Giftson Rajarajan1, Pavithra Priyadorshini S2, Chandana Subbarao3
1Graduate student, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences,
Saveetha University, Chennai
2Tutor, Department of Public Health Dentistry, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai
3Reader, Department of Endodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai
The purpose of this review is to assess the efficacy of different irrigating solutions in the removal of the smear layer from the root canal. Irrigating solutions are used in root canal treatment for the removal of the infected tissue which may still be present especially in the accessory canals. There are other uses for irrigating solutions like anti microbial property and lubrication .The removal of smear layer is vital for the adaptation of the obturation material to the root canal walls and the prevention of reinfection as some micro organisms penetrate deeper into the dentinal tubules. The most commonly used irrigating solution in day to day use are sodium hypochlorite and chlorhexidine gluconate which are said to have very good anti microbial efficacy but inefficiency in the removal of smear layer. This review focuses on the establishment of irrigants in the removal of smear layer and its use in routine procedures.
The aim of endodontic treatment is the complete removal of pulp all tissues and micro organisms, that remains in the root canal system and provides an appropriate root canal filling and consequently the repair of the periapical tissues. The success of any endodontic treatment depends on the meticulous use of the endodontic triad. The endodontic triad consists of the following steps which includes canal preparation, sterilisation and obturation. Preparation of root canal system includes both enlargement and shaping of the complex root canal spaces.(1)
Bacteria present in the canals must be removed by irrigants. However bacteria in the deeper canal areas will remain in the bacteria even after conventional root canal treatment and may occasionally cause periapical complications. Such bacteria should be eliminated to ensure a successful outcome. The purpose of obturation is to prevent the reinfection of the cleaned, shaped and disinfected root canal. Successful obturation involves the use of materials and techniques capable of densely filling the 3 dimensional root canal spaces and providing a fluid tight seal in the apical and coronal part to prevent reinfection.(2) It is essential that a thorough chemomechanical debridement of pulpal tissue, dentin debris, and infective microorganisms is achieved. Irrigants can augment mechanical debridement by flushing out debris, dissolving tissue, and disinfecting the root canal system. Chemical debridement is especially needed for teeth with complex internal anatomy such as fins or other irregularities that might be missed by instrumentation. Some of the commonly used irrigating solutions are sodium hypochlorite, ethylenediamine tetra acetic acid (EDTA) and chlorhexidine.
The most commonly used root canal irrigants in endodontic treatment are hypochlorites, EDTA (Disodiumethylenediaminetraacetic acid), hydrogen peroxide, chlorhexidine and chloramine.
Hypochlorites are the most frequently used root canal irrigants since their introduction as a successful root canal irrigant in 1936 by Walker. Hypochlorites include sodium hypochlorite and natrium hypochlorite.(3) Hypochlorite have a proteolytic effect. Wherein the necrotic tissues and detritus are dissolved. In addition to this it also has bactericidal effect. Anti microbial and viricidal effect are achieved by the oxidative effect of oxygen, but a.so by addition of chlorine, which has an oxidative effect, in addition it destroys cytoplasm and inhibits dehydrogenases in microorganisms. In endodontic concentrations of 0.5%, 1%, 2.5%, 5.25% are used. The most commonly used concentration is 1% since it provides optimum antibacterial effect. However the time taken for inhibition of microorganisms is shortened at higher concentrations.(4) But a higher concentration poses a threat to surrounding tissues like periapical tissues and mucosa of oral cavity. Due to this it is not recommended to use above 1% concentration without coffer dams. Hypochlorites are highly bio compactible. They never show any mutagenity, toxicity, teratogenity, carcinogenity or allergic effects. Another main feature of Hypochlorites is that it dissolved only the organic part of the smear layer but does not remove it completely. This reaction with only the organic part is termed as 'soap effect'. This is because sodium hypochlorite is a base and dissolves only the proteins. This soap effect increases the effectiveness of the endodontic tools and lowers the risk of their breakage.
EDTA (Disodiumethylenediaminetraacetic acid) is not a disinfecting agent instead it is a chelate creating of decalcification agent. It dissolved the inorganic part of the smear layer, softens the dentin, degrades calcification and obliterates the root canals. 17% is the commonly used concentration. It is generally left inside the root canal for 15 minutes for optimal results. EDTA is commonly used in the form of a gel. It is necessary to supplement these gels with sodium hypochlorite irrigation which is responsible for the proteolytic effect on organic part of the smear layer and neutralisation of EDTA.
Hydrogen peroxide has an anti ironical effect and dissolves tissues and peroxide affects anaerobic bacteria. A major drawback in the usage of peroxide is the cases of emphysema caused due to liberation of oxygen bubbles into soft tissues. (5) Therefore it must not be used under strong pressure. The recommended usage is 3% however peroxides have a low effectiveness.
Chlorhexidine is a bisguanide, while for irrigation its salt with gluconic acid (chlorhexidine gluconate) is used. It is either a fluid or a gel and is used in the concentrations of 0.2%, 1% and 2%. It's is the most effective anti microbial agent which has both bacteriostatic and bacteriocidal properties. It has a wide spectrum of effectiveness against gram negative and gram positive bacteria, Yeast and fungi. It is well dissolvable in water and its effect is minimally 7 hours but can last even more than 12 hours. It binds to the cell wall of the bacteria and damages the lipoprotein membrane of the bacteria to provide a bacteriostatic effect. (6)At higher concentration it penetrates through the cell wall of the bacteria and acts bactericidally. They are non toxic, non teratogenic and do not cause cancer. But chlorhexidine is not commonly used in endodontics.(7)
Chloramine is a monocrytalic powder with a strong odour of chloric acid. It is non toxic and non irritant. 2% concentration is used as an irrigant.(8) It has a stronger anti microbial effect in combination with hydrogen peroxide.
All the irrigation solutions at our disposable have their share of limitations and the search for an ideal root canal irrigant continues with the development of newer materials and methods. Therefore new root canal irrigants are and developed.(9)
MTAD is a mixture of doxycycline, citric acid, and a detergent (Tween 80). Since its introduction, it is a material that has been researched extensively for its properties(10). Manufacturer instructions for using this irrigant were flooding the root canal with 1 mL of the irrigant and soaking for 5 minutes, and the remaining 4 mL is then delivered with continuous irrigation and suction. MTAD has some advantages over conventional irrigants and solutions used in root canal treatment. (11) MTAD is effective in removing the smear layer along the whole length of the root canal and in removing organic and inorganic debris and does produce any signs of erosion or physical changes in dentine, whereas a mixture of 5.25% sodium hypochlorite and 17% EDTA does. In particular, MTAD is less cytotoxic than a range of endodontic medicaments, including eugenol, hydrogen peroxide (3%), EDTA, and calcium hydroxide paste.
Tetraclean (Ogna Laboratori Farmaceutici, Muggiò (Mi), Italy), like MTAD, is a mixture of an antibiotic, an acid, and a detergent.(12) However, the concentration of the antibiotic, doxycycline (50 mg/mL), and the type of detergent (polypropylene glycol) differ from those of MTAD. But tetraclean has higher level of biofilm disintegration when compared to MTAD.
Electrochemically Activated (ECA) solutions are produced from tap water and low-concentrated salt solutions. (13) Principle of ECA is transferring liquids into a metastable state via an electrochemical unipolar (anode or cathode) action through the use of an element/reactor (“Flow-through Electrolytic Module” or FEM). The FEM consists of an anode, a solid titanium cylinder with a special coating that fits coaxially inside the cathode, a hollow cylinder also made from titanium with another special coating. A ceramic membrane separates the electrodes. (14) The FEM is capable of producing types of solutions that have bactericidal and sporicidal activity; yet they are odourless, safe to human tissue, and essentially noncorrosive for most metal surfaces. Electrochemical treatment in the anode and cathode chambers results in the synthesis of two types of solutions: that produced in the anode chamber is termed an Anolyte, and that produced in the cathode chamber is Catholyte. Anolyte solutions containing a mixture of oxidizing substances demonstrate pronounced microbiocidal effectiveness against bacteria, viruses, fungi, and protozoa. Anolyte solution has been termed Superoxidized Water or Oxidative Potential Water. Depending on the type ECA device that incorporated the FEM elements the pH of anolyte varies; it may be acidic (anolyte), neutral (anolyte neutral), or alkaline (anolyte neutral cathodic); acidic anolyte was used initially but in recent years the neutral and alkaline solutions have been recommended for clinical application. (15) Under clean conditions, freshly generated superoxidized solution was found to be highly active against all these microorganisms giving a 99.999% or greater reduction in two minutes or less. That allowed investigators to treat it as a potent microbiocidal agent. ECA is showing promising results due to ease of removal of debris and smear layer, nontoxic and efficient in apical one third of canal. It has a potential to be an efficient root canal irrigant.
Ozone is a very powerful bactericide that can kill microorganisms effectively. It is an unstable gas, capable of oxidizing any biological entity. (16) It was reported that ozone at low concentration, 0.1 ppm, is sufficient to inactivate bacterial cells including their spores. It is present naturally in air and can be easily produced by ozone generator. When introduced in water, ozone dissolves rapidly and dissociates rather quickly. The concentration of ozone in ozonated water can be measured using a dissolved ozone meter. Although ozonated water is a powerful antimicrobial agent against bacteria, fungi, protozoa, and viruses, less attention has been paid to the antibacterial activity of ozonated water in bacterial biofilm and hence in root canal infection. (17)There is need for further studies and modifications in ozonated water before it could be used as a root canal irrigant.
Herbal irrigants have also been introduced. Triphala is an Indian ayurvedic herbal formulation consisting of dried and powdered fruits of three medicinal plants, Terminalia bellerica, Terminalia chebula, and Emblica officinalis, and green tea polyphenols (GTPs; Essence and Flavours, Mysore, India); the traditional drink of Japan and China is prepared from the young shoots of tea plant Camellia sinensis.(18) Herbal alternatives showed promising antibacterial efficacy on 3- and 6-week biofilm along with MTAD and 5% sodium hypochlorite. Triphala is proven to be safe, containing active constituents that have beneficial physiologic effect apart from its curative property such as antioxidant, anti-inflammatory, and radical scavenging activity and may have an added advantage over the traditional root canal irrigants.
Photon activated disinfection is another promising area in Endodontic irrigation. Photo dynamic therapy PDT is based on the concept that nontoxic photosensitizers can be preferentially localized in certain tissues and subsequently activated by light of the appropriate wavelength to generate singlet oxygen and free radicals that are cytotoxic to cells of the target tissue. Methylene blue (MB) is a well-established photosensitizer that has been used in PDT for targeting various gram-positive and gram-negative oral bacteria and was previously used to study the effect of PDT on endodontic disinfection. It is suggested the potential of PDT to be used as an adjunctive antimicrobial procedure after standard endodontic chemomechanical debridement, but they also demonstrated the importance of further optimization of light dosimetry for bacterial photodestruction in root canals. Along with methylene blue, tolonium chloride has been also used as a photosensitizing agent. It is applied to the infected area and left in situ for a short period. (19)The agent binds to the cellular membrane of bacteria, which will then rupture when activated by a laser source emitting radiation at an appropriate wavelength. The light is transmitted into the root canals at the tip of a small flexible optical fiber that is attached to a disposable handpiece. The laser emits a maximum of only 100 mW and does not generate sufficient heat to harm adjacent tissues. Furthermore, tolonium chloride dye is biocompatible and does not stain dental tissue.
Different irrigants can be used in endodontics. Each one having its own significances and drawbacks. EDTA, sodium hypochlorite and chlorhexidine are some of the commonly used endodontic irritants. But newer technological development have introduced the usage of Ozone and photon activated disinfection as effective irritants. But more research is needed in this area especially with regard to the latest technologies and methods to facilitate better efficiency of these endodonticsirrigants.
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Received on 12.11.2018 Modified on 21.11.2018
Accepted on 25.12.2018 © RJPT All right reserved