Growth rotations /certified fixed orthodontic courses by Indian dental academy

GROWTH ROTATIONS

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INDIAN DENTAL ACADEMY
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Contents
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Introduction
Terminologies
Concepts of Mandibular growth Rotations
Concepts of Maxillary growth Rotations
Prediction of Mand growth Rotation
Interaction b/n jaw Rotation &Tooth
eruption
• Clinical implications
• conclusion

Introduction
Since Cephalometrics introduced in 1930,
originally used to reveal The Anatomy of head

Longitudinal study is possible, soon employed
to test various Concepts of mechanisms of
postnatal growth of head

Introduction
Longitudinal Cephalometrics
analysis of profile
radiographs shows that
facial shape is remarkably
constant during growth


• Until the use of metallic
implants the extent to
which the mand & maxilla
rotate during growth was
not appreciated

• The Rotation tends to be
masked by surface
remodeling


• Lande in 1952 observed that the lower border
of the mand becomes less steeply inclined
• The phrase “GROWTH ROTATION” was
introduced in 1955 by Bjork
• With the use of metallic implants, He could
infer the sites & amt of growth & resorption
• Superimposing 2 consecutive tracings
showed that the older Mand rotated

Forward Rotation (Bjork)
Counterclockwise Rotation (shudy)
Posterior growth is greater than
Anterior

Backward ward Rotation (Bjork)
Clockwise Rotation (shudy)
Anterior growth is greater than posterior


TERMINOLOGIES
• 1965-Schudy introduced clockwise and
counterclockwise rotation.
• 1969-Bjork discussed different directions
of rotation of the mandibular implant line
and the relation of these to mandibular
form.


• 1970-Odegard described rotation as the
change in the orientation that can occur
between implant line and lower border of the
mandible.
• 1977-Lavergne and Gasson described the
terms Positional and Morphogenetic
rotations.
• 1983-Bjork and Skieller gave the termsTotal rotation.
Matrix rotation.
Intramatrix rotation

• 1985-Dibbets introduced the term
Counterbalancing rotation.
• 1988-Solow,Houston
True rotation.
Apparent rotation.
Angular remodeling of the lower border.
• Proffit- used the terms
Internal rotation.
Total rotation .
External rotation.


TOTAL ROTATION / TRUE ROTATION /
INTERNAL ROTATION
• Is the rotation of the mandibular corpus
and is measured as a change in
inclination of the implant line, in the
mandibular corpus relative to the
anterior cranial base.


If the implant line rotates forwards, the total
rotation is designated as Negative
The Total Forward Rotation is indicated by
converging sella – nasion lines


MATRIX ROTATION / APPARENT
ROTATION / TOTAL 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)
• Is designated as Negative,when Tangential
mandibular line rotates forwards

The matrix rotates forwards & backwards in same
individual during the growth period – PENDULUM
MOVEMENT
Center of Rotation – Condyles


INTRAMATRIX ROTATION/
ANGULAR REMODELING/
EXTERNAL ROTATION
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

• Forward Rotation of the corpus relative to the
tangential mand line is recorded as Negative

• Center of rotation is somewhere in the corpus

• Depends on rotation of corpus of mand &
rotation of maxilla & occlusion of teeth


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+
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-


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


• According to Bjork & Skieller’
“Intramatrix” concept
First,the mandible “wiggles” with in the
matrix
Second,this “wiggling” is associated
predominantly with the corpus, but is
caused by the growing condyle
Third, Rotation results from or compensates
for, a genetically determined program

BJORK

SOLOW,
HOUSTON

PROFFIT

Rotation of Mandibular
core relative to cranial
base implants

Total
Rotation

True
Rotation

Internal
Rotation

Rotation of Mandibular
plane relative to cranial
base

Matrix
Rotation

Apparent
Rotation

Total
Rotation

External
Rotation of Mandibular Intramatrix Angular
Remodeling Rotation
plane relative to core of Rotation
of lower
Mandible
border

• The Total Rotation = Matrix Rotation
+
IntraMatrix Rotation


• The center of Total Rotation depends on other
two centers of Rotation
• The pattern of vertical facial development is
strongly related to the Rotation of both the jaws
• For an average individual with normal vertical
facial height
• Total Rotation = – 15
Matrix Rotation = –4
IntraMatrix Rotation = –11

“Positional” & “Morphogenetic”
Rotation
Given by Lavergne & Gasson

Positional Rotation deals with the position of
the mandible with in the head


Morphogenetic Rotation
• concerns the shape of the mandible itself
• super imposing the two tracings on a line through
condylion & pogonion

•The angle b/n two implant lines is determined &
this corresponds to the degree of morphogenetic
Rotation
• similer to Bjork’s Intramatrix Rotation but not
identical

Bjork & Skieller
consider the key factor of Intramatrix rotation to
be found in a rotation of the mandibular corpus
inside its matrix
Lavergne & GassonFound the effective
mechanism in Ramus, its
forward or backward
growth,therby shortening or
elongating the effective
length of the mandible


• Maxillary – Mandibular sagittal discrepancy is
minimized by opening or closing the gonial angle


“It is a compensating mechanism which is
capable of enlarging or reducing
mandibular length as measured along the
condylion-pogonion diagonal”


J.M.H.Dibbets
• Re-examination of the concept of
“Intramatrix Rotation" as defined by Bjork
& Skieller & also explored by Lavergne &
Gasson
• Three diff interpretations of Intramatrix
concept are


• 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


Bjork approach
Superimposing two tracings of the same mandible registered
upon natural reference structures shows Rotation


Divergence of implant lines indicates
Intramatrix rotation

Superimposed on implant markers
Indicates extensive remodeling


• 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 in order to allow ‘Intramatrix rotation’
• Any Depositional or Resorptive activity maintains
original contours

Painting rotated with in frame but external configuration &
dimensions do not change

• The bony element can rotate with in its
periosteal frame
• Every deflection of condylar growth
creates the possibility of compensatory
remodeling, mostly resorption of the lower
border resulting in Intramatrix rotation
• Intramatrix Rotation neutralizes the
condylar growth.

Second option-Hunterian concept
or Morphogenetic rotation
Posterior ramal deposition &
Ant resorption

The direction of condylar growth
follows pattern that enlarges the
Mandible maximally


Third option - Dibbets
• 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.
suggested mechanism

Counterbalancing Rotation

Counterbalancing Rotation
“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 mand condyle is accompanied by selective
remodeling & thus neutralizes the growth
* Results in selective enlargement of the mandible, apart &
distinct from mechanisms that have been described in the
literature

Counterbalancing proportion
Defined as the percentage of condylar
incremental growth, detected by implants that
has contributed to the enlargement of the
condylion- pogonion dimension

• The quantification & comparison of condylar
growth & mandibular enlargement


Mandibular growth =pg-Ar2 –
Pg-Ar1
Condylar growth – Ar1 – Ar2

Growth of articulare to pogonion

Counterbalancing =
Condylar incremental growth
proportion

×100

• According to the concept of congruous mandibular
growth, the proportion expected is 100%.
• But the proportion ranges from 50% to 97%.

• Average counterbalancing proportion for Angle classes
Class III – 85%
Class I – 76%
Class II Div 2 – 59%
Class II Div 1– 65.5%

Effective contribution vary among individuals because of
varying condylar directions & mand remodeling

Concepts of mandibular
Rotations


Enlow’s concept
Two categories of Rotations
- Remodeling Rotations
- Displacement Rotations


Remodeling


Ramus
• Ramus undergoes remodeling to carryout
following functions
• Place the corpus in constant functional
relationship with maxillary arch
• To bridge the pharyngeal compartment
• To accommodate the vertical dimension of
nasomaxillary complex
• Give attachment to the growing masticatory
musculature. www.indiandentalacademy.com

Vertical lengthening ramus continues after horizontal
growth ceases


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


• Vertical growth changes of the mandibular
dento-alveolar arch, the ramus & middle
cranialfossae must match nasomaxillary
growth to achieve facial balance
• Any diff will lead to Displacement mand
Rotations


Displacement rotations
• Changes in the junctional contact with the
cranial floor and maxilla.
• Cranial base angleOpen-downward and backward rotation of
mandible.
Closed-forward rotation.


Closed Angle

Open Angle


Vertically short midface causes forward
rotation & upward inclination of mandible


Long nasomaxillary region causes downward
& backward alignment of mandible


Schudy’s concept
• The Rotation of the mandible resulting from an
inhormony b/n vertical growth & horizontal
growth
• Counter clockwise Rotation deficiency of vertical growth compared to
horizontal growth & tends to cause closed bite
• Clockwise Rotation –
excessive vertical growth compared to horizontal
growth & tends to cause open bite

Vertical elements of growth
• Growth at nasion
• Growth of maxillary corpus
• Growth of max post alveolar processes
• Growth of mand post alveolar processes


Posterior growth analysis
The ratio b/n horizontal growth
& Vertical growth

A= I+ II + III


Bjork concept


Forward Rotation – 3 Types
Type – I
Center- TMJ
Deep bite
↓ Ant facial height

Lower dental arch compressed in to upper
Cause-occlusal imbalance due to loss of teeth/powerful
musculature

• Type II
• Center- incisal edges of lower ant teeth
• Marked development of post facial height &
normal ↑ ant facial height
• ↑ Post facial height
Lowering of middle cranial fossae
increase in height of ramus


Vertical direction of the
condylar growth lowered
the mandible more than it
is carried forward
Muscular & ligamentus
attachments Carries the
lowered mandible forward

Lower border undergoes characteristic remodeling

Type III
Center of rotation - premolars

The dental arches compressed
in to each other & basal deep
bite develops

Cause – Anomalous occlusion of
ant teeth

• The inclination of teeth is greatly
influenced by rotation of jaws

• Displaces the path of eruption of teeth in
mesial direction

• Ant crowding referred as packing

Backward Rotation –two Types
Type I
Center - TMJ
underdevelopment of
post facial height leads
to Backward Rotation
Causes- the middle Cranial
fossae is rised
-Incomplete development in
height of middle cranial
fossae as in oxycephaly

Type II
• Center – Most distal occluding molars
• Cause - Sagittal growth direction of condyle

• The symphysis is swung backwards & chin
drawn back

• Double chin


Basal open bite develops

Lower ant teeth retroclined &
alveolar prognathism is reduced

Rotation did not lie in the
over eruption of lower teeth
This type of rotation is characteristic in condylar hypoplasia &
In condylar aplasia

Mandibular growth
Rotation is closely
associated with both
the direction & the
amount of growth at
the condyles


Maxillary Rotations


Bjork & Skieller
Implant studies of Bjork & Skieller have
shown that, The downward & forward
displacement of maxillae are associated
with varying degrees of vertical Rotation
Internal Rotation produced with in the core
of maxilla tends to be masked by surface
changes & alterations in the rate of teeth
eruption

• The maxilla is less easy to delude in to
core of bone & functional processes

• Alveolar process is functional process but
no areas of muscle attachment


• Lateral implants – 4yrs of age, inserted in the
zygomatic process two on each side, antly on the
lower margin away from the crest

•Indicates increase in width
of median suture at the
level of first molars


• Anterior implants – 10yrs of age, inserted below the
anterior nasal spine on each side of median suture
at the level of apices of central incisors


• Maxillary Rotations studied in 2 planes

Transverse plane
Vertical plane


Transverse / Mutual Rotation of two
Maxillae
Triangle is constructed with the sides of
constant length by joining ant & lateral implants


• Lateral implants separate more than ant
implants
• Two maxillae rotate in relation to each other
in transverse plane
• Length of the maxilla is reduced in mid
sagittal plane
• Length of dental arch becomes reduced

Vertical Rotation
A line from tip of ant implant to
Lateral implant is drawn on
profile radiograph

Tracings shows change in
inclination of implant line to the
SN plane at diff ages

The inclination of nasal floor to ant cranial base is
maintained by differential remodeling
In forward rotation – the
resorption at nasal floor
is greater antly than
postly
Facial growth is
greater postly


In backward Rotation Rotates downwards & backwards

Resorption at nasal floor
is greater postly

Facial growth is greater
antly than postly

Enlow’s
Maxillary Rotations

Displacement

Remodeling


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


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


• Displacement in clockwise/counterclockwise
direction would result in canting & misfit of the
palate & maxillary arch in to either open / closed bite
positions

• Remodeling fields along nasal & oral sides of the
palate offset & compensate


2-3 – primary displacement
1-2 - Remodeling movement


Prediction of mandibular growth
Rotation
Bjork method
• Longitudinal method
• Metric method
• Structural method

Longitudinal method
• The course of development in annual x-ray
Cephalometric films

• Superimposed on natural reference strs


Rotation – angle b/n SN lines


Limitations
Pattern of growth is not constant
•

permits observation of changes only in sagittal
direction

• Changes in vertical direction are masked to
larger extent

Metric method
• Prediction of facial development on basis of facial
morphology ,determined from a single x-ray

• Statistical studies – predicting the intensity & direction of
development from shape & size at childhood is not feasible

• The changes in shape of face during adolescence weakly
correlated with shape of face at 12yrs

Structural method
• Based on information gained from implant
studies of mandibular remodeling process
• Recognizes specific structural signs
develop as a result of remodeling
• Various types of rotations can be
recognized with implant method

Structural signs
• Seven structural signs of extreme growth rotation
• Considered in relation to condylar growth direction
• Greater the number, more reliable the prediction will be.
• Signs are not clearly developed before puberty


• Inclination of condylar head
• Curvature of the mandibular canal
• The shape of the lower border of the mandible
• Inclination of the symphysis
• Interincisal angle
• Interpremolar and molar angles
• Lower anterior face height

Condylar Inclination


Mandibular Canal


Lower Border & Inclination of
Symphysis


Inter Incisal Inclination


Inter Molar Relation


• But Baumrind & Rodney lee contradicted
findings of Bjork et al very strongly


• The study conducted in our Department by violet
barbosa,
• Lower gonial angle
• Inclination of condylar head
• Inclination of symphysis are reliable signs to
predict the type of rotation
• Limited extent

Interaction b/n Rotation & Tooth
eruption
• Rotational pattern greatly influences the
magnitude & direction of eruption

• Superimposition on mand lower borderno change in incisor eruption


Forward Rotation
• Superimposition on implants – forward directed
path of eruption
• Forward migration of whole dentition
• Anterior crowding
• Lower post teeth- more upright
• Increase in interpremolar & intermolar angles

Average values:
Mandibular arch
Mean forward migration of mandibular molars 5.2mm.
Lower central incisors-3.2mm.
Shortening of the dental arch-2.0mm.


Average values:
• Maxillary arch
-Mesial migration I molars-5mm
-central incisors-2.5mm
Shortening of arch-1mm+1.5mm


Backward Rotation
• Incisors become retroclined
• Alv prognathism is reduced
• Eruption of lower molars – hindered
• Interpremolar& intermolar angles are
small

• Proffit
-The lower mandibular teeth erupt in upward and
forward direction.
-Forward rotation –alters the path of eruptiondirected posteriorly.


Clinical implications
Forward Rotation
•
•
•
•
•
•
•

Short face type
“Square jaw” type
Low mandibular plane
angle
Skeletal anterior deep bite
Crowding of anterior teeth
Palatal plane is nearly
horizontal.
smile - lower incisors are
visible with the upper
incisors hidden behind the
upper lip.

Backward Rotation
•
•
•
•
•
•

Long face type
“Round jaw” type
Steep mandibular plane
angle
Skeletal anterior open
bite
Dental protrusion
Negative inclination of
palatal plane


• Various combinations of rotations can cause
malocclusions


Growth Rotation can also affect sagittally
• Hypodivergent - can compensate for class II
- worsen class III

Hyperdivergent - worsen class II
- compensate for class III


Treatment in preadolescent
children
Growth modificationVertical, sagittal, transverse
Before adolescent growth spurt ends


• 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


• Forward Rotation
• Major risk of deep bite developing- prevented
stabilizing appliance introduced before
puberty

• After treatment, stabilization is necessary
until the growth of the jaws is completed

• Mandibular deficiency
• Functional appliances
• Removable appliances
Activator, Bionator, Frankel 1&2
Bimler’s appliance, Twin block appliance
• Fixed
Herbst appliance, Jasper jumper, Churro
jumper,Forsus

Mandibular excess
Functional appliances
Frankel 3
Reverse Activator


MANDIBULAR EXCESS
• extra oral force
• orthopedic
chin cup
• occipital pull chin cup
vertical pull chin cup
Steep mandibular plane
angle & excessive lower
facial height.

ADULTS
BILATERAL SAGITTAL SPLIT OSTEOTOMY

SET BACK

ADVANCEMENT


Maxillary deficiency
• Growth modulation in
sagittal plane can be done :
1.face mask

Delaire facemask

2.reverse functional
appliances.


Petite facemask

Maxillary excess
• To restrict the maxillary growth
Headgear


Cervical head gear:
used in patients with horizontal growth
pattern with reduced lower facial height.


Occipital pull Head gear:Used in long face patients with high mandibular
plane angle.


References
• Contemporary orthodontics
- William.R.Proffit(2nd &3rd ed.)
• Essentials of of facial growth
- Donald.H.Enlow.
• Dentofacial orthopaedics with functional
appliances
-Thomas M.Graber, Thomas Rakosi, Alexandrer
G.Petrovic.

• Facial growth and facial orthopedics.
-van der Linden.
• Determinants of mandibular form & growth (CFGS)
Monograph-4
• Factors effecting growth of the midface (CFGS)
Monogrph-6.
• The rotation of mandible resulting from growth;Its
implications in orthodontic treament
-F.F.Schudy-AO 1965.no.1,36-50.

• Prediction of growth rotation - A.Bjork-AJO-DO1969,jun 39-53.

• Facial development and tooth eruption :an
implant study at the age of pubertyA.Bjork,V.Skieller AJO-DO 1972,62,4;339-383.

• Normal and abnormal growth of mandible.a
synthesis of longitudinal cephalometric implant
studies over a period of 25
years.A.Bjork,V.Skieller.EJO-1983,5;1-46.

• The puzzle of growth rotation. J.M.H.Dibbets –AJODO June 1985 ,87,6;473-480.
• Mandibular rotations – concepts & terminology
Beni Solow & William Houston J B-EJO1988,10;177-179.
• Mandibular rotation and enlargement.
J.M.H.Dibbets.AJO-DO July 1990,29-32.
• Mandibular morphologic characteristics in relation to
various facial types and jaw rotations.- Dr. Violet
Barbosa Aug 1996.


Thank you
Leader in continuing dental education


Growth rotations /certified fixed orthodontic courses by Indian dental academy

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