This document discusses irrigation in endodontic therapy. It outlines the goals of irrigation as removing debris, dissolving tissues, antibacterial action, and lubrication. Sodium hypochlorite is the most commonly used irrigant and has antimicrobial, tissue dissolving, and lubricating properties. Chelating agents like EDTA are also used as they soften dentin and remove smear layers. Newer irrigants continue to be explored but sodium hypochlorite remains the gold standard due to its effectiveness and low toxicity to tissues. Ultrasonic irrigation provides improved cleaning by increasing the mechanical and thermal activity of irrigants.

1. INTRODUCTION
An important objective in endodontic therapy is the removal of pulpal
and dentinal debris from the root canal system, to accomplish this it is essential
to use an irrigant or combination of irrigants during and after biomechanical
preparation of the canal system. Refers to as chemical preparation, when
accomplished simultaneously are often reported as “chemomechanical
preparation”.
GOALS OF IRRIGATION
Four goals of irrigation :
1. Lavage of debris
2. Tissue dissolution.
3. Antibacterial action and
4. Lubrication.
Debridement with hand instruments alone are not possible able to
remove all the tissue remnants in the pulp chamber and canals. It is necessary
to rely on some means of chemical dissolution of the remaining tissue, and this
depend upon the type of remaining tissue whether it is vital, necrotics, or
chemically fixed tissue, unfortunately, irrigants are not equally effective on all
three tissue types. Some tissue all three tissues may be encountered clinically in
the same tooth.
Other variables are the method and extent of canal instrumentation –
whether coronal apical or apico coronal (step back), preparation.

2. Laboratory studies have shown, for example, that the step-back
preparation leaves less tissue debris.
• The extent of instrumentation and the size of the last instrument used at
working length influence the penetration of irrigants.
• Quantity and temperature of the irrigating solutions the length of time of
contact, the level of observations (apical, middle, or coronal), the
presence of serum proteins, the depth of penetration of the irrigating
needle, the type and gauge of the irrigating needle, the surface tension of
the irrigating solution (with alcohol or detergent), and the age of the
solution are all influences the effects of the irrigating solutions.
DESIRABLE PROPERTIES FOR AN ENDODONTIC IRRIGANT
The chemical agent selected for endodontic irrigation should poses from
major properties :
1. Should have antimicrobial activity.
2. Dissolve necrotis tissue.
3. Aid in debridement of the canal system.
4. Be nontoxic to the periradicular tissues.
The first three of these properties are interrelated, tissue dissolution
property aids in the debridement by dissolving organic debris, these assist in
reducing the microbial flora by removing necrotic debris and thereby reducing
the substrate that promotes the growth of microorganisms.
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3. HISTORY OF IRRIGATING SOLUTIONS
Prior to 1940, water was the most commonly used endodontic irrigant, it
provided lubricating effect making instrumentation of the canal wall easier.
The number and types of irrigants that have been recommended later on
include acid, chelating agents, proteolytic enzymes, alkaline solutions and other
clinical agents such as oxidizing agents and normal saline solutions.
ACIDS AND CHELATING AGENTS
Acids and chelating agents were used because of their ability to soften
dentin, making enlargement of the canal system easier. Acids such as 30%
hydrochloric acid and 50% phosphoric acid were used as late as 1940s with
little or no understanding of effects on periradicular tissues.
These caustic acids dissolved inorganic structure of dentin with the
remaining organic matrix offering less resistance to instrumentation.
Chelating agents - came into increasing use in the 1970s. They softened the
dentin better then acids and also far more biologically acceptable to the soft
tissues. They combine with and inactivate calcium ions. This decalcification
effect results in less resistance to instrumentation.
CHELATING AGENTS ARE:
EDTA, REDTA (EDTA buffered with sodium hydroxide in an aqueous
vehicle). RC-Preparation (EDTA and urea peroxide) and citric acid.
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4. Proteolytic Enzymes
Were utilized in 1930s and 1940s for their tissue solvency effect. They
possessed very little tissue solvency property within root canal systems.
Enzymes used in the therapy are : Streptokinase, streptodornase, papain,
enzymol and purified trypsin.
Alkaline Solutions
Used solutions are, sodium dioxide, sodium hypochlorite, potassium
hydroxide, urea and sodium hypochlorite. Sodium hypochlorite has been
proved clinically acceptable and is the most commonly used irrigant in
endodontics.
Oxidizing Agents
In 1943, Grossman introduced the concept of using an oxidizing agent
as an irrigant in conjunction with sodium hypochlorite. He recommended that
solution of 3% hydrogen peroxide be alternated with a solution of 5.25%
sodium hypochlorite, so that the foaming action resulting from the chemical
reaction would help to remove debris from the canal system.
Recently another oxidizing agent, gly-oxide has been recommended,
particularly for narrow, curved canals contains carbamide peroxide in an
anhydrous glyceral base is highly viscous, glyceral base provides very good
lubrication, has little antibacterial activity not a tissue solvent.
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5. Sodium Hypochlorite
Used as an endodontic irrigant for well over four decades. It is reducing
agent, is a clean straw colored solution containing about 5% of available
chlorine.
This irrigant when used during cleaning and shaping act as a lubricant,
solvent of the pulp tissue, antiseptic and bleach.
The amount of dilution and its use in combination with other irrigants
such as glyoxide, RC-Prep, or hydrogen peroxide still remain controversial.
Trepagnier has reported either 5.25% or 2.6% sodium hypochlorite has
the same effects for a period of 5 minutes when used in root canal system.
Cunningham has shown 5.26% and 2.6% NaOcl were equally effective
at 37°C (body temperature) warming the solution increase its antibacterial
effect.
Rosefield demonstrated 5.25% sodium hypochlorite dissolves vital
tissue and dissolves necrotic tissue better than in any other concentration.
Antimicrobial property is due to the destruction of bacterial by
penetration into the bacterial cell and chemical combination with the
protoplasm of the bacterial cell.
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6. Hand and associates have shown that sodium hypochlorite retain its
antimicrobial activity in the presence of organic matter such as blood and
serum albumin.
Alternate irrigation with sodium hypochlorite and hydrogen peroxide
(3%) produces energetic effervescence that mechanically forces debris and
microorganisms out of the canal. Release of nascent oxygen causes the forming
effect.
- Combination seems to reduce the tissue solving property advantage is
mechanically bubbles and pushes the debris.
- The solvent action of the sodium hypochlorite.
- The disinfectant and, bleaching action by both solution.
Sodium hypochlorite should be used last because hydrogen peroxide can
react with pulp debris and blood to form gas, trapped gas in the tooth causes
continuous pain.
Fischer and Huerta believe it is the alkaline property (pH 11.0 – 11.5) of
sodium hypochlorite that makes it effective against anaerobic microbes.
Bactericidal effect gained by combining sodium hypochlorite with other
chemicals come from the release of chlorine gas. It is true with citric acid,
some extent with EDTA and not with hydrogen peroxide. Sodium hypochlorite
is a tissue irritant and this discourages its use to its full strength.
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7. CHELATING AGENTS
Most common chelating solutions used for irrigation Tublicid, EDTA,
EDTAC, File-Eze and RC-Prep. In all of these EDTA-Ethyline diamine tetra-
acetic acid is the active ingradient.
Introduced into the endodontic practice by Nygaard Ostby. Later he
introduced EDTAC, EDTA with cetrimide, quaternary ammonium compound
to reduce surface tension and increase penetration, cetrimide acts as
disinfectant.
EDTA functions by forming a calcium chelate solution with the calcium
ion of dentin : (the dentin becomes more fliable and easier to instrument).
When all of the available inorganic matter of dentin is chelated by the EDTA-
Dentin reaction, a chemical equilibrium is established.
EDTA + 2ca++
 Ca EDTA Ca
This equilibrium reaches within 7 hours, regardless of surface area
involved indicating that EDTA is chemically self limiting in the chelation of
irorganic material from dentin.
The optimal pH for the demineralizing efficiency of EDTA as shown by
Valdrighi is between 5.0 and 6.0.
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8. Goldberg has shown EDTAC increases permeability into dentinal
tubules accessory canals and apical foramina. McComb found EDTA sealed in
the canal for 24 hrs produced the cleanest dentinal walls.
Goldman and colleagues in 1981 were shown combined use of sodium
hypochlorite and EDTA removed smear layer, chelating agents remove only
calcified tissues whereas sodium hypochlorite removes organic material
confirming the composition of smear layer.
Original Nygaard Ostby formula for 15% EDTA was
- Disodium salt of EDTA 17.0g
- Distilled water 100.00ml
- 5ml sodium hydroxide 9.25 ml
Summarizing the effects of EDTA studied by both in vitro and invivo.
1. Effective in softening the dentin.
2. Has distinct antimicrobial properties.
3. Is capable of causing moderate degree of irritation.
4. Has no deliterious effect when used clinically.
5. Irrigation with EDTA removes smear layer.
6. Demineralization is proportional to the exposure time.
7. To a depth of 20-30µ in 5 minutes.
In 1969 Stewart and others developed RC-prep. is composed of EDTA
and urea peroxide in a base of carbowax. An effectiev lubricating and cleaning
agent for root canals and allowed deeper penetration of the medicament into the
dentin.
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9. According to Cook and associates RC-preparation allowed maximum
leakage into filled canals over 2-6 times the leakage of the canals.
Another root canal irrigant is solvizol which is N1
-N1
-Decamethylene –
N4
, N4
-decamethylenebis – 4 – amino quinaldinium–diacetate
Kaufman suggested that with a neutral pH has a broad spectrum of
bactericidal activity as well as the ability to chelate calcium, makes it a
cleansing potency and biologically compatible. This applies to tublicid (green,
red and blue) as well.
EDTA is inserted by depositing a few drops in the pulp chamber with a
syringe and then carefully pumping the solution into the root canal with a fine
root canal instrument, and is continued with the solution bathing the canal at all
times until cleaning and shaping are completed.
ORGANIC ACIDS
Tidmarch, felt 50% citric acid gave the cleanest dentin walls without a
smear layer.
Wayman reported excellent filling results after preparation with citric
acid (20%), followed by 2.6% sodium hypochlorite and a final flushing with
10% citric acid US Air Force tested effective as a bactericidal in 5-10min. other
organic acid used to remove smear layer are polyacrylic acid for one as
Durelon and Fuji II liquids, both 40% polyacrylic acids.
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10. OTHER IRRIGANTS
9-amine acridine reviewed by Schmitz enjoys regional popularity
because of its low toxicity and antimicrobial action and has a purported
“osteogenic potential”, has no wide spread use because its not a tissue solvent
or chelator.
Chloriamine – T has little ability to dissolve necrotic tissue.
- Chlorhexidine gluconate (0.2%). Recently, Loma Linda group reported it to
be more effective as an antimicrobial agent.
- Kaufman reported bis-dequalinium acetate (BDA) as disinfectant and
chemotherapeutic agent. He cites its low toxicity, lubrication action,
disinfecting ability, and low surface tension, as well as its chelating
properties and low incidence of post-treatment pain. It is marked as
solvidont.
BDA is recommended as an excellent substitute for sodium hypochlorite
in those who are allergic to sodium hypochlorite.
Action of chlorhexidine : action is the result of absorption of chlorhexidine
onto the cell wall of the microbes thereby altering the cells osmotic
equilibrium; resulting in leakage of intracellular components.
Broad spectrum, antimicrobial, substantivity and relative absence of
toxicity.
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11. 2% glutaraldehyde - Wemes and co-workers 1982 used 2% glutaraldehyde as
an endodontic irrigant. It causes irreversible fixation of tissues, they observed
smooth layer of dentin material resulted in closure of apical and lateral canals
and the dentinal tubules and showed considerable antibacterial effect.
ULTRASONIC IRRIGATION
The use of ultrasonic irrigation to better cleanse root canals, of their
fillings debris and bacteria has been well reported by Martin and Cunningham.
The oscillating movement of the file creates ultrasonic wave of sodium
hypochlorite irrigant solution which is delivered along the side of the file and
the vibration produces heat that increases the chemical effectiveness. It also
produces cavitation, that is the growth and collapse of bubbles, with a resulting
increase in the mechanical cleansing activity of the solution, this increases in
thermal and mechanical activity of the solution, helps in removal of debris and
tissue from the isthmus and removal of smear layer are more efficient
bactericidal action also increases.
Sonic system uses water as an irrigant and doesn’t usually require
diamond files for the flare of the preparation.
Technique
The instrument required is a disposable plastic or glass syringe with an
endodontic notched needle. The needle should be bent to an angle to reach the
canals of posterior as well as anterior teeth. The needle is inserted into the
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12. canal part way and should not bind the canal sufficient room between the
needle and canal allows for the return flow and avoids forcing of solution into
the periapical time.
When it is not binding, the solution should be ejected with little or no
pressure, on the plunger during the shaping and cleaning of the canal care
should be taken that canals are always full of fresh solution.
A perforated irrigating needle deliver irrigant 360° in the canal, and
large volumes of the irrigant solution physically remove more material it has
been claimed.
Disadvantage is that it is delicate and bends out of shape easily.
MICROBIAL FLORA
The basis of pulpal disease and the ultimate death of the dental pulp is
found in the science of microbiology, clinician must recognize the cause and
effect of bacterial invasion of the pulp tissue, what occurs to the bacteria when
treatment ensures and final consequences when treatment is completed.
BRIEF HISTORICAL PERSPECTIVE
In 1894 Miller became the first researcher to identify bacteria in the
diseased pulp.
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13. In 1910 William Hunter described dissemination of microorganisms,
which became formally known as “focal infection theory”, which caused
concern with oral focal infection.
In 1939 F. Wilfred Fish investigated zones in tissue that formed in
response to infection, recognizing four zones of reaction.
Appleton suggested that without bacteria no need would exist for
endodontic treatment supported by the study of Cabechashi and colleagues.
Appleton maintained that the function of root canal therapy is to render
the canal and periapical tissue sterile and a bacteriologic examination has
therefore necessary.
Since 1901 the question of the validity of culturing remains and the
controversy continues.
Earlier studies described a flora consisting predominantly of aerobic and
facultative anaerobic microorganisms. The differences in flora, as reported by
different investigations over the past 5 years, are the result of improved
technology in sampling such as new anaerobic culturing techniques, new and
improved culturing media, and more sophisticated methods of isolation and
identification of microorganisms and also the interest of the investigator.
In 1919, Henric and Hartzell (began indentifying bacteria from the
dental pulp) found that 65% of the organisms were streptococci, 20% were
staphylococci, and the remaining bacteria were corynebacteria and yeasts.
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14. In 1952, Grossman and Cristrian found that infected pulpal tissue
occupied 77% gram positive cocci, 16% yeast and 5% gram negative rods.
In 1973 Berg and Mord and in 1974 Kantz and Henry used anaerobic
isolation and obliggate anaerobes in 27% of their samples.
- Actinomyces, Camrlobaction, Eubacteria, Fusobacteria, streptococcus and
veilonells.
- Bystorm and Sundquist found 87% of their isolation anaerobes.
- Sandquist concluded that accute inflammation of the periradicular area is
induced by combinations of bacterial strains and predominately that of
bacteriocids.
- Black pigmented bacteriocidal, B.gingivalis and B. endodontalis were
present only in acute infections.
Glick and associates were able to identify HIV (Human Immuno
Deficiency Virus) in noninflammed dental pulps of patients with AIDS through
the use of polyacrylase chain reaction (PCR) test, which present in fibroblasts
of pulp. Maidorf compiled a list of generalization regarding organisms isolated
from root canal are :
1. Mixed infections are more common than single organism isolates.
2. The wide variety of organisms found are partially related to the periapical
inserts and culture techniques of these investigations.
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15. 3. The invasion of dentin from the pulp has been described but the type of
organisms, growth rate and variability are poorly understood.
4. Pulpal isolates are similar to oral flora with gram positive cocci
predominating.
5. Organisms associated with flare ups do not differ from asymptomatic canal
isolates.
6. Cultured organism elaborate a variety of invasive enzymes.
7. The present practice of treating the source of the infection of the root canal
and not the periapical tissue confirms to the findings of Hedman.
BACTERIAL PATHWAYS INTO THE PULP
Bacteria enter the pulp through :
1. The crown or root following traumatic exposure of the pulp, through the
dentinal tubules following carious invasion, restorative procedures
including crown preparation and leaking restorations.
2. From the periodontal tissue through exposed dentinal tubules, lateral and
accessory canals or apical and lateral foramina.
3. By lymphatic or hematogenous route, anachoresis is defined as the
localization of transient bacteria in the blood into an inflamed area, such as
a traumatized or inflamed pulp.
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16. BACTERIOLOGIC EXAMINATION
Sterility of a canal or a reduction in the number of microorganisms in a
root canal can’t be determined by sight and smell. Some organisms are
chromogenic and not all bacteria give if noxious odour, culture is a valuable
and important tool.
Buchbinder showed that 10% more teeth had treated successfully on
postoperative check up if they had a negative culture before obturation.
Oliet and Soxin, Zolcow and Ingle have shown higher success rate under
similar circumstances.
Eggink found difference in healing for upto 3 years when obturated in
the presence of positive or negative cultures, from the time of healing.
Morqu contended that the success rate is the same whether the root canal
yields a positive or negative culture at the time of obturation.
The difference of 10% in result obtained by most investigators does not
appear great. But in 10% of all teeth treated in presence of a positive culture is
the success is unlikely.
Endodontic treatment without the benefit of bacteriologic control is
justified neither elonofically or ethically.
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17. CULTURE MEDIA
Culture techniques is to determine the type of organisms to be found
whether it is in the canal proper or the periradicular area of the teeth.
Not all microorganisms present in a root canal grow in readily available
media especially obligate anaerobes, exposure to air during endodontic
treatment or to the chemical agents such as sodium hypochlorite will destroy
obligate anaerobes. Even though single organism of certain species is enough
to initiate growth in culture media, according to Grossman maximum number
of organisms needed is ten.
Common endodontic culture media are:
Brain heart infusion broth with 0.1% agar.
Trypticase soy broth with 0.1% Agar (TSA) 0.1 Agar facilitates growth
of anaerobes. Thioglycolate and glucose ascites broth.
Addition of 5% Ascitic fluid or 10% horse serum will enable fastidious
organism to grow. Test tubes filled to a high level, should be used for culturing
to provide different degrees of oxygen tension at different levels of the culture
medium.
- In viability media for growth (VMG) and stuart transport medium must
strains survive for longer period.
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18. - Moller - base culture medium containing veal, veal heart, peptone prodintia
an agar gel, and certain supplements will give slow grower time to produce
a positive result continue about 2 weeks.
- Sandquist - used pre-reduced media anaerobic box to grow anaerobes,
Griffee found prereduced thioglycollate medium twice effective.
- (When samples are taken) proper use of nitrogen gas over the canal orifice
before samples were taken ensure canal orifice free from atmosphere
oxygen.
Blood agar, trypticase soy, or green/heart infusions media base may be
fortified with defibrineted blood the presence of catalase present in the
hemolysed blood destroys the toxic effects of hydrogen peroxide, which is
lethal to anaerobic organisms.
Hemin, sodium lactate and vitamin K are added to any of the above base
media and illustrated in chambers with flowing gas mixtures of almost pure
carbon dioxide with less than 5% hydrogen or mixtures of oxygen free gases,
such as 80% nitrogen, 10% hydrogen and 10% carbon dioxide allow anaerobic
growth.
TAKING THE CULTURE
The dressing from the previous visit is removed from the root canal and
is discarded. A sterile charcoal impregnated absorbant point is inserted into the
canal, with a spring motion to cleanse the canal surface of any trace of
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19. medicament, the point is removed and discarded which will prevent carrying
any of the medicament into the culture medium could inhibit bacterial growth
and possible false negative culture.
A fresh sterile absorbant point is now inserted into the apical foramen
and is allowed to remain for at least 1 min to absorb as much periapical exudate
and microorganisms from the root canal as possible. The absorbent point is
removed with sterilized cotton pliers held with thumb, index and middle finger,
while the plug or cap of the test tube is removed with little finger and palm of
the same hand, the test tube held in the other hand is tilted slightly to prevent
air contamination, the lip of the tube is flamed the absorbent point is dropped
and the plug or cap is replaced and the culture tube is incubated properly.
ANAEROBIC CULTURING
Fastidious process that requires special equipment and media used in a
temperature controlled oxygen free environment.
For clinicians wish to culture anaerobic microorganisms from samples
obtained from periradicular tissue and root canal.
PERIRADICULAR SAMPLE
Using an aseptic technique, insert the sterile needle into the periradicular
space (i.e., swelling) aspirate fluid, eject air inside the syringe band
immediately, insert the needle through the rubber septum stopper of an Anaport
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20. vial from which the gas has been removed and eject the fluid, transport the
sample within 4 hour after taking the sample to culturing department.
ROOT CANAL SAMPLE
Aseptically prepare an access cavity into the pulp chamber, inject few
drops of prereduced anaerobically sterilized medium (chopped meat glucose
broth sandquist) into chamber, pump the medium into the root canal with a
sterile endodontic file, aspirate the fluid, eject any air from the syringe
immediately, insert the needle through the rubber stopper of an anaport vial and
eject the fluid. If an exudate is present inside the root canal, the injection of
additional medium is unaccessory for sampling.
SUMMARY AND CONCLUSION
Irrigants in endodontic therapy is a must and are many, it is for the
clinician to select particular irrigant, depending on the clinical observation,
sterility canal configuration, the knowledge of the microbial flora, and their
isolations and maintaining negative field in the canal improves the success of
root canal.
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21. Contents
 Introduction
 Goals of Irrigation
 Desirable Properties
 Irrigating Solutions
 Ultrasonic Irrigation
 Microbial Flora
 Bacterial Pathways into the Pulp
 Bacteriologic Examination
 Culture Media
 Taking the Culture
 Summary & Conclusion
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