---

Background and Objective: Maxillary sinus gradually extends laterally and inferiorly during pneumatization, and lamina dura of molar and premolar teeth can make a part of sinus floor. Knowledge about this anatomic relationship is essential to prevent complications paticularly iatrogenic perforation of sinus floor. Limitations of periapical and panoramic radiographs to visualization of this relationship led to the usage of cone-beam computed tomography (CBCT). This study was aimed to evaluate the vertical and horizontal relationship between roots of maxillary molars and sinus floor in CBCT images.
Methods: In this descriptive cross sectional study, ninety-five samples were selected of patients in Department of oral and maxillofacial radiology in Tabriz, Iran using simple randomization. Mean age of patients was 32.5 years old. Images were made by VGi cone beam Newtom and reconstructed by NNT viewer version 2.17. The vertical and horizontal relationship between roots of 139 maxillary first and 126 second molar teeth and floor of sinus evaluated.
Results: Type 2 was the most common relationship among the first and second molars, vertically (the inferior wall of the sinus located below the level connecting the buccal and palatal root apices,without an apical protrusion) and horizontally (the alveolar recess of the inferior wall of the sinus located between the buccal and palatal roots). There was a significant relationship between the type of tooth and sinus floor (P<0.05).
Conclusion: Most of the maxillary molar roots were in contact with sinus floor and sinus floor was extended mostly between buccal and palatal roots vertically and horizontally, respectively. Attention to sinus involvement possibility during interventions in maxillary molar region is important.

---

Background and Objective: Sinus extension is a physiological process that occurs in the growth cells of the paranasal sinuses and leads to increasing their volume over time, causing challenges in the dental implant process. This study was conducted to evaluate maxillary sinus morphometrics by cone-beam computed tomography (CBCT).
Methods: This descriptive-analytical study was conducted on the CBCT images of 100 people (52 male and 48 female) with a mean age of 45.32 ± 17.41 and the age range of 27 to 63 years referring to an oral and maxillofacial specialized radiology clinic in Babol, Iran during 2019. The amount of maxillary sinus extension in the panoramic-like view was recorded based on the amount of its extension in terms of the first anterior tooth and the last posterior tooth. In the new net technologies (NNT) software, in the section related to creating panoramic-like views, first, in the axial sections, the starting point of the maxillary sinus was specified from the occlusal side, and the mediolateral dimensions were measured at distances of 3 mm above and 3 mm below.
Results: The highest amount of maxillary sinus progress in the right anterior side was related to the mesial of tooth 5 (15%), and the highest amount of sinus progress in the left anterior side was related to the distal of tooth 3 (15%) and the mesial of tooth 4 (15%), which had no statistically significant differences. The most progress in the anterior area was related to the distal of the canine tooth and the mesial of the first premolar. The mean mediolateral sinus progress at 3 mm above the right nasal floor was higher in females than in males (P<0.05). Gender and age had no statistically significant relationship with maxillary sinus progress.
Conclusion: The maxillary sinus progress was almost equal in the left and right sides and also in males and females.