Congenital fusion of the maxilla and mandible (congenital bony syngnathia)


A rare case of syngnathia (maxillomandibular fusion) is described in a 2-year-old boy who presented from a rural area of Saudi Arabia. The child had the problem since birth and had undergone two surgical attempts to release the fusion at another institution but both had failed and recurrence occurred. In the authors’ institute, the patient underwent two separate surgical procedures at the age of 2 and 3 years. Both procedures were followed by a period of aggressive physiotherapy, but the patient presented with re-fusion of the mandible and the maxilla 1 year after the first operation and 5 months after the second operation. It was decided to defer treatment until puberty. The cause of the relapse may be the high osteogenic potential because of his youth or the failure of the parents to maintain the active physiotherapy protocol because they live in a rural area and close follow-up was difficult. A possible genetic predisposition for bone formation at this site should be investigated.

Congenital maxillomandibular fusion syngnathia is rare. A single mucosal band is termed synechiae and complete bony fusion is called synostosis. Congenital synostosis of the mandible and maxilla is less common than syngnathia .

The fusion may be unilateral or bilateral and may involve only the soft tissues or both the hard and soft tissues . Fusion of the alveolar ridges of the mandible and maxilla is reported more commonly than fusion of the ascending rami of mandible to the posterior area of the maxilla and zygomatic complex .

The authors report a case of a 2-year-old boy with congenital syngnathia, who underwent four surgical procedures to release the fusion before the age of 3 years. All procedures failed and the maxilla and mandible fused together again.

Case report

A 2-year-old boy was referred to the authors’ hospital from a rural hospital suffering from inability to open his mouth since birth ( Fig. 1 a ). His parents noted that he had not been able to open his mouth or chew, so his diet consisted of liquids only. He appeared to be malnourished and underweight, with poor oral hygiene.

Fig. 1
Preoperative frontal photograph of the patient (A); and immediate postoperative frontal picture immediately following the first operation (B).

The mother had had a healthy gestation period and there was no history of illness, trauma or drug use. The baby was the family’s first child, and there was no history of similar anomalies in close relatives. Routine blood tests were within normal values.

The mother reported that the child had undergone two surgical interventions; the first when he was 10 days old and the second at 6 months. She said he managed to open his mouth for a short period after the first surgery, but 3 weeks later the condition recurred and the second surgery did not solve the problem. Examination revealed that the patient’s jaws were fused bilaterally in the posterior regions and there was an 8 mm open bite in the anterior region. The mandible appeared retruded, but there were no other intra- or extra-oral anomalies.

A CT scan revealed normal bilateral temporomandibular joint (TMJ) structures with no bony ankylosis or soft tissue fusion in the coronal view ( Fig. 2 c ); but fusion of the ascending ramus with zygomatic process of the maxilla was identified bilaterally ( Figs 2a and 3a,c ). A 3D CT scan showed a bilateral elongated coronoid process ( Figs 2a and 4 ) and a healed fracture line on the left side, which probably resulted from the previous attempts to open the mouth when the child was 10 days old ( Fig. 4 ).

Fig. 2
Preoperative 3D CT scan showing the extent of bony fusion (arrow) and the elongated coronoid process (A). Postoperative 3D CT scan showing the osteotomy cut (arrow) (B). Coronal CT scan showing normal condylar head on both sides (C).

Fig. 3
Preoperative coronal CT scan (A) showing the extent of the fusion at the posterior part of the maxilla with the mandibular ramus and (B) a postoperative coronal CT scan showing the extent of the bilateral osteotomy (arrows). Preoperative axial CT (C) shows the extent of the fusion and a postoperative axial CT (D) shows miniplates used on the zygomatic arch (arrow) for fixation after completing the osteotomy.

Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Congenital fusion of the maxilla and mandible (congenital bony syngnathia)
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