|Year : 2014 | Volume
| Issue : 3 | Page : 266-270
Diagnosis of temporomandibular joint (TMJ) ankylosis in children
Priya Shetty, Ann Thomas, B Sowmya
Department of Pedodontics, A.J. Institute of Dental Sciences, Mangalore, Karnataka, India
|Date of Web Publication||2-Jul-2014|
Department of Pedodontics, AJ Institute of Dental Sciences NH17, Kuntikana, Mangalore - 575 008, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Temporomandibular joint (TMJ) ankylosis involves fusion of the mandibular condyle with the base of the skull. It results in functional, esthetic, and psychosocial limitations, if it affects children at an early age. Hence, it is important to recognize and diagnose the pathology and provide immediate treatment alternatives to improve the patient condition. In this case report, we highlight the diagnostic perspective of TMJ ankylosis in children, and the use of 3D computed tomography as an effective diagnostic aid.
Keywords: 3D computed tomography, ankylosis, children, diagnosis, three dimensional computed tomography
|How to cite this article:|
Shetty P, Thomas A, Sowmya B. Diagnosis of temporomandibular joint (TMJ) ankylosis in children. J Indian Soc Pedod Prev Dent 2014;32:266-70
|How to cite this URL:|
Shetty P, Thomas A, Sowmya B. Diagnosis of temporomandibular joint (TMJ) ankylosis in children. J Indian Soc Pedod Prev Dent [serial online] 2014 [cited 2020 Aug 8];32:266-70. Available from: http://www.jisppd.com/text.asp?2014/32/3/266/135848
| Introduction|| |
Temporomandibular joint (TMJ) ankylosis is a disabling condition of mastication in which the condylar movement is limited by a mechanical problem in the joint (true ankylosis) or a mechanical cause not related to the joint components (false ankylosis). ,
In children, trauma is identified as the main cause of TMJ ankylosis (57-63%). ,, The other etiological factors are infections, rheumatoid arthritis, hypoparathyroidism, psoriasis, and burns.  Ankylosis in children can have a tremendous effect on physical and psychological well-being due to restricted mouth opening, inability to chew food, and poor oral hygiene. ,, Due to growth deformity, the child may become shy and reclusive and have a low self-esteem. , Trauma to TMJ in early childhood can affect the growth potential of the mandible. , Any traumatic injury to the joint, if left unnoticed and untreated immediately can cause loss of growth and function resulting in muscle and bone atrophy and subsequently micrognathia, microgenia, and retrognathia. ,, The retrognathic mandible with its short rami together with the bigonial distance affects the dimensions of the oropharynx, giving rise to obstruction of the airways. ,
It is hypothesized that the extravasation of the blood into the joint, disrupts the fibrocartilage integrity and allows the in growth of the fibrous connective tissue into the joint. Subsequently, this results in the ossification and fusion of the mandibular condyle to the articular surface of the temporal bone. 
The long standing ankylosed joint results in chronic isometric contractions of the masticatory muscles, viz., temporalis muscle, pterygomasseteric muscle sling, and suprahyoid depressor muscle. This also results in elongation of the coronoid process, shortening of the mandibular ramus, recession of the chin and elongation in a cephalocaudal direction and development of the antegonial notch, which is the only evident radiographic feature. ,
If ankylosis is not detected in the early stages of a fibrous union, it can cause a severe facial deformity.  The position of the tongue, pattern of swallowing, and activity of the muscles of facial expressions are all functional contributors of the deformity.
In children, unilateral ankylosis of TMJ causes facial asymmetry due to deviation of the chin towards the affected side. Complete absence of mouth opening and recession is a characteristic feature of bilateral ankylosis, resulting in a "bird face deformity". ,
The effective treatment of TMJ ankylosis is based on a detailed preoperative radiographic assessment of the type and extent of ankylosis. However, the conventional radiographs do not give an accurate visualization of the ankylosed joint. Currently, three-dimensional (3D) tomography reconstruction allows elaboration of accentuated images for diagnosis and treatment planning. ,
This case report highlights the need for early diagnosis and the utilization of 3D computed tomography (CT) as an effective diagnostic aid in the management of TMJ ankylosis.
| Case Report|| |
A five-year-old boy reported to our department with the chief complaint of limitation of mouth opening [Figure 1]. History revealed that the child had a fall when he was two years old and had complained of pain and swelling near the ears, which gradually subsided. However, there was a gradual reduction of mouth opening, as a result of which the child was unable to eat properly. This led to the parents consulting physicians and dentists, who prescribed analgesics and muscle relaxants. Finally, they reported to our department for evaluation.
On extra-oral examination, the child did not show any obvious asymmetry or deformity of the face. On intraoral examination, [Figure 2] the mouth opening was very minimal, 2 mm, and he was unable to protrude the mandible. An orthopantomogram was prescribed for complete radiographic evaluation. The orthopantomogram did not give a clear picture of the temporomandibular joint and the associated structures [Figure 3]. The antegonial notch was, however, visible on the radiograph. There was superimposition of the joint and associated structures. Hence, 3D CT was advised for a comprehensive evaluation of the joint. This provided an excellent visualization of the enclosed joint on the left side, the condoyle head was fused to the articular surface of the temporal bone, with elongation of the coronoid process and the development of the antegonial notch [Figure 4].
|Figure 2: Orthopantomogram showing superimposition of the joint and associated structures|
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|Figure 3: 3D computed tomography (CT) showing ankylosis of the joint on the left side|
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The unaffected side of the joint showed flatness and elongation of the ramous and midline shift. However, no bony union of the joint was visible radiographically, confirming unilateral ankylosis.
This facilitated surgical management, and coronoidectomy and costochondral graft replacement was performed. Postoperatively, the child showed satisfactory mouth opening, which improved considerably after physiotherapy [Figure 5].
| Discussion|| |
It is essential to take into consideration certain clinical and radiographic features for a precise diagnosis of TMJ ankylosis in children.
According to Graziani, patients who present a TMJ ankylosis have a limited opening of the mouth of 1-2 mm.  Zarb et al., asserted that TMJ ankylosis patients are able to obtain 5-7mm of interincisal opening but do not have any protrusion or lateral mandibular movement.  When the problem is unilateral, patients can reach 3-4mm of lateral movement towards the affected side. 
Certain characteristics help distinguish fibrous ankylosis from bony ankylosis. Patients with fibrous ankylosis will find forceful opening of the mouth painful but will be able to protrude the mandible slightly. However, bony ankylosis patients will not find forceful opening of the mouth painful but will be unable to protrude the mandible. ,,
In fibrous ankylosis, the articulating surfaces is usually irregular because of erosions. The joint space is usually very narrow and two irregular surfaces appear to fit one another like a jigsaw puzzle. In bony ankylosis, the joint space may be partly or completely obliterated by the osseous bridge, which may be a slender segment of bone or a large bony mass. This extensive new bone may fuse the condyle to the cranial base. The morphologic changes involve a compensatory elongation of the coronoid process and deepening of the antegonial notch in the ramus on the affected side as a result of muscle function during attempted mandibular opening. If ankylosis occurs before mandibular growth is completed, the growth of the affected side of the mandible is inhibited. ,,
Since 1930, radiographic images have been used as an important diagnostic tool in TMJ diseases. ,
TMJ imaging includes plain radiography, panoramic radiography, tomograms, conventional CT, arthrography, three dimensional CT, magnetic resonance imaging, ultrasonography, and radionuclide imaging. , The conventional radiographs often necessitate multiple views of the joint, as patient positioning is crucial in panoramic imaging. If the head is inclined posteriorly, the image of the condyle appears flattened and if head is inclined anteriorly, the condyle appears sclerotic. As the child is unable to open the mouth, he will not be able to place his chin on the focal trough, while taking an orthopantomogram; this can cause multiple imaging and hence, more radiation exposure to the patient.
There is a disadvantage of poor structural resolution from superimposition of adjacent anatomic structures. The extension of ankylosis is not visualized in most of the conventional radiographs. With 3D CT imaging, the size and extent of the lesion is clearly visualized, the procedure lasts for a minute, and motion artifacts are minimized. 
The main advantages are that the structural relationships between hard and soft tissues can be observed and superimposition of images is eliminated. Availability of data in a 3D format has allowed the construction of life-sized models that can be used for trial surgeries. In the present case, 3D CT was used as an adjunct to orthopantomogram. In general, the characteristic radiographic feature is that the condyle is bridged with the temporal bone. It could be a small piece of bone or even a large bone mass that could involve the condyle, temporal bone, and zygomatic process. In long standing cases, the antegonial notch appears severely depressed, and the TMJ area may be obliterated with dense sclerotic bone. , Fibrous ankylosis presents a normal image or small areas of erosion but the joint space is reduced with limited mandibular opening movements. ,
However, the main drawback is that these changes cannot be visualized in the initial stages. Though bony ankylosis shows osseous alteration, the diagnosis of fibrous ankylosis is difficult due to the absence of any radiographic features. Hence, when a child reports of an injury to the joint area, application of a cold compress and administration of anti-inflammatory analgesics may be considered as a preventive modality to reduce the extravastion of blood into the joint and the subsequent inflammatory changes leading to ankylosis.
The treatment of TMJ ankylosis involves early surgical intervention, elaborate resection and aggressive physiotherapy for six months post-operatively. , A variety of techniques for treatment of TMJ ankylosis have been described including intraoral coronoidectomy, ramus osteotomy, high condylectomy, forceful opening of the jaw under general anesthesia, lysis of adhesion of the pterygoid space,  autogenous costochondral graft, and free vascularized whole joint transplants. ,,,,,,
To summarize it can be suggested that the pedodontist or the clinician should consider any traumatic injury to the TMJ as a risk for ankylosis in children. Hence, if a child reports immediately or with a recent history of trauma, the first line of treatment should be to reduce the inflammation in the joint spaces and prevent intra-articular hematoma by applying ice or cold compress to the joint and prescribing anti-inflammatory analgesics.
In a child with hypomobility of the joint, checking the level of restricted mouth opening, prescribing radiographs for accurate visualization of the joint, physiotherapy for improving hypomobility, and prevention of fibrous and bony changes in the joint should be considered.
If the radiographic features clearly indicate the onset of ankylosis, referral to a surgeon for early surgical intervention is mandatory. It is important to stress that no case of ankylosis be treated without a previous radiographic diagnosis. With advances in TMJ imaging methods, such as 3D CT, it is possible to accurately diagnose and plan treatment in children.
| Conclusion|| |
Very often, a lack of understanding of the clinical and radiographic features of ankylosis can result in the dentist misdiagnosing or failing to diagnose ankylosis. A delayed diagnosis can result in prolongation of the appropriate treatment, which can be detrimental in a growing child. An early diagnosis and treatment of ankylosis in children is essential to restore normal function and dentofacial balance.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]