When a 3.8x16 mm implant is being placed, it is distal (Fig.4).  The MO composite of the tooth #30 has to be trimmed for fabrication of an immediate provisional (Fig.5 <).

To place the implant mesially, the initial osteotomy should be established higher in the mesial slope of the socket (Fig.3 red line).  Once the drill penentrates the lamina dura (Fig.5 short black line), change the trajectory (Fig.5 red line).  A potential drawback may be loss of primary stability when osteotomy increases.

To reduce the chance to injury the buccally located loop, the osteotomy should be as lingual as possible.  Initial depth is 19 mm (gingival level, Fig.3).  In fact all of the three intraop PAs (Fig.3-5) do not show the Mental Loop until panoramic X-ray is taken immediately postop (Fig.6).  There is no postop paresthesia.

Narrowly Missing Mental Loop Xin Wei, DDS, PhD, MS 1st edition 08/08/2017, last revision 11/29/2017