This document discusses various irrigating solutions used during root canal treatment. It begins with a brief history of irrigants, from water and proteolytic enzymes to chelating agents and sodium hypochlorite. The ideal properties of irrigants are listed as well as the goals and role of irrigation. Various classes of irrigants are classified and described in detail, including acids, chelating agents, oxidizing agents, and others. Individual irrigants such as sodium hypochlorite, hydrogen peroxide, and citric acid are also discussed in regards to their properties, actions, and effectiveness at tissue dissolution, antibacterial activity, and smear layer removal.

1. IRRIGATING SOLUTIONS
INTRODUCTION
An important objective of endodontic therapy is the removal of
necrotic infected pulp and dentinal debris from the root canal system
of infected or non-vital teeth.
In order to accomplish this objective, it is essential to use an
irrigating solution or a combination of irrigating solutions during
BMP of the root canals.
Failure to use an irrigating solution during BMP results in
considerable amount of debris to be left behind in the root canal
system ultimately leading to endodontic failure. Hence for obtaining
an optimum level of disinfection of the root canal system
chemicomechanical preparation is a must.
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2. HISTORY
Prior to 1940’s Water was the most commonly used irrigant as
it was:
- Readily available.
- Inexpensive.
- Provided a lubricating effect during instrumentation.
During 1940’s proteolytic enzymes like streptokinase,
streptodomase, papain, enzymal etc. were being used as irrigating
solutions because of their tissue dissolving property.
In 1943, Grossman introduced the concept of using oxidizing
agents as irrigants.
In 1945, Daniel formulated an irrigating solution comprising
of a aminoacridine.
In 1970’s chelating agents were used increasingly because of
their biologically acceptable properties.
Goals of irrigation (Ingle):
1. Lavage of debris.
2. Tissue dissolution.
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3. 3. Antibacterial action.
4. Lubrication.
Ideal requirements of irrigating solutions (DCNA):
1. Antimicrobial property.
2. Dissolve necrotic tissue debris.
3. Aid in debridement of the root canal system.
4. Non-toxic to the periapical tissues.
Role of intracanal irrigants (Weine):
Irrigants perform important physical and biologic function
during endodontic therapy.
1. Loosens tissue debris – Dentinal shavings and microorganisms
from the irregular radicular dentine walls.
2. Flushes – The above into the pulp chamber space where it is
easily removed by aspiration or paper points.
3. Dissolves – Organic tissues that are entrapped in accessory or
lateral canals and that is inaccessible to hand instruments.
4. Antibacterial action – Certain irrigants possess germicidal
action, other reduce the number of microorganisms by
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4. eliminating the source or substrate for survival of these
organisms.
5. Lubricating effect : Facilitates instrumentation of the canals.
6. Irrigants possess a bleaching action.
CLASSIFICATION:
I. ACIDS and CHELATING AGENTS
ORGANIC EDTA
Citric acid EDTAC
Maleic acid RC-Prep
Tannic acid
Phosphoric acid
Tublicid
Lactic acid
INORGANIC
H2SO4 50%
HCl 30%
II. PROTEOLYTIC ENZYMES
- Streptokinase.
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5. - Enzymol.
- Streptodornase.
- Purified trypsin.
- Papain
III. OXIDIZING AGENTS
- 3% hydrogen peroxide.
- Urea peroxide.
- Glyoxide.
IV. ALKALINE SOLUTIONS
- Sodium dioxide.
- Urea.
- Sodium hydroxide.
- Sodium hypochlorite 0.5%, 1%, 2.6%, 5.25%.
- Potassium hydroxide.
- Chloramine-T.
V. OTHERS
- Chlorhexidine gluconate 0.2%
- Glutaraldehyde.
- Oxidative potential water.
- 2% potentiated acid.
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6. - 1% pentanedial.
- Calcium hydroxide solution.
- Bardac-22
INDIVIDUAL IRRIGANTS
TAP WATER
One of the early irrigating solutions used for flushing of the
root canals showed good clinical success. Studies performed in 1955
by Lorixzy et al showed periapical bone regeneration of after
mechanical instrumentation using tap water as an irrigating solution.
HOT WATER
A stream of hot water, 140-178°F discharged from an insulated
syringe was the first irrigant used.
Physiologic Saline:
From a biological stand point, sterile normal saline is the best
irrigant to use because it causes.
• Least apical tissue irritation or damage.
• Biocompatible.
• Least amount of cell lysis.
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7. Disadvantages:
1. However saline solution does not remove the smear layer but
merely flushes out some of the superficial debri from the root
canal system.
2. Has poor antibacterial properties, however irrigation followed
by ultrasonic and sonic instrumentation have been reported to
be almost as effective as 0.5 to 2.5% NaOCl irrigation in
reducing the number of bacteria in infected root canals.
SODIUM HYPOCHLORITE
Is one of the most popular irrigating solutions. It has been used
as an irrigant for well over 4 decades.
- It was first recommended as an antiseptic solution by
HENRY DAKIN in 1915 and was called as DAKIN’s
SOLUTION during the time of World War-I (NaOCl
buffered with sodium bicarbonate).
- 0.5% NaOCl solution was then used as a treatment for
infected wounds.
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8. Manufactured: It is made by bubbling chlorine gas through NaOH to
form equal amounts of sodium hypochlorite and sodium chloride
(NaOH  gas NaOCl + NaCl2)
Properties of NaOCl:
1. Antibacterial action
2. Strong dissolution property: Fresh tissue
Necrotic tissue
Fixed tissue
3. Lubricant – for effective instrumentation.
4. Bleaching action on discolored teeth.
5. Increased permeability of dentinal tubules for easier
penetration of an intra-canal medicaments.
NaOCl has been used in various concentrations ranging from
0.5-5.25%.
Most commonly used concentration – 2.5%
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9. ACTIONS:
Antibacterial:
NaOCl exerts its antibacterial action either by:
- Direct contact with microorganisms.
- Vapour action.
Destruction of the bacteria takes place in two phases:
1. Penetration into the bacterial cell.
2. Chemical combination with the protoplasm of the bacterial cell
that destroys it.
- Sodium hypochlorite at 5.25% is an extremely effective
antimicrobial agent.
- Studies have shown that this solution will destroy most
of the microorganisms found in the root-canal system
after exposure of 1 minute or less.
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10. FACTORS AFFECTING THE ANTIMICROBIAL PROPERTIES
OF NaOCl:
1. Diluting 5.25% NaOCl inhibits its antimicrobial property
significantly.
2. Bactericidal effectiveness of 5.25% NaOCl decreases over
time. Martin suggested a storage shelf-life of 3 months for
undiluted preparations.
3. The antimicrobial property may be achieved in a significantly
lesser time by prewarming the solution (room temperature
22°C-body temperature 37°C).
4. It maintains a remarkable degree of antimicrobial activity in
the presence of organic matter such as blood and serum
albumin.
** Briseno (1992) and coworkers demonstrated that the irrigation of
the root canal with 1% NaOCl (manual) was more effective against
the test organisms (E-edi + S.mutans) than irrigation of the root
canal with 2% NaOCl + ultrasound.
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11. TISSUE SOLVENT PROPERTY
NaOCl possesses strong tissue dissolution property for fresh
vital tissue, necrotic tissue and fixed tissues. This tissue dissolving
capacity equals to that shown by H2SO4 and HCl.
The solvent action of NaOCl has been attributed to its high
alkalinity.
The removal of organic tissue by NaOCl is by the release of
hypochlorous acid which reacts with insoluble proteins to form
soluble polypeptides, aminoacids and other by products.
NaOCl – hypochlorus acid + insoluble proteins – soluble
polypeptides, aminoacids and byproducts.
Grossman has shown that it can dissolve an entire pulp in 20
minutes to 2 hours.
5.25% of NaOCl is capable of penetrating into the dentinal
tubules and dissolving the contents of the tubules adjacent to the
main canal.
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12. This is an extremely important property for an endodontic
irrigant because of the irregularities in the surface of the canal walls
which prevents contact by instruments regardless of the BMP
techniques utilized.
NaOCl and Smear layers
NaOCl alone is not very effective in removal of the smear
layer, but when used in conjunction with other solutions or with
ultrasonics it has shown to remove the smear layer effectively.
Yamada and associates (1983) reported that a final flushing of
17% EDTA, followed by 10ml of 5.25% NaOCl, was more effective
in removing both inorganic and organic debris. These authors
concluded, that flushing with a chelating agent removed the final
calcific sludge that remained on the canal walls.
Flushing with 10ml NaOCl removed any remaining organic
tissue, thus leaving patent dentinal tubules on the surface of the canal
walls.
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13. A recent study (Lengiz in 97) showed that the use of 0.5%
NaOCl in combination with Ca(OH)2 preparation and ultrasonics in
the root canal can effectively remove the smear layer.
Also this is considered to be more safer than the use of NaOCl
solution is 5% concentration which is proved to be highly toxic.
TOXICITY OF NaOCl TO PERIAPICAL TISSUE:
NaOCl is an effective solvent of both necrotic and vital
tissues, which makes it toxic to the surrounding tissues.
There have been numerous reports of soft tissue complications
as a result of its inadvertent infection beyond the root canal system.
- Severe pain.
- Edema.
- Profuse haemorrhage both interstitially and through the
tooth.
This may be followed by (for several days)
- Increasing edema.
- Ecchymosis.
- Tissue necrosis.
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14. - Parasthesia.
- Secondary infection (rarely).
Majority of cases, have shown complete resolution within a
couple of weeks. In some cases they may be long-term parasthesia or
scarring.
Treatment for this type of emergency:
1. Remain calm and assist the patient in remaining calm.
2. Evaluate the reclined dental chair to decrease pressure from
the head.
a. For immediate relief of pain – nerve block and L.A.
b. Wet, cold, compress – continually applied to the face –
for relief of pain and burning sensation and minimize
swelling (for upto 6 hours).
c. Analgesics – after emergency treatment.
d. To control inflammation – corticosteroids immediately
i.v. for 3 days.
e. To prevent infection – antibiotics (1wk).
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15. f. Heat packs and warm mouth rinse (after initial
treatment).
To improve circulation to the area.
3. Advise the patient concerning the anticipated swelling and
ecchymosis.
4. Give the patient both verbal and written instructions.
5. Reassure the patient that he will regain his normal appearance
within a short period.
HYDROGEN PEROXIDE
For years 3% H2O2 was recommended as a canal irrigant
because of:
• Its effervescent action.
• Disinfecting properties.
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16. Actions:
1) Effervesent action:
This action was specially indicated in mandibular teeth where
the bubbling of the peroxide was thought to lift debris from the canal
system almost defying gravity.
However, H2O2 does not possess tissue dissolution properties
and is not effective as a lubricant.
Hence, alternate use of H2O2 + NaOCl irrigating solutions was
recommended by Grossman.
This alternate irrigation regimen during chemicomechanical
preparation produces.
1. Transient but energetic effervescence that mechanically forces
out debris and microorganisms out of the canal.
2. At the same time the O2 that is liberated in an active state
assists in destroying the anaerobic microorganisms.
3. NaOCl effectively removes the soft tissue debris.
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17. 4. The permeability of dentinal tubules is increased allowing
deeper penetration of intracanal medicament.
5. Increases the bleaching action on discolored teeth.
Toxicity.
CHELATING AGENTS
Chelating agents have come to be used in endodontic
repeatedly to aid in the mechanical enlargement of difficult root
canals by softening the root canal dentin walls.
EDTA – The most common chelating solutions used in
endodontics are based on ethylene diamine tetra-acetic acid
composed by Disodium salt of EDTA distilled water 100ml, 5N
NaOH 4.25ml.
This was 1st
described for use in endodontics by Ostby. He
found the following with EDTA.
Functions:
- It has certain dentin dissolving effects desirable in all
kinds of root canal therapy – ease in instrumentation.
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18. - It reduced the time necessary for debridement and
disinfection.
- It aided in enlarging narrow / obstructed canals.
- It helped make possible the bypassing of broken
instruments in the canals.
- Removed the inorganic component of smear layer.
- Had no corrosive effects on the instruments.
Action:
The sodium salts of EDTA are capable of forming soluble non-
ionic chelates with large number of metallic ions viz. calcium ions.
Because EDTA would seek the calcium metal ion in the
hydroxyapatite crystals of dentin in a chelate and thereby act to
demineralize dentin and enamel.
Ostby and associates found that EDTA decalcified dentin to a
depth of 20-30µm in 5 minutes.
Precautions to be taken with EDTA.
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19. Researchers have reported that it is possible to overchelate a
canal which can lead to perforation.
EDTA is known to remain active within the canal for 5 days.
- If not inactivated the solution may seep into the
periapical tissues and damage the bone.
- Therefore at the completion of appt, the canal must be
irrigated with NaOCl.
RC Preparation:
It’s a combination of 17% EDTA + ureperoxide 10%,
developed by Stewart and colleagues.
Effective lubricating and cleaning agent.
- It allows deeper penetration of the medicament into the
dentin.
- It is not water-soluble.
- It is popularly used in combination with NaOCl.
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20. - Because it is thought to produce a bubbling action helps
loosen and float out dentinal debris.
Studies have shown RC preparation might affect the apical
seal.
- Cook and associates reported twice as much leakage in
canals obturated with GP or silver cones following
cleaning and shaping with RC preparation NaOCl than
with NaOCl alone.
EDTAC (commercial name)
There is addition of quaternary ammonium compound to
EDTA – Cetavlon which has lead to a solution called EDTA-C, has
greater germicidal acitivity and disinfecting properties.
REDTA – A quaternary ammonium bromide has been added to
EDTA solution to reduce the surface tension + increase the
permeability of the solution.
This combination has been shown to remove the smear layer in
the RC during instrumentation.
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21. SALVIZOL
Another chelating agent is salvizol based on
aminoquinaldinum diacetate.
Properties:
1. It has surface acting property similar to quaternary ammonium
groups.
2. Chelating action.
3. Organic debridement.
4. Bactericidal activity.
ORGANIC ACIDS
The use of organic acid irrigants to irrigate and debride root
canals is as old as root canal therapy itself.
CITRIC ACID:
Has been recommended as a canal irrigant because of its
ability to demineralize and remove the smear layer effectively.
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22. 2 observations were made:
1. It acts as a chelating agent on dentine.
2. Therefore, it occurs naturally in the body, it is more acceptable
biologically than other acids ((Jenkin and Dawer 1963).
The chelating action of citric acid softens the dentin and
facilitates easy removal of the smear layer.
CA has been used effectively in concentration of 10, 25 and
50% as RC irrigant.
Disadvantages:
C.A. may leave precipitated crystals (calcium and phosphate
containing crystals) in the canal wall. Which may be a disadvantage.
- Citric acid has been used in combination with NaOCl to
effectively clean the R.C.
- C.A. removes smear layer better than many acids like
poly acrylic acid, lactic acid and phosphoric acid.
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23. TANNIC ACID
Tannic acid is another cleansing agent for root canal
preparation was suggested by Graham Mount.
It has been extensively used in the treatment of burns (more
than 100 years old).
Action: It acts as a surface coagulant by precipitating proteins.
*Studies have shown that the use of tannic acid in the root canal as
an irrigant cleansed the canal more effectively than the conventional
combination of NaOCl + H2O2.
CHLORHEXIDINE GLUCONATE
Chlorhexidine has become recognized as an effective
antimicrobial agent and its use as a potential endodontic irrigant has
been demonstrated in the last decade.
Recently, it has been accepted as a root canal irrigant in
endodontics.
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24. Advantages:
1. Has a broad spectrum antimicrobial action.
2. Relative absence of toxicity.
Disadvantage – it is not known to possess a tissue dissolving
property.
Structure is a symmetrical cationic molecule consisting of:
4-chlorophenyl rings and 2 biguanide groups
Connected by a central hexamethylene chain
Specturm of activity
Chlorhexidine is bactericidal and effective against gram +ve,
gram-ve, yeast, Candida albicans.
Action:
C.G. acts by adsorbing into the cell wall of the
microorganisms and causing leakage of the intracellular components.
At low concentration of chlorhexidine, small molecule wt
substances will leach out, resulting in bacteriostatic effect.
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25. At higher concentration, chlorhexidine is bactericidal because
of precipitation or coagulation of the cytoplasm caused by protein
cross linking.
The bacteriostatic effect of chlorhexidine is considered to be
more effective. The bound chlorhexidine molecule is slowly released
for upto 24 hours, as the concentration decrease.
According to Klimn et al
When used as an intra canal irrigant in the endodontic
treatment for periapical lesions C.G. showed:
1. Clinical relief of symptoms.
2. Sterility.
3. Reduction in the size of periapical lesions.
All at a mean follow up of 24 months.
In another study (O hara et al) showed that CG was the most
efficient antibacterial agent when compared to 3% H2O2, 5.25%
NaOCl, saline REDTA 17%.
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26. GLUTARALDEHYDE
Lately glutaraldehyde has been suggested as an endodontic
irrigant.
Weine suggested that the use of 2% aqueous solution of
glutaraldehyde as a canal irrigant.
Glutaraldehyde is known to cause irreversible fixation without
any adverse tissue reactions.
Weine observed that apart from the normal mechanical and
chemical techniques for preparing and disinfecting root canals, a
different concept is that: detoxification can be obtained by using
fixatives.
These are able to block off certain end groups in the
aminoacids of the organic component of debris formed during
instrumentation.
This renders them metabolically inert (remaining organic
debris).
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27. Since it is impossible to remove all the organic material from
the lateral canals, ramifications and dentinal tubules, complete
fixation of the root canal contents remaining after mechanical
cleansing might therefore be considered to be the ideal treatment.
5 year clinical results of root canal treatment with 2%
glutaraldehyde showed a success rate of 96% for chronic and 89%
for acute periapical conditions.
Glutaraldehyde was preferred to formaldehyde. Therefore it
has 4 additional properties:
1. Irreversible bonding with proteins.
2. Limited diffusion into tooth structure.
3. No periapical irritation.
4. Appears to cause a softening of dentin for limited duration,
facilitating the mechanical preparation of the root canal.
Thus the greater reduction in microorganisms with
glutaraldehyde 2% can be attributed to the fixative property
rendering the microorganisms inert and non-toxic.
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28. 9-AMINOACRIDINE
The efficacy of 9-aminoacridine has been reviewed by
Schmitz.
Properties:
- Antibacterial action.
- Low toxicity.
- Osteogenic potential.
Disadvantage:
1. Not a chelator.
2. Not a tissue solvent.
It use is not widespread.
Mechanism of action:
Disruption of cellular metabolic pathways of microorganisms:
i. Inhibition of cells, protein synthesis.
ii. Inhibition of DNA synthesis.
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29. Use:
1. The most promising use of 9-aminoacridine appears to be in
the management of endodontically involved teeth with large
periapical absecesses.
It is one of the few endodontic medicaments recommended for
pressure irrigation of the periapical tissues via the canals.
2. Since it possesses a low inflammatory potential consistent with
its ability to maintain asepsis the drug may be sealed in the
canal as an interim medication.
Glyoxide:
Glyoxide is an irrigation solution i.e. comprised of 10% urea
peroxide (Carbamide peroxide) in a vehicle of anhydrous glycerol in
1961 Stewart proposed glyoxide to be an effective adjunct to
instrumentation for cleaning of the root canal.
Action:
1. Antibacterial activity that is more potent than 3% H2O2.
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30. 2. Enhances root canal lubrication without softening the dentin.
Hence, unlike other chelating agents that react with dentine
(and may cause root perforation or ledging in softened walls). With
glyoxide this does not occur, here only lubrication is enhanced.
3. It is less toxic to periapical tissues than NaOCl.
4. It also has greater solvent action than 3% H2O2.
Use:
1. the best use of glyoxide is in narrow and curved canals where
slippery effect of glycerol is maximized for instrumentation.
OXIDATIVE POTENTIAL WATER
This was developed in Japan and is an electrolytically obtained
highly acidic water that has an outstanding antimicrobial activity
killing bacteria and viruses.
BARDAC-22 (0.5%).
New quaternary ammonium compound.
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31. IMPORTANT FACTORS ASSOCIATED WITH IRRIGATION
1. The most important factor in irrigation is the delivery system
and not the irrigating solution per se.
2. Volume of the irrigation used is more important than the
concentration or the type of the irrigant.
3. Depth of irrigating device within the canal.
4. Irrigant penetration is influenced by factors like:
- Canal.
- Type and size of the irrigant needle.
- Canal size and shape.
Technique of Endodontic Irrigation:
1. After rubber dam elevation, access is gained to the root canal
system. The pulp chamber is thoroughly debrided and flushed
with the irrigating solution.
2. The orifice of the canal especially of posterior teeth is very
narrow hence care must be exercised to properly enlarge the
orifice and to flare the canals so that the needle of the
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32. irrigating syringe passes easily into the canal. The needle is
best at an angle so as to allow easy access into the root canals.
3. The needle is inserted into the canal and slowly advanced
apically without bendens with the canal walls and when
resistance is felt the needle should be withdrawn by few
months.
4. The irrigating solution is deposited slowly without any
pressure.
If the needle is forced apical until it binds against the canal
walls injection of any solution even water will cause discomfort
to the patient.
A perforated irrigating needle (Goldstein) has been developed
to deliver irrigant at 360° to the root canal. The disadvantage with
this needle is that it is delicate and bends out of shape easily.
Ultrasonic hand pieces may be used for irrigate. They pass
sound waves to the endodontic file and cause it to librate at 25,000
vibrations.
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33. They cut dentin and result in acoustic streaming of the irrigant.
Martin and Cunningham stated that cavitation occurs within the
irrigating solution and this leads to increased debris dislodgment
from the canal walls.
A sonic handpiece may also be used to irrigate canals. This
handpiece has endodontic files with sound waves causing the file to
liberate at 8,000 vibration and dislodge the debris within the canals.
DOXYCYCLINE HYDROCHLORIDE
More recently DH, a hydroxy derivative of tetracycline is
under study as an irrigant. It is the most potent anticollagenase
antibiotic among commercially available tetracyclines.
The tetracyclines are broad spectrum antibiotics demonstrated
to be effective in control of periodontal pathogens.
Advantages:
1. The dentin surface is capable of acting as a reservoir by
adsorbing and slowly releasing antibacterial levels of
doxycycline into the adjacent environment for several days
following topical applications of this antibiotic solutions.
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34. 2. Inhibit extracellular collagenase activity and bone resorption.
Metranidazole
Antibiotic spectrum confined solely to obligate anaerobes.
Active against bacteroides, porphyromonas fusibacterium,
clostridium and peptococci and peptostreptococci.
Comes as an injection: Metranidazole 500mg, NaCl2 0.8,
Water.
Barnett and Tronstad reported the successful use of
metranidazole in controlling infections by bacterioides spp and
pseudomonas spp colonized at root ends of endodontically treated
teeth that had failed to heal and remained refractory to all other
treatment.
Adverse reactions include:
- Nausea.
- Headache.
- Metallic taste.
- Xerostomia.
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35. Conclusion:
Debridement of the root canal systems is essential for a
predictably successful endodontic treatment. The identification and
elimination of bacteria, removed of other necrotic products from the
canal with appropriate irrigating solutions with proper technique
ensures definite fulfillment of one of the objectives of root canal
therapy.
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