Activator seminar presentation (activator )

Activator

1. Activator and its modifications 1

2. Introduction In the past 20 years there has been increasing awareness of growth modifications produced by functional appliances among orthodontists. Major reasons for their popularity includes Increasing recognition of FORM & FUNCTION Realization that NEUROMUSCULAR INVOLVEMENT is vital in treatment. Recognizing the IMPORTANCE OF AIRWAY in therapeutic considerations Growing understanding of HEAD POSTURE AND ITS ROLE 2

3. HISTORY Fox (1803) advocated application of extra oral force to control the growth of maxilla . KINGSLEY introduced "Jumping of the bite": in 1879 to correct sagittal relationship between Upper and lower jaws. HOTZ modified the kingsley's plate into a vorbissplate (used it for deep bite and retrognathism ). From Kingsley 's concept, VIGGO AndrEsen 1908 developed a loose fitting appliance on his daughter as a retainer during summer vacations which gave remarkable results. He called it biomechanical retainer . 3

4. s ome yrs before this, PIERRE ROBIN created monobloc to position the mandible forward to prevent occluding the airway in patients of GLOSSOPTOSIS . Andresen moved to Oslo University, Norway where he met KARL HAUPL (a periodontist and histologist) who became convinced that appliance induced growth changes in a physiological manner. Then the name activator or Norwegian system was coined 4

5. CLASSIFICATION OF FUNCTIONAL APPLIANCE Tooth Borne - Passive (MYOTONIC) eg . Andreson's Activator (Depends on Muscle Mass for their Action) Balter's Bionator Tooth Borne - Active (MYODYNAMIC) eg . Elastic Open Activator (Depends of Muscle activity for their function) Klammpt's activator Tissue Borne – Passive eg . Oral Screen, Lip Bumper Tissue Borne – Active eg . Frankel 5

6. Indications of Activator Actively growing individual with favorable (horizontal) growth pattern. Well aligned maxillary and mandibular teeth Mandibular incisors should be upright over the basal bone. 6

7. Used In Class II Div 1 Class II Div 2 after aligning the incisors Class III Class I open bite Class I deep bite For cross bite correction (Trimming done in such a way that maxillary molars are moved laterally and mandibular molars lingually ). Preliminary before Fixed appliance to improve skeletal jaw relationship. For post- treatment retention 7

8. Contra Indications Class I crowding, due to tooth size jaw discrepancy Increased lower facial height. Extreme vertical mandibular growth Severely procumbent lower incisors Nasal stenosis . Non growing individuals 8

9. Efficacy of Activator: According to Andresen & Haupl (1955) Activator is effective in exploiting the interrelationship between function and changes in INTERNAL BONE STRUCTURE. During GROWTH, there is also interrelationship between FUNCTION and EXTERNAL BONE FORM . The condylar adaptation to the anterior positioning of the mandible consists of growth in an upward and backward direction to maintain the integrity of TMJ. This adaptational process in induced by the loose fitting appliance. 9

10. Classification of views : Views of various authors are classified into 3 groups 1.Myotatic reflex activity and isometric contractions 2.Viscoelastic property of muscle and stretching of soft tissues 3.Transitional type 10

11. Myotatic reflex activity and isometric contractions This was the concept given initially by Andresen and Haupl in 1938. It was based on ‘shaking of bone ‘hypothesis of Roux 1883. Other authors substantiated this; namely Petrik-1957 McNamera-1973 Petrovic-1984 According to this concept myotatic reflex activity and isometric contractions induce musculoskeletal adaptation to new mandibular closing pattern. The receptors in the periodontal ligament and the lateral pterygoid muscle play an important role in the skeletal adaptation. These receptors send signals to the masticator nucleus.   11

12. sensory signals via the afferent fibers reach the trigeminal nucleus and send efferent signals to the muscle, which causes the contraction of muscle fibers. Hence there is no change in the length of the muscle (isometric). That is the myotatic reflex, which causes adaptation in musculoskeletal pattern. For this kind of mechanism to act the side should be within the free way space with minimal sagittal advancement 12

13. Viscoelastic property of muscle and stretching of soft tissues: The hypothesis that the activator works according to the myotatic reflex activity had resistance from the beginning. Grude in 1952 said that there was a mismatch between bite suggested by Andersen and the mechanism of action. According to this theory whenever any muscle is stretched beyond its limit isometric contraction does not take place but the muscle stretches, Further no myotatic reflex activity was seen in the perioral musculature. 13

14. The proponents of this theory suggested that whenever the bite is opened beyond freeway space it is the clasp knife reflex that comes into action. the negative sensory are carried by the fibers to the ganglion, which inhibits the muscular contraction leading to stretching of the muscle. 14

15. the activator acts by viscoelastic property of muscle and stretching of soft tissues. That is the basis of activator action is potential energy. Depending on the amount of stretch the following effects where seen Emptying of vessels Pressing out of interstitial fluid Stretching of fibers Elastic deformation of bone Bioplastic adaptation of bone Woodside (1973) and Harvold (1974) suggested 10-15 mm of vertical opening 15

16. Transitional type of action This is a mechanism of action between the two extremes. Here the bite is opened beyond the freeway space but not an extreme opening as suggested by Woodside, Herren and Harvold . Eschler (1952) Suggested that when bite is opened beyond freeway space muscle stretching occurs, but there are cycle of isotonic and isometric contractions. Ahlgren’s electromyographic research in 1970 also supported this theory. 16

17. Force analysis in activator therapy Functional Appliances creates following types of forces by activating the muscles STATIC DYNAMIC RYTHMIC 17

18. 1) Static : These are permanent forces and can vary in magnitude and direction. They do not appear simultaneously with movements of mandible. Eg . Forces of gravity, posture and elasticity of soft tissues and muscles. 2) Dynamic : These are interrupted forces and appear simultaneously with movements of head and body and have higher magnitude than static forces. It depends on design and construction of appliance and patient’s reaction. Eg . Forces produced during swallowing. 18

19. 3) Rhythmic forces : These are associated with respiration and circulation , and are synchronous with breathing and their amplitude varies with pulse. The mandible transmits rythmic vibrations to the maxilla. They are important in stimulating cellular activity. These are intermittent and interrupted forces i.e. Force application to teeth and mandible is intermittent. Removal of activator from mouth interrupts these forces. 19

20. According to original Andersen - Haupl Concept The only forces acting in activator therapy are natural ones, however recent modifications with different designs and incorporation of additional elements (springs, jackscrews, magnets) have allowed use of active forces along with natural forces. 20

21. According to Moss, Petrovic,Woodside the condylar growth is an expression of a locally based homeostasis for establishment and maintenance of a functionally co- ordinated stomatognathic system. Petrovic has shown LPM plays a decisive role in growth because forward posturing of condyles activate its superior head of the LMP which induces cell-proliferation in condyle and a growth response in young people. 21

22. Up to a limited degree activator can control the upper growth vector supplied by sphenooccipital synchondrosis which moves the maxillary base forward. Activators with special constructions can influence growth and translation of nasomaxillary complex and can also alter the vertical skeletal relationship. Changing maxillary base inclination can compensate for rotations of mandibular growth vectors. 22

23. If activator is constructed with a vertical opening of bite with no or minimal saggital change the effects are mainly on mid facial development in subnasal area. 23

24. According to Woodside Small vertical opening  Restricts only horizontal mid facial development. Wide vertical opening  Downward displacement of midface area and decrease in S.N.A. angle. Extreme vertical opening  Maxillary plane is tipped upwards and point A moves forwards and increase in S.N.A. angle. 24

25. Effectiveness of activators during sleep Serves as a "Night Guard" preventing deleterious nocturnal parafunctional activity and stimulating normal muscle activity. (Mandibular protraction enhances metabolic pump activity of the retrodiscal pad thereby increases blood flow.. Protracted, unloaded condyle enhances condylar growth increments and favourable upward and backward growth direction. HOTZ, Petrovic , oudet , stuzmann stated that growth increments were greater at night due to increased growth hormone secretion. 25

26. Study Model Analysis T he first permanent molar relationship in habitual occlusion. Nature of midline discrepancy - if present, functional analysis done to determine the path of closure from postural rest to occlusion. If midline changes, functional problem is likely which can be corrected by the functional appliance. If the dentoalveolar midlines are not coinciding functional appliance cannot correct Symmetry of dental arches evaluated. If curve of spee - leveling needed is severe - activator cannot perform it. Crowding and any dental discrepancies are noted. 26

27. FUNCTIONAL ANALYSIS Precise registration of postural rest position. Path of closure determined. Prematurities noted. Clicking or crepitus in the TMJ palpated. Interocclusal clearence or free way space measured. Respiration (if disturbed nasal respiration present - choice will be an open activator) Size of tonsil and adenoids recorded. 27

28. CEPHALOMETRIC ANALYSIS Helps to identify the craniofacial morphogenetic pattern to be treated. Direction of growth determined (average, horizontal or vertical) Differentiation between position and size of jaw bases. Morphological peculiarities Axial inclination and position of maxillary and mandibular incisors. 28

29. VTO - VISUAL TREATMENT OBJECTIVES Is the method of predicting what the end result of treatment would be. Patient is asked to close the mouth in habitual occlusion and relax the lips - PROFILE is carefully studied. It can be photographed. Next the patient is asked to posture the mandible forward into a correct sagittal relationship, reducing the overjet . A photograph can be taken again. According to one of the methods, if profile improves with 1/2 protrusion FRANKEL recommended Full protrusion ACTIVATOR or BIONATOR If the profile still does not Improve ACTIVATOR with HEAD GEAR. 29

30. Treatment Planning : After the diagnosis of the kind of problem depending on the type of correction desired the type of appliance is planned. The main step instrumental in bring about the desired correction is the type of construction bite. The various types of construction bites areas follows. 30

31. CONSTRUCTION BITE Anterior Positioning of Mandible: The usual intermaxillary relationship for average class II problem is end to end incisal . However, it should not exceed 7-8 mm 'OR' three quarter of M-D dimension of Ist permanent molar 'OR' half the individual's maximum range. 31

32. Reasons: 1) If it is more than half the maximum range, it become more uncomfortable for patient and he may not keep appliance in mouth and patient may become less cooperative. 2) The distance between points of buccal cusps of Ist molars is the amount of distance necessary to change a class II malocclusion into class I occlusion. 32

33. It is claimed that one of the best position for obtaining desired histological transformation of TMJ from class II Malocclusion to class I occlusion is approximately half the distance that the condyles can move forward along the anterior wall of fossa to articulator tubercle. If it is greater than half it might prevent any favourable anatomical rebuilding of TMJ structures. 33

34. Contra Indications [for anterior positioning with this Magnitude] If overjet is too large (18mm eg in some cases) (Anterior positioning is done in stepwise progression in 2 or 3 phases.) Severe labial tipping of Maxillary incisors. [First upright incisors by prefunctional 34

35. Disadvantages Difficulty of wearing the appliance and adapting to new relationship. Muscle spasms often occur and appliance tends to fall out of mouth. Difficult to achieve lip seal. 35

36. OPENING THE BITE Vertical considerations are as important as to sagittal determination and are intimately linked to it. Maintaining a proper horizontal-vertical relationship and determining the height of bite are guided by following principles. Mandible must be dislocated from postural resting position in at least one direction  Saggittaly or vertically to active the associated musculature and induce strain in the tissues. 36

37. 2) If magnitude of forward positioning is great ( 7-8mm ) the vertical opening should be minimal so as not to overstretch the muscles.As It leads to increased force component in saggittal plane. 37

38. According to Witt  Saggittal force  315-395g Vertical force  70-175g Primary neuromuscular activation is in elevator muscles of mandible. 3) If extensive vertical opening is needed, mandible must not be anteriorly positioned i.e. if bite opening exceeds 6mm, protraction must be very slight. It is done in functionally true deep bite cases and cases with vertical growth pattern.  Both muscles and viscoelastic properties of soft tissue are involved. 38

39. GENERAL RULES FOR CONSTRUCTION BITE: If forward positioning is 7-8 m then vertical opening should be 2-4mm. If forward positioning is not more than 3-5mm then vertical opening should be 4-6mm. Activator can correct lower midline shifts if actual lateral translation of mandible itself exist. 39

40. If midline abnormality is due to tooth migration no asymmetry exists between treatment and medicine. An attempt to correct this type of problem may lead to iatrogenic asymmetry. Functional cross bite can be corrected by taking proper construction bite. 40

41. Steps for bite registration are as follows Mark the midlines , molar relation & desired mesial shift on the cast Train the patient after seating him in an upright & relaxed posture Soften a sheet of bees wax and roll it in to 1cm diameter Shape it and press it on the lower cast and mark the midline Transfer the wax to the patient’s mouth and fit it on the mandible Move the mandible as previously practiced 41

42. Remove the wax chill it and remove the excess Place the bite on the cast and check if the desired correction has been achieved Replace the hard wax in patient’s mouth and check after asking him to bite hard During bite registration the vertical dimension can be checked using the two reference points -On the tip of the nose - On the soft tissue chin 42

43. Construction bite for various types of activators ANDRESON APPLIANCE Vertical opening is within the limits of free way space ( 2 to 4 mm). Mandibular advancement being 3 to 5 mm. Used for less severe class II MO with deep bite and upright or lingually inclined lower incisor. 43

44. MODUS OPERANDI The appliance induces activation of MYOTACTIC REFLEX & ISOMETRIC CONTRACTIONS. These muscle forces are transmitted by the appliance to move the teeth. Thus the appliance uses KINETIC ENERGY. REFLEX CONTROL OF SKELETAL MUSCLE CONTRACTION MECHANISM OF STRETCH OR MYOTACTIC REFLEX Stretch reflex when elicited causes contraction of the stretched muscle. Muscle stretch receptors are proprioceptive nerve endings called muscle spindles situated within the muscle. 44

45. MUSCLE SPINDLES Contain THIN INTRAFUSAL MUSCLE FIBERS Nuclear bag region MUSCLE FIBRE (non contractile) (Striated & contractile) Impulses arise Conducted Group I A sensory fibre Synapse with '  ' efferents supply the extra fusal muscle fibre responsible CONTRACTION OF STRETCHED MUSCLE. Therefore called "monosynaptic reflex arc" Functional significance of stretch reflex serves as a mechanism for upright posture or standing. Similarly stretch reflex acts in the mandibular musculature to maintain postural rest position in relation to maxilla   45

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47. HARVOLD WOOD-SIDE ACTIVATOR The mandible is placed approximately 3mm distal to the most protrusive position sagitally and vertically an extreme separation of 10 to 15mm beyond the free way space. MODUS OPERANDI Here the mandible is opened beyond 4mm so it does not work in the same manner as Anderson's activator but by stretching of soft tissue - THE VISCO ELASTIC EFFECT. In such cases CLASP - KNIFE REFLEX plays a role. 47

48. Mechanism of clasp knife reflex or autogenic inhibition Example: Spastic limb Resistance encountered Due to Hyperactive reflex contraction If carried out forcibly Limb collapses readily This phenomena is called CLASP KNIFE RIGIDITY (i.e. muscle first resists and then relaxes 48

49. Stimulus is EXCESS stretch when elicited leads to muscle relaxation. Receptors are Golgi tendon organs situated in the muscle. Impulses conducted by group I B sensory nerve fibre act on motor neuron or '  ' efferent supplying the stretched muscle . It is a DISYNAPTIC REFLEX ARC because an inter neuron is interposed between sensory and motor neuron. Functional significance :- is to protect overload by preventing damaging contractions against strong stretching force 49

50. H - ACTIVATOR A ctivator constructed with low vertical opening and a markedly forward mandibular positioning is designated as horizontal or 'H' activator. 50

51. Indications: Class II Div 1 with sufficient overjet Class II Div 1 MO where there is mandibular overclosure that results in a functional retrusion of the mandible. In such cases activator can act in the sense of "Jumping the bite" Class II Div 1 MO with posteriorly positioned mandible due to growth deficiency with horizontal growth pattern. As a mandible moves mesially to engage the appliance, elevator muscle of mastication get activated. When teeth engage the appliance myotactic reflex is activated. In addition muscle force arising during biting and swallowing causes stimulation of muscle spindles which elicits reflex muscle activity 51

52. Effects of H - activator Mandible can be postured forward without tipping the lower incisors labially . LIP TRAP got eliminated Maxillary incisors can be positioned upright or lingually Anterior growth vector of maxilla is slightly inhibited. Class II Div 1 MO with vertical growth pattern when treated with H activator results in DUAL bite. 52

53. V-ACTIVATORS Activator with large vertical opening and minimal anterior positioning is designated as V activator. Mandible is positioned anteriorily only 3-5mm ahead of habitual occlusion. Vertical opening 4 to 6mm beyond the postural rest position. Indicated in vertical growth pattern. 53

54. MODUS OPERANDI Induces myotactic reflex activity. The greater vertical opening thus allows the myotactic reflex to remain operative even when the musculature is more relaxed ( that is when the patient is sleeping). Stretching of muscles and soft tissue elicits an additional force - the viscoelastic force. This stretch reflex influences inclination of maxillary base. 54

55. Deep bite MO. May be dentoalveolar or skeletal . In dentoalveolar problems, the deep overbite may be due to infra-occlusion of buccal segments or supra - occlusion of anterior segments. Construction bite may be moderate or high depending on the free way space. If it is due to supra - occlusion of anterior segments, interocclusal space is usually small and should resort to high construction bite. Intrusion of incisors is possible to only a limited extent when an activator in being used. 55

56. Skeletal deep bite MO's have a horizontal growth pattern, for which forward inclination of maxillary base can compensate. Loading the incisors can achieve a slight forward inclination of the maxillary base as well as frees the molars to erupt. Here the construction bite is high (5 to 6mm beyond the free way space ). A dento alveolar compensation is possible by extrusion of lower molars and distal driving of upper molars with stabilizing wires. 56

57. Open bite MO Anterior positioning of mandible is necessary if the skeletal relationship is orthognathic. Bite is opened 4 to 5mm to develop a sufficient elastic depressing force and load the molars that are in premature contact. 57

58. Arch length deficiency problems MO with crowding can sometimes be treated with the activator and can accomplish the desired expansion because it is anchored intermaxillarly . The appliance works in a manner similar to that of two active plates with jackscrews in upper and lower parts. Construction bite should be low. 58

59. Construction bite for class III MO Goal is posterior positioning of mandible or maxillary protraction. The construction bite taken by retruding the lower jaw. Extent of vertical opening depends on the retrusion possible. In PSEUDO CLASS III, functional deviation is present where the forced bite is easily achieved. The mandibular incisors hit prematurely in an end to end contact and mandible slides anteriorly to complete the occlusal relationship. In these cases vertical opening is for enough to clear the incisal guidance for construction bite. Here it is possible to achieve edge to edge bite relationship with posterior teeth still out of contact. In SKELETAL CLASS III MO with normal path of closure from postural rest to habitual occlusion, treatment not possible with functional appliance. 59

60. F abrication of the activator In short lab procedures include Mounting the casts to a fixator Preparation of wire elements. Which include labial bow made of 0.9 mm wire and Additional wire elements, like the stabilizing wire and active springs. Fixation of jackscrews and wire elements. Fabrication of acrylic portion. Finishing and polishing. This is different from trimming of the activator. Here only the rough edges are smoothened to prevent injury to the patient.  60

61. 61

62. Fabrication of the acrylic parts consist of upper , lower and inter occlusal parts . Upper and lower parts consist of dental and gingival portions . Flanges of upper part extends 8 to 12 mm high in gingival area and covers the alveolar crest. Flanges of lower part extends 5 to 12mm in gingival area. Flange extention is greater in V activators as the patients of this category have open mouth postures. Can be prepared with cold acrylic directly on models or wax pattern done and invested in a flask to be prepared in heat cure. 62

63. Clinical management of the appliance On the first visit insert the appliance and give instructions Initially it is worn for 2-3 hours in a day for the 1 st week Followed by night time wear and 1-3 hours of day time wear for 2 nd week. The patient is recalled for check up on 3 rd week Followed by check up appointments every 6 weeks Trimming according to the plan is started from second visit once the patient gets used to the appliance. Activation of wire elements are also done if necessary The patient activates Jackscrew at 2 weeks interval if necessary. 63

64. Trimming of the activator In order to stimulate the functional activity of the perioral musculature with the loose appliances so that the movement and eruption of selected teeth can be guided, certain areas of the acrylic which contact the teeth should be ground away. 64

65. VERTICAL PLANE Intrusion:- Only limited intrusion is possible. Relative intrusion is one of the objectives. Incisor intrusion: brought about by Loading the incisal edge. Labial bow placed in the incisal third. Molar intrusion brought about byAcrylic plate touching only the cusps. Acrylic plate ground away from fissures and grooves. If larger occlusal surfaces are loaded, reflex opening occurs frequently resulting in less depressing action by the appliance 65

66. Extrusion: indicated in open bite problems. Incisor extrusion Labial bow is placed in the gingival 1/3 Loading the gingival 1/3 on the lingual surface. Molar extrusion Enhancing eruption by grinding the acrylic plate from the occlusal surface. Acrylic contacting the gingival 1/3 on the lingual surface 66

67. SAGITTAL PLANE : Protrusion : L oading the lingual surface with acrylic contacts. Screening away lip strains with passive labial bow or lip pards . Auxiliaries used are Protrusion springs (0.8mm) Wooden pegs Guttapercha may be added to the lingual acrylic. 67

68. Retrusion : A crylic trimmed away from behind the incisors. Active labial bow. 68

69. FOR DISTAL MOVEMENT OF THE POSTERIORS g uide planes should be on the mesio lingual surfaces. Stabilizing wires or spurs can be used Active open springs. In class II div 1 MO with deep bite, acrylic contacts the mesio gingival surfaces of upper posterior and distogingival surface of lower posteriors. The upper teeth are hence guided in downward and backward directions and lower teeth in an upward and forward directions to establish the proper sagittal and vertical relations. Acrylic on the lingual surface of the upper incisors is ground away and labial bow made active if they are to be retracted . 69

70. transverse plane To achieve transverse movement lingual acrylic surface opposite the posterior should be in contact with the teeth. Higher level of force can be obtained by adding a thin layer of self cure soft acrylic. More effective expansion can be achieved with use of jack screws. 70

71. SELECTIVE TRIMMING OF THE ACTIVATOR During selective trimming only the upper or lower molars are extruded. After erupting, eruption of antagonist can be controlled. Thus both sagital and vertical relationship can be influenced. Eruption pathway of the molars should be considered. "CONTROLLED DIFFERENTIAL ERUPTION GUIDANCE" must be employed for the best interdental and occlusal plane relationship, particularly in case of flush terminal plane relationships, proper selective grinding can convert an impending class II or class III MO into class I interdigitation. 71

72. Pit falls of treatment with activator: 1. Dual bite (JCO 1983 May – Robert Shaye ) is commonly seen in cases treated with activator. Initially, positional adaptation indeed takes place during class II treatment. This Robert Shaye calls it as phantom activator phenomena. However the tendency to function in a forward mandibular position does not guarantee that structural adaptation will follow spontaneously. 72

73. Severe centric relation – habitual occlusion discrepancies may be observed in the form of dual bite succinctly termed as "SUNDAY BITE". It seen mostly in Post Pubertal Females treated with activators, Vertically growing patients treated with 'H' activator. If dual bite is present at the termination of treatment – it cannot be considered successful. DUAL BITE CASES ARE FAILURES 73

74. Activator produces labial tipping of lower incisors . In correcting class II MO, appliance contacts the lingual of the lower incisors, then as the muscles pull the mandible back toward CR position, incisor flaring easily occurs. This can be overcome by ACTIVATOR / HEAD GEAR combination (AJO 1996 July) Activator cannot produce detailed precise finishing of occlusion . It should be followed by short phase of fixed appliance therapy (or) require refinement of occlusion through tooth positioners . 74

75. Modifications of the activator: Various operators based on their treatment philosophy have suggested various modifications in the appliance design. These modifications of the activator are as follows:   75

76. Broadly categorized into 2 types Appliances with one rigid acrylic mass for maxillary and mandible arches but with reduced volume or bulk. Reduced volume in anterior palatal region to restore contact between tongue and palate eg . Elastic open activator Disadvantages : construction bite cannot be opened too much vertically Reduction in alveolar region and with a cross-palatal wire instead of full acrylic plate. Eg . Bionator Appliance consisting of 2 parts joined by wire bows. Muscle impulse are reinforced by wire elements in the design. Eg . Schwarz double plate 76

77. Eschler's modification Herren's activator (1953) Herren's shage activator – LSU activator The bow activator of Schwarz Reduced activator of Cybernator of Schmuth The Karwetsky appliance The propulsor The cutout (or) palate free activator Elastic open activator of Klammt Stockfish's Kinetor Hamilton expansion activator system. (or) Bonded activator Bionator Combined activator /HG Orthopaedics . MAD – Magnetic Activator Device. 77

78. 78 Harvold -Woodside activator –Cl-II Construction bite Vertical opening of 12-15 mm Flanges Labial arch wire Palatal contact and expansion

79. 79 Herren-Shaye activator Paul Herren of Zurich L.S.U of Robert Shaye Mandible positioned 2-3 mm beyond neutroclusion Incisal edges are 2-4 mm apart Trangular arrow head clasps Lingual flanges

80. Used for Cl III malocclusion Appliance is split horizontally Screw is embedded in the acrylic behind the incisors Occlusal surfaces are covered with acrylic Weise screw 80 Wunderer activator

81. 81 Bow activator- A.M.Schwarz Upper and lower parts are connected by a elastic bow Transverse mobility is believed to provide additional stimulus Independent expansion is possible Step wise advancement is possible Can be used in unilateral distoclusion Distortion and breakages common

82. 82 U-bow activator – Karwetzky Maxillary and mandibular active plates are joined in the 1 st perm molar region using a U shaped bow made of 1.1mm ss wire

83. 83 Bonded activator-Hamilton Mainly used in non compliant patients Used for expansion along with forward positioning of jaws

84. 84 Bionator -Balters 1960 Balters concept-position of the tongue is decisive Equilibrium between tongue and circumoral muscles is responsible for shape of dental arches and inter cuspation Bite taken in an edge to edge relation Dorsum of tongue in contact with soft palate Lip closure

85. Horse shoe shaped acrylic lingual plate Upper anterior part kept free for proper tongue function 85 Appliance design

86. 86 Labial bow with buccinator loops Palatal bar

87. 87 Basic Cl II appliance

88. 88 Class III or reversed bionator

89. Other differences Less bulky more patient compliance Can be worn all time except during meals Vulnerable to distortion Simultaneous requirement of stabilization of the appliance and selective grinding for eruption guidence 89

90. Ideal cases for bionator therapy 90 Mild Cl II in mixed dentition Well aligned arches Abnormal muscle pattern Buccal teeth are in infraclusion,-large freeway space Adults with TMJ problems Bruxism and clenching during REM

91. Bibiliography T.M.Graber , Thomas Rakosi , A.G.Petrovic ; Dentofacial orthopedics with functional appliances: 2 nd Edition, Mosby Co. 1997; Page no 161-194 T.M.Graber,Bedrich Neumann; removable orthodontic appliances : 2 nd edition W.B.Saunders Co. ; Page no 198- 310 91