Female, 36 years old. She was admitted to the hospital with “nasal neoplasm (left) and nasal septal deviation” because of “left-sided nasal congestion for more than 3 years, aggravated by blood in mucus for 1 month”. He was in good health. The patient had a history of jaw injury in early childhood and had undergone a labiogingival incision at the age of about 10 to remove an ectopic tooth from the left maxillary sinus at a local hospital. In the past month, the nasal congestion was aggravated with blood in the snot, so he went to the local county people’s hospital and was examined by sinus CT: left maxillary sinusitis and foreign body in the left nasal cavity; he was referred to our hospital for surgery. He was admitted to the hospital for examination: general condition was good; there was no deformity of the external nose, left deviation of the nasal septum was obvious, there was a new biological bulge at the bottom of the left nose, hard, mucous membrane was broken and dirty, a little purulent discharge from the left nasal cavity, the right nasal cavity was clean, no abnormality was seen; oral teeth 2 3 4 were absent, denture repair was performed, gums were not broken. Sinus CT (64-row reconstruction) showed: deviated nasal septum, inflammation of left maxillary sinus, irregular shaped bony protrusion of the medial wall of sinus cavity and nasal base, see Fig. 1 and Fig. 2. “After extraction, there was also a cuspid tooth partially protruding into the nasal cavity at the junction of the lateral side and the medial wall of the maxillary sinus, which was not active and was extracted, and there was no sinus tract with the maxillary sinus, the middle nasal tract was clean, the natural opening of the left maxillary sinus was good, and the oral gingival mucosa was was intact. The patient was given symptomatic treatment such as anti-infection and hemostasis, and the nasal filling was removed on the second postoperative day and discharged on the seventh postoperative day. At the time of discharge, the nose was well ventilated, the nasal septum was centered, and the trauma at the base of the nose was covered with pseudomembrane. Final diagnosis: nasal ectopic tooth (left) and deviated nasal septum. At 1 month postoperative follow-up, the patient’s nose was well ventilated and the left nasal base was completely epithelialized, with no sinus tract formation, nasal stenosis or other sequelae remaining. Transposed tooth is more common in oral diseases, but nasal ectopic tooth is less common. In this case, the ectopic tooth in the left nasal cavity was probably caused by the traumatic injury in early childhood, which caused some teeth to flip and shift and grow wrongly into the nasal cavity. The clinical symptoms of nasal ectopic teeth are diverse and include facial pain, recurrent nasal congestion, rhinorrhea, foul-smelling purulent snot, headache, external nasal deviation, and naso-oral fistula. A detailed medical history, such as a history of previous facial trauma and a family history of facial developmental disorders (e.g., cleft palate), can help in the diagnosis. Examination reveals white or black nasal dentition, often covered by granulation tissue, which should be distinguished from exophytic bone warts, nasoliths, nasal foreign bodies or tumors. Detailed examination of the alignment of the oral permanent dentition, paying attention to the neatness of the incisal area, the presence of missing teeth, infection or sinus tract formation, etc. Nasal X-ray or CT examination can assist in the diagnosis, and eventually, surgical extraction of the nasal teeth is required to confirm the diagnosis. The timing of extraction is usually chosen after the permanent teeth around it have fully erupted to avoid damaging the permanent dentition. In this case, a labiogingival incision was performed to remove the ectopic teeth from the left maxillary sinus before the patient reached adulthood, but the diagnosis was missed because the other two ectopic permanent teeth in the nasal cavity had not yet erupted. Figure 1: Horizontal CT of nasal ectopic tooth (left) Figure 2: Coronal CT of nasal ectopic tooth (left) Figure 3: Physical picture of nasal ectopic tooth with dirt on the surface of the tooth exposed in the nasal cavity