First Permanent Molar in Ortho

Question 1

Characteristics of the ideal pt to lose the 1st permanent molar?

Answer 1

Age 8 1/2 - 10yrs old
Class I
Mild incisor crowding
All permanent teeth present

Question 2

Implications of loss of the 1st permanent molars?

Answer 2

Disturbs occlusion - especially in lower arch extraction
Ortho treatment prolonged e.g if pt has high caries rate and doubtful cooperation
Treatment may be more difficult e.g. if carious/restored = remove 6s
Pts unsuitable

Question 3

When extracting 6s, what factors influence success?

Answer 3

Degree of crowding - avoid if no crowding
Upper or lower (upper 6s rarely a problem)
Timing of extraction - immediate XLA (unrestorable) or retain it and have ortho later
Balancing or compensating extractions

Question 4

Why are lower 6s a problem?

Answer 4

As the lower 7 after 6 is extracted:
Tilts mesially
Rotates mesio-lingually = occlusal problems
Leans lingually
Over eruption of upper 6 = stops any mesial movement of lower 7

Question 5

What occurs when the 6 is extracted too late or too early?

Answer 5

Too late = Minimal spontaneous space closure

Too early = 5 moves distally or can become ectopic

Question 6

When is the ideal time to extract lower 6s to achieve spontaneous space closure?

Answer 6

When bifurcation of lower 7 visible
Other favourable factors:
- Lower 5 engaged in bifurfaction of E
- Lower 7 mesially angulated
- Lower 8 present

Question 7

What to consider when thinking about extracting the lower 6s?

Answer 7

Will the pt need ortho treatment:
- Yes = refer
Will the affected tooth require a crown or RCT in future?
- Yes = consider extraction or extraction of the other 1st molars

Question 8

What is balancing?

Answer 8

Extraction in the same arch on the opposite side

Question 9

What is compensating?

Answer 9

Extraction in the opposite arch on the same side

Question 10

Balance or compensate 1st molar extraction?

Answer 10

Do not balance 6s

Consider extraction of upper 6 if extracting lower 6

Question 11

What is alveolar necking?

Answer 11

Cortical bone left = harder = more difficult to close the space

Question 12

What is an advantage of XLA of 6s?

Answer 12

Less likely to get impacted lower 8s

Question 13

How to extract 6s with class II pts?

Answer 13

Extract 1st molars early
Correct class II with functional appliance OR maintain and incorporate into ortho Rx

Question 14

XLA of 6s in class III pts?

Answer 14

Delay ortho treatment to assess mandibular growth

Timing of extraction can alter if orthognathic surgery is planned