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Captcha Image Reload image challenge


Oral Medicine

Authors: Dr. Md. Asdullah, Dr. Kauser K .Khawaja, Dr. Ansul Aggarwal

Abstract

The present review will give an update on temporomandibular joint (TMJ) imaging using CBCT. It will focus on diagnostic accuracy and the value of CBCT compared with other imaging modalities for the evaluation of TMJs. There are several imaging modalities to visualize the TMJ. Cone beam computed tomography (CBCT) is a developing technique that is being increasingly used in dentomaxillofacial imaging due to its relatively low-dose high-spatial-resolution characteristics. Research in TMJ imaging has been greatly inspired by the advent of CBCT. In this paper we aim to discuss the present scenario of the role of CBCT in TMJ imaging.

Keywords:Cone beam computed tomography, temporomandibular joint disorder, temporomandibular joint imaging

INTRODUCTION

Diagnostic radiology plays an important part in treating patients with TMD effectively and efficiently. Radiological investigations are of paramount importance in the diagnostic assessment of a patient with TMD. The American Academy of Oral and Maxillofacial Radiology (AAOMR) has established the rationale for image selection for diagnosis, treatment planning and follow up of a patient with conditions affecting the TMJ (parameter 2).1 Conventional radiographic TMJ projections like transpharyngeal, transcranial, panoramic radiograph, conventional tomographic sections of TMJ may be adequate in a number of clinical situations. But there are bony alterations that occur in these disorders like erosions, osteophytes, pneumatisation of articular eminence that are difficult to be detected in conventional radiographs due to overlapping of the anatomic structures. This warrants the use of advanced imaging modalities like Magnetic Resonance Imaging (MRI), arthrography, conventional Computed Tomography (CT) and Cone Beam Computed Tomography (CBCT).2,3 CBCT is a relatively recent increment in the ever expanding horizon of clinical CT technologies. The first prototype clinical CBCT scanner was used in 1982 at Mayo Clinic. The commercial CBCT scanners made their entry almost a decade after the initial adaptation for angiographic applications. Ever since, several CBCT systems have evolved that have been extensively used in the field of medical clinical imaging.4 This article aims to highlight the role of CBCT research of TMJ imaging.
 
CBCT of normal temporomandibular joint CBCT image TMJ with 3D reconstruction
 
CBCT of normal temporomandibular joint CBCT image TMJ with 3D reconstruction
 
CBCT of normal temporomandibular joint CBCT image TMJ with 3D reconstruction


CBCT IN TMJ IMAGINE

A large body of literature has been published in recent times due to the fact that CBCT has inspired research in TMJ imaging. An important advantage of CBCT imaging of TMJ is that it allows accurate measurements of the volume and surface of the condyle. These measurements are extremely advantageous in clinical practice when treating patients with TMJ dysfunction.

Osteoarthritis of the TMJ is an age – related degenerative disease seen in almost 40% of patients above the age of 40 years. It causes bony changes in the TMJ like flattening, sclerosis, formation of osteophytes, erosion, resorption of the condylar head, erosion of the mandibular fossa and reduced joint space. Flattening (59%) and osteophyte (29%) are the most prevalent degenerative changes seen on CBCT.5

Many in vitro cadaveric studies have explored the role of CBCT in assessing bony defects and osteophytes. Erosive changes in the TMJ are most effectively diagnosed using CBCT in the 6 inch FOV as compared to the 12 inch FOV.6 Alexiou, et al. used CBCT to evaluate the degenerative changes and concluded that patients in older age groups are expected to have more frequent and more severe bone changes than those in younger patients.7 Alkhader, et al. performed a comparative study between CBCT and MRI. According to them CBCT is better than MRI in detecting changes in shape (flattening, osteophyte formation or erosion) rather than changes in size. They concluded that this was probably because MRI had limited spatial resolution and increased slice thickness (>3mm) in clinical use.

Also other problems like presence of fibrous tissues inside the TMJ, proximity of lateral pterygoid muscle to the articular surface of the condyle and presence of air spaces in the temporal bone can impede the accuracy in the interpretation of MRI.8 However there is a poor correlation between condylar changes observed on CBCT images and clinical signs and symptoms seen in patients with TMJ osteoarthritis (TMJOA).9

CBCT plays an important role in diagnosing early stages of juvenile idiopathic arthritis (JIA) in children which, when undetected, can damage facial development and cause growth alterations. Farronato, et al. concluded from their study that CBCT can be used to volumetrically quantify the TMJ damage in these patients by measuring condylar and mandibular volumes.10 Condylar asymmetry is very common in children with JIA. CBCT shows a wide variety of condylar destruction patterns which could be small erosions within the cortex to almost complete deformation of the head of the condyle.11

The TMJ is often involved in patients with multiple maxillofacial fractures. Here again in most cases neither medical CT nor conventional dental radiography alone can address all the diagnostic challenges that are encountered. CBCT enables us to meet the patient needs by providing adequate information regarding the nature of fracture, its extent and relative locations of important anatomic structures.12

Conclusion

In a relatively short period of time, CBCT has emerged as a cost- and dose-effective alternative to CT for examination of the TMJs, although it may be more sensitive to motion artefacts. The imaging modality is superior to conventional radiographic methods, as well as MRI, in the assessment of osseous TMJ abnormalities. However, it should be emphasized that the diagnostic information obtained is limited to the morphology of the osseous joint components, cortical bone integrity and subcortical osseous abnormalities. For the assessment of inflammatory activity and soft-tissue abnormalities such as internal derangement in patients with TMD, MRI is the method of choice.

Refrences
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