Non-symptomatic abnormalities of the maxillary sinus such as mucosal thickening, retention cysts, and opacification are reported to occur in up to 74% of all cases [1–6]. For diagnosis of symptomatic pathologies of the maxillary sinus like retention cysts, polyps, and tumors, panoramic radiographies (PAN) are commonly used and widely available. In PAN, not every area of interest is accurately detected and allocated. Furthermore, small maxillary sinus lesions with diameter less than 3 mm show poor detection rates [7]. Three-dimensional imaging is useful in the maxilla for a wide range of clinical settings, such as trauma, bone pathology, and neoplastic diseases, as well as in dental implantology and sinus augmentation [8–12].

Computed tomography (CT) is an excellent tool for maxillary sinus examination and diagnosis [13, 14]. A survey among 331 otolaryngologists showed that the majority (75%) did not obtain confirmatory CT scan before initial non-surgical therapy. Though, prior proceeding with sinus surgery, an average of one (59%) or even two (37%) CT scans was reported [15]. Cone beam computed tomography (CBCT) is mostly used for dental implant planning [6, 10, 16] and offers diagnostic options similar to CT scans but without contrast agents and with about 10–50% less radiation exposure [17, 18]. Especially if small fields of view are used for CBCT, radiation exposure is significantly reduced. However, this exposure to radiation as well as the costs are still significantly higher when compared to those of conventional dental imaging [19–22]. For diagnosis and general preoperative planning, both PAN and CBCT are described to be useful and important diagnostic tools [11, 23, 24]. Nonetheless, there are only few studies [7, 12, 14, 25] and some case reports [26–28] that showed an additional clinical benefit of CBCT for evaluation of maxillary sinus when compared to PAN. In most studies, non-symptomatic sites were visualized in order to exclude pathologic findings prior to dental implant surgery [1, 7, 23, 24, 29, 30].