CYBERNETICS
INDIAN DENTAL ACADEMY
Leader in continuing dental education

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www.indiandentalacade...
Greek word KYBERNETES (art of
steering)
Plato & Ampere
Norbart Weiner 1948
“ Science of control & communication
in animal ...
www.indiandentalacademy.com
 Cybernetics is the science that
studies the abstract principles of
organization in complex systems. It
is concerned not ...
• Based on communication & information
theory : particularly on feedback
control system.
• Has bought new concepts eg –ve ...
CYBERNETICS
The science of control and
communication in biological,
electronic and mechanical systems.
This includes analy...
• Permits display of qualitative and
quantitative relationship between
observed and experimental findings
(what I see is w...
Cybernetic features:
1 Placing observations next to each
other
2.diagram displaying qualitative
relations b/w observations...
Cybernetics

Transfer of Information

• Cybernetic systems operate through
transfer of information
•

Physical,

Chemical,...
Black box concept
Input

Black Box

Output

Input

Transfer function

Output

Black box is the physiologic system under st...
Input
Orthodontic,
Functional,
& orthopedic
appliances

Black Box
Genetically determined &
cybernetically organized
biolog...
• Identification & analysis of
feedback loops are among main tasks
in craniofacial growth .
• So far, cybernetic language ...
Pavlovian concept of
accommodation in biological
systems
 Conditioning
 Reinforcement
 Habituation
Living animals respo...
Morphophysiologic system
Open loop

closed loop

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Open Loop
Output

has no effect on the input

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Refutations
1. Steiner & Brown
“The
North Carolina
chain gang”

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2. Post retention
Relapse

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Principle of optimality
Feedback controlled behavioral
Pattern is assessed.
Deviation b/w given state of
system + desired ...
Closed Loop
Relationship maintained between
input and output

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Closed Loop systems
Input

Regulation of effect

Measure of effect

Return of modified information
www.indiandentalacademy...
Closed Loop

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Morphophysiologic systems

Open loop

closed loop
Regulator

www.indiandentalacademy.com

Servosystem
These concepts of cybernetics :
1.Mechanism of craniofacial Growth
2.Method of operation of orthopedic
& orthodontic appli...
• Theory of facial growth based
on these concepts of
cybernetics is servosystem

www.indiandentalacademy.com
Control of
maxillary growth
• Direct effect : STH
preosteoblast
• Indirect effect : thr
intermediaries
www.indiandentalaca...
Types of Cartilage
Primary

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Types of Cartilage
Secondary

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Double differentiating
potential of skeletoblasts

www.indiandentalacademy.com
Primary Cartilage:
Epiphysis,

Synchondrosis,

Nasal Septum, Ethmoid
Sphenoid
Secondary Cartilage:
Condyle, Coronoid, Mid ...
Factors
influencing
Growth

Primary
Cartilage

Secondary
Cartilage

Hormones

Yes

Yes

Local Factors No

Yes (Pre-

(Chon...
Growth of the maxilla

Growth in
Length

Growth in
Height

www.indiandentalacademy.com

Growth in
Width
Growth in Length:
Traction
SeptoPremaxillary
ligament

Induction

Growth of
Nasal Septum

Biomechanical

Labio narinary
Mu...
Growth in Width:
Growth of
Lateral cartilaginous
masses of Ethmoid

Release of
STH
Somatomedin

Transverse
Separation of
p...
www.indiandentalacademy.com
Growth in height

www.indiandentalacademy.com
Control of Mandibular Growth
Role of Lateral Pterygoid & Retrodiscal Pad
Two roles :
•Blood
Supply
•Biomechanic

www.india...
Metabolic role
Increase
• Blood & Lymph flow
• nutritive factors
Decrease
• Cell catabolites
• -ve feedback factors
www.in...
Biomechanic role

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Relationship Between Lateral Pterygoid,
Retrodiscal Pad and Condyle

MENISCUS

LPM
RDP

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Somatomedin & LPM
Interaction

www.indiandentalacademy.com
• Definitions
• Command : signals established
independent of feedback system
under scrutiny.
• Reference input elements:
e...
•Actuating signal :corresponds to
output signal of the controller
• Controlled system : b/w actualing
signal & directly co...
Components of a Servosystem
Reference Input Elements

Reference Input

COMMAND
Actuator,
Coupling
System

Controlled syste...
The Face as a Servosystem
Input –

Maxillary dental arch

Output – sagittal position of the
mandible.

www.indiandentalaca...
The Face as a Servosystem
Release of
Hormones(Command)

LPM & RDP

(Coupling system)
Actuating
signal

Hormones

Growth at...
The Sensory Engram

• Blueprint of ideal muscular
function/position
• Collection of feedback loops

• CNS tends to operate...
www.indiandentalacademy.com
Other Terms Related to a Servosystem

Gain

=

Output
Input

Amplification

(Gain>1)

Attenuation

(Gain <1)

www.indiande...
Attractor

Cusp to fossa relation

Repeller

Cusp to cusp relation

Disturbances

Abnormal tooth position
Occlusal interfe...
Peripheral Comparator
Before development of Occlusion:•Sensory engram not
developed
•Servosystem does not
operate
•Genetic...
Discontinuities

Stable

Unstable

Stable

Catastrophe Theory
So , a class II molar r/l will never spontaneously revert
ww...
Bifurcation

www.indiandentalacademy.com
Importance of Discontinuities
Facial growth should be accounted for by
using unpredetermined & discontinous
models rather ...
Cybernetics
Dr.Rekha
www.indiandentalacademy.com
The Face as a Servosystem
Release of
Hormones(Command)

LPM & RDP

(Coupling system)
Actuating
signal

Hormones

Growth at...
www.indiandentalacademy.com
Failure of Servosystem to Control
Growth
• Peripheral comparator faulty –
Caries, Mutilated dentition.
•Discrepancy betwee...
Action of Functional
Appliances

www.indiandentalacademy.com
www.indiandentalacademy.com
Mode of action of
functional Appliances
Functional appliance

LPM
Retrodiscal Pad
Growth stimulating factors
Lengthening o...
Two Types of Functional Appliances

1) Activator, Postural hyperpropulsor,
Frankel appliance, Twin block,
Bionator, Class ...
FIRST

GROUP:

Forward Position

mandible:

Increased activity of
LPM and RDP
LPM “helped to contract more” by
Functional ...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
CELLULAR LEVEL
1. Precursor
Skeletoblast –
pleuripotent,
fibroblast like.
2. Prechondroblast
– faster cell
cycle, matures
...
Chondroblasts lost
removed)

(hypertrophy, surgically

Increased
multiplication of
prechondroblasts
Local
control
over
mul...
www.indiandentalacademy.com
Functional appliances (especially Class
II elastics)
Increased activity
of RDP

Increased nutrients and growth
factors
inh...
Cytoplasmic junctions between
skeletoblasts reduce.

Transmission of inhibitory factors reduce.

Increased mitotic rate an...
Reduced negative feedback
signal reaching
prechondroblasts

Increased growth at the
condyle

www.indiandentalacademy.com
SECOND GROUP:
Position mandible forward , open in
beyond rest position.
Viscoelastic property of muscle is imp
No increase...
• Proponents contend that the use
of myotactic reflex should be
largely ignored.
• Alveolar remodelling is
obtained from t...
wo steps:

)While appliance is worn:Forward position
increase in length of LPM
New sensory engram

)While appliance is not...
Action of first group
while appliance is worn

Action of second group
while appliance is not worn

www.indiandentalacademy...
A New Parameter for
estimating condylar growth
direction

• Growth direction of condyle
coincides in general with the axes...
Stutzmann’s angle increases
at the beginning of
treatment(only a transient
remedial event).
Closes: horizontal growth
patt...
CLINICAL IMPLICATIONS
1)Principle of optimality of function :
Less relapse tendency if post
orthodontic treatment muscular...
2) Removal of functional appliance
– when growth is complete.
3) If removed when growth not
complete – Proper intercuspati...
4) Understanding of when, and for how long
a particular functional appliance
should be worn.
First group – Full time
Secon...
5)

Proper functioning of LPM and RDP
important for growth – Proper
parent counseling.

6) Sensory engram poorly developed...
Drawbacks
Lot of importance on condyle:
Fracture?

)Peripheral comparator (occlusion)
itself is unstable.
discrepancies ma...
) Occurrence of Class II end on
relation is seen often?

) Action of reverse pull headgear
on maxilla (primary cartilage)
...
References
Dentofacial Orthopedics with Functional
Appliances
Graber, Rakosi, Petrovic

Craniofacial Growth Series – Mon...
Treatment objectives and case retention:
Cybernetic and myometric considerations
1970

R.M. Jacobs Am J Orthod, 58:552-56...
www.indiandentalacademy.com
Leader in continuing dental education

www.indiandentalacademy.com
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Cybernetics /certified fixed orthodontic courses by Indian dental academy

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Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Cybernetics /certified fixed orthodontic courses by Indian dental academy

  1. 1. CYBERNETICS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Greek word KYBERNETES (art of steering) Plato & Ampere Norbart Weiner 1948 “ Science of control & communication in animal & machine” ART OF ENSURING THE EFFICACY OF ACTION. Once regarded as pointless sophistication in accounting for www.indiandentalacademy.com biologic & biomedical findings.
  3. 3. www.indiandentalacademy.com
  4. 4.  Cybernetics is the science that studies the abstract principles of organization in complex systems. It is concerned not so much with what systems consist of, but how they function. The cybernetic theory postulates that everything affects everything & therefore organized living systems never operate in an open-loop manner www.indiandentalacademy.com
  5. 5. • Based on communication & information theory : particularly on feedback control system. • Has bought new concepts eg –ve & +ve feedback,self regulation,reference input ,open & close loop www.indiandentalacademy.com
  6. 6. CYBERNETICS The science of control and communication in biological, electronic and mechanical systems. This includes analysis of feedback mechanics that serve to govern or modify the actions of various systems. TABER’S CYCLOPEDIC MEDICAL DICTIONARY 16TH ED www.indiandentalacademy.com
  7. 7. • Permits display of qualitative and quantitative relationship between observed and experimental findings (what I see is what I report) • Broader understanding of orthodontic problems, and action of appliances • Rigorous language of cybernetics is the most app way to lead to the current use of computers www.indiandentalacademy.com
  8. 8. Cybernetic features: 1 Placing observations next to each other 2.diagram displaying qualitative relations b/w observations. 3.mathematical language to describe interactions among various parts of morphophysiologic system. 4.cybernetics based on communication & information theory : mainly on feedback control system is also a useful research approach www.indiandentalacademy.com
  9. 9. Cybernetics Transfer of Information • Cybernetic systems operate through transfer of information • Physical, Chemical, Electromagnetic www.indiandentalacademy.com
  10. 10. Black box concept Input Black Box Output Input Transfer function Output Black box is the physiologic system under study www.indiandentalacademy.com
  11. 11. Input Orthodontic, Functional, & orthopedic appliances Black Box Genetically determined & cybernetically organized biologic features of Phenomena characterizing, inducing, or controlling spontaneous & appliancemodulated growth relative To the following: •Max. lengthening & •Widening •Mandible lengthening •Teeth movements www.indiandentalacademy.com Output Correction of malocclusion & Intermax. malrelation
  12. 12. • Identification & analysis of feedback loops are among main tasks in craniofacial growth . • So far, cybernetic language has been the best tool to render accurately the intricacy & complexity of craniofacial morphogenesis & the means to influence it clinically. www.indiandentalacademy.com
  13. 13. Pavlovian concept of accommodation in biological systems  Conditioning  Reinforcement  Habituation Living animals respond passively to stimuli www.indiandentalacademy.com
  14. 14. Morphophysiologic system Open loop closed loop www.indiandentalacademy.com
  15. 15. Open Loop Output has no effect on the input www.indiandentalacademy.com
  16. 16. Refutations 1. Steiner & Brown “The North Carolina chain gang” www.indiandentalacademy.com
  17. 17. 2. Post retention Relapse www.indiandentalacademy.com
  18. 18. Principle of optimality Feedback controlled behavioral Pattern is assessed. Deviation b/w given state of system + desired optimal state of system is fed back as input : system then take action to reduce this deviation to a min. www.indiandentalacademy.com
  19. 19. Closed Loop Relationship maintained between input and output www.indiandentalacademy.com
  20. 20. Closed Loop systems Input Regulation of effect Measure of effect Return of modified information www.indiandentalacademy.com
  21. 21. Closed Loop www.indiandentalacademy.com
  22. 22. Morphophysiologic systems Open loop closed loop Regulator www.indiandentalacademy.com Servosystem
  23. 23. These concepts of cybernetics : 1.Mechanism of craniofacial Growth 2.Method of operation of orthopedic & orthodontic appliance. www.indiandentalacademy.com
  24. 24. • Theory of facial growth based on these concepts of cybernetics is servosystem www.indiandentalacademy.com
  25. 25. Control of maxillary growth • Direct effect : STH preosteoblast • Indirect effect : thr intermediaries www.indiandentalacademy.com
  26. 26. Types of Cartilage Primary www.indiandentalacademy.com
  27. 27. Types of Cartilage Secondary www.indiandentalacademy.com
  28. 28. Double differentiating potential of skeletoblasts www.indiandentalacademy.com
  29. 29. Primary Cartilage: Epiphysis, Synchondrosis, Nasal Septum, Ethmoid Sphenoid Secondary Cartilage: Condyle, Coronoid, Mid Palatal Suture, Fracture Callus www.indiandentalacademy.com
  30. 30. Factors influencing Growth Primary Cartilage Secondary Cartilage Hormones Yes Yes Local Factors No Yes (Pre- (Chondroblasts surrounded by matrix) Orthopaedic appliances chondroblasts not surrounded by matrix) Only Direction Direction and Amount Charlier, Petrovic, Stutzmann www.indiandentalacademy.com Strasburg, France
  31. 31. Growth of the maxilla Growth in Length Growth in Height www.indiandentalacademy.com Growth in Width
  32. 32. Growth in Length: Traction SeptoPremaxillary ligament Induction Growth of Nasal Septum Biomechanical Labio narinary Muscles Release of STH Somatomedin Thrust Growth of Pre Maxillary extremity Anterior shift Of premaxillary bones Growth of PremaxilloMaxillary suture Protrusion of Upper Incisors Increased size Of Tongue Thrust Protrusion of Lower Incisors www.indiandentalacademy.com Direct Action Growth of Maxillo Palatine suture
  33. 33. Growth in Width: Growth of Lateral cartilaginous masses of Ethmoid Release of STH Somatomedin Transverse Separation of premaxillae Outward growth Of maxillary bones Growth of cartilage B/w greater wings & body of sphenoid Increased size Of Tongue Outward shift of Alveolus and molars www.indiandentalacademy.com Direct effect Growth of inter Pre Maxillary suture Transverse Separation of Horizontal Maxilla and Palatine plates Growth of mid Palatine suture Outward Appositional Bone growth
  34. 34. www.indiandentalacademy.com
  35. 35. Growth in height www.indiandentalacademy.com
  36. 36. Control of Mandibular Growth Role of Lateral Pterygoid & Retrodiscal Pad Two roles : •Blood Supply •Biomechanic www.indiandentalacademy.com
  37. 37. Metabolic role Increase • Blood & Lymph flow • nutritive factors Decrease • Cell catabolites • -ve feedback factors www.indiandentalacademy.com
  38. 38. Biomechanic role www.indiandentalacademy.com
  39. 39. Relationship Between Lateral Pterygoid, Retrodiscal Pad and Condyle MENISCUS LPM RDP www.indiandentalacademy.com
  40. 40. Somatomedin & LPM Interaction www.indiandentalacademy.com
  41. 41. • Definitions • Command : signals established independent of feedback system under scrutiny. • Reference input elements: establish r/lship b/w command & reference input • Reference input : signal established as a standard of comparison. • Controller : located b/w deviation & actualling signal www.indiandentalacademy.com
  42. 42. •Actuating signal :corresponds to output signal of the controller • Controlled system : b/w actualing signal & directly controlled variable. • control variable : output signal of the system. www.indiandentalacademy.com
  43. 43. Components of a Servosystem Reference Input Elements Reference Input COMMAND Actuator, Coupling System Controlled system (Controlled Variable) Performance Analyzing Elements Central Comparator (sensory engram) Output COMPARATOR Deviation Signal www.indiandentalacademy.com Performance
  44. 44. The Face as a Servosystem Input – Maxillary dental arch Output – sagittal position of the mandible. www.indiandentalacademy.com
  45. 45. The Face as a Servosystem Release of Hormones(Command) LPM & RDP (Coupling system) Actuating signal Hormones Growth at condyle (Controlled System) Position of Maxillary Dental arch (Ref Input) Output Actuator (Motor Cortex) Brain (sensory engram) Deviation Signal www.indiandentalacademy.com OCCLUSION (Comparator) Periodontium, Teeth Musculature Joint Mastication (Performance)
  46. 46. The Sensory Engram • Blueprint of ideal muscular function/position • Collection of feedback loops • CNS tends to operate along these feedback loops www.indiandentalacademy.com
  47. 47. www.indiandentalacademy.com
  48. 48. Other Terms Related to a Servosystem Gain = Output Input Amplification (Gain>1) Attenuation (Gain <1) www.indiandentalacademy.com
  49. 49. Attractor Cusp to fossa relation Repeller Cusp to cusp relation Disturbances Abnormal tooth position Occlusal interferences Arthritis Muscle Inflammation Periodontitis, Pulpitis www.indiandentalacademy.com
  50. 50. Peripheral Comparator Before development of Occlusion:•Sensory engram not developed •Servosystem does not operate •Genetic influence on mandibular growth •Anodontia After Development of Occlusion:•Sensory engram forms •Peripheral comparator controls growth www.indiandentalacademy.com
  51. 51. Discontinuities Stable Unstable Stable Catastrophe Theory So , a class II molar r/l will never spontaneously revert www.indiandentalacademy.com to class I
  52. 52. Bifurcation www.indiandentalacademy.com
  53. 53. Importance of Discontinuities Facial growth should be accounted for by using unpredetermined & discontinous models rather continous & deterministic ones. Stability of occlusion after it is established • Genotype does partially influence the phenotype www.indiandentalacademy.com
  54. 54. Cybernetics Dr.Rekha www.indiandentalacademy.com
  55. 55. The Face as a Servosystem Release of Hormones(Command) LPM & RDP (Coupling system) Actuating signal Hormones Growth at condyle (Controlled System) Position of Maxillary Dental arch (Ref Input) Output Actuator (Motor Cortex) Brain (sensory engram) Deviation Signal www.indiandentalacademy.com OCCLUSION (Comparator) Periodontium, Teeth Musculature Joint Mastication (Performance)
  56. 56. www.indiandentalacademy.com
  57. 57. Failure of Servosystem to Control Growth • Peripheral comparator faulty – Caries, Mutilated dentition. •Discrepancy between rotation pattern (Anterior or Posterior) and location of comparator. www.indiandentalacademy.com
  58. 58. Action of Functional Appliances www.indiandentalacademy.com
  59. 59. www.indiandentalacademy.com
  60. 60. Mode of action of functional Appliances Functional appliance LPM Retrodiscal Pad Growth stimulating factors Lengthening of mandible www.indiandentalacademy.com
  61. 61. Two Types of Functional Appliances 1) Activator, Postural hyperpropulsor, Frankel appliance, Twin block, Bionator, Class II Elastics(?) ) Herren activator, LSU activator, Harvold-Woodside activator, Extra oral traction on the mandible. www.indiandentalacademy.com
  62. 62. FIRST GROUP: Forward Position mandible: Increased activity of LPM and RDP LPM “helped to contract more” by Functional appliances. i.e myotactic reflex & isometric contractions www.indiandentalacademy.com
  63. 63. www.indiandentalacademy.com
  64. 64. www.indiandentalacademy.com
  65. 65. www.indiandentalacademy.com
  66. 66. CELLULAR LEVEL 1. Precursor Skeletoblast – pleuripotent, fibroblast like. 2. Prechondroblast – faster cell cycle, matures into Chondroblast www.indiandentalacademy.com
  67. 67. Chondroblasts lost removed) (hypertrophy, surgically Increased multiplication of prechondroblasts Local control over multiplication of prechondroblasts Originates from chondroblastic layer •Stutzmann and Petrovic (1982, 1990) www.indiandentalacademy.com
  68. 68. www.indiandentalacademy.com
  69. 69. Functional appliances (especially Class II elastics) Increased activity of RDP Increased nutrients and growth factors inhibitors removed. Increased mitoses and earlier hypertrophy of chondroblasts. www.indiandentalacademy.com
  70. 70. Cytoplasmic junctions between skeletoblasts reduce. Transmission of inhibitory factors reduce. Increased mitotic rate and rate of differentiation into prechondroblasts. www.indiandentalacademy.com
  71. 71. Reduced negative feedback signal reaching prechondroblasts Increased growth at the condyle www.indiandentalacademy.com
  72. 72. SECOND GROUP: Position mandible forward , open in beyond rest position. Viscoelastic property of muscle is imp No increase in activity of LPM •Herren (1953) •Auf der Maur (1978) •Yet there was an increase in growth www.indiandentalacademy.com
  73. 73. • Proponents contend that the use of myotactic reflex should be largely ignored. • Alveolar remodelling is obtained from the inherent elasticity of muscle,tendinous tissue, skin without motor stimulation. www.indiandentalacademy.com
  74. 74. wo steps: )While appliance is worn:Forward position increase in length of LPM New sensory engram )While appliance is not worn:New sensory engram Functioning in anterior position Increased activity of RDP www.indiandentalacademy.com
  75. 75. Action of first group while appliance is worn Action of second group while appliance is not worn www.indiandentalacademy.com
  76. 76. A New Parameter for estimating condylar growth direction • Growth direction of condyle coincides in general with the axes of individual trabeculae ,located just inferior to the central part of the condylar cartilage. • Stutzmann’s angle : trabecular alignment with mandibular plane. www.indiandentalacademy.com
  77. 77. Stutzmann’s angle increases at the beginning of treatment(only a transient remedial event). Closes: horizontal growth pattern. Opens : vertical growth pattern. www.indiandentalacademy.com
  78. 78. CLINICAL IMPLICATIONS 1)Principle of optimality of function : Less relapse tendency if post orthodontic treatment muscular activity produces a lower deviation signal. www.indiandentalacademy.com
  79. 79. 2) Removal of functional appliance – when growth is complete. 3) If removed when growth not complete – Proper intercuspation. www.indiandentalacademy.com
  80. 80. 4) Understanding of when, and for how long a particular functional appliance should be worn. First group – Full time Second group – Part time www.indiandentalacademy.com
  81. 81. 5) Proper functioning of LPM and RDP important for growth – Proper parent counseling. 6) Sensory engram poorly developed in younger children. 7) Utilization of high hormonal activity at puberty. www.indiandentalacademy.com
  82. 82. Drawbacks Lot of importance on condyle: Fracture? )Peripheral comparator (occlusion) itself is unstable. discrepancies may be overcome by Dentoalveolar changes rather than growth of Mandible. www.indiandentalacademy.com
  83. 83. ) Occurrence of Class II end on relation is seen often? ) Action of reverse pull headgear on maxilla (primary cartilage) www.indiandentalacademy.com
  84. 84. References Dentofacial Orthopedics with Functional Appliances Graber, Rakosi, Petrovic Craniofacial Growth Series – Monograph (Craniofacial Growth Theory and Orthodontic Treatment – Edited by Carlson) www.indiandentalacademy.com
  85. 85. Treatment objectives and case retention: Cybernetic and myometric considerations 1970 R.M. Jacobs Am J Orthod, 58:552-564, Grant’s Atlas of Anatomy www.indiandentalacademy.com
  86. 86. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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