Class III Flashcards

1
Q

Define Class 3 malocclusion according to BSI ?

A
  • Lower incisor edge occludes anterior to the cingulum of the upper incisor with reduced or reversed overjet
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1
Q

2 aetiological factors associated with class 3 maocclusion?

A
  • Genetic - habsburg family
  • Environmental factors - cleft lip and palate , Acromegaly
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2
Q

What is the aetiology of class 3 skeletal pattern?

A
  • Small maxilla
  • Large mandible
  • Combination of both
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3
Q

Which skeletal base is mainly associated with class 3 malocclusion?

A

Skeletal class III

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4
Q

What two features in the vertical skeletal pattern , that can be complex to treat?

A
  • Increased FMPA and anterior open bite
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5
Q

If a retrusive maxilla site on a wider part of mandible in class 3 , what would this lead to?

A
  • Bilateral crossbite
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6
Q

4 dental features that can be associated with Class 3 malocclusion?

A
  • Class III incisors
  • Class III molars
  • Tendency to reverse overjet
  • Reduced overbite and anterior open bite
  • Anterior and posterior crossbites
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7
Q

Regarding crowding , explain how can this be present in class III malocclusion?

A
  • Maxilla often crowded
  • Mandible aligned or spaces
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8
Q

How would you describe the upper and lower incisors in class 3?

A
  • Proclined upper and retroclined lowers
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9
Q

A patient have a class 3 malocclusion, what problem is associated during closure?

A

tendency to displacements on closing

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10
Q

How can the soft tissue affect dentoalveolar compensation in class III?

A
  • Tongue proclines upper incisors
  • Lower lip retroclines lower incisors
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11
Q

3 reasons to treat a class 3 malocclusion?

A
  • Aesthetics
  • Dental health reasons
  • Function
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12
Q

3 dental health concerns in class 3?

A
  • Attrition
  • Gingival recession
  • Mandibular displacement
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13
Q

4 factors that can make class III malocclusion more difficult to treat?

A
  • increase of number of teeth in anterior crossbite
  • increase in anterioposterior discrepency
  • Pressence of anterior open bite
  • Facial growth
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14
Q

Why facial growth might be a problem in treating class III malocclusion?

A
  • Mandibular growth continues for longer leading to worse malocclusion
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15
Q

5 treatment options for Class III?

A
  • Accept
  • Intercept early with URA
  • Growth modification
  • Camouflage
  • Orthognathic surgery
16
Q

4 indications of accepting class 3?

A

mild cases where there is no dental health concerns or aesthetic concerns

17
Q

When would intercepting for Class III malocclusion be suitable?

A
  • 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
18
Q

When would correcting a lateral incisor crossbite be suitable in relation to permanent canines?

A

If the canines are high above the lateral roots as there is a risk of resoption if the canines are in buccal position

19
Q

What would the interceptive treatment with URA do in class III?

A
  • Procline incisors over the bite using a z spring as an active component
20
Q

What is the aim of growth modification in class III cases?

A
  • reducing or redirecting mandibular growth and encouraging maxillary growth
21
Q

4 functional appliances used for growth modification other than protraction headgear with rapid maxillary expansion?

A
  • Chin up
  • Reverse twin block
  • Frankel III
22
Q

What does chin up do?

A
  • Lingual tipping of lower incisors and rotates the mandible down and forward
23
Q

What does frankel III consist of for the correction of Class III malocclusion and what does it do?

A
  • Shields labial to upper incisors to hold lip away
  • Palatal arch to procline the upper incisors
  • Lower labial bow to retrocline the lower incisors
24
Q

What is this?

A

Reverse twin block

25
Q

What is this?

A

Protraction headgear

26
Q

What are the disadvantages of protraction headgear? and when does it give the best results?

A
  • needs excellent cooperation
  • needs to be worn for 14 hours per day
  • 8-10 years in early mixed dentition
27
Q

What are those?

A

Bollard implants in infrazygomatic crest and lower canine region

28
Q

When would you use bollard implants?

A
  • in later mixed or permanent dentition
29
Q

5 favourable features for camouflage of class 3 malocclusion?

A
  • 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
30
Q

What would be the extraction pattern for the orthodontic camouflage to treat class III malocclusion ?

A
  • XLA further back in upper
  • XLA further forward in lowers
  • Usually upper 5s and lower 4s
  • Howerever, dental health indicates the extraction pattern
31
Q

What are the aims of camouflage in Class III malocclusion?

A
  • Procline upper incisors
  • Retrocline lower incisors
  • Correct the overjet
32
Q

What is orthognathic surgery?

A
  • Surgical manipulation of the mandible or the maxilla or both to produce optimal dento-facial aesthetics and function
33
Q

3 indications of orthognathic surgery in Class III skeletal pattern?

A
  • Growth has stopped
  • Moderate or severe skeletal discrepancy
  • Aesthetic and functional concerns
34
Q

4 professionals in the MDT of orthognathic treatment?

A
  • Orthodontist
  • Maxillofacial surgeon
  • Technician
  • Psychologist
35
Q

How long would presurgical ortho treatment last?

A

18 months to align the arch

36
Q

How long would post surgical ortho treatment last?

A

6 months for stability

37
Q
A