CYBERNETICSDr.Ameet.V ORIGIN Greek word KYBERNETES (steersman) Plato & Ampere Norbart Weiner 1948 “ Science of control & communication in animal & machine” 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. Cybernetics focuses on how systems use information, models, and control actions to steer towards and maintain their goals, while counteracting various disturbances. The cybernetic theory postulates that everything affects everything & therefore organized living systems never operate in an openloop manner There is a dynamic motor control of receptor sensitivity. receptor orientation. stimulus selection & sources of environmental stimuli . Black box concept Input Black Box Output Input Transfer function Output Black box is the physiologic system under study . & orthopedic appliances Black Box Genetically determined & cybernetically organized biologic features of Phenomena characterizing. Functional. lengthening & •Widening •Mandible lengthening •Teeth movements Output Correction of malocclusion & Intermax. malrelation . or controlling spontaneous & appliancemodulated growth relative To the following: •Max.Input Orthodontic. inducing. Pavlovian concept of accommodation in biological systems Conditioning Reinforcement Habituation Living animals respond passively to stimuli . Open Loop Output has no effect on the input . Refutations 1. Steiner & Brown “The North Carolina chain gang” . 2. Post retention Relapse . Principle of optimality Laws of Energetics Energy expenditure Gravitational work Kinetic energy Mechanical/Functional efficiency . France 1977 1982 . Strasbourg. Petrovic National Institute Of Health & Medical Research.Prof. Alexandre G. Morphophysiologic systems Open loop Closed loop Regulator Servosystem Comparator Feedback Peripheral Central Positive Negative . Closed Loop systems Input Regulation of effect Measure of effect Return of modified information . Closed Loop systems . Regulator Type of Closed Loop Input is constant Servosystem Type of Closed Loop Input varies across time . Controlled System Output (Controlled Variable) Central Comparator Deviation Signal Reference Input COMPARATOR (peripheral) Performance Analyzing Elements Performance . Coupling System.Components of a Servosystem COMMAND Reference Input Elements Actuator. Growth of the craniofacial region & the servosystem . Cartilage & its types Primary Secondary . Types of Cartilage Primary . Types of Cartilage Secondary . Nasal Septum. Ethmoid(lat masses). Sphenoid Secondary Cartilage: Condyle. Coronoid. Fracture Callus . Synchondrosis.Primary Cartilage: Axial skeleton Epiphysis. Sutures. Factors influencing Growth Hormones Primary Cartilage Secondary Cartilage Yes Yes Local Factors No Yes (Pre- Orthopaedic appliances Only Direction Direction and Amount (Chondroblasts surrounded by matrix) chondroblasts not surrounded by matrix) . Condylar cartilage Sarnat – Akin to Epiphyseal Stutzmann & Petrovic – secondary - Response to local factors Phylogenetic success Fine tuning of occlusion . Cell types in condylar cartilage 1. 2. matures into Chondroblast 3. fibroblast like. Precursor Skeletoblast – pleuripotent. Prechondroblast – faster cell cycle. Preosteoblast . Double differentiating potential of skeletoblasts . Relationship Between Lateral Pterygoid. Retrodiscal Pad and Condyle MENISCUS LPM RDP/ MTMF . Somatomedin & LPM Interaction . Evidence supporting the role of LPM Resection EMG in monkeys Microelectric stimulation of LPM Post hyperpropulsor Non fatigable fibers Serial sarcomeres Goret-Nicaise. Awn & Dhem Voudouris . Retrodiscal Pad / MTMF Jeanne J Stutzmann 1.Biomechanic role 2.Metabolic role . 1996 .Biomechanic role Posterior growth rotation Supplementary lengthening Paulsen. Metabolic role Increase Blood & Lymph flow Open loop nutritive factors Decrease Cell catabolites -ve feedback factors . The Face as a Servosystem Input – Maxillary dental arch Output – Adjustment of the position of mandibular dental arch . The Face as a Servosystem Release of Hormones (Command) LPM & RDP (Coupling system) Actuating signal Labionarinary muscles Septal cart.Premax-frenum OCCLUSION Growth at condyle ( P.Comparator) Output (Controlled Variable) Periodontium. Teeth Musculature Joint Actuator (Motor Cortex) Brain (sensory engram) Position of Maxillary Dental arch (Ref Input) Deviation Signal Mastication (Performance) . Growth of the maxilla Growth in Length Growth in Width . Growth in Length: Traction SeptoPremaxillary ligament Growth of Nasal Septum Labio narinary Muscles Release of STH Somatomedin Thrust Induction Growth of Pre Maxillary extremity Biomechanical Anterior shift Of premaxillary bones Growth of PremaxilloMaxillary suture Protrusion of Upper Incisors Increased size Of Tongue Thrust Protrusion of Lower Incisors Direct Action Growth of Maxillo Palatine suture . . Growth in Width: Growth of Lateral cartilaginous masses of Ethmoid Release of STH Somatomedin 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 Direct effect Transverse Separation of premaxillae Growth of inter Pre Maxillary suture Transverse Separation of Horizontal Maxilla and Palatine plates Growth of mid Palatine suture Outward Appositional Bone growth . Condylar cartilage growth Peripheral comparator Confrontation Output . Intrinsic regulation of condylar growth . Large amounts of TESTOSTERONE 2. Large amounts of 3. STH – Somatomedin . Small or large amounts of 2.Other Terms Related to a Servosystem Gain = Output Input Amplification (Gain>1) Attenuation (Gain <1) 1. Small amounts of OESTROGEN TESTOSTERONE 3. Very small amounts of CORTISONE OESTROGEN 1. Attractor Cusp to fossa relation Repeller Cusp to cusp relation Disturbances Abnormal tooth position Occlusal interferences Arthritis Muscle Inflammation Periodontitis. Pulpitis . 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 . Discontinuities Stable Unstable Catastrophe Theory Stable . Bifurcation . Importance of Discontinuities Growth prediction . treatment planning . decision making Genome partially determines the phenome Supports mixed dentition therapy . Mode of action of functional Appliances Functional appliance LPM Retrodiscal Pad Growth stimulating factors Lengthening of mandible . Class II Elastics(?) 2) Herren activator. Twin block. Extra oral traction on the mandible.Two Types of Functional Appliances: 1) Activator. LSU activator. Bionator. . Frankel appliance. Harvold-Woodside activator. Postural hyperpropulsor. .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. CELLULAR LEVEL 1. Precursor Skeletoblast – pleuripotent, fibroblast like. 2. Prechondroblast – faster cell cycle, matures into Chondroblast Chondroblasts lost Increased multiplication of prechondroblasts (surgically removed) Local control prechondroblasts over multiplication of Originates from chondroblastic layer •Stutzman &Petrovic (1982, 1990) 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. Reduced negative feedback signal reaching prechondroblasts Increased growth at the condyle . . Increased mitotic rate and rate of differentiation into prechondroblasts.Cytoplasmic junctions between skeletoblasts reduce. Transmission of inhibitory factors reduce. SECOND GROUP: Position mandible forward . No increase in activity of LPM •Herren (1953) •Auf der Maur (1978) Yet there was an increase in growth . open in beyond rest position. Two steps: 1) While appliance is worn:Forward position Reduction of length of LPM New sensory engram 2) While appliance is not worn:New sensory engram Functioning in anterior position Increased activity of RDP . Action of first group while appliance is worn Action of second while appliance is not worn group . CLINICAL IMPLICATIONS 1) Principle of optimality of function :Less relapse tendency if post orthodontic treatment muscular activity produces a lower deviation signal. . 2) Removal of functional appliance – when growth is complete. . 3) If removed when growth not complete – Proper intercuspation. First group – Full time Second group – Part time .4) Understanding of when. and for how long a particular functional appliance should be worn. . 6) Utilization of high hormonal activity at puberty.5) Proper functioning of LPM and RDP important for growth – Proper parent counseling. .Drawbacks 1) Lot of importance on condyle: Fracture? 2) Peripheral comparator (occlusion) discrepancies may be overcome by Dentoalveolar changes. 3) Occurrence of end on relation is seen often 4) Action of reverse pull headgear on maxilla . LPM.J Petrovic. TMF & postural hyperpropulsor in growth of mandible – J.J Stutzmann & A.381-92 .97.References Auxologic categorization & chronobiologic specification for the choice of appropriate orthodontic treatment – Alexander Petrovic AJODO 1994 Feb. Am J Orthod Dentofac Orthop May 1990. 1997. Petrovic.Treatment objectives & case retention:Cybernetic & “myometric” considerations – Richard M.:13-73 .Mosby-year Book Inc. 2nd edition. Rakosi. Jacobs.58:552-56 Dentofacial orthopedics with functional appliances – Graber. AJO 1970.
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