Temporomandibular joint imaging 2 /certified fixed orthodontic courses by Indian dental academy

DEPARTMENT OF ORAL MEDICINE DIAGNOSISDEPARTMENT OF ORAL MEDICINE DIAGNOSIS
ANDAND
RADIOLOGYRADIOLOGY
TEJAS KHAIRE IV/ITEJAS KHAIRE IV/I
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing dental education

The Temporomandibular joint (TMJ) is the jaw joint.
As the term temporomandibular indicates, this joint
includes the temporal bone and mandible. The glenoid
fossa and articular eminence of the temporal bone, the
condyle of mandible, and the articular disk between
bones make up TMJ area. This area can be very difficult to
examine radiographically because of multiple adjacent
bony structures.
Specialized imaging techniques must be used for TMJ

The transcranial provides a sagittal view of lateral
aspects of the condyle and temporal component.
It is used to evaluate the superior surface of condyle and
articular eminence.
INDICATIONS
For identifying gross osseous changes on lateral aspect
Displaced Condylar fractures
Osteoarthritis
Rheumatoid Arthritis
Outline of articular disc
Translatory movement of condyle in relation to glenoid fossa.

FILM PLACEMENT
The cassette is placed flat against the patient’s ear and centered over
the TM joint of interest, against the facial skin parallel to the sagittal plane.


HEAD POSITION
The patients head is adjusted so that the sagittal plane is vertical.
The ala tragus line is parallel to the floor.
This view is taken with the patients mouth in different positions Open mouth and closed mouth
.
BEAM ALIGNMENT
The point of entry is different according to the technique used.
A. Post auricular or Lindblom technique
Point of entry of central ray is 0.5 inch behind and 2 inch above the auditory meatus.
The beam is directed downward(+25degrees) and forward(20 degrees) and is centered on the
TMJ being examined
B. Grewcock approach
The central ray enters through a point 2 inch above the external auditory meatus.
C. Gill’s approach
The central ray enters through a point ½” inch anterior and 2” above external auditory meatus.

In all three techniques the central ray is directed caudally at an angle of +20 to +25 degree
Exposure parameters
Kvp-70
mA-07
Seconds-1.5

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It provides a sagittal view of medial pole of condyle and usually taken in open
mouth positon
FILM PLACEMENT
The cassette is placed flat against the patient’s ear and centered to a point
0.5i nch anterior to external auditory meatus, over the TM joint of interest,
against the facial skin parallel to the sagittal plane.
HEAD POSITION
The patients head is adjusted so that the sagittal plane is vertical and parallel
to the film, with the TM joint of interest adjacent to the film.
The film is centered to a point ½” anterior to the external auditory meatus
The occlusal plane should be parallel to the transverse axis of the film so
that the soft parts of nasopharynx are in one line with TMJ.

P

The patient is instructed to slowly inhale through nose during exposure,
so as to ensure filling of nasopharynx with air during exposure
The patient should open his mouth so that the condyles move away
from the base of skull and the mandibular notch of opposite side is
enlarged .
BEAM ALIGNMENT.
Point of entry of central ray is directed from opposite side cranially ,
at an angle of -5 to -10 degrees posteriorly
It is directed through the mandibular notch, that is a window between
the coronoid, condyle and the zygomatic arch, to the side below the
base of skull to the TM joint of interest
EXPOSURE PARAMETERS
Kvp-70
mA-07

It provides anterior view of TMJ, perpendicular to transcranial and
transpharyngeal projections.
FILM PLACEMENT
The film is positioned behind the patients head at an angle of 45degree to sagittal
plane.
HEAD POSITION
The patients head is positioned so that the sagittal plane is vertical. The
canthomeatul line should be 10 degree to the horizontal, with the head tipped
downwards.
The mouth should be wide open.

BEAM ALIGNMENT
The tube head is placed in front of patients face
The central ray is directed to the joint of interest, at an angle of +20degree, to
strike the cassette at right angles.

P

 The point of entry may be taken at:
 1. Pupil of same eye, asking the patient to look
straight ahead
 2. Medial canthus of same eye.
 3. Medial canthus of opposite eye
 EXPOSURE PARAMETERS
 Kvp-70
 mA-07
 Seconds-0.8
 Here the entire mediolateral dimension of the
articular eminence, condylar head, and condylar
neck is visible, which makes this view particularly
useful for visualizing condylar neck fractures.

This view is primarily meant for viewing
The condylar neck and head
High fractures of the TMJ
Quality of articular surfaces
Condylar hypoplasia or hypertrophy.
FILM PLACEMENT
The cassette is placed perpendicular to the floor in a cassette
holding device.The long-axis of cassette is placed vertically.

HEAD POSITION
The patients head is tilted downwards so that the
canthomeatul line forms a 25 to 30 degree angle with
cassette.
The film is adjusted so that the lips are centered to the
film.
Only patients forehead and tip of nose should touch the
film
The patient here is asked to keep his/her mouth wideopen.
BEAM ALIGNMENT
It is directed through the mid-sagittal plane at the level of
mandible and perpendicular to the film.
EXPOSURE PARAMETERS
Kvp-65
mA-10
Seconds 2-3

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Xeroradiography provide a finer and clearer image of TMJ
because of wide latitude and edge enhancement inherent
characteristic of this modality. Greater bony detail and
additional information, particularly in areas of overlap.
A serious drawback of this technique is unavoidable higher
dose of radiation at skin surface which is 2.4 to 16.2 times
higher than with conventional techniques.
Therefore it is not a practical method for routine TMJ
examination.

D

The purpose of submentovertex view is to identify the position of
condyles, demonstrate the base of skull, evaluate fractures of zygomatic
arch.
FILM PLACEMENT
The cassette is placed perpendicular to the floor in a cassette holding
device. The long axis of the cassette is placed vertically.
HEAD POSITION
The patient’s head and neck are tipped back as far as possible; the vertex
(top) of the skull touches the cassette .Both the midsagittal and Frankfort
plane are positioned perpendicular to floor .The head is centered on
cassette.
BEAM ALIGNMENT
The central ray is directed through the centre of head and
perpendicular to the cassette.

Panoramic radiography used to be considered a good imaging
method for evaluating TMJ since information about the teeth and
other parts of the jaws were also shown on the image. However,
the relationship between the condyle and glenoid fossa cannot be
evaluated in the panoramic film because the fossa cannot be seen
with superimposition of the base of the skull and zygomatic arch.
The morphology of the condyle becomes wider than the anatomic
structure of the condyle Panoramic radiography has also been
used in evaluating condyle fractures .


.

The soft tissue imaging can be imaged with magnetic resonance imaging
(MRI) or arthrography
ARTHROGRAPHY
The technique of TMJ arthrography was introduced in the 1940s but it was
not extensively used until the late 1970s
There are two technical methods for arthrography of TMJ. In single-
contrast arthrography, radiopaque material is injected into either the
lower or upper joint space, or into both compartments .In double-contrast
arthrography, a small amount of air is injected into the joint space after the
injection of contrast materials .
A comparative study reported that there was no statistically significant
difference in the diagnostic accuracy between these two techniques



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Several studies have shown that arthrography is an accurate imaging
method for evaluating anterior disc displacement.
The accuracy for diagnosing the position of the disc ranged from 84%
to 100%. Perforation and adhesion of the disc can also be shown by this
technique .These studies have given important evidence for diagnosis
and identification of TMJ internal derangement Arthrography is based on
plain film and tomography .
A recent study reported that using the arthrography technique might
improve the accuracy of diagnosing perforations and adhesions of the disc
in magnetic resonance imaging of TMJ (Toyama et al. 2000).
There are some advantages of this technique. Arthrography is a method
that depends upon more technical training and experience in the
observation of images.




MRI uses a magnetic field and radio frequency pulses rather than ionizing
radiation to produce multiple digital image slices
MRI with surface coil was Introduced applied to TMJ imaging in the 1980s
Several studies have compared MRI of TMJ with arthrography and CT).
The accuracy of MRI in evaluating osseous changes in TMJ was 60%
to100% and the accuracy in evaluating disc displacement was 73% to
95% . Studies showed that MRI was the best method of imaging both the
hard and soft tissues of the TMJ.
Several studies have confirmed that disc displacement In MRI showed
close associations with clicking, pain and other dysfunction symptoms of
TMJ . MRI was considered as a golden standard to evaluate the disc
position
The results of some reports have shown that MRI is not only an accurate
method to detect the disc position but also a potential technique to
evaluate the pathological changes of the masticatory muscles in TMD.





Tomography of TMJ is generated through the synchronous movement of the x-
ray tube and film cassette through an imaginary fulcrum located in the center
of the desired imaging plane. Linear tomography and complex tomography are
involved
Osseous changes : Arthrography is a good method for depicting the osseous
changes with arthrosis in TMJ
In studies of TMJ specimens obtained at autopsy, tomography has been
shown to represent the anatomic structures better than transcranial
radiography
Condyle position. For evaluation of condyle position in glenoid fossa of TMJ,
tomography has been reported to be more reliable than plain film and
panoramic radiography in a study comparing the three methods.
Tomography has been used for evaluating the condyle position and joint
space. Clinically, condyle position is still an important aspect in orthognathic
surgery and orthodontic studies .The major disadvantage of tomography is
the lack of visualization of the soft tissue of TMJ, a problem shared with
plain film radiography.


1  .
ORAL  RADIOLOGY   PRINCIPLES  AND  INTERPRETATION  5TH
EDITION
WHITE.PHAROAH
2.DENTAL  RADIOLOGRAPHY PRINCIPLES AND TECHNIQUES 3RD
EDITION
LAURA.JOEN.
3.DENTAL  AND  MAXILLOFACIAL RADIOLOGY
KARJODKAR

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