Despite several researches have been done on dimensional changes in volume of the sphenoid sinus using computed tomography, there is limited report on this issue by cone beam computed tomography (CBCT). So, this study aimed to determine dimensional changes in volume of the sphenoid sinus based on sex, age and presence of septum using CBCT in patients. This study was done on 170 patient’s CBCT. All examinations were made with NEWTOM 3G CBCT system (QR, srl, verna, Italy) with exposure protocol of 110 kvp , 3.2 mA and 12×12-inch radiation field of view. The volume of the sphenoid sinus was determined by the semiautomatic segmentation mode of the ITKSNAP® 3.4.0 software (Cognitica). presence or absence of septum in the sphenoid sinus was evaluated by a dynamic evaluation of the CBCT volume in the axial, sagittal, and coronal views. The volumetric measurements and the assessment of the septum was done by two oral and maxillofacial radiologists. Data was analyzed using t-test by SPSS-21. Based on the results, there was significant difference between males and females on volume of the sphenoid sinus which was higher in males compared to the females (P=0.034). Also, there wasn’t significant relationship in presence or absence of septation with dimensional changes in the sinus (P>0.05). In addition, a lightly reduction in volume of the sphenoid sinus can be seen, by aging (P=0.000). In conclusion, results showed that there was relationship between sinus volume and gender. Also, with ageing, sinus volume decreases and the presence of septa in the sinus didn’t affect sinus volume

Dimensional changes, Sphenoid sinus, CBCT, Septa