Fig.4 (preop PA): The distance between the apex of the implant (7x14 mm) appears to be far from the upper border (red line) of the Inferior Alveolar Canal. 

Fig.6 (preop CBCT (coronal section through the septum) taken 2 years earlier): The apex of the implant is 2.8 mm from the upper border of  the Inferior Alveolar Nerve (N).  In fact the red line in Fig.4 is the lower border of the Inferior Alveolar Canal.

The stability of the implant is mainly derived from the contact with buccal (B) and lingual (L) cortices.

Overcautious or Not

Xin Wei, DDS, PhD, MS 1st edition 12/22/2014, last revision 12/23/2014