Cybernetic Theory
of
Craniofacial Growth
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacade...
Introduction
• Sutural
Genetic locus

• Cartilaginous
• Functional matrix

www.indiandentalacademy.com
CYBERNETICS
The science of control and communication in
biological, electronic and mechanical systems.
This includes analy...
Petrovic 1977
• Demonstrate qualitative and quantitative
relationship between observed and experimental
findings.
• Broade...
Cybernetics

Transfer of Information

• Cybernetic systems operate through transfer of
information
• Physical, Chemical, E...
Input

Input

Process

Cybernetic
System
Transfer Function

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Output

Output
Physiological cybernetic systems

Open loop

Closed loop

Regulator

Servosystem

Comparator

Feedback

www.indiandentalac...
Open Loop
Output has no effect on the input

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Closed Loop
Relationship maintained between input and output

Input

Comparator

Feedback
Loop

Transfer function

Output
...
Regulation Type of Closed Loop
Input is constant
Any change of the input will initiate a “regulatory
process”
Input

Compa...
Servosystem Type of Closed Loop

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Components of a Servosystem
COMMAND

Reference Input Elements

Actuator, Coupling System,
Controlled System

COMPARATOR
Ou...
Growth of the Face
According to the
Servosystem Theory
www.indiandentalacademy.com
Types of Cartilage
Primary

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Types of Cartilage
Secondary

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Primary Cartilage:
Epiphysis, Synchondrosis, Nasal Septum, Ethmoid
Sphenoid
Secondary Cartilage:
Condyle, Coronoid, Mid Pa...
Factors influencing Primary
Growth
Cartilage

Secondary
Cartilage

Hormones

Yes

Yes

Local Factors

No (Chondroblasts

Y...
Role of Lateral Pterygoid and Retrodiscal Pad

•Blood Supply

•Bio-mechanic

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Relationship Between Lateral Pterygoid,
Retrodiscal Pad and Condyle

MENISCUS

LPM
RDP

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Stutzmann and Petrovic

Proper function of Lateral Pterygoid and
retrodicsal pad:
• Excision of Lateral Pterygoid
• Reduce...
The Face as a Servosystem

Input – Maxillary dental arch

Output – Adjustment of the position of mandibular
dental arch
ww...
The Face as a Servosystem
Release of
Hormones (Command)

LPM & RDP
(Coupling system)

Position of Maxillary
Dental arch (R...
Growth of the maxilla

Growth in
Length

Growth in
Width

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Growth in Length:

Traction
SeptoPremaxillary
ligament

Induction

Growth of
Nasal Septum

Biomechanical

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

Release of
STH
Somatomedin

Transverse
Separation of
p...
Growth at the Posterior Border of the Ramus

www.indiandentalacademy.com
Other Terms Related to a Servosystem
Gain

=

Output
Input

Amplification (Gain>1)

Attenuation (Gain <1)

1. Large amount...
Attractor

Cusp to fossa relation

Repeller

Cusp to cusp relation

Disturbances

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

Stable

Unstable

Catastrophe Theory
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Stable
Bifurcation

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Height of
Bifurcation

OR

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Importance of Discontinuities

•Growth prediction , treatment planning , decision making
•Stability of occlusion after it ...
Failure of Servosystem to Control Growth
• Peripheral comparator faulty – Caries,
Mutilated dentition.
•Discrepancy betwee...
The Sensory Engram

• Collection of feedback loops
• Blueprint of ideal muscular function/position
• CNS tends to operate ...
Optimality of Function

•Minimum deviation signal
•CNS always tries to revert back to optimal position
•Observation of Cha...
Development of Skeletal Malocclusion
According to the Servosystem Theory

www.indiandentalacademy.com
For every unit of Growth hormone released,
the amount of growth in the maxilla is less than
in the mandible.

www.indiande...
Increase in length

LPM(max)
LPM(norm)
LPM(min)
MAX

Retrognathism

Prognathism

L1

N

www.indiandentalacademy.com
L2

Ho...
Action of Functional
Appliances

www.indiandentalacademy.com
Two Types of Functional Appliances:

) Activator, Postural hyperpropulsor, Frankel
appliance, Twin block, Bionator, Class ...
FIRST GROUP:
Position mandible
Forward

Increased activity of
LPM and RDP

Less fatigable fibres in LPM
•Oudet et al (1988...
CELLULAR LEVEL
1. Precursor
Skeletoblast –
pleuripotent,
fibroblast like.
2. Prechondroblast –
faster cell cycle,
matures ...
Chondroblasts lost

Increased
multiplication of
prechondroblasts

(hypertrophy, surgically removed)

Local
control
prechon...
www.indiandentalacademy.com
Functional appliances (especially Class II elastics)

Increased activity of RDP
Increased nutrients and growth factors sup...
Reduced negative feedback
signal reaching
prechondroblasts
Increased growth at the
condyle

www.indiandentalacademy.com
Cytoplasmic junctions between skeletoblasts reduce.

Transmission of inhibitory factors reduce.

Increased mitotic rate an...
SECOND GROUP:
Position mandible forward , open in beyond rest
position.
No increase in activity of LPM
•Herren (1953)
•Auf...
wo steps:

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

) While appliance is ...
Action of first group

while appliance is worn

Action of second

while appliance is not worn

group

www.indiandentalacad...
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
intercuspat...
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 i...
Drawbacks
Lot of importance on condyle:
Fracture?

Peripheral comparator (occlusion)
discrepancies may be overcome by Dent...
Occurrence of Class II end on relation is seen often?

Action of reverse pull headgear on maxilla
(primary cartilage)

www...
References
Dentofacial Orthopedics with Functional
Appliances
Graber, Rakosi, Petrovic

Craniofacial Growth Series – Mon...
Treatment objectives and case retention:
Cybernetic and myometric considerations
R.M. Jacobs Am J Orthod, 58:552-564, 197...
Thank you
For more details please visit
www.indiandentalacademy.com

www.indiandentalacademy.com
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Cybernetic theory of craniofacial /certified fixed orthodontic courses by Indian dental academy

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The 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.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Cybernetic theory of craniofacial /certified fixed orthodontic courses by Indian dental academy

  1. 1. Cybernetic Theory of Craniofacial Growth INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Introduction • Sutural Genetic locus • Cartilaginous • Functional matrix www.indiandentalacademy.com
  3. 3. 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. DICTIONARY 16TH ED TABER’S CYCLOPEDIC MEDICAL www.indiandentalacademy.com
  4. 4. Petrovic 1977 • Demonstrate qualitative and quantitative relationship between observed and experimental findings. • Broader understanding of orthodontic problems, and action of appliances • Familiarity of orthodontists with cybernetics www.indiandentalacademy.com
  5. 5. Cybernetics Transfer of Information • Cybernetic systems operate through transfer of information • Physical, Chemical, Electromagnetic www.indiandentalacademy.com
  6. 6. Input Input Process Cybernetic System Transfer Function www.indiandentalacademy.com Output Output
  7. 7. Physiological cybernetic systems Open loop Closed loop Regulator Servosystem Comparator Feedback www.indiandentalacademy.com Peripheral Central Positive Negative
  8. 8. Open Loop Output has no effect on the input www.indiandentalacademy.com
  9. 9. Closed Loop Relationship maintained between input and output Input Comparator Feedback Loop Transfer function Output www.indiandentalacademy.com
  10. 10. Regulation Type of Closed Loop Input is constant Any change of the input will initiate a “regulatory process” Input Comparator Regulation of input www.indiandentalacademy.com Transfer function
  11. 11. Servosystem Type of Closed Loop www.indiandentalacademy.com
  12. 12. Components of a Servosystem COMMAND Reference Input Elements Actuator, Coupling System, Controlled System COMPARATOR Output (Controlled Variable) Central Comparator (sensory engram) Reference Input Deviation Signal www.indiandentalacademy.com Performance Analyzing Elements Performance
  13. 13. Growth of the Face According to the Servosystem Theory www.indiandentalacademy.com
  14. 14. Types of Cartilage Primary www.indiandentalacademy.com
  15. 15. Types of Cartilage Secondary www.indiandentalacademy.com
  16. 16. Primary Cartilage: Epiphysis, Synchondrosis, Nasal Septum, Ethmoid Sphenoid Secondary Cartilage: Condyle, Coronoid, Mid Palatal Suture, Fracture Callus www.indiandentalacademy.com
  17. 17. Factors influencing Primary Growth Cartilage Secondary Cartilage Hormones Yes Yes Local Factors No (Chondroblasts Yes (Pre- Orthopaedic appliances Only Direction Direction and Amount surrounded by matrix) chondroblasts not surrounded by matrix) Charlier, Petrovic, Stutzmann www.indiandentalacademy.com Strasburg, France
  18. 18. Role of Lateral Pterygoid and Retrodiscal Pad •Blood Supply •Bio-mechanic www.indiandentalacademy.com
  19. 19. Relationship Between Lateral Pterygoid, Retrodiscal Pad and Condyle MENISCUS LPM RDP www.indiandentalacademy.com
  20. 20. Stutzmann and Petrovic Proper function of Lateral Pterygoid and retrodicsal pad: • Excision of Lateral Pterygoid • Reduced function of the Retrodiscal pad (Rat experiments) www.indiandentalacademy.com
  21. 21. The Face as a Servosystem Input – Maxillary dental arch Output – Adjustment of the position of mandibular dental arch www.indiandentalacademy.com
  22. 22. The Face as a Servosystem Release of Hormones (Command) LPM & RDP (Coupling system) Position of Maxillary Dental arch (Ref Input) Hormones Growth at condyle (Controlled System) OCCLUSION Output Periodontium, Teeth Musculature Joint Actuating signal Actuator (Motor Cortex) Brain (sensory engram) (Comparator) Deviation Signal www.indiandentalacademy.com Mastication (Performance)
  23. 23. Growth of the maxilla Growth in Length Growth in Width www.indiandentalacademy.com
  24. 24. www.indiandentalacademy.com
  25. 25. 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 Direct Action www.indiandentalacademy.com Growth of Maxillo Palatine suture
  26. 26. 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
  27. 27. Growth at the Posterior Border of the Ramus www.indiandentalacademy.com
  28. 28. Other Terms Related to a Servosystem Gain = Output Input Amplification (Gain>1) Attenuation (Gain <1) 1. Large amounts of TESTOSTERONE 2. Small or large amounts of 2. Small amounts of OESTROGEN TESTOSTERONE 3. Large amounts of 3. Very small amounts of CORTISONE OESTROGEN 1. STH – Somatomedin www.indiandentalacademy.com
  29. 29. Attractor Cusp to fossa relation Repeller Cusp to cusp relation Disturbances Abnormal tooth position Occlusal interferences Arthritis Muscle Inflammation Periodontitis, Pulpitis www.indiandentalacademy.com
  30. 30. www.indiandentalacademy.com
  31. 31. 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
  32. 32. Discontinuities Stable Unstable Catastrophe Theory www.indiandentalacademy.com Stable
  33. 33. Bifurcation www.indiandentalacademy.com
  34. 34. Height of Bifurcation OR www.indiandentalacademy.com
  35. 35. Importance of Discontinuities •Growth prediction , treatment planning , decision making •Stability of occlusion after it is established •Genotype does not directly influence the phenotype www.indiandentalacademy.com
  36. 36. 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
  37. 37. The Sensory Engram • Collection of feedback loops • Blueprint of ideal muscular function/position • CNS tends to operate along these feedback loops www.indiandentalacademy.com
  38. 38. Optimality of Function •Minimum deviation signal •CNS always tries to revert back to optimal position •Observation of Chain gang prisoners by Jacobs (1968) www.indiandentalacademy.com
  39. 39. Development of Skeletal Malocclusion According to the Servosystem Theory www.indiandentalacademy.com
  40. 40. For every unit of Growth hormone released, the amount of growth in the maxilla is less than in the mandible. www.indiandentalacademy.com
  41. 41. Increase in length LPM(max) LPM(norm) LPM(min) MAX Retrognathism Prognathism L1 N www.indiandentalacademy.com L2 Hormone levels
  42. 42. Action of Functional Appliances www.indiandentalacademy.com
  43. 43. Two Types of Functional Appliances: ) 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
  44. 44. FIRST GROUP: Position mandible Forward Increased activity of LPM and RDP Less fatigable fibres in LPM •Oudet et al (1988) •Carlson et al (1990) LPM “helped to contract more” by Functional appliances. www.indiandentalacademy.com
  45. 45. CELLULAR LEVEL 1. Precursor Skeletoblast – pleuripotent, fibroblast like. 2. Prechondroblast – faster cell cycle, matures into Chondroblast www.indiandentalacademy.com
  46. 46. Chondroblasts lost Increased multiplication of prechondroblasts (hypertrophy, surgically removed) Local control prechondroblasts over multiplication of Originates from chondroblastic layer •Stutzmann and Petrovic (1982, 1990) www.indiandentalacademy.com
  47. 47. www.indiandentalacademy.com
  48. 48. Functional appliances (especially Class II elastics) Increased activity of RDP Increased nutrients and growth factors supplied and inhibitors removed. Increased mitoses and earlier hypertrophy of chondroblasts. www.indiandentalacademy.com
  49. 49. Reduced negative feedback signal reaching prechondroblasts Increased growth at the condyle www.indiandentalacademy.com
  50. 50. Cytoplasmic junctions between skeletoblasts reduce. Transmission of inhibitory factors reduce. Increased mitotic rate and rate of differentiation into prechondroblasts. www.indiandentalacademy.com
  51. 51. SECOND GROUP: Position mandible forward , open in beyond rest position. No increase in activity of LPM •Herren (1953) •Auf der Maur (1978) Yet there was an increase in growth www.indiandentalacademy.com
  52. 52. wo steps: ) While appliance is worn:Forward position Reduction of 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
  53. 53. Action of first group while appliance is worn Action of second while appliance is not worn group www.indiandentalacademy.com
  54. 54. 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
  55. 55. 2) Removal of functional appliance – when growth is complete. 3) If removed when growth not complete – Proper intercuspation. www.indiandentalacademy.com
  56. 56. 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
  57. 57. 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
  58. 58. Drawbacks Lot of importance on condyle: Fracture? Peripheral comparator (occlusion) discrepancies may be overcome by Dentoalveolar changes. www.indiandentalacademy.com
  59. 59. Occurrence of Class II end on relation is seen often? Action of reverse pull headgear on maxilla (primary cartilage) www.indiandentalacademy.com
  60. 60. References Dentofacial Orthopedics with Functional Appliances Graber, Rakosi, Petrovic Craniofacial Growth Series – Monograph 23 (Craniofacial Growth Theory and Orthodontic Treatment – Edited by Carlson) www.indiandentalacademy.com
  61. 61. Treatment objectives and case retention: Cybernetic and myometric considerations R.M. Jacobs Am J Orthod, 58:552-564, 1970 Grant’s Atlas of Anatomy www.indiandentalacademy.com
  62. 62. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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