GROWTH ROTATION OF POST NATEL GROWTH OF MAXILLA.pptx

Dr. BABITHA MERIN GEORGE
1 ST YEAR PG
DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL
ORTHOPEDICS
SEMINAR NO : 2

CONTENTS
o INTRODUCTION
o TERMINOLOGIES
o BJORK STUDY/IMPLANT RADIOGRAPHY
o MANDIBULAR GROWTH ROTATION
o BJORK STUDY
o STRUCTURAL SIGNS OF GROWTH ROTATION
o CLINICAL IMPLICATIONS
o BJORK AND SKEILLER’S METHOD

o THREE DIFFERENT INTERPRETATION OF
INTRAMATRIX ROTATION
o DIBBET’S CONCEPT
o COUNTERBALANCING ROTATION
o COUNTERBALANCING PROPORTION
o SCHUDY’S CONCEPT
o PROFFIT’S DESCRIPTION OF ROTATION
o SOLOW & HOUSTON DESCRIPTION OF ROTATION
o REFERENCES

INTRODUCTION
⮚The phrase growth rotation was introduced in 1955 by Bjork. In
reporting a case he states that the lowering of the mandible during growth
was “considerably greater posteriorly than anteriorly, Bjork drew attention
to what he called the mandibular rotation”.
⮚This was based on the fact metallic implants, had given Bjork precise
markers from which he could infer the sites and amount of growth and
resorption in a given mandible.
The puzzle of growth rotation – J.M.H. Dibbets, AJO, June 1985, pg. 473-480

⮚By superimposing two consecutive tracings
of the child's mandible registered on the
implants, the image of the older mandible
appeared to have rotated slightly forward
during the intervening period relative to its
original shape.
⮚The direction of growth and inclination of
jaw bases is unique and no two individuals
are alike.

ROLE IN
ORTHODONTICS
The rotation of maxillary and mandibular jaw bases
is a major factor in etiological assessment,
determining the nature of anomaly, the prognostic
evaluation, determining the possible forms of
treatment, in choosing the principles of treatment
and also in assessing the stability of treatment
results.
Certain rotational patterns of jaw bases can be
manipulated quite effectively by means of functional
and orthopedic devices while certain extreme
rotations are very difficult to treat and surgical
correction has to be performed at a later stage.

TERMINOLOGIES.
 Lande in 1952 – Pointed that lower border of mandible on average
becomes less steeply inclined with growth.
 Bjork in 1955 – Drew attention to mandibular growth rotation as a
feature of normal facial growth, and he done metallic implant study
and demonstrated the much greater underlying mandibular rotation
that was masked by periosteal remodeling at the lower border.
 F.F.Schudy in 1965- introduced clockwise and counterclockwise
rotation.
 Bjork in1969- Discussed different directions of rotation of the
mandibular implant line and the relation of these to mandibular
form.
9

Odegard in 1970-Described rotation as the change in the
orientation that can occur between implant line and lower
border of the mandible.
Bjork and Skieller in 1972 –Demonstrated that
dentoalveolar adaptation in response to mandibular
growth rotation could result in occlusal change such as late
lower incisor crowding.
Lavergne and Gasson in 1977- Described the terms
Positional and Morphogenetic rotations.
Bjork and Skieller in 1983 gave the terms-
Total rotation.
Matrix rotation.
Intramatrix rotation.
10

Dibbets in 1985- Introduced the term “Counterbalancing
rotation”.
Solow,Houston in 1988 -
True rotation.
Apparent rotation.
Angular remodeling of the lower border.
Proffit- used the terms
Internal rotation.
Total rotation .
External rotation.
11

BJORK
STUDY/IMPLANT
RADIOGRAPHY
⮚The first implant radiographic study was initiated in the year 1951 by
Bjork and comprised of a mixed longitudinal study of about 100 children
of each sex covering the age from 4 to 24 yrs.
⮚And it was Bjork who used metallic implants as markers in the jaws.
⮚Until Bjork's studies, the extent to which both the maxilla and
mandible rotate during growth was not appreciated.
Bjork A. Prediction of mandibular growth rotation. Am J Orthod.1969;55:585-99

 He identified that the mandibular canal is not remodeled to
the same extent as the outer surface of the jaw and the
trabaculae related to canal (Core of the mandible) are
therefore relatively stationary.
 Also the lower border of the developing molar tooth germ
(before the roots begins to form) appears to be fairly stable
point and serve as natural reference structure in the growth
analysis of the mandible .
 By super imposing consecutive tracings, he
concluded that rotation involved.
1. Marked resorption in the gonial region.
2. Apposition in the posterior and lower border
of the symphysis.

The implants are used
To find the sites of growth
and resorption in individual
jaws.
To examined individual
variation in direction and
intensity of growth.
To analyze the mechanism of
changes in intermaxillary
relations during growth.
THE
IMPLANTS
ARE USED

IMPLANTS WERE PLACED IN THE FOLLOWING SITES OF
MANDIBLE:-
•Anterior aspect of symphysis, in the
midline below the root tips.
•Two pins on the right side of
mandibular body
•One pin under the first premolar
and the other below the first molar.
One pin on the external aspect of the
right ramus in level with the occlusal
surface of the molars.

⮚Growth in length of the mandible in man occurs
essentially at the condyles.
⮚The anterior aspect of the chin is extremely stable.
RESULTS OF STUDY

 The thickening of the symphysis normally takes place by
apposition, which contributes to the increase in height of
the apposition on its posterior surface. On its lower border
there is likewise symphysis

⮚Below the angle of the mandible there is normally
resorption, which may be very pronounced.
⮚The growth at the condyles usually does not
occur in the direction of the ramus
⮚The mandibular canal is not remodeled to the
same extent as the outer surface of the jaw. The
curvature of the mandibular canal, therefore,
reflects the earlier shape of the mandible.

MANDIBULAR GROWTH ROTATIONS
⮚Mandibular rotations assume an important role in orthodontic
treatment planning because mandibular rotations are more common
than maxillary rotations.
⮚Mandibular inclination drastically affects facial morphology, and
treatment planning and treatment outcome and mandibular inclination
to a certain extent can be effectively guided by certain functional or
orthopedic appliances during growth period.

 The pattern of mandibular growth rotation is generally UPWARD
& FORWARD curving growth whose degree of rotation is being
masked by resorption on the lower aspect of the gonial angle
and apposition below the symphysis.

 With the conventional examination of the cephalametric
radiograph (base of the mandible), TMJ was considered as the
center of rotation of the mandible.
 Bjork with the implant method recognized various types
of rotation with varying centres of rotation.

TERMINOLOGY BY BJORK
⮚Forward Rotation: When posterior growth is greater than anterior
growth.
⮚Backward Rotation: When anterior growth is greater than posterior
growth.
⮚Total Rotation: It is the rotation of mandibular core relative to
cranial base.
⮚Matrix Rotation: It is the rotation of mandibular
plane relative to cranial base.
⮚Intramatrix Rotation: It is the rotation of
mandibular plane relative to core of the
mandible.

BJORK’S CLASSIFICATION(1969):
FORWARD
ROTATION
BACKWARD
ROTATION
• TYPE I
• TYPE II
• TYPE III
• TYPE I
• TYPE II

FORWARD ROTATION
RD ROTATION
Forward rotation has 3 types:
Type 1:
Center- Joints
Deep bite
Lower dental arch is pressed
into upper
Underdevelopment of the
anterior face height
Cause- occlusal imbalance due to
loss of teeth or powerful muscular
pressure

Type II:
Center-incisal
edge of lower
anterior teeth
Cause-
combination of
marked
development of
the posterior face
height and
normal increase
in the anterior
height.
⮚The posterior
part of the
mandible then
rotates away
from the maxilla.
⮚muscular and
ligamentous
attachments, with
the center at the
incisal edges of
lower incisors.

 The increase in posterior face height has two components-
1. Lowering of middle cranial fossa in relation to the anterior one
leads to lowering of condylar fossa.
2. Increase in the height of the ramus.

Type III:
Occurs in anomalous
occlusion of the
anterior teeth where
there is a large overjet.
Center of rotation is
displaced backward to
the level of the
premolars instead of
incisors.
The anterior face
height becomes
underdeveloped when
the posterior face
height increases.
Dental arches are
pressed into each
other and basal deep
bite develops

⮚In the growth rotation of type II and type III, the
mandibular symphysis swings forward to a marked
and the chin becomes prominent.
⮚Rotation also displaces the path of eruption of all the
teeth in the mesial direction, thereby tending to create
crowding in the anterior segment through what may be
referred to as “packing”.

• The rotation also affects the position of the lower posterior
teeth in relation to the upper teeth
• Forward growth rotation thus causes the lower posterior
to be more upright than usual in relation to upper posterior
teeth, with an increase in interpremolar and intermolar
angles.

FORWARD ROTATIONS
COR FACIAL HEIGHT CAUSE
Anterior Posterior
Type I Joint Decrease
AFH Deep
bite
- Occlusal imbalance due
to loss of teeth /
powerful musculature.
Type II Inciscal edge of
the lower
anterior teeth
Normal
AFH
Marked
increased
PFH
(i). Lowering at middle
cranial fossa, lowering
the condylar fossa
(ii). Vertical growth at
the mandibular condyle
Type III At the level of
premolars
Decrease
AFH Deep
bite
Increase
PFH
In anamolous occlusion
of anterior e.g.
Increased overjet.

BACKWARD ROTATION
Backward rotation of mandible is less
common than forward rotation.
Two types have been recognized:
 TYPE 1
 TYPE 2

The center of
rotation lies in the
TMJ.
▪This occurs when bite
is raised by orthodontic
means and results in an
increase in the anterior
face height.
In case of flattening of
the cranial base, the
middle cranial fossae are
raised in relation to the
anterior one, and then
the mandible is also
raised
⮚Incomplete development in
height of the middle cranial fossa (
as in Oxycephaly),the
underdeveloped posterior facial
height leads to a backward rotation
of mandible, with overdevelopment
of anterior face height and possibly
open bite as a consequence.
Type I:

Type II:
⮚the centre of rotation is
situated at the most distal
occluding molars.
occurs in connection with
growth in the sagittal
direction at the condyles
As the mandible grows in
the direction of its length, it
is carried forward more than
it is lowered in the face, and
because of its attachment
to muscles and ligaments
it is rotated backward
Because of the position of
center of rotation at the
molars, the symphysis is
swung backward and the
chin is drawn back below
the face
⮚The soft tissues of the
chin may not follow this
movement and a
characteristic double chin
can form.
⮚Basal open bite may
develop, and there is
difficulty in closing the lips
without tension.
⮚This type of backward
rotation has been
found to be
characteristic in cases
of various form of
condylar hypoplasia

In Type II Backward rotation COR at the distal occluding
molars
Symphysis is swung backward
Chin is drawn below the face
Soft tissue do not follow the bony chin
Characteristic double chin is formed
Double Chin

BACKWARD ROTATIONS
COR CAUSE FACIAL
Type I TMJ 1. Raising of bite by
orthodontic means
Increased AFH
2. Flattening of cranial
base
3. Oxycephaly
Decreased PFH
Increased AFH
Type II Most distal
occluding molars
Growth in the sagittal
direction at the
mandibular condyles
Basal open bite

Type II in both types of rotation is due to different condylar
growth direction.
FORWARD BACKWARD
Vertical direction of condylar
growth
Lowering of mandible
This lowering of mandible in turn
takes place as forward rotation
due to the muscular and
ligamentous attachments
Saggital direction of condylar
growth
Mandible grows in the direction of
its length
Due to attachments of muscles and
ligaments the mandible is rotated
backwards
S
U
M
M
A
R
Y

Forward rotation
 Dentoalveolar proclination of lower anteriors
 Mesial path of eruption leading to crowding (packing)
Backward rotation
 Dentoalveolar retroclination of lower anteriors
 Crowding.
S
U
M
M
A
R
Y
Inclination of teeth: (Bjork & Skieller) (lower)
 The inclination of teeth, is also greatly influenced by rotation of
the lower jaw.
 Incisors:
Irrespective of jaw rotation the lower incisors are functionally
related to the upper incisors & follow the upper incisors.

 Lower posterior teeth
 Forward :
 Upright than normal lower posteriors in relation to the upper
posteriors.
 Increase in interpremolar and intermolar angles
and the vice versa for backward rotations.

Following
are the
signs of
growth
rotation.
1.Inclination of the condylar head
2.Curvature of the mandibular canal
3.Shape of lower border of mandible
4.Inclination of the symphysis
5.Inter premolar or intermolar angles
6.Inter incisal angle
7.Anterior lower face height.
STRUCTURAL SIGNS OF GROWTH ROTATION
⮚Bjork has given seven structural signs of extreme growth rotation in
relation to the condylar growth direction.

1. INCLINATION OF THE CONDYLAR HEAD
⮚A forward or backward inclination of the condylar head is a
characteristic sign, but it may not be easy to identify on the
cephalometric radiogram, where part of the condyle is
masked.

2.CURVATURE OF THE MANDIBULAR CANAL
⮚The curving of the mandibular canal
may also be a clear sign.
⮚ In the vertical type of condylar growth,
the curvature of the canal tends to be
greater than that of the mandibular
contour, including the angle of the jaw,
whereas in the sagittal type the opposite
is generally the case.

3.SHAPE OF LOWER BORDER OF MANDIBLE
⮚In sagittal growth, the anterior
rounding is absent and the cortical
layer is thin, while the lower contour
at the jaw angle is convex(backward
rotation).
HORZONTAL CONDYLAR
GROWTH

⮚In vertical condylar growth, the
pronounced apposition below the
symphysis and the anterior part of the
mandible produces an anterior rounding,
with a thick cortical layer, while the
resorption at the angle produces a typical
concavity(forward rotation).
VERTICAL CONDYLAR
GROWTH

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GROWTH ROTATIONS
53
Lower border of mandible
(Antigonial notch).

4.INCLINATION OF THE SYMPHYSIS
⮚The inclination of the symphysis is an important feature.
⮚In the vertical type of growth, the symphysis swings forward in the
face and the chin is prominent, while in the sagittal type it is swung
back, with a receding chin.
⮚The evaluation is complicated by the simultaneous remodeling of
the alveolar process in the opposite direction.

Lower Border & Inclination of Symphysis

5.INTER MOLAR ANGLE
⮚The inter molar angle tends to increase in
forward rotation of the mandible and decrease
when the rotation is directed backward. The
difference in the interpremolar and intermolar
angles in the two growth types is also clear.

6.INTER INCISAL ANGLE
⮚In backward rotation the inter incisal angle is reduced,
whereas in forward rotation it is increased.

7.ANTERIOR LOWER FACE HEIGHT.
▪ In forward growth rotation there is deep overbite and reduced lower face
height.
▪ In backward rotation there is increased lower face height and open bite.

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LOWER ANTERIOR FACIAL HEIGHT

• It is important to detect extreme types of mandibular
rotation occurring during growth
• Not all of them will be found in a particular individual, but
the greater the number which is present the more reliable
the prediction will be .
HE CONCLUDED ON THE STRUCTURAL SIGNS

CLINICAL IMPLICATIONS
Both forward and backward rotation generally influences path of
eruption
Serious risk of extreme migration after extractions
Extractions should be avoided until the beginning of pubertal
growth spurt.

 According to Petrovic
In orthognathic type of face, the ramus and the body
of the mandible are fully developed, and the width of
the ascending ramus is equal to the height of the
body of the mandible, including height of the alveolar
process and the incisors. The condyle and coronoid
process are almost in the same plane and symphysis
is well developed.
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In case of a retrognathic mandible corpus is narrow in
molar region. Symphysis is narrow and long, ramus is
narrow and short and the gonial angle is obtuse and the
coronoid process is relatively smaller than the condylar
process..
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In prognathic type the corpus is well developed and
wide in molar region. Symphysis is wider in sagital
plane, ramus is wide and long and the gonial angle is
acute or small.
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BJORK AND SKIELLER’S METHOD
DIVIDED THE MANDIBULAR ROTATIONS INTO THREE COMPONENTS:
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TOTAL
ROTATION
MATRIX
ROTATION
INTRAMATRIX
ROTATION

Total Rotation
 Is the rotation of the mandibular corpus
 Is measured as change in inclination of
a reference line or a implant line in the
mandibular corpus relative to the
anterior cranial base,
 If line anteriorly rotate towards the face
then is known as forward rotating in
relation to S-N plane and designated as
‘-’
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 Total rotation obviously is perceived by Isaacson’ and his co-workers.
They constructed a “center of rotation” for the mandible, and, in an
elegant way, overcame the absence of implants.
 A major factor in the position of this center, however, is the
translation” or displacement” of the mandible in relation to an
referent, in this case the cranial base. In fact, then, this center is a
summation of mandibular movement in relation to the cranium and
Bjork’s actual “intramatrix rotation.”
 Isaacson and associates, therefore, contributed an important piece to
the puzzle in the form of a geometric construction of the center of
“total rotation.” They did not, however, unravel or isolate the specific
elements that contribute to the location of this center.

Matrix rotation
 Was called as apparent rotation by Lande.
 Is rotation of soft tissue matrix of the mandible
relative to the cranial base.
 Is shown by a tangential mandibular line.
 It can rotate forward and backward in the same
patient with condyles as the centre of rotation
and is described by the term pendulum
movement.
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 The assessment of the mandibular plane angle and developmental
changes in that angle (defined as “matrix rotation” by Bjork and
Skieller) is the oldest known piece of the puzzle.
 Since the inception of cephalometrics on a longitudinal basis, in
effect, “matrix rotation” reflecting angular changes in the
mandibular plane has been quantified.
 Schudy and Jarabak and Fizzell were pioneers who contributed to
this particular aspect of rotation. The so-called clockwise- and
counterclockwise-growing faces, as defined in the Jarabak analysis,
show these specific postulated patterns only when related to the
cranial base.
 It is not primarily the remodeling of the mandible upon which this
classification is based; rather, it is the position of the mandibular
plane in relation to the cranial base that is being assessed.

Intramatrix rotation
 Is the difference between total rotation and the matrix
rotation.
 It is an expression of remodeling of the lower border of the
mandible.
 It is found out by the change in inclination of an implant line
or reference line in the mandibular corpus to the tangential
mandibular line.
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 Rotation of the corpus
relative to the tangential
line such that it faces
front is called as forward
rotation.
 Centre of rotation is
somewhere in corpus and
not in the condyles and
depends on rotation of
corpus, growth rotation
of the maxilla and
occlusion of the teeth.
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BJORK AND SKIELLER SAID THAT THREE CHANGES OCCUR IN
INTRAMATRIX ROTATION:
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The mandible “wiggles” in in its matrix
This wiggling is associated with the
corpus and is caused by growing condyle.
The rotation results from or compensates for
genetically predetermined program.

 The condyle grows on a circular arc with
radius from center at chin to the condyle.
 When two tracings are superimposed on
their contours, they are identical in size
& shape.
 The external configuration of mandible
need not change its form or its position
in order to allow ‘Intramatrix rotation’
 Any Depositional or Resorptive activity at
the periosteum maintains original
contours

Diagrammatic Illustration Of Concept Of
Intramatrix Rotation”

First option - Bjork & Skieller
define the “Intramatrix Rotation” as The
Rotation of the mandibular corpus relative
to the lower border is a result of genetically
determined condylar growth( both in
magnitude & in direction).

Lavergne and Gasson, define rotation as:
"positional" and ''morphogenetic.“
Morphogenetic rotation of the mandible
concerns the shape of the mandible itself,
while
Positional rotation deals with the position
of the mandible within the head
They found the working mechanism in the
forward or backward inclination of the
ramus, thereby elongating or shortening the
mandible.

Second option-Hunterian concept
or Morphogenetic rotation
• Lavergne and Gasson, using their own
“morphogenetic rotation” which is essentially
the same phenomenon as ‘ ‘intramatrix rotation
,’ ’ postulate that this phenomenon is a
compensating mechanism which is capable of
enlarging
or reducing mandibular length as
measured along the condylion-pogonion
diagonal.

Lavergne and gasson concluded that:
• Anterior rotation of the mandible is associated with a vertical or even
anterior condylar growth direction and a marked closure of the gonial
angle and these minimize the effects of mandibular growth.

BJORK’S APPROACH HUNTERIAN CONCEPTION
TWO METHODS OF SUPERIMPOSING THE
MANDIBLE

DIBBETS’ CONCEPT:
⮚Bjork & Skeiller postulated that “intramatrix rotation” is an
expression of remodeling at the lower border of mandible and
assumed that the rotation occurred in the corpus of mandible.
⮚Lavergne and Gasson on the other hand contended that the rotation
affected the ramus and the gonial angle and, consequently, the length
of the condylion-pogonion diagonal.

Gave a third interpretation which is based on two hypothetical
divergent patterns of growth.
Third option - Dibbets

1.CIRCULAR GROWTH PATTERN
 Condylar growth as a segment of a circle with its center at the chin.
 The whole mandible then rotate around itself within its periosteal
contours.
 It results in only intramatrix rotation and marked absence of actual
enlargement of mandible.

⮚Comparing the extremes, Dibbets deduced that “intramatrix rotation” is
capable of offsetting and of neutralizing growth to a substantial degree.
2. LINEAR CONDYLAR GROWTH PATTERN
⮚It occurs without any “intramatrix rotation” and maximum
enlargement of mandible.
⮚Most children will be observed to fall in between these two postulated
extreme patterns.

⮚Dibbets introduced the concept of counterbalancing rotation
which tries to offset condylar growth increments, which would
otherwise throw the mandible out of its established equilibrium
with its associated skeletal units (that is the maxillae).
⮚Thus, counterbalancing rotation is a mechanism that:
1. Neutralizes growth, and
2. Results in selective enlargement of mandible.
COUNTERBALANCING ROTATION

Counterbalancing Proportion
It is the quotient between mandibular and condylar
incremental growth and is expressed as a
percentage.
Condylar growth and mandibular growth are
weighted in relation to one another.
The proportion gives a percentage of condylar
relocation that has contributed to actual mandibular
enlargement.
94
J. M. H. Dibbets. Mandibular rotation and enlargement. Am. J. Orthod. Dentofac. Orthop. July
1990 ;98:29-32.)

Counterbalancing =
proportion
Growth of articulare to pogonion
Condylar incremental growth
×100
Mandibular growth =
pg-Ar2 – Pg-Ar1
Condylar growth – Ar1 – Ar2

According to the concept of congruous mandibular growth
the proportion should be 100%.
But study done by Dibbets shows that it ranges from 50% to
90%.
This percentage strongly correlates type of malocclusion.
Class III- 85%
Class I -76%
Class II Div 2-59%
Class II Div 1-65.5%
It is apparent that an incongruity often exists between the
condylar growth and the direction of enlargement of the
anatomic mandible.
96

SCHUDY’S CONCEPT:
⮚Rotation of the mandible is the result of disharmony between vertical
growth and antero-posterior growth or horizontal growth of jaws.
⮚He described two types of growth rotation of mandible:
CLOCKWISE
ROTATION
COUNTERCLOCK
WISE ROTATION

▪ Counter-clockwise Rotation
If the condylar growth is greater than
vertical growth in the molar area, the
mandible rotates counterclockwise and
results in more horizontal change of chin
and less increase in anterior facial height.
▪ Clockwise rotation if vertical growth in
the molar region is greater than at the
condyles, the mandible rotates clockwise
resulting in more anterior facial height.

CLOCKWISE ROTATION
⮚Vertical growth in the molar region is
greater than that at the condylar growth.
⮚Increase in anterior facial height.
⮚Less horizontal change in chin.
⮚Extreme condition - open bite.

⮚Growth at the mandibular condyles produces a forward component of
chin(horizontal growth), not a downward and forward component.
⮚The vertical components of facial growth are:
▪Growth at the nasion and corpus of
maxilla gets the palatal plane down.
Growth of the maxillary posterior
alveolar processes causing the
teeth to move away from the
plane;
▪Growth at the mandibular posterior
alveolar processes causing the molar
teeth to move occlusally.

102 Vertical ‘elements’ of growth
Growth at the condyles =
I- AP growth of nasion.
II- Vertical growth of corpus of maxilla.
III-Vertical growth of maxillary alveolar process.
IV-Vertical growth of mandibular alveolar process.
SCHUDY’S CONCEPT

103 Posterior growth analysis
 Ratio between the vertical
and horizontal growth.
 A=I+II+III+IV

⮚The dorsal migration of glenoid fossa tends to cancel out the
growth of the condyles in many cases.
⮚The vertical growth of anterior alveolar processes does not seem to
have an appreciable effect on facial height.
⮚It merely expressed in varying degree of overbite.
⮚When vertical growth exceeds horizontal growth (condylar growth),
pogonion cannot keep pace with the forward growth of the upper
face and the mandibular plane must become steeper.
 The final vector of growth of chin is a resultant of struggle
between horizontal growth and vertical growth.

⮚The condylar growth is greater than
vertical growth in the molar area.
⮚This rotation is nearly always
accompanied by a forward movement of
pogonion and an increase in the facial
angle.
⮚It shows more horizontal change in the
chin and
⮚Less increase in anterior facial height.
COUNTERCLOCKWISE ROTATION

 This flattening of the mandibular plane tends to increase the vertical
overbite and renders vertical overbite corrections and retention more
difficult.
 Size of the gonial angle has an important influence upon the degrees of
resultant counterclockwise rotation.The smaller the gonial angle ,the
greater rotation is produced for each mm of forward movement of the
pogonion.
 An obtuse gonial angle compensate for a short ramus and corpus i.e. the
gonial angle helps to compensate for length

⮚Schudy states that the mandible should not be considered as a
single growth entity, but rather as four entity:
⮚Growth of
the condyle
and ramus
Growth of
the posterior
alveolar
process
⮚Growth of
the corpus
⮚Growth of
the anterior
alveolar
process

⮚This unique bone may grow quite uniformly in all directions or
in any one of its aspects which may grow out of proportion to
the rest of the bone.

PROFFIT’S DESCRIPTION OF ROTATION:

TERMINOLOGY BY PROFFIT:
Internal rotation: It is the rotation of
mandibular core relative to cranial base.
External rotation: It is the rotation of
mandibular plane relative to core of the
mandible.
Total rotation: It is the rotation of mandibular
plane relative to cranial base.

• Internal rotation is the rotation which
occurs in the core of the jaw.
• In mandible, the core is the bone
which surrounds the inferior alveolar
nerve.
• There are two contributors to internal
rotation , namely
 matrix rotation; and
 intramatrix rotation
INTERNAL ROTATION

 Matrix rotation occurs around the
condyle while intramatrix rotation is
centered within the body of mandible.
 Matrix rotation is the rotation of
mandibular plane related to cranial
base.
 Intramatrix rotation is the rotation of
bony element within its periosteal
matrix which occurs in the corpus or
the core of the mandible.

On an average there is about 15 degrees of total or
summary rotation from age 4 to adult life.
Of this about, 25% results from matrix rotation and
75% from intramatrix rotation.

EXTERNAL ROTATION:
 Rotation caused by the surface changes and
and the alteration in the rate of tooth
eruption is called as external rotation.
 These surface changes include resorption in
posterior part of the lower border of the
mandible, while the anterior aspect of lower
border of mandible is unchanged or
undergoes slight apposition.

 Rotation of mandibular plane relative to core of the mandible.
 This external compensation in an average growing adult is
about 11 to 12 degrees.

TOTAL ROTATION
 It is the net resultant
rotation including the
internal and external
rotation.
 The difference between
the internal and external
rotation accounts for 3 to
4 degrees reduction in
mandibular plane angle
during growth in
adolescence.

⮚Rotation of mandible decides the vertical proportions of the face.
⮚Horizontal growers have a
-Short lower anterior facial height.
-And they are predisposed to having a deep bite.
-Crowding of anterior teeth.
-Low mandibular plane angle.
⮚Vertical growers have a
- long lower anterior facial height.
-And they are predisposed to having a open bite
-Dental protrusion.
CLINICAL IMPORTANCE

PROFFIT : Total Rotation = Internal - External
rotation rotation
BJORK : Matrix Rotation = Total - Intramatrix
rotation rotation
SOLOW : Apparent Rotation = True - Angular
rotation Remodelling

Terminology by Solow & Houston:
True Rotation : rotation of mandibular core relative to
cranial base.
Apparent Rotation : rotation of mandibular plane relative
to cranial base.
Angular Remodeling of Lower Border : rotation of
mandibular plane relative to core of mandible.

 3 changes with respect to growth rotation of
mandible:
TRUE ROTATION OF MANDIBLE:
 Rotation of mandibular body relative to anterior
cranial base.
This is the rotation originally described by Bjork
(1955) and subsequently called ‘Total rotation’by
Bjork and Skeiller (1983).
It is the fundamental rotation that may occur in the
relationship between mandible and cranial base.
Beni Solow and William J. B. Houston. Mandibular rotations: concepts and terminology. European Journal of
Orthodontics 10(1988) 177-179

APPARENT ROTATION OF MANDIBLE:
 The angular change of mandibular line relative to anterior
cranial base.
 True Rotation + Remodelling. ( Matrix rotation)
 This is the type of change reported by Lande (1952) and
which was called 'matrix rotation' by Bjork and Skieller (1983).
(1983). It is the angular change that is apparent from
conventional cephalometric analysis. It is the result of true
mandibular rotation and remodelling at the lower border of
the mandible.
Beni Solow and William J. B. Houston. Mandibular rotations: concepts and terminology. European Journal of Orthodontics 10(1988)
177-179

ANGULAR REMODELLING OF LOWER BORDER:
• Angular change of mandibular line when mandible is registered on
implants or stable trabecular structures. ( Intramatrix rotation)
• This is a measure of the amount of remodelling that occurs at the
mandibular border.
• From an aetiological point of view it seems logical to assume that this
remodelling occurs, for instance, when the true rotation of the mandible
forces the gonial region against the pterygo-masseteric muscular sling, a
mechanism which probably led Bjork and Skieller (1983) to suggest the
term 'intramatrix rotation’.

3/1/2024
GROWTH ROTATIONS
125
BJORK SOLOW AND
HOUSTON
PROFFIT
Rotation of
mandibular core
relative to cranial
base
Total
rotation
True rotation
Internal
rotation
Mandibular plane
relative to cranial
base
Matrix
rotation
Apparent
rotation
Total
rotation
Mandibular plane
relative to the core
of the mandible
Intra matrix
rotation
Angular
modeling of
lower border
External
rotation

PREVIOUS SESSION
o INTRODUCTION
o TERMINOLOGIES
o BJORK STUDY/IMPLANT RADIOGRAPHY
o MANDIBULAR GROWTH ROTATION
o BJORK STUDY
o STRUCTURAL SIGNS OF GROWTH ROTATION
o CLINICAL IMPLICATIONS
o BJORK AND SKEILLER’S METHOD

CONTENTS
 GROWTH ROTATION OF MAXILLA
 JAW ROTATION AND TOOTH ERUPTION
 MUTUAL RELATIONSHIP OF ROTATING JAW BASES
 STUDIES ON GROWTH ROTATION
 OBSERVATIONS BY PETROVIC AND STUTZMAN
 PREDICTION OF MANDIBULAR GROWTH ROTATION

 CEPHALOMETRIC DIAGNOSIS IN GROWTH ROTATION
 MECHANISM OF ROTATION
 ENLOW’S CONCEPT OF GROWTH ROTATION
 CLINICAL ASPECTS
 CONCLUSION
 CEPHALOMETRIC ANGLES

GROWTH ROTATION OF MAXILLA
• Generally, the vector of maxillary growth is in anterior and inferior
direction ( downward and forward displacement).
• Due to the varying growth activities of middle cranial fossa, the sutural
attachments of midface and surface remodeling, the maxilla tends to
get rotated by displacement.
• If this rotational pattern is extreme, result in canting and misfit of the
palate and maxillary arch.

Bjork and Skeiller (1972) studied this rotational
growth of maxilla with the help of implants.
Core of the maxilla - above the alveolar process.
Functional process - alveolar process, bones
surrounding air passages.

Implant sites selected by Bjork include:-
•Inferior to anterior nasal spine
•In the zygomatic process of
maxilla(lateral implant)
•At the border between the hard palate
and the alveolar process medial to first
molar.

⮚The lateral implant placed on anterior and posterior contour of
zygomatic process seems to give best results when compared to other
sites.
⮚It is less easy to divide the maxilla into a core of bone and a series of
functional processes.

⮚If the implants are placed above the maxillary alveolar process,
however, one can observe a core of the maxilla that undergoes a
small and variable degree of rotation.
⮚Bjork and Skeiller introduced various terminologies to describe the
growth rotation of maxilla.

INTERNAL ROTATION
• The rotational pattern that occurs in the
core of maxilla.
• This is also called as intramatrix
rotation.

EXTERNAL ROTATION
• Simultaneous to internal rotation of maxilla, varying degrees of
resorption of bone on the nasal side and apposition of bone of the
palatal side in anterior and posterior parts of the palate also takes place.
• All these changes collectively contribute to external rotation.
• This external rotation is usually opposite in direction and equal in
magnitude to the internal rotation, so that the two rotations cancel each
other and the net change in jaw orientation, as evaluated by the palatal
plane is zero .

• Depending upon the different degrees of combination of internal
and external rotations, Bjork and Skeiller observed two types of
rotational growth.
The terminologies used are forward and backward rotation.

FORWARD GROWTH
ROTATION
 This condition occurs either due to
excessive internal rotation or lack of
normal compensatory external rotation
or a combination of both.
 The maxilla is inclined upwards and
forward, the anterior end is tipped up.
 This is known as ante inclination as
coined by Schwarz.

• This forward rotation also tends to tip the incisors
forward, increasing their prominence.
• The extent of forward tipping in relation to anterior
cranial base is given in degrees by Schwarz.

• The inclination angle is not measured
directly but is defined as the angle
between the Pn-perpendicular and the
palatal plane (J angle).
• In ante inclination, this angle is greater
than 85 degrees whereas in normal
inclination, it is approximately equal to
85 degrees.

BACKWARD ROTATION
• In this, there is downward and backward
tipping of the anterior end of the palatal
plane and the maxillary base.
• It is called retroclination – by Schwarz
• In this type of maxillary displacement, the jaw
bases are translated posteriorly and upper
incisors appear to tip lingually.

• J angle is less than 85 degrees.
• Though the growth related rotation does occur in the midface,
extreme rotational patterns are often compounded with various
environmental disturbances.
• According to Linder-Aronson, Lowe, and Woodside, various
environmental influences such as neuromuscular dysfunction,
occlusal forces can cause extreme rotation of jaw bases.

JAW ROTATION AND TOOTH ERUPTION
 By means of implant method, the eruption path of the teeth
have been analyzed by Bjork and Skeiller in relation to facial
development and growth of the jaws.
 The rotation of the face necessitates compensatory adaptation
of the paths of eruption of the teeth.
 When there is full compensatory occlusal development, the
lower incisors retain their inclination in the face practically
undisturbed, irrespective of the rotation of the jaw, because of
a forward tipping on the jaw base.

⮚The posterior teeth in the lower jaw, too, involved in this
compensatory occlusal development and are, likewise, tipped
forward.
⮚The lower dental arch then shifts forward on the jaw base
without undergoing any appreciable change in shape.
⮚The intermolar inclination remains comparatively constant as
the lateral teeth in both jaws follow the rotation of the face.

⮚Eruption of the upper molars appeared to be a combination of
active eruption of the teeth in the jaw bone and bodily rotation of the
maxilla.
⮚In forward rotation of maxilla, the incisors tend to tip forward
increasing their prominence, while in the backward type of rotation,
the anterior teeth are directed more posteriorly, relatively decreasing
their prominence and uprighting them.
⮚The eruption path of mandibular teeth is normally upward and
forward.

⮚In excessive forward rotation in short faced individuals,
the incisors to be carried in to an overlapping position ,
hence there is tendency towards deep bite malocclusion.
⮚Due to the lingual movement of lower incisors, there is
reduction in arch length because of rotational changes
and this is more evident in mandible when compared to
the maxilla.

⮚Numerous authors have contributed to the understanding of
growth rotations through implant studies.
⮚Various methods and studies have been described to predict
the direction and the amount of growth rotation of mandible.
STUDIES ON GROWTH ROTATIONS

SKEILLER, ARNE BJORK AND LINDE-
HANSEN METHOD
⮚This is a longitudinal cephalometric study with the aid of implants.
⮚They chose 21 Danish children both girls and boys who never had
orthodontic treatment.
⮚After placing the implants at specific sites, two X rays were taken
▪ 1st- 3 years before the pubertal growth spurt,
▪ 2nd- 3 years after pubertal growth spurt.
Laurel R. Leslie et al. Prediction of mandibular growth rotation: Assessment of the Skieller, Björk, and Linde-Hansen method. American Journal of
Orthodontics and Dentofacial Orthopedics December 1998:Pg no :659-667.

Initially, they chose 44 independent morphologic variables in the
mandible for superimposition.
From them 4 variable were used which gave the best prognostic
estimate of mandibular growth rotation.

2. Intermolar angle (MOLs-MOLi)
3. Shape of the lower border
(ML1-ML2)
4. Inclination of the symphysis
(CTL-NSL)
Index I was found to be more accurate than the
other two and was chosen as the first
independent variable.
1. Mandibular inclination represented by
three alternatives:
✔Index I –proportion between posterior
and anterior facial height.
✔Lower gonial angle(GOL)
✔Inclination of the lower border(NSL-
ML1)

MORPHOLOGICAL OBSERVATIONS SEEN IN FORWARD AND BACKWARD
ROTATIONS BY SKEILLER,ARNE BJORK AND LINDE-HANSEN

METHOD BY TODD, RAM S
NANDA, FRANS CURRIER,
SURENDAR K NANDA
⮚The purpose of this study was to
determine whether symphysis morphology
could be used as a predictor of direction of
mandibular growth rotation.
⮚They used lateral X rays of 115 adults for
this study.

⮚The mandibular symphyseal dimensions studied included:-
✔Symphyseal
height
✔Symphyseal
angle
✔Symphyseal
depth
✔Symphysis
ratio-
Height/Depth
ratio

CEPHALOMETRIC
MEASUREMENTS USED
TO QUANTIFY
SYMPHYSIS
MORPHOLOGY

⮚A tangent is drawn passing through point B.
Then a line grid was constructed with the lines
of the grid parallel and perpendicular to the
constructed tangent line.
⮚The superior limit of the symphysis was taken
at point B, and the most inferior, superior,
anterior and posterior outline of the symphysis
are marked and thus grid was completed.

INFERENCES OF THIS STUDY:
⮚This study concluded that the mandible with anterior growth rotation was
associated with small height, large depth, small ratio, and large angle of the
symphysis.
⮚Conversely, a posterior growth rotation was associated with a large height,
small depth and increased ratio, small angle of the symphysis.
⮚Men possess a stronger relationship between symphyseal morphology and
the direction of mandibular growth when compared to women.

⮚Women also showed the same relationship as the men between symphysis
height, depth, ratio, and angle to the direction of the mandibular growth.
⮚Symphysis showed continuous change up to adulthood in both male and
female, with the female subjects having smaller and earlier changes
occurring than compared to male.
⮚The symphyseal height, depth, height ratio, increased while symphyseal
angle decreased with age.
 Symphysis ratio was strongly related to the direction of mandibular
growth in men.

•Mandibular alveolar bone organ
cultured for 3 days, showed bone
turnover adjacent to mandibular 1st PM,
> In anterior growth rotation.
•Thus when orthodontic force is
applied, the magnitude of force
application increase in alveolar bone in
ant. rotating mandible
•Alveolar bone formation is higher on mesial
side and resorption more marked on distal side
in ant .rotating mandible
This implies that first premolar undergoes a
physiologic distalization rather than the
mesialization during growth in the anteriorly
rotating mandible
OBSERVATIONS
OF PETROVIC
AND
STUTZMAN

While in posterior growth rotation,the
first premolars undergo more
mesialization
•In anterior growth rotation, the response
of prechondroblasts , subperiosteal and
trabecular osteoblast, muscles of
mastication are more responsive to
hormones.
•Clinically consistent that thicker
mandible is found in anterior rotators
and gracile ramus and corpus seen in
extreme post.rotation.

PREDICTION OF MANDIBULAR GROWTH
ROTATION
 If an attempt is made to assess the growth trend at an early
stage, this information can be used in designing the
treatment of evaluating the problems that may arise before
growth is complete.
 In spite of several attempts in recent years, there is still
doubt as to the extent to which growth of the face as a
whole can be predicted from a single profile radiograph.

 In an attempt to analyse the possibility of predicting growth of
single facial dimension, Bjork and palling correlated linear
and angular measurements at pubertal age with residual
growth of these dimensions up to adulthood. These
correlations were however found to be low.
 Hixon suggested that the best estimate of an adult facial
dimension for a given child is to use the dimension
presented by the child and add to that the remaining
average growth for the group. This method was adopted
by several authors. However, this estimate would fit an
average but not an extreme growth pattern, where
prediction from a clinical point is more important.

 Lavergne tried to individualize the prediction by a subdivision
according to the morphogenetic types.
 Ricketts arcial method of long range growth prediction uses
geometric procedures to gain information about the growth
pattern of the mandible.
 A computerized system for short range facial growth
prediction and treatment simulation, based on longitudinal
observations of individual growth rate and direction has been
developed by Bjork-Jorgensen.

A growth analysis consists of essentially 3 items:
1. assessment of the development in shape of the face.
2. assessment of whether the intensity of the facial growth is
high or low.
3. evaluation of the individual rate of maturation.

According to Bjork
In the assessment of shape there are three methods:
1.Longitudinal method
2.Metric method
3.Structural method
I. LONGITUDINAL METHOD
• Consists of following the course of development in annual cephalometric
cephalometric films.
• It is for the subjects displaying the most pronounced changes in facial
forms that the diagnosis of growth pattern is important.

Limitation
1. Pattern of growth is not constant and may be changed later.
2. Permits observation of changes in the sagittal jaw relation with
growth and those occurring in the vertical jaw relation are
masked.
Changes in the vertical positions of the jaw in the form of
rotation appear to be smaller when assessed with conventional
longitudinal X-ray films by using the base of the mandible as
the reference than when assessed with the help of implants.

• Analysis of vertical development of the face may done using
natural reference structures in the mandible by
superimposing two radiographs taken at different ages and
orienting reference to these structures, one may estimate
the growth pattern of the mandible by reading the angle
between the Nasion sella lines for the two ages.

Longitudinal method of analysis
of mandibular growth rotation
from the angle between the N-S
lines ,at two stages after
superimposition of the
mandibles on natural reference
structures.

2. METRIC METHOD
 Aims at a prediction of facial development on the basis of facial
morphology, determined metrically from a single X-ray film. However,
prediction of development from size and shape at childhood is not
very accurate.
 The growth in length of the mandible during adolescence could not
be judged from its size before puberty .
 The changes in shape of the face during adolescence, expressed in
terms of angular measurements also weekly correlated with the shape
shape of the face at 12 years which is the age at which treatment is
instituted.

3. STRUCTURAL METHOD
 Is based on information concerning the remodelling process
of the mandible during growth, gained from the implant
studies.
 The principle is to recognize specific structural features that
that develop as a result of remodelling in a particular type of
mandibular rotation.
 A prediction of the subsequent course is then made on the
assumption that the trend will continue.

Gonial Angle and mandibular rotation
 The size of Gonion angle influence the number of degree of counter
clockwise rotation of mandible.
 The smaller the gonion angle, the greater the rotation is produced for
for each mm of forward movement of pogonion
Facial divergence and mandibular rotation
 The degree of facial divergence (SN – MP) has a significant bearing on
on mandibular rotation.
 Larger SN-MP angle, the more the mandible tends to become steeper
steeper and the chin moves more backward.
 The smaller the angle, the greater the tendency of the mandible to
become flat and the chin to grow forward.

CEPHALOMETRIC ANGLES
1. Basal plane angle
Angle of inclination of the
mandible to the maxillary
base
Mean - 25°

2.ANGLE OF
INCLINATION ( J angle )
Angle between PN line and the
palatal plane
Mean - 85°

3.SN-MP ANGLE
Inclination of the
mandible to the
anterior cranial base
Mean - 32°

4. GONIAL ANGLE
Angle between ramus &
corpus
Mean – 128°+/-7°

CEPHALOMETRIC DIAGNOSIS IN GROWTH
ROTATION
Various cepahlometric analysis that are routinely
used clinically include:-
⮚Jarabak’s cephalometric analysis, predicted the
direction of mandibular growth, including the
saddle angle, articular angle, gonial angle.
• With the sum of these three angles greater
than 396 degrees, posterior mandibular growth
pattern was observed while less than 396
degrees was associated with anterior
mandibular growth.

⮚Ratio of the posterior to anterior facial height of 56-62
percent indicated a posterior growth rotation, where as a
ratio of 65-80 percent indicated an anterior growth
tendency.
⮚If the anterior facial height is greater, the gonial angle
adapts to this requirement by increasing.

• The perpendicular from Go to Sn
divides the gonial angle into a
smaller posterior(Go1) and a larger
(Go2)parts.
• If gonial angle opens out posteriorly
with large Go1 (posterior rotation),
basal plane angle becomes small.
Se-N
Gonion

• If the gonial angle opens out anteriorly
with small Go1(anterior rotation), basal
plane angle becomes increased.
 The basal plane angle is the angle
between the palatal plane and
mandibular plane.
• It defines the inclination of the mandible to
the maxillary base.

• It determines the direction of rotation of the mandible.
• Mean angle= 25 degrees
• Increased basal angle –mandible rotated backwards(vertical growth).
• Decreased basal angle-mandible rotated forwards(horizontal growth).
• The basal plane angle is divided into two by the occlusal plane.
• The upper angle is 110 degrees and lower is 14 degrees.

• The lower angle is important for assessing the prognosis for opening
the bite.
• If it is large, the prognosis is good.
• If it is small the prognosis is poor.
 Other angles that tell about the rotation of mandible include the Y
axis ,SN-MP,FH-MP angles
 Various structural signs of extreme growth rotations can elicited from
the radiographs.

GROWTH DIRECTION-ROTATION OF THE MANDIBLE
TYPE OF ROTATION IN RELATION TO ANTERIOR CRANIAL BASE:
Parallel displacement = Neutral growth type
Forward rotation = Horizontal growth type
Backward rotation = Vertical growth type
Thomas Rakosi et al .Color atlas of dental medicine .Orthodontic Diagnosis. Pg no :192-197.

HORIZONTAL ROTATION VERTICAL ROTATION
Upward and forward rotation during the
growth(horizontal growth pattern).
Downward and backward rotation of the
mandible increases(vertical growth pattern)
Deep bite Open bite
With increased horizontal rotation of the
mandible,the difference in length between
anterior and posterior facial height is decreased.
development of anterior facial height is
disproportionately greater
Ramus-long and wide short and narrow ramus
mandibular symphysis-thick. thin symphysis
base of the mandible-high.
Straight mandibular canal
small mandibular base
Curved mandibular canal
Condylar growth dominates Sutural-alveolar growth is increased compared
to the condylar region.
Less prominent antegonial notching Prominent antegonial notching

MANDIBULAR ROTATION AND FACIAL PROFILE
Reduced lower facial height is characteristic for the profile contour in a
patient with enhanced horizontal mandibular rotation.
Thomas Rakosi et al .Color atlas of dental medicine .Orthodontic Diagnosis. Pg no :192-197

CEPHALOMETRIC FINDINGS IN HORIZONTAL MANDIBULAR
ROTATION

CEPHALOMETRIC FINDINGS IN VERTICAL MANDIBULAR
ROTATION

ROTATION OF THE MAXILLARY BASE
Classification of rotation of the maxilla in relation to
the anterior cranial base :
Normal
inclination
Retro
inclination
Ante
inclination

MAXILLARY INCLINATION AND OCCLUSAL FINDINGS
Maxillary rotation influences the amount of overbite and the clinical appearance of the inclination
of the upper anterior teeth.

CEPHALOMETRIC FINDINGS IN MAXILLARY
RETROINCLINATION
The inclination angle is not correlated to the mandibular growth pattern

CEPHALOMETRIC FINDINGS IN MAXILLARY
ANTEINCLINATION

MUTUAL RELATIONSHIP OF ROTATING JAW
BASES
⮚When BJORK introduced the concept of rotation, the concept was
widely extended and misused.
⮚In an attempt to clarify this situation, a classification was proposed
whereby a clear cut distinction between the morphogenetic and
positional rotations was presented.
⮚Morphogenetic Rotation of the mandible concerns the shape of the
mandible itself,

While Positional Rotation
deals with the position of the
mandible within the head
Superimposition done on line
through condylion and
pogonion.
The angle formed between the
2 implant lines-degree of
morphogenetic rotation.
Similar to Bjork’s intramatrix but
not identical

According to Lavergne and Gasson (1982) the mutual rotation of
the upper and lower jaw can be of following 4 types:
CONVERGENT
OF JAW BASES
DIVERGENT ROTATION
OF JAW BASES.
CRANIAL ROTATION OF
BOTH JAWS.
CAUDAL ROTATION OF
BOTH JAWS.

1. CONVERGENT ROTATION.
⮚ Both maxilla and mandible converge
towards each other.
⮚ Thus creating a true severe deep bite that
that is difficult to manage.

2. DIVERGENT JAW BASES.
⮚ In this type, the Maxilla and mandible
move away or diverge from each other.

3. CRANIAL ROTATION OF
BOTH THE BASES.
⮚Both maxilla and mandible rotates upward
and forward.
⮚Horizontal growth pattern occurs in a
relatively harmonious manner wherein
rotation of maxilla occurs upward and forward

4. CAUDAL ROTATION OF BOTH
BASES.
⮚Both the maxilla and mandible rotate
downward and backward.
⮚Similar to cranial rotation of jaw bases, this also
occurs in harmonious manner wherein the
downward and backward maxillary rotation
offsets the open bite created by downward and
backward mandibular rotation.

CEPHALOMETRIC FINDINGS IN DOWNWARD
ROTATION OF THE JAW BASES

CEPHALOMETRIC FINDINGS IN DIVERGENT
ROTATION OF JAW BASES

203
Enlow’s concept.
 The ramus has a sequence of remodeling changes to
provide for 4 basic functions.
Elongation of the corpus.
Accommodates for horizontal growth of middle cranial
fossa and pharynx.
Accommodates for vertical growth of nasomaxillary
complex.
To position the mandibular corpus in proper position to
maxillary corpus.

204
 The ramus provides intrinsic capacity for adaptation .
 If its adequate then class I occlusion results.
MANDIBULAR ROTATIONS
Displacement Remodeling

Displacement type of rotation
 Mandible rotates on the condylar pivot.
 The primary reason for this is to adjust to the vertical size of midface
and alignment of middle cranial fossa
 Rotates forward to meet short mid face or closed bicranial flexure.
 Rotates backward to meet vertically increased mid face or open
bicranial flexure.
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205

206
 Changes in the junctional contact with the cranial floor and
maxilla.
 Cranial base angle -
Open-downward and backward rotation of mandible.
Closed-forward rotation.

208
Short nasomaxillary complex-forward rotations

209 Long nasomaxillary complex –backward
rotations

Remodeling type
Occurs at angle between corpus and ramus
Occurs due to resorbtive and depository changes
occurring at this junction.
It basically leads to More upright ramus alignment
relative to corpus accommodating a vertically
lengthened mid face.
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211

212
 Mandible has to remodel to-
 1.To produce a more upright ramus alignment
relative to the corpus.
 This accommodates the continued vertical growth
of naso-maxillary region and the eruption of
permanent dentition.
 2. To provide ramus-corpus angular adjustments to
accommodate the effects of the whole mandible
displacement rotations.
 e.g., : of the displacement rotation causes more
upward & forward alignment of the mandible as a
whole than the remodeling rotation, partially or
completely offsets this by opening the ramus-corpus
angle.

213
 Opening and closing of the gonial angle compensates for
extreme forward or backward rotation.

214 Ramal remodeling
Ramus moves posteriorly-
increasing the length of the
corpus.
Grows horizontally to match
the growth of the pharyngeal
space.
Ceases when growth stops

215
 2nd type of remodeling.
 Makes ramus more upright but does not increase the
horizontal dimension.

On contrast a downward and backward whole-mandible
displacement can be offset by closing the ramus-corpus angle by
remodeling rotation.
 It is necessarily a function of the ramus, rather than the corpus to
provide the basic remodeling changes leading to a more open/more
closed ramus-corpus angle.
 The same combinations of resorption and deposition in the various
parts of the ramus that bring about relocation of the ramus in
posterior direction also serve to remodel and adjust the RAMUS
CORPUS ANGLE.

 As growth proceeds, the utilization of these ramus growth changes
to alter ramus corpus alignment decreases and finally ceases.
 Another remodelling mechanism takes over.
• Condyle previously growing in a more vertical direction now
begins to grow anteriorly as well.
• This anterior condylar growth is complemented by bone
deposition superiorly on the anterior border of the ramus.
• Resorption continues inferiorly on the anterior border to provide
space for molars.
• A converse combination of remodelling takes place on the
posterior border.

Clinical Implications
1. Downward alignment of the whole mandible at the condylar pivot  has
a mandibular retrusive effect.
Only Corpus  mandibular protrusive effect.
Upward alignment of the whole mandible  Mandibular protrusive effect
effect
Only corpus  Mandibular retrusive.
2. The more extreme the rotation of the mandible during growth, the greater
the clinical problems that is presents.
 Extreme rotation greatly influence the path of eruption of the teeth,
magnitude of tooth eruption, anteroposterior position of incisor teeth.

 In normal growth, maxilla usually rotates a few degrees
forward.
 It may be normal but usually the maxilla rotates slightly
backward.
Forward Rotation of maxilla  Tends to tip the incisors
forward and increase their
prominence.
Backward Rotation of maxilla  Directs the anterior
teeth more posteriorly relatively up righting
them and decreasing their prominence.
During adolescence about half the total maxillary teeth
movement is due to rotation of maxilla (Teeth moved along
with the jaw - Translocation).
3.Interaction between jaw rotation and tooth eruption

• Path of eruption of mandibular teeth -Upward and forward
Forward rotation of growth - Lingual positioning of
mandibular incisors relative to mandible.
Lingual positioning of mandibular incisors
Molars migrate further mesially during growth than the incisors
Decrease in the arch length
• The forward rotation progressively uprights the incisors, causing a
tendency toward crowding.( brachyfacial individuals)

LINGUALLY PLACED INCISORS MESIAL MOLAR MIGRATION

 Incase of pronounced forward rotation, there is a major risk of deep
bite developing.
 In the case of backward rotation, opening of the bite is difficult to
prevent during treatment so in the case of extreme forward rotation a
stabilizing appliance like bite plane is introduced before puberty and
continued until growth completion.
 According to Bjork, it is advisable to delay orthodontic extractions
until beginning of pubertal growth spurt.

4.Facial patterns :
SHORT FACE PATTERN
Excessive forward rotation of mandible during growth.
Short Anterior LFH
Horizontal palatal
plane
Square jaw
(Mandible)
Square gonial
angle
Low MPA
Deep bite &
crowding
Excessive forward rotation may be due to :
(i) Increase in internal mandibular rotation
(ii) Decrease in external rotation

LONG FACE PATTERN (INCREASED LAFH)
Backward rotation of mandible
Anterior open
bite
Increase
MPA
Palatal plane
rotates down
posteriorly
Mandibular
deficiency
Mandibular backward rotation result primarily from:
 Lack of normal internal rotation
 Or even backward internal rotation
 The internal rotation is primarily matrix rotation (Cor- condyle)
and not intramatrix rotation.
 Backward rotation of mandible also occur in patients with
abnormalities or pathologic changes in TMJ

5.According to schudy :
Clockwise rotation of mandible (effect upon treatment)
 Would not help reduce ANB angle
 Not aid in correction of class – II molar relation.
 Would tend to help correct the vertical overbite of incisors and
maintain it.
Counter clockwise rotation
 Tends to increase the vertical overbite (deep bite) and renders vertical
overbite correction and retention more difficult.
 According to schudy the condylar growth versus vertical growth
determines the mandibular rotation.
Orthodontic treatment does not stimulate growth at the condyles. It is
only the vertical increments that we may possibly alter with
orthodontic treatment.

 Inhibition of growth of vertical increments will have the same
effect as stimulating growth at the condyle.
 So if vertical growth is deficient we try to stimulate it.
(Cervical pull head gear, class II elastics). If vertical growth is excessive
we try to inhibit it (Inhibit downward growth of maxillary molar – high
pull head gear).
6. It is also important to identify the relationship between jaw base
rotations and occlusal findings (e.g., Inclination of upper anteriors and
lower anteriors and over bite) and accordingly plan the treatment,
especially if the patient is in growth phase.

7. Combinations of maxillary and mandibular rotation and its clinical
implications (Lavergne and Gasson 1982). The combinations are very
important for occlusal relationship.
 Convergent rotation of jaws during growth.
A deep bite which is very difficult to correct even by functional
methods.
 Divergent rotation  skeletal open bite often results. Severe cases
require orthognathic surgery.
 Rotation in the same direction :
The occlusal relationship is maintained normally in most situations
(e.g., deep bite avoided in cranially directed rotation of both jaws).

8. Upward and forward tipping of anterior maxilla is often observed in
confirmed mouth breathers.
9. Mandibular rotation is caused by both growth dependent and
functional influences, only functional influences can be altered
therapeutically while growth can only be guided so the rotation of
mandible can be only moderately influenced therapeutically.
Generally the inclination of maxillary base is stable and no growth
dependent influences seen, thus the inclination can be influenced by
both fixed orthopedic and functional therapeutic techniques.

 The ability of an orthodontist to predict future mandibular growth
would greatly aid in the diagnosis and treatment planning.
 Better therapeutic decisions could be made regarding timing and
length of the treatment, appliance selection, extraction pattern and
possible need for surgery.
 And with it’s knowledge therapy could be truly tailored to the
individual with the possibility of obtaining optimal results in shorter
period of time.
3/1/2024
232 CONCLUSION

 Therefore we should predict future growth changes that occur
thereby avoiding making undesirable changes and can alter
undesirable growth pattern.
⮚The rotation of the mandible during growth appears to be a complex
phenomenon showing annual variations in direction & intensity
⮚Such rotation is not only dependent on mandibular factors, but also
is strongly related to the intensity of growth of both jaws.

 Clinician should confine his effort to correct the abnormal growth
pattern during the process of correcting the malocclusion for better
prognosis

• Proffit W R, Fields H W, Sarver D M. Contemporary Orthodontics
6th edition. New Delhi:Elsevier; 2019.
• Premkumar S. Text book of craniofacial growth. New
Delhi:Jaypee Brother Medical publisher(P) Ltd;2011
• Essentials of facial growth – Enlow & Hans
• Thomas Rakosi et al .Color atlas of dental medicine .Orthodontic Diagnosis.
Pg no :192-197.
• Bjork A. Prediction of mandibular growth rotation. Am J
Orthod.1969;55:585-99.
REFERENCES

• The puzzle of growth rotation – J.M.H. Dibbets, AJO, June 1985, pg.
473-480
• J. M. H. Dibbets. Mandibular rotation and enlargement. Am. J. Orthod.
Dentofac. Orthop. July 1990 ;98:29-32.)
• F.F.Schudy.The rotation of the mandible resulting from growth:Its
implications in orthodontic treatment.Jan 1965;Vol 35 no 1;pg.36-50.
• Beni Solow and William J. B. Houston. Mandibular rotations:
concepts and terminology. European Journal of Orthodontics
10(1988) 177-179

• Robert J. Isaacson, D.D.S., Ph.D., Richard J. Zapfel, D.D.S., M.S.D., Frank
W. Worms, D.D.S., M.S.D., and Arthur G. Erdman, B.S., KS., Ph.D. Effects
of rotational jaw growth on the occlusion and profile . Am. J. Ovtlzod.
September 1977;Volume 72 Number 3;
pg no :276-286 .
• NICOLE GASSON & JEAN LAVERGNE . Maxillary rotation during human
growth: Annual variation and correlations with mandibular rotation.
Acta Odont. Scand. 35,1977;pg no;13-21.
• Bjork A , Skeiller V, Linde-Hansen T. Prediction of mandibular
growth rotation evaluated from a longitudinal implant sample.
AJODO1984;86:5:359-370.

AKNOWLEDGEMENT
Dr. Rajkumar S. Alle
Dr. Shwetha
Dr. Suma. T
Dr. Shashi kumar
Dr. Lokesh
Dr. Kiran
Dr. Siddarth Arya
Dr. Bharathi
Dr. Mayank
Dr.Roshan

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