Endodontic Irrigation Pertot W.J. & Simon S. — Complete Guide

01

Why Canal Irrigation is Critical

A fundamental step that is frequently underestimated

Canal irrigation is the most important step in endodontic treatment for cleaning, disinfecting and preparing the canal system. Instrumentation alone does not clean — it shapes. It is irrigation that eliminates bacteria, organic debris and necrotic pulp tissue that instruments cannot reach.

Effective irrigation is the prerequisite for a hermetic obturation and lasting periapical healing.

Objectives of canal irrigation

Objective	Primary agent responsible	Importance
Elimination of bacteria and biofilms	NaOCl	Critical
Dissolution of necrotic pulp tissue	NaOCl	Critical
Instrument lubrication during shaping	EDTA gel	Critical
Smear layer removal	EDTA liquid	Critical
Canal debris evacuation	NaOCl + flow	High
Decalcification and penetration facilitation	EDTA gel	High

Core concept — Pertot & Simon, 2004 The Pertot-Simon sequence is built on the complementarity of two agents: sodium hypochlorite for organic tissue dissolution and disinfection, and EDTA (gel + liquid) for mineral chelation and smear layer removal. Neither agent alone can fulfil all irrigation objectives.

02

The Irrigating Agents — Overview

Sodium hypochlorite (NaOCl)

Reference agent — global gold standard

Dissolves organic tissue (pulp, necrosis, biofilm)
Broad-spectrum antibacterial activity — including anaerobes
Available in concentrations from 0.5% to 5.25%
Low cost and widely available (including in Algeria)
Does not dissolve mineral debris (smear layer)

EDTA (ethylenediaminetetraacetic acid)

Chelating agent — smear layer removal

Chelates calcium ions — selective demineralisation
Removes the smear layer left after instrumentation
Exposes dentinal tubules for better sealer penetration
Available as a gel (instrumentation) and 17% liquid (final rinse)
Does not dissolve organic tissue

Property comparison of principal irrigants

Property	NaOCl	EDTA liquid 17%	EDTA gel
Organic tissue dissolution	Excellent	None	None
Antibacterial activity	High	Moderate	Low
Smear layer removal	None	Excellent	Partial
Instrument lubrication	Low	None	Excellent
Periapical biocompatibility	Irritant	Moderate	Good

03

NaOCl — Mechanism of Action and Concentrations

Biochemical mechanism of action

Sodium hypochlorite acts through chlorination and oxidation of bacterial cellular proteins. In aqueous solution, it dissociates into hydroxyl ions (OH⁻) and hypochlorous acid (HOCl), which penetrates the bacterial cell membrane and causes irreversible lysis of structural proteins.

Its capacity to dissolve organic tissue (proteolysis) is unique among irrigants — no other agent is capable of dissolving residual pulp tissue.

Concentrations — Efficacy vs biocompatibility trade-off

Concentration	Antibacterial efficacy	Tissue dissolution	Periapical toxicity	Recommended use
0.5%	Moderate	Low	Very low	Primary teeth, sensitive patients
1.0%	Good	Moderate	Low	Routine — good general compromise
2.5%	Very good	Good	Moderate	Recommended by Pertot & Simon — standard
5.25%	Excellent	Excellent	High	Extensive necrosis — maximum precautions

Heated NaOCl — significantly enhanced efficacy Heating NaOCl to 37–45°C (body temperature or slightly above) doubles or triples its tissue dissolution capacity without increasing toxicity. This simple practice, achieved with a solution warmer or water bath, significantly improves clinical effectiveness.

04

EDTA — Gel and Liquid: Two Distinct Roles

EDTA gel — Instrument lubrication

Intraoperative use — applied to instruments

Applied directly onto instruments before canal introduction
Lubrication allowing smoother file progression
Partial decalcification facilitating instrumental penetration
Reduces instrument stress — prevention of fracture
Examples: RC-Prep, Glyde File Prep, EndoGel, Calcinase Slide

EDTA liquid 17% — Final rinse

Post-shaping use — smear layer elimination

Administered only after complete canal shaping
1–3 minutes contact on canal walls — agitation recommended
Eliminates the mineral smear layer left by instruments
Exposes dentinal tubules — improves obturation sealer penetration
Mandatory NaOCl rinse after EDTA (neutralisation and final disinfection)

Never mix NaOCl and EDTA simultaneously in the canal Immediately combining NaOCl and EDTA in the same space causes precipitation and mutual inactivation of both agents. Always rinse with NaOCl after EDTA — never alternate without an intermediate rinse.

05

Pertot-Simon Sequence — Step by Step

1

Initial rinse — Access cavity completed

Immediately after the access cavity is completed, a copious NaOCl flush is performed to eliminate coronal debris and prevent any contamination of the pulp chamber. The chamber is kept full of NaOCl for the entire duration of treatment.

Agent: NaOCl 2.5% — Generous volume

2

EDTA gel — Before initial hand instrumentation

A thin coat of EDTA chelating gel is applied to manual files (K-files) before canal introduction. This gel lubricates and facilitates wall decalcification, making progression smoother and reducing the risk of instrument fracture.

Agent: EDTA gel (RC-Prep / Glyde / EndoGel)

3

Intermediate irrigation — Throughout the entire instrumentation phase

Throughout the shaping phase, systematic NaOCl irrigation is performed after each instrument withdrawal. This continuous irrigation dissolves released organic debris and maintains canal system disinfection.

Agent: NaOCl 2.5% — After every instrument

4

EDTA gel — Before each NiTi rotary instrument

Before using NiTi rotary instruments, a fresh application of chelating gel is made to each instrument. This step protects instruments against excessive cyclic stress and improves their progression through curved segments.

Agent: EDTA gel — Before every rotary file

5

Final EDTA liquid 17% rinse — After complete shaping

At the conclusion of shaping, a final rinse with 17% EDTA liquid for 1 to 2 minutes removes the mineral smear layer from the canal walls. This rinse is followed immediately by an NaOCl flush to neutralise the EDTA and achieve final disinfection.

Agent: EDTA 17% (1–2 min) → NaOCl (final flush)

6

Drying and obturation

Canals are carefully dried with sterile paper points matched to the preparation size, without cotton wool pledgets that may leave fibres. Drying quality directly determines the adhesion of the obturation sealer to the canal walls.

Sterile paper points — Residue-free drying

06

Irrigant Activation — Beyond Passive Irrigation

Why activate irrigants?

Passive irrigation by simple needle injection creates limited flow, insufficient to penetrate uninstrumented areas, isthmi and canal ramifications. Activation techniques significantly improve irrigant penetration and efficacy.

Passive ultrasonic irrigation (PUI)

Gold standard of activation — recommended

Ultrasonic inserts without apical pressure — vibration only
Creates acoustic micro-streaming in the irrigating solution
Penetrates uninstrumented areas, isthmi and ramifications
3 cycles of 20 seconds after each main irrigation
Improves disinfection efficacy by up to 50% vs passive irrigation

Mechanical activation (SAF, XP-endo Finisher)

Specialised mechanical agitation systems

SAF (Self-Adjusting File): simultaneous shaping + irrigation
XP-endo Finisher: thermosensitive NiTi wire — expands at 37°C
Cleans areas unreached by conventional rotary shaping
Particularly effective in oval and flattened canals

PUI Activation Protocol — Optimal Sequence

To be performed after canal shaping, before the final EDTA rinse.

NaOCl activation (disinfection)

Fill the canal with NaOCl 2.5%
Ultrasonic insert at 1 mm from working length — no apical pressure
Activate 20 seconds × 3 cycles — renew NaOCl between each cycle

EDTA 17% activation (smear layer removal)

Fill the canal with 17% EDTA liquid
Activate 20 seconds × 3 cycles
Immediate final NaOCl flush afterwards

07

Safety — Preventing Irrigation Accidents

NaOCl accident — the most severe accident in endodontics Extrusion of NaOCl into periapical tissues causes immediate tissue necrosis, severe pain, rapid facial swelling and may require hospitalisation. Prevention is absolute — there is no simple treatment once the accident has occurred.

Extrusion risk factors

High-risk situations

Needle wedged in the canal — backflow impossible
Excessive or sudden injection pressure
Widely open apex (open apex, resorption)
Irrigation at working length without precautions
NaOCl concentration above 5% without specific indication

Systematic prevention measures

Safety rules — apply at every session

Side-vented, closed-end needle — mandatory standard
Position needle 2–3 mm short of working length
Gentle, continuous injection pressure — never sudden
Never wedge the needle in the canal — free withdrawal ensured
Verify free passage of irrigant before injecting
Simultaneous aspiration at the pulp chamber level

08

Equipment and Needles

Needle selection — Safety as the priority criterion

Needle type	Tip	Safety	Recommended use
Side-vented needle (Max-i-Probe, NaviTip)	Closed	High	Standard — recommended for daily use
End-vented needle (conventional)	Open	Low	Avoid — major extrusion risk
NaviTip FX (activation)	Closed + flexible	High	Curved canals — excellent penetration
Ultrasonic inserts (Irrisafe, Irri-S)	Rounded	Good	PUI activation — complete protocol

Essential equipment for the Pertot-Simon protocol

5 mL or 10 mL syringes with Luer-Lock connector
Side-vented, closed-end needles (27G or 30G depending on canal diameter)
Freshly prepared or commercial NaOCl 2.5% solution
EDTA gel (RC-Prep, Glyde File Prep, EndoGel or equivalent)
17% EDTA liquid for the final rinse
Sterile paper points (ISO 15 to 40 depending on preparation)
Endodontic aspiration system or surgical suction

09

Advantages of the Pertot-Simon Sequence

Clinical advantages

Documented outcomes

Optimal cleaning — organic dissolution (NaOCl) + mineral removal (EDTA)
Constant lubrication — safer instrument progression
Reduced instrument fracture risk through EDTA gel
Smear layer eliminated — better sealer penetration and adhesion
Significant reduction in post-operative infectious complications

Practical advantages

Reproducibility and accessibility

Simple, clear and reproducible protocol — applicable in routine practice
Accessible products — NaOCl available in Algeria (pharmacies, distributors)
No mandatory specialist equipment for the basic version
Compatible with all shaping systems (NiTi rotary, reciprocating)
Quick to learn — protocol memorisable within a few sessions

Reference standard since 2004 The sequence published by Pertot W.J. and Simon S. in 2004 has become a reference in French-speaking endodontics. It is built on the NaOCl/EDTA complementarity principle and has been widely validated by clinical practice and contemporary endodontic literature.

10

Clinical FAQ

For routine practice, a concentration of 2.5% represents the best compromise between antimicrobial efficacy, tissue dissolution capacity and biological tolerability. This is the concentration recommended by Pertot & Simon. 5.25% is reserved for cases of extensive necrosis with significant periapical infection, with maximum sealing precautions to avoid extrusion. In Algeria, domestic sodium hypochlorite solution (bleach) can be diluted to obtain a 2.5% concentration, but the use of medical-grade products with a guaranteed concentration is recommended.

The NaOCl rinse after EDTA liquid is indispensable for two reasons: (1) EDTA neutralisation — if residual EDTA remains in contact with the walls at obturation, it can interfere with sealer setting and compromise the bond between sealer and dentine; (2) Final disinfection — EDTA has no significant antibacterial activity; the final NaOCl flush ensures disinfection of the dentinal wall now free of its smear layer, with NaOCl penetrating the exposed tubules for in-depth disinfection.

No, they are not interchangeable because they serve distinct roles. EDTA gel is designed for instrument lubrication during instrumentation — its viscosity keeps it in contact with the instrument and facilitates progression. Its chelating action is limited and localised. 17% EDTA liquid is designed as a rinsing irrigant — it penetrates all canal walls, creates sufficient contact time to chelate the mineral smear layer and is easily evacuated by the subsequent rinse. Using EDTA gel alone for the final rinse would be insufficient to correctly eliminate the smear layer.

Recommendations vary among authors, but current data suggests more generous volumes than typically practised. For a standard molar canal: NaOCl during instrumentation — minimum 2 mL per intermediate rinse, equating to approximately 10–15 mL total per canal across the entire session; Final EDTA liquid — 3–5 mL over 1–2 minutes of activation. The pulp chamber must remain constantly filled with NaOCl — if it empties, the canal is exposed to recontamination. Irrigation quality is determined by volume, contact time and activation combined.

Chlorhexidine (CHX) 2% has excellent antibacterial properties and prolonged substantivity (residual effect), but it presents a major limitation in endodontics: it does not dissolve organic tissue. In the presence of residual pulp tissue or necrosis, it is therefore insufficient as the sole irrigant. It may be used as an adjunct to NaOCl in certain situations (documented NaOCl allergy), but cannot replace it in the Pertot-Simon sequence. Warning: CHX and NaOCl must never be mixed — they form a brown toxic precipitate (parachloroaniline).

For primary teeth and paediatric patients, the sequence is adapted with specific precautions: (1) Reduced NaOCl concentration to 0.5–1% to minimise irritation risk in the event of accidental extrusion; (2) Reduced volume and even gentler pressure — primary apices are often widely open; (3) Very short needles positioned well short of the apex; (4) EDTA gel remains indicated for lubrication. In apexification or widely open apex cases, some practitioners prefer saline as the primary irrigant with NaOCl at very low concentration used coronally only.

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References

Pertot WJ, Simon S. Irrigation endodontique. Réalités Cliniques. 2004;15(3):219-232.
Haapasalo M, Shen Y, Qian W, Gao Y. Irrigation in endodontics. Dent Clin North Am. 2010;54(2):291-312.
Zehnder M. Root canal irrigants. J Endod. 2006;32(5):389-398.
Moorer WR, Wesselink PR. Factors promoting the tissue dissolving capability of sodium hypochlorite. Int Endod J. 1982;15(4):187-96.
van der Sluis LW, Versluis M, Wu MK, Wesselink PR. Passive ultrasonic irrigation of the root canal. Int Endod J. 2007;40(6):415-426.
Teixeira CS, Felippe MC, Felippe WT. The effect of application time of EDTA and NaOCl on intracanal smear layer removal. Int Endod J. 2005;38(5):285-90.