Septa within the sinus: effect on elevation of the sinus floor.

Elevation of the sinus floor allows the correct number and length of oral implants to be placed. The sinus membrane is dissected blindly, usually by a crestal approach, but several internal configurations of the maxillary sinus or intrasinus septa can cause problems. We studied 150 sinuses from 40 male cadavers, and 35 randomised male patients by anatomical dissection and computed tomography. Forty-six subjects (61%) had no bony septa or had septa less than 4mm. Twenty-nine (39%) had bony septa of which seven were incomplete, one had a complete bony septum in each maxillary sinus, and 20 had symmetrical bony septa. We present the results of a study of bony intramaxillary sinus septa and the potential problems they can cause during elevation of the sinus floor.