The study required access to University of Michigan Protected Health Information (PHI). PHI was necessary in order to track and coordinate the CBCT data and dental and medical history for each subject. Corresponding subject charts and electronic records were reviewed for retrieval of relevant implant placement and restorative history, medical history, and demographic information, including gender and age and smoking history. Also, any pertinent dental treatment was received and response to treatment were reviewed and recorded. No other personal information was retrieved. The use of PHI involved no greater than minimal risk because each subject was assigned a coded number that was used for all data analyses, tables, and reports.

Using CBCT images, the mucosal thickness/height was measured at the point of maximum height using sagittal views, which were perpendicular to the underlying sinus floor at edentulous sites [12, 20]. Using these sagittal views, measurements were taken at four points: ¼, ½, and ¾ of the widest distance of the maxillary sinus from anterior to posterior. In order to standardize the measurements for each sinus, each scan was carefully oriented in the axial, coronal, and sagittal plane. In the axial plane, a horizontal line from the right and left zygoma was chosen as the standard. Orienting the hard palate horizontally was the standard in the coronal plane as well as in the sagittal plane. The specific teeth that were to be replaced by implants were then located by reviewing each patient’s chart, and the area of implant placement was located in the CBCT. To select the appropriate slice in the sagittal view to measure the mucosal thickening, the vertical line in the axial view was placed in the center of the alveolus where the future implant was to be placed. The appropriate sagittal view was then obtained and measurements of the mucosal thickening were performed. Each measurement was completed with the brightness and contrast set at 50%, and the zoom function was utilized to better visualize the soft tissue.