Basic of cephalometric rupesh

INTRODUCTION,INTRODUCTION,
HISTORY,MERITSHISTORY,MERITS
DEMERITS,DEMERITS,
LANDMARKS,LINES ANDLANDMARKS,LINES AND
PLANES OFPLANES OF
CEPHALOMETRICSCEPHALOMETRICS..
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CONTENTSCONTENTS
 Introduction
 Historical aspect
 Advantages and limitations
 Radiographic cephalometric technique
 Quality of the radiographs
 Protection from radiation
 Tracing Technique
 Cephalometrics landmarks
 Lines and Planes of Norma lateralis
 Stability of landmarks
 Superimposition of Cephalometric radiographs
 Bibiliography.

INTRODUCTIONINTRODUCTION
Cephalometrics is the language in which the
poetry of orthodontic diagnosis and its planning
is written.
Cephalometrics includes measurements,
description and appraisal of the morphologic
configuration and growth changes in the skull
by ascertaining the dimensions of line angles
and planes between anthropometric land marks
established by physical anthropologists and
points selected by orthodontists.www.indiandentalacademy.com

HISTORICAL ASPECT.HISTORICAL ASPECT.
Cephalometry comes under the branch of
anthropometry with craniometry. There were the
physical anthropologists who firstly introduced the
lines or angles in measuring the face and
correlating them with each other.
In 1780,Camper probably the first to usefulness of
the angle formed by the intersection of a line from
the bone of the nose to external auditory meatus
with a line tangent to facial profile.

The Dutchman, Vanloon is said to be the
first introducing anthropology in to
orthodontics. He made a plaster cast of the
entire face in which, models of the dentition
were inserted oriented with help of cubus
craniophorus (Device used by
anthropologists to study the crania orbital
plane) by P.Simon in 1922.
Milo Hellmam, was also one of the first great
orthodontists of the time. He adapted the
technique of physical anthropology to
orthodontic research.

 Roentgen’s discovery of X-rays in 1895
opened new doors in finding the answers to the
questions that other relatively limited technique
were unable to answer.
 In 1921 Pacini published a paper entitled
“Roentgen Ray Anthropometry of the skull” in
which he described a technique of producing and
measuring radiographs of both dried skull and
living patients.
 Pacini identified certain land marks on x-rays-
Go,Pog, Na and ANS. The estimated centre of
sella tumecia, Top of the EAM- Akoustion.

 In 1931 the methodology cephalometric
radiography came to full fruition when
Broadbent(USA) and Hofrath in Germany
simultaneously published method to obtain
standardized head radiographs. The
principle involved was a constant focal spot
to object distance (5ft.) and preferably a
constant object to film distance..
 In 1968 Bjork designed and X-ray
cephalostat in which patients head position
was highly reproducible.

More recently in 1988 a multiprojection
cephalometer developed by Solow & Kreiborg.
This apparatus featured improved control of head
position and digital exposure control as well as
number of technical operative innovations.
 Dr. Robert M.Ricketts first introduced the
computer in Orthodontic Cephalometry,
Computerized Cephalometry has number of
advantages over conventional one of being less
time consuming, lesser chances of error and easy
storage and retrieval of cephalometric values and
tracings.

ADVANTAGES &LIMITATIONSADVANTAGES &LIMITATIONS
 Study Casts – information of dental structures
 Facial photographs – surface features
 But only cephalometric images yield accurate
information on the spatial relationships between
surface and deep structure.
 This is relatively non- invasive, non-destructive, high
information yield at relatively low physiologic cost.
It rendered serial assessment of growth possible and
permitted investigators to monitor the ongoing
procedures of treatment and growth in vitro.

Important in orthodontic growth
analysis,diagnosis, treatment planning,
monitoring of therapy, and evaluation of
final treatment outcome.
Cephalographs provide additional
radiographic information mediolaterally,
which is particularly useful for presurgical
and asymmetric growth evaluation.

LIMITATIONSLIMITATIONS
 1. Relation rather than absolute
 2. Radiation exposure
 3. Absence of anatomical references whose shape
and location remain constant through time.
 4. Lack of sufficient standardization in current
image acquisition and measurement procedures.
 5. Cephalograms are 2 dimensional pictures of 3
dimensional objects. It leads to different projective
displacement of anatomical structure lying at
different parts.

RADIOGRAPHIC CEPHALOMETRICRADIOGRAPHIC CEPHALOMETRIC
TECHNIQUETECHNIQUE
The basic components of the equipment for
producing a lateral cephalometric are:
1. An X-ray apparatus
2. An image receptor system
3. A cephalostat.
X-ray Apparatus comprises of X-rays tube,
transformers, filters, collimators, and a coolant
system, all encased in the machine’s housing.

Image Receptor system ; Extra oral
projection like lateral ceph. requires a
complex image receptor system that consists
of an extra oral film, intensifying screens, a
cassette, a grid and soft tissue shield.
 Extra oral film is a screen film size ranging
from 8x10 inches to 10x12 inches. Basic
component of the film are an emulsion of
silver halide crystals suspected in a gelatin
frame work and a transparent blue- tinted
cellulose acetate that serves as a base.

Silver halide exposed Metallic silver film Visible and
crystals to x-rays processing permanent image
Latent image
Intensifying Screens: Phosphorescent crystals such
as Ca tungstate + Barium lead sulfate coated
onto a plastic support.
- Exposed to X-ray beam- emit fluorescent light- can
be recorded.
- Decreases patient exposure dose.
- - Increases contrast by intensifying the photographic
effect.

Grid: - To prevent the fogging. Comprising
alternate Radio-opaque + Radiolucent.
strips and placed between subject and film.
R.O. of Lead foil – act as absorber
R.L. of Plastic – allow the primary beam to
pass through .
Soft Tissue Shield: - is an aluminium
wedge that is placed over the cassette
inorder to act as a filter and reduce over
penetration of the X-rays into the soft tissue
profile.

 Cephalostat:- As described by Broadbent (1931).
 -Patient’s head is fixed by 2 ear rods that are
inserted into the ear holes so that the upper border
of the ear holes rest on the upper part of the ear
rods.
- -Head is centered in the cephalostat, is oriented
with the FHP parallel to floor and MSP vertical
and parallel to the cassette.
 - Standardized FHP is achieved by placing the
infraorbital pointer at the patient’s orbit and then
adjusting the head until the infra-orbital pointer
and ear rods are at the same level.
 - The upper part of face is supported by forehead
clamp positioned at nasion.

The conventional use of 2 ear rods to stabilize the
head in radiographic Cephalometry is based on the
assumption that the transmeatal axis of human is
perpendicular to mid-sagittal plane.
Actually, asymmetry is a general characteristic and
the relationship of the left and right ears in their
vertical and horizontal relation to each other
which is frequently asymmetric.
In these instances the insertion of ear-rods will
obviously result in vertical and/or horizontal
rotation of the head, which introduces a deficient
and misleading image. So only the left ear-rods
should be used in radiographic Cephalometry both
for lateral and particular for the frontal projection.

Natural head posture (NHP)
 The concept of NHP in the living subjects
was introduced in Orthodontics in 1950s.
Broca, an anatomist described NHP as the
position of the head attained when an
individual stands with the visual axis in the
horizontal plane.
 The patient should be standing up and
should look into the reflection of his or her
own eyes in a mirror directly ahead in the
middle of the cephalostat (Sollow and Tallgren
in 1971).

 Natural head position is a standardized and
reproducible orientation of head in space when one
focusing on distant point at eye level.
 - Focus film distance is usually 5 ft.
 - Teeth are in C.O. and lips in response.
 - Usually left side of the head faces the cassettes.
 - For the PA projection (Caldweld projection).The
bilateral ear rods are rotated 90 degree relative to
their orientation during the lateral projection
procedure.
 A lead marker should be attached to one of the upper
corners of the cassette to indicate the patient’s right
or left side

Film Processing:-
 In general manual processing of the
cephalometric-radiographs at 70o
f requires 5
minutes development cycle followed by a
30-seconds rinse and a 10 minute fixation
cycle. At least a 20 minute washing cycle is
necessary after that. If not rinse thoroughly
the fixer solution will continue to act on
film after processing and eventually tint or
discolour the image.
Automatic processors commonly produce a
dry, processed film in about 5min.

 Quality of the Radiographs: Cephalometric
Image:-
 Image quality is a major factor influencing the
accuracy of cephalometric analysis. An acceptable
diagnostic radiograph is considered in the light of
2 groups of characteristics:
 - Visual characteristics – Density
 – Contrast
 -Geometric Characteristics-Image unsharpness
 –Image magnification
 –Shape Distortion.

 A. Density – is the degree of blackness of the
image. 2 main factors that control the radiographic
density are:
 -The exposure technique : Exposure factors related
to density are expressed as an equation.
 Density = Kvp x mA x S/D
 -The processing procedure : Density is directly
proportional to the temperature of the developing
solution and size of silver halide crystals (larger
grain size- high speed film)
 B. Contrast - is the difference in densities
between adjacent areas. If the contrast is high
there will a short scale contrast and vice versa.

 Factors controlling the radiographs contrast
are:-
 Tube Voltage: When the voltage is low, contrast
will be high but there will be short scale contrast
and vice versa.
 Secondary or Scattered Radiation: Decreases
the contrast by producing film fog.
 Subject Contrast: Nature and properties of the
subject i.e. thickness, density, and atomic number.
 Processing Procedure: - Increases temperature –
Increased contrast.

Geometric Characteristics
 A. Image Unsharpness
 - Geometric –due to penumbra (fuzzy outline)
 - Motion
 - Materials –Grain size –Intensifying screens
 B. Image magnification : Enlargement of the actual size
of the object.
 - Greater the object – film distance greater is the
magnification . At 90mm object to film distance with a 5
feet anode-object distance enlargement is about 6% at a
distance of 130mm it will be 8.5%.
 - It is also noted that in any single plane of the head
that is at right angle to the central rays, the enlargement
is uniform through out. Rotation of head could cause
foreshortening of the images of objects on one side and
elongation of those on the other side.www.indiandentalacademy.com

 C. Shape Distortion: results in an image that does not
correspond proportionally to the subject.
 -It occurs as results of improper orientation of the
patients head in the cephalostat or improper alignment
of the film and central rays.
 - Usually the miliamperage setting does not exceed
10mA the kilovoltage is about 60-90 KV, exposure
time not more than 3 seconds.
 - An increases by 15 KV necessitates a halving of the
exposure time.
 Optimum temperature of developer and developing
time are 680
F and 5 minutes respectively.

 Protection from Radiation:-
 Protection measures that aim to minimize the exposure to
the patient include:-
 1.Utilization of a high speed film and intensifying screen
decreased dose of radiation decreased exposure time.
 2. Filtration of secondary radiation by an aluminium filter.
 3.Collimation by a diaphragm made of lead – optimum
beam size.
 4.Proper exposure technique and processing – to avoid
repetition.
 5.The patients wearing a lead apron in order to absorb
scattered radiation.
 - To avoid scattered radiation the operator should stand at
least 6 feet behind the tube or should preferably behind a
Pb protective barrier.www.indiandentalacademy.com

 Tracing Technique:-
 - One should become thoroughly familiar with the gross
anatomy of the face in particular the bony components of
the cranium and face, before any attempts are made to trace
a cephalometric head film.
 -It must be recognized that a 2-dimensional Cephalograms
represents a three dimensional object and that bilateral
structures will be projected on to the film. One should be
able to distinguish bilateral structures and traces them
independently, because left and right outlines will not be
perfectly superimposed in most instances due to facial
asymmetry, greater magnification of the image on the side
of the skull farthest from the film and imperfect positioning
of the cephalostat.

 - Bilateral structures are
first traced
independently. An
average is then drawn by
visual approximation,
which is represented by
a broken line.

Tracing Material:-
1.Lateral cephalogram (8x10inches) and
view box.
2.Acetate matte tracing paper.
3.A sharp 3H drawing pencil
4.Masking tape
5.A few sheets of black card board and a
hollow card board tube.
6.A protractor scale.

 General Consideration for Tracing:-
 - Cephalograms is placed on the view box with the
patient’s image facing to the right and tape the
four corners.
 -With a fine felt tipped black pen draw 3
registration crosses on the radiograph, two within
the cranium and one over the area of the cervical
vertebrae –allow for reorientation,for later
verification – if film is displace during tracing.
 -Next the tracing sheet is taped over the
radiograph with shiny side facing the radiograph,
3 registrations crosses, patients name, record No.
and age is recorded on the sheet.

Selective Viewing and Masking:-
1.The use of dense black paper to cover or
mask all portions of the film except the
immediate area being traced reduces eye
strain and allows for more accurate tracing
in “faded” areas.
2.Excess light may be cut further by
looking through a black paper cone.
3.Fine details may be revealed by lifting the
tracing paper from the film for an
unobstructed view of the section to be
studied.

STEPWISE TRACING TECHNIQUE
Section 1: Soft tissue profile, external
cranium , vertebra.
Section 2: Cranial base, internal border of
cranium, frontal sinus and ear rods.
Section 3: Maxilla and related structures
including nasal bone and PTM.
Section 4: The mandible.

ANATOMICAL LANDMARKS: THEANATOMICAL LANDMARKS: THE
GUIDE POSTS OFGUIDE POSTS OF
CEPHALOMETRICSCEPHALOMETRICS
1. Point F (constructed): This point approximates
the foramen caecum and represents the anatomic
anterior limit of the cranial base, constructed as
the point of intersection of a line perpendicular to
the SN plane from the point of crossing of the
images of the orbital roofs and the internal plate
of the frontal bone (cohen).

2. FMN: Front
maxillary nasal suture-
the most superior point
of the suture.
3. Na: the most
anterior point of the front
nasal suture in the
median plane.

1. 4.SE: Sphenoethmoidal
– the intersection of the
shadows of the greater
wing of the sphenoid
and the cranial floor.
 5.Sor: Supraorbitale –
the most anterior points
of the intersection of the
shadow of the roof of
the orbit and its lateral
contour

 6.RO: roof of orbit –
uppermost point on the
roof of the orbit.
 7.Ba: Basion – the median
point of the anterior
margin of the foramen
magnum.
 8.Bo: Bolton point- the
highest point in the
upward curvature of the
retrocondylar fossa.
 9.Op: opisthion: the
posterior edge of foramen
magnum.

 Cl (clinoidale) : the most
superior point on the
contour of the anterior
clinoid.
 Ptm: Pterygomaxillary
fissure- a bilateral
teardrop-shaped area of
radiolucency.
 S (Sella): Point
representing the midpoint
of the pituitary fossa (sella
turcica)

 Sc: midpoint of the
entrance to the sella.
 Si: floor of sella- the
lowermost point on
the internal contour of
the sella turcica.
 Sp: dorsum sella- the
most posterior point
on the internal contour
of the sella turcica.

 PO (Anatomic): Superior
point of the external
auditory meatus.
 Te (Temporale): The
intersection of the
shadows of the ethmoid
and the anterior wall of
the infratemporal fossa.
 A: Point A (or ss,
subspinale) – the point at
the deepest midline
concavity on the maxilla
between the anterior nasal
spine and prosthion

 ANS: anterior nasal spine
– tip of the bony anterior
nasal spine.
 APMax: anterior point for
determining the length of
the maxilla- this is
constructed by dropping a
perpendicular from point
A to the palatal plane.
 KR: the key ridge- the
lowermost point on the
contour of the shadow of
the anterior wall of the
intratemporal fossa.

Or: Orbitale – the
lowermost point in the
inferior margin of the
orbit, midpoint between
right and left images.
Pns: Posterior nasal spine.
Pr: Prosthion – the lowest
and most anterior point on
the alveolar portion of the
premaxilla in the median
plane, between the upper
central incisors

APMan : anterior landmark
for determining the length
of the mandible –
perpendicular dropped
from Pog to the
mandibular plane
(Rakosi).
Ar: Articulare – the point
of intersection of the
images of the posterior
border of the condylar
process of the mandible
and the inferior border of
the basal part of the
occipital bone.

 B : Point B (supramentale)- the
point at the deepest midline
concavity on the mandibular
symphysis between infradentale
and pogonion.
 Co, condylion (or cd): the most
superior point on the head of the
condylar head.
 Gn: Gnathion- most anteroinferior
point on the symphysis of the chin.
 Go: Gonion – constructed point
of intersection of the ramus plane
and the mandibular plane

 Id: Infradentale- the highest
and most anterior point on
the alveolar process in the
median plane between the
mandibular central incisors.
 Me: menton – the most
inferior midline point on the
mandibular symphysis.
 Pog : pogonion – the most
anterior point of the bony
chin in the symphysis .

SOFT TISSUE LANDMARKSSOFT TISSUE LANDMARKS
 G-glabella-the most
prominent point in the
midsagittal plane of
forehead.
 Ils-inferior labial
sulcus-the point of
greatest concavity in
the midline of the
lower lip between
labrale inferius and
menton.

 Li-labrale inferius-the
median point in the lower
margin of the lower
membranous lip.
 Ls-labrale superius-the
median point in the upper
margin of the upper
membranous lip
 Ms-menton soft tissue-the
contructed point of
intersection of a vertical
co-ordinate from menton
and the inferior soft tissue
contour of the chin.

 Ns-nasion soft tissue-point of
deepest concavity of the soft
tissue contour of the root of
the nose.
 Pn-pronasale-the mot
prominent point of the nose.
 Pos-pogonion soft tissue-the
most prominent point on the
soft tissue contour of the
chin.
 Sls-superior labial sulcus-the
point of greatest concavity in
the midline of the upper lip
between subnasale and
labrale superius

 Sn-subnasale-the point
where the lower border of
the nose meets the outer
contour of the upper lip.
 St-stomion-the midpoint
between stomion superius
and stomion inferious
 Sti-stomion inferious-the
highest point of the lower
lip.
 Sts- stomion superius-the
lowest point the upper lip.

Cephalometric landmarks ofCephalometric landmarks of
PharynxPharynx
 ANS-anterior nasal spine.
 APW-anterior pharyngeal
wall.
 Hy-hyoid.
 PNS-posterior nasal spine.
 PPW-posterior pharyngeal
wall.
 Pt-posterior point of
tongue.
 Ptm-pterygomaxillary
fissure.

 Spw-superior
pharyngeal wall.
 U- tip of uvula.
 Uo-point on the oral
side of soft palate.
 Up-point on the
pharyngeal side of the
soft palate.
 UT- upper point of the
tongue.

CEPALOMETRIC LANDMARKS OFCEPALOMETRIC LANDMARKS OF
CERVICAL VERTEBRAE.CERVICAL VERTEBRAE.
 Cv2ap- the apex of the
odontoid process of the 2nd
cervical vertebrae.
 Cv2ip- the most
inferoposterior point on the
body of the 2nd
cv.
 Cv2ia-the most inferoanterior
on the body of the 2nd
cv.
 Cv3sp-most superoposterior
point on the body of 3rd
cv.
 Cv3ip-the most
inferoposterior point on the
body of the 3rd
cv.

 Cv3sa-most superoanterior
point on the body of 3rd
cv.
 Cv3ia-the most inferoanterior
point on the body of the 3rd
cv.
 Cv4sp- most superoposterior
point on the body of 4th
cv.
 Cv4ip-the most inferoposterior
point on the body of the 4th
cv.
 Cv4sa- most superoanterior
point on the body of 4th
cv.
 Cv4ia- the most inferoanterior
point on the body of the 4th
cv.

 Cv5sp- most
superoposterior point on
the body of 5th
cv.
 Cv5ip-the most
inferoposterior point on
the body of the 5th
cv.
 Cv5sa- most
superoanterior point on
the body of 5th
cv.
 Cv5ip- the most
inferoanterior point on
the body of the 5th
cv.

 Cv6sp-most
superoposterior point on
the body of 6th
cv.
 Cv6ip-the most
inferoposterior point on
the body of the 6th
cv.
 Cv6sa- most
superoanterior point on
the body of 6th
cv.
 Cv6ia-the most
inferoanterior point on
the body of the 6th
cv.

LINES AND PLANES OFLINES AND PLANES OF
NORMA LATERALISNORMA LATERALIS
 Broca’s line : (1875) was devised as an attempt to
improve on Blumenbach’s plane. It extends from
the Prosthion to the lowermost point of the
occipital condyle.
 His plane: (1874) runs from acanthion to
opisthion. Useful in the study of skull specimens.
 Camper’s Line : Defined as the extending from
Ac (tip of the ANS) to the center of the external
auditory meatus.

 Von Baer’s line: Anthropological in origin follows
the anteroposteroir axis of the zygomatic arch tangent
to its uppermost conversity.
 Von Ihering’s line: An old of anthropological origins.
Extends from orbitale to the center of the external
auditory meatus instead of porion.
 Blumenbasch’s plane:- resting horizontal plane,
plane formed as the skull minus the mandible. This
usually entails the skull.
 Broadbent’s line: was devised in the late 1920s by
B. Holly Broadbent S-N reference baseline. It runs of
course from sella to nasion.
 Broadbent Bolton line :- Runs from Bolton points to
nasion.

 Decoster’s line:-Only line that is not a linear connection
of two points extends from the internal plate of the
frontal bone down through the roof of the cribriform
plate to the anterior portion of sella turcica.
 Frankfort Horizontal Plane (FH):- Another one of the
oldest and most prestigious planes of cephalometrics. It
may be visualized on the living individual, the dried
skull and the lateral roentgenocephalogram of the living
patient as well. The line runs from orbitale to porion.
 Palatal Plane: from ANS to PNS.
 Huxley’s line: Runs from nasion to basion referred to
as nasion basion line. quite popular in the computerized
cephalometric fields as reference line.

 Margolis line :- This lines runs from nasion to the spheno-
occipital synchondrosis.
 Mandibular plane :- There are four different mandibular planes
used. Tweed and Rickett’s define the mandibular plane as a
straight line tangent to the lowermost border to the mandible .
Downs one of the founding fathers of clinical cephalometric
analysis define this plane as a the line joining gonion to menton.
Steiner defined is as the line joining gonion and ganthion .
Bimlers’s line M-No (menton to antegonial notch).
 Occlusal Plane :- There are three occlusal planes. The line
joining the midpoint of the overlap of the mesiobuccal cusps of the
upper and lower first molars with the point bisecting the overbite
of the incisors used by both Downs and Steiner . Ricketts used
functional occlusal plane which is a line joining the midpoint of
the overlap of the mesiobuccal cusps of the first molars and the
buccal cusps of the premolars or the deciduous molars. Third plane
is the line joining the midsection of the molar cusps to the tip of
the upper incisor.

 Orbital plane:- Plane perpendicular to the
Frankfort Horizontal plane at orbtiale.
 Ramus line : line tangent to the posterior border of
the ramus of the mandible.
 Y-axis : Line first devised by Downs sella to
gnathion. Its angulation with the Frankfort
Horizontal is used as an indication of the general
direction of growth .
 Rickett’s esthetic line - Soft tissue profile
reference lines. Extends from the soft tissues tip of
the nose to the most anterior portion of the profile
of the soft tissue chin.

Holdaways line : this line also referred to as
the harmony line and is a soft tissue profile
assessment reference line. It is a specific for
determination of the balance and harmony
of the lower lip. Vermilion border of the
lower lip should fall within 1mm of a line
drawn from the unstrained soft tissue chin
to the vermilion border of the upper lip.

STABILITY OF LANDMARKSSTABILITY OF LANDMARKS
 Sella: We know that during growth distance
increases between sella and some anterior points
such as nasion and also distance increases between
sella and posterior points such as basion.
 But what happens to the sella?
 Dr R.A.Latham interpreted his findings as
indicative that growth continues at the sphenoidal
surface of the synchondrosis and is accompanied
by an upward and backward movement of the sella
due to remodeling as the size of the pituitary gland
itself also grows in volume.

 Dr Melsen performed studies and found that sella
moves on the average 2mm downward and
backward in relation to the tuberculum sella.
 Nasion; It is the most anterior point of the
frontnasal suture.
 There are two basic types of sutures.
 Edge to Edge type: Exhibit growth that is
correlated with the physical separation of the
bones.
 Overlapping type: Growth does not necessarily
imply bony separation but does imply a physical
relocation of the suture itself relative to these
respective bones (FNS is of overlapping variety).

ANS and A point : Due to overall
downward and forward growth of the
maxilla landmarks as ANS and A point
follow a similar pattern of movement
relative to cranial bone . The anterior and
posterior nasal spines usually descend in
unison thus keeping the palatal plane
parallel to the former positions throughout
growth.

SUPERIMPOSITION OFSUPERIMPOSITION OF
CEPHALOMETRIC RADIOGRAPHSCEPHALOMETRIC RADIOGRAPHS
 A cephalometric superimposition is an
analysis of lateral Cephalograms of the same
patient taken a different time. These
superimpositions are used to evaluate patient’s
growth pattern between different ages and to
evaluate changes in the dentoalveolar and basal
relationships after a course of orthodontic or
surgical treatment.

When evaluating the dentofacial changes that
occur as a results of growth or Tt, orthodontists
are interested in observing specific areas of
alterations.As a results cephalometric
superimpositions involve the evaluations of :
- Changes in the overall face.
- Changes in the maxilla and its dentition
- Amount and direction of condylar growth
- Mandibular rotations

 Evaluation of the overall changes in the face
 Cranial structures have traditionally been used
for these superimpositions base on the fact that
both the neurocranium and its related structures
achieve most of their growth potential at a
relatively early age.
 Superimposition Methods
 - Broadbent triangle (Na-S-Bo) and its registration
point R were among the first structures used for
superimposition -2 tracings are registered at R
points keeping Bo-Na plane parallel.
 - S-N line ; 2 tracings are oriented on the S-N line
with registration at sella.

 -Basion Horizontal (coben 1955, 1986): Serial
tracings are registered at basion and oriented with
the SN planes. The line form basion drawn
parallel to the original FH or the mean FH of the
several radiographs establishes the contents SN-
FH relationship and the basion horizontal plane of
the series.
 -Ba-N Plane: it was suggested by Rickett’s et al
(1979). Superimposition area was Ba-Na line with
registration CC point where the Ba-Na plane and
facial axis intersect.
 FHP: on Frankfort horizontal with portion as the
point of anteroposterior registration.

Drawbacks:
Landmarks used to superimpose the tracings are
not stable during growth.
- Sella moves upward and forward.
- Bolton point frequently obscured by the mastoid
process in the teenage years.
- Position of Basion is influenced by the
remodeling processes on the surface of the clivus
and on the anterior border of the foramen
magnum as well as by displacement of the
occipital bone (Growth at speheno-occipital
synchondrosis) Melsen 1974.

 -This superimposition showed
 1. Anterior portion of the face moves away form
the porion (But we know that porion and other
portions of the posterior face as condyle, gonion,
body of ramus, move posteriorly during growth )
 2. Permanent first maxillary molar erupt past the
level of the deciduous occlusal plane
 3. Mandibular 1st
molar appear stationary with
respect to movement along the vertical plane
relative to Mandibular border.
 - These structures have a low degree of validity,
although they have a high degree of
reproducibility.

 Reference structures for overall Face super
Impositions
 Nelson’s (1960) cephalometric study and
Melsen’s (1974) histological investigation
identified various bony surfaces that undergo
relatively minimal alterations during growth and
has been called stable structures or reference
structures.
This method of overall superimposition presents a
high degree of validity and a medium to high
degree of reproducibility.

Reference structures for overall Face superReference structures for overall Face super
ImpositionsImpositions
 1.Anterior wall of sella
turcia.
 2.Contour of the cribriform
plate of the ethmoid bone.
 3.Details of the trabecular
system in the ethmoid cells.
 4.Median border of the
orbital roof.
 5.The plane of the sphenoid
base (planum sphenoidale).

 Maxillary Superimposition
 The purpose is to evaluate the movement of the
maxillary teeth in relation to the basal parts of the
maxilla. A number of methods have been suggested.
 1. Along the palatal plane at ANS
 2. Along the nasal floor at the anterior surface of maxilla
 3. Along the palatal plane registered at PTM fissure
(Moore)
 4. On the outline of the infra temporal fossa and the
posterior portion of the hard palate (Riedel).
 5. On the best fit of the internal palatal structures
(McNamara)
 6. In the metallic implants (Bjork and Skieller )
 7. On the anterior surface of the zygomatic pr. of the mx.
(Bjork and skieller).www.indiandentalacademy.com

 1. Along the palatal
plane at ANS
2. Along the nasal
floor at the anterior
surface of maxilla

 3. Along the palatal
plane registered at
PTM fissure
(Moore)
 4. On the outline of
the infratemporal
fossa and the
posterior portion of
the hard palate
(Riedel).

 Draw backs
 - Palatal shelf undergo continuous remodeling
hard palate undergoes continuous resorption on its
nasal surface and apposition on the oral side.
 - ANS and PNS both undergo significant antero-
post remodeling and ANS showed twice as much
vertical displacement as PNS.
 Anterior contour of the zygomatic process of the
maxilla shows relative stability after the age of 8
but it is characterized by double structures which
makes it difficult to identify accurately and hence
to trace the construction line.

 Where to superimpose in the Maxilla
 Two methods are recommended
 - Structural method
 - Best fit method
 - Structural Method : Recommended when the details of the
zygomatic pr . of the mx are clearly visible in both Cephalograms.
 -Tracing are superimposed on the construction line to know the
amount of apposition at the floor of orbit. Move the
superimposition so that the amount of resorption at the nasal floor
is equal to the apposition at the floor of the orbit.
 - Amount of mx rotation can be estimated from the angle formed
by 2N-S lines
 Medium to high degree of validity and low degree of
reproducibility.

 Modified Best Fit method
 - If the details of the zygomatic process are not clearly
identifiable .
 - Superimpositions are made on the nasal and palatal
surface of the hard palate in an area that is not
significantly influenced by incisor movement.
 - Second tracing is adjusted over first have the following
structures arranged in a best fit alignment .
 - Contour of the oral part of the palate.
 - Contour of the nasal floor.
 - Entrance of the incisal canal.
 Molar eruption are underestimated by 30% and incisor
eruption by 50% (As downward remodeling of nasal
floor is not accounted). So it has low validity and a
medium degree of reproducibility

 Mandibular Superimpositions
 - To evaluate the movements of the mandibular
teeth in relation to the basal parts of the mandible.
 - A number of areas have been suggested
including the lower border of mandible a tangent
to lower border of mandible constructed lower
border of mandible by joining Me and Go.
 - These methods are not accurate as significant
remodeling occurs at the lower border of md.
 - Low degree of validity high degree of
reproducibility.

Stable Structures for Superimposition on theStable Structures for Superimposition on the
MandibleMandible
Bjork and Skieller (1983) form their
implant studies indicated these
structures as relatively stable:
 1. Anterior contour of the chin
 2. The inner contour of the cortical
plates at the inferior border of the
symphysis and any distinct trabecular
structure in the lower part of the
symphysis.
 3.Posteriorly the contours of the
mandibular canal and in the lower
contour of a mineralized molar germ.
 Medium to high degree of validity
and medium to high degree of
reproducibility.

ReferencesReferences
1. Athanasios E Athanasiou; Orthodontic Cephalometry; Mosby-
Wolfe,1 :11-20,46-60,107-123: 1995.
2. Alexander Jacobson; Radiography Cephalometry; Quintessence
Co: 39-62,165-173,175-184: 1995.
3. Margherita Santoro,Karim J.,Thomas.J.C. ;Accuracy of digital
and analogue cephalometric measurements assessed with the
sandwich technique; Am J Orthod Dento Orthop: 129:345-351:
2006.
4. Historical Aspects of Roentogenographic Cephalometry. Am J
Orthod Dento Orthop: 129: 2: 2006.

5. T.M.Graber,Implementation of the
Roentogenographic cephalometric Am J Orthod
Dento Orthop:12:1968.
6. C.C.Steiner,Clinical Cephalometrics for you and
me: Am J Orthod Dento Orthop: 10: 1983.

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