CLASS III Flashcards
What is the definition of a Class III malocclusion according to BSI?
- lower incisor edge occludes anterior to the cingulum plateau of the upper CI
- the overjet is reduced or reversed
What is the aetiology of Class III malocclusion?
- strong genetic link
- cleft lip & palate
- acromegaly
What is the aetiology of a Class III skeletal malocclusion?
- small maxilla (maxillary hypoplasia)
- large mandible (mandibular prognathism)
- combination of both
How does a class III malocclusion usually present tranversely?
Bilateral crossbite (sometimes)
What are the dental features of a Class III malocclusion?
- Class III molar relationship (not always)
- tendency to reverse overjet
- reduced overbite
- anterior open bite (sometimes)
- crossbites (anterior/buccal)
- altered alignement
- dentoalveolar compensation
- tendency for displacements on closing
How does alignment usually present in patients with Class III malocclusion?
- maxilla often crowded
- mandible often aligned or spaced)
What can dentoalveolar compensation present as in class III malocclusion?
- proclined upper incisors
- retroclined lower incisors
Why do we treat a class III malocclusion?
- aesthetics
- dental health (risk of attrition, gingival recession or mandibular displacement)
- function (speech & mastication issues)
What are some factors that can make treatment of Class III malocclusion more difficult?
- > number of teeth in anterior crossbite
- skeletal element in aetiology
- > in the A-P discrepancy
- presence of AOB
Why should you wait until growth has stopped before treating Class III malocclusion?
- mandibular growth continues for longer
- potential for class III to get worse
What does the onset of the pubertal growth spirt coincide with?
spurt in jaw growth
What are the management options for Class III malocclusions?
- accept/monitor
- intercept early with URA
- growth modification
- camouflage
- combined orthognathic/orthodontic tx
When would you accept/monitor a class III occlusion?
- no concerns
- no dental health indications
- mild cases
When would you use interceptive treatment for a class III occlusion?
- suitable if class III incisors have developed due to early contact on permanent incisors
- use of URAs
What functional appliances are used as growth modification for Class III malocclusion?
- chin cup
- reverse twin block
- Frankel III
What features are on a Frankel III?
- shields labial to upper incisors to hold lip away
- palatal arch to procline the upper incisors
- lower labial bow to retrocline the lower incisors
How is protractor headgear used for treatment of class III malocclusion?
- 14 hours/day protraction facemask
- 400g per side
- best results when used in early mixed dentition
- patient must be cooperative
What is meant by orthodontic camouflage of a Class III malocclusion?
Accept underlying skeletal base relationship:
- aim for class I incisors
What are some favourable features for camouflage treatment of a class III malocclusion?
- growth stopped
- mild to moderate Class III skeletal base ANB not <0
- average or increased overbite
- able to reach edge to edge incisor relationship
- little or not dentoalveolar compensation
How can orthodontic camouflage be achieved in a class III malocclusion patient?
- extract further back in upper arch
- extracted further forward in the lower arch
What is the aim of orthodontic camouflage in treatment of Class III malocclusion?
- procline upper incisors
- retrocline lower incisors
- corect overjet
Who is involved in the multidicisplinary team for orthognathic surgery?
- orthodontist
- maxillofacial surgeon
- technician
- psychologist
what is involved in presurgical orthodontics before orthognathic treatment?
Level, align, co-ordinate & decompensate
what is the role of a GDP in class III malocclusion?
- identify class III malocclusion
- refer to hospital service or specialist practitioner
(potential URA treatment)
