Discussion
The nasal cavity and paranasal sinuses (frontal, ethmoid, sphenoid and maxillary sinuses) form an anatomical and functional unit covered by the same mucosa. The drainage of these sinuses is from small and narrow openings into the nasal cavity. 3 While early on, the aeration of these sinuses was detected by anatomical measurements, cadaver studies and conventional radiography, today detection is performed with CT imaging (Computerized tomography) with evaluation in all sections and provides more accurate data. 7
Cavalieri method is an effective method used to calculate the volume of anatomical structures. It is used to measure the volumes on 3D radiographs of structures that cannot be isolated. In this method, the object whose volume is to be calculated is divided into sections of the same thickness on the radiograph. In these sections, the area of the relevant object is calculated by using the planimetry or the point counting methods. The total volume is calculated by multiplying the calculated total area with the section thickness. 8Although the Cavalieri method has been used frequently for calculating volumes of anatomic structures. Today, different workflows have been determined with newly developed software and the volumes of anatomic structures are now calculated with these software. In the present study the method used by Tretiakow et al. has been employed for volume calculation. 9 After image acquisition, axial, coronal, and sagittal planes were generated by the software and the segmentation process was navigated and inspected. The “threshold”, “scissors”, “islands”, “level” and “smoothing” tools were used respectively and paranasal sinus volumes were calculated.
The complex structure and pneumatization of the paranasal sinuses have been evaluated in numerous studies in different populations and both patient groups with underlying sinus diseases and non-diseased patients have been reported to have considerable anatomic variations.7, 10-12 The same data were also widely investigated before and after different non-surgical and surgical interventions for various pathologic conditions. 4, 8, 13-18 Changes in paranasal sinus morphologies are often varying degrees of hypoplasia, and it has been observed that the formal configurations are commonly preserved. This situation has been reported in genetic syndromes that cause growth center arrests, interval pressure alterations and osteonecrosis. 10 Shape asymmetries are frequently reported among CLP (cleft lip and palate) human fetuses. Especially the sphenoid sinuses can vary in shape and size. It has been also shown that the maxillary sinuses of CLP fetuses are insufficient in size compared to fetuses without CLP. 1
Le Fort I osteotomy is one of the techniques among subspecialties of maxillofacial surgery and enables to treat dentofacial deformities of the midface. In this technique, temporary disconnection of the complete maxilla from the midface is required. While it enables to move the maxilla in three dimensions superior repositioning of the maxilla is typically necessary in the maxillofacial deformity treatment with a vertical maxillary excess, such as cases of long face, open bite, or mentum protrusion. 8 Studies investigating the anatomy of paranasal sinuses before and after Le Fort I osteotomy are great in number. It has been reported that the impact of Le Fort I osteotomy on the upper airway spaces depends on the amount and direction of the skeletal movements, age, gender, and individual variations, and that Le Fort I osteotomy can have an important impact on sinus health.15,16 The volume of maxillary sinuses increases compared to that of the pre-surgery and there are reports of possible complications after Le Fort I osteotomy such as causing or aggravating pre-existing maxillary sinus inflammatory processes such as acute sinusitis, the incidence of rhinosinusitis symptoms and iatrogenic damage. 13,16,18