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
What is this?
Reverse twin block
What is this?
Protraction headgear
What are the disadvantages of protraction headgear? and when does it give the best results?
- needs excellent cooperation
- needs to be worn for 14 hours per day
- 8-10 years in early mixed dentition
What are those?
Bollard implants in infrazygomatic crest and lower canine region
When would you use bollard implants?
- in later mixed or permanent dentition
5 favourable features for camouflage of class 3 malocclusion?
- Growth has stopeed
- Mild to moderate class II skeletal base ( ANB not less than 0)
- Average or increased overbite
- Edge to edge incisor relationship
- Little dentoalveolar compensation
What would be the extraction pattern for the orthodontic camouflage to treat class III malocclusion ?
- XLA further back in upper
- XLA further forward in lowers
- Usually upper 5s and lower 4s
- Howerever, dental health indicates the extraction pattern
What are the aims of camouflage in Class III malocclusion?
- Procline upper incisors
- Retrocline lower incisors
- Correct the overjet
What is orthognathic surgery?
- Surgical manipulation of the mandible or the maxilla or both to produce optimal dento-facial aesthetics and function
3 indications of orthognathic surgery in Class III skeletal pattern?
- Growth has stopped
- Moderate or severe skeletal discrepancy
- Aesthetic and functional concerns
4 professionals in the MDT of orthognathic treatment?
- Orthodontist
- Maxillofacial surgeon
- Technician
- Psychologist
How long would presurgical ortho treatment last?
18 months to align the arch
How long would post surgical ortho treatment last?
6 months for stability
