We report the case of a foreign body in the maxillary sinus with unknown path of entry.
The patient, a 60-year-old man, was referred to our department with a chief complaint of a sense of strangeness in the right paranasal sinuses. Panoramic imaging and computed tomography （CT） showed a 34mm （length） ×3mm （diameter） foreign body in the right maxillary sinus, which was like metal, and the right maxillary sinus mucosa was clearly swollen. The object was removed under general anesthesia, and radical surgery of the right maxillary sinus was performed at the same time. The post-operative course was uneventful.
The foreign body looked like a dental material related to root canal treatment. However, from a clinical point of view, there was no tooth extraction socket or oral maxillary sinus fistula. We asked the patient how the foreign body may have entered and the history of dental treatment, but his memory was vague and the path of entry was not known.
