Clinical Guidelines for Treating Developing Class III Malocclusion

CLINICAL GUIDELINES FOR
TREATING DEVOLOPING
CLASS III MALOCCLUSION
“ ONE OF THE MOST DIFFICULT PROBLEMS TO TREAT IN MIXED
DENTITION IS CLASS III MALOCCLUSION”
Grabber , Vanarsdal , Vig (current principles and techiniques 4th edition)

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 CLASSIFICATION
 ETIOLOGY






TERRATOGENS
SYNDROMES
GENETIC
ENVIRONMENTAL INFLUENCES.
THE POSTERIOR MOLAR CROWDING

 DIAGNOSIS
 GROWTH
 Prepubertal growth period
 Pubertal growth period
 Postpubertal growth period

 TREATMENT STRATERGIES
 TREATMENT OPTIONS.

CLASSIFICATION
ANGLE in 1889 defined class III molar as 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.

Tweed divided class III into
# Pseudo class III malocclusions and
# True class III malocclusions.

Moyers classified them according to the cause of the problem
# Osseous
# muscular
# dental in origin
Moyers emphasized the need to determine whether the mandible,
on closure, is in centric relation or “convenient” anterior
position (for patients with neuromuscular or functional
malocclusions). Anterior repositioning generally results from
tooth contact relationship, which forces the mandible into a
forward position.


Class III malocclusion can be defined as a skeletal facial deformity
characterized by a forward mandibular position with respect to
the cranial base and/or maxilla . This facial dysplasia can be
classified into

# mandibular prognathism,
# maxillary retrognathism,
# a combination of both, depending on the variation of the anteroposterior
jaw relationships.

Patients also often exhibit maxillary constriction that is manifested
as an anterior and/or posterior crossbite. Petit describes such
patients as having a "prognathic syndrome" in which the
underlying skeletal elements may be out of balance in all three
planes of space.
Vertically, they can also be divided into three basic types depending
on the vertical disproportions:
# long
# average
# short face.


Tweed divided class III onto two distinct categories
CATEGORY A
These are characterized by a conventional shaped mandible. If the
anterior cross bite has been present over a period of 2-3 years or
more, the mandible is larger than average. The junction of ramus
and body forms a “lazy L”. The FMA is flat and ranges between
10 and 22 . The occlusal plane is parallel to the mandibular
border as there is no excessive height in the incisor area. The
maxilla, on the contrary is more underdeveloped. The ANB may
be –7 to –10 if not treated early.
Ideal treatment time is during mixed dentition (7-9 yrs of age)
but if the malocclusion occurs in primary dentition, it can be
started as early as 4 years of age. As a rule, no retention is
necessary.

CATEGORY B
These are characterized by very obtuse gonial angles and a steep
FMA that ranges from 30 to 50 and upward.
The occlusal plane converges posteriorly towards the mandibular
border, because of excessive height from incisal cutting edges to
the mandibular border as compared to the molar height to the
mandibular border.
In severe cases, the mandibular incisors are retrusive . The labial
and lingual plates of alveolar bone are thin. At the junction of
basal bone and alveolar process, the thickness of bone
labiolingually is 3-4 mm. The lower lip is over developed and
overactive when the patient speaks.
Tweed calls them as unfortunate children.

CENTRIC
RELATION


SHORT

AVERAGE


LONG

ETIOLOGY
1.TERRATOGENS
Teratogens causing Cleft lip and palate are Aspirin, Cigarette smoke
(hypoxia), Dilantin, 6-Mercaptopurine. Cleft lip and palate result in
a maxillary deficiency.
Vitamin D excess causes premature closure of sutures and might lead
to a class III malocclusion.
2.SYNDROMES
 Crouzons syndrome - Is charecterised hypertelorism, strabismus,
midface hypoplasia, a prominent beaked nose, high arched palate,
mandibular prognathism and dental malocclusion.
 Fetal alcohol syndrome – deficiency of midface and maxillary
growth may manifest as class III.

 Acromegaly is caused by an anterior pituitary tumor that
secretes excessive amount of growth hormone. 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.
 Hemimandibular hypertrophy - The reason is unknown.
Formerly called Condylar hyperplasia, it is now called as
hemimandibular hypertrophy as the body of the mandible is also
affected. This condition leads to a class III with asymmetry.
 Basal cell nevus– bifid rib syndrome. Also called Gorlin and
Goltz syndrome, it exhibits mild mandibular prognathism, rib
anomalies, vertebral anomalies, cutanoeus, neurologic and
ophthalmic anomalies.

Cleidocranial dysplasia - It is an inherited disease. It appears as a
dominant mendelian characteristic and may be transmitted by
either sex
• Maxilla is underdeveloped and smaller than normal in relation to
the mandible . However, Davis has reported that 70% of patients
have prognathic mandible and normal maxilla.
• There is a high narrow arched palate and an actual cleft is
common.

Achondroplasia (chondro dystrophia fetalis) -It is a hereditary
autosomal dominant disoder .Patient (dwarf) has a
brachycephalic head and thickened muscles. Retruded maxilla
because of restriction in base of the skull. This produces a
relative mandibular prognathism

3.GENETIC INFLUENCES
HAPSBURG JAW. This was the famous mandibular prognathism
demonstrated by several generations of the Hungarians/Austrian
dual monarchy.


Strohmayer (1937) concluded from his detailed pedigree analysis
of the Hapsburg family line that the mandibular prognathism
was transmitted as an autosomal dominant trait.
Hughes and Moore 1942 suggested that the mandible and maxilla
are under separate influence of genetics control, and that certain
portions of individual bones, such as the ramus, body, and
symphysis of the mandible are under different genetic and
environmental influences.
Suzuki (1961) studied Japanese families and noted that there was a
significantly higher incidence of mandibular prognathism in
members of family (34.4%) in comparison of families of
individuals with normal occlusion (7.5%).


Schulze and Weise (1965) also studied mandibular prognathism in
monozygotic and dizygotic twins. They reported that
concordance in monozygotic twins was six times higher than
among dizygotic twins.
Watnick (1972) studied 35 pairs of monozygotic and 35 pairs of
dizygotic like-sexed twins using lateral cephalometry.
 Areas, such as the lingual symphysis, lateral surface of the ramus
and frontal curvature of the mandible are predominantly under
genetic control.
 Other areas, such as the antegonial notch, are predominantly
affected by environmental factors.


Litton et al (1970) carried out an analysis of the literature and also
analyzed a group of probands, siblings and parents with Class III
malocclusion, and analyzed the results in an effort to determine a
possible mode of transmission.
Both autosomal dominant and autosomal recessive transmission
were ruled out and there was no association with gender .
The polygenic multifactorial threshold model put forward by
Edward et al 1960, however, did fit the data and accordingly
proposed a polygenic model with a threshold for expression to
explain familial distribution.


Nakasima and Nakata (AJO 1982) assessed the craniofacial
morphologic differences between parents of Class II patients and
parents of Class III patients, as well as parent-offspring correlations,
and the genetic and environmental components of variation within
the craniofacial complex in these malocclusions. ,
– The results showed that The parents of Class III patients had a
concave profile with a mesioclusion type of denture pattern. This
suggests that Class III malocclusions have a genetic basis. The
skeletal pattern was more directly related to genetic factors.
EX: CROUZONS SYNDROME
Caused by multiple mutations in the fibroblast growth factor receptor2
gene (FGFR2). Mutation in Tyrosine kinase receptor, at Ig II – Ig III
domain Chromosome and region: 10q 253-q26

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 forwards at 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 .

5.THE POSTERIOR 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 .

DIAGNOSIS OF DENTAL, SKELETAL AND
PSEUDO CLASS III

1.Age , sex and family history of the patient.

2.Dental assessment.
Molar relationship ,careful assessment of caries, missing teeth, tooth
size discrepancies, or any mesial drift of the posterior teeth.
Incisor relationship : If a positive overjet is found with retroclined
lower incisors, a compensated class III malocclusion is suspected


3.CEPHALOMETRIC ASSESSMENT.
These measurements can be used to confirm the contributions of
maxilla and mandible as well as their dentition to the class III
dental and skeletal relationships.
Craniofacial morphogenic characteristics: in addition to determining
a patient's maxillary and mandibular relationship relative to the
cranial base, evaluation of the intermaxillary relationship,
mandibular plane angle, gonial angle, and venical facial
dimension is also helpful.
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.

CLASS III MALOCCLUSION WITH A STRONG
MANDIBULAR BASE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.

Mandibular base and ascending ramus are large
SNA angle is normal
SNB angle is larger than normal.
ANB angle is negative
Gonial angle is usually large
Articular angle is usually small.
Anteriorly positioned mandible
The tongue is postured forward and lies low in the mouth
The upper incisors are tipped labially
The lower incisors are inclined lingually
Lateral cross bites are often evident
Maxillary arch appears to be narrowed.

CEPHALOMETRIC VARIABLES TO PREDICT
FUTURE SUCCESS OF EARLY ORTHOPEDIC CL
III TREATMENT. AJO 2005 March , Peter Nagan.
64 pts who were treated with protraction face mask were
assessed in the study . the cephalograms were assessed
pre tmt and a minimum of 3 yrs after tmt . they were
divided into 2 groups successful and unsuccessful
depending on the over jet and molar relationship.11
linear and 5 angular measurements were analyzed with a
logistic regression model to identify dento skeletal
variables responsible for prediction of successful and
unsuccessful tmt outcomes.

Four significant variables were
i. Position of condyle with reference to cranial base (CO-GD)
ii. Ramal length (CO-GO)
iii. mandibular length (CO-PG)
iv. Gonial angle (Ar –GO - Me)
 Gonial angle was more in the unsuccessful group.
 Successful outcome is directly proportional to Position of
condyle with reference to cranial base and Ramal length. And
inversely proportional to mandibular length and Gonial angle.
Conclusion : Cl III growing patients with forward positioned
mandible , small ramal length , large mandibular length and
obtuse gonial angle are associated with unsatisfactory outcomes
after pubertal growth.

4 .FUNCTIONAL ASSESSMENT.
Assess the relationship of maxilla to mandible to find if a CR-CO
discrepancy exists. Anterior positioning of the mandible may
result from an abnormal tooth contact ,that forces the mandible
forward.
Patients with a forward shift of the mandible on closure may have a
class I skeletal pattern, normal facial profile and class I molar
relationship in CR but a class III skeletal and dental pattern in
CO.
Elimination of CR-CO shift should reveal whether it is a simple
class I or a compensated class III malocclusion. On the other
hand, a patient with no shift on closure has a true class III
malocclusion.

5 .PROFILE ASSESSMENT.
A profile evaluation involves an analysis of facial proportions; chin
position, midface position and vertical proportion.
► Patients with maxillary deficiency usually have a concave profile,
evidenced by the flattening of the infraorbital rim and the area
adjacent to the nose.
► By blocking out the upper and the lower lips, the chin position is
evaluated with reference to the nose, upperface and forehead. A
degree of chin prominence that would be normal for an adult
may suggest a class III skeletal pattern in a young child.
► By blocking out the lower lip and chin, the midface is evaluated.
There should be a convexity to an imaginary line extending from
the inferior border of the orbit, through the alar base of the nose
and down to the corner of the mouth. A straight or a concave
tissue contour indicates a midface deficiency.
► Vertical proportion should be checked in CO and CR. The
normal ratio of LFH to TFH is 0.55(approx). This ratio is
decreased in patientswww.indiandentalacademy.com and over closure of
with functional shift
mandible.

DIAGNOSTIC CRITERIA FOR PSEUDO CLASS III.
Rabie and Yan Gu (AJO 2000) identified the diagnostic criteria for pseudo
class III
 Majority showed no family history (72%).
That 72% showed no family history indicates that local
environmental factors could be the reason fro Pseudo class III.
The factors can be retained deciduous teeth, Odontomas, trauma
which can change the path of eruption, allowing them to erupt
palatally. This could cause premature contacts during normal path
of closure leading to anterior displacement of mandible.
 Lee showed that molar relation was class I at CR and class III at
habitual occlusion.
 Decreased midface length.
 Forward position of the mandible with normal mandibular length.
 Retroclined upper incisors with normal lower incisors.

JCO 1990 Jun Keys to Treatment Plans for Class III Patients with
Skeletal Discrepancies - DAVID W. WARREN
→ Patient History
→ Frontal and Profile Facial Appearance
→ Radiographic Analysis
→ Overbite
→ Incisor Inclination
→ Cephalometric and Skeletal Analyses
→ Musculature and TMJ
→ Patients and parents attitude

INITIAL SYMPTOMS OF CLASS III 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.
 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.

GROWTH
Growth prediction is important not only in tmt planning but also in
retention.
“IT IS ADVISABLE TO UNDERESTIMATE THE FUTURE
GROWTH OF A CLASS II AND OVER ESTIMATE THE
GROWTH OF CLASS III – so any increase in class II and less
or normal growth in class III in growth prediction will be
helpful.” NANDA


It has been believed that Class III malocclusion may be caused by
excessive growth of the mandible with respect to the maxilla
and/or cranial base. However longitudinal studies show similar
maxillary and mandibular incremental changes during the
prepubertal, pubertal, and postpubertal period when compared
to Class I subjects.
Therefore, it would be rational to assume that the skeletal
framework of Class III malocclusion must have been established
early before the prepubertal growth period.

CLASS III FACIAL GROWTH
# Pre pubertal growth period
# Pubertal growth period
# Post pubertal growth period

PREPUBERTA GROWTH PERIOD :
Mitani H. Prepubertal growth of mandibular prognathism. AJO 1981

Mitani compared growth changes between Class III and Class I
patients during the prepubertal growth period. Each set of serial
lateralcephalometric head films consisted of a 4-year series from
age 7 to 10 years.
 No significant difference was found between the two groups
with regard to the size of the maxilla.
 The maxilla, as measured from basion to Ptm was more retruded
for the Class III group.
 The incremental changes in both groups for these two
measurements were relatively similar.

 Comparison of the annual size increase in the mandible showed
that the total mandibular length of the Class III group
maintained greater values than the Class I group until the age of
10 years.
 The ANPog angle showed a significant difference in facial
convexity between the two groups. The amount of reduction in
convexity was slightly greater in the Class I than in the Class III
group with age.
In conclusion, skeletal Class III malocclusion showed an
incremental growth change similar to the Class I group during
the prepubertal period. These results suggest that the
morphologic pattern of the prognathic face associated with
mandibular excess is probably established in early life. Once
established, the annual growth increment is quite similar to that
in an individual with a normal or Class I face before puberty.

PUBERTAL GROWTH PERIOD
Bandai et al. Craniofacial growth of mandibular prognathism in
Japanese girls during pubertal growth period-Longitudinal study
from 9 to 14 years of age. AJO 2000.
reported on the craniofacial growth pattern of skeletal Class III
malocclusion during the pubertal growth period (9-14 years) in
Japanese girls . All patients exhibited a large reverse over jet and
none underwent orthodontic or growth-related orthopedic
therapy before or during the study period. The Class I group
comprised 18 Class I girls who served as control subjects. Serial
lateral cephalometric head films were used over a period of 5
years from 9 to 14 years of age.


 No significant difference between the two groups was found in
the total increase of any cephalometric measurements regarding
the maxilla .
 Although the midfacial length and upper facial height of the
Class III patients were significantly smaller than those of the
Class I, the average incremental changes in the maxillary length
showed no significant difference between the two groups.
 The mean values of the total mandibular length and the body
length of the Class III group were significantly greater . whereas
the ramus height was not.
 The average mandibular growth changes measured were 14.9
mm in the Class III group and 13.1 mm in the Class I Group.

 The principal skeletal frameworks of the two groups were
maintained during the pubertal period.
 The occlusal plane angle of Class III subjects remained
unchanged. However, in Class I subjects it showed
counterclockwise rotation during this growth period.

In conclusion, Class III malocclusion showed neither excessive
mandlibular growth nor deficient maxillary growth when
compared to Class I subjects during the pubertal growth period.
The skeletal malocclusion seems to have been established before
the pubertal growth period and maintained thereafter.
Meanwhile, the dentoalveolar disharmony is aggravated and
becomes more severe during this period shown by the difference
in occlusal plane angle and the Wits appraisal.

POST PUBERTAL GROWTH PERIOD.
Mitani H, Growth of mandibular prognathism after pubertal growth
peak. AJO 1993.
Cephalograms were taken at the age of 14 and 17 years. During the
observation period, a comparison of the maxillary measurements
showed
 That neither the size nor position of the maxilla showed any
significant difference between the two groups.
 Comparison of the mandibular measurements showed that the
total length of the Class III group were significantly greater than
those of the Class I .
 whereas the ramus height and the body length exhibited no
significant difference between the two groups.

 There was no significant difference between the two groups in
any of the changes in mandibular measurements during the time
periods studied.
 No significant difference was observed between the two groups
in the total changes in ANB angle and Wits appraisal.
 The skeletal frameworks of the two groups were maintained
during the postpubertal period.

In conclusion, the Class III group showed an incremental growth
change similar to the Class I group. The.morphologic
characteristics of the skeletal Class III malocclusion are
maintained during the postpubertal period.


SKELETAL GROWTH AND THE OCCLUSAL PLANE:
Speculations arose to the reason why Class I subjects with growth
changes similar to those of Class III subjects could maintain a
normal occlusion.
This phenomenon may be attributed to the rotational change of the
occlusal plane , in the Class I group.The occlusal plane is displaced
in a downward-forward direction with counterclockwise rotation.
Therefore, the anteroposterior relationship between the bimaxillary
apical bases evaluated on the occlusal plane is harmoniously
maintained in spite of differential jaw growth.
However, in Class III subjects the amount of maxillomandibular
differential growth is not compensated for by the counterclockwise
rotational change of the occlusal plane. The dentoalveolar
disharmony is significantly aggravated due to lack of homeostasis
of the neuromuscular system which functions to maintain a stable
intercuspal position in normal occlusion.
These results may point to the benefit of early orthodontic
intervention that may minimize the amount of apical base
discrepancy that seems to be aggravated with growth.

FACIAL GROWTH IN CL I AND CL III


JCO 1978 Sep Thomas Creekmore Class III Treatment Planning:
To diagnose and treatment planing for a young Class III patient involves
understanding the growth of the face that may occur to transform an
acceptable young face to the unacceptable prognathism of the adult.
Could the excessive growth of the mandible be prevented? Does the
establishment of a good occlusion lock the jaws together and cause
them to grow harmoniously?
"No“
Does treatment with Class III elastics inhibit mandibular growth?
Evidence indicates that Class III elastics have very limited influence on
the actual growth of the mandible or maxilla. the elastics extrude
maxillary molars as the maxillary dentition is moved forward. This
rotates the mandible and mandibular teeth down and back, trading a
Class III prognathism for a potential long face Class I open bite.
Actual shortening of the mandible or inhibition of mandibular growth is
not accomplished.

Can the excessive mandibular growth be prevented with chin
cup treatment during the growth period?
Experimental studies on monkeys indicated that mandibular growth
can be arrested with the use of a chin cup. However, the effect
of chin cup therapy on humans has proven less than impressive.
The addition of protraction therapy on the maxilla from the chin
cup offers additional corrective potential. However, in an
excessively growing mandible, chin cup and protraction therapy
would have to be continued over the entire growth period.


Can the mature skeletal framework of a patient be predicted
when the patient is 8 to 10 years of age?
Data studies using graph and the computer really gives an average
growth probability for individuals similar to that one, rather than a
true growth prediction for that particular individual.The use of
average growth increments as normal growth and implying that
growth other than average growth is abnormal is very misleading.
Lateral cephalograms of an individual taken at one-year and two-year
intervals will show that individual's growth pattern during that
time . This offers the best probability of future growth. If the
skeletal framework is changing with growth, the final relationship
of the jaws at maturity will still be difficult to predict.
If the maxilla and mandible are growing down and forward at the
same rate and the skeletal framework is not changing, then growth
would not be a detriment to treatment and the time when growth
stops becomes insignificant.

What will the case be like at maturity?
The best treatment for the patient at maturity is a major
consideration in Class III cases. Most true mandibular
prognathic patients can be treated to a better occlusal and
esthetic result with an orthodontic-surgical approach rather than
with orthodontic treatment alone.
However, the orthodontic treatment required for the orthodonticsurgical approach is usually diametrically opposite to that
required for orthodontic treatment alone. This means that a
Class III malocclusion which is treated by orthodontics alone,
but not quite successfully, which then requires surgery, would be
severely compromised. You've burned your bridges behind you.
So, for the final treatment plan for a Class III malocclusion, the
skeletal framework at maturity becomes paramount.

Recommendations For Class III Treatment Planning
Take a lateral cephalogram at the initial examination. Examine the
patient yearly taking progress head x-rays and checking for
changes in the occlusion. However, don't be misled by the
occlusion. It may look exactly the same clinically, and the face
may still look pretty good. Only accurate tracings of the
cephalograms and their superimposition will show the true
changes. Jaw relationships have to change a great deal before it
shows up in the occlusion. After two years, if the patient has
grown favorably over this period of time and can be treated
without surgery, then start treatment as indicated.
If the patient is growing unfavorably and the probability of surgery
is high, then wait. Start orthodontic treatment so that the patient
will be ready for surgery about the time growth ceases. If the
unfavorable growth does not continue long enough to require
surgery, then treat by orthodontics in one stage of treatment.
“Nothing has been lost, only delayed”

GUIDELINES AND
STRAERGIES FOR
CLASS III
MALOCCLUSION
CORRECTION

TREATMENT STRAERGY 1 – Nanda

At the initial diagnosis in the deciduous dentition and/or early
mixed dentition, patients receive a differential diagnosis and are
divided into two groups according to the extent of their threedimensional jaw disharmonies.
Long-term management is usually recommended for patients
diagnosed with mild or moderate skeletal Class III, and this
management is clearly separated into two treatment phases .
The early mixed dentition is the most desirable time for the first
phase of orthodontic treatment and the second phase of
treatment is generally applied during or after the postpubertal
period.

The treatment objectives of the first phase are:
I. To maintain good oral hygiene with the help of dental caries risk
tests.
2. To correct functional deviation of the mandible and to stabilize
the jaw position.
3. To improve the three-dimensional jaw deformity as far as
possible.
4. To correct and control the deviation of the dental midline.
5. To accomplish desirable anterior occlusion for establishing
anterior guidance in the future.
6. To establish bilateral posterior support.
7. To gain enough space for the buccal teeth.
8. To normalize and enhance orofacial functions.

The treatment objectives of the second phase of treatment are:
1.
2.
3.
4.

To achieve a balanced soft tissue profile
To establish final functional occlusion
To regulate temporomandibular joint (TMJ) and oral
functions
To prevent periodontal disease and promote oral health.


During the observation period, growth data is collected from the
patient and oral hygiene is professionally controlled. A very
important point is that the quick completion of each phase will
motivate the patient to comply through out the long term
management period.
Patients with extremely severe skeletal Class III malocclusion, in
whom orthognathic surgery is indicated, may need to skip the
first phase of treatment and their orthodontic problems cannot
be addressed until the post pubertal period. It is important to
collect growth data from these patients to establish an individual
growth database for determining the timing of onhognathic
surgery, and to professionally control oral hygiene during the
observation period.
But evidence based researches have led to many favorable
conclusions for early treatment of Class III malocclusion, in
particular gets the nod from many authors starting with Tweed,
treatment timings can be as early as 4 years of age.

EARLY TREATMENT
Ricketts (AJO 2000) has summarized
the main objectives of early treatment
lying in five concepts.
1.

UTILITY OF EARLY
TREATMENT PROTOCOLS
Angles classification

Obtaining a skeletal change (structural).
I

2.

3.

Providing the opportunity of a
functional change in the environment.
Utilization of the individual growth
expression towards the correction.

Deciduous
dentition

II

III

+

-

++

Elimination of detrimental habits .

5.

+++

Late mixed

4.

Early mixed

++

+++

+

Early
permanent

+

+++

+

Taking advantage of the forces of
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. Anteroposterior functional shift.
5. Convergent facial type.
6. Symmetric condylar growth.
7. Growing patients with expected good cooperation.
If the above factors are not present in the patient, they are listed as
negative and treatment can be delayed until growth is completed.

TWO STAGE TREATMENT OF SKELETAL CL III
MALOCCLUSION DURING EARLY PREMANENT
DENTITION. AJO oct 2005

Patients with skeletal cl III was treated during early perm dentition
in 2 phases . The 1st phase consisted of max protraction with
RPE , phase 2 consisted of an fixed appliance.
Patients was evaluated 1 yr post treatment and observed good
stability with a favorable growth pattern .Thus the authors
concluded that cl III treatment can be started in early perm
dentition with good final results.

TREATMENT STRAERGY 2 – Graber and Vig.
In patients where the malocclusion is diagnosed in the permanent
dention along with a strong skeletal descrepncy , treatment
involves comprehensive orthodontic therapy along with
extractions and surgery.
In patients in whom excessive growth is anticipated, surgery is
deferred till growth is over. But the patients have to face the
psychological problems associated with this malocclusion.
If diagnosis is made in the late descidious dentition or the mixed
dentition stage the treatment protocol is intended to addresses
the skeletal imbalance. Frankle recommended FR-3 for patients
with cl III due maxillary retrusion , other options include the
chin cup , the Delaire and Petit face masks . Though the options
produce beneficial results their long term effects are variable.

TREATMENT STRATERGIE 3


Angle 1994: Commentary: Skeletal Class III malocclusion Robert
M. Rubin.
Since many patients are not candidates for orthognathic surgery, a
conservative approach – namely dentoalveolar camouflage is
often necessary.
Dr. Sato reports on four cases of high angle Class III malocclusions
(14 -19 yrs) .Each had been treated with molar extractions.
Upper second and lower third molars were extracted in the 14year-old. In the other three patients, third molars were removed,
along with the lower first premolars in one case.
Dr. Sato states that the objectives of his treatment are to intrude the
posterior teeth and upright them, reconstruct the occlusal plane,
and reposition the mandible posteriorly.

Class III elastics were used for advancement of the upper anteriors
and retraction of the lower anteriors, while the vertical component
of the elastics assist in closing any anterior openbite that may be
present. The result is an acceptable occlusal scheme with soft
tissue changes consistent with the dropping of chin point.
Dr. Sato credits the use of a multiloop edgewise archwire (MEAW)
for intruding the molars and uprighting the posteriors. Loops are
useful in increasing the range and reducing the force and teeth
remote from the loops become the anchorage units.
Dentoalveolar camouflage for Class III occlusions is a useful
modality of treatment when surgery is not available. Dr. Sato
demonstrates excellent results, given the limitations inherent in
this approach.

COMMON TREATMENT OPTIONS
Treatment modalities include:
♫ Incline plane
♫ Modified incline plane
♫ Chin cap
♫ Protraction head gear.
♫ Fixed appliances
♫ Rapid maxillary expansion
♫ Frankel 3
♫ Reverse activator

INCLINED PLANE
Indicated in
→ Lingually inclined upper anterior teeth with an anterior crossbite
→ Well-aligned lower anterior teeth without labioversion
→ Deep-to-normal overbite
→ Normal-to-low mandibular plane angle.
Treatment effects of the incline plane are:
1. The upper anterior teeth tip labially with biting force.
2. The lower anterior teeth tip slightly lingually.


3. The mandible rotates downward and backward and the
mandibular plane angle increases during correction of the
anterior crossbite. After correction, the mandible will recover to
its original downward and forward position and the mandibular
plane angle will return to its original angulation or even less.
4. In terms of the incisor positions, most patients show lingually
inclined lower incisors; upper incisor positions exhibit greater
variation.


MODIFIED INCLINE PLANE
For patients with an anterior dental crossbite, where the upper and
lower incisors are lingually and labially inclined, respectively, and
an incline plane is contraindicated.
In such circumstances, a modified incline plane is a better choice. A
modified incline plane is a removable appliance which
structurally resembles a Hawley appliance with an incline plane
placed at the anterior portion.
The anterior incline plane portion can be trimmed away by the time
the anterior crossbite has been corrected, allowing the appliance
to serve as a retainer.

Effects of modified incline plane:
1. Improvement of the soft tissue profile
2. Labial inclination of the upper incisors
3. Lingual inclination of the lower incisors
4. Downward and backward rotation of the mandible with an
increase in the mandibular plane angle.


CHIN CUP THERAPY
Devoloped in early 1960s chin cap therapy has been widely
recognized as a method for treating developing Class III
malocclusion in young patients. A number of clinical and
experimental studies have reported that chin cap force has
several short-term orthopedic effects:
(1) Redirection of mandibular growth.
(2) Backward repositioning of the mandible.
(3) Retardation of mandibular growth.
(4) Remodeling of the mandible and the TMJ.


Long-term effects of chincap therapy on skeletal profile in mandibular
prognathism. Sugawara. AJO 98

This study involved 63 Japanese girls who showed anterior crossbite
and Class III skeletal pattern before treatment and who were
divided into three groups according to their age at the start of chin
cup therapy:
age 7 (before the pubertal growth spurt);
age 9 (at the beginning of the growth spurt), and
age 11(around the peak of the growth spurt).
The data were derived from lateral cephalometric head films taken
serially at the ages of 7,9, 11, 14, and 17 years for analysis of
intercuspal position. Basically the same type of chin cap was worn
by all patients. The force applied on the chin was oriented along a
line from the gnathion to the sella turcica and ranged from 250 to
300 g per side . Patients were instructed to wear the chin cap for at
least 14 hours daily.

SHORT TERM EFFECTS
► The skeletal profiles of patients were significantly improved and
there was retrusion of the mandible during the initial stage of
chin cap therapy for every group
► In response to the orthopedic force, the skeletal profiles of
patients who began treatment at age 7 changed more than those
who began treatment at a later age.
► In addition, patients who began treatment at age 7 showed a
more posterior positioning of the mandible than those who
entered treatment at age 11.
These results indicated that chin cap treatment is more effective
before the pubertal growth spurt. In other words, it appears that
the effects of chin cap force may be offset by rapid mandibular
growth during puberty.

LONG TERM EFFECTS
► The mandible of the group which started tmt at age 7 when
compared to untreated age 11 pts had apparently been displaced
backward during the 3 years of treatment. A significant reduction
in the gonial angle was observed during this period.
The differences in skeletal profiles at age 17 between patients who
began treatment at age 7 and at age 11, compared with the
control group of 19 year olds.
► For the group that began treatment at age 11, the position of the
mandible was relatively more forward than the group who began
treatment at age 7.
► Although a great difference was observed in the position of the
mandible at age 11, these differences decreased gradually up to
age 17 years.
► The control Class III group who received no treatment showed
the mandible in a relatively more forward position than the other
two groups.

The changes in skeletal profile, although they represent significant
improvement in the younger children, are not maintained in
most cases. This finding suggests that skeletal profiles have a
tendency to return to their original shapes, which may have been
predetermined morphogenetically ( Nakumara JJOS 1985 ,
Endo. N JJOS 1987).

It has been speculated that some skeletal rebound may occur
during or after the pubertal growth period. The significant
rebound observed in this study indicates that the hypothesis that
"the short-term effects of chin cap therapy are maintained after
complete growth" is questionable.


CONCLUSION:
► First, the chin cap appliance should be considered only as an
option to correct anterior crossbite in the first phase of treatment
for patients who are still growing.
► Second, indications for chin cap therapy should be limited to mild
to moderate skeletal Class III malocclusions that can be
camouflaged by dentoalveolar compensation in the second phase
of orthodontic treatment, even if anterior cross bite recurs after
the first phase of treatment.
► Third, chin cap therapy is contraindicated in patients with
apparent mandibular excess. For such cases, surgical orthodontic
treatment is recommended to construct stable and functional
occlusion after growth.

Effective timing for application of orthopedic force in skeletal Class
III malocclusion - AJO 1981 Oct .Sakamoto
The purpose of this study was to investigate the most effective
treatment timing with the chin cup in the treatment of the skeletal
Class lll malocclusion.
61 patients were treated with the chin cup therapy. Ages ranged from
3 to 12 years at the beginning of active treatment. The A-B
differences before and after treatment were measured to analyze
the skeletal change that occurred. Although the anterior cross-bite
was corrected in all cases, the final values of the A-B difference
were dependent upon the age the treatment was started and the
level of disharmony before treatrment.
The final values showed more improvement in the younger age group
and in the group with milder disharmony before treatment.

Cephalometric evaluation of class-III patients with chin cap
and tongue guard. Danaie SM J Indian Soc Pedod Prev
Dent. 2005 Jun;
The purpose of this study was to determine the effect of chin
cup therapy combined with an upper tongue guard in the early
treatment of class-III malocclusion on the nasomaxillary
complex and mandible.
The mean force of chin cap was determined to be 200 g on each
side for 18 h/day and the mean treatment period was 22 months.
The comparison of dependent variables revealed that skeletal
effects of chin cap therapy were more than dental and soft tissue
effects.
Changes in the upper and lower pharyngeal spaces were not
significant. A reduction of nasolabial angle occurred due to the
protrusion of upper incisors. Finally, it was shown that the
combination of chin cap and upper tongue guard could be more
effective in the early treatment.

PROTRACTION HEAD GEAR
This was reintroduced by Delaire in 1960’s after Oppenheim(1944) .
Delaire et al are credited with introducing the concept of
protraction headgear to treat Class III malocclusion . Petit later
modified Delaire’s basic concept by increasing the force
generated by the appliance, thus decreasing the overall treatment
time. Turley improved patient cooperation in wearing the
appliance by fabricating customized facemasks
The rationale for protraction headgear is to apply heavy forces on
the midface in order to advance the maxilla anteriorly. In
patients with a normally sized mandible an retrusive maxilla,
forward displacement of the maxilla is conceptually good.


PETIT
FACE MASK

DELAIRE
FACE MASK


BIOMECHANICS OF A PROTRACTION HEAD GEAR
1. Magnitude of force
2. Direction and point of force application
3. Duration of force
4. Force constancy.
Magnitude of force
Sutural morphology changes is related to age .The midpalatal suture
remains patent long after growth is complete, but it becomes
difficult to open with an RPE after the age of 15-16 years due to
the complex interlocking of sutures. Conversely, in adolescents,
midpalatal suture opening is very simple and can be accomplished
with minimal tipping of the posterior teeth. Also, for the maxilla to
advance forward in each affected suture, numerous areas of
resorption and apposition have to take place due to their tortuous
nature, quite unlike the midpalatal suture.
♦ For preadolescent patients (5-8 years) :200-250 g on each side
♦ early adolescent patients (8-11 years)
:300--450 g on each
♦ late adolescent patientswww.indiandentalacademy.com
(12 years and up): 450-600 g can be used.

Direction and point of force application
Nanda showed that by changing the line of force on the midface, the
center of rotation of the maxilla could be altered .
θ Nanda and Hickori (AO 1984) stated that the center of resistance
of the midface is probably 5-10 mm below the orbitale on the
zygomatic bone.
θ Later, Tanne (AJO 1989) reported that the center of resistance of
the maxilla was located between the root tip of the maxilla first
and second premolars.
θ 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)

By changing the point of force attachment on the mask or outer
bow of the headgear, the vertical dimension of the face can be
controlled In Class III patients with a flat mandibular plane and a
deep bite, a force below the level of the occlusal plane may be
more desirable to rotate the mandible downward and backward.
A line of force closer to the center of resistance of the midface will
deliver a translatory force and a Line of force closer to the
occlusal plane has a rotational force
The direction of the force on the chin is distal and almost in a
straight line, which can also cause a rotation of the mandible
downward and backward. In Class III, long-faced patients, a
vertical pull chin cap can be added to minimize the undesirable
forces on the chin. A chin cap is especially desirable in Class III
patients with a long vertical dimension and open bite tendency.

Duration of Force
The majority of clinical studies recommend use of a protraction
headgear anywhere from 3 to 12 months. Patient compliance
beyond 6 months is difficult. Also, the older the patient, the less
cooperative he/she will be. In some patients, if necessary after
an observation period, patients are asked to use the headgear
again for 3-4 months.
The daily wear time depends also on the age of the patient. In
preadolescent patients, 10-12 h of use per day is sufficient. In
adolescent patients, it may be necessary to increase the wear time
from 12 to 16 h per day. The latter group may also have
problems with compliance.


Force Constancy
The force is applied with elastics from the outer bow of the
headgear to the face mask. The elastic force should be
measured at the beginning to determine the desired force
level. Patients should be instructed to use fresh elastics as much
as possible.

EFFECTS OF THE FACE MASK:
1. The maxillary incisors move in the anterior direction, whereas
the mandibular incisors move 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.

5.
6.
7.

8.

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.
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.

10. A significant decrease in the upper lip sulcus depth can be
evaluated as another favorable effect of the appliance on the
soft tissue profile.
11. The lower lip moved posteriorly to lie behind the Steiner S line.
12. 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.
13. Backward repositioning of the pogonion soft, and slight
inhibition of anterior migration of the lower lip was seen.
14. 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

Facemask therapy with rigid anchorage in a patient with
maxillary hypoplasia and severe Oligodontia AJO 2003
the treatment of a 10-year-old girl with a Class III skeletal
relationship with maxillary hypoplasia and severe oligodontia.
The maxillary arch was in a complete crossbite relationship with
the mandibular arch. The treatment plan called for displacing the
maxillary complex anteriorly with a facemask. Because of the
lack of available teeth, a rigid anchorage implant was used in
combination with the remaining teeth to provide anchorage. A
titanium lag screw was placed in the maxillary alveolus. Three
weeks later, 800 g of orthodontic force was applied. A significant
anterior displacement of the nasomaxillary complex was acheived
with the facemask. At the end of treatment, a temporary
removable partial denture was placed.


Baik (AJO 1995) found significantly greater forward movement of
the maxilla (+2 mm) in protraction with RME compared to
protraction with out RME (+0.9mm). In the same study, greater
forward movement of the maxilla (+2.8mm) was found when
protraction was initiated during maxillary expansion compared
with protraction after expansion.
This study showed that better results are obtained with
protraction during expansion.


THE EFFECTS OF MAXILLARY PROTRCTION
THERAPY WITH OR WITH OUT RAPID PALATAL
EXPANSION: AN PROSPECTIVE , RANDOMISED
CLINICAL TRIAL. AJO 2005 sep Vaughn.

The study chose 46 children aged 5-10 yrs.
The results of this 5 yr clinical trial indicate that early face mask
therapy with or without RPE is effective in treating cl III
malocclusion. The measurements showed no significant
differences between and non expansion group in any measured
variable.


COMPARISON OF ORTHODONTIC AND
ORTHOPEDIC EFFECTS OF MAX PROTRACTION
HEADGEAR BETWEEN DESCIDIOUS AND EARLY
MIXED DENTITION. AJO 2004 Kajiyama.
34 subjets were treated during their descidious dentition and 29
were treated in their early mixed dentition. The mechanism of
correction of the cross bite was the same in both the groups . the
clinical effects of the appliance is greater in the descidious
dentition than the mixed dentition.


The effectiveness of protraction face mask therapy:
A meta-analysis
This study examined the effectiveness of maxillary protraction with
orthopedic appliances in Class III patients. A meta-analysis of
relevant literature was performed to determine whether a
consensus exists regarding controversial issues such as the timing
of treatment and the use of adjunctive intraoral appliances. The
statistical synthesis of changes before and after treatment in
selected cephalometric landmarks showed no distinct difference
between the palatal expansion group and nonexpansion group
except for 1 variable, upper incisor angulation, which increased
to a greater degree in the nonexpansion group.

This finding implies that more skeletal effect and less dental change
are produced in the expansion appliance group.
Examination of the effects of age revealed greater treatment
changes in the younger group. Results indicate that protraction
face mask therapy is effective in patients who are growing, but to
a lesser degree in patients who are older than 10 years of age, and
that protraction in combination with an initial period of
expansion may provide more significant skeletal effects.


LONG TERM FOLLOW UP OF EARLY TREATMENT WITH
PROTRACTION HEAD GEAR. EJO 2005 Hagg
21 cl III patients with an average age of 8 yrs were treated with the
appliance and reviewed 8 yrs later , 2/3ed of pts had had a
positive over jet . The MP opened , LAFH increased in relapse
goup . Because of unfavorable growth pattern one third of
patients who have a positive tmt response still had a potential
risk for orthognathic surgery later in life .


RAPID PALATAL EXPANSION
The placement of an acrylic splint expander opens the bite vertically
and has an intrusive force against the maxilla because of the strech
of the masticatory musculature which produces a slight forward
positioning of the maxilla . This spontaneous correction of class III
occours during the active phase of treatment ie in the first 30-40
days.
Treatment effects.
 Produces spontaneous correction of class II and class III
malocclusions.
 Correction of cross bite
 Increase in arch perimeter Correct cuspal inclinations
 Improves airway function
 Encourage more rapid tooth movement in mixed dentition patients
 Broaden the smile www.indiandentalacademy.com

Benefits of palatal expansion in Cl III
Palatal expansion has been advocated as a routine part of Class III
correction with facemask therapy. The benefits of palatal
expansion might include
♦ Expansion of a narrow maxilla
♦ correction of posterior crossbite
♦ increase in arch length
♦ bite opening,
♦ loosening or activation of circummaxillary sutures,
♦ initiating downward and forward movement of the maxillary
complex.


Haas showed that maxillary expansion always moves the maxilla
down and forward. These findings have been supported by
others.
Clinicians have advocated maxillary expansion a week before
starting facemask use, even without maxillary constriction or
crowding.
In a randomized clinical trial to examine the effects of palatal
expansion on maxillary protraction. The results of this study
showed no differences between the expansion and the non
expansion groups in any cephalometric variable, in overall
treatment time, or in the time for initial crossbite correction. The
results suggest that without other reasons for expansion, such as
maxillary width or space deficiency, expansion does not
significantly aid in Class III correction.

FRANKEL 3
Developed by Professor Rolf Fränkel .
FR-3, is used in the treatment of Class III malocclusions. 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 Fränkel, 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. Fränke 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.

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.

CLASS 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.
Used in pseudo class III malocclusion where the mand incisor
approximate prematurely in an end to end contact and the mand
slides anteriorly to complete the occlusal relationship. So the
vertical dimension is opened far enough to clear the incisal
guidance for the construction bite. This eliminates the protrusive
relation ship with the mand in centric relation.

An edge to edge bite relationship can be achieved with the post
teeth still out of contact.
Change during therapy – opening the mand to a more post
position , allowing the condyle to drop back in the fossa .at the
same time the maxillary incisor are tipped labially to provide the
proper incisor guidance . the force was eliminated in the upper
arch with max lip pads to allow the fullest extent of the growth
potential in the deficient area during the eruption of incisors .


In case of true cl iii :
If the bite can be opened and the incisal guidance established ,
adaptation of the maxillary base to the prognathic mand can be
expected to a certain degree. Correct insical guidance prevents
ant displacement of the mand during tmt . The buds of the
lower 1st premolar can be removed to assist in the compensation
with potential dentoalveolar adaptation.


Treatment Changes
 Backward positioning of the mandible.
 Significant increases of the ANB angle and the Wits values.
 The SNB and SNPog became smaller resulting in increasing
facial convexity .
 The articular angle is 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 ,
mandibular length , and ramus length .
 Dentoalveolar adaptations included labial tipping of the upper
incisors as well as lingual tipping of lower incisors .


CONCLUSION
• DIAGNOSE EARLY
• PREDICT GROWTH
• TREAT EARLY
• BE READY TO TREAT THE PATIENT
AGAIN ON A LATER DATE

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Clinical Guidelines for Treating Developing Class III Malocclusion

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Clinical Guidelines for Treating Developing Class III Malocclusion