Cone Beam Computed Tomography (CBCT) has been used to assess the volume of the maxillary sinus using the manual and semi-automatic segmentation. The majority of researches stressed on the reduced accuracy of the automatic segmentation when compared to the real volume. Regarding the semi-automatic segmentation, there are researches assessed the volumetric measurement of the maxillary sinus and they reported that there is no significant difference between semi- automatic and the manual segmentation in CT.

Automatic segmentation is believed to be less time consuming and more accurate in assessment of structures with regular border but fairly assessed the structures with irregular border like paranasal sinuses. The semi-automatic software is efficient and accurate as manual tracing with significant reduction in inter-observer variability and time . On the other hand, all neighboring contacting voxels located within a defined range (threshold) of similar HU values of different adjacent tissues may be measured so over calculation or under calculation could be suspected

Inclusion Criteria:

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Inclusion Criteria of participants of the In vitro part of the study:

• Skulls with intact walls of maxillary sinus.
• Skulls with dentulous or edentulous jaws.

Exclusion criteria of participants:

• Skulls with missing parts of the maxilla that could be caused from traumatic injuries, diseases and space occupying lesions of maxilla.
• Skulls with severe mutilation caused by environmental decay.

Inclusion Criteria of participants of the In vivo part of the study:

• Patients without any pathosis affects maxillary sinus.
• Patients with dentulous or edentulous jaws.

Exclusion criteria of participants:

• Patients with traumatic injuries, diseases and space occupying lesions of maxilla.
• Patients with sinus lifting or surgeries.
• Patients with mucosal thickening more than 3mm