Oroantral fistula

Abnormal communication between the maxillary sinus and oral cavity. It is most often a complication of tooth extraction, but may also occur after apicectomy; it may also develop spontaneously due to severe periodontal disease. The teeth most frequently involved are the upper second molar, followed by the first molar. Small fistulae may close spontaneously, but larger fistulae usually require surgical closure. Preoperative determination of the size of the fistula is often unreliable. The appearance of oroantral fistula on multiplanar CT imaging is disruption of the bony floor of the maxillary sinus, with soft tissue opacification of the maxillary sinus. Dental reformatted CT can be useful for evaluating patients suspected of having oroantral fistula. However, the bone between the roots of the teeth and the maxillary sinus may be very thin and is sometimes not visible on CT images. Moreover, the roots may appear to project into the maxillary sinus; this should not be misinterpreted as evidence of an oroantral fistula.