Non surgical management of skeletal Class 3 malocclusion

Non surgicalNon surgical
managementmanagement
ofof
skeletal class IIIskeletal class III
malocclusionmalocclusion

INTRODUCTION
ETIOLOGY
SYMPTOMS OF CLASS III MALOCCLUSION
FUNCTIONAL AND CEPHALOMETRIC ANALYSIS
CEPHALOMETRIC CLASSIFICATION OF
MALOCCLUSION
TIMING OF CLASS III MALOCCLUSION
TREATMENT OF TYPE A CLASS III
TREATMENT OF TYPE B CLASS III
TREATMENT OF TYPE A AND B CLASS III
BIOMECHANICS AND GENERAL ASPECTS OF
PERMANENT DENTITION TREATMENT
RETENTION OF CLASS III

What is a Class III ?What is a Class III ?
The true genetic Class III growth pattern is the opposite of
the most common orthodontic problem which is retrusion
of the lower jaw. In the Class III the lower jaw is
protrusive and it may be mistakenly referred to as an
"under bite". In reality, the lower jaw is too long relative to
the rest of the face, and the chin appears to protrude too far
in front of the rest of the face. The true Class III is a
genetically directed problem which may express itself at
an early age, but usually becomes more apparent as the
child approaches the teenage growth spurt. Generally, we
will find a parent or grandparent with the exact same
problem on one side of the family.

The true Class III is not an all or none problem.
There are varying degrees in the amount of
abnormal growth which can occur in the lower jaw.
Once the lower teeth move out in front of the upper
incisors, the muscles influence their position and
the size of the chin comes into play to determine
how "bad" the condition looks.

According to ANGLE class III malocclusion
is defined as class III molar relation with
the mesio – buccal cusp of the maxillary
first permanent molar occluding in the inter
dental space between the mandibular first
and second molars. Or lower permanent
molar is ahead of the upper first molar by a
distance of the width of a premolar or half
the width of a molar.

ETIOLOGYETIOLOGY
Although it is difficult to know the precise
cause of most malocclusions, we do know in general
what the possibilities are, and these must be considered
during treatment.
1.TERATOGENS:
Cleft lip and palate result in maxillary deficiency in
most occasions a class III malocclusion is established.
Teratogens causing cleft lip and palate are aspirin,
cigarette smoke (hypoxia), Dilantin, 6-Mercaptopurine,
valium etc Vitamin D excess causes premature
closure of sutures and might lead to class III
malocclusion.

2. ACROMEGALY AND HEMI MANDIBULAR
HYPERTROPHY:
Acromegaly is caused by anterior pituitary
tumour that secretes excessive amount of growth harmone.
Here excessive mandibular growth occurs creating a
skeletal class III malocclusion. Often the mandibular
growth accelerates to levels seen in the adult growth
spurt, years after the adolescent growth spurt is completed.
The reason for hemimandibular hypertrophy is unknown.
Formerly called condylar hypoplasia it is know called a
hemi mandibular hypertrophy as a body of mandible is
affected. This condition leads to a class III with
asymmetry

3. GENETIC INFLUENCES:
Best known examples of genetic influences are the
classic HAPSBURG JAW and the prognathic
mandible of Austrian royal family. The influence
of inherited tendencies is strong for mandibular
prognathism in particular (most inherited condition
followed by long face pattern which is second.
Litton et al (ajo 1970) concluded that one
third of a group of children who presented with a
severe class III malocclusion had a parent with the
same problem and one sixth had an affected
sibling.

4.ENVIRONMENTAL INFLUENCES:
Large tongue as in the case of thyroid deficiency
can contribute to a mandibular prognathism by
causing the mandible to be positioned forward all
times.
Rakosi and Schilli suggested mouth
breathing in the etiology of class III
malocclusions. They hypothesized that excessive
mandibular growth could arise as a result of
abnormal mandibular posture because constant
distraction of the mandibular condyle from the
fossa may be a growth stimulus.

5.The posterior ‘squeezing out’ effect of molar crowding
There has been discussion of posterior crowding as a
factor in the development of Class III malocclusions.
The theory suggests that a squeezing out effect can
occur because of crowding in the molar regions, which
can contribute to an anterior open-bite malocclusion in
a mandible with poor vertical growth in the ramus area .
Alternatively, good ramus growth can lead to a Class
III malocclusion. This concept is not well understood,
and has not been fully investigated

The incidence of skeletal Class III malocclusion in the
white population is approximately 5%. The mid face
deficiency is high in Asian population which increases
the frequency of malocclusion. The incidence of this
malocclusion ranges between 4%and 13% among the
Japanese and 4% and 12% among the Chinese. A lesser
incidence of class III malocclusion is seen among
African- Americans. The incidence has been reported to
be significantly higher in the Scandinavian and Japanese
populations.
INCIDENCE OF CLASS IIIINCIDENCE OF CLASS III
MALOCCLUSION:MALOCCLUSION:

Early signs of true progressive mandibular prognathism
occasionally can occur in infancy. In the first months of
life a sequential development of the class III condition
may be observed as:
 Eruption of the maxillary central incisors in a lingual
relationship and the mandibular incisors in a forward
position with no overjet.
 Development of an incisal crossbite during the eruption
of the lateral incisors into a normal relationship.
INITIAL SYMPTOMS OF CLASS IIIINITIAL SYMPTOMS OF CLASS III
MALOCCLUSIONMALOCCLUSION

 Full incisor cross bites some weeks later.
 Flattening of the tongue as it drops away from the
palatal contact and postures forward, pressing against
the lower incisors
 Habitual protraction of the mandible by the child into
the protruded functional and morphologic relationship

The configuration and form of the forehead and nose in
relation to the lower face are significant for esthetic
evaluation and prognosis. A well formed Naso labial angle
is important for esthetic improvement. If the angle is acute,
the premaxilla segment can be retracted if the angle is
obtuse; the segment must be protracted to improve facial
esthetics. The soft tissue of the chin can compensate for or
accentuate a skeletal class III relationship depending on its
thickness. Gingival retraction or dehiscence can often be
seen in early class III malocclusion. This damage is
irreversible and is an indication for early treatment
CLINICAL EXAMINATIONCLINICAL EXAMINATION

The next step is examination of the dentition,
including the morphology and number of teeth.
Congenital absence in the maxilla (e.g., missing
canine or first premolar teeth) makes treatment more
difficult.
When evaluating tile axial inclination of the
teeth, certain disadvantageous irregularities such as
labial tipping of the upper incisors and lingual tipping
of the lower incisors still in anterior cross bite should
be noted. A concavity of the lingual alveolar structure
in the mandible also is a clue to future difficulties in
the correction of Class III malocclusion.

Crowding of maxillary teeth also enhances
treatment problems; treatment may require
extraction of the counterpart teeth in the lower arch,
leading to great difficulty in closing spaces and
maintaining proper incisor axial inclination. To
make treatment easier if extractions are required,
the clinician should perform extractions in the
mandible before proceeding to those in the maxilla.
Depending on the state of development,
enucleation or germectomy may be feasible for the
lower first premolars. The molar occlusal
relationship is usually Class III, but the plane of
occlusion also should be evaluated because its
correction may be necessary before surgery

FUNCTIONAL ANALYSIS:FUNCTIONAL ANALYSIS:
The path of closure is from the postural rest position to
occlusion must be carefully studied. The mandible may
slide anteriorly into a forced protrusion because of
premature contact and tooth guidance when the jaw closes
into full occlusion. Such anterior displacements have more
favorable prognosis. In contrast, patients with problems
caused by an anterior rest position with respect to habitual
occlusion are difficult to treat and usually require
orthognathic surgery.

In addition to this pseudo-forced bite category
also exists. This is a skeletal class III with a
dental compensation arising from labial tipping
of the upper incisors on a deficient maxillary base
and lingual tipping of the lower incisors on an
excessively long mandible. Orthodontic pre
surgical treatment must decompensate these
malpositions before surgical procedures can be
performed.

TEMPOROMANDIBULAR JOINT AND TONGUETEMPOROMANDIBULAR JOINT AND TONGUE
ASSESMENTASSESMENT
 If the condyle occupies the most posterior position in
the temporal fossa the likelihood of its riding over the
posterior periphery of the articular disk is increased
with concomitant clicking and lateral crepitus,.
 Abnormal tongue function, size and posture must be
considered. The tongue may be postured low in the
mouth and be flat and elongated, especially in cases
of mouth breathing. In cases of Macroglossia the
tongue is not contained within the dentition and the
scalloping effect of the tooth contact may be visible
on the periphery.

LIP FUNCTION AND MORPHOLOGICALLIP FUNCTION AND MORPHOLOGICAL
ASSESMENTASSESMENT
 A short hypotonic retrusive upper lip is often seen in
combination with a heavy, redundant, everted lower lip.
 A closed lip position will produce the appearance of a
long lower lip, as the lip elongates to close over the
class III incisor relationship. The closed lip length is
misleading and should not be used for treatment
planning. Relaxed lip appearance is deceiving due to
hypotonicity of lower lip --- this causes elevation and
apparent lengthening.
 The lower lip length should be verified with the lower
incisor tip to soft tissue menton which is not influenced
by posture

Maxillary retrusion is associated with
upper lip retrusion and a straight maxillary
sulcus curve. Upper lip retrusion is treated
with labial crown torque.

DIAGNOSTIC CHARACTERISTICS OF ANDIAGNOSTIC CHARACTERISTICS OF AN
UNFAVOURABLE CLASS III GROWTHUNFAVOURABLE CLASS III GROWTH
1. An increased gonial angle
2. Antegonial notching
3. Backward direction of condylar growth
4. Thin mandibular symphysis
5. Compensation in position of upper and lower
incisors in response to disproportionate jaw growth.
6. Mandibular incisors are retroclined as child
becomes older there roots tend to press against the
labial plate producing a WASH BOARD EFFECT.
Maxillary incisors are usually flared anteriorly.

CEPHALOMETRIC ASSESMENTCEPHALOMETRIC ASSESMENT
OF CLASS III:OF CLASS III:
Several studies have expanded on these findings in an attempt to
compare Class III malocclusion with Class I controls relative to
the morphology of the maxilla, the mandible, and the cranial base.
These differences include the following:
1. The SNA angle is significantly lower in the Class III
samples, indicating a greater degree of maxillary
retrusion.
2. Mandibular protrusion is greater in the Class III samples.
3. The mean ANB angle in the Class III samples is negative.

4. The gonial angle is more obtuse in the Class III
samples.
5. The mandibular plane angle is steeper than normal
in the Class III samples.
6. Lower anterior face height is significantly greater
in the Class III samples.
7. The sella angle and articular angle were smaller in
class III samples.
8. Anterior position of the mandible is seen.

CEPHALOMETRIC CLASSIFICATIONCEPHALOMETRIC CLASSIFICATION
CLASS III MALOCCLUSION CAUSED BY A
DENTO ALVEOLAR MALRELATIONSHIP
No basal sagittal discrepancy is apparent
The sub spinale -nasion-supra mentale (ANB
angle) is within normal limits.
Maxillary incisors tipped lingually and
mandibular incisors tipped labially

CLASS III MALOCCLUSION WITH A STRONG
MANDIBULAR BASE
1. Mandibular base and ascending ramus are large
2. SNA angle is normal
3. SNB angle is larger than normal.
4. ANB angle is negative
5. Gonial angle is usually large
6. Articular angle is usually small.
7. Anteriorly positioned mandible
8. The tongue is postured forward and lies low in the mouth
9. The upper incisors are tipped labially
10. The lower incisors are inclined lingually
11. Lateral cross bites are often evident
12. Maxillary arch appears to be narrowed.

CLASS III MALOCCLUSION WITH AN
UNDER DEVELOPED MAXILLA
1. Maxillary base is small and retrognathic
2. Smaller SNA angle
3. Normal SNB angle
4. Mid face deficiency and some cases of
associated cleft palates are seen

CLASS III MALOCCLUSION WITH A COMBINED
UNDERDEVELOPED MAXILLA AND A PROMINENT
MANDIBLE
 SNA angle is small and maxillary base is short
 SNB angle is large and the mandibular base is large
In a patient with short ramus:
1. Growth pattern is vertical and the gonial angle is large.
2. Often open bite is seen
3. Crowding in the upper arch
In a patient with long ramus:
1. Growth pattern is horizontal and gonial angle is small
2. Reversed over bite is apparent

CLASS III MALOCCLUSION WITH A
PSEUDO FORCED BITE OR ANTERIOR
DISPLACEMENT
The condition known as class III skeletal dysplasia
is partially compensated by the labial tipping of the
upper incisors and the lingual inclination of the
lower incisors
This tooth mal position results in additional
anterior guidance of the mandible on the path from
postural rest to the habitual occlusion as the lingual
aspect of the lower incisors rides on the maxillary
incisor margins after initial contact

PSEUDO CLASS IIIPSEUDO CLASS III
 Moyer’s suggested pseudo–Class III malocclusion as a
positional mal relationship with an acquired neuro-muscular
reflex. Pseudo–Class III malocclusion has been identified with
anterior crossbite as a result of mandibular displacement.
 Premature contact between the maxillary and mandibular
incisors results in forward displacement of the mandible in
pseudo Class III malocclusion so as to disengage the incisors
and permit further closure into the position in which the
posterior teeth occluded. Several reports attributed the incisor
interference to the retroclined upper incisors and proclined
lower incisors in pseudo–Class III malocclusion.
 Based on clinical assessment, Turley and Lin reported that
pseudo Class III malocclusion showed some degree of
hereditary tendency

Pseudo class IIIPseudo class III
Habitual occlusion Centric relation

Clinical Examination (RABIE 2000 AJO)
Clinical examination of pseudo–Class III malocclusion
revealed that 75% of the examined cases showed a mesial
step, which corresponds to Angle’s Class I at HO and
showed a normal relationship of the primary molar that is a
flush terminal plane at CR. Diagnostic characteristics of
pseudo–Class III malocclusion could be summarized as:
1. Majority showed no family history.
2. Class I molar and canine relationships at HO and Class II or
end to end relationship at CR.
3. Decreased midface length.
4. Forward position of the mandible with normal mandibular
length.
5. Retroclined upper incisors and normal lower incisors.
6. Retrusive upper lip.

The timing of Class IIIThe timing of Class III
treatmenttreatment
Early correction of mandibular Displacements
These should be identified at dental age 8 or 9, soon after the
permanent incisors erupt. This incisor relationship has the potential to
restrict maxillary development and encourage mandibular growth,
thereby worsening the Class III problem. This is similar to the effect
of a functional appliance in Class II treatment.
Normally, such displacements can be corrected by simple tooth
movements, and it is important for treatment to be provided at an
early age. Subsequently, unrestricted maxillary development can
resume, and if the condyles are centered in the fossae, this will
eliminate the potential ‘functional appliance’ effect of the original
mandibular displacement.

Maxillary retrognathism
Growing patients who present with maxillary
retrognathism should be considered for early expansion
and development of the maxilla. This may involve the
use of rapid maxillary expansion and a reverse headgear.
Subsequently, a palatal bar can be used to stabilize the
skeletal change, and then full fixed appliance treatment
can be commenced at approximately 12 years of age.
Borderline surgical cases
In some cases with mandibular excess, the diagnosis will
suggest that mandibular surgery may be needed. It is
helpful to delay orthodontic treatment for such cases, if
possible. This will allow assessment of growth patterns,
using regular cephalometric radiographs, so that a more
informed surgical/non-surgical decision can be reached.

Class III surgical cases
Some cases are clearly Class III surgical cases
from the outset, and should not be treated until
all growth has ceased. Timing will be beyond
the age of 20 years in males and a little earlier
in females.

The surgical/non-surgical decision in Class
III treatment
As with Class III treatment, it is important to
recognize those Class III cases which have a
major skeletal disproportion, either at the time
of assessment, or where there is a probability
of unfavorable growth. For such individuals, it
will be necessary to consider a
surgical/orthodontic solution. Treatment on
the basis of orthodontics alone should be
delayed, or discarded as a :

Situation A – A Surgical/ orthodontic correction to an ideal
result: Determined that mandibular surgery will be required,
then the surgeon will normally wait until all growth has
finished, which may be as late as 22 years of age in males. The
surgeon will then require the orthodontist to decompensate the
incisors. Correction will be achieved by A/P realignment of the
mandible and/or maxilla, with transverse correction of the
maxilla if necessary. This should lead to an optimal facial and
dental result.
A 6-mm mandibular set-back will
result in measurements to true
vertical line (TVL) which are within
1 SD of the ideal.

Situation B – orthodontic masking of a mild Class III
skeletal case.
As an alternative to ‘A’ above, if the underlying skeletal
discrepancy is mild, it may be decided to follow a treatment
plan based on orthodontics alone. This will allow correction
to be commenced much earlier, and the patient will be
informed of the possibility of late mandibular growth. The
orthodontist will then solve the problem by ‘masking’ the
underlying Class III discrepancy by dental compensation.
In this theoretical representation, the
upper incisors were proclined 2° and
the lowers were retroclined 8°.

This will involve proclination of upper incisors
and retroclination of lower incisors. Good patient
cooperation with Class III elastics and/or a face
mask will normally be needed in this type of
treatment. This should lead to an acceptable
dental and facial outcome without the need for
orthognathic surgery.

Situation C – late mandibular growth:
After orthodontic masking of a mild Class III malocclusion, late
mandibular growth can occur, especially in males. This is a
difficult situation to manage. Sometimes the patient will find the
late change in dental and facial outcome acceptable, and seek no
further treatment. However, if mandibular surgery is deemed
necessary, there is limited scope for facial improvement from the
surgery, because of the dentally compensated teeth.
In some cases, late mandibular growth
occurs after the type of treatment
shown in ‘B’ above. This is difficult
to manage.

The incisors will need to be decompensated by
orthodontics before surgery, if there is to be an
optimal facial benefit from the surgery. The
treatment of Class III malocclusions is relatively
easy when the problem is confined to the alveolar
bone, but when the deformity is in the basal bone
such as in a deficient maxilla or overgrowth of
the mandible, and then the malocclusion does not
respond readily to treatment and tends to recur
after treatment.

EARLY TREATMENT OF CLASS IIIEARLY TREATMENT OF CLASS III
MALOCCLUSION:MALOCCLUSION:
The “Doctrine of limitations” was in full swing in the 40”s
and 50”s.Early treatment was condemned except for serial
extractions.
The view that prevailed then was that skeletal alteration
was impossible and that the dominance of genetic
morphologic pattern was so great that it included unaltered
muscle patterns.
Further any treatment on the deciduous dentition was held
to be so temporary that it had no effect on the permanent
dentition. But evidence based researches have led to many
favorable conclusions for early treatment. Class III
malocclusion, in particular gets the nod from many authors
in favor of early treatment .Starting with Tweed, treatment
timings can be as early as 4 years of age.

Rickets (AJO 2000) has summarized the main
objectives of early treatment lying in five
concepts
1. Obtaining a skeletal change (structural)
2. Providing the opportunity of a functional change
in the environment
3. Utilization of the individual growth towards the
correction.
4. Elimination of the detrimental habits (breathing
etc)
5. Taking advantage of the forces of the occlusal
development towards the correction.

Turpin has developed a list of positive and negative
factors to aid in deciding when to interrupt a
developing class III malocclusion
POSITIVE FACTORS:
1. Good facial esthetics
2. Mild skeletal disharmony
3. No familial prognathism
4. Antero posterior functional shift
5. Convergent facial type
6. Symmetric condylar growth
7. Growing patients with expected good cooperation.
8. If the above factors are not present in the patient , they
are listed as negative and treatment can be delayed until
growth is completed.

Joondeph, after Turpin’s thesis, also pointed out
the goals of early intervention:
1. Reduce the skeletal discrepancy and provide a
more favorable environment for normal growth.
2. Achieve as much relative maxillary advancement
as possible.
3. Improve occlusal relationships.
4. Improve facial esthetics for more psychosocial
development.
5. Reduce or simplify, phase II or surgical treatment.

PERMANENT DENTITION THERAPY:PERMANENT DENTITION THERAPY:
Another treatment consideration is that extraction
therapy may have limited applicability in Class
III treatment. For example, we would not want to
limit extractions to the lower arch because many
times the incisors are generally inclined lingually
and extraction treatment tends to increase this
inclination, possibly beyond the limits of the
lingual plate of bone. Also, extractions may be
contraindicated when orthodontic treatment must
be combined with surgical treatment.

Another consideration is that many of the forces in conventional
orthodontics carry risks because of the unfavorable growth pattern in
patients with Class III malocclusions. For example, many patients
with Class III malocclusions have an increased vertical face height,
particularly of the lower anterior part of the face, with an open-bite.
In these patients, Class III elastics and second-order bends in the
posterior regions cannot be used conveniently because the extrusive
force components on posterior teeth can open the bite and increase
the vertical dimension further. Particular attention must be paid to
the use of Class III elastics because they can also extrude the
mandibular incisors, and there is frequently excessive vertical
dentoalveolar development in the incisor region.
Since many of the conventional treatment procedures have
limitations, we should consider the use of extra oral traction because
appropriate force systems can be placed with fewer deleterious side
effects.

There are three important diagnostic principles
which merit attention.
First, it is particularly important to determine
whether the mandible, on closure, is in centric
relation or in a "convenient" anterior position.
The practical implication is that a Class I problem
can appear to be a Class III malocclusion
(pseudo-Class III malocclusion) when the
mandible is forced anteriorly . Even a true Class
III malocclusion can appear much more serious if
there is an anterior path of closure of the
mandible

Type Anterior
position of
mandible
Centric relation and centric
occlusion Significance
Pseudo-Class
III
Present Not
coincident
Problem is less
difficult than it
appears ( in a
Class I) actually.
True Class III Present Not
coincident
Not coincident
Problem is less
difficult than it
appears
True Class III Absent Coincident Problem is as
difficult as it
appears

The second principle is that the nature of
the skeletal discrepancy must be defined
because treatment, to a large extent, is
based on this differential diagnosis.
Class III malocclusions can be classified
as
An under developed maxilla---TYPE A
An over developed mandible--TYPE B
A combination of TYPE A and TYPE B

Third, a malocclusion reflects the interplay of many
conditions that may be impossible to evaluate singularly.
One important variable is the potential growth and
development of a patient with a Class III malocclusion.
In this context, at least two factors may be detrimental
and aggravate Class III malocclusions with time. One is
the differential growth of the jaws, carrying the mandible
more anteriorly relative to the maxilla. Also, local
conditions (such as low tongue posture) may adversely
influence the growth pattern. Since the amount and the
timing of growth of the mandible cannot be assessed
accurately, we cannot consider a Class III malocclusion
fully resolved until facial growth has ended.

TREATMENT FOR TYPE A CLASS IIITREATMENT FOR TYPE A CLASS III
Characteristic of this type in which the maxilla appears
retrognathic is a concave profile which represents
underdevelopment of the middle part of the face, rather
than prominence of the mandible. Treatment should be
started early, as early as 4 years of age, for two
fundamental reasons. One is that extraoral traction which
pulls the maxilla anteriorly functions in the same
direction as the direction of development. Second, unlike
posterior movement of the mandibular arch, anterior
movement of the maxillary arch appears to have a greater
chance of remaining stable. With this kind of treatment,
we can expect to achieve:

 An orthopedic protraction of the maxilla with a
strong force (500 to 1,000 Gm per side). This change
appears to be limited especially if treatment is started
after 6 years of age,
 An increase in the inclination of the maxillary
incisors to obtain a sufficient overjet, associated
more or less with
 Bodily movement of all the teeth in an anterior
direction, advancing point A,
 Both an improvement in function and a more esthetic
profile.

The use of protraction headgear in the treatment of Class
III malocclusion was described more than 100 years ago,
with other descriptions appearing early in this century.
Early orthopedic intervention provides a non surgical
alternative in the treatment of Class III malocclusion
with maxillary retrusion. Protraction headgear provides
directed, forward growth of the maxilla at an early age.
An extra oral force of 300 gm or more per side, when
applied, can cause significant changes in the circum
maxillary sutures and in the maxillary tuberosity.
Tension produced within the sutures was believed to
cause an increase in vascularity and a concomitant
differentiation of the cellular tissues resulting in
increased osteoblastic activity.
FACE MASK:FACE MASK:

In an animal study with tantalum implants and oxytetracycline
dyes, heavy intermittent maxillary protraction was found to
produce forward displacement of the mid face, anterior relocation
of the inferior border of the orbit, and gross osseous alterations
extending superiorly to the area of the fronto maxillary suture. The
study also found that post treatment skeletal rebound was minimal
and was observed only during the first month after discontinuation
of mechanical forces.
Clinically, the maxilla can be advanced 2 to 4 mm
over a 12 to 15-month period of headgear treatment. The use of
protraction headgear has been shown to be most effective in the
full deciduous or early transitional dentition, with less skeletal
changes after 9 years of age. A recent longitudinal study
suggested that orthopedic effects of protraction headgear on
dentofacial structure was possible in young girls as late as during
the acceleration phase of pubertal growth spurt.

DESIGN:
The orthopedic facial mask consists of three basic components.
The facial mask, a bonded maxillary splint and elastics. The
facial mask is an extra oral device composed of a fore head
pad and a chin pad that are connected with a heavy steel
support rod. To this support rod is connected a cross bow to
which are attached rubber bands to produce a forward and
downward elastic traction of the maxilla. The position of the
pads and the cross bow can be adjusted simply by loosening
and tightening set screws within each part of the appliance.
The major modification in the appliance is the
addition of facial mask hooks in the upper first deciduous
molar. In patients in whom treatment is started before the
eruption of the upper first molars, the appliance is designed to
incorporate the first and second deciduous molars as well s
deciduous canines.

PARTS OF PETIT FACE MASKPARTS OF PETIT FACE MASK

Petit face mask lateral and frontal viewPetit face mask lateral and frontal view

Delaire type face maskDelaire type face mask

The splint is activated once per day until the desired
increase in transverse width has been achieved. In
patient in whom no increase in transverse dimension is
desired, the appliance still activated for 8-10 days to
disrupt the maxillary sutural system and to promote
maxillary protraction (HASS 1965)
After the patient has been accustomed to
wearing the maxillary splint, the facial mask treatment is
initiated. The current version of the petit facial mask is
one universal size and can be adjusted to fit the facial
contours of most patients.

SEQUENCE OF ELASTICS:
 At the time of delivery 3/8” 8 oz 2
weeks
 After 2 weeks 1/2” 14 oz
 Increased to a max of 5/16” 14 oz
Young patients (4-9) years should wear the mask
on a full time basis except during meals. Duration
is 4-6 months. They can be retained with only
night time wear or with a maintenance plate, chin
cup or FR III. In older patients, it is worn at all
times except during school.

SKELETAL EFFECTS OF MAXILLARY
PROTRACTION ( sutures involved):
The maxilla articulates with nine other bones of
the craniofacial complex: frontal, nasal, lacrimal,
ethmoid, palatine, vomer, zygoma, inferior nasal
concha, opposite maxilla, and occasionally
sphenoid. Palatal expansion had been shown to
produce a forward and downward movement of
the maxilla by affecting the intermaxillary and
circummaxillary sutures. The disruption of these
sutures may help initiating cellular response in
the sutures, allowing a more positive reaction to
protraction forces.

Sutures involved in face maskSutures involved in face mask

Kambara found changes at the circummaxillary
sutures and at the maxillary tuberosity attributable
to posteroanterior traction, including the opening
of sutures, stretching of sutural connective-tissue
fibers, new bone deposition along the stretched
fibers, and apparent tissue homeostasis that
maintained the sutural width. Nanda and Hickory
showed how the histologic modifications in the
zygomatico maxillary suture after maxillary
protraction varied according to the orientation of
the force system applied.

Biomechanical studies on dry human skulls have
demonstrated further that the application of an
anteriorly directed force results in forward
movement of the maxilla.
These investigations also showed that the direction
of the force is critical in controlling rotation of the
upper jaw. A force generated parallel to the
maxilla or above the palatal plane produces
counterclockwise rotation of the palatal plane.

BIOMECHANICS:
The centre of resistance of the maxilla is located at the
distal contacts of the maxillary first molars, one half the
distance from the functional occlusal plane to the
inferior border of the orbit.( Lee AJO 1997) Protraction
of maxilla below the Centre of resistance produces
counter clock wise rotation of the maxilla. Also Hata et
al (AJO 1987) found using human skulls that protraction
forces at the level of the maxillary arch produces
forward but counter clock wise rotation unless a heavy
downward vector of force was applied.

A heavy force at 300 -450 gms downward to the
occlusal plane is accepted.10 degree of counter
clock wise rotation being acceptable .Force levels
of 300-500 gms on either side in both primary
and mixed dentition is recommended by most
authors.
Direction of force being downward, the point of
application is 5 mm above the palatal plane in the
canine region. Hata et al suggested that an
effective forward displacement of the maxilla can
be obtained with this point of application

EFFECTS OF THE FACE MASK:
1. The maxillary incisors moved in the anterior direction,
whereas the mandibular incisors moved posteriorly.
2. After maxillary protraction, the maxilla was displaced
anteriorly, whereas the mandible rotated posteriorly.
3. The mandibular plane angle and anterior lower and
total face heights increased.
4. There is no change in SN-palatal plane angle during
growth period.
5. These changes were reflected in the profile, whereby
the skeletal profile convexity increased and soft tissue
facial angle and facial convexity increased; and the
Class III concave profile became more balanced, with
the upper lip area becoming more marked.

6. Position of the posterior nasal spine remained stable
7. Over bite was improved by eruption of maxillary and
mandibular molars.
8. Anchorage loss was observed during maxillary
protraction with mesial movement of the maxillary
molars. An average of 5.68 mm anterior movement of
the upper incisors resulted in a significant amount of
upper lip protraction.
9. The ratio of upper lip protraction to upper incisor
protraction relative to the vertical reference line was
1:1.26.
10. A significant decrease in upper lip thickness to
vermilion was caused by the fact that during the
treatment period, total anterior movement of the upper
incisors was approximately 1 mm more than that of the
upper lip.

11. A significant decrease in the upper lip sulcus depth can be
evaluated as another favorable effect of the appliance on the soft
tissue profile.
12. The lower lip moved posteriorly to lie behind the Steiner S line,
13. After the correction of the crossbite in Class III cases, the lower
lip most often contacts both lower and upper incisors and would
therefore be influenced not only by the retraction of the lower
incisors but by protraction of the upper incisors as well.
14. Backward repositioning of the pogonion soft, and slight
inhibition of anterior migration of the lower lip was seen.
15. upward and forward rotation of the maxilla occurs when
protraction force on molars is applied parallel to the occlusal
plane. This type of maxillary rotation can be minimized when
the force is applied in the canine area, 20° to 30° below the
occlusal plane.

Movement of A point in different studiesMovement of A point in different studies

Sagittal Changes After MaxillarySagittal Changes After Maxillary
ProtractionProtraction
1. Maxillary advancement,
2. Mandibular rotation,
3. Labial tipping of the maxillary incisors,
4. Lingual tipping of the mandibular incisors,
5. Mesial movement of the maxillary molars,
6. Changes in ANB differences towards a more
positive value

One other aspect of Class III malocclusions is
that a retrognathic maxilla is often associated
with a narrow maxillary arch which is in bilateral
cross-bite. Expansion of the maxillary arch can
be done at the same time as protraction of the
maxilla (which brings it into a narrower portion
of the mandible), or it can be done later. For this
purpose, a rapid maxillary expansion appliance
is used.

Rapid maxillary expansion is the corner stone of
increasing the transverse dimension in growing
individual.
In general there are three types of expansions are
there to increase the transverse dimension
1.ORTHODONTIC EXPANSION
2.PASSIVE EXPANSION
3.ORTHOPEDIC EXPANSION

RAPID MAXILLARY EXPANSIONRAPID MAXILLARY EXPANSION
RME is an indication of an orthopedic expansion
Indications for RME.
 Patients who have lateral discrepancies that result in either unilateral
or bilateral posterior crossbites involving several teeth are
candidates for RME. The constriction may be skeletal (narrow
maxillary base or wide mandible), dental, or a combination of both
skeletal and dental constriction.
 Anteroposterior discrepancies. For example, patients with skeletal
Class II, Division 1 malocclusions with or without a posterior
crossbite, patients with Class III malocclusions, and patients with
borderline skeletal and pseudo Class III problems are candidates if
they have maxillary constriction or posterior crossbite.
 Cleft lip and palate patients with collapsed maxillae .
 Procedure to gain arch length in patients who have moderate
maxillary crowding.

Contraindications for RME.
Patients who cannot cooperate with the clinician
are not candidates for RME.
Patients who have a single tooth in crossbite
probably do not need RME.
Patients who have anterior open bites, steep
mandibular planes, and convex profiles are
generally not well suited to RME.
Patients who have skeletal asymmetry of the
maxilla or mandible,
Adults with severe anteroposterior and vertical
skeletal discrepancies are not good candidates for
RME

The following factors need to be considered during
treatment planning to determine whether to expand the
dental arches conventionally or with RME:
 The magnitude of the discrepancy between the maxillary
and mandibular first molar and premolar widths; if the
discrepancy is 4 mm or more, one should consider RME,
 The severity of the crossbite, that is, the number of teeth
involved, and
 The initial angulations of the molars and premolars—
when the maxillary molars are buccally inclined,
conventional expansion will tip them further into the
buccal musculature; and if the mandibular molars are
lingually inclined, the buccal movement to upright them
will increase the need to widen the upper arch.

 The increase in mandibular plane angle with treatment
may be due to incomplete compensation of the short-
term downward displacement of maxilla by the vertical
growth of the ramus. One year after protraction, the
mandibular plane angle decreased, and this value was
significantly smaller than that of the untreated group of
age 12 . The increase in the mandibular plane angle with
treatment may be due to
 The relapse of the treatment that induces vertical
increase of anterior facial height and clockwise rotation
of the mandible, and
 Chin cup effects after protraction.

Treatment effects of RMETreatment effects of RME
 Correction of cross bite
 Increase in arch perimeter (approx .7 times the
change in premolar width)
 Correct cuspal inclinations
 Improves airway function
 Encourage more rapid tooth movement in mixed
dentition patients
 Broaden the smile
 Produces spontaneous correction of class II and class
III malocclusions.

Changes following palatal expansionChanges following palatal expansion

GINGIVAL CONSIDERATIONSGINGIVAL CONSIDERATIONS
Implant studies in expansion confirmed 50% dental
movement and 50% skeletal movement in children
and in adolescents only 35% movement was skeletal
and 65% was dental. As the patient grows older
tipping becomes greater which puts the teeth at higher
risk of gingival recession (Lindhe 1989). He stated
that “during orthodontic treatment tooth is moved
through the envelope of alveolar process at sites with
thin and inflamed gingiva and there is a risk that
gingival recession may occur.

The labial plate of bone in maxilla is extremely
thin on the facial surface of the teeth. The
extensive bodily movement of the incisors in a
labial direction through the alveolar bone resulted
in a small apical displacement of gingival margin
which appeared to thin by tooth movement and
reduction of alveolar bone height but no loss of
connective tissue attachment was apparent when
there were no signs of inflammation . Gingival
graft can be used to prevent this gingival
recession

MODIFIED PROTRACTION HEAD GEARMODIFIED PROTRACTION HEAD GEAR
A modified protraction headgear design and the
biomechanical considerations of its clinical use are
presented by Nanda (1980 AJO). The clinical results
show that a modified protraction headgear with a chin
cup helps in the correction of moderately severe Class III
malocclusions by the anterior displacement of the
maxilla and maxillary dentition, and possibly restricting
or changing the direction of the growth of the mandible.
This headgear can also be used to correct axial
inclinations and or mesial displacement of posterior teeth

LONG TERM EFFECTS OFLONG TERM EFFECTS OF
RPE/FACEMASK:RPE/FACEMASK:
Mc NAMARA AND SARVER ET AL (AJO 2003)
In the cephalometric investigation, authors compared the
long-term effects of an initial phase of rapid maxillary
expansion and facemask (RME/FM) therapy followed by
comprehensive edgewise therapy with the effects of
growth in untreated, matched controls. During the post
treatment period, the treated and untreated Class III
subjects generally grew similarly, although the skeletal
relationship of the maxilla to the mandible remained
unchanged in the RME/FM group, whereas the controls
had an increased skeletal discrepancy of 3.0 mm. Over
the long term, there was a slightly greater increase in
midfacial length (1.6 mm) in the treatment group than in
the controls.

Similarly, the distance from Point A to nasion
perpendicular decreased by 1.2 mm in the treated
group. The overall increase in mandibular length was
2.4 mm less in the RME/FM group than in the
controls, and mandibular projection relative to nasion
perpendicular was 3.0 mm less in the treated group.
The change in the Wits appraisal was substantial
between groups (6.1 mm), with an improvement in
the inter maxillary relationship in the treated group
(3.4 mm. No clinically significant differences were
observed between the groups in the vertical
dimension.

Overjet increased significantly in the treated group
relative to the controls (4.4 mm), whereas the molar
relationship decreased significantly (–3.9 mm During
the post treatment period that includes the pubertal
growth spurt, craniofacial growth in RME/FM
patients is similar to that of untreated Class III
controls. Aggressive over-correction of the Class III
skeletal malocclusion, even toward a Class II occlusal
relationship, appears to be advisable, with the
establishment of positive overbite and overjet
relationships essential to the long-term stability of the
treatment outcome.

THE FUNCTIONAL REGULATOR (FR-3)THE FUNCTIONAL REGULATOR (FR-3)
OF FRANKELOF FRANKEL
It is an example of passive expansion
INDICATION:
This appliance has been used during the
deciduous, mixed, and early permanent
dentition stages to correct Class III
malocclusion characterized by maxillary
skeletal retrusion, and not mandibular
prognathism.

According to Frankel, the vestibular shields and upper
labial pads function to counteract the forces of the
surrounding muscles that restrict forward maxillary
skeletal development and retrude maxillary tooth position.
Frankel has also stated that the vestibular shields stand
away from the alveolar process of the maxilla but fit
closely in the mandible, thus stimulating maxillary
alveolar development and restricting mandibular alveolar
development. Frankel reported a study of 74 severe Class
III cases treated with the FR-3, comparing these cases to
58 Class II cases treated with the FR-1 appliance. He noted
greater forward movement of maxillary landmarks in the
Class III cases than in the Class II cases. He also stated
that the changes in maxillary position in the Class II cases
were minimal in comparison to what would normally
occur during growth. He concluded. from this study that
the forward development of the maxilla is stimulated by
the FR-3 appliance.

Another use of the FR-3 has been suggested by Petit
in the treatment of severe Class III cases. Petit
advocates the use of heavy orthopedic forces
generated by the facial mask to achieve the initial
correction of the malocclusion. Further, he suggests
that an FR-3 may be used to retrain the maxillary
anteroposterior correction and to retrain the
associated musculature.
Eirew has stated that the FR-3 is an excellent
retraining device and aid to muscular reeducation
following surgical correction of mesiocclusion.

Construction bite
A horseshoe wafer of medium hard wax is used to orient
the upper and lower dental arches in all three planes of
space (horizontal, transverse, and vertical). Any arbitrary
adjustments in work-model orientation during appliance
fabrication can lead to an appliance that does not fit
properly.
The bite registration is taken with the patient's mandible in
the most comfortably retruded position. It is necessary to
allow 1 to 2 mm of inter occlusal space in the molar region
for the construction of the lower and, when necessary,
upper occlusal rests. A wide open-bite registration should
be avoided. In cases with an anterior open bite, only 1 mm
of vertical bite-opening in the posterior region is
necessary.

Use of removable appliancesUse of removable appliances
A second method involves the use of
removable appliances which are placed in the
deciduous dentition stage of development or in
the mixed-dentition stage when certain teeth
have exfoliated or are carious. If retention of
the removable appliance is adequate, we can
apply up to 500 Gm. per side.

The orthodontic effect, moving the maxillary teeth
forward, can be achieved at any time. However, there
appear to be ''more optimum'' situations for this procedure.
One is when there is insufficient room for the canines. In
this instance, maxillary incisors can be moved forward to
make space. If orthopedic protraction of the maxilla is also
indicated, it is generally done immediately after space has
been gained for the canines by moving the incisors
anteriorly. In addition, the maxillary teeth are protracted
when the potential for an orthopedic effect is diminished
(age 9 to 10+, that is, at the end of the mixed-dentition
stage of development or later) and when the basal
discrepancy is not severe.

The movement of the maxillary teeth can be associated
with reverse torque to stimulate the most anterior part of
the maxilla to move in an anterior direction (point A).
Since the force requirements for moving the teeth are
modest, the buccal and palatal areas of the teeth are not
united and extraoral traction, pulling in an anterior
direction, can be attached to the labial arch either on
loops mesial to the canines or distal to the first molars.
Another type of appliance is a reverse headgear . This
functions to produce anterior movement to the maxilla
and to redirect the anterior movement of the mandible.
This appliance can be used when strong forces are not
necessary. Under these conditions, however, the
orthopedic effect may be limited.

TREATMENT FOR TYPE BTREATMENT FOR TYPE B
CLASS IIICLASS III
Characteristic of this type of malocclusion is the
overdevelopment of the mandible, especially in relation to
the maxilla. The profile is flat or concave, reflecting the
hyper development of the lower third of the face rather
than the underdevelopment of the middle third of the face.
The treatment of choice would be to inhibit or redirect the
growth of the mandible. For this purpose, a few appliances
are available.
CHIN CUP :
Orthopedic force is used to protract the
maxilla, while the chincap or mental anchorage serves to
redirect mandibular growth

REVIEW OF LITERATURE:
Appliances resembling chin cups have been in use since
the early 1800's. According to Graber, the early attempts
with the chin cup were not successful because of
incomplete knowledge of mandibular and facial growth, its
use on non growing patients, and an inadequate
understanding of the forces generated by the chin cup.
Armstrong applied 500 Gm. of force via chin cups on 100
adolescent patients with mandibular prognathism. He
reported that half of his patients showed improvement in
the Class III profile, whereas none of the control, non
treated patients showed any favorable change.

Thilander treated sixty patients with chin cups for 1 to 6
years. A significant percentage of patients did not
improve. The patients who showed improvement were
comparatively young and showed favorable dental
changes. The force generated by the chin cup in his study
was only 150 to 200 Gm. Graber, Chung, and Aoba
reported results in patients treated with chin cups for 12
to 14 hours each day with a force of 1.5 to 2 pounds on
each side. They showed that mandibular growth could be
redirected with a chin cup. They asserted that continuous
use of the appliance for a long period or through active
growth was necessary to achieve stable results.
Graber treated 35 Class III malocclusions in children
between the ages of 5 and 8 years with chin cup therapy
for 3 years. He found that the therapy was particularly
effective in patients with increased vertical growth of the
face.

Chin cup therapy primarily works on the hypothesis that
a force directed through the condyles will inhibit as well
as redirect the condylar growth. However, this therapy
alone may not be indicated for a fair percentage of
patients in skeletal Class III who show a small midfacial
bone or a retropositioned maxilla with relatively normal
mandibular dimensions. Jacobson and associates studied
149 Class III patients and noted that in approximately
one fourth of the sample the problem was due to
maxillary deficiency.
Several clinical studies in the past have noted that
treatment of patients in skeletal Class III should include
protraction of the maxilla with or without chin cups.
Oppenheim suggested a technique for moving the
maxilla forward. He noted that restriction of growth or
distal movement of the mandible was impossible

Cervical chin cupCervical chin cup

High pull chin cupHigh pull chin cup

Kettle and Burhapp reported an appliance for cleft lip
and palate which successfully inhibited forward
growth of the mandible and simultaneously caused
anterior movement of the maxilla.
Chin cup therapy may improve the following variables
of dental and skeletal Class III morphology:
 retrusive maxilla,
 moderate to severe protrusive mandible,
 anterior crossbite, and
 concave profile.

Both animal and clinical studies of chin cap treatment
have reported and confirmed numerous statistically
significant changes in the craniofacial complex as a
result of treatment:
1. A decrease in the mandibular plane angle.
2. A decrease in the gonial angle.
3. A decrease in the SNB angle.
4. A redirection in the downward vertical growth of the
midface.
However, as Mitani and Fukazawa
and other investigators have reported, when the Class III
malocclusion is characterized by maxillary retrusion,
chincap force may have inconsistent results and may not
be the treatment of choice. In these cases, the use of a
protracting appliance, either alone or in conjunction
with a chincap, may be the treatment of choice.

In dealing with the correction of the Class III malocclusion
with an anterior crossbite, there are two approaches - (1)
correction by adjustment of the skeletal bones, and (2)
correction by adjusting the dentoalveolar bone. The two
approaches are radically different and diametrically
opposite in basic principle. One stimulates alveolar bone
and the other inhibits alveolar bone.
Apparently, when we try to prevent forward growth of the
mandible by applying posterior and superior force with a
chin cap, it has an adverse effect on the gonion angle -
causing the angle to increase instead of decrease.
Apparently, this posterior and upward force from the chin
cap reverses the natural tendency of the gonion angle to
reduce as it grows. This involves basic biologic
phenomena, about which we have no knowledge at the
present time.

However, its application is limited to an extent because part of
the force can be dispersed as it pushes against the soft tissue and
also because there is no control of tooth position, which is
possible with other types of extraoral traction.
If we are trying to depict changes of the maxilla, it would seem
desirable to include the entire maxilla. In the illustrations
shown, only the anterior superior approximately one-half of the
maxilla (the "northeast" one-half) is included in the maxillary
triangle, while the "southwest" approximately one-half of the
maxilla, including the dentoalveolar portion, is not included in
the maxillary triangle.

The growth of the non-included portion of the maxilla establishes
the vertical dimension of the maxilla, and along with that of the
mandible establishes the vertical dimension of the face. The
mandibular triangle includes only the basal portion of the
mandible and dentoalveolar processes. " If the "relative
positions" of the maxilla and the mandible are not rigidly
specified, then vertical growth of the upper and lower
dentoalveolar processes cannot be accounted for. As pointed out
above, there are two gonion angle phenomena, (1) reduction due
to growth and (2) reduction due to Class III treatment. Also there
is a third phenomenon of mandibular change. This involves the
bending of the neck of the condyle. This backward bending of the
condyle is in response to Class II treatment with removable
appliances.

As the neck of the condyle reverts back toward its former position
post treatment, as it usually does (DeVincenzo 1991), one of four
post treatment reactions must occur;
1. The molar relation must revert back toward Class II occlusion,
2. The lower molars must move forward on the mandible,
3. There must be a change in the temporal mandibular joint, or
4. There must be a dual bite.
The authors of the Class III study speak of”shrinkage" of the
condylion-pogonion distance, but this is a misnomer. The distance
does not become smaller, it only fails to increase in proportion to
the growth of the condyle, because of the reduction of the gonion
angle. The backward bending of the neck of the condyle followed
by a reversion to its former position must be related in some
unknown way to maintaining the constancy of the axis of the
ramus.

EXTRA ORAL TRACTION:
By means of extraoral traction we hope to obtain
a) A repositioning of the mandible posteriorly so that
the condyle enters the glenoid fossa if there is an
anterior path of closure of the mandible;
b) Orthodontic movement, inclining the teeth
posteriorly;
c) Control of the anterior bite depth;
d) Better control of the vertical dimension; and
e) Influence over the potential growth and development
of the mandible.

There are two types of extra oral traction that can be
applied to the lower arch.
1. Kloehn type of face-bow that is placed against the first
molars.
2. The other consists of facial wires placed against the
incisor segment by means of ''J" hooks or loops on the
arch wire
Practically, the Kloehn type appliance has limited
applicability in open bite cases because tipping can lead to
clockwise rotation of the mandible and it cannot control
the position of the incisor segment. On the other hand with
the use of facial wires there are a number of beneficial
effects that can be obtained. One is that mandibular
incisors can readily be retracted without straining
anchorage since Class I forces are not necessary for
incisor retraction. Second is the control of anterior bite
depth . For example, in open-bite problems, a high-pull
headgear can be used.

A straight-pull headgear can be applied when bite depth is
shallow , whereas in the presence of a deep bite a low-
pull gear is suggested . In addition, it is possible to place
the force directly against the first molars by incorporating
molar stops into the wire. In this manner, the molars can
be held in situ, as when the deciduous second molar
exfoliates and the second premolar is erupting, or the
molars can be moved distally. Also, with facial wires,
mandibular clockwise rotation with possible increase in
vertical dimension can be avoided in open-bite cases.
Further, there is the possible restraint of forward growth.

This generally requires a combination type of therapy to produce
anterior movement of the maxilla and posterior movement of the
mandible. This is chosen when the malocclusion reflects
underdevelopment of the maxilla associated with hyper
development of the mandible. It can also be done when, during
treatment, to accept a compromise result between relationships of
the mandible and maxilla.
Maxillary protraction and mandibular retraction can be achieved
by using, in successive treatment periods, two types of extraoral
traction. For example, initially, a facial mask may be used to gain
space for the maxillary teeth and to protract the maxillary arch. In
a subsequent treatment period, an extraoral appliance can be used
to move the mandibular arch distally or, at least, to control the
incisor region and possibly influence mandibular growth and
development
TREATMENT OF TYPE A AND TYPE BTREATMENT OF TYPE A AND TYPE B

CLASS III ACTIVATORCLASS III ACTIVATOR
Somchai Satravaha, (AJO 1999)
The activator was introduced by Andresen and has been long
served for correction of skeletal Class II malocclusions. Rakosi
suggested modification of the activator for use in Class III
treatment. The appliance consists of wire and acrylic parts.
The wire components are
 4 stop-loops located mesial to all first molars to prevent mesial
tipping of the molars and to stabilize the appliance,
 lower labial bow to stabilize the appliance,
 upper labial pads to remove the force of the upper lip and
create periosteal pull to induce bone formation, and
 tongue crib to correct anterior tongue thrusting habit.

Class III ActivatorClass III Activator

The goal of using a Class III activator was to achieve posterior
positioning of the mandible or maxillary protraction. The
construction bite is taken by retruding the lower jaw. The
upper labial pad of the activator is intended to protract the
maxilla
Treatment Changes
 Effect on a backward positioning of the mandible.
 There were significant increases of the ANB angle and the
Wits values.
 The SNB and SNPog became smaller resulting in increasing
facial convexity (NAPog).
 The articular angle was significantly enlarged, thus
augmenting the sum of the saddle, articular, and gonial angles.
 The facial axis opened significantly.
 There were significant differences in the upper face height (N-
ANS), mandibular length (Co-Gn), and ramus length (Ar-Go).
 Dentoalveolar adaptations included labial tipping of the upper
incisors as well as lingual tipping of lower incisors .

Posttreatment Changes
 ANB angle as well as the Wits value remained quite stable.
 The SNA, SNB, SNPog, and NAPog became larger.
 The articular angle was increased
 The gonial angle exhibited a compensatory decline resulting in
decreasing of the sum angle
Long-term Results
 The Class III activator produced a more posterior position of the
mandible and changed direction of the mandibular growth.
 Both alterations remained through the post activator period.
 The maxilla and the mandible grew with an increase in maxillo
mandibular differential; the maxilla remained in a more forward
position
 There was significant difference in the degree of change of angle
OP/Go-Gn during the treatment but disappeared in the post
activator period due to compensatory reduction of the gonial angle.

(JCO 1997)
The Two-Piece Corrector was designed by
Gerald.R.Eganhouse 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
TWO PIECE CORRECTORTWO PIECE CORRECTOR

Two piece correctorTwo piece corrector

Appliance construction:
 A construction bite of 4-6 mm thick is taken using an “Exacto Bite”
registration jig. This gives an accurate centric relation, since the
mandibular incisors can be positioned precisely. In the laboratory, a
slide is created on the articulator, with the male(guide) portion in the
maxillary acrylic plate and the female (groove) potion in the
mandibular plate. The male portion is extended about 15 mm distal
to allow for anteroposterior sliding and to ensure lateral stability as
correction progresses. The anterior portion of the two pieces will
flush when the appliance is inserted, but the maxillary piece will
gradually slide forward on the mandibular piece
 Elastics provide the force between two parts of the appliance – one
hook on each side of the maxillary plate on the disto buccal aspect
of the maxillary first molar, two located in the maxillary first
bicuspid – canine area, and the fourth placed between the
mandibular canine and lateral incisor

The shorter elastics (1/8 ” 6oz ) are attached from the
mandibular hook to the most anterior hook on the
maxilla. As treatment progresses, it is moved to the
posterior hook. The longer elastic on each side stretched
from the mandibular hook to the molar hook can be ¼”,
or 3/16” depending on the comfort.
DURATION:
12 hours a day in conjugation with face mask. 11 months
of treatment time and 18 -24 months of retention
INDICATION:
Mild skeletal class III where future surgery would not be
indicated. And used during preadolescent and adolescent
growth periods

CLASS III BIONATOR (GARATINNI ET AL AJO
1998)
BALTERS BIONATOR III can be used in patients
with skeletal Class III malocclusion. The use of this
appliance causes some skeletal changes through
neuromuscular modifications.
CRITERIA
 Angle Class III molar relationship;
 Edge-to edge incisor position or anterior cross bite;
 Concave profile;
 Head hyperextension posture;
 Static and dynamic Class III neuromuscular attitude;
 Hypertonic upper lip;
 Low and forward tongue rest position.

Class III BionatorClass III Bionator

CONSTRUCTION BITE:
The construction bite was taken by gently
repositioning the mandible distally in centric
relation technique. The mandible is positioned
distally, applying as little force as possible in
order to put the condyle in centric relation,
avoiding compression in the retrodiscal pad. The
vertical thickness of the bite, corresponding to the
interocclusal acrylic between upper and lower
first molar should not exceed 3 to 4 mm, Patients
had to wear this appliance for at least 22 hours a
day.

RESULTS:
Mean increase in the upper jaw length
Advancement of point A
Palatal and mandibular plane angles widened
Increase of the anterior facial height
Reduced Antero posterior mandibular growth
Therefore, the Bionator III is helpful in Class III
malocclusion treatment in growing patients with
midfacial deficiency, hypo divergent growth
pattern, and reduced facial height.

TREATMENT IN PERMANENTTREATMENT IN PERMANENT
DENTITIONDENTITION
THE FOUR-STAGE TREATMENT PLANNING
PROCESS FOR CLASS III CASES
Stage 1 – setting a PIP for the upper incisors
The first stage in Class III treatment planning concerns upper
incisor position. It is necessary to determine an ideal position
and then decide whether it can be achieved. If not, a modified
position may be appropriate, which is less than ideal, but
acceptable. In this way a ‘planned incisor position’, or PIP, is
determined.

Stage 2 – the lower incisors
The second stage of treatment planning involves
positioning of the lower incisors. This is
frequently a key concern in Class III cases with
mandibular excess

Stage 3 – the remaining upper teeth
It is beneficial to evaluate the remaining upper teeth at stage 3.
If upper premolar extractions are necessary (usually second
premolars) then it is normally logical to extract lower first
premolar, in a Class III case. However, if the upper arch can be
treated without extractions, then a range of lower arch options
needs to be considered.
The third stage therefore involves deciding how to position the
rest of the upper teeth to fit the PIP for the upper incisors. It
normally assists Class III treatment mechanics if upper arch
extractions can be avoided. The dental VTO will confirm the
required movement of molars and canines.

Stage 4 – the remaining lower teeth
Lower premolar extractions assist in the retraction of
lower incisors, and are helpful to Class III treatment
mechanics in many cases. The dental VTO can be used
to reach a correct decision. In some Class III marginal
extractions cases, second molars may be considered

UPPER INCISOR MOVEMENT IN CLASS III
TREATMENT
In mild Class III cases, with a normal maxilla but
mandibular excess, the pre-treatment upper incisor
position may be close to the PIP. In this situation,
the case may require relatively little movement of
the upper incisors. However, in many Class III
cases, there will be a requirement to move the
upper incisors mesially. In some maxillary
deficiency Class III cases, it can be a challenge to
achieve the required mesial movement without
excessive Proclination. If a Class III case requires
mesial movement of upper incisors, it can be
achieved in two ways:

1. By proclination and mesial movement of upper incisors
within the available bone . Many Class III cases require
mesial movement of upper incisors, to keep pace with
the growing mandible. When upper incisors are
proclined forwards, each 2.5° of proclination creates
approximately 1mm of space per side, or 2mm in total.
For this reason upper premolar extractions are not
advisable in many Class III cases. If upper premolars
are extracted it can be difficult or impossible to procline
upper incisors.
2. By mesial movement of the maxillary bone as a result
of normal growth or orthodontic procedures.

Mesial movement of upper incisors within the
bone
During tooth leveling with the opening wires, there
is a tendency for upper incisors to move mesially
due to bracket tip, In Class III cases, this is
normally beneficial, and moves the upper incisors
towards PIP. Likewise, at the rectangular HANT
and the rectangular steel wire stages, the A/P
expansion and torque effects tend to produce
beneficial changes for most Class III cases. This
can be further augmented by the use of Class III
elastics. Because of these spontaneous tooth
movements during tooth leveling and aligning, the
early management of the upper arch in mild Class
III cases is normally straightforward

Limits to mesial movement of upper incisors
1. Excessive proclination. It is necessary to avoid excessive
proclination of the upper incisors, otherwise unesthetic appearance
and inadequate function will result. As a general rule, proclination
of the upper incisors beyond 120° to the maxillary plane should be
avoided, although there is individual variation . In some cases, less
proclination than 120° may be appropriate. Gingival recession and
long clinical crowns can result from excessive proclination.
2. Failure to fully achieve a positive overjet. This can be due to the
forward position of the lower incisors, or other reasons, and the
resulting bite can be difficult to manage
If this is allowed to persist, then there is a risk of enamel damage
and/or root resorption. Accordingly, it is unwise to attempt to
correct a Class III incisor relationship by orthodontic procedures
alone, unless it is clear from the outset that full correction can be
achieved, and a near normal overjet obtained.

Mesial movement of maxillary bone due to growth
 Maxillary growth cannot be relied on as a useful factor
in correction of Class III malocclusions. Generally in
this type of case, maxillary growth will not be favorable
or helpful in reaching the PIP for the upper incisor.
Mesial movement of maxillary bone due to orthodontic
treatment
 In growing individuals who have maxillary deficiency,
consideration can be given to treatment procedures
which will encourage orthopedic change within the
maxillary bone
 These can include rapid maxillary expansion, and the
use of reverse headgear

LOWER INCISOR MOVEMENT IN CLASS
III CASES
Distal movement of the lower incisors can be
achieved by distal movement of the teeth within
the mandibular bone, or by distal movement of
the mandible itself, when there is a displacement.
Unfavorable mesial movement of the lower
incisors can occur because of mandibular growth

Class III mechanicsClass III mechanics
Inter-maxillary Class III elastics are most helpful in
orthodontic (non-surgical) correction of Class III cases. They
tend to produce lower incisor retroclination, upper incisor
proclination, and A/P correction of the molar relationship. All
components of the Class III elastic force can therefore be
helpful in reaching treatment goals in average or low angle
cases.

Distal movement and retraction of the lower incisors
within the mandibular bone
In most non-surgical Class III treatments, it is helpful to
retract and retrocline the lower incisors . This can
compensate for mild mandibular prognathism or mild
maxillary retrognathism, and hence mask the underlying
skeletal discrepancy. The anatomy of the mandibular
bone in the lower incisor region places limits on what
should be attempted. Retraction and retroclination
beyond a figure of approximately 80° to the mandibular
plane is undesirable, because of the risk of dehiscence
and lack of bone support for the over-retracted incisors.
Also, dental esthetics and function will be adversely
affected

The required retraction and retroclination of the lower
incisors is normally achieved with the assistance of
Class III elastics, and treatment mechanics are easier in
cases where lower teeth have been extracted. Lower first
premolar extractions are most favorable in assisting
lower incisor distal movement, but loss of lower second
molars can also be considered .If the lower arch is
managed on a non-extraction basis, Class III mechanics
can be used to produce some retraction and
retroclination of the lower incisors.

This can produce distal tipping of the lower premolars and
molars, which in turn reduces the available space for the
lower third molars . Early removal of lower third molars
can be considered in some cases. A non-extraction
approach to Class III treatment may not achieve sufficient
lower incisor movement for the needs of the case.
Correction of the malocclusion may be possible, but not
over-correction. Thus, there is no provision in the result
for any late growth changes, which occur relatively
frequently in Class III cases, especially among male
patients.

Distal movement of mandibular bone –
distal repositioning
In many Class III cases, there is a mesial
displacement of the mandible at the start of
treatment. As treatment progresses, the mandible
repositions distally, to a position with the condyles
centered in the fossae. This favorable change can
be predicted at the treatment planning stage, and is
a useful adjunct to distal movement of the lower
incisors within the facial complex.

Mesial movement of mandibular bone – Class III
growth
This is a major factor in the treatment and subsequent
retention of Class III patients, especially males. If a
decision is made to treat the malocclusion with
orthodontics alone, every patient should be informed of
the unpredictable nature of Class III growth, and of the
implications of any unfavorable growth which may occur
in the retention period.

Retention of class IIIRetention of class III
Class III malocclusion worsens with the continuing
mandibular growth.
Relapse from continuing mandibular growth is likely
to occur and such growth is extremely difficult to
control.
Applying a restraining force to a mandible as from
chin cap is not effective in controlling growth in a
class III patient. In mild class III problems a
functional appliance or a positioner may be enough
to maintain the occlusal relationship during post
treatment growth.

Non surgical management of skeletal Class 3 malocclusion

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to Non surgical management of skeletal Class 3 malocclusion

Similar to Non surgical management of skeletal Class 3 malocclusion (20)

More from Indian dental academy

More from Indian dental academy (20)

Recently uploaded

Recently uploaded (20)

Non surgical management of skeletal Class 3 malocclusion