Endodontic Irrigation Solutions: a Review
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Review Article Endodontic Irrigation Solutions: A Review Celaletin Topbas1, Ozkan Adiguzel2 1 Istanbul Aydin University, Faculty of Dentistry, Department of Endodontics, Istanbul, Turkey 2 Dicle University, Faculty of Dentistry, Department of Endodontics, Diyarbakir, Turkey Abstract The goal of endodontic treatment is to remove all the vital and necrotic tissues, microorganisms and microbial byproducts from root canal system. This goal can be achieved through chemical and mechanical debridement of root canals. This article narrates the Correspondence: specifics and requirements of the irrigation solutions. Sodium Dr. Celalettin TOPBAS hypochlorite is proposed as the primary irrigant by virtue of its Istanbul University, Faculty of organic tissue dissolution capacity and broad antimicrobial properties. Dentistry, Department of On the other hand, chelation solutions are recommended as auxiliary Endodontics, Istanbul, TURKEY. E-mail:[email protected] solutions to remove the smear layer or to hinder its formation on dentin surface. Thus, it's hoped that sealers and root canal fillers can Received 14 August 2017 penetrate to dentin tubules and obturate the canals hermetically. Accepted 19 October 2017 There are new studies on traditional irrigants especially on some irrigants that can replace sodium hypoclorite. This article reviews the Access Online new irrigants which can be used in future endodontic practice, and their advantages and limitations. Moreover, actions and interactions of recently used irrigants are adverted. Keywords: Irrigation solutions, chelators, sodium hypochlorite, smear layer, disinfection DOI 10.5577/intdentres. 2017.vol7.no3.2 How to cite this article: Topbas C, Adiguzel O. Endodontic Irrigation Solutions: A Review. Int Dent Res 2017;7:54-61. Root canals are usually shaped under constant irrigation with hand instruments and rotary systems Introduction (1). In a study of micro-CT images obtained before and after root canal shaping, 35% or more of the The goal of endodontic treatment is to root canal surface (including the isthmus) was found remove all vital and necrotic tissues, to be untouched, regardless of the canal preparation microorganisms, and microbial byproducts from the technique. Therefore, the importance of irrigation root canal system. This goal can be accomplished by and the complete disinfection of root canals has chemical and mechanical cleaning of the root canal been emphasized (2). In addition, irrigation system. The anatomy of the root canal system is solutions should aid removal of the smear layer. As extremely complex and variable, and effective no single solution has all of the desired properties, a cleaning and disinfection are not always possible. combination of two or more solutions is required for safe and effective irrigation. 54 IDR — Volume 7, Number 3, 2017 Topbas and Adiguzel Endodontic Irrigation Solutions Properties of an ideal irrigant are: (3, 4). NaOCl has a broad antibacterial spectrum and is sporicidal and viricidal. Its tissue-dissolving • Bactericidal, germicidal, and fungicidal activity is greater for necrotic tissue than for vital effects tissue. These valuable properties have encouraged • Ability to serve as a lubricant during the use of liquid NaOCl as a basic irrigation solution instrumentation in endodontics since the early 1920s (5). • Ability to dissolve organic dentinal tissues Pécora et al have shown that when NaOCl is (pulp tissue, collagen, and biofilm) in a reaction with water, it reaches a dynamic • Ability to dissolve inorganic dentinal tissues equilibrium as shown below (7). • No irritation of periapical tissues + - + • Solution stability NaOCl + H2O ↔ NaOH + HOCl ↔ Na + OH + H - • Prolonged and sustainable antibacterial + OCl activity after use • Activity in an environment in which blood, NaOCl reacts with organic tissue, resulting in serum, and tissue protein products are saponification, amino acid neutralization, and present chloramine reactions. Owing to its solvent effect on • Ability to remove the smear layer completely necrotic tissues, NaOCl has become the most widely • Low surface tension used irrigation solution in endodontics (8). However, • Disinfection of dentin and dentinal tubules the appropriate concentration for NaOCl solutions • No interference with periapical tissue used in endodontics is a matter of much debate. healing Organic matter (inflammatory exudate, • No staining of tooth tissues tissue residue, and microbial mass) in root canals • No weakening of tooth tissues reduces the effect of NaOCl. High concentrations of • No triggering of a cell-mediated immune NaOCl have better tissue-dissolving effects. Low response concentrations used in high volumes have potency • No antigenic, toxic, or carcinogenic effect on equivalent to that of high concentrations (9). In the peripheral tissue cells of the tooth addition, higher concentrations of NaOCl are more • No negative effect on the physical properties toxic than lower concentrations (10). of the exposed dentin As the anatomy of the root canal system • No negative effect on the sealing abilities of enables limited application to the root alone, NaOCl sealers can be used safely and reliably in high • Ease of application and low cost concentrations during root canal treatment if it is not • Long shelf life. introduced into the periapical tissues. The achievement of NaOCl contact with all canal surfaces for an optimal duration is much more important than the NaOCl concentration (11). Sodium Hypochlorite (NaOCl) The necrotic tissue-dissolving property of NaOCl is unique (11). Its activity increases with the NaOCl is the most widely used irrigation concentration, temperature, and duration of solution. It is ideal compared with other irrigation application (12). When NaOCl is used as the first solutions because it is the only solution that irrigant, its dentinal organic tissue-dissolving effect possesses most required properties. The first is not very strong, as hydroxyapatite in the smear chemically produced liquid chlorine solution was layer covers the collagen surface. However, when a potassium hypochlorite, discovered in France by decalcifying agent is used prior to NaOCl, Berthollet (1748-1822). The chemist Labarraque hydroxyapatite dissolves readily and the underlying (1777-1850) proposed the use of NaOCl for the collagen fibrils become clear. When NaOCl is used in prevention of puerperium and other infectious this stage, it acts directly on collagen, leading to the diseases (5). rapid destruction of collagen in the superficial dentin Based on controlled laboratory studies (13). After chemomechanical preparation, erosion of conducted by Koch and Pasteur, the use of NaOCl as the dentin has been demonstrated when irrigation a disinfectant became extremely widespread in the with NaOCl is followed by the use of late 19th century. During World War I, the chemist ethylenediaminetetraacetic acid (EDTA) or citric acid Henry Drysdale Dakin and the surgeon Alexis Carrel (CA) (14). used buffered 0.5% NaOCl to wash and disinfect The tissue-dissolving capacity of NaOCl infected wounds, based on Dakin's study of the solutions can be increased by increasing the solution effectiveness of different solutions on infected temperature, by ultrasonic activation, and by necrotic tissues (5, 6). prolongation of the working time (5). One of the most frequently used methods of increasing activity International Dental Research © 2017 55 Endodontic Irrigation Solutions Topbas and Adiguzel is to increase the temperature of a low- Grawehr et al. found that a solution of EDTA concentration NaOCl solution. The tissue-dissolving mixed with NaOCl retained calcium-binding capacity, capacity of a 1% NaOCl solution at 45°C was found but showed a sudden and rapid decrease in the to be equivalent to that of a 5.25% solution at 20°C. amount of chlorine in NaOCl, significantly reducing In addition, the systemic toxicity of heated low- the ability of NaOCl to degrade tissue (21). Many density NaOCl solutions is less than that of mishaps, such as the splashing of NaOCl into the unheated, higher-concentration ones (15). patient's or dentist's eye, damaging of the patient's The antibacterial and tissue-dissolving clothes, extrusion of NaOCl beyond the apical effects of a 5.25% NaOCl solution are diminished foramen, inadvertent injection of irrigants instead of when the solution is diluted (15). When NaOCl is anesthesia, or allergic reaction to the irrigation mixed with water, the following reaction occurs: solution, can occur during root canal treatment (22). NaOCl + H2O → NaOH + HOCl (hypochlorous acid) However, NaOCl solutions are inexpensive and easy [1.] to use, and they have a long shelf life (23). The hypochlorous acid in aqueous solution dissolves to hypochlorite anion (OCl-): HOCl ↔ H + OCl- [2.] Ethylenediaminetetraacetic Acid (EDTA) Hypochlorous acid (HOCl) is a stronger oxidant than the hypochlorite ion (OCl−). The Complete cleaning of the root canal system dissociation of HOCl depends on pH [2.reaction]. A requires the combined use of organic and inorganic balance exists between HOCl and OCl−. HOCl has a tissue-dissolving irrigation solutions. As NaOCl germicidal effect. At a pH of 10, essentially all effectively dissolves only organic tissue, other chlorine is OCl−; at a pH of 4.5, all chlorine is HOCl. solutions should be used to remove the smear layer The disinfecting properties of hypochlorite solutions and debris from the root canal system. The use of decrease with increasing pH, whereas their