS and if syngnathia with bony fusion could be an isolated congenital deformity.