Congenital unilateral fusion of the maxilla and mandible.

We present an uncommon severe first branchial arch congenital malformation, in which complete unilateral bony fusion between the maxillary and mandibular processes was found in a newborn exposed to carbamazepine medication all through pregnancy. This condition interferes with oral feeding, intubation, growth and development. In a review of previously reported cases it was found that this anomaly was commonly associated with other abnormalities. The etiology of this malformation was uncertain in our case, as carbamazepine was not proven to be the definite cause.