Class III Flashcards
Define Class 3 malocclusion according to BSI ?
- Lower incisor edge occludes anterior to the cingulum of the upper incisor with reduced or reversed overjet
2 aetiological factors associated with class 3 maocclusion?
- Genetic - habsburg family
- Environmental factors - cleft lip and palate , Acromegaly
What is the aetiology of class 3 skeletal pattern?
- Small maxilla
- Large mandible
- Combination of both
Which skeletal base is mainly associated with class 3 malocclusion?
Skeletal class III
What two features in the vertical skeletal pattern , that can be complex to treat?
- Increased FMPA and anterior open bite
If a retrusive maxilla site on a wider part of mandible in class 3 , what would this lead to?
- Bilateral crossbite
4 dental features that can be associated with Class 3 malocclusion?
- Class III incisors
- Class III molars
- Tendency to reverse overjet
- Reduced overbite and anterior open bite
- Anterior and posterior crossbites
Regarding crowding , explain how can this be present in class III malocclusion?
- Maxilla often crowded
- Mandible aligned or spaces
How would you describe the upper and lower incisors in class 3?
- Proclined upper and retroclined lowers
A patient have a class 3 malocclusion, what problem is associated during closure?
tendency to displacements on closing
How can the soft tissue affect dentoalveolar compensation in class III?
- Tongue proclines upper incisors
- Lower lip retroclines lower incisors
3 reasons to treat a class 3 malocclusion?
- Aesthetics
- Dental health reasons
- Function
3 dental health concerns in class 3?
- Attrition
- Gingival recession
- Mandibular displacement
4 factors that can make class III malocclusion more difficult to treat?
- increase of number of teeth in anterior crossbite
- increase in anterioposterior discrepency
- Pressence of anterior open bite
- Facial growth
Why facial growth might be a problem in treating class III malocclusion?
- Mandibular growth continues for longer leading to worse malocclusion
5 treatment options for Class III?
- Accept
- Intercept early with URA
- Growth modification
- Camouflage
- Orthognathic surgery
4 indications of accepting class 3?
mild cases where there is no dental health concerns or aesthetic concerns
When would intercepting for Class III malocclusion be suitable?
- Class 3 incisors have developed due to early contact of permanent incisors
- For the correction of anterior crossbite in mixed dentition to encounter mandibular growth by dentoalveolar compensation
When would correcting a lateral incisor crossbite be suitable in relation to permanent canines?
If the canines are high above the lateral roots as there is a risk of resoption if the canines are in buccal position
What would the interceptive treatment with URA do in class III?
- Procline incisors over the bite using a z spring as an active component
What is the aim of growth modification in class III cases?
- reducing or redirecting mandibular growth and encouraging maxillary growth
4 functional appliances used for growth modification other than protraction headgear with rapid maxillary expansion?
- Chin up
- Reverse twin block
- Frankel III
What does chin up do?
- Lingual tipping of lower incisors and rotates the mandible down and forward
What does frankel III consist of for the correction of Class III malocclusion and what does it do?
- Shields labial to upper incisors to hold lip away
- Palatal arch to procline the upper incisors
- Lower labial bow to retrocline the lower incisors
