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Year : 2021  |  Volume : 8  |  Issue : 1  |  Page : 60-64

Case report on congenital syngnathia: Surgery and a 4-year follow-up

1 Swiss Cleft Centre, BSES MG Hospital, Mumbai, Maharashtra, India
2 Department of Cleft and Craniofacial Surgery, BSES MG Hospital, Mumbai, Maharashtra, India
3 Cleft Children International is the Organisation founded by Prof. Hermann Sailer, Switzerland

Date of Submission25-Jul-2020
Date of Acceptance18-Sep-2020
Date of Web Publication13-Jan-2021

Correspondence Address:
Dr. Niyati Satish Balse
Swiss Cleft Centre, BSES MG Hospital, Mumbai, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jclpca.jclpca_24_20

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Syngnathia is an extremely rare craniofacial malformation affecting the upper and lower jaws, in particular, and adjacent bony and soft tissues, to lesser or greater extent. Fusion of jaws leads to complications such as compromised airway and breathing, feeding difficulty, and poor growth. An early multidisciplinary intervention, surgery at the appropriate time, and meticulous postoperative monitoring are most imperative in its management. We describe a case of a 6-month-old child with congenital syngnathia that was managed successfully. Four-year follow-up revealed satisfactory outcomes and the need for corrective jaw surgeries after growth completion for improved function and esthetics. Anesthesia considerations, feeding, surgical management, postoperative care, and follow-up as well as growth regulation have been discussed in detail.

Keywords: Congenital maxilla-mandibular fusion, hypoplastic mandible, syngnathia, temporomandibular joint ankylosis

How to cite this article:
Ladani P, Balse NS, Jayakar B, Sailer H. Case report on congenital syngnathia: Surgery and a 4-year follow-up. J Cleft Lip Palate Craniofac Anomal 2021;8:60-4

How to cite this URL:
Ladani P, Balse NS, Jayakar B, Sailer H. Case report on congenital syngnathia: Surgery and a 4-year follow-up. J Cleft Lip Palate Craniofac Anomal [serial online] 2021 [cited 2021 Apr 11];8:60-4. Available from: https://www.jclpca.org/text.asp?2021/8/1/60/298625

  Introduction Top

“Syngnathia” is the congenital adhesion of the maxilla and mandible. It may be complete or partial; fibrous (synechiae) or bony (synostosis) adhesion of the jaws.[1] It may manifest as an isolated entity or may be associated with other malformations such as cleft lip, cleft palate, and digital, genital, and other systemic anomalies.[1] In 1936, Burkett reported the first case of syngnathia.[2] Not more than 50 cases have been reported in the literature.[2] True maxilla-mandibular fusion without the involvement of adjacent structures is an extremely rare condition.[3] Surgical separation of the fused jaws is a prerequisite for long-term management of airway and feeding difficulties.

We report a case of congenital syngnathia that was successfully managed in our unit. There are no standard protocols for the management of syngnathia due to rarity of this condition and limited literature on this.[1] Our patient showed no signs of respiratory distress, and hence, a treatment strategy consisting of elective surgical release of the bony fusion under general anesthesia was considered.

  Case Report Top

A case of congenital syngnathia was referred to our unit. The child was born to a 29-year-old female at 40 weeks of gestation by normal vaginal delivery. Birth weight was 2700 g, length was 40 cm, and head circumference was 32 cm. The baby girl was 6 months old when referred to our unit. Her parents described difficulty in feeding the baby due to restricted mouth opening [Figure 1]. The baby was the second child of a nonconsanguineous couple with no history of any congenital deformities in the family. The pregnancy was uncomplicated with no history of teratogenic exposure. The child appeared active and in good status. Physical examination revealed severely restricted mouth opening, micrognathia, and severe facial asymmetry. The skin color and other facial features appeared normal. Intraoral examination revealed an intergum distance of 1 mm on the right side and complete bony fusion of the jaw on the other side of the midline with mucosal continuity intact [Figure 2]. History revealed that the vitals of the baby were stable and the child showed no signs of respiratory distress, maintaining 100% oxygen saturation levels at birth.
Figure 1: A 6-month-old child with congenital bony syngnathia

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Figure 2: Intraoral examination revealing an interalveolar distance on 1 mm on the right side and complete fusion of jaws with intact mucosal continuity on the left side

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Computed tomography with three-dimensional reconstruction of the skull was advised [Figure 3]. It revealed a complete bony fusion of the jaws on the left side with a normal interalveolar distance on the right side. The temporomandibular joint (TMJ) on the right side appeared indistinct with hypoplastic coronoid and condyle, whereas on the left side, the TMJ was absent with no precise demarcation of individual bones ipsilaterally. The rest of the facial skeleton appeared normal. Surgical release under general anesthesia was planned.
Figure 3: Computed tomographic three.dimensional reconstruction revealing complete bony fusion of the jaws and absence of temporomandibular joint on the left side

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Surgical procedure

Flexible fiber-optic bronchoscope was used for intubation and general anesthesia was administered. A thorough intraoral examination was done under? General Anesthesia (GA). The mucosal adhesions on the right side were severed using surgical blade and diathermy, whereas mucoperiosteum was raised and the fused area was exposed on the left side. The bony fusion was osteotomized; gap arthroplasty was done. Manipulation using Smith's spreader and Doyen's mouth gag was done, and a mouth opening of 25 mm was achieved with normal jaw movements [Figure 4] and [Figure 5]. Hemostasis was ensured without complications. No airway problems were encountered postoperatively and the vitals were stable. The child was closely monitored, fed orally, and discharged on the 5th postoperative day. Gentle passive physiotherapy was advised.
Figure 4: Surgical incision and manipulation

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Figure 5: Complete separation of the fused jaws after surgical manipulation and mechanical separation bilaterally to achieve adequate mouth opening

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One-year follow-up revealed a mouth opening of 22 cm, satisfactory jaw movement, and presence of deciduous teeth [Figure 6]. Four-year follow-up revealed prominent facial asymmetry, malocclusion, and dental caries [Figure 7]. Difficulty in mastication and oral hygiene maintenance were reported by the parents. Interference on the speech was also noticed. Further management in the form of mandibular distraction osteogenesis for functional and esthetic improvement was advised to the parents. We proposed carrying out the corrective surgery in stages. There is a possibility of persistent bony attachment (or Sometimes, after the primary surgery mild relapse may occur in the form of bony or fibrous reattachment) which may need separation prior to starting distraction. Hence, the sentence. This would be followed by the removal of distraction device and bone augmentation in the deficient regions of the mandible, 3–4 months after surgery. We plan to begin the orthodontic therapy in the permanent dentition phase followed by orthognathic surgery, if needed after completion of growth.
Figure 6: A 1-year follow-up showing satisfactory mouth opening and erupted deciduous teeth

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Figure 7: A 4-year follow-up revealing restricted mouth opening and asymmetrical facial features, malocclusion, and disproportionate jaws indicating need for corrective surgeries postgrowth completion

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  Discussion Top

Fused defects of the jaws may be broadly classified as soft tissue fusion defects (synechiae) and hard tissue fusion defects (syngnathia), based on the nature of connecting tissue. Dawson in 1996 reviewed 14 cases of bony fusion and proposed a classification as follows: Type 1: simple syngnathia (with no associated congenital anomalies in head and neck); Type 2-complex syngnathia; (a) associated with aglossia and (b) associated with agenesis or hypoplasia of the mandible.[4] Laster in 2006 suggested that the extent of associated deformities depends upon the timing, duration, and magnitude of traumatic forces and thus proposed a more detailed classification as follows: Type 1A: Simple anterior syngnathia without any other congenital deformity in the head and neck; Type 1B: Complex anterior syngnathia associated with other congenital deformity in the head and neck; Type 2A: Simple zygomatico-mandibular syngnathia; and Type 2B: Complex zygomatico-mandibular syngnathia associated with clefts or TMJ ankylosis.[5] Our case could be considered as Laster's Type 2B since the fusion extended posteriorly and the TMJ of the left side was indistinct suggestive of ankylosis.

A persistent buccopharyngeal membrane is considered to be the most common cause of synechiae.[6] The other possible causes are local ischemia of the amniotic bands causing pressure on the first branchial arch or a genetic predisposition toward anomalous fusion of the adjacent epithelial surfaces.[7]

Syngnathia may be associated with syndromes such a popliteal pterygium syndrome (PPS), Van der Woude syndrome (VWS), orofacial digital syndrome, cleft palate lateral synechia syndrome, and nonhereditary aglossia-adactylia syndrome.[4],[7] PPS and VWS are due to mutation in gene encoding interferon regulatory factor-6 on the chromosomes 1q32–q41.[1]

The timing of surgical release may vary. Puvabanditsin et al. reported successful surgical release of fibrous bands in 4-day-old child with syngnathia and VWS,[6] whereas Dawson et al. reported a series of cases wherein one of the syndromic cases was allowed to gain weight and surgery was performed at 1 year of age. In the same report, the authors also point out that as infants are obligate nose breathers, it is unlikely that an early release may help airway security and also that early intervention may produce relapse, thus advocating a delayed release to prevent multiple unsuccessful surgeries.[4] Many delay the surgery to avoid damage to facial growth centers and facial nerve.[8]

Complete syngnathia is surgically managed under general anesthesia, with fiber-optic intubation being the technique of choice in elective cases.[1] In case of emergency such as compromised airway or unavailability of fiber-optic intubation facility, surgical tracheostomy may be performed. In our case, we preferred fiber-optic intubation for general anesthesia and the child was reversed and extubated uneventfully with no postoperative airway complications.

Management techniques range from gradual mechanical separation of synechiae over a period of few weeks[8] to the use of distraction for a period of 10 days[9] for complete bony syngnathia. Hard bony adhesions may require use of osteotomes and mechanical separators to release the bony fusion and arthroplasty to gain adequate mouth opening.[10] Mechanical manipulation needs to be done gently since excessive force may lead to fracture of the jaws.[10] There have been reports wherein packs were sutured to the raw surfaces for 3 weeks to prevent bleeding and re-fusion and keep the jaws distracted.[8] In our case, we used osteotomes and Smith's spreader as the mechanical separator and did a gap arthroplasty to achieve adequate mouth opening.

Postoperative care is very imperative; airway, breathing, and feeding need to be monitored. Neonatal Intensive Care Unit (NICU) care may be needed. Postoperative death has also been reported and is mainly due to respiratory failure secondary to aspiration pneumonia.[3] As far as the outcome is concerned, most cases report an immediate improvement in mouth opening, following which normal feeding habits can be gradually resumed. Valnicek and Clarke advocated bottle feeding postoperatively to increase the range of movements of the tight TMJ ligaments.[8] Our patient was advised passive physiotherapy, postsurgery, in the form of mouth opening exercises performed by the mother. Feeding was normal and there were no complications in any form. A high rate of recurrence has been reported in the literature.[3] Facial asymmetry and skeletal and dental malocclusion may be noticed over a period of time, and these may be addressed by means of distraction osteogenesis, orthodontics, other orthognathic surgeries, and soft tissue and bone augmentation procedures. In our case, clinical examination at 4 years suggests mild relapse and facial asymmetry. The asymmetry mainly exists due to hypoplastic mandible and deficient ramal height, which may be a result of persistent bony fusion of the left zygoma and ramus. We intend to address this by performing distraction osteogenesis to lengthen the ramus, in addition to separation of the persistent bony fusion. The process of distraction will allow controlled lengthening of the bony as well as soft tissue.[11] Dental malocclusion shall be managed by means of orthodontics in the permanent dentition phase. Corrective orthognathic surgeries, if required, shall be performed after growth completion.

  Conclusion Top

Early intervention in the form of surgery is the only definitive management tool in case of complete bony syngnathia. We obtained satisfactory results in our patient. Prognosis is good in terms of mouth opening and feeding. A long-term follow-up is necessary to monitor the growth and maintenance of normal mouth opening and jaw movements.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


We are thankful to Cleft children International, Zurich, Switzerland, for funding the surgeries of this patient and many other cleft patients.

Financial support and sponsorship

Cleft children International, Zurich, Switzerland, supported the study.

Conflicts of interest

There are no conflicts of interest.

  References Top

Albano del Cristo Barreto Paternina CB, Duro EA, Benitez SM. Early treatment of congenital syngnathia. A case report. J Pediatr Neonat Individ Med 2018;77:2281-692.  Back to cited text no. 1
Broome M, Vial Y, Jacquemont S, Sergi C, Kamnasaran D, Giannoni E. Complete maxillo-mandibular syngnathia in a newborn with multiple congenital malformations. Pediatr Neonatol 2016;57:65-8.  Back to cited text no. 2
Mohan A. Syngnathia–congenital maxillomandibular fusion: Case report and literature review. J Oral Maxillofac Surg 2018;76:1096.e1-6.  Back to cited text no. 3
Dawson KH, Gruss JS, Myall RW. Congenital bony syngnathia: A proposed classification. Cleft Palate Craniofac J 1997;34:141-6.  Back to cited text no. 4
Laster Z, Temkin D, Zarfin Y, Kushnir A. Complete bony fusion of the mandible to the zygomatic complex and maxillary tuberosity: Case report and review. Int J Oral Maxillofac Surg 2001;30:75-9.  Back to cited text no. 5
Puvabanditsin S, Garrow E, Sitburana O, Avila FM, Nabong MY, Biswas A. Syngnathia and Van der Woude syndrome: A case report and literature review. Cleft Palate Craniofac J 2003;40:104-6.  Back to cited text no. 6
Tomlinson JK, Liem NT, Savarirayan R, Meara JG. Isolated and syndromic syngnathism: Management, implications, and genetics. Ann Plast Surg 2006;57:231-5.  Back to cited text no. 7
Valnicek SM, Clarke HM. Syngnathia: A report of two cases. Cleft Palate Craniofac J 1993;30:582-5.  Back to cited text no. 8
Konas E, Aliyev A, Tunçbilek G. Congenital maxillomandibular syngnathia: A new management technique using distraction techniques. J Craniofac Surg 2015;26:e68-70.  Back to cited text no. 9
Mortazavi SH, Motamedi MH. Congenital fusion of the jaws. Indian J Pediatr 2007;74:416-8.  Back to cited text no. 10
Yoon HJ, Kim HG. Intraoral mandibular distraction osteogenesis in facial asymmetry patients with unilateral temporomandibular joint bony ankylosis. Int J Oral Maxillofac Surg 2002;31:544-8.  Back to cited text no. 11


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]


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