Designed osteotomy depth is 7.3 mm IS drill with 4 rings at #15.  In fact osteotomy is created using 2.2 mm drill with 2 rings (sinus membrane barely visible from the osteotomy) and 3-4 mm ones with 3 rings.  With a carrier of bone graft, sinus lift is initiated with 4x9 mm dummy implant (Fig.1). 

Sticky Last Next Xin Wei, DDS, PhD, MS 1st edition 11/06/2019, last revision 11/06/2019