Fig.2 (CBCT sagittal section): The socket of the 1st molar seems to be distalized.  The mesial socket appears to be the ideal site for implantation.  Although  a 13 mm implant has sufficient clearance from the Inferior Alveolar Canal, it may violate another anatomic landmark.

Mesial Socket

Xin Wei, DDS, PhD, MS 1st edition 02/03/2017, last revision 10/07/2018