Cephalometrics: A Guide to Landmarks and Measurements

 Cephalometrics
introduced for use
by orthodontists in
1931 by Dr.
Broadbent in the
USA and Hofrath
in Germany
independently of
one another.
www.indiandentalacademy.com

Cephalo: head
Metric: measurments
 Cephalometry: is the analysis and the
interpretation of standardized radiographs of the
facial bones.
 It is a standardized and reproducible form of
skull radiography used extensively in orthodontics
to asses the relationships of the teeth to the jaws,
and the jaws to the rest of the facial skeleton.

 Head position: the patient’s head is
oriented in the same position relative to
the x-ray beam every time a film is taken,
with the use of a cephalostat.
 Ear rods: in the ear canals (external
auditory meatus).
 Frankfort plane: horizontal.
 Teeth: in centric occlusion.
 Lips: in their habitual position.

 Assess facial and dentoskeletal
relationships.
 To study growth and growth patterns
 Evaluation of post treatment changes.
 Research purposes and long term follow-
up studies.

 The cranial base.
 The facial skeleton.
 Soft tissues.

The midpoint of
the
sella turcica

The most inferior
anterior point on
the margin of the
orbit

• Sella Turcica (S)
• Orbitale (Or)

The most anterior
point
of the frontonasal
suture

The most posterior
inferior point on the
clivus (basiocciput).
It represents the
posterior limit of the
midline cranial base.
It lies on the anterior
margin of foramen

• Nasion (N)
• Basion (Ba)

The tip of the
anterior nasal
spine

The tip of the
posterior nasal
spine

• Anterior Nasal Spine
(ANS)
• Posterior Nasal Spine
(PNS)

The most posterior
point on the
profile of the
maxilla between
the
anterior nasal
spine and the
alveolar crestwww.indiandentalacademy.com

The most posterior
point on the profile of
the mandible between
the chin point and the
alveolar crest

• A point
• B point

The most anterior
point on the bony
chin

The lowermost point
of the mandibular
symphysis in the
midline

• Pogonion (Pog)
• Menton (Me)

The most inferior point
on the mandibular
symphysis in the
midline

The most posterior
inferior point on the
angle of the
mandible

• Gnathion (Gn)
• Gonion (Go)

The uppermost,
outermost point on
the bony external
auditory meatus

• Porion (Po): superior
point of external
auditory meatus
• Machine Porion:
landmark created by ear
post of cephalostat

The intersection of
the posterior border
of the neck of the
mandibular condyle
and the lower
margin of the

The most
superior
posterior point
on the head of
the mandibular
condyle

The tip of the
crown of the most
prominent upper
incisor

The tip of the crown
of the most
prominent lower
incisor (E-lower
incisor edge)

• 1: most anterior
upper
central incisor__
• 1: most anterior
lower central incisor
• 6: upper permanent
first molar
__
• 6: lower permanent
first molar

Sella - NaSioN
plaNe:
S – N
Represent the cranial
base

De CoSter’S liNe:
Follows the floor of the
anterior
cranial base from the
anterior margin of the
ethmoid bone to sella
turcica

Maxillary
liNe:
aNS - pNS

MaNDibular
plaNe:
Me - Go

 Line drawn from Menton (Me) to
Gonion (Go)

oCCluSal
plaNe:
Cusp tips of molars – tip
of lower incisor

FuNCtioNal oCCluSal plaNe
(Fop):
Passes through the occlusion
of the premolars or deciduous
molars and the first
permanent molars

the liNe FroM poiNt
a to poGoNioN:
a – poG
For best aesthetic results: -lower incisor
edges
lay on A-Pog
line
(Willians, 1969)

Measurement:
 Skeletal relationships :
 Sagittal basal relationships
 Vertical basal relationships
 Dentoalvealar relationships
 Soft tissues analysis

Angle SNA (82 ±
3)
Prognathism of
maxillary
apical base

Angle SNB (79 ± 3)
Mandibular
prognathism

Angle ANB (3 ± 1)
The
anteroposterior
apical base
relationship
(skeletal pattern)

 Jaw discrepancies (maxillary and
mandibular).
 Anteroposterior position of the Nasion
 Inclination of S-N line to the Frankfort
plane.
 Lower anterior facial height.

Wits analysis
(Jacobson, 1975)
Compares the
relationships of
the maxilla and
mandible with
the occlusal
plane (FOP)

S-N-POG (87 ± 3)
Indicate the
anteroposterior
position of the chin

Maxillary-
mandibular
planes angle
(Mx-Mn or MM
angle) (27 ± 5)

Frankfort-
mandibular
planes angle (FM
angle) (27 ± 5)

If the SN line inclination from the True
horizontal or from Frankfort plane
deviates more than 6 degrees, and
less than 11 degrees, measurements
based on the SN line should be
corrected by this difference.

Face height
ratio
(Me-Mx / N-
Me) (50 - 55 %)
To estimate the
anterior
intermaxillary
height

Gonial angle
(Ar-TGp / TGi-
Me)
(126 ± 5)

 Upper incisor to maxillary plane angle
(UI / Mx) (108 ± 5)
 Lower incisor to mandibular plane angle
(LI / Mn) (92 ± 5)
 Interincisor angle (UI / LI) (133 ± 10)
 Lower incisor edge to A-Pog distance (E↓
A-Pog) (0-2 mm)

UI / Mx plane angle (108
± 5)
LI / Mn plane angle (92
± 5)
Interincisal angle (133 ±
10)
E A-Pog (0-2 mm)↓
E C (0-2 mm)↓ ↑
FOP / Mx (10 ± 4)

 Cephalometric superimpositions
involve the evaluation of:
Changes in the overall face.
Changes in the maxilla and its dentition.
Changes in the mandible and its
dentition.
Amount and direction of condylar growth,
and mandibular rotation.
(Kristensen, 1989)www.indiandentalacademy.com

 The most accurate superimposition is
obtained by tracing the first radiograph and
superimposing that tracing on the second
film, registering the appropriate cranial
base structures. (Ekstrom, 1982)
 Reliable picture of overall facial growth.
Superimposition on:
 S-N line with registration at sella (reliable)
 De Coster’s line (more reliable).

 Maxilla is subject to extensive periosteal
remodelling.
Superimposition on:
 The anterior surface of the zygomatic
process – little periosteal remodelling with
growth (Bjork and Skieller, 1979) (not
easily seen and too short).
 Anterior surface of the palatal vault.
 The maxillary plane (at PNS)(contour of
the palate at the alveolar process base).

The mandible undergoes rather
complex remodeling changes
(anterior / posterior growth rotations.
(Bjork and Skieller,
1972)

Superimposition on:
 The inner contour of the cortex of
the mandibular symphysis (most
useful).
To evaluate remodeling in the mandible with
growth.
To evaluate changes in the lower incisor
position.
 The contour of the mandibular canal.
 The crypt of the developing third
permanent molars (from the time of
commencement of mineralization until root
formation begins).

 A digitizer comprises an illuminated radiographic
viewing screen connected to a computer.
 Information from a lateral cephalometric radiograph
is entered into the computer by means of a cursor
which records the horizontal and vertical (x,y) co-
ordinates of cephalometric points or bony or soft
tissue outlines.
 Specialized software employed to utilize the
information entered to produce a tracing and/or the
analysis of choice.
 Research purposes.

 Digora scanner.
 Studies have shown digitizers to be as
accurate as tracing a radiograph by hand.
 There was no difference in the regional
superimpositions of the mandible, the
maxilla, and the cranial base, manually vs
digitally with Quick Ceph 2000.
(Roden-Johnson et al.,
2008)

Cephalometrics: A Guide to Landmarks and Measurements

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