Headgears /fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy


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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Headgears /fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy

  1. 1. HEADGEARS www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. Definition: A class of appliances characterised by the extroral positions of activating elements and supporting structure and having remotely located responsive force. www.indiandentalacademy.com
  4. 4. History:  More than 100 years ago Kingsley is reported to have used occipital anchorage during treatment. The "head cap" was described by Kingsley in 1866 and Farrar in the 1870's.  In 1907, Angle referred to extraoral anchorage and illustrated his occipital headgear and traction bar, which he replaced with “Baker’s anchorage”.  In seventh edition of his text, Angle described the use of extroral traction combined with extraction of upper premolars. www.indiandentalacademy.com
  5. 5. Kingsley’s headgear Angle’s headgear www.indiandentalacademy.com
  6. 6.  According to Breitner, in 1911 Oppenheim introduced the concept of center of rotation of a tooth as the point around which a tooth would rotate when a force was applied to the crown. Oppenheim also recognised that if a force could be arranged so that it passed through the center of rotation then a tooth, such as a molar would move bodily. www.indiandentalacademy.com
  7. 7.  Since such bodily movement does not involve tipping or rotation, the focal point for the force to produce the translatory movement has become known as the center of resistance.  Kloehn took up the use of extraoral traction following a publication by oppenheim in 1936 and must be given the credit for use of cervical traction as 1st phase in 2 phase treatment of class II and maxillary anterior crowding.  Phase I was concerned with distalising the maxillary I permanent molar before pubertal growth spurt. www.indiandentalacademy.com
  8. 8.  To translate molar distally, Kloehn advocated alternately tipping the molar crowns and roots. Distal crown tipping was produced by positioning the outer bow of the face bow below the center of resistance and distal root tipping by positioning the ends of the bow above the center of resistance.  Weber showed examples of extraoral traction designed to distalise mandibular teeth. Kloehn – type headgear www.indiandentalacademy.com
  9. 9.  Appliances resembling chin cups have been in use since the early 1800's. According to Graber, the early attempts with the chin cup were not successful because of incomplete knowledge of mandibular and facial growth, its use on nongrowing patients, and an inadequate understanding of the forces generated by the chin cup.  Armstrong applied 500 Gm. of force via chin cups on 100 adolescent patients with mandibular prognathism. He reported that half of his patients showed improvement in the Class III profile, whereas none of the control, nontreated patients showed any favorable change. www.indiandentalacademy.com
  10. 10.  Thilander treated sixty patients with chin cups for 1 to 6 years. A significant percentage of patients did not improve. The patients who showed improvement were comparatively young and showed favorable dental changes. The force generated by the chin cup in his study was only 150 to 200 Gm.  Graber, Chung, and Aoba reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 1.5 to 2 pounds on each side. They showed that mandibular growth could be redirected with a chin cup. They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results. www.indiandentalacademy.com
  11. 11.  Graber treated 35 Class III malocclusions in children between the ages of 5 and 8 years with chin cup therapy for 3 years. He found that the therapy was particularly effective in patients with increased vertical growth of the face.  Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups. Oppenheim suggested a technique for moving the maxilla forward. He noted that restriction of growth or distal movement of the mandible was impossible. www.indiandentalacademy.com
  12. 12.  Kettle and Burhapp reported an appliance for cleft lip and palate which successfully inhibited forward growth of the mandible and simultaneously caused anterior movement of the maxilla.  Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet. Haas showed downward and forward movement of the maxilla as a result of palatal expansion. The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance.  Delaire, Verdon, and Floor have extensively used a facial mask to protract the maxilla anteriorly. Elastics generating forces of 1,000 to 2,000 Gm. are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly. www.indiandentalacademy.com
  13. 13. Types Of Headgear  According to the means of attachment to teeth 1) Using face - bow, which slots into tubes soldered onto the bridge of a removable appliance crib or tubes which form an integral part of a band attachment or tubes which are incorporated in the design of a functional appliance. The face – bow is an inner – outer bow. Inner bow is available either in 0.045” or 0.051” depending on the size of headgear tube. Outer bow is usually 0.072” 2) J – hooks which can be directly attached onto the arch wire in a fixed appliance or attached to hooks soldered onto the labial bow of a removable appliance. www.indiandentalacademy.com
  14. 14.  1) 2) According to force element Elastic strap or elastic bands Spring loaded  According to direction of pull a) b) c) d) e) f) g) Cervical pull Straight pull High pull (Occipital/parietal) Reverse Pull or protraction headgear Combination headgear Interlandi which gives more options for force direction. Chin cup -- occipital and vertical www.indiandentalacademy.com
  15. 15.  According to the purpose of usage: A. growth modulators 1. Protractors 2. Retractors 3. To control vertical excess A. reverse pull A. high pull A. chin cup B. straight pull C. cervical pull D. combination B. for space regaining C. molar distalisation D. intrusion of maxilla www.indiandentalacademy.com
  16. 16. High Pull Cervical pull www.indiandentalacademy.com Combination pull
  17. 17. Retraction head gear www.indiandentalacademy.com
  18. 18. COMPONENTS OF HEADGEAR: The principal components are • Force delivering unit: usually a facebow or a J hook that delivers force to the intra oral location • Force generating unit: this is the active unit- usually springs of elastic bands • Anchor unit: its location depends on the direction of the force applied, and is usually from the neck or the head. Force is transmitted to the dental arch by • Facebow: the force is delivered to the first molar by the face bow which is engaged in the buccal tube. It can be attached to removable appliances also. The facebow has an inner and an outer bow. The inner bow is available in either 0.045-0.051 inch, dependent on the size of the headgear tubes on the first molars. The outer bow is usually 0.072 inch. www.indiandentalacademy.com
  19. 19. The different methods of making the inner bow stop mesial to the first molar buccal tube are – u- loop: advantage is that the length of the arm can be altered by adjusting the loop; – Bayonet bend: horizontal inset bend that keeps the anterior segment of the bow away from the brackets. – Trevor Johnson Friction stops: stops can be fixed at the desirable location by crimping/soldering it – Stop screws: the position of these screws can be changed and can be re-used. Outer bow is attached to the anchor unit and can be of different types depending on its length: • srt- outer bow shorter than the inner bow • m- outer bow almost the same length as that of the inner bow • lo- outer bow is longer than the inner bow www.indiandentalacademy.com
  20. 20. • Force magnitude: Recommended force values per side for – full permanent dentition – 400-600 gms – early mixed dentition – 150-250 gms – late mixed dentition – 300-400 gms – Retention in permanent dentition – 150-400 gms. • Duration: according to Graber, forces of 12-16 hour duration applied as intermittent forces appear to be the most effective for orthopedic changes. Because the headgear is tooth borne, intermittent force minimizes tooth movement while still providing for skeletal change. An intermittent heavy force is less damaging to the periodontium and the teeth. • Force direction or vector: this depends on the location of the extraoral attachment and the location of the outer bow. www.indiandentalacademy.com
  21. 21. • Magnitude – For dental changes– According to Kloehn (1961) & Jacobson (1967) guided by patient comfort. – According to Berman (1976) – 450 gm/side (1lb). – J-hook headgear applies- 170-226 gm initially For Orthopedic changes – – According to Klein, Poulton, Graber- 450900gm/side (1-2lb). – Should not exceed total of 7 pounds force on maxilla. www.indiandentalacademy.com
  22. 22. BIOMECHANICAL CONSIDERATIONS     Mechanics describes the effects of forces on bodies and can be generally divided into three areas: 1) statics 2) Kinetics 3) strength of materials. Statics describes the effects of forces on bodies that are at rest or have a constant velocity. Force is action of one body on another body that tends to change or changes the shape of that second body. A force is equal to mass times acceleration (F = ma). Unit is Newton or gram. Millisecond/s^2. Grams are substituted for Newton in clinical orthodontics because the contribution of acceleration to the magnitude of force is clinically irrelevant. www.indiandentalacademy.com
  23. 23.  A force is a vector and is defined by the characteristics of vectors, which have magnitude and direction.  Magnitude of vectors represent its size. Direction is described by the vector’s line of action and point of origin.  The sum of two or more vectors is called resultant.  Clinically, the determination of horizontal , vertical and transverse components of a force improves the understanding of the direction of tooth movement that might be expected. www.indiandentalacademy.com
  24. 24. Center of resistance  A free body can be considered to have a single point within it where all of its mass is centered.  The center of mass is the point through which an applied force must pass for a free object to move linearly without any rotation.  Tooth is restrained body in which this center of mass is called center of resistance. It can be described in each plane of space. Single tooth, units of teeth, complete dental arches and the jaws themselves each have center of resistance.  In other words the center of resistance is the point on the body where a single force would produce translation i.e ., all points moving in parallel, straight lines www.indiandentalacademy.com
  25. 25.  The center of resistance of a tooth is dependent on the root length and morphology, the number of roots, and the level of alveolar bone support.  The exact location of the center of resistance is not easily identified. Analytical studies have determined that the center of resistance for single rooted tooth with normal alveolar bone levels is about one fourth to one third the distance from the cementoenamel junction to the root apex.  Miki and Hirato found that the location of the center of resistance of the midface of the human skull was between the first and second upper premolars anteroposteriorly, and between the lower margin of orbitale and distal apex of the first molar vertically in the sagittal plane.  It is distal to the lateral incisor roots for intrusive movements of maxillary anterior teeth. www.indiandentalacademy.com
  26. 26.  In maxillary first molar the center of resistance is estimated to be in the middle third of the root near the junction of cervical third or approximately at the trifurcation of the roots.  The center of resistance should not be regarded as a fixed point within a tooth, but rather as the composite point of all factors, offering different components of resistance to a certain force application. 1. The tooth anatomy and mass distribution within the tooth 2. The structure of the periodontal attachment 3. The degree of bony surroundings 4. The adjacent teeth. www.indiandentalacademy.com
  27. 27. Center of resistance of maxilla www.indiandentalacademy.com
  28. 28.  The point of application of a force is simply the point of contact between the body being moved and the applied force.  Direction is indicated by the body of the arrow itself and the arrowhead. Without the head of the arrow, the body alone indicates the line of action. The sense is determined by which end we put the arrowhead on.  Since the movement of a tooth (or any object) is determined by the net effect of all forces on it, it is necessary to combine applied forces to determine a single net force, or resultant. www.indiandentalacademy.com
  29. 29.  There may be a force on a tooth that we wish to break up into components.  For example, a cervical headgear to maxillary molars will move the molars in both the occlusal and distal directions. It may be useful to resolve the headgear force into the components that are parallel and perpendicular to the occlusal plane, in order to determine the magnitude of force in each of these directions. www.indiandentalacademy.com
  30. 30. Center of rotation  The center of rotation of a body is a point around which the body will rotate or tip.  The center of rotation can be changed, being dependent on external force application.  When a force is applied to a tooth and its line of action does not pass through center of rotation, then tipping will occur around a center of rotation which may be located anywhere between the center of resistance of the tooth and infinity. www.indiandentalacademy.com
  31. 31. Resolving a force into components It is often useful to divide a single force into components at right angles to each other. Usually, the objective is to determine how much force is being delivered perpendicular and parallel to the occlusal plane, Frankfort horizontal, or the long axis of the tooth. www.indiandentalacademy.com
  32. 32. Moment of force  Forces not acting through the center of resistance do not solely produce linear motion.  The moment of force results in some rotational movement. The moment of force is the tendency for a force to produce rotation.  It is unrecognized in clinical orthodontics. Awareness of moment of force is required to develop effective and efficient appliance designs.  Two variables determine the moment of force – the magnitude of the force and the distance. Either one can be manipulated by the clinician to achieve the desired force systems. www.indiandentalacademy.com
  33. 33. Moment of a couple  This is another method of achieving rotational movements.  A couple is two parallel forces of equal magnitude acting in opposite directions and separated by a distance.  Direction is determined by following the direction of either force around the center of resistance to the origin of opposite force. www.indiandentalacademy.com
  34. 34. BIOMECHANICS OF HEADGEAR  Understanding how to control the direction and magnitude of the forces produced by various headgear designs is paramount in achieving desirable clinical results.  Decreasing the patient's length of treatment and improving the treatment results would be only two of the benefits derived from applying well-planned force systems.  A method of analyzing force systems produced in the anterior-posterior and vertical planes will aid the clinician. www.indiandentalacademy.com
  35. 35.  In 1971 Armstrong demonstrated the importance of the precise control of magnitude, direction, and duration of extraoral force to increase its efficiency and effectiveness in treating malocclusions in the late mixed dentition.  Gould has shown how changes in the inclination of the facebow affect the direction of the force and ultimately the direction of tooth movement.  Greenspan presented reference charts elaborating the different moments and forces produced with the various headgear designs. www.indiandentalacademy.com
  36. 36. Moments (M) and forces produced by force vectors applied at varying positions relative to the center of resistance (CR) of a constrained body in this case the maxillary 1st molar. The vertical (V} and horizontal (H) forces are proportional in magnitude to the legs of the triangle that is constructed . In (a) the vertical and horizontal components of the force are approximately equal. The moment's direction is counterclockwise since the line of force is above CR. The magnitude of M is the product of LF times the perpendicular distance (identified as P)from LF to CR. LF goes through CR in (b) thus there is no M produced. The tooth will translate parallel to the line of force. The posterior force component is larger than the superior. The LF in (c) will produce a posterior and interior movement. The moment (P x LF) is below CR and is therefore www.indiandentalacademy.com clockwise.
  37. 37.  The magnitude of the moment produced by the headgear is calculated by multiplying the perpendicular distance (P) from the LF to the CR by the magnitude of the force. Thus, for a given force, the greater the distance from the CR that the force is applied, the greater will be the moment.  A comprehensive understanding of the potential, limitations, and undesirable side-effects can be gained by understanding the mechanical principles involved in its application.  We can now apply our basic principles to assess force systems applied by various headgear designs. www.indiandentalacademy.com
  38. 38. Center of resistance of maxilla: • Miki 1979 and Hirato 1984 reported that the location of the center of resistance in the midface of the human skull is between the first and second upper premolars anteroposteriorly, and between the lower margin of orbitale and the distal apex of the first molar vertically in the sagittal plane. www.indiandentalacademy.com
  39. 39. • Lee in AJO 1997 determined the Cres of the maxilla using holographic inferometry. They found that the Cres of the maxilla was located at the distal contacts of the maxillary first molars, one half the distance from the functional occlusal plane to the inferior border of the orbit. Hence the application of 500 gms per side of force applied 15 mm above the occlusal plane and directed 200 downward from the occlusal plane produced pure translatory movement of maxilla. Protraction of maxilla below the CRes produces counterclockwise rotation of the maxilla. They suggested that by varying the force system, the amount and direction of maxillary rotation might be controlled. www.indiandentalacademy.com
  40. 40. • The center of resistance of the dentomaxillary complex when viewed in the sagittal plane is located on a line perpendicular to functional occlusal plane at the distal contact of first maxillary molars. When viewed in the frontal plane, there are two centers of resistance since the dentomaxillary complex is essentially comprised of two bones that articulate with each other at the mid palatal suture. If forces are applied in the presence of a 0.036 stainless steel TPA or a sutural expander, then the two units act as a single unit. www.indiandentalacademy.com
  41. 41. Clinical location of the Cres: (angle 1999 Stanley Braun) • The location of the Cres clinically is important. This can be done by holding an amalgam plugger or similar instrument in the maxillary vestibule when the teeth are in occlusion and the soft tissues and lips are relaxed. The amalgam plugger is positioned at the Cres of maxilla. The instrument is then palpated externally and a mark is made on the skin surface corresponding to it. The procedure is done for the other side also. The outer bow may then be adjusted so that the force vector passes through this point. www.indiandentalacademy.com
  42. 42. • Tanne et al concluded that the Cres of the maxilla was located at the posterosuperior ridge of the pterygomaxillary fissure. He suggested that the nasomaxillary complex was suspended by a sutural system similar to the desmodontal system of a tooth, possessing a Cres. • Since the handle for applying force to the maxilla is the teeth, a given force vector must be analyzed relative to both the Cres of the dental units (which lies between the bicuspid roots) as well as to the Cres of the skeletal unit. If no rotational effect is desired, then the force vector must pass through the Cres of both the skeletal and dental units. The force passing through both centers of resistance will lead to pure translatory reactive movement with the centers of rotation at infinity. www.indiandentalacademy.com
  43. 43. • When planning the direction in which the dental and skeletal units should move to approach a given treatment goal, the effect of growth on the development of these structures must also be considered. The force vector and the growth vector together determine the resultant vector of spatial displacement. The tendency towards extrusion or intrusion in the molar or incisor regions will be determined by the direction of force vector and notably by the rotational tendencies derived from the relation of the force vector to the center of resistance. The least rotational and vertical change is obtained in an arrangement wherein the applied force vector passes through the Cres of the upper arch and the maxilla and this is the desired condition for vertical control. www.indiandentalacademy.com
  44. 44. Cervical Headgear  The cervical (Kloehn) headgear is a device that many orthodontists have used routinely in the great majority of their headgear cases.  It is composed of three basic parts: (1) molar bands and tubes, (2) inner bow and outer bow soldered together near the middle of the two bows, and (3) a neckstrap that is placed around the back of the neck to provide traction.  This extraoral pull is generally applied bilaterally, for three main purposes: (1) as a restraining force, (2) as a retracting force, or (3) as a supplementary force. www.indiandentalacademy.com
  45. 45.  The cervical headgear is applied in early treatment of Class II malocclusion to inhibit forward displacement of the maxilla or maxillary teeth, while the rest of the dentofacial structures continue their normal growth.  As demonstrated by Oppenheim, this can cause a change in the intermaxillary relationship from Class II to Class I.  Perhaps the change in molar relationship is due not so much to the distal force, but to the clockwise moment that very effectively tips the molar crown distally. www.indiandentalacademy.com
  46. 46.  The main disadvantage to the use of the cervical headgear is that it normally will cause extrusion of the upper molars.  This movement is seldom desirable except in treatment of patients with short lower facial heights. These patients, it should be remembered, are few and far between.  The decision to treat with cervical headgear needs to be based on a complete understanding of the desired tooth movement and the force system that is produced with this headgear style. www.indiandentalacademy.com
  47. 47. Force systems with cervical headgear. OB (Outer bow)-A lies along the LFO and therefore only vertical and horizontal forces will be produced no M. The position of OB-B will produce an extrusive F posterior F and counterclockwise M since it is above CR. Outer bows located below the LFO will produce posterior forces and smaller extrusive forces since they are closer vertically to the neckstrap and clockwise moments. www.indiandentalacademy.com
  48. 48.  The different moments and forces produced by the cervical headgear depend on the situation of the outer bow in relation to the LFO. By definition, when the outer bow lies along the LFO, no moment occurs, and the force system will be reduced to a bodily movement in a posterior and extrusive direction.  If the outer bow is placed above this line (angle of above 20- 30 degree above occlusal plane), the moment produced by the force will be in a counterclockwise direction. On the other hand, if the outer bow is adjusted below this line the moment created will be clockwise. However, the direction of the forces are the same extrusive and posterior. It should be noted though that there is an exception to this rule. www.indiandentalacademy.com
  49. 49.  If the outer bow is located below (angle of less than 20 degree to occlusal plane) the neckstrap, the resultant force will be a small intrusive one, instead of extrusive. Of course, a distal force and large clockwise moment will also be produced.  The direction of pull provided by the cervical headgear is especially advantageous in treating short-face Class II maxillary protrusive cases with low mandibular plane angles and deep bites, where it is desirable to extrude the upper posterior teeth.  Also, the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases.  outer bow is short -- steepen the occlusal plane  outer bow is long -- flatten the occlusal plane www.indiandentalacademy.com
  50. 50. If the teeth are banded and stabilized, cervical pull appliance, produces a force below both center of resistance of maxilla and the dentition.. The distances of the force vector to A and B determine the center of rotation (x). www.indiandentalacademy.com
  51. 51. Studies on cervical headgear: • Cook et al in AJO 1994 studied growing children with Class II, Division 1 malocclusions who were treated with two different techniques: one group with orthopedic cervical headgear/lower utility arch (CHG/LUA) and another with cervical headgear alone. The outer bow was bent 200 upward and the inner bow was expanded. A force of 450 gms was used on either side. The authors found that CHG produced Class II correction through maxillary orthopedic and orthodontic changes, did not cause the upper molar to extrude beyond the amount seen with normal eruption, and did not produce an opening rotation of the mandible even in those patients who had dolichocephalic facial patterns. www.indiandentalacademy.com
  52. 52. • . • Melsen et al in AJO 2003 studied the intramaxillary molar displacement 7 years after treatment with Kloehn headgear and cervical traction. Two groups of 10 patients were studied. In one group, the outer bow was tilted upward by 200 and in another group, it was tilted down by 200. In the group that had the outer bow tilted downwards, molar correction was faster. In both the groups, the maxilla was moved backward and downward. A strong tendency of the molars to return to the key ridge was demonstrated, and there was no evidence that the Class I relationship obtained by extraoral traction was more stable than that obtained by functional or intramaxillary appliances. www.indiandentalacademy.com
  53. 53. • Haralabakis et al(AJO 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle, and assessed the ‘myth’ of posterior mandibular rotation. • They concluded that regardless of treatment taken, vertical skeletal relationship was not affected. www.indiandentalacademy.com
  54. 54. • Valiathan et al (JIOS1994) reported case of class II div I malocclusion treated non extraction with help of headgear. • Patient had come with a complaint of prominent upper teeth. • Extra oral examination – Convex profile, incompetent lips. • Intra oral examination – Class II molar/canine relation, missing lower left central incisor. Overjet was 11mm, Overbite - 5mm. www.indiandentalacademy.com
  55. 55. • • • • Patient was motivated to wear headgear. Duration of headgear wear – 10 – 12 hrs/day. 10 – 12 ounces force on each side. At end of treatment ANB reduced from 6˚ to 3 ˚. IMPA – 100˚ to 89˚. • Molar relation became class I, lips became competent & Profile improved considerably. • Total treatment duration was 2 yrs 2 months. www.indiandentalacademy.com
  56. 56. High Pull Headgear  The high-pull headgear, like the cervical-pull, is analyzed using the same principles of force and moment production described before. This style headgear always produces an intrusive and posterior direction of pull, due to the position of the headcap.  The direction of the moment that is produced is dependent on the position of the outer bow . If the outer bow is placed anterior to the LFO (angulated > 45 degree to occlusal plane) moment produced will be counterclockwise.  On the other hand, if the outer bow is placed posterior to this line (angulated less than 45 degree to occlusal plane), the moment produced will be in a clockwise direction. www.indiandentalacademy.com
  57. 57. High-pull headgears produce intrusive and posterior forces. Locating the outer bow in front of the LFO (A and D) will produce a counterclockwise M while an OB behind (B and C) will create a clockwise M. An OB located on the LFO would of course produce no M. www.indiandentalacademy.com
  58. 58.  The magnitude of this moment will be proportional to the distance of the outer bow to the CR.  If a distal and intrusive movement with no moment is desired, the outer bow must be placed somewhere along the LFO.  This force system would be beneficial in a long-face Class II patient with a high mandibular plane angle, where intrusion of maxillary molars would decrease facial height and improve the facial profile. www.indiandentalacademy.com
  59. 59. Short outer bow angulated high to create the headgear force line of action that is far anterior to the unit’s centre of resistance. This results in a force system at the unit’s center of resistance with a moment that tends to flatten the occlusal plane and distal and intrusive force components. www.indiandentalacademy.com
  60. 60. With long outer bow such that the headgear force’s line of action passes through the unit’s center of resistance and therefore no change in the cant of occlusal plane www.indiandentalacademy.com
  61. 61. Long outer bow. The equivalent force system at the unit’s center of resistance has a moment that tends to steepen the occlusal plane and a force with intrusive and distal components. May be necessary for class II open bite patients. www.indiandentalacademy.com
  62. 62. Studies on high pull headgear: • Firouz et al in AJO 1992 examined the skeletal and dental effects of the high-pull extraoral appliance, when the resultant force was directed through the level of trifurcation of the maxillary molars. Patients wore the headgear for a 6-month period, an average of 12 hours a day. The authors found that by directing the force of the headgear approximately through the center of resistance of the maxillary molars, it was possible to translate the molars in the direction of the applied force. Hence both intrusion and distal movement of the molars can be achieved at the same time.. www.indiandentalacademy.com
  63. 63. • Burke and Jacobson in AJO 1992 evaluated vertical changes in growing patients with high MPA Class II, Division 1 malocclusions who were treated with cervical and occipital headgears applied from different angles relative to the occlusal plane. They found greater vertical changes in pts with cervical HG. The changes in occlusal plane between the two types of headgears were most significant. Posterior maxillary dentoalveolar changes between the two groups were significant. www.indiandentalacademy.com
  64. 64. Straight Pull Headgear or Interlandi or Combination headgear  This style headgear is a combination of the high-pull and cervical headgear, with the advantage of increased versatility. Depending on the force system desired, the orthodontist has the opportunity to change the location of the LFO.  The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force.  This is accomplished by placing the LFO through the center of resistance, parallel to the occlusal plane.  Clinically, this means bending the outer bow to the same level as CR, and hooking the elastic to a notch at the same vertical level. www.indiandentalacademy.com
  65. 65. • Combination Facebow • The cervical facebow and the high-pull facebow can be used in combination (hence the term "combi facebow") to alter the direction of force along the plane of the occlusion. • Advocated by Armstrong (1971) and Berman (1976). www.indiandentalacademy.com
  66. 66. The straight-pull headgear is versatile in that the clinician has many optional LFO's . In this case an OB located on the LFO would cause translation in a posterior and slightly superior direction. OB's above the LFO will produce posterior and extrusive forces and clockwise moments. Placing the outer bow along an LFO that Is parallel to the maxillary occlusal plane will produce a pure posterior translation. www.indiandentalacademy.com
  67. 67.  The relation of the outer bow to the LFO dictates the direction and magnitude of forces and moments. Placing the outer bow above the LFO will produce a posterior force, counterclockwise rotation, and most often an intrusive force.  However, if the LFO cants up anteriorly (attachment site of elastic is lower on headcap than at outer bow), an extrusive force will be produced. If the outer bow is below the LFO, the force produced will be posterior and superior, and the moment will be in a clockwise direction. www.indiandentalacademy.com
  68. 68.  The straight-pull is the headgear of choice in a Class II malocclusion with no vertical problems.  It is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teeth, or possibly even translate them posteriorly. www.indiandentalacademy.com
  69. 69. Force’s line of action passes through center of resistance. No moment acting to change the cant of occlusal plane, and there is pure distal force passing through the center of resistance. www.indiandentalacademy.com
  70. 70.  This configuration is typical for redirecting maxillary horizontal growth in class II patients and /or to move maxillary molars distally via translation.  When a force is applied to a headgear with inner and outer bows, one side effect is buccal expansion component of forces, which act bilaterally.  This side effect is often helpful in class II malocclusions because it is often necessary to expand the posteriors to maintain proper interception as the buccal segment class II interrelationship is corrected.  If such expansion is not required, it can be prevented by using a transpalatal arch. www.indiandentalacademy.com
  71. 71. Vertical Pull Headgear  The main purpose of this headgear is to produce an intrusive direction of force to maxillary teeth, with posteriorly directed forces.  If the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR, pure intrusion may take place. Due to the multiple notches in the headcap, this headgear is also very versatile, as the LFO orientation may be changed.  However, upon establishing the LFO, our principles of determining force systems produced remains unchanged. www.indiandentalacademy.com
  72. 72. The vertical-pull headgear is used primarily when a large magnitude of pure intrusion is needed. The outer bow must be located on the LFO to obtain pure intrusion (A). An OB located anterior to the LFO will produce an intrusive force and a smaller posterior force and a counterclockwise moment (B and C). Locating the OB posterior to LFO will cause intrusion a small anterior force and a clockwise moment (D and E). www.indiandentalacademy.com
  73. 73.  The head is divided into two components: the anterior component from the LFO forward and the posterior component located behind the LFO. If the outer bow is placed anywhere in the anterior compartment, the moment created will be counterclockwise, and the forces produced will be intrusive and posterior.  If the outer bow is placed anywhere in the posterior section, the moment will be clockwise and the vertical force will be intrusive, but the horizontal force will be forward.  If this latter force system is desired, it will require inserting the inner bow into the buccal headgear tube from the distal. www.indiandentalacademy.com
  74. 74. • Root High-Pull Facebow • This facebow is designed to produce in intrusive force on the upper buccal segment which makes it valuable in the treatment of open-bite malocclusions. • Parts: • High-Pull heads strap with traction release force modules. • Facebow with outer bow tips terminating in approximation of 1st molar region. www.indiandentalacademy.com
  75. 75. • Root proposed that if the posterior vertical dimensions are controlled, more of the mandibular growth, will be, expressed in the horizontal direction thereby conserving or 'maximizing' the horizontal growth of the mandible. • In addition, when 'J' hooks are attached to hooks between upper central and internal incisors, it is impossible to dislodge them during normal usage from the soldered hooks. www.indiandentalacademy.com
  76. 76. • The purpose of the high pull Headgear when used in this manner is to produce a retrusive and intrusive force on upper anteriors. This force is also useful in counteracting the downward vector of force produce by Class II elastics. • In patients with low mandibular plane angles that need as much vertical development as possible, the combination of a high-pull Headgear with class II elastics can aid in predictable horizontal and vertical correction of malocclusions with the lower lip providing adequate restraint to class II elastic pull. www.indiandentalacademy.com
  77. 77. • The Interlandi type High-Pull Headgear • In this design, the outer bows are attached to the head straps of the headgear with the help of ½" later elastics. The direction of the applied force was modified by changing the point of attachment of the elastics. The level of buccal trifurcation of the maxillary first molar is to be clinically and radiographically determined. www.indiandentalacademy.com
  78. 78. • In order to prevent the distal tipping of molars, the end of the outer bow must terminate in the same plane as the centre of the upper 1st molar. Therefore, the force component is aligned to pass through the approximate centre of resistance of these teeth. • The inner bow is made parallel to the occlusal plane and the length of the outer bow is reduced so that it does not extend distal to the maxillary first molar. A force of 500 gms/side is used with recommended wear of 12 hrs/day. www.indiandentalacademy.com
  79. 79. • Asher Face Bow : Demonstrated by Roth. • This is a High-Pull facebow with a headcap and short intra-oral bow. • Used to retract maxillary incisors in premolar extraction spaces using 12-15 ounces of force. • It applies force directly to maxillary canine brackets. www.indiandentalacademy.com
  80. 80. Asymmetric Headgear  Right versus left asymmetries can be corrected using transpalatal or lingual arches to correct asymmetric molar axial inclinations. The same mechanism can be used to correct asymmetric molar rotations.  If buccal occlusion is asymmetric e.g. Class I on one side and class II on the other side, without asymmetries either in molar axial inclinations or in rotations, then it is most logical to achieve the correction with asymmetric headgear.  Distal forces exist on both sides, but they are three times greater on the long outer bow side than on the short outer bow side. www.indiandentalacademy.com
  81. 81.  Lateral forces, directed toward the short outer bow side exist with this headgear. Crossbite development should be kept in mind.  These are usually cervical or combination type. www.indiandentalacademy.com
  82. 82.  Suggestions to be noted with regard to the use of the asymmetric cervical gear: 1. The differential in length of arms of face-bow need not be great, only sufficient to alter the geometry so that the resultant bisector crosses the molar line closer to the more anteriorly positioned molar than to the other. Excessive difference in arm lengths could increase the lateral forces. 2. The diameter of wires can be increased for greater rigidity; it is suggested that the arch wire be 0.055 inch and the face-bow 0.075 inch (the 0.075 inch face-bow is approximately five times as stiff as the 0.050 inch one). 3. The arms of the face-bow should clear the cheeks so as not to introduce more undesirable lateral forces. www.indiandentalacademy.com
  83. 83. Asymmetric Headgear forces www.indiandentalacademy.com
  84. 84.  Rigorous force analysis of the several cervical gears of different design using elastic straps shows that the fundamental principle involved in the distribution of the forces to the right and left molars is the geometry of the direction of the right and left forces emanating from the cervical elastic band.  If these forces are symmetrical with reference to the midsagittal line of the head, then the distribution of the reactionary forces at the right and left molars will be equal, irrespective of the design of the rigid portions of the appliance (or the point of attachment of face-bow to arch wire). www.indiandentalacademy.com
  85. 85.  If the direction of forces from the cervical elastic band is asymmetrical with respect to the midsagittal line of the head, then the anterior-posterior components of the reactionary forces on the right and left molars will be unequal, the molar nearest the resultant of the two elastic band forces receiving the greater force. 2. Small lateral forces on the molars are always developed by this eccentric design. These forces can be manipulated to cause all lateral reaction to occur on one side or the other by springing the labial arch inward or outward, respectively. www.indiandentalacademy.com
  86. 86. • Unilateral face-bows – Hershey (AJO 1981) • Face-bows which successfully and predictably provide an asymmetrical delivery of distal force to their innerbow terminals are termed "unilateral face-bows”. www.indiandentalacademy.com
  87. 87. www.indiandentalacademy.com
  88. 88. • The face-bows are oriented so that the X axis passes through a point on the terminal ends of the inner bow and perpendicular to the midsagittal plane (Y axis). • The tractional forces FL and FR, which are equal in magnitude, are directed posteriorly and medially from the outer-bow tips and converge to form a tangent with the curvature of the neck. In all true unilateral face-bows, extension of these tractional forces allows then to intersect at a point to the right of the midsagittal plane. www.indiandentalacademy.com
  89. 89. • Bisection of the angle formed by the two tractional forces FL and FR yields a resultant force FZ. When resultant force FZ is extended, it intersects the interterminal line (X axis) to the left of the midsagittal plane (Y axis) and divides the interterminal line into unequal lengths a and b. • Because the resultant force intersects the interterminal line to the left of the midsagittal plane, the left inner-bow terminal (RLY) receives a greater distal force than the right inner bow terminal (RRY) Given those conditions, the distribution of these distal forces can be determined. www.indiandentalacademy.com
  90. 90. • Distal force exist on both sides but they are 3 times greater on long outer bow than short outer bow. • Also one has to watch if any crossbite is developing because of lateral forces www.indiandentalacademy.com
  91. 91. • In an evaluation of the lateral forces, a distinction must be made between the net lateral force and the lateral forces delivered to each of the two inner-bow terminals. • The net lateral force is the sum of force applied to both inner-bow terminals. • The direction of this net lateral force will always run from the inner-bow terminal receiving the greater distal force toward the side receiving the lesser distal force. www.indiandentalacademy.com
  92. 92. • The magnitude of this net lateral force is theoretically determinable. In contrast, the distribution of the lateral forces delivered to each of the specific inner-bow terminals is indeterminant and cannot be resolved theoretically. • One can only say that, at a given time, a specific inner-bow terminal is receiving a portion of the net lateral force that ranges in magnitude from all of the net lateral force to none of it. www.indiandentalacademy.com
  93. 93. There are four types of unilateral facebow designs available:  Power-arm face-bow. In this design, one outer bow is longer and/or wider than the other, with the longer or wider bow tip located on the side anticipated to receive the greater distal force. While effective in producing unilateral distal forces, the power-arm face-bow also generates lateral forces which tend to move the favored molar tooth into lingual cross-bite and the other molar into buccal cross-bite. Soldered-offset face-bow. Here the outer bow is attached to the inner bow by a fixed soldered joint placed on the side favored to receive the greater distal force. www.indiandentalacademy.com
  94. 94. • Swivel-offset face-bow. In this design the outer bow is attached to the inner bow through a swivel joint located in an offset position on the side favored to receive the greater distal force. • Spring-attachment face-bow. Here an open coil of spring is wrapped around one of the inner-bow terminals of a conventional bilateral face-bow. The coil is placed distal to the stop on the side favored to receive the greater distal force. • Yoshida et al in AJO 1998 evaluated the effects and side effects of asymmetric face-bows. They suggested that the power arm face-bow is thought to be relatively recommendable because it showed an acceptable asymmetric effect and is easily fabricated from a commercially available face-bow. They concluded that all asymmetric face-bows generate lateral forces as side effects as long as the force delivery system with a combination of an asymmetric face-bow and a neck strap or head cap is applied. www.indiandentalacademy.com
  95. 95. Headgear to lower jaw    1) 2)  1. 2. Headgear bracket-tube combinations can be attached to either lower first or second molar. If the bracket-tube combination is on the first molar, it is advantageous to place the headgear tube occlusally. First molar is preferred since The lingual arch is on the first molar and gives better control. It is easier for the patient. Possible directions are: The posterior segments tend to move back A positive moment will be produced, which will steepen the occlusal plane. www.indiandentalacademy.com
  96. 96. J- hook Headgear J-hooks to arch wire  A line of pull attached to the incisor region of the arch wire and passing occlusally to the center of the resistance will place a distally directed force upon the maxillary teeth, but will also tip the occlusal plane downwards at the incisor end of the arch.  A line of pull through center of resistance will produce distal movement of the maxillary arch without undesirable rotational effects.  A more vertical direction of pull, mesial and apical to center of resistance produces an anti-clockwise moment and an intrusive effect upon the incisor end of the arch wire  Disadvantage is that the flexibility of arch wire results in unavoidable deformations which subject the teeth near the attachment to diurnal reversals of force application as the extraoral appliance is attached or disengaged. Heavy arch wires minimize this rebound effect, but not eliminated. www.indiandentalacademy.com
  97. 97. J-hooks to individual teeth  If the center of resistance of a single tooth coincides with the centroid the line of force of a Jhook headgear intended to produce upright bodily movement of an individual tooth should ideally pass through this center of resistance.  Most authorities suggest an occipitally directed line of force to move maxillary canines distally. But straight pull is suggested as it is difficult to obey theoretical concepts when moving mandibular canines. www.indiandentalacademy.com
  98. 98. Direction of Headgear Force  Given by the line of action of force from the point of origin to the point of application of force. Anteroposterior Plane:  Explained by linear vectors of force. An anteroposterior force that does not pass through the occlusal plane will certainly have a vertical component. a) Force directed upwards above the occlusal plane has an intrusive effect on maxilla. b) Force directed downwards below the occlusal plane has an extrusive effect on maxilla. c) Force passing along Center of Resistance produces www.indiandentalacademy.com translation.
  99. 99. d) Force away from center of resistance( mesially, distally, apically, occlusally) produces a moment tending to change the occlusal cant. e) Magnitude of moment is determined by moment arm. Greater the moment arm – closer the Center of rotation moves towards canter of resistance and greater is the moment. f) Medium length of outer bow is chosen for translation. g) Short / long outer bow chosen when moment is desired. www.indiandentalacademy.com
  100. 100. Vertical Plane: a) Direction determined by the sense of the line of action. b) Outer bow along the Center of resistance produces translation. c) Force apical / occlusal to center of resistance produces moment ( Extrusive / intrusive / distal). d) Magnitude dependent on the inclination of line of action. www.indiandentalacademy.com
  101. 101. Lateral Plane: a) Shape or length of outer Bow has no effect on force application provided the distance of point of attachment to the midline axis are equal. Headgear tube placed buccal to center of resistance. b) Hence any force applied, passes buccal to center of resistance tending to roll the molars, buccally on intrusion and palatally on extrusion. This rotatory tendency is directly proportional to the perpendicular distance of buccal tube to center of resistance (moment arm). Clinically this moment is countered using 1. Palatal bar 2. Rectangular headgear tubes www.indiandentalacademy.com
  102. 102. CLINICAL APPLICATIONS OF HEADGEAR FORCE  There are four main uses of headgear force 1. 2. 3. 4. Anchorage control Tooth movement Orthopedic changes Controlling the cant of the occlusal plane www.indiandentalacademy.com
  103. 103. Anchorage Control  In class II treatment, headgear force can play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted.  Intraoral mechanics often result in eruption of teeth.  Headgear produces a vertical force greater than the force of side effect  Inner and outer bows can be of any shape, convolution, and length.  Only the angle and level of the final line of action after the strap forces have been applied to know exactly the force of headgear system. www.indiandentalacademy.com
  104. 104. Vertical force on molar tube, a side effect of intraoral mechanics Vertical component of occipital headgear force negates extrusive intraoral force side effect www.indiandentalacademy.com
  105. 105.  The reaction force from headgear is dissipated against the bones of the cranial vault, thus adding the resistance of these structures to the anchorage unit.  The only problem with reinforcement outside the dental arch is that springs within an arch provide constant forces, whereas elastics from one arch to the other tend to be intermittent, and extraoral force is likely to be even more intermittent.  For first molar extraction cases -Interlandi headgear to be suitable and well tolerated www.indiandentalacademy.com
  106. 106. Tooth movement  Adjustment of outer bow such that a horizontal force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently, clinical experience shows that the first molars will move distally 2mm in 24 months without tipping.  Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light. www.indiandentalacademy.com
  107. 107. Intrusion in deep bite cases  Headgear can be used in adjunct to upper utility arch. High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment.  120 to 150 g force is delivered. Distalization of molars  Headgear is the obvious choice. Fill time wear is necessary. Molar extrusion should be avoided so straight pull or high pull is used and not cervical.  Force – 300g on each side.  Unilateral molar distalization in unilateral class II can be achieved by asymmetric cervical headgear www.indiandentalacademy.com
  108. 108. Canine retraction using direct headgear force  Headgear using four hooks is used, which over a base arch wire 19 x 25 steel.  200 g of force supplied to each point of attachment to slide the canines posteriorly www.indiandentalacademy.com
  109. 109. Orthopedic changes  If the headgear is applied through the center of resistance of maxilla, which is in the posterosuperior part of maxilla. Determined clinically by dropping a line vertically 10mm from the outer canthus of eye and making a horizontal from that point to meet the pupil line in front of the face. www.indiandentalacademy.com
  110. 110.  If a preadolescent patient wears the headgear at least 12 hours each night , the forward component of maxillary growth is redirected. Effects of orthopedic forces on maxilla  Cervical traction produces stresses along the frontal process of maxilla, zygomaticofrontal suture, and the junction of the palatine bones, areas where high-pull traction produced no observable effect. Only the highpull headgear produces stress at the anterior junction of maxillae (anterior nasal spine). www.indiandentalacademy.com
  111. 111. Pterygoid plates of the sphenoid  High stress develops upon activation.  These stresses begin in the middle of the posterior curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla.  As the force increases, the stresses progress superiorly toward the body of the sphenoid bone. Zygomatic arches  Cervical and high pull both produce similar stress .  Starts at the inferior border of the zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone.  Cervical force produces more intensity at lower load level. www.indiandentalacademy.com
  112. 112. Junction of the maxilla with the lacrimal and ethmoid bones  Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid. Maxillary teeth  High stresses around maxillary molars with cervical traction. These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex.  Also distal to second molar. Frontal process of maxilla  Stresses produced anterior to nasolacrimal foramen only with cervical pull. www.indiandentalacademy.com
  113. 113. Zygomaticofrontal suture  Just before maximum cervical load stress begins to appear. Only with cervical pull. Palate  Cervical traction produces stress in posterior region developing in the horizontal portion of palatine bones. High pull has no effect. Anterior junction of left and right maxillae  Only high pull produces forces below the anterior nasal spine and just lateral to the suture between the two maxillae. www.indiandentalacademy.com
  114. 114. Sphenomaxillary suture- large compressive stresses. Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stresses Frontozygomatic suture- large compressive stress Frontomaxillary suture- large tensile stress  Sphenomaxillary and sphenozygomatic sutures, in particular, resisted the posterior displacement of the complex  Stresses in the nasomaxillary sutures are varied by the direction of headgear force, and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth. www.indiandentalacademy.com
  115. 115.  Clinical studies have also demonstrated that extraoral force is effective at restricting maxillary horizontal growth. In fact, several studies are also available which indicate that headgear therapy can reposition the maxillary complex posteriorly and inferiorly in growing patients.  Armstrong has demonstrated remarkably rapid (three to four months) correction of Class II malocclusions in growing patients with the use of continuous heavy forces parallel to the occlusal plane.  Although not attached to the mandible or primarily aimed at mandibular alteration, headgear treatment has been shown to effect mandibular remodeling; the mandible and chin point have been shown to relocate anteriorly in standard edgewise treatment. Whether this represents a change which would not have occurred in untreated individuals remains unclear. www.indiandentalacademy.com
  116. 116.    In Class II malocclusions with a fault in maxilla, profile convexity of the upper jaw can be a) Basal – large S-N-A angle b) Dentoalveolar – increased sell-nasion-prosthion (S-N_Pr) angle. c) Dental – increased upper incisor to S-N plane angle Maxillary basal prognathism requires heavy orthopedic force. When evaluating the maxillary base, the inclination should also be considered. An upward and forward inclination aggravates maxillary protrusion. (Schwarz (1958) termed this as pseudoprotrusion) www.indiandentalacademy.com
  117. 117.  A retro inclination (palatal plane tipped anteriorly) can actually compensate for maxillary prognathism.  The control of the vertical dimension in this type of malocclusion often depends on the inclination of the maxillary base, especially if it is combined with either a deep overbite or an open bite. Combined activator – headgear therapy is required. www.indiandentalacademy.com
  118. 118. Short face( skeletal Deep bite) Class II when growth potential remains  Goal is to increase face height and correct deep bite, while allowing more eruption of the lower than the upper teeth so that the occlusal plane rotates up posteriorly.  Although cervical headgear tends to open the bite anteriorly and therefore would help to correct a deep bite problem, it differentially erupts the upper rather than the lower molars and does not produce the desired change in the orientation of occlusal plane.  So functional appliances are useful in these patients. www.indiandentalacademy.com
  119. 119. Class II with normal face height and growth potential  Clinical studies show that in these patients , many have deep bite due to excessive eruption of lower incisors. And can be treated successfully by two stage treatment.  Stage I using headgear or functional appliances.  Straight pull or high pull headgear is preferred over cervical headgear, to reduce the elongation of maxillary molars and better control the inclination of the mandibular plane. www.indiandentalacademy.com
  120. 120. Skeletal open bite  Characterized by excessive AFH. Major diagnostic criteria are: 1. Short mandibular ramus 2. a rotation of the palatal plane down posteriorly.  Typical growth pattern shows vertical growth of the maxilla, often more posteriorly than anteriorly, coupled with downward-backward rotation of the mandible and excessive eruption of maxillary and mandibular teeth.  Only two thirds of the patients have actually an open bite – in others excessive eruption of incisors keeps the bite closed – but rotation of the mandible produces class II malocclusion even if the mandible is normal in size and severe class II if the mandible is small. www.indiandentalacademy.com
  121. 121.   Successful growth modification would be restraining vertical development and encouraging anteroposterior mandibular growth while controlling the eruption of teeth in both jaws. High pull headgear to the maxillary first molars is the least effective because it does not control the eruption of other teeth. Furthermore use of molars as primary handle on maxilla presents three problems: 1.Vertical component of force produces buccolingual tipping . 2. The level of force application is limited by the tolerance and response of the supporting tissues of these two teeth. 3. Molar movement is the predominant dental change. www.indiandentalacademy.com
  122. 122.  High pull headgear with maxillary splint is better, as it provides en masse dental control.  Advantages 1. restraint of anteroinferior displacement of maxillary complex with growth. 2. restraint of maxillary teeth 3. Disengagement corrects occlusal interferences, facilitating correction of functional mandibular displacements. 4. Direction and distribution of extraoral force application to the maxilla may be adjusted over a broader range. 5. incisors can be retracted by including labial bow in the design and full control over incisor tipping possible. 6. safety enhanced. www.indiandentalacademy.com
  123. 123.  But this does not control the eruption of lower teeth. Eruption of lower teeth is controlled most readily by interocclusal bite blocks, easily incorporated into a functional appliance. If the bite blocks separates the teeth more than the freeway space, force is created against both upper and lower teeth that opposes eruption.  So the most effective treatment is a combination of a functional appliance with bite blocks and high pull headgear.  If cervical (Kloehn type) headgear is used, the maxillary molars are driven distally into the “wedge” as the molars are extruded or tipped down and back. The mandible is rotated down and back, increasing the apparent mandibular retrusion and allowing compensatory alveolodental growth to stabilize this undesirable sagittal change. The maxillary incisors are usually tipped down and back at the same time, restricting forward mandibular growth. This result is now known as kloehn effect. www.indiandentalacademy.com
  124. 124.  With combined activator – headgear treatment, high pull headgear attached to activator exerts a retarding force on horizontal and vertical maxillary growth vectors.  A high pull headgear does not tip the palatal plane down and does not tip up the anterior end of the palatal plane, which tends to enhance maxillary incisor protrusion and upper lip prominence. www.indiandentalacademy.com
  125. 125.  The headgear-activator has the following modes of action: 1. Intrusion and retraction of upper front teeth 2. Distalization of upper molars 3. Maxilla retraction 4. Mandibular growth stimulation, especially in the brachyfacial group 5. Opening of the facial axis in the brachyfacial group 6. Maintenance of the facial axis in the dolichofacial group 7. Minor, if any, tilting of lower incisors 8. Stopping lower incisor eruption 9. Stopping the descent of the palate www.indiandentalacademy.com
  126. 126.  Vertical control is obtained in two ways. 1.The untrimmed interocclusal acrylic acts as a bite block, preventing molar eruption and clockwise mandibular rotation. 2.The inclination of the outer facebow allows precise control over the direction of force, according to the following principles: a)A force passing through the center of resistance produces pure translation in the direction of the force. b)A force passing at a distance from the center of resistance generates a moment, with a combined effect of rotation (from the moment) and translation (from the force). www.indiandentalacademy.com
  127. 127. HEADGEARS WITH OTHER APPLIANCES HEADGEARS WITH REMOVABLE APPLIANCES: Margolis acrylic cervico occipital anchorage: • Margolis in 1976 incorporated extraoral force with removable appliances for pts with class II malocclusions, using them both in active and retentive phases of treatment. The Margolis appliance is called an ACCO. Modified maxillary removable Hawley type appliance permits the use of extraoral forces against the maxillary dentition. Multiple ball end clasps and occlusal coverage can increase the resistance to dislodgement by extraoral traction. Margolis used this appliance to hold the torque correction achieved with fixed appliances. This appliance was later modified by the addition of 1 mm buccal tubes to the labial wire and soldering them vertically at the canine-lateral incisor embrasure to receive the Jhook extraoral force arms. An inclined plane was added to eliminate functional retrusion and free the mandible for all possible forward growth. www.indiandentalacademy.com
  128. 128. • A new ACCO is made after extraoral forces and inclined plane have created a class I buccal segment. The ACCO should be worn both day and night with a minimum of 12 hrs nocturnal headgear wear. ACCO can be continued to be used as a retainer after active treatment and extraoral force can be applied as indicated with the ACCO to treat any residual sagittal abnormality or tendency to return to original class II relationship. www.indiandentalacademy.com
  129. 129. Jacobson’s splint • Jacobson used a splint similar to the ACCO with extra oral traction for correction of mild class II malocclusions. The reduction in overjet and the sagittal discrepancy reduce the deforming action of the abnormal perioral muscle function. The force magnitude for this type of removable appliance must not be too great to prevent dislodgement of the appliance. www.indiandentalacademy.com
  130. 130. • The direction of pull of the extra oral force should coincide roughly with that of the Y-axis or a line extending from the symphysis to a point 1.5 cm in front of the external auditory meatus. This prevents the unfavorable basal maxillary tipping and extrusion of teeth. The Jacobson craniomaxillary splint is used with occlusal coverage to aid in retention and to prevent maxillary eruption while allowing unimpeded upward and forward eruption of the mandibular buccal segment that assists in sagittal correction. www.indiandentalacademy.com
  131. 131. Verdon combination appliance: • An appliance similar to Jacobson’s splint was used. The basic appliance of choice is a modified active plate. The major objective is to effect a change through a distalising influence on the maxillary arch leaving the mandibular arch alone. An occipital headcap is used to prevent tipping down the anterior palatal plane. A cervical strap can be used but the force values are significantly smaller, producing more dentoalveolar and less basal effects. www.indiandentalacademy.com
  132. 132. HEADGEAR WITH FIXED APPLIANCES: Edgewise appliance: • Various types of headgears are used with the edgewise appliance depending on the type of malocclusion and the stage of treatment for effecting dental and skeletal changes. • Kloehn type of headgear is the type most commonly used mainly to reinforce anchorage. In growing patients, it produces skeletal changes if high forces are used. The end of the outer bow is bent up at an angle of 150 to prevent tipping of molars. This produces opening of the bite due to extrusion of molars. Hence it should only be used in patients with normal or deep overbites. In patients with normal or low mandibular plane angles, kloehn face bow can be used to obtain skeletal corrections. www.indiandentalacademy.com
  133. 133. • Straight pull headgear is used on the upper arch if extrusion of the teeth is not desired. This type is used on the upper arch during retraction of the canines and incisors. • High pull headgear with facebow is used to intrude molars in selected cases of open bites. • Intrusion of buccal teeth produces a rotation of mandible thereby closing the openbite and reducing the LAFH. • High pull headgear using J-hook can be used in the anterior segment for deep bite correction and for correction of gummy smiles. www.indiandentalacademy.com
  134. 134. Straight wire appliance: • When anchorage is critical, the anterior teeth are retracted by the use of a modified Asher’s face bow which can be hooked either to a neck strap to retract the lower or upper anteriors or an anterior high pull headcap to retract and intrude the upper incisors. • Ashers high pull facebow with headcap is used to retract the incisors using 12-15 oz of force. www.indiandentalacademy.com
  135. 135. Begg appliance: • Extraoral forces are usually not required with begg since begg mechanics minimizes the need for anchorage conservation. However, headgears can be used in isolated cases for distalisation of teeth or when orthopedic control of maxilla is favored over extraction or orthognathic surgery. Such indications would include severe skeletal class II problems with high ANB differences combined with excessive maxillary protrusion. Headgear would also be indicated in nonextraction cases requiring distal positioning of the posterior teeth or maxilla to produce an acceptable anteroposterior dental and skeletal relationship. www.indiandentalacademy.com
  136. 136. Level anchorage system: • High pull face bow headgear is used to the maxillary molar or a high pull J hook headgear attached to the maxillary area, with 1 pound pressure on each side, worn 12 hours per day by a growing patient will reduce the ANB approximately by 10. Anchorage space in the lower arch needed to correct the ANB angle is reduced by approximately 1 mm for each 6 months of headgear wear. www.indiandentalacademy.com
  137. 137. HEADGEARS WITH FUNCTIONAL APPLIANCES Headgears with activator • Levin et al in AJO 1985 reported the use of a cervical headgear with the activator. A cervical HG with a long outer bow applying a force of 400 gms was used. It was concluded that activator cervical headgear therapy results in a simulation of normal mandibular occlusal development and a redirection of maxillary dentoalveolar development. Mesofacial and brachyfacial types appeared to respond most favorably to treatment. www.indiandentalacademy.com
  138. 138. • Pfeiffer in AJO 1982 described the combination activator — cervical headgear therapy. They preferred to use cervical headgear, where necessary, for two reasons: (1) to extrude maxillary molars, and (2) to apply orthopedic traction to the maxilla and an activator to induce orthopedic mandibular changes, restrain maxillary growth, and cause selective eruption of teeth. • Cura et al in AJO 1996 compared the effects of activator and activator with HG therepy. A high pull head gear was used with a force of 400 gms per side for 17 hrs a day. They found greater improvement in the sagittal base relationship in cases treated with combination therapy than in patients who were treated with activator alone. www.indiandentalacademy.com
  139. 139. • Stockli and Teusher in their combination therapy said that vertical and sagittal control of maxillary growth was essential in the management of class II patients. Their activator HG combination achieved control in all the three planes of space. A high pull HG was used for depression of molars and vertical control of the maxilla. www.indiandentalacademy.com
  140. 140. Headgears with herbst appliance. • Was first reported by weislander in AJO 1984. It is indicated only in cases of severe class II MO in early mixed dentition. In order to transfer as much force as possible to the base of the maxilla, splints may be used with an attempt to distribute the force over the total dentoalveolar area for better anchorage purposes. Orthopedic forces in human beings, usually in the magnitude of 500 to 1,000 gm of pressure on each side were suggested. When the total maxillary dental arch is used as anchorage, forces up to 1,500 gm on each side can be applied without discomfort to the patient. In most cases treated in the mixed dentition, appliances were constructed for nighttime wear only, and 12 to 18 hours of wear gave maximum treatment effect. The orthopedic effect of treatment may increase if proper anchorage is used and if the appliance is worn 24 hours. www.indiandentalacademy.com
  141. 141. • Weislander in AJO 1993 evaluated the effect of treatment and retention on a group of consecutive cases several years out of retention and to compare the initial changes during Herbst treatment with the long-term situation 8 years after treatment. An average increase of 2mm was found in the mandibular body length. Prolonged retention with activator was needed to minimize relapse. Findings indicated that maxillary sutural remodeling might be more receptive long-term to orthopedic treatment than the mandibular condylar growth process. • Schiavoni in AJO 1992 evaluated the possibility of controlling vertical dimension by using Herbst appliance and high pull headgear in hyperdivergent facial patterns. The high-pull headgear had an orthopedic restriction of the maxillary vertical development rather than an effect on the sagittal plane. Elimination of anterior inferences by orthodontic repositioning of the front teeth and preventing extrusion of the posterior teeth allowed an anterior rotation of the mandible, with improvement of the sagittal correction and beneficial reduction in lower face height. www.indiandentalacademy.com
  142. 142. • Rabie and Hagg in Sem Orthod 2003 investigated the effect of adding HG to the herbst appliance and in the retention period. A high pull HG whose outer bow was adjusted to be 300 above the occlusal plane was used. The HG delivered a force of 400-500 gms. Results showed that the maxillary restraint and improvement in jaw base was greater in patients who had HG during the treatment period. Rotation of the palatal plane was seen in the herbst group but not the HG- herbst group. The authors concluded that adding HG to the herbst resulted in increased orthopedic effect on the maxilla and a large increase in the jaw base relationship. www.indiandentalacademy.com
  143. 143. Headgears with Bionator • Dahan et al in AJO 1989 described the use of a bioactivator with high pull headgear for treatment of class II division I malocclusion cases. High-pull headgear was adjusted to the buccal tube units of the multianchorage system. The headgear was worn every night (8 to 10 hours) during the first year of treatment. They concluded that the combination of a bimaxillary appliance with extraoral forces leads to rapid changes in the correction of Class II, Division 1 skeletal conditions. www.indiandentalacademy.com
  144. 144. Headgears and Twin block • Parkin and sandler in AJO 2001 compared the effects of two modifications of twin block. The effect of twin block appliance modified by the incorporation of a high pull headgear and torquing springs positioned on the maxillary incisors was studied. The headgear force was directed at the Cres of the maxilla in an attempt to control the vertical position of the maxilla. Flying headgear tubes situated next to the maxillary second premolars were used to apply a force of 400 gm per side, worn for 120 hours per week. www.indiandentalacademy.com
  145. 145. • They found that in pts with headgear, the maxillary plane appeared to have rotated in an anticlockwise direction. Vertical eruption of the maxillary molars was restricted by headgear. A restraint in the anteroposterior position of the maxilla was demonstrated. The authors concluded that the addition of high pull headgear in patients with twin block allowed effective vertical and sagittal control of the maxilla with no increase in LFH/TFH. www.indiandentalacademy.com
  146. 146. Headgears with frankel appliance: • Owen et al in JCO 1985 modified the FR by adding posterior bite blocks and a headgear for the control of the posterior maxilla. A high pull headgear was used for posterior maxillary control. The modified function regulator appeared to offer advantages in combining functional jaw orthopedics with directional force headgear in the early comprehensive treatment of long face patients. www.indiandentalacademy.com
  147. 147. • They suggested that the vertical dimension or anterior facial height (ANS-Me) could be held constant or even decreased through the holding or intrusion of the upper molars. Although no condylar growth was demonstrated in this study, there was a potential for increased mandibular growth. www.indiandentalacademy.com
  148. 148. Comparison with Functional appliances www.indiandentalacademy.com
  149. 149. Outcomes in a 2-phase randomized clinical trial of early Class II treatment. Tulloch JF, Proffit WR, Phillips C. (Am J Orthod Dentofacial Orthop. 2004) • In a 2-phased, parallel, randomized trial of early (preadolescent) versus later (adolescent) treatment for children with severe (>7 mm overjet) Class II malocclusions. • Favorable growth changes were observed in about 75% of those receiving early treatment with either a headgear or a functional appliance. After a second phase of fixed appliance treatment for both the previously treated children and the untreated controls, however, early treatment had little effect on the subsequent treatment outcomes www.indiandentalacademy.com
  150. 150. • Both bionator and head-gear treatments corrected Class II molar relationships, reduced overjet and apical base discrepancies, and caused posterior maxillary tooth movement. • The skeletal changes, largely attributable to enhanced mandibular growth in both headgear and bionator subjects, were stable a year after the end of treatment, but dental movements relapsed www.indiandentalacademy.com
  151. 151. • Headgear versus function regulator in the early treatment of Class II, Division 1 malocclusion: A randomized clinical trial J. Ghafari,F. S. Shofer, U. Jacobsson Hunt, D. L. Markowitz, and L. L. Lasterb • A prospective randomized clinical trial was conducted to evaluate the early treatment of Class II, Division 1 malocclusion in prepubertal children. Facial and occlusal changes after treatment with either a headgear or a Frankel function regulator were reported. www.indiandentalacademy.com
  152. 152. • The results indicate that both the headgear and function regulator were effective in correcting the malocclusion www.indiandentalacademy.com
  153. 153. • Graber Appliance: – Plastic positioner type appliance made to fit the teeth with incorporated metal arms which receive the extraoral source of force. – Used in treatment of Class II Division 1 cases by allowing arch expansion. Mills Vig appliance: • Consists of an active expansion plate with a jack-screw to eliminate maxillary narrowing and crossbite. • Soldered buccal tubes to molars receive facebow end. www.indiandentalacademy.com
  154. 154. HEADGEARS FOR MOLAR DISTALISATION: According to Nanda et al • By directing the forces through the Cres of the maxillary molars, intrusion and distalisation of molars can be achieved. • An average of 500 gms was suggested to translate the molars distally and at the same time initiate maxillary changes that are normally associated with high force levels. • If the headgear is used for a short period of 6 months with good patient co-operation, significant dental improvement in the class II molar relation can be achieved. www.indiandentalacademy.com
  155. 155. Cephalometric guidelines for headgear treatment Direction of growth Broad mandibular base and ascending ramus together with a very marked, thick symphysis suggest a change in direction toward horizontal growth. Narrow mandible and thin symphysis – vertical growth. Growth potential If the mandible is too small in class II in a growing individual, growth may be expected to be quite considerable. A well developed mandible in a posterior position must be considered to offer poor prospects for successful correction of class II malocclusion, except in cases with translation. Convexity of nasomaxillary complex SNA angle large ANS far anterior to N- Pog line. Ante – inclination of maxilla (large J angle) will increase protrusion (pseudo protrusion). Midface (N – Sn) is short. Extreme case – Microrhinal dysplasia. www.indiandentalacademy.com
  156. 156. Timing of headgear treatment  The most optimum treatment time is between maturational stages SMI 4 to 7, a very high velocity period of growth.  The next most desirable time to treat is during the accelerating velocity period between stages SMI 1 to 3  the least desirable time is during the decelerating velocity period between maturational stages SMI 8 to 11. This information is clinically useful for all growth related mechanics of treatment, retention, and orthosurgical timing of therapy. www.indiandentalacademy.com
  157. 157. SELECTION GUIDELINES FOR HEADGEAR TYPES 1. Cervical pull face bow headgear a) A large horizontal component of force is present, but also a vertical component, which may extrude the maxillary molar. b) Molar extrusion may assist the treatment of class II, low Frankfurt-mandibular angle, increased overbite cases. c) Limited molar extrusion will probably not affect class II cases with an average FMA, particularly if angle SNB is average. Facial changes must be monitored during treatment. d) High FMA, class II cases, should never be subjected to this line of force to avoid the creation of an unfavorable mandibular rotation, with consequent ill effects upon the face. www.indiandentalacademy.com
  158. 158. e) Outer arms bent downwards will tilt distally the crowns of mesially tilted molars. f) Outer arms bent upwards appear to result in more upright, but less distal movement. 2. Straight pull face bow headgear a) A very large horizontal component of force is present. b) A small vertical force component may produce mild extrusion. c) It will probably effect less distal movement of the root, than of the crown. www.indiandentalacademy.com
  159. 159. 3. High pull face bow headgear a) Root axial control may be achieved to produce effective upright distal movement of the molar teeth or tilting as is required. b) The molar will be intruded and the ratio between distal and intrusive movement will depend upon the steepness of the angle of pull. c) It is a suitable line of force to move distally the fully banded maxillary arch, intruding the molar end and less certainly the incisor end. d) In high FMA, class II cases, with reduced or even average overbite, distal movement with extrusion of maxillary molars is probably to be avoided, and high pull anchorage may be advantageous. www.indiandentalacademy.com
  160. 160. e) In high FMA, class II cases, with anterior open bite, a vertical line of force commencing occlusally and passing distally to the center of resistance, will intrude the maxillary molars and may rotate downwards the incisal end of a fully banded arch. 4. Cervical pull J-hook headgear a) Used to the maxillary incisor region, a tipping of the incisal end of the occlusal plane in a downward direction may result, with a reduction of open bite. However molar extrusion is probable. b) Used to the mandibular incisor region, it may depress the chin creating more vertical space into which maxillary teeth may be extruded during class III treatment. The resultant downward and backward rotation reduces the antero-posterior basal discrepancy. www.indiandentalacademy.com
  161. 161. 5. Straight pull J-hook headgear a) It is suitable for moving mandibular canines distally. b) Attached to the maxillary incisor region, distal arch movement occurs, but a downward tipping of the incisal end of the arch is probable. 6. High pull j-hook headgear a) A line of force to the maxillary incisor region passing mesial and apical to the center of resistance, will intrude the upper incisors, move them distally and augment palatal root torque. b) A line of force to the maxillary incisor region passing through the center of resistance will have a large distal and smaller intrusive effect upon the incisor region. Theoretically this may produce the greatest orthopedic effect. www.indiandentalacademy.com
  162. 162. c) A line of force to the maxillary incisor region passing occlusal to the center of resistance may have a mild downward tipping effect upon the incisal end of the occlusal plane. d) It is the direction of choice for distal movement of maxillary canines or to sliding jigs for maxillary molar distal movement or anchorage www.indiandentalacademy.com
  163. 163. The following are to be followed with headgear treatment: 1. Routine use of Visual Treatment Objective of some type of comparative treatment goal. 2. Routine cephalometric x-rays at six to nine month intervals to evaluate treatment changes and progress. 3. Knowledge of normal growth and the effects of orthodontic treatment and extraoral forces to the patient. 4. A prediction of the future skeletal pattern of the patient, the accuracy of which can be enhanced by the control that can be exerted upon the skeletal pattern by proper orthodontic and orthopedic treatment. www.indiandentalacademy.com
  164. 164. Components of face bow system  Maxillary molar tubes are positioned gingivally or occlusally on the molar bracket.  The advantage to gingival placement is that the tube is closer to the center of rotation of molar, which reduces molar tipping. www.indiandentalacademy.com
  165. 165. The outer Bow (Wisker Bow)  The outer bow ends anteriorly to the ears. Then when a patient wears a combination face bow, the high pull portion will fit naturally in front of the ears and the neck strap will attach below the ears.  In all cases, the outer bow is positioned in the horizontal plane parallel to and even with the inner bow. Outer bow dimension – 0.051" – 0.062" stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal t  When using a high pull retractor, the end of the outer bow should coincide with the location of the maxillary first molars. It is bent 60 degree angle superior to horizontal.  The outer bow must be adjusted to fit the face of the patient. Should be 5 to 10mm away from cheeks. www.indiandentalacademy.com
  166. 166. Outer bow resting passively between lips Outer bow several millimeters from cheek www.indiandentalacademy.com
  167. 167. Length of outer bow is critical to the desired changes www.indiandentalacademy.com
  168. 168. The Inner Bow  Proper adjustment of the inner bow will allow the wire to slide in and out of the headgear tubes easily when the posterior strap is not attached.  Adjustments to the inner bow can be made in six directions: bucco-lingually, superior- inferiorly, antero-posteriorly.  First Bucco-lingual force is controlled.  If the bow is inserted into one headgear tube, the other bow end should be expanded approximately 5mm buccal to the opposite tube.  This expansion bend is made near the anterior portion of the inner bow. www.indiandentalacademy.com
  169. 169. As a class II molar relationship is corrected, the relative forward movement of the lower arch will produce a cross bite tendency unless the upper arch width is expanded www.indiandentalacademy.com
  170. 170. Vertical adjustments can be made at molar adjustment loops www.indiandentalacademy.com
  171. 171.  If maxillary arch expansion is desired and a face bow is used, a greater amount of expansive force must be built into the inner bow. Inner bow is expanded more than 5mm.  Secondly, in superior-inferior direction  When the patient closes his mouth and relaxes his lips, the anterior junction of the inner and outer bows should not be pushing either lip in vertical direction.  The bow should be in a passive position between the lips. In order to maintain this position , the posterior ends of the inner bow are adjusted superiorly or inferiorly. www.indiandentalacademy.com
  172. 172.  Lastly, antero-posterior adjustment.  Inner-outer bow junction is just anterior to the point where the lips seal.  It may be necessary to enlarge or constrict the loops in the inner bow to achieve this position. www.indiandentalacademy.com
  173. 173. Safety Issues • Injuries have been reported with the use of headgear. They have been associated with the catapult effect of simple elasticated extra oral traction and with the face bow coming out at night. • In some cases, facebow either was knocked, pulled out of molar tubes while still attached to headstrap or neckstrap. This lead facebow to recoil and hit patient in face, head or neck. • This detachment and injuries can compromise success of treatment. www.indiandentalacademy.com
  174. 174.  The potential of these devices to injure the face has been recognized by the orthodontic community. Among the possible sites of injury are the eyes.  With improper handling, headgear appliances can result in penetrating ocular injuries. The removable metallic bow contains two projections that normally fit into the mouth. However, when pulled forward, the bow can slip from the oral cavity, retract under tension, and strike the eyes with substantial force.  Spectacles may provide protection, but it is also possible that these metallic projections under tension could slip beneath the frames and strike the eyes. The distance between these two projections approximates the interpupillary distance. Thus, there is an added risk of bilateral ocular injuries www.indiandentalacademy.com
  175. 175.  In general, bacterial endophthalmitis occurs infrequently after penetrating ocular injuries. However, in headgear injuries, the risk of bacterial infection is extremely high because the penetrating object is contaminated with saliva.  The normal flora of the oral cavity consists of a multitude of organisms, including S viridans, anaerobic and aerobic staphylococci, gram-negative diplococci (Neisseria and Branhamella species), Corynebacterium, Lactobacillus, anaerobic Vibrio, and Actinomyces species. Thus, patients are susceptible to mixed-flora infections.  In response to the occurrence of facial injuries, manufacturers are developing new appliances with devices that prevent disengagement or that release the elastic traction when sharp forces are applied www.indiandentalacademy.com
  176. 176. Samuels et al AJO 1996 in a review of orthodontic face-bow injuries and safety equipment found that the cause of the injuries could be roughly grouped into four categories. 1. Accidental disengagement when the child was playing while wearing the headgear 2. Incorrect handling by the child during the fitting or removal of the headgear 3. Deliberate disengagement of the headgear caused by another child 4. Unintentional disengagement or detachment of the headgear during sleep. www.indiandentalacademy.com
  177. 177. • Injuries have occurred with both removable & fixed appliances. • Ranged in severity from minor lacerations to loss of eye. • All occurred in children aged between 9-14 yrs. • The presence of oral micro-organisms on the ends of inner bow radically alters the outcome of the soft tissue trauma, making the patient highly susceptible to infections. www.indiandentalacademy.com
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  179. 179. • Facebow injuries to eye can cause little pain at the outset often delaying the child seeking treatment • This delay allow infection to proceed unchecked for a considerable period of time. • Eyeball is also an excellent culture medium, and when it becomes infected it becomes difficult to control. www.indiandentalacademy.com
  180. 180. • When one eye is injured there is a risk to the other undamaged eye from a process called sympathetic opthalmitis. • In order to prevent these injuries – several safety devices. • These include self releasing extra oral traction systems, plastic neckstraps, shielded facebows and locking facebows. • Patients should be instructed on proper use of appliance. www.indiandentalacademy.com
  181. 181. • Facebows should be designed so that the ends of neither the inner nor outer bow are capable of producing either penetrating injuries or lacerations. Self releasing headgear/neckgear – • Manufactured in a variety of designs. • Modular systems can be use with Headcap or neckcap. • Travel provide by these modules should enable a comfortable range of head movement by patient without their unintentional release www.indiandentalacademy.com
  182. 182. www.indiandentalacademy.com Safety release headgear with spring mechanism which breaks apart when excessive
  183. 183. • For headcap – 10mm extension. • For neckstrap – 25 mm/module. • Plastic neckstraps – Retain facebow within buccal tubes.. • As the strap is not flexible it cannot accommodate the changing distance between the back of neck and the facebow, and still provide a continuous resistance to the displacement of facebow from buccal tubes. www.indiandentalacademy.com
  184. 184. • Shielded facebows – Shielding include on their inner ends in an attempt to reduce the severity or risk of soft tissue trauma. • Shielding does not improve facebow self retentive capability and it can disengage in night. • Locking orthodontic facebows – It has 2 omega bands so that it can easily adjusted to fit different lengths of buccal tubes. www.indiandentalacademy.com
  185. 185. www.indiandentalacademy.com
  186. 186. • It successfully reduced night time disengagement of facebow to less than 1%. • Patients instructions – 1) Never wear headgear during playful activity. 2) If it ever comes off at night or there are any other problems patient should stop wearing the appliance and return to see clinician. 3) Excessive force should not be used while removing facebow. www.indiandentalacademy.com
  187. 187. • 4) Before removing facebow patient first must remove headcap/neckstrap. • 5) If any injury occurs to eye, eye should be examined without delay by a suitably trained medical practitioner. www.indiandentalacademy.com
  188. 188. Patient Compliance • An important aspect of using extra oral traction is whether appliance is being worn as instructed. • Patient’s compliance can be improved if both parents & clinician provide motivation. www.indiandentalacademy.com
  189. 189. • Patient should be warned- soreness to be expected during 1st week till supporting bone adapts to force. • Next visit after 2wks - verify patient compliance. • Then after 1 month next visit. Frequent visits increase compliance • Indicators to assess headgear wear– Ease with which patient can place & remove appliance – Mobility of maxillary molar. – Signs of wear of extra oral attachment components & calculus on face-bow after few months of wear. – Improvement in A-P relationship. – Patient keeps a daily diary of length of use www.indiandentalacademy.com
  190. 190. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com