Class II Divison 1 Orthodontics Dentistry by Cezar E.
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Transcript of Class II Divison 1 Orthodontics Dentistry by Cezar E.
Orthodontics
Class II division 1
By: Cezar Edward
Introduction
‘the lower incisor edges lie posterior to the
cingulum plateau of the upper incisors, there
is an increase in overjet and the upper
central incisors are usually proclined.
Aetiology
Skeletal pattern
Soft tissues
Dental factors
Habits
Skeletal pattern
A Class II division 1 incisor relationship is usually
associated with a Class II skeletal pattern,
commonly due to a retrognathic mandible
However, proclination of the upper incisors and/or
retroclination of the lower incisors by a habit or the
soft tissues can result in an increased overjet on a
Class I, or even a Class III skeletal pattern.
Soft tissues
the patient will try to achieve an anterior oral seal in one of
the following ways:
• circumoral muscular activity to achieve a lip-to-lip seal
• the mandible is postured forwards to allow the lips to meet
at rest;
• the lower lip is drawn up behind the upper incisors
• the tongue is placed forwards between the incisors to
contact the lower lip, often contributing to the development
of an incomplete overbite;
• a combination of these.
Dental factors
A Class II division 1 incisor relationship may occur
in the presence of crowding or spacing. Where the
arches are crowded, lack of space may
result in the upper incisors being crowded out of
the arch labially and thus to exacerbation of the
overjet. Conversely, crowding of the lower
labial segment may help to compensate for an
increased overjet in the same manner.
Habits
A persistent digit-sucking habit
The severity of the effects produced will
depend upon the duration and the
intensity”Force” and Position ”# of digits”
• proclination of the upper incisors;
• retroclination of the lower labial segment;
• an incomplete overbite or a localized anterior open bite;
• narrowing of the upper arch thought to be mediated by the tongue
taking up a lower position in the mouth and the negative pressure
generated during sucking of the digit.
It will make :
Occlusal features
The overjet is increased, and the upper
incisors may be proclined
The overbite is often increased, but may be
incomplete as a result of a forward adaptive
tongue position, a habit, or increased
vertical skeletal proportions.
Assessment of and treatment planning in
Class II division 1 malocclusions
Factors influencing a definative treatment plan
The patient’s age
The difficulty of treatment
The likely stability of overjet reduction
The patient’s facial appearance
Practical treatment planning
The likely stability of overjet
reduction
The soft tissues are the major determinant
of stability following overjet reduction.
Ideally, at the end of overjet reduction the lower lip should act on the
incisal one-third of the upper incisors and be able to achieve a competent
lip seal. If this is not possible, consideration should be given as to whether
treatment is necessary (if alignment is acceptable and the overjet is not
signifi cantly increased) and, if indicated, whether prolonged retention or
even surgery is required
Following overjet reduction, this
patient’s lips will probably be
competent. Therefore the prognosis
for stability of the corrected incisor
relationship is good
Class II division 1 malocclusion with a poor prognosis for the
stability of overjet reduction owing to the markedly incompetent lips
and increased vertical proportions. Prolonged retention would be
advisable.
The patient’s facial appearance
The decision as to whether extractions are required will depend
upon the presence of crowding,
Class II division 1 malocclusions are commonly
associated with increased overbite, which must be reduced
before the overjet can be reduced. Overbite reduction requires
space.
It is fair to say that headgear is associated with compliance problems;
to try and eliminate this a number of ‘non-compliance’ appliances have
been developed which aim to produce distal movement of the molars.
These can be classified as follows:
• Intramaxillary: anchorage derived from within the arch – anterior
teeth, premolars, coverage of palatal vault.
• Intermaxillary: anchorage derived from opposing arch. In Class II
cases this is the lower arch.
• Absolute anchorage: anchorage derived from implants (TADs).
Early treatmenttreatment for Class II division 1 malocclusions is best
deferred until the late mixed/early permanent dentition
where the transition from the functional to the fixed
appliance can be made straightaway without having to wait
for teeth to erupt; space can be gained for relief of
crowding and reduction of the overjet by the extraction of
permanent teeth (if indicated), and soft tissue maturity
increases thelikelihood of lip competence.
In the interim a custom-made mouthguard can be worn for
sports. However, if the upper incisors are thought to be at
particular risk of trauma during the mixed dentition,
treatment with a functional appliance can be considered
Management of an increased overjet
associated with a moderate
to severe Class II skeletal pattern
(1) Growth modification
(2) Orthodontic camouflage
(3) Surgical correction
by attempting restraint of maxillary growth,
by encouraging mandibular growth, or by a combination of the two
( Fig. 9.14 ). Headgear can be used to try and restrain growth of the
maxilla horizontally and/or vertically, depending upon the direction
of force relative to the maxilla. Functional appliances appear
to produce limited restraint of maxillary growth whilst encouraging
mandibular growth.
(1) Growth modification
Fig. 9.14 Patient treated by growth
modification. Because correction required a
combination of restraint of vertical and forward
growth of the maxilla and encouragement of
forward growth of the mandible, a functional
appliance with high-pull headgear was used:
(a, b) pre-treatment aged 12 years; (c, d)
following a year of retention aged 15 years.
A B
CD
Recent work has suggested that predictors
of a successful outcome are
• Mandibular retrusion (Pogonion to Nasion
perpendicular > 7 mm)
• The angle between the ramus and the
lower border of the mandible
(Condylion-Gonion-Menton) is <123°
using fixed appliances to achieve bodily
retraction of the upper incisors ( Fig. 9.15 ). The severity of the case that
can be approached in this way is limited by the availability of cortical
bone palatal to the upper incisors and by the patient’s facial profile.
(2) Orthodontic camouflage
Patient with Class II division 1 malocclusion on a moderately severe Class II
skeletal pattern treated by orthodontic camouflage in which
both upper first premolars were extracted to gain space for overjet reduction and
fixed appliances were used for bodily retraction of the upper incisors:
(a–c) pre-treatment (note the upright upper incisors); (d–f) post-retention.
Unfortunately, ‘gummy’ smiles associated with increased vertical
skeletal proportions and/or a short upper lip will often worsen as the
incisors are retracted. Therefore active steps should be taken to
manage this problem. Milder cases are best managed by either the use
of highpull headgear to either a functional type of appliance or a
removable appliance, for example, a Maxillary Intrusion Splint to try
and restrain maxillary vertical development while the rest of the
face grows. In severe cases of vertical maxillary excess or where there
is an excessive amount of upper incisor show in an adult patient,
surgery to impact the maxilla is advisable.
Retention
Relapse encompasses the return following
treatment of the original features of the
malocclusion as well as long-term growth
and soft tissue changes. so retention must
be discussed with, and planned, for every
patient.
Key points
• Class II/1 malocclusions are commonly associated with an underlying
Class II skeletal pattern with a retrusive mandible
• For cases with an underlying Class II skeletal pattern the options are
growth modification, camouflage or surgery
• Research evidence would suggest that growth modification produces
limited skeletal effects over and above normal growth
• Research indicates that early (two-phase) treatment does not have any
benefits over conventional treatment
Reference