When the trephine bur extends 6 mm with possibly penetrating the mesial sinus floor (Fig.6 <), the 3.5 mm osteotome finally lifts the sinus floor (Fig.7 arrow) with perforation of the sinus membrane.

Uneven Sinus Floor

Xin Wei, DDS, PhD, MS 1st edition 08/24/2015, last revision 08/25/2015