CBCT axial section provides the most relevant information as to where to place mini implants (Fig.3,4).  It appears that the buccal (B) proximal space between #2 and 3 is the narrowest (Fig.4: 0.7 mm), where placement should be avoided.

Two of 1.6x6 mm and one of 1.6x8 mm implants are partially placed buccally and palatally (P), respectively. 

Intrusion

Xin Wei, DDS, PhD, MS 1st edition 07/15/2015, last revision 07/15/2015