Class III Flashcards
What is the BSI definition of a class III malocclusion?
Lower incisor edge occludes anterior to the cingulum plateau of the upper central incisor
The overjet is reduced or reversed
What can aetiology of this malocclusion be due to?
Retrognathic maxilla
Prognathic mandible
or a combination of both
What is the vertical associations with this malocclusion?
May be associated with average, increased or reduced vertical proportions
–FMPA
–Facial height proportions
Increased FMPA and anterior open bite is more complex to treat
What are the Dental Features of a Class III malocclusion?
Class III incisor relationship
Class III molar relationship (not always)
Tendency to reverse overjet
Reduced overbite, anterior open bite may be present
Crossbites (anterior, buccal)
Alignment
–Maxilla often crowded
–Mandible often aligned or spaced
Dentoalveolar compensation
–Proclined upper incisors
–Retroclined lower incisors
Tendency for displacements on closing
What are the soft tissue involvements in aetiology?
Not usually involved in aetiology
Do not encourage dentoalveolar compensation
–Tongue proclines the upper incisors
–Lower lip retroclines lower incisors
What factors can make this malocclusion more difficult to treat?
Increased number of teeth in anterior crossbite
Skeletal element in aetiology
Increase the A-P discrepancy
Presence of anterior open bite
What impact does facial growth have on this malocclusion?
Tends to be unfavourable
Mandibular growth continues for longer
Potential for Class III to get worse
Do not do anything irreversible until growth has stopped
–Could affect future treatment if surgery is required
What are the management options for Class III occlusion?
Accept/monitor
Intercept early with URA
Growth modification
Camouflage
Combined orthognathic/orthodontic Tx
When would you accept and monitor this malocclusion?
If there are no patient concerns
No dental health concerns
–No displacements
–No attrition
Mild cases
When is interceptive treatment suitable for?
Suitable if Class III incisors have developed due to early contact on permanent incisors (i.e. mandibular displacement)
Only suitable for correcting a lateral incisor crossbite if permanent canines are high above lateral roots
–Delay if canines have dropped down into buccal position as risk of resorption to lateral incisor
When would you treat with growth modification?
Growing patient
Aimed at reducing and/or redirecting mandibular growth and encourage maxillary growth
Functional appliances
–Reverse twin block
–Frankel III
Rapid maxillary expansion (RME)
What is a Frankel III (functional appliance)?
Shields labial to upper incisors to hold lip away
Palatal arch to procline the upper incisors
Lower labial bow to retrocline the lower incisors
What are the favourable features for camouflage of this malocclusion?
Growth has stopped
Mild to moderate Class III skeletal base
Average or increased overbite
Able to reach edge to edge incisor relationship
Little or no dentoalveolar compensation
What are the aims of orthodontic camouflage?
Procline upper incisors
Retrocline lower incisors
Correct overjet
What is the GDP’s role in the treatment of this malocclusion?
Identify Class III malocclusion
Refer to hospital service or specialist practitioner
