2. Class III malocclusion
A malocclusion that is:
Very easy to identify but is often
Difficult to treat
3. This condition represents a pre-normalcy where
the mandible is in a mesial relation to the
upper arch
According to Angle Class III molar relationship
refers to a condition where the mesio-buccal
cusp of the upper first mol or occludes between
the mandibular first and second molars.
Although this definition represents a typical
Class III relationship, the lower molar can be in
a mesial relationship to a varying degree.
4. ETIOLOGY
True Class III malocclusion
exhibits
(Underlying skeletal imbalance)
usually inherited
have a very strong GENETIC basis.
Habitual forward positioning
of the mandible (Psudo Class III)
Occlusal prematurities
Enlarged adenoids
5. Causes of an reversed overjet
cause Aetiology
Skeletal pattern (Class III) - Long mandible
- Forward placement of glenoid fossa
positioning the mandible more
anteriorly
- Short and/or retrognathic maxilla
- Short anterior cranial base
Anterior mandibular displacement on closure - Premature contact
Retained primary upper incisors These may deflect the eruption path of
their successors palatally into crossbite
Restrained of maxillary growth - Found in repaired cleft lip & palate &
attributed to the effect of postsurgical
scar tissue
6. cause Aetiology
Skeletal pattern (Class III) - Long mandible
- Forward placement of glenoid fossa positioning the mandible
more anteriorly
- Short and/or retrognathic maxilla
- Short anterior cranial base
Causes of an reversed overjet
7. cause Aetiology
Anterior mandibular displacement on closure - Premature contact
Causes of an reversed overjet
8. Retained primary upper incisors These may deflect the eruption path of
their successors palatally into crossbite
9. Causes of an reversed overjet
cause Aetiology
Skeletal pattern (Class III) - Long mandible
- Forward placement of glenoid fossa
positioning the mandible more
anteriorly
- Short and/or retrognathic maxilla
- Short anterior cranial base
Anterior mandibular displacement on closure - Premature contact
Retained primary upper incisors These may deflect the eruption path of
their successors palatally into crossbite
Restrained of maxillary growth - Found in repaired cleft lip & palate &
attributed to the effect of postsurgical
scar tissue
12. The reasons for early treatment :
1. To correct the anterior displacement of the mandible
before the ERUPTION of the CANINES and PREMOLARS
so that
they can be guided into a Class 1 Relationship
13. The reasons for early treatment :
2. To provide space for the eruption of
the BUCCAL segments
as a result of
Proclination of the upper incisor
14. The reasons for early treatment :
3. to provide a normal environment for the growth of the maxilla
by Elimination the Anterior Crossbite
15. The reasons for early treatment : To this should be added
4. Psychological benefits
resulting from improved dental
and facial appearance.
18. What is Orthopedic appliance ?
Orthopedic appliance that allows orthodontists
to control growth of facial structures
Various designs
Used with growing patients
19. Class II Correction
Class III Correction
(excess growth of maxilla/
(deficient growth of
deficient growth of mandible) maxilla/excess growth
– Cervical Headgear of maxilla)
– High Pull Headgear
– Reverse Pull Headgear
– Chin Cup
– Combination
20. Interception during growth
The following are some of the growth modulation procedures that can be
carried out:
a. Frankel III, a mayofunctional c. Chin cup with high pull headgear is
used to intercept Class III
appliance can be used during
malocclusion due to mandibular
growth to intercept Class III due
prognathism.
to maxillary skeletal retrusion.
d. Severe Class III malocclusions that
b. Reverse activator. are a result of maxillary retrusion
can be treated by reverse
headgear or face mask to protract
the maxilla
21. Orthopaedic change in class 3 malocclusions
The possible effects of orthopaedic treatment in class 3 malocclusions.
1. Stimulation of maxillary
growth ( 50% ) as measured
by SNA.
2. Inhibition of mandibular
projection ( 90% ) as
measured by SNB.
The annual change expected was
calculated as 1.8° in ANB.
22. Mandibular skeletal appliances (CHINCAPS)
The use of CHINCAPS was a popular treatment modality
Based on the belief that
The mandible was
the major contributor to the
class 3 malocclusion.
23. Mandibular skeletal appliances (CHINCAPS)
Chincap therapy was effective in
Reducing Before PUBERTY
Mandibular Prognathism
But this advantage was then lost.
24. Chin Cup Therapy
1. Mild skeletal problem (PSEUDO CLASS III)
2. Short Vertical Face height because causes
longer facial height
3. Requires normally positioned or
proclined lower incisors because it will
retrocline incisors
25. Effects of Chin Cup Therapy
1 - Lingual tipping of the mandibular incisors – leading to crowding
Change in direction
2 - Change in direction of
mandibular growth
(Downward and backward)
May lead to skeletal open bites in
patients with initially increased lower
anterior facial height
26. Maxillary skeletal appliances ( Reverse Pull Headgear)
(Require a Very Cooperative Patient)
Used to apply
an anteriorly directed force, via ELASTICS,
on the maxillary teeth and maxilla
This technique useful in
Class III associated with a CLP
anomaly & hypodontia where
forward movement of the buccal
segment teeth to close space is
desirable.
27. Reverse Pull Headgear / face mask
Side effects include
downward and backward
rotation of the mandible
Lingual tipping of the
mandibular incisors
28. Timing of Any Orthopaedic Treatment
Females
– 8.5-10.5 years old
– In general, if menses have
occurred, most of the rapid
growth has already occurred and
headgear will not be very
helpful
Males
– 9.5-11.5 years old
30. Treatment planning in class III malocclusions
Many factors should be considered before planning the treatment:
1. The patients opinion regarding their occlusion and facial appearance.
2. The severity of the skeletal pattern.
3. The expected pattern of future growth.
4. Dento-alveolar compensation.
5. The degree of crowding.
31. Regarding their occlusion & facial appearance
1. PATIENT'S OPINION (needs to be approached with some tact).
32. 2. Severity of skeletal pattern:
both
- Anteroposteriorly &
- Vertically
(The major determinant of
the difficulty &
prognosis of orthodontic treatment).
34. 3. Expected pattern of further growth:
both
anteroposteriorly &
vertically
Children with increased
vertical proportions
The average growth
tend to
often continue to exhibit
Worsening a vertical pattern of
the relation between growth
the arches.
which reduce the overbite.
35. Treatment planning in Class III malocclusions:
In Class III malocclusions
Normal or increased overbite
is an advantage
as a vertical overlap of the
upper incisors with the lower
incisors post-treatment is vital
for stability.
36. 4. If the patient can achieve an edge-to-edge incisor position :
Increase the prognosis of correction the incisor relationship.
37. 5. Dento-alveolar compensation:
orthodontic treatment aimed to
increase it,
if it already present, trying to
increase it further may not be
an aesthetic or stable treatment option.
38. 6. Degree of crowding:
crowding occurs more frequently, and to a greater degree, in the upper arch.
Extractions should be resisted
as it worsening the incisor
relationship.
Where upper extractions are necessary, it is advisable
to extract at least as forwards in the lower arch.
39. 1. Expansion the arch Anteriorlly to correct
anterior X-bite.
2. Expansion the arch Buccoligually to correct
buccal segment X-bite.
3. Distal movement of the upper buccal segment with
Headgear
To relief upper arch crowding
40. To relief upper arch crowding
Additional space can be gained by
Expansion the arch Anteriorly
to correct the incisor relationship
and/or
41. To relief upper arch crowding
Additional space can be gained by
1. Expansion the arch
Buccoligually to correct
buccal segment X-bite.
42. Expansion of the upper arch
to correct a X-bite
will have the effect of reducing
overbite, which is a disadvantage
in Class III
(overbite reduction occurs because expansion of the upper arch is
achieved primarily by tilting the upper premolars & molars
buccaly) palatal cusps swinging and ‘propping open’ the occlusion.
43. Expansion of the upper arch
If upper arch expansion is
indicated & the overbite is
reduced
Fixed Appliances should be used to limit tilting of upper
molars buccally during expansion.
45. To relief upper arch crowding
Distal movement of the upper
buccal segment with Headgear to
gain space for alignment is
inadvisable (restraining growth
of maxilla).
46. To relief upper arch crowding
Mild to Moderate Crowding
space can be made by a
Combination of
1. forward movement of the
incisors &
2. distal movement of the
remaining buccal segment teeth.
47. Functional appliances
can be useful in mixed dentition
where a combination of
Proclination of the upper
incisors together with
Retroclination of the lower
incisors is required.
49. Orthodontic correction
Can be achieved by either
(i)- Proclination of the upper
incisors alone or
(ii)- Retroclination of the lower
incisors with or without
proclination of the upper incisors.
50. Orthodontic correction
This determined by:
– Skeletal pattern &
– Amount of overbite present
before treatment
51. Orthodontic correction
– Amount of overbite present
before treatment
Proclination of the Overbite
upper incisors
Retroclination of the Overbite
lower incisors
53. Treatment options:
1. Accepting the incisor
relationship:
(a) - in mild cases where the overbite
is minimal;
(b) - if the remainder of the family
have a similar facial appearance.
54. 2. Proclination of the upper labial segment:
Best carried out in the mixed dentition
when the canines are
Unerupted and High Above the roots of the upper lateral incisors.
55. Proclination of the upper labial segment:
Correction of the incisors relationship by proclination of the upper incisors only
can be considered in cases with the following features:
a) A Class I or mild Class III skeletal
pattern.
b) The upper incisors are not already
proclined.
c) An adequate overbite will be
present at the end of treatment to
retain the corrected position of the
upper incisors.
56. 3. Retroclination of the lower labial segment with or without proclination
of the upper labial segment:
In those cases with
a mild to moderate Class III skeletal
pattern, or
where there us reduce overbite,
A combination of retroclination of the
lower incisors and proclination of the
upper incisors will achieve correction of
incisors relationship.
57. To advance the upper incisors & retrocline the lower incisors
Removable appliances
Functional appliances
Fixed appliances: tooth movements are accomplished more efficiently
58. To advance the upper incisors & retrocline the lower incisors
Removable appliances Early mixed dentition.
Functional appliances Permanent dentition.
Fixed appliances: tooth movements are accomplished more efficiently
59. For retroclination the lower labial segment
Space is required in the lower arch
&
Extractions are required
unless the arch is spaced
naturally.
60. Role of extractions
Extraction of the lower deciduous canines
may
Allow the lower incisors to drop
lingually and
Assist in the correction of the reverse
overjet.
61. Role of extractions
Class III malocclusion characterized
by upper arch length deficiency and
anterior cross bite can be treated by
extracting the lower first premolars
followed by fixed mechanotherapy.
In case of arch length deficiency
involving both the arches, the first
premolars should be extracted in
both the upper and lower arches.
62. 3. Retroclination of the lower labial segment with or without proclination of
the upper labial segment:
Use of a ROUND archwire in the
lower arch & a RECTANGULAR arch
in the upper arch help to correct the
incisors relationship.
Intermaxillary Class III elastic
traction from the lower labial
segment to the upper molars can also
be used to help move the upper arch
forwards & the lower arch
backwards
(care required to avoid extrusion of the
molars which will reduce overbite.
63. Surgery:
Sever skeletal pattern and/or
reduced overbite or
an anterior openbite
(Precludes يعوقorthodontic alone)
64. Surgery:
ANB
Surgery is almost required
if the value for
ANB ⁰ < – 4°
&
The inclination of the lower incisors
to the mandiblar plane < 83°.
65. Treatment of severe Class III after growth
Class III
Maxillary deficiency
Maxillary advancement procedures
such as
Le Fort I osteotomy.
66. Treatment of severe Class III after growth
Class III
Mandibular prognathism
Mandibular set back procedures
Body ostectomy
