The aim of the present comparative study was to determine whether it is possible to diagnose the AAA canal in the lateral maxillary sinus wall in both corresponding PR and CBCT images. The hypothesis was that the AAA canal is more often identifiable in CBCT scans than in PR scans. The findings of our study indicate that in the CBCT images, the AAA canal could be detected in 154 (46%) cases in the maxillary sinus on the right. However, only 4 (1.2%) of these were also visible in PR (Table 3). One (0.3%) of the diagnosed AAA canals in PR could not be confirmed in CBCT.

A direct comparison of the corresponding images revealed that this may be caused by translucencies, such as those due to the hard palate or by imaging the dorsum of the tongue. Both of these are superimposed on the maxillary sinus in PR images and could result in misdiagnoses in the intervening translucent areas. From the available CBCT images, it was possible to detect 164 AAA canals (49%) on the left, while only 1 (0.3%) was recognizable in PR (Table 4). There was no case in which the AAA canal was visible in PR but not CBCT on the left.

No significant correlation was found between the presence of the AAA canal and age (p > 0.05).

As a first step, 549 patient records compiled in the period between 2010 and 2017 in a private dental practice in Stuttgart were selected and anonymized. A total of 335 patients (with 635 sites) fulfilled the selection criteria, of which 173 were female and 162 were male. The average age of the female patients was 62.1 years, and the average age of the male patients and 58.4 years. However, in contrast to similar comparative studies, the remaining 335 patients (with 635 sites) represent a high number of admissions used for statistical analysis [15, 18, 19].

In the preliminary stages, measurement integrity was verified by an expert. The measurements were repeated at 2-week intervals. For both intra-observer reliability and inter-observer reliability, Cohen’s kappa coefficient was computed as 1.0 with a 95% confidence interval of [0.92; 1.00]. Thus, a high degree of concordance was obtained.

Sinus lifting has become a common surgical intervention for increasing alveolar bone height prior to dental implant placement in the posterior maxilla [20]. However, specific complications must be accounted for intraoperatively, such as Schneiderian membrane perforation or bleeding from the antral alveolar artery [7, 9]. Maridati et al. reported that accidental bleeding of the AAA is one of the two most frequent complications of sinus lifting, along with perforation of the sinus membrane [9]. The AAA maintains a varying relationship with the sinus wall and is usually completely intraosseous. Only in rare instances (< 8%), it is more superficial on the lateral wall [21].

The detection of the AAA prior to dental procedures in connection with the maxillary sinus, such as elevation of the maxillary sinus floor, has been proven crucial for the avoidance of complications [7, 22]. Large-diameter blood vessels may impose more serious risk of bleeding during surgery [22]. Specialist literature recommends both PR and CBCT for diagnosis and planning prior to dental surgery [15, 16]. PR is a widely available, useful, and essential diagnostic tool in dentistry with respect to both diagnosis and general preoperative planning [23]. In PR, not every area of interest is accurately detected and allocated. The size and distribution of anatomical structures and lesions in the maxillary sinus affect visibility in PR. Furthermore, small maxillary sinus lesions (retention cysts, polyps, etc.) with a diameter of less than 3 mm show poor detection rates [18]. Particularly, CBCT leaves little room for interpretation of the findings and thus enables an examiner-independent assessment of specific findings that may be relevant for planned subsequent surgical interventions [24].

Three-dimensional imaging has been shown to be effective in the maxilla for a wide range of clinical settings, such as trauma, bone pathology, and neoplastic diseases, as well as dental implantology and sinus augmentation [24, 25]. In a systematic review of the assessment of the prevalence of an intraosseous canal in the lateral sinus wall, Varela et al. discovered that the detection of the canal has proven more frequent in CBCT studies (78.12%) than in CT studies (51.19%) [26]. They determined that in contrast to CBCT, conventional CT showed thicker arteries with a thickness of 0.5 mm or more. Thus, CBCT seems to provide reliable results with respect to the detectability of vascular canals. CBCT is a valuable diagnostic tool. Most previous studies recommend it as a presurgical evaluation of the maxillary sinus when identifying anatomical structures, particularly vascular supply [13, 27, 28].

In cadaver studies, both Rosano et al. and Sato et al. examined the prevalence of the AAA and discovered that it could be detected by dissection in 100% of the lateral sinus walls [12, 29]. By contrast, Temmerman et al. examined visibility in the lateral sinus wall and discovered AAA canals in 50% of the analysed CT images [30]. Likewise, Elian et al. and Mardinger et al. came to similar conclusions [31, 32]. As Mardinger et al. argue, a significantly lower number of detected AAA canals shows that the vessel must be of sufficient size to be identified by a CT scan.

The results of our study show similar observations regarding the visibility of the AAA canal and are confirmed by previous studies. The AAA canal could be observed in almost half of the CBCT images. It is possible smaller AAA canals were not visible in our CBCT images.

In addition to anatomical variations in the maxillary sinus, Shiki et al. evaluated pathological findings such as mucosal thickening, fluid retention, and sinus opacification related to the occurrence of maxillary sinusitis in PR and CBCT. They reported that soft tissues of the maxillary sinus cannot be effectively visualized in panoramic radiographs. One key result of this study was that the incidence of maxillary sinusitis was twice as high in patients opting for implant-supported restoration than in patients who did not [18].

They also found that some lesions in the maxillary sinus often have no symptoms initially. They concluded that the diagnosis of the pathological findings is often carried out incidentally when images of the area are obtained for other purposes. The authors recommend searching for these, since they are related to limitations in inserting dental implants and are causes of severe post-surgery inflammation. Above all, if the operation is unsuccessful, a worsening of the lesions would be expected [18].

Dau et al. discussed an entirely different aspect. In their experimental and comparative diagnostic study, they sought to determine whether the use of PR as opposed to CBCT impacts the evaluation of symptomatic maxillary sinus pathologies. Depending on the clinical and radiological experience of the observer, they found that PR alone remained insufficient for evaluating pathologies in the maxillary sinus [33]. This raises an interesting question of whether the presence of pathological findings influences the visibility of AAA canal in CBCT, meaning that in these cases, CBCT would not be indicated to detect AAA canals. Anamali et al. concluded that CBCT images provide highly instructive information, including the presence of AAA canal, regardless of the presence of intrasinusal pathoses [34].

Whether there is a correlation between the patient's age and the visibility of the AAA canal is controversial. While some working groups describe a correlation in their studies [32, 36], others could not find any correlation [37, 38].

In our study no significant association was found between the prevalence of the visibility of the AAA canal and age of participants. Further studies will be necessary here to be able to make a reliable statement.

The results of our study are consistent with other studies [24, 27, 34]. Accordingly, the present study shows that PR systematically underestimates the visibility of AAA canal. This was shown by directly comparing corresponding PR and CBCT images. Based on the present data, cross-sectional imaging may be recommended during the surgical planning of sinus augmentation procedures in visualising AAA canal for minimizing both intra- and postoperative complications.

Therefore, our hypothesis that there is a difference in the visibility of the AAA canal in the lateral maxillary sinus wall in favor of CBCT images compared to PR images can be agreed.