This document discusses different types of cephalometric analyses used in orthodontics including Downs analysis, Steiner analysis, and Tweed analysis. It provides details on specific skeletal and dental landmarks and measurements for each analysis, including common reference values. Downs analysis consists of 10 parameters, 5 skeletal and 5 dental, to evaluate the maxillomandibular relationship and dental positioning. Steiner analysis also includes skeletal and dental measurements as well as a soft tissue measurement. Tweed analysis uses 3 reference planes to evaluate the mandibular plane angle and lower incisor angulation.

2. • 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.

3. LANDMARKS

4. Horizontal Planes in Cephalometry

5. Cephalometric Analysis
• Downs Analysis
• Steiner Analysis
• Tweed Analysis
• Wits Appraisal

6. 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.

7. 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
skeletal class III with

8. 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.

9. 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

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

11. 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.

12. 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.

13. 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

14. 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.

15. 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.

16. 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.

17. 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

18. 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

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

23. 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

24. 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