In total, 128 maxillary sinuses were analyzed. The mean surface area was found to be 39.7 cm² and the mean volume 17.1 cm³. The mean surface area of the remaining pneumatized cavities of obliterated sinuses was found to be 36.4 cm² and the mean volume 15 cm³ (Table 1). 42.2% of all sinuses showed an obliteration, and the mean volume of the obliterated sinuses was 5.1 cm³. If there was an obliteration, on average, 27% of the maxillary sinus was obliterated, and overall, the obliterations ranged between 1 and 95%. The dentition state (edentulous, partly edentulous, or dentate posterior region) had no influence on the size of the osseus sinus volume (Fig. 4, p = 0.52).

A total of 73 maxillary sinuses showed unimpaired conditions (57.0%), and 55 showed a pathology (43%). Out of these 55 patients showing a pathology, 30 had a mucosal thickening (23.4%), 17 had a sinus polyp (13.3%), one showed a complete obliteration (0.8%), four had a mucosal thickening and a periapical radiolucency (3.1%), one had a foreign body (0.8%), one had a mucosal thickening and a foreign body (0.8%), and one had a nonspecific opacification (0.8%) (Table 2). Moreover, 20 out of the 55 recorded pathologies were seen in women (36.4%) and 35 in men (63.6%).

The presence of a pathology significantly (p < 0.001) increased the obliterated volume of a maxillary sinus (Fig. 5). Apical radiolucency, on the other hand, did not increase the obliterated volume of the maxillary sinus (p = 0.32). There was also no association between the presence of pathology and the number of communicating roots with the maxillary sinus (p = 0.62).

In total, 64 patients were analyzed. Patients had a mean age of 46.2 years. Out of 64 patients, 38 were female (59.4%) and 26 were male (40.6%). Fifty-five patients (85.9%) were dentate or partially dentate and 9 edentulous (14.1%). Fifteen patients (23.4%) had endodontic treatment on at least one tooth in the posterior region of the upper jaw starting from the first premolar. The frequency of teeth communicating with at least one maxillary sinus was 34.4% (22 patients). More than half of the patients (54.7%) had at least one partially or fully obliterated sinus. Out of these 35 patients, 16 had a unilateral obliteration of the maxillary sinus (25%) and 19 had a bilateral obliteration (29.7%). Apical radiolucencies were present in 11 patients (17.2%).