The socket shield at #11 is apparently incomplete, since the apical gutta percha (Fig.2 <) and the apex of the root (Fig.2,3 R) are not removed.  The bone is hard when a 1.6 mm drill is being used (Fig.2) as the apical native bone is almost exclusively composed of the cortices.  Two of the apical threads of 3.5x13 mm implant are bent (Fig.3).

Hard Bone Last Next Xin Wei, DDS, PhD, MS 1st edition 09/28/2018, last revision 02/20/2021