After use of 4.5x8.5 mm guide drill at #19, a 5x8.5 mm implant is placed with guide in place. When the latter is removed, the implant is found to be placed shallow.  Following use of 4.5x10 mm drill for ~.75 mm deeper, the implant returns with deeper placement (Fig.1,2), confirmed after guide removal.

Deep Enough? Next Xin Wei, DDS, PhD, MS 1st edition 11/12/2018, last revision 11/12/2018