###### Abstract  
Background: Various parameters are known to affect the amount and type of mucosal thickening. The aim of this retrospective study was to investigate these effects through a survey of cone-beam computed tomography (CBCT) images. CBCT scans of 150 patients, which included the area of the MS and maxillary teeth (canine, first premolar, second premolar, first molar, second molar, and third molar), were evaluated retrospectively for the presence of sinus mucosal thickening. The parameters evaluated as possible causes of mucosal thickening were age, sex, tooth type, proximity to the maxillary sinus, endodontic treatment, and periapical lesion. Descriptive statistics and multiple logistic regression were used to analyze the data. A total of 28% of the teeth presented with mucosal thickening, which was associated with periapical lesions in 57.1% of 77 cases. The size of the lesion was the only parameter that was found to be significantly connected to the presence of mucosal thickness. More than 50% of teeth with periapical lesions in the posterior maxilla exhibited mucosal thickening. Other parameters such as age, sex, and the position of the root tips in relation to the MS floor did not influence the probability of developing mucosal thickening.  
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molars due to the super imposition of adjacent structures such as the palatal root or the zygomatic bone [13, 14, 15].  
Panoramic radiography (OPG) is usually used for the diagnosis of orofacial pain, however, panoramic images have only a limited value for the diagnosis of sinus lesions [16].  
Cone beam computed tomography (CBCT) is often used for imaging of the MS [17, 18].  
CBCT has a lower radiation dose [19], higher resolution, and lower scanning time [7], it also allows three-dimensional cross-sectional imaging, which eliminates distortion and superposition [20]. In this context, a number of studies have reported CBCT to be suitable for the evaluation of the maxillary sinuses and adjacent teeth [7, 21, 22, 23, 24, 25].  
A number of studies have compared OPG and CBCT for diagnosing sinus diseases, as well as for evaluating the anatomical relationships of the posterior teeth and their distance to the maxillary sinus floor. Panoramic imaging has a low efficacy in the diagnosis of sinus disease [16, 26] and a history of unreliable diagnoses when evaluating the distance between the sinus floor and roots of the maxillary teeth [27].  
The use of plain films, such as [PERSON] view (occipitmental view) and Caldwell's view (occipitofrontal view), is a traditional method for evaluating the sinonasal area. These methods have the advantage of availability, ease of use, low radiation dose, and low cost [28, 29, 30]. A study by [PERSON] et al. [31] comparing the diagnostic efficacy of digital Waters' and Caldwell's radiographic views in measuring the sinonasal area concluded that the digital Waters' view is a reliable modality for maxillary sinus evaluation, with a superior ability to detect healthy cases [31].  
One disadvantage of CBCT is that the soft tissue contrast resolution is inferior to that of magnetic resonance imaging (MRI), which can also provide precise sinus anatomical characterization, as well as a differentiation between inflammatory sinus alterations [32]. However, despite this capability, a number of studies have reported that the efficacy of assessing maxillary sinus pathology using MRI remains controversial [33, 34].  
Overall, the high radiation dose and financial cost of both CT and CBCT imaging necessitate a justification of their use to evaluate abnormalities of the maxillary sinuses [8].  
The purpose of this study was to use CBCT to analyze the correlation between the periapical status of maxillary posterior teeth and the status of the MS mucosa.