Cephalometric points /certified fixed orthodontic courses by Indian dental academy

www.indiandentalacademy.comwww.indiandentalacademy.com

INTRODUCTIONINTRODUCTION
HISTORYHISTORY
TRACING AND ITS EQUIPMENTSTRACING AND ITS EQUIPMENTS
REFERENCE POINTSREFERENCE POINTS
-PROPERTIES-PROPERTIES
-DEFINITIONS-DEFINITIONS
SIGNIFICANCE OF LINEAR ANDSIGNIFICANCE OF LINEAR AND
ANGULAR MEASUREMENTSANGULAR MEASUREMENTS
CONCLUSIONCONCLUSION

INTRODUCTIONINTRODUCTION
The assessment of cranio-facial dimensionThe assessment of cranio-facial dimension
is not a new skill in orthodontics.Theis not a new skill in orthodontics.The
earliest method used was to assessearliest method used was to assess facial
proportions from an artistic point of viewfrom an artistic point of view
with beauty and harmony as the guidingwith beauty and harmony as the guiding
principles.principles.

Cephalometric radiography was introducedCephalometric radiography was introduced
in to orthodontics during 1930’s ,but thein to orthodontics during 1930’s ,but the
method gained wider range of acceptancemethod gained wider range of acceptance
only in the last twenty yearsonly in the last twenty years

HISTORICAL PREVIEWHISTORICAL PREVIEW
The evolution of cephalometry in 20The evolution of cephalometry in 20thth
century is universally linked tocentury is universally linked to Edward
Angle’s publication of his classification of
malocclusion
The scheme used the relationship b/wThe scheme used the relationship b/w
maxillary and mandibular dental archesmaxillary and mandibular dental arches

 VANLOON-1915
For meaningful diagnosis & treatmentFor meaningful diagnosis & treatment
planning, a three dimensional systemplanning, a three dimensional system
was required to determine the relation ofwas required to determine the relation of
dentition to the facedentition to the face
 BROADBENT & HOFRATH-1931
Published methods to obtainPublished methods to obtain
standardized head radiographs in thestandardized head radiographs in the
Angle orthodontistAngle orthodontist

TRACING TECHNIQUESTRACING TECHNIQUES
 Familiarise with gross anatomy of head-the bonyFamiliarise with gross anatomy of head-the bony
components of cranium and facecomponents of cranium and face
 A two dimensional cephalogram represents aA two dimensional cephalogram represents a
three dimensional object & bilateral structuresthree dimensional object & bilateral structures
will be projected on to the film.These bilateralwill be projected on to the film.These bilateral
structures should be distinguished and tracedstructures should be distinguished and traced

EQUIPMENTSEQUIPMENTS
-LATERAL CEPHALOGRAM (8X10 INCHES)-LATERAL CEPHALOGRAM (8X10 INCHES)
-ACETATE MATTE TRACING PAPER-ACETATE MATTE TRACING PAPER
-3H DRAWING PENCIL-3H DRAWING PENCIL
-MASKING TAPE-MASKING TAPE
-SHEETS OF CARDBOARD (6X12 INCHES)-SHEETS OF CARDBOARD (6X12 INCHES)
-A PROTRACTOR-A PROTRACTOR
-DENTAL CASTS TRIMMED TO MAXIMUM-DENTAL CASTS TRIMMED TO MAXIMUM
INTER CUSPIDATION OF TEETH IN OCC:INTER CUSPIDATION OF TEETH IN OCC:
-VIEW BOX-VIEW BOX

REFERENCE POINTSREFERENCE POINTS
The effective evaluation of radiographsThe effective evaluation of radiographs
depends on accurate definitions anddepends on accurate definitions and
localisation of landmarks,which provideslocalisation of landmarks,which provides
the basis for all further workthe basis for all further work
Distinction is made b/w anatomical andDistinction is made b/w anatomical and
anthropological points which are locatedanthropological points which are located
on or within skeletal structureson or within skeletal structures

PROPERTIESPROPERTIES
Ease of locationEase of location
Constancy of contoursConstancy of contours

1.EASE OF LOCATION:1.EASE OF LOCATION:
According to MOYERS (1973) thisAccording to MOYERS (1973) this
depends on the following factorsdepends on the following factors
-Quality of radiographs-Quality of radiographs
-Overlapping anatomical contours-Overlapping anatomical contours
-Observer experience-Observer experience

A. QUALITY OF RADIOGRAPHSA. QUALITY OF RADIOGRAPHS
 The quality of radiographs is often marred byThe quality of radiographs is often marred by
magnification or distortionmagnification or distortion
-Magnification is due to divergence of x-rays .-Magnification is due to divergence of x-rays .
The smaller the focus film distance andThe smaller the focus film distance and
greater the object image distance, greater is thegreater the object image distance, greater is the
magnificationmagnification
-Distortion arises from two dimensional-Distortion arises from two dimensional
representation of three dimensional objectrepresentation of three dimensional object

B. OVERLAPPING ANATOMICALB. OVERLAPPING ANATOMICAL
CONTOURSCONTOURS
Facial structures overlap a great deal,soFacial structures overlap a great deal,so
that location of certain landmarks maythat location of certain landmarks may
present problemspresent problems

C. OBSERVERC. OBSERVER
EXPERIENCEEXPERIENCE
Observer’s experience and practice play aObserver’s experience and practice play a
major role in the interpretation ofmajor role in the interpretation of
radiographs ,with knowledge of anatomyradiographs ,with knowledge of anatomy
and x-ray anatomy as the key factorand x-ray anatomy as the key factor

2. CONSTANCY OF CONTOURS2. CONSTANCY OF CONTOURS
The structures of skull show dependenceThe structures of skull show dependence
on a number of factors such as sex ,on a number of factors such as sex ,
growth , race etc…growth , race etc…
The constancy of contours is therefore notThe constancy of contours is therefore not
entirely reliable in contra-distinction toentirely reliable in contra-distinction to
points located close to the base of skullpoints located close to the base of skull
where variation due to growth is minimalwhere variation due to growth is minimal

Reference pointsReference points
UnilateralUnilateral BilateralBilateral

Nasion
Most anterior point of naso-frontal
suture in the median planewww.indiandentalacademy.comwww.indiandentalacademy.com

Nasion’
The point of maximum concavity b/w nose
and foreheadwww.indiandentalacademy.comwww.indiandentalacademy.com

Sella
Midpoint of hypophysial fossa

Midpoint of entrance to sella
The midpoint of line connecting the posterior
Clinoid process and the anterior opening of
Sella turcica

Condylion
Most superior point on the head of the condyle

Basion
The lowest point on the
anterior margin of the
Foramen magnum in the median planewww.indiandentalacademy.comwww.indiandentalacademy.com

Gonion
The intersection of line tangent to the
posterior margin of the ascending ramus
and the mandibular base

Menton
The most inferior point of the outline
Of symphysis in the mid-sagittal
plane www.indiandentalacademy.comwww.indiandentalacademy.com

Gnathion
The most anterior and inferior point of bony chinwww.indiandentalacademy.comwww.indiandentalacademy.com

Point B,Supramentale
The most posterior point in the outer contour
of mandibular alveolar process,in the median
plane

Prosthion
The lowest,most anterior point on the
alveolar portion of the premaxilla
b/w the upper centrals

Point A,Subspinale
The deepest midline point b/w the anterior
nasal spine and the prosthionwww.indiandentalacademy.comwww.indiandentalacademy.com

Anterior Nasal Spine
The tip of bony anterior nasal spine ,
In the median plane

Posterior Nasal Spine
The intersection b/w pterygopalatine
fossa and the floor of the nose.

Orbitale
Lowermost point of the orbit in the
radiograph www.indiandentalacademy.comwww.indiandentalacademy.com

Tip of nose
The most anterior point of
soft-tissue nose

Subnasale
The point at which nasal septum merges
mesially with the integument of upper lipwww.indiandentalacademy.comwww.indiandentalacademy.com

Inferior labial Sulcus
The point at which labrale inferius
meets soft tissue pogonionwww.indiandentalacademy.comwww.indiandentalacademy.com

Labrale Superius
Edge of upper lip

Soft tissue pogonion
The most anterior point of soft
tissue chin

pterygomaxillare
The posterior superior point of
pterugomaxillary fissure

Porion
The most superiorly positioned
point of external auditory meatus

Articulare
The point of intersection of posterior
Border of condylar process of mand
And inferior border of basilar part of
Occipital bone

 Dento-skeletal analysis –carried out in 3 stages.Dento-skeletal analysis –carried out in 3 stages.
1.Analysis of facial skeleton
2.Analysis of maxillary and
mandibular bases
3. Dento alveolar analysis

ANALYSIS OF FACIAL SKELETONANALYSIS OF FACIAL SKELETON
DeterminesDetermines Saddle, Articular and Gonial
angles and the extent of cranial base &angles and the extent of cranial base &
facial heightfacial height

SADDLE ANGLE
TheThe NS-ar angle is the angle b/w anteriorangle is the angle b/w anterior
and posterior cranial baseand posterior cranial base
Within the posterior cranial base lies theWithin the posterior cranial base lies the
sagittal growth centre, the sphenooccipitalsagittal growth centre, the sphenooccipital
synchondrosissynchondrosis
The position of the fossa is determined byThe position of the fossa is determined by
growth changes in this areagrowth changes in this area

A large saddle angle indicates a posteriorA large saddle angle indicates a posterior
position and a small saddle angle indicates anposition and a small saddle angle indicates an
anterior position of the fossaanterior position of the fossa
If this deviation is not compensated by lengthIf this deviation is not compensated by length
of the ascending ramus –prognathic orof the ascending ramus –prognathic or
retrognathicretrognathic
Mean valueMean value 123o +
5o

ARTICULAR ANGLE
If the bite is opened by extrusion ofIf the bite is opened by extrusion of
posterior teeth the angle increases whileposterior teeth the angle increases while
mesial movement makes it smallermesial movement makes it smaller
A large articular angle imposesA large articular angle imposes
retrognathic changes on the profile &retrognathic changes on the profile &
small angle , the prognathic changessmall angle , the prognathic changes
Mean value is 143Mean value is 143O +
6O

GONIAL ANGLEGONIAL ANGLE
A large angle –posterior rotation of theA large angle –posterior rotation of the
mandible with condylar growth directedmandible with condylar growth directed
posteriorlyposteriorly
A small gonial angle-anterior rotation withA small gonial angle-anterior rotation with
vertical growth of the condylevertical growth of the condyle
Mean value is 128Mean value is 128OO ++
77OO

Upper and Lower gonial angles-JarabakUpper and Lower gonial angles-Jarabak
Divided by a line drawn from nasion toDivided by a line drawn from nasion to
goniongonion
The upper angle is formed by ascendingThe upper angle is formed by ascending
ramus and the line joining nasion andramus and the line joining nasion and
goniongonion
Large upper angle –horizontalLarge upper angle –horizontal
Large lower angle-vertical growthLarge lower angle-vertical growth
Small upper angle-caudalSmall upper angle-caudal
Small lower angle-sagittal growthSmall lower angle-sagittal growthwww.indiandentalacademy.comwww.indiandentalacademy.com

1.The increased gonial angle is due to1.The increased gonial angle is due to
adaptation to greater anterior faceadaptation to greater anterior face
height.Adaptation may also occur in theheight.Adaptation may also occur in the
posterior part of facial skeleton due toposterior part of facial skeleton due to
posterior rotation in the TMJ,with theposterior rotation in the TMJ,with the
gonial angle unchanged ;the basal anglegonial angle unchanged ;the basal angle
will be increased however.will be increased however.
2. The height of the alveolar process adapts2. The height of the alveolar process adapts
to a large gonial angle ,resulting into a large gonial angle ,resulting in
increased anterior face heightincreased anterior face height

Posterior gonial anglePosterior gonial angle
Two types of gonial angles can beTwo types of gonial angles can be
distinguisheddistinguished
-A gonial angle opening out-A gonial angle opening out
posteriorly,with Go1 relatively largeposteriorly,with Go1 relatively large
-A gonial angle opening out anteriorly ,-A gonial angle opening out anteriorly ,
with Go 1 relatively smallwith Go 1 relatively small

Anterior gonial angleAnterior gonial angle
The anterior gonial angle was checked forThe anterior gonial angle was checked for
correlation with the basal plane angle.correlation with the basal plane angle.
-Basal plane angle becoming smaller in-Basal plane angle becoming smaller in
relation to gonial angle due to posteriorrelation to gonial angle due to posterior
rotation of mandiblerotation of mandible
-A relative increase in basal plane angle-A relative increase in basal plane angle
due to anterior rotation of mandibledue to anterior rotation of mandible

Sum of posterior anglesSum of posterior angles
The sum of all the three angles isThe sum of all the three angles is
396396OO ++
66OO
 If it is greater than 396If it is greater than 396OO
, the direction of, the direction of
growth is likely to be vertical;if it is smallergrowth is likely to be vertical;if it is smaller
then growth may be expected to bethen growth may be expected to be
horizontalhorizontal

ANALYSIS OF MAXILLARY ANDANALYSIS OF MAXILLARY AND
MANDIBULAR BASESMANDIBULAR BASES

SNA AngleSNA Angle
It defines the anteroposterior position ofIt defines the anteroposterior position of
point A relative to anterior cranial basepoint A relative to anterior cranial base
with a mean value of 81with a mean value of 81OO
as normalas normal
A large SNA Angle (greater than 84A large SNA Angle (greater than 84OO
))
makes the antero-posterior position ofmakes the antero-posterior position of
maxilla prognathicmaxilla prognathic
A small angle (less than 78A small angle (less than 78OO
) makes it) makes it
retrognathicretrognathic

SNB AngleSNB Angle
It defines the antero-posterior position ofIt defines the antero-posterior position of
mandible in relation to the anterior cranialmandible in relation to the anterior cranial
base with a mean value of 79base with a mean value of 79OO
as normalas normal
A large SNB Angle (greater than 82A large SNB Angle (greater than 82OO
))
makes it prognathicmakes it prognathic
A small SNB Angle (less than 79A small SNB Angle (less than 79OO
) makes) makes
it retrognathicit retrognathic

MORPHOLOGY OF THE MANDIBLEMORPHOLOGY OF THE MANDIBLE
-- orthognathicorthognathic
- prognathic- prognathic
- retrognathicretrognathic

Orthognathic typeOrthognathic type
Ramus and the body are fully developedRamus and the body are fully developed
with the width of the ascending ramuswith the width of the ascending ramus
equal to the height of body of the mandibleequal to the height of body of the mandible
The occlusal surface runs parallel to planeThe occlusal surface runs parallel to plane
of the mandible with condylar andof the mandible with condylar and
coronoid process almost on the samecoronoid process almost on the same
planeplane
The lower incisors almost at right angle toThe lower incisors almost at right angle to
plane of the mandibleplane of the mandible

Retrognathic typeRetrognathic type
The ascending ramus is narrow,as is theThe ascending ramus is narrow,as is the
condyle in the antero-posterior directioncondyle in the antero-posterior direction
The coronoid process is shorter than theThe coronoid process is shorter than the
condylar process and the mandibularcondylar process and the mandibular
angle is largeangle is large
The angle b/w the axis of lower incisorsThe angle b/w the axis of lower incisors
and the mandibular plane is greater thanand the mandibular plane is greater than
9090OO
..

Prognathic typePrognathic type
The ascending ramus and the body areThe ascending ramus and the body are
wide with small mandibular anglewide with small mandibular angle
The symphysis is well developedThe symphysis is well developed
The angle b/w the axis of lower incisorsThe angle b/w the axis of lower incisors
and the mandibular plane is less than 90and the mandibular plane is less than 90OO

ANB AngleANB Angle
The ANB Angle is positive if point A liesThe ANB Angle is positive if point A lies
anterior to NB and negative if point A liesanterior to NB and negative if point A lies
posterior to NBposterior to NB
If NA and NB coincide the angle will beIf NA and NB coincide the angle will be
zerozero
On average the angle is 2On average the angle is 2OO
High positives-class II ,and negatives inHigh positives-class II ,and negatives in
skeletal class IIIskeletal class III

The Wit’s MethodThe Wit’s Method
A measure of the extent to which jaws areA measure of the extent to which jaws are
related to each other antero-posteriorlyrelated to each other antero-posteriorly
The perpendiculars are drawn on a lateralThe perpendiculars are drawn on a lateral
cephalometric head filmtracing from pointcephalometric head filmtracing from point
A and point B on maxilla and mandible onA and point B on maxilla and mandible on
to the occlusal plane which is drawn thruto the occlusal plane which is drawn thru
the region of maximal cuspalthe region of maximal cuspal
interdigitationinterdigitation

The points of contacts on the occlusalThe points of contacts on the occlusal
plane are labelled as AO and BOplane are labelled as AO and BO
It was found that with normal occlusion,It was found that with normal occlusion,
point BO was approx 1mm anterior topoint BO was approx 1mm anterior to
point AOpoint AO
In skeletal Class II jaw dysplasias ,pointIn skeletal Class II jaw dysplasias ,point
BO will be located well behind point AOBO will be located well behind point AO
and viceversa in skeletal Class IIIand viceversa in skeletal Class III

HORIZONTAL LINESHORIZONTAL LINES
Inter-relations are assessed to determineInter-relations are assessed to determine
the vertical position of the maxillary andthe vertical position of the maxillary and
mandibular basesmandibular bases
The most important lines are the SNThe most important lines are the SN
plane,FH plane,Palatal plane,occlusalplane,FH plane,Palatal plane,occlusal
plane and the mandibular planeplane and the mandibular plane

Basal plane angleBasal plane angle
It defines the inclination of the mandible toIt defines the inclination of the mandible to
the maxillary base ,therefore also servesthe maxillary base ,therefore also serves
to determine the rotation of the mandibleto determine the rotation of the mandible
If the basal plane angle is large then theIf the basal plane angle is large then the
mandible is usually rotated backwards andmandible is usually rotated backwards and
if it is small then the mandible is rotatedif it is small then the mandible is rotated
forwardsforwards

With the retro-inclination of the maxillaryWith the retro-inclination of the maxillary
base , the basal angle will be relativelybase , the basal angle will be relatively
smaller,with ante-inclination, relativelysmaller,with ante-inclination, relatively
largerlarger
The mean basal angle is 25The mean basal angle is 25OO

N-S-Gn AngleN-S-Gn Angle
This angle determines the relative positionThis angle determines the relative position
of mandible to cranial base as anof mandible to cranial base as an
additional checkadditional check
It has a mean value of 66It has a mean value of 66oo
A greater value –mandible in a posteriorA greater value –mandible in a posterior
position with a vertical growth patternposition with a vertical growth pattern
If the angle is less than the mean valueIf the angle is less than the mean value
mandible is in an anterior positionmandible is in an anterior position

DENTO-ALVEOLAR ANALYSISDENTO-ALVEOLAR ANALYSIS

Angulation of upper incisorsAngulation of upper incisors
Two measurements are considered;firstlyTwo measurements are considered;firstly
its long axis considered in relation to SNits long axis considered in relation to SN
and secondly to palatal planeand secondly to palatal plane
For the first measurement , the long axisFor the first measurement , the long axis
of upper incisors is extended to intersectof upper incisors is extended to intersect
the SN line and the posterior angle isthe SN line and the posterior angle is
measuredmeasured

The mean value is 102The mean value is 102oo ++
2200
Up to the 7Up to the 7thth
year , it is only 94-100year , it is only 94-100OO
onon
average ,with 102average ,with 102OO
achieved only 1 or 2achieved only 1 or 2
years after eruptionyears after eruption
Larger angles indicate maxillary incisorLarger angles indicate maxillary incisor
protrusion and smaller angles very uprightprotrusion and smaller angles very upright
incisorsincisors

In the second measurement the anteriorIn the second measurement the anterior
angle b/w the long axis of incisor and theangle b/w the long axis of incisor and the
palatal plane is measuredpalatal plane is measured
The mean value from 8The mean value from 8thth
year onward isyear onward is
7070OO ++
55OO
An enlarged angle signifies very uprightAn enlarged angle signifies very upright
incisors ,a smaller than average oneincisors ,a smaller than average one
incisor protrusionincisor protrusion

Angulation of Lower IncisorsAngulation of Lower Incisors
The posterior angle b/w the long axis ofThe posterior angle b/w the long axis of
the incisor and the mandibular plane isthe incisor and the mandibular plane is
determineddetermined
The mean value is 90The mean value is 90OO ++
33OO
From the 6From the 6thth
to the 12to the 12thth
year ,the angleyear ,the angle
increases from 88increases from 88OO
– 94– 94OO

A wide angle indicates protrusion ofA wide angle indicates protrusion of
mandibular incisors , a smaller thanmandibular incisors , a smaller than
normal angle , a very upright incisorsnormal angle , a very upright incisors

Assessment of Incisor positionAssessment of Incisor position
The distance of incisal edges from theThe distance of incisal edges from the
NPog line is determinedNPog line is determined
The average distance is 4The average distance is 4 ++
2 mm for2 mm for
mawillary incisors and for lower incisors itmawillary incisors and for lower incisors it
is -2 to +2mmis -2 to +2mm

This particular measurement is a keyThis particular measurement is a key
factor-factor-
-whether the extraction is indicated-whether the extraction is indicated
-whether the lower incisors can be-whether the lower incisors can be
moved forwardmoved forward
-whether the anchorage is critical-whether the anchorage is critical

CONCLUSIONCONCLUSION
Among the many miracles of life is theAmong the many miracles of life is the
uniqueness of human face.No part of ouruniqueness of human face.No part of our
anatomy provides more information;anatomy provides more information;
indeed,no part of our anatomy is moreindeed,no part of our anatomy is more
vital to our success and existence.vital to our success and existence.
In this era of burgeoning biotechnologyIn this era of burgeoning biotechnology
orthodontic profession has entered aorthodontic profession has entered a
pivotal period –the one that will continue topivotal period –the one that will continue to
change the practice of orthodontics.change the practice of orthodontics.

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