Osteotomy at the sites of #2 and 3 goes on as planned.  Sinus lift using DIO 2.8 mm round bur with 6 and 7 mm stoppers (respectively) is carried on without certainty, because it is difficult to feel the stop through the osteotomy.  The crest may be uneven or soft.  It appears that the soft tissue landmark as a stop may be easier to identify.  In fact a 3 mm IBS Magic Expander (an osteotome) was used for sinus lift at #3.  The 2 implants are placed with 20 and 30 Ncm (Fig.1,2).  Healing abutments are inserted.  The one at #3 may touch the crestal bone, causing bone necrosis and infection; the healing abutment is incompletely seated and later dislodges.  Guide with Lift Last Next Profile Drill Xin Wei, DDS, PhD, MS 1st edition 03/28/2018, last revision 02/13/2021