title: 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.
abstract: BACKGROUND
  The purpose of the present study was to evaluate the thickness and the anatomic characteristics of the Schneiderian membrane and cortical bone using limited cone beam computed tomography (CBCT) scannning in patients referred for planning of apical surgery of maxillary molars.
  
  
  METHODS
  This controlled study included 2 cohorts of patients (n = 50 for each group). For patients in group 1 (with apical pathology), 3 measurements in millimeters were performed using coronal and sagittal CBCT slices: the dimension of the apical lesion in the axis of the root, the width of the cortical bone in the axis of the root, and the thickness of the Schneiderian membrane perpendicular to the underlying cortical bone. For the analysis of CBCT scans of group 2 (without apical pathologies), 2 measurements were performed using coronal and sagittal CBCT slices: the width of the cortical bone in the axis of the root and the thickness of the Schneiderian membrane perpendicular to the underlying cortical bone.
  
  
  RESULTS
  For group 1, the periapical lesions evaluated measured between 0.27 and 7.41 mm in diameter, the apical bone separating the apical lesions from the maxillary sinus ranged from 0.13 to 7.83 mm, and the dimensions of the Schneiderian membrane ranged from 0.25 to 13.98 mm. The apical bone was generally thicker in patients with periapical lesions. Regarding the dimensions of the Schneiderian membrane, the values were statistically significantly higher for the patients in group 1 compared with group 2.
  
  
  CONCLUSIONS
  The study showed that the Schneiderian membrane in the vicinity of roots with apical lesions tends to be significantly thicker when compared with the roots of teeth without apical pathoses.
authors.affiliation: Department of Oral Surgery and Stomatology, University of Bern, Bern, Switzerland. michael.bornstein@zmk.unibe.ch
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bornstein
authors.forename: Joelle
authors.initials: J
authors.lastname: Wasmer
authors.forename: Pedram
authors.initials: P
authors.lastname: Sendi
authors.forename: Simone F M
authors.initials: SF
authors.lastname: Janner
authors.forename: Daniel
authors.initials: D
authors.lastname: Buser
authors.forename: Thomas
authors.initials: T
authors.lastname: von Arx
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging*; D001047:Apicoectomy; D015331:Cohort Studies; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007576:Jaw, Edentulous, Partially / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging*; D008443:Maxillary Sinus / Q000000981:diagnostic imaging; D008875:Middle Aged; D008963:Molar / Q000000981:diagnostic imaging*; D009297:Nasal Mucosa / Q000000981:diagnostic imaging*; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging; D019227:Tooth Apex / Q000000981:diagnostic imaging*; D019553:Tooth, Nonvital / Q000000981:diagnostic imaging