COGS,DOWNS ANALYSIS,STEINERS ANALYSIS,WITS APPRAISAL

1. CEPHALOMETRIC
EVALUATION AND INTERPRETATION

2. Contents
• Introduction
• Cephalometrics for orthognathic surgery
(COGS)
• Soft tissue cephalometric analysis by burstone
• Downs Analysis
• Steiner Analysis
• Tweed Analysis
• Wits Appraisal

3. Introduction
• Origin: ‘Cephalo’ means head and ‘Metric’ is measurement
• Discovery of X-rays measurement of the head from shadows
of bony and soft tissue landmarks on the roentgenographic image
,known as the Roentgenographic Cephalometry.
• Spawned by the classic work of Broadbent in
United States and Hofrath in Germany,
cephalometrics has enjoyed wide acceptance

4. Definitions
• “The scientific measurement of the bones of the cranium and
face, utilizing a fixed, reproducible position for lateral
radiographic exposure of skull and facial bones” -- Moyers
• “ A scientific study of the measurements of the head with
relation to specific reference points; used for evaluation of
facial growth and development, including soft tissue profile” -
- Grabers

5. o The focus film distance was set at 5 feet (152.4 cm) and the
subject film distance could be measured to calculate image
magnification.
o With the two X ray tubes at right angles to each other in the
same horizontal plane, two images (lateral & PA) could be
simultaneously produced.

6. CEPHALOGRAM CAN BE OF TWO
TYPES:
a) LATERAL CEPHALOGRAM: this provides a lateral
view of the skull. It is taken with the head in a
standardized reproducible position at a specified
distance from the source of the X ray.
b) FRONTAL CEPHALOGRAM: this provides an antero-
posterior view of the skull.

7. CEPHALOMETRIC LANDMARKS
o Cephalometric landmarks are readily recognizable
points on a cephalometric radiograph or tracing,
representing certain hard or soft tissue anatomical
structures (anatomical landmarks) & (derived
landmarks).
o Anatomic landmarks represent actual anatomic
structures of the skull.
o Derived landmarks are the landmarks obtained
secondarily from anatomic structures in the
cephalogram.

8. Requirements
o Should be easily seen on the roentgenogram,
o Be uniform in out line, and easily reproducible.
o Should have significant relationship to the vectors of growth.
o Should permit valid quantitative measurements of lines and
angles projected from them.
o Measurements should be amenable to statistical analyses.

9. HARD TISSUE LANDMARKS

10. Hard tissue landmarks

11. Lateral cephalometric landmarks
• Nasion (N,Na) : the most anterior on the frontonasal sutures
in the midsagittal plane
• Orbitale (Or) : the lowest point on the inferior margin of the
orbit.
• Porion (Po): the most superior point on the outline of the
external auditory meatus (anatomic). The superior most point
of the ear rods (machine porion) sometimes is used.

12. • Gonion (Go): the most posterior inferior point on the outline
of the angle of the mandible.
• Pogonion(pog): its is the most anterior point of the boney cin
in the median plane.
• Gnathion (Gn) : the most anterior inferior point on the bony
chin in the midsagittal plane.
• Menton (Me) : the most inferior point of the mandibular
symphysis in the midsagittal plane.
•

13. • A-point (Point A, Subspinale, SS) : the most posterior midline
point on the concavity between the ANS and prosthion.
• Anterior nasal spine (ANS): the anterior tip of the sharp bony
process of maxilla at he lower margin anterior nasal opening.

14. • Articulare (Ar) a point at the junction of the posterior border
of ramus of mandible and inferior border of posterior cranial
base (occipital bone).
• B-point (Point B, Supramentale, sm): the most posterior
midline point in the concavity of the mandible between the
most superior point on the alveolar bone overlying the
mandibular incisors (infradental) and Pog.

15. • Basion (Ba): the lowest point on the anterior rim of the
foramen magnum.
• Bolton (Bo): the intersection of the outline of the occipital
condyle and the foramen magnum at the highest point on the
notch posterior to the occipital condyle.

16. • Pterygo-maxillary fissure (PTM) : bilateral inverted tear drop
shaped radiolucency whose anterior border represents the
posterior surfaces of the tuberosities of the maxilla.
• Sella (S) : the geometric centre of the pituitary fossa (sella
turcica), determined by inspection – a constructed point in
the midsagittal plane.
• Posterior nasal spine (PNS) : the most posterior point on the
bony hard palate in the midsagittal plane, the meeting point
between inferior & superior surfaces of the hard palate at its
posterior aspect.

17. When a jaw discrepancy accompanies a severe
malocclusion, only 3 possible treatment options
exist:
1. Modification of growth
2. Camouflage (displacing the teeth to obtain proper
function despite the jaw deformity), which
produces a dental compensation for skeletal
discrepancy.
3. Surgical repositioning of jaws and dentoalveolar
segments to obtain proper positioning

18. Analysis to help diagnose and plan for
orthognathic surgeries came in late seventies
and early eighties.

19. CEPHALOMETRIC
ANALYSIS
COGS by Burstone
(1978)
SOFT TISSUE ANALYSIS by
Burstone
(1980)

20. CEPHALOMETRICS FOR ORTHOGNATHIC
SURGERY (COGS) – BURSTONE

21. • Developed by Charles Burstone et al. at University
of Connecticut.
• Presented first in Journal of Oral Surgery. 1978:
April
• Followed by Soft Tissue Cephalometric Analysis
for Orthognathic Surgery in Journal of Oral Surgery
in 1980.

22. BURSTONE ANALYSIS
COGS system describes the horizontal and vertical
positions of the facial bones by the use of constant
coordinate systems as follows:
• Size of the bone are represented by direct linear
measurements.
• Shape of the bones are represented by the
angular measurements.

23. REFERENCE PLANE USED:
• The base line used for
comparison of most of the data
in this analysis is a constructed
plane called as Horizontal Plane
(HP)
• Most measurements in this
analysis will be made either
parallel to or perpendicular to
this Horizontal Plane.
• It is constructed by drawing a
line 70 from SN, intersecting at
N
HP

24. PARAMETERS
CRANIAL BASE
LENGTH
HORIZONTAL
SKELETAL PROFILE
VERTICAL PROFILE
VERTICAL DENTAL
MAXILLA AND
MANDIBLE
DENTAL

25. CRANIAL BASE LENGTH
• Cranial base length is measured by
measuring the distance between Ar
and N
• It is measured parallel to HP
• The measurement Ar to N is a
relatively stable anatomical plane,
however it can be changed by
cranial surgery
Le Forte II and Le Forte III
surgery changes position of N
Autorotation of Mandible changes
position of Ar

26. • Two measurements are considered
in Cranial Base length –
• Ar-Ptm and Ptm-N
• Ar-Ptm is the distance between Ar
and Ptm which is measured
parallel to HP
• Standard Value
MALES 37.1 + 2.8 mm
FEMALES 32.8 + 1.9 mm
Ar-Ptm indicates the position of
mandible in relation to posterior
surface of maxilla

27. • Ptm-N is the distance between Ptm
and N which is measured parallel to
HP
• Standard Value
MALES 52.8 + 4.1 mm
FEMALES 50.9 + 3 mm
• Ptm-N indicates the position of
posterior border of maxilla in
relation to Nasion
• If this value increases it indicates
more posterior position of maxilla
in relation to N
• If it decreases it indicates anterior
position of maxilla in relation to N

28. HORIZONTAL SKELETAL PROFILE ANALYSIS
Used to assess the amount of discrepancy in
anteroposterior direction
All the measurements in this set of analysis are
made parallel to HP--- hence it is called horizontal
skeletal profile analysis

29. 1. N Perpendicular to A, parallel to HP
• A perpendicular to HP is dropped
from N (N perpendicular) and
horizontal distance parallel to HP is
measured from point A
• Standard Value
MALES 0 + 3.7 mm
FEMALES -2 + 3.7 mm
This measurement describes the
position of apical base of maxilla in
relation to nasion

30. 2. N perpendicular to B, parallel to HP
• It is obtained by measuring the
distance between Point B and
Nasion perpendicular (N
perpendicular)
• Standard Value
MALES -5.3 + 6.7 mm
FEMALES -6.9 + 4.3 mm
This measurement describes the
position of apical base of
mandible in relation to nasion

31. 3. N perpendicular to Pg, parallel to HP
• It is obtained by measuring the
distance between Pogonion and
Nasion perpendicular (N
perpendicular)
• Standard Value
MALES -4.3 + 8.5 mm
FEMALES -6.5 + 5.1 mm
This measurement describes the
position of mandibular chin in
relation to nasion

32. 4. ANGLE OF CONVEXITY
• It is the angle formed between N-A
and A-Pg
• Standard Value
MALES 3.90 + 6.40
FEMALES 2.60 + 5.10
A positive angle indicates convex
profile while negative angle indicates
concave profile

33. VERTICAL SKELETAL PROFILE ANALYSIS
• A Vertical skeletal discrepancy may reflect an
anterior, posterior or complex dysplasia of the
face
• It is divided into two components:
Anterior component
Posterior component

34. 1. N - ANS perpendicular to HP
• Distance between N and ANS
measured perpendicular to HP
gives us the Middle third facial
height.
• Standard Value
MALES 54.7 + 3.2 mm
FEMALES 50 + 2.4 mm
Any increase or decrease in this value
indicates increased or decreased
middle third facial height respectively

35. 2. ANS – Gn perpendicular to HP
• Distance between ANS and Gn
measured perpendicular to HP
gives us the Lower third facial
height.
• Standard Value
MALES 68.6 + 3.8 mm
FEMALES 61.3 + 3.3 mm
Any increase or decrease in this value
indicates increased or decreased
lower third facial height respectively

36. 3. PNS – N, perpendicular to HP
• Distance between PNS and HP
gives us the posterior maxillary
height.
• Standard Value
MALES 53.9 + 1.7 mm
FEMALES 50.6 + 2.2 mm
Any increase or decrease in this
value indicates increased or
decreased posterior maxillary height
respectively
HP

37. 4. MP – HP angle
• Mandibular plane angle in relation to
Horizontal plane intersecting at Gn
gives us posterior divergence of
mandible
• Standard Value
MALES 230 + 5.90
FEMALES 24.20 + 50
• This angle relates posterior facial
divergence with respect to anterior
facial height
Any increase or decrease in value
suggests increased or decreased
posterior facial divergence

38. MAXILLA AND MANDIBLE
• ANS and PNS are projected
on HP
• Distance between these two
points on HP gives us total
effective maxillary length
• Standard Value
MALES 57.7 + 2.5 mm
FEMALES 52.6 + 3.5 mm

39. 2. Ar to Go
• Mandibular ramal length is
the linear distance between
Articulare and Gonion
• Standard Value
MALES 52 + 4.2 mm
FEMALES 46.8 + 2.5 mm
Variation in Ramal length can
be a causative factor for
skeletal open bite or deep bite

40. 3. Go to Pg
• Mandibular body length is
the linear distance between
Gonion and Pogonion
• Standard Value
MALES 83.7 + 4.6 mm
FEMALES 74.3 + 5.8 mm

41. 4. Point B to Pg
• This measurment describes the
prominence of chin in relation
to mandibular apical base
• It is obtained by measuring the
distance between point B and a
perpendicular to MP passing
through Pg
• Standard Value
MALES 8.9 + 1.7 mm
FEMALES 7.2 + 1.9 mm

42. 5. Ar-Go-Gn Angle (gonial angle)
• This measurment represents the
relationship between the ramal
plane and mandibular plane
• Standard Value
MALES 119.10 + 6.50
FEMALES 1220 + 6.90
Gonial angle also contributes to
skeletal open bite or deep bite

43. VERTICAL DENTAL ANALYSIS
• To obtain upper anterior dental
height, perpendicular distance from
incisal edge of upper incisor to NF
is measured
• Standard Value
MALES 30.5 + 2.1 mm
FEMALES 27.5 + 1.7 mm
Any increase or decrease in this value
indicates increased or decreased upper
anterior dental height respectively

44. 2. Lower 1 to MP
• To obtain lower anterior dental
height, perpendicular distance
between incisal edge of lower
incisor to MP is measured
• Standard Value
MALES 45 + 2.1 mm
FEMALES 40.8 + 1.8 mm
Any increase or decrease in this
value indicates increased or
decreased lower anterior dental
height respectively

45. 3. Upper 6 to NF
• To measure upper posterior dental
height a perpendicular line is
dropped from the tip of
mesiobuccal cusp of upper first
molar to NF
• Standard Value
MALES 26.2 + 2.0 mm
FEMALES 23 + 1.3 mm
Any increase or decrease in this
value indicates increased or
decreased upper posterior dental
height respectively

46. 4. Lower 6 to MP
• To measure lower posterior
dental height a perpendicular line
is dropped from the mesiobuccal
cusp of lower first molar to MP
• Standard Value
MALES 35.8 + 2.6 mm
FEMALES 32.1 + 1.9 mm
Any increase or decrease in this
value indicates increased or
decreased lower posterior dental
height respectively

47. DENTAL ANALYSIS
• OP is Occlusal Plane constructed
from buccal groove of first
permanent molars through a point
1 mm apical to the incisal edge of
the central incisors
• When incisors are not in proper
overbite relation, two OP are to be
constructed, upper and lower.
• Standard Value
MALES 6.20 + 5.10
FEMALES 7.10 + 2.50
HP
OP

48. • An increased OP-HP may be associated with skeletal
open bite, lip incompetence and increased anterior
facial height
• A decreased OP-HP may be associated with skeletal
deep bite, decreased anterior facial height and lip
redundancy

49. 2. A – B parallel to OP
• This distance is obtained by
measuring the distance
between projection of Point
A and Point B on OP
• Standard Value
MALES -1.1 + 2.0 mm
FEMALES -0.4 + 2.5 mm
This distance gives us
relationship between maxillary
and mandibular apical bases in
relation to OP

50. 3. Upper 1 to NF (angle)
• This angle is constructed by
intersecting a line passing
through the tip of incisal
edge through the root tip of
upper incisor and NF line
• Standard Value
MALES 1110 + 4.70
FEMALES 112.50 + 5.30
This angle gives us the
inclination of upper incisors
in relation to nasal floor (NF)

51. 4. Lower 1 to MP (angle)
• This angle is constructed by
intersecting a line joining the
incisal edge of lower incisor
passing through its root tip
and MP
• Standard Value
MALES 95.90 + 5.20
FEMALES 95.90 + 5.70
This angle gives inclination of
lower incisors in relation to MP

52. SOFT TISSUE ANALYSIS--- BURSTONE

53. FACIAL FORM
FACIAL
CONVEXIT
Y ANGLE
MAXILLARY
PROGNATHISM
MANDIBULAR
PROGNATHISM
VERTICAL
HEIGHT
RATIO
LOWER FACE
THROAT
ANGLE
LOWER
VERTICAL
HEIGHT
DEPTH
RATIO
LIP POSITION AND
FORM
NASOLABIAL
ANGLE
UPPER LIP
PROTRUSION
LOWER LIP
PROTRUSION
MENTOLABI
AL SULCUS
DEPTH
VERTICAL
LIP CHIN
RATIO
MAXILLAR
Y INCISOR
EXPOSURE
INTER
LABIAL
GAP

54. FACIAL FORM

55. 1. FACIAL CONVEXITY ANGLE
• This angle is formed by
intersecting G-Sn line
and Sn-Pg’ line
• Standard Value
120 + 40
Any increase or decrease
in this value indicates
Convex or Concave
Profile respectively.

56. 2. MAXILLARY PROGNATHISM
• Distance between Sn and a
line perpendicular to HP
passing through glabella
gives maxillary prognathism
• Standard Value
6 + 3 mm
A negative number suggests
Retrognathism while a large
positive value suggests
Prognathism

57. 3. MANDIBULAR PROGNATHISM
• Distance between Pg and a line
perpendicular to HP passing
through G gives Mandibular
prognathism
• Standard Value
0 + 4 mm
A negative number suggests
Retrognathism while a large positive
value suggests Prognathism

58. 4. VERTICAL HEIGHT RATIO
• It is the ratio between G-Sn
(Middle Facial third) and
Sn-Me’ (Lower Facial third)
measured perpendicular to
HP
• Standard Value
1 : 1
Increased ratio suggests
increased middle third height
and vice versa

59. 5. LOWER FACE THROAT ANGLE
• It is the angle formed by
intersection of Sn-Gn’ and
Gn’-C
• Standard Value
1000 + 70
This angle affects treatment
planning to correct
anteroposterior facial dysplasia

60. 6. Lower Face Vertical Height Depth Ratio
It is obtained by dividing Sn-
Gn’ distance with C-Gn’
distance
Standard Value
1.2 : 1
A much larger than 1 value
indicates that patient has a
relatively short neck

61. LIP POSITION AND FORM

62. 1. Nasolabial angle
• It is the angle formed by intersection
of Cm-Sn line and Sn-Ls
• Standard Value
1020 + 80
• Lower than normal Nasolabial angle
suggests proclination of upper
incisors or anterior maxillary base
protrusion or both
• Higher than normal Nasolabial angle
suggests retroclination of upper
incisors or maxillary base retrusion
or both

63. 2. Upper lip protrusion
• It is perpendicular distance
between Ls to Sn-Pg’ line
• Standard Value
3 + 1 mm
• It is perpendicular distance
between Li to Sn-Pg’ line
• Standard Value
2 + 1 mm

64. 4. Mentolabial Sulcus depth
• It is perpendicular distance
between deepest point on the
mentolabial sulcus to Li-Pg’ line
• Standard Value
4 + 2 mm
The depth of sulcus is affected by
various factors which are – flared
lower incisors, flaccid lower lip
tone, extruded upper incisors
causing rolling of lower lip, and
prominence of chin

65. 5. Vertical lip:chin ratio
• It is ratio between Sn-Stms
and Stmi-Me’
• Standard Value
0.5 or 1:2
Whenever the value decreases
vertical reduction genioplasty
should be considered

66. 6. Maxillary incisor exposure
• It is obtained by measuring the
distance between tip of upper
central incisor and Stms
• Standard Value
2 + 2 mm
Increased incisor exposure may be
due to vertical maxillary excess or
short upper lip
Decreased incisor exposure may be
due to vertical maxillary deficiency
or larger upper lip

67. 7. Interlabial Gap
• It is the distance between Stms
and Stmi
• Standard Value
2 + 2 mm
Patients with vertical maxillary
excess tend to have large interlabial
gap and lip incompetence
Patients with vertical maxillary
deficiency tend to have no Inter
labial gap and Lip redundancy

68. This cephalometric analysis is one step in diagnosis
and treatment planning for a surgical case. It gives
the clinician an insight into the quantitative nature of
the skeleto-dental and also soft tissue dysplasia.
COGS analysis uses linear dimensions to
describe the size and positions of facial bones and
this is practical because surgeon thinks more in
millimeters than in angles for planning and
accomplishing procedures.

69. • Types
LATERAL CEPHALOGRAM
FRONTAL CEPHALOGRAM
• USES
Helps in orthodontic diagnosis.
Helps in classification of skeletal and dental
abnormalities.
Helps in planning treatment of an individual.
Helps in evaluation of treatment results.
Helps in predicting growth related changes.

70. LANDMARKS

71. Horizontal Planes in Cephalometry

72. Downs Analysis
• It is one of the most frequently used
cephalometric analysis.
• Downs analysis consists of ten
parameters of which five are skeletal
and five are dental.

73. Skeletal Parameters
FACIAL ANGLE
• It is the inside inferior
angle formed by
intersection of nasion -
pogonion line and F.H.
plane.
• Average value- 87.8’
( 82 – 95’)
• Significance - Indicates
antero - posterior
positioning of mandible in
relation to upper face.
Angle is increased in

74. ANGLE OF CONVEXITY
• Angle formed at the
inersection nasion-point A
to point A – pogonion.
• Average value; 0’
( -8.5 to 10’).
• Significance- A positive
angle suggest a prominent
maxillary denture base in
relation to mandible.
• Negative angle is
indicative of prognathic
profile.

75. A-B PLANE ANGLE
• Angle formed at the
intersection of point A –
point B line to nasion –
pogonion line.
• Average value- -4.6’
( -9 to 0’)
• Significance- indicative
of maxillo mandibular
relationship in relation to
facial plane.
• Negative since point B
is positioned behind point
A.
• Positive in class III

76. MANDIBULAR PLANE ANGLE
• Angle formed at the
intersection of mandibular
plane with F.H.
Plane.
• Average value-
21.9’ ( 17 to 28’)

77. Y-AXIS
• Angle formed b/w sella
gnathion to F.H. plane.
• Average value; 59’ ( 53’
to 66’)
• Angle is larger in class
II facial patterns.
Indicates growth pattern
of a individual.

78. CANT OF OCCLUSAL PLANE
• Angle formed b/w
occlusal plane to F.H.
Plane
• Average value- 9.3 (
1.5 to 14’)
• Gives a measure of
slope of occlusal plane
relative to F.H. Plane.

79. INTER INCISAL ANGLE
• Angle between long axes
of upper and lower
incisors.
• Average value: 135.4’ (
130 to 150.5’)
• Decreased in case of
bidental protrusion

80. INCISOR OCCLUSAL
PLANE ANGLE
• This is the inside inferior
angle formed by the
intersection between the
long axis of lover central
incisor and the occlusal
plane and is read as a
plus or minus deviation
from a right angle
• Average value: 14.5” (
3.5 to 20’)
• An increase in this
angle is suggestive of
increased lower incisor
proclination.

81. INCISOR MANDIBULAR PLANE
ANGLE
• This angel is formed by
intersection of the long
axis of the lower incisor
and the mandibular plane.
• Average value: 1.4’(-8.2
to 7’)
• An increase in this angle
is suggestive of increased
lower incisor proclination.

82. UPPER INCISOR TO A-POG
• 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
4mm mm(rang-1 to 5
mm)
• The measurement is
more in patients
presenting with upper
incisor proclination.

83. STEINER ANALYSIS
• SKELETAL PARAMETERS
SNA ANGLE
SNB ANGLE
ANB ANGLE
MANDIBULAR PLANE ANGLE
OCCLUSAL PLANE ANGLE
• DENTAL PARAMETERS
UPPER INCISOR TO N-A ANGLE
UPPER INCISOR TO N-A LINEAR
LOWER INCISOR TO N-B ANGLE
LOWER INCISOR TO N-B LINEAR
INTER INCISOR ANGLE
• SOFT TISSUE ANALYSIS
S LINE

84. SNA (Maxillary position) 82.0
SNB (Mandibular position) 80
ANB (Maxillary/Mandibular relation) 2
lncisor to NA (Upper incisors to NA mm) 4mm
lncisor to NA (Upper incisors to NA degree) 22
lncisor to NB (Lower incisors to NB mm) 4mm
lncisor to NB (Lower incisors to NB degree) 25
lnter-incisal angle 131
Mandibular plane angle 32
SN to occlusal plane 14

88. TWEED ANALYSIS
Makes use of three planes
1. Frankfort horizontal plane
2. Mandibular plane
3. Long axis of lower incisors

89. FMA (Frankfurt plane to
mandibular plane)
16-35
FMIA (Frankfurt plane to lower
incisor angulation)
85-95
IMPA (Lower incisor to
mandibular plane)
60-75

90. WITS APPRAISAL
• Measures the relationship of maxilla and
mandible to each other and to the sagital
plane
• Used where ANB are not realiable
• Perpendicular are drawn from point A and
point B to the functional occlusal plane to
form AO and BO