Servo system in orthodontics
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The document discusses various theories of craniofacial growth, with a focus on the servosystem theory, which integrates genetic, hormonal, and functional factors to explain coordinated growth. The theory emphasizes the importance of cybernetics in understanding the complex interactions and feedback mechanisms that regulate craniofacial development. Applications of this theory in clinical orthodontics highlight its relevance in treating malocclusions and optimizing the use of functional appliances.
![T1= Expected ML/NSL - Measured ML/NSL.
T2= Expected NL/NSL - Measured NL/NSL
T3= ANB
Expectd ML/NSl = 192-2*SNB and Expectd Nl/NSL = [(Measured ML/NSL)/2]-7
www.indiandentalacademy.com](https://image.slidesharecdn.com/servo-160512120101/85/Servo-system-in-orthodontics-50-320.jpg)
Servo system in orthodontics
- 2. INTRODUCTION Over many years various theories of growth have been proposed for the craniofacial complex. The Genetic theory, Scott’s Hypothesis, Sicher’s Sutural Dominance theory, Functional matrix theory attempt to explain the growth of the cranofacial complex with different growth determinants and have their own limitations. The Servosystem theory of growth is based on a factorial qualitative analysis which takes into account various factors which determine a coordinated growth of the craniofacial complex as a whole. The Servosystem theory attempts to explain craniofacial growth and the modus operandi of Functional appliances. www.indiandentalacademy.com
- 3. GROWTH THEORY’S GENETIC CONTROL THEORY: • Genotype supplies all the information required for phenotype expression. • Does not address the question of local and general factors modifying gene expression. www.indiandentalacademy.com
- 4. GROWTH THEORY’S SICHER’S SUTURAL DOMINANCE THEORY: • He believed that craniofacial growth occurs at sutures. • Paired parallel sutures which attach the facial bones to the cranial base and skull push the nasomaxillary complex forwards to compare with mandibular growth. • Acknowledges the genetic influence on growth at the sutures. • Transplantation of sutures to another site showed that there was no innate growth potential. • Cases of Microcephaly and Hydrocephaly. www.indiandentalacademy.com
- 5. GROWTH THEORY’S CARTILAGE DIRECTED GROWTH THEORY: • James Scott- 1953, 1954, 1967 • Cartilage has intrinsic growth potential. • Role of Periosteum and sutures only secondary. • All cartilages through out the skull are primary centres of growth. • Growth of the maxilla is attributed to the growth of the Nasal septal cartilage. •Nasal septal carrtilage is the pacemaker of growth for the nasomaxillary complex. •The mandible is like the diaphysis of a long bone bent with epiphyseal cartilages at both ends. www.indiandentalacademy.com
- 6. GROWTH THEORY’S CARTILAGE DIRECTED GROWTH THEORY: • Epiphyseal cartilages cartilages transplanted to a different area will continue to grow - innate growth potential. • Nasal septal cartilages also grow when transplanted to another site. •Removal of nasal septal cartilages gives rise to retarded midface development. • Petrovic’s studies have shown that only primary cartilages grow in organ culture and not secondary cartilages. www.indiandentalacademy.com
- 7. GROWTH THEORY’S FUNCTIONAL MATRIX THEORY: • Melvin Moss 1960, 1962, 1997. • A Hypothesis substantiated in the revisited theory’s. www.indiandentalacademy.com
- 8. SERVOSYSTEM THEORY Alexandre Petrovic, Charlier,and Jeanne Stutzmann of Louis Pasteur School of Medicine. SERVOSYSTEM THEORY Study’s in Otosclerosis by Petrovic revealed that cartilage surrounding the cochlea never grew in organ culture but epiphyseal cartilages grew well. Petrovic and Charlier in 1967-69- Jaw Growth rate and direction can be modified by functional appliance. Jeanne Stutzmann-1976 The role of LPM and retrodiscal pad -mediator role Petrovic and coworkers:Chronobiological aspects of cartilage and bone growth www.indiandentalacademy.com
- 9. SERVOSYSTEM THEORY OVERVIEW MANDIBULAR GROWTH HORMONAL STATUS MAXILLARY GROWTH AND SAGGITAL POSITION LATERAL PTERYGOID AND RETRODISCAL PAD FUNCTIONAL APPLIANCES STABLE OCCLUSION MALOCCLUSION www.indiandentalacademy.com
- 10. SERVOSYSTEM THEORY AND CYBERNETICS Craniofacial growth is a multifaceted process where the connections and interrelationships are complex with interactions and feedbacks. The Servosystem theory uses the Cybernetic language of information and communication as a tool to explain the influence of various factors - extrinsic and intrinsic on Craniofacial growth. www.indiandentalacademy.com
- 11. SERVOSYSTEM THEORY AND CYBERNETICS CYBERNETICS: • “the language used to describe control and communication in man and machine.” • Study’s the role of information and the technique of measuring and transmitting it. • “Cybernetics” derived from a greek word meaning ‘steersman’ by Dr.Rosenbleuth and Norbert Weiner and others in 1947. www.indiandentalacademy.com
- 12. SERVOSYSTEM THEORY AND CYBERNETICS CYBERNETICS: • Used to explain Systems and Circuit analysis. • Can also be used in Biological Biomedical sciences to explain negative and positive feedback loops, self regulation, gain and in the process explain physiological processes. www.indiandentalacademy.com
- 13. SERVOSYSTEM THEORY AND CYBERNETICS CYBERNETICS: • A Cybernetically organised system operates through signals transmitting information. • Signals can be physical, chemical or electromagnetic in nature and of low energy. • Advantages: not static, sophisticated. Tr - RH TSH THYROXINE T3,T4 www.indiandentalacademy.com
- 14. CLASSIFICATION OF CONTROL SYSTEMS PHYSIOLOGICAL SYSTEMS CLOSED LOOP CONTROL SYSTEM OPEN LOOP CONTROL SYSTEM REGULATOR SYSTEM SERVOSYSTEM www.indiandentalacademy.com
- 15. CONTROL SYSTEMS CLOSED LOOP SYSTEM: • A specific communication between output and input is present • A feed back loop with a comparator is present. • eg: feed back loops maintaining hormone levels, blood sugar etc • Two types: Regulator and Servosystem. Tr - RH TSH THYROXINE T3,T4 www.indiandentalacademy.com
- 16. CYBERNETIC ORGANISATION OF CRANIOFACIAL GROWTH INPUT(STIMULUS) ORTHOPEDIC AND FUNCTIONAL APPLIANCES BLACK BOX •GENETICALLY DETERMINED AND CYBERNETICALLY ORGANISED GROWTH •MAXILLA LENGTHENING AND WIDENING •MANDIBLE LENGTHING WIDENING •TEETH MOVEMENT OUTPUT CORRECTION OF MALOCCLUSION AND INTERMAXILLA Y RELATION www.indiandentalacademy.com
- 17. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM CONTROLLED SYSTEM: • Located between the controlled variable and the actuating signal. • Condylar cartilage. CONTROLLER ACTUATOR REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 18. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM COMMAND: • A signal established independent of the Servosystem. •It affects the behaviour of the control system without being affected by the consequences of the behaviour. • Growth hormone, Testosterone, Oestrogen. CONTROLLER ACTUATOR REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 19. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM REFERENCE INPUT: • A signal established as a standard of comparison. • Ideally should be totally independent of the feed back. • The sagittal position of the maxilla. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 20. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM REFERENCE INPUT ELEMENT: • They establish the relationship between the COMMAND(Growth hormone) and the REFERENCE INPUT(Saggital position of the maxilla). • Septal cartilage, Septopremaxillary frenum, Labionarinary muscle, Premaxilla and Maxilla. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 21. RELATIONSHIP BETWEEN THE COMMAND, REFERENCE INPUT AND THE REFERENCE INPUT ELEMENTS. THRUST EFFECT LIGAMENT TRACTION MUSCLE TRACTION www.indiandentalacademy.com
- 22. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM COMPARATOR: REFERENCE INPUT ELEMENT COMPARATO R COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT •Serves to establish the relationship between the REFERENCE INPUT and the CONTROLLEDVARIABLE. • The “operation of confrontation”- Occlusal contact between the upper and lower jaw. • Any deviation from optimal occlusal contact detected by the comparator leads to correction signals to reestablish optimum occlusal contact.www.indiandentalacademy.com
- 23. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM THE CONTROLLER: • Located between the deviation signal and the actuating signal. • Lateral pterygoid muscle and the Retrodiscal pad. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 24. ROLE OF THE LATERAL PTERYGOID MUSCLE AND RETRODISCAL PAD. • Blood supply •Increase in open loop factors • Reduction in negative feed back factors • Biomechanical www.indiandentalacademy.com
- 25. ROLE OF THE LATERAL PTERYGOID MUSCLE AND RETRODISCAL PAD. Petrovic’s Experiments: 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 www.indiandentalacademy.com
- 26. ROLE OF THE LATERAL PTERYGOID MUSCLE AND RETRODISCAL PAD. Recent studies…. GROWTH RELATIVITY www.indiandentalacademy.com
- 27. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM ACTUATING SIGNAL: • Output signal from the controller-actuator complex. • Activity of the LPM and Retrodiscal pad. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 28. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM CONTROLLED VARIABLE: • Final output. • Sagittal position of the mandible. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 29. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM GAIN: • OUTPUT DIVIDED BY INPUT. • > 1 - AMPLIFICATION . < 1 - ATTENUATION. • Pterygomandiibular coupling. • Genetically determined but can be amplified by GH and Testosterone. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 30. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM ATTRACTOR: • Structurally stable steady state. • What the Servosystem tries to achieve. •Full interdigitation type of Class I, II, III. www.indiandentalacademy.com
- 31. COMPONENTS OF THE CRANIOFACIAL SERVOSYSTEM REPELLER: • a state of unstable equilibrium. • Tries to change to a stable steady state- ATTRACTOR. •Cusp to cusp occlusal contact. REFERENCE INPUT ELEMENT COMPARATOR COMMAND PERFORMANCE ANALYSING ELEMENTS CONTROLLED SYSTEM CONTROLLER ACTUATOR PERFORMANCE AMPLIFIER REFERENCE INPUT OPUTPUT www.indiandentalacademy.com
- 32. CYBERNETIC ORGANISATION OF MAXILLARY GROWTH. www.indiandentalacademy.com
- 33. CYBERNETIC ORGANISATION OF MANDIBULAR GROWTH. www.indiandentalacademy.com
- 34. BIFURCATION TYPE OF SITUATIONS UNSTABLE OCCLUSION STABLE CLASS I STABLE CLASS II www.indiandentalacademy.com
- 35. CONSIDERATONS IN CRANIOFACIAL SERVOSYSTEMS • GROWTH ROTATIONS OF THE MANDIBLE. • ALVEOLAR BONE TURN OVER RATE www.indiandentalacademy.com
- 36. GROWTH ROTATIONS OF THE MANDIBLE. www.indiandentalacademy.com
- 37. ALVEOLAR BONE TURN OVER RATE TISSUE LEVEL GROWTH POTENTIAL: “ The rank of the alveolar bone turn over rate.” TISSUE LEVEL GROWTH RESPONSIVENESS: “ The magnitude of increase in alveolar bone turn over rate caaused by a 10 day wearing of Class II elastics.” www.indiandentalacademy.com
- 38. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS • modus operandi of functional appliances. • Role of hormones • Development of malocclusion • Application of recent research www.indiandentalacademy.com
- 39. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS FUNCTIONAL APPLIANCES INCREASED CONTRACTILE ACTIVITY OF LPM INCREASE IN GROWTH STIMULATING FACTORS ENHANCEMENT OF LOCAL MEDIATORS REDUCTION IN LOCAL REGULATORS ADDITIONAL GROWTH OF THE CONDYLAR CARTILAGE ADDITIONAL SUBPERIOSTEAL OSSIFICATION SUPPLEMENTARY LENGTHENING OF THE MANDIBLEwww.indiandentalacademy.com
- 40. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS FUNCTIONAL APPLIANCES • POSTURAL HYPERPROPULSOR • ANDERSEN HAUPL ACTIVATOR • CLASS II ELASTICS • FRANKEL’S APPLIANCE • TWIN BLOCK • HERREN OR L.S.U ACTIVATOR • HARVOLD WOODSIDE ACTIVATOR www.indiandentalacademy.com
- 41. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS POSTURAL HYPERPROPULSOR: • Simulates a more anterior position of the upper dental arch. • A deviation signal is produced which increases LPM and retrodiscal pad activity. TWIN BLOCK: • Alters the occlusal inclined planes. • 70 degree inclined planes alter the sensory engram and provide a horizontal component of force. www.indiandentalacademy.com
- 42. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS CLASS II ELASTICS: • Act primarily through the retrodiscal pad rather than the LPM. • Alters the intrinsic regulation of prechondroblast multiplication . • Enhance the rate of hypertrophy of Functional chondroblasts so that the decreased amount of Functional chondroblasts enhance prechondroblast replication. • Similar to the effect of Thyroxine. www.indiandentalacademy.com
- 43. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS L.S.U or HERREN ACTIVATOR: • Acts when the appliance is not worn. •Action not mediated to through the LPM but through the Retrodiscal pad. • Shortening of the LPM when the appliance is worn when compared to other muscles. • A new sensory engram is produced. • The mandible closes in a more anterior position. •Stimulation of the retrodiscal pad and alteration of intrinsic regulation of the cartilage similar to the Class II elastics. www.indiandentalacademy.com
- 44. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS EFFECT OF CHIN CUP THERAAPY: • Retropulsion of the mandible results in reduction in the number of dividing cells. • Dividing cells if any are found anteriorly. • Resulting in anterior growth rotation and decreased mandibular length. www.indiandentalacademy.com
- 45. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS ROLE OF HORMONES: • www.indiandentalacademy.com
- 46. APPLICATION OF THE SERVOSYSTEM THEORY IN CLINICAL ORTHODONTICS DEVELOPMENT OF MALOCCLUSION - MALFUNCTION OF THE SERVOSYSTEM. MALFUNCTION AT THE LEVEL OF THE PERIPHERAL COMPARATOR MORPHOLOGIC ALLY DEFECTIVE INADEQUATE REFERENCE INHERENT LLIMITATION OF GROWTH MECHANISMS ANTERIOR ROTATION CLAS III SKELETAL POSTERIOR ROTATION CLASS II SKELETAL www.indiandentalacademy.com
- 47. APPLICATION OF RECENT RESEARCH Lavergne and Petrovic grouped children who are morphogenetically and morphophysiologically alike. Members within each group have similar tissue level growth potential and will respond in a similar manner to functional appliances. I 1 BASAL SAGITTAL GROWTH POTENTIAL OF MANDIBLE ALMOST SAME AS THAT OF THE MAXILLA - 70% 2 BASAL SAGITTAL GROWTH OF THE MANDIBLE IS INFERIOR TO THAT OF MAXILLA - 25% 3 BASAL SAGITTAL GROWTH OF THE MANDIBLE IS SUPERIOR TO THAT OF THE MAXILLA- 3% II A ANTERIORLY ROTATING R NEUTRAL P POSTERIORLY ROTATING www.indiandentalacademy.com
- 48. III N NORMAL AP RELATIONSHIP OPEN BITE OB M MANDIBLE MESIAL NORMAL N D MANDIBLE DISTAL DEEP BITE DB www.indiandentalacademy.com
- 50. T1= Expected ML/NSL - Measured ML/NSL. T2= Expected NL/NSL - Measured NL/NSL T3= ANB Expectd ML/NSl = 192-2*SNB and Expectd Nl/NSL = [(Measured ML/NSL)/2]-7 www.indiandentalacademy.com
- 52. CONCLUSION The Servosystem theory with the pharaseology of Cybernetics gives us an insight into the complex process of Craniofacial growth. Though the experiments conducted by Petrovic and coworkers were conducted on rats the biochemical and cellular response is the same. At the moment the Servosystem theory is the only theory which can explain the role of intrinsic and extrinsic factors in growth. www.indiandentalacademy.com