Covadonga Sanchez PADILLA, Oliver Valencia DE PABLO, Ruth PEREZ-ALFAYATE, Antonio J CONDE VILLAR, Gaizka LOROÑO, Borja AGUILAR, Giampiero ROSSI-FEDELE, Roberto ESTEVEZ
European Endodontic Journal - 2026;11(2):82-89
Objective: To compare the efficacy of sodium hypochlorite (NaOCl) combined with ethylenediaminetetraacetic acid (EDTA), etidronic acid (HEDP), or Keratobacter (KB; a glycocholic acid-based solution with surfactants), for smear-layer removal, using subsonic agitation during the final rinse. Methods: Following decoronation, 40 human central mandibular incisors (single-canal) were randomly assigned into one of 3 experimental groups (n = 12 each) based on the irrigant solution used (NaOCl + EDTAfinal, NaOCl + HEDP , and NaOCl + KB) or used as control specimens: positive controls (irrigation omitted) or negative controls (no chemo-mechanical preparation) (n = 2 per group). Experimental groups were prepared using reciprocating instruments and irrigated with the respective solutions, with the chelator omitted for the NaOCl + EDTAfinal group at this stage. The teeth were then split, scanned with an electron microscope, and the smear layer was scored (0-3) at 3 levels by 2 blinded examiners. The reassembled specimens underwent a final rinse with the relevant solutions incorporating subsonic agitation, after which they were disassembled, and the remaining smear layer was scored as before. A non-parametric Brunner-Langer model of longitudinal data was estimated for the cleaning results for each of the levels. Then, an ATS-type ANOVA statistical test was used to analyze the effect of the irrigant, the treatment stage, and the interaction between them. The Mann-Whitney test with Bonferroni correction was used for multiple comparisons between irrigants in each phase. The significance level for all analyses was 5%. Results: Following instrumentation, negative controls were scored 0, and positive controls were scored 3. NaOCl + KB was associated with significantly lower scores compared to NaOCl + EDTAfinal and NaOCl + HEDP (coronal and apical levels) (P < .001). After the final rinse, NaOCl + KB showed significantly lower scores compared to NaOCl + HEDP coronally (P = .015), with the final rinse being associated with significantly lower scores solely for NaOCl + KB at the middle and apical levels (P = .002). Conclusions: NaOCl + KB had the lower scores for smear layer compared to the other experimental groups, with the final rinse enhancing smear layer removal for NaOCl + KB.
