What the two cases were
Qian Wu and Daniel J. Yen, at the Department of Endodontics, Dongyang People’s Hospital Affiliated to Wenzhou Medical University (Zhejiang, China), report two adolescents treated with regenerative endodontic treatment (RET) for severe inflammatory root resorption (IRR) in a mandibular premolar, published online 11 September 2026 in Experimental and Therapeutic Medicine (DOI 10.3892/etm.2026.13292). Case 1 was an 11-year-old boy whose fractured anomalous central cusp led to pulp necrosis and IRR so advanced that the apical root segment had separated completely at the mid-root level. Case 2 was a 15-year-old boy with external IRR, an open and anomalous apical foramen, thin canal walls, and a large periapical lesion; his prior treatment history was unclear. Both protocols followed the standard RET sequence: 1.5% sodium hypochlorite irrigation, a calcium hydroxide intracanal medicament for four weeks, 17% EDTA rinse, then a blood-derived scaffold and a 3 mm iRoot BP Plus coronal seal.
What happened on follow-up
In case 1, a periapical bleeding clot served as the scaffold. At one month the separated apical fragment had moved back into contact with the main root and the periapical radiolucency had resolved. But at 12 months the fragment had drifted mesially, no further mineral deposition was seen, and at 24 months the authors report the tooth asymptomatic and stable with a periodontal ligament space around both fragment and main root, while stating plainly that the newly mineralized tissue was insufficient to fully restore root continuity. In case 2, periapical bleeding was inadequate to fill the canal, so the clinicians aspirated blood from the maxillary terminal alveolar bone (an 18-gauge needle, less than 2 mm deep) and used that alveolar-derived autologous blood (ADAB) clot as the scaffold. The tooth never responded to vitality testing, but at 36 months the boy was asymptomatic, the periapical lesion had almost completely resolved radiographically, and the resorption had arrested. In both cases the guardians declined cone-beam CT, so the internal-versus-external classification and the three-dimensional position of the separated fragment rest on two-dimensional radiographs alone, a limitation the authors state rather than bury.
The scaffold claim, at its actual evidence level
The ADAB technique is the paper’s claimed novelty: first use of an alveolar-derived blood clot for root resorption, and a harvest a dentist can perform without a nurse or centrifuge, unlike platelet-rich plasma or fibrin. The authors are direct about where that stands. The ADAB platelet count is about 50% of peripheral venous blood in their prior measurement, the growth factor content relevant to pulp and bone repair is unknown, no comparison against conventional clots or platelet concentrates has been run, and the biological rationale leans on indirect evidence from bone marrow aspirate studies. Their own conclusion: the outcomes do not constitute proof of ADAB efficacy, and preclinical and clinical validation is required before it can be recommended for routine use.
Where this sits in the record
The paper’s own table of prior work shows the state of the evidence: RET for inflammatory root resorption rests almost entirely on case reports and case series, with only a handful of small clinical trials (10, 20, and 92 patients) behind it. These two cases extend that series at its severe end: after disinfection plus a blood scaffold, resorption arrested in both teeth, the slight lesion in case 1 resolved within a month, and the large lesion in case 2 had almost completely resolved by three years. They do not show regenerated pulp: case 2 never responded to vitality testing, and in case 1 the structural defect persisted. For the pulp-dentin repair program, this is human clinical evidence at the case-report tier, below the program’s small autologous pulp stem cell trial in immature incisors, and it does not move anything on the current field assessment. The honest watch item is whether anyone tests the ADAB scaffold against a conventional blood clot in a design with more than two teeth and three-dimensional imaging, since without that comparison the cheaper, dentist-only harvest remains a hypothesis with a plausible mechanism, not a result.
Provenance: grounded in the full open-access text of Wu and Yen (2026), Experimental and Therapeutic Medicine 32: 297, DOI 10.3892/etm.2026.13292, read from the publisher’s PDF, plus this site’s ledger and program pages. Method and sourcing standard at /method/.