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2. Introduction
Craniofacial growth has been the ground for research for
several years, starting from Genetic theory, Sutural
theory, Cartilaginous theory, Functional matrix theory,
Van Limborg’s theory and now the Cybernetic theory.
The Servosystem is a part of the cybernetic theory which
describes the craniofacial growth mechanism
systematically and also explains the functioning of the
various appliance system
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3. Genetic theory
Genotype supplies all the information required for the
phenotypic expression
The influence of the general, regional and local factors
modifying the gene expression
How does the modification occurs
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4. Sicher’s Sutural dominance theory
Craniofacial sutures are responsible for the growth
This theory acknowledge the importance of Genetic
theory
Sutures, cartilage and and Periosteum are growth centers
Sutures carry the genetic potential of the growth
pattern,thus sutural patterns were predetermined
Disapproved
Transplantation of the sutures
Moss’ experiment on rats
Hydrocephaly and microcephaly
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6. Cartilage directed theory of growth
Proposed by James Scott – 1953, 1954, 1967
Cartilage and periosteum as active and primary growth
centers
Sutures play a passive and secondary role
Cartilage have the intrinsic genetic potential
Nasal cartilage and mid face
Transplantation
Mandible and condylar cartilage
Achondroplasia
Disapproved
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8. Functional matrix
Proposed by Melvin Moss 1960, 1962, 1997
Original concept of Functional cranial component by Van
Der Klaaw
The origin, form, position ,growth and maintenance of
the skeletal tissue is secondary and compensatory to the
responses that occur in the specifically related non
skeletal tissues, organs or functioning spaces
Could not explain the control of the epigenetic factors
Functional matrix hypothesis revisited – 1997 AJO DOwww.indiandentalacademy.com
9. Functional matrix
Functional cranial component
Functional matrixSkeletal unit
Micro
Skeletal
unit
Macro
Skeletal
unit
Capsular
matrix
Periosteal
matrix
Transformation
Translation
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11. Cybernetic and control theory
Demonstrates the quantitative and qualitative relationship
between the observationally and experimentally collected
findings
Petrovic was the first to propose a cybernetic model to
account for the physiological phenomena involving
facial growth and functioning of the functional and
orthopeadic appliances
Observation findings Experimental finding
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12. Epistemplogic features
Branch of philosophy that deals with the possibility,
nature, origin, structure and validity of knowledge
Hypothesis
Refute
FAIL
Corroboration Strengthening
of the theory
Popper1963,
Science is not a
static
acceptance of
truth but rather
the permanent
search for truth
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13. Cibernetically organized biologic features
Orthodontic
functional , and
orthopaedic
appliances
o Maxillary
lengthening and
widening,
o mandibular
lengthening and
widening,
oTeeth movements
Correction of
malocclusion
and
intermaxillary
relation
INPUT BLACK BOX OUTPUT
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14. Classification of the loop systems
Physiologic systems
Closed loop system Open loop system
Regulator
system
Servosystem
Input
Not a
constant
constant
No comparator
No feed back
mechanism
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16. Command
Signal established independent of the feedback system
Affects the behavior of the control system without being
affected by the consequences
Eg. Growth hormones,testosterone, and estrogen
CONTROLLER
ACTUATOR
REFERENCE INPUT
ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
PERFORMANCE
AMPLIFIER
REFERENCE
INPUT
OPUTPUT
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17. Reference input element
Between the command and the reference input
Septal cartilage, septopremaxillary frenum, labionarinari
muscle and premaxillary and maxillary bone
REFERENCE INPUT
ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
CONTROLLER
ACTUATOR
PERFORMANCE
AMPLIFIER
REFERENCE
INPUT
OPUTPUT
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18. Reference input constantly changing variable
Signal established as a standard of comparison
Independent of the feedback mechanism
Sagittal position of the maxilla
REFERENCE INPUT ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
CONTROLLER
ACTUATOR
PERFORMANCE
AMPLIFIER REFERENCE
INPUTOPUTPUT
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19. Control of the maxillary growth
Direct effect Indirect effect
STH -
stomatomedin
Spheno occipital synchondrosis
Nasal septal cartilage
Lateral masses of ethmoid
Body and greater wing of sphenoid
Forward
growth of
septal
cartilage
Outward
growth
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20. Forward growth of septal cartilage
Thrust effect
Anterior extremity of the
nasal septal cartilage
Spreads laterally in
antero inferior direction
Penentrates into the
premaxillary bone
Premaxillomaxillary
suture
Maxillopalatine
suture
Thrust
effect
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21. Septopremaxillary ligament traction
Traction of the labionarinari muscle
Traction of the premaxillary bone through this muscle
Biomechanic promotion of the forward growth of the upper jaw
Absence of labial muscle attachment on the nasal septum –
cleftlip- bone deformation
Growth of the nasal
septal cartilage
Traction effect on the
premaxillary bone through
the Septopremaxillary
ligament
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22. Outward growth
Outward growth of the lateral cartilaginous
masses of the ethmoid and the cartilage
between the body and greater wings of
sphenoid
Produces a lateralization of the right and left
alveolar ridges
Stimulates the growth of the midpalatal suture
Outward growth of the
maxilla
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23. Performance and the performance
analysing elements
REFERENCE INPUT ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
CONTROLLER
ACTUATOR
PERFORMANC
E
AMPLIFIER
REFERENCE
INPUT
OPUTPUT
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24. The controller and the actuating signal
The central nervous system
Controls the activity of the lateral pterygoid muscle and
the retrodiscal pad
The A.signal is the response of muscle and the
retrodiscal pad
REFERENCE INPUT
ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
CONTROLLER
ACTUATOR
PERFORMANCE
AMPLIFIER
OPUTPUT
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25. Role of lateral pterygoid & retrodiscal pad
I CONTROL- INTACT LPM AND
RETRODISCAL PAD
NORMAL
II BILATERAL RESECTION OF LPM DECREASED NO OF DIVIDING
CELLS
DECREASED GROWTH RATE
OPENING OF STUTZMANN’S
ANGLE
DECREASED WIDTH OF MITOTIC
COMPARTMENT
III TMF CLAMPED BILATERALLY SAME AS II BUT LESS
INTENSE
IV TMF CLAMPED
LPM RESECTED
SAME AS II AND V
V TMF RESECTED SAME AS A II
VI LPM AND TMF RESECTED
BILATERALLY
NO CHANGE
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26. Retrodiscal pad
Partly a mediator of LPM as the blood supply is through
this muscle
Surgical resection causes diminished rate of growth of
condylar cartilage and lengthening of mandible
Blood circulating effect
Biomechanic effect
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27. Controlled system
Is the final outcome of the system
The sagittal position of the mandible
REFERENCE INPUT
ELEMENT
COMPARATOR
COMMAND
PERFORMANCE
ANALYSING
ELEMENTS
CONTROLLED
SYSTEM
CONTROLLER
ACTUATOR
PERFORMANCE
AMPLIFIER
REFERENCE
INPUT
OPUTPUT
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28. The Attractor
Structurally stable steady state in a dynamic system
Full interdigitation of the teeth be it class I, Class II or
Class III, with cusp to fossa relationship thus eliminating
The servosystem strives to achieve this stable form
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29. The Repeller
Unstable equilibrium state
Cusp to cusp type of occlusal relationship
The comparator detects this deviation signal and tries to
achieve the cusp to fossa relationship through the
servosystem
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30. Comparator
Central comparator Peripheral comparator
Detects the
disturbances in
periphery
Periodontal receptors
Repetitive
posturing of the
mandible
Sensory engram
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31. Functioning of functional appliances
Functional appliances
Increased contraction
of LPM
Additional growth of
condylar cartilage
In growth stimulating factors
Change in the condylar
trabecular orientation
Iterative activity of the
retrodiscal pad
Enhancement of local mediators
Reduction of local regulators
Additional subperiosteal
ossification of the posterior
border of mandible
Supplementary
lengthening of
the mandible
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32. Postural hyperpropulsor
Upper dental arch in a more
anterior position
Confrontation
between arches
Supplementary
lengthening of mandible
Contractile activity
of LPM
Reduced by fwd posturing
of mandible
Deviated signal
Reduced intensity
of the deviated
signal
Reduction in
anatomic
repositioning of
the mandible
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33. Class II elastics
No increase in the contractile activity
Action through the retrodiscal pad
Intrinsic regulation of the prechondroblasts multiplication
Biologic activator for stimulating effect of class II
elastics seem to be retrodiscal pad and its role as a
metabolic pump
Functional prechondroblast
stimulated growth rate
Restriction of the
prechondroblast multiplication
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34. Herren Activator
Two step effects
When the appliance is
worn
Reduced length of the
muscle as the mandible is
positioned forward
When the appliance is not
worn
The retrodiscal pad is
more stimulated
Early onset of hypertrophy
of the prechondroblasts
Growth rate of condylar
cartilage is increased
No stimulating effect on
the condylar cartilage
Effect similar to class II elastics
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35. Chin cap therapy
The number of dividing cells in the condylar cartilage is
decreased
Vertical growth direction and closing of the Stutzmann
angle
Decrease in the length of the mandible
Complete immobilization and the use of chin cap induces
the greatest decrease in the growth rate of condylar
cartilage and the lengthening of the mandible
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39. Effect of hormone - maxilla and mandible
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40. Lavergne and Petrovic,1983
Growth categories - taken both maxilla and mandible
into consideration
Three level arborization
I
l
e
v
e
l
2
l
e
v
e
l
3
L
e
v
e
l
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41. Petrovic growth categories
Growth inequality of bases
1 Mandible equal to maxilla
2 Mandible smaller than maxilla
3 Mandible greater than mandible
Rotation of the mandible
R Neutral
P Posterior rotation of mandible
A Anterior rotation of mandible
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44. I LEVEL
Mandible
greater than
maxilla
Mandible
less than
maxilla
Mandible equal to maxilla
Quantitative
determination of
difference between
maxilla and mandible
70%
3%25% Cell and molecular
biology level
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45. II LEVEL
PosteriorAnterior
Neutral
Relates to the
growth
rotation and growth
inclination
of both maxilla
and mandible
Partly on respiration,
phonation and deglutition
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47. Tissue level growth potential – level of subperiosteal
ossification rate and the level of alveolar bone turnover
rate
Tissue level growth responsiveness – the degree of
augmentation of the alveolar bone turnover resulting
from orthodontic treatment
Morphogenetic rotation – the change in the shape of the
mandible
Positional rotation – the change in the position of the
mandible with relation to adjacent structures
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48. Lavergne and Gasson, 1977
Six auxologic categories of the mandible
Depends on – tissue level growth potential
- tissue level growth responsiveness to
orthodontic, orthopaedic and functional appliances
helps define the biologic, inter individual variation of the
growing mandible
Clinicians must give more importance to tissue level
growth responsiveness than just determining the growth
direction
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50. Local factors affecting the condylar
cartilage
Cytoplasmic junction
between the skeletoblasts
become quantitatively
reduced
Inhibitory intercellular
stimulations are reduced
Cell division rate
increases
Rate of differentiation of
skeletoblasts to
prechondroblasts increases
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51. Consistent transmembrane ion flux variation
•Intra cellular Na ion concentration increased
•Intracellular K ion concentration is decreased
•Discharge of H ion from blasts cell is increased
•Increased pH
•Intracytoplasmic Ca concentration is low
Local factors affecting the condylar
cartilage
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52. Local coupling mechanism
Open loop part of the
system
Stimulating effect on the
cell multiplication
Growth hormone and
growth promoting factors
acting primarily by
inhibition of the restraining
signal
Closed loop part of the
system
Inhibitory effect on the
cell multiplication and
consists of regulators of
local origin
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53. Bifurcation
Cusp to cusp unstable position
corresponds to functional
discontinuity
Lack of interdental contacts
correspond to the absence of
both stable and bifurcation
situation
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54. Occlusal development
First phase
Morphogenetic process
leading to stable occlusion
Stable occlusal
development capable of
serving as a peripheral
comparator is not achieved
Creation of an engram is
not possible
Second phase
First phase coincides with
the establishment of the
occlusion to serve as the
peripheral comparator
Thus the creation of an
engram
Minimizes the possible
deviation to achieve
stable occlusal
adjustment
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55. Malfunctioning of the servosystem
Morphologically defective
peripheral comparator
Morphologically acceptable
peripheral comparator
Multiple caries
Extreme bruxism
Inadequate reference bases
Anterior rotating mand with
distal jaw basal relationship
Or a posteriorly rotating mand
with mesial interjaw basal
relation ship
The control system operates
faultlessly but is unable to
correct the discrepancy between
the growth rates of the upper
and lower jaw
Seen in anteriorly rotating mand
associated with mesial basal
interjaw relationship and in
posteriorly rotating mand
associated with distal basal inter
jaw relationship
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56. Conclusion
The treatment of dentofacial malrelations requires
considerable insight into the modalities of craniofacial
growth which is adequately understood only with a
knowledge of mechanisms controlling it,so far the
cybernetic language has been the best tool to render
accurately the intricacy and complexity of the
craniofacial growth and means to influence it clinically
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