oral medicine and radiology

1. Dept. Oral Medicine and Radiology
Govt. Dental College Trivandrum
Seminar Topic : TMJ IMAGING
Presented by,
ASWATHY.B
Final year part 1
GDC Trivandrum

2. Contents
 Introduction
 Hard tissue imaging Techniques
 Soft tissue imaging Techniques
 Conclusion
 References

3. Introduction
 A thorough understanding of the anatomy and
morphology of the TMJ is essential so that a normal
variant is not mistaken for an abnormality.
 Several variable must be considered when selecting the
type of imaging techniques to use, including the specific
clinical problem to be addressed, whether the imaging of
the hard or soft tissue is desired, the strength and
limitations of the modalities being considered, the cost of
the examination and the radiation dose.
 Both joints should be imaged during the examination for
comparison.

4. TMJ Imaging
Types of imaging techniques depends on,
 Specific clinical problem
 Need for image of hard or soft tissue
 Amount of information image
 Cost
 Radiation dose
TMJ Imaging
Hard tissue imaging
Soft tissue imaging

5. Hard tissue Imaging
1. Tomography
 conventional
 computed
 OPG
 CBCT
2 Conventional
 Submentovertex
 Transcranial
 Transpharangyeal
 Transorbital
 Lateral oblique

6. Soft tissue imaging
 Arthrography
 MRI
 Ultrasound
Abnormalities in TMJ Imaging
In Hard tissue imaging,
 Bony ankylosis
 Remodelling
 Developmental anomalies
 Neoplasm
 Trauma or fracture
 Range of motion

7. In soft tissue imaging,
 Disc position
 Disc perforation
 Joint effusion
 Inflammatory condition
 Joint space calcification
Panoramic imaging
 The panoramic image is a useful tool for providing a broad
overview of the anatomic structures of and around the tmj.
 It serve as a screening radiograph only.
 It is used to identify gross osseous changes like,
1. Assymmetry
2. Extensive erosions
3. Tumors
4. Fractures
5. Osteophytes

8. Limitations
1. Low quality images
2. Provide thick image layer
3. Oblique and distorted view
4. No information regarding condylar positioning and function
5. Superimposition by skull base and zygomatic arch
Plain film imaging modalities
The plain film usually consists of combination of following
projections and allows visualization in various planes.
 Transcranial projection
 Trasnspharyngeal projections
 Transorbital projections
 Submentovertex projections

9. Transcranial projection
 It is a view that aids in visualizing the sagittal view of the
lateral aspect of condyle and temporal compartment.
 It is taken in both open and closed mouth position
Patient position : sagittal plane is perpendicular to the ground
Cassette: parallel to sagittal plane
Central ray: point of entry is two and a half inches above external
auditory meatus and behind
Vertical angulation: 25°
Horizontal angulation : 20°
Film position : Cassette is placed flat againt ear and centered
over tmj of interest
Point of exit : Tmj of interest

11. Uses
 For identifying gross osseous changes in lateral aspect of
joint
 Displaced condylar fracture
 Studying range of motion of tmj
 Joint space calcification
 Limitations
 Super imposition of ipsilateral petrous part of temporal
bone
 Changes in Central and medial surfaces not seen
 Condylar position difficult to determine especially if
individualisation of horizontal angulation is not done for
each patient.

12.  Trasnspharyngeal projections
 Also known as PARMA Projection or MACQUEEN DELL Technique
 It provide the sagittal view of medial pole of condyle.
 It is taken in open mouth position
Patient position
 Sagittal plane : perpendicular to ground
 Coronal plane : perpendicular to ground
 Cassatte : parallel to sagittal plane
 Mouth open position
Central ray
 Entry : sigmoid notch of opposite side
 Vertical angulation : - 5 °to - 10°
 Horizontal angulation : 10 °posterior to line following right and left bony
meatus
Film postion
 Against patient ear
 Centered to half inch anterior to external auditory meatus
 Exit point : coronoid, condyle and zygomatic arch of opposite side below base
of skull

14. Uses
 To see the medial aspect of condyle
 To see gross changes in medial aspect especially erosive changes
Limitations
 Temporal component not imaged well
 Only open mouth position is possible

15. Transorbital projections
It is taken in the open or protruded position and depicts the entire medial lateral
aspect of condyle in frontal plane.
Also called Zimmer Projection
Patient position
Sagittal plane : perpendicular to ground
Right baseline parallel to ground
Mouth open position
Central ray
Vertical angulation : 10°
Horizontal angulation : 30°
Entry : ipsilateral orbit
Exit: ipsilateral condyle
Film position
Behind patient ‘s head
Angle 45 ° to sagittal plane

17. Uses
 Provide anterior view of tmj
 Mediolateral eminence of articular eminence seen
 For seeing condylar neck fracture, gross generative
changes
 Limitation
 Only neck is seen in cases of reduced condylar
movement

18. Submentovertex projections
 It provides aview of skull bone and condyle in a horizontal plane
 Structures seen : symmetrical Projection of petrosa, mastoid
process, foramen ovale, spinosum canals, carotid canals,
sphenoidal sinuses, mandible, maxillary sinus, nasal septum,
odontoid process of atlas etc.
Patient position
 Head: Centre of Cassette
 Neck and head – tipped as far as possible
 Mid sagittal plane : perpendicular to plane of film
Central ray
 90°to film and mid sagittal plane, 90° to imaginary line joining
mandibular first molars

19.  Uses : gives a view of base of skull and condyles, determine the
angulations of long axis of the condylar head , evaluating facial
assymmetry, condylar displacement.

20. Tomography
 It is a radiographic technique designed to image more clearly
objects lying within plane of interest.
 Image outside the area of interest are blurred out.
Types,
1. Conventional tomography
2. Computed tomography
3. Cone beam computed tomography
Conventional tomography
 Also known as body section radiography
 Film based tomography
Equipments
 X- ray tube
 Radiographic film

21. Procedure
 X- ray tube and radiographic film are placed on opposite sides of fulcrum,
imaginary point located with in the body’s plane of interest ( focal plane).
 During exposure, tube and film move in opposite direction synchronously
about fulcrum which is static. Thus the image of objects with in the focal
plane are Clearly formed and those outside are blurred.
Advantages
 Multiple thin image slices are produced which permit visualization of
structures free of Superimposition.
Disadvantages
 Images which reduced contrast
Uses
 Provide 3D shape
 Internal osseous components
 Extent of ankylosis
 Neoplasm
 Imaging complex fractures
 Complication from implants

22. Indications
 Tomography of sinuses
 Tomography of mandible
 Tomography of facial bones to study facial structures
 For dental implant patients
 Tomography of tmj in conjunction with arthrography
Computed tomography
 Synonyms : computed axial tomography, computerized
axial transverse scanning
 Sectional images are produced
1. Axial
2. Coronal
3. saggital

23. Equipments
 Radiographic tube emits fan shaped x- ray beam
 Scintillation detector or ionization chambers
 Here both move in a synchronized manner around the patient.
Indication
 Investigation of tmj
Cone beam computed tomography
 Principle : cone shaped x- ray source
 CBCT examination is usually acquired with the patient in the closed
mouth position with teeth in maximum intercuspation.
 CBCT system allows low resolution image acquisition to be done in
open mouth or other position to evaluate range of motion

24. Indications
 Determining the presnce and extent of ankylosis
 Neoplasm
 Fractures
 Evaluating complications from the use of polytetrafluoroethylene or
silicosheet implants and identifying heterotropic bone growth.
Soft tissue imaging
Indication
 Disc position and morphology
 Image abnormalities in muscle or surrounding tissues
Abnoramalities of soft tissues
 Disc perforation
 Disc position
 Fibous ankylosis
 Joint effusion
 Infkammatory condition
 Joint space calcification

25. Magnetic Resonance Imaging
 MRI uses static and gradient magnetic fields and non
ionizing electromagnetic radiation in the form of
radiofrequency pulses to produce tomographic images
Principle
 Transfer energy to spinning hydrogen protons
 Resonance frequency for protons lies with in the
radiofrequency band of electro magnetic spectrum.
 The examination may be performed with the use of T1
weighted, proton density or T2 weighted pulse sequence
depending on the type of information required.
 Proton density images are slightly superior to T1 weighted
images in demonstrating osseous and discal tissues,
whereas T2 weighted images demonstrate inflammation
and joint effusion.

26. Indication
 For tmj marrow changes and soft tissue components
Contraindications
 Patient who have a pacemaker or some other implanted devices,
intracranial vascular clip, metal particles in vital Structures.
 Patient with claustrophobia
Arthrography
 It is a technique in which an indirect image of the disk is obtained
by injecting a radio opaque contrast agent into the joint spaces
under fluoroscopic guidence.
Indications
 Position and function of disk
 History of persistent locking
 Disk pain and dysfunction

27.  Disk perforation
 Joint dynamics
 Disk displacement
Contra Indications
 Infections in preauricular region
 Patient allergic to contrast media
 Patient withbleeding disorders and on anticoagulant
therapy.
Complications
 Vascular injury
 Extravasation of irrigation fluid into surrounding tissues
 Infections
 Nerve injury

28. Arthroscopy
 This procedure helps in the direct visualization of
internal joints
 Last line of investigation
 Procedure is similar to arthrography
 Used for evaluating articular cavity condition
Advantages
 Safe procedure
 Direct visualization
 Minimal post operative complications
 Color change is clearly seen

29. Ultrasonography
 Used for the study of tissues of human body with
utilizationof reflection of high frequency sound waves
ranging between 1-20MHz
 Tranducer generate high frequency Ultrasound waves,
most important component is thin piezoelectric crystals
 At tissue interface, some waves are reflected and some
are absorbed
Clinical application
 TMJ disorder
 Myofacial pain dysfunction syndrome
 To assess the correct location of joint spaces
 As an alternative to MRI contraindicated patients

30. Conclusion
 There are many lesser known techniques in
maxillofacial imaging which can be used as a powerful
tool for demonstrating a large variety of craniofacial
structures.
 Although new paradigms for x- ray imaging techniques
have emerged, they may not be economic and readily
feasible to be used in many health centers.
 In such cases, some of these techniques can still be
used as a standard procedure for demonstrating various
craniofacial structures.

31. References
1. White and Pharaoh’s oral radiology, Sanjay. M. Mallya, Ernest W.
N Lam
2. Text book of oral Medicine and Oral Diagnosis and Oral
Radiology – Ravikiran Ongole, Praveen B. N
3. Textbook of Oral Medicine and Oral Radiology by Peeyush
Shivhare.