Since crowding is most severe at R2s and 3s, extraction of R4s seems reasonable (Fig.6). 

No brackets are to be placed at R2s initially because of block out.

Elastic can be placed between R3s as early as possible to facilitate eruption.

Severe Crowding

Xin Wei, DDS, PhD, MS 1st edition 07/09/2016, last revision 07/09/2016