The document discusses various concepts related to mandibular growth rotations proposed by different orthodontic researchers over time. It begins by introducing Arne Bjork who first described growth rotations in 1955. It then covers Enlow's concept of remodeling and displacement rotations. Bjork's 1969 classification of forward and backward mandibular rotations is described, including his identification of three types of forward and two types of backward rotations based on their center of rotation. The document also discusses concepts by Bjork and Skieller on total, matrix, and intramatrix rotations. Fred Schudy's concept relating rotation to the disharmony between vertical, anteroposterior and horizontal growth is summarized. Finally, Dibbets' re

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GROWTH
ROTATIONS
Dr MOHAMMED BASHEER

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Introduction
The phrase growth rotation was introduced in 1955 by Dr ARNE BJORK
He described it a particular phenomenon occurring during the growth of the
head

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Of all the patterns of growth , growth rotations assume an important role in
orthodontics because of its major impact on treatment strategies.
It is a major factor in etiological assessment , determining the nature of
anomaly , the prognostic evaluation , determining the possible forms of
treatment and also in assessing the stability of treatment results .

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ENLOWS CONCEPT
basic categories of rotations:
remodelling rotations displacement rotations
FUNDAMENTAL PRINCIPLE OF GROWTH

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remodelling rotations
• Surface towards the directions
is depository +
• Surface away from the growth
direction is resorptive (-)
• If deposition > resoprtion then
cortical thickness increases
• This pattern causes a rotation

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Schema of “skeletal units” of the mandible.

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Schematic representation of mandibular growth, showing
the fetal mandible superimposed
upon the adult mandible.

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Displacement rotations
The whole bone is carried by mechanical force as it simultaneously enlarges .

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2 types of displacements
Primary displacement
Takes place with a bones own enlargement
The whole bone displaced in anterior and
inferior directions
The amount of primary displacement produces
space within the bone continues to enlarge

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Secondary displacement
• The movement of a bone is not related
to its own enlargement
• the anterior direction of growth by the
middle cranial fossae and the temporal
lobes of the cerebrum secondarily
displaces the entire nasomaxillary
complex anteriorly and inferiorly

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A Bjork Started his study in 1951
Had a sample size of 100 children between the age group of 4 – 24 yrs.
Used metal implants to find the sites of growth and resorption in individual jaws.
Also examined individual variation in direction and intensity.
Analyzed mechanics of changes in intermaxillary relations during growth.
Implant radiography

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Mandibular growth rotations assume an important role because they are
common than maxillary rotations.
Mandibular inclinations drastically affects facial morphology , and treatment
planning , treatment outcome
Implants were placed in the anterior aspect of symphysis
2 pins on the right side of the mandibular body
One pin on the external surface of the ramus

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BJORKS CLASSIFICATION OF MANDIBULAR ROTATIONS
(1969)
Arne Bjork (1911–1996) was a Swedish
dentist
Dr. Bjork was born in Darlane, Sweden. He
served as chairman of orthodontics in Malmo,
Sweden from 1940-1950.
Professor of Orthodontics in Royal Dental
College, Denmark. Eventually he became the
head of Department of Orthodontics and head
of Craniofacial Growth Center at the Royal
Dental College for 30 years.
He was nominated as member of World
Federations of Orthodontists in 1995.

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AJO JUNE 1969 , VOL 55 , ISSUE 6 , P 585-599

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Rotations of mandible
forward rotations backward rotation
-Type 1 -Type 1
-Type 2 -Type 2
-Type 3
AJO JUNE 1969 , VOL 55 , ISSUE 6 , P 585-599

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Type 1 forward rotations
Center- TMJ
Lower dental arch
compressed in to the
upper arch
Deep bite ↓ Ant facial height
Cause-occlusal
imbalance due to
loss of teeth/powerful
musculature
AJO JUNE 1969 , VOL 55 , ISSUE 6 , P 585-599

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6/26/2016

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Type II
Center- incisal edges
of lower ant teeth
It is due to Marked
development of post
facial height & normal ↑
ant facial height
Lowering of the
mandible occurs which
happens as forward
rotation
Muscular & ligamentus
attachments Carries
the lowered mandible
forward
• Lowering of middle cranial fossae
• increase in height of ramus in case of
vertical growth
Post facial height:::2
components

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6/26/2016

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Type III
Center of rotation -
premolars
The dental arches
compressed in to
each other , & basal
deep bite develops
in case of large
overjets the COR
shifts to the LEVEL
of premolars
The AFH when
the PFH
Cause –
unbalanced
occlusions

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• Chin becomes prominent
• Mandibular symphysis
swings forward

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Backward Rotation Type I
Center – TMJ
Bite raised by
orthodontic means 
AFH increases
Causes- the middle
Cranial fossae is
raised
Incomplete
development in height
of middle cranial
fossae 
underveloped of PFH
underdevelopment of
post facial height
leads to Backward
Rotation

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6/26/2016

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Type II
Center – Most distal occluding molars
Cause - Sagittal growth direction of condyle , as
mandible grows in direction of length because it is
attached to ligament , it is rotated backwards
The symphysis is swung backwards & chin drawn back
Double chin
Basal open bite develops
Lower ant teeth retroclined & alveolar prognathism is
reduced
This type of rotation is characteristic in condylar
hypoplasia & In condylar aplasia
AJO JUNE 1969 , VOL 55 , ISSUE 6 , P 585-599

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Finally he also concluded that
Mandibular growth Rotation is closely associated with both the direction & the
amount of growth at the condyles

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Structural Signs given by DR A . Bjork
Condylar inclination.
Mandibular canal inclination.
Lower border of mandible (Antigonial notch).
Symphysis inclination.
Interincisal inclination.
Intermolar angle.
Lower face height.
Bjork gave seven structural signs to find the direction of
mandibular growth.
These signs are not clearly developed before puberty.

28. Page  28 GROWTH ROTATIONS
28
Condylar inclination

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Mandibular canal inclination.

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GROWTH ROTATIONS
30
Lower border of mandible
(Antigonial notch).

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GROWTH ROTATIONS
31
Symphysis inclination.

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Interincisal inclination.
Intermolar angle.

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33
LOWER ANTERIOR FACIAL HEIGHT

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He concluded on the structural signs
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 .

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Clinical implications !!
Both forward & Backward rotation greatly influences paths of eruption
Serious risk of extreme migration after extractions
Extractions should be avoided until the beginning of pubertal growth spurt

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BJORK AND SKIELLER

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After conducted the implant study they concluded that
Divided the
mandibular rotations
into three
components
• Total rotation
• Matrix rotation
• Intramatrix rotation

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Total rotation
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,‘-’

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MATRIX ROTATION
Rotation of the soft tissue
matrix of the mandible
relative to the Anterior
cranial base
The soft tissue matrix is
defined by the Tangential
mandibular line(ML1)
The matrix rotates forwards &
backwards in same individual
during the growth period –
PENDULUM MOVEMENT
Center of Rotation – Condyles

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Defined as the change in inclination
of an implant line in the mandibular
corpus relative to the tangential
mandibular line
Intramatrix Rotation is an expression
of remodeling at the lower border of
the mandible
Is the difference between total
rotation and the matrix rotation.
Centre of rotation is
somewhere in corpus
and depends on
rotation of corpus,
growth rotation of the
maxilla and occlusion
of the teeth.

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The diff b/n Total Rotation & Matrix Rotation is
intramatrix Rotation

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Fred F SCHUDY
• Fred was born on a small farm in south Missouri
• he entered Washington University Dental School in St Lou-
is,
• Fred was a member of the AAO, the American Dental
Association, The Edward H. Angle Society, and the Charles
Tweed Foundation.

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SCHUDYS CONCEPT
Angle orthod 1965 ; 1; 36-50

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According to F F SCHUDY
Rotation of the mandible is a result of disharmony between vertical growth, antero-posterior
growth and horizontal growth.
Clockwise
rotation
Counter-
clockwise
rotation

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Basic idea ???
IF horizontal growth >> vertical growth == counter clock wise rotation
in the molar area
If vertical growth >> horizontal growth == clockwise movement rotation
To those increments which move the chin vertically = we apply vertical growth
The condyles which causes the chin to move forward we apply the term
horizontal growth

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Clock wise rotation
As a result of more vertical growth in the molar region than at
the condyles
Point of rotation == condyles
Results in ++ AFH , this can cause open bites
Growth at condyle == forward component  chin
When the vertical aspects are applied through occlusal contact
== downward +backward direction chin === clockwise rotation

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There are four vertical
growth elements which
increase the facial height,
these are:-
• Anterior growth of nasion.
• Corpus of maxilla getting
palatal plane down.
• Eruption of maxillary
molars.
• Eruption of mandibular
molars.

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Counter clock wise rotation
It due to more condylar growth than vertical growth
Point of rotation being == most distal aspect
mandibular molar
Forward movement of the pogonion FACIAL
ANGLE
The flattening of the occlusal plane causes more
vertical bite
The smaller the gonial angle the greater the rotation
is produced for each mm of forward movement

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Clinical implications !!!
If vertical growth is deficient , simulation of
vertical growth can be done , vice versa
The mandible should not be considered as a
single entity ,
He concluded that mandibular growth is the
principal determining factor of facial morphology .

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DIBBETS CONCEPT
AJO 1985 volume 87 issue 6

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He re examined Bjork & Skeiller method
Diagrammatic illustration of the concept of “intramatrix rotation.” The
mandibular periosteal contours may be likened to a frame bordering a
painting. The painting may be rotated within the frame, but the external
outline, configuration, and dimensions do not change.
AJO 1985 volume 87 issue 6

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Bjork and skeiller stated that “ intramatrix rotation “ is an expression of the
remodeling at the lower border of the mandible & rotation occurs at the
corpus of the mandible
A third option was given by dibbets after evaluation of bjorks technique

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An alternative interpretation was given by DIBBETS
He hypothetically
constructed Two
divergent patterns of
mandibular growth
1)Circular growth pattern
of condyle, resulting in
Intramatrix Rotation without
any enlargement of
mandible
2)linear growth pattern
of the condyle,
characterized by the
absence of intramatrix
rotation but evidencing
mandibular enlargement.

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Counterbalancing Rotation
 Defined as the percentage of condylar incremental growth, detected by
implants that has contributed to the enlargement of the condylion- pogonion
dimension
Counterbalancing Rotation pertains to circular condylar growth, accompanied
by selective coordinated remodeling, which does not contribute to the
incremental growth of the mandible.
The actual path of the condyle is accompanied by selective remodeling &
thus neutralizes the growth

56. Page  56 AM J
ORTHOO DENTOFAC ORTHOP 1990;98:29-32.)

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

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• Average counterbalancing proportion for Angle classes
Class III – 85%
Class I – 76%
Class II Div 2 – 59%
Class II Div 1– 65.5%
• proportion ranges from 50% to 97%.
• It is apparent that an incongruity often exists between
the condylar growth direction and the direction
of enlargement of the anatomic mandible.
• Two mandibular tracings of the same individual at age
11 years 7 months and 17 years 7 months,

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PROFFIT S CLASSIFICATION
rotation depending location of growth
Internal external
rotation rotation
Total rotation

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Rotation occurring in the core of the jaw were called as INTERNAL ROTATION
The core is the bone that surrounds the inferior alveolar nerve
 internal rotation of the mandible 10-15 degrees
internal rotation
matrix rotation intramatrix rotation

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Matrix rotation
It occurs around the condyle
Termed as hinge rotation
Rotation of the mandibular plane related to cranial base
Opening and closing of bite will change the inclination of mandibular plane
relative to S-N

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Intra matrix rotation
It is the rotation of bony element within its periosteal matrix which occurs in the
corpus of the core of the mandible .
If there is no hinge movement then the total rotation and intra matrix will be identical
On an average there is about 15 degrees of total for age 4 to adult life

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Rotation caused by the surface changes and the alteration in the rate of tooth eruption
is called as EXTERNAL ROTATION
The external compensation in an average growing adult is 11-12 degrees
The difference between the internal and external rotation accounts for 3-4 degrees
reduction in mandibular plane angle during growth in adolescence.

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Clinical importance
Short face type
 Low mandibular plane angle
 Skeletal anterior deep bite
 Crowding of anterior teeth
 --LAFH
Long face
 Skeletal anterior open bite
 Dental protrusion
 ++LAFH

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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
remodeling of
lower border
External
rotation

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Growth rotation of maxilla
Maxilla undergoes extensive remodeling and displacements when subjected
to various functional demands .
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 .

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Growth of maxilla occurs by two ways
– Passive displacement- in primary dentition
period
– Active growth is by surface remodeling

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Enlow’s
Maxillary Rotations
Displacement Remodeling

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Displacement Rotations
Primary displacement
The whole nasomaxillary
complex is displaced in
conjunction with its own
growth

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Secondary Displacement
- Results from growth of other bones & their soft tissues

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In 1972 Bjork and skeiller studied rotational growth of
maxilla with the help of implants
3 sites of implant placement
were as follows
Inferior to nasal spine
Zygomatic process of
maxilla ( lateral implant)
At the border between the
hard palate and the alveolar
process medial to first molar

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Based on this they gave the various terminologies
Internal rotation
External rotation
Forward growth
rotation
Backward rotation

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Internal rotation
A rotational pattern that
occurs in the core of the
maxilla
Also known as intra matrix
rotation
It is similar to the intra
matrix rotation of mandible
In most individuals the
external and internal
rotations cancel each other.

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External rotation
Simultaneous to the internal rotation of maxilla , various degrees of
resorption of bone occur on the nasal side and deposition of bone
on the palatal side ,
Similarly ,variations in the amount of eruption of incisors and molars .
All these contribute to external rotation

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Combination of IR and ER
•Forward rotation
•Backward rotation
Bjork and
skeiller
observed 2
types of
rotational
growth

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Forward growth rotation
Due to excessive internal
rotation or lack of normal
external rotation or
combination of both
Maxilla inclined upward
and forward
This rotation tips incisors
forward

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Backward rotation
Downward and
backward
tipping of the
anterior end of
the palatal
plane and the
maxillary base
The jaw bases
are translated
posteriorly
,Incisors
appear to tip
lingually

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Clinical importance
An upward and forward tipping of the anterior part of maxilla often
seen in mouth breathers .
Downward and backward tipping of anterior part of maxilla is
observed as a natural compensation in patients with vertically
growing faces
The inclination of maxilla can be influenced by fixed mechancho
therapy and orthopedic treatment .

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MUTUAL REALTIONSHIP OF ROTATING JAW BASES
It was an attempt to clarify weather there was a difference between the morph
ogenic and positional rotations
Morphogenic rotation concerns with the shape
Positional rotation concerns with the position of the mandible
They have a major role in the mutual adjustment of both the jaws .

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 According to Lavergne and Gasson the mutual rotation of the upper
and lower jaw can be of following 4 types
1. Convergent rotation.
 Severe deep bite.
 Difficult to treat with a functional therapy.
2. Divergent jaw bases.
 Severe open bite.
 In severe cases orthognathic surgery is required.

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3. Cranial rotation of both the bases.
 Horizontal growth pattern.
 Maxillary cranial rotation compensates
for the mandibular rotation.
 Normal bite.
 Bot maxilla and mandible rotates
upward and forward
4. Caudal rotation of both bases.
 Vertical growth pattern.
 Maxillary caudal rotation compensates
for the mandibular rotation.
 Normal bite.

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Studies on growth rotation
Various studies have been conducted , notable among them are Bjork ,
skeiller , lavenrgne and gasson , schudy , profit
All these studies have been conducted to predict the mandibular growth

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AJODO 1994 ;106 : 60-9

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Inferences
Mandible with anterior growth rotation was associated with small height ,large
depth ,small ratio and large angle of the symphysis
Men posses a stronger relationship between symphyseal growth and and
direction of mandibular growth
Women also showed the same relationship as men between symphysis height
,depth ,ratio and angle to the direction of growth
The symphyseal depth , height , ratio ,increased while symphyseal angle
decreased with age .

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Mandibular auto rotation after surgery (lefort 1 )

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Conclusion
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.

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References
Contemporary orthodontics- William.R.Proffit 5th and 4th edition
Essentials of of facial growth - Donald.H.Enlow.
CRANIOFACIALDEVELOPMENT- Geoffrey H. Sperber
Text book of craniofacial growth – Sridhar premkumar
Prediction of growth rotation - A.Bjork-AJO-DO-1969,jun 39-53.
Facial development and tooth eruption :an implant study at the age of puberty-
A.Bjork,V.Skieller AJO-DO 1972,62,4;339-383.
The rotation of mandible resulting from growth;Its implications in orthodontic
treament -F.F.Schudy-AO 1965.no.1,36-50.
The puzzle of growth rotation. J.M.H.Dibbets –AJO-DO June 1985 ,87,6;473-
480.
Mandibular rotation and enlargement. J.M.H.Dibbets.AJO-DO July 1990,29-
32.

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Facial Growth in Man, Studied With the Aid of Metallic Implants. By Arne Bjork,
Acta odontol. scandinav 13: 9-34, June, 1955
Prediction of mandibular growth rotation evaluated from a longitudinal implant
sample – Bjork, Skieller and Hansen, AJO, Nov 1984, pg. 359-370.
Assessment of symphysis morphology as a predictor of the direction of
mandibular growth Todd Aki, DDS, MS," Ram S. Nanda, DDS, MS, PhD, b G.
Frans Currier, DDS, MDS, MED, = and Surender K. Nanda, DMD, MS d

90. Page  90
Thank you