Class iii malocclusion /certified fixed orthodontic courses by Indian dental academy

VT’s

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VT’s

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IntroductIon
classIfIcatIon
frequency
etIology
VarIants
clInIcal examInatIon
functIonal
examInatIon
radIologIcal
examInatIon
dIfferentIal
dIagnosIs
treatment
retentIon plannIng
conclusIons
references


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

Orthodontic treatment not only involves
establishment of physiologically and anatomically
functional occlusion but also includes correction
of the relationship of the maxilla and mandible to
each other and to the rest of the craniofacial
complex.


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According to Angle (1899): Class III malocclusion
occurred when the lower teeth occluded mesial to
their normal relationship by the width of one
premolar or even more in extreme cases. (mesioocclusion)
Class III malocclusion can be defined as
skeletofacial deformity characterized by a forward
mandibular position with respect to the cranial
base and maxilla.
The facial dysphasia can be classified into
mandibular prognathism, maxillary retrognathism
or combination of both depending variation of the
anteroposterior jaw relation

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It is generally agreed by orthodontists that
skeletal Class III malocclusions are difficult to
treat by orthodontic means alone.
A skeletal class III discrepancy may be the result
of a large mandible, a small maxilla, a distally
positioned maxilla, or any combination of the
three.
Most often the patients are advised to wait until
the termination of active facial growth so that
maxillofacial surgery can be performed


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

Generally of 2 types:
 Dentoalveolar
 Skeletal

 TWEED (1966)

CLASS III MALOCCLUSION

PSEUDO CLASS III

SKELETAL CLASS III

Normal Mandible

Large Mandible

Underdeveloped Maxilla

Underdeveloped or Normal
Maxilla


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MOYERS
ACCORDING TO THE CAUSE

Osseous

Muscular

Dental

FREQUENCY OF CLASS III MALOCCLUSION
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1) Caucasians

1 to 4 %

Swedish population:
2) African – Americans

7 to 13 Years - 4.2%
14 to 18 Years - 9.4%

5 to 8%

3) Asian
Maxillary deficiency
Japanese:
4 % younger / 14 % older
Chinese:

3 % younger / 13 % older

Indians:

1.3% (J Ind. Ped & Prev Dent: 1998 – Uteraja et al)

Iranian:

2.1% (East Mediters Health J: 2006: Danaie et al)

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McGuigan (1966) – Inheritance of
class III malocclusion in Hapsburg
Family,
having
the
distinct
characteristics of prognathic lower
jaw.
Litton et al (1970) – Dental
characteristics of class III are related to
genetic inheritance.
Rakosi & Schilli (1981) Functional
factors: Anteriorly positioned tongue
believed to be a local epigenetic factor.
Also associated with syndromes like
Apert and Cruzons.

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Mental diseases – Compulsive habits of protruding
the mandible.
Enlarged tonsils and naso-respiratory diseases –
Results in anterior tongue posturing.
Premature loss of decidious molars – Results in
anterior mandibular displacement.
Tongue thrusting habit – Prevents eruption of
buccal segments, thus causing auto-rotation of
mandible into excessive intra occlusal space.



The posterior ‘squeezing out’ effect of molar
crowding:


due to 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

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Guyer et al (1986) 13-15 years- 57% - Normal to prognathic
Mand. with Retrusive Max.


Ngan P et al: AJODO : 1996

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Ellis & Mc Namara 1996: 243 possible types of Class III
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Wu, Lin 1986: 75 % of all Chinese Class III have max.
retrusion and increased lower facial heights.

COMPONENTS OF CLASS III
MALOCCLUSION
Vertical components :
•Vertical Deficient
•Vertical Normal
•Vertically excess

Anterio-Posterior components :
• Maxillary Deficient
• Mandibular excess
• Combined Maxillary deficient and mandibular
excess

DENTAL ASSESSMENT FOR DIAGNOSIS OF CLASS
III MALOCCLUSION (molar relation and over jet)
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Ngan P et al: Pediat Dent : 1997

1) Cranial Base

Angle – More Acute

Middle Cranial Fossa  Posterio-Superior Alignment
2) Maxilla

Decreased horizontal maxillary growth when
compared with the patients with class I malocclusion.
3) Mandible

Gonial Angle  Obtuse

Anteriorly placed
4) Dentoalveolar compensation

Proclination of upper incisors, Retroclination of
lower incisors.

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

In 1970 Dietrich reported that Class III skeletal
discrepancies change with age.
DENTAL AGE

MAXILLARY
ANTEROPOSTERIOR
DEFICIENCY

Stage I
Primary

23%

26%

Stage II
Mixed

30%

44%

Stage III
Permanent


NEGATIVE ANB
ANGLE

34%

37%.

These all results indicates that the abnormal skeletal
characteristics can become move pronounced with time.

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Growth prediction can be used to define Class
III tendency and identify specific skeletal
morphologic pattern.



Certain cephalometric measurements such as
cranial flexure, Porion location and ramus
position have been used predict normal or
abnormal growth.



Mito and Co-workers suggested that accuracy of
prediction is around 70-80% by use of cervical
vertebral to predicted mandibular growthpotential.

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GTRV analysis is performed in early
permanent dentition.
This helps clinicians to decide whether the
malocclusion can be camouflaged by
orthodontic or by surgical intervention
once the growth is completed.

GTRV =Horizontal growth changes of maxilla
Horizontal growth changes of
mandible


GRTV ratio normal individual 0.77 mm at
8-16 year.

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In case of Class III patient have GTRV Ratio
0.33-0.38 mm maxillary deficiency and can
be successfully treated by with camouflage
Class III patient with excessive mandibular
growth with GTRV<0.38 mm then it
indicated Orthognathic surgery.


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

The craniofacial skeletal pattern of children with
Class III malocclusion is evident in the early
deciduous dentition.



A sample of 69 Class III subjects were compared
with 60 subjects exhibiting normal occlusion.


They showed both maxillary retrusion and mandibular
protrusion with additional other skeletal characteristics
are short anterior cranial base length, larger mandibular
ramus height and corpus length.


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Class III skeletal imbalance shows either edge to
edge incisor relationship or an anterior crossbite in
deciduous dentition.
The skeletal components of the class III malocclusion
tend to worsen along with subsequent growth.
MEAN ANNUAL
GROWTH
INCREMENT

EARLY MIXED
DENTITION

LATE MIXED
DENTITION

MAXILLA

0.8mm / 1.1 mm

1.1 mm / 1.4 mm

MANDIBLE

4.5mm / 2.6 mm

4.4 mm / 2.8 mm

Class III
Normal growers

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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.


GPR

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Full incisor cross bites develops
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

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GPR

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

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.


Acute: the premaxilla segment can be retracted



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 recession or dehiscence can often be seen in early class
III malocclusion. This damage is irreversible and is an indication
for early treatment

GPR

The next step is Examination Of The Dentition,
including the morphology and number of
teeth. Congenital absence (e.g., in the maxilla:
missing canine or first premolar teeth) makes
treatment more difficult.
When evaluating the 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.
GPR


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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
GPR
correction may be necessary before surgery

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The Path Of Closure: 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.

GPR

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In addition, 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.


GPR

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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.

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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

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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.


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1.
2.
3.
4.
5.

6.

An increased gonial angle
Antegonial notching
Backward direction of condylar growth
Thin mandibular symphysis
Compensation in position of upper and lower
incisors in response to disproportionate jaw
growth.
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. GPR



Several studies have been done 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.

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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 CLASSIFICATION


Dentoalveolar Class III:
No apparent sagittal skeletal discrepancy (normal ANB angle)
Tipping of incisors : upper- lingual and lower -labial



Skeletal Class III:
 Max retrusion
 Mand prognathism
 Combination
Negative to 00 ANB angle and Wits appraisal
Increased mand length and more obtuse gonial angle
Tipping of incisors: upper- labial & lower lingual
(compensation)



Pseudo Class III (Kwong & Lin 1987)
Ceph values intermediate to class I & III.
Except for functional positioning of Mand in a more protrusive
position probably due to premature contacts (CO-CR
discrepancy ) or Habits.

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EARLY TREATMENT IN GROWING
CHILDREN

FUNCTIONAL AND ORTHOPEDIC APPLIANCES

LATE TREATMENT IN LATE
ADOLOSENCE AND NON GROWING
ADULTS


ORTHODONTICS + SURGERY

NAGN et al 2001

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

Class III malocclusion is established early in life and
is not a self correcting disharmony. Cephalometric
and morphometric gives treatment of Class III
malocclusion. It is carried out more efficiently during
early mixed dentition than late mixed dentition.



At post pubertal observation (Cs5 and Cs6) when
active growth of the skeleton is completed. Class III
subjects treated with rapid maxillary expander and
facial mask well before the growth (CS1) present and
there will be peak mandibular growth at Cs3 stage.
Early orthodontic treatment: J Daniel Subtenly


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To prevent irreversible soft tissue or on bony
changes. Often associated with anterior crossbite
leads to abnormal wear of lower incisor. Dental
decomposition of mandibular incisors leads to
tinning of alveolar place and gingival recession.
To improve skeletal discrepancies. Early orthopedic
treatment using facemask or chin cup therapy
improve skeletal relations which minimize excessive
dental decompensation i.e. over closure of mandible
and retroclination of mandibular incisor.
Early treatment eliminate the functional shift, CRCO discrepancies and prevents severe Orthognathic
surgeries .
AJODO 2006
Early treatment provides pleasing profile thus Apr Suppl

EARLY CORRECTION OF MANDIBULAR
DISPLACEMENTS
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

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
AJODO 2006
eliminate the potential ‘functional Apr Suppl

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MAXILLARY RETROGNATHISM
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Growing patients who present with maxillary retrognathism
should be considered for early expansion and development
of the maxilla.
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
AJODO
surgical/non-surgical decision can be reached. 2006 Apr Suppl

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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.


AJODO 2006 Apr Suppl

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.


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AJODO 2000

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. AJODO 2006 Apr Suppl
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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.

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AJODO 2006 Apr Suppl

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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.

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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



There are three important diagnostic principles
which merits attention.
First Principle:
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



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VT’s

Type

Pseudo-Class III

Anterior
position of
mandible
Present

Centric relation and centric
occlusion Significance
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



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


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

Third Principle:


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.


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

1.

2.

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.
Extraoral traction which pulls the maxilla anteriorly
functions in the same direction as the direction of
development.
Unlike posterior movement of the mandibular arch,
anterior movement of the maxillary arch appears to
have a greater chance of remaining stable.



RESULTS ACHIEVED:
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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.
 RESULT: Both an improvement in function and a
more esthetic profile.












The use of Protraction Headgear - > 100 years ago
Early orthopedic intervention - non surgical
alternative in the treatment of Class III
malocclusion with maxillary retrusion.
Protraction headgear – FORCE -directed forwards
in the same direction of growth of the maxilla
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.

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RESULTS PRODUCED :

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.
But, 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.

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APPLIANCE DESIGN:
 The orthopedic facial mask consists of three
basic components.


FACIAL MASK
BONDED/ BANDED MAXILLARY SPLINT



ELASTICS





The facial mask : an extra oral device composed
of
a fore head pad
 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 bywww.indiandentalacademy.comand tightening set
loosening


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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 as
deciduous canines

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TUBINGER 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.


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SEQUENCE OF ELASTICS:
 At the time of delivery
 After 2 weeks
 Increased to a max. of


3/8”
1/2”
5/16”

8 oz
14 oz
14 oz

2 weeks

Timing of wear:
Young patients (4 - 9 years) should wear the mask on a
full time basis except during meals.
 In older patients, it is worn at all times except during
school





Duration is 4-6 months.
Retained: with only night time wear or with a
maintenance plate, chin cup, FR III or a modified
utility arch with Class III elastics.

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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

VT’s

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.

VT’s


BIOMECHANICS:
VT’s

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.

VT’s








A heavy force at 300 -450 gms on either side at
about 300 to the functional occlusal plane in
both primary and mixed dentition is
recommended by most authors producing 10
degree of counter clock wise rotation being
acceptable .
Direction of force: Downwards and forwards
Point of Application: 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
VT’s

1.

2.

3.
4.
5.

The maxillary incisors moved in the anterior
direction, whereas the mandibular incisors
moved posteriorly.
After maxillary protraction, the maxilla was
displaced anteriorly, whereas the mandible
rotated posteriorly.
The mandibular plane angle and anterior lower
and total face heights increased.
There is no change in SN-palatal plane angle
during growth period.
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

6.
7.
8.

9.

10.

Position of the posterior nasal spine remained
stable
Over bite was improved by eruption of maxillary
and mandibular molars.
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.
The ratio of upper lip protraction to upper incisor
protraction relative to the vertical reference line
was 1:1.26
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.

VT’s

11.

12.
13.

14.

15.

A significant decrease in the upper lip sulcus depth
can be evaluated as another favorable effect of the
appliance on the soft tissue profile.
The lower lip moved posteriorly to lie behind the
Steiner S line
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.
Backward repositioning of the pog’, and slight
inhibition of anterior migration of the lower lip was
seen.
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.

VT’s

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


VT’s

# Indications for RME

VT’s



Patients who have LATERAL DISCREPANCIES
resulting in either unilateral or bilateral posterior
crossbites



ANTERO-POSTERIOR DISCREPANCIES



Cleft lip and palate patients with collapsed maxillae .



Procedure to gain arch length in patients who have
moderate maxillary crowding.

# Contraindications for RME
 Non cooperate patients
 Patients who have a single tooth in crossbite
 Patients who have anterior open bites, steep
mandibular planes, and convex profiles
 Patients who have gross skeletal asymmetry of the
maxilla or mandible
 Adults with severe anteroposterior and vertical
skeletal discrepancies


VT’s

VT’s









Does RME enhance the efficiency of maxillary
protraction with face mask in developing Class
III malocclusion?
Results: Face mask therapy effective in early
Class III MO
The need for palatal expansion in the absence of
a transverse discrepancy or a skeletal/ dental
cross bite is not supported.
Correction due to combined skeletal and dental
change.

AJO DO 2005 128; 299-309

VT’s





The skeletal change following protraction is
significant.
But has no correlation with expansion.


Kalha A S: EBD 2006:7,16-17

VT’s

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

VT’s

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.


VT’s

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.
Some of the mild class III can be treated with bite
planes in the anterior region (Nanda 2006)

VT’s

Characteristic of this type of malocclusion is the
overdevelopment of the mandible, especially
in relation to the maxilla.
The treatment of choice would be to inhibit or
redirect the growth of the mandible. For this
purpose, a few appliances are available.


VT’s

Orthopedic force with the chincup or mental
anchorage - serves to redirect mandibular growth
Appliances resembling chin cups have been in use
since the early 1800's.
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.

Types of chincup
VT’s

VERTICAL PULL CHIN CUP


VT’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.

VT’s

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.

VT’s









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 et al 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

As the neck of the condyle reverts back toward its former
position post treatment, as it usually does (De Vincenzo
1991), one of four post treatment reactions must occur;
1.
The molar relation must revert back toward Class III
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.

VT’s

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

VT’s

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

VT’s

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.

Somchai Satravaha: AJODO 1999


VT’s



The construction bite is taken by retruding the lower jaw.

Post treatment Changes





ANB angle as well as the Wits value remained quite stable.
The SNA, SNB, SN-Pog, and NA-Pog became larger.
The articular angle was increased
The gonial angle exhibited a compensatory decline resulting
in decreasing of the sum angle

VT’s

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

VT’s

WUNDERER’S MODIFICATION

KARWATZKY’S MODIFICATION

VT’s

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

JCO 1997

Appliance construction:
VT’s







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

VT’s

MALE GUIDE

FEMALE GROVE


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” – 6oz) 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

VT’s

VT’s

CLASS III BIONATOR
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.

Garatinni et al AJODO 1998


VT’s

• Upper lip pads
• Lower labial bow
• Protrusion bow in the upper arch


VT’s

MODIFICATIONS
• WITH UPPER LIP PADS
• WITH REPELLING MAGNETS

MODE OF ACTION


VT’s

AO 2005


VT’s

AJODO 1990


VT’s

JCO 2005 & AO 2006

VT’s

Liou et al JCO 2005

VT’s


JCO 2003

VT’s


Fun Ortho 2004

VT’s


WJO 2006

VT’s

TREATMENT OF CLASS III
MALOCCLUSIONS IN ADULT
OR NONGROWING
INDIVIDUALS


VT’s



When a patient is diagnosed as a Class III
malocclusion in the permanent dentition and if
there is a strong skeletal component to the Class
III malocclusion then treatment options are less.



Such treatment usually includes comprehensive
orthodontic therapy, either combined with
extraction or orthognathic surgery.




The Orthognathic surgical procedure is designed to
address the imbalance of the skeletal component (Eg:
mandibular set back in patient with mandibular
prognathism and Le-Fort I advancement in maxillary
skeletal retrusion.)



In patients who are expected to have excessive
skeletal growth in the future, the surgical procedure
is usually deferred until the end of active growth
period.



In the diagnosis and treatment planning of patients
who present with a Class III malocclusion in the late
deciduous or in the mixed dentition, several
treatment options are available.

VT’s

VT’s







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



Lower first premolar extractions are most
favorable in assisting lower incisor distal
movement, or Extraction of lower 2nd molars and
Distalization of the 1st molar to achieve a class I
molar relation (AO 2006) .



If the lower arch is managed on a nonextraction 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 .

VT’s



Early removal of lower 3rd 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.

VT’s






VT’s

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 :
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.



VT’s

VT’s

The incisors will need to be decompensated by
orthodontics before surgery, if there is to be an
optimal facial benefit from the surgery: REVERSE
ORTHODONTICS
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.

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.

VT’s

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- CAMOFLAGUE

In this theoretical representation, the
upper incisors were proclined 2° and
the lowers were retroclined 8°.

VT’s

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.

VT’s

VT’s



Early surgery is possible in maxillary deficient but
surgical intervention in young child may further
adversely affect the growth of maxilla.



Patients with true mandibular prognathism may
continue to grow for several years beyond the
puberty so that two lateral cephalograms are
taken at least 1 year apart demonstrate no
significant growth occurring over that period.


VT’s



The current surgical methods for correcting
skeletal Class III problems include:
 Setting

back prognathic mandible.
 Mandibular inferior border osteotomy
to reduce chin height or prominence.
 LeFort I osteotomy to advance a
deficient maxilla.


VT’s



Skeletal discrepancies can not be resolved during
mixed dentition by growth modification may
require comprehensive appliance therapy or
surgical correction.



Some patients treated in early childhood may
recur malocclusion during adolescence.
Treatment in adolescence is indicated to alleviate
the potential psychosocial problems and reduce
the need for surgery.



Malocclusion with mild mandibular prognathism
and moderate overbite can be corrected by



Class III elastics with or without extraction of
teeth are used to camouflaged the skeletal
discrepancy, resulting in acceptable facial
profile.



As early as 1907 Edward Angle suggested that
the only way to correct severe Class III
malocclusion in adult was to combine surgery
and orthodontic treatment.



Before 1970s must thought that Class III
malocclusion were primarily caused by
excessive anteroposterior growth of the
mandible and most were corrected by

VT’s



However later studies indicated 20-25% of
mandibular protrusion, but also around 75% of
maxilla deficient cases also leads to Class III
malocclusion so that clinician should analyse
where the fault, whether in maxilla or
mandible or combination.



Maxillary growth may be completed at age 14 15 years were as mandibular growth may
continue until early 20 years. After this surgical
procedure can be carried out.


VT’s

VT’s

Chung, Kim, et al : AO 2006


VT’s



Eliminate anterior and posterior dental
compensation with guideline from orthodontic
visual treatment objectives (VTO).



Establish appropriate anteroposterior and vertical
incisor position.



Achieve compatible arch forms and inter canine
widths, which are essential to make dental
midlines compatible at surgery.



Correct tooth size discrepancy



Class III mechanics, molar tie backs are not
used when leveling & teeth are allowed to
level forward. The orthodontic VTO should
be referred to confirm the extent of incisor
decompensation required.



On the completion of leveling, Class II
elastics may be used to advance the
mandibular buccal segment and further to
procline the mandibular incisors.



When decompensating the mandibular
incisors, clinician should keep in mind,
patient with mandibular antero posterior
excess often have a very thin bony symphysis
and a small area of attached gingiva in the
incisor region

VT’s





Bilateral sagittal split osteotomy (BSSO) is the
procedure of choice,
Although (TOVRO) trans-oral vertical ramus
osteotomy may be indicated in large setback
procedures.

NOTE: Correct positioning of condyle is important.
The surgeon should carefully free the medial
pterygoid an a stylomandibular ligament from the
medial side of the ramus. Otherwise proximal
segment will be pushed back by distal segment &
with return of muscle function, the patient will tend
to position mandible forward again.

VT’s

VT’s



The incidence of neuro-sensory morbidity
with trans-oral Vertical ramus osteotomy is
less associated with bilateral sagittal split
ramus osteotomy.



A genioplasty is often indicated to place
the chin in most esthetic antero posterior,
vertical and midsagittal position.


VT’s



The clinician should design the retention plan
according to original malocclusion and its
possible relapse tendency.



If tendency to relapse is noticed, light (2.5 3.5 oz) Class III elastics should be placed
immediately.



A rectangular arch wire should be placed in
maxilla to prevent the molar extrusion.

VT’s








BSSO for Class III – 30% likelihood to relapse
For isolated mand set back (1.49mm = 22.6%)
the most important factor responsible for relapse
is its magnitude.
In bimax surgeries (set back = 5.44 mm &
relapse = 3.33 mm – 61.2 %) : counterclockwise
rotation of the proximal segment
Rigid internal fixation did not guarantee more
stability.(9.8 – 66%)
Int’l J

of adult ortho & orthga surgery: 2001

VT’s



Maxillary anteroposterior deficiency often
misdiagnosed as mandibular anteroposterior
excess. So the clinician must carefully
distinguish between the two deformities.




Cases of maxillary deficiency often involve
crowding in the maxilla and retraction of
incisor is indicated. This will require
extractions.

1.If maximum retraction is necessary or significant
crowding is present - extn of 1st premolar is
indicated
2.If little retraction is necessary or crowding is
slight – 2nd premolar is indicated.
3. Advancement of mandibular incisors from an
upright or lingually tipped position may be
limited by lack of attached gingiva or thin
alveolar bone and symphysis. Extn of
mandibular 2nd premolar is necessary to provide
required space towww.indiandentalacademy.comcrowding.
manage

VT’s

Orthodontic Mechanics:
Pre surgically:- the maxillary incisors should be
placed in good angulation in the central trough
of bone. To achieve best esthetic results.
Surgical treatment:-The maxilla is advanced by
means of Le-fort I Osteotomy. So surgeon can
correct discrepancies in the Vertical,
Transverse and Sagittal planes.


VT’s



Undesirable soft tissue changes may occur,
including widening of &/or tipping up of the nose
and increased nasolabial angle. So that patient
should be informed about expected soft tissue
changes.

Post surgical orthodontics: Surgical splint is given only in multipiece LeFort-I
maxillary osteotomy or in bi-jaw surgery.
 Once the splint is removed immediately the
orthodontist should place orthodontic palatal bar
and continuous arch wire to maintain achieved
results.


VT’s

VT’s



In as study done by Chen et al in 2007 compared
the short and long term effects of bimaxillary
surgery and mandibular setback on the narrowing
of airway and concluded that bimaxillary surgery
prevent narrowing of the airway space, which may
lead to obstructive sleep apnea.

AJODO 2007

VT’s



DISTRACTION OSTEOGENESIS:


MAXILLARY DISTRACTION


VT’s

VT’s





Tooth borne anchorage
devices like TPA and
Expansion Screws may lead
to Dentoalveolar
compensatory changes like
lose of arch length, forward
movement of molars,
proclination of max. incisors,
etc.
Solution: Hydroxylapatite
coated Osseointegrated
palatal onplant

VT’s






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 the mandible using a
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.




Wilford et al in their literature review attributed
few identifiable & unavoidable factors to relapse
in class III individuals:
Unstable presurgurgical orthodontics
 Condyle being forces posteriorly into the fossa
 Occlusal splints that open the bite and create an upward
and forward rotation of the mandible on splint removal
 Failure to remove the bony interferences from proximal
segment that do not allow the segments to fit passively
 Macroglosia
 Untreated active condylar hyperplasia.



VT’s

VT’s











To improve skeletal discrepancy and provide a more
favorable environment for future growth. But this may prove
detrimental for long term stability of the case.
Early orthopedic treatment using face mask or chin cup
therapy improve skeletal relations which in turn minimizes
excessive dental decompensation.
Early treatment provides more pleasing facial profile, thus
improves psycho-social development of child.
It eliminates Orthognathic surgery maximizing growth
potential of maxilla may minimize the extent of surgical
procedures in cases of severe Class III malocclusion.
“Correct diagnosis and proper treatment planning
holds the key to successful outcome of the case.”

VT’s

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Contemporary orthodontics: William R. Proffit
Early orthodontic treatment: J Daniel Subtenly
Orthodontics current principles and techniques: T.M Graber, Vanarsdal,
Vig
Biomechanics and esthetic strategies in Clinical Orthodontics: Ravindra
Nanda
Text of orthodontics: Samier Bishara
Graber Petrovic Rakosi
Seminar in orthodontics 2005 – EARLY TREATMENT
AJODO 2006 Apr Suppl.
Int’l J of adult ortho & orthga surgery: 2001
Ngan P et al: AJODO : 1996
Ngan P et al: Pediat Dent : 1997
AJO DO 2005 128; 299-309
Kalha A S: EBD 2006:7,16-17
JCO 1997 – 2 PIECE CORRECTOR FOR CLASS III
Garatinni et al AJODO 1998
J Ind. Ped & Prev Dent: 1998 – Uteraja et al
East Mediters Health J: 2006: www.indiandentalacademy.com
Danaie et al

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Class iii malocclusion /certified fixed orthodontic courses by Indian dental academy

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