The case
In April 2023, a 17-year-old female was referred to the University of Yamanashi for extraction of impacted third molars found at a routine dental visit. A panoramic radiograph showed all four third molars completely impacted and, distal to each maxillary third molar, a bilaterally symmetrical pair of tooth-like radiopaque structures. CT with 3D reconstruction confirmed the key finding: two independent supernumerary teeth on each side, each with its own crown and root morphology, sitting behind the upper wisdom teeth. In July 2023 the surgical team extracted eight teeth under general anesthesia: both lower third molars and the upper third, fourth, and fifth molars on both sides. Each extracted tooth was independent, with no fusion to neighbors and no oroantral communication, and all four supernumerary teeth looked like molars on gross examination. The one-year follow-up was uneventful.
How rare the count is
The authors anchor the rarity with literature numbers. Reported supernumerary tooth prevalence runs 0.1% to 3.8%, and the maxillary molar region accounts for about 11.0% of cases. Fifth molars are described as extremely rare. Among children aged 5 to 15 with supernumerary teeth, 4.6% had three or more, and in one cited series only 2.4% (6 of 251) of affected individuals had five or more. The authors state that only ten cases of bilateral maxillary fourth molars, including this one, have been reported, and that four of the ten came from Japan, which they note as a possible regional pattern rather than a measured one. In cited series, supernumerary teeth overall are reported more often in Black populations (6.4%) than White populations (0.9%), and in Asian populations (2.7%) than White populations (1.6%); those comparisons are the authors’ cited literature, not data from this case.
What the report does not show
The limits are stated plainly and matter for reading the anatomy. No histopathology was performed on the extracted specimens, so the dental tissue composition was never microscopically confirmed and odontoma could not be definitively excluded, even though the CT appearance and gross molar morphology argue against it. This is one patient, one center, one surgical episode: it establishes that a symmetric fourth-plus-fifth molar pattern occurs, not how often, and not through what mechanism. The genetic and racial-prevalence discussion is a literature summary inside a case report, not new evidence. Nothing here was followed over developmental time, so the report cannot say when the extra teeth formed or why.
Where it sits in the field
The piece moves nothing in the current pass (2026-10-05): it is clinical anatomy, not regeneration evidence, and no program tier changes. It still belongs in the record for the tooth-number question. The bioengineered tooth germ route, and the anti-USAG-1 work behind it, is built on the discovery that loosening one brake on tooth-number signaling can yield extra, morphologically normal teeth in animals; this case is the natural, unmanipulated extreme of the same variable, a human dentition that produced two molars beyond the third. The authors themselves frame supernumerary molars under phylogenetic atavism and spatial variation in the successional dental lamina, the developmental territory the germ program works in. The honest boundary: a supernumerary fourth or fifth molar is an anomaly of the existing dentition, not a functioning third dentition, and no claim of regenerative relevance is made or supported by the paper.
Where we differ from the coverage
There is no press coverage of this case, so the comparison is with how extra-molar cases tend to circulate, as human-interest items about people “growing a third set of teeth.” That framing overreads what is on the radiograph. Four extra molars in a teenager is a striking count, but these are supernumerary teeth of the permanent dentition, surgically removed because of impaction and inflammation risk, not a usable spare set. The genuinely notable points are quieter: symmetric fifth molars are scarce enough that this case is counted among ten in the literature, the 3D CT diagnostic chain is the part with clinical transferable value, and the absence of histopathology is a real gap, not a footnote.
Provenance: grounded in the full open-access text of Wakao et al. (2026), Cureus 18(9):e115718, DOI 10.7759/cureus.115718, read as the PubMed Central full text (PMC13633679); every number and attribution above was checked against that source. Method and sourcing standard at /method/.