Morphometric Analysis of the Maxillary Sinus Using CT-Based Air-Cavity Reconstruction: A Retrospective Study

Background/Objectives: This study aimed to characterize the three-dimensional morphology of the aerated maxillary sinus using CT-based air-cavity reconstruction and to evaluate its relationship with selected morphometric parameters, septa characteristics, bilateral symmetry, and dental root extension. Methods: This retrospective study included 125 paranasal computed tomography (CT) examinations from 61 males, 64 females (mean age 37.04 ± 15.37 years), corresponding to 250 maxillary sinuses. Three-dimensional air-cavity segmentation was performed using Mimics software following a standardized Hounsfield unit-based thresholding protocol. Morphological patterns of the aerated cavity were classified according to internal compartmentalization and associated morphological features. Morphometric measurements, including ostium-to-sinus-floor distance, axial sinus dimensions, multiplanar septal characteristics, and dental root extension, were recorded and statistically analyzed. Results: Unilocular morphology represented the predominant configuration on both sides (right: 55.2%; left: 53.6%), whereas bilocular and multilocular patterns were less common. Morphologically more complex configurations demonstrated a higher frequency of coronal and axial septa than simple unilocular cavities. Side-to-side differences were identified for ostium-to-sinus-floor distance (p = 0.050), axial longitudinal sinus length (p = 0.027), and pole measurements (p < 0.001). Dental root extension was more frequent on the left side (16.0%) than on the right (6.4%; p = 0.002). Male participants exhibited greater ostium-to-sinus-floor distances and larger axial sinus dimensions than females (all p < 0.05), whereas age showed only a weak negative correlation with left axial transverse sinus length (ρ = -0.191, p = 0.032). Inter-observer agreement for the proposed 18-category three-dimensional morphological classification was substantial (Cohen's κ = 0.726 for the right side and κ = 0.717 for the left side; both p < 0.001). Conclusions: CT-based three-dimensional air-cavity reconstruction enabled detailed evaluation of the internal morphology of the aerated maxillary sinus. The observed variability in morphological patterns, septa distribution, and selected morphometric characteristics suggests that assessment of the aerated cavity may complement conventional morphometric evaluation of the maxillary sinus. These findings provide a descriptive anatomical reference that may support future radiological, anatomical, and computational investigations of maxillary sinus morphology.