Welcome to Indian Dental Academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy has a unique training program & curriculum that provides students with exceptional clinical skills and enabling them to return to their office with high level confidence and start treating patients
State of the art comprehensive training-Faculty of world wide repute &Very affordable.
Activator therapy /certified fixed orthodontic courses by Indian dental academy
INDIAN DENTAL ACADEMY
Leader in continuing dental education
3.History of functional appliance
4 Studies of functional appliance therapy
5 Principles of functional appliance therapy
6.Cephalometric diagnosis for functional appliance therapy
7.History of activator
9.Mode of action of activator
10.Force analysis in activator therapy
11 .Construction bite
12. Fabrication and management of
13. Trimming of the activator
14. Modifications of Activator
15.The Bionator—a Modified
16. The Bimler Appliance
17. Review of literature
he term "functional appliance" refers to
a variety of removable appliances designed
to alter the arrangement of various muscle
groups that influence the function and
position of the mandible in order to
trasmit forces to the dentition and the
basal bone. Typically these muscular
forces are generated by altering the
mandibular position sagittally and
vertically,resulting in orthodontic and
Functional appliances have been used since the
1930s. Despite this relatively long history, there
continues to be much controversy relating to
their use,method of action, and effectiveness.
Although there are a number of functional
appliances used by clinicians, the activator used
to correct Class II malocclusions.
HISTORY OF FUNCTIONAL
• Four men out of the past who came forward with a
fundamentally new approach to orthodontics
Norman W. Kingsley
Alfred P. Rogers
• In 1880, Kingsley introduced the term and
concept of "jumping the bite" for patients
with mandibular retrusion.
• He inserted a vulcanite palatal plate
consisting of an anterior incline that
guided the mandible to a forward position
when the patient closed on it.
• This maneuver corrected the sagittal
relationship without tipping the lower
• Vorbissplatte was a modified
• Hotz used the appliance in cases of
overbite was likely to cause a
retrognathism, and the lower incisors
hyperactivity of the mentalis muscle
and lower lip. www.indiandentalacademy.com
• Impressed by Kingsley's concepts and appliances,
Andresen developed a mobile, loose fitting
appliance modification that transferred
functioning muscle stimuli to the jaws, teeth, and
• The progenitor of the appliance was a modified
Kingsley plate that Andresen used as a retainer
over summer vacation for his daughter after he
removed fixed appliances used to correct a
Seeing the continued improvement with this
retainer, he called www.indiandentalacademy.com working
it a biomechanic
• Some years before Andresen started
experimenting with his working retainer,
• Robin had created an appliance quite similar in its
objectives. The monobloc, as he called it (because
it was a single block of vulcanite), positioned the
mandible forward in patients with glossoptosis
and severe mandibular retrognathism who risked
occluding their airways with their tongues.
• Robin noted that forward mandibular posture
reduced this hazard and also led to significant
improvement in the jaw relationship. The problem,
usually associated with cleft palate, became
known as the Pierre Robin syndrome.
• Familiar with the work of Roux, who subscribed to
hypothesis, the time Andresen and Haupl teamed
up to write about their appliance, they called it an
activator, be-cause of its ability to activate the
• NEUROMUSCULAR RESPONSE
success of functional appliance
therapy depends on
the neuromuscular response. Children
with neuromuscular diseases such as
poliomyelitis and cerebral palsy
• The first
• Historically, the term "activator" was
introduced to describe the
"activation of mandibular growth," to
which the achieved correction of a
Class II malocclusion was attributed .
appliances position the
mandible forward, promoting a new
mandibular postural position.
• The reactive forces from the
stretch of the muscles and soft
tissues are transmitted to the
maxillary dentition and through that,
to the maxilla.
• The acrylic body of the Andresen
activator covers part of the palate
and the lingual aspect of the
mandibular alveolar ridge.
• A labial bow fits anterior to the
maxillary incisors and carries U-loops
• On the palatal aspects of the
maxillary incisors, the acrylic is
relieved to allow their retraction.
EFFICACY OF THE
• According to Andresen and Haupl
(1955), the activator is effective in
exploiting the interrelationship
between function and changes in
internal bone structure.
• The activator induces
musculoskeletal adaptation by
introducing a new pattern of
• Neuromuscular adaptation to
the increased distance and
changes in direction is the
reeducating the orofacial
• The adaption in the functional
pattern caused by the activator and
also include and affect the condyles.
• Condylar adaptation to anterior
positioning of the mandible consists
of growth in an upward and backward
direction to maintain the integrity of
• This adaptation is induced by a loose
appliance. The construction bite does
not open the mandible beyond
postural rest position
• Myotatic reflex activity is
stimulated, causing isometric muscle
contraction. This muscle force
transmitted by the appliance moves
the teeth. Thus the appliance works
by kinetic energy.
• Although Andresens and Haupl's
original concept and working
hypothesis have been discussed and
practiced for 55 years, they are still
controversial; some authorities
accept some or all of their ideas,
whereas others completely reject
Classification of veiws
• depending on the construction of the
appliance, the activator can initiate
myotatic reflex activity, induce
isometric muscle contractions
(sometimes also inducing isotonic
contractions), or rely on the
viscoelastic properties of the
stretched soft tissues.
• According to the mode of action, two
main principles apply. A third
approach combines the two
• 1. According to the original AndresenHaupl concept, the forces generated in
activator therapy are caused by muscle
contractions and myotatic reflex activity.
• A loose appliance stimulate the muscle and
the moving appliance moves the teeth.
• The muscles function with kinetic energy
and intermittent forces are clinically
• 2. According to the second working
hypothesis, the appliance is squeezed
between the jaws in a splinting
• The appliance exerts forces that
move the teeth in this rigid position.
• The stretch reflex is activated,
inherent tissue elasticity is
operative, and strain occurs without
• The appliance works using potential
• For this mode of action an
overcompensation of the construction bite
in the sagittal or vertical plane is
• An efficient stretch action is achieved by
overcompensation and the viscoelastic
properties of the contiguous soft tissues.
SKELETAL AND DENTOALVEOLAR
EFFECTS OF THE ACTIVATOR
• 1.Any skeletal effect from the
activator depends on the growth
• Two divergent growth vectors propel
the jaw bases in an anterior direction
• a.The sphenoccipital synchondrosis
moves the cranial base and
nasomaxillary complex up & forward.
• b.The condyle translates the
mandible in a downward and forward
• The activator is most effective in
controlling the lower vector or the
downward and forward growth of the
• Johnston (1976) attributes this
response to "unloading the condyle."
• Only the upward and backward
growth of the condyle is capable of
moving the mandible anteriorly
• As the research by Petrovic has shown,
the LPM plays a decisive role in this
• Forward posturing of the condyle
activates the superior head of the LPM.
• In young people this induces a cell
proliferation in the condyle and a growth
• The activator can, to a limited degree
control the upper growth vector, supplied
by the sphenoccipital synchondrosis,which
moves the maxillary base forward.
• If the mandible cannot be positioned
anteriorly, maxillary growth can be
inhibited and redirected.
• activator also must assess and, if
necessary, alter the vertical skeletal
• Changing the maxillary base inclination can
compensate for rotations of mandibular
• A downward displacement of the maxillary
base allows the maxilla to adapt to a
vertical rotation of the mandible.
• If the rotation of the jaw bases during
growth is unfavorable, activator therapy
cannot be completed successfully.
• If the activator is constructed with a
vertical opening of the bite only or with
minimal sagittal change, the effect is
primarily on midfacial development in the
subnasal area. Both vertical maxillary
growth and eruption of the teeth are
• Woodside believes that a small
vertical opening restricts only
horizontal midfacial development,
whereas a wide vertical opening
achieves the restriction by
downward displacement of the
• 2. The dentoalveolar efficiency of
the activator helps achieve, a primary
• Teeth and bones fill in the space
between the two divergent growth
• The dentoalveolar effect of the activator
is to control tooth eruption and alveolar
• For this reason the activator is most
effective if used in the early mixed
• With proper trimming of the appliance,
different movements can be performed
and the eruption of the teeth can be
FORCE ANALYSIS IN
• When the functional appliance
activates the muscles various types
of forces are created—
• Two principles are employed in the
• Force application —the source is
• Force elimination —the dentition is
shielded from normal & abnormal
functional and tissue pressures by
pads, shields, and wire
• The types of force employed in activator therapy
may be categorized as follows:
• 1.The growth potential, including the eruption
and migration of teeth, produces natural forces.
These can be guided promoted, and inhibited by
• 2.Muscle contractions and stretching of the soft
tissues initiate force when the mandible is
relocated from its position by the appliance. The
activator stimulates and transforms the
contractions. Whereas forces may be functional
(muscular) in origin, their activation is artificial.
These artificially functioning forces be effective
in all three planes:
• a. In the sagital plane the mandible is
propelled down and forward, so that
muscle force is delivered to the
condyle and a strain is produced in
the condylar region.
• A slight reciprocal force can be
transmitted to the maxilla during
• b.vertical plane the teeth and alveolar
processes are either loaded with or
relieved of normal forces.
• If the construction bite is high, a greater
strain is produced to the contiguous
• If transmitted to maxilla these forces can
inhibit growth increament and direction
and influence the inclination of
• c. In the transverse plane, forces
also can be created with midline
• 3.Various active elements (e.g.,
springs, screws) can be built into the
activator to produce an active
biomechanic type of force
• Proper activator fabrication requires the
determination and reproduction of the correct
construction or working bite.
• The purpose of this mandibular manipulation is to
relocate the jaw in the direction of treatment
objectives. This creates artificial functional
forces and allows assessment of the appliance's
mode of action. Before taking the construction
bite, the clinician must prepare by making a
detailed study of the plaster casts, cephalometric
and panoral head films, and the patient's
• Creating an "instant correction"—
moving the mandible forward into
an anterior more normal sagittal
relationship—may help motivate
patients with Class II malocclusions.
Study model analysis
– Before constructing the activator, the clinician
must consider the following factors, based on the
– 1. First permanent molar relationship in habitual
– 2. Nature of the midline discrepancy, if any:
3. Symmetry of the dental arches:
– 4. Curve of Spee:
– 5. Crowding and any dental discrepancies:
– Functional analysis. Before the construction bite
is taken,a functional analysis is performed to
obtain the following information:
– 1. Precise registration of the postural rest
position in natural head posture (because the
vertical opening of the construction bite depends
– 2. Path of closure from postural rest to habital
occlusion(any sagittal or transverse deviations
• 3. Prematurities, point of initial contact,
occlusal interferences, and resultant
mandibular displacement, if any (some of
these can be eliminated with the activator,
but some require other therapeutic
• 4. Sounds such as clicking and crepitus in
the TMJ (might indicate a functional
abnormality or the need for some
modification of appliance design)
• 5. Interocclusal clearance or freeway
space (should be checked several times
and the mean amount recorded)
• 6. Respiration (with allergies or disturbed
nasal respiration, the patient cannot wear
a bulky appliance; in such cases an open
activator or twin block may be used, or
the respiratory abnormalities may be
• The extent of anterior positioning for Class II malocclusion
and posterior positioning for Class III malocclusions should
• Anterior positioning of the mandible. The usual
intermaxillary relationship for the average Class II problem
is end-to-end incisal. However, it should not exceed 7 to 8
mm, or three quarters of the mesiodistal dimension of the
first permanent molar, in most instances.
• Anterior positioning of this magnitude is contraindicated if
any of the following pertain:
1.The overjet is too large:
2.Labial tipping of the maxillary incisors is severe:
• 3.An incisor (usually a lateral) has erupted
markedly to the lingual: The mandible must be
postured anteriorly to an eidge-to-edge
relationship with the lingually malposed tooth;
otherwise, labial movement of this tooth will be
• Eschler (1952) termed the condition a pathologic
construction bite. As with severely proclined
upper incisors, use of a short prefunctional
appliance to improve alignment of lingually
malposed teeth is advisable before starting
activator treatment, thereby eliminating the need
for the pathologic construction bite.
• Opening the bite. Vertical considerations are as important
as the sagittal determination and are intimately linked to it.
Maintaining a proper horizontal-vertical relationship and
determining the height of the bite are guided by the
• 1. The mandible must be dislocated from the postural
resting position in at least one direction—sagittally or
vertically. This dislocation is essential to activate the
associated musculature and induce.a strain in the tissues.
• 2.If the magnitude of the forward position is great (7 or 8
mm), the vertical opening should be minimal so as not to
overstretch the muscles. This type of construction bite
produces an increased force component in the sagittal
plane, allowing a forward positioning of the mandible.
• 3. If extensive vertical opening is needed,
the mandible must not be anteriorly
positioned. If the bite opening exceeds 6
mm, mandibular protraction must be very
slight . Myotatic reflex activity of the
muscles of mastication can then be
observed, as can a stretching of the soft
tissues. The vertical relationship, either
deep bite or open bite,can be
therapeutically affected by the activator.
• Disadvantages of a wide-open construction
bite include the difficulty of wearing the
appliance and adapting to the a new
relationship. Muscle spasms often occur,
and the appliance tends to fall out of the
mouth. The high construction bite also
makes lip seal difficult if not impossible.
• The ultimate reestablishment of normal lip
seal is esential in functional appliance
General rules for the
• The assessment of the construction
bite determines the
• kind of muscle stimulation,
• frequency of mandibular movements,
• duration of effective forces.
• In a forward positioning of the mandible of 7 to 8 mm the
vertical opening must be slight to moderate (2 to 4 mm).
• 2. If the forward positioning is no more than 3 to 5 mm the
vertical opening should be 4 to 6 mm.
• 3. The activator can correct lower midline shifts or
deviations only if actual lateral translation of the mandible
itself exists. If the midline abnormality is caused by tooth
migration, no asymmetric relationship exists between the
mandible and maxilla. An attempt to correct this type of
dental problem could lead to iatrogenic asymmetry.
Functional crossbites in the functional analysis can be
corrected by taking the proper construction bite.
• Execution of the Construction '
• A construction bite prepared on casts
may have the following disadvantages:
• It may not fit.
• Asymmetric biting may have occurred on
• The patient may not be really
comfortable and may be disturbed more
frequently during sleep.
• The likelihood of unwanted lower incisor
procumbency may be greater, because the
appliance exerts undue stress on these
Technique for a
• Technique for a
Bite with Slightly
• Technique for a
• Construction Bite
with Opening and
Positioning of the
MANAGEMENT OF THE
If the patient is wearing the activator without difficulty and
fowllowing instructions, checkup appointments should be scheduled
every 6 weeks. During these office visits the clinician should
maintain rapport with the patient, reinforce motivation, and
perform the following procedures:
1. All guide planes that have been ground and all areas in contact
with the teeth should be observed for shiny surfaces that indicate
whether the appliance is being worn correctly and is working
2. Reshaping of acrylic guide areas may be required after initial
trimming to improve function; it also may be needed during the
course of treatment to ensure continued tooth movement
(particularly in the upper arch) if retrusion or distalization is
desired. Maxillary change is usually minimal at best, however. If
the permanent teeth are erupting, reshaping also may be motion of
the appliance in the mouth may change wire configurations and
occasionally fatigues wires sufficiently to cause necessary.
• 3. Acrylic contact guide planes often must be
resealed or recontoured to maintain the proper
functional activation on the desired teeth by
adding self-curing soft acrylic in a thin layer.
Clinical examination of the acrylic inclined planes
for shiny spots helps determine the amount of
sealing to be done.
• 4. The labial bows and any additional wire
elements must be checked for action and possible
deformation. The active bow should touch the
teeth. The passive bow should position away from
the teeth but remain in contact with the soft
tissues. The guiding and stabilizing wires are
activated by the patient's biting into the
• 6. In expansion treatment the
jackscrews are normally activated by
the patient at 2-week intervals. The
clinician should check this activation
for too-frequent or infrequent
activation. Too much activation
prevents the appliance from fitting
properly. The activation interval may
need to be changed.
• Herren Shaye
activator : Herren
activator in two
• 1. By overcompensating the
ventral position of
the mandible in the
• 2. By seating the
arch by means of
The Bow activator of A.M
• The bow activator is a horizontally
split activator having a maxillary
portion and a mandibular portion
connected together by an elastic
bow. This kind of modification allows
step wise sagittal advancement of
the mandible by adjustment of the
• This is an activator modification that
is mostly used in treatment of Class
Reduced activator or
cybernator of Shmuth :
• This modification of the activator is
proposed by Professor G.P.F. Schmuth.
This appliance resembles a bionator with
the acrylic portion of the activator
reduced from the maxillary anterior area
leaving a small flange of acrylic on the
• The two halves may be connected by an
omega shaped palatal wire similar to
Hyperpropulsor Activator GEORGES GAUMOND, 1986 Jun JCO
from the monobloc
of Robin, consists
of a bimaxillary
block of acrylic
made with the bite
open and the
mandible in a
• The incisal edges of the upper and
lower incisors should be separated
12-15mm, with the only limit to
hyperpropulsion being the discomfort
of the patient. Extraoral force is
used with the appliance, which is
worn only at night.
• The appliance is most useful in younger children when a
sizable overjet raises fear of incisal fracture.
• The appliance is also effective in Class II, division 1 cases
when a small tooth-to-jaw size relationship would
contraindicate extraction; in cases of missing upper
bicuspids or molars, especially if there is already
spontaneous space closure; and in cases of poor cooperation
with fixed appliances.
• The appliance can be used in cases of posterior rotation,
since it does not alter the vertical dimension.
• It also permits, to the extent of the individual's growth
potential, a reduction of the discrepancy between the
maxillary and mandibular bony arches— either by acting on
the maxilla through varying the extraoral force, or by
acting on the mandible through acrylic added as soon as the
patient can propulse beyond the initial registration.
Cut out or Palate free
This is a modification proposed by
Metzelder to combine the
advantages of bionator and the
The mandibular portion of the
appliance resembles an activator
while the maxillary portion has
acrylic covering only the palatal
aspect of the buccal teeth and a
small part of the adjoining gingiva.
The palate thus remains free of
acrylic thereby making the
appliance more convenient for
patients to wear the appliance for
Due to the greater amount of
wearing time, success should be
greater with the palate free
• This consists of maxillary and mandibular plates joined by a
'U' bow in the region of the first permanent molar.
• Type I: This is used in the treatment of Class II, Division
1. In this modification, the larger lower leg is placed
posteriorly. Thus when the two arms of the U bow are
squeezed the lower plate moves sagitally forwards
• Type II : This is used for the treatment of Class III
malocclusion. In this appliance the larger lower leg is placed
anteriorly. Thus when the U bow is squeezed the mandibular
plate moves distally.
• Type III: They are used in bringing about asymmetric
advancements of the mandible. The U bow is attached
anteriorly on one side and posteriorly on the other side to
allow asymmetric sagital movement of the mandible
Bimler appliance (Bite
former, Bimler stimulator)
• A modification of the activator by H.P.
Bimler. There are three main kinds of
• type A for patients with Class II Division 1
• type B for those with Class II Division 2
• type C for patients with a Class III
Elastic open activator
• A modification of the activator
developed by G. Klammt. The
appliance has reduced acrylic bulk,
facilitating increased appliance wear.
The acrylic is replaced by wires
which increase the flexibility of the
appliance. The flexible design allows
isotonic muscular contractions (in
contrast to rigid appliances, which
only allow isometric contractions).
Herren activator (L.S.U.
• A modification of the activator developed
by P. Herren (also known as the Louisiana
State University modification of the same
• It is essentially an activator made to a
construction bite that positions the
mandible forward and downward to a
• According to P. Herren, the wearing of
this appliance iswww.indiandentalacademy.com increase
not supposed to
the activity of the lateral pterygoidmuscle
Lehman appliance (Lehman
A combination activator-headgear appliance developed by
R.Lehman. It consists of a maxillary acrylic plate that carries two
rigidly fixed outer bows and a mandibular lingual shield. The acrylic
plate covers the palate and it extends over the occlusal and incisal
surfaces of the maxillary teeth, up to the occlusal third of their
buccal and labial surfaces.
Selective expansion of the maxillary arch is possible by
appropriately activating the two transverse expansion screws (one
anterior and one posterior) that are embedded in the plate.
Occipital traction is applied through a headstrap attached on the
outer bows, which are fixed at the anterior aspect of the
appliance. The mandibular lingual shield is connected to the
maxillary plate by means of two heavy S-shaped wires. Unlike many
activator type appliances which are constructed with the mandible
in a protruded position, this appliance is made from a bite
registration taken in centric occlusion.Accordingto R.Lehman, the
S-shaped wires are activated by approximately 2 mm every 4 to 6
weeks, to achieve a gradual advancement of the mandible.
• A modified activator used in combination
with a high-pull headgear.
• The appliance was introduced by U.M.
Teuscher and P.W. Stockli as a means to
avoid the detrimental profile effects of
cervical traction when treating Class II
malocclusions in growing individuals. Buccal
headgear tubes are incorporated in the
interocclusal acrylic at the level of the
maxillary second premolar or first molar.
Nocturnal airway patency
• By Peter T George (JCO)1987
• NAPA was designed to keep the airway open
during sleep by Posturing the tongue more
anteriorly. inhibiting wide jaw opening. assuring
adequate air intake through the mouth when ever
nasal obstruction exists.
• The mandible was postured forward to advance
the tongue relative to the posterior pharyngeal
wall. Because the genioglossus originates at the
inner surface of the mandibular symphysis and
inserts into the tongue,the mandibular protrusion
brings the tongue forwards.
• By Levrini .A (JCO 1996)
• The OSA is a modified bionator that
incorporates principles developed by
Bimler, Klammt,Stockfisch, and Woodside.
It is a composite myodynamic functional
appliance, with a rigid frame of acrylic
resin and stainless steel wires connected
to elastomeric occlusal pads.
Indications of activator :
It is primarily used in actively growing individuals with favorable growth
The maxillary and mandibular teeth should be well aligned.
The mandibular incisors should be upright over the basal bone.
The following are some of the indications forthe use of activator :
1. Class II, Division 1 malocclusion
2. Class II, Division 2 malocclusion
3. Class III malocclusion
4. Class I open bite malocclusion
5. Class I deep bite malocclusion
6. As a preliminary treatment before major fixed appliance therapy
to improve skeletal jaw relations
7. For post-treatment retention
8. Children with lack of vertical development in lower facial height.
• 1. The appliance is not used in correction of Class
I problems of crowded teeth caused by
disharmony between tooth size and jaw size,
• 2. The appliance is contraindicated in children
with excess lower facial height and extreme
vertical mandibular growth.
• 3. The appliance is not used in children whose
lower incisors are severely procumbent.
• 4. The appliance cannot be used in children with
nasal stenosis caused by structural problems
within the nose or chronic untreated allergy.
• 5. The appliance has limited application in nongrowing individuals.
Advantages of activator
• 1. It uses existing growth of the jaws.
• 2. During treatment the patient
experiences minimal oral hygiene problems.
• 3 .The intervals between appointments is
• 4. The appointments are usually short due
to need for minimal adjustments.
• 5. Due to the above reasons they are more
Disadvantages of activator
• 1. Requires very good patient cooperation.
• 2. The activator cannot produce a precise
detailing and finishing of the
occlusion.Thus post-treatment fixed
appliance therapy maybe needed for
detailing of the occlusion.
• 3. It may produce moderate mandibular
rotation (anteriorly downwards). Thus
activators are not used in cases of
excessive lower face height.
Activators As Retainers
1980 Aug(529 - 545)]:
• Many severe Class II cases are treated
with fixed appliances to completion before
jaw growth is completed.
• The posttreatment growth pattern
occasionally causes the case to relapse
back into a Class II relationship. The
activator is very useful for retaining these
cases, especially where there was a deep
bite involved. A strong relapse tendency
will also require directional headgear
The studies summarized in this chapter have
led to the following conclusions, which may
influence the clinician's approach to functional
1. Removable functional appliances used part time do not routinely
create clinically useful increases in mandibular length.
2. Redirection of maxillary growth direction may occur with either
a large or moderate vertical opening of the construction bite.
3. Successful redirection of maxillary growth direction is always
followed by recovery toward the normal path of growth direction.
However, a net restriction in midface position occurs.
5. Both the function regulator and bionator activator create
similarly increased amounts of LPM activity at appliance insertion.
6. The insertion and progressive activation of a functipnal
appliance produce a decrease in the resting and functional activity
of the muscles of mastication.
7. Chronic condylar unloading produces a rapid down ward and
forward relocation of the glenoid fossa; this relocation
The Bionator—a Modified
-Developed by Balter
-Termed by Kantorowicz
Kantorowicz's assessment of the bionator is essentially correct in
(1) The bionator is, in fact, considerably less bulky than the
activator. It lacks the part covering the anterior section of the
palate, which is contiguous to the tongue. Children are therefore
immediately able to speak normally, though the appliance fits
loosely in the mouth.
Thus, it is possible to require that the bionator be worn day and
night except at meals. It is feasible for wear during school. An
important feature of the bionator is its freedom of movement in
the oral cavity. It would be totally incorrect and detrimental to fix
it by any device on either the maxillary or mandibular teeth.
(2) To Balters, the essential factor is the
tongue. To quote him, "The equilibrium between
tongue and cheeks, especially between the tongue
and the lips in the height, breadth and depth in in
an oral space of maximum size and optimal limits,
providing functional space for the tongue, is
essential for the natural health of the dental
arches and their relation to each other. Every
disturbance will deform the dentition and during
growth that may be impeded too. The tongue is
the essential factor for the development of the
dentition. It is the center of the reflex activity
in the oral cavity."
According to Balters, the essential points for treatment are
to accomplish lip closure and bring the back of the tongue into
contact with the soft palate;
to enlarge the oral space and to train its function;
to bring the incisors into an edge to edge relationship—like Begg,
he feels that this is a natural bodily orientation;
by virtue of the preceding, to achieve an elongation of the
mandible, which, in turn, will enlarge the oral space and make the
improved tongue position possible;
to achieve an improved relationship of the jaws, tongue and the
dentition, as well as the surrounding soft tissues, as a result.
• The treatment of Class II, division 1
malocclusions in the'-mixed dentition using the
standard bionator is indicated under the
• 1. The dental arches are well aligned originally.
• 2. The mandible is in a posterior position (i.e.,
• 3. The skeletal discrepancy is not too severe.
• 4. A labial tipping of the upper incisors is
• The bionator is not indicated if the
following is true:
• 1. The Class II relationship is caused by
• 2. A vertical growth pattern is present.
• 3. Labial tipping of the lower incisors is
evident. Anterior posturing of the
mandible with simultaneous uprighting of
the lower incisors cannot be performed
with the bionator.
• The main purpose is to prevent the riding of the
condyle over the posterior edge of the disk, which
causes the clicking.
• By checking clinically, first in habitual occlusion
and then in a forward postured mandible, the
operator can determine how far forward the
mandible must be brought to eliminate the
clicking on the opening maneuver. The clicking
usually disappears in these cases when the
mandible is opened in the forward posture. This
means that the condyle no longer rides over the
posterior disk margin, onto the retrodiscal pad.
• 1. MAD II FOR
CORRECTION OF CLASS
II DIV 1 MALOCCLUSION
Am J Orthod 1993
M.Darelinder,A.Jean Pierre Joho.
• SAMARIUM COBALT
Magnets are incorporated
on the buccal aspects of
the upper and lower
MAD can be used as
• -for correction of mandibular lateral
deviation (MAD I)
• -for class II malocclusions (MAD II)
• -for class III malocclusion (MAD
• -for open bite cases (MAD IV)
Tongue function during activator treatment. A
cephalometric and dynamometric study by Johan
• The results seem to verify
Andresen's hypothesis that tongue
activity is stimulated by activators
but they do not support his view that
wearing an activator would result in
permanent hypertrophy of the
How effective is the combined
By Olav Bondevik (EJO 1991)
• The frequency and possible causes of failure and success
with the combination activator-headgear as the sole
appliance was analysed retrospectively in 32 girls and 46
boys. The subjects comprised all the patients who started
treatment with this combination in the postgraduate
courses in 1972-82 at the Orthodontic Department of the
University of Oslo, and where fixed appliances were not
included in the initial treatment plan. Only 14 subjects
completed the treatment with entirely satisfactory results
according to strict criteria set for an acceptable standard.
Among the most co-operative patients less than 50 per cent
ended with entirely satisfactory results, and no one with
decreasing or poor co-operation had a satisfactory result.
Neither sex, treatment time, nor ossification of the ulnar
sesamoid bone seemed to influence the results significantly.
Treatment needs followingActivatorheadgear therapy
By Iav Bondevik, ( Angle orthod
• The purpose of this study was to analyze the types and
prevalence of malocclusions that remain to be corrected
after a period combined activator-headgear treatment.
Study models of all patients who started treatment with an
activator-headgear appliance in the graduate orthodontic
clinic at the University of Oslo between 1972 and 1982
• Results show that the most frequently remaining problems
following activator-headgear treatment were overbite,
overjet and the presence of interdental spaces. Correction
of the Class II skeletal and dental relationship was achieved
in the majority of the cases. The only predictor for success
was age at the time of treatment.
Combination Headgear-Activator - DR.
HERMAN VAN BEEK
JCO Volume 1984 Mar(185 - 189):
Clinical Aspects of Headgear-Activator Treatment
The headgear-activator has the following modes of action:
1. Intrusion and retraction of upper front teeth
2. Distalization of upper molars
3. Maxilla retraction
4. Mandibular growth stimulation, especially in the
5. Opening of the facial axis in the brachyfacial group
6. Maintenance of the facial axis in the dolichofacial group
7. Minor, if any, tilting of lower incisors
8. Stopping lower incisor eruption
9. Stopping the descent of the palate
Activator treatment - Vargervik
• Response to activator treatment in Class II malocclusions
• A clinical study was designed to disclose the effects of
activator treatment in the correction of Class II
malocclusions. The rationale for the use of the activator
appliance was based on the premise that correction of
distocclusion can be achieved by
• (1) inhibition of forward growth of the maxilla,
• (2) inhibition of mesial migration of maxillary teeth,
• (3) inhibition of maxillary alveolar height increase and
extrusion of mandibular molars,
• (4) increased growth of the mandible,
• (5) anterior relocation of the glenoid fossa,
• (6) mesial movement of mandibular teeth,
• (7) combinations of these effects.
• It was therefore concluded that, in
addition to the statistically significant
changes, smaller changes occurred in
several areas without being consistent
enough or of a large enough magnitude to
become statistically significant in the
analyses of mean values. Comparison of
group averages may mask treatment
effects that significantly contribute to
the correction of malocclusions in
A cephalometric analysis of skeletal and
dental changes contributing to Class II
correction in activator treatment
• Hans Pancherz,(Am J Orthod)1984
• The purpose of this investigation was to evaluate
cephalometrically the mechanism of
anteroposterior occlusal changes in activator
treatment. The sample consisted of thirty Class
II, Division 1 malocclusion cases treated
successfully with activators during an average
time period of 32 months. Before- and aftertreatment head films in centric occlusion were
analyzed. The occlusal line (OL) and occlusal line
perpendicular (OLp) through sella were used for
reference. Linear measurements were performed
parallel to OL..
The following results were found:
(1) The improvement in occlusal relationships in the molar and
incisor segments was about equally a result of skeletal and dental
(2) Overjet correction averaging 5.0 mm was a result of 2.4 mm
more mandibular growth than maxillary growth, a 2.5 mm distal
movement of the maxillary incisors, and a 0.1 mm mesial movement
of the mandibular incisors.
(3) Class II molar correction averaging 5.1 mm was a result of 2.4
mm more mandibular growth than maxillary growth, a 0.4 mm distal
movement of the maxillary molars, and a 2.3 mm mesial movement
of the mandibular molars.
(4) When the findings were compared with longitudinal records of
persons with normal occlusion (Bolton standards), activator
treatment seemed to inhibit maxillary growth, move the maxillary
incisors and molars distally, and move the mandibular incisors and
molars mesially. Mandibular growth appeared not to be affected by
Effects of Activator Treatment on Class II, Division
1 Malocclusion (JCO) Aug 1989 - DR. CHANG, DR.
KAI-MING WU, DR. KUN-CHEE CHEN,
This study was undertaken to evaluate the effects of activator
treatment on a group of Class II, division 1 patients with skeletal
Materials and Methods:
Nine boy and six girl patients from the Orthodontic Department,
National Taiwan University Hospital, were selected as the
treatment group. All were Chinese, and they ranged in age from
7.2 to 11.9 years, with a mean of 9.5 years. All were treated
exclusively with activators.
The untreated control group consisted of 21 boys and 14 girls,
with similar Class II, division 1 malocclusions, selected from the
growth studies of the School of Dentistry, National Taiwan
University. All were Chinese, and the mean age was 9.6 years.
Patients were asked to wear the appliances about 14 hours per day,
but no effort was made to measure cooperation.
Pretreatment cephalograms of the two groups were compared
statistically to confirm that there were no significant differences
in craniofacial morphology.
• Activator treatment in this study was
successful in girls and boys from age 7 to
12. Children from age 7 to 12 are highly
responsive to praise and positive
reinforcement and therefore tend to be
cooperative. Early functional appliance
treatment can correct any abnormal
muscular habits that might influence later
facial development and form.
Temporal muscle activity during the first year of
Class II, Division 1 malocclusion treatment with an
activator (1991 Apr) Am J Orthod
Bengt Ingerval and Urs Thüer,
• The activity of the anterior and posterior
temporal muscles in response to treatment
with a splint type of activator was studied
in children with distal occlusion.
• The effect on muscle activity was
compared with that in a similar group of
children being treated with a headgear and
with that in a control group receiving
orthodontic treatment for Class I
• The activity in the rest position was constant
during the 1-year period of observation. During
maximal bite the activity of the posterior
temporal muscle decreased significantly in the
group with headgear and the control group and in
a subgroup of children with large protrusions in
the construction bite who had been treated with
activators. This decrease was considered to be an
effect of occlusal instability brought about by
the treatment. There was no evidence of a
decrease in the postural (rest) activity of the
posterior temporal muscle, although such a
decrease has been described as a sign of forward
displacement of the mandible during treatment
with a functional appliance.
Functional treatment of condylar
fractures in adult patients E. K.
Basdra,A. Stellzig, Drmeddent, .
1998 Jun Am J Orthod
• Functional treatment of condylar
fractures in adult patients usually follows
the closed reduction/maxillomandibular
fixation approach. Some of the problems
arising when functional appliances (i.e.,
activator) are used have been identified
and presented here, especially in patients
where fractured parts are
• They conclude that activators are not the best means of
treating condylar fractures with displacements/dislocations
in adult patients. Therefore patients who after the removal
of the intermaxillary fixation show good occlusal
relationships should be only treated with the use of
intermaxillary elastics. Patients exhibiting anterior or
lateral open bites after intermaxillary fixation should be
treated with biteplates (half or posterior bilateral),
combined with vertical elastics, to reestablish the initial
occlusal relations. A small group of patients with condylar
fractures treated by the above functional concept has been
shown. They showed good response and reported no
complaints or discomfort 1 year later. The occlusion
recovered to the initial relationship and no selective
grinding was necessary after treatment. This approach
seems promising in the treatment of condylar fractures in
Skeletal profile changes related to two
patterns of activator effects - Luder
Volume 1982 May Am J Orthod
• A longitudinal cephalometric study
was carried out on twelve boys and
thirteen girls who initially exhibited
Class II, Division 1 malocclusion and
who were treated exclusively with
activators. Twenty-four boys and
fifteen girls, corresponding with the
experimental subjects with respect
to initial age and observation period,
were selected as controls.
The aim of the investigation was to examine cephalometric profile
changes associated with two patterns of effects of activator
treatment detected previously.
The findings demonstrate that the two types of reaction bring
about similar corrections of both apical base discrepancy and
dental Class II relationship but clearly differ in their effects on
the skeletal profile.
Whereas the first type of reaction results in an improvement in
mandibular retrognathism, a marked rotation of the occlusal plane,
and good vertical control of the upper and lower dental arches,
the second type is distinguished by a significant reduction of
maxillary prognathism, downward and backward rotation of the
mandible, and forward tipping of the lower incisors. Additional
evidence presented further suggests that the two patterns of
effects are due to differences in the construction bites of the
appliances. According to this hypothesis, a great interocclusal
height of an activator would lead to the first and a low
construction bite to the second type of reaction.
Orthodontic forces exerted by activators with varying
construction bite heights Takuji Noro, Kazuo Tanne, and
Mamoru Sakuda, AJO-DO1994 Feb
• The present study was conducted to investigate the nature
of forces induced with activators by measuring strains,
electromyogram (EMG) and electroencephalogram (EEG)
during a 2-hour sleep period. Fifteen adolescent patients
with Class II and Class III malocclusions, (30 subjects)
were used. Four types of activators were made for each
patient with construction bites taken at incisal edge
clearances of 2, 4, 6, and 8 mm vertically. The magnitude of
forces generated by passive tension of soft tissues
increased significantly (p < 0.01) from approximately in the
Class II group and also increased in the Class III group
with varying construction bite heights from 2 to 8 mm.
Higher construction bites also significantly changed (p <
0.01) the direction of forces by passive tension from
vertical to posterior and from vertical to anterior in
relation to the reference plane in the Class II and Class III
• Duration of forces generated by passive
tension was most significantly longer than
that of active contraction of the jaw
closing muscles, irrespective of the
construction bite heights. It is concluded
that passive tension, derived from
viscoelasticity of soft tissues, plays a
more important role in inducing changes
than phasic stretch reflex during jaw
orthopedic therapy with activators
Predicting functional appliance treatment outcome in Class
Susi Barton, and Paul A.
• Selecting cases suitable for treatment
with a functional appliance remains a
problem as much of the relevant literature
is anecdotal. There are also design and
methodologic differences between the
available studies, and most studies are
limited to the Andresen type of appliance.
The literature suggests that functional
appliances are most successful in cases
with an overjet of up to 11 mm, an
increased overbite, active facial growth,
and good cooperation. (Am J Orthod Dentofac Orthop
Catch them young
Watch them grow
Leader in continuing dental education