early treatment of class III malocclusion

1. EARLY TREATMENT OF CLASS
III MALOCCLUSION
Preceptores:
Dr Shalaj Bhatnagar
Dr Meenu
Presented by;
Dr jasmine

2. 1. INTRODUCTION
2. DEFINITION
3. COMPONENTS OF CLASS III
4. CLASSIFICATION
5. EITIOLOGY
6. EARLY SIGNS AND SYMPTOMS OF CLASS III
7. RATIONALE FOR EARLY TREATMENT
8. TREATMENT TIMINGS
9. TREATMENT MODALITIES
10. FACEMASK
1. FM + RME
2. ALT RAMEC
3. MMPH
4. TTBA
5. MODIFIED TTBA
6. MAXILLARY PROTACTOR
11. CHIN CUP
12. FUNCTIONAL APPLIANCE THERAPY
1. FR III
2. ACTIVATOR
3. BIONATOR
13. TWO PIECE CORRECTOR
2

3. INTRODUCTION
• Mandibular prognathism has received the attention of dental
clinicians for several hundred years.
• In 1778, John Hunter, in writing in his book The Natural History of
the Human Teeth, stated: “It is not uncommon to find the lower
jaw projecting too far forwards, so that its fore teeth pass before
those of the upper jaw, when the mouth is shut; which is attended
with inconvenience, and disfigures the face.”

4. • The use of restraining devices to reduce mandibular prognathism
was reported in the early 1800’s
• Cellier in France and Fox, Kingsley, and Farrar in the United States
all designed appliances that resemble today’s chin cup.
• These early attempts to correct mandibular prognathism tended to
fail for one of two reasons. First, the forces generated by appliances
in the 1800’s were usually too small to have an influence on
condylar growth mechanisms. Second, treatment was often begun
after facial skeletal growth was completed, leaving the practitioner
with the task of literally “driving” the mandible backward in the
craniofacial complex.
• There was no clinical concept of growth guidance.

5. • The early failure with the chin cup appliance was one of the reasons
that orthodontists turned to intraoral appliances with intermaxillary
elastics in an attempt to correct the Class III problem. By their very
nature, however, the intraoral appliances limited the clinician to a
dental correction in a skeletal malocclusion. While it was sometimes
possible to mask the skeletal disharmony between upper and lower
jaws with a dental correction, the majority of cases that were treated
were compromised and unsuccessful.

6. • A conceptual change in the treatment of the Class III malocclusion
was offered in the late 1940’s and early 1950’ss After observation of
the gross effects of Milwaukee brace treatment on the growth and
form of the mandible, it was proposed that strong “orthopedic”
forces in the range of 400 to 800 Gm. might be used to reduce a
mandibular prognathism.
• The “orthopedic force” concept was put into actual use by directing
strong forces to the mandibular basal bone through a chin cup
mechanism. Although the design of the appliance was certainly not
new, the use of heavy force was an important modification.

7. DEFINITION
According to ANGLE class III malocclusion is defined as class III
molar relation with the mesio – buccal cusp of the maxillary first
permanent molar occluding in the inter dental space between the
mandibular first and second molars. Or lower permanent molar is
ahead of the upper first molar by a distance of the width of a
premolar or half the width of a molar.
7

8. COMPONENTS OF CLASS III
• Guyer et al found that approximately 57% of the patients with
either a normal or prognathic mandible showed a deficiency in the
maxilla.
• In a sample of Chinese patients, Wu, Peng, and Lin found the
percentage of skeletal Class III malocclusion with maxillary
retrusion to be as high as 75%.
• Contemporary studies have found Class III to be composed of pure
mandibular protrusion (19.1% to 45.2%), pure maxillary retrusion
(19.5% to 37.5%), or a combination of mandibular protrusion and
maxillary retrusion (1.5% to 30%).
• According to Ellis and McNamara 1984 and Sue et al 1987,
maxillary retrognathism is present in 62% to 67% of all class III
patients
• According to Bell et al AJO 1981 maxillary retrognathism was found
in 30–40% and Jacobson et al AJO 1974 reported that the one-quarter
of Class III malocclusions demonstrated retruded maxilla8

11. CLASSIFICATION
• Acc to Delaire, Class III malocclusion can be classified as:
1. Maxillary retrusion with mandibular retrusion
2. Orthognathic maxilla with prognathic mandible
3. Maxillary and mandibular protrusion
4. Maxillary retrusion with orthognathic mandible
5. Maxillary and mandibular retrusion
6. Maxillary retrusion with mandibular protrusion
7. Orthognathic maxilla with mandibular retrusion
8. Maxillary protrusion with mandibular orthognathia
9. Maxillary protrusion with mandibular retrusion

12. ETIOLOGY
Class III malocclusion may have a multifactorial etiology. It can be
broadly classified as:
• Genetic:
– 33 out of 40 decendants of the HABSBURG family had a class III
jaw
• Ethnic
– 3% in caucasians
– 5% african american
– 14% chinese and japanese
– (3.4% indians)
• Environmental (epigenetic):
– Large tongue
– Forward tongue position ( eg in cases of adenoids)
– Mouth breathing 12

13. • Systemic:
– Acromegaly and hemi mandibular hypertrophy:
Acromegaly is caused by anterior pituitary tumour that secretes
excessive amount of growth hormone. Here excessive mandibular
growth occurs creating a skeletal class III malocclusion.
– Teratogenic:
Teratogens causing cleft lip and palate are aspirin, cigarette smoke
(hypoxia), dilantin, 6-mercaptopurine, valium
vitamin D excess causes premature closure of sutures and might
lead to class III malocclusion.
13

14. EARLY EXTRAORAL SIGNS OF A DEVELOPING CLASS III
Early signs of true progressive mandibular prognathism can be
observed from infancy.
• Straight or concave facial profile
• Malar deficiency
• Increased lower anterior facial height
• Anatomically large lower lip length
14

15. EARLY INTRAORAL SIGNS OF A DEVELOPING CLASS III
•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.
•Flattening of the tongue as it drops away from the palatal contact and
postures forward, pressing against the lower incisors
15

16. EARLY SIGNS OF A DEVELOPING CLASS III
•Zero overjet
•Unilateral/ bilateral posterior crossbite
•Proclined maxillary incisors and retroclined mandibular incisors
•Wide lower arch and narrow maxillary arch
•Flat curve of spee
16

17. EARLY SIGNS OF A DEVELOPING CLASS III
•Habitual protraction of the mandible by the child into the protruded
functional and morphologic relationship
17

18. Pseudo class III
18
Habitual occlusion Centric relation

19. How to differentiate a dental crossbite from a
skeletal crossbite

22. Cephalometric-Cranial features
• Patients with a Class III
malocclusion exhibited a
cranial base angle (Ba-S-N)
that was more acute and
exhibited a more anteriorly
positioned articulare
compared with patients with a
Class I malocclusion.

23. Cephalometric-Maxillary features
• The horizontal "A Point"
movement is approximately
0.4 mm/yr compared with 1.0
mm/yr in patients with a
Class I malocclusion

24. Cephalometric-Mandibular features
• The ascending ramus tends to be
shorter with a steeper
mandibular plane angle.
• The gonial angle is more obtuse
in Class III malocclusions
• Typically, patients with Class III
malocclusions display
dentoalveolar compensation in
the form of proclination of the
maxillary incisors accompanied
with retroclination of the
mandibular incisors.

25. RATIONALE FOR EARLY TREATMENT
Early Timely Treatment Of Class III Malocclusion, Peter Ngan, Seminars In
Orthodontics 2005 11:140-145
• To prevent progressive irreversible soft tissue or bony changes
( wear of mandibular incisors, gingival recession etc)
• To improve skeletal discrepancies and provide a favourable
environment for future growth. Excessive mandibular growth is
often accompanied by dental compensation of the mandibular
incisors. Early orthopedic treatment improves skeletal relationships,
hence minimizing dental compensation
• To improve occlusal function (CR/CO discrepancy)
• To simplify phase 2 comprehensive trt
• To provide more pleasing esthetics thus improving the psychosocial
development of child 25

26. 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.
If the above factors are not present in the patient , they are listed as
negative and treatment can be delayed until growth is completed.
26

27. TREATMENT TIMINGS
• According to Delaire : Between 5 and 8 years
• Clinically : at the time of the initial eruption
of the maxillary central incisors
(Negan 1997 , Kapust et al 1998 , McNamara et al 2000)
• Greater degree of anterior maxillary
displacement can be obtained when
protraction facemask therapy starts in the
Primary or Early Mixed Dentition
(Baccetti – Franchi – McNamara . WJO 2001, Ngan, Semin orthod 2005)
• Melsen , 1975 : The Circummaxillary sutures
are smooth and broad before age 8 and
become more heavily interdigitated around
puberty (age 11-13)

28. • Class III treatment with maxillary expansion and protraction is
effective in the maxilla only when it is performed before the peak
( CS1 or CS2 ), whereas it is effective in the mandible during both
prepubertal and pubertal stages .
(Baccetti , Franchi and McNamara . Semin Orthod,2005 The Cervical Vertebral
Maturation( CVM) Method for Assessment of Optimal Treatment Timing in Dentofacial
Orthopedics)

29. GROWTH TREATMENT RESPONSE
VECTOR (GTRV)
GTRV ratio of an indivisual with
normal growth pattern of age 8-16
is 0.77
That is, mandible usually exceeds
the maxilla in horizontal growth
by 23% to maintain good skeletal
relation.
Class III patients with excessive
mandibular growth together with
GTRV between 0.38- 0.88 can be
successfully treated without
surgery

30. TREATMENT OPTIONS
1. For retrusive maxilla
1. Fm + Rme
2. Alt Ramec
3. Mmph
4. Ttba
5. Modified Ttba
6. Maxillary Protactor
2. For protrusive mandible- Chin Cup
3. For combination therapy- Functional Appliance
1. Fr Iii
2. Activator
3. Bionator
4. Two Piece Corrector

32. FACE MASK THERAPY
• Face-mask therapy was first described more than a century ago, and
since the late 1960s it has been used with increasing frequency for
the correction of Class III malocclusion.
• In 1944, Oppenheim reported that it is impossible to move the
mandible backward, but that it is possible to bring the maxilla
forward to compensate for mandibular overgrowth when treating
Class III
• The use of protraction facemask was 1st
done by Jean Delaire in 1875.
• It is indicated in cases of retruded or hypoplastic maxilla

33. DESIGN OF APPLIANCE:
The orthopedic facial mask consists of three
basic components. The facial mask, a
bonded maxillary splint and elastics.
The facial mask is an extra oral device
composed of a fore head pad and a chin
pad that are connected with a heavy steel
support rod. To this support rod is
connected a cross bow to which are
attached rubber bands to produce a
forward and downward elastic traction of
the maxilla. The position of the pads and
the cross bow can be adjusted simply by
loosening and tightening set screws within
each part of the appliance.

34. DESIGN OF APPLIANCE:
• Acrylic component should cover crown of
teeth leaving 1mm at the gingival margin
• Margins should have a chamfer finish to
minimise food retention
• Occlusally, thisckness should not exceed 1-2
mm
• Hooks should be placed between lateral and
canines approx 15 mm gingival to occlusal
plane.
• The bite plane may be banded or bonded,
however bonded is preferred due to ease of
use
• A Hyrax may be placed in the mid palatal
area to assist in correction of transverse
discrepancy and loosen the circum-maxillary
sutures

35. • Class III mandible is often accompanied by a
narrow, collapsed maxilla; thus RME
alongwith FM is indicated
• Patients who have lateral discrepancies that
result in either unilateral or bilateral posterior
crossbites involving several teeth are
candidates for rme.
• Cleft lip and palate patients with collapsed
maxillae .
• A Hyrax may be placed in the mid palatal
area to assist in correction of transverse
discrepancy and loosen the circum-maxillary
sutures

36. APPLIANCE MANIPULATION
• At the first appointment, the plate is
bonded.
• On the 2nd
appointment RME and traction is
started. Rate= 0.5mm/day i.e. one quarter
turn twice daily
• 7-10 days of expansion followed by
protraction
• 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)
• Face mask should be worn for 10-12 hours
daily
• The force generated by elastics should be in
the range of 350-400g/side

37. • After the patient has been accustomed to wearing the maxillary
splint, the facial mask treatment is initiated.
Sequence of elastics:
• At the time of delivery 3/8” 8 oz 2 weeks
• After 2 weeks 1/2” 14 oz
• Increased to a max of 5/16” 14 oz
Young patients (4-9) years should wear the mask on a full time basis
except during meals.
Clinically, the maxilla can be advanced 2 to 4 mm over a 12 to 15-
month period of headgear treatment.
37

38. • Class III correction
was a result of a
forward movement
of the maxilla with
no downward and
backward rotation of
the mandible.
However,
improvement of the
skeletal profile is
greater in Group
“E”, in which
devices were
anchored on
deciduous teeth

39. DIRECTION OF FORCE APPLICATION
• Staggers JCO 1992 - The orthodontist must first decide, whether to
protract with a clockwise moment on the maxilla, a
counterclockwise moment, or no moment.
• Protraction forces applied parallel to the occlusal plane, at the level
of the maxillary arch, have been shown to produce anterior rotation
and a forward movement of the maxilla.
• If the patient has normal overbite and normal vertical proportions,
protraction without any moment is indicated.
• If the patient has an anterior open bite in addition to the maxillary
deficiency, a clockwise moment should be used.
• If the patient has a deep bite, counterclockwise moment should be
chosen.

40. Biomechanics:
• According to Tanne et al and Hirato, The
centre of resistance of the maxilla is
located along 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 at or below the
centre of resistance produces counter
clock wise rotation of the maxilla. hata et
al (AJO 1987)
40

42. EFFECTS OF PROTRACTION FACEMASK
WITH RME
• Anterior displacement of maxilla
• Forward movement of maxillary dentition
• Downward and backward rotation of mandible
• Increase in LAFH
• Increase in convexity and improved profile

43. ALT-RAMEC PROTOCOL
LIOU described a unique protocol for effect maxillary
protraction. It had 3 components:
A two hinged rapid maxillary expander for greater anterior
displacement of maxilla
alternative weekly expansion and contstriction for
disarticulating the sutures (Alt-RAMEC)
Intraoral maxillary protraction springs for non compliant
patients.
The expander was alternatively activated and deactivated
for 9 weeks by 1 mm/day. This is followed by routine
protraction.

44. MODIFICATIONS OF FACEMASK
THERAPY

45. DESIGNS OF PROTRACTION FACEMASKS
• Delaire mask- 1978
– Extraoral anchorage from
forehead, chin
– Elastics attached between
hooks soldered on intraoral
arch
• Petit -1983
– Forehead and chin pads
– Force generated from distal of
maxillary molars

46. • Supraorbital protraction
appliance by Grummons
– Zygomatic areas provide more
surface for anchorage
• Protraction headgear by
Hickham 1991
– More esthetic
– Must be carefully adjusted
behind the ear

47. (Am J Orthod Dentofacial Orthop 2000;117:27-38)
•Ichikawa et al and Kawagoe et al reported that conventional
maxillary protraction headgears cause extrusion and anterior rotation
of the anchor teeth, and upward and forward rotation of the maxilla.
•As the mandible is attached to the head with temporomandibular
joint (TMJ), it is impossible to really stabilize the force system in
reverse pull headgear, which takes anchorage from the chin, because
the movement of the mandible does not allow us to apply a consistent
force.
•In growing children, force application to the chin by reverse-pull
headgear causes downward and backward rotation of mandible.
Grummons claimed that reverse headgears might have harmful effects
on the TMJ because they take support from the mandible.

50. • It consists of a removable upper splint, a lower splint, and a traction
bow. The upper splint contains the buccal hook (placed on the
maxillary first deciduous molar or premolar region) and to the
lower splint is attached a traction bow from the molar tubes.
• TTBA is delivered and patients are instructed to wear the appliance
for 12-14 hours per day. Approximately 300-500 g/side of force is
delivered from the lower traction bow to the buccal hooks of the
upper splint, at an angle of 20° below the occlusal plane to minimize
the counterclockwise rotation tendency

51. J Clin Orthod 2003;37:218-23

53. • Maxillary expander: a full
coverage acrylic cap splint type
expansion appliance that covered
all the maxillary dentition. Hooks
embedded in both the premolar
and the molar region on the
buccal sides of the expander. The
maxillary expansion appliance to
be activated everyday (0.20 mm)
• Mandibular plate: a mandibular
plate covering the posterior
mandibular dental arch was
constructed

54. • Chincap: hooks were attached on
the lateral sides of the acrylic
chincap to apply cervical forces.
• Lower face bow (1.2 mm in
diameter): it attached the acrylic
chincap to the mandibular plate. A
horizontal bar was used to apply
protraction elastics two to three cm
in front of the lips (Figure 3c,d).

55. RETENTION AFTER FACEMASK
THERAPY
• Acc to Delaire, facemask therapy should be retained by a thick
posterior bite plane for the day and a chin cap for the night

56. CHIN CUP THERAPY
• Skeletal Class III malocclusion with a relatively normal maxilla and a
moderately protrusive mandible can be treated with the use of a chin
cup.

57. Review of literature
According to graber, the early attempts with the chin cup were not
successful because of incomplete knowledge of mandibular and
facial growth.
• Armstrong applied 500 gm of force via chin cups and reported that
half of his patients showed improvement in the class III profile,
whereas none of the control, non treated patients showed any
favorable change.
• Thilander treated sixty patients with chin cups. A significant
percentage of patients did not improve since the force generated by
the chin cup in his study was only 150 to 200 gm.
• Graber, chung, and aoba reported results in patients treated with chin
cups for 12 to 14 hours each day with a force of 1.5 to 2 pounds on
each side. They showed that mandibular growth could be redirected
with a chin cup. They asserted that continuous use of the appliance
for a long period or through active growth was necessary to achieve
stable results.

58. • Chin cup therapy primarily works on the hypothesis that a force
directed through the condyles will inhibit as well as redirect the
condylar growth.

59. EFFECT ON MANDIBULAR GROWTH
The orthopedic effects of a chin cup on the mandible include
•1) redirection of mandibular growth vertically,
•2) backward repositioning (rotation) of the mandible, and
•3) remodeling of the mandible with closure of the gonial angle.
•To date, there is no agreement in the literature as to whether chin
cup therapy may or may not inhibit the growth of the mandible .
•Because of the backward mandibular rotation, control of the
vertical growth during chin cup treatment is difficult to manage.

60. EFFECT ON MAXILLARY GROWTH
• Some studies have indicated that a chin cup appliance has no effect
on the anteroposterior growth of the maxilla.
• However, Uner, Yuksel, and Ucuncu showed that early correction
of an anterior crossbite with a chin cup appliance prevents
retardation of anteroposterior maxillary growth.

61. FORCE MAGNITUDE AND DIRECTION
Chin cups are divided into two types:
•the occipital-pull chin cup- that is used for
patients with mandibular protrusion and
•the vertical-pull chin cup - that is used in
patients presenting with a steep
mandibular plane angle and excessive
anterior facial height.
•Appropriate force= 300 to 500 g per side .
•Patients are instructed to wear the
appliance 14 hr/day. Usually in the
evening and night
•The orthopedic force is usually directed
either through the condyle or below the
condyle.

63. Stability after chin cup therapy
• The stability of chin cup treatment remains unclear.
• Several investigators reported stability in horizontal maxillary and
mandibular changes associated with chin cup treatment.
(Deguchi T, Kitsugi A: Stability of changes associated with chin cup treatment,
Angle Orthod 66:139-146, 1996. 66.
• However, few studies reported a tendency to return to the original
growth pattern after the chin cup is discontinued
Uner O, Yuksel S, Ucuncu N: Long-term evaluation after chin cup treatment, Eur
J Orthod 17:135-141, 1995
• Hideo Mitani: Recovery Growth Of The Mandible After Chin Cup
Therapy: Fact Or Fiction, Semin Orthod, Sept 2007

64. Sugawara J et al: Long-term effects of chin cup therapy on
skeletal profile in mandibular prognathism, Am J Orthod
Dentofacial Orthop 98:127-133, 1990.
• Sugarwara et al published a report on the long-term effects of chin
cup therapy on three groups of Japanese girls who started chin cup
treatment at 7, 9, and 11 years. All 63 patients were followed with
serial lateral head films taken at the ages of 7, 9, 11, 14, and 17 years.
• The authors found that the skeletal profile was greatly improved
during the initial stages of chin cup therapy, but these changes were
often not maintained.
• Patients who started treatment at an earlier age had a catch-up
mandibular displacement in a forward and downward direction
before growth was completed.
• The authors concluded that chin cup therapy did not necessarily
guarantee a positive correction of the skeletal profile after
completion of growth, which suggests the need for the extended use
of the chin cup over the growth period.

65. Effects on TMJ
Clinical Evaluation Of Temporomandibular Joint Disorders In
Patients Treated With Chin Cup, Deguchi And Mimura, Angle Orthod
1998, 68(1)91-94.
“Anterior displacement of the disc is is the most commonly encountered type
of internal derangement. Posterior displacement of the condyle which can be
induced by the chin cup therapy, may cause anterior disc displacement”

66. FUNCTIONAL APPLIANCE
THERAPY

67. FRANKEL III APPLIANCE
• The Frankel III (FRIII) regulator is a
functional appliance designed to counteract
the muscle forces acting on the maxillary
complex.
Indication:
This appliance has been used during the
deciduous, mixed, and early permanent
dentition stages to correct class III
malocclusion characterized by maxillary
skeletal retrusion, and not mandibular
prognathism.
• The FRIII appliance can also be used as a
retentive device following maxillary
protraction treatment

69. Appliance design and construction
• The FR-3 (Fig. 1) is composed of wire
and acrylic. As with the FR-2
appliance,’ the base of operation is the
buccal and labial vestibule.
• There are four acrylic parts of the FR-3:
• Two vestibular shields and two upper
labial pads. The vestibular shields
extend from the depth of the
mandibular vestibule to the height of
the maxillary vestibule.
• The upper labial pads that lie in the
labial vestibule above the upper
incisors function to eliminate the
restrictive pressure of the upper lip on
the under- developed maxilla

70. • The upper labial pads of the FR-3 are
in an inverted tear-drop shape in
sagittal view. They should lie in the
height of the vestibular sulcus
parallel to the contour of the
alveolus.
• The force of the upper lip is
transferred by the upper labial pads
to the vestibular shields. Since the
vestibular shields lie in close
approximation to the mandibular
alveolus, the force of the associated
soft tissue may be transmitted
through the appliance to the
mandible.

71. • The upper labial pads are connected to
the vestibular shields by a support wire
The lower aspects of the vestibular
shield are connected by a lower labial
wire that rests against the labial surface
of the lower incisors.

72. • Upper lingual wire originates in the
vestibular shield, traverses the
interocclusal space, and rests against the
cingula of the upper incisors.
• The palatal wire originates in the
vestibular shields and traverses the palate
behind the last molar present. Thus, the
maxilla and the maxillary dentition are not
restricted in their forward movement by
the wires of the appliance.
• There are two pairs of occlusal rests in the
molar region, one of which is optional. The
purpose of this wire is to prevent the
eruption of the lower first molar as is
advocated by Harvold.

73. • There are two pairs of occlusal rests in
the molar region, one of which is
optional. The purpose of mandibular
rest is to prevent the eruption of the
lower first molar as is advocated by
Harvold.
• The maxillary occlusal rest is necessary
only in cases of anterior crossbite so that
only enough vertical opening is
achieved to allow for the correction of
the anterior crossbite. As soon as the
crossbite has been corrected, the upper
occlusal rest should be removed from
the appliance to minimize bite opening.

74. Construction bite
A horseshoe wafer of medium hard wax is used
The bite registration is taken with the patient's mandible in the most
comfortably retruded position. It is necessary to allow 1 to 2 mm of
inter occlusal space in the molar region for the construction of the
lower and, when necessary, upper occlusal rests. A wide open-bite
registration should be avoided. In cases with an anterior open bite,
only 1 mm of vertical bite-opening in the posterior region is
necessary.
74

75. Appliance activation
• After the appliance has been worn on a full-time basis for 3 or 4
months, the distance between the upper labial pads and the
underlying alveolus will decrease. Thus, activation of the appliance
is necessary to continue treatment.
• A crosscut fissure burr is used in a low- speed dental handpiece to
free the ends of the labial- pad support wires. Enough acrylic is
removed around the end of this wire to allow anterior advancement
of the wire and maxillary labial pads. The lingual surface of the
upper labial pads are kept 3 mm away from the underlying alveolus
throughout treatment.

76. 76

77. 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.
• The goal of using a class III activator was to achieve posterior
positioning of the mandible or maxillary protraction.
77

78. 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.
• The construction bite is taken by retruding the lower jaw. The upper
labial pad of the activator is intended to protract the maxilla
78

79. Treatment changes
• backward positioning of the mandible.
• significant increases of the anb angle and the wits values.
• The snb and snpog get smaller resulting in increasing facial
convexity (napog).
• The articular angle enlarges, thus augmenting the sum of the
saddle, articular, and gonial angles.
• The facial axis opens
• There are significant differences in the upper face height (n-ans),
mandibular length (co-gn), and ramus length (ar-go).
• Dentoalveolar adaptations included labial tipping of the upper
incisors as well as lingual tipping of lower incisors .

80. The shorter elastics (1/8 ” 6oz ) are attached from the mandibular
hook to the most anterior hook on the maxilla. As treatment
progresses, it is moved to the posterior hook. The longer elastic on
each side stretched from the mandibular hook to the molar hook can
be ¼”, or 3/16” depending on the comfort.
Duration:
12 hours a day in conjugation with face mask. 11 months of treatment
time and 18 -24 months of retention
Indication:
Mild skeletal class III where future surgery would not be indicated.
And used during preadolescent and adolescent growth periods
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81. CLASS III BIONATOR
(garatinni et al ajo 1998)
BALTERS BIONATOR III can be used in patients with skeletal class III
malocclusion. The use of this appliance causes some skeletal
changes through neuromuscular modifications.
Criteria
• Angle class III molar relationship;
• Edge-to edge incisor position or anterior cross bite;
• Concave profile;
• Head hyperextension posture;
• Static and dynamic class III neuromuscular attitude;
• Hypertonic upper lip;
• Low and forward tongue rest position.
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82. 82
Lower labial bow slightly in
contact with lower incisors
Palatal bar upto 1st
pm to
position the tongue

83. Construction bite:
• The construction bite is taken by gently repositioning the mandible
distally in centric relation technique.
• The mandible is positioned distally, applying as little force as
possible in order to put the condyle in centric relation, avoiding
compression in the retrodiscal pad.
• The vertical thickness of the bite, corresponding to the interocclusal
acrylic between upper and lower first molar should not exceed 3 to
4 mm, patients had to wear this appliance for at least 22 hours a
day.
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84. Results:
• Mean increase in the upper jaw length
• Advancement of point A
• Palatal and mandibular plane angles widened
• Increase of the anterior facial height
• Reduced antero posterior mandibular growth
therefore, the bionator III is helpful in class III malocclusion
treatment in growing patients with midfacial deficiency, hypo
divergent growth pattern, and reduced facial height.
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85. TWO PIECE CORRECTOR
Egnhouse JR, Jco 1997
The two-piece corrector was designed by Gerald.R.Eganhouse
• 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
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