Osteotomy shows two layers of bone. The first one feels slightly less dense than the normal bone (Fig.1 above the red dashed line), while the second one is extremely hard (3-4 mm in depth). For the last 1.5 mm of the osteotomy, the 4.5 mm drill has to be withdrawn for bone shaving removal before finishing the osteotomy. In all the graft bone contributes to implant stability (insertion torque > 50 Ncm). At least the implant is surrounded by the bone with less likelihood of developing periimplantitis.
Xin Wei, DDS, PhD, MS 1st edition 09/04/2018, last revision 08/11/2019