What was tested

Wesam Osama Hassan, Ahmed ElSheshtawy, Manal Abdelbaki and Geraldine Ahmed, at the Faculty of Dentistry, Cairo University, ran a prospective, parallel-group randomized trial of regenerative endodontic therapy in mature teeth, published in BMC Oral Health on 12 October 2026 (DOI 10.1186/s12903-026-09924-w). The trial, registered as NCT05585359, enrolled 28 medically healthy adults aged 18 to 45 with mature permanent single-rooted anterior teeth, closed apices, pulp necrosis and chronic apical periodontitis. The sample size calculation called for 12 patients per group; 14 per group were randomized to allow for 15% dropout.

Both groups received the same disinfection protocol (double antibiotic paste for three weeks, 1.5% sodium hypochlorite, final 17% EDTA rinse) and the same 3 mm calcium silicate coronal barrier. The only difference was the scaffold: injectable platelet-rich fibrin (i-PRF, centrifuged 700 rpm for 3 min) mixed with vitamin C at roughly 250 µM (0.5 mL of a 100 mg/mL solution per 1 mL of i-PRF), versus i-PRF alone. Intentional apical bleeding was not performed. The primary outcome was periapical lesion area on cone-beam computed tomography (CBCT) at 12 months, with CBCT periapical index scores, standardized two-dimensional radiographs at 3, 6, 9 and 12 months, and numerical pain scores at 6 to 72 hours and one week as secondary outcomes.

What they found

Two participants in the control group dropped out, leaving 14 in the vitamin C group and 12 in the i-PRF-only group for the healing analysis; pain data covered all 28. Baseline lesion areas were comparable (CBCT median 28.7 mm², range 6.7 to 64.6, versus 29.0 mm², range 1.3 to 80.0; P = 0.734). At 12 months, both groups had healed substantially and the groups did not differ: median lesion area 3.5 mm² (range 0 to 26.8) versus 5.3 mm² (range 0 to 27.9), P = 0.981. The within-group reduction was statistically significant in each group (P = 0.001 each). CBCT-PAI scores and two-dimensional radiographs told the same story: no between-group differences at any postoperative point. The largest numerical gap was the two-dimensional percentage reduction at 9 months, minus 84.7% in the vitamin C group versus minus 60.7% with i-PRF alone, which did not reach significance (P = 0.077).

Postoperative pain was low in both groups, with no significant between-group difference at any time point (6 h: P = 0.442; 12 h: P = 0.150). Clinical success, defined as absence of percussion pain, swelling and sinus tract, was 100% in both groups (14 of 14 and 12 of 12). The single failure was in the control arm: a fractured restoration and loss of tooth structure with reinfection, managed with conventional root canal treatment.

What it does not show

This is a comparison between two i-PRF formulations, not against the conventional blood-clot regenerative protocol, so it cannot say whether either scaffold beats standard care. No pulp sensibility testing was done and no histology was obtained, so the radiographic healing is evidence of treatment response, not of regenerated pulp; the authors state this plainly. It is one center, a modest sample, and a 12-month window. The 250 µM vitamin C dose was chosen from in vitro literature rather than validated pharmacokinetics for the root canal environment. One registry note: the NCT05585359 record has never been updated past its October 2022 posting, so it still carries the stale status “not yet recruiting” and no results entry, even though the trial ran from April 2023 to January 2025.

Where it sits in the field

For the pulp and dentin repair program, this is a useful null result on the clinical wing of the route. Regenerative procedures in necrotic mature teeth now have randomized-trial support for periapical healing with platelet-concentrate scaffolds, and this trial answers a narrower question: does an inexpensive antioxidant add-on move the outcome? At this sample size, it does not. That narrows where future adjunct hunting should look and leaves the program’s standing questions, long-term histology and true pulp-dentin complex restoration, untouched. The current field assessment stands at /field/.

Where we differ from the coverage

We found no press or popular coverage of this trial to differ from. Against the paper’s own framing, we hold back one inference: the discussion attributes the vitamin C group’s significant pain decline over time (P = 0.001; no such trend in the control group, P = 0.075) to vitamin C’s antioxidant and healing effects, but every direct between-group pain comparison was non-significant. A within-group trend against a non-significant between-group contrast is a hypothesis, not a signal, and at n = 14 per group the honest reading is equivalence.

Provenance: grounded in the open-access full text (BMC Oral Health 26:1978, published 12 October 2026) and the ClinicalTrials.gov record NCT05585359, both retrieved and cross-checked for this piece; every number above was verified against the published text and tables. Method and sourcing standard at /method/.