Schneider membrane thickness classification evaluated by cone-beam computed tomography and its importance in the...

Perforation of the Schneiderian membrane is a common complication of sinus augmentation. The aim of this retrospective study was to assess the associations between the lateral wall technique and the ridge approach and the risk of perforation, together with the relations between the thickness of the membrane and the risk of perforation. We studied 200 patients (103 men and 97 women) who had cone-beam computed tomography (CT) before a sinus lift with either a lateral wall technique (n=100) or the rigid approach (n=100) for insertion of prosthetic implants. Two-hundred cone-beam CT images were studied, and the mucosal thickness was evaluated. Perforations of the membrane were recorded during operation. The thickness of the Schneiderian membrane on cone-beam CT images was classified as Type I (not recordable), Type II (0-2mm), Type III (3-4mm), or Type IV(>4mm). Type I was recorded in 52 (26%), Type II in 35 (18%), type III in 67 (34%), and type IV in 46 (23%). There were 16 perforations: 12 Type I and four Type II, seven of 100 with the lateral wall technique, and nine of 100 who had the rigid approach. Based on these results we suggest that a membrane 0-2mm thick may be an important determinant of perforation, regardless of the procedure used.