Cephalometrics in orthodontics/prosthodontic courses

CEPHALOMETRICSCEPHALOMETRICS
ININ
ORTHODONTICSORTHODONTICS
INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMY
Leader in continuing Dental EducationLeader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 IntroductionIntroduction
 Historical aspectHistorical aspect
 Advantages and limitationsAdvantages and limitations
 Radiographic cephalometric techniqueRadiographic cephalometric technique
 Quality of the radiographsQuality of the radiographs
 Protection from radiationProtection from radiation
 Tracing TechniqueTracing Technique
 Cephalometrics landmarksCephalometrics landmarks
 Lines and Planes of Norma lateralisLines and Planes of Norma lateralis
 Stability of landmarksStability of landmarks
 Superimposition of Cephalometric radiographsSuperimposition of Cephalometric radiographs
 Bibiliography.Bibiliography.

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

HISTORICAL ASPECT.HISTORICAL ASPECT.
 Cephalometry comes under the branch of anthropometryCephalometry comes under the branch of anthropometry
with craniometry. There were the physical anthropologistswith craniometry. There were the physical anthropologists
who firstly introduced the lines or angles in measuring thewho firstly introduced the lines or angles in measuring the
face and correlating them with each other.face and correlating them with each other.
 In 1780,Camper probably the first to usefulness of theIn 1780,Camper probably the first to usefulness of the
angle formed by the intersection of a line from the boneangle formed by the intersection of a line from the bone
of the nose to external auditory meatus with a line tangentof the nose to external auditory meatus with a line tangent
to facial profile.to facial profile.
 Spix (1815) proposed to modify the camper horizontal bySpix (1815) proposed to modify the camper horizontal by
drawing a line from prosthion tangent to the occipitaldrawing a line from prosthion tangent to the occipital
condyle.condyle.

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

 The Dutchman, Vanloon(1915) is said to beThe Dutchman, Vanloon(1915) is said to be
the first introducing anthropology in tothe first introducing anthropology in to
orthodontics. He made a plaster cast of theorthodontics. He made a plaster cast of the
entire face in which, models of the dentitionentire face in which, models of the dentition
were inserted oriented with help of cubuswere inserted oriented with help of cubus
craniophorus (Device used bycraniophorus (Device used by
anthropologists to study the crania orbitalanthropologists to study the crania orbital
plane) by P.Simon in 1922.plane) by P.Simon in 1922.
 In 1929, the world’s anthropologists metIn 1929, the world’s anthropologists met
and agreed on the definition of theand agreed on the definition of the
Frankfort horizontal plane.Frankfort horizontal plane.

 In 1931 the methodology cephalometricIn 1931 the methodology cephalometric
radiography came to full fruition whenradiography came to full fruition when
Broadbent(USA) and Hofrath in GermanyBroadbent(USA) and Hofrath in Germany
simultaneously published method to obtainsimultaneously published method to obtain
standardized head radiographs. The principlestandardized head radiographs. The principle
involved was a constant focal spot to objectinvolved was a constant focal spot to object
distance (5ft.) and preferably a constant object todistance (5ft.) and preferably a constant object to
film distance.film distance.
 Lucien de coster of belgium (1939) was the first toLucien de coster of belgium (1939) was the first to
publish an analysis based on proportionalpublish an analysis based on proportional
relationship in the face conforming to principlesrelationship in the face conforming to principles
used in antiquity.used in antiquity.
 Herbert I Margolis (1943) was first to relateHerbert I Margolis (1943) was first to relate
mandibular incisor to the lower border ofmandibular incisor to the lower border of
mandiblemandible

 James A. McNanara’s (1943) own measurement toJames A. McNanara’s (1943) own measurement to
indicate tooth and jaw positions more specifically,indicate tooth and jaw positions more specifically,
and relates the jaws in A-P position to verticaland relates the jaws in A-P position to vertical
 William B.Downs (1947) he completed a landmarkWilliam B.Downs (1947) he completed a landmark
study “variations in facial relationship : theirstudy “variations in facial relationship : their
significance in treatment and prognosis” which comesignificance in treatment and prognosis” which come
to known as Downs analysisto known as Downs analysis
 Richard A. Riedel (1922-1994) introduced one of theRichard A. Riedel (1922-1994) introduced one of the
most widely accepted diagnostic cephalometricmost widely accepted diagnostic cephalometric
measurements in use: ANB anglemeasurements in use: ANB angle

 Cecil C. Steiner (1953) published his analysis. ThatCecil C. Steiner (1953) published his analysis. That
offer specific guide for the use of cephalometricoffer specific guide for the use of cephalometric
measurements in treatment planing ,based on whatmeasurements in treatment planing ,based on what
compromises in incisor positions would be necessarycompromises in incisor positions would be necessary
to achieve normal occlusion when the ANB angleto achieve normal occlusion when the ANB angle
was not idealwas not ideal
 Tweed (1954), he constructed a triangle formed byTweed (1954), he constructed a triangle formed by
lower central incisor, mandibular plane, and frankfortlower central incisor, mandibular plane, and frankfort
horizontal plane.horizontal plane.
 In 1968 Bjork designed and X-ray cephalostat inIn 1968 Bjork designed and X-ray cephalostat in
which patients head position was highly reproducible.which patients head position was highly reproducible.

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

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

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

LIMITATIONSLIMITATIONS
 1. Relation rather than absolute1. Relation rather than absolute
 2. Radiation exposure2. Radiation exposure
 3. Absence of anatomical references whose shape3. Absence of anatomical references whose shape
and location remain constant through time.and location remain constant through time.
 4. Lack of sufficient standardization in current4. Lack of sufficient standardization in current
image acquisition and measurement procedures.image acquisition and measurement procedures.
 5. Cephalograms are 2 dimensional pictures of 35. Cephalograms are 2 dimensional pictures of 3
dimensional objects. It leads to different projectivedimensional objects. It leads to different projective
displacement of anatomical structure lying atdisplacement of anatomical structure lying at
different parts.different parts.

RADIOGRAPHIC CEPHALOMETRICRADIOGRAPHIC CEPHALOMETRIC
TECHNIQUETECHNIQUE
 The basic components of the equipment forThe basic components of the equipment for
producing a lateral cephalometric are:producing a lateral cephalometric are:
 1. An X-ray apparatus1. An X-ray apparatus
 2. An image receptor system2. An image receptor system
 3. A cephalostat.3. A cephalostat.

X-ray Apparatus:-X-ray Apparatus:-
comprises of X-rays tube, transformers, filters,comprises of X-rays tube, transformers, filters,
collimators, and a coolant system, all encased incollimators, and a coolant system, all encased in
the machine’s housing.the machine’s housing.
 The three basic elements that generate the X- raysThe three basic elements that generate the X- rays
a. a cathodea. a cathode
b. an anodeb. an anode
c. the electrical power supplyc. the electrical power supply
a. cathode:-a. cathode:-
is a tungsten filament surrounded by ais a tungsten filament surrounded by a
molybdenum. And serves as a source of electrons.molybdenum. And serves as a source of electrons.

b. an anode :-b. an anode :-
 consist of a tungsten target embedded in a copperconsist of a tungsten target embedded in a copper
stem. The purpose of the target in an x ray tube is tostem. The purpose of the target in an x ray tube is to
convert the kinetic energy of the electrons generatedconvert the kinetic energy of the electrons generated
from the filament in to x ray photons. Less than 1 % offrom the filament in to x ray photons. Less than 1 % of
the electron kinetic energy is converted to the x raysthe electron kinetic energy is converted to the x rays
photons.photons.
 the size of the focal spot , which determines imagethe size of the focal spot , which determines image
quality. The target face in the x ray tube is oriented atquality. The target face in the x ray tube is oriented at
an angle of 15 to 20an angle of 15 to 2000 to the cathode .to the cathode .
 the size or area of the effective focal spot created by thethe size or area of the effective focal spot created by the
inclined target is between 1x1 mminclined target is between 1x1 mm22 and 1x2 mmand 1x2 mm22 ..

 the low- energy photons are filtered out by means of anthe low- energy photons are filtered out by means of an
aluminium filteraluminium filter
 The divergent x ray beam then passes through a leadThe divergent x ray beam then passes through a lead
diaphragm that fits over the opening of the machinediaphragm that fits over the opening of the machine
housing and determine the beam’s size and shape.housing and determine the beam’s size and shape.
 Only x ray with sufficient penetrating power areOnly x ray with sufficient penetrating power are
allowed to reach the patientallowed to reach the patient
c. the electric power supply :-c. the electric power supply :-
the primary function of the power supply of an x raythe primary function of the power supply of an x ray
machine are tomachine are to
1. provide a low voltage current to heat the x ray tube1. provide a low voltage current to heat the x ray tube
filament by use of an step- down transformerfilament by use of an step- down transformer
2. generate a high potential diff. between the anode2. generate a high potential diff. between the anode
and cathode by use of a high- voltage transformerand cathode by use of a high- voltage transformer

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

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

 Grid:Grid: -- To prevent the fogging. ComprisingTo prevent the fogging. Comprising
alternate Radio-opaque (usually lead) andalternate Radio-opaque (usually lead) and
strips of radiolucent material (often plastic)strips of radiolucent material (often plastic)
and paced between subject and film.and paced between subject and film.
 R.O. of Lead foil – act as absorberR.O. of Lead foil – act as absorber
 R.L. of Plastic – allow the primary beam toR.L. of Plastic – allow the primary beam to
pass through .pass through .
 Soft Tissue ShieldSoft Tissue Shield: -: - is an aluminiumis an aluminium
wedge that is placed over the cassettewedge that is placed over the cassette
inorder to act as a filter and reduce overinorder to act as a filter and reduce over
penetration of the X-rays into the soft tissuepenetration of the X-rays into the soft tissue
profile.profile.

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

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

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

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

Film Processing:-Film Processing:-
 In general manual processing of theIn general manual processing of the
cephalometric-radiographs at 68cephalometric-radiographs at 68oo
f requires 5f requires 5
minutes development cycle followed by aminutes development cycle followed by a
30-seconds rinse and a 10 minute fixation30-seconds rinse and a 10 minute fixation
cycle. At least a 20 minute washing cycle iscycle. At least a 20 minute washing cycle is
necessary after that. If not rinse thoroughlynecessary after that. If not rinse thoroughly
the fixer solution will continue to act onthe fixer solution will continue to act on
film after processing and eventually tint orfilm after processing and eventually tint or
discolour the image.discolour the image.
 Automatic processors commonly produce aAutomatic processors commonly produce a
dry, processed film in about 4 to 6 min.dry, processed film in about 4 to 6 min.

Quality of the Radiographs: CephalometricQuality of the Radiographs: Cephalometric
Image:-Image:-
 Image quality is a major factor influencing theImage quality is a major factor influencing the
accuracy of cephalometric analysis. An acceptableaccuracy of cephalometric analysis. An acceptable
diagnostic radiograph is considered in the light ofdiagnostic radiograph is considered in the light of
2 groups of characteristics:2 groups of characteristics:
Visual characteristicsVisual characteristics
 DensityDensity
 ContrastContrast
Geometric CharacteristicsGeometric Characteristics
 Image unsharpnessImage unsharpness
 Image magnificationImage magnification
 Shape Distortion.Shape Distortion.

A.A. DensityDensity –– is the degree of blackness of the image.is the degree of blackness of the image.
2 main factors that control the radiographic2 main factors that control the radiographic
density are:density are:
The exposure techniqueThe exposure technique : Exposure factors related to: Exposure factors related to
density are expressed as an equation.density are expressed as an equation.
Density = Kvp x mA x S/DDensity = Kvp x mA x S/D
The processing procedureThe processing procedure : Density is directly: Density is directly
proportional to the temperature of the developingproportional to the temperature of the developing
solution and size of silver halide crystals (largersolution and size of silver halide crystals (larger
grain size- high speed film)grain size- high speed film)
B.B.Contrast -Contrast - is the difference in densities betweenis the difference in densities between
adjacent areas. If the contrast is high there will aadjacent areas. If the contrast is high there will a
short scale contrast and vice versa.short scale contrast and vice versa.

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

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

C.C. Shape Distortion:Shape Distortion: results in an image that does notresults in an image that does not
correspond proportionally to the subject.correspond proportionally to the subject.
 It occurs as results of improper orientation of theIt occurs as results of improper orientation of the
patients head in the cephalostat or improper alignmentpatients head in the cephalostat or improper alignment
of the film and central rays.of the film and central rays.
 Usually the miliamperage setting does not exceedUsually the miliamperage setting does not exceed
10mA the kilovoltage is about 60-90 KV, exposure10mA the kilovoltage is about 60-90 KV, exposure
time not more than 3 seconds.time not more than 3 seconds.
 An increases by 15 KV necessitates to decrease theAn increases by 15 KV necessitates to decrease the
exposure time to half.exposure time to half.
 Optimum temperature of developer and developingOptimum temperature of developer and developing
time are 68time are 6800
F and 5 minutes respectively.F and 5 minutes respectively.

Protection from Radiation:-Protection from Radiation:-
 Protection measures that aim to minimize theProtection measures that aim to minimize the
exposure to the patient include:-exposure to the patient include:-
1.Utilization of a high speed film (D,E) and1.Utilization of a high speed film (D,E) and
intensifying screen decreased dose of radiationintensifying screen decreased dose of radiation
decreased exposure time.decreased exposure time.
2. Filtration of secondary radiation by an aluminium2. Filtration of secondary radiation by an aluminium
filter.filter.
3.Collimation by a diaphragm made of lead –3.Collimation by a diaphragm made of lead –
optimum beam size.optimum beam size.
4.Proper exposure technique and processing – to4.Proper exposure technique and processing – to
avoid repetition.avoid repetition.

5.The patients wearing a lead apron in order to5.The patients wearing a lead apron in order to
absorb scattered radiation.absorb scattered radiation.
To avoid scattered radiation the operator shouldTo avoid scattered radiation the operator should
stand at least 6 feet from the patient, at anstand at least 6 feet from the patient, at an
angle of 90 to 135angle of 90 to 13500 to the central ray of x- rayto the central ray of x- ray
beam or should preferably behind a Pbbeam or should preferably behind a Pb
protective barrier.protective barrier.

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

 - Bilateral structures are- Bilateral structures are
first tracedfirst traced
independently. Anindependently. An
average is then drawn byaverage is then drawn by
visual approximation,visual approximation,
which is represented bywhich is represented by
a broken line.a broken line.

Tracing Material:-Tracing Material:-
1. Lateral cephalogram (8x10inches) and view box.1. Lateral cephalogram (8x10inches) and view box.
2. Acetate matte tracing paper.2. Acetate matte tracing paper.
3. A sharp 3H drawing pencil3. A sharp 3H drawing pencil
4. Masking tape4. Masking tape
5. A few sheets of black card board and a hollow5. A few sheets of black card board and a hollow
card board tube.card board tube.
6. A protractor scale.6. A protractor scale.
7. Dental casts trimmed to maximal intercuspidation7. Dental casts trimmed to maximal intercuspidation
of the teeth in occlusionof the teeth in occlusion
8. Pencil sharpener and an eraser8. Pencil sharpener and an eraser

General Consideration for Tracing:-General Consideration for Tracing:-
 Cephalogram is placed on the view box with theCephalogram is placed on the view box with the
patient’s image facing to the right and tape thepatient’s image facing to the right and tape the
four corners.four corners.
 With a fine felt tipped black pen draw 3With a fine felt tipped black pen draw 3
registration crosses on the radiograph, two withinregistration crosses on the radiograph, two within
the cranium and one over the area of the cervicalthe cranium and one over the area of the cervical
vertebrae –allow for reorientation,for latervertebrae –allow for reorientation,for later
verification – if film is displace during tracing.verification – if film is displace during tracing.
 Next the tracing sheet is taped over the radiographNext the tracing sheet is taped over the radiograph
with shiny side facing the radiograph, 3with shiny side facing the radiograph, 3
registrations crosses, patients name, record No.registrations crosses, patients name, record No.
and age in years and months, date theand age in years and months, date the
cephalogram was taken is recorded on the sheet.cephalogram was taken is recorded on the sheet.

Selective Viewing and Masking:-Selective Viewing and Masking:-
1.The use of dense black paper to cover or1.The use of dense black paper to cover or
mask all portions of the film except themask all portions of the film except the
immediate area being traced reduces eyeimmediate area being traced reduces eye
strain and allows for more accurate tracingstrain and allows for more accurate tracing
in “faded” areas.in “faded” areas.
2.Excess light may be cut further by looking2.Excess light may be cut further by looking
through a black paper cone.through a black paper cone.
3.Fine details may be revealed by lifting the3.Fine details may be revealed by lifting the
tracing paper from the film for antracing paper from the film for an
unobstructed view of the section to beunobstructed view of the section to be
studied.studied.

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

ANATOMICAL LANDMARKS:ANATOMICAL LANDMARKS:
 1. Point F1. Point F (constructed):(constructed): This point approximates theThis point approximates the
foramen caecum and represents the anatomic anteriorforamen caecum and represents the anatomic anterior
limit of the cranial base, constructed as the point oflimit of the cranial base, constructed as the point of
intersection of a line perpendicular to the SN plane fromintersection of a line perpendicular to the SN plane from
the point of crossing of the images of the orbital roofsthe point of crossing of the images of the orbital roofs
and the internal plate of the frontal bone (cohen).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.

1.1. 4.SE:4.SE: SphenoethmoidalSphenoethmoidal
– the intersection of the– the intersection of the
shadows of the greatershadows of the greater
wing of the sphenoidwing of the sphenoid
and the cranial floor.and the cranial floor.
 5.Sor:5.Sor: Supraorbitale –Supraorbitale –
the most anterior pointsthe most anterior points
of the intersection of theof the intersection of the
shadow of the roof ofshadow of the roof of
the orbit and its lateralthe orbit and its lateral
contourcontour

 6.RO:6.RO: roof of orbit –roof of orbit –
uppermost point on theuppermost point on the
roof of the orbit.roof of the orbit.
 7.Ba:7.Ba: Basion – the medianBasion – the median
point of the anteriorpoint of the anterior
margin of the foramenmargin of the foramen
magnum.magnum.
 8.Bo:8.Bo: Bolton point- theBolton point- the
highest point in thehighest point in the
upward curvature of theupward curvature of the
retrocondylar fossa.retrocondylar fossa.
 9.Op:9.Op: opisthion: theopisthion: the
posterior edge of foramenposterior edge of foramen
magnum.magnum.

 Cl (clinoidale) :Cl (clinoidale) : the mostthe most
superior point on thesuperior point on the
contour of the anteriorcontour of the anterior
clinoid.clinoid.
 Ptm:Ptm: PterygomaxillaryPterygomaxillary
fissure- a bilateralfissure- a bilateral
teardrop-shaped area ofteardrop-shaped area of
radiolucency.radiolucency.
 S (Sella):S (Sella): PointPoint
representing the midpointrepresenting the midpoint
of the pituitary fossa (sellaof the pituitary fossa (sella
turcica)turcica)

 Se:Se: midpoint of themidpoint of the
entrance to the sella.entrance to the sella.
 Si:Si: floor of sella- thefloor of sella- the
lowermost point onlowermost point on
the internal contour ofthe internal contour of
the sella turcica.the sella turcica.
 Sp:Sp: dorsum sella- thedorsum sella- the
most posterior pointmost posterior point
on the internal contouron the internal contour
of the sella turcica.of the sella turcica.

 PO (Anatomic):PO (Anatomic): SuperiorSuperior
point of the externalpoint of the external
auditory meatus.auditory meatus.
 Te (Temporale):Te (Temporale): TheThe
intersection of theintersection of the
shadows of the ethmoidshadows of the ethmoid
and the anterior wall ofand the anterior wall of
the infratemporal fossa.the infratemporal fossa.
 A:A: Point A (or ss,Point A (or ss,
subspinale) – the point atsubspinale) – the point at
the deepest midlinethe deepest midline
concavity on the maxillaconcavity on the maxilla
between the anterior nasalbetween the anterior nasal
spine and prosthionspine and prosthion

 ANS:ANS: anterior nasal spineanterior nasal spine
– tip of the bony anterior– tip of the bony anterior
nasal spine.nasal spine.
 APMax:APMax: anterior point foranterior point for
determining the length ofdetermining the length of
the maxilla- this isthe maxilla- this is
constructed by dropping aconstructed by dropping a
perpendicular from pointperpendicular from point
A to the palatal plane.A to the palatal plane.
 KR:KR: the key ridge- thethe key ridge- the
lowermost point on thelowermost point on the
contour of the shadow ofcontour of the shadow of
the anterior wall of thethe anterior wall of the
intratemporal fossa.intratemporal fossa.

Or:Or: Orbitale – theOrbitale – the
lowermost point in thelowermost point in the
inferior margin of theinferior margin of the
orbit, midpoint betweenorbit, midpoint between
right and left images.right and left images.
Pns:Pns: Posterior nasal spine.Posterior nasal spine.
Pr:Pr: Prosthion – the lowestProsthion – the lowest
and most anterior point onand most anterior point on
the alveolar portion of thethe alveolar portion of the
premaxilla in the medianpremaxilla in the median
plane, between the upperplane, between the upper
central incisorscentral incisors

APMan :APMan : anterior landmarkanterior landmark
for determining the lengthfor determining the length
of the mandible –of the mandible –
perpendicular droppedperpendicular dropped
from Pog to thefrom Pog to the
mandibular planemandibular plane
(Rakosi).(Rakosi).
Ar:Ar: Articulare – the pointArticulare – the point
of intersection of theof intersection of the
images of the posteriorimages of the posterior
border of the condylarborder of the condylar
process of the mandibleprocess of the mandible
and the inferior border ofand the inferior border of
the basal part of thethe basal part of the
occipital bone.occipital bone.

 B :B : Point B (supramentale)- thePoint B (supramentale)- the
point at the deepest midlinepoint at the deepest midline
concavity on the mandibularconcavity on the mandibular
symphysis between infradentalesymphysis between infradentale
and pogonion.and pogonion.
 Co, condylion (or cd):Co, condylion (or cd): the mostthe most
superior point on the head of thesuperior point on the head of the
condylar head.condylar head.
 Gn:Gn: Gnathion- most anteroinferiorGnathion- most anteroinferior
point on the symphysis of the chin.point on the symphysis of the chin.
 Go:Go: Gonion – constructed pointGonion – constructed point
of intersection of the ramus planeof intersection of the ramus plane
and the mandibular planeand the mandibular plane

 Id:Id: Infradentale- the highestInfradentale- the highest
and most anterior point onand most anterior point on
the alveolar process in thethe alveolar process in the
median plane between themedian plane between the
mandibular central incisors.mandibular central incisors.
 Me:Me: menton – the mostmenton – the most
inferior midline point on theinferior midline point on the
mandibular symphysis.mandibular symphysis.
 Pog :Pog : pogonion – the mostpogonion – the most
anterior point of the bonyanterior point of the bony
chin in the symphysis .chin in the symphysis .

SOFT TISSUE LANDMARKSSOFT TISSUE LANDMARKS
 G-glabella-the mostG-glabella-the most
prominent point in theprominent point in the
midsagittal plane ofmidsagittal plane of
forehead.forehead.
 Ils-inferior labialIls-inferior labial
sulcus-the point ofsulcus-the point of
greatest concavity ingreatest concavity in
the midline of thethe midline of the
lower lip betweenlower lip between
labrale inferius andlabrale inferius and
menton.menton.

 Li-labrale inferius-theLi-labrale inferius-the
median point in the lowermedian point in the lower
margin of the lowermargin of the lower
membranous lip.membranous lip.
 Ls-labrale superius-theLs-labrale superius-the
median point in the uppermedian point in the upper
margin of the uppermargin of the upper
membranous lipmembranous lip
 Ms-menton soft tissue-theMs-menton soft tissue-the
contructed point ofcontructed point of
intersection of a verticalintersection of a vertical
co-ordinate from mentonco-ordinate from menton
and the inferior soft tissueand the inferior soft tissue
contour of the chin.contour of the chin.

 Ns-nasion soft tissue-point ofNs-nasion soft tissue-point of
deepest concavity of the softdeepest concavity of the soft
tissue contour of the root oftissue contour of the root of
the nose.the nose.
 Pn-pronasale-the mostPn-pronasale-the most
prominent point of the nose.prominent point of the nose.
 Pos-pogonion soft tissue-thePos-pogonion soft tissue-the
most prominent point on themost prominent point on the
soft tissue contour of thesoft tissue contour of the
chin.chin.
 Sls-superior labial sulcus-theSls-superior labial sulcus-the
point of greatest concavity inpoint of greatest concavity in
the midline of the upper lipthe midline of the upper lip
between subnasale andbetween subnasale and
labrale superiuslabrale superius

 Sn-subnasale-the pointSn-subnasale-the point
where the lower border ofwhere the lower border of
the nose meets the outerthe nose meets the outer
contour of the upper lip.contour of the upper lip.
 St-stomion-the midpointSt-stomion-the midpoint
between stomion superiusbetween stomion superius
and stomion inferiousand stomion inferious
 Sti-stomion inferious-theSti-stomion inferious-the
highest point of the lowerhighest point of the lower
lip.lip.
 Sts- stomion superius-theSts- stomion superius-the
lowest point the upper lip.lowest point the upper lip.

Cephalometric landmarks of PharynxCephalometric landmarks of Pharynx
 ANS-anterior nasal spine.ANS-anterior nasal spine.
 APW-anterior pharyngealAPW-anterior pharyngeal
wall.wall.
 Hy-hyoid.Hy-hyoid.
 PNS-posterior nasal spine.PNS-posterior nasal spine.
 PPW-posterior pharyngealPPW-posterior pharyngeal
wall.wall.
 Pt-posterior point ofPt-posterior point of
tongue.tongue.
 Ptm-pterygomaxillaryPtm-pterygomaxillary
fissure.fissure.

 Spw-superiorSpw-superior
pharyngeal wall.pharyngeal wall.
 U- tip of uvula.U- tip of uvula.
 Uo-point on the oralUo-point on the oral
side of soft palate.side of soft palate.
 Up-point on theUp-point on the
pharyngeal side of thepharyngeal side of the
soft palate.soft palate.
 UT- upper point of theUT- upper point of the
tongue.tongue.

CEPALOMETRIC LANDMARKS OFCEPALOMETRIC LANDMARKS OF
CERVICAL VERTEBRAE.CERVICAL VERTEBRAE.
 Cv2ap- the apex of theCv2ap- the apex of the
odontoid process of the 2odontoid process of the 2ndnd
cervical vertebrae.cervical vertebrae.
 Cv2ip- the mostCv2ip- the most
inferoposterior point on theinferoposterior point on the
body of the 2body of the 2ndnd
cv.cv.
 Cv2ia-the most inferoanteriorCv2ia-the most inferoanterior
on the body of the 2on the body of the 2ndnd
cv.cv.
 Cv3sp-most superoposteriorCv3sp-most superoposterior
point on the body of 3point on the body of 3rdrd
cv.cv.
 Cv3ip-the mostCv3ip-the most
inferoposterior point on theinferoposterior point on the
body of the 3body of the 3rdrd
cv.cv.

 Cv3sa-most superoanteriorCv3sa-most superoanterior
point on the body of 3point on the body of 3rdrd
cv.cv.
 Cv3ia-the most inferoanteriorCv3ia-the most inferoanterior
point on the body of the 3point on the body of the 3rdrd
cv.cv.
 Cv4sp- most superoposteriorCv4sp- most superoposterior
point on the body of 4point on the body of 4thth
cv.cv.
 Cv4ip-the most inferoposteriorCv4ip-the most inferoposterior
point on the body of the 4point on the body of the 4thth
cv.cv.
 Cv4sa- most superoanteriorCv4sa- most superoanterior
point on the body of 4point on the body of 4thth
cv.cv.
 Cv4ia- the most inferoanteriorCv4ia- the most inferoanterior
point on the body of the 4point on the body of the 4thth
cv.cv.

 Cv5sp- mostCv5sp- most
superoposterior point onsuperoposterior point on
the body of 5the body of 5thth
cv.cv.
inferoposterior point oninferoposterior point on
the body of the 5the body of the 5thth
cv.cv.
 Cv5sa- mostCv5sa- most
superoanterior point onsuperoanterior point on
cv.cv.
 Cv5ip- the mostCv5ip- the most
inferoanterior point oninferoanterior point on
cv.cv.

 Cv6sp-mostCv6sp-most
superoposterior point onsuperoposterior point on
cv.cv.
inferoposterior point oninferoposterior point on
cv.cv.
 Cv6sa- mostCv6sa- most
superoanterior point onsuperoanterior point on
cv.cv.
 Cv6ia-the mostCv6ia-the most
inferoanterior point oninferoanterior point on
cv.cv.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

This superimposition showedThis superimposition showed
 1. Anterior portion of the face moves away form1. Anterior portion of the face moves away form
the porion (But we know that portion and otherthe porion (But we know that portion and other
portions of the posterior face as condyle, gonion,portions of the posterior face as condyle, gonion,
body of ramus, move posteriorly during growth )body of ramus, move posteriorly during growth )
 2. Permanent first maxillary molar erupt past the2. Permanent first maxillary molar erupt past the
level of the deciduous occlusal planelevel of the deciduous occlusal plane
 3. Mandibular 13. Mandibular 1stst
molar appear stationary withmolar appear stationary with
respect to movement along the vertical planerespect to movement along the vertical plane
relative to Mandibular border.relative to Mandibular border.
 -- These structures have a low degree of validity,These structures have a low degree of validity,
although they have a high degree ofalthough they have a high degree of
reproducibility.reproducibility.

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

Reference structures for overall Face superReference structures for overall Face super
ImpositionsImpositions
 1.Anterior wall of sella1.Anterior wall of sella
turcia.turcia.
 2.Contour of the cribriform2.Contour of the cribriform
plate of the ethmoid bone.plate of the ethmoid bone.
 3.Details of the trabecular3.Details of the trabecular
system in the ethmoid cells.system in the ethmoid cells.
 4.Median border of the4.Median border of the
orbital roof.orbital roof.
 5.The plane of the sphenoid5.The plane of the sphenoid
base (planum sphenoidale).base (planum sphenoidale).

Maxillary SuperimpositionMaxillary Superimposition
 The purpose is to evaluate the movement of theThe purpose is to evaluate the movement of the
maxillary teeth in relation to the basal parts of themaxillary teeth in relation to the basal parts of the
maxilla. A number of methods have been suggested.maxilla. A number of methods have been suggested.
 1. Along the palatal plane at ANS1. Along the palatal plane at ANS
 2. Along the nasal floor at the anterior surface of maxilla2. Along the nasal floor at the anterior surface of maxilla
 3. Along the palatal plane registered at PTM fissure3. Along the palatal plane registered at PTM fissure
(Moore)(Moore)
 4. On the outline of the infra temporal fossa and the4. On the outline of the infra temporal fossa and the
posterior portion of the hard palate (Riedel).posterior portion of the hard palate (Riedel).
 5. On the best fit of the internal palatal structures5. On the best fit of the internal palatal structures
(McNamara)(McNamara)
 6. In the metallic implants (Bjork and Skieller )6. In the metallic implants (Bjork and Skieller )
 7. On the anterior surface of the zygomatic pr. of the mx.7. On the anterior surface of the zygomatic pr. of the mx.
(Bjork and skieller).(Bjork and skieller).www.indiandentalacademy.comwww.indiandentalacademy.com

 1. Along the palatal1. Along the palatal
plane at ANSplane at ANS
2. Along the nasal
floor at the anterior
surface of maxilla

 3. Along the palatal3. Along the palatal
plane registered atplane registered at
PTM fissurePTM fissure
(Moore)(Moore)
 4. On the outline of4. On the outline of
the infratemporalthe infratemporal
fossa and thefossa and the
posterior portion ofposterior portion of
the hard palatethe hard palate
(Riedel).(Riedel).

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

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

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

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

Stable Structures for Superimposition on the MandibleStable Structures for Superimposition on the Mandible
Bjork and Skieller (1983) form theirBjork and Skieller (1983) form their
implant studies indicated theseimplant studies indicated these
structures as relatively stable:structures as relatively stable:
 1. Anterior contour of the chin1. Anterior contour of the chin
 2. The inner contour of the cortical2. The inner contour of the cortical
plates at the inferior border of theplates at the inferior border of the
symphysis and any distinct trabecularsymphysis and any distinct trabecular
structure in the lower part of thestructure in the lower part of the
symphysis.symphysis.
 3.Posteriorly the contours of the3.Posteriorly the contours of the
mandibular canal and in the lowermandibular canal and in the lower
contour of a mineralized molar germ.contour of a mineralized molar germ.
 Medium to high degree of validityMedium to high degree of validity
and medium to high degree ofand medium to high degree of

BIBILIOGRAPHYBIBILIOGRAPHY
 Athanasios E Athanasiou;OrthodonticAthanasios E Athanasiou;Orthodontic
Cephalometry;Mosby-Wolfe,1 1995:11-20,46-60,107-Cephalometry;Mosby-Wolfe,1 1995:11-20,46-60,107-
123.123.
 Alexander Jacobson; RadiographyAlexander Jacobson; Radiography
Cephalometry;Quintessence Co,1995,26-33,39-62,165-Cephalometry;Quintessence Co,1995,26-33,39-62,165-
173,175-184.173,175-184.
 Stuart c. white and Michael J. pharoah; oral radiologyStuart c. white and Michael J. pharoah; oral radiology
principles and interpretation; Mosby 4principles and interpretation; Mosby 4thth
edition, 6-9edition, 6-9
 Thomas Rakosi; an atlas and manual of cephalometricThomas Rakosi; an atlas and manual of cephalometric
radiography; wolfe,1 1978: 7-8,radiography; wolfe,1 1978: 7-8,

 Norman Wahl, Orthodontics of 3 millennia.che.8:Norman Wahl, Orthodontics of 3 millennia.che.8:
the cephalometer takes its place in orthodonticthe cephalometer takes its place in orthodontic
armamentarium. AJO DO 2006,Vol-129.No.4,armamentarium. AJO DO 2006,Vol-129.No.4,
574-579574-579
 The introduction of cephalometric radiography,The introduction of cephalometric radiography,
Angle Orthodontist;Vol.51,No.2,April ,1981,93-Angle Orthodontist;Vol.51,No.2,April ,1981,93-
114114
 the Angle Orthodontist on CD-ROM (Copyright ©the Angle Orthodontist on CD-ROM (Copyright ©
1997 Angle Orthodontist, Inc.), 1997 No. 2, 83 -1997 Angle Orthodontist, Inc.), 1997 No. 2, 83 -
85: Making sense of cephalometrics Robert M.85: Making sense of cephalometrics Robert M.
RubinRubin

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