Extraction of first permanent molars
Introduction
First permanent molars, which erupt at around 6 years of age, are susceptible to hypomineralisation, hypoplasia and decay. First molars of poor prognosis may necessitate enforced extraction, or may be considered for elective removal by way of balancing or compensating extractions in an orthodontic treatment plan.
Balancing extraction - removal of first molar from contralateral side of the same arch
Compensating extraction - removal of first molar from ipsilateral side of opposing arch
Timing
The lower first permanent molars should be extracted when there is radiographic evidence of dentine calcification in the lower second permanent molar bifurcation. This is usually at 8-10 years of age.
In the upper arch, as long as the first molar is extracted before the upper second molar has erupted, ie by 12-13 years of age, the second molar will tend to move into a favourable occlusal position.
Class I
Minimal crowding
> No need to balance extractions
> Consider compensating extraction if lower first molar is removed to prevent upper first molar overerupting
> No need to compensate if upper first molar is removed
Crowding in buccal segments
> If bilateral consider balancing extractions for relief of crowding and maintenance of symmetric molar relationships
> Consider compensating when lower first molars are removed to prevent overeruption of upper first molars
Crowding in labial segment
> Little spontaneous relief with first molar extraction
> Leave extraction of first molars until second molars have erupted so extraction space can be utilised to relieve crowding
Class II
> Most space required in upper arch
> No compensating extractions required if upper first permanent molars are removed
> Compensating extractions should be considered if lower first molars are removed
Class III
> Extraction of upper first molars should be avoided if at all possible
> Extract lower first molars at optimum time to aid space closure
> Balancing or compensating extraction are not usually required