Principles of class iii treatment reformated /certified fixed orthodontic courses by Indian dental academy

Principles of class III
treatment
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CLASSIFICATION
Class III
DENTAL
SKELETAL
TRUE
PSEUDO
TRUE

features of true and pseudo class III
True class III
• Concave profile
• a class III skeletal pattern,
• No premature contacts
• Forward path of closure
• Gonial angle increased or
decreased.
• Retrusion of mandible is not
possible
Pseudo class III
Straight / concave
a class I skeletal pattern,
Premature contacts present
Deviated path of closure
Normal gonial angle
Retrusion of mandible is possible

Class III subdivision
This is characterized by class I molar relation on one
side and class III on the other side

Habitual occlusion Centric relation

Class III modifications of Martin
Dewey
• Type I: the upper and lower dental arches
when viewed separately are in normal aligment
. But when the arches are made to occlude the
patient shows an edge to edge incisor
aligment, suggestive of forwardly moved
mandibular dental arch.
 Type II:Type II: Mandibular incisors are crowded andMandibular incisors are crowded and
are in lingual relation to the maxillary incisors.are in lingual relation to the maxillary incisors.
 Type III:Type III: The maxillary incisors are crowded andThe maxillary incisors are crowded and
are in cross bite in relation to the mandibularare in cross bite in relation to the mandibular
anteriors.anteriors.

CEPHALOMETRIC CLASSIFICATION OF
CLASS III – Moyers
1. Class III malocclusions caused by dentoalveolar
malrelationships
2. Class III malocclusions with a long mandibular
base
3. Class III malocclusions with under developed
maxilla

4. Class III skeletal malocclusion with a
combination of underdeveloped maxilla and
prominent mandible (horizontal / vertical
growth pattern)
5. Class III skeletal malocclusion with tooth
guidance or pseudo forced bite.

ETIOLOGY OF CLASS IIIETIOLOGY OF CLASS III
1 Genetical determination
2 Functional factors and soft tissue
influence
3 Occlusal forces due to abnormal eruption
pattern
4 Environmental factors
5 other factors

True class IIITrue class III Pseudo class III
Large mandible
Retro positioned maxilla
Small maxilla
occlusal prematurities
enlarged adenoids
premature loss of deciduous molars
Abnormal path of eruptionForwardly placed mandible
Combination of the above

Initial Symptoms of Class III
Malocclusion
• Early signs of true, progressive mandibular
prognathism occasionally can occur in infancy.
• A protruded mandible with an anteriorly
positioned tongue can be seen only in cases of
very severe dysplasia before the eruption of the
incisors.
• In the first months of life a sequential
development of the Class III condition may be
observed.

This step-by-step progression is
• 1. Eruption of the maxillary central incisors in a lingual
relationship and the mandibular incisors in a forward
position with no overjet
• 2. Development of an incisal crossbite during the eruption
of the lateral incisors into a normal relationship
• 3. Full incisor crossbite some weeks later
• 4. Flattening of the tongue as it drops away from palatal
contact and postures forward, pressing against the lower
incisors
• 5. Habitual protraction of the mandible by the child into the
protruded functional and morphologic relationship

TREATMENT PLAN

Management of pseudo-Class III malocclusion
 Involves both permanent & deciduous dentition.
 The optimum ages 6–9 years.
 Reason to avoid early correction of pseudo-Class
III in the deciduous dentition because of poor
stability of correction. (cross bite may develop
during the transitional dentition, pt lands up in
further treatment )

 Some practitioners prefer to wait for the
permanent maxillary incisors to erupt before
initiating therapy due to the natural tendency of
teeth to erupt in a lingual position during dental
arch development.
 Sometimes, functional deciduous anterior
cross bites occasionally correct themselves
spontaneously.

White – intervention of pseudo-Class III
malocclusion in mixed dentition when maxillary and
mandibular incisors have erupted allows the
permanent teeth to erupt into a better position
and improves the dental aesthetics.
Advantages of treatment of pseudo-Class III
malocclusion in the mixed dentition:
prevents unfavorable growth of skeletal
components (early treatment of anterior cross bite can help to
minimize adaptations that are often seen in severe late adolescent
malocclusion)

Prevents functional posterior cross bite
and habits, ( bruxism develops from anterior or posterior
interferences).
Gaining space for eruption of canines (lack of
space could be caused by retro-inclination of upper incisors
frequently found in pseudo or Class III malocclusion)
Avoids the risk of periodontal problems to
mandibular incisors caused by the traumatic
occlusion due to the cross bite.

• Equilibration
• Acrylic inclined planes along the
mandibular incisors
• Maxillary labial bow along with mandibular
inclined plane.
• Bionator therapy

• Equilibration -
• Systematic reshaping of the occlusal
anatomy of teeth to minimize the role of
occlusal disharmonies
• In primary dentition – grind with bur
• In mixed dentition – teeth should be
moved with appliances to a position
where it achieves a final proper
occlusion

Indicated in pseudo class III with upper
incisors tipped lingually causing anterior
mandibular displacement on closure from
postural rest to habitual occlusion.

SKELETAL – TREATMENT
OPTIONS
GROWTH
PRESENT
GROWTH
COMPLETED
PRIMARY DENTITION
MIXED DENTITION
PERMANENT DENTITION
CAMOUFLAGE
SURGICAL

Treatment in the deciduous
dentition
• FUNCTIONAL CLASS III
RELATIONSHIP.
• CLASS III RELATIONSHIP WITH THE
FAULT IN THE MANDIBLE
• CLASS III RELATIONSHIP WITH THE
FAULT IN THE MAXILLA

FUNCTIONAL CLASS III RELATIONSHIP.
• no skeletal Class III signs are present.
• The mandible slides anteriorly into an
edge-to-edge or crossbite relationship.
• Usually the tooth guidance is in the
canine region.
• Careful equilibration of these teeth is
needed to correct the problem.

• In other cases,
• decreased intercanine distance
- caused by chronic nasorespiratory
problems;
- low tongue posture are the
morphology that results in tooth guidance.
Rx-- expansion of the maxillary arch without
canine equilibration is indicated.

So a functional Class III relationship may be
a beginning sign of a true Class III
malocclusion. Patients with such
malocclusions need to" be followed
continuously, and orthopedic guidance
may be needed at any time.

CLASS III RELATIONSHIP WITH THE FAULT IN
THE MANDIBLE
• the mandibular basal measurement -large
• S-N-B angle can be large.
• Maxilla- usually normally developed
Treatment objective
Growth inhibition or redirection and posterior
positioning of the mandible
A chincap or a reverse (Class III) activator
can be used to exert a retrusive force on
the mandible www.indiandentalacademy.com

CLASS III RELATIONSHIP WITH THE FAULT IN
THE MAXILLA
• retrognathic maxilla or midface
• orthognathic mandible
• The tooth buds of the upper incisors are often
rotated and crowded.
Treatment
in mild cases - with an activator or Fra'nkel
appliance,
in severe problems- extraoral orthopedic
protractive force using a Delaire-type face mask
is required.

• Kraus (1956), Fra'nkel (1967), and others
recommended Loading the palatal area behind
the upper incisors while relieving the labial
muscle forces with lip pads, is often effective.
• Eruption of the incisors before the maxillary
incisors become locked behind the mandibular
counterparts is advantageous.

• A combination of these two types of Class III
malocclusions (retrusive maxilla and protrusive
mandible) of course is possible and logically
requires therapeutic control of both areas via
maxillary protraction and mandibular retractive
growth guidance.

Class III / reverse bionatorClass III / reverse bionator
 to encourage development of maxilla.
 construction bite- post most retruded
position of mand.
 allows a labial movement of maxillary
incisors and restrictive influence on the
mandible.

MIXED DENTITION
MAXILLARY EXCESS
MANDIBULAR
DEFICIENCY
COMBINATION
VERTICAL
HORIZONTAL
AVERAGE
SKELETAL GROWTH PATTERN

In Class III malocclusions with fault
in the mandible in mixed dentition
• treatment objectives - growth inhibition and
posterior mandibular positioning
• early mixed dentition, extraction of the lower
deciduous canines and deciduous first molars
can be performed to facilitate the correction of
the incisal guidance.
In some selected cases,
enucleation of the lower first premolars
- decreasing lower arch length and providing
dental compensation for the skeletal problem as the
six lower anterior teeth are retracted into the
extraction sites.
-Germectomy also limits alveolar
growth.

• Rx class III in vertical growth pattern is more
difficult than treatment with a horizontal pattern.
• Achieving a good overbite is difficult with a
vertical growth vector. Excessive anterior face
height is evident; it compensates for the growth
but usually is not enough.
• In these cases a chincap or a low or high-pull
headgear may be helpful to control posterior
eruption, depending on the growth direction.

In Class III malocclusions in the
mixed dentition with the fault in the
maxilla,
• promote growth and protract the maxillary complex.
• Both horizontal and vertical growth should be
encouraged because maxillary vertical deficiency
enhances the apparent mandibular protrusion with its
autorotation into an overdosed habitual occlusion.
• An improvement in the midface concavity can be seen if
treatment is performed during the eruption of the
maxillary incisors.
• The eruption can be channeled as desired by the guiding
planes of the activator, with simultaneous relief) of labial
muscle force provided by the lip pads at the depth of the
vestibule. Simultaneously the mandible can be put under
retrusive chincap force to reduce the sagittal discrepancy

• . An alternate approach
• align the maxillary arch with a short period of
direct-bonded attachments or active plates; the
mid-face can be favorably influenced by the
orthopedic protraction of a Delaire mask.
• If the crowding in maxillary arch is too severe,
extraction may be required in the maxillary arch.
In such a case the lower first premolars also
must be removed to allow proper dentitional
adjustment.
• fixed multiattachment therapy & possible
orthognathic surgery may be the therapies of
choice, depending on the severity of the problem
and the age-linked expressivity.

JEAN DELAIRE(1960) of France had found
that this approach involves applying forces on
to the maxillary sutures while reciprocally
pushing on the mandible and the forehead
through the anchorage provided to the facial
mask.

.
Delaire mask

petit facial mask
lateral view frontal view

COMPONENTS OF FACIAL MASK
a. Facial mask
b. Bonded maxillary expansion splint .
c. Heavy elastics

a. Face mask
 Extra oral device modified by petit
A forehead pad and a chin pad connected by a
heavy steel rod
 A cross bow is attached to rod , to which
elastics are attached.
Brings a downward and forward traction on
maxilla.
Can be adjusted by adjusting screws.

b. Bonded maxillary splint
 An acrylic splint for permanent and primary
molars
 Hook engaged in mesial aspect of splint in first
deciduous molar region
c. Elastics
 Elastics attached to the hook and traction is
applied

Effects
1. correction of CO-CR discrepancy, a shift in
occlusal relation ship occurs immediately in pseudo
class III
2. max protraction with 1-2 mm of forward
movement is seen along with forward movement of
dentition
3. lingual tipping of lower incisors in preexisting cross
bites
4. redirection of mandibular growth in downward and
backward direction which results in increase in
lower anterior facial height.
5. Forward movement of maxilla and maxillary teeth
specially in old pts.

Skeletal effects of maxillary protraction
 Nanda – found that with the same line of
force , different mid facial bones were
displaced in different directions depending on
the moment of force generated at sutures.
 Jackson, Konich and Shapiro – found that
anterior positioning of the maxillary complex is
accompanied with a small amount of clockwise
rotation during the treatment period.

Frankel III myofunctional applianceFrankel III myofunctional appliance
Counteract the muscle forces acting on
maxillary complex.
Early mixed dentition and deciduous dentition.
Mechanism of action:
it shields the distracting forces of upper lip
transmitted on to the maxilla by upper labial
pads and are transmitted to the mandible by
the loose fit of the appliance.

LIP PADS – eliminate the restrictive forces of
the upper lips on the maxilla as well as they
provide a stretching of the adjacent periosteum
, stimulating bone apposition on the labial
alveolar surface.
The distracting forces of the upper
lip are removed from the maxilla by
the upper labial pads. The force of
the upper lip is transmitted through
the appliance to the mandible
because of the close fit of the
appliance to that arch

Occlusal view of FR III

Treatment effects-
Skeletal and dental effects are produced
Forward movement of maxillary skeletal and
dental land marks
Backward rotation of the mandible with an
increase in the lower anterior facial height
Proclination of the upper incisors and lingual
tipping of lower incisors are seen.

CHIN CAP – mandibular prognathismmandibular prognathism
• Oldest of all the treatments.
• Chin cups have been used for Class III
correction.
• Design of a chin cup for Class' III patients
directs the force posteriorly through the
condyles.
• To rotate the mandible upward, the line of
force should be through the centroid of the
roots of the lower arch.

Types-
1) Occipital pull chin cap- in mand prognathism
2) Vertical pull chin cap – in steep mand plane angle
and excess lower ant facial height.
Chin cup design To rotate the mandible closed, force is directed
through the posterior teeth, not through the condyle.

Occipital pull chin cap –
: in mild – moderate mand prognathism
: it is successful if patients can bring
incisors edge to edge
: used in short lower ant facial ht
( increases the vertical dimension)
: if vertical dimension should be
increased the line of force should pass thro
the condyles and below it .

Treatment in the permanent
dentition
• If Class III malocclusion is primarily
dentoalveolar and not a true skeletal
malrelationship-Rx is successful
• The skeletal type of Class III malocclusion
can be compensated by tooth removal
and surgery.

CAMOUFLAGE TREATMENT
Beyond the adolescent growth
spurt to correct a skeletal problem teeth
should be displaced relative to their
supporting bone to compensate for the
underlying jaw discrepacy. This is termed
camouflage treatment.

The characteristics of a patient who
would be a good candidate for
camouflage treatment are:
• Too old for successful growth modification
• Mild skeletal Class III
• Reasonably good alignment of teeth (so that the
extraction spaces would be available for
controlled anteroposterior displacement and not
used to relieve crowding)
• Good vertical facial proportions, neither extreme
short face (skeletal deep bite) nor long face
(skeletal open bite)

camouflage treatment is avoided in:
• Moderate or severe Class III, and vertical
skeletal discrepancies
• Patients with severe crowding or protrusion of
incisors, in whom the extraction spaces will be
required to achieve proper alignment of the
incisors
• Patients with excellent remaining growth potential
(in whom growth modification treatment should
be used) or non-growing adults with more than
mild discrepancies (in whom orthognathic
surgery usually offers better long-term results.www.indiandentalacademy.com

The characteristics of a patient who
would be treated best by surgically
repositioning the jaws are:
• Severe skeletal discrepancy or extremely
severe dentoalveolar problem
• Adult patient (little if any remaining
growth), or younger patient with extremely
severe or progressive deformity
• Good general health status (mild,
controlled systemic disease acceptable)

SURGICAL TREATMENT
SURGICAL
POST SURGICAL
PRESURGICAL

SURGICAL PROCEDURES:
In case of,
Maxillary deficiency- Le Fort I Osteotomy
Mandibular excess- Saggital split
osteotomy
prominent chin- Reduction Genioplasty.

POST SUGICAL
ORTHODONTICS
Can be initiated 3 to 4 weeks after
the release of immobilization. Stabilization
arch wires are removed and replaced by
working arch wires with light vertical forces
till a good stable occlusion is achieved.

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Principles of class iii treatment reformated /certified fixed orthodontic courses by Indian dental academy