Root Canal Irrigations

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CONTENTS

  IRRIGATION

        Irrigation serves as a physical flush to remove debris as well as serving as a antibacterial agent ,tissue solvent and lubricant.Some are effective in removal of the smear layer .It is highly recommended that canal always be instrumented while containing an irrigant or lubricating agent 

Requirements of a ideal irrigant

1.          Should be good tissue or debris solvent

2.          Should have low toxicity

3.          Should have low surface tension to promote flow into inaccessible areas

4.          Should be biocompatible

5.          Should be a lubricant

6.          Should have antimicrobial properties

7.          Should be capable of removing the smear layer

Method of irrigation

ü    Disposable syringes of 2.5ml or 5ml capacity with blunted needles are used .A bend of obtuse angle is made for convenience

ü    Special needles with closed tip and lateral openings are used;Eg Max-I-Probe , Prorinse

·                  Soln is expressed very slowly .The files will carry the irrigant by capillary action and the narrow canal will retain much of the soln .Excess is carried away by aspiration  or by gauze pad .

·                  Irrigants should not be forcibly inserted into the periapical tissues

·                  Needle should not bind to the canal walls, should be loose enough to permit return flow of the soln.

·                  The return of soln is caught on a gauze placed near the access opening

·                  Irrigation should be done frequently with change of instrument

·                  The canals should not be dried with compressed air. This may result in tissue emphysema [ venturi effect]

SODIUM HYPOCHLORITE NAOCL

·                  Most widely used;Household bleach 5.25%.

·                  Effective antimicrobial agent, serves as a lubricant during instrumentation

·                  Dissolves vital and nonvital tissues

·                  It is a reducing agent

·                  Is a clear straw colored solution containing about 5% of available Cl

·                  On ionization produces hypochlorous acid and hypochlorite ion

·                  Effective Antimicrobial activity

·                  0.5% - 5.2% solution is an effective conc. for use as an irrigants in the root canal

·                  strong proteolytic effect makes it an excellent aid during instrumentation

·                  5.2% conc. is the most effective conc.

·                  2.5% is commonly employed conc. as it decreases the potential of toxicity while maintaining dissolving  and antimicrobial activity

·                  Decreasing the conc. is safer but reduces the effectiveness of the irrigants

This can be compensated by

i.              Increasing the vol of irrigants employed

ii.              Increasing the duration of irrigation

iii.              Warming the irrigant increases the effectiveness this can be done with the help of chairside irrigant warming devices

·                  Passive ultrasonic activation of the irrigant has been advocated to improve the effectiveness of NaOCl as well as to enable to reach into the complex isthmuses of the root canal

·                  NaOCl can dissolve an entire pulp in 20 min to 2 hrs

·                  Destruction of bacteria takes place in two phase

o       Penetration into the cell wall

·                  Chemical combination with the protoplasm of the bacterial cell and disruption of DNA synthesis

·                  It is effective against endodontic microorganisms including those difficult to eradicate such as enterococcus actinomyces and candidia organisms

·                  Lower conc. dissolves mainly necrotic tissues. Higher  conc. has better dissolution but can dissolve both vital and necrotic tissues

·                  NaOCl has an alkaline pH of 12-13 and is hypertonic. Some   recommend the use of demineralizing agent to enhance the cleaning of difficult to reach areas such as dentinal tubules and lateral canals

Drawback

1.          Cytotoxic and caustic effects on healthy periradicular tissues on inadvertent extrusion during the irrigating procedures.Therefore, Lower conc. 0.5 – 1% /2.5% NaOCl being preferred

2.          Does not remove the inorganic component of the endodontic smear layer

3.          Unpleasant taste

4.          Solution should be kept in a cool place away from sunlight

5.          Releases free oxygen radicals and have potential to decrease the bonding of resin to dentin

CHLORHEXIDINE DIGLUCONATE

·                  2% CHX posses a broad spectrum antimicrobial activity against G+ve and G-ve bacteria

·                  Less toxicity and have substanstivty property binding to HAP.Doesn’t remove smear layer and hence employed in conjunction with other irrigants .It has a cationic molecular component that attaches to the –vely charged cell membrane areas ,causing cell lysis

·                  It  has significant antibacterial effects than calcium hydroxide

·                  Effective combination of calcium hydroxide and CHX showing strong antimicrobial activity against obligate anaerobes. This combination augment the antimicrobial effect

IODINE POTASSIUM IODIDE

·                  It is a traditional root canal irrigant

·                  Has the ability to kill wide spectrum of microorganism found in root canal

·                  Acts as an ionizing agent by reacting with free sulfhydryl groups of bacterial enzymes, cleaving disulfide bonds

·                  E faecalis often associated with therapy resistant periapical infection and combination of IKI and CHX may be effective against resistant bacteria

Disadv

·                  Iodine might be allergic to some patients

HYDROGEN PEROXIDE H2O2

·                  Widely used

·                  With two modes of action

·                  The bubbling of the soln when in contact with tissues and certain chemicals ,physically foams the debris from the canal

·                  The liberation of oxygen destroys strictly anaerobic microorg.

·                  The solvent action of H2o2  Is much less than that of NaOCl

·                  Many clinician use the soln alternatively 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 dislodigng food particles and debris packed in the canal

·                  Being a less solvent it cause less harm to the periapical tissues

·                  When procedural accidents have caused perforation or when the apical constriction has been destroyed with severe pericementitis, it is the preferred irrigant

·                  However it should not be the last irrigant used in the canal because the nascent oxygen may remain after the access preptn closure and build up pressure

·                  Therefore NaOCl should be used to react  with the H2o2  and liberate the oxygen remaining and the canals should be dried with paper points

CHELATING AGENTS.

The most common chelating solutions used for irrigation include  EDTA, and RC Prep, in all of which EDTA is  the active ingredient

Introduced by Nygaard-Ostby .Available in paste and liquid form

EDTA [ Ethylienediamine tetra acetic acid]

·                  Nontoxic and only slightly irritating to tissue 

·                  Highly stable soluble metal chelates in combination with heavy metals or alk. earth ions

·                  It functions by forming a Ca chelates solution with the Ca ions of dentin

·                  The effect of chelators in negotiating narrow, tortuous, calcified canals to establish patency depends both on canal width and on the amount of active substance available, as the demineralization process continues until all chelators have formed complexes with calcium.

·                  The dentin thereby becomes more friable and easier to instrument

·                  It is found effective for achieving canal patency ,enlargement and smear layer removal .Smear layer is a combination of dentin pulp or bacterial debris

·                  It exert its strongest effect when used synergistically with NaOCl

·                  Calcium binding results in the release of protons, and EDTA loses its efficiency in an acidic environment. thus the action of EDTA is thought to be self-limiting.

·                  The extent of demineralization is proportional to the exposure time

·                  It is employed by depositing few drops into the pulp chamber with a syringe and then carefully pumping the soln into the root canal with a fine root canal instrument

·                  When it is difficult to introduce a file into the canal due to intracanal calcification  or iatrogenic blockage then EDTA can be used

·                  One should try to negotiate such canals with an instrument coated with EDTA gel

·                  If the apical constriction is opened then the irrigant may seep periapically and damage the periapical tissue and bone

·                  Therefore at the completion it must be irrigated with NaOCl to inactivate it

·                  If it risk breaking a fine instrument , it is better to pump EDTA and wait for a min before instrumentation

·                  Once the apical foramen is reached and the canal is enlarged then the canal is irrigated in the usual manner

·                  It is also useful in the location of a canal, which is difficult to find ,by sealing in the chamber between appointment .because the orifices are less calcified than the surrounding dentin  and sufficient softening may allow it to be located with a sharp tip of the instrument

·                  The recommended regime for irrigation is to employ 17% EDTA for 1 min followed by a final rinse NaOCl

·                  Neutral EDTA showed a higher degree of decalcification of dentin surfaces than RC-Prep, although its effect was reduced in apical region

RC-Prep is composed of EDTA and urea peroxide in a base of Carbowax

       It has a natural effervescence that is increased with irrigation with NaOCl to aid in removal of debris

MTAD

·                  Newly introduced Which employs a mixture of tetracycline isomer[doxycycline], citric acid and a detergent as a final rinse to remove the smear layer

·                  Commonly employed after  initial irrigation with 1.3% NaOCl

·                  Antibacterial effect is high due to the presence of tetracycline

·                  Effectively removes the smear layer without significant changes in the dentinal tubules

·                  Use is controversial however because  of emergence of increasingly resistant strains

Carbamide peroxide

·                  It is available in an anhydrous glycerol base [Gly oxide] and is a useful irrigant

·                  Best tolerated by the periapical tissues with greater solvent action and is more germicidal than H2o2  .therefore it is best for treating canals with wide apices

·                  Due to its slippery effect it is best for narrow and curved canals and are less likely of perforation 

Electrochemically activated water

·                  Also  known as oxidative potential water recently was tested as a potential irrigant. This  solution is active against bacteria and removes the smear layer .It uses anode cathode system

Two types of ECA soln are

Ø    Anolytic-highly antimicrobial

Ø    Catholyte- strong cleaning ability

Physiologic Saline

·                  It is very mild and non toxic

Disadv – has poor antibacterial effect

BIS-DEQUALINIUM ACETATE [BDA]

·                  It is a disinfectant with low toxicity

·                  Has a low tension so flows into the accessory canals

·                  Exhibits low incidence of post operative pain

·                  An excellent substitute in patients allergic to NaOCl

RUDDLE’S SOLUTION

·                  New experimental irrigating soln in an attempt to visualize the microanatomy  of canal system

·                  Composition

                70%EDTA

§    55NaOCl

·                  Hypaque which is an aqu soln of iodide salt  ,ditrizoate and sodium iodine

Mechanism of action

I.              Solvent action of NaOCl,improved penetration of EDTA and radioopacity of hypaque helps to visualize the shape and microanatomy  of canals and dentin thickness during endodontic therapy

II.              The solvent actn of NaOCl clears the contents of root canal system and thus enable hypaque component flow into every nook  and corner of the canal system such as fracture , missed canal and defective restoration

Benefits of Using Irrigants in Root Canal Treatment

1.          Removal of particulate debris and wetting of the canal walls

2.          Destruction of microorganisms

3.          Dissolution of organic debris

4.          Opening of dentinal tubules by removal of the smear layer

5.          Disinfection and cleaning of areas inaccessible to endodontic instruments