An ex vivo evaluation of submicron diamond irrigant using sonic agitation systems on the penetration of calcium silicate-based sealers into dentinal tubules

The smear layer influences dentine permeability and may compromise sealer penetration, which is critical for achieving an effective three-dimensional seal during root canal obturation. This ex vivo study evaluated whether a 500 nm submicron diamond irrigant (10 mg/mL) with sonic agitation improves smear layer removal and dentinal tubule penetration of a calcium silicate–based (CS-based) sealer. Forty eight single-rooted teeth were prepared to Protaper Gold F2 and allocated to four irrigation protocols ( n = 12): (a) 3% sodium hypochlorite (NaOCl) with manual irrigation (NaOCl-MI); (b) 3% NaOCl with sonic agitation (NaOCl-SA); (c) 17% ethylenediaminetetraacetic acid with sonic agitation (EDTA-SA); and (d) 3% NaOCl plus submicron diamonds with sonic agitation (NaOCl-D-SA). Smear-layer removal was scored on SEM images (Hülsmann) and compared using Kruskal–Wallis with Dunn’s test. After hydraulic condensation with Rhodamine B–labelled CS-based sealer, CLSM quantified maximum penetration depth and sealer coverage; variables were analyzed using linear mixed-effects models with Bonferroni-adjusted pairwise comparisons ( p < 0.05). NaOCl-D-SA and EDTA-SA achieved effective smear removal, whereas NaOCl-MI and NaOCl-SA were inferior. Sealer coverage was higher in NaOCl-D-SA than NaOCl-MI/NaOCl-SA and comparable to EDTA-SA. NaOCl-D-SA produced the greatest penetration depth, followed by EDTA-SA; across all groups, coronal and middle penetration depths tended to exceed apical depths. Our results suggested that submicron diamond irrigation with sonic agitation improved smear-layer removal and enhanced CS-based sealer penetration under ex vivo conditions. This approach warrants further in vivo and clinical evaluation.