Characteristics and dimensions of the Schneiderian membrane and apical bone in maxillary molars referred for apical surgery: a comparative radiographic analysis using limited cone beam computed tomography.

By Bornstein MM, Wasmer J, Sendi P, Janner SF, Buser D, Von Arx T.

Date: 04/2013
Journal: JOE


Purpose: to evaluate the thickness and the anatomic characteristics of the Schneiderian membrane and cortical bone using limited CBCT scanning in patients referred for apical surgery of maxillary molars.

The Schneiderian membrane is the mucous membrane that covers the inner part of the maxillary sinus cavity 

• N= 100  (2 groups of patients)

•Group 1 clinical signs and symptoms and/or radiographic apical pathosis related to at least 1 endodontically treated maxillary molar.

•Group 2 patients scheduled for limited CBCT imaging for further implant insertion in the posterior maxilla.


•The limited CBCT images were obtained using a small field of view.

•For each tooth, the slices were reformatted to align the root axis with the vertical plane in the sagittal and coronal views.

•The images were evaluated by a calibrated master student not directly involved in the treatment and follow-up of the patients.

•The analyses and measurements were performed using a specialized computer software (i-Dixel). Three Measurements were done for group 1 and two for group 2 (see figures).

Most highlighted Results:

•The apical bone was generally thicker in patients with periapical lesions. •For the Schneiderian membrane, the dimensions were statistically significantly higher for the patients in group 1 compared with group 2. •The values for the bone separating the apical lesions from the maxillary sinus ranged from 0.13 to 7.83 mm for group 1, and 0.00 to 2.88 mm  in Group 2.

•Clinical significance:

Because of the complex anatomic situation in the posterior maxilla, CBCT imaging is an important radiographic method for preoperative planning of apical surgery.

•Risk of oroantral communication should always be evaluated before surgery of an upper posterior tooth.