class III Flashcards
What is the BSI definition of Class III malocclusion
Lower incisor edge occludes anterior to the cingulum plateau of the upper incisors
The overjet is reduced or reversed
What is the incidence of Class III malocclusion?
3-7% in the UK
Higher incidence in Asia
Describe the AP skeletal aetiology of Class III malocclusion
It could be due to a small maxilla, large mandible (most common), or a combination of both
What are the dental features of Class III malocclusion?
Class III incisor relationship
Class III molar relationship (not always)
Tendency to reverse overjet
Reduced overbite
Cross bites
Why is it important to treat a Class III malocclusion?
For aesthetics
Dental health reasons eg - attrition, gingival recession, mandibular displacement
Function eg - speech and mastication
What factors increase the difficulty in treating Class III malocclusion?
Larger number of teeth in anterior crossbite
Skeletal element in aetiology
Greater AP discrepancy
Presence of an AOB
What are the management options for Class III malocclusion?
Accept/monitor
Intercept early with URA
Growth modification
Camouflage
Combined orthognathic/orthodontic treatment
When is interceptive treatment suitable for Class III malocclusion?
If class III incisors have developed due to early contact on permanent incisors, or for correcting a lateral incisor crossbite if permanent canines are high above lateral roots
What is the purpose of a chin cup in orthodontics?
A functional appliance used to tip the lower incisors lingually and rotate the mandible down and back.
Not used anymore
Explain the use of protraction headgear in orthodontics
Protracts the maxilla and corrects class III malocclusion
It requires a cooperative patient to wear the headgear for approximately 14 hours a day.
Most effective when used in early mixed dentition and may be combined with rapid maxillary expansion
What are Bollard implants used for in orthodontics?
Used in late mixed and permanent dentition to provide anchorage for orthodontic treatment
They are inserted in the infrazygomatic crest and lower canine region
Mucoperiosteal flaps need to be raised for their insertion and removal
Define orthodontic camouflage
An approach in orthodontics where the underlying skeletal base relationship is accepted, and the focus is on moving the teeth to achieve a class I incisor relationship
When is orthodontic camouflage a good treatment option in a class III?
It is suitable for patients with mild to moderate class III skeletal base, average or increased overbite, and little or no dentoalveolar compensation
What is the extraction pattern for camouflage in orthodontics?
Extracting further back in the upper arch and further forward in the lower arch
The classic pattern is to extract the upper 5s and lower 4s, but the extraction pattern may vary based on dental health and individual patient need
Describe the aims of camouflage in orthodontics
Procline the upper incisors
Retrocline the lower incisors
Correct the overjet