HERBST APPLIANCE
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INTRODUCTION Functional appliances developed primarily in Europe by many clinicians in an affort to stimulate mandibular growth, and aid in the correction of skeletal class-2 malocclusions. Lack of success with functional appliances has been attributed to lack of patient coperation in appliance wear and inability to control the amount and direction of mandibular growth. HERBST appliance designed by EMIL HERBST in 1905 and reintroduced by PANCHERZ attempts to adress these problems of patient non-compliance. www.indiandentalacademy.com
HISTORICAL PERSPECTIVE -Norman W Kigsley was the first to use the forward positioning of the mandible. -Pierre Robin first designed an appliance that was later used to influence muscular activity by change in the spatial relationship of jaws. -Alfred P Rogers recognised the importance of orofacial system in the problems of orthodontic treatment. -Viaggo Anderson designed an appliance that fitted loosely in the mouth and transferred muscular stimuli to the jaws ;teeth ;;supporting structures. www.indiandentalacademy.com
-In 1909 Emil Herbst presented a fixed bite jumping device called Sharnier or JOINT. IN 1977 Pancherz resorrected the HERBST appliance for use as an experimental tool in clinical research. In 1979 Pancherz in ajo called attention to the possibility for stimulation of mandibular growth by means of Herbst appliance. Since 1979 the Herbst appliance has gained increasing attention especially in europe and U.S.A’.
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HERBST appliance is a fixed bite jumping appliance.Bite jumping can be defined as a change in sagittal intermaxillary dental arch relationships by an anterior displacement of the mandible. The appliance is reported to produce both skeletal and dental changes in growing individuals. Appliance is compromised of telescopic mechanism with sliding pin and tube components which keep the mandible in protruded position.
Diagnostic criteria for case selection Growing patients with skeletal class-2 and dental class div-1 and 2 malocclusions.
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-Patients with retrognathic mandible & orthognathic maxilla with ANB OF 5 or greater. -Positive V.T.O. -WELL aligned maxillary and mandibular dental arches. -Favourably Y- axis . -Normal nasiolabial angle. -3mm or greater Witts appraisal. -upper incisor angulation to SN plane of 104 or greater. -lower incisal to mandibular plane of 95 or lesser. www.indiandentalacademy.com
INDICATIONS -Growing patients with skeletal and dental class-2 div 1&2 malocclusions. -patients with orthognathic maxilla and retrognathic mandible. -patients who have passed the pubertal growth spurt but still have some growth potential left in them. -in patients with mouth breathing habit. -uncoperative patients
CONTRAINDICATIONS www.indiandentalacademy.com
-Hyper divergent facial patterns. -abnormal mid face. -negative V.T.O.
DESIGN OF THE APPLIANCE It is a bilateral telescopic mechanism attached to orthodontic bands and keeps the mandible in an advanced position.Telescopic device consists of -TUBE; -PLUNGER; -TWO PIVOTS; -TWO LOCKING SCREWS. Pivot for the tube is attached tomaxillary first molar bands and pivot st for plunger is attached to mandibular 1 pre molar band. Length of www.indiandentalacademy.com
Length of the plunger should be kept at maximum to prevent it from disengaging from tube on wide mouth opening. The mechanism permits vertical opening movements and also lateral movements of the jaw.
ANCHORAGE SYSTEM OF THE HERBST APPLIANCE Conventionally in the maxillary arch the 1st premolars and permanent 1st molars are interconnected on each side with half round or roundsectional wire. In mandibular arch the 1 st premolar bands are connected with a round lingual wire that touches the lingual surfaces of front teeth.THIS FORM OF ANCHORAGE IS CALLED PARTIAL ANCHORAGE. In some instances this typewww.indiandentalacademy.com of anchorage is insufficient and there fore
In the maxillary arch labial sectional wire is placed in the brackets of premolars,canines,incisors.In the mandibular arch lingual sectional wire is extended to 1st permanent molars which are banded.This form of anchorage is called TOTAL ANCHORAGE. In the deciduous and mixed dentition period bonded type of herbst is used because of absense of 1st premolars.This system is called SPLINT ANCHORAGE SYSTEM. PELOTT ANCHORAGE system: in the mandibular arch with the lingual arch wires acrylic pelott is fabricated and fixed touching the lingual mucosa about 3mm below the gingival margin. This system is most efficient in withstanding the stresses plced on lower anterior teeth. www.indiandentalacademy.com
CONSTRUCTION OF THE APPLIANCE THE CONSTRUCTION BITE: Bite is recorded by motivating the patient to posture mandible forward in an edge to edge incisal position with midlines coinciding.If acrylic splints are needed care should be taken that sufficient vertical clearence is left for their construction. After the bite registration models are mounted on an articulator with the wax bite. CONSTRUCTION OF BONDED HERBST:All bands except those on the mandibular 1st molars should be formed of band material of 0.15mm thickness -construction bite is takenwww.indiandentalacademy.com with mandible advanced to desired position
And alginate impressions are made while bands are still on teeth. Bands are fixed in the impression and plaster models are poured .The banded models are oriented to each other in the construction bite and mounted in an articulator.Lingual arch wires and pivots for the telescopic mechanismare soldered to the bands. The finished appliance is cemented and telescopic mechanism is attached to the pivots using a screw driver . CONSTRUCTION OF BANDED HERBST:Acrylic splint herbst consists of a wire frame work over which 2.5-3.0mm of biocryl is pressure moulded using biostar .Posterior teeth are covered from canines through 1 st molars in the upper arch.Whereas full occlusal coverage is provided for the mandibular arch. www.indiandentalacademy.com
MAXILLARY WIRE FRAME WORK:Alength of 0.045 elgilloy wire is bent around the premolars and molars both on buccal and lingual side and transpalatal bar is included in the design to increase stability. MANDIBULAR WIRE FRAME WORK:0.40 INCCH ELGILLOY WIRE IS CONTOURED ALONG the buccal, lingual surfaces of six anterior teeth and posterior teeth. Both wire frame works are placed on their work models and secured. The pivots are oriented in correct horizontal ,vertical ,angular positions and then welded.after the skeletal wire frame work is ready biocryl sheet is adapted using biostar pressure moulding device. The splint is cemented with light cure resin system. www.indiandentalacademy.com
TREATMENT EFFECTS EFFECTS ON DENTOFACIAL COMPLEX: Herbst appliance is the most powerful treatment modality in the treatment of class-2 malocclusions. -normalization of oclusion is accomplished in 6-8 months of treatment.Overcorrected sagittal dental arch relations & incomplete cuspal interdigitation are expected at end of treatment. Improvement in sagittal & dental arch relations are result of both skeletal dental changes. Overjet was reduced by an average of 7mm &molar relationship improved by 6.5mm duringwww.indiandentalacademy.com treatment period.
During the 1st post treatment period of 6 months the overjet relapsed by 2mm &molar relation by 1.6mm. These occlusal changes were result of maxillary &mandibular tooth movements. Maxillary&mandibular growth were equal and did not contribute to the occlusal changes observed. -DURING 2ND POST treatment period of 6 months overjet recovered by .3mm while molar relation was almost unchanged. Maxillary &mandibular tooth movements were minimal .Mandibular growth was .2mm larger than maxillary growth & this counteracted negative effects of dental changes. EFFECTS ON MANDIBLE : In order to examine the short term & long term effects of herbst treatment on mandibular growth & www.indiandentalacademy.com
Mandibular morpholgy was assesed by measuring the jaw base length (C-PG) & GONIAL ANGLE & beta angle. During 6 months of treatment mancibular base length increased more in the Herbst group ,gonial angle opened & beta angle closed in the herbst group. At the end of growth the increase in mandibular base length was less than that in the control group. Gonial angle closed more in herbst group ,beta angle opened more in the herbst group.
MARKED mandibular morpholgical changes occurred during herbst treatment.After treatment these changes seemed to revert and on a long term basis no influence of herbst on mandibular morphology could be verified. www.indiandentalacademy.com
EFFECTS ON MAXILLA : 1.Sagittal maxillary jaw position changes: During the total observation period average amount of forward growth of maxilla was 3.6mm which was about half the forward growth in control group.Hence the appliance has a significant restraining effect on the growth of maxilla. 2. Palatal plane changes: During the total observation period palatal plane tipped downward by 1.1 degrees which was twice that seen in untreated controls. 3. Occlusal plane changes: On average occlusal plane tipped upward by .6mm during the total observation period which was half that seen in controls. www.indiandentalacademy.com
4. Sagittal maxillary molar position changes: During the total observation period the molar moved mesially by .6mm which was 60% that seen in untreated controls. 5. Vertical maxillary molar position changes: During the observation period molars intruded by 3.9mm which was comparable to that seen in controls. Conclusion was the appliance had marked high pull head gear effect on maxillary complex. Herbst appliance : 1. Stimulates mandibular growth 2. Inhibition of maxillary growth. 3.distal movement of upper teeth .4.Mesial movement of lower www.indiandentalacademy.com
EFFECTS ON FACIAL PROFILE: Herbst appliance treatment results in reduction of hard &soft tissue profile .upper lip becomes retrusive & whereas lower lip remains unchanged. EFFECTS ON MASTICATORY SYSYEM: -Patients adapt to appliance &accept it quikly despite the fact that at the beginning of treatment they have contact between anterior teeth .Chewing difficulties are experienced only during 1 st 7-10 days of treatment . -No adverse long term effects of appliance on craniomandibular system have been found during examination at end of their growth period . Treatment with herbst appliance normalizes EMG pattern of www.indiandentalacademy.com
Temporal &masseter muscles . Lateral tomograms of patients treated with herbst appliance have noted normal condyle - fossa relation ,however research indicates anterior positioning of articular fossa.TMJ remodelling ocurred with bony apposition at inferior border of anterior aspect of postglenoid fossa ,and at posterosuperior aspect of condyle. MULTI PHASE TREATMENT APPROACH: 1. Treatment of class 2 div-1 malocclusion : a. Orthopaedic phase
b . Orthodontic phase
2 .TREATMENT OF CLASS 2 DIV –2: www.indiandentalacademy.com
TIMING OF TREATMENT : Favourable time to start treatment is at peak of pubertal growth spurt . Pancherz recomendslate appliance therapy just after the peak of growth velocity to favour occlusal stability after treatment and to reduce post treatment retention . Early treatment is not recommended because stable cuspal interdigitation is difficult after appliance therapy and this prolongs retention period after appliance removal .
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RETENTION & RELAPSE Good post treatment occlusal intercuspation has been emphasized for the prevention of skeletal & dental relapse. Pancherz list of relapse promoting factors : 1. EARLY or MIXED DENTITION TREATMENT 2. ATYPICAL SWALLOWING HABITS . 3. RECOVERY GROWTH CHANGES AFTER TREATMENT. Treatmemt generally leads to over corrected sagittal dental arch relations with incomplete cuspal interdigitation .Thus a period of active retention is necessary with andreson activatoruntil www.indiandentalacademy.com the occlusion has settled into good intercuspation .
MODIFICATION IN HERBST APPLIANCE TREATMENT : In class –2 cases with narrow ,constricted maxillary arch expansion can be performed with herbst appliance by soldering quad helix or other rapid palatal expansion devices to the molar & premolar bands. If mandibular 1st premolars have not erupted permanent can be used for anchorage . Buccal tubes can be welded to mandibular molar bands for addition of franckel type lip pads which is usefull for correction of hyperactive mentalis muscle activity or alipbumper may be added to the buccal tubes to provide distalizing force to the mandibular dental arch. www.indiandentalacademy.com
Raymond weislander suggested the use of vertical pull chin cap or high pull head gear in case of patients with vertical hyperplasia of lower face along with herbst appliance . TAREK ZREIK ( JCO –1995) has modified the appliance to decrease the breakage problems with banded herbst appliance & called it as EMDEN modification .It includes : a. stainless steel crowns on maxillary 1st permanent molars. b. removable acrylic splint on mandibular arch . C .double buccal tubes on stainless steel crowns of upper 1 st permanent molars which can accommodate utility arches ,sectional or continuous wires. www.indiandentalacademy.com
Screws protrude enough to encroach upon mucosa of cheek & cause ulceration,to solve this problem HUG –CAPS are marketed which can cover screws . Sandblasting the underside of band or crown with microetcher increases the retention of appliance . American orthodontics has come out with photoetched bands with increased surface area . Photoetched bands with glass ionomer cement make loose bands a distant memory .
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FLIP LOCK HERBST
Flip-Lock Herbst appliance's ball-joint connector.
Split bushings used for reactivation.
End of rod crimped onto mandibular ball.
Split bushings used for reactivation.
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Buccal cantilever wire made by doubling .045" wire and soldering the two strands together.
Cantilever Herbst design.
Mandibular acrylic matrix Herbst design. Atlas Axle with tube and piston hela togetner by cotter pin. www.indiandentalacademy.com
Herbst appliance with hexagonal screws.
. Maxillary Malu attachment with cotter pin
opening. B. Mandibular Malu attachment with archwire slot and cotter pin opening.
Assembled Herbst with Malu attachments. www.indiandentalacademy.com
. Sliding auxiliary archwire, made of .9-1mm round stainless steel, inserted
in lower first molar tube. B. Force of Herbst appliance distributed to main mandibular archwire by auxiliary archwire.
Auxiliary archwire attached anteriorly to main archwire with elastomeric modules. B. Posted mandibular archwire. www.indiandentalacademy.com
Different hooks of .9-1mm stainless steel wire used to attach Herbst tubes to upper first molar bands, depending on space available between upper and lower first molars.
Malu attachment, combined with stopped wire, used to attach Herbst tube to upper first molar band. www.indiandentalacademy.com
. In skeletal open bite case, upper second molar is banded and Herbst tube is attached as far
distally as possible. This increases distance from assumed center of resistance of maxillary dentition (CR ud) to attachment point of Herbst tube, increasing length of moment arm of intrusive force from Herbst appliance. B. Placing tube too far distally can cause interference with masseter muscle (pars superficialis).
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. Coelho design, using 1.5mm-diameter rod attached to upper first molar and sliding freely along auxiliary archwire. B. Tube added to auxiliary archwire distal to stop in lower canine area to increase mandibular advancement.
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Removable Plastic Herbst retainer, with upper and lower occlusal splints connected by the herbst mechanism. www.indiandentalacademy.com
Components of Mandibular Advancement Locking Unit (MALU).
Upper "Mobee" hinge inserted into hole on tube and secured to headgear tube with ball pin.
Lower key hinge inserted into hole on plunger With upper and lower MALU components in place, len of tube-plunger assembly is adjusted according to and locked to base arch with brass pin. www.indiandentalacademy.com desired mandibular protrusion.
CONCLUSIONS
If your only instrument is hammer than every problem looks like anail. Similarly if only orthodontic tool for treating class-2 malocclusions is a retractor then every class-2 will seem like amaxillary protrusion and clearly not every one is.
Herbst appliance is not a theraupeutic panacea but when diagnosis and patient selection are accurate it can routinly treat difficult non co-operative class –2 patients successfully. www.indiandentalacademy.com
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