1) Class III malocclusions involve the lower incisors positioned anteriorly to the upper incisors. The main causes are skeletal (increased mandibular length or reduced maxillary length), soft tissue, and dental factors like upper arch crowding. 2) Treatment planning considers the severity, growth potential, dentoalveolar compensation, and overbite. Options include accepting the incisor relationship, early orthopaedic treatment like face masks, orthodontic camouflage involving tooth movement, or orthognathic surgery. 3) Early orthopaedic treatment aims to protract the maxilla using face masks or bone-anchored protraction. Orthodontic cam

1. Orthodontics
Class III
By Cezar Edward

2. contents
11.1 Aetiology 138
11.1.1 Skeletal pattern 138
11.1.2 Soft tissues 138
11.1.3 Dental factors 138
11.2 Occlusal features 139
11.3 Treatment planning in Class III
malocclusions 139
11.4 Treatment options 140
11.4.1 Accepting the incisor relationship 140
11.4.2 Early orthopaedic treatment 140
11.4.3 Orthodontic camoufl age 143
11.4.4 Surgery 145

3. Introduction
Class III incisor relationship includes those
malocclusions where the lower incisor edge
occludes anterior to the cingulum plateau of
the upper incisors.
-Increase vertical dimension
-Decrease overbite
-Decrease overjet

4. Aetiology
 Skeletal pattern
 Soft tissues
 Dental factors

5. Skeletal pattern
 most important factor
Class III malocclusions exhibit the following:
• increased mandibular length;
• a more anteriorly placed glenoid fossa so that the condylar head is
positioned more anteriorly leading to mandibular prognathism;
• reduced maxillary length;
• a more retruded position of the maxilla leading to maxillary retrusion.
Patient with mandibular prognathism Patient with maxillary retrognathia

6. Soft tissues
*Do not play a major aetiological role.
*The dento-alveolar compensation occurs in Class III
malocclusions because an anterior oral seal can frequently
be achieved by upper to lower lip contact.
This has the effect of moulding the upper and lower labial
segments towards each other.
The main exception occurs in patients with increased
vertical skeletal
proportions where the lips are more likely to be
incompetent and an anterior oral seal is often
accomplished by tongue to lower lip contact.

7. Dental factors
Often associated with a narrow upper arch
and a broad lower arch, with the result that
crowding is seen more commonly,
and to a greater degree, in the upper arch
than in the lower.
Frequently, the lower arch is well aligned or
even spaced.

8. Occlusal features
Fig. 11.3 Diagram illustrating the path of
closure in a Class III
malocclusion from an edge-to-edge incisor
relationship into maximal
occlusion. Although the mandible is
displaced forwards from the initial
contact of the incisors to achieve maximal
interdigitation, the condylar
head is not displaced out of the glenoid
fossa.
Fig. 11.4 A Class III malocclusion with a
narrow crowded upper arch
and a broader less crowded lower arch
with associated buccal crossbite.
Class III malocclusions often exhibit
dentoalveolar compensation with the
upper incisors proclined and the lower
incisors retroclined, which reduces the
severity of the incisor relationship

9. Treatment planning in Class III
malocclusions
A number of factors should be considered before planning treatment.
1. Patient’s concerns and motivation towards treatment
2.The severity of the skeletal pattern, both anteroposteriorly and vertically,
should be assessed.
3.The amount and expected pattern of future growth -When evaluating the
likely direction and extent of facial growth, the patient’s age, sex, facial pattern and
family history of Class III malocclusions should be taken into consideration
4.If the patient can achieve an edge-to-edge incisor contact and then
displaces forwards into a reverse overjet, this increases the prognosis for
correction of the incisor relationship.
5.The degree of crowding in each arch
6.Amount of dento-alveolar compensation present
7.Overbite

10. Using headgear for distal movement of the upper buccal segments to
gain space for alignment is inadvisable in Class III malocclusions as this
will have the effect of restraining growth of the maxilla.
Functional appliances are less widely used in Class III malocclusions
because it is difficult for patients to posture posteriorly to
achieve an active working bite.
headgear can be used for children “to reduce the growth of the mandible

11. Treatment options
 Accepting the incisor relationship
 Early orthopaedic treatment
 Orthodontic camouflage
 Surgery

12. Accepting the incisor
relationship
Mild Class III case where it was decided to accept the incisor
relationship and direct treatment towards alignment of the
arches only

13. Early orthopaedic treatment
Protraction face-mask used to advance the maxilla. The forces
applied in this technique are in the region of 400 g per side and a co-
operative patient is necessary to achieve the 14 hours per day
wear required
A recent multi-centre randomized controlled trial in patients under the
age of 10 years showed a success rate of 70 per cent in terms of
achieving a positive overjet over a followup period of 15 months.

15. Bone anchored maxillary protraction (known as BAMP). Screws or
mini-plates are used in the posterior maxilla and anterior mandible
for Class III elastics. There is some evidence to show that a greater
degree of maxillary advancement is achieved than with face-mask
therapy alone.
A combination of these two techniques – elastics are run between
skeletal anchorage in the maxilla and a face mask.
Chin-cup – this has the eff ect of rotating the mandible downwards
and backwards with a reduction of overbite so is largely historic.

16. Orthodontic camouflage
Correction of an anterior crossbite in a Class I or mild Class III skeletal
pattern can be undertaken in the mixed dentition when the unerupted
permanent canines are high above the roots of the upper lateral incisors
.Extraction of the lower deciduous canines at the same time may
allow the lower labial segment to move lingually slightly.
Later in the mixed dentition when the developing canines drop
down into a buccal position relative to the lateral incisor root there may be
a risk of resorption if the incisors are moved labially. In this situation correction
is then best deferred until the permanent canines have erupted.
Fig. 11.10 Diagram to show how proclination of the
upper incisors results in a reduction of overbite.
Fig. 11.11 Diagram to show how retroclination of the
lower incisors results in an increase of overbite

17. Fig. 11.13 Class III intermaxillary traction.

18. Remember!!
 In class III we need space in lower arch to
make retroclination

19. Surgery
It has been suggested that surgery is almost
always required if the value for the ANB angle is
below –4° and the inclination of the lower incisors
to the mandibular plane is less than 80°
planning and commencement of a combined
orthodontic and orthognathic approach is best
delayed until age 15 years in girls and age 16
years in boys.

20. Key points
• Growth is often unfavourable in Class III malocclusions
• If orthopaedic treatment might be an option then it is important
to refer the patient to a specialist before 10 years of age

21. Reference