Process of ectopic tooth formation in the maxillary sinus: follow-up observation of one case

Abstract

Objective: This study was performed to investigate the process of ectopic tooth formation.

Methods: A patient with an ectopic tooth was followed for 6 years. The tooth size and mineralization were evaluated by paranasal sinus computed tomography every 3 years.

Results: The ectopic tooth was present in the nasal crest of the maxilla and did not change significantly during the 6-year follow-up period. However, the patient developed a new ectopic tooth in the maxillary sinus (ETm). This tooth, located in the posterior wall of the left maxillary sinus, initially appeared as a small region of soft tissue on computed tomography. After 3 years, the area of mixed density had significantly increased, and some of it had significantly mineralized to form an ETm. After 6 years, the ETm had further mineralized and enlarged in situ. The width between the left and right sides of the ETm in 2018 (9.08 ± 2.09 mm) was significantly larger than that in 2015 (7.51 ± 2.18 mm), indicating that ETm formation is a gradual process of mineralization.

Conclusion: Ectopic teeth can gradually form by in situ mineralization after adolescence, suggesting that ectopic teeth are genetically regulated and result from a programmed formation process occurring at a specific time point.

Keywords: Ectopic teeth; computed tomography; follow-up studies; maxillary sinus; mineralization; supernumerary teeth.

Figure 1.

Coronal computed tomography images obtained at three time points showing an ectopic tooth in the nasal crest of the maxilla. (a) 2012, (b) 2015, (c) 2018. There were no significant differences among the three scans (ranging from 2012 to 2018).

Figure 2.

Axial computed tomography (CT) images showing the process of ectopic tooth formation in the posterior wall of the left maxillary sinus (ETm). (a) The first CT examination (2012) showed the ETm as only an area of soft tissue density in the posterior wall of the left maxillary sinus accompanied by a slight bone defect. (b) The second CT examination (2015) clearly showed the ETm, but mineralization was not complete, and half of the area remained an area of soft tissue density. However, the posterior wall of the left maxillary sinus showed complete ossification. (c) The third CT examination (2018) showed complete mineralization of the ETm in situ.

Figure 3.

The ectopic tooth in the nasal crest of the maxilla (ETn) was extracted during nasal cavity ventilation expansion surgery. (a) Intraoperative observation of the ETn. (b) The extracted ETn.