Temporomandibular Ankylosis

Temporomandibular Ankylosis Definition

The temporomandibular joint (TMJ) is commonly known as the jaw joint. It is formed by articulation between mandible (lower jaw) and temporal bone of the skull. Ankylosis is Greek word meaning “stiff joint”. Ankylosis of the temporomandibular joint refers to stiffening or fusion of the articular surfaces of the mandible and temporal bone on one or both the sides. It is characterized by facial asymmetry, limited jaw opening and deviation of the mandible.

Temporomandibular Ankylosis  Symptoms

The ankylosis can be unilateral (one sided) or bilateral (both sides) in nature.

Unilateral TM Ankylosis

  • Unilateral ankylosis is associated with marked facial asymmetry.
  • The chin is receded with an underdeveloped lower jaw on the affected side.
  • The lower jaw and chin deviates on opening the mouth towards the affected side.
  • The face appears full and rounded on the affected side and flat and elongated on the normal side.
  • The lower margin of the lower jaw appears to be notched.
  • The mouth opening is limited and extent of limitation may vary according to the type of ankylosis.
  • The dental findings include orthodontic problems such as cross bites and class II malocclusion.

Bilateral TM Ankylosis

  • In bilateral ankylosis the entire mandible is symmetrical, underdeveloped and smaller in size.
  • The small size of the mandible gives a characteristic bird face deformity with receding chin.
  • The angle of the jaw from neck to chin is reduced or almost absent.
  • Notching is present on either side of the chin on lower margin of the jaw.
  • The upper jaw is narrow and upper incisors are proclined leading to an open bite,
  • Severe malocclusion, crowded teeth and poor periodontal health is also commonly seen in patients with bilateral ankylosis.
  • The mouth opening is less than 5mm or completely diminished in few cases.

Temporomandibular Ankylosis Causes

The chief predisposing factors for the development of temporomandibular ankylosis are trauma and infection in or around the joint region.
Injury to the temporomandibular joint (TMJ) may occur during a forceps delivery. Trauma during intrauterine life leads to congenital ankylosis. After birth, trauma can be caused by direct blow at the joint region or at the chin level. Any injury lading to hemorrhage inside the joint space is capable of initiating the process of ankylosis.

Infection of the joint can be direct or indirect. It can occur secondary to a systemic sepsis, osteomyelitis, scarlet fever and tuberculosis. The direct spread of infection can occur in cases of middle ear infections, space infections and parotid gland abscess. Degenerating diseases such as rheumatic arthritis and osteoathritis can also lead to temporomandibular ankylosis.

Temporomandibular Ankylosis Treatment

Treatment of temporomandibular ankylosis is always surgical. Early surgical correction is essential for regaining the joint function and aesthetics. Surgical method depends on age of onset of ankylosis, extent of ankylosis and associated facial deformity. The techniques used for treating temporomandibular ankylosis include condylectomy, gap arthroplasty or interpositional arthroplasty.


Condylectomy is recommended in cases with fibrous ankylosis. The entire condyle is resected and replaced prefabricated condylar prosthesis made up of steel, titanium or vitallium.

Gap arthroplasty

Gap arthroplasty is advocated in extensive bony ankylosis.

Interpositional arthroplasty

Interpositional arthroplasty is advocated to avoid recurrence of ankylosis.

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