Effects and Uses of Functional Appliances

AFFECTS AND EFFECTS
OF FUNCTIONAL APPLIANCES
www.indiandentalacademy.com

DEFINITION OF FUNCTIONAL
APPLIANCES:
“A functional appliance harnesses
natural forces which it transmits to the teeth
and alveolar bone in a pre determined
direction”.
(White, Gardiner, Leighton)

PRINCIPLES OF FUNCTIONAL
APPLIANCE THERAPY:
It is to reposition a retrusive mandible to a
forward position
by constructing a removable appliance
that effects a protrusive bite when the
appliance is placed in the mouth.

INTRODUCTION:
Functional appliances are designed to
change the patients
pattern of function,
alter the jaw relationships,
and reprogram the neuromusculature,
thus altering the functional matrix of the
face. www.indiandentalacademy.com

CONCEPTS OF FUNCTIONAL
APPLIANCES:
NEW PATTERN OF FUNCTION:
NEW MORPHOLOGIC PATTERN:

• Björk and Pancherz demonstrated only small changes in
mandibular growth and concluded that it was not affected by
treatment with functional appliances.
• By contrast Harris, DeVincenzo, and Windmiller suggested that
there may be significant influences on mandibular growth after
timely intervention.
• Robertson, Freunthaller; Bjork & Softly suggested that the
principal changes that occurred with functional appliance
therapy were dentoalveolar.

• Bjork, Jackobson and, Harvold and Vargervik stated that
activators did not produce alterations in mandibular growth that
were different from those that would have occurred without
treatment.
• Browne and Marschner and Harris noted a significantly higher
rate of mandibular growth.
• Freunthaller stated that functional therapy has a “stimulating
effect on growth centers and sites”.

EFFECTS OF FUNCTIONAL APPLIANCES:
Functional appliances
Increased contractile activity of the LPM
Intensification of the repetitive activity of the retrodiscal pad
Increase in growth stimulating factors
*Enhancement of local mediators (STH)
*Reduction of local regulators (pre chondroblast multiplication
restraining factor)
*Change in condylar trabecular orientation
*Additional growth of condylar cartilage
*Additional subperiosteal ossification of the posterior border of the
mandible
Supplementary lengthening of the mandible

C-II CORRECTION : a likely scenario (Graber &
Vanarsdall) Skeletal effects:
•Condylar growth amount during treatment (1-3 mm).
•Fossa displacement, growth, & adaptation (3-5 mm).
•Elimination of functional retrusion (0.5-1.5 mm).
•More favorable growth direction (0.5-1.5 mm).
•Withholding of downward & forward maxillary growth (1-1.5
mm).
•Differential upward & forward maxillary growth (1.5-2.5 mm).
•Headgear effect (0.5-0.0 mm).www.indiandentalacademy.com

SOFT TISSUE EFFECTS:
• Neuromuscular adaptation.
• Improving muscle tonus.
• Improving lip seal.
• Improvement in facial esthetics.

DENTAL EFFECTS:
Maxilla:
•Restraining effect on posterior teeth.
•Retroclination of upper anteriors.
Mandible:
•Mesialization and eruption of posterior teeth.
•Proclination of anteriors.

BITE PLANES:
These are extensions of acrylic base frame work.
Action:-
During functional movements like swallowing, due to
lack of contact of the posterior teeth all the forces are
transmitted to the region of contact, which guides the
teeth to erupt into normal position.

ORAL SCREEN: (1912 Newell)
• Using changes in muscle balance primarily,
Theoretical basis of appliance action: (Selmer-Olsen)

LIP BUMPER:
lip sucking and (perverted lower lip function)
hyperactivity of mentalis muscle can be activated. By
guiding the lower lip into a more forward position and
eliminating the lip trap, they enable dento alveolar
development to follow a normal pattern.

REMOVABLE FUNCTIONAL APPLIANCES

ACTIVATOR:
Activate normal function while eliminating the spatial and
morphologic malrelationships excerbating the malocclusion.
During craniofacial growth the activator can influence the third
level of articulation, as outlined by Moffett (i.e, the sutures and
TMJ)

Affects: (1985 Graeme.L.Roberts)
1) Re-education of musculature.
2) Lateral pterygoid muscle stimulation.
3) Decreased bio-chemical feed back.
4) Unloading of the mandibular condyle.
5) Transduction of viscoelastic force.
6) Differential eruption.

HORIZONTAL ACTIVATOR
VERTICAL ACTIVATOR

EFFECTS: (Aus ortho-1985-March)
Antero-posterior effects:
1) A forward displacement of the lower arch.
2) A distal movement of maxillary arch.
3). An inhibition of the forward growth of the maxilla.
4) A stimulation of condylar growth.
5) A remodelling of the mandibular fossa.
6) An elimination of interferences which guide the mandible
distally during closure.

The vertical effects:
Successful overbite reduction found to be accompanied by:
1) Inhibition of lower incisor euption.
2) Facilitation of molar eruption.
3) Encouragement of forward mandibular rotation.
4) An increase in lower face height.

COMBINATION HEADGEAR-ACTIVATOR: (JCO1984March)
1) Intrusion and retraction of upper front teeth.
2) Distalization of upper molars.
3) Maxilla retraction.
4) Mandibular growth stimulation, especially in the brachyfacial
group.
5) Opening of the facial axis in the brachyfacial group.
6) Maintenance of the facial axis in the dolico facial group.
7) Minor, if any, tilting of lower incisors.
8) Stopping lower incisor eruption.
9) Stopping the decent of the palate.www.indiandentalacademy.com

BIONATOR:
Philosophy: Tongue is the center of the reflex activity in the oral
cavity.
The bionator is a functional appliance introduced by “Balters” in
1956.
Kantorowicz termed the bionator “the skeleton of an activator from
which there is nothing left but the naked embodiment of Robin’s
thoughts”.

AFFECTS OF BIONATOR:
• CHANGE IN TONGUE POSITION.
• KEEPS AWAY BUCCAL MUSCULATURE.
• LIP SEAL.
• MANDIBULAR PROTRUSION.

Effects of Bionator : (A.O. 1995)
1) Decreased skeletal convexity.
2) reduced overjet and overbite.
3) Decreased facial convexity.
4) Increase in length of the lower lip.
5) Minimal effect on the upper lip.

•Standard appliance.
•Open bite appliance.
•C-III appliance.

FRANKEL FUNCTIONAL REGULATOR:
Philosophy:
1) Vestibular arena of operations.
2) Sagittal correction via tooth borne maxillary anchorage.
3) Minimal maxillary basal effect.
4) Periosteal pull, lip pads and buccal shields.

FR-2 FR-3
FR-4

Effects of Functional Regulator:
1. An increase of sagittal and transverse intraoral space.
2. An increase in vertical intraoral space.
3. A forward positioning of the mandible.
4. The development of new patterns of motor function, the
improvement of muscle tonus, and the establishment of a
proper oral seal.

EFFECTS: (AJO-1985-AUG)
1. The appliance has little or no effect on maxillary skeletal
structures, depending upon the landmarks measured. The effect
on the position of point A reflects the treatment effect on
underlying dental elements.
2. The forward movement expected of the maxillary molar is
reduced (0.7 to 1.4 mm), but the normal vertical movement is not
reduced.
3. There is some upper incisor tipping in a lingual direction (2.3
to 2.7 mm).
4. There is tipping of the lower incisors (0.5 to 1.2 mm).

5. There is increased vertical eruption of the lower molar (1.7 to
1.8 mm). There is no horizontal advancement of these teeth with
respect to the mandibular body, but there is substantial
advancement with respect to maxillary structures.
6. Fränkel treatment displaces the mandibular body parallel to
itself along the facial axis. On the average, the mandibular plane
angle and the facial axis angle show no treatment effect; vertical
measures of lower facial height show a great treatment effect
(1.3 to 3.1 mm); measures of chin position show an effect that
varies according to the choice-of measure.

THE MODIFIED BASS APPLIANCE:
The Bass removable orthopedic appliance system1-4 can be
used in growing patients with skeletal Class II malocclusions to
optimize facial appearance and to rapidly and effectively correct
the Class II dental relationship.

MANDIBULAR GROWTH ADVANCER: (MGA)
It advances the mandible progressively with a splint, with the objective
of remodelling the condyle and the glenoid fossain the TMJ.
The MGA functions as follows:-
1. As the upper and lower splints are made separately and are fixed by
cold-curing acrylic in a new construction bite within the oral cavity, the
MGA can be fit more easily and effectively in three-dimensional mandibular
adjustments. In other words, this appliance achieves an exact construction
position and changes it progressively.

2. To correct a Class II relationship into a Class I relationship,
the mandibular position must sometimes be overcorrected into
a Class I relationship horizontally, namely, a Class III
relationship. With this appliance, it is possible to go from a
Class II to a Class III relationship with only one appliance
throughout the treatment period.
3. While improving the horizontal problem, it is possible to
selectively allow the vertical eruption of posterior teeth by
trimming the occlusal shelf, as anterior teeth are impeded by an
anterior ledge.
4. Since this appliance is simple, it can be used concomitantly
with a fixed appliance. Thus tooth irregularity can be corrected
simultaneously with the correction of the skeletal discrepancy.www.indiandentalacademy.com

TWO-PIECE CORRECTOR
The Two-Piece Corrector described in this article was designed
to apply biological forces that will counteract any Class III
developmental vectors, whether skeletal or dentoalveolar, and
correct or minimize their effects on the patient.
It is a removable acrylic appliance that simultaneously applies
an anterior force to the maxilla and an equal posterior force to
the mandible. The flat, sliding surfaces of the two pieces create
almost no friction as the dentition is disoccluded during
movement, but provide both lateral and anteroposterior stability.

THE TWIN BLOCK:
Twin blocks are simple bite-blocks that achieve rapid
functional correction of malocclusion by the transmission of
favorable occlusal forces to occlusal inclined planes that cover
the posterior teeth.
The forces of occlusion are used as the functional
mechanism to correct the malocclusion.

AFFECTS OF TWIN BLOCK:
•Mandibular protrusion.
•Lip seal.
•Favorable position of occlusal inclined plane.

AJO-1988-JAN EFFECTS
1. Reduction in the anteroposterior apical base discrepancy on
angular assessment of ANB angle
2. Increase in effective mandibular length (articulare to gnathion)
3. Increase in length of the facial axis (cc to gnathion)
4. Increase in facial height (nasion to menton). The majority of
patients in the control sample had deep overbite and the aims of
treatment were consistent with increasing facial height.
5. Reduction in facial convexity (A point to facial plane)
6. Reduction in the distance from the distal outline of the upper
first molar to the pterygoid vertical.

Skeletal changes as a result of Twin Block therapy AJO1998 JAN
1. A mean forward growth/repositioning of the mandible of 2.4 mm,
measured at Ar-Pog, was demonstrated after Twin Block therapy.
2. The most noticeable skeletal change was an increase in the angle SNB.
3. No significant maxillary restraint could be demonstrated.
4. There was an increase in lower anterior facial height.
Dental changes as a result of Twin Block therapy
1. The mean overjet reduction of 7.5 mm involved a net 10.8° retroclination
of the upper incisors and 7.9° proclination of the lower incisors.
2. Buccal segment correction occurred by distal movement of the upper
molars and lower molar eruption in an anterior and superior direction.

EFFECTS: (AJO-1999-TOTH & McNAMARA)
Maxillary skeletal effects:
• Does not produce clinically significant restriction of maxillary growth.
Mandibular skeletal effect:
• Lund and Sandler reported an average increase in the distance from
articulare to gnathion of 2.4 mm during a 12 month period of twin block
treatment.
• The additional increase in condylon to gnathion length of 3 mm.
Vertical changes:
3 mm increase inlowe anterior facial height.
3.2 mm increase in posterior facial height.

THE MAGNETIC FUNCTIONAL SYSTEM: (MFS)
CHARACTERISTICS:
•High force-to-volume ratio.
•Maximal force at short distances.
•3-dimensional centripetal orientation of attractive
magnetic force.
•No interruption of magnetic force lines by
intermittent media.
•No friction in attractive force configuration.
•No energy loss.

FIXED FUNCTIONAL APPLIANCES:

•It is fixed to the teeth.
•Patient compliance is not required for its correct
function.
•It works 24 hours a day.
•Treatment time is short.

PUSHING FORCES

PULLING FORCES

HERBST APPLIANCE:
Treatment effects:
It is most powerful and effective modality in the treatment of c-II
malocclusions. The improvement in the sagittal and vertical occlusal
relationships during treatment is a result of both skeletal and dental
changes. (Pancherz 1982 ab)
Sagittal changes:
skeletal changes:
•Restrains maxillary growth and stimulates mandibular growth.
•Bone remodelling processes in lower mandibular border change the
morphology of the mandible.
•The articular fossa is repositioned anteriorly in the skull.www.indiandentalacademy.com

Dental changes:
•Mandibular teeth move anteriorly, the incisors procline.
•Maxillary molars move posteriorly.
Vertical changes:
Overbite reduction:
•Primarly accomplished by intrusion of the lower incisors and enhanced
eruption of the lower molars.
•Partly proclination of lower incisors.
•Occlusal plane tipdown.
Effects on facial profile:
•Reduction of the herd & soft tissue profile convexity.
•Retrusion of u / l lips in relation to the esthetic line because of normal
nose & chin growth.

Effects on masticatory system:
Because the mandible kept continuously in a protracted position, the
harmonious interaction among the occluding teeth, masticatory muscles,
and jaw joint is challenged.
Muscle activity:
Normaliges EMG pattern of the muscles.
TMJ:
No adverse efect on the the TMJ over time.
Research evidence indicates anterior positioning of the articular fossa
however. www.indiandentalacademy.com

JASPER JUMPER: (Modified Herbst appliance)
The inter arch flexible-force module allows the patient greater freedom of
mandibular movement than that possible with the original bite-jumping
mechanism of Herbst.
Treatment effects:
Maxillary adaptations:
Headgear effect:
•Distalization of the upper segment , or headgear effect.
•Light forces (2—4 ounces) expressed by modules to distalize the upper
molars.
•Because the forces are resisted by the entire lower dentition , minimal
changes in mandibular dentition are noted.

Retraction of anterior teeth:
Ni-Ti or inter maxillary elastic attached to the pin through the face-bow
tube can be used to retract the upper canines or six anterior teeth at once.
Mandibular adaptations:
If mandibular advancement is desired, the level of force generated by the
module is generally greater (6-8 ounces) than that generated if maxillary
molar distalization is intended. (2-4 ounces)
(AO 1994-2)
The JJ has little or no orthopedic effect on horizontal mandibular growth.
C-II correction primarily by dento-alveolar movement and secondarily, by
basal maxillary restraint.

Concludes:
1.The maxilla underwent limited posterior displacement and continued its
normal inferior descent.
2.While the mandible showed little or no growth stimulation or
downward/forward glenoid fossa remodeling, it did rotate backward
(clockwise) slightly.
3.The maxillary molars underwent significant posterior tipping and relative
intrusion.
4.The maxillary incisors underwent significant posterior tipping and
extrusion/eruption.
5.The mandibular molars underwent significant anterior bodily movement
and tipping, and eruption/extrusion.
6.The mandibular incisors underwent significant uncontrolled forward
tipping and intrusion. www.indiandentalacademy.com

FORSUS-FATIGUE RESISTANT DEVICE:

MANDIBULAR PROTRACTION APLIANCE:
The Mandibular Protraction Appliances have proven reliable and
efficient in the correction of various aspects of Class II malocclusions,
including overjet, overbite, midline shift, spacing, and molar position.

THE EUREKA SPRING:
The forerunner to the Eureka Spring was a system devised by
Northcutt in 1974. The new device incorporates significant
changes to Northcutt’s design, including triple telescoping
action, flexible ball-and-socket attachments, a completely
encased spring that remains intact even if the device becomes
disengaged, and a shaft for guiding the spring.

The Universal Bite Jumper
The Universal Bite Jumper, can be used in all phases of treatment, in the
mixed or permanent dentition, and with removable or fixed appliances.
Like other mandibular propulsion appliances, the UBJ uses a telescoping
mechanism; an active coil spring can be added if necessary. The UBJ can
also be used in Class III cases if mounted in a reverse configuration.

ADJUSTABLE BITE CORRECTOR:
A new device, the Adjustable Bite Corrector (Fig. 1), functions similarly to
the Herbst and Jasper Jumper, but incorporates several useful features not
found in the others.
•Universal Right and Left.
•Adjustable Length and Force.
•Stretchable Spring.
•Attachment Parts.
Special molar clips allow easy removal and replacement of the
end piece at the upper molar headgear tube, for quick repair or
adjustment during treatment

The Churro Jumper
The Churro Jumper furnishes orthodontists with an effective
and inexpensive alternative force system for the anteroposterior
correction of Class II and Class III malocclusions.
Although the Churro Jumper was conceived as an
improvement to the MPA, it functions more like the Jasper
Jumper.

THE SUPER SPRING:

SAIF SPRING:

THE MANDIBULAR ANTERIOR REPOSITIONING
APPLIANCE:

MANDIBULAR LOCKING UNIT:

VENTRAL TELESCOPE: (PROFESSIONAL
POSITIONERS)

THE BIOPEDIC APPLIANCE:

THE RITTO APPLIANCE:

THE TWIN FORCE BITE CORRECTOR:

ALPERN C-II CLOSURE

conclusion
In per suit of ideals in orthodontics, facial
balance and harmony are of equal importance to
dental and occlusal perfection. We cannot afford
to ignore the importance of orthopaedic
techniques in achieving these goals by growth
guidance during the formative years of facial
and dental development.

Effects and Uses of Functional Appliances

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Effects and Uses of Functional Appliances