Class 3

Question 0

What is the prevelence of class 3 malocclusion?

Answer 0

3%

Question 1

What is a class 3 incisor relationship?

Answer 1

Lower edge of the incisor occluded anterior to the clingulum plateau of the upper incisors

Question 2

What are the broad causes of class 3?

Answer 2

Skeletal
Soft tissue
Occlusal and dento alveolar
Facial growth

Question 3

What are the skeletal causes of class 3?

Answer 3

AP: usually class 3: large mandible, small maxilla or both and short anterior cranial base

Vertical: can be average increased or decreases

Transverse: narrow upper arch, broad lower arch

Question 4

What are the soft tissue causes of class 3?

Answer 4

Not usually a cause but leads to dento alveolar compensation

Question 5

What is the UIA in a class 3 and how does this compare to the average size?

Answer 5

Class 3: 118

Normal: 109

Question 6

What is the LIA in a class 3 and how does this compare to the average size?

Answer 6

Class 3: 89/79

Normal 93

Question 7

What are the occlusal features of class 3? And what can its lead to?

Answer 7

Anterior cross bite due to class 3 incisor 
Posterior cross bite due to arch width discrepancy and also the larger parts of the mandible occlude with the smaller parts of the maxilla 

Wear on labial upper incisors and recession on lower
Crowded upper arch and spaced or aligned lower

Can lead to mandib displacement

Question 8

T/F
It is not possible to compensate for adverse growth in class 3 compared to class 2?

Answer 8

T

Question 9

Where is there more bone, behind the upper incisors or in front?

Answer 9

Behind

Question 10

Why do we treat class 3 later than earlier?

Answer 10

It is not possible to predict growth for that individual and must assume that their growth will be average. Best to not treat until they stop growing

Question 11

In which case do you treat early?

Answer 11

Mild class 3 with mandibular displacement

Question 12

Why do you treat mild class 3 early?

Answer 12

May cause damage to the periodontium and it is quick and easy to treat and thus if the later growth is unfavourable then not much has been lost

Question 13

How do you treat a mild class 3?

Answer 13

Procline upper incisors with URA

Question 14

How do you treat a moderate class 3?

Answer 14

Procline uppers and retroclined lowers with FA

Question 15

How do you treat a severe class 3?

Answer 15

Orthognathic

Question 16

What factors would indicate treatment is likely to be successful?

Answer 16

NALM

Normal or increased overbite
Anterior mandib displacement
Little or no DA compensation
Mild class 3 pattern

Question 17

With Moderate class 3 when would you treat them?

Answer 17

Treat them later rather than earlier to avoid uncertainty from future growth

Question 18

What does a forward ,anterior displacement suggest?

Answer 18

1. It is a tooth related cause

2. Some of the correction will arise from the condyles dropping back into the fossa

Question 19

When do you treat severe class 3?

Answer 19

Once growth stopped since needs surgery

Question 20

What would be the purse of ortho in severe class 3?

Answer 20

Decompensate the incisors and co ordinate arches

Question 21

What surgery would be done to the mandible ?

Answer 21

Bilateral Sagittal split

Question 22

What surgery would be done to the maxilla ?

Answer 22

Le Fort 1 osteotomy