The maxillary sinus is the largest of four paranasal sinus. It appears as a pyramid of four thin, bony walls, the base of which faces the lateral nasal wall and the apex of which extends toward zygomatic bone. The antrum is approximately 34 to 35mm at its base, and the apex extends 23mm toward the zygomatic area. The average volume is 15mL and increases as posterior tooth loss and pneumotization occurs. Bony septa joining medial and lateral walls may complicated the sinus lift procedure as potential for sinus membrane perforation at these areas.
Pathologically, sinusitis has been related often to maxillary or frontal sinus involvement. Other problems identified with lesser encounter includes tumors and malignancy. 60% of squamous cell carcinomas of the paranasal sinuses located in the maxillary sinus, usually in the lower half of the spectrum. Other iatrogenic incidence would be oroantral fistulas as the consequence of the tooth or implant extraction, trauma, or surgical entry into the maxillary sinus. Because of anatomic proximity of the sinus and oral cavity, many oral diseases also extend into the sinus such as periapical, follicular, and odontogenic keratocysts, fibrous dysplasia, ossifying fibromas, and giant cell lesions. Other cystic lesions such as pseudocysts, retention cysts, and/or mucocele may be diagnosed in the area.
- Upper left: maxillary sinus in relation to the skull
- Upper right: close up view of maxillary sinus
- Lower left: maxillary sinus in relation to the teeth, noted the root proximity of posterior teeth to the sinus floor
- Lower right: interior view of maxillary sinus, the lateral wall is carefully section and lift up to see the inside of the sinus cavity. The sinus membrane lines the cavity. Note the ostium where the sinus drainage occurs.