State of the field, fourth pass

Three weeks on, the ladder has not moved: one program has adult safety data and nothing more, the repair wing gained two small randomized trials and a sheep study, and nothing upstream of a person has changed.

Written 2026-10-25. This is the fourth pass; it supersedes the third pass of 2026-10-05, which stays published and unchanged in the archive. This pass is published ahead of the four-week cadence mark, at the site owner’s request; the evidence window is the three weeks since the third pass. Since the third pass, the pulp and dentin repair stream gained two small randomized trials, one a clean null result for a cheap adjunct and one a radiographic apical-closure result in children, plus a descriptive sheep study of a freeze-dried cell preparation. The bioengineered tooth germ program gained a named, marker-defined human progenitor population that repairs dentin, pulp-like tissue and bone in graft and rodent models and forms no tooth. A mouse knockout study mapped where USAG-1 sits in the circuitry of supernumerary incisor formation. None of it is human efficacy data for a third dentition, and no tier moved.

Program bases were re-checked against the research pool, the trial registries, and the sponsor’s disclosure pages. One re-verification this pass failed on its face: the jRCT registry host was unreachable from the pipeline host on the day of writing, so the lead program’s registry state is carried forward from the 2026-10-05 verification, which is 20 days old and inside the 120-day window. That gap is stated here rather than smoothed over.

Tier ladder

• Tier 5: Replicated human efficacy. Held by: nothing.
• Tier 4: Human efficacy or safety data, single program. Held by: anti-USAG-1 / TRG-035.
• Tier 3: Small or single-center human data, narrow endpoint. Held by: pulp and dentin repair.
• Tier 2: Animal result, no human protocol proposed. Held by: bioengineered tooth germ, dental epithelial organoids, tooth-root organoids.
• Tier 1: In vitro only, or mechanism without a tissue result. Held by: nothing at this pass.

Per-program assessment

Anti-USAG-1 / TRG-035 (Toregem BioPharma, Kyoto University): tier 4, held

The human program has still answered only one question: whether a single ascending dose is tolerated in adults. This pass attempted to re-verify the registry entry (jRCTa2051240154) and could not: the jRCT host did not respond from the pipeline host on the day of writing. The stated registry state therefore rests on the third pass’s verification of 2026-10-05: recruitment status Complete, a target of 30 healthy adult males aged 30 to 65, a single intravenous dose in five ascending steps, a primary endpoint of safety, and secondary endpoints of pharmacokinetics and anti-TRG-035 antibody frequency (kitano-2024-phase1). No outcome data is posted. A check of clinicaltrials.gov this pass found no TRG-035 record there, which is consistent with the US program still being pre-IND.

On the sponsor’s side, the three newsroom items since the third pass are all governance or business development, and none enters the record as a field event: selection for the Nakanoshima Qross startup-support stage (2026-10-02), a BioJapan 2026 exhibit announcement (2026-10-06), and a former minister’s visit to the company booth at the Global Startup Expo (2026-10-20). The latest disclosure that touches the science remains the 17 August 2026 completion of the PMDA clinical trial notification investigation for the Phase IIa trial (toregem-2026-pmda-ctn); no enrollment, no dosing, and no results for Phase IIa have been disclosed, and the sponsor’s own next disclosed step remains institutional ethics review at participating sites.

One biology result this window belongs to the program’s background rather than its evidence: a SOSTDC1 (USAG-1) knockout study mapped, at single-cell resolution, the Wnt-driven cell populations behind supernumerary maxillary incisor formation in mice. It sharpens the developmental picture of the drug’s target; it contains no antibody data and nothing from a person.

Tier 4 stands unchanged: human safety data exists for a single program, carried on a registry entry last verified 20 days ago, and nothing more. No peer-reviewed human result set is public and no efficacy endpoint has been tested in anyone.

What would change this assessment: an efficacy endpoint in the intended population, children with congenital anodontia, reported with its statistical plan rather than by press release; or a dated human image showing a tooth in a site that was radiographically empty before treatment. A re-verified registry entry would also restore the basis to fully current status.

Bioengineered tooth germ: tier 2, held

The window’s one publication-grade addition recharacterizes the program’s central gap, human cell sourcing, rather than closing it. Yu and colleagues profiled about 34,000 cells from six prenatal human mandibles by single-cell RNA sequencing and identified a surface-marker-defined odontogenic ectomesenchymal progenitor, SLITRK6-positive, that persists after birth in the apical papilla of immature permanent teeth and in the dental follicle of unerupted teeth (covered in the analysis stream). In a kidney-capsule transplant these cells formed DSPP-positive and DMP1-positive dentin-like matrix with mouse enamel-organ epithelium; in subcutaneous grafts they made pulp-like tissue; in a rat periodontal-bone defect they made alveolar bone. No transplant formed a tooth, the authors state this plainly, and the atlas is cross-sectional, so the reported differentiation paths are inference rather than lineage tracing. The honest summary is a named, prospectively isolatable human cell source for dental tissue engineering, with the same adult-sourcing scarcity the program has always had.

The mammal basis is otherwise untouched. A transplanted bioengineered tooth germ erupted, occluded, and responded to mechanical and pain stimuli in an adult mouse (2009, ikeda-2009); chemically defined culture supports mouse tooth reconstitution with BMP-driven enamel induction (zhang-2024-chemically-defined-tooth-reconstitution); and decellularized porcine tooth-bud scaffolds seeded with dental and endothelial cells form tooth-like tissues, including periodontal-ligament-like tissue with Sharpey’s fibers, in adult minipigs (zhang-yelick-2025-decellularized-tooth-bud). The qualifying results also stand: lingual-buccal positional memory persists in dissociated and reaggregated mouse dental mesenchyme (kim-2025-dental-mesenchyme-position), and the inductive tooth-germ secretome is not sufficient to replace living mesenchyme for tooth induction in mice (birjandi-sharpe-2025-tooth-germ-secretome, with the February 2026 publisher correction, birjandi-sharpe-2026-secretome-correction, replacing Figure 7 panels D-I, conclusions unchanged per the authors). A mouse syngnathia study of BMP4-dependent molar primordium segregation is developmental patterning, useful context and no capability result. No new mammal whole-tooth result appeared this window, and no human protocol has been proposed.

What would change this assessment: independent replication of tooth formation in a large animal by a group with no commercial stake, a credible human cell-sourcing plan, or reconstitution of a tooth germ from the new marker-defined human progenitor with developmental control demonstrated.

Dental epithelial organoids: tier 2, held

No news this pass that shifts the basis. The window’s only addition on this wing is an in-vitro characterization of dental epithelial cells derived from human deciduous dental pulp, a model-system result one step upstream of an organoid claim. The basis stands: human dental epithelial organoids with a stemness phenotype and in vivo assessment (hemeryck-2022) remain the tier basis, supported by a soluble Notch agonist maturing human ameloblast organoids to enamel-like mineral under the mouse kidney capsule (patni-2026-ameloblast-organoid), PITX2-positive embryonic oral epithelium induced from human pluripotent stem cells in ten days (nakashima-2025-oral-epithelium), and a biomimetic elastin-like matrix nucleating enamel-like mineral on acid-etched human enamel and dentin ex vivo (hasan-2025-biomimetic-enamel-restoration). The program sits at the organoid/model boundary, not at a replacement tooth.

What would change this assessment: organoid-derived enamel tissue of native thickness and orientation, integrated in a living jaw.

Tooth-root organoids: tier 2, held

No news this pass. The basis stands: self-assembled tooth root organoids from postnatal human dental stem cells organize dentin-, pulp-, cementum-, and ligament-like tissue with in vivo assessment (calabrese-2024), and the 2026 scaling result still constrains the route to a larger construct: smaller root-organoid constructs lose the layered mineral pattern, pointing to a minimum cell mass for proper patterning (calabrese-2026-root-organoid-scaling). Eruption, crown formation, innervation, and periodontal integration remain unresolved, and nothing has been placed in an animal jaw.

What would change this assessment: eruption, crown formation, innervation, and periodontal integration of an organoid-derived construct in an animal jaw.

Pulp and dentin repair: tier 3, held

The tier basis stands and the window’s three additions qualify it on every side: a human null result, a human radiographic result without histology, and a large-animal descriptive study. The tier still rests on the randomized trial of autologous deciduous-tooth pulp stem cell implantation in immature permanent incisors: 26 patients evaluated with 24-month imaging, regenerated pulp tissue with vessels and nerves (xuan-2018), supported by a 2026 small randomized trial of platelet-rich fibrin versus mineral trioxide aggregate for direct pulp capping in 20 adult molars, with borderline dentin-bridge volume difference and indistinguishable clinical outcomes (asthana-2026-prf-mta-pulp-capping), and qualified by the best available human histology after a regenerative endodontic procedure: dentin-like tissue without an organized odontoblast layer, sparse neurovascular ingrowth, apical osteoid, a single case with a contralateral control (yang-2026-rep-histology-human). Tideglusib dentin repair remains preclinical (neves-2017).

New this window, each short of the ladder’s human bar in a different way. First, a 28-patient Cairo University randomized trial found no added benefit from mixing vitamin C into injectable platelet-rich fibrin for regenerative endodontics in necrotic mature single-rooted teeth: CBCT periapical healing, pain and clinical success at 12 months were equivalent between groups, at 100 percent clinical success in both (covered in the analysis stream). It is a clean null result, it narrows where adjunct hunting should look, and it has no histology and no comparison against the conventional blood-clot protocol. Its registry record has never been updated past its 2022 posting, a reminder that registry status fields lag the literature. Second, a 60-patient Chennai randomized trial in children aged 7 to 9 found pulpotomy with PRF plus nanohydroxyapatite gave 90 percent complete or near-complete radiographic apical closure at 12 months versus 60 percent with PRF alone, a large and statistically sharp radiographic gradient (covered in the analysis stream). The endpoint is radiographic, with no histological ground truth, no mineral trioxide aggregate arm, and one center; the radiographic winner was also the only augmented arm with tenderness events, so superiority belongs to the endpoint, not the procedure. Third, a Tbilisi group reported vascularized pulp-like tissue with a predentin border 30 days after sheep pulpotomy filled with freeze-dried bone-marrow-derived cells on microcarriers in fibrin gel (covered in the analysis stream); the readout is descriptive histology with no scoring system, the transplanted cells were virtually undetectable by day 20 and the mechanism is paracrine rather than engraftment, so the honest summary is a storable cell-derived preparation, not a living graft.

None of this moves the tier. It thickens the human evidence that regenerative procedures in the pulp space work at the level of healing and radiographic maturation, and it sharpens the standing qualification: what is regrown in people remains repair-adjacent tissue, not a rebuilt pulp-dentin complex, let alone anything beyond the pulp space.

What would change this assessment: controlled human evidence that repair extends beyond the pulp space, true enamel regrowth rather than surface remineralization, or human histology showing an organized odontoblast layer and organized neurovascular ingrowth after a regenerative procedure.

Myth vs record

1. Claim: people born without wisdom teeth are predisposed to infertility. Verdict: unsupported. A Wake Forest commentary this window tested the folk claim against the developmental record and found no clinical, epidemiological, or embryological evidence for it, tracing the association to rare syndromes and folklore (covered in the analysis stream). Tooth number and reproductive function share no documented causal pathway. Agenesis remains a screening sign for some developmental syndromes, which is a different claim with real evidence behind it.
2. Claim: PRF plus nanohydroxyapatite is now the proven superior pulpotomy for immature teeth. Verdict: overstated. The new trial supports a radiographic-endpoint win in 60 children at one center, without histology and without a mineral trioxide aggregate comparison arm. That is a real result with a stated boundary, not a change of standard of care.
3. Claim: TRG-035 Phase IIa trials are underway. Verdict: still unsupported, restated from the third pass. The last disclosed scientific step is the completed PMDA clinical trial notification investigation of 17 August 2026 (toregem-2026-pmda-ctn); the sponsor has disclosed no enrollment, no dosing, and no results, and the registry entry could not be re-verified this pass, which is stated rather than assumed.

What would change the field-level assessment

1. A dated human image showing a tooth in a site that was radiographically empty before treatment.
2. An efficacy endpoint, in children, reported with its statistical plan rather than by press release.
3. Independent replication of tooth formation in a large animal by a group with no commercial stake.

Corrections applied this pass

• None logged since the third pass; the inbox is empty. The previously logged duplicate-analysis retirement from the third pass remains in force. One deferred item carried without change: the withdrawal decision on the duplicate regenerative-endodontics-versus-apexification page remains open, awaiting a deliberate on-record human decision.

Cited here

• kitano-2024-phase1: first-in-human Phase I announcement and registry record, single ascending dose, adults; registry last verified 2026-10-05, re-verification attempted and failed this pass.
• toregem-2026-pmda-ctn: PMDA CTN investigation completed for Phase IIa, 17 August 2026.
• toregem-2025-fda-preind: sponsor disclosure of FDA response to pre-IND meetings, 27 November 2025.
• toregem-2026-financing: Phase I complete and Phase II preparation disclosure, 19 May 2026.
• amed-2025-orphan: Japanese orphan drug designation for severe congenital partial anodontia.
• murashima-suginami-2021: anti-USAG-1 rescues tooth agenesis in mice and ferrets.
• moradi-2026-usag1-review: USAG-1 expression map and clinical-timeline review.
• hashim-2026-usag1-periodontal: USAG-1 as a candidate target for periodontal regeneration, review.
• ikeda-2009: bioengineered tooth germ functional in an adult mouse.
• zhang-2024-chemically-defined-tooth-reconstitution: chemically defined mouse tooth reconstitution.
• zhang-yelick-2025-decellularized-tooth-bud: decellularized scaffolds in minipigs.
• kim-2025-dental-mesenchyme-position: positional memory in dental mesenchyme.
• birjandi-sharpe-2025-tooth-germ-secretome: secretome does not replace living mesenchyme.
• birjandi-sharpe-2026-secretome-correction: publisher correction to that study.
• mubeen-2026-cichlid-tooth-replacement: cichlid whole-tooth regeneration, eLife version of record.
• hemeryck-2022: human dental epithelial organoids with in vivo assessment.
• patni-2026-ameloblast-organoid: Notch-agonist-matured ameloblast organoids, enamel-like mineral in mice.
• nakashima-2025-oral-epithelium: PITX2-positive oral epithelium from human pluripotent stem cells.
• hasan-2025-biomimetic-enamel-restoration: biomimetic enamel-like mineral ex vivo.
• calabrese-2024: self-assembled tooth root organoids from human dental stem cells.
• calabrese-2026-root-organoid-scaling: size scaling disrupts the layered mineral pattern.
• xuan-2018: randomized autologous pulp stem cell trial, 26 patients, 24-month imaging.
• asthana-2026-prf-mta-pulp-capping: PRF versus MTA direct pulp capping randomized trial.
• yang-2026-rep-histology-human: human histology after a regenerative endodontic procedure.
• neves-2017: tideglusib promotes reparative dentin in mice.
• Hassan et al. 2026, BMC Oral Health, doi:10.1186/s12903-026-09924-w: i-PRF plus vitamin C randomized trial, null adjunct result; analysis stream only, not yet in the keyed bibliography.
• Srinivasan et al. 2026, International Journal of Clinical Pediatric Dentistry 19(9), doi:10.5005/jp-journals-10005-3643: PRF plus nanohydroxyapatite pulpotomy randomized trial; analysis stream only.
• Kakabadze et al. 2026, American Journal of Stem Cells 15(1), doi:10.62347/rjpq4886: freeze-dried cell preparation, sheep pulpotomy; analysis stream only.
• Yu et al. 2026, Stem Cell Reports, doi:10.1016/j.stemcr.2026.103121: SLITRK6-positive human tooth-germ progenitor; analysis stream only.