To avoid drills or implant (particularly immediate one, #13, Fig.3 (close to #12 distally curved root)) touching the neighboring root, 2.2 mm drill will reach the depth (sequentially) first and take segmental panoramic X-ray.  Then return to the original sequence: diameter first and depth second to avoid bone necrosis.

Positional X-ray Last Next Xin Wei, DDS, PhD, MS 1st edition 05/19/2019, last revision 06/04/2019