Growth modification and head gears


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Growth modification and head gears

  1. 1. Dr. Rashid Mahmood
  2. 2. DiscrepanciesSkeletalDentalSoft-tissues
  3. 3. Three dimensions ↔Transverse →Sagittal ↕Vertical
  4. 4. Transverse Discrepancies
  5. 5. Vertical Discrepancies
  6. 6. Sagittal Discrepancies
  7. 7. Sagittal Discrepancies
  8. 8. Sagittal Discrepancies
  9. 9. In Orthodontics
  10. 10. Definition: Removable or fixed orthodontic appliances which use forces generated by the stretching of muscles, fascia and / or Peridontium to alter skeletal and dental relationships.
  11. 11. Form follows function
  12. 12. Form follows function
  13. 13. “If compensatory, adaptive lip and tongue function could exacerbate excessive over-jet in class II-type malocclusions and if abnormal swallowing and prolonged finger- sucking habits could create anterioropen-bite and narrow maxillary arches,could not the same muscles be used to correct these and other problem????”
  14. 14. Background Functional appliances are conceptually based on Moss’ functional matrix theory Functional matrix theory proposes that functional matrices, tissues like muscles and glands influence skeletal units such as jaw bones and ultimately control their growth
  15. 15. The appliances used to improve functional relationship of dento-facial structures by eliminating unfavorable developmental factors andimproving the neuromuscular environment enveloping the developing occlusion
  16. 16. Function Muscular ActionEffect on dento-alveolar development
  17. 17. What they do…..? Alter the neuromuscular environment of oro-facial region to improve occlusal development and/or craniofacial skeletal growth Utilize muscle forces to effect bony and dental changes Disarticulate the teeth Encourage new mandibular position Require a tight lip seal during swallowing Selectively alter the eruptive path of teeth
  18. 18. When???
  19. 19. When??? Functional appliance treatment should be started before the pubertal growth spurt This is the time when the mandible may exhibit increased growth which may be influenced Duration---------------------------10-12 hours a day These appliances should be worn at night-time as this is when growth takes place
  20. 20. INDICATIONS1. Growing ages (Mixed dentition and/or early permanent dentition)2. Skeletal Considerations (Sagital correction of class II &III) Skeletal Class II with Short mandible a) Class II division 1 b) Class II division 2 (Convert div 2 to div 1)1. Vertical Considerations a) Normal to low angle cases2. Dental Considerations a) Local irregularity & rotation of incisors especially upper incisors b) Crowding or dental compensation (Pre-functional Orthodontics require3. Open bite/ deep bite correction4. Cross bite correction5. To correct mal-forming dysfunction
  21. 21. CONTRAINDICATIONS1. Children with neuromuscular disorders a. Poliomyelitis b. Cerebral palsy2. Compliance3. Hyperdivegent faces4. Unfavorable growth5. Protruded lower incisors6. Severe crowding7. Age
  22. 22. Treatment Principles Force Application: Compressive stress and strain act on the structures involved resulting in primary alteration in form and secondary adaptation in function e.g all removable appliances Force Elimination: Abnormal and destructive environmental influences are eliminated to allow optimum development like lip bumpers and frankel buccal sheilds
  23. 23. Mode of Action Functional Appliances influence facial skeleton through condylar and sutural areas. Goal is to  Use the functional stimulus of oro-facial muscles , channeling this stimulus to the jaws, condyles and teeth to bring the change.  Purely functional and intermittent forces
  24. 24. Limitations Adult Age(Ineffective in adults) High Angle Cases(Increases vertical height of patient) Compliance Precise detailing of tooth position not possible Crowding (Cases with ALD are difficult to manage) Precise correction of Incisor inclination not possible Increased lower incisor inclination (They tend to increase lower incisor inclination & thus proper Sagital correction may not be possible if not properly managed)
  25. 25. Functional appliances if used properly & at right time then they help in improving theprofile and eliminating the need for Orthognathic Surgery
  26. 26. TYPESActivePassive
  27. 27.  Active appliances reposition the mandible so that the condyle is forced out of the glenoid fossa and this in turn is thought to stimulate the posterior/superior growth of the condyle. Passive appliances act by repositioning the musculature associated with the mandible so that the jaw bone itself responds by growing to the new equilibrium position
  30. 30. TYPESTooth BorneTissue Borne
  31. 31. Simple functional appliances Can be used for both mand and maxilla Uses the muscular force from upper or lower lip to provide distal Lip bumper force specially to molars In lower arch headgear is less acceptable so lip bumper is useful Remove soft tissues forces from labial aspect Result increased lower incisor inclination by influence of tongue This can be reduced by placing it as low as possible in labial sulcus so that upper part of lip is in contact with teeth
  32. 32. Simple functional appliancesOral screens Forerunner of functional regulator Consists of vestibular shields which holds the lip away from all teeth except upper incisors b/c pressure from lips is transferred to U I and acts to move them palatally Can be used in mixed dentition and aids patient with digit sucking
  33. 33. Jaw Orthopedic FunctionalAppliances Removable Functional Appliances  TOOTH BORN  MONOBLOCK  ACTIVATORS  BIONATORS  TWIN BLOCKS  MAGNETIC APPLIANCE  TISSUE BORN  FRANKEL FUNCTIONAL APPLIANCE Fixed Functional Appliances  Flexible Fixed Functional Appliances (FFFA)  Rigid Fixed Functional Appliances (RFFA)  Hybrid Appliance  Fixed version of RFA (fixed twin block , dynamix appliance)  Elastics
  34. 34. TYPES MYOTONIC  Depend upon displacement of mandible in AP and vertical plane. e.g Activators MYODYNAMIC  Not only translate the mandible AP & vertically but also attempt to utilize and translate muscular movements e.g Bimler appliance
  35. 35. Passive functional appliances Frankel
  36. 36. Active functional appliances Removable active functional appliances  Bionator
  37. 37. Active functional appliances Removable active functional appliances  activator
  38. 38. Active functional appliances Removable active functional appliances  Twin-block appliance
  39. 39. Active functional appliances Fixed active functional appliances  Herbst
  40. 40. Andresen Activator Viggo Andersen Mono-block  As upper and lower plates appear joined together Activator Norwegian appliance
  41. 41. Modified Andresen–Häupl-type activator Class II cases Div I For better control of lower incisor inclination, the lower incisors are covered with acrylic, which is relieved on the lingual surface Correct overjet, overbite and molar relationship during active growth Labial bow to prevent incisors proclination Maximum extension of lower lingual flanges in order to redistribute the force on mucoperiostium of mandible Coffin spring instead of palatal plate Canine loops ----- screening loops of bionator and buccal shields of FR.
  42. 42. Limitations Difficulty in speech Needs removal during eating Arch expansion cannot be carried out simultaneously
  43. 43. AndresenLabial view of the Andresen appliance. The picture shows labial Bow in0.8mm S.S wire with tubing and lower incisal capping.
  44. 44. AndresenModels removed
  45. 45. AndresenLingual or palatal view
  46. 46. AndresenBuccal Views
  48. 48. Dr. Rolf Frankel Passive functional appliance Essentially tissue borne Appliance of choice in class II due to mandibular retrusion.FRANKEL APPLIANCE Used in early mix dentition. Has direct effect on neuromuscular system.FRANKEL CORRECTOR Causes anterior advancement of mandible and increase in LAFH. Expands dental arches.FUNCTIONAL REGULATOR
  49. 49. FUNCTIONAL REGULATOR Oral vestibule is used as operational basis for the treatment of dentoalveolar discrepancies. It combines the principles of Anderson’s appliance and oral screen. Mode of action depends upon the relieving and lifting the pressure on teeth from lips and cheeks, so that the jaws can be allowed to grow and the teeth can be guided to move into new more favorable position.
  50. 50. Frankel ApplianceThe wire assembly anchors the appliance onthe maxillary arch at the mesial embrasure ofthe of first molar.
  51. 51. FrankelApplianceRolf FrankelA cross palatalstabilizing wire on themaxillary arch.
  52. 52. FUNCTIONAL REGULATOR FR I a. Class I b. Class II div 1 <5mm c. Class II div 1 >7mm FR II Class II div 2 FR III Class III FR IV Open bite & mild bimax
  53. 53. FUNCTIONAL REGULATOR FR I a. Class I It is mainly used to treat cases of Class I malocclusion with minor to moderate crowding or arrested development of dental bases. It can also be used in class I malocclusion with deep bite.
  54. 54. FR I Appliance The components include: Upper • Palatal wire 6 / 6 in 0.9mm S.S wire. • Canine wires 3 / 3 in 0.9mm S.S wire. • Labial Bow 2 / 2 in 0.9mm S.S wire. Lower • Lip Pads and Joining wires in 0.9mm S.S wire. • Hanger wires 5 / 5 in 0.9mm S.S Labial view wire. • Lingual Pusher Springs 3 / 3 in 0.7mm S.S wire.
  55. 55. FR I Appliance Buccal view of the Frankel appliance.
  56. 56. FR I Appliance Frankel appliance - lingual / palatal view.
  57. 57. FR I ApplianceFrankel appliance with upper model removed.
  58. 58. FR I ApplianceFrankel appliance with lower model removed.
  59. 59. FUNCTIONAL REGULATOR FR I b. Class II div 1 where over-jet is <5mm c. Class II div 1 where the over-jet is >7mm
  60. 60. FUNCTIONAL REGULATOR FR II Class II div 2 Prior to the functional therapy the incisor need to be aligned
  61. 61. FR II Appliance1. Flexible Appliance2. The lingual and labial segments in lower portion encourage holding the mandible in a postured position to alter the lip behavior.3. By retraining the facial muscles & muscles of mastication to occupy new position.4. The maxilla & mandible will be influenced to grow into corrected position.5. Stretching of periosteum, osteoblastic activity & thus the bone formation. Labial Bow Palatal Arch Canine Clasps Buccal Shields Occlusal Rests Labial Pads
  62. 62. FUNCTIONAL REGULATOR FR III Class III Mild Class III casesThe correction of class III Malocclusion is by dento-alveolar means, not because of skeletal growth modification
  63. 63. Registration of Bite Varies with the type used. Move mandible forward by 4 – 6 mm. Or edge to edge contact of incisors 2.5 to 3.5 occlusal clearance. Correction of sagittal discrepancy in 2 or 3 stages. 3 dimensional effect of FR
  64. 64. Bionator 1.Light Appliance 2.Better Compliance 3.Full Time WearTiming for Bionator Therapy Effective and stable when it is initiated immediately before the pubertal growth spurt. Optimal timing to start treatment with the Bionator is when a concavity is evident at the lower borders of both the second and the third cervical vertebrae (CVMS II). In the long term, the amount of significant supplementary elongation of the mandible in subjects treated with the Bionator during the pubertal growth spurt is 5.1 mm more than that in untreated subjects with class-II malocclusion. Significant increments in mandibular ramus height and for a significantly more backward direction of condylar growth.
  65. 65. • Used in mix dentition.• Major indication is in extremely deep bite.• Used to bring mandible in forward position and to increase LAFH by eruption of posterior teeth…California Bionator.• Can be used to close bite and maintaining bite.• Protusion springs may be used in class II div2
  66. 66. Labial BowBionatorFacets in the acrylicwhich accepts maxillary& mandibular teeth &hold them in posturedposition Palatal spring (Reverse coffin spring) Lingual horseshoe of acrylic
  67. 67. Twin Block Indications Class II div 1 Distal molar and canine relationship of at least half premolar width Overjet more than or equal to 5mm Protrusion of maxillary incisors Class II skelatal type ANB≥ 4 Occlusal development ..late mixed dentition or early permanenet dentition Normal & low angle cases
  68. 68. Effects of twin block Skeletal effects: mandibular length increses,during 1 yr, restrains maxilla Dentoalveolar change: upper incisors tip back Lower incisors move forward Overjet reduction.,.(correction achieved by skelatal and dentoalveolar reduction Correction of buccal segment achieved by combination of distal movement of upper molars &forward movement lower molars ANB reduction Increased vertical dimensions..(inc lower facial height)mandibular plane angle increases Reduction of facial convexity
  69. 69. Contraindications TMJ problems Sk assymetries Syndromic pts
  70. 70. ClarK 1988 Twin Block In Function Adams Clasp Labial Bow Inclined PlaneModifiedAdams Clasp Bite block Inclined Plane Expansion Screw Bite block
  71. 71. “where there is a will there is a way”
  72. 72. Chapter 13
  73. 73. Jaw Orthopedic FunctionalAppliances Removable Functional Appliances  TOOTH BORN  MONOBLOCK  ACTIVATORS  BIONATORS  TWIN BLOCKS  MAGNETIC APPLIANCE  TISSUE BORN  FRANKEL FUNCTIONAL APPLIANCE Fixed Functional Appliances  Flexible Fixed Functional Appliances (FFFA)  Rigid Fixed Functional Appliances (RFFA)  Hybrid Appliance  Fixed version of RFA (fixed twin block , dynamix appliance)  Elastics
  74. 74. • Fixed functional.• should be used in permanent dentition.• Easily tolerated by the patient.• Should be changed after some time .
  75. 75. Fixed Functional AppliancesAdvantages Continuous stimulus for mandibular growth (24 hr use) They are smaller in size permitting better adaptation to functions such as a mastication, swallowing, speech and breathing. Non-compliance Class II devices, which are able to treat Class II malocclusions successfully, while reducing the need for patient co-operation and overall treatment time. Allows greater control by the orthodontist.Disadvantages Application of force is transmitted directly to the teeth through a support system, the main disadvantage that may be encountered is dental movement that takes place during treatment
  76. 76. APPLIANCE DISCRIPTION Can be compared to the artificial joint between maxilla & mandible. A bilateral telescopic mechanism keeps the mandible in continuous anterior position. Appliance consists of a tube to which plunger fits. Tube is fixed to the distal end of maxillary molars & rod into the lower first premolars.
  77. 77. Herbst Appliance The Herbst appliance consists of two tubes, two plungers, axles and screws Type I is characterized by a fixing system to the crowns or bands through the use of screws. It is necessary to weld the axles to the bands or crowns and then fix the tubes and plungers with the screws Type II has a fixing system that fits directly onto the archwires through the use of screws Disadvantage is the fracture of archwires Type III is for anchorage Type IV has a fixation system with a ball attachment, which allows greater flexibility and freedom of mandibular movement. Disadvantage in relation to other similar appliances is that it needs brakes to stabilize the joint. The brakes are small and sometime difficult to fit. When a fracture occurs or a brake is lost, the appliance comes loose
  78. 78. FFF-ApplianceJasper Jumper
  79. 79. Jasper Jumper Herbst Appliance
  80. 80. Indicationsof FFFA Class I (An anchorage reinforcement) Class II division 1 and 2 Class III malocclusions Molar distalization Midline discrepancy
  81. 81. Flexible Fixed Functional AppliancesInter-maxillary torsion coils, or fixed springs.Advantages Elasticity Flexibility Allow great freedom of movement of the mandible Lateral movements can be carried out with easeDisadvantages Fractures can occur both in the appliance itself (mainly in areas that have more acute angles) and in the support system (mainly in the lower arch) If on one hand flexibility is an advantage, on the other hand it does tend to produce fatigue in the springs Tendency of the patient to chew on the appliance, possibly contributing to breakage or damage. It is not possible for the patient to completely open his mouth, depending on the way the system is fixed onto the lower arch, good opening can be achieved. Expansive & replacement of broken parts adds cost Inventory Unhygienic but covering of springs make them hygienic
  82. 82. Mechanism of Action FFFAs allow the patient to close in centric relation When the patient closes in centric relation, the contour of the bow should be significantly increased By slightly overactivating the appliance in centric relation, the patient will automatically position the mandible forward. This is a natural response to decrease the force module and alleviate discomfort.
  83. 83. Clinical Relevance In brachyfacial cases, due to their strong musculature, it is necessary to use more force (greater activation) than in dolicofacial cases. If the patient has large cusps with good intercuspation, it will be necessary to exert greater activation on the spring. Greater force for orthopedic effects while lesser for dento-alveolar movements To maximize the dentoalveolar movements in the upper arch and minimize any loss of anchorage in the lower, the upper archwire is not tied back. It can be used to obtain maximum anchorage, holding upper molars back as the upper incisors are retracted.
  84. 84. Unwanted Effects Due to the intrusive force on the upper molars, a posterior open bite is common as well as posterior expansion due to the deflected force module. Tendency for the lower molar to rotate mesiobuccally, causing a mild posterior crossbite especially when the second molars have not been banded Proclination of lower incisors.. Not recommended in mixed dentition, especially late mixed dentition to avoid unwanted dental movements.
  85. 85. Jasper Jumper Intrusion and distalization of the upper molars, with occasional opening of the posterior bite similar to that seen with a Herbst ppliance. Some indication of condylar growth. Anterior migration of the mandibular teeth through alveolar bone. Intrusion of the lower incisors.
  86. 86. Advantage comfortable because of its covering.Disadvantages The large inventory that must be kept, the coating material may degrade Fractures
  87. 87. Contd. Canines can be retracted against mandibular dentition. As the force modules cause asymmetric forces, it can be used to treat dental asymmetries. Causes mandibular advancement and increase in LAFH. Can be used in post surgical stabilization of class II patients.
  88. 88. Indications. Dental Class II malocclusion. Skeletal Class II with maxillary excess as opposed to mandibular deficiency. Deep bite with retroclined mandibular incisors. Midline CorrectionContra-indications. Cases predisposed to root resorption. Dental and skeletal open bites. Vertical growth with high mandibular plane angle and excess lower facial height. Minimum buccal vestibular space.
  89. 89. Rigid Fixed Functional Appliances RFFAs do not easily fracture but neither do they have elasticity or flexibility. After fitting and activation they do not allow the patient to close in centric relation. This means that the mandible is in a forward position 24 hours a day creating greater stimulus for mandibular growth than with FFFAs. Skeletal effects produced with this type of appliance are greater than with FFFAs Mechanism of Action Telescopic mechanism which encourages forward repositioning of the lower jaw as the patient closes into occlusion
  90. 90. Indications. Dental Class II malocclusion due to retrognathic mandible Skeletal Class II mandibular deficiency. Deep bite with retroclined mandibular incisors. They can be used as an anterior repositioning splinting patient with TMJ disorders. Residual growth can be utilized in post adolescent patients. Can be used in mouth breathers.Contra-indications. Cases predisposed to root resorption. Dental and skeletal open bites. Vertical growth with high maxillomandibular plane angle and excess lower facial height.
  91. 91. TYPES OF APPLIANCE Bonded herbst (High Angle Cases) Banded herbs Flip locked herbst Crowned herbst
  92. 92. The Flip-Lock Herbst Appliance Reduced number of moving parts that can lead to breakage or failure. Easy to use Comfortable Instead of a screw attachment, it has a ball-joint connector so it needs no retaining springs. Less chairside time activation
  93. 93. Bonded Herbst Appliance It is a wire reinfofced acrylic splint. The pivots are fixed to the wire framework at distobuucal aspect High Angle Cases of the upper first molar mesial aspect of lower first premolar. Tube is fitted to the pivot in the upper molars & shaft is fixed to mandibular premolar region
  94. 94. BANDED HERBST Upper & lower first premolar & first molars are banded.the tubes are fixed to pivots soldered to distobuccal aspect upper first molars. The shaft or rods are fixed to pivots soldered to lower first premolar band.
  96. 96. Hybrid Functional Appliances Hybrid appliances are specifically and individually tailored to exploit the natural processes of growth and development. These appliances blend several components designed to address specific problems
  97. 97. Asymmetric mandibular deficiency or facial asymmetry in children
  98. 98. Condylar fracture
  99. 99. Fixed Version Of RFA • Dynamax Appliance • Fixed Twin Block • Magnetic Appliances • Elastics
  100. 100. Fixed version of RFA Clip-on Fixed Functional ApplianceAdvantages of the Appliance Patient co-operation is not required. It works for 24 hours a day. A full fixed appliance can be placed at the same time as the Class II correction is being carried out. Treatment time is short because of full time wear. There is no transitional phase between functional phase and the fixed phase so treatment time reduced. Overlap of the functional and fixed phase further reduces treatment time. It is less bulky than other functional appliances.
  101. 101. Fixed version of RFAJO March 2001 Clip-on Fixed FA Occlusal blocks with lingual tube attachments Inclined Planes Occlusal blocks with palatal tube attachments.
  102. 102. Disadvantages of the Appliance Breakage of the Appliance Construction of the Appliance . Oral Hygiene Problems Airways ClearanceClip-on Fixed Functional ApplianceThe results showed that this appliance was effective in correcting Class II malocclusion; the noncompliance rate was only 6%
  103. 103. Extra-oral forceDento-facial orthopedics
  104. 104. Head Gears Orthopedic appliance that control growth of facial structures Various designs. Used with growing patients.
  105. 105. USES OF HEAD GEAR CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH ;(excess growth of maxilla/deficient growth of mandible) Head gear restrain the forward and downward growth of maxilla by holding back the growth of upper jaw, allowing the lower jaw to catch up and thus the correction of class II. MOLAR DISTILIZATION. head gear may be used to distalize maxillary molar to correct the class II molar relation ship or to gain space for relief of crowding. AS AN ANCHORAGE In some situations ,to maintain the bite, the orthodontist will not want the back teeth to come forward. The headgear serves to hold them back to maintain anchorage.
  106. 106. USES OF HEAD GEAR REINFORCEMENT OF ANCHORAGE. head gear can be used to reinforce anchorage in high anchorage cases. MOLAR ROTATION. can also be brought about with the inner bow of headgear. CORRECTION OF SKELETAL CLASS III. (deficient growth of maxilla/excess growth of mandible).; by protraction or reverse pull head gear that causes the anterior displacement of maxilla.
  107. 107. CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH ;(excess growth of maxilla/deficient growth of mandible)
  108. 108. CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH ;(excess growth of maxilla/deficient growth of mandible)
  110. 110. TYPES OF HEAD GEAR  High pull  Cervical pull  Combination pull  Reverse pull  Asymmetric Head Gear
  111. 111. TYPES OF HEAD GEAR
  112. 112. TYPES OF HEADGEARHigh pull Cervical Pull Combination Reverse pull pull Asymmetric headgear
  113. 113. COMPONENTS PARTS OF HAEDGEAR. Face bows; ( Inner and outer bow). Release modules. Straps or cushions. Other items.
  114. 114. FACE BOW STYLES. KLOEHN Regular Cushion Loop J-HOOK ASHER BITE PLATE
  115. 115. FACEBOW STYLES Kloehn style Bite plateCushion loop Asher facebow J -hook
  117. 117. BIOMECHANICS OF HEADGEAR The relation ship of line of action of force to the center of resistance of maxilla or first molar determines whether translation (bodily )or rotation (tipping) takes place. When a force does not pass through the center of resistance of the maxilla/molar, A moment is produced. The direction of line of force can be changed by adjusting the length and position of outer bow.
  118. 118. High Pull Head Gear Bodily movement of molar (no tipping) when line of force is passing through the center of resistance of molar. Both backward and upward movement of molar. When line of force is above CR --- mesial tip of crown and distal tip of root. When line of force is below CR --- mesial tip of root and distal tip of crown.
  119. 119. Low Pull/Cervical Head Gear Bodily movement of molar (no tipping) when line of force is passing through the center of resistance of molar, as determined by the outer bow length and position Both backward and downward movements of molar. When line of force is above CR --- mesial tip of crown and distal tip of root. When line of force is below CR --- mesial tip of root and distal tip of crown. The outer bow is always longer than that used in High pull.
  120. 120. BIOMECHANICS OF HEAD GEAR Similar considerations apply to maxilla. Unless the line of force is through the center of resistance, rotation of maxilla occurs. Control of line of force is easier when face bow inserted into the splint covering all teeth. With all teeth splinted; it is possible to consider the maxilla as a unit and to relate the line of force to the center of resistance of maxilla.
  121. 121. RULE TO CHECK WHETHER THE LINE OF FORCE IS THROUGH THE CENTER OF RESISTANCE IN HIGH PULL AND CERVICAL PULL HEADGEAR In order to determine the proper position of outer bow. Use index finger to apply pressure in direction of head gear selected. A)In case of high pull headgear we move index finger below the outer bow, pushing up and back. As the finger is moved on the outer bow applying force. The bow will move up between the lips. B)In case of cervical pull headgear we move index finger above the outer bow, pushing down and back. As the finger is moved on the outer bow applying force. The bow will move down between the lips.
  122. 122. BIOMECHANICS OF HEADGEAR When the bow moves up, the roots of maxillary first molar will move distally.. When the bow moves down, the roots of maxillary first molar will move mesially and crown distally.. When the bow does not move. The force is through the center of resistance of the maxillary first molar and molar will move bodily and not rotate.
  123. 123. BIOMECHANICS OF HEAD GEAR EFFECT OF THE LENGTH OF OUTER BOW. The longer outer bow bend up and shorter bow bend down could produce the same line of force through the center of resistance of molar.
  124. 124. High Pull Head Gear Derives anchorage from parietal region. It produces intrusion and distalization of teeth. INDICATIONS. Open bite cases. High mandibular plane angle. Long face cases with an increase in lower anterior facial height.High pull headgear can be used as. HIGH PULL HEADGEAR TO MOLARS. HIGH PULL HEADGEAR TO MAXILLARY SPLINT HIGH PULL HEADGEAR TO FUNCTIONAL APPLIANCE.
  125. 125. CERVICAL HEAD GEAR The anchor unit in this head gear is nape of neck. It causes extrusion and distalization of molars along with distal movement of maxilla.Indications: short face,class II Anchorage conservation. early treatment of classII
  126. 126. Combination pull Headgear Derives anchorage from at least two regions ; the neck and occiput. It causes distal and slight superior force on maxilla and dentition.
  127. 127. Protraction head gear. The rationale for protraction headgear is to apply heavy force on the mid face in order to advance the maxilla anteriorly. In this type inner bow is bent to achieve distal insertion ,outer bow is modified to make hook in premolar region for elastic attachment. The center of resistance of mid face is difficult to locate but most studies shows it 5-10mm below the orbit.
  128. 128. Protraction head gear. A line of force closer to center of resistance of mid face will deliver a translatory force and line of force closer to occlusal plane has rotational force.
  129. 129. Petit Face Mask For the protraction of maxilla and maxillary dentoalveolar segments. developing Class III pattern. Cleft lip and palate patients. Extra-oral elastics (heavy)
  130. 130. Asymmetric head gear. Asymmetic force is achieved with a head gear by using an asymmetric outer bow,can be useful in regaining bilateral but asymmetric lost space.
  131. 131. Time, Duration and Force of HeadgearTherapy. FORCE. 500 TO 700gm(orthopedic )150- 200gm(orthodontic force). DURATION 12 -14hrs /Day, emphasis on wearing it from early morning. Treatment Duration. 12 TO 18 Months.
  132. 132. TREATMENT EFFECTSSKELETAL EFFECTS Frontomaxillary,zygomaticotemporal,zygomaticomaxil lary n pterygopalatine r most imp growth sites for development of maxilla. head gears act by compressing the sutures thus restricting the normal downward n fowad growth of maxilla.DENTAL EFFECTS Distalization of molars. Extrusion and intrusion of molars
  133. 133. SIDE EFFECTS OF HEAD GEAR Compensatory erruption of max And mand molars but can be controlled by fixed lingual arch. Distal tipping of max molars. Increased facial height.