Activator/certified fixed orthodontic courses by Indian dental academy


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Activator/certified fixed orthodontic courses by Indian dental academy

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Introduction  A functional appliance is one that changes the posture of the mandible, by holding it open or open and forward, stretches the soft tissues and changes the tone of muscles creating pressures which are transmitted to the dental and skeletal structures, moving teeth and modifying growth.  The goal of the functional appliance therapy is to favorably influence the growth of the mandible achieving optimal growth direction and amount and to eliminate any dysfunction or posteriorly retarded habitual occlusion.
  3. 3.  Definition – activators are those appliances which can activate muscle forces.  The term coined by Andersen & Haupl jointly in 1936.
  4. 4. Historical background  1880- Kingsley’s vulcanite plate-  “jumping the bite” for retruded mandible  Found to be a difficult job  No longer in use  Towards the end of 19th century- Vorbissplate-  Hotz’s modification of Kingsley plate for treatment of deep bite with functional retrusion of mandible.
  5. 5.  Hawley’s inclined bite plane-  A direct descendant of the kingsley plate.  Frequently used in TMD therapy.  1902- Robin’s monoblock-  For bimaxillary expansion  Advocated its use for glossoptosis in 1923 as it positioned mandible forward.
  6. 6.  1908- Viggo Andersen in Denmark-  Modified Kingsley plate with addition of horseshoe shaped acrylic extension in the mandible.  Used on his own daughter.  Named “active retainer or retention activator”
  7. 7.  1925- Andersen-Haupl activator-  Teamed up with Karl Haupl in Oslow, Norway.  Haupl was the one to explain it extensively, (Funktions- Keiferorthopaedic, Leipzig,1936, Herman Neusser) hence the name.  Some called it “Monoblock of Andersen”  Also called “Norwegian activator”
  8. 8.  Haupl justified their working hypothesis on writing of Roux- shaking the bone hypothesis in 1883- became background of both general orthopedic 7 functional dental orthopedics.  In 1918- Dr Alfred P Rogers conceived idea of functional aspects of muscles in treatment of malocclusion & is important correlation of activator treatment therapy- no success reported without concomitant use of appliance therapy.
  9. 9.  1933- Oppenheim published his investigation under title “crises in orthodontics”. Noticed potential tissue damaging side effects of heavy orthodontic forces.  Throughout Europe, activator became one universal appliance.
  10. 10.  1938- introduction of expansion plates by A.M Schwarz – added to development of activator.  Basically activator was loose appliance that works intermittently on Farrar’s biological principle “labor & rest”. Appliance uses m. action & hence it is an “myodynamic appliance”- meant for night time wear only.
  11. 11.  Conversion of myodynamic activator into myotonic- increase in interocclusal distance when Petric joined the group- Myotonic appliance of Andersen, Haupl & Petric.  1949- Bilmer appliance- developed his own system of functional appliances consisting of 3 types & 6 variations- “Elasticher Gebissformer”.
  12. 12.  1950- Bionator  Herren’s activator-  Learned about activator from Petric  Co-authored the 6th addition of the Andersen- Haupl’s classic text book “functions- Kleifer Orthopedic”  Later he modified the activator.  Utilizes the extreme sagittal displacement of the mandible.
  13. 13.  Elastic open activator- 1960-  Designed by G.Klammt, discipline of Bilmer in 1960, as Bilmer appliance was too fragile.  Harvold & Woodside (1971)-  The designs of their activator utilizes extreme vertical displacement.  Palate free activator- 1974- a modification of activator by Metzelder in 1974.  Propulsor- 1980- conceived by Mulhemann & refined by Hotz.
  14. 14. Force analyses in activator therapy  Static forces- gravity & posture & elasticity of soft tissues  Dynamic forces- produced during various actions like swallowing, opening & closing.  Rhythmic forces- associated with respiration & circulation.  Active forces- forces produced by springs, jackscrews, pads & magnets.
  15. 15. Mode of action of activator  Force elimination  Force application
  16. 16. Force application  Types of force employed in Activator Therapy:  The growth potential including the eruption and migration of teeth gives rise to natural forces. These can be guided, promoted or inhibited by activator.  Muscle contractions and soft tissue stretching initiate forces when the mandible is relocated. The contractions are stimulated and transformed by the activator. These artificial functioning forces can be effective in all three planes of space.
  17. 17. a) In the sagittal plane, the mandible is propelled forward and muscle force is delivered to condyle and strain is produced in the condylar region. A slight reciprocal force is transmitted to the maxilla. b) In the vertical plane, teeth and alveolar processes are either loaded with or relieved of normal forces. with a high construction bite, greater strain on maxilla, can have an inhibitory effect on growth increments and direction and can influence the inclination of maxillary base.
  18. 18. c) In the transverse plane it is possible to create forces with midline corrections.  Various active elements like springs and screws can also be incorporated.
  19. 19. 3 concepts explaining mode of action of activator  Original Andersen-Haupl concept-  New function can change the internal structure of bone.  During growth, new function can change external shape of bone also.  Induces musculo-skeletal adaptation by introducing new pattern of mandibular closure.  Myodynamic appliance- uses kinetic energy through stretch reflex.
  20. 20.  The forward positioning of the mandible activates superior head of LPM, induces a cell proliferation in the condyle & a growth response (Petrovic)  Acc to Grude (1952) , this action is observed only if the mandible is not displaced beyond postural rest position.
  21. 21.
  22. 22. Drawback-  When mouth is opened only 3-4 mm by the appliance 1 or 2 things can happen-  Appliance may fall out  The wider open position does not permit it to mandible & result- ineffectiveness
  23. 23. Concept of visco-elastic property  The concept was to overcome the drawback of previous theory.  If the mandible opens beyond the 4mm limit, the appliance does not work in the manner Andersen & Haupl had suggested.  Clasp-knife reflex is initiated that builds up potential energy.  Herren overextends in the sagittal plane moving mandible into anterior cross bite position  Woodside opens as much as 10-15mm beyond the postural rest position.
  24. 24.
  25. 25.  Depending upon the magnitude & duration of the applied force, the viscoelastic traction can be divided into the following stages-  Emptying of vessels  Pressing out of the interstial fluid  Elastic deformation of the bones  Bioplastic adaptation
  26. 26. Concept of combined principles  Uses m. contraction & viscoelastic properties of the soft tissues.  Greater bite opening than Andersen & Haupl but don’t over compensate as Woodside (4- 6mm opening)  Ultimate mechanism depends on value on malocclusion, interocclusal clearance, head posture, state of mind & level of conciousness.
  27. 27.  Escher (1952)- works alternately with isotonic & isometric contractions.  Cycle- at insertion of appliance mandible elevated by isotonic m. contraction – in contact with the appliance isometric m. contractions start. As mandible cant reach postural rest position, elevators remain stretched- fatigue & mandible drops & cycle begins again.
  28. 28. Objectives of activator treatment  To achieve major changes in facial esthetic  To achieve major occlusal changes in the M- D, vertical & transverse planes of space.  To remodel arch form  To achieve moderate reductions in skeletal dysplasia b/w maxilla & mandible.  To change the direction of the mandibular growth by vertical manipulation.  Correction of incisor cross bite by vertical manipulation.
  29. 29. Limitation of activator treatment  Mandible anchorage loss  Relative retrusion  Cant be used itself for decrowding & doesn't perform detailed tooth positioning.  Effective in growing pts only  Tends to produce moderate mandibular rotations so contraindicated in pts with excess lower facial height.
  30. 30. Indications of activator treatment  used in moderate skeletal dysplacias between the midfacial area and the mandible in which case moderate amounts of mandibualr growth and maxillary- incisor retraction may combine for successful treatment primarily in actively growing individuals with favourable facial growth pattern.  Well aligned maxillary and mandibular teeth and mandibular teeth should be upright over basal bone structures.  It provides a superb treatment in children with lack of vertical development in lower face height because differential vertical alveolar development can be readily obtained in either the maxillary or arch as desired. mandibular  It provides a useful preliminary treatment before major fixed appliance mechanotherapy.  It is useful for post treatment retention in children with a deep overbite caused by overclosure.
  31. 31. Facial morphology best suited for activator therapy  1. Correction of dentoalveolar Class II malocclusions: As activator is a form of intermaxillary therapy, it can cause mandibular dentition slip labially and maxillary dentition lingually. Hence it is suitable for correction of dentoalveolar Class II malocclusions characterized by lingually positioned mandibular dentition and labially positioned maxillary dentition.  2. Moderate skeletal dysplasia: Moderate skeletal dysplasia in which moderate amount of mandibular growth and maxillary incisor retraction may combine for successful treatment. It is not suitable for management of skeletal dysplasia of any morphological type that exhibits extremes dysplasia between the mid facial area and the mandible unless it is to be used as the first stage of 2-stage treatment.
  32. 32.  3. Ideal for management of Class II malocclusion resulting from environmental influences e.g. thumb sucking and chronic mouth breathing if some growth still remains and the oral habit can be eliminated. The exact prevalence of this type of malocclusions is not known but should be suspected in any Class II malocclusion exhibiting excessive lower facial height is not due to environmental factors, the activator can propude further deterioration in the facial aesthetic.
  33. 33. CLASS II MALOCCLUSIONS BEST MANAGED BY THE ACTIVATOR .  The activator constitutes a form of class II intermaxillary therapy and if it is used, correctly, it can cause the mandibular dentition to slip labially. Thus activator can correct dentoalveolar class II characterized by lingually positioned mandibular dentitions.  Activator is less appropriate in skeletal problems associated with extreme apical base dysplasias due to mandibular retrognathism. Unless the patient has a favorable amount and dereliction of growth in the midfacial and mandibular areas, the, maxillary dentition must be retracted bodily to camouflage the skeletal dysplasia. The activator is not suited to perform active bodily retractions of incisor teeth.
  34. 34.  The activator is more suited for class II resulting from midfacial prognathism when the direction of and amount mandibular growth are favorable. Retraction maxillary dentition of is avoided to prevent overemphasizing nose prominence. The activator does not perform active bodily retractions of teeth, it is suited for use in children who need minimal amounts of maxillary incisor movement while mandible develops forward to camouflage the midface prognathism.
  35. 35.  Activator is suitable for the not management of skeletal dysplasias of any morphological type that exhibits extreme dysplasia midfacial between the area and the mandible.
  36. 36.  Class-II division-I malocclusion has the midfacial area and the mandible were harmoniously related. With permanent alteration in the rest position of the mandible as an chronic nasal obstruction the mandible assumes an environmentally increased retrognathic position. This represents a neuromuscular malocclusion, since its origin involves the alteration of some very basic neuromuscular reflexes.
  37. 37.  It is ideal for the management of class II resulting from environmental influences such as thumbsucking and chronic mouthbreathing. If some growth still remains and the oral habit can be eliminated. These are probably environmental stimulations of skeletal problems.  However, if the lower face height excess is not due to environmental factors, the activator can produce further deterioration in facial esthetics.
  38. 38.  There is another class II neuro-muscular malocclusion characterized by a normal path of closure, excess freeway space and overclosure may appear class I in overclosed positioned but they are real class II in rest position. Obviously this is not a case of deep bite. But rather of apparent overbite, more correctly be classified as a complete open bite.
  39. 39.  The cause of this excess freeway space or the complete open bite is an abnormal posture of the tongue during rest in this individual. Because tongue rests on the occlusal surfaces, teeth are not permitted to erupt but the jaws continue their normal downward and forward growth. As growth continues, the inhibition of tooth eruption creates an increasing excess freeway space.  Orthodontic treatment for this patient would more correctly be planned around the jaw relationships indicated by the rest position tracing rather than the overclosed centric occlusion tracing which actually gives a more prognathic position of the mandible than actually exists.  The activator is an ideal appliance to effect the differentia tooth eruption in the maxillary and mandibular buccal segments.
  40. 40. CONTRADICATIONS  Activator is not useful in correction of class I class II malocclusion with crowding. It may be used to assist in the correction of disharmony between in tooth size and jaw size has been being managed concurrently through serial extractions.  Activator is contraindicated in children with extreme LAFH.  It should not be used in case where there is mandibular incisor procumbency at start of treatment.
  41. 41.  The appliance cannot be used in children with nasal stenosis caused by structural problems within the nose or chronic untreated allergy.  appliance has limited application in the non growing individuals though it may be used successfully in cases where clinician has determined that the patient's facial morphological condition will tolerate increase in lower face height.
  42. 42. SKELETAL AND DENTOALVEOLAR EFFECT OF ACTIVATOR  During craniofacial growth the activator is capable of influencing the third level of articulation, as outlined by MOFFET, i.e. the sutures and the TMJ. This efficiency is determined by construction bite.  SKELETAL EFFECT - is dependent on the growth potential.
  43. 43.  Two divergent growth vectors propel the jaw bases in an anterior direction.  Sphenooccipital synchondrosis moves the cranium base.  and nasomaxillary complex upward and forward.  The Activator can, to a limited degree control this upper growth vector which moves the maxillary base in a forward direction. If the mandible cannot be positioned anteriorly, the growth and translation of the nasomaxillary complex can be influenced.  The vertical skeletal relationship must be assessed and can be altered, if need be by the activator.  Rotations of mandibular growth vectors can be compensated by changing the maxillary base inclination.
  44. 44.  A downward displacement of the maxillary base allows an adaptation of the maxilla to a vertical rotation of the mandible.  Activator constructed with vertical opening only effect primarily the midface development in the subnasal area.  Both vertical maxillary growth and eruption of teeth are restricted.  DONALD WOODSIDE believes that a small vertical opening restricts only the horizontal midface development whereas a wide vertical opening achieves the restriction by the downward displacement of the midface area.  A decrease in SNA angle can be observed unless the bite opening is extreme. In such cases the maxillary plane is then tipped forward and point 'A' moves a little forward.
  45. 45.  The second growth vector, the condyle translates the mandible in a downward and forward direction. The activator is most effective in controlling this vector or the downward and forward growth of the mandible.  This effect can be designated as an articular one, because of the promotion or redirection of condylar growth.  Only the upward and backward growth of the condyle is capable of moving the mandible anteriorly.  According to MOSS, PETROVIC, Condylar growth is an expression of a locally based homeostasis for the establishment and maintenance of a functionally coordinated stomatognathic system.
  46. 46.  PETROVIC's research has shown- the lateral Pterygoid m. plays decisive role.  Forward posturing of the mandible activates the superior head of lateral pterygoid & induces cell proliferation & growth in young individuals.
  47. 47.
  48. 48. Effect on mandible  Birkebaek et al (1984): laminographic implant study-  1.1mm increase in condylar growth in 10 months  Slight forward displacement of glenoid fossa  1.1mm increase in LAFH  Increase in MPA by 2.5 degree  Demner el al (1961), Vargervik & Harvold (1985) found similar increase in mandibular length.
  49. 49.  Pancherz (AJO 1984):  Evaluated 30 class II div I children in the mixed dentition who were treated sucessfully  Only 0.3mm increase per year, not statistically significant.  Bjork (AJO 1951), Watson (AJO 1981) observed similar results.
  50. 50. Effects on maxilla  Williams & Melsen (AJO 1982)- demonstrated backward rotation of mandible due to increase in posterior maxillary height.  Forseberg & Odenrik (EJO 1981) noted a significant decrease of the SNA angle  Vagervik & Harvold (AJO 1985)- inhibited horizontal growth of maxilla by 2mm  Pancherz (AJO 1984) found restriction by 1.7mm
  51. 51. Dental effects  Various tooth movements have been observed during activator therapy-  Forward displacement of anterior segment (Bjork 1969)  Bodily displacement of incisors (Jacobsen in 1967)  Labial tipping of lower incisors (Richardson in 1982)  Lingual tipping of lower incisors (Moss in 1962)
  52. 52.  Studies by Bjork, Weislander & Harvold showed following effects-  Class I occlusion was achieved through distal tipping of maxillary teeth & mesial mov. Of mandibular dentition.  70% of overjet was corrected by incisal tipping- 50% by lingual movement of maxillary incisor while 22 % by mandibular incisor flaring.
  53. 53. Effect on soft tissues  Forsberg & Odenrick (EJO 1981)-  Significant lip retrusion  No difference in nose growth  Significant forward positioning of soft tissue pogonion  Lip balance was not achieved in pts with relatively retrognathic profiles or those with steep MPA’s
  55. 55. EFFICACY OF ACTIVATOR  With the proper construction of the appliance, muscles of mastication that are extended slightly past resting position are automatically stimulated to contract (stretch or myotatic reflex) according basic muscle physiological principles. The same contractive tendency occurs when the sublingual muscles are extended by the forward positioning causes labial tipping or Labial bodily movement of lower incisors.
  56. 56.  ANDRESEN and HAUPL believed that the presence of a loosely fitting activator increases muscles of mastication against the appliance.  Intermittent movements of the appliance in swallowing and biting deliver distal and intrusive forces to maxillary teeth engaged in the appliance.  Activator being trimmed loosely, it will drop when the jaws relax. The patient must be conditioned to bite into the appliance to keep it in position, and if correctly motivated, a conditioned reflex is soon developed and this act is performed while sleeping.
  57. 57.  So when the mandible moves mesially to engage the appliance, the elevator muscles of mastication are activated, the myotatic reflex is activated, so that in addition to the muscular force delivered during swallowing and biting, the reflex stretch stimulation of the muscle spindles also elicits reflex muscle activity.
  58. 58.  Thus forces elicited result in tooth movement and bone remodelling and may prevent further forward movement of maxillary dentoalveolar process or move it slightly distally.  The activator of ANDRESEN & HAUPL works by using kinetic energy.
  59. 59. Why appliance s/b loose fitting  The superior heads of the lateral pterygoid have the most important role, since they assist in skeletal adaptation.  The fundamental requirement for stimulation is ability the to activate pterygoids.  An appliance holding the mandible rigidly in anteriorly displaced position does not activate LPM m. & hence does not stimulate condylar growth.
  60. 60. Timing of treatment
  61. 61. Fabrication of activator appliance  Diagnostic preparation- Patient compliance is essential. It is important to clinically assess the somatic and psychological aspects for each patient also determine the patient's motivation potential. This may be enhanced by creating an instant correction in class II by moving the mandible forward into a more normal sagittal relationship. Patient sees the potential and objectives of the correction to be brought about by the appliance and is more likely to work toward this goal of esthetic improvement.
  62. 62.  In some cases of maxillary protrusion and excessive vertical dimension with reduced symphyseal prominence, A forward positioning will not make the profile look better, in which case other treatment measures are employed.
  63. 63. VTO
  64. 64. PRETREATMENT CONSIDERATIONS  Before treatment with the activator is started, the forward movement of the mandible should be checked to see that it is not blocked by the occlusal interferences that make the correction of the distocclusion impossible, which is usually by,  Narrow intercanine dimension.  Lower second molar slightly over erupted distal to the first molar, it will impede the forward movement of the mandible.  Overeruption of maxillary second deciduous molar into the space created by the premature loss of its antagonist.  A quite common and easily overlooked causes for interference is the buccal cross bite of an upper premolar.
  65. 65. Before bite registration few analyses have to be done.  Study Hodel Analysis:  1. The 1st permanent molar relationship.  2. Nature of midline discrepancy if any  3. Symmetry of the dental arches is determined.  4. Curve of spee is checked to see if it can be leveled with the activator.  5. Crowding and any dental discrepancies  Functional Analysis:-  1. Rest position  2. Path of closure  3. Prematurities  4. THJ examination  5. Interocclusal clearance  6. Respiration  Cephalometric Analysis  1. The direction of growth  2. The difference between the position and the size of the Jaw bases.
  66. 66.  ANDRESEN'S first activators did not displace mandible beyond the physiologic rest position relative the vertical and was 3 mm short of the limit of the patient's tolerance relative to the protrusion.  First to oppose was SELMER-OSLEN  1. Muscles couldn't be stimulated at night, for this was the time nature used to give them rest.  2. Forces delivered to the teeth by the appliance were a form of potential energy and not kinetic energy.  3. Andresen's 2-4 mm opening in molar region is beyond physiologic rest position.  4. He said Andresen is wrong if he thought an appliance holding the jaws a 2 mm beyond is a truly functional passive appliance. Construction bite
  67. 67.  PAUL HERREN- activator didn't work according to Andresen's theories at all, even if it was constructed within the physiological limits of rest position. His construction bite is in sagittal direction, the mandible is positioned in an overcompensated by 3-4 mm. Vertical opening - 2-4 mm plus the deep bite that is already present.  The Louisiana state university acivator of ROBERT SHAYE (1982) essentially follows the same design and principles.  HARVOLD (1974) said you have got to go Stretch the muscles, the more stretch, the better. His construction bite - 3 mm short of patient's limit of tolerance in .protrusive position but with a 8-10 mm vertical opening beyond the rest Position.
  68. 68.  WOODSIDE (1974-75) - said to go even further beyond rest position to 12-15 mm  GRABER and NEUMANN said use a combination of bite opening and protrusion to equal to 10 mm. In other words, if you open the bite 4 mm between the occlusions posteriorly then advance the mandible by 6 mm.  BALTERS of Germany advocated protrusive incisal end-to end with an interincisal opening of 2-3 mm.
  69. 69.  Construction s/b made considering vertical, horizontal & transverse planes
  70. 70. Horizontal posturing of mandible 1. The original sagittal jaw relationship may be maintained. 2. Mandible may be positioned forward to change the sagittal relationship equally on both sides. 3. The bite is changed on one side but is maintained as much as possible on the other side as with a unilateral Class II Div. 1 or class II Div. 2 or class III. This means that a normal midline relationship exists in postural rest, but a midline swing to the side that is forced in the habitual occlusal relationship. 4. The mandible is postured backward as much as possible in the fossa, opening the bite enough to try for an end to end incisal relationship or as close to this as possible, in class III malocclusions.
  71. 71. Vertical opening of mandible  Dependent on three major considerations:  (1) The kind dysgnathic problem (Sagittal and vertical relationships, morphogenetic growth pattern)  (2) the developmental state, sex, and age of the patient (potential incremental change)  and (3) the type of activator to be used.
  72. 72. Type of malocclusion:  Different sagittal and vertical dysplasias require different construction bite registrations. For example, in deep bite Class II, Division 2 and Class III malocclusions, it is necessary to record the vertical distance between incisal of lower incisors the upper and margins determining how wide open the construction bite should  In permanent dentition cases (specifically in Class II Division II malocclusions or class I Division 2 symptoms, or in anterior cross bites, e.g., Class III malocclusions), it is best to open the bite the for the construction registration a distance of 1.5mm to 3 mm, vertically beyond the incisal edges.
  73. 73.  In the mixed dentition, it should be increased to 4 mm. to 7 mm. Thus, the original overbite is a determining factor.  In the Class II, Division malocclusion 2 a severe in the permanent dentition, the bite may have to be opened up to 9 mm. in the molar region and occasionally more.  Woodside feels it improves the chances of retention during sleep and enlists the viscoelastic properties of the stretched soft tissues.
  74. 74.  The reason the bite can be opened so far is that type of Class II, Division 2 malocclusion most frequently has a palatal plane that is tipped down anteriorly along with a deep bite and an excessive curve of spee. A large bite opening can improve the maxillary incisor inclination because the anterior end of the palatal plane is with held or tipped up and this also reduces the deep overbite because the lower incisors are under intrusive action as the maxillary base rotates upward and forward.
  75. 75.  The wide open construction bite brings the mandible out of the range of any tooth guidance and resultant retrusive effect on the condyle and the path of closure. Also such cases usually do not have a severe sagittal malrelationship and usually have a good chin- button morphological appearance so rocking open the bite, which drops the symphysis down and back, does not have a deleterious effect on the profile. This is particularly true since in most of these cases there is a horizontal growth pattern.The large vertical opening improves the growth direction and allows the full eruption of the posterior teeth, which are usually in marked infraocclusion.
  76. 76.  If only mandibular positioning is needed, or a small anterior posturing is required the (only maxillary teeth spaced & labially inclined ) , the vertical opening should be rised more in order to elicit more positive functional and viscoelastic response from musculature.  Class II, Division 1 problems demanding more horizontal posturing to establish correct maxillomandibular relationship, a smaller vertical opening is needed, particularly if the growth direction axis is along the y axis.
  77. 77.  In cases with a more vertical growth direction and a deep overbite, a larger bite opening is desirable for the construction bite registration This allows some downward and backward compensation of maxillary growth (and palatal plane) to fit the mandibular growth pattern.
  78. 78.  In Class II, Division I malocclusions in which  (1) the sagittal malrelationship is the width of a whole premolar;  (2) there is a severe curve of Spee  (3) the lower incisors are over erupted, impinge on the palatal mucosa, the construction bite should not be higher than vertical end to end relationship.
  79. 79.  This is because the interocclusal distance in the molar region, with infraocclusion of the molars and supraocclusion of the lower incisors, might exceed 7 mm which would be excessive because of the possible lateral spread of the tongue.  If moderate curve of Spee vertical opening s/b increased to allow for posterior eruption & getting favorable muscle balance. In such cases, 4mm. Between incisal edges is desirable, and it can occasionally be even more.
  80. 80.  In the case of a synchronous downward and backward arciform growth pattern and an average incisor overbite, caution is the watchword, so as not to accentuate the molar eruption too much, which will create a more retrusive profile and possibly induce an anterior open bite that will be difficult to close.  The interocclusal space should not exceed 4 mm in the molar region. The same applies to anterior open bite problems. The interocclusal acrylic table or tooth bed should not be ground away in such cases, but rather should maintain constant intrusive contact on the upper and lower posterior teeth in both arches.
  81. 81. Type of activator
  82. 82. Transverse posturing of mandible  If the upper and lower midlines do not coincide, a determination must be made as to the fault - maxillary or mandibular. The patient is observed in postural rest position to check the midlines and is then asked to slowly close the mouth into full habitual occlusion.  1. Midlines of postural rest position and occlusion coinciding - construction bite no change.  2. Postural rest position coincides with midlines while occlusal position does not, this is due to shift from one side to other, occlusal interferences should be checked. Construction bite should follow the resting Position midline relationship.
  83. 83.  3. Midlines of both in rest and occlusion - caused by shifting of teeth in one jaw or the other. The construction bite should line up with the midlines of maxilla and mandible regardless of shifting of teeth. Dental midline discrepancies caused by shifting and malposition of the teeth can be corrected late with the fixed appliances. Occasionally a short pretreatment fixed appliance to correct midline.
  84. 84. Construction bite planning  The purpose of the construction bite is to fabricate an appliance that induces the following effects:  (1) to bring the lower jaw into a tolerable forward position with every occluding action of the mandible  and (2) to "block the bite“ depressing the lower anterior teeth and stopping their eruption, while attempting to stimulate eruption of the posterior segments.
  85. 85.  Taking the construction bite one should look at the bite in three different planes of space: sagittal , vertical and frontal.  Therefore it is first necessary to clarify three points using the procedure developed by Schwartz.
  86. 86. Anterior positioning mandible  The usual intermaxillary relationship for the Class II problem is that of end to end an average incisal relationship. However. it should not exceed 7 mm to 8mm. Or quarters of the mesiodistal dimension of the first permanent molar. Anterior positioning of this magnitude is contraindicated in the following instances:
  87. 87.  If the overjet is too large (in extreme cases approach 18 mm) the anterior positioning becomes a stepwise progression to be accomplished in two or three phases.  If there is severe labial tipping of the maxillary incisors. they should probably be uprighted first if possible by a prefunctional appliance.
  88. 88.  If one of the incisors usually the lateral incisor has erupted markedly to the lingual the mandible must be postured anteriorly to an edge to edge relationship with the lingually malposed tooth otherwise labial movement of this tooth would not be possible. Eschler termed this a "pathological" construction bite.
  89. 89. THE EXTENT OF MAXIMUM FORWARD MOVEMENT OF THE MANDIBLE (SCHWARZ)  In a normal case, the maximum forward movement of the mandible averages 9-10mm, but as little as 6- 7mm. The optimal forward movement of the mandible for the construction bite is usually half the individual’s maximum range. There are three reasons for this –  more uncomfortable for the patient  The distance of 5mm is approximately is the same as that between the points of the buccal cusps of the first molars. This is the amount of distance necessary to change a class II malocclusion into a class I occlusion.
  90. 90.  It is claimed that one of the best positions for obtaining the desired histological transformation of the TMJ from a Class II malocclusion into a Class I is l approximately half the distance that the condyle can move forward along the anterior wall of the fossa to the articular tubercle.
  91. 91. Opening the Bite  There are some guiding principles in maintaining a proper horizontal vertical relationship and determining the height of the bite-  The mandible must be dislocated from the resting position in at least one direction - sagittally or vertically. This is essential in order to activate the associated musculature and induce a strain in the tissues.
  92. 92.  If the magnitude of the forward position is great (7mm- 8mm), the vertical opening should be minimal so as not to overstretch the muscles. This type of construction bite means an increased force component in the sagittal plane, enabling a forward positioning of the mandible. The primary neuromuscular activation is in the elevator muscles of the mandible.
  93. 93.  If the vertical opening must be extensive, the mandible must not be anteriorly positioned. If the bite opening is more than 6 mm, mandibular protraction must be very slight. Myotatic reflex activity of muscles of mastication can then be observed as can a stretching of the soft tissues. A more extensive bite opening is possible in functionally true deep-bite cases. If the bit registration is high both the muscles and the viscoelastic properties of the soft tissues are enlisted.  The vertical force is increased and the sagittal force is decreased. This type of construction bite is not effective in achieving anterior positioning of the mandible, but the inclination of the maxillary base can be influenced.
  94. 94.  One possible indication of this type of construction bite is in the case vertical growth pattern. In such cases, the vertical relationship, either deep bite or open bite, can be therapeutically affected the activator.  The disadvantages of a wide construction bite are the difficulty in wearing appliance, with increased difficulty of patient to adaptation. Muscle spasms often occur in such cases, and appliance tends fall out of mouth. The wide open construction bite also makes the lip seal difficult. Yet the reestablishment of a normal lip seal is essential requisite of functional appliance therapy.
  95. 95. The Extent of the Individual's Occlusal Clearance in the Resting Position: (Schwarz)  Clinical experience indicates that the opening of construction bite in excess by approximately 2mm individual's position is optimal. Resting individuals the interocclusal clearance amounts to 2 mm to 3mm in the molar area. and 4mm. to 5mm in the incisor area. An opening of 4 mm to 5mm in the Molar area and 6mm to 7mm in the incisor area frequently will desired.
  96. 96.  As we know from the study of rest position when mandible is open beyond this position. the condyle moves downward and forward on the articular eminence. Thus the bite open more than 5 mm. in the molar area, forward movement of 4mm. will suffice.
  97. 97.  Highly experienced clinicians such as Petrik and Herren entirely disregard the rest position.  Petrik – The upper and lower incisal edges should meet in as close to an to edge relationship as possible in a horizontal plane. This maneuver will generally leave the incisors 1mm to 4mm. Apart at most, with a posterior bite opening of 4mm. to 7mm. Contrary to many other clinicians, Petrik also given preference to bring the mandible forward to the complete desired distance at once, not in stages.
  98. 98.  The configuration of the original malocclusion and the movability of the mandible must be studied carefully before deciding which technique to follow.  Taking the construction bite is a most important step in the treatment. It should be done directly in the patient's mouth. No articulator duplicates the exact condylar pathway as in the patient.
  99. 99. General rules for the construction bite:  If the forward positioning of the mandible is 7mm to 8mm the vertical opening must be slight to moderate(2mm-4mm).  If the forward positioning is not more than 3mm to 5mm the vertical opening should be 4mm to 6mm.  Lower midline shifts or deviations can be corrected by the activator only if there is actual lateral translation of the mandible itself. Functional cross bites that are observed in the functional analysis can be corrected by taking the proper construction bite.
  100. 100.  Both experimental research and clinical experience have shown that an increase in muscle activation with overextended appliances does not increase the efficiency of the activator.  Acc to Sander- the frequency of maximal biting into a 6mm. high construction bite is 12.5 percent of the sleeping time, whereas in an 11mm construction bite it is only 1.1 percent of the time. If the height is increased to 13mm as prescribed by Harvold, maximal biting takes place only 0.8 percent of the time.
  101. 101. EXECUTION OF THE CONSTRUCTION BITE TECHNIQUE  First, a horseshoe-shaped wax bite rim is prepared for insertion between the maxillary and mandibular teeth.  Choice to keep bite on lower or upper arch
  102. 102.  Before taking the wax bite registration, the patient is seated in an upright position. The posture should be relaxed and not strained. The mandible is then gently guided the predetermined position. The operator guides but not force the jaw into the desired sagittal relationship. This exercise is repeated three or four times.
  103. 103.  The patient is asked to repeat the exercise alone and then hold the forward position for a while to set up an exteroceptive engram that can be replicated when wax is placed between the teeth.
  104. 104.  After the operator is relatively sure that the patient can replicate the exercise, the softened wax bite placed in the mouth in the manner already described.  Wax should not be too soft. During the closing movement, the operator controls the edge to edge incisal relationship and the midline registration.  To visualize the midlines & to establish correct reproduction of the incisal relationship, wax should be cut away from the labial surface of the central incisors.
  105. 105.  In the final step, the wax is carefully removed from the mouth without distorting and is checked on the upper and the lower models and chilled.  After it has been fitted on casts, the margins are trimmed with a scissors, so the operator can be sure the wax is in close approximation to all the cusps of the teeth.  The hardened wax bite is then checked once again in the mouth.
  106. 106. Sequential steps for the construction bite: Schwartz  The following step by step procedure for taking the construction bite is suggested: 1. Reproduce the maximum forward movement of the mandible and the correct occlusal clearance of postural rest. Observe whether a functional lateral shift occurs and register the true mandibular midline with a pencil on the labial surfaces of the upper and lower incisors on the casts and in the patient's mouth. 2. Determine the amount of mesial and vertical mandibular displacement necessary for the construction bite. It is helpful to mark the amount of mesial shift with a pencil on the buccal surfaces of the first molars. 3. Show the patient on the casts and in the mirror in which direction the mandible should be moved. Practice the forward mandibular movement by gently guiding the mandible in the desired direction.
  107. 107.  Advise the patient to move the jaw slowly according to the verbal instructions and to stop movement immediately when asked to do so. Talk to the patient in a calm, reassuring manner. 4. Soften a sheet of beeswax and make a tight roll, approximately 1 cm in diameter. 5. Shape the roll to conform to the lower dental cast, leaving the seam on the inside. Press the softened roll of wax on the lower arch so that only the buccal teeth are covered. In the front, the wax roll lies just lingual to the lower incisors. Make a groove on the wax to indicate the midline. Remove any excess wax that extends onto the retromolar tissue. The distal half of the last molar tooth should not be covered with wax.
  108. 108. 6. Transfer the wax to the patient's mouth, fitting it on the lower arch in the same manner that it was fitted on the plaster cast. 7. Move the mandible forward as was previously practiced. If the registration fails, make a new wax roll and repeat. 8. Remove the wax bite from the mouth and chill it. With a sharp knife, trim the excess buccal wax until the occlusal surfaces of the molars are visible. By carefully checking the plaster casts, also remove all wax that is contacting the soft tissues, the interproximal papillae, and the palate. If this is not done, the wax bite cannot be seated properly on the casts.
  109. 109. 9. Place the wax bite between the casts and check that the mandible is moved forward the desired amount in the three planes of space. If the construction bite is incorrect, replace it on lower cast, and soften its superior surface add a layer of warm wax. Repeat the procedure from No.6 through No.1O. 10.Replace the hard wax bite in the patient's mouth and have the patient close the jaw slightly more firmly to assure the correct fit.
  110. 110. Mounting & fabrication of appliance  After the construction bite is taken and checked in the patient and rechecked on stone working models, the working models are mounted on the fixator.  Fixator- Allows upper and lower parts to be made separately.
  111. 111. Making of wire elements  Labial bow – horizontal portion can be kept above or below area of greatest convexity depending on overbite.  Passive- .8mm  Active- .9mm
  112. 112.  Labial guide bow philosophy- when appliance in mouth- pt can close only by bringing mandible forward.  When pt speaks or moves jaw up or down, the sensory n’s of the maxillofacial complex sense the smooth coordinated action the labial bow as it slides up & down over the 6 anterior teeth.
  113. 113.  These receptor help activate the oro-facial muscles to keep the mandible in the protruded position as it closes to keep the appliance moving vertically in a smooth and coordinated motion.  The labial guide bow also acts to hold the inner surface of the upper lip away from the premaxilla and anterior teeth. The space or clearance of I mm between the wire and labial surface of teeth which is sufficient to break the directness of the force vector of the weight and strain of the upper lip in this area.
  114. 114.  Due to the increased vertical dimension of the appliance the perioral musculature is put to increased myotonic tension. This myotonic tension is further increased when lips attempts to seal during swallowing. This increased pressure can rotate a premaxilla, teeth and all in a distal direction without something to stop to it.
  115. 115.  The labial bow anchored against the acrylic base of the appliance and by means of this, through force vectors to the mesial of first molars holds the lip away from the teeth and bone just enough that no movement of this type will occur. Therefore the myotonic stretch placed on the orofacial muscles by the appliance causes a distal drive to be exerted through the interproximal evaginations of acrylic.
  116. 116.  Since the premaxilla and anteriors are not bound by either the labial bow or appliance acrylic, they feel none of this distal drive. As a result they stay in the same relative cephalometric position while the posterior segments of teeth and the appliance itself drifts distally
  117. 117.  The greatest amount of myotonic tension exists during the first 3 months. The appliance is worn before the muscles and mandible have repositioned themselves, the labial bow is usually kept off of the front teeth at this time to take full advantage of the distallizing forces made available to push the maxillary posterior segments.  In the fourth month it is adjusted to contact, to assist in the rotation of the teeth and bone to a more conventional arch form.
  118. 118. How made
  119. 119.  The coffin spring- Shaped like the greek letter Omege, introduced into orthodontics around in 1880, it serves three main functions to the activator.  First, it acts as a tongue trainer, helps correct the deviant swallowing pattern and tongue thrust by causing the base of tongue to seal itself against the soft palate during swallowing and thus prevented the tip of the tongue from scamming up against the lingual surfaces of the anterior teeth and the premaxillary rugae area.
  120. 120.  Secondly, the coffin spring can be used .as an active component in moving the buccal posterior segments laterally.  Thirdly, for entirely practical reasons the coffin spring is great for giving the appliance strength, durability and stability in the mouth.
  121. 121. How made
  122. 122. FABRICATION OF THE ACRYLIC PORTION  The appliance consists of upper, lower and interocclusal parts. The dental and gingival portions can be differentiated in lower.  If the construction bite is high, the extension of the flanges is greater than for as horizontal type of activator, which positions the mandible more anteriorly.
  123. 123.  This extension is important to enhance the retention of the appliance, particularly for the vertical activator, because the patients habitually have an open mouth posture.  The flanges for the upper part are 8-12 mm high in the gingival area, covering the alveolar crest.  If the acrylic part is thin in the palatal region, it may cause too much appliance flexibility. To increase the rigidity a palatal bar can be used.
  124. 124.  The lower acrylic plate is 5-10 mm wide in the molar area. It is sometimes greater with flanges 10-15 mm.  After the appliance has been carefully checked for proper fit in the mouth, an exact plan of needed tooth movement is developed. Approximate trimming can be done on plaster casts. However, the final grinding must be done in the mouth.
  125. 125.  Any undercoat acrylic surfaces that might interfere with the planned tooth guidance must be removed This potential problem can be checked with an explorer or visualized by checking the shadows created on the acrylic by undercut surfaces.
  126. 126.  Since there is always a bit of adjustment and to be expected while the appliance is worn during the first couple of weeks, the final trimming is not done until the second visit in most cases to achieve the best possible efficiency.  The acrylic areas that contact the teeth are likely to become polished & thus area of force delivery can be well identified. Then careful grinding can be done.
  127. 127. PRINCIPLE OF THERAPEUTIC TRIMMING FOR TOOTH GUIDANCE  Selective guidance of the eruption of teeth and development of arch form is necessary in addition to the elimination of all possible functional retrusive muscle activity and attempts to get the best possible condylar growth adaptation to the more correct sagittal relationship.
  128. 128.  The aim of trimming is to achieve a loosely fitting appliance that patient can yet manipulate the one that maintains the sagittal relationship while stimulating or restricting selective eruption and movement of anterior and posterior teeth.  The acrylic transmit the desired intermittent force and contact. The teeth are called guiding planes. The magnitude of force is determined by the amount of actual acrylic contacting the tooth surface.  Larger the contacting surface lesser is the force delivered.
  129. 129.  Trimming in to control tooth movement in 3 planes of space-  Vertical  Transverse  sagittal
  130. 130. Advantages  Forces employed are physiological and produce no damage to teeth or supporting tissues.  Intervals between adjustments are less (6.8 wks).  Minimum hygiene tissue oral problems, minimum irritation and damage.  Appliance worn at night.  Appointments are brief.  Uses existing growth of the jaws to the maximum.  Provides in excellent control vertical direction particularly overclosure.
  131. 131.  Useful in correction of malocclusions associated with habits Thumb sucking, Tongue thrusting.  After treatment appliance, itself acts as a retainer saving cost & professional time.  Cost factor is low.
  132. 132. DISADVANTAGES  Careful case selection.  No detailed precise finishing of occlusion.  Full reliance on patient for successful treatment.
  133. 133. Biological effects of appliance in corrections class-II division-l malocclusion  Following findings by McNamara, Moyers into 6 categories: 1. Remodelling of mandibular condyle -  Adaptive changes in 3 general layers of condylar cartilage.  Surface changes at anterior aspect of posterior glenoid fossa.
  134. 134. 2 Retardation or redirection of horizontal maxilla growth- Basal area of maxilla are retarded in their normal forward development. 3. Mandibular rotation- Increased height of mandibular alveolar process and variable degree of rate of eruption of teeth in buccal segment resulting in backward rotation of mandible.  This may be compensated by vertical growth of condyles at a later age. An increase of LAFH is inevitable.
  135. 135. 4. Dental arch changes –  Distal migration of maxillary molars.  Mesial migration of mandibular molars. 5. Altered eruption of teeth in buccal segments- vertical eruption of maxillary posterior teeth inhibited. Eruption of antagonist take place can undisturbed and free of occlusal imbalances.
  136. 136. 6. Incisor tipping  Immediate to anterior displacement of response mandible occurs within dental arch - incisor region.  Average activator treatment  Initially - dental changes predominate  Later - Increase in SNB, Decrease in SNA, skeletal effect.
  137. 137. Modifications of activator
  138. 138. ANDRESEN-HAUPL ACTIVATOR  As already mentioned the term activator was coined jointly by Andersen and Haupl in their textbook "Functions Keifer orthopedic" published in 1936.  Hence the first activator is known as "Andresen Haupl activator ".  The original appliance combined an upper and lower plate of the occlusal level and was made vulacanite rubber.  Only one wire element was used – a maxillary labial bow made of -0.8 to 0.9mm SS wire. The appliance had to be remade several times to complete the treatment. For expansion the appliance was split in the centre and a flexible coffin spring was incorporated.
  139. 139.  Later the body was replaced by acrylic and the labial bow incorporated was with two U- loops in the canine regions with the retaining arm passing through canine and 1st deciduous molar or 1st premolar. The labial bow could be active or passive.  Later when Andresen and Haupl incorporated with Petrik and published the fifth edition of their back in 1957 many additional wire elements were described.
  140. 140.  Several modifications have been done thereafter which will be discussed later.
  141. 141. Harvold Woodside activator  The initially small inter-occlusal distance with a construction bite was increased in subsequent edition of the Andersen-Haupl text. The vertical displacement of the mandible was increased first in order to prevent the loss of appliance during sleep in some cases. When Petrik got involved in the team the, myodynamic appliance of Andersen & Haupl became myotonic appliance. Importance of the change over escaped attention until it was pointed out by Slagsvold.
  142. 142.  Important aspects of Harvold-Woodside activator - 1. Vertical construction bite: Harvold in 1971 originated the idea of using viscoelastic properties of the muscles and soft tissues as force generators. He places the mandible approximately 3mm distal to the most protrusive position that the patient is able to achieve whereas vertically an extreme separation of the jaws is used so that the mandible maybe opened 8 - 10 mm beyond the free way space. Woodside uses vertical separation of approximately 12mm - 15mm beyond the daytime rest position of the mandible.
  143. 143. The proponents of this concept contend that the use of myotatic reflex along with attempts to increase the frequency of biting and swallowing should be largely ignored, letting passive tension (vjscoelastic properties) in the stretched labial and oral musculature deliver the primary force to the appliance. Thus the power to produce alveolar remodeling is obtained from the inherent elasticity of muscles, tendinous tissues and skin without motor stimulation. This is mediated through clasp knife or autogenic inhibition reflex.
  144. 144. 2. Functional occlusal plane and use of differential control of teeth eruption –  If there is minimal eruption of the maxillary posterior teeth and over eruption of the mandibular posterior teeth there will be a distinct tendency for the establishment of a Class III MO or the functional occlusal plane established itself at a higher level. Conversely, if there is a minimal eruption of the mandibular buccal segment and an over eruption of the maxillary buccal segments, the functional occlusal plane will be established at a lower level and the mesial component of the maxillary buccal segment eruption will be over emphasized. These changes may contribute to the establishment of Class II relationship.  In Class II activators Harvold Woodside used this principle of differential control of tooth eruption and allows eruption of mandibular posterior teeth.
  145. 145.  APPLIANCE:  Similar to Andersen Haupl activator with some differences -  Flanges: To further assist appliance in position during sleep, the mandibular flanges extended deeply lingual to the molars to condition the patient to retain the activator in the mouth. If an attempt is made to remove it with tongue, the deep flanges will rub on the under cut surfaces of the mucoperiosteum and irritate the tissues. The patient quickly learns that this discomfort can be avoided by biting firmly into the appliance. The under cut lingual flanges are therefore another conditioning device.
  146. 146.  Labial arch wire:  The labial arch wire is made of 0.9 cm SS round wire. The labial arches are commonly of two designs.  a. Hawley retainer type.  b. Andresen type.  A modified Andresen design is used when there has been considerable narrowing of the maxillary arch in the canine region resulting from muscle contracture force. This design release the force of the cheeks from themaxillary canine area and permits normal arch formed to be restored.
  147. 147.  Dislodging Springs: Heavy gauge dislodging springs are placed passively against maxillary 1st permanent molars and are adjusted distally 05. mm.-They are not intended to move the molars distally but are intended to create a dislodging action within the appliance. Such action helps pt. to bite into the appliance to keep it in position. For this reason the dislodging springs act as additional activators of the muscle of mastication. They also provide friction against the mesial surface of the maxillary first molar and in the activators in which the acrylic has been trimmed occlusally in the maxillary buccal segments; they tend to prevent its eruption. Thus dislodging springs may assist in the correct manipulation of the functional occlusal plane.
  148. 148. Herren’s activator  Herren was disappointed by low success rate of Andresen - Haupl- Petrik activator, which was less that 50%.  While observing patients wearing activator at night and watching his own musculature while using the activator he realized that the activator acted only like a passive splint at night. Herren's research cleared up the mystique about active jaw movements that the appliance supposedly elicited at night.
  149. 149.  The Herren or LSU activator of Robert Shyae is as such modified as follows:-  1. Overcompensating construction bite for the positioning of the mandible.  2. Upper molar clasps, which secures a positive splinting effect during the whole night.
  150. 150.  Modus Operandi - 1. Any inert activator acts like a splint. It is a "myotonic appliance", to use the term rightfully coined by Graber. In class II, malocclusion, the construction bite of Herren activator dislocates the mandible forward by a total of 8mm or more. When a child inserts the activator the mandible is purposefully carried forward until it is possible to bite completely into the positioning splint. The mandibular teeth then fit comfortably in the inert appliance which braces the incisors and canines as well as the lingual surfaces of the posterior teeth.
  151. 151.  The lower dental arch is supported against the pull of the stretched retractor muscles. The mandible is kept from being retracted because the activator take the load of these forces and transmit them in an occlusal direction to the maxillary dental arch. Since action equal reaction, a force of equal magnitude and opposite direction acts against the mandibular dental arch.
  152. 152.  According to Graf, an average of 100N of force was measured for every millimeter of mandibular forward shift. When mandible is displaced forward by 8 mm, around 300g of force is generated.  The activator holds the retractive musculature of the mandible " passively stretched. In contrast the protractors are slackened.  Auf der Maur - found that two patients who were wearing a Herren activator showed no electromyographic activity within the lateral pterygoid muscle.
  153. 153. 2. Although forces are generated in a transverse direction but not sufficient to cause expansion. Hence an expansion screw may be used. 3. Moreover, the activator, inserted between the teeth and tongue, act as a shield that keeps the tongue away from the free way space, which enables the eruption of the tooth, provided that the acrylic occlusal stops of posterior teeth are ground away from the appliance. It should be kept in mind that this effect lasts for only about 9 hours of sleeping time and might be counteracted by strong occlusal forces during day time.
  154. 154.  Construction Bite 1. Positioning the mandible in sagittal direction dominates over the vertical direction 2. Anterior positioning: - From the post normal distoocclusion the mandible is carried forward not only to class I molar relation but also an additional 3 mm to 4mm beyond neutro occlusion. 3. Vertical positioning: -In deep bite cases, the incisor edges are kept 2-4mm apart to allow sufficient amount of acrylic to be present between incisors. This allows removal of acrylic along the lingual surfaces of Maxillary when needed. Therefore the posterior vertical opening depends upon the amount of anterior overbite. The vertical interocclusal distance in deep overbite totals the amount of overbite plus 2 to 4
  155. 155.  In an open bite, the incisor relationship furnishes no indicator for the vertical thickness of the construction bite. In such instances, the interocclusal distance between upper and lower molars is decisive (4mm to 6mm). Thus, the wax bite keeps the mandible constantly open beyond the rest position in the sleeping patient.
  156. 156.  In Class II mesiocclusions without midline deviation, care must be taken that upper and lower dental arch, midline coincide in the construction bite. When properly taken, the over compensating construction bite it class II, Div I mesiocclusions often brings the incisors into an edge to edge & when the upper incisiors are not markedly relationship and occasionally proclined, even beyond. In class II Div 2 Malocclusions the incisal edge relationship may approach an anterior cross- bite while the construction bite is taken.
  157. 157.  Peculiar feature of Herren's Activator:  Retention of activator by arrow head & Jackson or Duyzings clasps - Herren argues that different position of mandible during sleep will not allow activator to be retained in its place hence; he advocates use of clasps to its retention.  Incorporation of Expansion Screw- In the majority of patients a midline expansion of the maxillary dental arch is required to obtain a normal buccolingual occlusal relationship between the dental arches when positioning the mandible forward into the desired class I relationship. An expansion screw, placed in the palatal vault at the level of the first premolars and activated by the patient (90 degrees as a quarter terms every second week), will correct the transverse arch width discrepancy.
  158. 158. 3. In all activators, the horizontal arches of the clasps and labial bows should be inserted into the middle of the interocclusal distance and not too close to the lingual surface of the teeth. In contrast, the active pallets may cross closely over contact points. 4. Use of Springs:- Moderate irregulations in the alignment of the maxillary- incisors can be corrected by the use of springs while the postnormal occlusal is being treated. Since the appliance is firmly seated on the upper teeth, these springs act efficiently, as in active plats.
  159. 159. 5. Restriction of mandibular mobility:- Mobility of the mandible is restricted by extending the lingual flanges of the activation as for as possible toward the floor of the mouth. These flanges guide the mandibular dental arch in its path to the proper position in the splint. Hence in taking the impressions, special attention must be given to a faithful reproduction of the depth of the posterior part of the alveolar processes. In the laboratory undercuts resulting from the lingual inclination of the alveolar processes are leveled with the application of wax before the flange are fabricated. If the flange prevents the sitting of the activator, their transverse width is reduced but never the depth.
  160. 160.  Treatment of class III- In case of class III malocclusion, activator therapy is recommended only when the orthodontist can guide the child's mandible from anterior cross bite into an edge-to-edge relationship. In the most retruded position of the mandible, the construction bite is taken with the incisal edges 2 or 3mm from each other.
  161. 161.  The activator acts simultaneously in 3 ways:-  holding the mandible back, splinting in the maxillary dental arch  tipping the maxillary incisors in a labial direction and  inducing a more anterior relationship of the maxillary dental arch to the mandibular dental arch.
  162. 162.  Potentiality of Herren activator - 1. To correct the class II malocclusion in an expedient, reliable and economic way. 2. To retard forward growth of maxilla. 3. To reposition the mandible during mandibular growth, either in horizontal or in vertical direction. 4. To archive these permanence in the mixed as well as early permanent dentition. 5. To provide a high rate of stability of the treatment results.
  163. 163. “H” activator (GRABER & NEWMANN)  Constructed with a low vertical opening registration and forward bite registration (atleast 3 mm posterior to the most protrusive positioning possible) .  Myotatic reflex is activated.  Muscle force arising during biting and swallowing. Maxillary incisors can be uprighted and the anterior growth vector of the maxilla will be slightly inhibited.
  164. 164.  This type of appliance is most effective when an anterior sagittal relationship of the mandible is the primary treatment objective.  It is indicated in class-II division-l malocclusion with sufficient overjet with a) functional retrusion b) result of growth deficiency
  165. 165. “V” activator (GRABER & NEWMANN)  Mandible is positioned only 3-5 mm a head anteriorly to habitual rest position the vertical opening.  A maximum of 4 mm beyond the postural resting vertical dimension.
  166. 166.  Activation of myotatic reflex. Additional force is elicited with the stretching of the muscles and soft tissues causing a response of the viscoelastic properties of the soft tissues involved.  The frequency of maximal biting into the appliance is less than in the HI activator.  The stretch reflex activation with the increased vertical dimension may well influence the inclination of the maxillary base.
  167. 167.  This appliance is indicated in cases with vertical growth patterns and is properly designated as the vertical “V” activator.  Disadvantages - Dual bite is commonly observed.
  168. 168. THE BOW ACTIVATOR OF A.M. SCHWARZ  Consists of upper and lower halves of the bow activator connected with an elastic bow made up of 0.9 to1 mm wire. In the anterior area between the halves a layer of rubber is attached to act as a shock absorber and to open the bite in the jaw.  For the treatment of Class II Division 1 Malocclusion, a beginning can be made with a small forward positioning, increasing this gradually by periodic adjustments.  There is possibility of activating only the bow on the side of unilateral disto- occlusion.  Maxillary or mandibular expansion can be carried out with the incorporation of the expansion screws.  Drawbacks:  1. Appliance easily disturbed.  2. Results not up to the theoretical expectations.
  169. 169. U BOW ACTIVATOR OF KARWETZKY  Constructed quite similarly to the Schwarz bow activator, but with an improved technique and an apparently increased efficiency.  The KARWETZKY appliance consists of maxillary and mandibular active plates joined by a U bow in the region of first permanent molars.  The active plates, both maxillary and mandibular extend over the occlusal aspects of all teeth.  The height of the construction bite varies with the modifier [Herren, Schwarz, Demisch, Woodside, etc.].
  170. 170.  Depending on the placement of the ends of U bows three type of appliance: -  Type I - class II malocclusions, in which the short anterior leg in upper, the lower longer leg is placed posteriorly.  Type II For class III malocclusions, in which lower longer leg is placed anteriorly to shorter leg in upper leg in upper half.  Type III Influence in a transverse direction where there seems to be a displacement to one side or other, that is a facial asymmetry or lateral cross bite.
  171. 171.  KARWETZKY's appliance exerts a delicate influence on the dentition and on the-TMJ.  The mobility of the parts allows various mandibular movements which makes the activator more comfortable and tends to reinforce the functional stimuli.  The delicate forces, plus the gradual and sequential forward positioning of the lower jaw will avoid the exertion of undue pressure.  The KARWETZKY activator may be combined with the fixed appliances.  An exciting potential for the appliance is the possibility of use with certain types of orthognathic surgery in adults, particularly with corticotomies and subapical resections.
  172. 172. Reactivator  Modification developed by ROBERT SHAYE and positioner Laboratories. An anterior Jackscrew is incorporated in the acrylic to permit gradual advancement of the lower jaw in stages, instead of only one 6-7 mm of forward posturing as done by conventional activator techniques.
  173. 173.  This is in line with petrovic's research showing a more favorable and continuing tissue response to the new stimuli. This is more desirable from a cybernetic approach as well.  Histologic studies of the condylar response show improvement in the incremental and directional reaction to reactivating procedures. The superiority of this approach has been stressed by Rolf Frankel.
  174. 174. THE REDUCEDACTIVATOR OR CYBERNATOR OF SCHMUTH  Designed by Prof. G.P.F. Schmuth of Bonn. According to him it is an adaptation of the activation to use it in the simplest manner.  The acrylic part is removed in a similar manner to that of Bionator.  Has coffin spring made of 1.1 or 1.2mm wire for expansion & labial bow of regular activator to hold the upper lip.  Lower incisors are covered by acrylic to hold them in a stable position. .  Protrusion loops for upper anterior teeth.  A molar spur can be incorporated to prevent mesial drift of upper first molars.
  175. 175.  Although the edge to edge bite of the Bionator maybe used. Schmuth prefer the customary bite of the activator.  Full times wear except meals, spats or special occasion.  May be combined with fixed appliance of different kinds that can be worn simultaneously.  Even headgear tubes can be incorporated.
  176. 176. THE PROPULSOR  Conceived by "Mulhemann and refined by Hotz (1980).  Combination of Monoblock and Oral screen.  No wire configuration is used  As the oral screen covers the alveolar process, it not only transmits distal force to upper anterior teeth but also to the alveolar bone. Hence it suitable for maxillary dento-alveolar protrusion.  Construction bite:  Similar to activator but in a more forward position.
  177. 177.  Periodic modification: 1. Appliance is reactivated by adding acrylic to the area that contacts the upper anterior segment. 2. The acrylic between the occlusal surfaces of the first molars serves to stabilize the appliance when therapy is initiated. As treatment progresses however, this acrylic is removed progressively to allow for unhindered eruption of the molars and resultant reduction of the deep overbite if present.
  178. 178.  If selective eruption of the mandibular teeth is desired to reduce Class II buccal segment relationship by upward and forward eruption of the lower teeth while preventing forward eruption of the upper teeth, more acrylic can be removed opposing the lower molars leaving them free.
  179. 179. Elastic Open activators (EOA)  Daytime activators.  Designed by G. Klamnt from East Germany in 1960.  Klamnt, a disciple of Bimler, designed this appliance. Appliance was very fragile.  Combination of Activator and Bimler appliance.  The reduced size increased patient compliance.  It resembles Bionator as EOA has no acrylic anteriorly and with more wires. There is, however, a substantial difference. The Bionator, though freely movable in the oral cavity, is carefully stabilized on posterior occlusal surfaces or the lower incisors, as the occasion demands. The  EOA almost completely lacks such stabilization, and thus its vertical mobility is unimpeded.  It is a myodynamic appliance.
  180. 180.  Standard EOA consists of –  1. Bilateral acrylic parts.  2. An upper and lower labial wire  3. A palatal arch, and  4. Guiding wires.
  181. 181. Construction bite:  According to Klamnt, the construction bite is taken with the incisors into an edge to edge bite. According to him even with an overjet as large as 10 mm, it is possible to get the incisors into an edge to edge bite without any problem in TMJ. In event that an edge to edge bite can not be achieved, the mandible is brought into an intermediate position. During the progress of treatment, the appliance may then be modified to permit an edge to edge bite.  It is preferable, however, to make a new appliance for this purpose.
  182. 182. CUT OUT OR PALATE FREE ACTIVATOR  A modification of activator by Dr Klaws Metzelder in 1974.  It is an attempt to combine the advantages of the bionator with some of those of the original Andresen-Haupl activator.  In the maxillary portion, however, the acrylic covers only the palatal or lingual aspects of the buccal teeth and a small part of the adjoining gingiva. Thus, the palate remains free, making it easier for the patient to wear the appliance continuously.  The narrow anterior portion of the appliance is reinforced by a small screw if expansion is needed, otherwise a wire can be used for this purpose.  The labial wire (0.9 mm) is the same as that used with activator. There is no coffin spring.
  183. 183.  Stabilization is achieved by carrying the acrylic over the occlusal surfaces of some of the buccal teeth, or by a small rim of acrylic that forms a little groove for the mandibular incisal margins. Capping of lower incisors is necessary to prevent procumbancy.  The technique is essentially the same as described for the Bionator, and the choice among the different types of possibilities of treatment is made according to the principles established by Baiters.  Construction bite-  Preferably edge-to-edge.
  184. 184.  Advantages:  1. Easier to make.  2. Carries almost all the appurtenances described for the activator e.g. Jackscrew for expansion, Petric finger springs for moving individual teeth, springs for labial tipping of lower incisors etc.  3. The labial tipping of upper incisors can be done in a number of ways e.g. by addition of acrylic, use of springs.
  185. 185. Bimler Appliance  The first publication on Bimler appliance came in 1949. The original name was Gebbisformer (German). .  Basic appliance: Simple circular arrangement of an upper labial arch wire and a lower lingual wire, which were connected by two acrylic palatal wings and completed by a lower acrylic cap.
  186. 186.  Main characteristics:  Myodynamic appliance  Prefabricated wire components  Redoubling of U-Ioops : Provides mechanical stability& Allows dimensional and positional changes i.e lengthening and shortening, and raising and lowering & Screens check pressure  Prefabricated parts
  187. 187.  Appliances types:  Based on Incisor Classification- 1. Protrusive Incisors -Type A appliance 2. Retrusive incisors - Type B appliance 3. Reversed Incisors - type C appliance
  188. 188.  Six variations in each type: 1. Variation 1: Standard -More or less normal arches with only minor occurrence of crowding. 2. Variation 2:Special-lnterdental springs designed to perform special task 3. Variation 3: Hypo - Indicated in midface deficiency with uni or bilateral open -bite. 4. Variation 4: Extra - Severe crowding requiring 1stpremolar extraction 5. Variation 5: Contra - Telescopic bite. 6. Variation 6: Bipro - Bimaxillary dental protrusion
  189. 189. Thank you For more details please visit