Schneiderian membrane perforation upon the advancement of mechanical drills passing through sinus walls: An ex vivo animal study.

Background/purpose: This ex vivo study aimed to evaluate the perforation of Schneiderian membrane upon the advancement of drills incrementally in 1 mm passing through the sinus during the implant site osteotomy with two different drill types and techniques. Materials and methods: Fifty goat heads with 50 pairs of sinuses were assigned to two groups: osseodensification drill (OD) and inverse conical shape drill (ICSD) to simulate transcrestal sinus elevation. Osteotomy was performed to pass through the lateral sinus wall, advancing the drills incrementally in 1 mm until perforation occurred. The integrity of the Schneiderian membranes was confirmed under a microscope. Results: The OD group caused sinus perforation after drilling 1 mm beyond the sinus wall, with 8 perforations (16 %) out of 50. The ICSD group only showed perforations after 2 mm of drilling, with 3 perforations (6 %) out of 50. Seventy percent of perforations in the OD group occurred within 3 mm, while 44 % of those in the ICSD group did. Most OD perforations occurred between 2 and 3 mm, while in the ICSD group, they occurred between 3 and 4 mm. No perforation was observed in the ICSD group when drilling up to 1 mm beyond the sinus wall. Conclusion: Different designs of the drills possessed different tolerance of the advancement of drills exceeding the sinus walls. The ICSD group did not show sinus membrane perforation until the drills extended 2 mm passing through the sinus wall, while the OD group would encounter perforation with less than 1 mm exceeding the sinus walls.