Extra oral radiograph

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Extra oral radiograph

  1. 1. Extra oral Radiology Islam Kassem ikassem@dr.com
  2. 2. ikassem@dr.com
  3. 3. Skull Radiography• Lateral cephalometric projection• Posteroanterior projection• Water’s projection• Submentovertex projection• Reverse Towne’s projection
  4. 4. Main indications• Fractures of the maxillofacial skeleton• Fractures of the skull• Investigation of the antra• Diseases affecting the skull base and vault• TMJ disorders. ikassem@dr.com
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  7. 7. Main maxillofacial/skull projectionsStandard occipitomental (0° OM)• 30° occipitomental (30° OM)• Postero-anterior of the skull (PA skull) sometimesreferred to as occipitofrontal (OF)• Postero-anterior of the jaws (PA jaws)• Reverse Townes• Rotated postero-anterior (rotated PA)• True lateral skull• Submento-vertex (SMV)• Transcranial• Transpharyngeal. ikassem@dr.com
  8. 8. Standard occipitomental (0° OM)• This projection shows the facial skeleton and• maxillary antra., and avoids superimposition of the• dense bones of the base of the skull. ikassem@dr.com
  9. 9. The main clinical indications include:Investigation of the maxillary antraDetecting the following middle third facialfractures:— LeFortI— Le Fort II— Le Fort III— Zygomatic complex— Naso-ethmoidal complex— Orbital blow-outCoronoid process fractures• Investigation of the frontal and ethmoidalsinuses• Investigation of the sphenoidal sinus(projection needs to be taken with the patientsmouth open). ikassem@dr.com
  10. 10. Technique and positioning1. The patient is positioned facing the film withthe head tipped back so the radiographic baselineis at 45° to the film, the so-called nose-chin position.This positioning drops the dense bones of the baseof the skull downwards and raises the facial bonesso they can be seen.2. The X-ray tube head is positioned with thecentral ray horizontal (0°) centered through theocciput ikassem@dr.com
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  13. 13. 30° occipitomental (30° OM)• This projection also shows the facial skeleton, but• from a different angle from the 0° OM, enabling• certain bony displacements to be detected. ikassem@dr.com
  14. 14. Main indications• Detecting the following middle third facialfractures:— LeFortI— Le Fort II— Le Fort III• Coronoid process fractures. ikassem@dr.com
  15. 15. Technique and positioning1. The patient is in exactly the same position asfor the 0° OM, i.e. the head tipped back,radiographic baseline at 45° to the film, in the nose-chin position.2. The X-ray tube head is aimed downwardsfrom above the head, with the central ray at 30° tothe horizontal, centered through the lower borderof the orbit ikassem@dr.com
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  18. 18. Postero-anterior of the skull (PA skull)This projection shows theskull vault, primarilythe frontal bones and thejaws. ikassem@dr.com
  19. 19. Main indications• Fractures of the skull vault• Investigation of the frontal sinuses• Conditions affecting the cranium, particularly:— Pagets disease— multiple myeloma— hyperparathyroidism• Intracranial calcification. ikassem@dr.com
  20. 20. Technique and positioning1. The patient is positioned facing the film with thehead tipped forwards so that the forehead and tipof the nose touch the film — the so-called forehead-nose position. The radiographic baseline ishorizontal and at right angles to the film. Thispositioning levels off the base of the skull andallows the vault of the skull to be seen withoutsuperimposition.2. The X-ray tube head is positioned with thecentral ray horizontal (0°) centered through theocciput . ikassem@dr.com
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  24. 24. Postero-anterior of the jaws (PA jaws/PA mandible)• This projection shows the posterior parts of the• mandible. It is not suitable for showing the facial• skeleton because of superimposition of the base of• the skull and the nasal bones. ikassem@dr.com
  25. 25. Main indications• Fractures of the mandible involving thefollowing sites:— Posterior third of the body— Angles— Rami— Low condylar necks• Lesions such as cysts or tumors in theposterior third of the body or rami to note anymedio-lateral expansion• Mandibular hypoplasia or hyperplasia• Maxillofacial deformities. ikassem@dr.com
  26. 26. Technique and positioning1. The patient is in exactly the same position asfor the PA skull, i.e. the head tipped forward, theradiographic baseline horizontal and perpendicularto the film in the forehead-nose position.2. The X-ray tube head is again horizontal (0°),but now the central ray is centered through thecervical spine at the level of the rami of themandible. ikassem@dr.com
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  29. 29. Reverse TownesThis projection shows thecondylar heads and necks.The original Townes view(an AP projection) wasdesigned to show theoccipital region, but alsoshowed the condyles.However, since all skullviews used in dentistry aretaken conventionallyin the PA direction, thereverse Townes (a PAprojection) is used. ikassem@dr.com
  30. 30. Main indications• High fractures of the condylar necks• Intra capsular fractures of the TMJ• Investigation of the quality of the articularsurfaces of the condylar heads in TMJ disorders• Condylar hypoplasia or hyperplasia. ikassem@dr.com
  31. 31. Technique and positioning1. The patient is in the PA position, i.e. thehead tipped forwards in the forehead-nose position,but in addition the mouth is open. The radiographicbaseline is horizontal and at right anglesto the film. Opening the mouth takes the condylarheads out of the glenoid fossae so they can beseen.2. The X-ray tube head is aimed upwards frombelow the occiput, with the central ray at 30° tothe horizontal, centered through the condyles. ikassem@dr.com
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  34. 34. True lateral skullThis projection shows the skullvault and facial skeleton fromthe lateral aspect. The maindifference between the truelateral skull and the truecephalometric lateral skulltaken on the cephalostat isthat the true lateral skull is notstandardizedor reproducible. This view isused when a single lateral viewof the skull is required but notin orthodontics or growthstudies. ikassem@dr.com
  35. 35. Main indications• Fractures of the cranium and the cranial base• Middle third facial fractures, to show possible downwardand backward displacement of the maxillae• Investigation of the frontal, sphenoidal and maxillary sinuses• Conditions affecting the skull vault,particularly:— Pagets disease— multiple myeloma— hyperparathyroidism• Conditions affecting the sella turcica, such as:— tumor of the pituitary gland in acromegaly. ikassem@dr.com
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  37. 37. Technique and positioning1. The patient is positioned with the headturned through 90°, so the side of the face touchesthe film. In this position, the sagittal plane of thehead is parallel to the film.2. The X-ray tube head is positioned with thecentral ray horizontal (0°) and perpendicular tothe sagittal plane and the film, centered throughthe external auditory meatus . ikassem@dr.com
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  40. 40. Submento-vertex (SMV)• This projection shows the base of the skull, sphenoidal• sinuses and facial skeleton from below. ikassem@dr.com
  41. 41. Main indications• Destructive/expansive lesions affecting thepalate, pterygoid region or base of skull• Investigation of the sphenoidal sinus• Assessment of the thickness (medio-lateral) ofthe posterior part of the mandible beforeosteotomy• Fracture of the Zygomatic arches — to showthese thin bones the SMV is taken withreduced exposure factors. ikassem@dr.com
  42. 42. Technique and positioning1. The patient is positioned facing away from the film. The head istipped backwards as far as is possible, so the vertex of the skulltouches the film. In this position, the radiographic baseline, isvertical and parallel to the film.2. The X-ray tube head is aimed upwards from below the chin, with thecentral ray at 5° to the horizontal, centered on an imaginary linejoiningthe lower first molars .Note: The head positioning required for this projectionmeans it is contraindicated in patientswith suspected neck injuries, especially suspectedfracture of the odontoid peg. ikassem@dr.com
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  46. 46. Water’s view ikassem@dr.com
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  48. 48. Temporomandibular Joint RadiographyRadiographs of the temporomandibular joint(TMJ) can be very difficult to examine becauseof the multiple adjacent bony structures.The articular disc and other soft tissues of theTMJ cannot be examined by radiographs.Special imaging techniques (e.g., arthrography,magnetic resonance imaging) must be used.Radiographic projections of the TMJ can be usedto show the bone and the relationship of thejaw joint.
  49. 49. Thank you• You can get the lecture on• http://www.slideshare.net/islamkassem ikassem@dr.com

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