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COLLEGE OF DENTAL SCIENCES DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS

Seminar On

ROOT CANAL IRRIGANTS

Presented by : -

Dr. Niju Aelias


CONTENTS  INTRODUCTION  PROPERTIES OF IDEAL SOLUTION  GOALS OF IRRIGATION  VARIOUS ROOT CANAL IRRIGANTS USED o NAOCl o H2 O2 o COMBINATION OF NaOCL + H2O2 o GLYOXIDE OTHER IRRIGANTS o CHLORHEXIDINE GLUCONATE o BDA o RUDDLE’S SOLUTION o ECA WATER o CHELATING AGENTS  EDTA  MTAD  IRRIGATION TECHNIQUE  FREQUENCY OF IRRIGATION  COMPLICATION  PRECAUTIONS


ďƒ° REFERENCES ďƒ° CONCLUSION INTRODUCTION : Total

cleaning

of

the

root

canal

system

using

mechanical

instrumentation is often ineffective due to extremely complex root canal morphology. Proper irrigation of the root canal system during endodontic therapy is vital to successful treatment. Many teeth have numerous accessory canals and fissure that cannot be negotiated by files. Since we are unable to place files in these accessory canals and irregularities, we rely on irrigants to perform chemical debridement in these areas.

For this reason, thorough irrigation of the canal system is

necessary for successful root canal therapy. PROPERTIES OF IDEAL SOLUTIONS : 1. Tissue solvent of both organic material (bacteria and pulp) and inorganic material (smear layer). 2. Sterilization or disinfection (antimicrobial activity). 3. Flushing gross debris accumulated during debridement. 4. Lubrication of canal to ease instrumentation. 5. Low toxicity so as not to harm periradicular and gingival tissue. 6. Low surface tension : This promotes its flow into inaccessible areas. 7. Antiseptic 8. Removal of smear layer Presently, there is no ideal irrigant that meets all of this criteria. GOALS OF IRRIGATION : Four goals of irrigation 1. Lavage of debris 2. Tissue dissolution 3. Antibacterial action and 3


4. Lubrication Although preliminary debridement is accomplished with hand instruments, this alone is not able to remove all the tissue remnants in the pulp chamber and canal. One must therefore rely on lavage and some means of chemical dissolution of the remaining tissue. Other variables are the method and the extent of canal instrumentation (studies have shown step back preparations leave less tissue debris). Other variables are ; • Quantity and temperature of the irrigating solution • The length of time of contact • The level of observation (apical, middle or coronal) • The presence of serum proteins • The depth of penetration of irrigating needle • The type and gauge of irrigating needle • The surface tension of irrigating solution and • The age of the solution E.g. Shelf life of 5.25% NaOCl was found to be 10 weeks. Whereas 2.6% and 1.0% was stable only for 1 weeks after mixing with water. MODE OF ACTION : When irrigants are used during instrumentation it loosens debris, pulp tissue and microorganisms from the irregular dentinal walls so that they can be removed from the canal. Since the reamers and files are much too large to fit into accessory canals, it is the solvent action that removes the tissue remaining there. Most irrigants have a germicidal / antibacterial effect. They also have a bleaching action to lighten color of teeth, which have been discoloured by trauma and decrease the chance of post-operative darkening. 4


VARIOUS ROOT CANAL IRRIGANTS USED : Many different types of solutions have been used for irrigation in endodontics since the first root canal was performed. 1. Water : Prior to 1940s, water was the most commonly used endodontic irrigant.  A stream of hot water (140-176oF) were also used. 2. Acids : Citric acid and phosphoric acid. 3. Alkaline solutions  Sodium hypochlorite (5.25%, 2.6%, 1%, 0.5%). 

Sodium hydroxide

 Urea  Potassium hydroxide 4. Oxidative agents  Hydrogen peroxide  Glyoxide 5. Chelating agents  EDTA 6. Normal saline 7. Anaesthetic solution Combination : 1. H2O2 and NaOCl 2. Glyoxide and NaOCl 3. RC prep and NaOCl 4. EDTA and NaOCl Acids : Such as sulfuric acids and hydrochloric acids were introduced to support the mechanical cleaning of the root canals. Recently citric acid and lactic acid have been suggested.

It removes smear layer (which is responsible for 5


harboring microorganisms) better than polyacrylic acid and phosphoric acid, the only disadvantage being citric acid left precipitate crystal in the root canal which might cause difficulty in root canal obturation. Saline : From biological point of view, it is sterile. It causes less apical tissue damage than other irrigants. Disadvantage : It has very less dissolving property and antibacterial activity. Hydrogen Peroxide : Most commonly used irrigant (it is used mainly in combination with NaOCl). It has 2 modes of action  It has effervescence effect which pushes out the tissue debris against the gravity. The bubbling of solution when it comes in contact with the tissue and certain chemicals physically forms debris from the canal.  It produces nascent O2 that destroys strictly anaerobic microorganisms. H2O2 is less effective as a solvent, so less damage to periapical tissue. Indication : When procedural accidents have caused either root or floor of the pulp chamber perforation or when apical constriction has been destroyed with severe pericementitis. Sodium Hypochlorite : The use of sodium hypochlorite for treating wounds was introduced during World War I by a physician named Dakin. Because antibiotics were not available until the bacteriologist, Alexander Fleming discovered penicillin. The solution used is called Dakin’s solution and is used for lavaging large flesh wounds.  Sodium hypochlorite is a reducing agent. 6


 It is a clear, straw coloured solution containing about 5% of available chlorine.  The solution should be kept in a cool place away from sunlight.  Popular household bleaching agents such as Clorox or purex are usually 5.2% solution of sodium hypochlorite and are satisfactory.  Solution ranging in strength from 0.5 to 5.25% have been recommended for use in endodontic.  NaOCl should be used clinically in concentration of 2.6 – 5.25% to take advantage of its ability to dissolve pulp tissue from all aspects of the root canal system.  Increasing concentration will increase the rate at which organic material is dissolved and may improve its effectiveness as an antibacterial agent.  50% dilution of commercial preparation (clorox) with distilled water gives a solution of 2.6% NaOCl.  Heating the solution will have a similar effect. Clinically a 60o C warm water bath is prepared by placing a beaker of water on a hot plate. Preloaded syringes of NaOCl maybe warmed by placing them into this warm water bath.  Solutions of NaOCl should be prepared fresh daily to obtain optimal clinical results.  Stable shelf life of 5.25% NaOCl – 10 weeks. Whereas 2.6 and 1.0% NaOCl -1 week after mixing with water.  To maximize tissue dissolution, access cavities must be filled with NaOCl during the entire cleaning and shaping procedure, the irrigant will act as a ; o Lubricant o Solvent of pulp tissue o Antiseptic o Bleach  NaOCl is not only a pulp solvent and root canal irrigant but also it has significant antimicrobial properties. 7


 Disinfection by means of NaOCl is initially slow, but increases progressively.  In fact one of the most advantages of pretreatment is to build teeth up so they have pulp chambers that can retain irrigants.  The potential for an irrigant is maximized when it is heated, flooded into shaped canals and given ample time to work. Destruction of Bacteria takes place in two phases : 1. Penetration into the bacterial cell and 2. Chemical combination with the protoplasm of the bacterial cell that destroys it. Disadvantage : 1. NaOCl is toxic to living tissue and extrusion of liquid through apices of teeth can cause post-operative pain, swelling and necrosis. However, the limited extrusion of NaOCl is unlikely to be significant because it is diluted and buffered by tissue fluids apically. 2. Because of corrosive nature of NaOCl, ultrasonic units used in canal irrigation are prone to mechanical breakdown. 3. Taste of NaOCl is unacceptable to patient and Vapours can irritate eye. Alternate irrigations with sodium hypochlorite and H2O2. Advantages of alternating solution of 3% H 2O2 and 5.25% sodium hypochlorite are ; 1. Their interaction in the canal produces a transient but energetic effervescence in which it mechanically “bubbles’ and pushes debris out of the root canal through the least resistant orifice into the chamber. 2. The solvent action of sodium hypochlorite on the organic debris of the pulp tissue. 3. O2 liberated by H2O2 destroys anaerobic microorganisms. 4. The disinfecting and bleaching action by both the solutions.

8


One should always use sodium hypochlorite last because hydrogen peroxide can react with pulp debris and blood to form gas (nascent O 2). Any gas trapped within the tooth will cause continuous pain. Therefore NaOCl should be used to react with H 2O2 and liberate the O2 remaining, and then the canal is dried with paper points and closed. Indications : The root canals that has been left open for drainage, since the effervescence is effective in dislodging food particles as well as other debris that may have packed the canal. Glyoxide :  Carbamide peroxide is available in an anhydrous glycerol base to prevent decomposition and is a useful irrigant.  It is better tolerated by periapical tissue than NaOCl and has greater solvent action and is more germicidal than H2O2. Therefore it is an excellent irrigant for treating canals with normal periapical tissue and wide apices, in which the more irritating solution would cause severe inflammation when forced out of the canal.  The best use of glyoxide is in narrow or curved canals, utilizing the slippery effect of the glycerol. Whereas chelating agents react with dentin and may cause root perforation or ledging in the softened walls, this action will not occur with glyoxide, where only lubrication is enhanced. Because the canals walls are slippery, they are easier to prepare but are less likely to be gouged or perforated.  It has been reported that NaOCl does not reach the apex of small canal until the canals are enlarged to size 20 or greater. However, Glyoxide being more vicious with a high surface tension can be manipulated into very small canals and will liberate oxygen.  According to weine Glyoxide as a major irrigant should be used in small canals until size 20 is reached and then switch to NaOCl.

9


OTHER IRRIGANTS : Chlorhexidine gluconate : • Chlorhexidine is a biguanide. • Chlorhexidine (0.2%) is used as an irrigant. • It posses a broad spectrum antimicrobial action, substantivity and a relative absence of toxicity. • Chlorhexidine causes cytoplasmic precipitation or coagulation on the cell wall. • Studies have shown that the alternate use of NaOCl and chlorhexidine gluconate irrigants resulted in a greater reduction of microbial flora when compared with the individual use of NaOCl or chlorhexidine gluconate alone. Disadvantages : It does not dissolve the pulp tissue. Bis-Dequalinium Acetate (BDA) :  It is used as a disinfectant and chemotherapeutic agent.  It has o Low toxicity o Lubrication action o Disinfecting ability o Low surface tension o Chelating properties o Low incidence of post operative pain.  It was marketed as Solvidont.  BDA is recommended as an excellent substitute for NaOCl in those patients who are allergic to NaOCl.

10


Visualization Endogram : Central to successful endodontic treatment has been the use of chemicals to penetrate, circulate, and clean all aspects of the root canal system. The most important chemicals used to actively clean the root canal system, NaOCl and chelating agents, are radiolucent. Therefore these reagents do not help the dentist radiographically to visualize the anatomy of the root canal system. Conventional radiographs and digital radiography do not have sufficient resolution to completely reveal the intricacies and microanatomy of the root canal systems. Recently a new experimental irrigating solution, the Ruddle’s solution, has been formulated to provide a breakthrough in clinical endodontic. Ruddle’s Solution : It contains ♦ 5% NaOCl ♦ Hypaque ♦ 17% EDTA  Hypaque is a high contrast and injectable dye Used in medicine for - Angiography Arteriography Urography & Nephrotomography  Hypaque is an aqueous solution of 2 iodine salts, diatrizoate meglumine and sodium iodine.  This is a radiopaque contrast solution to radiographically visualize root canal system.  The solution has the same specific gravity as NaOCl, is water soluble, has a pH of 6.7 to 7.7, and is stable at room temperature.  This composition simultaneously provides the solvent action of full strength NaOCl, visualization (because its radiodensity is similar to

11


gutta percha), and improved penetration (because the tensioactive agent lowers surface tension). ďƒ°

Clinician can use endogram to visualize the microanatomy, verify the shape and monitor the remaining root wall thickness during preparation procedure. Clinically, the solution is flushed into the root canal system of a tooth

once sufficient access to the pulp chamber has been made.

The sodium

hypochlorite portion of the composition will dissolve the pulp and eliminate the bacteria, along with endotoxins that are harbored within the root canal system. The solvent action of this solution progressively clears out the contents of the root canal system, thus enabling the iodine portion of the composition to flow into this vacated space. Endograms are useful in visualizing pathologic events, such as caries, certain fractures, missed canals, and leaking restorations. Additionally, endograms can assist the clinician in managing internal resorption, because the solution will map its location, size, and extent. In endodontic nonsurgical retreatment, the endogram has shown promise for improving diagnostics, treatment planning, and management of iatrogenic mishaps. This method of visualization assists dentists in determining the best course of action and in deciding whether to salvage or extract a particular tooth. Electrochemically Activated H2O (ECA) : Electrochemically Activated Water is produced with a new and unique anode – cathode system. The solution suppose to exist in a metastable state for 48 hours after production and contains many free radicals and variety of molecules. After 48 hours the solution returns to stable state becoming inactive again. In metastable state the solution have very high oxidation reduction potential.

12


Two types of ECA solution are produced. 1. Anolyte : High oxidation potential 400-1200 milli volts. It is possible to produce acidic, neutral or alkaline (pH 2-8). Anolyte is highly antimicrobial. 2. Catholyte : Alkaline solution (pH 7-12) with reduction potential. Catholyte have strong cleaning and detergent effect. CHELATING AGENTS : Chelating agents containing Ethylenediamine Tetra Acetic Acid (EDTA) may be used clinically for cleaning and shaping. • The purpose of a chelator is for lubrication, emulsification and holding debris in suspension. • Chelators are formulated for clinical use and can be selected in either a viscous suspension or an aqueous suspension. • Viscous suspension has several ingredients typically suspended in a water soluble vehicle. • A viscous suspension of a chelator advantageously promotes the emulsification of organic tissue and facilitates the negotiation of the canal and is best used for holding debris in liquid suspension. • An aqueous solution of chelator is best reserved for finishing the preparation, it removes the smear layer in an organic or inorganic film or both formed on the walls of the canal by the cutting action of instruments. EDTA : Nygard Ostby was the first who suggested the use of EDTA for cleaning and widening canals.  If functions by forming a calcium chelate solution with the calcium ion of dentin, the dentin thereby becomes more friable and easier to instrument.

13


 EDTA is used during cleaning and shaping of the root canal and is effective for achieving canal patency, enlargement, debridement and disinfection.  EDTA contains four acetic acid groups attached to ethylenediamine. C2H3O2

C2H3O2 N-CH2 –CH2-N

C2H3O2

C2H3O2

The formula is as follows : Disodium salt of EDTA

: 17.0 g

Distilled water

: 100.0ml

5N Sodium hydroxide

: 9.25 ml

Effects of EDTA : 1. EDTA is effective in softening dentin 2. EDTA has distinct antimicrobial properties. 3. EDTA is capable of causing a moderate degree of irritation. 4. EDTA has no deleterious effect when used clinically as an irrigating solution. 5. Irrigation with EDTA removes the smear layer. 6. The extent of demineralization of EDTA is proportional to the exposure time. 7. EDTA effects partial demineralization of dentin to a depth of 20 to 30 µm in 5 minutes.  Optimum working time of EDTA – 15 minutes, after which no more chelating action can be expected. EDTA solutions should perhaps be renewed in the canal each 15 minutes. The most common chelating solution used for irrigation include Tublicid, EDTA, EDTAC, File Eze and RC-Prep in all of which EDTA is the active ingredient.

14


RC Prep :  RC prep is a viscous chelator.  Its principle ingredients are EDTA, Urea Peroxide and Propylene Glycol in a base of Carbo Wax.  Glycol is the lubricant that coats instruments and facilitates their movements in canals, coating calcific material or in restricted canals that exhibits various degree of calcification.  It is not water soluble.  Irrigation with NaOCl following the use of RC prep removes smear layer and produces significant effervescence, creating an elevator action to evacuate debris that was dislodged from the root canal system.  Since it is foamy, RC prep is placed on flutes of a file and carried directly to walls of canal being prepared. EDTAC : The addition of Cetavlon (0.84 gm), a quaternary ammonium compound to EDTA produce a solution called EDTAC, which has greater germicidal activity.  It has greater inflammatory potential to tissue as well.  The inactivator for EDTAC is NaOCl. Other Chelating Agents : Salvizol

:

N1, N1 decamethylene –N4, N4 decamethylene bis 4

aminoquinaldinium – diacetate  Salvizol with neutral pH has broad spectrum of bactericidal activity as well as the ability to chelate calcium. This gives the product cleansing potency while being biologically compatible. Procedure : Chelating agents are placed in the orifice of the canal to be enlarged, on the tip of the endodontic explorer or on the flutes of the enlarging instrument if

15


the agent is foamy (as in RC-Prep) or by plastic irritating syringe, if liquid (eg. EDTA). EDTA reacts with glass so syringes of that material should not be used.  Then the chelating agents are carefully pumped into the root canal with a fine root canal instrument.  Instrumentation is continued with the solution bathing the canal at all times until cleaning and shaping are completed.  When it is difficult to introduce a file into the canal one should try to force the EDTA ahead of the instrument.  When the canal is patent except for the last 2 or 3 mm, the same technique should be used to reach the apical foramen.  If the root canal of a posterior tooth is narrow and if one risks breaking a fine instrument, it is better to pump EDTA into the canal and wait 2 or 3 minutes before attempting instrumentation. Once the apical foramen has been reached and the canal has been enlarged, the canal should be irrigated in the usual manner. Irrigation Technique :  Systems for the delivery of irrigating solution into the root canal ranges from simple disposable syringe to complex devices capable of irrigating and aspirating simultaneously.  Disposable plastic syringes of 2.5 or 5 ml capacity with 25 or 27 gauge blunted needles are useful for endodontic irrigation.  The smaller syringe barrels (i.e. less than 10 ml) require frequent refilling during the instrumentation phase of therapy. Plastic syringes in the 10 to 20 ml range may offer the best combination of sufficient solution volume and ease of handling. “Back filling” of a syringe from a 500 ml laboratory plastic wash bottle filled with the irrigant of choice saves time and effort when compared with aspirating the solution into the barrel from a container.

16


 The barrel tip should be a Leur Lok design, rather than friction fit to prevent accidental needle dislodgement during irrigation.  The needle should be bent to an obtuse angle, to reach the canals of posterior as well as anterior teeth.  The needle is inserted into the root canal so that it does not binds. Sufficient room between needle and canal wall allows for the return flow of the solution and avoids forcing of solution into the periapical tissue.  When one is certain that the needle does not bind, the solution should be ejected from the syringe with little or no pressure on the plunger. The object is to wash out the canal and not to force the solution under pressure into periradicular tissues.  During the cleaning and shaping of the root canal, care should be taken that the canals are always full of fresh solution.  In narrow root canals, the tip of the needle is placed near the root canal orifice and the irrigant is discharged until it fills the pulp chamber. The solution is then pumped into root canal with a file.  The return flow of solution is caught on a gauze sponge or is aspirated.  Irrigation should be followed by thorough drying of the root canals after the completion of cleaning and shaping. Most of the residual irrigating solution may be removed from the root canal by holding the needle of the syringe in the canal and withdrawing the plunger slowly. Final drying should be effected with absorbent points.  Compressed air must not be used for drying the root canal because tissue emphysema may result if an air bubble penetrates the periapical tissue. Frequency Of Irrigation : The frequency of irrigation is dictated by the amount of work that a particular instrument performs. As a rule, a clinician should irrigate copiously, recapitulate, and reirrigate at least after every two to three instruments.

17


Generally, this cycle should be repeated more frequently in tighter, longer, and more curved canals, and especially if the system exhibits unusual anatomy. Files potentially carry irrigant progressively deeper into the canal by surface tension. However, when an instrument is placed into a relatively small canal, the file tends to displace the irrigant. When the instrument is withdrawn, the irrigant usually flows back into the space the file occupied, unless there is an air pocket.

This phenomenon must be appreciated to integrate the most

efficacious irrigation method clinically. Advanced Irrigating Needle : Max I Probe Needle or Pro Rinse Max I probe irrigates through side vent and the apical end of the probe is closed. It consists of 25, 28 and 30 gauge closed ended needles. Advantages : Prevents accidental forcing of irrigating solution into periapical tissue Endo Irrigator : Recently new technologies have been developed that deliver various type of ‘on line’ irrigants from in office air pressurized bottles. In this method of irrigation, clinician can select among several solutions with a push of a button. Various gauged canuli can then be selected and attached onto the irrigating

handpiece.

New irrigation

technology

allows

clinician to

conveniently choose, dispense and more effectively irrigate root canal systems. MTAD : A new solution for the removal of the smear layer. Mixture of Tetracycline isomer (Doxycycline) + Acid (citric acid) + Detergent (Tween 80).

18


MTAD is an effective solution for the removal of the smear layer and does not change the structure of dentinal tubules when canals are irrigated with NaOCl and followed with a final rinse of MTAD. Tetracycline including Tetracycline HCl, Minocycline and Doxycycline are Broad Spectrum Antibiotics that are effective against a wide range of microorganisms. Mechanism of action : Tetracycline has the following properties : a) It is bacteriostatic in nature.

This property may be advantageous

because in the absence of bacterial cell lysis, antigenic byproducts (i.e. Endotoxins) are not released. b) Low pH : Thus it can act as a calcium chelator and cause enamel and root surface demineralization. c) Substantive medication : Becomes absorbed and is gradually released from tooth structures such as dentin and cementum have prolonged effect. d) It significantly enhances healing after surgical periodontal therapy. Similar attempts with penicillin and erythromycin were ineffective. Acid : Doxycycline and Citric acid were effective in removal of smear layer when used for 1 to 5 minutes. Detergent : The role of the detergent in this mixture is to lower the surface tension and increase the generating ability of the irrigating solution. Experimentation with various concentrations of these material showed that a mixture of Doxycycline, Citric acid and Tween-80 was capable of removing the smear layer from the surface of instrumented root canals better than a combination of Doxycycline and citric acid alone. Advantages over EDTA : The smear layer contains organic and inorganic components. To remove the smear layer, irrigating solutions should dissolve both components.

19


EDTA : Is an effective etchant and can remove the smear layer when used alternatively with 5.25% NaOCl. Disadvantages over EDTA : -

This removal is limited to the coronal and middle thirds of the canal preparation.

-

But this combination is less effective in the apical third probably because of inadequate volume and/or penetration of the solution.

-

Has destructive effects on the coronal and middle thirds of root dentin (severe erosion).

-

Limited antibacterial effects.

-

The destructive effects of 5 minutes – EDTA exposure, no significant dentinal erosion was observed on surface in contact with MTAD for periods ranging from 1 to 20 minutes.

So these reasons make us believe that MTAD is a superior material to EDTA for the removal of smear layer. Ultrasonics : Richman in 1957 was the first to use ultrasonic scaler for apicoectomies. He was followed by Martin who designed a commercial system harnessing the ultrasonic energy for the preparation and cleaning the root canal in 1976. This technique was termed endosonics. Endosonics : Martin and Cunningham have coined the term endosonics, to refer to endodontic treatment by supersonic, sonic or subsonic systems. There are principally two different types of devices. 1. The ultrasonic device which oscillates at a frequency of 20-30 KHz. Eg. Caviendo, Piezo Ultrasonic. 2. The sonic device which oscillates at a frequency of 1-6 KHz. Eg. Endosonic air.

20


Method for Action : Ultrasonic cleaning was described initially as Implosion or Cavitation. Cavitation occurs when ultrasonic file vibrates in a liquid to produce alternating compression and rarefaction of pressure in the form of growth and subsequent violent collapse of bubbles in fluid. A negative pressure develops within the exposed cells of the intracanal materials (pulp tissue, bacteria, debris, metabolites, substrates etc). This causes an implosion or inward explosion that breaks these cells apart inwardly and leads to their destruction. Since an irrigation / aspiration system is employed in the endodontic equipment for ultrasonics, the broken cell part are washed out and then removed from the canal system. The atomic bomb also works by the Implosion principle. In 1975 Ahmad and her group described another mechanism for ultrasonic cleaning – Acoustical Streaming. Ahmad stated that cavitation cannot occur in closed environment as in root canals for 2 reasons. 1. For cavitation to occur in root canal the file must vibrate at a displacement amplitude of atleast 135 micrometers and power setting in endosonic unit was too low to produce this amplitude. 2. Cavitation also depends on the free displacement amplitude of the file. This would be impossible to achieve during instrumentation because when the file contacts the canal walls there will be reduction in amplitude. Acoustic Streaming : Acoustic streaming is produced around an object oscillating in a liquid, that is it creates small, intense circular fluid movement (i.e. eddy; flow) around the instrument.

21


It is characterized by the production of large shear forces that are capable of dislodging or disassociating lumps of material. However the forces of acoustic streaming are not sufficient to break up the bacterial cell wall. The eddying occurs closer to the tip than in the coronal end of the file, with an apically directed flow at the tip. Streaming forces occurring around the file disassociate clumps of bacteria without disrupting them. The acoustic streaming generated by the file help reduce the number of bacteria in the canal by removing the smear layer and debris harboring bacteria, thereby facilitating their mechanical removal. The main advantage of ultrasonic files is that they move irrigant around the canal and penetrate to the most apical extent of the instrument. The general conclusion is that acoustic micro streaming does occur around the oscillating file. To be effective in this action, the file must be kept moving at all times so that free oscillation can be maintained. Instruments are generally moved circumferentially within the canal space. COMPLICATIONS OF IRRIGATING SOLUTION 1. Damage to clothing. 2. Damage to eye 3. Injection of NaOCl beyond apical foramina 4. Injection of H2O2 beyond apical foramina 5. Tissue emphysema 6. Hypersensitivity to NaOCl DAMAGE TO CLOTHING : NaOCl is a common household bleaching agent and even a small amount when falls on clothing may cause severe damage to clothes. This complication can be prevented by giving proper protection to patient and operators clothing.

22


DAMAGE TO EYE : NaOCl (5.25%) in aqueous solution is very alkaline (pH 10.8 to 11) and its accidental splashing into eye is hazardous. Alkaline chemicals tend to penetrate tissues. Clinical symptoms after such accidents are ; -Pain - Photophobia - Blepharospasm Mechanism of Injury : Anatomy of Cornea : It consists of 5 layers. 1. Epithelial layer (5-6 layers) 2. Bowman’s layer 3. Stroma 4. Descemet’s membrane 5. Endothelium  When a chemical injury occurs, the corneal epithelium is the first to get damaged and this corneal epithelium consists of rich plexus of unmyelinated sensory nerve ending. As a result nerve endings are exposed and patient experiences burning sensation and photophobia.  Under normal circumstances, the cornea is an effective barrier to microorganism. Once traumatized the pavement epithelium is no longer intact allowing access to the underlying avasuclar stroma and bowman’s layer. As a result of unprotected layer it provides an excellent culture medium for many organisms especially Pseudomona Arginosa, Streptococcus Viridans and Staphylococcus.  Once NaOCl is splashed on the surface of the eye it is physically absorbed by the protein structures of corneal epithelium (some portion) and remaining portion continues to diffuse into previously unaffected 23


deep layers. This progressive spread has a potential of involving entire epithelial layer and reaching bowman’s layer, where irreversible tissue damage may result. For this reason early treatment is utmost important to prevent damage i.e. by irrigation. Treatment : 1. Irrigation of affected eye with sterile normal saline.

The sterile

hypertonic salt solution resolves corneal oedema and debris of eye. 1 liter bag completely used : 10-15 minutes. 2. Antidote should not be used. Heat generated by reaction with chemical may increase degree of injury. 3. During irrigation upper and lower eyelids should be everted. 4. Medical Treatment Cetrapred : Combination of antibiotics and steroidal ophthalmic solution. Vascon A : Îą receptor stimulant and antihistamine combination. INJECTION OF SODIUM HYPOCHLORITE BEYOND APICAL FORAMINA : Causes : 1. Teeth with wide apical foramina. 2. Apical constriction destroyed during instrumentation. 3. Apical resorption 4. Extreme pressure during irrigation. 5. Binding of irrigating needle to root canal with no space for the irrigant to come out coronally. As a result large volume of irrigant will contact apical tissues. Symptoms : 1. Immediate severe pain, swelling 2. Immediate oedema

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3. Profuse bleeding from root canal 4. Ecchymosis 5. Chlorine taste and irritation of throat after injection into maxillary sinus. 6. Parasthesia is possible. Treatment : 1. Pain control – Anesthesia 2. Antibiotics and Analgesics : Because of the potential for spread of infection related to tissue destruction it is advisable to prescribe antibiotics in addition to analgesics for pain. 3. Antihistamines can also be given. 4. Extraoral cold compresses (ice packs) : 1st day for reduction of swelling. After 1st day - warm compresses and frequent warm saline mouth rinses for stimulation of local systemic circulation. The use of intramuscular steroids, and in most severe cases, hospitalization and surgical intervention with wound debridement may be necessary. Allergic Reactions to NaOCl : If the patient is allergic to household bleach, the dentist should choose a substitute irrigant during endodontic therapy. INJECTION OF H2O2 BEYOND APICAL FORAMINA : -

Pain

-

Swelling, erythema

-

Crepitus – Air moving in tissue space -cracking sound Similar to sound produced by rubbing together fragments of fractured bone.

-

Emphysema

25


Treatment : Antibiotics Analgesics TISSUE EMPHYSEMA : Tissue space emphysema has been defined as the passage and collection of gas in tissue spaces or facial planes. Etiologic Factors : Compressed air being forced into tissue spaces. Two procedures in endodontics, if carried out improperly have a potential to cause problem. 1. During canal preparation, a blast of air to dry the canals. 2. During apical surgery, air from a high speed drill can lead to air emphysema. Clinical Features : Rapid swelling, erythema and crepitus. Tissue space emphysema remains in the subcutaneous connective tissue and usually doesnot spread into deep anatomical spares. Migration of air into neck region could cause respiratory difficulty and progression into mediastinum could cause death. There are several diagnostic signs of mediastinal emphysema. 1. A sudden swelling of the neck. 2. The patient may have difficulty in breathing and his voice would sound brassy. 3. The characteristic crackling can be induced when the swollen regions are palpated. Finally, the mediastinal crunching noise on auscultation and air spaces are seen on anteroposterior and lateral chest radiographs.

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Treatment : -

Palliative care and observation to immediate medical attention if the airway or mediastinum is compromised.

-

Antibiotic coverage – to prevent risk of secondary infection.

Prevention : -

Use paper points to dry root canals.

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In surgical procedures, once a flap is reflected, apical access can be made with the slow speed or high speed handpiece that do not direct jets of air into surgery sites.

PRECAUTIONS : 1. Correct working length determination to be taken. 2. Ask the patient whether hypersensitive to household bleach or not before starting endodontic procedure. 3. Patients eyes and clothing should be protected effectively against irrigating solution. 4. Use lock type syringe rather than friction fit. 5. During irrigation a low and constant pressure should be used and operator must ensure that excess irrigant leaves the root canal coronally via the access cavity. 6. Never place needle so deeply into the canal that it binds against the walls. 7. Oscillate the needle in and out of the canal to ensure that the tip is free to express irrigant without resistance. 8. Stop irrigating if the needle jams. 9. Never use compressed air to dry the root canals – use paper points. 10. When H2O2 and NaOCl are alternatively used, always use NaOCl last because H2O2 can react with pulp debris and blood to form gas and any gas trapped within the tooth will cause continuous pain. 11. Wedging the irrigating needle into canal must be avoided and a side delivery orifice needle is recommended.

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CONCLUSION : Regardless of which type or combinations of irrigants are used, it is important to remember several points. The type of irrigant is only part of the cleaning and shaping process. Gross removal of tissue is very important to the dissolution of the remaining tissue, if the majority of the tissue can be removed with files and initial irrigation, this leaves less material to be dissolved. It is also important to remember that without proper access preparation and canal enlargement, it is nearly impossible to get deep enough needle penetration to allow the irrigant to provide the maximum benefit at the apical portion of the tooth. These two are very important, since even if we discover an ideal irrigant, it will be ineffective without proper access and canal preparation. Since there is no ideal irrigant and since many different types and combinations of irrigants have been used successfully in root canal therapy, it is important for the practitioner to choose an irrigant that works best for them.

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Root canal irrigants/ dental implant courses by Indian dental academy