Overview and definition
A mesiodens is a supernumerary tooth situated in or near the midline of the anterior maxilla, typically between the two maxillary central incisors, and is the most common supernumerary tooth.[1][2][3] It is a developmental dental variant, not a neoplasm or disease; it reflects an additional tooth bud beyond the normal complement rather than a pathologic lesion.[4][5] Reported prevalence in the general population ranges from 0.15% to 1.9%, with a male predominance of approximately 2–3:1.[6][7][8] Mesiodentes are usually small and conical but may be tuberculate or show heterogeneous morphology, and may occur singly or as multiples (double mesiodens being less common).[3][4] The term applies to the maxillary midline position; by contrast, supernumerary teeth in the mandibular midline are far rarer and not designated "mesiodens" in the strict anatomic sense, though analogous midline nomenclature has been proposed.[9] Etiology is incompletely understood, with dental lamina hyperactivity and genetic factors most commonly implicated.[5][6][7]
Radiographic findings
Recognition and location. A mesiodens is frequently an incidental finding during evaluation of delayed or asymmetric incisor eruption, or on routine imaging; most are impacted, commonly palatal to the central incisors.[7][10] Periapical, occlusal, and panoramic radiographs are standard, though superimposition of the anterior nasal spine and adjacent incisor roots can obscure it on periapical views, and panoramic blurring in the anterior zone contributes to missed detection.[1][2]
Appearance and orientation. It typically appears as a small conical radiopaque tooth-like structure near the midline; orientation may be normal, inclined, inverted (crown directed toward the nasal cavity), or transverse.[3][10][11] CBCT is the reference standard for precise localization, orientation, and relationship to adjacent roots, and is particularly valuable before any surgical planning.[3][10][12]
Mimics and discriminators. Chief considerations are distinguishing a true mesiodens from a normally positioned or dilacerated central incisor, odontoma, and superimposed anatomy such as the anterior nasal spine; three-dimensional imaging resolves most ambiguity.[1][3][11]
Management and prognosis
An isolated, asymptomatic mesiodens is an incidental developmental variant, and interpretation should focus on whether it is causing or threatens to cause complications in the adjacent dentition.[4][8] Documented complications occur in roughly half of affected patients and include midline diastema, delayed or ectopic eruption, displacement, rotation, root resorption of adjacent teeth, cystic change, and rarely nasal eruption.[8] These findings are the principal red flags prompting referral to a specialist for surgical and/or orthodontic evaluation.[6][8] Current narrative evidence favors early surgical intervention around 6–7 years of age when an impacted mesiodens threatens developing incisors, balanced against the risk of iatrogenic injury to adjacent tooth germs; management is best risk-stratified by morphology, position, and age.[6][13] CBCT-based assessment guides surgical approach selection.[10][12] Formal treatment decisions are beyond the scope of this entry and should be individualized by the treating team.