Growth rotations

Growth
Rotations
By,
Miliya Parveen

Contents:
• Introduction
• Determining rotational growth changes
• Mandibular rotations
-Dr. Arne Björk & Skieller (1983)
- Dr. Arne Björk (1969)
- Dr. William Proffit:
- Dr. F. F. Schudy (1965):
- Dr. Lavergne and Gasson (1976)
- Dr. J.M.H. Dibbets (1985) :
- Dr Robert Isaacson and co‐workers (1977)

• Clinical significance of Rotation :
-Relationship between Condylar growth and Rotations
-Relationship between Dentition and Rotations
-Relationship between Chin position and Rotations
• Prediction of Rotation
-Prediction by the structural method
-Reliability of prediction
• Maxillary rotations
-Maxillary Rotational Patterns:
• Cranial base rotations
• Interrelationship between rotation of skeletal components
• Orthodontics and Rotation
• Treatment protocol
• Conclusion
• References

Introduction:
• For many years, orthodontists
were taught that the mandible
grows upward and backward and
is displaced downward and
forward.
• This led to the idea,
greater amounts of
superior/posterior growth
greater amounts of
inferior/anterior displacements

• While most mandibular growth occurs in the superior and
posterior regions, the superior changes (especially those in the
condylar region) are substantially greater than the posteriorly
directed changes.
• Contradictorily however, many children showing the greatest
anterior chin displacements have condyles that grow anteriorly.
Thus, some hidden factor in mandibular growth must be
active that would explain the forwards displacement of the
chin despite anterior condylar growth.

Determining rotational growth changes:
1. Bjork’s Implant radiography technique
2. Natural occurring landmarks
1. Bjork’s implant radiography technique –
• In 1951, Bjork started a study of 100 children of each sex from
ages 4 to 24 years.
• Tantalum metallic implants are inserted in the jaws to serve as
fixed reference points.

• These reference points are
then used to superimpose serial
radiographs to determine
internal growth changes.

2. Natural occurring landmarks –
• These structures within the mandible are used to superimpose
serial radiographs.
• The lower border of the mandible stays stable during growth
due to extensive remodelling and so cannot be used in evaluating
predicting growth rotations in the mandible.
• Based on his superimpositions, Bjork identified primary and
secondary structures that do not change over time.

Primary Structures:
i. Contour of the chin just
below the pogonion.
ii. The inner contour of the
cortical plate at the lower
border of the symphysis.
iii. Posteriorly, the contours
of the inferior alveolar
nerve canals are stable
throughout growth.
Secondary Structures: Before root development begins, the
lower contour of a mineralized tooth germ provides a
secondary structure that can be superimposed upon.

Mandible Lower
Border
Remodelling Metallic Implants
Ødegaard Angle alpha Angle epsilon Angle gammma
Björk and Skieller Matrix rotation Intramatrix rotation Total rotation
Solow and Houston Apparent rotation Angular remodelling True rotation
Profitt Total rotation External rotation Internal rotation
Mandibular Rotations:
• Through the years, subsequent authors have used different terms
to describe the same, or similar entities and different concepts of
rotations have been described by the pioneers.

1. DR. ARNE BJÖRK & SKIELLER (1983) :
• Bjork showed that the mandibular corpus rotates during growth
but the shape is kept stable by the associated surface remodelling.
• He divided the rotation into three components to understand the
different patterns of mandibular rotation.
• These are differently composed and show a changing
inter‐relationship in each individual throughout the entire growth
period.

I. Total rotation -
- Total rotation is the rotation of the
mandibular corpus and is measured as
change in inclination of a reference or
an implant line, in the corpus relative
to the anterior cranial base.
• The three components of mandibular rotation are :

- In the mandibular tracing, the total
forward rotation is indicated by the
converging nasion‐sella line and a
reference line in the corpus.
- When the implant line rotated forward
(i.e., counterclockwise with the subject
facing to the right), it was designated as
negative and referred to as anterior or
forward rotation.
- In contrast, clockwise rotation was
designated as positive and referred to as
posterior or backward rotation.

II. Matrix rotation -
- Matrix rotation expresses rotation of
the soft tissue matrix of the mandible
relative to the anterior cranial base.
- In other words, matrix rotation
quantified the change of the mandibular
plane angle.
- On profile radiographs, the soft tissue
matrix is defined by the tangential
mandibular line ML.

- The matrix rotation is recorded as negative when the
tangential mandibular line rotates forward relative to the
nasion‐sella line.
- The matrix sometimes rotates
forwards and sometimes
backwards in the same subject
during the growth period, with the
condyles as the centre of rotation,
and can be described as a
pendulum movement.

III. Intramatrix Rotation -
- The intramatrix rotation is an
expression of the remodelling at the
lower border of the mandible.
- Defined by the change in inclination of
an implant or reference line in the
mandibular corpus relative to the
tangential mandibular line ML.
- In other words, it is the difference
between the total rotation and the matrix
rotation.

- The intramatrix rotation represents a rotation of the mandibular
corpus inside its matrix with the centre somewhere in the corpus
and not at the condyles.
-The location of the centre of rotation depends not only on the
rotation of the corpus of the mandible but also on the growth
rotation of the maxilla and the occlusion of the teeth.
- Forward rotation of the corpus relative to the tangential line is
recorded as negative.

- The posterior part of the corpus is simultaneously pressed down into
the matrix, resulting in resorption at the lower border in the region of
the angle of the mandible.
- The opposite happens for backward intramatrix rotation.
-When the direction of total rotation is
more forward than the matrix rotation,
remodelling takes place at the lower
border of the mandible.
- Forward intramatrix rotation lifts up the
anterior part of the corpus from the soft
tissue matrix and the stretching leads to
apposition below the symphysis and
anteriorly at the lower margin.

2. DR. ARNE BJÖRK (1969) :
• There are two main directions of rotation i.e. Forward or Backward.
• In forward rotating cases, the total rotation is characterized by the
fact that the intramatrix rotation is usually the dominant component.
• In backward rotating cases, two types of rotation can be
distinguished, one in which backward matrix rotation is the dominant
component and in the other, backward intramatrix rotation dominates.
• Within both patterns, different types can be distinguished depending
on where the centre of rotation lies.

I. Forward Rotation Types –
1) Type I:
-Rotation about centres in the joints
which gives rise to a deep‐bite, in which
the lower dental arch is pressed into the
upper, resulting in underdevelopment of
the anterior face height.
-Features →
a) Centre of rotation – in joint
b) Deep bite
c) Decreased lower anterior facial height
d) Usually associated with powerful musculature
e) May lead to occlusal imbalance and loss of teeth

2) Type II:
- Rotation is about a centre located at the incisal edges of the lower
anterior teeth, due to the 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.
- The increase in the posterior face height has two components-
a. The lowering of the middle cranial fossae i.r.t. the anterior
one as the cranial base bends causes the condylar fossae to be
lowered.
b. The increase in the height of the ramus, pronounced in the
case of vertical growth at the mandibular condyles.

- Because of the vertical direction of
condylar growth, the mandible is
lowered more than it is carried forward
which takes place as a forward rotation
in relation to the maxilla.
- The anterior facial height in this region
may not increase due to
a. simultaneous marked resorption
below the gonial angle,
b. the lower border undergoing
remodelling and
c. eruption of molars keeping pace
with increase in ramal height.

- Features →
a) Centre of rotation – at incisal edges of lower incisors
b) Increased posterior facial height
c) Normal lower anterior facial height
d) Mandibular symphysis swings forward
e) No increase in overbite
f) Compensatory forward shift of the entire arch with
forward tipping of incisors and molars.
g) May show crowding in lower anterior segment.

3) Type III:
- In the case of large maxillary or
mandibular overjet, the centre of
rotation is displaced backward to the
level of the premolars.
- In this type of rotation, the anterior
facial height becomes underdeveloped
when the posterior face height
increases.
- The dental arches are pressed into each other and basal
deep‐bite develops.

II. Backward rotation types –
1) Type I:
- The centre of the backward rotation lies
in the TMJ when the 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, so mandible is
also raised.
- This underdevelopment of the posterior face height leads to a
backward rotation of the mandible, with increase in anterior face
height and possibly open‐bite.

2) Type II:
- The rotation centre is situated at the
most distal occluding molars.
- As the mandible grows in the
direction of its length, it is carried
forward more than it is lowered in the
face and rotated backward.
- The symphysis is swung backwards
which the soft tissues of the chin may
not follow and a characteristic double
chin can form.
- Increase in anterior facial height, basal open‐bite, incompetent lips,
retroclination of lower incisors and proclination of molars and premolars.

3. Dr. William Proffit:
• The rotation that occurs in the core of each
jaw is called the internal rotation and is
visualised by the implant line (total rotation
according to Bjork).
• Rotations caused by surface changes and
alteration in the rate of tooth eruption is called
external rotation (intramatrix rotation
according to Bjork).
• Rotation occurring due to the rotation around
the condyle is called total rotation(matrix
rotation according to Bjork).

4. Dr. F. F. Schudy (1965):
• Wanted to correlate differences in horizontal and vertical growth
of the mandible with mandibular rotations.
• Based his findings on the inclination of the mandibular plane and
occlusal plane compared to the SN plane at different ages.
• As the mandibular plane is affected by remodelling, it becomes
quite difficult to compare his findings with true mandibular
rotation.

• Schudy described rotation as -
I. Clockwise Rotation:
(from the patients right side)
- Result of excessive vertical over
horizontal (condylar) growth
- Pogonion cannot keep pace with
the forward growth of the upper
face and the mandibular plane
becomes steeper
- Causes a reduction in the vertical
overbite
- The point of rotation is at the
condyle

II. Counter-clockwise Rotation:
- Result of a deficiency in vertical
growth as related to horizontal
growth.
- Accompanied by a forward
movement of pogonion and
increase in the facial angle.
- The point of rotation is the most
distal mandibular molar in occlusal
contact.
- Flattening of the mandibular plane
tends to increase the vertical
overbite and renders vertical
overbite correction and retention
more difficult.

5. Dr. Lavergne and Gasson (1976) :
• They found a strong relationship between the degree of rotation
and the difference in the rate of growth between the jaws.
Maxilla grows
more than
mandible
Posterior
mandibular
rotation
Minor
opening of
gonial angle
Maximum
increase in
mandibular length
Rotation controls
the excess of
maxillary growth
Mandible grows
more than maxilla
Anterior
mandibular
rotation
Closure of gonial
angle
Control the excess of
mandibular growth

• They constructed a diagram of rotation, divided in two parts:
1. The first period – instability in direction of rotation related
with changing relationships between the rates of growth in
both jaws
2. The second period - a constant direction of rotation
connected with a time in which one of the jaws continuously
exhibits greater growth than the other

1. Morphogenetic rotation of the mandible
concerns the shape of the mandible itself.
- When two cephalograms are superimposed on
the line through condylion and pogonion, the angle
between the two implants lines corresponds to the
degree of morphogenetic rotation.
2. Positional rotation deals with position of the
mandible.
- When two successive cephalograms are
superimposed on SN line, the angle between the
two implant lines corresponds to the degree of
positional rotation of the mandible.
• They introduced the terms morphogenetic and positional rotations.

1. Convergent rotation of the jaw bases:
- Both maxilla and mandible converge towards
each other
- Closing of the maxillo‐mandibular plane angle
- Severe true deep bite, difficult to manage
2. Divergent rotation of the jaw bases:
- Maxilla and mandible move away, or diverge
- Opening of the basal angle
- Open bite problems
- Extreme cases require surgical correction.
• Lavergne and Gasson in 1982 proposed four major types of mutual
jaw rotations:

3. Cranial rotation of both jaws:
- Both jaws rotate upward and forward
- Horizontal growth pattern compensates for
cranial rotation of the mandible, offsetting a
deep bite
- Results in a normal overbite relationship.
4. Caudal rotation of both jaws:
- Both the maxilla and mandible rotate
downward and backward.
- Offsets an open bite created by downward and
backward mandibular rotation.

6. Dr. J.M.H. Dibbets (1985) :
• Dibbets presented an alternative interpretation of mandibular rotation,
called counterbalancing rotation which pertains to circular condylar
growth, accompanied by selective coordinated remodelling, which does
not contribute to the incremental growth of the mandible.
• Based upon two divergent hypothetical patterns of growth:
(1) a circular growth direction with a centre on the chin and no
enlargement of the mandible but maximal
rotation, versus
(2) a linear growth direction with maximal enlargement of the
mandible but minimal rotation.

• The external configuration of the mandible need not change its form
or its position within the head in order to allow ''intramatrix rotation''
of the bony element to occur.
• Any depositional or resorptive activity at the periosteum will serve
to preserve or to maintain the original contours.

• In this context, the bony periosteal contours, perceived two
dimensionally, may be likened to a frame bordering a painting.
• Applying the foregoing analogy to the mandible, it means that a bony
element can rotate within its external periosteal frame, which is by
definition, "intramatrix rotation."

• The condyle grows on a circular arc (C-C’) with a radius of fixed
length, running from the center at the chin to the condyle without
change in form of the mandible.
• Growth of the condyle has at least two effects:
1. Intramatrix rotation
2. Enlargement - every millimetre of condylar growth along the
pogonion‐condylion diagonal enlarges the mandible along that
diagonal by 1 mm.

• In case there is more enlargement of the condyle, hardly any
"intramatrix rotation" will occur. All growth increments will be
expressed in dimensional gain.
• Deflection of the condylar growth direction from that pattern
causes compensatory remodelling resulting in "intramatrix
rotation.“
• The actual effect of growth of the condylar cartilage is
neutralized to a given extent which is the basis for Dibbets’
Counterbalance Rotation.
• Counterbalancing rotation is a mechanism that
(1) neutralizes growth
(2) results in selective enlargement of the mandible.

7. Dr Robert Isaacson and co‐workers (1977) :
• According to Isaacson, mandibular rotations result from dissimilar
increments of vertical growth between the mandibular condyle and fossa
and the maxillary sutures‐alveolar processes.
• The centre of rotation is located anteroposteriorly based on the degree of
disproportionality in vertical growth occurring between these two areas.
• The more alike the increments of growth are
between the two, the more centre of rotation
approaches infinity. In case of exactly equal
increments of vertical growth, translation occurs,
and the centre of rotation is at infinity.

• Forward mandibular rotations - When vertical increments of
condylar growth are greater than the vertical increments of alveolar
growth. The centre of rotation in this instance is always located
anterior to the most posterior dental contact.
• Backward mandibular rotation - When the vertical growth of
the alveolar area is greater than the condylar area. The centre of
rotation in this instance is always located at or posterior to the
condyle.
• The vector of condylar growth determines the vertical location of
the centre of rotation. The centre of rotation is always located on an
axis formed by the perpendicular bisector of the vector of condylar
growth.

• Rotation of the mandibular implant or stable
structure relative to the anterior cranial base.
True Rotation
• Angular changes of the mandibular plane angle
relative to the anterior cranial base
Apparent Rotation
• Changes of the mandibular plane relative to the
stable structure of the implant line of mandible.
Angular Remodelling
7. Dr. Solow and Houston (1988):

• According to Enlow, two distinct mandibular skeletal rotations exist.
7. Dr. Enlow & Hans (1996):
1. Displacement rotation:
- The whole mandible can move up or down with a
pivot at the condyle.
- Caused by changes in the placement of junctional
contacts with cranial floor and the maxilla
- If the cranial base angle is open then downward and
backward rotation (dolichofacial) is seen.
- If the angle is closed, mandible would rotate upward
to accommodate a closed basicranial flexuresuperior
nasomaxillary position (brachyfacial)

2. Remodelling rotation:
- The alignment between the ramus and the corpus
can change.
- This utilizes depository and resorptive growth
processes and produces angular and dimensional
changes in the ramus and corpus of an individual
mandible i.e., rotations in these parts occur in
relation to one another.
- This is not merely the change gonial angle but
rather change in the alignment between the whole
corpus and ramus.
- The result is a relative upward or downward
displacement of the corpus relative to the ramus.

Clinical significance of Rotation :
• In general, the more extreme the rotation of the mandible during
growth, the greater the clinical problems that it presents.
• Extreme rotation, whether forward or backward, greatly influences
the paths of eruption of the teeth and there is a risk of extreme
migration after extractions, thereby secure anchorage is called for.
• Crowding in the mandible results from both directions of growth
rotation. In the case of forward rotation, there is a major risk of
deep‐bite developing which can be prevented by means of a
stabilizing appliance, such as a bite plane, introduced before puberty.

1. Relationship between Condylar growth and Rotations :
• When vertical increments of condylar growth are greater than the
vertical increments of sutural and alveolar growth, forward
mandibular rotations occur, whereas when the vertical growth of the
sutural-alveolar area is greater than the condylar area, backward
mandibular rotation occurs.
• The vector of condylar growth determines the vertical location of
the centre of rotation. The centre of rotation is always located on an
axis formed by the perpendicular bisector of the vector of condylar
growth.

• If the vector of condylar growth has a posterior component
relative to the occlusal plane, the centre of rotation will be
located in front and above or behind and below the condylar
growth vector.
• When the vector of condylar growth has an anterior
component relative to the occlusal plane, the centre of rotation
be located in front and below or behind and above the condylar
growth vector.
• If the vertical growth of the condylar area exceeds the
sutural‐alveolar areas, forward rotation will occur. If vertical
growth of the sutural‐alveolar area exceeds the condylar area,
backward rotation will occur.

• In cases with a vertical direction of condylar growth, a
considerable increase in the curvature of the mandibular
base is seen, whereas in cases where growth was directed
sagittally, the mandibular base was flattened.
• The gonial angle decreases with the vertical condylar
growth and increases with the sagittal direction of growth.
• The compensatory resorption beneath the angulus region
is greater in the case of vertical condylar growth, whereas in
the case of sagittal growth it is moderate, or apposition could
occur.

• Change in the inclination of the upper and lower incisors to the
nasion‐sella line was not correlated significantly with the rotation of
either of the jaws.
• The change in the inclination of the lower molars in the face was
moderately correlated with the rotation of the mandible and thus
followed, on an average, the rotation of this jaw.
• The change in the inclination of the upper molars in the face was
correlated with the rotation of both jaws, more with that of the
mandible.
2. Relationship between Dentition and Rotations :

• With forward true rotation, the lower incisors are moved
away from the lower lip and toward the tongue. This disrupts
their equilibrium, and they compensate by proclining as they
erupt.
• For every degree of forward true rotation, the incisors will
procline approximately 0.71 degrees.
• The incisors retrocline when the mandible rotates posteriorly
due probably to relatively greater lip than tongue pressure.
Clinically, this results in a loss of arch perimeter and often
increases the risk of crowding.

3. Relationship between Chin position and Rotations :
• There are only three other possibilities for AP chin changes:
(1)Condylar growth - posterior condylar growth repositions the chin
forwards, while anterior condylar growth repositions the chin
backwards
(2) Changes in glenoid fossa position ‐ Anterior or posterior
changes in fossa position relocates the chin forward and backward,
respectively
(3) True mandibular rotation - the most important factor in AP chin
position change

• Clinical consequence –
1)In hyperdivergent Class II patients, notwithstanding the type of
treatment, some patients’ chins were displaced anteriorly, while
others were displaced posteriorly due primarily to each individual’s
true rotational patterns.
2)True rotation explains why Class II patients treated with functional
appliances often do not improve their chin projection, even with
posterior redirection of condylar growth. Functional appliances
displace the mandible forward and downward by either rotating the
mandible downward or limiting its true forward rotation. Both of
these alternatives are detrimental to AP chin position.

Prediction of Rotation :
LONGITUDINAL METHOD:
• Following the course of development in annual cephalometric
films
METRIC METHOD:
• Prediction of facial development on basis of facial
morphology, determined metrically from a single x‐ray film
STRUCTURAL METHOD:
• Based on information concerning the remodeling process of
mandible during growth from implant studies

Prediction by the structural method :
1. According to Bjork, structural signs that can be used :
a) Inclination of the condylar head ‐ Forward or
backward inclination of the condylar head correlates
with a similar growth rotation.

b) Curvature of the mandibular canal ‐ In the vertical
type of condylar growth, the curvature of the canal is
greater than that of the mandibular contour and opposite
in the sagittal type. The canal may then be straight, or it
may even curve in the opposite direction.

c) Shape of the lower border of the mandible ‐ 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. In sagittal
growth, the anterior rounding is absent, and the cortical layer
is thin, while the lower contour at the jaw angle is convex.

d) Inclination of the symphysis ‐ It is measured as the angle
between the tangent to the anterior surface of the mandible and
the anterior cranial base. 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.

e) Interincisal angle ‐ In forward rotators, there is a more
obtuse interincisal angle than in backward rotators.

f) Interpremolar or intermolar angles ‐ In forward rotators
the intermolar and inter‐premolar angles will be more
obtuse than backward rotators.

g) 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.

2. Prediction methods of Skieller included four variables which,
in combination, gave the best prognostic estimate (86%) of
mandibular growth rotation :
a) Mandibular inclination - represented by three alternatives,
i. Index I (proportion between posterior and anterior facial height)
ii. Lower gonial angle (GOL)
iii. Inclination of lower border (SN‐ML)
The mandibular inclination had a 60% predictive value of the
direction of rotation.
b) Intermolar angle ‐ increase in forward rotation of the mandible
and decrease in backward rotation. The change in the intermolar
angle during growth is even more distinct in backward‐rotating
cases where eruption of the molars often is impeded.

c) Shape of lower border - In forward rotation, apposition
below the anterior part of the mandible is greater, giving
rise to a convex shape of the lower anterior border. In
backward rotation of the mandible, an almost linear shape
of the anterior lower border seen. In backward rotating
cases the shape of the lower border is characterized by
apposition below the angular part, resulting in a convex
shape.
d) Inclination of symphysis - Measured as the angle between
the tangent to the anterior surface of the mandible and the
anterior cranial base. This surface is normally free from
remodelling.

3. According to a study by Aki et al. the size and shape of the
mandibular symphysis is an important consideration in
orthodontic treatment.
- In the case of a larger symphysis, more
incisor protrusion will be acceptable and
more likelihood of success with
non‐extraction treatment.
- Anterior growth rotation - small height
and large angle of the symphysis.
- Posterior growth rotation - large height
and small angle of the symphysis.

• Baumrind (1984) - unlikely that such predictions play any consequential
operational role in the planning of successful orthodontic therapy at the present.
• Von Bremen (2005) - Bjork’s structural signs - difficult to categorize hyper‐ or
hypodivergent skeletofacial morphology. However, hypodivergency was
recognized more easily than hyperdivergency.
• Aki et al (1994) the symphysis - reliable growth indicator, predicts the direction
of mandibular growth.
• Halazonetis (1991) - shape of the mandibular lower border - unreliable.
• Mair and Hunder (1992) - inclination of the mandibular ramus and the gonial
angle - a weak correlation to the mandibular growth direction.
• Kolodzielj et al (2002) - depth of the antigonial notch - no association between
this structural sign and the direction of future mandibular growth rotation.
Reliability of prediction :

Maxillary Rotation :
• Due to varying growth activity of the middle cranial fossa, sutural
growth activity and surface remodelling, the maxilla is rotated during
development.
• The growth changes which take place in the maxilla are -
1) Marked resorption in length in the anterior nasal spine region
2) Lowering of the nasal floor by resorption
3) Lowering of the maxilla affected mainly by sutural growth and/or
by periosteal growth increments in height of the alveolar arch.
4) Increase in height of the nasal cavity due to the sutural lowering
of the maxilla and/or the lowering of the nasal floor.

• Depending on the specific degrees and combination of internal and
external rotation the following patterns were identified by Bjork :
1. Forward Rotation: due to excessive internal rotation or lack of
compensatory external rotation, or both.
-The maxilla is inclined upward and forward.
-Increases the prominence of the maxillary incisors and aggravates
maxillary protrusion.
2. Backward Rotation: the maxilla rotates clockwise.
- Retroclination of the incisors.
- Forward shift of the entire dental arch on the maxillary corpus, the
space for the incisors decreases, results in late secondary crowding.
Maxillary Rotational Patterns:

3. Transverse mutual rotation of the two maxillae:
-Bjork in his experiment placed an anterior & lateral implant in each
maxilla.
- From the age of 10-11 years, the increase in width between the lateral
implants was 3.5 times more than between the anterior implants
indicating that the two maxillae rotates in relation to each other in the
transverse plane.
-As a result,
1) Lateral segments separates more posteriorly.
2) Distance between molars increases more than the distance between
canines

Cranial Base Rotation :
• The cranial base exerts a greater influence on the face than vice versa.
• Changes in cranial base orientation includes -
- The human cranial base flexes postnatally.
- It shortens and widens, the vault increases in height, and the sphenoidal
angle closes.
- Basion moves closer to the pterygoid plates
due to remodelling causing a clockwise
rotation of the occipital and an anticlockwise
rotation of the sphenoid bone.
- Remodelling of the bilateral temporal bones,
resulting in a widening of the cranial base.

• A narrow cranial base (dolichocephalic) tends to have greater
clockwise rotation of occipital bones that tends to keep the cranial
base narrow. In addition, if there is an anticlockwise rotation of the
sphenoid bones, results in narrower faces with an increase in depth
of their maxillary arches.
• A combination of a clockwise occipital and an anticlockwise
sphenoidal rotation leads to a tendency to develop a relative
maxillary protrusion (Class II).
• A wider cranial base tends to display an increase in the
anticlockwise rotation of their occipital bones in combination with a
greater degree of clockwise rotation of their sphenoid bones,
displaying a relative widening and shortening of their maxillary
arches (Class III).

Interrelationship between rotation of skeletal components :
• When trying to decipher the anatomic and developmental relationships
predisposing to malocclusions, the developmental variables that should be
analysed are:
1. The rotational position of the middle cranial fossa.
2. The resultant displacement of the anterior cranial fossa
and the nasomaxillary complex.
3. The resultant displacement of the whole mandible by
the nasomaxillary complex and the cranial base.
4. The resultant opening or closing of the gonial angle.
5. The displacement effects on the mandible by a
vertically short or long nasomaxillary complex.

1. Dolichofacial form:
- Mandibular retrusive/maxillary protrusive effects (+) are seen when -
a) Anterior inclination to the middle cranial fossa.
b) Anterior and inferior position of the maxillary complex due above.
c) Downward and backward alignment of ramus.
d) Posterior and inferior position of point B due to above.
e) A long nasomaxillary complex.
f) An increased span of the middle cranial fossa due to the anterior rotation of
the fossa.
g) Closure of the gonial angle adds to the mandibular retrusive effect.

- Effects seen are –
a) The brain is in general long and narrow and
the basicranial flexure is more flat.
b) Nasomaxillary complex placed in a more
protrusive position and is lowered relative
to the mandibular condyle.
c) Results in a downward and backward rotation of the whole mandible.
d) The occlusal plane is rotated downward causing a retrusive mandible,
placement of the molars in a Class II position with a convex profile.
e) Longer and narrower anterior cranial fossa results in a narrower
palate that has a high vault.
f) Subsequently the dental arch would be narrow and long

2. Brachyfacial form:
- Mandibular protrusive/Maxillary retrusive effects are seen when:
a)A posteriorly inclined middle cranial fossa.
b)A posterior and superior positioned nasomaxillary complex due to the
posterior inclination of the middle cranial base.
c)A forward and upward alignment of the ramus.
d)An anteriorly and superior positioned point B due to the forward
alignment of the ramus.
e)A short nasomaxillary complex.
f)Opening of the Gonial angle increasing the mandibular protrusive effect.

-Effects seen are –
a) The brain is wider and shorter anteroposteriorly
with an increase in the cranial base flexure.
b) Shortening of the anterior cranial base positions
the nasomaxillary complex more posteriorly and
superiorly, with a shorter length.
c) A forward rotation of the mandible into a more
prognathic position, placement of the molar in a
Class III position
d) A straight to concave profile
e) Anterior cranial fossa has a shorter but wider shape reflected
in a shorter, wider dental arch with a shallower vault.

Orthodontics and Rotation :
• Clockwise rotation:
- During the growth phase, this would work against
attempts to correct the ANB angle and Class II
molar relationships in patients.
- Can help to reduce a deep vertical overbite
- A vertical growth predisposition would lend itself
to overbite correction and retention in treatment.
• When evaluating a patient to be treated, determination of the growth rotation is
of importance to get an idea of how rotation would affect treatment and
treatment might affect growth rotation.

• Counter clockwise Rotation:
- The mandibular plane is flattened combined with an
increase in the overbite.
- Problems during treatment would include the reduction of
a deep overbite and retention of overbite reduction.
• When treating Class II cases with the use of inter‐arch
elastics, the extent to which orthodontic forces may affect
the rotation, may be determined by analysis of the effect of
bite raising.
- Analysis shows that bite raising affects the remodelling of
the mandible, similar to the effect of occipital pull headgear
inducing rotation of the maxillary corpus inside its matrix.

• Posterior rotations are induced by orthodontic treatment,
particularly associated with the use of Class II elastics,
anchorage bends and anterior bite planes but are often transient.
• High‐angled and low‐angled facial patterns at time of
appliance removal are not associated with increased risk of
post‐retention relapse of mandibular incisor malalignment,
and in adolescent orthodontic patients are poor predictors of
type of posttreatment growth.
• The degree of rotation, when measured to
the SN line, was influenced by treatment.
An increase in treatment led to a reduction
in the amount of anterior rotation,
especially if cervical pull headgear were
used.

TREATMENT PROTOCOL :
• Various combinations of rotation can cause malocclusion –
1. Mandibular Deficiency
a) Functional appliances - Activator, Bionator, Frankel
1 & 2, Twin Block
a) Fixed appliances - Herbst, Jasper Jumper
2. Mandibular excess
a) Functional appliances -Frankel 3, Reverse Activator
b) Extra oral forces: orthopedic chin cup, occipital/ vertical
pull chin cup
c) Adults: Bilateral Sagittal Split Osteotomy

3. Maxillary deficiency: face mask and reverse functional
appliances.
4. Maxillary Excess: Cervical Head gear, in horizontal
growers and vertical head gear in long face individuals or
vertical growers

CONCLUSION :
• Using the available knowledge on growth rotations and how it
influences the adaptation of the components of the craniofacial
complex in an effort to create a stable occlusion, we as clinicians can
enhance our understanding of the underlying problem seen in a patient
with a malocclusion.
• With understanding of the underlying problem, we can tailor the
treatment to be more effective and minimize the risk of in‐treatment as
well as post‐treatment complications.

REFERENCES :
• Erick du Raan, Craniofacial Growth Rotations. ResearchGate.
DOI:10.13140/RG.2.2.31173.55524
• Peter H. Buschang, Helder B. Jacob, Mandibular rotation revisited:
What makes it so important?, Seminars in Orthodontics, Volume 20, Issue
4, 2014, Pages 299-315,
• Dibbets, J.M.H., 1985. The puzzle of growth rotation. American Journal
of Orthodontics, 87(6), pp.473–480.
• F.F. Schudy: The rotation of the mandible resulting from growth: its
implications in orthodontic treatment. Angle orthodontics,1965- vol.35,
No.1, 36-50.
• Beni Solow & william j. Houston :Mandibular rotations: concept and
terminology- EJO-1988 (10) 177-179.

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