Wits, sassouni, jarabak /certified fixed orthodontic courses by Indian dental academy

CEPHALOMETRIC
ANALYSIS

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WITS APPRAISAL
• Since the introduction of ANB angle,it has been
one of the most popular means of cephalometric
evaluation of the A-P relationship of apical
bases.
• There are many situations in which ANB reading
cannot be relied upon.
• Purpose of Wits appraisal is to identify these
instances where ANB reading does not
accurately reflect the extent of A-P jaw
dysplasia.

• Relating the jaws to SN plane has certain
inherent inconsistencies because of
possible variations in the craniofacial
physiognomy ,such as• 1) The A-P position of nasion relative to
jaws.
• 2) The rotational effect of jaws relative to
cranial reference plane.

Effect of position of Nasion
A) Normal relationship
B) Nasion forward due
to long cranial base.
C) Nasion
retropositioned due
to short cranial base.


Effect of angulation of jaws,
occlusal plane on ANB angle
A) Normal relationship.
B) Effect of
counterclockwise
rotation of face .
C) Effect of clockwise
rotation of face.


•

Recognizing these shortcomings of ANB angle,
number of authors came up with alternative method-

1)

Jenkins (1955)-used functional occlusal plane.

1)

Harvold (1963)- Projected points A and B onto occlusal
plane. Termed the resulting measurement as A-B
difference.

2)

Jacobson (1975)- Published the classic article, “The
Wits appraisal of jaw disharmony”

• ‘WITS’- abbreviation for university of
witswatersrand,Johannesburg,South Africa.
• According to Jacobson- It is not an analysis per
se;rather it is intended as a diagnostic aid
whereby the severity or degree of A-P
disharmony can be measured.
• Measure of extent to which jaws are related to
each other A-P, independent of relationship to
cranial landmarks.

• Occlusal plane is
drawn through the
region of overlapping
cusps of premolars &
molars.
• Perpendiculars are
drawn on occlusal
plane from points A &
B.
• Contact points
labelled as AO & BO.


• In a sample of 21 adult males selected on basis of
excellence of occlusion, it was found that BO was
approx. 1mm ahead of AO.
• In 25 adult females ,AO & BO coincided.
• Therefore average jaw relationship according to wits
reading is –
-1mm in males
0mm in females
Clinical Significance - In skeletal class II,BO located well
behind AO.
In skeletal class III,BO would be forward of point AO.
Greater the wits reading – Greater the jaw discrepancy.

Applications of wits appraisal
•

The ANB angle is shown to be affected by several enviornmental
factors,diagnosis based on this angle may give false results,in
certain cases.

•

Factors affecting ANB angle-

•

1) Patient’s age- ANB has a definite tendency to reduce with
increasing age.

•

2) Change in spatial position of nasion.

•

3) Rotational effect of jaws

•

4) Change in the angle SN to occlusal plane.

•

5) The degree of facial prognathism.

•
•

6) Mandibular plane angle –
High angle suggests a
divergent type profile,
clockwise rotation of jaws,
resultant increase in ANB
reading.

•

In many cases where SNA,
SNB angles are in no way
representative of jaw
disharmony, wits appraisal
may be conveniently applied.


• DRAWBACKS – Largely dependent on correct location
or representation of the occlusal plane. Sometimes right
& left sides of posterior teeth don’t always coincide.
• In mixed dentition with deep bite,constructed occlusal
plane may differ considerably from functional occlusal
plane of deciduous & permanent molars
• If curve of spee is deep,it may be difficult to follow the
plane of maximum intercuspation.
• The angulation of functional occlusal plane to
pterygomaxillary vertical plane has been shown to
decrease from age 4 to 24.
•
( Sherman,Woods,Nanda, AJO-DO,May 1988)

• As growth takes place,there is change in
position of B point,which is masked by
increasing prominence of the chin.
• The ‘wits’ appraisal is intended not as a
single diagnostic criteria but as an
additional measurement, which may be
included in the existing cephalometric
analysis to aid in the assessment of the
degree of A-P jaw disharmony .

SASSOUNI’S ANALYSIS
• First published in AJO 1955,won first prize in
Essay contest sponsored by American
Association of Orthodontics.
• According to sassouni- “Architecture of skull is
result of many forces ,genetic forces,growth
forces,muscular,functional,enviornmental forces
on the adaptable bony substance.”
• At each period of life the skull is the end result of
the interaction of these forces.

• Problem – How can we study the architecture ?
• What is the significance of this architecture for diagnosis
and treatment?
• Are disturbances or disproportions in facial architecture
possible etiological factors in orthodontics, oral surgery,
prosthetics & periodontics ?
• Aim – To find some acceptably constant relationships in
the architecture of the head & to use them for diagnosis
& treatment.
• Material – 100 lateral head X-ray films (51 girls,49 boys).
White children of Mediterranean racial origin.


Terminology


Planes
1
Mandibular
plane,OG –
Tangent to inferior
border.
2 Occlusal plane,OPThrough mesial
cusps of
permanent 1st
molars & incisal
edges of incisors.
3 Palatal plane,ON –
perpendicular to
mid sagittal
plane,through
ANS-PNS.

• 4 Anterior cranial
base plane
angle,OS’- parallel to
axis of upper contour
of anterior cranial
base & tangent to
inferior border of
sella turcica
• 5 Ramal plane –
Tangent to posterior
border of ascending
ramus.


•

ARCS-

•

1 Anterior arc – Between
anterior cranial base plane
& mandibular plane,with O
as center & O – ANS as
radius.

•

2 Posterior arc – Between
anterior cranial base plane
& mandibular base plane,O
centre, OSp as radius. ( Sp is
most posterior point on rear
margin of sella turcica )


• Analysis- Mandible, Palate and Anterior cranial base are
examined.
• Mandible – 3 types
• 1 Curved – Upward traction forces at gonion &
downward pulling force at the menton are in equilibrium.
• 2 Oblique – Upward traction & downward pulling forces
seem to be so strong that we have a notch just anterior
to the gonial insertion of masseter.
• 3 Horizontal - Upward traction forces at gonion seems to
be greater than downward pulling forces at menton.


Palate
• Horizontal – Line
connecting ANS-PNS
passes through bony
structure of the palate.
• Convex – Line passes
above the bony structure
of palate.
• Concave – Line passes
below the bony structure
of palate.

• Relationship –
• With curved
mandible; horizontal
palate.
• Oblique mandible;
convex palate.
• Horizontal mandible;
concave palate


Key Ridge
• Presents 2 shapes –
Vertical & straight ,or Ilike.
• Double curved,like a
reverse 3 or like a sigma.
• Relation- When palate is
concave or convex,key
ridge is sigma like.
• When palate is
horizontal;key ridge is I –
like.


Relationship between mandibular plane,occlusal
plane,palatal plane & anterior cranial base plane
• In a well proportioned
face, all meet posteriorly
at the same point O.
• If we draw a circle from O
as a center,with O-ANS
as radius,it passes
through –
pogonion,nasion,ANS,
incisal edge of upper
incisor.
• All these points are
equidistant from O.

Posterior relationship in a well–proportioned face
•

•

If we draw a circle with O as
center,passing through
posterior wall of sella turcica
(Sp),it also passes through
gonion.
It can be said that –

•

A) Gonion & posterior wall of
sella turcica are equidistant
from O.

•

B) Anterior cranial base &
corpal length of mandible are
equal in length & position.


Relationship between anterior & posterior arcs
•
•
•
•
•
•
•
•

Face is delimited by –
Above by anterior cranial base
plane,OS’.
Below by mandibular plane
,OG.
Anteriorly by arc passing
through ANS.
Posteriorly by arc passing
through Sp
Proportion between anterior &
posterior arcs is a function of angle S’O G , ratio of both
radii Ra (O-ANS) / Rp (O-SP).
Combination of S’OG and
Ra/Rp is facial index.


Relationships between angles
• Angle S’OG (Mandibular
cranial angle) is unique to
each individual face.
• Angle S’ON
(Palatocranial ) = Angle
NOG (Palatomandibular)
• Angle NOP
(Occlusopalatal ) is
between 1/1 & 1/2 Angle
POG (occlusomandibular)
• Angle POG is always
larger than angle NOP in
a well proportioned face.


Classification of facial types
• I – Anterior cranial base
plane does not meet
three other planes at
common point O.
• II – Palatal plane does
not meet at O.
• III – Occlusal plane does
not meet at O.
• IV – Mandibular plane
does not meet at O.
• Type A – Plane passes
above point O.
• Type B – Below point O.

• In the sample studied ,type II facial pattern
was most frequent.
• Normal occlusion is condition necessary
but not sufficient for a well proportioned
face.
• Among 50 cases with normal
occlusion,only 16 had well proportioned
faces.

Classification based on vertical Proportions
• I Equal – Upper &
lower faces are equal.
Cranial base plane ANS = ANS – M.P.
II Minus – Lower face
is smaller than upper
face.
III Plus – Lower face is
larger.

Classification of profile
• I Archial – Anterior
arc passes through
Na,ANS,upper incisor
edge,pogonion.


• II Pre archial –
ANS,Upper
incisor,Pogonion are
situated anterior to
anterior arc passing
through Na.


• III Post archial –
Situated posterior to
anterior arc.


• Convex – ANS,Upper
incisor , are situated
anterior to anterior arc
passing by
Na,Pogonion.


• Concave – ANS &
upper incisor are
situated posterior to
anterior arc passing
by Na & pogonion.


Conclusions
• A complete well proportioned face as seen on
lateral X ray film is one in which –
• 1) Four facial planes meet at point O.
• 2) Anterior upper & lower faces are equal.
• 3) Posterior upper & lower faces are equal.
• 4) Profile is archial.
• 5) Corpus of mandible is equal in size & position
to the anterior cranial base.


• Thus there can be number of well
proportioned faces as it is a question of
proportion & not of absolute size.
• Acc. To Sassouni : “We have to admit that
there is no universal normality; there is no
norm which can be applied
indiscriminately to every body”

The Sassouni cephalometric analysis – A Racial
Comparison.
Dr. Ashima Valiathan J.I.D.A.1977
•

Compared the caucasians,Negro,Indian profiles. Findings –

•

1) Majority of caucasians have archial profile, majority of Indians
have post archial ( 65%) ,largest number of negroes presented with
a post-archial profile.

•

2) Both Indians & Negroes showed an overall procumbency of the
anterior teeth.

•

3) Compared to caucasians who showed equal upper & lower facial
heights,in Indians the anterior & posterior lower facial height were
more.

•

4) Corpus of mandible was found to be longer than the cranial base
in Indians as well as Negroes.


JARABAK ANALYSIS
• Presented by Joseph R .Jarabak in 1972.
• Composite analysis, takes into account
the skeletal aspects of growth as
described by Bjork.
• Analysis can be used in clinical
assessment of growth events to follow,
shows how to design treatment in
anticipation of these growth events.

• Takes into account ,the relationship
between anterior & posterior cranial base,
face & cranium, cranium & mandible.
• Interpret how craniofacial growth will
influence the dentition during treatment or
post treatment growth period.
.

• A feature of analysis is POLYGON, Na – S – Ar –
Go - Me to assess
anterior & posterior face
height relationships & to
predict the direction of
growth changes in lower
face.
• Basis of approach is
relationship of 3 angles• 1 Saddle angle- Na-S-Ar
• 2 Articular angle- S-Ar-Go
• 3 Gonial angle- Ar-Go-Me

• At age 11, anterior cranial base ( S-Na) should
equal to mandibular body length ( Go-Me).
• Ideal ratio of posterior cranial base length ( S-Ar)
to ramus height ( Ar-Go) is 3:4.
• CLOCKWISE GROWTH CHANGE – If sum of 3
angles is > 396°, ratio of posterior ( S-Go) to
anterior face height ( N-Me) is 56% to 64%.
• Anterior face height is increasing rapidly,
downward & backward growth change at
symphysis, & anterior open bite tendency.

• COUNTERCLOCKWISE CHANGE –
• 3 angles sum is < 396°,ratio of posterior to
anterior face height 65 to 80 %.
• More rapidly increasing posterior face
height, forward growth of condyle,anterior
deep bite tendency.


• Sample –
• Origin – some of the measurments were
described & taken . Bjork cephalometric
analysis.
• Facial growth predictions were made after
the age of 10 yrs, using the mean values
based on 200 treated cases, 5 yrs after
treatment.


MEASUREMENTS
• Saddle angle – Cranial
base bend formed by
joining N-S-Ar. Mean
Value – 123 ± 5°.
• Among Indians mean
value 124 ± 4°. North
Indians have a higher
saddle angle, indicate a
slightly posterior position
of mandible.
• ( Manish Valiathan
,Ashima Valiathan,
V.Ravinder, JIOS 2001).


• Large angle – Mandibular fossa growth will be
more posterior for the remaining growth
increment. Leads to increase in length of body of
mandible , arrangement of ascending ramus if
face has to remain orthognathic.
• If mandibular body length is same or shorter
than anterior cranial base, face will be
retrognathic & continue to grow that way.
• If angle is small,it tends to increase facial
prognathism.
• An extremely small angle can be seen in
achondroplastic patients.

• Flexure in saddle angle can be either large
or small in 3 body types.
• Higher angle – ectomorphs,
• lower angles – endomorphic &
mesomorphic pattern.
• Lokar showed in a stastically significant
sample that a small saddle angle is one of
the most frequently seen characteristics of
skeletal class III malocclusions.
• Saddle angle is in no way influenced by
orthodontic treatment.

• Articular angle – is
between S-Ar-Go.
• Mean value – 143 ±
6°.
• Indian – 141 ± 2°.
• Can be changed by
orthodontic treatment.
• If bite is opened by
extrusion of teeth or
by driving molars
distally, angle will
increase.

• If bite is closed by moving posterior teeth
anteriorly,articular angle will decrease.
• Females have a slightly higher articular
angle than males indicating that females
have a retrognathic mandibles in
comparison with males.


•
•
•
•

Gonial angle- between Ar-Go-Gn.
Expresses the form of mandible & its growth
direction.
Mean value – 128 ± 7°
Indian – 120 ± 1°
Manner in which ascending ramus & mandibular
body are related to each other to form gonial
angle determines how the mandibular growth will
influence facial structure.

• To determine the angular
relationship in which the
ramus & mandibular body
are put together angle is
divided into 2 parts –
• upper & lower gonial
angle by facial depth line
through a tangent of
lower border of mandible
& posterior surface of
ascending ramus.

• Upper angle – Slant of ramus .
• Mean value – 52° – 55°
• Indian value – 51° ,South Indian males show a higher
value.
•
•
•
•

Lower angle – Slant of body of mandible.
Mean value – 70 ° – 75 °
Indian value - 69°
If upper angle is large, remaining growth increment will
be in sagittal direction.
• If it is small, remaining increment will be downward or
downward & backward.

• Thus on completion of treatment,an
allowance for growth must be made,
leaving a somewhat greater overjet.
• Provides incisive freedom between
anterior teeth.
• Otherwise either mandibular crowding
may follow or anterior teeth may begin to
assume a class III relationship.

Ramus height
• Distance between Go
& Ar.
• Mean value – 44 ±
5mm.
• Boys – 40 – 46mm.
• Girls – 38 – 40 mm.
• Indian value;
• Males : 51 – 54 mm
• Females: 47mm.

• In boys ramus height increases 1 – 2
mm /yr , in girls : ¾ to 1 ¼ mm/ yr.
• As long as 3: 4 ratio ( posterior cranial
length to ramus height ) prevails children
having small faces would show favorable
downward mandibular growth.


Mandibular body length
• From Go – Me.
• Mean value : 71± 5mm.
• Increase in mandibular body length contributes
little to total facial prognathism, tend to increase
mandibular prognathism.
• A good incisor relation van go into class III, open
bite as a result of increase in ramus &
mandibular body length.
• Usually happens when – saddle angle is small,
mandibular body length to cranial base length is
> than 1.1 : 1: ; ramus height is more than 46mm
& upper gonial angle is large.

Posterior & Anterior facial height
• Ratio of posterior to
anterior face height of 56
– 62 % indicates
clockwise growing face.
• 65 – 82 % - higher
posterior facial growth
takes place, face grew
counter – clockwise.
• If posterior face is short ,
one can expect face to be
more retrognathic.

Facial depth & Facial length
• Facial depth –
distance from Na to
Go.
• Facial length –
distance from sella to
the intersecting lines
of facial & mandibular
planes


• Facial depth increases with growth in
almost all faces.
• Increment is greater when both gonial
angles are small.
• Facial length is a function of horizontal &
vertical growth combined, will be greater
where growth increments of lower face are
more horizontal than vertical.

DENTURE ANALYSIS
• Mandibular incisors to
facial plane –
• Ideally : 2mm in front or
behind facial plane.
• if posterior to plane,chin
are prominent, & lips are
withdrawn. ( Dished in).
• Anterior to facial plane :
lower face has a denture
prominence.


• Ideal relation of maxillary teeth to facial
plane is 5 ± 2 mm.
• In Indians, South Indian show greater
maxillary dental protrusion; South Indian
females have greater mandibular dental
protrusion.
• Maxillary incisor to SN plane – Mean
angulation : 102 ± 2°.

Relating Mandibular molars to symphysis
• Linear measurement
of distance from
mandibular 1st molar
( crown or mesial
root) to posterior
border of symphysis.
• Indirectly tells abount
the degree of overbite
that may develop in
retention & post
retention periods.

• If distance from these 2 points decreases
as a result of treatment , it indicates
molars were moved forward.
• Will result in increased overbite after teeth
have settled in function
• If roots & crowns moved in different
amounts , means molar were tipped
during treatment.

SOFT TISSUE PROFILE

• Analysis uses Rickett’s E plane because
of its simplicity ,reliability & chair side use.
• Esthetic E line : straight line from tip of
nose to tip of chin.
• Desirable relation : Lower lip lightly
touches the straight edge & upper lip is 2
– 4 mm behind E line.


• Nose being the most changeable of the 2
reference structures, has a profound
influence on relations of lips to the E
plane.
• Influence is not seen before 14 th yr.
• From 14 – 18 yrs it grows considerably in
boys.
• Generally prominent in malocclusions
characterized by forward maxilla.

REFERENCES
• 1 Valiathan A : Sassouni’s Cephalometric
analysis – A racial comparison. J I D A 1977;
49 : 393 – 95.
• 2 Valiathan M, Valiathan A, V.Ravinder: Jarabak
analysis reborn. J I O S 2001;34 : 66 -76.
• 3 Jarabak, Fizzell: Technique and treatment with
light wire edgewise appliance.St. Louis, Mosby ,
2nd edtn,Vol I ; Pg- 131 – 166.
• 4 Sassouni V. : A roentgenographic
cephalometric analysis of cephalo-facial dental
relationships. AJO 1955; 735 -61.

• 5 Jacobson: Wits appraisal of jaw disharmony.
AJO 1975.
• 6 Sherman, Woods, Nanda: Longitudinal effects
of growth on wits appraisal. AJO 1988.
• 7 Samir E. Bishara, Julie A. Fahl, Larry C.
Peterson: Longitudinal changes in ANB angle
and wits appraisal – Clinical implications. AJO
1983;84 (2): 133 -39
• 8 Jacobson : Introduction to radiographic
cephalometry. Lea & Febgier, Philadelphia;
1985,2nd edtn. Pg-63 – 71.

Thank you
Leader in continuing dental education


Wits, sassouni, jarabak /certified fixed orthodontic courses by Indian dental academy

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