Congenital Maxillomandibular Syngnathia: Review of Literature and Proposed New Classification System

Abstract

Purpose: Maxillomandibular fusion (syngnathia) is a rare craniofacial anomaly. It occurs as either fibrous (synechiae) or bony (synostosis) fusion of jaw or fusion of mandible to zygoma, tuberosity, hard palate and temporal bone. There are several documentations delineating this condition but owing to its varying presentation, association with both intraoral and extraoral anomalies and syndromes, reviewing it has been as uphill task. The non-unanimous description of cases in the literature and the use of different nomenclatures make it difficult to classify this condition.

Methods: Extensive search of the literature was done from the year 1936 to 2018 which included a total of 118 cases with 62 cases of bony fusion, 48 cases of fibrous fusion and 8 cases of combined fusion, i.e., fibrous on one site and bony on another side.

Results: This paper proposes a novel, simple and explicit classification system on the basis of nature of fusing tissues, location and extent, association with syndrome after reviewing the existing literature. Furthermore, this review reports 4 new cases of syngnathia along with their clinical, radiographic features and their management protocol.

Conclusions: This classification can be generalized to all the cases of syngnathia and can further facilitate in its appropriate diagnosis and treatment plan.

Keywords: Anomaly; Fusion; Synechiae; Syngnathia; Temporomandibular joint.

Fig. 1

a Facial profile frontal bossing and phocomelia. b Anterior bony fusion involving maxillary and mandibular arch. c 3D CT showing bony fusion. d Sagittal view showing bony fusion. e Intraoperative view release of bony fusion

Fig. 2

a 3D CBCT view showing bony fusion on right side extending from alveolar process of the mandible till ZMC. b Coronal sectional showing bony fusion. c Intraoperative view of release of fusion

Fig. 3

a, b Fibrous band extending bilaterally between right and left posterior maxillary and mandibular alveolar ridge. c 3D CBCT showing no bony fusion. d Coronal section showing midline cleft palate. e Mouth opening achieved after release of mucosal adhesion

Fig. 4

a Multiple discrete fibrous adhesion between maxillary anterior and posterior alveolar arches. b 3D CT showing normal TMJ with no bony involvement

Fig. 5

Suggested management protocol