OPG and Extraoral radiography

Thorough knowledge of the indications of various extra oral techniques allows accurate and timely diagnosis of various maxillofacial pathologies. Further, we can arrive at a diagnosis with minimum number of x-rays there by reducing patient exposure to radiation.

1. Radiographs (Part 2) Presented by Dr . Neha Sharma PG II YR

2. CONTENTS 3 PANORAMIC IMAGING EXTRAORAL RADIOGRAPHS CEPHALOMETRIC LANDMARKS LATERAL SKULL PROJECTION SUBMENTOVERTEX PROJECTION PA WATERS PROJECTION REVERSE TOWNES PROJECTION TMJ IMAGING CONCLUSION

3. HISTORY OF - EXTRAORAL RADIOGRAPHIC TECHNIQUES

4. Extra-oral Source Discovered by Dr. Hisatugu Numata of Japan, 1933

5. Father of Panoramic Radiography 1949, extra-oral films X-ray source - stationary Dr Yrjo Veli Paatero

6. What is panoramic imaging / pantomography ??? A technique for producing a single tomographic image of the facial structures that includes both the maxillary and mandibular dental arches and their supporting structures .

7. ‘Panorama’ ‘Tomography’ An unobstructed view of a region in every direction An X-ray technique for making radiographs of layers of tissue in depth without the interference of tissues above and below the level PANTOMOGRAPHY

8. Equipment Panoramic X-ray unit

9. 2. Screen film

10. 3. Intensifying screens

11. 4. Cassette

12. BONY LANDMARKS IN MANDIBLE 14 1 1. Condylar head 2. Sigmoid notch 3 . Coronoid process 4. External oblique ridge 5. Mandibular canal 2 3 4 5 6. Post. Border of Ramus 8. Lower border 7. Gonial Angle 6 7 9. Mental ridge 11. Mental foramen 10. Genial tubercle 13. Lingula 12. External Oblique Ridge 14. Hyoid bone 8 9 10 11 12 13 14

13. BONY LANDMARKS IN MAXILLA 15 15 15. Glenoid fossa 19. Floor of Max.Sinus 17. Zygomatic Arch 16. Articular eminence 18.Post. wall max. sinus 20. Zygomatic process of max. forming innominate line 21. Hard palate 22. Floor of the orbit 23. Nasal septum 24. Incisive foramen 25. Inferior choncha 26. Meatus 27. Frontal process of Z.bone 16 17 18 19 20 21 22 23 29 25 24 26 28.Pterygo max. fissure 30. Maxillary tuberosity 29.Spine of the sphenoid bone 31. Lateral pterygoid plate 31 30 28 27

14. OTHER STRUCTURES 16 32 32. External acoustic meatus 34. Shadow of ear lobe 33. Styloid process 35. nose 36. Shadow of Cervical spine 33 34 35 36 37 37. Cervical vertebrae 38 38. Nasopharyngeal space 39. Shadow of uvula 40 39 40 Submandibular fossa

15. A panoramic film is not as useful as periapical radiography for detecting small carious lesions, periodontal diseases, or periapical lesions . It should not be used as a substitute for intraoral films.

16. Impacted teeth and its relation with the mandibular canal.

17. To evaluate eruption patterns

18. To detect diseases, lesions, conditions of the jaws a nd the extent of large lesions.

19. to evaluate trauma

20. Retained teeth or root tips in edentulous patients

21. Post-operative examination and patient education.

22. Implants

23. ROTATION CENTER The pivotal point or axis, around which the cassette carrier and X-ray tubehead rotate, is termed a ROTATION CENTER.

24. D ouble center of rotation

25. Three stationary centers of rotation

26. Continously moving center of rotation

27. During the exposure cycle, the machine shifts to one or more additional rotation centers. This rotational change allows the image layer to conform to the shape of the dental arches. The location and no. of rotational centers influence the size and shape of the focal trough.

28. Focal trough The focal trough (also known as the Image layer ) is defined as a 3-D curved zone in which structures are clearly demonstrated on a panoramic radiograph.

29. Advantages Field size Minimal exposure Simplicity Patient cooperation 5. Useful in patients with trismus & gagging 6. Valuable visual aid for patient education

30. Disadvantages Cannot be used in detection of caries and periodontal disease. Overlapping of teeth in premolar region Focal trough limitations Shadow of cervical spine in the lower anterior region. 5. Ghost images 6. Equipment cost

31. 34 C OMMON ERRORS

32. PATIENT POSITIONING ERRORS

33. Positioning of lips and tongue

34. Positioning of Frankfort plane upward

35. Positioning of Frankfort plane downward

36. Positioning of teeth anterior to focal trough

37. Positioning of teeth posterior to focal trough

38. Positioning of midsagittal plane

39. Patient movement

40. Positioning of spine

41. Processing Errors Underexposed, light, washed out image Very dark film, Overexposed Film Fog Improper filter in daylight loader

42. Panoramic Image = Right lateral image+ PA image+ Left Lateral image

43. Extraoral radiographic techniques 29/07/14 46

44. Lateral cephalometric projection Film position - cassette is placed perpendicular to the floor with long axis of the cassette placed vertically. Position of patient - left side of the face is positioned against the cassette. Mid sagittal plane is perpendicular to the floor and parallel to film . Central ray - perpendicular to the film.

45. Exposure parameters KVp = 84 mAs = 13 Seconds =1.6

46. indications To evaluate facial growth and development, trauma, disease and developmental anomalies . D emonstrates the bones of the face, skull as well as the soft tissue profile of the fac e .

47. Film position - cassette is perpendicular to the floor with long axis of the cassette placed vertically. Position of patient –The film is adjusted so that the upper circumference of the skull is .5 inch below the lower border of the cassette. Central ray - perpendicular to the film towards the E.A.M. True lateral skull

48. Lateral skull projection 51 Exposure parameters KVp = 65 mAs = 10 Seconds =.5-2 sec

49. To survey skull and facial bone for trauma or pathology. Nasopharangeal soft tissue , paranasal sinus and hard palate. Condition affecting sella turcica , such as tumour of pitutary gland in acromegaly. Indications

50. 29/07/14 53 PA WATERS PROJECTION Film position - cassette is perpendicular to the floor with long axis of the cassette placed vertically. Position of patient - mid sagittal plane perpendicular to the floor and parallel to film . Head is extended so that only the chin touches the casette . The tip of nose is .5 to 1.5 cm away from the cassette Central ray - perpendicular and to the midpoint of the film.

51. 54 Exposure parameters KVp = 65 mAs = 10 Seconds =2 -3 sec

52. INDICATIONS 55 Demonstrate the maxillary , frontal and ethmoidal sinuses. The orbit, frontozygomatic suture, nasal cavity, coronoid process of the mandible and the zygomatic arch are also seen.

53. 56 Film position - cassette is placed perpendicular to the floor with long axis of the cassette placed horizontally. Position of patient - head is centered on the cassette (Head and neck tipped back).Vertex of the skull touches the cassette. Central raY - perpendicular to the film. I t enters via between angle of mandible and in a coronal plane ¾ inches anterior to the external auditory meatus . Submentovertex (base) projection

54. Submentovertex (base) projection 57 Exposure parameters KVp = 50 mAs = 20 Seconds = .4

55. indications 58 Help to study destructive lesion affecting the palate, pterygoid region or base of the skull, sphenoidal sinus. Fractures of zygomatic arches (JUG HANDLE).

56. Lateral oblique Film position - flat against the patient cheeks and is centered over the body of the mandible. Position of patient - ala tragus line is parallel to the floor. Inferior border of the cassette should be parallel to the lower border of the mandible and below it. Central ray - directed 2cm behind the angle of the mandible and beam is directed -10° to -15°

57. Exposure parameters KVp = 65-70 mAs = 10 Seconds =.8

58. Lateral Oblique Views - Largely replaced by panoramic views Indications:   Impacted third molars  fractures of the ramus, condyle or body of the mandible. 61

59. 62

60. Transcranial VIEW 63 Film position - cassette is placed flat against the patient ear and centred over the TMJ of interest. Position of patient - head is adjusted so that the saggital plane is vertical. The ala tragus is parallel to floor. Central ray - is ½ inch behind and 2 inch above the auditory meatus

61. 64 Exposure parameters KVp = 70 mAs = .7 Seconds =1.5 Indications A rthritic changes on the articular surface. To evaluate the joint’s bony relationship.

62. Transpharyngeal view 65 Film position - cassette is placed flat against the patient ear and is centered to a point ½’” anterior to ext. auditory meatus, over the TMJ of interest . Position of patient - head is adjusted so that the saggital plane is vertical.The ala tragus is parallel to floor. Central ray - from the opposite side cranially at an angle -5° to -10°.

63. INDICATIONS 66 Fracture of condylar head and neck of the mandible Exposure parameters KVp = 70 mAs = 7 Seconds =1.5

64. TransORBITAL /ZIMMER view 67 Film position - cassette is placed behind the patient’s head at an angle of 45° to the saggital plane. Position of patient - head is adjusted so that the saggital plane is vertical. The canthomeatal line is parallel to floor. The mouth should be wide open. Central ray - from the opposite side cranially at an angle -5° to -10°.

65. INDICATIONS 68 The anterior view of the temporomandibular joint Medial displacement of fractured condyle Fracture of neck of condyle. There is minimum superimposition. Exposure parameters KVp = 70 mAs = 7 Seconds =.8

66. REVERSE-TOWNE PROJECTION(OPEN MOUTH) 69 Film position - cassette is placed perpendicular to the floor with long axis of the cassette placed horizontally. Position of patient- Pt. forehead and tip of the nose should touch the film and is asked to keep his mouth wide open Central ray - directed via mid saggital plane at the level of the mandible and is perpendicular to the film.

67. 70 Exposure parameters KVp = 65 mAs = 10 Seconds = 2-3 INDICATIONS: Suspected fracture of the condylar neck. Intracapsular fracture of the TMJ Shows posterolateral wall of maxillary sin us

68. Drawbacks of extra oral techniques 71 Magnification occurs due to the greater object to film distance used. Details are not well defined. Contrast is reduced as the secondary radiation produced by the soft tissues is more. It is a 2- D image of 3- D structure.

69. CONCLUSION Thorough knowledge of the indications of various extra oral techniques allows accurate and timely diagnosis of various maxillofacial pathologies. Further, we can arrive at a diagnosis with minimum number of x-rays there by reducing patient exposure to radiation.

70. White SC, Pharoah MJ.Oral Radiology Principles And Interpretations.6 th elsevier:: Missouri; 2009 Mac Donald,Avery.Dentistry For The Child And Adolscent.9 th .elsevier: Missouri; 2011 Langland and Langlais .. Principles Of Dental Imaging.7 th ed.elsevier : Muir; 2005 Freny R,Karjodkar.Textbook Of Dental And Maxillofacial Radiology.6 th ed.elsevier: Reed; 2000 Dental radiography, Principles and Techniques; Haring, Howerton;Third edition.

71. DR ANKIT GOEL, SUBHARTI.