Cephalometrics analysis

CEPHALOMETRICS
DR. RACHAEL GUPTA
MDS PART II

CONTENTS
• Introduction –defination
• Why cephalometrics
• History of cephalometrics
• Radiographic techniques used in cephalometrics
Lateral cephalometrics
Posterioanterior cephalometrics
• Tracing technique
• Cephalometric landmarks
• Cephalometric planes
• Cephalometric analysis
• Errors in cephalometric measurement
• Methods of controlling error in cephalometric
• Advances in cephalometrics
• Conclusion

Definition of terminology
Anthropometry – Measurement of dimensions of the human
body and it’s parts.
Craniometry – Branch of anthropometry dealing with
measurements of dimensions and angles of bony skull.
Cephalometry – Scientific measurement of dimensions of the
‘living’ head.
RADIOGRAPHIC CEPHALOMETRY- ALEXANDER JACOBSON

Cephalometric analysis – Process of evaluating the skeletal, dental,
and soft tissue relationships of a patient by comparing
measurements performed on the patient’s cephalometric tracing
with population norms for respective measurements, to come to a
diagnosis of the patient’s orthodontic problem.

5
WHY CEPHALOMETRICS ?
• Growth and development
• Diagnosis
• Treatment planning
• Prognosis
• Record of patient
• Craniofacial abnormalities
• Facial types
• Soft tissue morphology
• Symmetry of face

HISTORY OF CEPHALOMETRIC
RADIOGRAPHY
• In 1895, Prof. Wilhelm Conrad Roentgen made a
remarkable contribution to science with the
discovery of x-rays.
• Prof. Wilhem Koening & Dr. Otto Walkhoff
simultaneously made the first dental radiograph in
1896
• Van Loon;
- First to introduce Cephalometrics to orthodontics.
- He applied anthropometric procedures in analyzing
facial growth by making plaster casts of face in to
which he inserted oriented casts of the dentition.

• Hellman (1920s) used cephalometric techniques and described their
value.
• A.J.Pacini (1922) The first x- ray pictures of skull in the standard
lateral view were taken
• Pacini;
Introduced a teleroentgenographic technique for standardized
lateral head radiography which proved to be of tremendous use in
cephalometry, as well as in measuring growth and dev of face.
• Atkinson (1922) advocated in locating and the soft tissue relations to
the face and the jaws.

• In 1923 Mc Cowen -visualize the relationship between the hard and
soft tissues and to note changes in profile which occur during
treatment.
• In 1931 cephalometric radiography came to full function when B.
Holly Broadbent in USA published methods to obtain standardized
head radiographs in the Angle Orthodontist (A new X ray tech & its
application to orthodontia).

• The diagnosing dental deformities by means of planes &
angles was first proposed in 1922 by Paul Simon in his
book, “Fundamental Principles of a Systematic Diagnosis
of Dental Anomalies”.

RADIOGRAPHIC TECHNIQUES
Basic equipment:
• Adjustable Cephalostat
• An X-ray source
• Film cassette with intensifying screens
• Film cassette holder

THE CEPHALOSTAT
Ear rod
forehead clamp
1. Ear rod
2. Forehead clamp
3. Cassette holder
4. Film cassette with intensifying screens
Cassette
holder
Radiographic cephalometry- Alexander Jacobson

Cephalostat
• 2 Types
- Broadbent-Bolton method
- Higley method
Used in most modern cephalostats.
=

X-Ray Source position
• It is positioned 5 feet(152.4cm) from the subject’s
midsagittal plane.
Film position
To minimize variations in magnification from patient to
patient & to obtain consistent measurements on the patient
over time, a distance of 15cm is often used.

15"60"
Source Plane
X-ray Source
Patient in Head Positioning
Device
Mid-Sagittal Plane
Film Plane
X-ray Film in
Cassette
152.4 cms

Factor affecting cephalometric radiographic
• Patient positioned with cephalostat using –
bilateral ear rods (placed at auditory meatus)
• Pt is in standing position
• Mid sagittal plane is vertical – perpendicular
to xray beam
- parallel to film plane
• Frankfort plane parallel to floor
• To penetrate the bony structures of the skull
setting below 70Kvp should not be used

PATIENT POSITIONING;
• 8*10 inch film cassette equipped with the appropriate film
and intensifying screens placed horizontally or vertically in
cassette holder.
• Patient placed within the ear rods of cephalostat exerting
moderate pressure on external auditory meatus.
• Patient Frankfort plane parallel to floor
• Locking nasal positioner against bridge of nose
• Film cassette moved 15cm away from midsagittal plane
• Xray beam enter and exit the pt near horizontal axis of
auditory meatus
LATERAL CEPHALOGRAM

• Once patient positioned properly, pt instructed to close to centric and
swallow
• Holding body of tongue in posterior area of soft palate

PATIENT POSITIONING;
PA CEPHALOMETRIC
RADIOGRAPH
• 8*10 film cassette placed vertically with cassette
holder component of cephalostat
• Bilateral ear rods rotated 90 degree
• Pt facing the film
• Mid coronal plane perpendicular to x-ray beam of pt
and parallel to film plane
• Nasal positioner placed on bridge of nose
• The central ray should enter the posterior part of skull
in occipital region and exit at most anterior and inferior
aspect of nasal bow

Shortcomings of the
Frankfurt horizontal plane
• Some individuals show a variation of their FH plane
to the true horizontal to an extent of 10°.
Am J Phys. Anthropol. 16: 1956
• An alternative to overcome this was to use a functionally derived
NHP(natural head position), according to Morrees & Kean.
• It was obtained by the patient standing up & looking directly into the
reflection of his/her eyes in a mirror directly ahead in the middle of
the cephalostat.
• To record the NHP ,the ear rods are not used for locking the patient
head into a fixed position but serve to place the midsagittal plane at a
fixed distance from the film plane.

Tracing supplies and equipments
• A lateral cephalogram
• Acetate matte tracing paper(.003 inches thick, 8×10
inches)
• A sharp 3H drawing pencil or a very fine tipped pen
• Masking tape
• A tooth symbol tracing template for drawing the teeth. Also
templates for tracing the outlines of ear rods.
• Dental casts trimmed to maximum intercuspation of the teeth in
occlusion.
• Viewbox (variable rheostat desirable but not essential).
• Pencil sharpener and a eraser.

Tracing of a Cephalogram
• Thorough familiarity with the gross anatomy is required before the
tracing.
• By convention the bilateral structures (eg, the rami and inferior
borders of the mandible) are first traced independently. An average is
then drawn by visual approximation, which is represented by a broken
line.

General considerations for the tracing
• Start by placing the cephalogram on the viewbox with the
patient’s image facing towards the right.
• Tape the four corners of the radiograph to the viewbox.
• Draw three crosses on the radiographs, two within the
cranium and one over the area of the cervical vertebrae
(registration crosses).

• Place the matte acetate film over the radiograph and tape it
securely.
• After firmly affixing the acetate film, trace the three
registration crosses.
• Print the pt name, record number, age in years and months,
the date on which the cephalogram was taken and your
name on the bottom left corner of the acetate film.
• Begin tracing using smooth continuous pressure.

Stepwise tracing technique
1. Tracing the soft tissue profile, external
cranium and the vertebrae,
2. Tracing the cranial base, internal
border of the cranium, frontal sinus
and the ear rods,
3. Maxilla and related structures
including the nasal bone and
pterygomaxillary fissure,
4. The mandible.

A landmark is a point which serves as a guide for measurement or
construction of planes. They are divided into two types:
1. Anatomic: These represent actual anatomic structure of the skull.
1. Constructed: These have been constructed or obtained secondarily
from anatomic structures in the cephalogram.

Unilateral landmarks
• Nasion (N)
• Sella (S)
• Point A (subspinale)
• Prosthion
• Infradentale
 Anterior nasal
spine(ANS)
Posterior nasal spine (PNS)
Point B (Supramentale)
Pogonion (Pog)
Gnathion
Menton (Me)
Basion (Ba)
• Orbitale Articulare(Ar)
• Gonion Pterygomaxillary fissure (Pt)
• Condylion Porion(Po)
Bilateral landmarks

• Nasion
The most anterior point
midway between frontal and nasal
bones on fronto-nasal suture.

• Orbitale
The lowest point on the inferior bony
margin of orbit

• Sella
The point representing the midpoint
of pituitary fossa or sella turcica

• Basion
It is median point of the anterior margin of foramen magum.

• Articulare
It is a point at the junction of
posterior border of ramus and the inferior
border of basilar part of occipital bone.

• Condylion
Most superior point on the head of the
condyle.

• Anterior Nasal Spine (ANS)
It is the anterior tip of the sharp bony
process of the maxilla at the lower margin of
the anterior nasal opening.

• Posterior Nasal Spine (PNS)
Process formed by the united
projecting ends of the posterior border.

• Porion
Superior most point on the external acoustic
meatus.

• Gonion (Go)
It is the lowest posterior and most out
ward point on the angle of the mandible.

• Pogonion (Pog)
The most anterior prominent point
on the chin in the median plane.

• Gnathion (Gn)
It is the most anterior and
inferior point of the bodychin.

• Menton
It is the most inferior midline point on the
mandibular symphysis

• Infradentale (Id)
The highest inter dental point
on the alveolar mucosa between the
mandibular central incisors.
(Highest and most anterior point).

• Point B –
It is the most posterior midline
point in the concavity of the
mandible between the most
superior point on the alveolar
bone

• Subnasale (Sn)
A skin point, the point
at which the nasal septum
merges inferiorly with the
upper lip.

• Point A
Deepest point on
the midline contour of
the alveolar process
between the anterior
nasal spine and
prosthion.

• Prosthion (Pr)
The lowest interdental point
on the alveolar mucosa in the
median plane between the
maxillary central incisor.

Cephalometric planes
Are derived from at least 2 or 3 landmarks and are used
for measurements, separation of anatomic divisions, definition
of anatomic structures of relating parts of the face to one
another. The various cephalometric planes used are:

• Frankfurt Horizontal plane: This
plane is drawn from Porion to
Orbitale
(The name is given in the conference
of anthropology,held at Frankfurt
in1885)
Horizontal planes

• Sella-Nasion plane: It
represents the anterior
cranial base.
• Can be accurately
located on the
radiographs.

• Basion-Nasion plane: This plane is
from basion to nasion point
• Palatal plane: plane passing through
the ANS and the PNS.
• Occlusion plane: It is the plane
passing through the cusp tips of the
upper and lower first molars and a
point bisecting the overbite.

• Mandibular plane: Different definitions
are given in different analysis
1.Downs analysis – it extends from Gonion
to Menton.
2.Steiner’s anlysis – it extends from
Gonion to Gnathion.
3.Tweed’s analysis- tangent to lower
border of mandible
Go
Me
Gn

Vertical Planes
• Facial plane : It extends from
nasion to pogonion.
• Y-axis : It is the line joining
sella to gnathion.
• Ramal plane : It is drawn
tangent to the posterior border
of the ramus and the condyles.
S N
Gn
Pog

Principle of Cephalometric analysis
• The goal is to compare the patient with a normal reference group, so
that differences between the patient’s actual dentofacial relationships
and those expected for his/her racial or ethnic groups are revealed.
• First popularized after world war-II in the form of Down’s analysis.

MEASUREMENT ANALYSIS
Hard tissue analysis
• Down’s
• Tweed’s
• Wits appraisal
• Steiner’s
• McNAMARA’S
• Rakosi’s
• Schwarz
• Cogs
Soft tissue analysis
• Holdaway’s

 Developed in 1948
 Consists of 10 parameters --- 5 skeletal & 5 dental
 FH plane is used as the reference plane.
- It was based on the study of 20 white subjects who had good occlusion
and proportional facial skeleton.
- This analysis indicates whether the dysplasia is in the facial skeleton or in
the dentition or both.
DOWN’S ANALYSIS

When observing facial profiles,W B Downs noted that generally the position
of the mandible could be used in determining whether or not faces were
balanced.
Downs reduced his observations to the following four basic facial types:

NN
PoPo O
O
Pog
Pog
Retrognathic- recessive mandible Prognathic- a protrusive mandible

N
Po O
Pog
N
Po O
Pog
Orthognathic- an ideal or average mandible
True prognathism – a pronounced protrusion of the lower
face

Down’s analysis consist of 10 parameters-
5 SKELETAL
- Facial angle
- Angle of convexity
- A-B Plane angle
- Mandibular Plane angle
- Y-Axis
5 DENTAL
- Cant of occlusal Plane
- Interincisal Angle
- Incisor occlusal plane angle
- Incisor mandibular Plane angle
- Upper incisor to A – POG line

Facial Angle
FH plane(po-o) – facial Plane (n-pog)
Used to measure degree of protrusion or retrusion of the lower
jaw
Average value – 87.8 degree
Range – 82-95 degree
Indicate anterio-posterior positioning of mandible in relation to
upper face.
Increased angle in case of class III malocclusion
Decreased in case of class II malocclusion
N
Po O
Pog

Angle of Convexity
N-A and A-POG
Reveals convexity of skeletal profile
Average value – 0 degree
Range – 8.5 to 10 degree
Increased angle in case of class II malocclusion
Decreased or negative angle in case of class III malocclusion

A-B Plane Angle
A-B and N-POG
Range – 9 to 0 Degree
Indicate maxillo-mandibular relationship in relation to
facial plane .
Negative angle- class II
Positive angle class III or class I prominence with
mandible

Mandibular plane
The mandibular plane acc to downs tangent to gonial
angle and lowest point of symphysis.
Relating FH plane and mandibular plane
Range - 17-28 degree
Indicate growth pattern
Increased angle – Vertical growth
Decreases angle - Horizontal growth

Y(growth) axis
Intersection of sella- gnathion with FH plane
Range – 53-66 degree
Increased angle – vertical growth of mandible
Decreases angle - horizontal growth

Cant of occlusal plane
Measure Angle between occlusal plane and FH plane
Range – 1.5-14 degree
larger +ve angle – class II maloclussion
long rami tends to decrease this angle

Inter incisal Angle
Line intersecting long axis of maxillary and mandibular CI.
Range – 130-150.5 degree
Increased angle – class II div II
Decreases angle – class II div I

Incisor occlusal plane angle
Line intersecting long axis of mandibular CI and
occlusion plane .
Positive angle increases as teeth incline forward,
teeth become proclined
Values are least in class 2 div 2 when incisors are
retroclined

Incisor mandibular plane angle
Line intersecting long axis of mandibular CI and
mandibular plane .
Increased angle – lower incisor proclination

Upper incisor to POG Line/protusion of maxillary
incisors
Linear measurement between incisal edge of maxillary CI
and the line joining A to POG .
Average value – 2.7 mm
Range – 1 to 5 mm
positive– Upper incisor proclination
Negative- retruded position of maxillary incisors

Introduced by Charles tweed (1895-1870)
tweed’s analysis is based on:
Inclination of mandibular incisors to the basal bone
And its association with vertical relation of the mandible to cranium
TWEED’S ANALYSIS
Tweed used three planes to establish a diagnostic triangle, the three planes used in this
analysis are:
1. Frankfurt horizontal plane
2. Mandibular plane
3. Long axis of lower incisor

TWEED’S
TRIANGLE
FMA – 25 degree
IMPA – 90 degree
FMIA-
65 degreeN
Po O

FMA indicates the direction of lower facial growth,both
horizontally and vertically
Mean -25 degree
If FMA Is less than 25 degree –horizontal growth pattern
FMA is greater than 25 degree –vertical growth atettern
IMPA indicates the upright position of mandibular incisor
And balance and harmony of lower facial profile
Mean -90 degree
FMIA indicates balance and harmony betwwen lower face
and anterior limit of dentition
Mean- 65 degree

2. FMA from 28 ° to 35 °, prognosis fair
3. FMA above 35°, Prognosis bad.
Following Can be derived from the change in its value as:
1. FMA 16° to 28 ° : prognosis good
Approximately 60 percent
malocclusions have FMA
between 16° and 28°

STEINER’S ANALYSIS
Developed by C.Steiner in 1953 can be considered the first of the modern
cephalometric analysis.
Sella nasion is a reference line.
Based on three different parameters -
• Skeletal analysis
• Dental analysis
• Soft tissue analysis

S
N
A
N
Maxilla
SNA: 820
Antero-posterior position of maxilla with cranial
base
Large value – Prognathic maxilla
Less value – backward or recessive location of
maxilla

Mandible
SNB: 800
Antero-posterior position of mandible with
cranial base
Large value – Prognathic Mandible (skeletal
class III)
Less value –recessive mandible
S
N
B

S
N
B
Prognathic mandible showing greater SNB angle

Relationship of maxilla and
mandible
ANB: 20
Difference between SNA and SNB.
Reflects anterio-posterior relationship of maxilla
to mandible
Large value – Class II skeletal tendency
Lesser value or zero- class III tendency
N
A
B
S

Occlusal plane
OP-SN: 140
Angle between SN and Occlusal Plane
Indicate relation of occlusal
plane to cranial base
Large value – vertical growth pattern/long
faces
Skeletal open bite
Decreases in – horizontal growth
pattern/skeleteal deep bite
S
N
Occlusal
plane

Mandibular plane
MP-SN: 320
Angle between SN and mandibular Plane
Indicate relation of mandibular
plane to cranial base
Large value – vertical growth pattern
S
N
mandibular
plane
Go
Me

Dental analysis
maxillary incisor position
UI-NA= 220
UI-NA= 4mm
NA
Angle between upper incisor and N-A Plane
Indicate relative inclination of maxillary incisor
Large angle seen –class 2 div 1
Angle less than 22 degree – class 2 divison 2
Measurement greater than 4mm-convex
profile,common class 1 bimaxillary protrusion
or class 2 div 1 malocclusion
Less than 4mm –concave profile, class 2 div 2
N
A

Mandibular incisor position
LI-NB = 250
LI-NB = 4mm
NB
Angle between lower incisor and N-b Plane
Indicate relative inclination of mandibular
incisor
Angle greater-class 2 div 1
Angle less – class 2 div 2 or class 3
N
B

Interincisal
angle: 1300
Angle between lower incisor and upper incisor
Indicate relative position of mandibular incisor
to maxillary incisor.
More acute or less than 130 – upper or lower
incisor require uprighting
greater – correcting of axial inclination

SOFT TISSUE ANALYSIS
STEINER’S S-LINE-
-Line extending from middle of S formes by
lower border of nose and contour of chin.
- Lips should fall on this line
- If lips beyond – Convex profile
- If lips behind – Concave profile

The mean values for Steiner’s analysis are as follows:
SNA 82°
SNB 80°
ANB 2°
SND 76°
Upper incisor to NA 22°
Upper incisor to NA 4mm
Lower incisor to NB 25°
Lower incisor to NB 4mm
interincisal angle 130°
MP to SN 32°

WIT’S APPRAISAL
The severity or degree of anteroposterior jaw disharmony can be measured on a lateral cephalometric head
film.
Cranial and denture landmarks
Point A is located at the deepest point on the contour of the maxilla between the anterior nasal spine
and the alveolus.
point A must be regarded as the anterior limit of the maxillary denture base.
Point B was described by Downs in 1948 as a point at the deepest curvature of the outline of the
symphysis of the chin.
This point is subjected to change with lower incisor movement may be regarded as the anterior limit
of the lower denture base

ANB angle as a measure of jaw dysplasia
The ANB angle in normal occlusions is generally 2 degrees.
Angles greater than this indicate tendencies toward Class II jaw disharmonies
smaller angles (extending to negative readings) reflect Class III anteroposterior jaw discrepancies

Lateral cephalometric head film tracing of a Class II malocclusion (A) and normal
occlusion(B), each having an ANB angle of 7 degrees.

Further example of a Class II malocclusion (A) and a normal occlusion (B) having
identical ANB angles readings (6 degrees).

The anteroposterior relationship of the jaws in these examples is not satisfactorily reflected by the ANB angle
readings.
Relating jaws to cranial reference planes presents inherent inconsistencies because of variations in cranio-
craniofacial complex will directly influence the ANB reading
Diagrammatic representation of an “average normal occlusion.” B, Nasion located farther
forward. This has the effect of reducing the ANB angle reading in this instance from 2 degrees to 2
degrees. C, Nasion positioned farther back has the effect of increasing the ANB angle, in this
example, from 2 degrees to 5 degrees.

Diagrammatic representation of an “average” normal occlusion. B, Counterclockwise
rotation of the jaws has the effect of reducing the ANB angle (in this instance from 2 degrees to 5
degrees). C, Clockwise rotation of the jaws has the effect of increasing the ANB angle (from 2
degrees to 8 degrees).

The “Wits” appraisal of jaw disharmony
The method of assessing the
degree or extent of the jaw disharmony entails
drawing perpendiculars on a lateral
cephalometric head film tracing from points A
and B on the maxilla and
mandible, respectively, onto the occlusal plane
which is drawn through the region of maximum
cuspal interdigitation.
The points of contact on the occlusal plane from
points A and B are labeled AO and BO

AO-BO
1. Skeletal Class-II : BO is
placed more than 4 mm
behind AO(positive reading)
2. Skeletal Class-III : BO is
ahead of AO A
B
O
Basis on excellence of occlusion
Average
In females AO And BO coincides
In males BO is located 1mm ahead
of point AO

Application of the “Wits” appraisal
A, Class II malocclusion: ANB angle, 7 degrees; “Wits” reading, 10 mm. B, Normal occlusion: ANB
angle, 7 degrees; “Wits” reading, 0

A, Class II malocclusion: ANB angle, 6 degrees; “Wits” reading, 6 mm. B, Normal occlusion: ANB angle, 6
degrees; “Wits” reading, 0 mm.

The ANB angle measures 10 degrees. By conventional assessment, this is a severe Class II
jaw disharmony. According to “Wits” appraisal (2 mm), the malocclusion is that of a mild Class
II skeletal pattern

appraise severity of anteroposterior jaw disharmony or dysplasia, the jaws must of necessity be related to
each other and to neither cranial nor extracranial landmarks.

Orthodontic procedures, we should strive never to allow this measurement to become less
than 1.5 mm. Faces with average lip thickness where there is a 3 mm. measurement are
preferred.
High skeletal convexity associated with mandibles that have obtuse gonial angles and long
lower face dimension, or in cases of very thin lips, it may be necessary to settle for a 1
mm. measurement.
With less face height, more prominent chins, and longer or thicker upper lips a measure
ment of up to 4 mm may not be excessive

UPPER AND LOWER GONIAL ANGLE
The gonial angle may be divided by a line drawn
from nasion to gonion.
• This gives an upper and lower gonial angle
• The upper angle is formed by the ascending
ramus and the line joining nasion and gonion.
• A larger upper angle indicates horizontal growth.
• The mean value is 50-55°.
• The lower angle is formed by the line joining
nasion and gonion and the lower border of the
mandible.
• A larger lower angle indicates vertical growth
pattern.
• The mean value is 72-75°.

FACIAL HEIGHT
POSTERIOR FACIAL HEIGHT is measured from S to
Go.
It is more in patients having horizontal growth
pattern than patients having vertical growth
pattern.
ANTERIOR FACIAL HEIGHT is measured from N to
Me.
It is more in patients having vertical growth
pattern than patients having horizontal growth
pattern.
It is given by ratio
Posterior facial height/anterior facial height multiply 100
Ratio less than 62% express vertical growth pattern
More than 65% express horizontal growth pattern

EXTENT OF ANTERIOR
BASAL LENGTH
It is taken from N to Se.
It is increased in horizontal growth pattern and
reduced in vertical growth pattern.
Mean value is 75mm.

EXTENT OF POSTERIOR
BASAL LENGTH
It is measured from S to Ar.
Also called as lateral cranial base length.
It is based on posterior facial height and position of the
fossa.
Short cranial bases are seen in vertical growth
pattern and skeletal open bites.
Mean value is 32-35mm

ANALYSIS OF JAW BASES
• SNA expresses the sagittal relationship of the
anterior limit of the maxillary apical base to the
anterior cranial base.
• It is large in prognathic maxilla and small in
retruded maxilla.
• Mean value is 81°.

SNB
• SNB expresses the sagittal reltionship between the
anterior extent of the mandibular apical base and
anterior cranial base.
• It is large with a prognathic mandible and small
with a retrusive mandible.
• If SNB is small and mandible is retrognathic
functional appliance therapy is indicated.

Base plane angle
The base plane angle is the angle between the
palatal plane and the mandibular plane.
• It is large in vertical growth pattern and small in
horizontal growth patterns.
• Mean value is 25° .
• The base plane angle is divided into 2:
Upper – between the palatal plane and the
occlusal plane. Mean value is 11°.
lower – between the occusal plane and the
mandibular plane . Mean value is 14°.

Inclination angle
It is the angle formed by the perpendicular line
dropped from N- Se at N and the palatal plane.
• A large angle expresses upward and forward
inclination whereas small angle indicates down and
back tipping of the anterior end of the palatal
plane and maxillary base.
• Mean value is 85°

Linear measurement of jaw bases
The extent of the mandibular base is determined
by measuring the distance between Go and Pog.
• More in patients having horizontal growth
pattern than patients having vertical growth
pattern.
• Ideally it should be 3mm more than N-Se distance
Extent of mandibular base

• It is determined by measuring the distance
between the PNS and a perpendicular drawn
from point A to the palatal plane.
• The difference of the measurement between
horizontal and vertical growth pattern is slight.
• Mean value is 44mm.
Extent of maxillary base

Length of ascending ramus
• The length of the ascending ramus is done by
measuring the distance between the gonion and
the condylion.
• The length of the ramus is more in patients
having horizontal growth pattern than vertical
growth pattern.
• Mean value is 46mm.

Analysis of dentoalvelor relationships
• The long axis of the upper incisors is extended to
intersect the S-N line and the posterior angle is
measured.
• It is used to determine the position of the
maxillary incisors.
• In cases of proclined upper incisors the angle
increases.
• Mean value is 102° .
• A smaller angle indicates the incisors are
lingually tipped which is advantageous for
functional appliance treatment.

Lower incisors
• The long axis of the lower incisors is extended to
intersect with the mandibular plane and the
posterior angle is measured.
• Smaller angle indicates lingual tipping of the
incisors.
• • Mean value is 90° .

Position of upper and lower incisors
• Position of the incisors is the distance
of the incisal edges from the N-Pog line
the so called facial plane.
• The average position of the maxillary
incisors is 2 to 4mm anterior to the N-
Pog line
• The average position of the mandibular
incisors is 2mm anterior or posterior to
the N-Pog line

CONCLUSION
• Cephalometrics although a major one- is one of many approaches and
considerations in the diagnosis and treatment of an orthodontic patient.
• Cephalometric analysis is essentially a technique to be used as a guide
in the diagnosis of a case of malocclusion.
• Although innumerable controversies exist in the field of
cephalometrics, it is still a very significant & effective diagnostic tool.

 Radiographic cephalometry- Alexander Jacobson
 Contemporary orthodontics- Willium Proffit 4th ed.
 Cephalometric radiography; Thomas Rakosi.
 Soft tissue cephalometric analysis: AJODO-1999: 116.
REFERENCE

Cephalometrics analysis

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