Shape, Septa and Scalloping of the Maxillary Sinus

The maxillary sinus varies according to age, however there are limited studies that have illustrated its 3D form over time. This study aimed to classify the maxillary sinus by the shape, number of septa and scallops in a 1 to 25 year age group, utilising computerized tomography (CT) scans and 3D reconstruction. CT scans (n=480) were reviewed from the picture archiving and communication system (PACS) of the state and private hospitals in Pietermaritzburg and Durban KwaZulu-Natal (KZN), South Africa. The sample consisted of 276 males and 204 females, 1-25 years and of two population groups, black African and white. SLICER 3D (www.slicer.org) was utilised in order to reconstruct a 3D model of the sinus. Morphological traits such as the presence of the sinus, scalloping and septa within the sinuses were categorised. In addition, the shape of the 3D model of the sinus was analysed anteriorly (coronal) and laterally (sagittal) adapting the classifications by Kim (1962) and Kim et al. (2002). The maxillary sinus was present bilaterally in n=477 individuals (99.4 %). Five different anterior shapes viz. Type 1 (triangular), Type 2 (upside down triangle), Type 3 (square), Type 4 (irregular) and Type 5 (rectangular) were identified in the anterior view. This shape was associated with age and population groups (p<0.05). In the lateral view, the maxillary sinus appeared to be quadrilateral with differences noted along the inferior wall. Intrasinus maxillary septa were more evident in the anterior region of the maxillary sinus (27.9 % right; 28.5 % left). The maxillary septa were commoner in females (37.9 % right; 39.4 % left) than in males (28.5 % right; 30.3 % left). They were also more commonly observed in the white cohort (63.8 % right; 68.1 % left) than in the black African cohort (29.1 % right; 30.5 % left). Scalloping in the axial plane from above along its anterior margin was also observed. An in-depth classification of the morphology of the 3D form of the maxillary sinus according to age (1 to 25 years) was established. Five different shapes in both the anterior and lateral view of the 3D model were observed. Anteriorly, it was noted that the main shape was Type 2 (upside down triangle). The shape of the sinus changed in the form according to age. Laterally, the shape was related to the development of the teeth, as the inferior wall of the sinus was classified. Maxillary septa and scalloping of the sinus were reported in all age groups. Surgically, the sinus morphology is essential for dental procedures such as sinus augmentation or dental implants, and anthropologically, in forensic identification.