Seminar on Mandibular Growth Rotation

SEMINARON
www.indiandentalacademy.comwww.indiandentalacademy.com

INTRODUCTION:INTRODUCTION:
The term growth rotation was introduced in 1955 by
Bjork. He used it to describe a particular phenomenon,
occurring during the growth of head.
History:
 At the time when x-ray cephalometry was introduced
research was concerned primarily with AVERAGE
GROWTH CHANGES in the form of face and head.
 These conventional x-ray measurement /tracings
showed comparatively small changes with age in the facial
form and intermaxillary relationship.www.indiandentalacademy.comwww.indiandentalacademy.com

A series of questions arose
(i) Is that intermaxillary relation static throughout the
period of growth?
(ii) If the facial form remain static with age then is the
treatment of malocclusion independent of age, sex or
maturation rate?
The answer was NO
 It was at this time when longitudinal studies with
cephalometry were conducted and the concept of
INDIVIDUAL DIFFERENCES in the development of
facial form and intermaxillary relations were recognized.www.indiandentalacademy.comwww.indiandentalacademy.com

 And it was Bjork who used metallic implants as
markers in the jaws from which he located,
1. Sites of growth and resorption in the individual jaws
and examined individual variation in direction &
intensity of growth.
2. The mechanisms underlying changes in the
intermaxillary relationship during growth.
 Until Bjork's studies, the extent to which both the
maxilla and mandible rotate during growth was not
appreciated.
 Bjork identified stable points
in the mandible and placed
implants on those points.
1. The core of the
mandible is the bone that
surround the inferior alveolar
nerve.
2. The rest of the
mandible consists of several
functional process.

 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 .
 In 1951, Bjork conducted a mixed longitudinal study by
the use of these implants in about 100 children of each sex
covering the age period from 4 to 24 years.
 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 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.

Thus these two factors the upward +forward growth
rotations of 15 degrees to 2-4 degrees.
 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.
BROADLY CLASSIFIED INTO
FORWARD ROTATION BACKWARD ROTATION
Type I Type II Type III Type I Type II

CORCOR FACIAL HEIGHTFACIAL HEIGHT CAUSECAUSE
AnteriorAnterior PosteriorPosterior
Type IType I JointJoint DecreaseDecrease
AFH DeepAFH Deep
bitebite
-- Occlusal imbalance dueOcclusal imbalance due
to loss of teeth /to loss of teeth /
powerful musculature.powerful musculature.
Type IIType II Inciscal edge ofInciscal edge of
the lowerthe lower
anterior teethanterior teeth
Normal AFHNormal AFH MarkedMarked
increasedincreased
PFHPFH
(i). Lowering at middle(i). Lowering at middle
cranial fossa, loweringcranial fossa, lowering
the condylar fossathe condylar fossa
(ii). Vertical growth at(ii). Vertical growth at
the mandibular condylethe mandibular condyle
Type IIIType III At the level ofAt the level of
premolarspremolars
DecreaseDecrease
AFH DeepAFH Deep
bitebite
IncreaseIncrease
PFHPFH
In anamolous occlusionIn anamolous occlusion
of anterior e.g.of anterior e.g.
Increased overjet.Increased overjet.
FORWARD ROTATIONS

CORCOR CAUSECAUSE FACIALFACIAL
Type IType I TMJTMJ 1. Raising of bite by1. Raising of bite by
orthodontic meansorthodontic means
Increased AFHIncreased AFH
2. Flattening of cranial2. Flattening of cranial
basebase
3. Oxycephaly3. Oxycephaly
Decreased PFHDecreased PFH
Increased AFHIncreased AFH
Type IIType II Most distalMost distal
occluding molarsoccluding molars
Growth in the saggitalGrowth in the saggital
direction at thedirection at the
mandibular condyulesmandibular condyules
Basal open biteBasal open bite
BACKWARD ROTATIONS
Less frequent than forward rotations

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

TYPE - I TYPE - II TYPE - III
TYPE - I TYPE - II

Double Chin
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
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.

Forward rotation
 Dentoalvealar proclination of lower anteriors
 Mesial path of eruption leading to crowding (packing)
Backward rotation
 Dentoalvealar retroclination of lower anteriors
 Crowding.
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.

Bjork also named 7 structural signs of extreme growth
rotations. He also stated these signs will help in a clinical
aspect to detect extreme types of mandibular rotation,
occurring during growth.
1. Inclination of the condylar head.
2. Curvature of the mandibular canal.
3. Shape of the lower border of the mandible
4. Inclination of the symphysis.
5. Inter Incisal Angle.
6. Inter premolar, Inter molar Angle.
7. Anterior lower Facial height.
 All these signs will not be found in an individual
 These signs are not clearly developed before puberty

Schudy’s concept of Mandibular notion
 ,The rotation of the mandible result from inharmony
between vertical growth and anteroposterior or horizontal
growth of the mandible.
 He dealt with growth increments which cause positional
changes of the chin.
 To those increments which cause the chin to move
vertically he applied the term -VERTICAL GROWTH
 To the one increment (condyle) which causes the chin to
move forward he applied - HORIZONTAL GROWTH
 He named the condyle as horizontal element and listed
out three vertical elements
1. growth at nasion & corpus of the maxilla.
2. growth of the maxillary posterior alveolar process
3. growth at the mandibular posterior alveolar process
causing the molar teeth to move occlusally.www.indiandentalacademy.comwww.indiandentalacademy.com

If the condylar growth is greater than the vertical growth
in the molar area, the mandible rotates COUNTER
CLOCKWISE resulting in horizontal change of the chin and
less increase in facial height Extreme of this condition cause
CLOSED BITES . causes increase in facial angle and
flattening of MANDIBULAR PLANE.
Conversely if vertical growth in the molar region is
greater than that at the condyles, the mandible rotates
CLOCKWISE resulting in more Anterior facial height.
Extremes of this condition cause OPEN BITES : with
steepening of mandibular plane.
 The horizontal condylar growth is pitted against the
combined vertical elements of growth . The final vector of
growth of the chin is a resultant of the struggle between
horizontal growth and vertical growth.

 When the growth at the condyle equals the growth of the
vertical elements, the net result is usually downward and
forward.
 In clockwise rotation the point of rotation being the
condyles.
 In counter clockwise rotation the point of rotation is the
most distal mandibular molar in occlusal contact.
He called the ratio between horizontal and vertical growth
increments as POSTERIOR GROWTH ANALYSIS. It is
this ratio depicting the relationship of vertical & horizontal
increments one to another that controls the forward
growth and rotation of the mandible.www.indiandentalacademy.comwww.indiandentalacademy.com

ENLOW’S CONCEPT OF MANDIBULAR ROTATION:
1. Displacement type
2. Remodeling type
Displacement type
 Rotational positioning of the entire mandible.
 Caused by changes in the placement of the functional
contacts with both the cranial floor and the maxilla.
 The dimensions & angular positions of the cranial floor
and maxilla directly affect the consequent rotational
position of the mandible.
 If cranial base angle is open downward and backward
DISPLACEMENT rotation of the mandible and converse
occurs if the angle is closed.
 If Nasomaxillary and dental complex is vertically long
downward and backward DISPLACEMENT rotation of
the mandible, and converse occurs if nasomaxillary
complex is vertically short.

Remodeling type
There are two reasons why a mandible undergoes the
remodeling type of rotation.
1. To produce a more upright ramous alignment relative to
the corpus.
This accommodates the continued vertical growth of
ethmomaxillary region and the eruption of permanent
dentition.
2. To provide ramus-corpus angular adjustments to
accommodate the effect of the whole mandible
displacement rotations.
e.g., : of the displacement rotation causes more upward &
forward alignment of the mandible as a whole then the
remodeling rotation, partially or completely offsets this by
opening the ramus-corpus angle.

DISPLACEMENT TYPE
REMODELLING TYPE

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.www.indiandentalacademy.comwww.indiandentalacademy.com

 As growith 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.www.indiandentalacademy.comwww.indiandentalacademy.com

 BJORK AND SKIELLER subsequently focused attention
on different patterns that emerged when different
registrations for superimposition were used.
 These various patterns can be expressed in a rotational
terminology.
I. Total rotation: The rotation of mandibular corpus
(implant line) relative to the anterior cranial base.
Solow an Houston - True rotation
Proffit - Internal rotation.
II. Matrix rotation: Rotation of soft-tissue matrix of the
mandible (Tangential mandibular line) relative to the
cranial base. Center - condyles

II. Solow an Houston - Apparent rotation
Proffit - Total rotations.
III. Intramatrix rotation: The difference between the total
rotation and the matrix rotation. The change in inclination
of an implant or reference line in the corpus relative to the
tangential mandibular line.
It is an expression of the remodeling at the lower border
of the mandible.
center – corpus.
III. Solow an Houston - Angular remodelling
PROFIT - External rotations

MATRIX AND INTRAMATRIX ROTATIONS

PROFFIT : Total Rotation = Internal - External
rotation rotation
BJORK : Matrix Rotation = Total - Intramatrix
rotation rotation
SOLOW : Apparent Rotation = True - Angular
rotation Remodelling
For an average individual with normal vertical facial
proportions there is about -15 of Internal Rotation (Total, True)
from 4 years – Adults life and 11-12° of external rotation.
(- sign = forward rotation).
X= 150
-(11-12)0
15° – External, Intramatrix,
Angular remodelling.
X= 30
- 40
3°
– 4°
- Total, Matrix,
Apparent.www.indiandentalacademy.comwww.indiandentalacademy.com

The different interpretations of the intra matrix rotation were
given by :
1.Lavergne and Gasson - He defined rotations as
a.Morphogenetic - Concerning the shape of the mandible
similar to intramatrix rotation.
b. Positional – Dealing with the position of the mandible.
They used a line joining condylon and pogonion to
super impose cephalogram and determine the angle between
the 2 implant lines.
They 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 condylar growth.
They postulated that intramatrix rotation is essentially
a compensating mechanism which is capable of reducing or
enlarging the mandibular length by opening or closing the
gonial angle.

2. Dibbets - He gave a third interpretation which is based on
two hypothetical divergent patterns of growth.
a. A circular growth pattern resulting in only intra matrix
rotation and no enlargement of the mandible.
b. A linear growth pattern characterized by absence of
intramatrix rotation but with mandibular enlargement.
He showed that the external configuration of the
mandible need not change its form or position within the
head to allow intramatrix rotation and any resorption or
deposition only serves to maintain the original contours.
He also stated that every millimeter of condylar
growth along the pogonion condylon diagonal would enlarge
the mandible by 1mm.
This is compensated by remodelling at the lower
border. This mechanism is termed as the counterbalancing
rotation. Thus counterbalancing rotation is a mechanism that
(i) Neutralizes effect of growth of the condylar cartilage.www.indiandentalacademy.comwww.indiandentalacademy.com

Rotation of Maxilla :
Core of the maxilla - above the alveolar process.
Functional process - alveolar process, bones
surrounding air passages.
Internal rotation: The cove of the maxilla undergoes a
small and variable degree of rotation forward or backward.
 At the same time resorption of bone on the nasal side and
apposition of bone on the palatal side in the anterior and
posterior part of palate occurs.
 Eruption of molars and incisors occurs.
 The above two factors account for the external rotation.
 For most patients the external rotation is opposite in
direction and equal in magnitude to Internal rotation.
 The two rotations thus cancel each other and the net change
in jaw orientation (palatal plane) is zero.
 Variation from this average pattern is common and result in
moderate variation in Jaw orientation.

ROTATION OF MAXILLA

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.www.indiandentalacademy.comwww.indiandentalacademy.com

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.
In the assessment of shape there are three methods.
I. Longitudinal method – Consists of following the course of
development in annual cephalometric films.
It is for the subjects displaying the most pronounced
changes in facial forms that the diagnosis of growth pattern
is important. www.indiandentalacademy.comwww.indiandentalacademy.com

Limitation
1. Pattern of growth is not constant and may be changed later.
2. Permits observation of changes in the saggital 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 sells lines for the two ages.

II. 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 and also the changes in shape of the
face during adolescence, expressed in terms of angular
measurements also weekly correlated with the shape of the
face at 12 years which is the age at which treatment is
instituted.
II. 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 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 each mm of forward movement of pogonion
Facial divergence and mandibular rotation
 The degree of facial divergence (SN – MP) has a
significant bearing on mandibular rotation.
 Larger SN-MP angle, the more the mandible tends to
become 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.www.indiandentalacademy.comwww.indiandentalacademy.com

REVIEW OF LITERATUREREVIEW OF LITERATURE
1. Schudy study :
Growth was studied on 62 patients.
29 – 11 – 14 years
33 – 8 – 11 years
Treated cases
50 – 11 – 14 years
 Aim of the study – To determine the cause of mandibular
rotation.
 Measuring vertical growth in the first molar teeth and
relating this growth to that at the mandibular condyles.

Results : -Results : -
Untreated Treated
Effective condyle growth 7.2 mm 6.7mm
Vertical growth 6.3mm 7.1mm
73% of vertical growth in the Untreated group
(4.6mm) was in the maxilla and 27% in the mandible.
Treated  68% maxilla, 32% mandible.
Thus he concluded that MAXILLA is responsible for
about 70% of total vertical growth and has an important
effect on the ‘tilt’ of the mandible.

2. Alf Tor Karlsen -1997 Angle orthodontist.
Study :
Aim : - Association between vertical craniofacial growth and
mandibular growth rotation.
Study group – Two groups
(i) Low MP-SN angle
(ii) High MP-SN angle
Nature - Longitudinal study from 6 – 15 years of age
Results : -
• Increased posterior - Positively correlated with
lower facial height FORWARD MATRIX ROTATION
Increase in ramus height Irrespective of MPA / age
2. Increase in LAFH - Weakly correlated with
mandibular rotation. (?)
Strongly and positively
correlated with increased in
corpus length

Over development of LAFH in high angle cases
occurred because the steep mandibular plane directed corpus
growth more downward.
3. 1995 A.O
The same author did a longitudinal study with boys
having low and high MP-SN angles.
Aim :- Compare the two groups with regard to dimensional
changes and mandibular growth rotation.
Result : - Significant correlations were almost exclusively
noted between dimensional change and total rotation and
dimensional change and matrix rotation.www.indiandentalacademy.comwww.indiandentalacademy.com

4. 1984 – Nov- Bjork and Skieller A.J.O.
Aim – To estimate the possibility of predicting the direction
and amount of growth rotation of the mandible on the basis
of morphologic criteria observed on a single profile
radiograph at pubertal age.
Forty four morphologic variables were employed and
four among them gave the best prognostic estimate (86%) of
mandibular growth rotation in the sample.
1.Mandibular inclination
a. Proportion between posterior and AFH (Index – I)
b. Lower Gonial angle (GOL)
c. Lower border inclination (NSL – ML1)

2. Inter molar angle (MOLs – MOLi)
3. Shape of lower border (ML1 – ML2)
4. Inclination of symphysis (CTL – NSL).
5. AJO Dec – 1998
In response to Bjork & Skieller’s article (1984 AJO)
Laurel R. Leslie Published a article assessing the reliability of
their method of predicting growth rotation using the four
variables.
 They concluded that only 9% of the variability in
mandibular growth rotation could be accounted for using the
four variables in combination in contrast to 83% given by
Bjork.
 Thus he stated that the method does not permit clinically
useful predictions of future mandibular growth rotation.www.indiandentalacademy.comwww.indiandentalacademy.com

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
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.
 Path of eruption of max teeth
 Downward and somewhat forward

 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).

MandibleMandible
Path of eruption of mandibular - Upward and forward
Teeth
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.www.indiandentalacademy.comwww.indiandentalacademy.com

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.

2. 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 MPADeep bite and
crowding
Excessive forward rotation may be due to
(i) Increase in internal mandibular rotation
(ii) Decrease in external rotationwww.indiandentalacademy.comwww.indiandentalacademy.com

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

3. 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 connect 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).
4. 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. www.indiandentalacademy.comwww.indiandentalacademy.com

6. 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).

COMBINATIONS OF ROTATIONS OF JAW BASES

7. Upward and forward tipping of anterior maxilla is often
observed in confirmed mouth breathers.
8. 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.www.indiandentalacademy.comwww.indiandentalacademy.com

CONCLUSIONCONCLUSION
Though different authors give different mechanisms
and terminologies for Growth rotations, the jaw should
rotate either forward or backward. It is upto the
orthodontists to identify the rotation early and its clinical
presentation and apply it in treatment, so that treatment
can be started at the earliest.

REFERENCESREFERENCES
1. Contemporary Orthodontics - Proffit
2. Handbook of Facial Growth - Enlow
3. Orthodontic Diagnosis - Rakosi
4. Dento facial orthopeadics with functional appliances -
Petrovic
5. Prediction of Mandibular growth rotation - Bjork (1969 June
AJO)
6. The rotation of the mandible resulting from growth : Its
implications in Orthodontic treatment - F.F. Schudy (1965
Angle Orthodontist
7. The puzzle of growth rotation - J.M.H. Dibbets (AJO
June 1995)
8. Mandibular rotation and enlargement – J.M.H. Dibbets (AJO
June 1990)
9. Bjork (1972) AJO

Seminar on Mandibular Growth Rotation

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Seminar on Mandibular Growth Rotation