Class 2/1

Question 1

What is the definition of class 2/1? And what is the aetiology?

Answer 1

the lower incisor edge occludes posterior to the cingulum plataeu of the upper incisors and the upper incisors are wither at a normal inclination or proclined and over jet is increased

Skeletal
Soft tissue
Dento alveolar : crowding
Local factors: digit habit

Question 2

Is the jet reduced, average or increased in class 2/1?

Answer 2

it is increased, the normal value is 2-3mm

Question 3

What is the incidence of class 2/1 incisor relationship? And why do they need treatment?

Answer 3

22% (2–30%)

Aesthetics
Function considerations
Dental health consideration
Reduced the risk of trauma to uppers

Question 4

what is the skeletal aetiology of class 2/1?

Answer 4

skeletal: large maxilla and small mandible or posterior articulation of the mandible within the gelnoid fossa, vertical and lateral relationships are normal, sometime retrognathic mandible

Question 5

What type of profile do class 2/1 usually have?

Answer 5

convex

Question 6

What are the soft tissue aetiology for class 2/1?

Answer 6

lip morpholgy: short upper lip and decreased tone
Lip competance
Anterior oral seal: created by tongue to lower lip or lower lip to palate
tongue

Question 7

where should the lower lip be relative to the tips of the upper incisors?

Answer 7

the lower lip should cover the incisal third

Question 8

When is it more likely to be seen where an anterior oral seal is created by the tongue being placed against the lower lip?

Answer 8

when there is an increase in vertical proportion

Question 9

What is a rare cause of class 2/1?

Answer 9

where the lower lip is so muscular that it retroclines the lower incisors

Question 10

What are the treatment options for class 2/1?

Answer 10

camofluage
growth modifcation
correct underlying skeletal abnormaility

Question 11

When would you treat a CLass 2/1 with camofluage?

Answer 11

when there is a mild skeletal discreapancy and you can tip the upper incisors back to reduce the overjet

Question 12

WHat would you use for growh modifcation?

Answer 12

functional appliances

Question 13

How effective is growth modifcation for class 2/1?

Answer 13

mitchell

not very effective, the changes acheived from the use of funcional appliances were not maintained long term and usuing functional appiances protracts the treatment

Question 14

What are the treatment methods for treating class 2/1?

Answer 14

upper removable appliances
functional appliances
fixed appliances
Orthognathic

Question 15

When would you use an URA?

Answer 15

overjet <8mm
proclined upper labial segment
3/3 are mesially angulated
class 1/mild class 2 skeletal pattern

may need to carry out extrcations

Question 16

When would you use a functional appliance in class 2/1?

Answer 16

one stage treatment

two stage followed by fixed appliances

Question 17

When would you use one stage functional appliances?

Answer 17

when the overjet >8mm
well aligned arches
class 2 molar
pubertal growth

Question 18

When would you use a a two stage functional appliances? (functional appliances followed by FA)

Answer 18

when the overjet is>8mm
crowding
class 2 molar

Question 19

When would we use fixed appliances alone?

Answer 19

multiple tooth movements
bodily movement of upper labial segment
correction of rotations
space closure
arch co-ordination

Question 20

When would we consider orthognathic treatment for people with class 2/1?

Answer 20

when there is a severe class 2 skeletal patten and tooth movement and growth modification alone would not correct the malocclusion

Question 21

People with severe class 2 skeletal pattern how would you use growth modifications?

Answer 21

restrain the maxilla using head gear

promote mandibular growth with functional

Question 22

An overjet of 6mm has a trauma incidence of how much?

Answer 22

22%

Question 23

An overjet of 9mm has a trauma incidence of how much?

Answer 23

24%

Question 24

An overjet of >9mm has a trauma incidence of how much?

Answer 24

44%

Question 25

What is the aetiology of class 2/1?

Answer 25

Skeletal
Soft tissue
Dento alveolar
Associated habits

Question 26

What is the dento alveolar cause of class 2/1?

Answer 26

The upper teeth are so crowded that they push the upper incisors out of the arch and the teeth are then pushed labially

Question 27

What is the stability of the overjet dependant upon?

Answer 27

Soft tissues

Question 28

What type of growth of the mandible is modern advantageous in class 2/1 cases?

Answer 28

Forward growth

Question 29

Why is backward growth in a class 2 less favourable?

Answer 29

1. AP discrepancy will worsen with growth

2. Increase in lower facial height will reduce likelihood do competent lips at the end of treatment