Irrigation / orthodontic courses by Indian dental academy

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.

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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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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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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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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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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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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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 20-30 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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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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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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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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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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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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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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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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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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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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- 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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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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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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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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