HEAD GEARS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
In order to conduct orthodontic treatment, force and the various modes in which force can be applied for treatment effects is of great significance. Most of forces can be generated from intra oral sources, when the intraoral sources are found to be insufficient, extraoral forces are resorted to. Among the most commonly used extraoral force generating source are the headgears. Headgears are available in a wide variety of configurations and are programmed to deliver forces in predetermined directions to bring about orthodontic and orthopaedic movements. www.indiandentalacademy.com
The first reported use of headgear anchorage for correction of protrusion of the upper anterior teeth was made by kingsley in 1866. Upper first bicuspid teeth were extracted , a gold frame was made to fit around the upper anterior teeth and this was attached with elastic ligatures to a leather headcap. Edward H.Angle reported on his occipital anchorage appliance in 1888. It consisted of clamp bands with tubes on upper first molar teeth, a labial bow that attached with with a ball & socket arrangement to an archwire (“B� arch) , and a headcap that attached to the facebow with elastic traction bands. www.indiandentalacademy.com
www.indiandentalacademy.com
The labial bow contacted the anterior teeth and these teeth were tipped lingually by action of headgear. Calvin case patented his headgear in 1907, not only could he retract anterior teeth , but he could also torque and intrude them. Case was also able to retract teeth in buccal segments to correct class II malocclusions. www.indiandentalacademy.com
www.indiandentalacademy.com
Setback – 1) Angle said that even though occipital anchorage is efficient, best approach is intermaxillary anchorage. 2) Case said about disadvantage of discomfort & irritation with occipital force. With these pronouncements headgear use in United States came to an abrupt stop. www.indiandentalacademy.com
Headgear use continued in europe. Dr. Albin Oppenheim used headgears to uncrowd teeth & to correct class II malocclusions, without having to extract teeth & without creating double protrusions. In U.S. Kloehn influenced by Oppenheim’s work started using headgears to correct Class II malocclusions.
www.indiandentalacademy.com
His greatest innovation was to solder outer bow to inner bow , thus by raising or lowering arms of outer bow, he controlled adverse distal tipping of molars. He introduced elastic neck strap to apply traction – Cervical headgear/Kloehn headgear.
www.indiandentalacademy.com
Later some orthodontists used occipital/ high pull headgear – a) to prevent mandibular rotation. b) Attached to upper incisors to keep them intruded & torqued while retracting them. But Ricketts stopped using high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichofacial patterns of facial growth. www.indiandentalacademy.com
Ricketts observations with cervical headgear were – 1) There was retraction of maxillary complex as measured at point A. 2) Palate rotated in a clockwise direction. 3) There was minimal extrusion of upper 1st molars & incisor teeth. 4) Occlusal plane rotated in anticlockwise direction. 5) Minimal or no adverse rotation of mandible.
www.indiandentalacademy.com
Graber in 1955 article ‘Extra oral force – Facts & fallacies quote – 1) There is no evidence that maxillary growth , per se is affected. 2) Bodily distal movement of molars can be accomplished, but in most cases it is merely restrained from coming forward in its normal path or tipped distally. 3) It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars. www.indiandentalacademy.com
4) Class II Div I malocclusions are amenable to correction by use of extraoral force. Marked improvement in basal relations can be obtained. 5) Growth is an important factor, its presence or absence profoundly influences the results. Coordination of treatment with pubertal growth spurt means a greater likelihood of success. www.indiandentalacademy.com
CLASSIFICATION There are various types of headgears depending on the location of the anchor unit. These are listed as follows: Cervical Pull High Pull J-hook Asymmetric/Unilateral. www.indiandentalacademy.com
Appliance Design Basic Elements: 1 Force delivering unit i.e. face bow, 'J' hooks. 2 Force generating unit i.e. Elastics, springs. 3 Anchor Unit i.e. Head cap, Neck pad www.indiandentalacademy.com
Face Bows : Made of stainless steel having a diameter between 0.040" to 0.051". It engages buccal tubes on the first molars. The methods used to make the inner bow stop mesial to the 1st molar are: Bayonet Bends / Horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth. Stops : Cylindrical tubes with an internal diameter corresponding to inner bow diameter. www.indiandentalacademy.com
Preformed inner loops: serve as adjustable stops as well as shock absorbers and are angulated for clearance. They also facilitate necessary unilateral adjustments to keep the facebow comfortably centered, increase facebow length as molars gradually move distally & reduce facebow length as incisors are retracted. Trevor Johnson friction stops: with internal diameter of 0.045" which can be soldered to inner bow to serve as stops.
www.indiandentalacademy.com
Outer Bow (Wisker Bow) Acts as a media through which force is transmitted to the inner arch. Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspid hooks and in 3 sizes short , medium and long. 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 tube. www.indiandentalacademy.com
www.indiandentalacademy.com
–
Miscellaneous Components: Springs : Calibrated tension springs are available. These have the advantage that the applied force can be varied. Elastics : Serve as force elements and are available in the following forms: Neck bands with strong/medium pull Extraoral plastic chins with length 119 mm Ribbon Headgears for making individual HG's.
Safety pads : for elastic bands Neck pads with length 180 mm Flexi pads in roll form for individual size.
www.indiandentalacademy.com
www.indiandentalacademy.com
Friction Release Systems : These include safety release to reduce "sling-shot' hazards by means of clips which release automatically when pulled with excessive force. They provide case of assembly and include an inner steel coil to provide a consistent traction force. Prescription Tab variable Force Neckpads : These provide adjustable calibrated force of 8-18 oz . Headcaps : of the following types are available: Pressembled Standard universal Preassembled Extra Comfort Vertical Pull
www.indiandentalacademy.com
Cervical Pull Headgear Dr. Silas J. Kloehn first described it on 1947. It is also known as the Kloehn Headgear. This was to become the most widely used form of an extraoral traction appliance to be used in contemporary orthodontics. Dr. Kloehn reported the use of a headgear attached by means of hooks to an upper 0.045" archwire stopped against the upper permanent first molars giving a reasonably well controlled force action with a cervical neck strap to general force. www.indiandentalacademy.com
www.indiandentalacademy.com
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outer bow to produce a force acting 5Ëš-10Ëš tangent the occlusal plane, it is called the cervical pull headgear. Recommended time of wear is 12-14 hrs/day This disto occlusally directed force has an extrusive effect on the molars.
www.indiandentalacademy.com
The effects of the appliance itself are most clearly revealed in instances where the Headgear is worn for 14 hrs/day especially when the patient is experiencing a relatively small amount of growth. As the distoocclusally directed force has an extrusive effect on the molars the cervical-Pull Headgear is not recommended in cases having an elevated mandibular plane angle or open bite cases.
www.indiandentalacademy.com
High-pull headgear The high-pull facebow is attached to the maxillary first molars by way of an inner bow that is the same length as the outer bow. The outer bow is bent upward so that the point of force application and the direction of force lie above the center of resistance of the maxillary first molars. The inner bow lies passively in the molar tubes, or it can be expanded if an increase in transpalatal width is desired www.indiandentalacademy.com
www.indiandentalacademy.com
Rationale justifying the use of a High-Pull Headgear – Cervical-Pull headgear's have certain drawbacks that are especially undesirable in a majority of Class II Division I cases. These problems have their origin in the line of action of the force, generated by a cervical-pull extraoral traction device, which often passes below the centre of resistance of the maxillary first molar.
www.indiandentalacademy.com
As a result of this, it produces a moment of force which results, in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment. An additional drawback of the cervical pull headgear is the distooclusally orientation of generated force which causes extrusionof molars. This prevents it's use in patents having a high mandibular plane angle. www.indiandentalacademy.com
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition. So concept and utility of the High-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction. www.indiandentalacademy.com
With the High-Pull Headgear, it is possible to change the direction of force in relation to the center of resistance of the dental units to which the force is being applied in order to achieve better control of resulting tooth movement in a distal direction, and to modify vertical changes in the maxillary molar position to correct Class II relationships using a relatively lower magnitude of forces. www.indiandentalacademy.com
Treatment effects of the High-Pull Headgear include intrusion and distalization of maxillary models, Anti-clockwise mandibular rotation, decreased lower facial height, retrusion of incisors etc.
www.indiandentalacademy.com
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
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
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
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
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
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
www.indiandentalacademy.com
J-Hook Headgear The forces produced by extraoral traction also can be attached anteriorly by means of J-hooks to the archwire or to hooks soldered to the archwire. Flared maxillary incisors can be retracted using either a high-pull or a straight-pull headgear combined with J-hooks that are attached to the archwire anteriorly or by using a closing arch supported by headgear. www.indiandentalacademy.com
www.indiandentalacademy.com
Headgears with J-hooks also are used to potentiate archwire mechanics by helping control forces incorporated into the archwire (e.g., torque, intrusion). J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth. Usually done in edgewise mechanotherapy.
www.indiandentalacademy.com
A similar type of retraction-stabilization of the mandibular dental arch also can be achieved. In addition, it is possible to attach J-hooks to the maxillary arch and the mandibular arch simultaneously. Armstrong (1971) , Hickham (1974) and Vaden et al (1986) have used 4 J hooks with the interlandii headgear to simultaneously retract maxillary & mandibular canines. www.indiandentalacademy.com
Hickham (1974) also suggested use of diagonally set J hooks for reciprocal correction of maxillary & mandibular centre lines. In Tweed-Merrifield non extraction treatment, Jhook headgear is also attached to mandibular anterior teeth to prevent mandibular incisor proclination during the resolution of lower incisor crowding and the preparation of mandibular anchorage.
www.indiandentalacademy.com
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
www.indiandentalacademy.com
www.indiandentalacademy.com
Advantages: – Comfortable to wear. – Conserves anchorage – Simultaneous retraction of both arches. Helps in intrusion of incisors.
www.indiandentalacademy.com
Distalizing plate of Margolis & Cetlin Commonly called ACCO appliance. AC – Acrylic CO – Cervical Occipital Anchorage. A removable plate is used to distalize maxillary molars bodily. During 2nd phase during which space consolidation occurs, extraoral forces help maintain anchorage posteriorly. www.indiandentalacademy.com
www.indiandentalacademy.com
Headgear with Activator: – Reported by Stockli + Teuscher (1964) wherein a cervical HG was attached to upper molars. – Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during Class II treatment. – Bass modified the appliance and used a 'J' hook headgear. www.indiandentalacademy.com
– Primary treatment objective is to restrict developmental contributions that tend to cause a skeletal Class II and at the same time attempt to correct anteroposterior relation of jaws. – Usage mainly limited to mixed dentition with force application of 250 gms/side.
www.indiandentalacademy.com
Headgear with Herbst Appliance: – First described by Wieslander (1984) wherein the headgear is fixed to a tube soldered to the molar attachment. – High-pull force direction using 1000 gms/side of force and worn for 12-18 hrs/day in mixed dentition period. – Produces a synergistic effect on correction of skeletal Class II cases wherein the Herbst Appliance stimulates mandibular growth while this headgear force redirects maxillary growth. www.indiandentalacademy.com
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 face-bow end. www.indiandentalacademy.com
Asymmetric/Unilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other. (e.g., Class II molar relationship on one side, Class I on the other The inner bow is shortened on the Class I side, and the outer bow is bent away from the cheek. www.indiandentalacademy.com
The center of attachment to the inner bow is moved laterally, thus producing asymmetrical forces against the two sides of the dental arches. Disadvantage - Extended use of this device will tend to skew the arch to one side.
www.indiandentalacademy.com
4 types – 1) Power arm face bow – One outer bow is longer/wider than the other. Longer/Wider bow tip is located on side anticipated to receive greater distal force. Power arm face bow also generates lateral forces which tend to move the favoured molar tooth into lingual crossbite and the opposite molar into buccal cross bite. www.indiandentalacademy.com
2) Soldered offset face bow - outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force. 3) Swivel offset face bow – In this design, outer bow is attached to inner bow by means of a swivel joint located in an offset position on the side favored to receive greater distal force. Said to minimize undesirable lateral forces. www.indiandentalacademy.com
4) Spring attachment face bow – An open coil spring is wrapped around one of the inner bow terminal of a conventional bilaterally symmetrical face bow. Coil is placed distal to the slope on side favored to receive the greater distal force.
www.indiandentalacademy.com
www.indiandentalacademy.com
Biomechnaical aspects. Location of centre of resistance a) Maxillary first molar – Situated at trifurcation of the roots. Worms et al(1973) reported that distalization of maxillary first molars led to occlusal & distal movement of erupting 2nd molars . Due to resistance offered by erupting 2nd molars, centre of resistance of 1st molars move from root trifurcation towards crown. www.indiandentalacademy.com
2) Maxillary dental arch – Between the roots of 1st & 2nd premolars. 3) Maxilla/Nasomaxillary complex – Nanda & Goldin(1980) reported it to be in central part of zygoma. According to Billet et al (2001) it is same as maxillary arch. Tanne et al (1995) – At pterygo-maxillary fissure. 4) For 4 maxillary incisors – According to Melsen et al(1990) it is within roots of central & lateral incisors. www.indiandentalacademy.com
www.indiandentalacademy.com
Pedersen et al (1991) & Vanden et al (1986) reported it to be more distally. 5) Maxillary six anterior teeth – Melsen et al(1990) estimated it to be in centroid of triangle linking centers of resistance of central, lateral incisors & canines. Vanden et al (1986) reported it to be distal to 2nd premolar root. Pedersen et al (1991) – Between canine & 1st premolar roots. www.indiandentalacademy.com
Cervical pull headgear 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. Line of force moment (LFO), is a line from the strap-force application point through the maxillary center of resistance. The different moments and forces produced by the cervical headgear depend on the situation of the outer bow in relation to the LFO. www.indiandentalacademy.com
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. Outer bow is equal length to inner bow. If the outer bow is placed above this line, it passes distal to centre of resistance the moment produced by the force will be in a counterclockwise direction. Outer bow is long. www.indiandentalacademy.com
www.indiandentalacademy.com
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. Tends to steepen occlusal plane. In such cases outer bow is short length. If the outer bow is located below 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.
www.indiandentalacademy.com
www.indiandentalacademy.com
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. www.indiandentalacademy.com
High Pull headgear 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 .
www.indiandentalacademy.com
If the outer bow is placed anterior to the LFO, either above or below the occlusal plane level, the moment produced will be counterclockwise. On the other hand, if the outer bow is placed posterior to this line, the moment produced will be in a clockwise direction. The magnitude of this moment will be proportional to the distance of the outer bow to the CR. www.indiandentalacademy.com
www.indiandentalacademy.com
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
www.indiandentalacademy.com
Straight Pull 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
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.
www.indiandentalacademy.com
www.indiandentalacademy.com
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.
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
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. The vertical-pull headgear is not as commonly used as are the others. However, it is very useful when pure intrusion of buccal segments is required, as in the Class I open-bite patient. www.indiandentalacademy.com
www.indiandentalacademy.com
Asymmetric headgear The critical consideration is the geometric configuration of the outer-bow tips relative to the midsagittal plane of the inner bow. Evaluation of the mechanics is developed around the basic concept that only when the outer-bow tips of an activated face-bow are asymmetrical about the midsagittal plane of the inner bow can unilateral forces be delivered to the inner-bow terminals. Given equal tractional forces, if no asymmetry of activated outer-bow tips is present, no unilateral distal forces can be delivered to the inner-bow terminals. www.indiandentalacademy.com
www.indiandentalacademy.com
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
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
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
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
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
J hook headgear This type of pull places an intrusive & distal force upon upper incisors. In theory high pull should be placed so that line of force passes labially to center of resistance, this will tip root palatally & crown labially. In practice difficult to achieve unless incisors are proclined or pull nearly vertical. www.indiandentalacademy.com
Hooks pointing occlusally & soldered distal to upper central rather than upper lateral makes vertical support more effective. Line of force passing – a) Mesial & apical to center of resistance : intrude & distalize upper incisors & augment palatal root torque. b) Passing through the center of resistance will have a large distal & small intrusive effect. c) Passing occlusal – has a mild downward tipping effect upon incisal end of occlusal plane. www.indiandentalacademy.com
Low pull J hook neckgear Can cause tipping of incisal end of occlusal plane in a downward direction,resulting in reduction of open bite. If used in mandibular incisor region, it may depress chin creating more vertical space into which maxillary teeth can be extruded during class III treatment. Resultant downward & backward mandibular rotation reduces the A-P basal discrepancy. www.indiandentalacademy.com
TREATMENT EFFECTS Extraoral traction has been shown to produce a variety of skeletal and dentoalveolar effects in Class II patients. Even though there is some agreement among investigators as to the effects produced, the clinical management of the appliance, the direction of force applied and the amount of force used may explain some of the differences among investigation. www.indiandentalacademy.com
Anteroposterior Dimension Maxillary Skeletal Position A primary treatment effect of extraoral traction is the restriction of maxillary skeletal growth. There is virtually universal agreement that because of treatment Point A is repositioned posteriorly relative to the remainder of the face, resulting in a reduction in maxillary prognathism. Wieslander (1974) has shown that this technique also influences that cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear. www.indiandentalacademy.com
Maxillary Dentoalveolar Position Distal movement of the maxillary molars is a typical treatment effect produced by cervical headgear therapy. In contrast, Hubbard and coworkers(1994), who studied a sample of patients treated by Kloehn, reported a mesial movement of the first molar. Extrusion of the maxillary molars also has been observed, with two to three times as much extrusion reported as would be expected during normal growth. On the other hand, Hubbard and colleagues did not observe molar extrusion. www.indiandentalacademy.com
Mandibular Dentoalveolar Position There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandibular dentition other than the treatment effects that are produced in association with fixed appliance treatment. There appears to be no effect.
www.indiandentalacademy.com
Mandibular Skeletal Position The anteroposterior relationship of the chin has been correlated to the amount of vertical opening produced during treatment. A downward and backward rotation of the mandible and a similar movement of Point B and pogonion have been reported, as has an opening of the mandibular plane angle. Kloehn(1947) and Ringenberg and Butts(1970) report no change in the SNB angle, but other investigators ( Mcnamara, 1996, Graber 1956) note either a posterior or anterior movement of Point B. www.indiandentalacademy.com
Vertical Dimension There is no universal agreement as to the effect of cervical headgear treatment on the vertical dimension, as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures.
www.indiandentalacademy.com
Mandibular Plane Angle and Lower Anterior Facial Height An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators. An opening of the bite and an increase in lower anterior facial height also has been a frequent finding. Klein(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth.
www.indiandentalacademy.com
A high-pull headgear has been recommended to reduce the extrusion of the maxillary first molars. In contrast, Ringenberg and Butts(1970), Baumrind(1978) , and Hubbard and coworkers(1994) report a closure of the mandibular plane angle with treatment, whereas others reported no change. www.indiandentalacademy.com
Occlusal Plane Angle Investigators have differed as to the effect of extraoral traction on the orientation of the occlusal plane relative to the cranial base. The anatomic occlusal plane normally closes with age. Klein(1957), King(1957), and Hubbard and colleagues (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base. Hubbard and associates noted that the functional occlusal plane closed slightly with treatment as well. www.indiandentalacademy.com
Palatal Plane Angle The palatal plane has been shown to tip anteriorly with an uneven descent, resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine. On the other hand, Kloehn(1961) and Boecler and co-workers(1989) noted no change in the palatal plane. www.indiandentalacademy.com
Transverse Dimension In the literature , changes in the transverse dimension with extraoral traction has been minimal. Ghafari and co-workers(1994), who conducted a comparative study of the straight-pull headgear and FR-2 appliance of Frankel. The inner bow of the facebow was adjusted at every appointment "to avoid any constriction or major expansion of the intermolar distance," resulting in a total expansion of the inner bow of 1.5-2.0 mm. www.indiandentalacademy.com
Ghafari and colleagues noted increases not only in intermolar distance, but in intercanine distance as well. These investigators hypothesized that the change in intercanine distance, a region not directly affected by the facebow, may have been a result of a shielding effect by the inner bow on the lip and cheek musculature, an indication of the influence of the buccal and labial musculature on tooth position.
www.indiandentalacademy.com
Stienberger , Burstone, Andersen (Angle 2004) did a study to see whether high pull headgear can prevent steepening /extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion. Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion. www.indiandentalacademy.com
Haulabakis 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
Leandro et al ( AJO 2005) studied the effects of cervical headgear on space available for maxillary 2nd molar to erupt. They suggested that despite restriction of movement of maxillary 1st molar & maxilla, there was sufficient space for 2 nd molar to erupt because of posterior displacement of PTM point & growth at maxillary tuberosity. www.indiandentalacademy.com
Serdar Usumez, Metin Orhan ( EJO 2005) studied effects of cervical headgear on head position. They found that it causes a significant cranial flexion, which may be responsible for its effects on mandible that is it can be a initiating factor for forward mandibular positioning.
www.indiandentalacademy.com
Hubbard et al ( Angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients . Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals. Maxillary 1st molars continue to grow forward, cranial base showed very little change. Mandibular plane angle did not increased appreciably with treatment
www.indiandentalacademy.com
Distal molar movement with Kloehn headgear:Is it stable? Birte Melsen, and Michel Dalstra, (AJO 2003) The aim of this study was to evaluate intramaxillary molar movement after 8 months of cervical traction and posttreatment displacement 7 years later. The total molar displacements in relation to stable intraosseous reference points were compared with those observed in an untreated control group that also had intraosseous reference indicators inserted. During the headgear period, the type of molar displacement could be predicted by the direction of the force system acting on the teeth.
www.indiandentalacademy.com
It was noted, however, that the variation in the vertical development was related more to each patient’s growth pattern than to the force system applied. After cessation of the headgear, intramaxillary displacement of the molars was noted, and the total displacement of the molars did not differ from that of the untreated group. The indication for intramaxillary displacement of the molars by means of extraoral traction is therefore questioned.
www.indiandentalacademy.com
Birte Melsen ( AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible.
www.indiandentalacademy.com
Quantitative analysis of the orthodontic and orthopedic effects of maxillary traction Sheldon Baumrind, ,Robert J. Isaacson ( AJO 1983) They analyzed differences in displacement of ANS and of the upper first molar when different vectors of force are delivered to the maxilla in non-full-banded Phase I mixed-dentition treatment of Class II malocclusion. Study included a cervical-traction group, a high-pull-to-upper-molar group, a modifiedactivator group, and an untreated Class II control group. www.indiandentalacademy.com
Orthopedic distal displacement of ANS was significantly greater in the high-pull and cervical groups than in the activator group. Orthopedic downward displacement of ANS was seen to be significantly greater in the cervical group than in the high-pull and activator groups. In the region of the first molar cusp, mean distal displacement of the tooth as an orthopedic effect was found to be almost identical in the cervical and high-pull groups (although variability was greater in the cervical group), but the mean orthodontic effect was significantly greater in the high-pull group than in the cervical group.
www.indiandentalacademy.com
The cervical-traction group showed significant mean extrusive effects of both the orthodontic and the orthopedic types, but even for this group total extrusion was on average no more than 1 mm. as compared to the control group.
www.indiandentalacademy.com
Changes in mandibular position and upper airway dimension by wearing cervical headgearduring sleep Hiyama et al ( AJO 2001) The purpose of this study was to examine changes in mandibular position and oropharyngeal structures that were induced by the wearing of cervical headgear during sleep. Ten healthy adults (7 male and 3 female) who gave their informed consent were included in this study. A pair of lateral cephalograms was taken with the patient in the supine position with and without cervical headgear at end-expiraton stage during 1 to 2 non rapid eye movement sleep.
www.indiandentalacademy.com
Amount of jaw opening was significantly decreased by the wearing of the cervical headgear (P < .05), although no significant anteroposterior mandibular displacement was induced. The sagittal dimension of the upper airway was significantly reduced (P < .05); however, no significant changes were observed in the vertical length of the upper airway.
www.indiandentalacademy.com
Although the hyoid bone and the third cervical vertebra moved significantly forward by the wearing of the cervical headgear (P < .05), the relationship among the mandibular symphysis, the hyoid bone,and the third cervical vertebra did not change.
These results suggest that cervical headgear significantly reduced the sagittal dimension of the upper airway during sleep, although there was no significant anteroposterior displacement of the mandible. www.indiandentalacademy.com
Force duration & magnitude Standard extra oral force fell in range between 400 & 700gm. 700 gm for 12 â&#x20AC;&#x201C; 14 hrs is required for an orthopaedic effect. Ricketts (1979). â&#x20AC;&#x201C; force of 150gm was appropriate for extra oral retraction in adults and children. 500gm was required for orthopaedic change. Kloehn considered that between 350 & 700gm of force was the most that could be tolerated.
www.indiandentalacademy.com
Armstrong(1971) used more than 2000gm. McLaughlin, Bennett & Trevisi (2001) recommended a force level of 250 to 350gm to provide anchorage for fixed appliances. In combination system - 100gm cervical pull with 150gm high pull for anchorage. For extra oral traction ; 150gm cervical pull with 250gm high pull headgear.
www.indiandentalacademy.com
Duration of force : 10 â&#x20AC;&#x201C; 12 hrs for anchorage. 12 â&#x20AC;&#x201C; 14 hrs for traction for distalization of molars or for orthopaedic effect.
www.indiandentalacademy.com
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 â&#x20AC;&#x201C; Convex profile, incompetent lips. Intra oral examination â&#x20AC;&#x201C; Class II molar/canine relation, missing lower left central incisor. Overjet was 11mm, Overbite - 5mm. www.indiandentalacademy.com
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
Comparison with Functional appliances
www.indiandentalacademy.com
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
Anteroposterior skeletal and dental changes after early Class II treatment with bionators and headgear Stephen D. Keeling (Am J Orthod Dentofacial Orthop1998)
In this study authors examined anteroposterior cephalometric changes in children enrolled in a randomized controlled trial of early treatment for Class II malocclusion. Children, aged 9.6Âą 6 0.8 years at the start of study, were randomly assigned to control (n= 581), bionator (n= 578), and headgear/biteplane (n =590) treatments. Cephalograms were obtained initially, after Class I molars were obtained or 2 years had elapsed, after an additional 6 months during which treated subjects were randomized to retention or no retention and after a final 6 months without appliances. www.indiandentalacademy.com
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
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
The results indicate that both the headgear and function regulator were effective in correcting the malocclusion
www.indiandentalacademy.com
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
Injuries have occurred with both removable & fixed appliances. Ranged in severity from minor lacerations to loss of eye. All occurred in children aged between 914 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
www.indiandentalacademy.com
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
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 â&#x20AC;&#x201C; 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
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 â&#x20AC;&#x201C; 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
www.indiandentalacademy.com
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
Shielded facebows â&#x20AC;&#x201C; 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 â&#x20AC;&#x201C; It has 2 omega bands so that it can easily adjusted to fit different lengths of buccal tubes.
www.indiandentalacademy.com
www.indiandentalacademy.com
It successfully reduced night time disengagement of facebow to less than 1%. Patients instructions â&#x20AC;&#x201C; 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
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
Patient Compliance An important aspect of using extra oral traction is whether appliance is being worn as instructed. Patientâ&#x20AC;&#x2122;s compliance can be improved if both parents & clinician provide motivation.
www.indiandentalacademy.com
Indicators 1) Patient keeps a daily diary of length of use. 2) Demonstrates skill in inserting facebow. 3) Mobility of teeth receiving traction force. 4) Parentral monitoring. 5) Soiled or recently cleaned neckstrap/headgear. www.indiandentalacademy.com
Conclusion To obtain desired dento skeletal effect with extra oral traction, type of appliance, amount of force, location of centers of resistance of teeth, maxilla & craniofacial type must be considered. Different subjects may respond differently to same type of extra oral traction. Cervical, combination & occipital face bow have similar A-P & vertical effects in growing patients.
www.indiandentalacademy.com
REFERENCES Valiathan Ashima, Gurjit Singh Randhawa & Jayan Joseph: Class II Division I treated non extraction with headgear, Journal of Indian Orthodontic Society, 1994; 25(1): 31-34. Suresh M and Ashima Valiathan: Asymmetric headgear treatment of Unilateral Class II div I malocclusion. Kerala Dental Journal 2000; 23(1): 1518. Ashima Valiathan and Amit Kumar Srivastava: Role of Kloehn headgear in class II â&#x20AC;&#x201C; Dental and skeletal correction. JICD 2000;47: 9-11. www.indiandentalacademy.com
Birte Melsen,and Michel Dalstra: Distal molar movement with Kloehn headgear:Is it stable. AJODO 2003;123:374-8) Leandro M. Piva, Helisio R. Leite, Maria O’ Reilly : Effects of cervical headgear & fixed appliances on space available for maxillary 2nd molar . AJODO 2005, 128(3);366-371. Haulabakis NB, Sifakakis IB: The effect of cervical headgear on patient with high or low mandibular plane angle and the ‘myth’ of posterior mandibular rotation. AJODO 2004,126;307 – 310.
www.indiandentalacademy.com
Serdar Usumez, Metin Orhan : Effect of cervical headgear wear on dynamic measurements of head position. EJO 2005 (27); 437-442. R.H.A. Samuels, N.Brezniak : Orthodontic facebows : safety issues and current management. J.O. 2002 (29) ; 101-107. Keith Godfrey : Extra oral retraction mechanics : a review. Aust. Ortho J 2004, 20; 31 â&#x20AC;&#x201C; 40.
www.indiandentalacademy.com
Kloehn SJ : Orthodontics â&#x20AC;&#x201C; force or persuasion. Angle Ortho 1953, 23; 56-65. Armstrong MM : Controlling the magnitude, duration & direction of extra oral force. AJO, 1971, 59 ; 217-243. Jacobson A; A key to understanding of extra oral forces. AJO 1979,75; 361-386. www.indiandentalacademy.com
Wieslander L; Long term effects of treatment with headgear-herbst appliance in early mixe dentiton. AJO 1993,104; 319-329. Hershey HG, Houghton CW, Burstone CJ; Unilateral facebows: a theoretical & laboratory analysis. AJO 1981; 79; 229-249. Nanda R : Biomechanics in clinical orthodontics. 1st edtn, Philadelphia, WB Saunders,1997; 130145. www.indiandentalacademy.com
Turner PJ: Extra oral traction. Dent Update. 1991;18;197-203. Firouz.M, Zernik J, Nanda R; Dental & orthopedic effects of high pull headgear in treatment of class II div I malocclusion. AJO, 1992;102; 197- 205. Graber TM; Extra oral force â&#x20AC;&#x201C; facts & fallacies. AJO 1955,41; 490-505. www.indiandentalacademy.com
Birte Melsen; Effects of cervical anchorage during and after treatment; An implant study. AJO 1978,73,5 ; 527-539. Gregory W. Hubbard, Ram S. Nanda, G. Frans Currier ; A cephalometric evaluation of non extraction treatment in class II malocclusion. Angle Ortho 1994,64 (5); 359-370. Charles T.Pavlick ; Cervical headgear usage & the Bioprogressive orthodontic philosophy. Semin. Ortho 1998, 4, 219-230.
www.indiandentalacademy.com
Bowden DE; Theoretical considerations of headgear therapy. A literature review. Mechanical principles . BJO 1978,5;145-152. Bowden DE; Theoretical considerations of headgear therapy. A literature review. Clinical response & Usage. BJO 1978,5; 173 â&#x20AC;&#x201C; 181. Contasti G, Legan HL; Biomechanical guidelines for headgear application. JCO 1982,16; 308312. www.indiandentalacademy.com
Tulloch JF, Proffit WR, Phillips C.Outcomes in a 2-phase randomized clinical trial of early Class II treatment. AJO 2004 Jun;125(6):657-67 . J. Ghafari, F. S. Shofer,b U. Jacobsson-Hunt, D. L. Markowitz, L.Lasterb - Headgear versus function regulator in the early treatment of Class II, Division 1 malocclusion:A randomized clinical trial. AJO 1998;113 (51-61.). Stephen D. Keeling, Timothy T. Wheeler, Gregory J. King, Cynthia W. Garvan - Anteroposterior skeletal and dental changes after early Class II treatment with bionators and headgear. AJO 1998;113:(40-50.).
www.indiandentalacademy.com
Sheldon Baumrind, Edward L. Korn,Robert J. Isaacson, Eugene E. West, Robert Molthen :Quantitative analysis of orthodontic and orthopedic effects of maxillary traction . AJO 1983 (84); 384-398. McNamara, Brudon; Orthodontics and dentofacial orthopedics. Pg â&#x20AC;&#x201C; 361 â&#x20AC;&#x201C; 375. 2 nd edtn, Needham press, Inc; Ann Arbor, Michigan.
www.indiandentalacademy.com
Thank you www.indiandentalacademy.com Leader in continuing dental education
www.indiandentalacademy.com