- Cephalometrics involves analyzing and measuring radiographic images of the head called cephalograms. Key landmarks are identified and linear and angular measurements are made between landmarks to assess craniofacial structures. - There are several commonly used analyses in orthodontics including Downs analysis, Steiner analysis, Tweed analysis, and the Wits appraisal. These analyses establish norms for skeletal and dental relationships and angles that can be used to diagnose malocclusions. - Landmarks, reference planes like the Frankfort horizontal and mandibular planes, and angular and linear measurements between them allow for evaluation of the positions of jaws, teeth, and soft tissues to develop treatment plans. Serial cephalograms also enable

2. CEPHALOMETRICS
Dr. Aswin.A
Senior Lecturer
Dept of orthodontics and dentofacial
orthopedics

3. • The term cephalometrics is used to describe the
analysis and measurements made on the cephalogram.

4. Introduction:
Craniometry can be said to be the fore-runner of cephalometry.
The discovery of X-rays in 1895 by Roentgen provided a
method of obtaining the inner craniofacial measurements .

5. • In 1922 Paccini standardized the radiographic
head images by positioning the subjects against a
film cassette at a distance of 2 meters from the X-
ray tube.
• In 1931 Boardbent in U.S.A. and Hafrath in
Germany simultaneously presented a standardized
cephalometric technique using a high powered X-
ray machine and a head holder called Cephalostat.

6. Types of Cephalograms
Cephalograms can be of two types:
1. Lateral cephalogram
2. Frontal cephalogram

7. Uses of Cephalograms:
1.Study of craniofacial growth – Serial
cephalometric studies have helped in providing
information regarding:
 Growth patterns
 Prediction of future growth.
2. Diagnosis of craniofacial deformities.

8. 3. Treatment planning
4. Evaluation of treated cases
5. Cephalograms can be used as adjunct for
estimation of skeletal age.

9. TECHNICAL ASPECT
• X- ray source & head holding device called cephalostat.
Distance between the X- ray source & mid serial plane of
the pt is 5ft /152.4 cm.
5 ft

10. Cephalostat - 2 ear rods- horizontal plane
- orbital pointer- vertical stabilization
contacts lower border of left orbit
-forehead clamp- supports upper part
of face- above the nasal bridge.

11. Cephalometric Landmarks
The cephalometric landmark can be of two types:
1. Anatomic landmarks: These landmarks represent actual
anatomic structures of the skull.
2. Derived landmarks: obtained secondarily from anatomic
structures.

12. The landmarks that are used in cephalometrics should
fulfill certain requirements.
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 quantitative
measurements of lines and angles projected from them.

13. Nasion:
Anterior point
midway
between the
frontal and
nasal bones on
the fronto-nasal
suture.

14. Orbitale:
Lowest point on the
inferior bony margin
of the orbit.

15. Porion
The highest bony
point on the upper
margin of external
auditory meatus.

16. Sella
Represents the midpoint
of the pituitary fossa or
sella turcica. It is a
constructed point in the
mid-sagittal plane.

17. Point A:
Deepest point in the
midline between the
anterior nasal
spine and alveolar crest
between the two central
incisors.
It is also called
subspinale.

18. Point B:
Deepest point in the
midline between the
alveolar crest on the
mandible and the mental
process. It is also called
supramentale

19. Basion
Median point of the
anterior margin of
the foramen
magnum.

20. Bolton Point
Highest point at the
post condylar notch of
the occipital bone

21. Anterior nasal spine: Anterior
tip of the sharp bony
process of the maxilla.
Gonion: Constructed point at
the junction of ramal plane
and the mandibular plane.

22. Pogonion
It is the most
anterior point of
the bony chin in
the median
plane.

23. Menton
It is the most
inferior midline
point on the
mandibular
symphysis.

24. Gnathion: The most anterio-inferior point on the symphysis
of the chin..

25. Articulare: The junction of the posterior border of ramus and
the inferior border of the basilar part of the occipital bone.

26. Condylion: Superior point on the head of the condyle.
.

27. Posterior nasal spine: The interaction 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.

28. Lines and Planes in Cephalometric
Horizontal Planes:
S.N. Plane: It is the cranial line between the center of sella tursica
and the anterior point of the fronto – nasal suture. It represents
the anterior cranial base.

29. S.N. Plane
Sella - nasion
It represents the
anterior cranial base.

30. Frankfort horizontal plane: F-H PLANE
Orbitale - porion.

31. Occlusal plane
It is a denture plane
bisecting the
posterior occlusion
of the permanent
molars and
premolars and
extends anteriorly

32. Palatal plane
Ans - pns

33. Mandibular plane
TWEEDS
a. Tangent to lower border
of the mandible.
STIENER:
Gonion and Gnathion
DOWNS
Gonion - Menton
GN

34. Vertical planes

35. • A – pog line

36. • Facial plane- nasion - pog

37. Facial axis
Ptm - gnathion.

38. • E plane

39. Downs had based his findings on
20 Caucasian individuals of 12-17
years age group
belonging to both the sexes.
Downs analysis consists of 10
parameters of which five
are skeletal and five are dental.
DOWNS ANALYSIS

40. SKELETAL PARAMETERS
Facial angle
It is the inside inferior angle formed by the
intersection of nasion-pogonion plane and the
F.H. plane. The average value is 87.8 while
the range is 82 to 95.

41. Angle of convexity
Angle is formed by the
intersection of a line from nasion
to point A and a line from point A
to pogonion. This angle reveals
the convexity or concavity of the
skeletal profile.

42. A-B plane angle
Formed between a line connecting
point A and point B and a line
joining nasion to pogonion (facial
plane). The mean value is – 4.6*
while the range is
-9 to 0*.

43. Mandibular plane angle
The mandibular plane angle
is formed by the intersection
of the mandibular plane with
the F.H. Plane. Nml 21.9*
while the range is
suggestive of a vertical
grower with hyper divergent
facial pattern.

44. Y- axis (growth axis)
Obtained by joining the
sella – gnathion line
with the F.H. plane.
The mean value is
59*with a range of 53 to
66*.

45. Dental Parameters
Cant of occlusal plane: This angle is formed
between the occlusal plane and the F.H. plane.
The mean value is 9.3* while the range is 1.5
to 14*.

46. Inter – Incisal angle
Formed between the long
axes of the upper and lower
incisors. The average readings
is 135.4* while the range is
between 130 to 150.5*. The
angle is decreased in class I
bimaxillary protrusion and
class II, division I malocclusion
whereas it is increased in a
class II, division 2 case.

47. Incisor occlusal plane angle
This is the inside inferior
angle formed by the
intersection between the
long axis of lower
central incisor and the
occlusal plane and is
read as a plus or minus
deviation from a right
angle. The average value is
14.5* while the
range is between 3.5 to 20*.

48. Incisor mandibular plane angle
This angle is formed by
intersection of the
long axis of the lower
incisor and the
mandibular plane.
The mean angulation is
1.4* while the range is
between 8.5 to 7*.

49. Upper incisor to A – pog line
This is a linear
measurement
between the
incisal edge of the
maxillary central
incisor and the
line joining point
A to pogonion.
This distance is
on an average 2.7
mm.

50. STEINER’S ANALYSIS
Cecil C. Steiner developed this analysis in 1930. By comparing the traced readings or
measurements of patients with malocclusions with those of normal occlusion, the
degree of deviation from the normal could be determined. The Steiner’s analysis
could be divided into three parts.
a) Skeletal Analysis
This helps in relating the upper and lower jaws to the skull and to each other.
b) Dental Analysis
This helps in relating upper and lower incisors to their respective jaws and to each
other.
c) Soft tissue
This provides a means of assessing the balance and harmony of lower facial profile.

51. S.N.A
Intersection of S.N. plane and a line
joining nasion and point A. This angle
indicates the relative antero-posterior
positioning of the maxilla in relation to
cranial base.
Normal Value 82*. Maxilla is prognathic,
Decreased angle -Retrognathic maxilla.

52. S.N.B
S.N.B angle: S.N. plane and a line
joining nasion to point B. Indicates the
antero- posterior positioning of the
mandible in relation to the cranial base.
Nml- 80*.
Increased angle- prognathic mandible.
Decreased angle- Retrusive mandible

53. A.N.B. angle
Intersection of lines joining
nasion to point A and nasion to
point B.
Denotes the relative position of
the maxilla and mandible to
each
other. Nml-2*. Class II skeletal
tendency. Skeletal class III
S
N

54. Mandibular plane angle
Angle formed between S.N.
plane and the mandibular
plane. (SN – GO – GN)
Nml- 32*. Indication of the
growth pattern of an
individual. Indicative of a
horizontal growing face.
Vertical growing individual

55. Occlusal plane angle: Angle is formed
between the occlusal plane and the S.N.
plane. NV- 14.5*.

56. DENTAL ANALYSIS
Upper incisor to N-A (angle):
intersection of the long axis
of the upper central incisors and
the line joining nasion to point A.
Nml-22*. An increased angle is
seen in patients who have
proclined upper incisors as in
Class II, Div 1 malocclusion.

57. Upper incisor to N-A (linear): Linear measurement between the labial surface of the
upper central incisor and the line joining nasion to point A. Determining the I position.
NV- 4mm. It increases in cases with proclined I
Lower incisor to N-B (angle): Angle is formed between the N-B plane and the long axis
of the I . NV- 25*. Value indicates proclination of I value indicates upright or
retroclined I .
Lower incisor to N-B: Linear distance between the labial surface of lower central incisor
and the line joining nasion to point B. Helps in assessing the I inclination. Increase
in this measurement indicates proclined I . NV- 4mm.
Inter-incisor angle: angle formed between the long axis of the upper and lower central
incisors. A reduced inter-incisor angle is associated with a Class II. Division 1
malocclusion or a Class I bimax. A larger than normal value is seen in Class II, division 2
malocclusion. NV – 130 to 131*.

59. Soft tissue analysis
• S- line
Line extending from
soft tissue contour
of chin to middle
of an “S” formed
by the lower
border of the nose.

60. TWEED ANALYSIS
The tweed analysis makes use of three planes that form a diagnostic triangle. The
planes used are:
a. Frankfort horizontal plane.
b. Mandibular plane.
c. Long axis of lower incisor.
The objectives of the analysis includes the determination of the position of the lower
incisor and evaluation of prognosis of a case.
The angles formed by these three planes are:
Frankfort mandibular plane angle (FMPA)
Angle formed by the intersection of the Frankfort horizontal plane with the mandibular
plane. The Nml 25*.

61. Incisor mandibular plane angle (IMPA)
Angle formed by the intersection of the long axis of the lower incisor with the
mandibular plane. It indicates the inclination of he lower incisor. Nml 90*.
Frankfort mandibular incisor angle (FMPA)
Angle formed y the intersection of the long axis of the lower incisor with the F.H. plane.
Nml 65*.

62. The Wits appraisal
A measure of the extent
to which the maxilla and
the mandible are related
to each other in the
antero-posterior or
sagittal plane.
AO AHEAD OF BO-2mm.

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