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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Canine Impaction and Its Importance in OrthodonticsAnalhaq Shaikh
Canine Impaction, Its Importance in Orthodontics, Etiology, Diagnosis and Management.
by Dr Analhaq Shaikh, 2nd year Postgraduate student, Sharavathi Dental College and Hospital, Shimoga, Karnataka
Canine Impaction can also be termed as Shy Canine.
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Canine Impaction and Its Importance in OrthodonticsAnalhaq Shaikh
Canine Impaction, Its Importance in Orthodontics, Etiology, Diagnosis and Management.
by Dr Analhaq Shaikh, 2nd year Postgraduate student, Sharavathi Dental College and Hospital, Shimoga, Karnataka
Canine Impaction can also be termed as Shy Canine.
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Growth rotations in relation to Orthodontics.
Determining rotational growth changes
Mandibular rotations
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
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3. Page 3
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
4. Page 4
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 .
5. Page 5
ENLOWS CONCEPT
basic categories of rotations:
remodelling rotations displacement rotations
FUNDAMENTAL PRINCIPLE OF GROWTH
6. Page 6
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
8. Page 8
Schematic representation of mandibular growth, showing
the fetal mandible superimposed
upon the adult mandible.
9. Page 9
Displacement rotations
The whole bone is carried by mechanical force as it simultaneously enlarges .
10. Page 10
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
11. Page 11
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
12. Page 12
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
13. Page 13
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
14. Page 14
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.
15. Page 15
AJO JUNE 1969 , VOL 55 , ISSUE 6 , P 585-599
16. Page 16
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
17. Page 17
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
19. Page 19
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
21. Page 21
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
23. Page 23
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
25. Page 25
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
26. Page 26
Finally he also concluded that
Mandibular growth Rotation is closely associated with both the direction & the
amount of growth at the condyles
27. Page 27
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.
35. Page 35
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 .
36. Page 36
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
38. Page 38
After conducted the implant study they concluded that
Divided the
mandibular rotations
into three
components
• Total rotation
• Matrix rotation
• Intramatrix rotation
39. Page 39
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,‘-’
40. Page 40
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
41. Page 41
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.
42. Page 42
The diff b/n Total Rotation & Matrix Rotation is
intramatrix Rotation
43. Page 43
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.
45. Page 45
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
46. Page 46
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
47. Page 47
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
48. Page 48
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.
49. Page 49
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
50. Page 50
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 .
52. Page 52
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
53. Page 53
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
54. Page 54
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.
55. Page 55
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.)
58. Page 58
• 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,
59. Page 59
PROFFIT S CLASSIFICATION
rotation depending location of growth
Internal external
rotation rotation
Total rotation
60. Page 60
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
61. Page 61
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
62. Page 62
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
63. Page 63
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.
64. Page 64
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
65. Page 65
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
66. Page 66
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 .
67. Page 67
Growth of maxilla occurs by two ways
– Passive displacement- in primary dentition
period
– Active growth is by surface remodeling
69. Page 69
Displacement Rotations
Primary displacement
The whole nasomaxillary
complex is displaced in
conjunction with its own
growth
70. Page 70
Secondary Displacement
- Results from growth of other bones & their soft tissues
71. Page 71
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
72. Page 72
Based on this they gave the various terminologies
Internal rotation
External rotation
Forward growth
rotation
Backward rotation
73. Page 73
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.
74. Page 74
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
75. Page 75
Combination of IR and ER
•Forward rotation
•Backward rotation
Bjork and
skeiller
observed 2
types of
rotational
growth
76. Page 76
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
77. Page 77
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
78. Page 78
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 .
79. Page 79
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 .
80. Page 80
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.
81. Page 81
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.
82. Page 82
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
85. Page 85
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 .
87. Page 87
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.
88. Page 88
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.
89. Page 89
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