Radiographic cephalometry /certified fixed orthodontic courses by Indian dental academy


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Radiographic cephalometry /certified fixed orthodontic courses by Indian dental academy

  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  5. 5. The assessment of craniofacial structures forms a part of orthodontics diagnosis. Cephalometric analysis of skeletal ,dental & soft tissues are merely aids in determining the diagnosis. For an accurate interpretation,the various readings must not be assessed independently. To interpret the data, all readings must be co-related with other clinical & diagnostic criteria before arriving at the diagnosis & treatment planning.
  6. 6. HISTORY
  7. 7. The earliest method used to asses facial proportions was by artistic standards with harmony, symmetry and beauty as key points. Craniometry said to be forerunner of cephlometry. Craniometry involved measurement of craniofacial dimensions of skulls of dead persons. The discovery of X- rays in 1895 by Roentgen revolutionized dentistry.The value of radiography as a diagnostic aid in orthodontics was proclaimed by W. A. Price in 1900
  8. 8. In 1922 Paccini standardized the radiographic head images by positioning subject against film cassette at a distance of 2 m from X-ray tube. In 1931 Broadbent in USA and Hofrath in Germany simultaneously presented a standardized cephalometric technique using high powered X ray machine and a head holder called cephalostat.
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  11. 11. Cephalograms can of two types a) Lateral cephalogramsThis provides lateral view of skull. Also referred to as lateral “cephs”, have become virtually indispensable to the orthodontists in treatment of patients. They are important in orthodontic growth analysis, diagnosis, treatment planning, monitoring of therapy and evaluation of final treatment out come.
  12. 12. b) Postroanterior cephalograms (PA) They provide additional radiographic information mediolaterally which is particularly useful for presurgical and asymmetric growth pattern. The basic equipment required to obtain both lateral and PA cephlometric view consists of an X-Ray source ,an adujustable cephlostat, a film cassete with radigraphic itensifying screens, and film cassette holder.
  13. 13. Uses of cephalograms – Cephlometric has established itself as one of pillars of comprehensive orthodontic diagnosis. It is also valuable tool in treatment planning and follow of patient undergoing orthodontic treatment. a) Ceplometrics helps in orthodontic diagnosis by enabling the study of skeletal, dental and soft structures of the cranio-facial region. b) It helps in classification of the skeletal dental abnormalities and also helps in establishing facial type.
  14. 14. c) Cephlometrics helps in planning treatment for an individual. d) It helps in evaluation of the treatment results by quantifying the changes brought by treatment. e) Cephlometrics helps predicting the growth related changes and changes brought by treatment. f) Cephlometrics is a valuable aid research work involving the cranio-dento-facial region.
  16. 16. Equipment: The cephalometric radiographs are taken using an apparatus that consists of an x-ray source and a head holding device called cephalostat. The cephalostat consists of two ear rods that prevent the movement of the head in the horizontal plane. Vertical stabilization of the head is brought about by an orbital pointer that contacts the lower border of the left orbit.
  17. 17. The upper part of the face is supported by the forehead clamp positioned above the region of the nasal bridge. The distance between X–ray source and the mid-sagittal plane of the patient is fixed at 5 feet (152.4 cm). Thus the equipment helps in standardizing the radiographs by use of constant head position and source film distance so that serial radiographs can be compared.
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  20. 20. CEPHLOMETRIC LANDMARKS Cephalometric makes use of certain landmarks or points on the skull which are used for quantitative analysis and measurements. Cephalometric landmarks can of two types : ANATOMIC LANDMARKS These landmarks represent actual anatomic structures of the skull
  21. 21. DERIVED LANDMARKS These are landmarks that have been obtained secondarily from anatomic structures in a cephalogram. REQUIREMENTS FOR LANDMARKS: a) It should be easily seen in a radiograph. b) It should be uniform in outline and should be reproducible. c) The landmarks should permit valid quntitative measurements of lines and angles projected from them.
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  23. 23. Cephalometric landmarks: Nasion: The most anterior point midway between the frontal and nasal bones on the fronto-nasal suture. Orbitale : The lowest point on the inferior bony margin of the orbit. Porion: The highest bony point on the upper margin of external auditory meatus.
  24. 24. Sella : The point representing the midpoint of the pituitary fossa or sella turcica. It is a constructed point in the mid-sagittal plane. Point A: It is the deepest point in the midline between the anterior nasal spine and alveolar crest between the two central incisors. It is also called subspinale.
  25. 25. Point B: It is the deepest point in the midline between the alveolar crest of mandible and the mental process. It is also called supramentale. Basion: It is the median point of the anterior margin of the foramen magnum. Bolton point : The highest point at the post condylar notch of the occipital bone.
  26. 26. Anterior nasal spine: It is the anterior tip of the sharp bony process of the maxilla in the midline of the lower margin of anterior nasal opening. Gonion: It is a constructed point at the junction of ramal plane and the mandibular plane. Pogonion: It is the most anterior point of the bony chin in the median plane.
  27. 27. Menton: It is the most inferior midline point on the mandibular symphysis. Gnathion : It is the most antero-inferior point on the symphysis of the chin. It is constructed by intersecting a line drawn perpendicular to the line connecting menton and pogonion.
  28. 28. Articulare : It is a point at the junction of the posterior border of ramus and the inferior border of the basilar part of the occipital bone. Condylion: The most superior point on the head of the condyle. Prosthion : The lowest and most anterior point on the alveolar bone in the midline, between the upper central incisors. It is also called supradentale.
  29. 29. Infradentale: The highest and most anterior point on the alveolar process, in the median plane between the mandibular central incisors. The key ridge : The lower most point on the contour of the anterior wall of the infratemporal fossa. Posterior nasal spine: The inter-section of a continuation of the anterior wall of the pterygo-palatine fossa and the floor of the nose, marking the distal limit of the maxilla.
  30. 30. Broadbent registration point : It is the midpoint of the perpendicular from the center of sella tursica to the Bolton plane. Ptm point : It is the intersection of the inferior border of the foraman rotundum with the posterior wall of the pterygo-maxillary fissure.
  31. 31. Tracing technique: The following items are recommended for tracing a head film: 1) A lateral cephalogram, the usual dimensions of which are 8 x 10 inches (patients with facial asymmetry often require a frontal anteroposterior headfilm). 2) Acetate matte tracing paper (0.003 inches thick, 8 x 10 inches). 3) A sharp 3H drawing pencil or a very fine felt-tipped pen. 4) Masking tape
  32. 32. 5) A few sheets of cardboard (preferably black), measuring approximately 6 x 12 inches, and a hollow cardboard tube. 6) A protractor and tooth symbol tracing template for drawing the teeth (optional). Most templates have round holes for tracing the outline of the ear rods. 7) Dental casts trimmed to maximal intercuspidation of the teeth in occlusion
  33. 33. 8) 9) View box (variable rheostat desirable, but no essential). Pencil sharpener and an eraser.
  34. 34. General considerations for tracing: Start by placing the cephalogram on the view box with the patient’s image facing to the right. Tape the four corners of the radiograph to the view box. With a fine felt-tipped black pen, draw three crosses on the radiograph, two within the cranium and one over the area of the cervical vertebrae.
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  36. 36. These registration crosses allow for reorienting the acetate tracing on the film for later verification or in the event the film becomes displaced during the tracing procedure, a not infrequent occurrence. Next, place the matte acetate film over the radiograph and tape it securely to the radiograph and the view box. After firmly affixing the acetate film, trace the three registration crosses.
  37. 37. . Use smooth continuous pressure on the pencil; whenever possible, trace image lines without stopping and/or lifting the pencil from the acetate film. Avoid erasures. Consult dental casts when outlining molar and incisor teeth, taking care to depict left and right teeth.
  38. 38. Down’s analysis Down elected to use FH (Frankfurt Horizontal plane) as a reference base to determine the degree of retrognathism, orthognathism or prognathism of lower jaw.
  39. 39. Parameter: Skeletal Facial angle (87.80) Angle of convexity (00) A-B plane angle (-4.80) Mandibular plane angle (21.90) Y-axis (59.40)
  40. 40. Dental Cant of occlusal plane (9.30) Interincisal angle (135.40) Incisor occlusal plane angle (14.50) Incisor mandibular plane angle (1.40) Protrusion of maxillary incisors (2.70)
  41. 41. Facial angle : (FH plane) to (N-Pog) · It is used to measure the degree of retrusion or protrusion of the lower jaw · It can be defined as the inferior inside angle in which the facial line (N-Pog) intersects the FH plane. · Mean value is 87.80 (SD = 3.6) · Increased angle = protrusive chin; Decreased angle = retrusive chin
  42. 42. Facial angle
  43. 43. Angle of convexity: · It is used to measure the degree of maxillary basal arch at its anterior limit (Point A) in relative to the total facial profile (N-Pog). · It is formed by the intersection of the line (N-Point A) to (Point A-Pog) · Mean value is 00 (SD = 5.10) · If the line (Point A-Pog) is located anterior to (N-point A), the angle is +ve. Suggesting protrusive maxilla in relation to mandible. Negative angle suggests retrusive maxilla.
  45. 45. A-B plane: · This is used to measure the relation of anterior limit of apical bases to each other relation to facial line. · Angle formed by intersection of line (Point A - Point B) to (N-Pog). · Mean value is –4.60 (SD = 3.60) Since point B is located behind point A, the angle is usually –ve. Only in class III it is +ve.
  46. 46. A-B plane
  47. 47. Mandibular plane angle: Relationship of the mandible to cranial base. Angle formed by intersection of line (M-Go) to FH plane. Mean value is 21.90 (SD = 3.2) High mandibular plane angles occur in both protrusive and retrusive faces which complicate treatment and prognosis. High and low mandibular plane angles suggest unfavourable growth patterns.
  48. 48. Mandibular plane angle
  49. 49. · · Y-axis: Y-axis indicate the degree of forward, backward and downward position of the chin in relation to upper face. Acute angle formed by the intersection of line (S-Gn) to FH plane. · Mean value is 59.40 (3.80) · An increase in Y-axis- Vertical growth, decrease in Y-axis Horizontal growth.
  50. 50. Dental parameters: Cant of occlusal plane: · It is the measure of the slope of occlusal plane to the FH plane. · Defined occlusal plane as that line bisecting the overlapping cusps of the first molars and the incisal overbite. When the occlusal plane is intersected to the FH plane, angle is formed. · Mean value is 9.30 (SD = 3.80)
  51. 51. Cant of occlusal plane
  52. 52. Interincisal angle: · Used to measure the relation of maxillary and mandibular central incisors to denture base. · The angle is formed by passing a line through the incisal edge and apex of the root of the maxillary and mandibular central incisor. · Mean value is 135.40 (SD = 5.80) · Angle is small if incisors are tipped forward.
  53. 53. Interincisal angle
  54. 54. Incisor occlusal plane angle: · It relates the lower incisors to their functioning surface at the occlusal plane. · Mean value is 14.50 (SD = 3.50) Angle increase as teeth forward.
  55. 55. Incisor occlusal plane angle
  56. 56. Incisor mandibular plane angle: · Angle is formed by intersection of mandibular plane with a • line passing through incisal edge and the apex of the root of the lower incisor. · Mean value is 1.40 (SD = 3.80) · Angle increase as teeth forward.
  57. 57. Incisor mandibular plane angle
  58. 58. Protrusion of maxillary incisors: · It is measured as the distance between the incisal edge of the maxillary central incisor to the line (Point A-Pog) · Mean value is 2.7 mm (SD = 1.8 mm) · Distance is +ve if incisal edge of maxillary central incisor is ahead of the line (Point A-Pog). This indicates protrusion of maxillary central incisor. Negative indicates retrusion of maxillary central incisor.
  59. 59. Upper incisor to A- pog line
  60. 60. STEINER ANALYSIS Steiner selected most meaningful parameters and evolved a composite analysis. The skeletal analysis entails relating the upper and lower jaw to the skull and to each other. The dental analysis relates the upper and lower incisor teeth to their respective jaws and to each other. Soft – tissue analysis provides a means of assessing the balance and harmony of the lower facial profile
  61. 61. Parameters: Skeletal SNA angle (maxilla) SNB angle (Mandibular) ANB angle (Maxillary-mandibular) Occlusal plane Mandibular plane
  62. 62. Dental Soft tissue Maxillary incisor position Mandibular incisor position Inter-incisal angle Lower incisor to chin S-line
  63. 63. Skeletal analysis: Since landmarks such as porion and orbitale are not always easily identified, Steiner elected to use the anterior cranial base (Sella-Nasion) as reference line to which jaws are related. The advantage of using these two midline points (Sella and Nasion) is that they are moved only a minimal amount whenever head deviates from true profile position and even if the head is rotated in the cephalostat.
  64. 64. Skeletal analysis: Maxilla (SNA angle): · It is used to measure the degree of protrusion or retrusion of maxilla to the cranial base. · SNA angle is formed by intersection of (S-N) line with (N-point A) line. · Mean SNA angle is 820. · Increase in angle  Forward positioning of maxilla · Decrease in  Backward positioning of
  65. 65. SNA angle
  66. 66. Mandible (SNB angle): · It is used to measure the degree of protrusion or retrusion of mandible to the cranial base. · SNB angle is formed by intersection of (S-N) line with (Npoint B) line. · Mean value is 800 · Increase in angle  Forward positioning of mandible Decrease in angle  Backward positioning of mandible
  67. 67. SNB angle
  68. 68. Maxilla to mandible (ANB angle) ANB angle provides information on the relative position of maxillary and mandible to each other. Angle formed by joining AN and NB (SNA-SNB) Mean value is 20. Increase in SNA (More than 20) suggests protrusive maxilla Decrease in SNA (less than 20) suggests retrusive maxilla and protrusive mandible
  69. 69. ANB angle
  70. 70. Occlusal plane: · It shows significance of the teeth in occlusion to the cranial base and face. · Occlusal plane is drawn through the region of the overlapping cusps of the first premolars and the molars. Angle formed by S-N plane to occlusal plane. ·   Mean reading for normal occlusion is 140.
  71. 71. Occlusal plane:
  72. 72. Mandibular plane (Go-Gn)     It shows the growth pattern. · It is drawn between gonion (Go) and gnathion (Gn) · Mean reading is 320. Excessive low or high mandibular plane angle suggests unfavourable growth pattern
  73. 73. Mandibular plane angle
  74. 74. Dental analysis: Maxillary incisor position: To know the relative location and axial inclination of the upper incisors by relating the teeth to N-A line. · Axial inclination: The upper incisor to N-A reading indicates the axial inclination of the upper incisor in degrees (Mean 220) · Location: Distance between most anteriorly placed point on the maxillary central incisor to the N-A line in millimeters (Mean 4 mm).
  75. 75. Upper incisor to N-A (angle)
  76. 76. Upper incisor to N-A (linear)
  77. 77. Mandibular incisor position: To know the relative anteroposterior location and axial inclination of the lower incisors by relating the lower incisors to N-B line. · Axial inclination: Angle formed between the long axis of the lower incisor and the N-B line indicates axial inclination of lower incisor (Mean = 250) · Location: Distance between most anteriorly placed point on mandibular incisor to N-B line (Mean = 4 mm).
  78. 78. Mandibular incisor position:
  79. 79. Inter-incisal angle: · To know the relative position of the upper incisor to that of lower incisor. · Angle formed by passing through long axis of upper central incisor and lower central incisor. · Mean value is 1300
  80. 80. Inter-incisal angle:
  81. 81. Soft-tissue analysis (S-line): · According to Steiner, Lips in well balanced faces should touch a line extending from soft-tissue contour of the chin to the middle of an S formed by lower border of the nose. This line is referred to as S-line. · Lips located beyond S-line tend to be procumbency and need orthodontic treatment. Lips located behind S-line, patient profile is generally “concave” and needs treatment.
  82. 82. STEINER`S S-LINE
  83. 83. Wits appraisal The Wits appraisal is a linear measurement and not an analysis. The purpose of Wits appraisal is to determine the severity of jaw disharmony that is not reflected in the conventional ANB angle (Steiners analysis).
  84. 84. ANB as a measure of jaw dysplasia: ANB angle in normal occlusions is 20. Angle greater indicates class II disharmony. Negative angle indicates class III disharmony. This is an acceptable generalization, there are many instances in which this (ANB angle) does not apply.
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  86. 86. Therefore variations from the accepted (ANB=20) assume importance when attempting to appraise craniofacial skeletal disharmony. degree of
  87. 87. Method of Wits appraisal : The purpose of Wits appraisal is to determine the severity of jaw disharmony that is not reflected in the conventional ANB angle. · It is a measure of the extent to which the jaws are related to each other anteroposteriorly. · Here, first the occlusal plane is drawn through the region of overlapping cusps of first premolars and first molars (Steiner analysis). · Then, perpendicular lines are drawn from point A and point B to the occlusal planes.
  89. 89. The points of contact on the occlusal plane from A and B are labeled as Ao and Bo respectively. Normal occlusion: Point Bo is 1 mm anterior to Ao · Class II: Point Ao is located anterior to Bo. · Class III: Point Bo is located anterior to Ao. Normal-For men - -1mm For women – 0mm (range,-2 to 4mm).
  91. 91. Therefore wits appraisal is intended not as single diagnostic criteria but as an additional measurement to SNA angle (Steiner’s) which aids in assessing the degree of anteroposterior jaw disharmony.
  92. 92. Tweed analysis: The Tweed analysis makes use of three plane that form a diagnostic triangle. The planes used are; · Frankfort horizontal plane · Mandibular plane Long axis of lower incisor The objectives of the analysis include; · Determination of the position of the lower incisor Evaluation of prognosis
  94. 94. The angles formed by these three planes are; Frankfort mandibular plane angle (FMPA): It is the angle formed by the intersection of the Frankfort horizontal plane with the mandibular plane. The mean value is 250 Incisor mandibular plane angle (IMPA): It is angle formed by the intersection of the long axis of the lower incisor with the mandibular plane. It indicates the relative inclination of the lower incisor. The mean value is 900.
  95. 95. Frankfort mandibular incisor angle (FMIA): It is the angle formed by the intersection of the lower incisor with the FH plane. The mean value is 650.
  96. 96. THANK YOU Leader in continuing dental education