Our study hypothesis was that mucosal thickening of more than 2 mm and up to 1/3 of the volume of the sinus would not alter the predictability for SFE and dental implant placement. The primary outcome was to determine the success rate of dental implant placement in augmented maxillary sinus areas with mucosal thickening. A secondary outcome was to evaluate the effect of gender, age, and smoking on the dimensions of sinus mucosal membranes.

This study consisted of performing a retrospective analysis of cone-beam computed tomographic (CBCT) scans taken with a CBCT machine (i-CAT Cone-Beam Computed Tomography machine, Imaging Sciences International, Hatfield, PA) for patients that underwent both maxillary sinus elevation with grafting and implant placement at the University of Michigan School of Dentistry from 2004 to 2014. This study was approved by the University of Michigan Institutional Review Board.

Subjects that exhibited the following criteria were included in the study: partial edentulism, over 18 years old, received dental implants after sinus grafting, and had clinical and radiographic follow-up. These subjects had at least one CBCT scan prior to a SFE procedure. Subjects that exhibited the following criteria were excluded from the study: under 18 years old, subjects whose CBCT images were not clear enough to read, or had portions of the maxillary sinus not fully captured in the field of view. Subject data that was extracted from the general and medical record included the following: age, gender, and any systemic issues following a review of overall systems for the presence of any pathology (respiratory system, cardiovascular system, diabetes status, smoking history, etc.).

Subject data extracted from the dental records included the following: restorative, endodontic, periodontal, orthodontic, and oral surgery treatment or extractions.

Given these specific inclusion and exclusion criteria and the specific purpose of this study, only 29 cases qualified for inclusion from an original screen of approximately 4000 cases. An initial search of our database resulted in a larger number of cases that would theoretically qualify; however, further investigation revealed the need to exclude a great number of cases. The reasons for exclusion of these cases were as follows: scatter on the CBCT images due to fixed prosthodontics, unclear CBCT images, poor charting that did not allow for proper data gathering, no follow-up radiographs, not enough of the sinus being visible in the image, diagnosed periapical pathosis in the examined areas, implants not being placed in the area of the maxillary sinus, or no grafting completed in the maxillary sinus. Although these factors greatly reduced our sample size, this, in turn, created a stronger data set for analyses.