A twelve-year-old girl walked into a dental school in Belfast with what looked like a straightforward referral: two extra teeth behind her upper front teeth that needed removing before orthodontic treatment could begin. What her clinicians discovered instead was one of the rarest dental anomalies in the literature, a developmental fusion between her permanent maxillary right central incisor and a partially erupted supernumerary tooth. The case, published in Clinical Case Reports, demonstrates how three-dimensional imaging and multidisciplinary planning transformed a routine extraction plan into a carefully choreographed surgical and orthodontic effort to save one of the most aesthetically and psychologically important teeth in the human dentition.
Tooth fusion is defined as the union of the enamel or dentin, or both, of two or more separate tooth germs during development. It is an uncommon finding even in baby teeth, with reported incidence rates ranging from 0.5 to 2.5 percent in the primary dentition and dropping dramatically to between 0.01 and 0.2 percent in the permanent dentition. Supernumerary teeth, additional teeth beyond the normal series, are somewhat more frequent, occurring in roughly 0.3 to 0.8 percent of primary dentitions and 1.5 to 3.5 percent of permanent ones, and they favor the anterior maxillary region more than any other site in the mouth. But when these two anomalies occur together, and specifically when a permanent incisor fuses with a supernumerary tooth, the situation becomes exceptionally rare, documented largely through isolated case reports and small case series.
The patient was referred by her community orthodontist in April 2025 for removal of two supernumerary teeth associated with the palatal aspect of both maxillary central incisors, along with two retained primary canines, to clear the way for fixed orthodontic treatment. Her medical history was unremarkable, there was no history of dental trauma, and no family history of fusion. By the time she was assessed, one primary canine had exfoliated naturally, but on the right side the clinical picture was more complicated: the supernumerary tooth there was partially erupted and lying palatal to the permanent central incisor. Vitality testing of the incisors was positive, and there was no tenderness to percussion, but clinical examination alone could not reveal the full story.
That story emerged from cone-beam computed tomography, the low-radiation three-dimensional imaging technique that has become indispensable in modern dentistry when two-dimensional radiographs fall short. The CBCT scan suggested fusion between the maxillary right central incisor and the adjacent supernumerary tooth, prompting a formal report from specialist dental and maxillofacial radiologists at Leeds Dental Institute. Their assessment confirmed continuity of dental tissue between the roots of the central incisor and the supernumerary in the coronal third of the roots, consistent with fusion. The supernumerary’s root was also described as sinuous in its apical third. On the left side, a second conical supernumerary sat palatal to the other central incisor with no direct contact, though without bony separation from the incisive foramen.
Orthodontic assessment revealed a class II division 2 malocclusion on a class I skeletal base, a shifted upper dental centerline, and a partially erupted maxillary left permanent canine. The treatment team identified clear reasons to remove the supernumeraries: they mechanically obstructed planned tooth movement and carried risks of resorption, dentigerous cyst development, and damage to adjacent teeth. Critically, the fused supernumerary would compromise movement of the upper right central incisor and increase the risk of caries and infection, since the fusion created a subgingival area protected from manual cleaning. Two options were presented to the patient and her family: monitoring the teeth in situ with awareness of future pathology risks, or proceeding with fixed appliance placement followed by surgical separation of the fusion.
The team chose the latter, and the planning that followed illustrates the depth of contingency thinking required for such cases. Because the surgery risked removing palatal bone support, there was a real chance of losing the central incisor during the operation or later through downstream pathology. A removable prosthesis was fabricated before surgery to replace the incisor should it be lost, and longer-term contingencies, from transitional adhesive bridgework to eventual implant placement once growth ceased, were mapped out. The patient’s high lip line, showing 2 millimeters of gingiva when smiling, added aesthetic urgency to these discussions, since prosthetic replacement near the smile line is unforgiving. Her adolescent age further complicated matters, as implants are typically deferred until jaw growth is complete.
The orthodontic preparation was itself a strategic maneuver. A fixed upper appliance was placed with a 0.013 nickel-titanium wire, later advanced to a 0.018 stainless steel round wire. The deliberate choice of a round rather than rectangular archwire avoided root torque on the vulnerable incisor, reducing the risk of iatrogenic damage during surgery. The appliance also served as a splint: with the wire in place, the maxillary right central incisor was mechanically stabilized intra-operatively and during post-operative healing, essentially turning the rest of the dental arch into a physiological support structure for the tooth at risk.
Surgery took place under general anesthetic in the oral surgery department. After reflecting a mucoperiosteal flap, the surgeons clinically confirmed the fusion. Using an osteotome with digital support of the upper right central incisor, they separated the supernumerary from the incisor and delivered it intact, leaving the permanent tooth firmly in place. The second supernumerary and the retained primary canine were removed in the same session. Intra-operative photographs documented the procedure, and follow-up examinations two months later showed the patient healing well, with the incisor retaining vitality and no radiographic signs of pathology.
The case underscores a broader lesson about diagnostic imaging. Guidelines support CBCT when two-dimensional imaging fails to provide sufficient diagnostic information, and here the scan was fundamental in confirming what was an incidental finding, a fusion neither clinically apparent nor expected. Without it, the surgical team would have approached what looked like routine supernumerary extraction with inadequate preparation, and the intra-operative findings matched the imaging precisely. The information gleaned shaped surgical planning, risk assessment, and the informed-consent conversation with the family, illustrating how modern imaging directly translates into safer care.
The literature contains successful examples of sectioning fused teeth using rotary handpieces and even lasers, but separation always carries risks including dentin hypersensitivity, pulpitis, resorption, and the potential need for root canal treatment or extraction. The Belfast team’s success hinged on weighing surgical and post-operative complications against the risks of leaving the anomaly in place, sequencing orthodontics before surgery to provide splinting where bone support was compromised, and committing to long-term follow-up of pulpal vitality, periodontal health, and radiographic appearance. For a rare anomaly within a rare anomaly, the case offers a replicable framework: recognize early with appropriate imaging, plan across specialties, prepare contingencies, and let orthodontics do more than straighten teeth.
Subject of Research: Multidisciplinary surgical and orthodontic management of a fusion between a permanent maxillary central incisor and a partially erupted supernumerary tooth
Article Title: The Multidisciplinary Management of A Fusion Involving a Permanent Maxillary Central Incisor and a Partially Erupted Supernumerary Tooth: A Case Report
Article References: Irvine, A., Juman, S., Marley, J., Fee, P., McNeill, A., & Johnston, C. (2026). The Multidisciplinary Management of A Fusion Involving a Permanent Maxillary Central Incisor and a Partially Erupted Supernumerary Tooth: A Case Report. Clinical Case Reports, 14(9), Article e73560. https://doi.org/10.1002/ccr3.73560
Image Credits: AI Generated
DOI: 10.1002/ccr3.73560
Keywords: tooth fusion, supernumerary teeth, CBCT, orthodontics, oral surgery, dental anomaly, case report, maxillary incisor, multidisciplinary care, pediatric dentistry, 3D imaging, dental pulp vitality
Cite Scienmag News
APA
MLA
Chicago
Ophelia Keating. (September 23, 2026). Rare Fused Tooth Case Shows How 3D Imaging Saved a Teenager’s Smile. Scienmag. https://scienmag.com/rare-fused-tooth-case-shows-how-3d-imaging-saved-a-teenagers-smile/
Ophelia Keating. “Rare Fused Tooth Case Shows How 3D Imaging Saved a Teenager’s Smile.” Scienmag, 23 September 2026, https://scienmag.com/rare-fused-tooth-case-shows-how-3d-imaging-saved-a-teenagers-smile/. Accessed 23 September 2026.
Ophelia Keating. “Rare Fused Tooth Case Shows How 3D Imaging Saved a Teenager’s Smile.” Scienmag. September 23, 2026. https://scienmag.com/rare-fused-tooth-case-shows-how-3d-imaging-saved-a-teenagers-smile/
Copy citation
Download RIS
Tags: 3D imaging3D imaging in dentistrycase reportCBCTcomplex dental anomaly managementdental anomalydental fusion and supernumerary teeth prevalencedental pulp vitalitydevelopmental dental fusionmaxillary incisormaxillary incisor anomaliesmultidisciplinary caremultidisciplinary dental treatmentoral surgeryorthodontic planning with 3D imagingorthodonticspediatric dentistrypreserving aesthetic teeth in teenagersrare dental developmental disordersRare fused tooth casesignificance of 3D imaging in oral surgerysupernumerary teethsupernumerary teeth in adolescentstooth fusion
