The document provides an overview of various irrigants used in endodontics, summarizing their requirements, functions, advantages, and disadvantages. Key irrigants discussed include sodium hypochlorite, chlorhexidine, iodine potassium iodide, hydrogen peroxide, MTAD, citric acid, and EDTA, highlighting their unique properties and applications in dental treatments. It emphasizes that no single irrigant fulfills all needs, and the combination and sequential use of different irrigants are crucial for successful endodontic outcomes.

1. Irrigants in endodontics
1
Simply discussed
A summary of 4 endodontic textbooks
(Torabinejad &Walton, Pathways,
Weine and Ingle) and a review

2. By
Ahmed Mostafa Hussein
Assisstant lecturer
Dental Biomaterials Department
Faculty of Dentistry, Mansoura University, Egypt
2014
ahmadmostafahussein3@yahoo.com
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3. Requirements and functions of irrigants
1. Dissolve organic and inorganic tissue.
2. Remove smear layer. (Pathway)
Disinfecting and cleaning areas inaccessible to
endodontic instruments. (pathway)
3. Flush out and remove debris → prevent apical
blockage by debris. (Ingle)
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4. 4. Antimicrobial
5. Lubricant
6. Low surface tension
7. Don't weaken the tooth structure
8. Non-toxic and non-irritant
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5. Advantages of smear layer removal
(Walton & Weine)
1. Allows penetration of irrigants into dentinal tubules.
2. Enhances penetration and adhesion of sealer to dentin.
3. Filling materials adapt better to the canal wall.
4. Reduces coronal and apical leakage.
N.B: The small particles of the smear layer are primarily
inorganic. (Walton)
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6. Functions of lubricants (Pathway)
1. Facilitate the mechanical action of endodontic
hand or rotary files
2. Increase cutting efficiency → better removal of
debris
3. Reduce torque → the files and reamers are less
likely to break (Weine)
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7. Types of irrigants
Saline, sodium hypochlorite (NaOCl),
chlorhexidine(CHX), Iodine potassium iodide (IKI),
hydrogen peroxide (H2O2), MTAD,
citric acid (CA),
EDTA (lubricant, decalcifying and chelating agent)
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8. * No single irrigating solution covers all of the
functions required from an irrigant.
* The alternating use of different irrigants in
the correct sequence contributes to a
successful treatment outcome.
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9. 1. Saline (Review)
* Lacks antibacterial activity when used alone.
* Doesn't dissolve tissue.
* Has the risk of contamination if used from
containers that have been opened more than once.
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10. 2. Sodium hypochlorite (NaOCl)
* NaOCl is one of the most widely used irrigating
solutions.
* Household bleach such as chlorox contains 5.25%
NaOCl. (Ingle)
* Full strength (5.25%) NaOCl is highly irritating to
periapical tissues and reduces the flexural strength
& elastic modulus of dentin.
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11. * A common concentration of NaOCl is 2.5% which
decreases toxicity and still maintains some tissue
dissolving and antimicrobial activity.
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12. Advantages of NaOCl (Walton)
1. Dissolve organic tissue: NaOCl is the only root-
canal irrigant that dissolves necrotic and vital
organic tissue (unique property). (Review)
2. Antimicrobial action
3. Lubricant
4. Inexpensive and readily available
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13. Disadvantages of NaOCl
1. Irritant to periapical tissues, mucous membrane
and skin. (Ingle)
2. Unpleasant odour.
3. Can damage clothes.
4. The use of NaOCl as the final rinse following
EDTA or citric acid (CA) produces severe erosion
of the canal-wall dentin and should be avoided.
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14. 5. Causes haemolysis & ulceration, inhibits
neutrophil migration and damages endothelial &
fibroblast cells.
N.B: In vivo, the presence of organic matter
(inflammatory exudate and tissue remnants)
weakens NaOCl effect.
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15. 3. Chlorhexidine (CHX)
* Relative absence of toxicity. (Ingle)
* Broad spectrum antimicrobial substantive activity
(continued antimicrobial effect), because
chlorhexidine (CHX) binds (is adsorped) and
released gradually from the hydroxyapatite
surfaces. (Review)
* 2% CHX has similar antimicrobial action as
5.25% NaOCl and is more effective against
Enterococcus faecalis. (Walton)
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16. * Recent reports have indicated that several
disinfecting agents such as CHX, Iodine potassium
iodide (IKI) and Ca(OH)2 are inhibited in the
presence of dentin. (Pathway)
* The activity of CHX is greatly reduced in the
presence of organic matter. (Review)
* CHX cannot be the main irrigant in standard
endodontic cases, because CHX doesn't dissolve
the smear layer or necrotic tissue. (disadvantage)
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17. Indications of CHX
1) 2ry endodontic infections.
2) At the end of chemomechanical preparation,
because CHX doesn't cause erosion of dentin like
NaOCl does as the final rinse after EDTA.
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18. 4. Iodine potassium iodide (IKI)
* Iodine is less cytotoxic & irritating to vital tissues
than NaOCl & CHX, but obvious disadvantage of
iodine is a possible allergic reaction in some
patients.
* 2 & 4% Iodine potassium iodide (IKI) has
considerable antimicrobial activity, but no tissue-
dissolving property. It can be used at the end of
chemomechanical preparation like CHX.
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19. * Although Ca(OH)2 alone was unable to kill E.
faecalis inside dentinal tubules, Ca(OH)2 mixed
with either IKI or CHX effectively disinfected
dentin (may be able to kill Ca(OH)2-resistant
bacteria). (Pathway)
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20. 5. Hydrogen peroxide (H2O2) (Weine)
* H2O2 destroys anaerobic microorganisms.
* The solvent action of H2O2 is less than that of
NaOCl, so H2O2 is less damaging to periapical
tissues.
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21. * Many clinicians use the solutions (H2O2 & NaOCl)
alternately during treatment. This method is
strongly suggested for irrigating canals of teeth
that have been left open for drainage, because the
effervescence is effective in dislodging food
particles & other debris that may have packed the
canal.
* H2O2 shouldn't be the last irrigant used in a canal,
because nascent oxygen may remain and cause
pressure. Therefore NaOCl should be used to react
with H2O2 and liberate the oxygen remaining.
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22. 6. MTAD (Walton and review)
* Mixture of tetracycline isomer (doxycycline), an
acid (citric acid) & detergent.
* Biocompatible.
* MTAD may be superior to NaOCl in antimicrobial
action.
* MTAD is effective in killing E. faecalis found in
failing treatments.
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23. * Although earlier studies showed promising
antibacterial effects by MTAD, recent studies have
indicated that NaOCl/EDTA combination is
equally or more effective than NaOCl/MTAD.
(Review)
* MTAD helps in removal of smear layer.
* MTAD doesn't dissolve organic tissue.
(disadvantage)
* It doesn't alter physical properties of dentin.
* It could be used at the end of chemomechanical
preparation after NaOCl. (Review)
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24. 7. Citric acid (CA)
* EDTA & citric acid (CA) effectively dissolve
inorganic material, including hydroxyapatite.
(Review)
* Help in smear layer removal. (Walton)
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25. 8. EDTA (ethylene diamine tetraacetic acid)
* Lubricant, chelator & decalcifying agents.
* EDTA is the most effective chelating agent in
endodontic therapy.
* In general, files remove dentin faster than the
chelators can soften the canal walls. (Walton)
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26. * 17% EDTA for 1 min remove inorganic
components.
* EDTA is effective in smear layer removal only in
coronal & middle thirds, but not in the apical
third.
N.B: NaOCl is necessary for removal of organic
component.
* EDTA has little effect on periapical tissue.
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27. 27

28. Disadvantage of EDTA
Deactivation of NaOCl by reducing the available
chlorine. (Walton)
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29. Contraindications of EDTA (Weine page 225)
1) A ledged or blocked canal: If a sharp instrument
is forced or rotated against a wall softened by the
chelate, a new but false canal will be started.
2) Curved canals once the larger-sized instruments
(size 30 or greater) are being used. These
instruments are not as flexible as the smaller sizes
and may produce root perforation.
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30. Indication of EDTA
The best use of chelating agents is to aid and
simplify preparation for very sclerotic canals after
the apex has already been reached with a fine
instrument.
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31. * Chelating agents are placed in the orifice of a
canal to be enlarged on the flutes of the enlarging
instrument or by plastic syringe.
N.B: EDTA reacts with glass, so glass syringes of
that material may not be used. (Weine pages 224 & 225)
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32. Precaution
EDTA will remain active within the canal for 5 days
if not inactivated. If the apical constriction has been
opened, the chelate may seep out & damage the
periapical bone. For this reason, at the completion
of the appointment, the canal must be irrigated with
NaOCl to inactivate EDTA. (Weine page 226)
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33. Conventional irrigation by syringe
* Disposable 2.5 or 5 ml plastic syringes are useful
for endodontic irrigation. (Weine)
N.B: Larger syringes are difficult to control for
pressure, and accidents may happen. (Review)
* A commonly used needle is the 27-gauge needle
with a notched tip, allowing for solution flowback,
or the blunt-tip ProRinse. (Ingle)
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34. 34
Notched tip

35. 35

36. 36

37. Selected video from youtube:
www.youtube.com/watch?v=3FVXN1sCKf8
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38. * All syringes for endodontic irrigation must have a
Luer-Lok design. (Review)
* The irrigating needle must be placed loosely in the
canal. To control the depth of insertion, the needle is
bent slightly at the appropriate length or a rubber
stopper is placed on the needle. (Walton)
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39. 39
Luer-Lok design

40. * Irrigants must be gently placed within the canals.
It is the action of intracanal instruments that
distributes the irrigant into the canal. (Weine)
* The needle is moved up and down constantly to
produce agitation & prevent binding or wedging of
the needle. (Walton)
N.B: Severe complications have been reported from
forcing irrigating solutions beyond the apex by
wedging the needle in the canal and not allowing an
adequate backflow. (Ingle)
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41. * The irrigant doesn't move apically more than 1
mm beyond the irrigation tip. (Walton)
* The closer the needle tip to the apex, the greater
the potential for damage to the periradicular tissues.
* The volume of irrigant is more important than the
concentration or type of irrigant. (Ingle page 502)
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42. * The apical 5 mm are not flushed until they have
been enlarged to size 30 and more often size 40
file. (Ingle)
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43. * Separate syringes should be used for each irrigant
to avoid chemical reactions between them. (Review)
* N.B: Ultrasonics proved superior effect to syringe
irrigation alone when the canal narrowed to 0.3 mm
(size 30 instrument) or less. (Ingle)
* N.B: The US Army reported the importance of
recapitulation–re-instrumentation with a smaller
instrument following each irrigation. (Ingle page 503)
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44. Questions
What are the irrigants that can be used for final
irrigation and why?
* CHX, IKI and MTAD can be used at the end of
chemomechanical preparation, because they doesn't
cause erosion of dentin.
N.B: Some patients have allergy to iodine.
N.B: CHX has continued antimicrobial activity, why?
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45. * What are the irrigants that cannot be used for
final irrigation and why?
1) EDTA: why?
2) NaOCl: why?
3) H2O2: why?
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46. Main references
1. Torabinejad M, Walton RE. Endodontics principles and
practice. 4th ed. Saunders; 2009. p. 391-404.
2. Cohen S, Hargreaves KM. Pathways of the pulp. 9th ed.
St. Louis: Mosby; 2006. p. 318-323.
3. Ingle JI,Bakland LK. Endodontics. 5th ed. BC Decker;
2002. p. 498-505.
4. Weine FS. Endodontic therapy. 6th ed. St. Louis:
Mosby; 2004. p. 221-226
5. Haapasalo M, Shen Y, Qian W, Gao Y. Irrigation in
endodontics. Dent Clin N Am. 2010; 54: 291-312.
(Review)
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