The precise assessment of the maxillary sinus is important in oral and maxillofacial surgery in cases of traumatology, sinusitis, and dental implantology. After the introduction of cone-beam computed tomography (CBCT) in dental medicine in 1998 [1], the number of clinicians using CBCTs increased constantly. Whereas in 2004, there were only three CBCTs registered in Switzerland, the current number exceeds 600. The CBCT has become an important diagnostic tool in dental medicine due to its high resolution and its possibility to limit imaging to specific areas of interest. Various specialties in dental medicine like oral and maxillofacial surgery and endodontics increasingly utilize CBCT imaging.

In general dentistry, however, panoramic imaging is still more popular than CBCT. The advantages of panoramic imaging are less radiation, less costs, and its suitability for primary diagnostics. The advantages of CBCT on the other hand are a high image quality of high-contrast structures, no geometric distortion, and no superimposition of surrounding anatomical structures [2].

The aim of this study was to examine the suitability of a volume measuring tool, being included in the implant planning software SMOP (Swissmeda AG, Baar, Switzerland), for the measurement of the 3D shape of the maxillary sinus. Next, this tool was used to measure the volume and surface of the maxillary sinuses. To the best of our knowledge, there is currently no study measuring the osseus and mucosal borders in CBCTs on a 3D level for the analysis of volume reduction due to obliteration. By measuring the osseus and mucosal bordered volume (remaining pneumatized cavity), not only the volume of the obliteration could be calculated, but also possible association between sinus obliteration and the dentition state as well as with the presence of periapical radiolucencies and foreign bodies could be analyzed. Further, possible associations between these measured sinus volumes and patient-specific general variables such as age and gender were evaluated.