Fixed fuctional appliances

FIXED FUNCTIONALFIXED FUNCTIONAL
APPLIANCESAPPLIANCES

INTRODUCTIONINTRODUCTION
 Class II malocclusions form a sizeableClass II malocclusions form a sizeable
number of patients treated by orthodontistnumber of patients treated by orthodontist
 Class II malocclusions can be caused by :Class II malocclusions can be caused by :
 Tooth migration (Dentoalveolar)Tooth migration (Dentoalveolar)
 Retrognathic mandible and normal maxillaRetrognathic mandible and normal maxilla
 Prognathic maxilla and normal mandiblePrognathic maxilla and normal mandible
 Combination of aboveCombination of above

 Mandibular retrusion is the single mostMandibular retrusion is the single most
common element in the production of acommon element in the production of a
Class II malocclusion which is oftenClass II malocclusion which is often
treated with the employment oftreated with the employment of
functional jaw orthopedic appliancesfunctional jaw orthopedic appliances

Functional applianceFunctional appliance
 AA removable or a fixed applianceremovable or a fixed appliance thatthat
alters the position of mandible andalters the position of mandible and
transmits the forces created by thetransmits the forces created by the
resulting stretch of the muscles and softresulting stretch of the muscles and soft
tissues and by the change of thetissues and by the change of the
neuromuscular environment to the dentalneuromuscular environment to the dental
and skeletal soft tissues to produceand skeletal soft tissues to produce
movement of teeth and modification ofmovement of teeth and modification of
growth.growth.

Growth modification Patient cooperation
Practice Management

Patient cooperation
Appliances used during early treatment can be divided
into three categories depending upon amount of
patient cooperation
1. Minimal cooperation e g: fixed appliances
2. Mild to moderate cooperation e g. Removable
appliance that is not functional in nature
3. Maximal cooperation: e g. removable functional
appliances and extra oral appliances.

 Removable functional jaw orthopedicRemovable functional jaw orthopedic
appliances achieve correction based onappliances achieve correction based on
patient cooperation and wear of thepatient cooperation and wear of the
appliance.appliance.
 Orthodontists in a bid to overcome the humanOrthodontists in a bid to overcome the human
element of patient cooperation researchedelement of patient cooperation researched
literature and envisioned the idea of a fixedliterature and envisioned the idea of a fixed
functional appliancefunctional appliance

ClassificationClassification
 According to the forces produced:According to the forces produced:
 Appliances producing pushing forcesAppliances producing pushing forces
 Appliances producing pulling forcesAppliances producing pulling forces

 Appliances producing Pushing forces:Appliances producing Pushing forces:
 These appliances deliver a pushing forceThese appliances deliver a pushing force
vector forcing the attachment points of thevector forcing the attachment points of the
appliance away from one anotherappliance away from one another

Appliances producing Pushing forces:Appliances producing Pushing forces:
Rigid:Rigid:
 1. Herbst Appliance and its modifications.1. Herbst Appliance and its modifications.
 2. Mandibular advancement repositioning splint2. Mandibular advancement repositioning splint
 3. Mandibular protraction appliance3. Mandibular protraction appliance
 4. Eureka Spring4. Eureka Spring
 5. Universal Bite Jumper5. Universal Bite Jumper
 6. Biopedic6. Biopedic
 7. Mandibular anterior repositioning appliance7. Mandibular anterior repositioning appliance

Appliances producing Pushing forces:Appliances producing Pushing forces:
 FlexibleFlexible::
 Jasper JumperJasper Jumper
 Churro JumperChurro Jumper
 Adjustable Bite CorrectorAdjustable Bite Corrector
 Klapper Super Spring IIKlapper Super Spring II
 ForsusForsus

Appliances Producing Pulling ForceAppliances Producing Pulling Force
 These appliances create a pulling forceThese appliances create a pulling force
vector between the points of attachment:vector between the points of attachment:
 SAIFSAIF (Sever able Adjustable intermaxillary(Sever able Adjustable intermaxillary
Force) springForce) spring
 Rick – A – NatorRick – A – Nator

Herbst ApplianceHerbst Appliance
 History, Background and DevelopmentHistory, Background and Development
 DesignDesign
 Anchorage forms of the Herbst ApplianceAnchorage forms of the Herbst Appliance
 ConstructionConstruction
 Effects on Dentofacial ComplexEffects on Dentofacial Complex
 Effects on facial profileEffects on facial profile
 Effects on masticatory systemEffects on masticatory system
 Mandibular anchorage problemsMandibular anchorage problems
 IndicationsIndications
 TimingTiming
 RetentionRetention

History, Background andHistory, Background and
DevelopmentDevelopment
 Developed byDeveloped by Emil HerbstEmil Herbst (1872 – 1940) in 1900s.(1872 – 1940) in 1900s.
 Herbst presented his appliance (original bandedHerbst presented his appliance (original banded
design) for the first time at the 5design) for the first time at the 5thth
international Dentalinternational Dental
Congress in Berlin in 1909.Congress in Berlin in 1909.
 It’s a fixed bite jumping device ( bite jumping is theIt’s a fixed bite jumping device ( bite jumping is the
production of a change in the sagittal intermaxillaryproduction of a change in the sagittal intermaxillary
jaw relationship by the anterior displacement of thejaw relationship by the anterior displacement of the
mandiblemandible

 Herbst employed the appliance most usefullyHerbst employed the appliance most usefully
in the following instancesin the following instances::
 Patients with Class II malocclusions andPatients with Class II malocclusions and
retrognathic mandiblesretrognathic mandibles
 In the facilitating of healing after mandibularIn the facilitating of healing after mandibular
ramus fractures.ramus fractures.
 As an artificial joint after surgical resection of theAs an artificial joint after surgical resection of the
condylar headcondylar head
 In patients with TMJ problems such as clickingIn patients with TMJ problems such as clicking
and bruxism.and bruxism.

 He called his applianceHe called his appliance
““OkklusionsscharnierOkklusionsscharnier””
oror
““RetentionsscharnierRetentionsscharnier ””
 After 1934 very little was published about the HerbstAfter 1934 very little was published about the Herbst
appliance until it was rediscovered by Hans Pancherzappliance until it was rediscovered by Hans Pancherz
of Malmo, Sweden in the late 1970’s.of Malmo, Sweden in the late 1970’s.
 In 1977, Pancherz resurrected Herbst appliance forIn 1977, Pancherz resurrected Herbst appliance for
use as an experimental tool in clinical researchuse as an experimental tool in clinical research

 Advantages of Herbst applianceAdvantages of Herbst appliance ::
 It is fixed to the teethIt is fixed to the teeth
 Patient compliance is not required for its correctPatient compliance is not required for its correct
functionfunction
 Works 24 hrs a dayWorks 24 hrs a day
 Treatment time is short app. 6 to 8monthsTreatment time is short app. 6 to 8months

DesignDesign
 AA bilateral telescopic mechanismbilateral telescopic mechanism attached toattached to
orthodontic bands which keeps the mandible aheadorthodontic bands which keeps the mandible ahead
in an anterior jumped positionin an anterior jumped position

 Each telescope consists of a tube, a plunger,Each telescope consists of a tube, a plunger,
2 pivots (axle), and two locking screws that2 pivots (axle), and two locking screws that
prevent the telescoping parts from slippingprevent the telescoping parts from slipping
past the pivots.past the pivots.

 Originally the telescoping parts of the HerbstOriginally the telescoping parts of the Herbst
appliance were curved conforming to Curveappliance were curved conforming to Curve
of spee, they were ,made of German Silverof spee, they were ,made of German Silver

 Pivot for the tube is attached to he maxillary 1Pivot for the tube is attached to he maxillary 1stst
molarmolar
band while that for the plunger is usually attached toband while that for the plunger is usually attached to
the mandibular 1the mandibular 1stst
premolar bandspremolar bands
 Length of the tube determines the amount of biteLength of the tube determines the amount of bite
jumping. Usually the mandible is retained in an incisaljumping. Usually the mandible is retained in an incisal
edge to edge relationshipedge to edge relationship..

Original Herbst ApplianceOriginal Herbst Appliance
 Originally Herbst as placing the telescope mechanismOriginally Herbst as placing the telescope mechanism
upside down (with plunger attached to the maxillaryupside down (with plunger attached to the maxillary
molar crown and the tube on the mandibular caninemolar crown and the tube on the mandibular canine
crown).crown).
 Tube had no open end , thus not allowing the plungerTube had no open end , thus not allowing the plunger
to extend behind the tube.to extend behind the tube.

 Length of the plunger should be kept at a maximumLength of the plunger should be kept at a maximum
to prevent it from disengaging from the tube.to prevent it from disengaging from the tube.
 A large interpivot distance prevents the plunger fromA large interpivot distance prevents the plunger from
slipping out of the tube when the mouth is openedslipping out of the tube when the mouth is opened
wide.wide.
 A plunger too far behind the tube can injure theA plunger too far behind the tube can injure the
buccal mucosa.buccal mucosa.
 If plunger disengages from the tube on mouthIf plunger disengages from the tube on mouth
opening , it may get stuck in the tube opening onopening , it may get stuck in the tube opening on
subsequent mouth closure and damage thesubsequent mouth closure and damage the

The Herbst ApplianceThe Herbst Appliance
 The Herbst appliance has undergoneThe Herbst appliance has undergone
some changes in its original design butsome changes in its original design but
since the seventies has maintained itssince the seventies has maintained its
general shape with only a fewgeneral shape with only a few
modifications taking place with regard tomodifications taking place with regard to
methods of application (Type I, II and IV).methods of application (Type I, II and IV).

 Type I is characterized byType I is characterized by
a fixing system to thea fixing system to the
crowns or bands throughcrowns or bands through
the use of screws. This isthe use of screws. This is
the most common form. Itthe most common form. It
is necessary to weld theis necessary to weld the
axles to the bands oraxles to the bands or
crowns and then fix thecrowns and then fix the
tubes and plungers withtubes and plungers with
the screwsthe screws

 Type II has a fixing system thatType II has a fixing system that
fits directly onto the archwiresfits directly onto the archwires
through the use of screws.through the use of screws.
This method of application hasThis method of application has
the disadvantage of causingthe disadvantage of causing
constant fractures in theconstant fractures in the
archwires. The lack of flexibilityarchwires. The lack of flexibility
together with the difficulty intogether with the difficulty in
lateral movements and thelateral movements and the
stress placed on the archwiresstress placed on the archwires
through activation causesthrough activation causes
fractures, especially in thefractures, especially in the
lower archlower arch

 Type IV has a fixation systemType IV has a fixation system
with a ball attachment, whichwith a ball attachment, which
allows greater flexibility andallows greater flexibility and
freedom of mandibularfreedom of mandibular
movement. A disadvantage inmovement. A disadvantage in
relation to other similarrelation to other similar
appliances is the fact that itappliances is the fact that it
needs brakes to stabilize theneeds brakes to stabilize the
joint. The brakes are small andjoint. The brakes are small and
sometime difficult to fit. Whensometime difficult to fit. When
a fracture occurs or a brake isa fracture occurs or a brake is
lost, the appliance comeslost, the appliance comes
looseloose

Anchorage forms of the HerbstAnchorage forms of the Herbst
applianceappliance
 Deserves special attention.Deserves special attention.
 Because of anchorage loss, maxillary andBecause of anchorage loss, maxillary and
mandibular tooth movements cannot be avoidedmandibular tooth movements cannot be avoided
 Several anchorage systems have beenSeveral anchorage systems have been
developed to control unwanted toothdeveloped to control unwanted tooth
movements.movements.

a)a) Anchorage forms used from 1909 to 1934:Anchorage forms used from 1909 to 1934:
- Standard anchorage system of HerbstStandard anchorage system of Herbst
- Early mixed dentition anchorage systemEarly mixed dentition anchorage system
- Late mixed dentition anchorage systemLate mixed dentition anchorage system

Standard anchorage systemStandard anchorage system
When 2nd
molars have nor erupted

 Early mixed dentition anchorage system:Early mixed dentition anchorage system:

 Late mixed dentition anchorage systemLate mixed dentition anchorage system ::
Canines are used as anchorage teeth insteadCanines are used as anchorage teeth instead
of incisors.of incisors.
Buccal mucosa a the corner of the mouth isBuccal mucosa a the corner of the mouth is
prone to ulceration when mandibular canineprone to ulceration when mandibular canine
is used as an abutment tooth for the plunger.is used as an abutment tooth for the plunger.

 Schwarz( 1934):Schwarz( 1934): Most teeth in the maxilla andMost teeth in the maxilla and
mandible were interconnected by labial asmandible were interconnected by labial as
well as lingual arch wires(well as lingual arch wires( Block anchorageBlock anchorage))
 Necessity of incorporating as many teeth asNecessity of incorporating as many teeth as
possible for anchorage to avoid unwantedpossible for anchorage to avoid unwanted
side effects was realized early by bothside effects was realized early by both
Herbst and othersHerbst and others..

 Anchorage forms used from 1979Anchorage forms used from 1979
onwardonward::
Pancherz originally used a banded type of HerbstPancherz originally used a banded type of Herbst
appliance.Individually made stainless steel bandsappliance.Individually made stainless steel bands
of a thick material (0.15- 0.18mm) were used.of a thick material (0.15- 0.18mm) were used.
1.1. Simple anchorage systemSimple anchorage system
2.2. Increased anchorage systemIncreased anchorage system
3.3. Total anchorage systemTotal anchorage system
4.4. Pellot anchoragePellot anchorage
5.5. Class III elasticsClass III elastics

1.1. Simple anchorage systemSimple anchorage system ::
 MaxillaMaxilla- Bands are placed on 1- Bands are placed on 1stst
permanent molars and firstpermanent molars and first
premolars.Joined on each side bypremolars.Joined on each side by
sectional arch wires.sectional arch wires.
 MandibleMandible- Premolars are banded and- Premolars are banded and
connected with a lingual sectional archconnected with a lingual sectional arch
 DisadvantagesDisadvantages::
 Space opening distal to maxillarySpace opening distal to maxillary
caninescanines
 Excessive intrusion of 1Excessive intrusion of 1stst
permanentpermanent
molars.molars.
 Buccal tipping of 1Buccal tipping of 1stst
premolarspremolars
 Intrusion of lower 1Intrusion of lower 1stst
molarsmolars
 Large proclination of lower anteriorsLarge proclination of lower anteriors

22.. IncreasedIncreased
anchorage systemanchorage system
 Maxillary and mandibularMaxillary and mandibular
front teeth werefront teeth were
incorporated in theincorporated in the
anchorage system by labialanchorage system by labial
sectional arch wires.sectional arch wires.
 Mandibular lingual arch wireMandibular lingual arch wire
extended to 1extended to 1stst
permanentpermanent
molarsmolars..

3.3.Total anchorage systemTotal anchorage system ::
 Utilized with cast chromium cobaltUtilized with cast chromium cobalt
splints.splints.
 Splints cover all buccal teeth in theSplints cover all buccal teeth in the
maxillary and mandibular archesmaxillary and mandibular arches
and also the mandibular canines.and also the mandibular canines.
 In addition the upper and lowerIn addition the upper and lower
front teeth are included in thefront teeth are included in the
anchorage system by way of labialanchorage system by way of labial
arch wires that are connected to thearch wires that are connected to the
splints.splints.

4.4. Pellot anchoragePellot anchorage ::
 11stst
premolars and permanentpremolars and permanent
11stst
molars were banded andmolars were banded and
connected with a lingual archconnected with a lingual arch
wirewire
 Acrylic pellot in front of lingualAcrylic pellot in front of lingual
arch wire touching the lingualarch wire touching the lingual
mucosamucosa..
 Severe ulceration of the lingualSevere ulceration of the lingual
mucosa can occur.mucosa can occur.

5. Class III elastics :5. Class III elastics :

 Pancherz and Hansen(1988)Pancherz and Hansen(1988) :: AnalyzedAnalyzed
the efficiency of 5 mandibular anchoragethe efficiency of 5 mandibular anchorage
systems in the Herbst treatment. Results ofsystems in the Herbst treatment. Results of
the study indicated that:the study indicated that:
 None of the 5 anchorage systems used inNone of the 5 anchorage systems used in
Herbst treatment could prevent anteriorHerbst treatment could prevent anterior
movement of the mandibular incisors andmovement of the mandibular incisors and
molars.molars.

 Lower anchorage is a problem difficult to masterLower anchorage is a problem difficult to master
in Herbst treatment. Some factors associatedin Herbst treatment. Some factors associated
with anchor loss can be :with anchor loss can be :
 Severity of A-P interarch discrepancySeverity of A-P interarch discrepancy
 Amount of bite jumping at the start of treatment.Amount of bite jumping at the start of treatment.

Construction of banded Herbst applianceConstruction of banded Herbst appliance
 Important considerationsImportant considerations::
 All bands except those on mandibular molars shouldAll bands except those on mandibular molars should
be formed individually of orthodontic material at leastbe formed individually of orthodontic material at least
0.15mm in thickness.0.15mm in thickness.
 Upper and lower pivots on each side should beUpper and lower pivots on each side should be
placed parallel to each other. This will provide aplaced parallel to each other. This will provide a
correct and smooth function of the telescopiccorrect and smooth function of the telescopic
mechanism.mechanism.

 Upper pivots should be placed distally onUpper pivots should be placed distally on
the molar bands and the lower pivotsthe molar bands and the lower pivots
mesially on the premolar bands.mesially on the premolar bands.
 Pivot openings on the tube and plungerPivot openings on the tube and plunger
should be widenedshould be widened

The Banded Herbst ApplianceThe Banded Herbst Appliance

Cast splint Herbst applianceCast splint Herbst appliance
 Bands are replaced by splints cast from a cobaltBands are replaced by splints cast from a cobalt
chromium alloy and cemented to teeth with GIC.chromium alloy and cemented to teeth with GIC.
 Upper & lower teeth are incorporated into theUpper & lower teeth are incorporated into the
anchorage through the addition of sectional archanchorage through the addition of sectional arch
wires.wires.

Cast splint Herbst applianceCast splint Herbst appliance
 AdvantagesAdvantages::
 Ensures precise fit onEnsures precise fit on
the teeth.the teeth.
 Strong and hygienic.Strong and hygienic.
 Saves chair time.Saves chair time.
 Causes very few clinicalCauses very few clinical
problems.problems.
 DisadvantagesDisadvantages::
 Tooth adjustments &Tooth adjustments &
interocclusalinterocclusal
adjustments duringadjustments during
treatment aretreatment are
prevented.prevented.
 UnhygienicUnhygienic
construction.construction.
 Bonding material isBonding material is
difficult to removedifficult to remove

A.A. EFFECTS ON DENTOFACIAL COMPLEXEFFECTS ON DENTOFACIAL COMPLEX
 Perhaps more than any other type of functionalPerhaps more than any other type of functional
appliance, whether fixed or removable in design, theappliance, whether fixed or removable in design, the
treatment effects produced by the Herbst appliancetreatment effects produced by the Herbst appliance
have been well documented.have been well documented.
 The effects on dentofacial complex can beThe effects on dentofacial complex can be
discussed under:discussed under:
 Treatment effectsTreatment effects
 Early post treatment effects.Early post treatment effects.
 Late post treatment effects.Late post treatment effects.

1.1. Treatment effectsTreatment effects
 Improvement in sagittal and vertical occlusalImprovement in sagittal and vertical occlusal
relationships during treatment is a result of bothrelationships during treatment is a result of both
skeletal and dental changesskeletal and dental changes (Pancherz, 1982)(Pancherz, 1982)..
 a.a. Sagittal changesSagittal changes:: Skeletal changesSkeletal changes
Dental changes.Dental changes.

I. Skeletal:I. Skeletal:
 1. Restrains maxillary growth and decrease of SNA1. Restrains maxillary growth and decrease of SNA
angle.angle.
 This may be explained by growth processes in theThis may be explained by growth processes in the
cranial base displacing the nasion (N) point morecranial base displacing the nasion (N) point more
anteriorly, thus apparently decreasing the SNA angleanteriorly, thus apparently decreasing the SNA angle
and giving an exaggerated picture of the treatmentand giving an exaggerated picture of the treatment
changes accomplished.changes accomplished.

 2.2. Increases mandibular lengthIncreases mandibular length::
 (Pancherz 1979, 1981, 1982)(Pancherz 1979, 1981, 1982) . This finding is in. This finding is in
agreement with several bite jumping experiments inagreement with several bite jumping experiments in
growing monkeysgrowing monkeys (Stockle and Willert 1971,(Stockle and Willert 1971,
McNamara 1972, 1973, 1975)McNamara 1972, 1973, 1975) and ratsand rats
(Petrovic and Stutzman 1969)(Petrovic and Stutzman 1969) , where it has, where it has
been shown that the condylar cartilage was capablebeen shown that the condylar cartilage was capable
of a compensatory tissue response following anof a compensatory tissue response following an
anterior displacement of mandible.anterior displacement of mandible.

 2a.2a. Evidence of temporomandibular growthEvidence of temporomandibular growth
adaptations in Herbst treatmentadaptations in Herbst treatment::
 The mechanism by which TMJ responds to functionalThe mechanism by which TMJ responds to functional
appliance therapy is a matter of controversy.appliance therapy is a matter of controversy.
Histologically several mandibular protrusionHistologically several mandibular protrusion
experiments in growing animals haveexperiments in growing animals have demonstrateddemonstrated
that condylar growth can be stimulated and that thethat condylar growth can be stimulated and that the
glenoid fossa can be remodeled..glenoid fossa can be remodeled..

 Three adaptive processes in the TMJ are thought toThree adaptive processes in the TMJ are thought to
contribute to the changes of mandibular positioncontribute to the changes of mandibular position
 1) condylar remodeling.1) condylar remodeling.
 (2)Glenoid fossa remodeling;(2)Glenoid fossa remodeling;
 (3) condylar position changes within the fossa(3) condylar position changes within the fossa..

Animal studiesAnimal studies
 Peterson and McNamara (2003) :Peterson and McNamara (2003) :
 Evaluated histologically the TMJ, glenoid fossa, andEvaluated histologically the TMJ, glenoid fossa, and
the posterior border of the mandible in juvenilethe posterior border of the mandible in juvenile
Rhesus monkeys whose mandibles had beenRhesus monkeys whose mandibles had been
positioned forward with a Herbst appliance. Thepositioned forward with a Herbst appliance. The
results of this study indicate that both condylarresults of this study indicate that both condylar
temporal bone and mandibular ramus adaptationstemporal bone and mandibular ramus adaptations
occur after placement of the Herbst appliance. Theoccur after placement of the Herbst appliance. The
following adaptations were observed:-following adaptations were observed:-

 Increased proliferation of condylar cartilage wasIncreased proliferation of condylar cartilage was
noted. It occurred primarily in the posterior andnoted. It occurred primarily in the posterior and
posterosuperior regions of the condyle.posterosuperior regions of the condyle.
 Significant deposition of new bone on the anteriorSignificant deposition of new bone on the anterior
surface of the postglonoid spine (vertical structuresurface of the postglonoid spine (vertical structure
that is located just anterior to the external auditorythat is located just anterior to the external auditory
meatus) occurred, indicating and anteriormeatus) occurred, indicating and anterior
repositioning of the glenoid fossa.repositioning of the glenoid fossa.
 Significant bone resorption on the posterior surface ofSignificant bone resorption on the posterior surface of
the postglenoid spine was noted.the postglenoid spine was noted.

 Significant bony apposition on the posteriorSignificant bony apposition on the posterior
border of the mandibular ramus was evidentborder of the mandibular ramus was evident
during early experimental periods.during early experimental periods.
 No gross or microscopic pathologicalNo gross or microscopic pathological
changes were noted in TMJ of the juvenilechanges were noted in TMJ of the juvenile
Rhesus monkey.Rhesus monkey.

CLINICAL STUDIES:CLINICAL STUDIES:
 They have provided radiographic evidence of TMJThey have provided radiographic evidence of TMJ
growth adaptation in Herbst treatment.growth adaptation in Herbst treatment.
 Magnetic resonance imaging (MRI), is a non invasiveMagnetic resonance imaging (MRI), is a non invasive
technique which allows a valid and reproducibletechnique which allows a valid and reproducible
assessment of articular joint cartilage morphology. Dueassessment of articular joint cartilage morphology. Due
to its superior sensitivity for detection of unmineralizedto its superior sensitivity for detection of unmineralized
tissue, MRI can be used to visualize cartilage changes attissue, MRI can be used to visualize cartilage changes at
on early stage.on early stage.

 Paulsen et al (1995)Paulsen et al (1995) ::
 Analysed TMJ changes in a single case of HerbstAnalysed TMJ changes in a single case of Herbst
treatment in late puberty using CT scanning andtreatment in late puberty using CT scanning and
OPG.OPG.
 Three months after insertion of the appliance CT-Three months after insertion of the appliance CT-
scanning and OPGs of the TMJ revealed new bonescanning and OPGs of the TMJ revealed new bone
formation as a double contour in the articular fossaformation as a double contour in the articular fossa
and on the posterior part of the condylar process as aand on the posterior part of the condylar process as a
result of adaptive bone remodeling.result of adaptive bone remodeling.

 On TMJ readiographs a double contour of the fossaOn TMJ readiographs a double contour of the fossa
outline have been demonstrated in some patientsoutline have been demonstrated in some patients
(Pancherz, 1979; Weislander, 1984(Pancherz, 1979; Weislander, 1984 )) whichwhich
possibility indicates anterior transformation of the fossa.possibility indicates anterior transformation of the fossa.
 Paulsen (1995)Paulsen (1995) :: Evaluated orthopaedic effects ofEvaluated orthopaedic effects of
Herbst treatment on the morphology of the condyleHerbst treatment on the morphology of the condyle
using OPGs and transpharyngeal radiographs. Theusing OPGs and transpharyngeal radiographs. The
orthopaedic treatment effect was, in most cases, visibleorthopaedic treatment effect was, in most cases, visible
as a change in morphology of the condyle, a doubleas a change in morphology of the condyle, a double
contour in the distocranial part of thecontour in the distocranial part of the

 Condyle and sometimes at the distal surface ofCondyle and sometimes at the distal surface of
ramus. The change in morphology and the doubleramus. The change in morphology and the double
contour of the condyle can be interpreted as bonecontour of the condyle can be interpreted as bone
remodeling. The newly formed bone on the posteriorremodeling. The newly formed bone on the posterior
part of the condyle can be explained as a responsepart of the condyle can be explained as a response
to hypertrophic chondrocytes, and that on theto hypertrophic chondrocytes, and that on the
posterior part of ramus as a response of restingposterior part of ramus as a response of resting
osteoblasts to mechanically induced changes in theosteoblasts to mechanically induced changes in the
condyle.condyle.

 Ruf and Pancherz (1998, 1999):Ruf and Pancherz (1998, 1999):
 Analysed three possible adaptive TMJAnalysed three possible adaptive TMJ
growth processes contributing to increase ingrowth processes contributing to increase in
mandibular prognathism accomplished bymandibular prognathism accomplished by
Herbst treatment :Herbst treatment :
 Condylar remodelingCondylar remodeling
 Glenoid fossa remodelingGlenoid fossa remodeling
 Condyle fossa relationship changes.Condyle fossa relationship changes.

 These changes were analyzed by means of MRI. After 6-These changes were analyzed by means of MRI. After 6-
12 weeks of treatment MRI signs of condylar remodeling12 weeks of treatment MRI signs of condylar remodeling
were seen at the posterosuperior border of the condyleswere seen at the posterosuperior border of the condyles
in the form of increase in MRI signal intensity onin the form of increase in MRI signal intensity on
posterosuperior aspect of condyle.posterosuperior aspect of condyle.
 MRI signs of glenoid fossa remodeling were seen atMRI signs of glenoid fossa remodeling were seen at
anterior surface of postglenoid spine. The condyle fossaanterior surface of postglenoid spine. The condyle fossa
relationship was, on average unaffected by Herbstrelationship was, on average unaffected by Herbst
therapy.therapy.

 It has been shown that during mandibular condylarIt has been shown that during mandibular condylar
growth, cartilage matrix production exceedsgrowth, cartilage matrix production exceeds
chondrocyte enlargementchondrocyte enlargement ((Booshardt Leuhrs andBooshardt Leuhrs and
Luder, 1991Luder, 1991).). The volume of cartilage matrixThe volume of cartilage matrix
depends to a considerable degree on its extensivedepends to a considerable degree on its extensive
water content. In water, hydrogen is very susceptivewater content. In water, hydrogen is very susceptive
to the effects of magnetic field in MRI due to highto the effects of magnetic field in MRI due to high
electronegativity of the oxygen.electronegativity of the oxygen.
 Therefore increase in MRI signal intensity indicatesTherefore increase in MRI signal intensity indicates
increase in water content of the tissue which is a signincrease in water content of the tissue which is a sign
of active condylar growth. Moreover increase in MRIof active condylar growth. Moreover increase in MRI
signal at 6-12 weeks correspond in time to changessignal at 6-12 weeks correspond in time to changes
reported in the histologic animal studiesreported in the histologic animal studies

 (Mc Namara and Carlson, 1979)(Mc Namara and Carlson, 1979) ..
 Condylar remodeling seemed to precede fossaCondylar remodeling seemed to precede fossa
remodeling. An explanation for the delayedremodeling. An explanation for the delayed
visualization of the adaptive response of glenoidvisualization of the adaptive response of glenoid
fossa remodeling might be the difference betweenfossa remodeling might be the difference between
adaptive process of the temporal bone (periostealadaptive process of the temporal bone (periosteal
ossification) and the condyle (endochondralossification) and the condyle (endochondral
ossification); the periosteal ossification is notossification); the periosteal ossification is not
associated with large increases in water content andassociated with large increases in water content and
does not result in a marked change in MRI signaldoes not result in a marked change in MRI signal
intensity. Therefore, the bone apposition along theintensity. Therefore, the bone apposition along the
post glenoid spine is visualized later in MRI, at thepost glenoid spine is visualized later in MRI, at the
time when the newly formed bone is consolidated.time when the newly formed bone is consolidated.

 The results indicate that condylar as well asThe results indicate that condylar as well as
glenoid fossa remodeling seem to contributeglenoid fossa remodeling seem to contribute
significantly to the increase in mandibularsignificantly to the increase in mandibular
prognathism resulting from Herbst treatment,prognathism resulting from Herbst treatment,
while condyle fossa relationship are of lesswhile condyle fossa relationship are of less
importance.importance.

2b. Effective condylar growth (Amount and2b. Effective condylar growth (Amount and
direction) during Herbst treatment:direction) during Herbst treatment:
 Effective condylar growth is a summation of condylarEffective condylar growth is a summation of condylar
growth, glenoid fossa displacement and condylargrowth, glenoid fossa displacement and condylar
position changes within fossa.position changes within fossa.
 Pancherz, Ruf and Kohlas (1998)Pancherz, Ruf and Kohlas (1998) indicated thatindicated that
during Herbst treatment period, effective condylar growthduring Herbst treatment period, effective condylar growth
was relatively more backward directed and about threewas relatively more backward directed and about three
times larger than in untreatedtimes larger than in untreated subjects with idealsubjects with ideal
occlusion.occlusion.

 Ruf and Pancherz (1998, 1999)Ruf and Pancherz (1998, 1999) ::
 Analysed effective condylar growth with aid of pre andAnalysed effective condylar growth with aid of pre and
post treatment lateral cephalometric roentgenograms.post treatment lateral cephalometric roentgenograms.
Effective condylar growth during treatment was onEffective condylar growth during treatment was on
average approximately 5 times larger in the Herbstaverage approximately 5 times larger in the Herbst
group than in an untreated group with ideal occlusiongroup than in an untreated group with ideal occlusion
and direction of growth changes was relatively moreand direction of growth changes was relatively more
horizontal in the treated cases.horizontal in the treated cases.

 Pancherz and Fischer (2003):Pancherz and Fischer (2003):
 Conducted long term cephalometric study in patientsConducted long term cephalometric study in patients
treated with Herbst appliance. Analyzed amount andtreated with Herbst appliance. Analyzed amount and
displacement of condylar growth and glenoid fossadisplacement of condylar growth and glenoid fossa
displacement as single components as well asdisplacement as single components as well as
combination of three adaptive TMJ adaptivecombination of three adaptive TMJ adaptive
components (effective condylar growth). Duringcomponents (effective condylar growth). During
treatment period condylar growth was directedtreatment period condylar growth was directed
posteriorly about twice the amount as in the controlposteriorly about twice the amount as in the control
subjects and the fossa was displaced in an anteriorsubjects and the fossa was displaced in an anterior
inferior direction. The effective TMJ changes showedinferior direction. The effective TMJ changes showed
a pattern similar to condylar growth but were morea pattern similar to condylar growth but were more
pronounced.pronounced.

 3. Bone remodeling3. Bone remodeling processes in the lowerprocesses in the lower
mandibular border changes the morphology ofmandibular border changes the morphology of
mandiblemandible (Pancherz, Littman 1989)(Pancherz, Littman 1989) . This. This
change may be a result of an altered musclechange may be a result of an altered muscle
function pattern during therapy.function pattern during therapy.

II. Dental:II. Dental:
 Dental changes seen during Herbst applianceDental changes seen during Herbst appliance
treatment are basically a result of anchoragetreatment are basically a result of anchorage
loss in the two dental arches. The telescopeloss in the two dental arches. The telescope
mechanism produces a posterior directed forcemechanism produces a posterior directed force
on the upper teeth and an anterior directed forceon the upper teeth and an anterior directed force
on the lower teeth, resulting in distal toothon the lower teeth, resulting in distal tooth
movements in the maxillary buccal segmentsmovements in the maxillary buccal segments
and mesial tooth movements in the mandible.and mesial tooth movements in the mandible.

 1. Mandibular teeth are moved anteriorly1. Mandibular teeth are moved anteriorly
Proclination of lower anteriors. MandibularProclination of lower anteriors. Mandibular
incisors proclined on an average of 6.6incisors proclined on an average of 6.6°° during 6during 6
monthsmonths (Pancherz, 1985).(Pancherz, 1985). In 24 class II subjectsIn 24 class II subjects
treated with the Herbst appliancetreated with the Herbst appliance (Hansen et al,(Hansen et al,
19971997)),, the proclination during treatment wasthe proclination during treatment was
1111°°..

 Lower Incisor Proclination & generalLower Incisor Proclination & general
recession:-recession:-
 Large amount of lower incisor proclination duringLarge amount of lower incisor proclination during
Herbst treatment could be thought to cause breakHerbst treatment could be thought to cause break
down of the labial gingival attachment & createdown of the labial gingival attachment & create
gingival recessions.gingival recessions.
 Ruf and Pancherz (1998):Ruf and Pancherz (1998):
 Accessed the effect of orthodontic proclination ofAccessed the effect of orthodontic proclination of
lower incisors in children and adolesctents w.r.tlower incisors in children and adolesctents w.r.t
development of gingival recession. The subjects weredevelopment of gingival recession. The subjects were
treated with Herbst appliance. Herbst treatmenttreated with Herbst appliance. Herbst treatment
resulted in varying degrees of lower incisorresulted in varying degrees of lower incisor
proclination (mean=8.9proclination (mean=8.9°°, range=0.5, range=0.5°°-19.5-19.5°°).).

 No inter relation was found between the amountNo inter relation was found between the amount
of incisor proclination and development ofof incisor proclination and development of
gingival recession. The conclusion of this studygingival recession. The conclusion of this study
was that in children and adolescents awas that in children and adolescents a
temporary orthodontic proclination of lowertemporary orthodontic proclination of lower
incisors seems not to result in gingivalincisors seems not to result in gingival
recessionrecession..

 2. Maxillary molars are moved distally2. Maxillary molars are moved distally. The effect of. The effect of
the Herbst appliance on maxillary molar teeth isthe Herbst appliance on maxillary molar teeth is
essentially comparable with that of a high pullessentially comparable with that of a high pull
headgearheadgear (Pancherz, Anechus- Pancherz,(Pancherz, Anechus- Pancherz,
1993)1993). The teeth are both distalized and intruded.. The teeth are both distalized and intruded.
 Normally, the dental changes occurring during HerbstNormally, the dental changes occurring during Herbst
appliance treatment would not be desirable. Distalappliance treatment would not be desirable. Distal
tooth movements in maxillary buccal segments couldtooth movements in maxillary buccal segments could
however, be desirable in cases with anterior crowlinghowever, be desirable in cases with anterior crowling

 3)3) Mesial movements of lower molarsMesial movements of lower molars
 4)4) Sagittal dental arch relationshipSagittal dental arch relationship::
 Overjet is reduced in all patients during treatmentOverjet is reduced in all patients during treatment
by increase in mandibular length and mesialby increase in mandibular length and mesial
movement (proclaination) of the mandibularmovement (proclaination) of the mandibular
incisors.incisors.
 Class II molar correction by increase in mandibularClass II molar correction by increase in mandibular
length, distal movement of maxillary molars andlength, distal movement of maxillary molars and
mesial movement of the mandibular molars.mesial movement of the mandibular molars.

 Herbst appliance corrects or overcorrectsHerbst appliance corrects or overcorrects
both molar & canine sagittal relation in mostboth molar & canine sagittal relation in most
of the cases. However treatment is moreof the cases. However treatment is more
effective in the molar than in the canineeffective in the molar than in the canine
region. This is probably due to the maxillaryregion. This is probably due to the maxillary
anchorage system, the molar connected toanchorage system, the molar connected to
the first premolar, is pushed distally by thethe first premolar, is pushed distally by the
telescope mechanismtelescope mechanism (Pancherz and(Pancherz and
Hansen 1986)Hansen 1986) .. The canine, on the otherThe canine, on the other
hand, is not directly engaged in thehand, is not directly engaged in the
anchorage system.anchorage system.

 5. Arch perimeter:5. Arch perimeter:
 Because of the distalizing forces of the telescopeBecause of the distalizing forces of the telescope
mechanism of the Herbst appliance on the upper 1stmechanism of the Herbst appliance on the upper 1st
molars and the anteriorly directed forces on the lowermolars and the anteriorly directed forces on the lower
front teeth, the maxillary and mandibular archfront teeth, the maxillary and mandibular arch
perimeters increase during treatment.perimeters increase during treatment. (Hansen et(Hansen et
al, 1995)al, 1995)
 Increase is larger in the maxilla than in the mandible.Increase is larger in the maxilla than in the mandible.
 Arch perimeter changes are, however, of a temporaryArch perimeter changes are, however, of a temporary
nature because settling of the teeth during thenature because settling of the teeth during the
immediate post treatment period.immediate post treatment period.

6. Arch width6. Arch width
 Hansen et al (1995)Hansen et al (1995) : During treatment the maxillary and: During treatment the maxillary and
mandibular dental arches expand laterally in both canine andmandibular dental arches expand laterally in both canine and
molar areas. The expansion is more marked in the maxilla thanmolar areas. The expansion is more marked in the maxilla than
in the mandible.in the mandible.
 Maxillary dental arch width:-Maxillary dental arch width:-
 The force directed from the telescope mechanism to the upperThe force directed from the telescope mechanism to the upper
molars is both distal and buccal. Expansion in the maxillarymolars is both distal and buccal. Expansion in the maxillary
canine area can be explained by the mode of action of thecanine area can be explained by the mode of action of the
appliance as the premolars are connected to the molars by aappliance as the premolars are connected to the molars by a
lingual sectional arch and the canines to the premolars by alingual sectional arch and the canines to the premolars by a
labial sectional arch. The premolars &the canines will be movedlabial sectional arch. The premolars &the canines will be moved
in a distal buccal direction into a broader part of maxillary archin a distal buccal direction into a broader part of maxillary arch
when telescope mechanism moves maxillary molars distally.when telescope mechanism moves maxillary molars distally.

Mandibular dental arch widthMandibular dental arch width
 The mandibular molar expansion is probably notThe mandibular molar expansion is probably not
a result of forces from the Herbst appliance buta result of forces from the Herbst appliance but
rather a compensatory expansion secondary torather a compensatory expansion secondary to
the maxillary expansion. As the mandible isthe maxillary expansion. As the mandible is
positioned anteriorly during treatment the degreepositioned anteriorly during treatment the degree
of compensatory expansion is relatively small.of compensatory expansion is relatively small.

 In summary following changes contribute toIn summary following changes contribute to
Herbst appliance correction of class IIHerbst appliance correction of class II
malocclusion.malocclusion.
 Stimulation of mandibular growth.Stimulation of mandibular growth.
 Inhibition of maxillary growth (a less importantInhibition of maxillary growth (a less important
change)change)
 Distal movement of upper dentitionDistal movement of upper dentition
 Mesial movement of lower dentitionMesial movement of lower dentition
(proclination of the incisors)(proclination of the incisors)

b)b) Vertical changesVertical changes
 SkeletalSkeletal
 DentalDental
In Class II malocclusions with deep bites, overbite may beIn Class II malocclusions with deep bites, overbite may be
reduced significantly by Herbst therapyreduced significantly by Herbst therapy (Pancherz,(Pancherz,
1982, 1985)1982, 1985) an average of 3.0mm (55%) during 6an average of 3.0mm (55%) during 6
months of treatment.months of treatment.

 Dental:Dental:
 Overbite reduction is primarily accomplishedOverbite reduction is primarily accomplished
by intrusion of lower incisors and enhancedby intrusion of lower incisors and enhanced
eruption of lower molars.eruption of lower molars.
 Part of the registered changes in the verticalPart of the registered changes in the vertical
position of the mandibular incisors resultsposition of the mandibular incisors results
from proclaination of these teethfrom proclaination of these teeth
 Because of vertical dental changes, maxillaryBecause of vertical dental changes, maxillary
and mandibular occlusal planes tip down.and mandibular occlusal planes tip down.

 Skeletal:Skeletal:
 Appliance has a limited effect on maxillary andAppliance has a limited effect on maxillary and
mandibular jaw position as expressed by palatalmandibular jaw position as expressed by palatal
plane(NL/NSL) and mandibular plane angle i.eplane(NL/NSL) and mandibular plane angle i.e
mandibular plane angle remain unchanged.mandibular plane angle remain unchanged.
 Increase in lower anterior facial height (LAFH) due toIncrease in lower anterior facial height (LAFH) due to
over eruption of lower posterior teeth.over eruption of lower posterior teeth.

 Increase in gonial angle – this may be due toIncrease in gonial angle – this may be due to
a more sagittaly directed growth of thea more sagittaly directed growth of the
condyle or it may result from resorptive bonecondyle or it may result from resorptive bone
changes in the gonion region, probably as achanges in the gonion region, probably as a
consequence of an altered muscle functionconsequence of an altered muscle function
during bite jumpingduring bite jumping (Pancherz & Littman,(Pancherz & Littman,
1989)1989)

 Position of the chin will be affected byPosition of the chin will be affected by
mandibular rotation, thus giving a false picture ofmandibular rotation, thus giving a false picture of
condylar responsecondylar response (Pancherz, 1982(Pancherz, 1982 )). The. The
corresponding chin position changes during thecorresponding chin position changes during the
different examination periods were a mirrordifferent examination periods were a mirror
image of effective condylar growth provided noimage of effective condylar growth provided no
mandibular autorotation occurred. In cases withmandibular autorotation occurred. In cases with
anterior mandibular autorotation relatively moreanterior mandibular autorotation relatively more
forward and in cases with posterior mandibularforward and in cases with posterior mandibular
autorotation relatively more backward directedautorotation relatively more backward directed
chin position changes resulted.chin position changes resulted.

 2. EARLY POST TREATMENT EFFECTS:2. EARLY POST TREATMENT EFFECTS:
 After Herbst treatment over corrected sagittalAfter Herbst treatment over corrected sagittal
dental arch relationships and incomplete cuspaldental arch relationships and incomplete cuspal
interdigitation are generally seen. Becauseinterdigitation are generally seen. Because
active treatment is short (6-8 months), theactive treatment is short (6-8 months), the
occlusion is unstable and adaptive occlusalocclusion is unstable and adaptive occlusal
changes tend to occur.changes tend to occur.

 Dental:-Dental:-
 During 1st year post treatment occlusion settles into aDuring 1st year post treatment occlusion settles into a
class I relationship.class I relationship.
 Overjet and overbite recover 30% of their previousOverjet and overbite recover 30% of their previous
dimensions.dimensions.
 Approx 90% of the post treatment occlusal changesApprox 90% of the post treatment occlusal changes
occur during 1st 6 months after treatment are of dentaloccur during 1st 6 months after treatment are of dental
originorigin
 Upper teeth (especially the molars) move anteriorly , theUpper teeth (especially the molars) move anteriorly , the
lower teeth move posteriorly and the incisors becomelower teeth move posteriorly and the incisors become
upright.upright.

Mandibular incisor proclination and crowding:Mandibular incisor proclination and crowding:
 Hansen et al (1997)Hansen et al (1997) :: during treatment withduring treatment with
Herbst appliance lower incisors proclined by 11Herbst appliance lower incisors proclined by 11°°..
In post treatment period, the lower incisorsIn post treatment period, the lower incisors
moved posteriorly toward their pretreatmentmoved posteriorly toward their pretreatment
position, but on average, they remained someposition, but on average, they remained some
what proclined. This rebound in incisorswhat proclined. This rebound in incisors
inclination did not result in anterior crowdinginclination did not result in anterior crowding
immediately after treatment. In the long termimmediately after treatment. In the long term
perspective, the development of incisor crowdingperspective, the development of incisor crowding
was instead thought to be caused by normalwas instead thought to be caused by normal
craniofacial and dento alveolar growth changes.craniofacial and dento alveolar growth changes.

 Arch perimeter:Arch perimeter:
 Arch perimeter continues to decrease after the settlingArch perimeter continues to decrease after the settling
period, and the net effect in the long term perspective isperiod, and the net effect in the long term perspective is
a decrease in the arch perimeter in both the maxilla anda decrease in the arch perimeter in both the maxilla and
in the mandible. This is in accordance with the archin the mandible. This is in accordance with the arch
perimeter decrease over time, normally found inperimeter decrease over time, normally found in
untreated subjects.untreated subjects.

 Arch widthArch width::
 Although some arch constriction occurred after theAlthough some arch constriction occurred after the
treatment period, the net effect on a long term basis wastreatment period, the net effect on a long term basis was
an expansion of both maxillary intercanine andan expansion of both maxillary intercanine and
intermolar widths. In the mandible the expansion duringintermolar widths. In the mandible the expansion during
treatment rebounded during the immediate posttreatment rebounded during the immediate post
treatment period , and the net effect on a long termtreatment period , and the net effect on a long term
basis was unchanged intermolar width and a slightlybasis was unchanged intermolar width and a slightly
constricted intercanine width.constricted intercanine width.

 Skeletal:-Skeletal:-
 Unfavourable maxillomandibular growth relationshipUnfavourable maxillomandibular growth relationship
contributes to only a minor degree of early postcontributes to only a minor degree of early post
treatment occlusal changes.treatment occlusal changes.
 A catch up maxillary growth and minor reduction inA catch up maxillary growth and minor reduction in
mandibular growth are apparent in subjects treatedmandibular growth are apparent in subjects treated
with the Herbst appliance in comparison withwith the Herbst appliance in comparison with
untreated controlsuntreated controls (Pancherz, 1981, Pancherz,(Pancherz, 1981, Pancherz,
Hansen, 1986)Hansen, 1986)..
 Increase in LAFH seen during treatment inIncrease in LAFH seen during treatment in
temporary. At time of re-examination 12 months posttemporary. At time of re-examination 12 months post
treatment, LAFH was same in Herbst group as in thetreatment, LAFH was same in Herbst group as in the
control group.control group.

 In the first post treatment period of 7.5 months theIn the first post treatment period of 7.5 months the
condylar growth amount was reduced in relation tocondylar growth amount was reduced in relation to
the treatment period, and the growth directionthe treatment period, and the growth direction
became more vertically upward. These changesbecame more vertically upward. These changes
could be described as “recovery” after Herbstcould be described as “recovery” after Herbst
therapy.therapy.
 The condylion point moves in posterior and inferiorThe condylion point moves in posterior and inferior
direction corresponding to normal growthdirection corresponding to normal growth
displacement of the fossa. It thus seems as ifdisplacement of the fossa. It thus seems as if
Herbst appliance has only a temporary effect onHerbst appliance has only a temporary effect on
physiologic posterior glenoid fossa growthphysiologic posterior glenoid fossa growth
displacement in the anterior direction.displacement in the anterior direction.

LATE POST TREATMENT EFFECTSLATE POST TREATMENT EFFECTS :-:-
 When examining patients treated with the HerbstWhen examining patients treated with the Herbst
appliance 5 to 10 yrs after treatment, the clinicianappliance 5 to 10 yrs after treatment, the clinician
usually notes several effects .usually notes several effects .
 Class I dental arch relationship is maintained by stableClass I dental arch relationship is maintained by stable
cuspal interdigitation of upper and lower teeth.cuspal interdigitation of upper and lower teeth.
 In several Herbst studiesIn several Herbst studies (Pancherz, 1982, 1991,(Pancherz, 1982, 1991,
1994; Pancherz, Hagg, 1985; Pancherz,1994; Pancherz, Hagg, 1985; Pancherz,
Hansen, 1986; Weislander, 1993)Hansen, 1986; Weislander, 1993) importance of aimportance of a
good post treatment occlusal intercuspation has beengood post treatment occlusal intercuspation has been
emphasized for prevention of dental and skeletalemphasized for prevention of dental and skeletal
relapse.relapse.

 Teeth locked in a stable class I IntercuspationTeeth locked in a stable class I Intercuspation
are more likely to transfer maxillary growthare more likely to transfer maxillary growth
forces to the mandible (or vice versa) andforces to the mandible (or vice versa) and
thus possibly act as restricting or stimulatingthus possibly act as restricting or stimulating
factors on mandibular growth. Thus afactors on mandibular growth. Thus a
functionally stable occlusion after herbst orfunctionally stable occlusion after herbst or
any orthodontic therapy could be moreany orthodontic therapy could be more
important for lasting treatment results thanimportant for lasting treatment results than
the post treatment growth patternthe post treatment growth pattern
(Pancherz, Fackel, 1990)(Pancherz, Fackel, 1990) ..

RELAPSE AFTER HERBST TREATMENT:-RELAPSE AFTER HERBST TREATMENT:-
 Pancherz (1991) :-Pancherz (1991) :-
 Investigated nature of class II relapse after HerbstInvestigated nature of class II relapse after Herbst
treatment. Results revealed that :-treatment. Results revealed that :-
 Relapse in overjet and sagittal molar relationshipRelapse in overjet and sagittal molar relationship
resulted mainly from post treatment maxillary andresulted mainly from post treatment maxillary and
mandibular dental changes. In particular maxillarymandibular dental changes. In particular maxillary
incisors and molars moved significantly (p<0.05) to aincisors and molars moved significantly (p<0.05) to a
more anterior position in the relapse group than in stablemore anterior position in the relapse group than in stable
group.group.

 Two relapse promoting factors were noted:Two relapse promoting factors were noted:
 Lip tongue dysfunction habit in 64% of the relapse casesLip tongue dysfunction habit in 64% of the relapse cases
but in none of the stable cases.but in none of the stable cases.
 An unstable Class I cuspal interdigitation existed in 57 %An unstable Class I cuspal interdigitation existed in 57 %
of the relapse cases but in only 13% of the stableof the relapse cases but in only 13% of the stable
cases.cases.
 Pancherz (1994) :-Pancherz (1994) :- Found the most frequentFound the most frequent
combination of factors for relapse were :combination of factors for relapse were :
 Early treatmentEarly treatment
 Mixed dentition treatmentMixed dentition treatment

 Persistent lip tongue dysfunction habitsPersistent lip tongue dysfunction habits
 Unstable post treatment growthUnstable post treatment growth
 Unfavorable post treatment growthUnfavorable post treatment growth
however, is not a suitable factor forhowever, is not a suitable factor for
occlusal relapse.occlusal relapse.

 Ideal treatment period for long term stability:Ideal treatment period for long term stability:
 Although early treatment seems to be an importantAlthough early treatment seems to be an important
feature for relapse. Because early treatment usuallyfeature for relapse. Because early treatment usually
implies mixed dentition treatment, a solid class I cuspalimplies mixed dentition treatment, a solid class I cuspal
interdigitation is usually not attained. Thus the primaryinterdigitation is usually not attained. Thus the primary
cause for the relapse is the unstable occlusion aftercause for the relapse is the unstable occlusion after
therapy and not the maturity period in which patients aretherapy and not the maturity period in which patients are
treated.treated.

 Long term effects on mandibular growth:Long term effects on mandibular growth:
 Researchers have noted that Herbst applianceResearchers have noted that Herbst appliance
improves the sagittal jaw base skeletal relationshipimproves the sagittal jaw base skeletal relationship
but doesn’t normalize it.but doesn’t normalize it. (Hansen, Pancherz,(Hansen, Pancherz,
1995)1995)
 Dentofacial orthopaedics using the Herbst applianceDentofacial orthopaedics using the Herbst appliance
had only a temporary impact on the existinghad only a temporary impact on the existing
skeletofacial growth patternskeletofacial growth pattern (Pancherz & Fackel,(Pancherz & Fackel,
1990)1990) ..
 During Herbst treatment, the amount and direction ofDuring Herbst treatment, the amount and direction of
TMJ changes were only temporarily affectedTMJ changes were only temporarily affected
favorably by Herbst treatmentfavorably by Herbst treatment (Pancherz &(Pancherz &
Fischer, 2003)Fischer, 2003)

EFFECTS ON FACIAL PROFILEEFFECTS ON FACIAL PROFILE
 Pancherz, Anehus – Pancherz (1994):Pancherz, Anehus – Pancherz (1994):
 Evaluated short and long term effects of the HerbstEvaluated short and long term effects of the Herbst
appliance on the soft tissue profile.appliance on the soft tissue profile.
 Treatment changes:Treatment changes:
 Reduction of hard and soft tissue profile convexity.Reduction of hard and soft tissue profile convexity.
 Upper lip becomes retrusive.Upper lip becomes retrusive.
 Lower lip remains almost unchanged.Lower lip remains almost unchanged.

 Post treatment effectsPost treatment effects::
 Reduction in the soft tissue profile convexityReduction in the soft tissue profile convexity
(excluding the nose) because of normal jaw(excluding the nose) because of normal jaw
growth changes.growth changes.
 Increase in the soft tissue profile (including theIncrease in the soft tissue profile (including the
nose) convexity because of normal nose growth.nose) convexity because of normal nose growth.
 Retrusion of upper and lower lips in relation to theRetrusion of upper and lower lips in relation to the
E line because of normal nose and chin growth.E line because of normal nose and chin growth.
 Most favorable soft tissue profile changes areMost favorable soft tissue profile changes are
seen in subjects with protrusive upper lips andseen in subjects with protrusive upper lips and
retrusive chin and lower lips.retrusive chin and lower lips.

EFFECTS ON THE MASTICATORYEFFECTS ON THE MASTICATORY
SYSTEM:SYSTEM:
 Masticatory ability:Masticatory ability:
 Chewing difficulties are experienced only during the firstChewing difficulties are experienced only during the first
7 to 10 days of treatment. No subsequent problems are7 to 10 days of treatment. No subsequent problems are
usually reported.usually reported.
 Treatment with the Herbst appliance doesn’t seem toTreatment with the Herbst appliance doesn’t seem to
have significant effect on functional status of thehave significant effect on functional status of the
masticatory musculaturemasticatory musculature (Pancherz and Pancherz,(Pancherz and Pancherz,
1982; Hansen et al, 1990: Foucart e al, 1998)1982; Hansen et al, 1990: Foucart e al, 1998) ..

Muscle activity:Muscle activity:
 Pancherz and Anehus PancherzPancherz and Anehus Pancherz investigatedinvestigated
the influence of Herbst appliance on the EMG patternthe influence of Herbst appliance on the EMG pattern
of temporal and masseter muscles.of temporal and masseter muscles.
 EMG activity of both the temporal and masseterEMG activity of both the temporal and masseter
muscle was reduced at the start of treatment.muscle was reduced at the start of treatment.
 The EMG activity came to pretreatment value afterThe EMG activity came to pretreatment value after
three months.three months.
 After six months EMG activity from both the musclesAfter six months EMG activity from both the muscles
exceeded pretreatment values, and 12 months postexceeded pretreatment values, and 12 months post
treatment contraction pattern in both the muscles istreatment contraction pattern in both the muscles is
similar to subjects with normal occlusion.similar to subjects with normal occlusion.

EFFECT ON TMJ:EFFECT ON TMJ:
 During treatment with the Herbst appliance lower jawDuring treatment with the Herbst appliance lower jaw
is continuously protruded so that the harmoniousis continuously protruded so that the harmonious
interaction of the occluding teeth, the masticatoryinteraction of the occluding teeth, the masticatory
muscles and the TMJ is challenged.muscles and the TMJ is challenged.
 On short term basis Herbst treatment seems not toOn short term basis Herbst treatment seems not to
cause any functional disturbances in these structurescause any functional disturbances in these structures
(Pancherz & Pancherz, 1980, 1982)(Pancherz & Pancherz, 1980, 1982) ..
 Hansen et al (1990)Hansen et al (1990): Analysed long term effects: Analysed long term effects
of Herbst treatment on TMJ.of Herbst treatment on TMJ.
 Anamnestic, clinical and radiographic findingsAnamnestic, clinical and radiographic findings
revealed that Herbst treatment did not seem to haverevealed that Herbst treatment did not seem to have
any long term effect on the craniomandibular system.any long term effect on the craniomandibular system.

 Ruf and Pancherz (1998)Ruf and Pancherz (1998)
 On a long term basis, no structural bone changesOn a long term basis, no structural bone changes
of the TMJ were detectable after Herbst treatment.of the TMJ were detectable after Herbst treatment.
 Nor is the prevalence of signs and symptoms ofNor is the prevalence of signs and symptoms of
TMD higher in Herbst patients than in the generalTMD higher in Herbst patients than in the general
population several years after treatment.population several years after treatment.

 Ruf & Pancherz (2000) :Ruf & Pancherz (2000) : Indicated that treatmentIndicated that treatment
with Herbst appliance:with Herbst appliance:
 Did not result in any muscular TMDDid not result in any muscular TMD
 Reduced the prevalence of capsulitis.Reduced the prevalence of capsulitis.
 Reduced the prevalence of structural condylar bonyReduced the prevalence of structural condylar bony
changes.changes.
 Did not induce any disc displacement in subjects withDid not induce any disc displacement in subjects with
physiologic disc position.physiologic disc position.
 Resulted in stable repositioning of the disc in subjectsResulted in stable repositioning of the disc in subjects
with partial disc displacement with reduction.with partial disc displacement with reduction.
 Couldn’t recapture the disc in subjects with aCouldn’t recapture the disc in subjects with a
pretreatment total disc displacement with or withoutpretreatment total disc displacement with or without
reduction.reduction.

 Important questionsImportant questions ::
 Does the Herbst appliance damage TMJ?Does the Herbst appliance damage TMJ?
 Does the Herbst appliance improve TMJDoes the Herbst appliance improve TMJ
function?function?
 What kind of class II patients benefit fromWhat kind of class II patients benefit from
Herbst treatment in terms of improvedHerbst treatment in terms of improved
TMJ function?TMJ function?

 Does Herbst appliance damage TMJ?Does Herbst appliance damage TMJ?
 From the previous studies it can beFrom the previous studies it can be
concluded that Herbst appliance doesn’tconcluded that Herbst appliance doesn’t
have an adverse effect on TMJ functionhave an adverse effect on TMJ function
on a short and long term basis.on a short and long term basis.

 Does Herbst appliance improve TMJ function?Does Herbst appliance improve TMJ function?
 Ruf and Pancherz (1998, 2000)Ruf and Pancherz (1998, 2000) ::
Prevalence of TMD in Class II subjectsPrevalence of TMD in Class II subjects
decreased by 50% from before to after Herbstdecreased by 50% from before to after Herbst
treatment and by 27% from before to 4 yrstreatment and by 27% from before to 4 yrs
after Herbst treatment.after Herbst treatment.
 Frequency change was opposite to that inFrequency change was opposite to that in
normal population in which TMD prevalencenormal population in which TMD prevalence
increases with age.increases with age.

 3.3. What kind of class II patients benefit fromWhat kind of class II patients benefit from
Herbst treatment in terms of improved TMJHerbst treatment in terms of improved TMJ
function?function?
 Appliance effects on:Appliance effects on:
 Disc positionDisc position
 Condylar position.Condylar position.
 TMJ soft tissues.TMJ soft tissues.
 TMJ bony structuresTMJ bony structures
 Masticatory musculatureMasticatory musculature

Disc positionDisc position
 A slight retrusion of the disc compared with pretreatmentA slight retrusion of the disc compared with pretreatment
values is seen at the end of treatmentvalues is seen at the end of treatment (Pancherz et(Pancherz et
al, 1999; Ruf and Pancherz, 2000)al, 1999; Ruf and Pancherz, 2000) . Can be due to:. Can be due to:
 Changes in form because of the remodeling processChanges in form because of the remodeling process
of the condyle and fossa.of the condyle and fossa.
 Remodelling of the discRemodelling of the disc (Nagy and Daniel, 1992)(Nagy and Daniel, 1992)
during the course of treatment.during the course of treatment.

 In contrast to normal disc repositioningIn contrast to normal disc repositioning
therapy, recapturing of the disc during Herbsttherapy, recapturing of the disc during Herbst
treatment was achieved by the retrusion oftreatment was achieved by the retrusion of
the disc and not by protrusion of the condyle.the disc and not by protrusion of the condyle.
 To date disc recapturing capacity of otherTo date disc recapturing capacity of other
functional appliance than the Herbstfunctional appliance than the Herbst
appliance has not been investigated , exceptappliance has not been investigated , except
that for activatorthat for activator ((Ruf, Wusten andRuf, Wusten and
Pancherz, 2002).Pancherz, 2002).

 Thus, until further knowledge is available,Thus, until further knowledge is available,
the Herbst appliance must be consideredthe Herbst appliance must be considered
the only functional appliance able tothe only functional appliance able to
improve the position of the articular discimprove the position of the articular disc
during treatmentduring treatment

 Treatment considerations for Class IITreatment considerations for Class II
patients with different degrees of discpatients with different degrees of disc
displacement:displacement:
 With partial disc displacement, there is a goodWith partial disc displacement, there is a good
prognosis for disc repositioning.prognosis for disc repositioning.
 With total disc displacement with reduction, there is aWith total disc displacement with reduction, there is a
bad prognosis for disc repositioning.bad prognosis for disc repositioning.
 With total disc displacement without reduction there isWith total disc displacement without reduction there is
no chance for disc repositioning.no chance for disc repositioning.

Condylar position:Condylar position:
 During Herbst treatment, the amount of anteriorDuring Herbst treatment, the amount of anterior
position of the condyle was temporarily increasedposition of the condyle was temporarily increased
 When the occlusion settled after treatment, theWhen the occlusion settled after treatment, the
condyle returned to its original fossa positioncondyle returned to its original fossa position
(Hansen et al, 1990; Ruf and Pancherz,(Hansen et al, 1990; Ruf and Pancherz,
2000)2000)..
 Inverse relationship between the condyle andInverse relationship between the condyle and
position of the disc, which was especiallyposition of the disc, which was especially
pronounced before treatment.pronounced before treatment.

TMJ soft tissues:TMJ soft tissues:
 No effects of Herbst treatment on the superiorNo effects of Herbst treatment on the superior
stratum of the posterior attachment or thestratum of the posterior attachment or the
structures of the joint capsule could be observedstructures of the joint capsule could be observed
(Ruf and Pancherz, 2000).(Ruf and Pancherz, 2000).
 Only affected structure was the inferior stratumOnly affected structure was the inferior stratum
of the posterior attachment.of the posterior attachment.

 Prevalence of the capsulitis of the inferiorPrevalence of the capsulitis of the inferior
stratum of the posterior attachment wasstratum of the posterior attachment was
reduced from 24% to 7%.reduced from 24% to 7%.
 Induction of capsulitis is caused by theInduction of capsulitis is caused by the
advancement of the condyle provoked by theadvancement of the condyle provoked by the
Herbst appliance, which results in expansionHerbst appliance, which results in expansion
of the posterior attachment.of the posterior attachment.

 Hansen, Pancherz and Hagg (1991)Hansen, Pancherz and Hagg (1991) ::
Growth period in which Herbst treatment wasGrowth period in which Herbst treatment was
performed did not seem to have anyperformed did not seem to have any
conclusive effect on the long term results.conclusive effect on the long term results.
However in order to favour occlusal stabilityHowever in order to favour occlusal stability
after treatment and to reduce the time of postafter treatment and to reduce the time of post
treatment retention, Herbst therapy in thetreatment retention, Herbst therapy in the
permanent dentition at or just after peakpermanent dentition at or just after peak
height velocity is recommended.height velocity is recommended.

TMJ bony structuresTMJ bony structures
 During Herbst treatment, the prevalence of structuralDuring Herbst treatment, the prevalence of structural
bony changes of the condyle (flattening, erosions,bony changes of the condyle (flattening, erosions,
osteophytes) decreasedosteophytes) decreased (Ruf and Pancherz, 2000)(Ruf and Pancherz, 2000) ..
 Remodelling of the condyle induced by the HerbstRemodelling of the condyle induced by the Herbst
appliance promoted normalization of the condylar bonyappliance promoted normalization of the condylar bony
structures.structures.

INDICATIONS FOR TREATMENTINDICATIONS FOR TREATMENT
 Pancherz (1985)Pancherz (1985);; indicated that Herbst applianceindicated that Herbst appliance
should be used only in growing individuals.should be used only in growing individuals.
 Should not be used in non growing subjects because.Should not be used in non growing subjects because.
 Skeletal alterations will be minimal.Skeletal alterations will be minimal.
 More of dentoalveolar changes.More of dentoalveolar changes.
 Increase risk of developing dual bite.Increase risk of developing dual bite.
 Unlike removable functional appliances, the HerbstUnlike removable functional appliances, the Herbst
appliance can be used in following instances.appliance can be used in following instances.

 Postadolescent patients:Postadolescent patients:
 Passed the maximum pubertal growth spurt.Passed the maximum pubertal growth spurt.
 Still have some growth potential.Still have some growth potential.
 Too old for conventional removable FA.Too old for conventional removable FA.
 Mouth breathersMouth breathers: Nasal airway obstructions: Nasal airway obstructions
can make the proper use of removable FAcan make the proper use of removable FA
difficult or impossible.difficult or impossible.
 Uncooperative patientsUncooperative patients..
 Patients who do not respond to removablePatients who do not respond to removable
FAFA..

TIMING OF TREATMENTTIMING OF TREATMENT
 Most favorable time to treat the patients with the HerbstMost favorable time to treat the patients with the Herbst
appliance is at the peak of pubertal growth spurtappliance is at the peak of pubertal growth spurt
((Pancherz, Hagg, 1985)Pancherz, Hagg, 1985) ..
 Pancherz & Hagg (1988):Pancherz & Hagg (1988): Indicated that the patientsIndicated that the patients
treated at the initial closure of the middle phalanx of thetreated at the initial closure of the middle phalanx of the
third finger (MP3-FG) had the greatest amount ofthird finger (MP3-FG) had the greatest amount of
condylar growth.condylar growth.
 MP3-FG stage occurs close to Peak height velocity.MP3-FG stage occurs close to Peak height velocity.
 Available literature demonstrates that ideal, period forAvailable literature demonstrates that ideal, period for
the Herbst treatment isthe Herbst treatment is::

 In permanent dentition at or just afterIn permanent dentition at or just after
the peak of pubertal growth spurt.the peak of pubertal growth spurt.
 Skeletal maturity stages FG to H of theSkeletal maturity stages FG to H of the
middle phalanx of third finger (implyingmiddle phalanx of third finger (implying
precapping to pre-union stages of theprecapping to pre-union stages of the
epiphysis and metaphysis).epiphysis and metaphysis).
 Manidbular growth stimulation in youngManidbular growth stimulation in young
adults:adults:

 McNamara, Peterson and PancherzMcNamara, Peterson and Pancherz
(2003)(2003)
 Evaluated histologically the response of theEvaluated histologically the response of the
mandibular condyle, glenoid fossa andmandibular condyle, glenoid fossa and
posterior border of the ramus of adultposterior border of the ramus of adult
Rhesus monkeys with the Herbst appliance.Rhesus monkeys with the Herbst appliance.
 No evidence of pathology was noted in anyNo evidence of pathology was noted in any
of the control or experimental TMJs.of the control or experimental TMJs.
 Increased proliferation of the condylarIncreased proliferation of the condylar
cartilage in the experimental animals.cartilage in the experimental animals.

 Minimal adaptations along the anteriorMinimal adaptations along the anterior
surface of post glenoid spine.surface of post glenoid spine.
 No evidence of bony apposition or resorptionNo evidence of bony apposition or resorption
on posterior border of ramuson posterior border of ramus..

 Ruf and Pancherz (1999):Ruf and Pancherz (1999): Analysed and comparedAnalysed and compared
TMJ remodeling in adolescent and young adults duringTMJ remodeling in adolescent and young adults during
Herbst treatment.Herbst treatment.
 Increase in mandibular prognathism accompanied byIncrease in mandibular prognathism accompanied by
Herbst therapy in both the adolescents and youngHerbst therapy in both the adolescents and young
adults.adults.
 Hence it is possible to reactivate or stimulate condylarHence it is possible to reactivate or stimulate condylar
growth even in subjects at the end of growth.growth even in subjects at the end of growth.
 Herbst appliance can be an alternative to orthognathicHerbst appliance can be an alternative to orthognathic
surgery in borderline skeletal class II cases.surgery in borderline skeletal class II cases.

IDEAL PATIENT FOR TREATMENT WITHIDEAL PATIENT FOR TREATMENT WITH
HERBST APPLIANCE:HERBST APPLIANCE:
 Skeletal morphology:Skeletal morphology:
 Retrognathic mandible.Retrognathic mandible.
 Small mandibular plane angle.Small mandibular plane angle.

 Dental morphology:Dental morphology:
 Class II dental arch relationship withClass II dental arch relationship with
increased overjet and normal or increasedincreased overjet and normal or increased
overbite (open bite cases not suitable foroverbite (open bite cases not suitable for
Herbst appliance).Herbst appliance).
 Maxillary and mandibular teeth well aligned.Maxillary and mandibular teeth well aligned.
 Maturation:Maturation: Treatment during pubertalTreatment during pubertal
growth spurt.growth spurt.

Multiphase treatment approach:Multiphase treatment approach:
 Class II, division 1 malocclusion.Class II, division 1 malocclusion.
 Orthopedic phaseOrthopedic phase
 Orthdontic phaseOrthdontic phase
 Class II, division 2 malocclusion:Class II, division 2 malocclusion:
 Orthodontic phaseOrthodontic phase
 Orthopedic phaseOrthopedic phase
 Orthodontic phase.Orthodontic phase.

MODIFICATIONS OF THE HERBST APPLIANCEMODIFICATIONS OF THE HERBST APPLIANCE
 In patients with class II malocclusions whoIn patients with class II malocclusions who
have narrow maxillary arches, expansion canhave narrow maxillary arches, expansion can
be performed using the Herbst appliance bybe performed using the Herbst appliance by
soldering a quad helix lingual arch wire or asoldering a quad helix lingual arch wire or a
rapid palatal expansion device to the upperrapid palatal expansion device to the upper
premolar and molar bands or to the splint.premolar and molar bands or to the splint.

The cast splint herbstThe cast splint herbst
 In the bands are replaced by splints cast from cobalt-In the bands are replaced by splints cast from cobalt-
chromium alloy and cemented to the teeth with GIC.chromium alloy and cemented to the teeth with GIC.
The upper and lower front teeth are incorporated intoThe upper and lower front teeth are incorporated into
the anchorage through the addition of sectional archthe anchorage through the addition of sectional arch
wires (figure)wires (figure)
 The cast splint applianceThe cast splint appliance
 ensures a precise fit on the teethensures a precise fit on the teeth
 is strong and hypgienicis strong and hypgienic
 saves chair timesaves chair time
 Causes very few clinical problems.Causes very few clinical problems.

Herbst with stainless steel crownsHerbst with stainless steel crowns
 Norris M. Langford, 1982 JCO)Norris M. Langford, 1982 JCO) suggestedsuggested
using stainless steel crowns on the upper firstusing stainless steel crowns on the upper first
molar and the lower first premolar and canine formolar and the lower first premolar and canine for
the Herbst appliance which are superior tothe Herbst appliance which are superior to
banding in that they are resistant to breakagebanding in that they are resistant to breakage
and becoming loose. He also suggested.and becoming loose. He also suggested.
Making a small hole in the occlusal pit of eachMaking a small hole in the occlusal pit of each
crown to allow trapped air to escape and tocrown to allow trapped air to escape and to
provide even coverage of cement around theprovide even coverage of cement around the
tooth.tooth.

The bonded Herbst appliance (JCO OctThe bonded Herbst appliance (JCO Oct
1982)1982)
 d) Introduced by Raymond P Howe to overcomed) Introduced by Raymond P Howe to overcome
some of the limitations of the original bandedsome of the limitations of the original banded
appliance which were.appliance which were.
 Since the banded design is attached in the lower arch to firstSince the banded design is attached in the lower arch to first
premolar bands, the use of the appliance is limited topremolar bands, the use of the appliance is limited to
patients with erupted mandibular first bicuspids. Although itpatients with erupted mandibular first bicuspids. Although it
is suggested that the mandibular canine may be used in theis suggested that the mandibular canine may be used in the
anchor, when the first premolar has yet to erupt, however,anchor, when the first premolar has yet to erupt, however,
the buccal mucosa at the corner of the mouth is prone tothe buccal mucosa at the corner of the mouth is prone to
ulceration when the mandibular canine is used as anulceration when the mandibular canine is used as an
abutment tooth for the plunger.abutment tooth for the plunger.

I)I) Repeated breakage and loosening of theRepeated breakage and loosening of the
appliance occurs, especially in the lowerappliance occurs, especially in the lower
bicuspid band area.bicuspid band area.
II)II) Rapid intrusion if the mandibular first bicuspidsRapid intrusion if the mandibular first bicuspids
which though temporary, partially deactivateswhich though temporary, partially deactivates
the appliance.the appliance.
III)III) As the bicuspids are depressed, the lingual archAs the bicuspids are depressed, the lingual arch
is also depressed, resulting in impingement onis also depressed, resulting in impingement on
the lingual gingiva.the lingual gingiva.
IV)IV) Possibility of incisal tooth fracture.Possibility of incisal tooth fracture.

 The bonded Herbst appliance design (fig )The bonded Herbst appliance design (fig )
 Like the original design, this also includes pairedLike the original design, this also includes paired
telescoping elements. Also these elements aretelescoping elements. Also these elements are
attached to the maxillary arch as in the originalattached to the maxillary arch as in the original
 However the paired telescoping elements, whichHowever the paired telescoping elements, which
had been attached to the lower bicuspids bandshad been attached to the lower bicuspids bands
are now attached to the entire lower dental archare now attached to the entire lower dental arch
by an acrylic bite splint.by an acrylic bite splint.

 The splint is constructed using aThe splint is constructed using a
circumferential wire framework, whichcircumferential wire framework, which
supports the lower herbst axles. The entiresupports the lower herbst axles. The entire
framework is embedded in an acrylic splint,framework is embedded in an acrylic splint,
which extends from the last available molarwhich extends from the last available molar
tooth on one side, around the arch, to the lasttooth on one side, around the arch, to the last
molar tooth on the opposite side. The acrylicmolar tooth on the opposite side. The acrylic
coverage begins at the free gingival margincoverage begins at the free gingival margin
on the buccal of the posterior teeth and runson the buccal of the posterior teeth and runs
over the occlusal surface of the teeth, endingover the occlusal surface of the teeth, ending
at the free gingival margin on the lingual.at the free gingival margin on the lingual.

 In the anterior region, the splint is reducedIn the anterior region, the splint is reduced
from the cervical, so that only the occlusalfrom the cervical, so that only the occlusal
1/3rd of the incisor and cuspid crowns is1/3rd of the incisor and cuspid crowns is
covered with acrylic. The splint containscovered with acrylic. The splint contains
the lower pivots, which are positioned inthe lower pivots, which are positioned in
the area of the mandibular first bicuspidsthe area of the mandibular first bicuspids
or deciduous first molars.or deciduous first molars.

 The lower splint is bonded to all lowerThe lower splint is bonded to all lower
teeth including the incisors, using ateeth including the incisors, using a
conventional etching and bondingconventional etching and bonding
technique.technique.

Modifications within this design :Modifications within this design :
 Short stiff coil springs (0.020” spring wire) 3mmShort stiff coil springs (0.020” spring wire) 3mm
long with an inside diameter slightly greater thanlong with an inside diameter slightly greater than
the plunges shaft, can be placed between thethe plunges shaft, can be placed between the
upper and lower telescoping elements.upper and lower telescoping elements.
 They provide a dampening effect as the plungers andThey provide a dampening effect as the plungers and
sleeves contact, reducing the shock inducedsleeves contact, reducing the shock induced
loosening of either the upper bands or the lower splintloosening of either the upper bands or the lower splint
 These springs can also be used to reactivate theThese springs can also be used to reactivate the
applianceappliance

 For patients requiring palatal expansion, a rapid palatalFor patients requiring palatal expansion, a rapid palatal
expander can be incorporated.expander can be incorporated.
 If rotations and displacements of the maxillary posteriorIf rotations and displacements of the maxillary posterior
teeth are to be minimized, a transpalatal arch bar can beteeth are to be minimized, a transpalatal arch bar can be
used.used.
 In patients displaying vertical hyperplasia of the lowerIn patients displaying vertical hyperplasia of the lower
face, a vertical pull chin cup may be used. Sine theface, a vertical pull chin cup may be used. Sine the
entire maxillary dentition is in contact with the splint, aentire maxillary dentition is in contact with the splint, a
significant amount of force can be applied.significant amount of force can be applied.

 Patients with hyperactive mentalis musculePatients with hyperactive mentalis muscule
may benefit form the attachment of Frankel likemay benefit form the attachment of Frankel like
labial pads, which may be inserted into buccallabial pads, which may be inserted into buccal
tubes on each side of the mandibular splint.tubes on each side of the mandibular splint.
 If a distal component of force is desired, aIf a distal component of force is desired, a
mandibular lip bumper can be inserted intomandibular lip bumper can be inserted into
similar buccal tubes in the lower splint.similar buccal tubes in the lower splint.

 To facilitate removal of the bonded appliance, holesTo facilitate removal of the bonded appliance, holes
are drilled in the splint corresponding to the middle ofare drilled in the splint corresponding to the middle of
the occlusal surfaces of the lower posterior teeth tothe occlusal surfaces of the lower posterior teeth to
accommodate the resting leg of a posterior bandaccommodate the resting leg of a posterior band
removing plierremoving plier
 In 1983 (JCO, Feb), Raymond P. Howe in his articleIn 1983 (JCO, Feb), Raymond P. Howe in his article
on “updating the bonded Herbst appliance”,on “updating the bonded Herbst appliance”,
suggested using an acrylic splint for the maxillarysuggested using an acrylic splint for the maxillary
arch as well. The maxillary splint covers all availablearch as well. The maxillary splint covers all available
maxillary teeth with exception of the central andmaxillary teeth with exception of the central and
lateral incisors. Acrylic coverage extends from thelateral incisors. Acrylic coverage extends from the
free gingival margin on the buccal surfaces of thefree gingival margin on the buccal surfaces of the
teeth over the occlusal, ending at the free gingivalteeth over the occlusal, ending at the free gingival
margin on the lingual surfaces. The occlusalmargin on the lingual surfaces. The occlusal
thickness of the maxillary splint is kept to a minimum,thickness of the maxillary splint is kept to a minimum,
so that the cusps of the posterior teeth perforate theso that the cusps of the posterior teeth perforate the
splint figure.splint figure.

 Add on auxiliaries (figure)Add on auxiliaries (figure)
 In addition to their use in attaching the HerbestIn addition to their use in attaching the Herbest
mechanism to the dental arches, The bonded splintsmechanism to the dental arches, The bonded splints
provide convenient structures for the inclusion ofprovide convenient structures for the inclusion of
auxiliary appliances.auxiliary appliances.
 Eg :Eg :
 Incorporation of rectangular buccal tubes in the maxillaryIncorporation of rectangular buccal tubes in the maxillary
splint allows the simultaneous use of a utility arch wire tosplint allows the simultaneous use of a utility arch wire to
procline and / or intrude the maxillary incisor teeth. Thisprocline and / or intrude the maxillary incisor teeth. This
is especially important if the maxillary incisor teeth areis especially important if the maxillary incisor teeth are
retropositioned.retropositioned.

 Rapid palatal expansion device.Rapid palatal expansion device.
 Removable frankle type padsRemovable frankle type pads
 Lip bumperLip bumper
 Vertical pull chin upVertical pull chin up

 AdvantagesAdvantages
 Allows attachment to the entire mandibular dentalAllows attachment to the entire mandibular dental
arch without the use of orthodontic bands on thearch without the use of orthodontic bands on the
mandibular first bicuspid teeth – hence patients atmandibular first bicuspid teeth – hence patients at
any stage of dental development can be fitted withany stage of dental development can be fitted with
the bonded Herbst.the bonded Herbst.
 Intrusion of mandibular bicuspids is minimized.Intrusion of mandibular bicuspids is minimized.
 Tissue impingement of the lower lingual wire isTissue impingement of the lower lingual wire is
preventedprevented
 Offers a degree of protection from incisal fractureOffers a degree of protection from incisal fracture
 Incidence of failure of the appliance due toIncidence of failure of the appliance due to
breakage is greatly reduced.breakage is greatly reduced.

e)e) The Acrylic splint Herbst appliance :The Acrylic splint Herbst appliance :
 The bonded Herbst appliance eventuallyThe bonded Herbst appliance eventually
evolved into the acrylic splint Herbst applianceevolved into the acrylic splint Herbst appliance
(McNamara, 1988; McNamara and Howe 1988).(McNamara, 1988; McNamara and Howe 1988).
 The acrylic splint Herbst appliance isThe acrylic splint Herbst appliance is
composed of a wire framework over which hascomposed of a wire framework over which has
been adapted, 2.5-3.0 mm thick splint Bioacryl,been adapted, 2.5-3.0 mm thick splint Bioacryl,
using a thermal pressure machine. If theusing a thermal pressure machine. If the
maxillary splint is removable, the canine ismaxillary splint is removable, the canine is
incorporated into the appliance (figure).incorporated into the appliance (figure).

 If the maxillary part of the appliance is to be bonded inIf the maxillary part of the appliance is to be bonded in
position, only the lingual surface of the maxillary canineposition, only the lingual surface of the maxillary canine
is incorporated into the arch (figure). The maxillary splintis incorporated into the arch (figure). The maxillary splint
covers the posterior dentition but does not contact thecovers the posterior dentition but does not contact the
upper incisors.upper incisors.
 The mandibular part of the appliance always isThe mandibular part of the appliance always is
removable. A splint covers the entire posterior dentitionremovable. A splint covers the entire posterior dentition
as well as the lower anterior teeth. The mandibular partas well as the lower anterior teeth. The mandibular part
of the appliance also covers the lingual surfaces of theof the appliance also covers the lingual surfaces of the
anterior teeth and 1/3rd to ½ of the labial surfaces ofanterior teeth and 1/3rd to ½ of the labial surfaces of
these teeth.these teeth.

f) Headgear – Herbst appliance : -f) Headgear – Herbst appliance : - WeislandeWeislande
(AJO, July 1984)(AJO, July 1984)
 Wesilander suggested the use of specialWesilander suggested the use of special
headgear – Herbst appliance in the treatment ofheadgear – Herbst appliance in the treatment of
large sagittal discrepancies between the maxillalarge sagittal discrepancies between the maxilla
and mandible in early mixed dentition.and mandible in early mixed dentition.
 The Herbst appliance consisted of a cast ofThe Herbst appliance consisted of a cast of
vitallium bonded to the lower arch and withvitallium bonded to the lower arch and with
bands on the upper first permanent molars.bands on the upper first permanent molars.
 The upper bands were united with a palatal barThe upper bands were united with a palatal bar
and connected to the lower splint with the Herbstand connected to the lower splint with the Herbst
telescopic arms.telescopic arms.

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