Irrigants In Endodontics Pdf Free ##VERIFIED##
Hypochlorite preparations are sporicidal and virucidal and show far greater tissue dissolving effects on necrotic than on vital tissues. These features prompted the use of aqueous sodium hypochlorite in endodontics as the main irrigant as early as 1920.
irrigants in endodontics pdf free
These are highly biocompatible and are commonly used in personal care products. Although citric acid appears to be slightly more potent at similar concentration than EDTA, both agents show high efficiency in removing the smear layer . In addition to their cleaning ability, chelators may detach biofilms adhering to root canal walls. An alternating irrigating regimen of NaOCl and EDTA may be more efficient in reducing bacterial loads in root canal systems than NaOCl alone . Antiseptics such as quaternary ammonium compounds (EDTAC) or tetracycline antibiotics (MTAD) have been added to EDTA and citric acid irrigants, respectively, to increase their antimicrobial capacity. The clinical value of this, however, is questionable [32, 33]. Generally speaking, the use of antibiotics instead of biocides such as hypochlorite or chlorhexidine appears unwarranted, as the former were developed for systemic use rather than local wound debridement and have a far narrower spectrum than the latter. Both citric acid and EDTA immediately reduce the available chlorine in solution, rendering the sodium hypochlorite irrigant ineffective on bacteria and necrotic tissue. Hence, citric acid or EDTA should never be mixed with sodium hypochlorite .
Clinical applications of anolyte and catholyte were reported to be effective . ECA solutions demonstrated more pronounced clinical effect and were associated with fewer incidences of allergic reactions compared to other antibacterial irrigants tested . Cleaning efficiency and safety for surfaces of dental instruments and equipment has been demonstrated in a number of studies.
To increase the efficacy of mechanical preparation and bacterial removal, instrumentation must be supplemented with efficient intracanal irrigants. Irrigation is defined as washing out a body cavity or wound with water or medical fluid. Thus the objective of irrigation is both mechanical and biologic. While the former is due to flushing effect, the latter is related to the antimicrobial properties of the irrigant . The ideal irrigant should be germicide and fungicide, non-toxic, nonirritating for host tissues, not interfering with tissue repair, stable in solution, have prolonged antimicrobial effect and is preferred to be relatively inexpensive [15, 16].
Agents for chemical treatment of the RCS can be divided into several phases, namely irrigants, rinses, and inter-appointment medicaments, the properties of which are being discussed in the present review, besides discussing the modern approaches in disinfection of the RCS .
Besides their wide spectrum and nonspecific killing efficacy on all microbes, hypochlorite preparations are both sporocidal and virucidal and also have much stronger dissolving effect on necrotic rather than vital tissues [19, 20]. These features prompted the use of aqueous NaOCl as the main irrigant in endodontics in early 1920s [21, 22]. Because of the complexity of irregular RCS, sufficient instrumentation may be impossible; therefore, NaOCl can improve root canal cleaning [23-25].
In the endodontic field, NaOCl shows a broad spectrum antimicrobial activity against difficult-to-eradicate microorganisms and biofilms of species such as Enterococcus, Actinomyces and Candida. Furthermore, NaOCl solutions are non-expensive, easily available, and have a long shelf life [26-28]. Other chlorine-releasing compounds have been advocated in endodontics, such as chloramine-T and sodium dichloroisocyanurate, which however never gained wide acceptance in endodontics, and appear to be less effective than hypochlorite at comparable concentrations .
One way to increase the efficacy of hypochlorite solutions could be lowering the pH, i.e. by buffering the solution with 1% bicarbonate . It has also been surmised that such solutions would be less toxic to vital tissues than their non-buffered counterparts . However, buffering hypochlorite with bicarbonate renders the solution unstable with a decrease in its shelf life to less than 1 week. Depending on the amount of the bicarbonate in the mixture and therefore the pH value, the antimicrobial efficacy of a fresh bicarbonate-buffered solution is only slightly higher if not similar, than that of a non-buffered solution . Another approach to improve the effectiveness of hypochlorite irrigants in the RCS could be to increase the temperature of low-concentration NaOCl solution. This improves its immediate tissue-dissolution capacity . Furthermore, heated hypochlorite solutions remove organic debris from dentin shavings more efficiently. Increasing the temperature of NaOCl by 5 degrees, doubles its activity .
CHX has been used in endodontics and proposed as both an irrigant and an intracanal medicament. It is active against a wide range of microorganisms, such as gram-positive and gram-negative bacteria including Enterococcus faecalis (E. faecalis), yeasts and fungi. When used as an intracanal medicament, CHX is more effective than CH against E. faecalis infection in dentinal tubules [56-58]. In fact, the antimicrobial activity of CHX is reduced when combined with other substances, including CH and CH plus zinc oxide, among others [56, 59-61]. For endodontic purposes, CHX can be used in a liquid or in a gel presentation. Ferraz et al. showed that 2% CHX gel has several advantages over 2% CHX solution, in spite of having similar antimicrobial, substantivity and biocompatibility properties [62, 63].
Iodide potassium iodine (IKI) is a traditional root canal disinfectant with wide-spectrum antimicrobial activity. It is used in different concentrations ranging from 2% to 5%. Iodine, as the oxidizing agent of this substance, reacts with free sulfhydryl groups of bacterial enzymes cleaving the disulfide bonds . It was manifested that CH-resistant microorganisms could be eradicated with a combination of IKI and CHX [65, 66]. It shows relatively low toxicity in experiments using tissue cultures. An obvious disadvantage of iodine is a possible allergic reaction in some patients, which can be the cause for inter-appointment pain .
A Mixture of Tetracycline, Acid and Detergent, labeled as Biopure MTAD (Dentsply, Tulsa Dental, Tulsa, OK, USA), was introduced as an antibacterial root canal cleanser [44, 68]. This biocompatible intracanal irrigant is commercially available as a two-component mix . One of the characteristics of this solution is the high binding affinity of the doxycycline component to dentin . In this irrigant, doxycycline hyclate is used instead of its free base, doxycycline monohydrate, to increase the water solubility of this broad-spectrum antibiotic . MTAD has been reported to be able to remove the smear layer due to the action of citric acid [71, 72], effectively eliminate microorganisms that are resistant to conventional endodontic irrigants/medications  and provide sustained antimicrobial activity [73-75]. MTAD was compared with commonly used irrigants and medications. The results showed MTAD to be less cytotoxic than eugenol, 3% H2O2, CH paste, 5.25% NaOCl, 0.12% CHX gluconate, and 17% EDTA. MTAD is more cytotoxic than NaOCl at 2.63%, 1.31%, and 0.66% concentrations.
Tetraclean (Ogna Laboratori, Farmaceutici, Milano, Italy) is another combination product similar to MTAD. The two irrigants differ in the concentration of antibiotics (doxycycline 150 mg/5ml for MTAD and 50 mg/5ml for Tetraclean) and the type of detergent (Tween 80 for MTAD). Mohammadi et al. showed that the substantivity of Tetraclean was significantly higher than that of MTAD .
Calcium hydroxide [Ca(OH)2] (CH) is a white odorless powder that was originally introduced to the field of endodontics by Herman as a direct pulp-capping agent . It is generally believed that the number of residual bacteria are responsible for endodontic failures . It can be controlled by placing an inter-appointment medicament within the prepared canal [78-80], and CH, is the most commonly used inter-appointment dressing which at least requires a period of 7 days for efficient disinfection . Antimicrobial activity of CH is related to the release of hydroxyl ions (OH-) in an aqueous environment which is probably due to the damage to the bacterial cytoplasmic membrane; protein denaturation; and damage to their DNA . However, some microorganisms such as E. faecalis  and C. albicans  are resistant to CH. Therefore, alternative intracanal medications have been sought to improve the eradication of bacteria before obturation. CHX gluconate is shown to be effective against some CH-resistant strains . Recent studies have suggested that considering this synergistic activity, CHX could be used in combination with CH to improve the antimicrobial efficacy . The high pH of CH (i.e. 12.5) alters the biologic properties of bacterial lipopolysacharide (LPS) present in the cell walls of gram-negative species and also inactivates the membrane transport mechanisms which has a role in killing the microorganism . However, as stated above, E. faecalis has been reported to be resistant to this effect as a result of its ability to penetrate the dentinal tubules and adapt to changes in the environment .
Recently, novel approaches in disinfection of RCS have been proposed that include the use of high-power lasers  as well as photodynamic therapy (PDT) . High-power lasers function by dose-dependent heat generation, and apart from bacterial killing properties, if incorrect parameters are used they have the potential to cause collateral damage such as char dentine, ankylosis of the roots, cementum melting, root resorption and periradicular necrosis [87, 88]. Since the introduction of laser to endodontics in 1971, several lasers were used for eliminating the bacteria from RCS. The erbium, chromium: yttrium-scandium-gallium-garnet laser (Er, Cr: YSGG), has the highest absorption in water and high affinity to hydroxyapatite, which make it suitable for root canal therapy [89, 90]. Lasers have the ability to clean and effectively disinfect the RCS, from the highly resistant species such as E. faecalis . The effect of neodymium: yttrium-aluminum-garnet laser (Nd: YAG) on E. faecalis biofilm is less than that of 1% NaOCl solution. A combination of laser and NaOCl results in complete elimination of E. faecalis biofilms . 350c69d7ab