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contemporary views on functional appliances /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.

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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
00919248678078

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contemporary views on functional appliances /certified fixed orthodontic courses by Indian dental academy

  1. 1. CONTEMPORARY VIEWS ON FUNCTIONAL APPLIANCE www.indiandentalacademy.com 1
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 2
  3. 3. CONTENT     Introduction The Road to dicovery: masters of functional appliance Classification of functional appliances A view and ideas : based on clinical studies 1) How Do The Functional Appliances Work ? 2) Do Functional Appliances have an Orthopedic Effect 3) What Bite Registration Technique Should We Follow ? 4) Stepwise Advancement of Mandible V/S Maximal Jumping Of Bite ? 5) Is Early Treatment Beneficial ? 6) Are The Treatment Changes Stable ? 7) Do Functional Appliances Cause Temporo Mandibular Disorders ? 8) Epiphysis of long bone vs condyle?  REASONS FOR INDIVIDUAL VARRIATION IN RESULT  conclusion www.indiandentalacademy.com 3
  4. 4. INTRODUCTION www.indiandentalacademy.com 4
  5. 5. Functional appliance , the most interesting , fascinating part of mechano therapeutic armamenterium available to orthodontist.  Since the inception of the idea of functional jaw orthopedics, it has always been surrounded with numerous views regarding its mode of action, the outcomes of such treatment, the stability, the timing, the appliance and its effects on the skeletal pattern. www.indiandentalacademy.com 5
  6. 6. MASTERS OF FUNCTIONAL APPLIANCES AND THERE VIEWS www.indiandentalacademy.com 6
  7. 7. In 1880, Kingsley introduced the term and concept of “jumping the bite” for patients with mandibular retrusion. www.indiandentalacademy.com 7
  8. 8. He inserted a vulcanite palatal plate consisting of an anterior incline that guided the mandible to a forward position when the patient closed on it. www.indiandentalacademy.com 8
  9. 9. The valcanite plate was fastened to the maxillary arch with silk threads and its action was enhanced by a vestibular plate connected with silk binding to the palatal plate to move the anterior teeth backward. www.indiandentalacademy.com 9
  10. 10. The purpose was not only to push the mandibular incisor forward but also to modify the entire articulation www.indiandentalacademy.com 10
  11. 11. The real goal of functional orthopedics had not yet been fully understood , that is shifting the mandible to provoke the phenomenon of bone and cartilage remodeling that would change its structure and position. www.indiandentalacademy.com 11
  12. 12. Hotz modified the Kingsley plate and called it vorbissplatte. It was used in cases of deep bite retrognathism, when the overbite was likely to cause a functional retrusion and the lower incisors were retro inclined by the hyperactivity of the mentalis muscle and the lip musculature. www.indiandentalacademy.com 12
  13. 13. In 1902, Pierre Robin of France introduced the Monobloc as a passive positioning device. It was used in neonates with micromandibular development, particularly infants with cleft lips and palates, to prevent glossoptosis. This Monobloc was a single vulcanite bite jumping appliance which was used to position the mandible forward in patients. www.indiandentalacademy.com 13
  14. 14. In 1908 viggo andresen experimented with a removable retention device for his daughter, following active multiband therapy , and was surprised to achieve further clinical improvements that is correcting of distocclusion. He called this retainer as biomechanical retainer. www.indiandentalacademy.com 14
  15. 15. When Andresen moved from Denmark to Norway , he became associated with Haupl. Andresen and Haupl teamed up and renamed this appliance as Activator.. because its ability to activate muscle forces. www.indiandentalacademy.com 15
  16. 16. They believed that the repetition of the new mandibular closure pattern induced a musculoskeletal adaptation and resulted in the reeducation of the oro-facial musculature. www.indiandentalacademy.com 16
  17. 17. The appliance advanced the mandible and generated a biomechanical force as the muscles attempted to return the mandible to its normal position. www.indiandentalacademy.com 17
  18. 18. Since it was designed to be loose fitting and required the patient to actively hold the appliance in place, it was often described as an exercise appliance. Valuable contributions were made by numerous authors to modify the activator appliance like, Harvold, Woodside, Herren etc. www.indiandentalacademy.com 18
  19. 19. The bulkiness of the activator and its limitations to nighttime wear caused the development of many similar appliances. www.indiandentalacademy.com 19
  20. 20. The Activator was modified by Balters in 1960, and he called it the Bionator.  It is a less bulky appliance and its lower portion is narrow, and its upper has only lateral extensions, with a crosspalatal stabilizing bar. www.indiandentalacademy.com 20
  21. 21. The palate is free for proprioceptive contact with the tongue; the buccinator wire loops hold away potentially deforming muscle action. Balter’s Bionator www.indiandentalacademy.com 21
  22. 22. The principle of treatment with the Bionator is not to activate the muscles but to modulate muscle activity, www.indiandentalacademy.com 22
  23. 23. Thereby enhancing normal development of the inherent growth pattern and eliminating abnormal and potentially deforming environmental factors. www.indiandentalacademy.com 23
  24. 24. At the same time Bimler in 1946 was working towards developing an appliance that consisted of wire elements that were fixed to each other by acrylic, which is known as the Bimler’s Appliance. www.indiandentalacademy.com 24
  25. 25. The patient were supposed to wear it all day and night except during meal time. www.indiandentalacademy.com 25
  26. 26. Perhaps the most significant development in removable appliances is the Funktionsregler (Functional Regulator) of Rolf Frankel in 1967. The Functional regulator (FR) is designed to be an exercise device. www.indiandentalacademy.com 26
  27. 27. Its conceptual method of action is based on medical orthopedic principles – exercise and muscle training are important training factors in the normal development of osseous tissues. www.indiandentalacademy.com 27
  28. 28. Frankel believed that poor postural behaviour of the orofacial musculature is the primary etiologic factor in Class II malocclusions. Therefore, correction of a Class II is achieved by permanently advancing the position of the mandible through muscular exercise. www.indiandentalacademy.com 28
  29. 29. All the above functional appliances shared the disadvantage of being made in one piece due to which the patient could not eat, speak or perform other normal functions with the appliance in the mouth. This led to the development of the Twin Block Appliance by William J. Clark in 1977 as a two piece appliance . www.indiandentalacademy.com 29
  30. 30. The appliance was designed for full time wear and thus could correct the maxillomandibular relationship through functional mandibular displacement because of the presence of the inclined planes in the upper and the lower plate. www.indiandentalacademy.com 30
  31. 31. The patients found this appliance very simple, comfortable and aesthetically acceptable. The use of the appliance during eating harnesses the full occlusal forces for the facial and dental development and maximize the functional response to treatment. www.indiandentalacademy.com 31
  32. 32. Classification of Functional Appliances : www.indiandentalacademy.com 32
  33. 33. Classification No. 1 1 2    All functional appliances were grouped together, where they were considered to be sub-class of removable appliances. Classification No. 2 Removable – Frankel appliance, Activator, Bionator etc Semifixed – Holtz appliance ,Bass appliance etc. Fixed A) Flexible fixed functional appliance eg. Jasper Jumper, Forsus etc. B) Rigid fixed functional appliance eg. Herbst Appliance, Bio- pedic appliance, etc. www.indiandentalacademy.com 33
  34. 34. Classification No. 3 A) Tooth borne Active (Myodynamic) : Jasper Jumper Bimler’s appliance Headgear + activator Passive (myotonic) : Activator Bionator Catalan’s appliance Twin block appliance Kinetor B) Tissue borne : Vestibular screen Frankel Appliance www.indiandentalacademy.com 34
  35. 35. Classification No. 4 Group A – Tooth Supported eg- Catlan’s appliance Group B – Teeth / Tissue Supported eg - activator Group C – Vestibular position appliances eg: Oral Screens, Frankel Appliances. www.indiandentalacademy.com 35
  36. 36. Classification No. 5 According to Graber Neumann  Group I – Consists of inclined planes and oral screens which transmit muscle forces directly to teeth.  Group II – is made up of activator and its various modifications permitting daytime as well as night time wear. They all reposition the mandible downward and forward activating the attached and associated musculature.  Group III – also refers an mandibular positional changes but its major area of operation is vestibule. Supporting bone and teeth influenced by changing the muscle balance through cheek shield and lip pads. www.indiandentalacademy.com 36
  37. 37. A views and ideas : Based on different studies www.indiandentalacademy.com 37
  38. 38. From the time functional appliances achieved wide spread usage, it has been surrounded by numerous controversies. Many clinicians look at these appliances with suspicion and have never been assured about its efficiency while many others just love to put them into usage. In the following section some of the myths and uncertainties surrounding the functional appliances will be dealt with. www.indiandentalacademy.com 38
  39. 39. How Do The Functional Appliances Work ? Over the years several theories have emerged attempting to shed light on mechanism of action of functional appliances. www.indiandentalacademy.com 39
  40. 40. Genetic theory : It suggests the condyle is under strong genetic control that causes the entire mandible to grow downward and forward. Although this may be related more to development of prenatal than postnatal condylar growth, this theory does indirectly question the effectiveness of orthopedic appliances in condylar growth. www.indiandentalacademy.com 40
  41. 41. Myotactic reflex hypothesis  According to the original Andresen-Haupl (1955) concept, the forces generated in activator therapy are cause by muscle contraction and myotatic reflex activity. A loose appliance stimulates the muscles, and the moving appliance moves the teeth. The muscles function with kinetic energy, and intermittent forces are clinically significant. www.indiandentalacademy.com 41
  42. 42. Successful treatment depends on:  Muscle stimulation, The frequency of movements of the mandible, and  The duration of effective forces. Activators with a low vertical dimension construction bite function this way. www.indiandentalacademy.com 42
  43. 43. Viscoelastic tissue forces :  Grude (1952) gives one explanation for the continuing controversy suggesting that the activators mode of action, According to him, the appliance is squeezed between the jaws in the splinting action. The appliance exerts forces that move the teeth in this rigid position. www.indiandentalacademy.com 43
  44. 44. The stretch reflex is activated, inherent tissue elasticity is operative, and strain occurs without functional movement. The appliance works using potential energy. www.indiandentalacademy.com 44
  45. 45. For this mode of action an over compensation of construction bite in sagittal or vertical plane is necessary. An efficient stretch action is achieved by over compensation and the viscoelastic properties of the contiguous soft tissues. www.indiandentalacademy.com 45
  46. 46. Twin-block effect :  The occlusal inclined plane is the fundamental functional mechanism of the natural dentition. Cuspid inclined planes play an important part in determining the relationship of the teeth as they erupt into occlusion. www.indiandentalacademy.com 46
  47. 47. If the mandible occludes in a distal relationship to the maxilla, the occlusal forces acting on the mandibular teeth in normal function have a distal component of force that is unfavourable to normal forward mandibular development. www.indiandentalacademy.com 47
  48. 48. Twin block appliance was developed in 1977 as a two piece appliance .This appliance modifies the occlusal inclined plane and use the forces of occlusion to correct the malocclusion. The mandible is guided forward by the occlusal inclined plane. www.indiandentalacademy.com 48
  49. 49. Lateral Pterygoid Hypothesis :  The influence of muscle function on bone structure, formation, and function has been recognized.  The masticatory muscles, particularly the lateral pterygoid has aroused considerable orthodontic interest. www.indiandentalacademy.com 49
  50. 50. Petrovic et al (1975) raised the possibility that the lateral pterygoid activity increased the proliferation of condylar tissue.  Later Mcnamara (1978-80) also confirmed the hypothesis by implanting electrodes in the muscles of monkeys in his longitudinal study of the effects of permanently placed mandibular protrusion appliances on the electromyographic (EMG) activities of lateral pterygoid and other masticatory muscles. www.indiandentalacademy.com 50
  51. 51. He reported that a qualitative increase in postural activity of the superior and inferior heads of the lateral pterygoid muscle was associated with an increased proliferation of condylar tissue. www.indiandentalacademy.com 51
  52. 52.  Attachment of lateral pterygoid muscle to the condylar head or articular disk may expected to cause condylar growth but an atomic research has not found evidence that significant attachments actually exist. Tissue contiguous with the TMJ www.indiandentalacademy.com 52
  53. 53. The lateral pterygoid muscle tendon is observed attaching however to the anterior border of fibrous capsule. www.indiandentalacademy.com 53
  54. 54. More recently permanently induced implanted longitudinal muscle monitoring technique have found that the condylar growth is actually related to decreased postural and functional lateral pterygoid muscle activity. This notion was also supported by human studies by Autder Manr, Pancherz and Anehus, that reported decreased muscle activity. www.indiandentalacademy.com 54
  55. 55. The Frankel Philosophy Frankel has based his appliance on the following principles : Vestibular arena of operation :  According to Frankel, the dentition is influenced by perioral muscle function. Abnormal perioral muscle function creates a barrier for the optimal growth of the dento-alveolar complex. www.indiandentalacademy.com 55
  56. 56. Thus the Frankel appliance is designed to hold away the muscles (buccal and labial) from the dentition, so that the dentoalveolar structures are free to develop. In addition, the frankel appliance acts as an exercise device or an oral gymnastic device that aids in correction of the abnormal perioral muscle function. www.indiandentalacademy.com 56
  57. 57. Sagittal correction via tooth born maxillary anchorage :  The Frankel appliance is anchored firmly in the maxillary arch by means of grooves in the molar and canine regions. The mandible is positioned anteriorly by means of an acrylic pad that contacts the alveolar bone behind the lower anterior segment. This lower lingual pad acts more as a proprioceptive trigger for postural maintenance of the mandible. www.indiandentalacademy.com 57
  58. 58. Differential Eruption Guidance :  The Frankel appliance is free of the mandible teeth. This allows selective eruption of the lower posterior teeth, which aids in correction of the discrepancy in the vertical dimension and also helps in saggittal correction of class II malocclusion by allowing upward and forward movement of only the mandibular teeth. www.indiandentalacademy.com 58
  59. 59. Minimal maxillary basal effect :  It has been noted that in most class II malocclusions, the maxillary position is close to normal while the mandible is retruded. The frankel appliance has relatively little retrusive saggittal effect on the maxilla in contrast to the marked protrusive change in mandible. www.indiandentalacademy.com 59
  60. 60. Periosteal pull by buccal shields and lip pads  The buccal shields and lip pads are extended to bring about outward periosteal pull. This aids in bone formation at the apical base.  The buccal shields and lip pads hold the buccal and labial musculature away from the teeth and investing tissues, eliminating any possible restrictive influence from this functional matrix. www.indiandentalacademy.com 60
  61. 61. Growth Relativity Hypothesis Enlow and Hans (2000) presented an excellent overall perspective suggesting that mandibular growth is a composite of regional forces and functional agents of growth control that interact in response to specific extracondylar activating signals. They are the foundation of growth relativity hypothesis. www.indiandentalacademy.com 61
  62. 62. Activity during growth relativity refers to growth that is relative to the displaced condyles from actively relocating fossas. Viscoelasticity refers to all non calcified tissue. Specifically the viscoelasticity addresses the viscosity and flow of the synovial fluid, the elasticity of the retrodiskal tissues, TMJ tendons and ligament other soft tissues and body fluids. www.indiandentalacademy.com 62
  63. 63. Viscoelastic changes : During orthopedic mandibular advancement, there is an influx of nutrients and other biodynamic factors into the region through the engorged blood vessels of the stretched retrodiscal tissue that feed on the fibrocartilage of the condyle. www.indiandentalacademy.com 63
  64. 64.  Another promising area is the alteration of synovial fluid dynamics that occurs with orthopedics.  Nitzan used disoccluding appliances in human beings to demonstrate low subatmospheric intra-articular pressures within the TMJ in the open position.  The low intra-articular pressures were significant in altering the joint fluid dynamics or flow of synovial fluid. www.indiandentalacademy.com 64
  65. 65. The TMJ pump may act similar to a suction cup placed directly on the displaced condylar head to activate growth.  These negative pressures initially below capillary perfusion pressures permit the greater flow of blood into glenoid fossa region. www.indiandentalacademy.com 65
  66. 66.  Three Growth Stimuli (A/C to Voudoris et. al )  (Displacement + Viscoelasticity + Referred Force) The concept that viscoelastic tissue forces can affect growth of the condyle suggests that modification first occurs as a result of the action of anterior orthopedic displacement. Second the condyle is affected by the posterior viscoelastic tissues anchored between the glenoid fossa and the condyle, inserting directly into the condylar fibrocartilage. Finally, it is hypothesized that displacement and viscoelasticity further stimulate (or turn on the light switch for) normal condylar growth by the transduction of forces over the fibrocartilage cap of the condylar head. www.indiandentalacademy.com 66
  67. 67. www.indiandentalacademy.com 67
  68. 68. www.indiandentalacademy.com 68
  69. 69. www.indiandentalacademy.com 69
  70. 70. Decrease in intra-articular pressure www.indiandentalacademy.com 70
  71. 71. Thus ensuring increase in new endochondral bone formation that appears to radiate as multidirectional finger-like processes beneath the condylar fibrocartilage, and significant appositional (periosteal) bone formation is seen in the fossa. www.indiandentalacademy.com 71
  72. 72.  Light bulb analogy of the condylar growth and retention.  When the condylar growth is continuously advanced, it lights up like a light bulb.  When the condyle is released from the anterior displacement, the reactivated muscle activity dims the light bulb and returns it close to normal growth activity. www.indiandentalacademy.com 72
  73. 73. In the boxed area , the upper open coil shows the potential of the anterior digastic muscle and other peri-mandibular connective tissues to reactivate and return the condyle back into the fossa once the advancement is released. The lower coil in the box represents the shortened inferior LPM. www.indiandentalacademy.com 73
  74. 74. 2) Do Functional Appliances have an Orthopedic Effect ?  The influence of functional appliances on mandibular growth is a controversial issue. The primary question is whether treatment with a functional appliance can induce a clinically significant increase in mandibular growth. Much of the work demonstrating the ability of functional appliances to stimulate mandibular growth is based on animal experimentation. www.indiandentalacademy.com 74
  75. 75. Whether these findings on animal models are applicable to human beings during routine clinical treatment is debatable. Discrepancies between animal and human studies are expected since animal experimentation frequently involves the use of continuous forces. www.indiandentalacademy.com 75
  76. 76. These types of forces usually are impractical and often undesirable in most clinical situations; therefore treatment results can be expected to be less dramatic and more variable. www.indiandentalacademy.com 76
  77. 77. Mc Namara evaluated the results obtained in his laboratory and those of Petrovic and concluded that a maximum of 5% - 15% increase in mandibular length can be expected in experimental animals under controlled laboratory conditions and during periods of active growth. www.indiandentalacademy.com 77
  78. 78. Johnston, after renewing series of experimental studies, concluded that condylar growth can be altered by unloading or distracting the condyle www.indiandentalacademy.com 78
  79. 79. Stockli and Willert also reported an increase in the size of the condylar head with significant proliferative activity in the intermediate zone. www.indiandentalacademy.com 79
  80. 80. Rabie et aI investigated the temporal pattern of expression of VEGF (vascular endothelial growth factor) and new bone formation in the condyle during forward mandibular position. Sagittal sections were cut and stained with VEGF antibodies www.indiandentalacademy.com 80
  81. 81. Results showed there was significant increase in both vascularization and mandibular bone growth upon forward mandibular positioning and highest amount of both were expressed in posterior region of the condyle. www.indiandentalacademy.com 81
  82. 82. VEGF expression with mandibular Forward positioning VEGF expression with normal growth www.indiandentalacademy.com 82
  83. 83. The highest acceleration of vascularization preceded that of new bone formation. Thus forward mandibular positioning resulted in increased vascularization and enhanced condylar growth. www.indiandentalacademy.com 83
  84. 84. V.G.F. CHONDROCYTES Blood Vessels www.indiandentalacademy.com 84
  85. 85. The results of the animal studies seems encouraging but whether such results can be expected in humans is questionable. www.indiandentalacademy.com 85
  86. 86. 3) What Bite Registration Technique Should We Follow ?  The construction bite determines the sagittal and vertical displacements of the mandible and therefore the degree and direction of appliance activation. The determination of a proper construction bite is critical for a functional appliance to succeed. www.indiandentalacademy.com 86
  87. 87. Andersen and Haupl increased the vertical dimension between the molars by 3-4 mm. Thus the appliance was loosely fitting appliance that would induce “myotactic reflex” which would encourage the patient to bite into the appliance. www.indiandentalacademy.com 87
  88. 88. Harvold increased the vertical dimension 911mm . Harvold believed that a small increase was ineffective because the vertical dimension normally increase during sleeping which permitted the mandible to slip out of the appliance.  Therefore he increased the vertical dimension 5-6 mm beyond 4-5mm rest position. www.indiandentalacademy.com 88
  89. 89. He also increased the horizontal displacement of the mandible beyond the advancement to a Class I molar relationship to an end to end incisor relationship.  The overextended activator, stretching the soft tissues like a splint, induces no myotactic reflex activity but instead applies a rigid stretch and creates a buildup of potential energy. www.indiandentalacademy.com 89
  90. 90. Herren over extends in a saggital plane, moving the mandible anteriorly into an incisal cross bite relationship. The bite registration most commonly used in North America registers the mandible protruded to a point approximately 3mm distance to the most protrusive position,  where as vertically the bite is registered approximately 4mm beyond the rest position of the mandible. www.indiandentalacademy.com 90
  91. 91. According to Graber, if the forward positioning of the mandible is 7-8mm, the vertical opening should be 2-4 mm.  and if the forward positioning is 3-5mm the vertical opening should be 4-6 mm. www.indiandentalacademy.com 91
  92. 92. Variation in the construction bite Bjork 5mm increase Class I molar Wieslander and Lagerstrom 5mm increase Class I molar Harvold and Vargervik 5 to 6 mm increase beyond rest position End to end incisor Pancherz 5 to 7 mm increase beyond rest position Class I molar or greater Vargervik and Harvold 7 to 8 mm incease beyond rst position _________ Birkebaek, Melsen, and Terp Greater than 2mm beyond rest position End to end incisor Luder 3 to 5 mm increase beyond rest position 3-4mm 2 o 3 mm increase beyond rest position End to end incisor 92 Williams, and Melsen www.indiandentalacademy.com
  93. 93. 4) Stepwise Advancement of Mandible V/S Maximal Jumping Of Bite ? The term “jumping the bite” was introduced by Kingsley regarding his maxillary plate. It refers to the advancment of the mandible to a class I relationship during bite registration. www.indiandentalacademy.com 93
  94. 94. McNamara and Petrovic (1981) suggested that a progressive activation method to bring the mandible gradually forward : placing less stress on the investing soft tissue matrix, and  might reduce the undesirable dental effect while maintaining the skeletal effect. www.indiandentalacademy.com 94
  95. 95. Anehas and Pancherz advocated the multistep approach to be a more physiologically favourable effect in terms of muscular response. www.indiandentalacademy.com 95
  96. 96. Rabie et al investigated the number of replicating mesenchymal cells to correlate it to the amount of bone formation in the condyle during stepwise advancement of the mandible Vs single step advancement. www.indiandentalacademy.com 96
  97. 97. In single step advancement group, the posterior region of the condyle contained twice as many as replicating cells as those present in response to the initial advancement in the stepwise group. During stepwise group, the level of new bone formation in response to the initial advancement was half as much as the level of new bone formed in the one step advancement . www.indiandentalacademy.com 97
  98. 98. After single step advancement Initial advancement in stepwise Advancement group www.indiandentalacademy.com 98
  99. 99.  The maximum level of bone formation in the single step group was reached 30 days after advancement followed by decline to levels equal to those expressed during natural growth between days 40 to 60..  Such a pattern can be explained on the basis that , in the single step advancement , the differentiation of mesenchymal cells to chondroblasts or osteoblasts curtails the population size because , once differentiated , they loose their replication ability. Therefore they go back to the levels of bone formation expressed during natural natural gaowth. www.indiandentalacademy.com 99
  100. 100. In contrast , the second advancement in the step wise manner recruits more mesenchymal cells leading to more blood vascules, thus lead to more bone formation, compare to single advancement and normal growth. www.indiandentalacademy.com 100
  101. 101. The inference is that the more mesenchymal cells in a given site, the more is the bone forming capacity at that site. Such a correlation was the foundation of auto-transplantation of mesenchymal cells for the repair of bone defects when other clinical strategies failed. The number of mesenchymal cells significantly increase when the mandible is positioned forward.. www.indiandentalacademy.com 101
  102. 102. Mandibular advancement produces stretching of the posterior fibers and the net effect of this mechanical strain brings about an increase in the number of replicating mesenchymal cells to the site. Therefore, growth of the mandible could be influenced to a greater extent by advancing the mandible forward in a stepwise manner to recruit a greater number of replicating cells to the site www.indiandentalacademy.com 102
  103. 103. Thus stepwise advancement of the mandible seems to be a better option when compared to the maximal bite jumping. The former is also a more comfortable and physiologically acceptable mode of treatment for the patient. www.indiandentalacademy.com 103
  104. 104. A B C Cellular changes in posterior region of condyle. (A) control group , B) 1 step advancement C) stepwise advancement on day 7 www.indiandentalacademy.com 104
  105. 105. 5) Is Early Treatment Beneficial ?  It has always been very confusing for the orthodontist to decide when exactly to begin treatment of growing patients. Whether to initiate treatment immediately or to allow the patient to complete his / her growth and then proceed with the treatment has become a nerve-wrecking issue. www.indiandentalacademy.com 105
  106. 106. It is believed that an early phase of treatment will present the need for treatment at a later stage and or reduce the severity of the malocclusion, which can be corrected with a phase II treatment thus reducing treatment time and yield better results. www.indiandentalacademy.com 106
  107. 107. One view is that: A major problem in assessing the efficacy of early treatment is that it take place during a growth period. Since we work without a control it is difficult to determine whether correction is the result of treatment or of normal growth that would happened anyway. www.indiandentalacademy.com 107
  108. 108. Pancherz assessed the long term effects of functional appliance in patients who were treated early and late (after peak velocity of growth)and showed that the post treatment relapse in overjet was 36% in early cases and 8% in late cases ; and sagital molar relationship relapse was 29% of early cases but none in late cases. www.indiandentalacademy.com 108
  109. 109. Thus concluded that the main cause of relapse seems to be unstable post treatment occlusal and persisting lip tongue dysfunction habit and the best treatment time would be in the a period after the peak height velocity of pubertal growth. www.indiandentalacademy.com 109
  110. 110. Ghafari et al proposes that treatment in late childhood may be more practical and cost-effective, because it reduces the total length of time a child has to be seen by an orthodontist. www.indiandentalacademy.com 110
  111. 111. Tullcoh et al who evaluated the benefit of early class II treatment by using a randomized controlled trial and concluded that for children with moderate to severe class II problems, early treatment followed by later comprehensive treatment on an average does not produce major differences in jaw relationship or dental occlusion compared with one later stage treatment. www.indiandentalacademy.com 111
  112. 112. But O’Brien et al in a multi center randomized controlled trial using TwinBlock appliance concluded that early treatment with the Twin Block is effective in reducing overjet and severity of malocclusion. The skeletal change was small and not clinically significant www.indiandentalacademy.com 112
  113. 113. Despite the rising popularity of a functional phase of treatment, the literature contains little support for the notion that it produces “extra” mandibular growth . www.indiandentalacademy.com 113
  114. 114. 6) For How Long Do We Treat ? For how long should the treatment be carried out is a prime consideration during functional appliance treatment. Chen et al while reviewing the various articles to analyse the efficacy of functional appliances noticed that the treatment duration differed widely among the studies, ranging from 6-24 months. www.indiandentalacademy.com 114
  115. 115. Studies have suggested that maximum condylar prechondroblastic and chondroblastic response to be 6 weeks after initial activation, which is used as a guide for planning the treatment. www.indiandentalacademy.com 115
  116. 116. Chayana et al monitored the amount of bone formed after early and later removal of bite jumping devices and compared it with that of normal growth. Appliances were fitted to position the mandible forward in the experimental groups. www.indiandentalacademy.com 116
  117. 117. On day 30, the device was removed in 2 groups (early removal) and the day 44 and 60. The full time wear and control animals were sacrificed at different points in time. The results showed that in the condyle, early removal of the appliance resulted in less bone formation when compared with that of natural growth. Late removal of the appliance resulted in bone formation similar to that of natural growth. www.indiandentalacademy.com 117
  118. 118. In conclusion, early appliance removal results in subnormal growth of the posterior condyle but not of the glenoid fossa. Increasing the length of mandibular advancement secures normal levels of mandibular growth in post treatment periods. www.indiandentalacademy.com 118
  119. 119. 7) Are The Treatment Changes Stable ? One of the most frustrating aspect of functional appliance therapy has been the ability to predict the stability of the changes after the removal of the appliance.  www.indiandentalacademy.com 119
  120. 120. Angelopaoulos (1991) showed that the glenoid fossa changes that occurred during mandibular advancement were stable. Thus glenoid fossa relocation has been shown to be a powerful tool in the correction of class II dysplasia. www.indiandentalacademy.com 120
  121. 121. Voudouris observed that the active return of the condyles to the fossa post treatment appears to deactivate the modifications by compressing the condyle against the proliferated retrodiskal tissues. Any additional bone induction appears to be clinically insignificant at the condyle in the long term. www.indiandentalacademy.com 121
  122. 122.  Orthopedic advancement has been associated with reduced muscle activity, while stimulating condylar proliferation. However, after long-term retention when the appliances have been removed, the majority of the condylar growth stimulation has been shown to be minimal in human beings. www.indiandentalacademy.com 122
  123. 123.  Pancherz and Fischer studied stability, the amount and direction of condylar growth, glenoid fossa displacement and “effective” TMJ changes by analyzing 35 class II, division I malocclusion treated with functional appliance.  The results revealed that during the treatment period condylar growth was directed posteriorly about twice the amount as in the control subjects, and the fossa was displaced in an anterior inferior direction.  The effective TMJ changes showed a pattern similar to condylar growth but were more pronounced. www.indiandentalacademy.com 123
  124. 124. During the first post treatment period, all TMJ changes revealed, the glenoid fossa was displaced backward; the amount of condlyar growth and effective TMJ changes was reduced, and the changes were more superiorly directed. During the second post treatment period all TMJ changes were considered physiological. Hence they concluded that during treatment the amount and duration of TMJ changes (condylar growth, fossa displacement and effective TMJ changes), were only temporarily affected favourably by treatment. www.indiandentalacademy.com 124
  125. 125. 8) Do Functional Appliances Cause Temporo Mandibular Disorders ? www.indiandentalacademy.com 125
  126. 126.  It has often been argued whether the Bite – Jumping produced by the various functional appliances causes any kind of damage to the TMJ. www.indiandentalacademy.com 126
  127. 127. Larsona and Ronnerman patients who were treated with the Functional appliance They concluded that extensive orthodontic treatment can be performed without fear of creating complications of TMD. They also suggested that orthodontic treatment may prevent TMD. www.indiandentalacademy.com 127
  128. 128. Pancherz evaluated the effects of the functional appliance in the treatment class II division I malocclusions and reported that the number of subjects with tenderness to palpation doubled during the initial 3 months of treatment. However, after appliance removal, most muscle symptoms disappeared in 12 months. www.indiandentalacademy.com 128
  129. 129. 9. Epiphysis of long bone vs condyle Epiphysis of long bone is a primary cartilage. Where as condyle is a secondary cartilage. Lets look the histological picture of these cartilage: www.indiandentalacademy.com 129
  130. 130. SCAN www.indiandentalacademy.com 130
  131. 131. Stutzmann emphasis that primary cartilage exists in the skull base , and the limbs The dividing cells , differentiated condroblasts ,are surrounded by a cartilagenous matrix that isolates them from local factor able to restrain or stimulate cartilagenous growth. www.indiandentalacademy.com 131
  132. 132. Where as in secondary cartilage exists in condylar and coronoid process and some times in sutures The dividing cells , prechondroblasts , are not surrounded by a cartilagenous matrix and thus are not isolated from local factor influence. www.indiandentalacademy.com 132
  133. 133. REASONS FOR INDIVIDUAL VARRIATION IN RESULT www.indiandentalacademy.com 133
  134. 134. Patient compliance varies Time of wear: some clinician advocate night time wear of these appliances , where as others recommend full time wear. If a long term effect is to applied to the growing facial infrastructure, it might be beneficial to work with appliances that can be worn full- time. www.indiandentalacademy.com 134
  135. 135. Mandible grows in a wave like fashion, with multiple acceleration in mandibular growth followed by quiescent periods. If orthodontic treatment is applied during quiescent period , significant orthopedic changes may not occur. www.indiandentalacademy.com 135
  136. 136. Improper diagnosis : we simply cannot expect growth control to exceed certain limits. The true nature of many malocclusion is comouflage by downward and backward mandibular rotation or by upward and forward mandibular rotation into an over closed position. www.indiandentalacademy.com 136
  137. 137. Thus a truly prognathic class III mandible may be rotated downward and back into a modrate class II relationship with excessive lower face height . The clinician in error , applies a class II functional appliance to what is in fact a camouflaged class III malocclusion , result may not be correct . www.indiandentalacademy.com 137
  138. 138. Age variation in the experimental group. It is difficult to find untreated class II div I control sample , so experimental results are often compared with those of untreared normal subject. www.indiandentalacademy.com 138
  139. 139. Variation in appliance design : such as the amount of mandibular advancement , types of construction bites , and prescribed time of wear –are so common that practically no to investigators use similar appliance design. Duration of treatment varies from study to study. www.indiandentalacademy.com 139
  140. 140. Cephalometric studies: Some ceph studies involve angular measurement such as SNA , SNB , ANB, to show skeletal changes. However these angles may increase or decrease when the incisor position changes , although no skeletal changes occurs , rendering the result invalid. www.indiandentalacademy.com 140
  141. 141. Some ceph landmarks used for the measurement of mandibular length are difficult to locate . eg: condylion. www.indiandentalacademy.com 141
  142. 142. Mandibular length measurement: some studies take mand length from Ar to Gn. They cannot distinguish between true mandibular length increase and functional condylar displacement. As in functioal treatment condyle is positioned anteriorly in glenoid fossa. www.indiandentalacademy.com 142
  143. 143. The assessment for increased condylar length is sometimes made from superimposition of lateral ceph on anatomical structures. This procedure is subject to considerable error because the radiographic images are often obscured by other cranial structures. Mandibular is a angular bone, measuring its length in linear direction is itself faulty. www.indiandentalacademy.com 143
  144. 144. Histologic studies :these studies itself having technical and analytical problems. Problem exist in quantifying new bone formation The plane of section must be identical to make accurate comparisons of the new bone formation. www.indiandentalacademy.com 144
  145. 145. Despite all these problems there is still convincing evidence supporting the concept that the functional appliances do create an orthopedic effect. Efficiency of functional appliances no longer needs to be “proved” unless one is ignoring thousands of case reports. www.indiandentalacademy.com 145
  146. 146. The missing link in all these studies appears to be lack of consideration of GLENOID FOSSA RELOCATION. well controlled animal studies show large amount of downward and forward glenoid fossa relocation in appliance worn 24 hours a day. EVIDENCE FROM HUMAN STUDY YET TO COME. www.indiandentalacademy.com 146
  147. 147. CONCLUSION www.indiandentalacademy.com 147
  148. 148. we realize that the principles of functional appliance – which had their initial epicenter in europe –later spread throughout the world. The seeds of functional thinking so generously and enthusiastically scattered for about 100 years , took root more or less broadly depending on the fertility on the ground they fell on. www.indiandentalacademy.com 148
  149. 149. Today we are able to evaluate the results of these teachings and gather their fruits. In facts , we can see that interest in functional therapy is increasing and that it has admires throughout the scientific world. Still in this field there is lot much to know and explore. www.indiandentalacademy.com 149
  150. 150. “ The orthodontics must not be a slave to one method” by, Rudolf hotz www.indiandentalacademy.com 150
  151. 151.  Graber, Rakosi, Petrovic. Dentofacial orthopedics with functional appliances.  The masters of functional orthodontics by Aurelio and Lorenzo.  Do functional appliances have an orthodontic effect ? AJO JAN 1998 VOL 113 NO. 11  Graber vanasdrall : THIRD EDITION.  William Proffit. Contemporary orthodontics. Mosby. 3rd Edition www.indiandentalacademy.com 151
  152. 152. References  John C Voudouris and Miaden M. Kuftinec. Improved clinical use of Twin Block and Herbst as a result of radiating viscoelastic forces on the condyle and fossa in treatment and long term retention : Growth Relatively. Am J Orthod 2000 ; 117 : 247-266.  A.B.M Rabie, Lily Shum, Atinooch Chayanupatkul. VEGF and bone formation in the glenoid fossa during forward mandibular positions. Am J of Orthod and Dentofacial Orthop 2002; 122 : 202-209.  A.B.M Rabie, Ming Ju Marjorie Tsai, Urban Hagg, Xi Diu, Bing-Wu Chou. The correlation of replicating cells and osteogenesis in the condyle during stepwise advancement. Angle Orthodontist 2003 ; 73 : 457-465  Rabie A.B.M & Hagg U. Factors regulating mandibular condylar growth. Am J Orthod Dentofacial Orthop 2002;122:401-9.  McNamara and Brudon. Orthodontics and Dentofacial Orthopedics. Needham Press, Inc. 1st edition . www.indiandentalacademy.com 152
  153. 153. THANK YOU www.indiandentalacademy.com 153
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  155. 155. Referencs : www.indiandentalacademy.com 155
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  161. 161. Decrease in intra-articular pressure www.indiandentalacademy.com 161
  162. 162. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com 162

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