There is a 1 mm separation from the Inferior Alveolar Nerve (brown) if a 8 mm implant is placed at #31 (Fig.3 (coronal section)), whereas 3 mm separation for a 6 mm implant (Fig.4).  Bone graft will be needed buccal to the implant at #31 (red circle; L: lingual).

A coronal section at the site of #30 confirms that a 12 mm implant is safe (Fig.5). 

The gingiva is thin.  The cuff of the cemented abutment will be 1 or 2 mm.

Short Implant

Xin Wei, DDS, PhD, MS 1st edition 08/16/2015, last revision 08/16/2015