The anatomical proximity of the roots of molars and premolars to the floor of the maxillary sinus creates the risk for the formation of odontogenic sinusitis, which is often initiated by foreign bodies entering the sinus during dental procedures. Odontegenic foreign bodies (FB) of the maxillary sinus are usually represented by fragments of tooth roots, filling material, plastic material used in sinus lifting, dental implants, dental burs, pins and needles. FB causes the development of an inflammatory process in the sinus due to the penetration of highly virulent microbiota of the oral cavity or the formation of a fungal body. In rare cases, small FB can be evacuated into the nasal cavity as a result of the movement of the cilia of the ciliated epithelium. Most odontogenic FB are radiopaque and are detected by computed tomography (CT) of the paranasal sinuses. CT data allows to accurately localize FB and choose a treatment tactics.