The evolution of closed sinus lift techniques since 1994 [1] was proposed as a less invasive method for management of atrophic posterior maxillae [2]. However, it is a blind technique that lacks the ability to confirm an intact sinus floor elevation without perforation and thus represented a real shortcoming [3]. Various forms of osteotome lifters were designed to guarantee safe elevation of maxillary sinus membrane [4,5,6,7,8], but all failed to prove a non-perforated elevation during the actual lifting procedures. Previously, the endoscope was used to test the efficiency of the closed sinus lifting to detect the presence or absence of the perforation by doing a large window on the lateral sinus wall. The technique is considered an invasive surgery where another sinus surgery is required. Meanwhile, CBCT [9, 10] represented the most commonly used technique to evaluate the thickness of the membrane, but it is not sensitive enough to detect minor perforations. Thus, minor perforations can be escaped leading to implant failure. We used the crestal osteotomy to assess endoscopically directly the sinus membrane through the crestal osteotomy site of the implant.