Proposed differential diagnosis and classification of non-syndromic and syndromic supernumerary teeth

Supernumerary teeth (SPNs), as common odontogenic developmental anomalies, not only cause local complications such as dental crowding and impaction but also serve as key oral manifestations of multiple genetic syndromes. We report a case of multiple SPNs (7 teeth with an odontoma) in a 17-year-old Chinese male who presented without any genetic syndromes. Clinical examination revealed a permanent dentition exhibiting Angle Class II malocclusion with dental crowding, featuring an ectopically erupted tooth 34 positioned lingual to tooth 35, two supernumerary teeth in the lingual region of teeth 44-45, and partially erupted teeth 17 and 27. Comprehensive imaging revealed a compound odontoma palatal to teeth 24-25 and multiple supernumerary teeth in the mandibular arch, with no associated root resorption or genetic abnormalities. The final diagnosis was multiple Non-syndromic Supernumerary Teeth, for which staged surgical removal of the odontoma and impacted supernumeraries was planned. This case elucidates the core distinguishing features between Non-syndromic Supernumerary Teeth and Syndromic Supernumerary Teeth. Based on the clinical history, physical examination, imaging findings, and genetic testing, a final diagnosis of Non-syndromic Supernumerary Teeth was established for this patient. Building on this foundation, we established a four-step differential method comprising clinical screening, radiographic localization, genetic verification, and multidisciplinary coordination. This approach pioneers the proposal of tooth count as a primary indicator for syndromic risk, providing enhanced evidence-based guidance for early identification of genetic disorders.