First permanent molar in orthodontics

Question 1

When is the best time and position of teeth to extract 6’s from ortho prespective?

Answer 1

Age 8.5-10 year old
Class I occlusion
Mild incisor crowding
All permanent teeth present

Question 2

What are the implications for loss of 6’s?

Answer 2

Disturbs occlusion - if lower, the upper may overerupt, 7 may move laterally
Orthodontic treatment prolonged
Treatment may be more difficult
Patients unsuitable

Question 3

Why is orthodontic treatment prolonged?

Answer 3

Patients: high caries rate, doubtful co-operation and motivation for treatment 
More teeth need to be moved
Acrylic button (nance button) attached to 7's to stop them drifting forwards

Question 4

What are the are problems with 1st permanent molar?

Answer 4

Geographical inequality

Socio-economical group inequality - higher in groups IV and V

Question 5

What are the factors influencing success that need to consider with extraction of 1st permanent molars

Answer 5

Degree of crowding/hypodontia
Upper or lower
Timing of extraction
Balancing and compensating extractions

Question 6

How will whether 6 is upper or lower affect the success?

Answer 6

They have different eruption paths

Lower 6 is the problem, upper 6 rarely has problems

Question 7

What are the problems with the removal of the lower 6’s?

Answer 7

7’s:
Tilts mesially
Rotates mesio-lingually - doesn’t give food contact with upper
Leans lingually
Over-eruption
Upper 7’s have more vertical point of eruption, lowr 7’s have more mesial path of eruption

Question 8

What is a positive with overeruption of 6’s?

Answer 8

stop any mesial movement of lower 7’s

if there is occlusal contact then will be ok

Question 9

When should 6’s be removed straight away without waiting for ortho treatment?

Answer 9

Unrestorable 6 symptomatic
Ortho treatment unlikely e.g. caries
7 fully through, so will not move much

Question 10

What happens if the lower 6 is extracted too late?

Answer 10

minimal space closure

Question 11

Lower 6’s extracted too early?

Answer 11

lower 5 can become ectopic or drift distally

Question 12

When may you retain the 1st permanent molars for ortho later?

Answer 12

High caries risk in all 6’s

Question 13

When is the ideal time to take out 6’s? What can this result in?

Answer 13

when have bifurcation of 7’s just forming
&’s mesially tipped so that now contacting the 5’s
7’s replace the 6’s

Question 14

What are other favourable factors for when to extract 6’s?

Answer 14

Lower 5 engaged in bifucation of E
Lower 7 mesially angulated
Lower 8 present

Question 15

What is compensating extractions?

Answer 15

Extraction in the opposite arch in the same side - may want to consider compensating 6’s

Question 16

What is balancing extractions?

Answer 16

Extraction in the same arch on the opposite side

Dont need to balance 6’s, too far back to affect centrline

Question 17

How does extraction of 6’s affect 7’s?

Answer 17

Tilts mesially
rotated mesio-lingually
Leans lingually
upper 6 may over-erupt

Question 18

What is the problem with alveolar necking and orthodontics?

Answer 18

Lots of cortical bone in the extraction site so when heals makes it more difficult to close orthodontically
Less likely to get spontaneous space closure

Question 19

What can extraction of 6’s prevent happening?

Answer 19

Prevents impacted 8’s

More space created posteriorly

Question 20

If class II malocclusion what may you consider with extraction of 6’s

Answer 20

Extract 6's early  and correct class II with functional appliance
or 
maintain and incorporate into ortho treatment plan as dont know how much they will grow

Question 21

If class III malocclusion what may you consider with extraction of 6’s

Answer 21

Seek orthodontic opinion as treatment may be delayed to assess mandibular growth
Timing of extraction can alter if orthognathic surgery planned