Download Class II malocclusion

D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Inter-arch problems
 Saggital problems:
Class II malocclusion: the lower dental arch and/or skeletal base is in distal
relation to the upper dental arch (skeletal base), The mesio-buccal cusp of the upper
first permanent molar occludes anterior to the buccal groove of the lower first
permanent molar
Class III malocclusion: the lower dental arch and/or skeletal base is in mesial
relation to the upper dental arch (skeletal base), The mesio-buccal cusp of the upper
first permanent molar occludes posterior to the buccal groove of the lower first
permanent molar
Class II
Class III
 Vertical problems:
Open bite: inherited, developmental or acquired malocclusion. There is no vertical
overlap between maxillary and mandibular anterior teeth (anterior open bite), or no
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
vertical contact is exhibited between maxillary and mandibular posterior teeth
(posterior open bite).
There are two types of open bite:
Dental open bite: a localized open bite that involves only a few teeth due to a digit
sucking habit or other local factors.
Skeletal open bite: involve a larger number of teeth which is caused by
divergence of the skeletal mandibular and/or maxillary planes leading to increased
facial height as in case of posterior rotational growth of the mandible.
Dental open bite
Skeletal open bite
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Deep bite: the vertical overlap between maxillary and mandibular anterior teeth
is increased beyond the normal range (more than 4mm), it is frequently associated
with decreased vertical facial dimension.
There are three types of deep bite:
1. None traumatic deep bite: in which the deep bite is still teeth to teeth
relationship.
2. Traumatic deep bite: in which the deep bite associated with the impingement
of the mandibular incisors in the mucosa palatal to the maxillary incisors
commonly is seen in malocclusion with extremely deep bite as in sever class II
malocclusion.
3. Bi-traumatic deep bite: usually seen in some cases of class II div. 2
malocclusion with minimal over jet, the retroclined maxillary incisors may
impinge in the keratinized tissue labial to the mandibular incisors causing
gingival recession at the same time there is a trauma to the palatal mucosa
caused by lower incisors.
Deep bite
Traumatic deep bite
Bi-traumatic deepbite
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
• Transverse problems:
Cross bite:
An abnormal relationship or discrepancy of one or more teeth in dental
arch to one or more teeth of opposing arch in buccolingual or labiolingual direction. A
cross bite could be dental or skeletal in etiology.
Anterior cross bite: if one or more of the lower incisors are in front of the upper
incisors, this condition is called reverse overjet.
Anterior cross bite
Buccal cross bite: the buccal cusps of the mandibular posterior teeth occlude buccally
to the buccal cusps of the maxillary posterior teeth. It could be:
Unilateral cross bite: affect only one side of the dental arch. It could be
either:
1. True unilateral cross bite: caused by an asymmetry present in the dental arch
and usually does not associated with deviation of the mandible on closure
.
2. False unilateral cross bite: caused by narrowing of the maxilla or widening of
the mandible leading to cusp to cusp relation, this situation is uncomfortable to
the patient so the patient tries to get maximum intercuspation by deviation of
the mandible to one side leading to the development of unilateral cross bite.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
False unilateral cross bite
Bilateral cross bite: affected both sides of dental arch and caused by severe
maxillary collapse and/or mandibular widening, there is no mandibular deviation
during closure.
Bilateral cross bite
Lingual cross bite(Scissor bite): the buccal cusps of the mandibular posterior
teeth occlude lingually to the palatal cusps of the maxillary posterior teeth without
contact of their occlusal surfaces and exhibit a vertical overlap.
Lingual cross bite
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Scissor bite: is present when one or more of the adjacent posterior teeth are either
positioned completely buccally or completely lingually to the antagonist teeth without
contact of their occlusal surfaces and exhibit a vertical overlap.
Midline shift (deviation): occur when the upper and lower dental midline are
not coincide. A midline shift of 0.5 could be considered as a normal
The midline shift could be:
Associated with mandibular deviation during closure due to presence of premature
contact.
Not associated with mandibular deviation during closure as in case of unilateral
missing of tooth or crowding.
Midline shift may be due to shift of the upper midline only or shift of the lower
midline only or sometimes both of them.
It’s important to differentiate between midline shift of dentition and face. We may see
one of them or sometimes both of them.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Midline shift of the face mostly caused by abnormal skeletal factor (unilateral
hyperplasia of the mandible or deviation of nose).
Midline shift of dentition mostly associated with unilateral (extraction, congenital
missing or impaction) of a tooth.
Classification of malocclusion
Classification of dental arch relations:
 Angle classification
Classification of malocclusion was introduced by E.H. Angle, based on the anteroposterior relationship of the maxillary and mandibular permanent first molar.
Angle’s classification:
Class I malocclusion (Neutrocclusion): The mesio-buccal cusp of the upper
first permanent molar occludes in the buccal groove between the buccal and
middle cusps of the lower first permanent molar.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
The term class I malocclusion should be distinguished from class I normal occlusion,
the term “class I” is sometimes used incorrectly as a synonym for normal occlusion,
although in reality, it only signifies a sagittal (antero-posterior) relationship of
maxillary and mandibular permanent 1st molars.
In class I malocclusion, the upper& lower permanent 1st molars in normal or correct
antero-posterior relationship but there are other problems within dental arch like:
spacing, crowding, impaction, rotation, deep bite, increased over jet etc..
Class II malocclusion (Distocclusion)(Postnormal occlusion): The
mesio-buccal cusp of the upper first permanent molar occludes anterior to the
buccal groove of the lower first permanent molar. The severity of class II
malocclusion is determined by fraction of cusp or unit. For example class II
malocclusion half cusp or full cusp.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Mesiobuccal cusp
Anterior buccal groove
Class II malocclusion can be divided into:
 Class II malocclusion, Division 1: class II malocclusion with proclined
maxillary incisors resulting in an increased over jet with incomplete over bite or
mostly deep bite.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
 Class II malocclusion, Division 2: class II malocclusion typically with the
maxillary incisors tipped palatally, a short anterior lower face height, deep bite and
normal or decreasing over jet.
The types of class II div.2
Type A: the four maxillary permanent incisors are tipped palatally.
Type B: the maxillary central incisors are tipped palatally and the maxillary lateral
incisors are tipped labially.
Class III malocclusion (Mesiocclusion)( Prenormal occlusion): The
mesio-buccal cusp of the upper first permanent molar occludes posterior to the
buccal groove of the lower first permanent molar. The severity of class III
malocclusion is determined by fraction of cusp or unit. For example class III
malocclusion half cusp or full cusp.
Mesiobuccal cusp
Anterior buccal groove
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Pseudo class ІІІ (FALSE or postural): This is not a true class ІІІ malocclusion
but its presentation is similar. Here the mandible shifts anteriorly during final stages of
closure due to the presence of premature contact of the incisors or the canines.
Pseudo class ІІІ
Angle classification
 Angle’s system of classification is the most traditional and oldest system still in
used, practical and easy to comprehend, widely used for teaching purpose.
 Angle’s system of classification based on the permanent 1st molar. So, when the
permanent 1st molar is missing we should shift to another classification which is
canine classification and if there is impacted canine or missing we shift to incisor
classification.
 Angle’s system of classification describes only the antero-posterior (sagittal)
relationship for permanent first molar and does not take in to account many other
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
important relationships in the anteroposterior (overjet, canine relationship), in
transverse relationship (crossbite) and vertical relationship (open &deep bite).
 Angle’s system of classification does not identify intra-arch problems such as
spacing, crowding, rotation, missing or impacted teeth.
 Angle’s system of classification describes only the dental antero-posterior
(sagittal) relationship which is not necessarily the same as the underlying sagittal
skeletal relationship.
 Sometimes, the Angle’s classification is not symmetrical on both sides for
example, we can find class II molar relationship on left side and class I molar
relationship on right side, this is called CLASS II SUB-DIVISION
 Condition in which class III molar relationship is present only on one side with
normal relation on the other side, this is called CLASS III SUB-DIVISION
Canine classification
Class I canine relationship: when the tip of upper canine located in the
embrasure area between lower canine and 1st premolar in occlusion. (the mesial
slope of upper canine coincide with distal slope of lower canine) in occlusion.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Class II canine relationship: When the mesial slope of upper canine is
ahead of the distal slope of lower canine in occlusion.
Class III canine relationship: When the mesial slope of the upper canine
lies behind the distal slope of the lower canine in occlusion.
Incisor classification
The incisor relationship does not always match the buccal segment (Angle classification).
Since much of the orthodontic treatment is focused on the correction of incisor malrelationship, it is helpful to have a classification of incisor relationship.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
Class I incisor relationship: the lower incisor edges occlude with or lie
immediately below the cingulum plateau (middle part of the palatal surface) of
the upper central incisors.
Class II incisor relationship: The lower incisor edges lie posterior to the
cingulum plateau of the upper incisors.
There are two divisions of class II incisor relationship:
DIVISION 1:
The upper central incisors are proclined or of average inclination & there is an
increase in overjet.
DIVISION 2:
The upper central incisors are retroclined. The overjet is usually minimal or
may be increased.
Class III incisor relationship: The lower incisor edges lies anterior to the
cingulum plateau of the upper incisors. The overjet is reduced or reversed.
Classification of dental base (skeletal bases) relations
The terms skeletal class I, II, III are commonly applied to describe dental base
relations in the antero-posterior direction when the jaws are closed and the teeth in full
occlusion.
D.U.C
Faculity of Dentistry
4th Grade
Orthodontic
Dr. Ghufran Dhari
Lec.2
 Skeletal class I: The jaws are in their ideal antero-posterior relationship in
occlusion.
 Skeletal class II: The lower jaw in occlusion is positioned further back in relation
to the upper jaw. This could be due to: a small mandible, a large maxilla or a
combination of both.
 Skeletal class III: The lower jaw in occlusion is positioned further forward in
relation to the upper jaw. This could be due to: a large mandible, a small maxilla or
a combination of both.
Skeletal cl I
Skeletal cl II
Skeletal cl III