What the paper is
Miriam Fatima Zaccaro Scelza, Pantaleo Scelza Neto and seven colleagues published “Biological Performance of a Nitrofurantoin-Based Triple Antibiotic Paste for Regenerative Endodontics” in the International Endodontic Journal on 23 September 2026 (doi:10.1111/iej.70276; PMID 42775408). The work was funded by FAPERJ, the Rio de Janeiro state research foundation (award E-26/211.458/2021). The journal is subscription-only; this piece is grounded in the paper’s complete structured abstract as indexed by Europe PMC, together with the Crossref record for author names, date and funding. Every number below comes from that abstract. The study is in vitro: no patients, no extracted teeth, no animal model.
The design
The experimental paste (EXP) replaces the minocycline in the classic Hoshino triple antibiotic formulation with nitrofurantoin, at 4 mg/g nitrofurantoin plus 1 mg/g ciprofloxacin and 5 mg/g metronidazole. Minocycline is a documented cause of dentin discoloration, which is the standing argument for non-staining substitutes. EXP was compared against two commercial Hoshino pastes (ciprofloxacin, metronidazole and minocycline at 1 or 5 mg/g, named Hoshino 1 and Hoshino 5) and a calcium hydroxide paste. Human dental pulp stem cells were exposed for 24 hours to extracts at 0.2 g/mL. Cytotoxicity was read four ways (XTT, Neutral Red, Crystal Violet and Live/Dead imaging), and 27 cytokines, chemokines and growth factors were quantified in the supernatants by multiplex immunoassay, with Kruskal-Wallis and Dunn-Holm post hoc testing.
The results, as reported
EXP maintained approximately 75 percent metabolic activity and showed a less severe cytotoxic profile than the Hoshino formulations. On the Neutral Red assay, which reads lysosomal integrity, EXP preserved significantly more intact cells than Hoshino 1, Hoshino 5 and the calcium hydroxide paste, and Live/Dead imaging supported greater viability with EXP. The cytokine panel separated the medicaments more clearly than the viability assays: Hoshino 5 significantly reduced IL-2, IL-5 and IL-8, while calcium hydroxide increased IL-6 and reduced IL-1β, IL-15, IL-17, VEGF and MIP-1β. Hoshino 1 and EXP differed from untreated control only on IP-10, and no cytokine differences occurred among the medicament-treated groups. The authors’ conclusion is comparative, not absolute: better cytocompatibility toward DPSCs than the conventional Hoshino formulations and better viability preservation than the tested calcium hydroxide paste, under these experimental conditions, and they pair it with previously demonstrated antimicrobial activity to argue EXP merits further investigation for regenerative endodontic procedures.
What it does and does not settle
For the pulp and dentine repair route, the logic of the study is sound: in a regenerative endodontic procedure the intracanal medicament must disinfect without killing the resident stem cells expected to repopulate the pulp space, so cytocompatibility on DPSCs is a real selection criterion, and a 24-hour extract exposure at clinical-range concentrations is a defensible first filter. The limits are equally clear. Exposure was 24 hours in a two-dimensional extract model, not the days-long dressing contact of actual treatment; the readouts are viability and secretion, not odontogenic differentiation or any outcome in a tooth; there is no infection model here, so the antimicrobial half of the case rests on prior work the abstract cites but does not show; and the roughly 75 percent metabolic activity figure means a quarter of metabolic activity was still lost, which the abstract does not discuss. Whether nitrofurantoin at these concentrations sustains the differentiation program a REP depends on is a question this paper does not answer.
Boundary, and where we differ from the coverage
This is one laboratory’s in vitro comparison, bounded as such, and it belongs in the route’s toolkit column rather than its evidence column. The field assessment does not change on this record. No press coverage of the paper exists as of 26 September 2026; if it is covered, the likely frame, that a new antibiotic paste could help regrow damaged teeth, would outrun a study that measured cell survival in culture dishes and is explicit that its case is comparative and preliminary. The record supports a narrower sentence: a FAPERJ-funded group has shown that a nitrofurantoin-based triple antibiotic paste is gentler on human pulp stem cells than the minocycline-containing standard or calcium hydroxide in vitro, which is a reasonable argument for testing it further, not a result in a patient.
Provenance: grounded in the complete structured abstract of Scelza et al. (2026), International Endodontic Journal, doi:10.1111/iej.70276, retrieved via Europe PMC (PMID 42775408) on 26 September 2026, with author names, publication date and funding confirmed against the Crossref record for the same DOI; the full text is subscription-only and was not available. See /method/.