Class 3 malocclusions /certified fixed orthodontic courses by Indian dental academy

Angle’s class III

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INDIAN DENTAL ACADEMY
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Introduction


Class III malocclusion represents a pre
normalcy where the mandible is in a
mesial relation to upper arch



In sagittal plane this occlusion is called
Pre normal occlusion



According to Lischer’s modification of
Angle’s classification this malocclusion is
known as Mesio occlusion

According to Angle a Class III molar
relationship refers to a condition where
the mesio buccal cusp of permanent
maxillary first molar occluding in the
interdental space between the mandibular
first and second molars.


Etiology
Heredity
 Age linked
 Functional factor and soft tissue
- Tongue posture
- Enlarged tonsils and naso respiratory
difficulties
- Excessive epi pharyngeal lymphoid
tissue



Occlusal forces created by abnormal
eruption
 Pre mature loss of deciduous molars
 Lack of eruption of maxillary buccal
segments
 Cleft lip and palate
 Compulsive habits of protruding the
mandible
 Trauma to the mid face during growth
phase



Frequency


1-3%



Depends on ethnic geographic factors and
age


Initial symptoms of Class III


1. Eruption of the maxillary central
incisors in a lingual relationship and
mandibular incisors in a forward position
with no over jet




2. Development of an incisal cross bite
during the eruption of lateral incisor into
a normal relation ship




3. Full incisor cross bite some weeks later




4. Flattening of the tongue as it drops
away from the palatal contact and
posture forwards pressing against the
lower incisors.



5. Habitual protraction of the mandible by
the child into the protruded functional
and morphological relationship.

In complete deciduous dentition

Mandibular anteriors are ventral to
maxillary one.Limited overbite is present.

Mandibular arch is too far ventral
to maxillary one.Good transverse
Mandibular deciduous molars occlude
relation
too far mesially to maxillary.Terminal
Anterior crossbite
plane –large mesial step

In intertransitional period

Mandibular and maxillary incisors erupted.
Incisal edges of maxillary incisors contact the
lingual surface of mandibular

Ventral position of mandibular dental
arch in relation to maxillary.
Reverse overjet in incisor- canine
region.
The individual position of the teeth is in
Mandibular first permanent molar occludes too
accordance with the deviation in
far mesially to the maxillary one.
contacts and crossing over the
Contact surface between them is small.
occlusion in canine region.

In permanent dentition

Mandibular permanent canine are position
labially to the maxillary lateral incisors.

Ventral position of the mandibular dental arch
in relation to maxillary.
All posterior teeth occlude too
Reversed over jet in anterior region
much mesially by one premolar
The position of individual teeth is www.indiandentalacademy.com
adapted to
crown width.
the deviations in occlusal relations.

Evaluation of Class III


Deciduous dentition
-Scissors bite with the facets of wear on
specific teeth
-Spaces between the teeth
-Tooth bud in the mandible
-Under development of the maxilla


Mixed dentition
- Cross bite of individual teeth
- Minimal over jet
- Lingually inclined lower incisors to achieve
a normal over jet



Classification
Angle’s classification
1. True Class III- Skeletal



2. Pseudo or Postural or Habitual class III
-forward movement of the mandible
during jaw closure


3. Class III subdivision – Class III molar
relation on one side and Class I relation
on other side


Cephalometric Classification


1. Class III malocclusion caused by dento
alveolar mal relationship




2. Class III malocclusion with long
mandibular base




3. Class III malocclusion with an under
developed maxilla




4. Class III malocclusion with a
combination of under developed maxilla
and prominent mandible; horizontal and
vertical growth pattern.




5.Class III skeletal malocclusion with
tooth guided or pseudo force bite


Clinical Features


Extra oral features



-Straight to concave
profile



Anterior facial
divergence

-Long face (increased
lower facial height)
 Prominent chin
 Steep mandibular plane
 Mandible appears to be
well developed
 (obtuse gonial angle)
 Lower lip full and
pendulous
 Maxillary vertical height
deficient



Intra oral features
 Class III molar and canine relationship




Edge to edge incisors relationship or
anterior cross bite


Upper arch is frequently
narrow and short and
lower arch is broad
 Upper teeth crowded
and mandibular arch is
often spaced
 Vertical growers –
anterior open bite
 Presence of occlusal pre
maturities resulting in
habitual forward
positioning of the
mandible



Diagnostic consideration
Clinical examination
 Functional analysis
 Radiographic examination
 Cephalometric analysis
 Study model analysis
 Soft tissue examination



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Class 3 malocclusions /certified fixed orthodontic courses by Indian dental academy

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