1. Orthodontic Cephalometrics
Dr.Gyan P. Singh(Associate prof.)
8th Dec.2014

2. Cephalometrics-Dr.Gyan P.Singh
William Down’s (1948)
5 skeletal & 5 denture patterns.
SKELETAL
1. Facial angle (87.5 degrees)
2. Angle of convexity (0 )
3. A-B Plane angle (-4.6)
4. Mandibular plane angle (21.9)
5. Y-Axis (59.4)
DENTAL
1.Cant of occlusal plane (9.3)
2.Interincisal angle (135.4)
3.Mandibular incisor to occlusal plane angle (14.5)
4.Incisor- mandibular plane angle (91.4)
5. Protrusion of maxillary incisor (2.7 mm) .
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3. Cephalometrics-Dr.Gyan P.Singh
1.Facial angle- Posterior-inferior angle at the intersection of facial plane with Frankfort horizontal plane , indicates the degree of recession or protrusion of the mandible in relation to upper face.
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2. Angle of convexity This angle measures the degree of the maxillary basal arch protrusion at its anterior limit relative to the facial profile.
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3.A-B plane angle A-B plane is a measure of the relation of the anterior limit of the apical bases to each other relative to the facial plane.
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4. Mandibular plane angle Mandibular plane is tangent to the gonial angle and the lowest point of the symphysis (Me).
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5. Y-Axis It is also called as growth –axis angle measured as posterior inferior angle on S-N plane and Sella to Gnathion line.
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Denture pattern
1.Cant of occlusal plane It is suggestive of anteropostrior tilt of occlusal plane in relation to the cranial base.
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2.Interincisal angle It is indicative of protrusiveness of upper and lower incisors.
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3.Mandibular incisor to occlusal plane The angle measured is the complement of the angle formed by the intersection of the long axis of lower incisor with the occlusal plane.
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4.Incisor-Mandibular plane angle It indicates inclination of the lower incisor on the mandibular plane.
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5.Protrusion of maxillary incisors The measurement is made from upper incisal edge to A-Pg line.
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Cecil C Steiner (1953)
5 skeletal & 5 denture patterns.
SKELETAL
1. Angle SNA(82 degree)
2. Angle SNB (80)
3. Angle ANB(2)
4. Mandibular plane angle (32)
5. Occlusal plane to S-N Plane(14.5)
DENTAL
1.Maxillary incisor position(angular-22)
2. Maxillary incisor position(linear-4 mm)
3. Mandibular incisor position(angular-25)
4. Mandibular incisor position(linear-4mm)
5. Inter incisal angle(131)
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1.Angle SNA Inner angle on SN plane to N-A line.
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2. Angle SNB Inner angle on SN plane to N-B line.
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3.Angle ANB Its difference of the angle SNA and SNB .
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4. Mandibular plane angle The inclination of mandibular plane to SN represents vertical relation of the mandible with the cranium.
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5. Occlusal plane angle The angle between the occlusal plane and the SN plane.
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Denture pattern
1.Maxillary incisor position(angular) The angulation of the long axis of maxillary incisor to NA line.
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2.Maxillary incisor position(linear) The linear distance of maxillary incisor to NA line.
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3.Mandibular incisor position(angular) The angulation of the long axis of mandibular incisor to NB line.
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4.Mandibular incisor position(linear) The linear distance of mandibular incisor to NB line.
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5.Inter incisal angle it is a measure of relative position of upper incisor to lower incisor.
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Tweed’s analysis(1954)
1.FMA (25 degree)-Mandibular plane angle
2.IMPA(90)-Lower incisors angle
3.FMIA(65)-Angle between Frankfort horizontal plane and lower incisors plane.
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45. Cephalometrics-Dr.Gyan P.Singh
Name , Age, Sex& Date
FMIA
FMIA
FMA
IMPA
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46. MCQ: Porion & Orbitale Nasion & sella Porion & Sella Porion & Nasion
1.Frankfort horizontal is a reference plane constructed by joining
Porion & Orbitale
Nasion & sella
Porion & Sella
Porion & Nasion
2. Facial plane is formed by
Sella gnathion
Sella nasion
(C) Nasion pogonion
(D) Nasion subspinale 46

47. 4. Facial plane angle is between FHP and N-Pog line
3. Downs cephalometric analysis uses– line as a reference plane
ANS-PNS
SN plane
Porion-Orbitale
Gonion- menton
4. Facial plane angle is between
FHP and N-Pog line
FHP and mandibular plane angle
(C) FHP and Sella Gonion line
(D) Basion- Nasion and N-Pog line 47

48. (C) Both maxillary and mandibular growth (D) To design appliance
5. Y-axis is used to analyse
Maxillary growth
Mandibular growth
(C) Both maxillary and mandibular growth
(D) To design appliance
6. Decreased interincisal angle indicates
Retrusion of teeth
Protrusion of teeth
Vertical overlap
Horizontal overlap 48

49. 7.The three landmarks which determine skeletal convexity are
Glabella,prosthion, and supramentale
Nasion, Sella and articulare
Nasion, subspinale and pogonion
Orbitale, anterior nasal spine and pogonion
8. Angle SNA is used to
Relate maxilla to mandible
Relate maxilla to cranial base
Relate mandible to maxilla
None of the above 49

50. 9. In bimaxillary prognathism malocclusion SNA is increased
SNB is increased
Both SNA and SNB are increased
Both SNA and SNB are decreased
10. Which of the following conditions cannot be assessed by a lateral cephalogram
Mandibular lateral asymmetry
Vertical facial descrepancy
Increased posterior height
Decreased anterior height 50

51. REFERENCES
Graber TM:Principles and Practicce Orthodontics,WB Saunders,1988
Profitt.Contemporary Orthodontics,Elsevier India.3rd ed.,2000. 51

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