Cephalometrics /certified fixed orthodontic courses by Indian dental academy

Cephalometrics
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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Cephalometrics
History, Evolution,
Landmarks

Introduction
 Ever since God created man he is trying
to change his image.
 Attempts to change facial appearance are
recounted throughout recorded history.
 The question of what is a normal face?
what constitutes beauty? will probably
never be answered.www.indiandentalacademy.com

 Orthodontists, in their attempts to
change facio-oro-dental deviations from
accepted norms, have adopted
cephalometric measurement, a method
employed in physical anthropology.
 Cephalometric radiography was
introduced in to orthodontics during the
1930s.

 Cephalometry developed from craniometry.
 Craniometry is defined as “the art of
measuring skulls of animals so as to
discover their specific differences”.
 For many years anatomists and
anthropologists were confined to
measuring craniofacial dimensions using
the skull of dead individuals.

 Cephalometry is concerned with
measuring the head inclusive of soft
tissues, be it living or dead.
 Craniometry – measuring skull.
 Cephalometry – measuring head.
 However Cephalometry had its
limitations due to the inaccuracies that
resulted from varying thickness of soft
tissues.

 With the discovery of X rays by Roentgen
in 1895, Radiographic Cephalometry
came in to being.
 Defined as the measurement of head
from bony and soft tissue land marks on
the radiographic image
(Krogman & Sassouni 1957).

This approach combines the
advantages of Craniometry and
anthropometry.
The disadvantage is that it produces
two dimensional image of a three
dimensional structure.

History
 History prior to the advent of
radiography begins with the attempts of
the scientists to classify the human
physiques.
 Basically it stems from the history of
Anthropometry.

 In 500 BC, Hippocrates, Father of
medicine, designated two physical types
1.Habitus phithicus -- long thin body
subject to tuberculosis, &
2.Habitus applecticus -- short thick
individual susceptible to vascular
diseases & apoplexy.
 Kretschmer (1921) described : pyknic
(compact), asthenic (without strength), &
athletic.

 Sheldon continued the work & refined it.
 He classified physique in to three types.
1.Endomorphy is centered on the
abdomen, and the whole digestive
system.
2.Mesomorphy is focused on the
muscles and the circulatory system.
3.Ectomorphy is related to the brain
and the nervous system.

 He discovered that these three
fundamental elements which, when
combined together, made up all these
physiques or somatotypes.
 He worked out ways to measure these
three components and to express them
numerically so that every human body
could be described in terms of three
numbers.

 Somatotype is defined as a quantified
expression and description of the
present morphological conformation of
a person.
 It is independent of size, age and
gender
 Denoted as x-y-z. (endo – meso – ecto).
Min – 1, Max – 7.

 Extreme physique types
- Endomorph (rounded, 7-1-1).
- Mesomorph (muscular, 1-7-1).
- Ectomorph (angular, 1-1-7).
Typical
- males (3-4-4)
- females (5-3-3)
Meso
Endo
Ecto

 Sheldon's Temperament Types:
Temperament is body type in
action.
 Endotonia is seen in the love of relaxation,
comfort, food and people.
 Mesotonia is centered on assertiveness and a
love of action.
 Ectotonia focuses on privacy, restraint and a
highly developed self-awareness.

History of measurements
and proportions
 Portrayal of human form demands not
only artistic talent & technical ability but
a disciplined & consistent style.
 The ancient Egyptians developed an
intricate quantitative system that defined
the proportions of the human body. It
became known as the Canon of
proportions.

 Initially the canons were enclosed in a grid
system of equalized squares with 18 horizontal
lines, line 18 drawn through hairline.
 Later it was included in a grid system of 22
horizontal lines, line 21 drawn through the
upper eyelid.

Period of Renaissance
 Leonardo da vinci was probably the
earliest to apply the theory of head
measurement.
 He used lines related to specific structures
in the head in his study of human form.

 His drawings included a study of facial
proportions in natural head position.
The profile was divided in to seven parts
by eight horizontal lines.
 The joining of the lower lip and chin and
the tip of the jaw and the upper tip of
the ear with the temple forms a perfect
square; and each face is half of the
head.

 Albrecht Durer, published a treatise in
1528 on cranial measurements which
comprised the “Vier Bucher von
menschliche Proportion”.
 Using geometrical methods he provided a
analysis of the leptoprosopic face &
euryprosopic face in coordinate system,
where the horizontal and the vertical lines
were drawn through the same land marks
or facial features.

 The sixteenth century saw the first truly
scientific attempt at cranial
measurement & the introduction by
Spigel of the “lineae cephalometricae”.
 Spigel‟s linear cephalometricae consisted
of four lines: the facial, occipital,
frontal, & sincipital lines.

 Facial: from the most inferior point of the chin to
the most superior point on the forehead.
 Occipital: from the crown of the head to atlas.
 Frontal: from one temple to the other.
 Sincipital: from the lowest part of the ear, to the
highest part of the sinciput -- the anterior part of
the head or skull from forehead to the crown.
 According to him in a well proportioned skull,
these lines should all be equal to one another.

 The Dutchman Pieter Camper was credited
with the introduction of facial angle.
 He oriented crania on a horizontal from the
middle of porus acusticus to a point
below the nose. Camper‟s horizontal
became the reference line for angular
measurements used to characterize
evolutionary trends in anthropological
studies.

 The facial angle as he described was
formed by the intersection of a facial line
and a horizontal plane.
 The facial line was a line tangential to the
most prominent part of the frontal bone
and to the slight convexity anterior to the
upper teeth.

 The horizontal plane passes through the
lower part of the nasal aperture,
backwards along the line of the
zygomatic arch, and through the centre
of the external auditory meatus.
 Camper‟s facial angle was readily
accepted as a standard measurement in
craniology.

 The terms prognathic and orthognathic
introduced by Retzius are tied to
Camper‟s illustrations of facial form.
 As a result the facial angle became a time
honored anthropological method to
determine the facial type.
 Prognathism refers to the prominence of
jaws, relative to forehead, & a straight
facial profile -- as orthognathous.

Drawbacks of Camper’s facial angle were:
 Ignores the contribution made by the lower
jaw to facial forms.
 No strict adherence to location of posterior
reference point for the horizontal plane.
 Direct comparison of skull of different ages
was not possible because the locating
point might alter its position with age.

 Deschamps introduced cephalic
triangle made up of facial, occipital, &
coronal angles.
 Facial angle was formed by the
intersection of a horizontal that passed
from the external auditory meatus to the
base of the nose, which crossed the
profile line.

 Similar to Camper‟s facial angle. The use
of external auditory meatus as a
reference point enabled a rough
comparison to be made between skulls.
 An antagonist of Camper, Johann
Friedrich Blumenbach rejected the use
of lines & angles as a test of universal
characteristics & proposed a minute
survey of the skull particularly the
frontal and maxillary bones.

 Anders Retzius correlated the two
schemes, i.e., of Camper and
Blumenbach, thereby providing a basis
for the methods of craniology used
today.
 He is also credited with the introduction
of cephalic index, the ratio of breadth to
length of the skull expressed as a
percentage.

 19th century produced 3 great men in history of
craniology: Huxley, Broca & Topinard.
 Thomas Huxley wrote that “the so called facial
angle, is the product of two factors, a facial & a
cranial, which vary independently.
 He also introduced two new angles, the spheno
maxillary and spheno ethmoidal angles. He
preferred the spheno maxillary angle to
Camper‟s angle when comparing the degree of
prognathism in different skulls.

 Broca -- founder of Paris Society of
Anthropology.
 He introduced a base line “plan alveolo-
condylien” which passes through the
alveolar point & tangential to the inferior
surfaces of the two occipital condyles.
 He developed craniostat,
constructed of wood for
positioning the skull.

 Paul Topinard used a similar craniostat
with some additional modifications.
 “The craniometer substitutes the
mathematical data for the uncertain
data founded on judgment & opinion”.
 It studies the skeleton, the cranium &
the face separately and each of the
plates as well.

 As standardization became the buzz word
in craniometry the
13th General Congress of the German
Anthropological Society met at
Frankfurt-am-Maine in August 1882.
 It is to this Congress that the Frankfurt
Horizontal Plane owes its name.

 The FHP is modified from the Baer‟s
horizontal which passed through the
zygomas, and a refinement of
Von Ihering‟s horizontal.
 Von Ihering‟s – plane passes through the
centre of auditory meatus to the lower
point on the inferior margin of orbit.
 FHP -- plane passes through the upper
border of the bony meatus vertically above
their centres.

 However the reproducibility of this plane
on an intact skull is less than Broca‟s
condyloalveolar plane.
 It is now taken as passing through the
right and left porion &left orbitale.
Thereby reducing the problems incurred
by asymmetrical skulls.

History of Cephalometric
Radiography
 In 1895, Prof. Wilhelm Conrad Roentgen
made a remarkable contribution to science
with the discovery of x-rays.
 On December 28, 1895 he submitted a
paper “On A New Kind of Rays, A
Preliminary Communication” to the
Wurzburg Physical Medical Society.

 Prof. Wilhem Koening & Dr. Otto
Walkhoff simultaneously made the first
dental radiograph in 1896.
 It was clear that the use of x-rays
provided the means of obtaining a
different perspective on the arrangement
and relation of bones thus expanding the
horizons of craniometry & cephalometry .

 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 in 1920s used cephalometric
techniques and described their value.

 The first x- ray pictures of skull in the
standard lateral view were taken by
A.J.Pacini & Carrera in 1922.
 Pacini received a research award from the
American Roentgen Ray Society for a
thesis entitled “Roentgen Ray
Anthropometry of the Skull”.

 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.
 His method, which was rather primitive,
involved a large fixed distance from the x
ray source to the cassette.

 The head of the subject, placed adjacent
to a standard holding the cassette, was
immobilized with a gauze bandage
wrapped around both the face and the
cassette.
 He identified the following landmarks :
gonion, pogonion, nasion, and anterior
nasal spine. He also located the sella
turcica & external auditory meatus.

 Atkinson in 1922 advocated the use of
roentgenograms in locating the „key
ridge‟ and the soft tissue relations to the
face and the jaws.
 In 1923 Mc Cowen reported that he used
profile roentgenograms for orthodontic
purposes to 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).
 H. Hofrath simultaneously published the
same in Fortschritte der Orthodontie in
Germany.

 The interesting fact is that Broadbent
was an Orthodontist, whereas Hofrath
was a Prosthodontist.
 This development enabled orthodontists
to capture the field of cephalometry
from the anatomists and
anthropologists.

Broadbent’s contribution
 Broadbent‟s interest in craniofacial growth
began with his orthodontic education
under E.H. Angle in 1920.
 He continued to pursue that interest
along with his orthodontic practice,
working with a leading anatomist J.
Wingate Todd

 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”.
 Although his “Law of the Canines” was
later disproved by Broadbent, his theories
stimulated Broadbent to apply the
principles of craniometry to living subjects.

 During 1920‟s Broadbent refined the
craniostat in to craniometer by the
addition of metric scales.
 That proved to be the first step in the
evolution of craniostat in to a
radiographic cephalostat.

 The patient‟s head was centered in the
cephalostat with the superior borders of
the external auditory meatus resting on
the upper parts the two ear rods.

 The lowest point on the inferior bony
border of the left orbit, indicated by the
orbital marker, was at the level of the
upper parts of the ear rods.
 Nose clamp was fixed at the root of the
nose to support the upper face.

 The focus film distance was set at 5 feet
(152.4 cm) and the subject film distance
could be measured to calculate image
magnification.
 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.

 Hofrath‟s technique differed from
Broadbent‟s in that the path of the
central ray was not fixed in relation to
the head and no plan was suggested for
super positioning subsequent x-rays.

 In 1937, using serial records of twins;
Broadbent showed how growth – or its
lack – was the greatest limiting factor in
clinical success.
 In 1943 he stipulated that eruption of
the third molars had no ill effect on the
denture, particularly the lower incisors.

 Brodie, in a landmark study, corroborated
Broadbent‟s contention that the growth
pattern of the normal child‟s face
develops in an orderly downward and
forward fashion and that the pattern, once
attained at an early age, did not change.

Thompson and Brodie in a report on the
rest position of the mandible, concluded
that:
 The morphogenetic pattern of the head
was established at a very early age and
did not change.
 The presence or absence of teeth has little
bearing on the form or the rest position
of the mandible.
 Vertical facial proportions are constant
throughout life.www.indiandentalacademy.com

 Margolis (1943) wrote on the relationship
between the inclination of the lower incisor
and the incisor-mandibular plane angle.
 First to corroborate Tweed‟s clinical
observation that, in normal occlusions, the
lower incisors are 90° to the mandibular
basal bone.
 In 1947 Margolis contributed his maxillo-
facial triangle.

Cephalometric
Analysis
 The major use of radiographic
cephalometry is in characterizing the
patient‟s dental and skeletal relationships.
 This led to the development of a number
of cephalometric analyses to compare a
patient to the population standards.

 William. B. Downs in 1948 developed the
first cephalometric analysis.
 Its significance was that it presented an
objective method of portraying many
factors underlying malocclusion.
 Followed by other analyses by
Steiner (1953), Tweed (1953), Ricketts
(1958), Sassouni (1969), Enlow (1969),
Jaraback (1970), Jacobson (1975) etc.

Evolution of
Cephalometrics
 The thoroughness of Broadbent‟s design of
the cephalometric method is evident from
the fact that the basic technique has
survived unchanged for over 70 years.
 The instrumentation had evolved to a more
suitable form for the individual practitioner
through the pioneering efforts of Margolis,
Higley & others.

Patient Orientation
 The ears are used as the basis for
orientation & fixation of the patient in the
beam axis.
 FH plane was adopted for horizontal
orientation with nasion for stabilization.
 FH plane was chosen because this
approximates the natural head position.

But the FHP also had its drawbacks :
 Some individuals show a variation of
their FH plane to the true horizontal to
an extent of ± 10°. (Avg – 7o)
 The landmarks to locate the FH plane,
orbitale & porion, are difficult to identify
on a cephalogram.

 An alternative to overcome this problem
was to use a functionally derived NHP.
 Obtained by asking the subject to look at
the image of their eyes in the mirror
located at eye level. (Morrees & Kean).
 Functionally derived NHP was more
accurate but its reproducibility was less
than FHP (anatomic approx of NHP).

X-Ray Source Position
 The x-ray is positioned 5 feet (152.4 cm)
from the subject‟s midsagittal plane. A
change to 150 cm has been adopted by
some, but the difference is negligible.
 A major improvement in cephalostats is
the capability of taking both lateral & PA
views with a single x-ray source.

Film Position &
Enlargement
 Other significant change from original
technique is adjustability of film position.
 The original cephalostat was based on
the design of the anthropometric
craniometer & cassettes were attached to
these mechanisms.

 The disadvantage of this very efficient
mechanical design is that it makes
cassette position and resultant
enlargement dependent on head size.
 Evaluation of serial changes by direct
superimposition is made unreliable by
this variable enlargement.

 The relative immunity of angular
measurements to enlargement
distortions led researchers to opt for
angular over linear values when possible.
 Newer instruments have been developed
to over come this variable enlargement
by providing independent adjustments
for head holding mechanisms & cassette.

Postero-Anterior
(Frontal)
Cephalometry

PA Cephalometry
 Since the introduction of a standardized
method for obtaining skull radiographs,
cephalometrics has become one of the
major diagnostic tools in orthodontics.
 The posterior anterior cephalogram
contains diagnostic information not
readily available from other sources.

 PA Ceph allows to evaluate the width and
angulation of the dental arches to their
osseous bases in the transverse plane.
 Helps evaluate the width and transverse
positions of the maxilla and mandible,
 To assess nasal cavity width; and analyze
vertical and/or transverse facial
asymmetries.

 A cephalostat that can be rotated 90° is
used, so that the central beam passes the
skull in a postero anterior direction and
bisects the transmeatal axis at 90o.
 Maintaining the identical horizontal
orientation from lateral to the PA
projection is critical when comparative
measurements are made. (Moyers et al).

 In using NHP for PA ceph, the practical
problem encountered is that the patient
facing the cassette makes it difficult for
the patient to look in to a mirror to
register NHP (Solow &Tallgren).
 Space problems make it impossible to
place a nose piece in front of nasion to
establish support in vertical plane.

 As far as exposure is considered, more
exposure is needed for PA cephalograms
than lateral views (Enlow).
 For better evaluation of patients with
craniofacial anomalies that require
special attention to upper face, the
patient should be positioned with the tip
of the nose and forehead lightly touching
the cassette holder (Chierci).

 In cases of suspected significant
mandibular displacement, the PA
cephalogram should be taken with the
mouth of the patient slightly open in
order to differentiate between
functional mandibular displacements
& dentoskeletal facial asymmetry
(Faber, 1985).

Cephalometric
Landmarks
 -- are readily recognizable points on a
cephalometric radiograph or tracing,
representing certain hard or soft tissue
anatomical structures (anatomical
landmarks) or intersections of lines
(constructed landmarks).

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

 Garn -- there are no „fixed points‟ in the
skull of living person. Depends on age,
sex, maturation rate, ethnic background,
and other factors.
 Landmarks show a range of normal
variation about mean. The orthodontist
to determine whether facial dimensions
and relationship fall with in the range of
normal variation or not.

Landmarks in Lat.Ceph
Hard tissue landmarks
 A-point (Point A, Subspinale, SS) : the
deepest (most posterior) midline point on
the curvature between the ANS and
prosthion.
 Anterior nasal spine (ANS): the tip of the
bony anterior nasal spine at the inferior
margin of the piriform aperture in the
midsagittal plane.

 Articulare (Ar) : constructed point
representing the intersection of three
radiographic images: the inferior surface
of the cranial base and the posterior out
line of the mandibular condyles
 B-point (Point B, Supramentale, sm): the
deepest (most posterior) midline point on
the bony curvature of the anterior
mandible, between infradenale and
pogonion.

 Basion (Ba): the most anterior inferior
point on the margin of the foramen
magnum in the midsagittal plane.
 Bolton (Bo) : the highest points on the
outlines of the retrocondylar fossae on
the occipital bone, approximating the
centre of the foramen magnum.

 Clinoidale (Cl) : most superior point on the
contour of anterior clinoid -- Usu unilateral.
 Condylion (Co) : the most superior point
on the head of the mandibular condyle
 Glabella (G): the most prominent point of
the anterior contour of the frontal bone in
the midsagittal plane.

 Gnathion (Gn) : the most anterior inferior
point on the bony chin in the midsagittal
plane.
 Gonion (Go): the most posterior inferior
point on the outline of the angle of the
mandible.
 Incisior inferius (Ii) : the incisal tip of the
most labially placed mandibular incisor.
 Incisior superius (Is) : maxillary incisor.

 Infradentale (Id) : the most superior
anterior point on the mandibular alveolar
process between the central incisors.
 Key Ridge (KR) : the lowermost point on
the contour of the shadow of the ant wall
of infratemporal fossa.

 Menton (Me) : the most inferior point of
the mandibular symphysis in the
midsagittal plane.
 Nasion (N,Na) : the intersection of the
internasal and frontonasal sutures in the
midsagittal plane
 Opisthion (Op) : the most posterior
inferior point on the margin of the foramen
magnum in the midsagittal plane

 Orbitale (Or) : the lowest point on the
inferior orbital margin
 Pogonion (pog, P, Pg) : the most anterior
point on the contour of the bony chin in
the midsagittal plane
 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.

 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.
 Prosthion (Pr, Supradentale) : the most
inferior anterior point on the maxillary
alveolar process between the central
incisors.

 Pterygomaxillary 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.

Soft Tissue Landmarks
 Cervical point (C) : the innermost point
between the submental area and the
neck in the midsagittal plane. Located
at the intersection of lines drawn
tangent to the neck and submental
areas.

 Inferior labial sulcus (Ils) : point of
greatest concavity on the contour of the
lower lip between the labrale inferius and
menton in the midsagittal plane.
 Labrale inferior (Li) : point denoting the
vermillion border of the lower lip in the
midsagittal plane.
 Labrale superior (Ls) : point denoting the
vermillion border of the upper lip in the
midsagittal plane.

 Pronasale (Pn) : most prominent point of
the tip of the nose, in the midsagittal
plane.
 Soft tissue glabella (G’) : most prominent
point of soft tissue drape of the fore head
in the midsagittal plane.
 Soft tissue menton (Me’) : most inferior
point of the soft tissue chin in the
midsagittal plane.

 Soft tissue nasion (N’, Na’) : deepest
point of the concavity between the
forehead and the soft tissue contour of
the nose in the midsagittal plane.
 Soft tissue pogonion (Pg’, Pog’) : most
prominent point on the soft tissue contour
of the chin in the midsagittal plane.

 Stomion (St) : most anterior point of
contact between the upper and lower lip in
the midsagittal plane. When the lips are
apart at rest, a superior and an inferior
stomion point can be distinguished.
 Stomion inferius (Sti) : highest midline
point of the lower lip.
 Stomin superius (Sts) : lowest midline
point of the upper lip

 Subnasale (Sn) : point in the midsagittal
plane where the base of the columella of
the nose meets the upper lip.
 Superior labial sulcus (Sls) : point of
greatest concavity on the contour of the
upper lip between subnasale and labrale
superius in the midsagittal plane.
 Trichion (Tr) : demarcation point of the
hair line in the midline of the forehead.

PA Ceph
Bilateral Skeletal Landmarks
 Greater Wing Superior Orbit (GWSO) -
the intersection of the superior border of
the greater wing of the sphenoid bone and
lateral orbital margin.
 Greater Wing Inferior Orbit (GWI0) - the
intersection of the inferior border of the
greater wing of the sphenoid bone and the

 Lesser Wing Orbit (LWO) - the
intersection of the superior border of the
lesser wing of the sphenoid bone and
medial aspect of the orbital margin.
 Orbitale (O) - the midpoint of the
inferior orbital margin.
 Lateral Orbit (LO) - the midpoint of the

 Medial Orbit (MO) - the midpoint of the
medial orbital margin.
 Superior Orbit (SO) - the midpoint of
the superior orbital margin.
 Zygomatic Frontal (ZF) - the
intersection of the zygomaticofrontal
suture and the lateral orbital margin.

S
o
So
OO
M
o
Lo
Zf

 Zygomatic (Z) - the most lateral aspect of
the zygomatic arch.
 Foramen Rotundum (FR) - the center of
foramen rotundum.
 Condyle Superior (CS) - the most superior
aspect of the condyle.
 Center Condyle (CC) - the center of the
condylar head of the condyle.

 Mastoid Process (MP) - the most inferior
point on the mastoid process.
 Malar (M) - the deepest point on the
curvature of the malar process of the
maxilla.
 Nasal Cavity (NC) - the most lateral point
on the nasal cavity.

 Mandible/Occiput (MBO) - the
intersection of the mandibular ramus and
the base of the occiput.
 Gonion (G) - the midpoint on the
curvature at the angle of the mandible
(gonion).
 Antegonial (AG) - the deepest point on
the curvature of the antegonial notch.

Cs
Cc
Z
Mp
G
Ag

Midline Skeletal
Landmarks
 Crista Galli (CG) - the geometric center
of the crista galli.
 Sella Turcica (ST) - the most inferior
point on the floor of sella turcica.

 Nasal Septum (NSM) - the approximated
midpoint on the nasal septum between
crista galli and the anterior nasal spine.
 Anterior Nasal Spine (ANS) - the center of
the intersection of the nasal septum and
the palate.
 Incisor Point (IPU) - the crest of the
alveolus between the maxillary central
incisors.

 Incisor Point (IPL) - the crest of the
alveolus between the mandibular central
incisors.
 Genial Tubercles (GT) - the center of the
genial tubercles of the mandible.
 Menton (ME) - the midpoint on the
inferior border of the mental
protuberance.

Bilateral Dental Landmarks
 Maxillary Cuspid (MX3) - the incisal tip of
the maxillary cuspid.
 Maxillary Molar (MX6) - the midpoint on
the buccal surface of the maxillary first
molar.

 Mandibular Cuspid (MD3) - the incisal
tip of the mandibular cuspid.
 Mandibular Molar (MD6) - the midpoint
on the buccal surface of the mandibular
first molar.

Identification And
Reproducibility
 Cephalometric measurements are
subject to errors that may be caused by
radiographic projection errors with in
the measuring system & errors in
landmark identification.

 Identification errors are considered as the
major source of cephalometric error.
Factors involved are:
 Density & sharpness of the image.
 Anatomic complexity & superimposition of
hard and soft tissues.
 Observer‟s experience.

 To determine the reproducibility of some
commonly used 15 landmarks. A Meta
analysis was carried out by B. Tipkova, P.
Major, N. Prasad & B. Hebbe in 1997.
 The 15 landmarks were N, S,Or, Ba, P,
ANS, PNA, Pt. A, Ptm, Go, Co, Ar, Pog,
Me, Pt.B.

 It was concluded that some landmarks
are more reproducible in a horizontal
direction and others in a vertical
direction.
 B, A, Ptm,Go, & S, exhibited acceptable
levels of accuracy along the horizontal
axis.
 A, S, Ptm exhibited acceptable levels of
along the vertical axis as well.

Identification error in PA
(Frontal) Ceph
 Paul W. Major, Donald E. Johnson and
Karen L. Hesse conducted a study which
was designed to quantify the
intraexaminer and interexaminer
reliability of 52 commonly used posterior
anterior cephalometric landmarks.

 The horizontal and vertical identification
errors were determined for a sample of
33 skulls and 25 patients.
 Interexaminer landmark identification
error was significantly larger than
intraexaminer error for many landmarks.

 Baumrind and Frantz pointed out that
there are 2 classes of errors associated
with cephalometrics. The first is
“projection” errors due to geometry of
the radiographic setup.
 The second error termed “errors of
identification,” arise due to uncertainty
involved in locating specific anatomic
landmarks on the radiograph.

 Landmarks on a sharp curve or at the
intersection of curves are generally
identified easily than points located on
flat or broad curves.
 Points located in areas of high contrast
are easier to identify than points located
in areas of low contrast.
 Superimposition of other structures,
reduces the ease of identification.

Conclusion
 Broadbent‟s gave us a three dimensional
analysis, but orthodontics has remained
preoccupied with the lateral view. The
lateral view is easy to work with and the
patient is also much more recognizable
than in the frontal (P-A) view, especially
with soft tissue enhancement.

 Clinical orthodontics is yet to fully utilize
Broadbent‟s contribution.
 We treat in three dimensions and the width
dimension that are visualized on the
frontal view are crucial in many cases.
 In these days of increasing awareness of
the contribution of muscular and
respiratory function, we can no more
afford to ignore it.

Broadbent

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