TMJ ProjectionsTMJ Projections

Temporomandibular Joint Temporomandibular Joint ProjectionsProjections

Introduction

The temporomandibular joint is one of the most difficult areas to investigate radiography. The type of imaging technique depends on the specific clinical problem whether imaging of order soft issue. The imaging modalities is used to evaluate the anatomy of TMJ, osseous contours, condyle and range of motion. The soft issue imaging is indicated to know the information about the disk position, to image the abnormalities of muscles and surrounding tissues.

Radiographic ProjectionsRadiographic Projections

Conventional Radiographic Projections

Transcranial view Transpharyngeal view Transorbital view Panoramic view Submentovertex view

Other Investigations

Tomography (CT) MRI Arthrography Arthroscopy

Transcranial ViewTranscranial View

Indications TMJ Pain dysfunction syndrome Size and position of disk Range of movement of joints

Advantage Simplicity Cheap and effective method Radiation exposure low

Technique

The patient is placed in the craniotome with head rotated through 90o

so that the TMJ is touching the film and the sagittal plane of head parallel to the film. The X ray tube is directed downwards 25o to the area of interest. The procedure is performed for open and closed mouth.

Transpharyngeal viewTranspharyngeal view

Indications

Osteo arthritis Rheumatic arthritis Fracture of neck and head of the condyle TMJ pain dysfunction syndrome

Technique

The patient holds the cassette against the side of the face over the TMJ area of interest. The film and the sagittal plane of the head are parallel. The X-ray beam is directed superiorly at 5o-10o to the sigmoid notch of the opposite side. The procedure is performed for opened and closed mouth.

Transorbital viewTransorbital view

Indications

Investigate the articular surface of condyle and disease within the joint

Fracture of the condylar neck and to show its medio-lateral displacement

Technique

The patient holds the cassette behind the ear and the head is tilted down 10o so that the canthomeatal line is horizontal. The X-ray beam is directed from the front of the patient through the contra lateral orbit. The procedure is performed for opened and closed mouth.

Panoramic viewPanoramic view

Indications

TMJ pain dysfunction syndrome Investigate disease within the joint # Condylar heads or necks Condylar abnormalities

Technique

Panoramic, images both condylar heads and technique can be modified by raising the X-ray tube and cassette carriage assembly to a slightly higher level in relation to patient. But these are limited usefulness because of the thick image layer and the oblique distorted view of the joint. Gross changes in the condyle can be observed.

Submentovetex viewSubmentovetex view

Indications

Condylar displacement Rotation of the mandible Curvature of mandible Displacement of the fractured zygomatic

arch

Technique

The film cassette is placed vertically in a holding device of the craniotome. The patient head and neck should be extended backward as far as possible, with the vertex of the skull at he centre of the cassette. The canthomeatal line should extend 10o past vertical so that frankfort line and is vertical and parallel to the film. The central ray is directed from below the mandible towards the vertex of the skull.

Other Investigations

Tomography

It is a radiographic technique that produce multiple thin image slices free of superimposition of overlapping structures. In TMJ it provides information about the three dimensional shape and the internal structure of the osseous components of the joints.

Advantages Extent of ankylosis Extent of neoplasm

MRI

It is a non-invasive technique producing high resolution images. MRI is mostly applied in diagnosis of internal derangements.

Arthrography

It is a technique in which an indirect image of the disk is obtained by injecting a radio opaque contrast agent into one or both joint spaces under fluoroscopic guidance.

Arthroscopy

It is a newly advanced technique which gives a direct visualisation of the TMJ which is considered to be the last line of procedure.

SummarySummary

The search for sharp, distortion-free imaging modalities for both hard and soft tissue has led to to the development of multiple conventional techniques and the adaptation of new technologies to the TMJ imaging. Hence the type of investigation depends upon several factors including Pt’s history, pt’s age, their signs and symptoms and the facilities available.