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The Great Rinse Debate: NaOCl, EDTA, and the Question of Saline in Endodontic Irrigation

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Endodontic irrigation protocols spark nearly as much debate as bubbles in the canal. Ask five dentists how they sequence irrigants, and you’ll probably get at least seven fiercely defended methods. A persistent question: should we slip a saline rinse between sodium hypochlorite (NaOCl) and EDTA, or end with saline altogether?


I reviewed the literature again—and with the release of a 2024 expert consensus, the conclusions are clearer than ever.


1. Understanding the Players


  • Sodium Hypochlorite (NaOCl)

    The gold standard for disinfection and organic tissue dissolution. Its active component—available chlorine—breaks down necrotic tissue and bacteria, especially when activated to reach complex canal anatomy.

  • 17% EDTA

    A chelating agent that removes the smear layer and opens dentinal tubules, allowing deeper penetration of irrigants and sealers. It has little to no inherent antimicrobial effect.


2. The Chemistry Problem: NaOCl + EDTA


When NaOCl meets EDTA, available chlorine is immediately consumed, sharply reducing the tissue‑dissolving and antimicrobial abilities of NaOCl (Zehnder, 2006; Rossi‑Fedele et al., 2012).


  • This interaction is not the same as the brown precipitate formed by NaOCl + CHX.

  • The clinical concern isn’t precipitate—it’s loss of NaOCl efficacy.

  • That’s why the sequence matters: after EDTA, reintroducing fresh NaOCl restores antimicrobial potential in freshly opened dentinal tubules.


3. The “Saline Between” Argument


Some suggest saline between NaOCl and EDTA to prevent chemical interaction.


  • Saline may dilute residues but does not reverse EDTA’s chlorine-neutralizing effect. Once EDTA inactivates NaOCl, only fresh NaOCl restores activity (Rossi‑Fedele et al., 2012).

  • The “precipitate risk” applies to NaOCl + CHX, not NaOCl + EDTA (Basrani et al., 2007).

  • Saline isn’t harmful—but in this sequence, it adds no clinical benefit.


4. Fresh Evidence from 2024 Expert Consensus


A March 2024 expert consensus in the Int J Oral Sci underscores gaps in standardizing irrigation protocols and reinforces the logic of NaOCl–EDTA–NaOCl:


  • Root canal anatomy limits mechanical cleaning, making chemical irrigation essential for infection control and improving treatment outcomes—especially considering issues like apical vapor lock  .

  • The consensus reviews irrigant properties, interactions, and modern activation techniques (sonic, ultrasonic, laser, negative pressure) to optimize irrigation  .

  • They recommend the following final irrigation protocol:

    NaOCl (2.5–5.25%) → 17% EDTA → Fresh NaOCl, precisely in that order, to achieve both smear-layer removal and antimicrobial efficacy  .


5. The Evidence-Based Final Rinse Protocol


Based on current evidence, including the recent consensus:


  1. Fresh NaOCl (2.5–5.25%), activated for 30–60 sec

  2. 17% EDTA, activated for 30–60 sec to remove smear layer

  3. Fresh NaOCl, for ~30 sec, activated—restoring disinfection power in opened dentinal tubules

  4. Optional final: 95% ethanol rinse to dry and enhance sealer penetration (Marending et al., 2007)

  5. Dry with sterile paper points and obturate


This clean sequence removes the need for saline—unless transitioning to CHX, which does require an intermediate rinse.


6. Key References


  • Zehnder M. Root canal irrigants. J Endod. 2006;32(5):389–398.

  • Rossi‑Fedele G et al. Antagonistic interactions between NaOCl, EDTA, CHX. J Endod. 2012;38(4):426–431.

  • Basrani B et al. NaOCl + CHX interaction. J Endod. 2007;33(8):966–969.

  • Marending M et al. Ethanol as final rinse. Int Endod J. 2007;40(8):703–710.

  • Zou X et al. Expert consensus on irrigation and intracanal medication in root canal therapy. Int J Oral Sci. 2024;16:23—standardizes guidelines and supports NaOCl → EDTA → NaOCl sequence  .


Final Thoughts


The NaOCl–EDTA–NaOCl sequence is not only safe but also supported by strong evidence for maximizing disinfection and smear layer removal. Saline in between? Not harmful, but unnecessary for this pairing. Like many things in dentistry, the key is understanding the why behind your protocol—so every rinse is purposeful, not just habitual.


The NaOCl–EDTA–NaOCl sequence is not just textbook—it’s evidence-based and now consensus-backed. Saline in between? Not harmful but unnecessary. Armed with this rationale, your irrigation protocol is intentional, effective, and clinically defensible.

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