In partial fulfilment of the requirements for the degree of Master in Medical Research.

Background:
Sex estimation is a critical component of forensic identification. Traditional reliance on the pelvis and skull for this purpose is often limited by preservation challenges. The maxillary sinus, owing to its protected anatomical location and notable sexual dimorphism, offers a viable alternative. This study aimed to assess morphological variations of the maxillary sinus using Cone Beam Computed Tomography (CBCT) among male and female patients in a Nepalese population and to evaluate its potential for sex determination.
Materials and Methods:
A prospective analytical CBCT-based cross-sectional study was conducted at the Department of Oral Medicine and Radiology, KUSMS. Ethical approval was taken from the Institutional Review Committee of KUSMS. The study included CBCT images of 110 adult patients (57 males, 53 females). CBCT scans of subjects aged 20- 60 years with full permanent dentition and interpretable, high-quality images showing all walls of the maxilla were included. Cases with motion artifacts, maxillary sinus pathology, prior surgery involving the maxilla, or craniofacial abnormalities were excluded. Sinus dimensions, height, width, length, and volume were measured bilaterally using standardized protocols. Data were analyzed using unpaired t-tests to compare height, width and length, Mann-Whitney U test to compare volume between genders and discriminant function analysis was used to develop predictive equations for gender determination.
Results:
Males exhibited significantly greater sinus height, width, and volume on both sides (p < 0.05), confirming sexual dimorphism. However, sinus length did not show statistically significant differences. The discriminant function analysis produced gender prediction accuracies of 65.1% (right), 61.3% (left), and 64.2% (combined). Volume and height were the most reliable predictors, while length contributed minimally to sex differentiation.
Conclusion:
The study confirms significant sexual dimorphism in maxillary sinus morphology in the Nepalese population, particularly in height, width, and volume. CBCT-based assessment offers moderate accuracy in sex determination and serves as a valuable adjunct in forensic scenarios where conventional skeletal markers are compromised. Though not definitive alone, maxillary sinus morphometry can contribute meaningfully to a multimodal forensic identification framework.
Key words: Maxillary sinus, cone beam computed tomography, gender determination, forensic odontology, anthropometry