Since there is no buccal plate atrophy at 4, or 8, socket shield is not attempted at #13.  Extraction turns out to be difficult because of tooth fracture.  The buccal and palatal flaps have to be elevated minimally for tooth sectioning and purchase point formation.  More surprising, a 4.5 mm implant appears to be too wide for the space; a 4x17 mm implant achieves insertion torque >60 Ncm (Fig.1,2).

4 mm Implant Next Xin Wei, DDS, PhD, MS 1st edition 11/01/2018, last revision 11/01/2018