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Antimicrobial efficacy of 4.2% sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in infected human root canals

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Abstract

The purpose of this study was to determine the antimicrobial efficacy of sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in human root canals infected by Enterococcus faecalis. One hundred sixty-five human single-rooted teeth were prepared and inoculated with E. faecalis for 48 h. Teeth were divided into 3 experimental groups according to the irrigation pattern used: group 1, 4.2% NaOCl pH 12; group 2, 4.2% NaOCl pH 7.5; and group 3, 4.2% NaOCl pH 6.5. Samples from the root canals were collected, and bacterial growth was analyzed by turbidity of the culture medium. None of the irrigating solutions used in this study demonstrated 100% effectiveness against E. faecalis. The antibacterial effectiveness of 4.2% NaOCl at pH 6.5 was significantly increased (P = .03) compared with 4.2% NaOCl at pH 12 (chi-squared test: P < .05). Bactericidal activity of NaOCl solution is enhanced by weak acidification of 4.2% NaOCl solution at pH 6.5.

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... 9,10 Several variables may interfere with the efficacy of NaOCl, such as concentration, 11 contact time, 9 temperature, 12 and pH. 13,14 The NaOCl in aqueous solution gives rise to hypochlorous acid (HOCl), which in turn dissociates into H ϩ and hypochlorite anion (OCL). 15 The antimicrobial activity of NaOCl is intensified by stabilization of the solution in low pH. ...
... 15 The antimicrobial activity of NaOCl is intensified by stabilization of the solution in low pH. 14,16,17 This can be explained by the greater concentration of HOCl 17 in relation to OCl, which prevails in high pH. HOCl has antimicrobial properties and oxidative capacity stronger than OCL. ...
... 15 The pH of NaOCl solutions may be lowered by its association with acids, such as EDTA, 18,19 citric acid, 17,20 or acetic acid. 14,17 Peracetic acid has demonstrated good antimicrobial properties arising from its decomposition into acetic acid and oxygen 21 and may therefore be an alternative for association with NaOCl. Although the combination of NaOCl with acidic solutions may increase its antimicrobial effect 13 and its oxidative capacity, 15 it is unknown whether the combination of NaOCl with acids increases its ability to penetrate into dentin. ...
Article
The objective of this study was to evaluate the penetration of 2.5% NaOCl associated with 17.0% EDTA, 1.0% citric acid, and 1.0% peracetic acid into dentin tubules. The roots of 44 bovine incisors were cross-sectioned and 5-mm-long fragments were produced from their middle thirds. The specimens were instrumented with ProTaper hand files, stained in crystal violet, then sectioned mesiodistally. The buccal fragments were divided into 4 groups (n = 9) and subjected to 2 consecutive 10-minute immersion periods in one of the following acid solutions combined with 2.5% NaOCl: 17.0% EDTA (group 1), 1.0% citric acid (group 2), and 1.0% peracetic acid (group 3). Nine fragments were immersed in 2.5% NaOCl (group 4). The analysis of the penetration of NaOCl solutions into dentin was performed by measuring the depth of crystal violet stain that was bleached using a steromicroscope under ×50 magnification. Statistical comparisons were carried out by Kruskal-Wallis and Dunn's tests at the 5% significance level. Group 1 showed less penetration into dentin than group 4 (P < .05). No statistically significant differences were observed among groups 2, 3, and 4 (P > .05). Association of NaOCl with acid solutions did not increase its penetration depth into root dentin.
... The bactericidal action of hypochlorite's can also potentially be enhanced by lowering their pH, by its association with acids (16) and by stabilizing them in low pH (17)(18)(19) (weak acidification of hypochlorite) (17). Acetic acid resulted a preferable choice because of its own antibacterial activity and safety (18). ...
... The bactericidal action of hypochlorite's can also potentially be enhanced by lowering their pH, by its association with acids (16) and by stabilizing them in low pH (17)(18)(19) (weak acidification of hypochlorite) (17). Acetic acid resulted a preferable choice because of its own antibacterial activity and safety (18). ...
... High concentration hypochlorites have shown significantly stronger antibacterial efficacy against E. faecalis than low concentration hypochlorites into the dentinal tubules (15). In addition, decreased antibacterial properties have been reported for 5.25% NaOCl when it is diluted (17). It is well known that increasing the chloride concentration of NaOCl solutions increases their cytotoxicity (11). ...
Article
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aim of this ex vivo study was to compare the antibacterial power of 1% NaOCl with 1% acetic acid, 5.25% NaOCl and two commercially available NaOCl modified with surfactants in bovine root dentin. A total of 120 dentin tubes prepared from intact bovine incisors were infected for 21 days with Enterococcus faecalis and randomly divided into six groups as follows: 5.25%NaOCl; Hypoclean; Chlor-Xtra; 1% NaOCl with 1% acetic acid; infected dentin tubes (positive control); and sterile dentin tubes (negative control). At experimental times of 0, 7, 14, 21 and 28 days, dentin chips were collected using sequential round burs with increasing diameters in separate test tubes containing 3 mL of freshly prepared BHI. Statistical analysis were performed using parametric methods (one-way ANOVA, and Bonferroni's multiple comparisons test, α=0.01). After culturing, the number of colony-forming units (CFU) was counted. All the NaOCl solutions showed small number of CFU over 28 days. ChlorXtra and Hypoclean had the smallest number of CFU at all times with greater antimicrobial efficacy than 5.25% NaOCl and 1% NaOCl solution with 1% acetic acid. Antibacterial Power of Sodium H y p o c h l o r i t e C o m b i n e d w i t h S u r f a c t a n t s a n d Ac e t i c Ac i d
... Sodium hypochlorite (NaOCl) is the most widely used irrigation solution in endodontics [6], and its antibacterial and tissue dissolution effectiveness depends on its pH, among other factors [7][8][9]. At pH 12, the regular type of NaOCl solution, the hypochlorite ion (OCl−) predominates in solution. ...
... At pH 12, the regular type of NaOCl solution, the hypochlorite ion (OCl−) predominates in solution. At this pH, tissue dissolution of NaOCl is maximized and it has the capability to disrupt and reduce the matrix of biofilm-related matter [8][9][10][11][12]. ...
... On the other hand, when NaOCl is acidified to pH 6.5, hypochlorous acid (HOCl) is mostly present [12][13][14], and the bactericidal ability of NaOCl is maximized [9,10,12,14,15]. ...
Article
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This study aimed to determine the bactericidal efficacy of sequential use of NaOCl pH 12 followed by acidified NaOCl pH 6.5, and compare it to that of either of these NaOCl solutions alone. E. faecalis biofilm was grown on standardized dentine specimens for four weeks. The specimens were randomly divided into four groups: (A) 4 min exposure to 0.9% saline solution (control); (B) 4 min exposure to 4% NaOCl pH 12; (C) 4 min exposure to 4% NaOCl pH 6.5; and (D) 2 min exposure to 4% NaOCl pH 12 followed by 2 min exposure to 4% NaOCl pH 6.5. The bactericidal activity was evaluated after the 4 min of contact time using confocal laser scanning microscopy. The volume ratio of red fluorescence to green and red fluorescence indicated the proportion of dead cells in the biofilm. The percent of dead cells in the saline solution group was significantly lower than those in the other groups. There was no significant difference between NaOCl pH 12 compared to NaOCl pH 6.5. The sequential use of NaOCl pH 12 followed by pH 6.5 significantly increased the percent of dead cells compared to both the samples exposed to either NaOCl pH 12 or pH 6.5. These results show that sequential irrigation protocol had a stronger bactericidal effect than the commonly used NaOCl pH 12.
... Although the dissolution effect of NaOCl is directly proportional to the exposure time, temperature, and concentration of the solution [5,8], few studies regarding the effect of the acidification of NaOCl to remove the organic matter have been published [9][10][11]. However, it appears that the antibacterial ability of NaOCl is enhanced when the pH of the solution is decreased [10,12,13], because at a lower pH, the available chlorine present as hypochlorous acid (HOCl) is more active than the hypochlorite anion that predominates at a higher pH [14]. The HOCl is able to penetrate the bacterial cell membrane because of its molecular structure, which is similar to water and the lack of electrical charge [15]. ...
... Zehnder et al. [32] demonstrated that the combination of NaOCl with C 2 H 4 O 2 results in the absence of available chlorine after the first minute of the preparation. It could be explained because of the evaporation of chlorine in gas form during the interaction of the substances [33,12]. Therefore, it is estimated that the chlorine level may decrease or become absent after the first minute of preparation, causing interferences in the result of the studies. ...
... In line with this statement, it is understood that the solutions should be placed directly into the root canal (clinically impracticable), rather than being prepared beforehand to avoid a potential loss of chlorine in the first minute. But only 1 min of interaction between the acidified solution and the bacterial flora of the root canal system is not enough to dissolve the organic matter or kill the bacteria [5,12]. Thus, in order to avoid pH changes of the solutions tested and consequently maintain the chlorine content, buffer substances were used aiming to keep the pH stabilized for long. ...
Article
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The aim of this study was to investigate whether variation in pH of sodium hypochlorite (NaOCl) increased its antibacterial and dissolution ability on polymicrobial biofilms formed in situ. Fifty-six dentin blocks (eight/group) were intraorally infected for 48 h and incubated in BHI for 48 h to standardize the biofilm growth. The specimens were irrigated with 1 and 2.5 % NaOCl with pH levels of 5, 7, and 12 for 20 min. The control group was irrigated with distilled water. The cell viability and the bacterial volume were measured at the pre- and post-irrigation procedures. Five random areas of each sample were chosen and analyzed with confocal laser scanning microscopy (CLSM). Statistical analysis was performed using the non-parametric Kruskal-Wallis and Dunn's tests (p < 0.05). All the experimental solutions were able to decrease the biomass (p < 0.05) except for the 1 % NaOCl-pH 5 group. The antibacterial ability of the NaOCl was dependent on the concentration and acidification of the solution. The acidification of NaOCl improves its antibacterial ability, but the dissolution effect of the irrigant is decreased. Bacteria and their products are the main factors in development of apical periodontitis. The pH reduction in the NaOCl could enhance the reduction or elimination of the root canal bacterial colonies in comparison with the unaltered solution.
... Only one of the included studies (Koba et al. 1999) takes this aspect into account. Obtaining a representative sample of microorganisms can be difficult (Mercade et al. 2009); thus, any reported positive effect of the laser treatment may be smaller than is actually possible because the most remote parts of the root canals, where the laser is said to have its effect, might not be sampled. Use of an inactivating agent to minimize the risk of disinfectants influencing the outcome is important (Mercade et al. 2009). ...
... Obtaining a representative sample of microorganisms can be difficult (Mercade et al. 2009); thus, any reported positive effect of the laser treatment may be smaller than is actually possible because the most remote parts of the root canals, where the laser is said to have its effect, might not be sampled. Use of an inactivating agent to minimize the risk of disinfectants influencing the outcome is important (Mercade et al. 2009). It is questionable whether the included studies accounted for this aspect. ...
Article
The aim was to evaluate the efficacy of various types of lasers used as an adjunct to chemo-mechanical disinfection of infected root canals with the outcome measures 'normal periapical condition' or 'reduction of microbial load'. PubMed, CENTRAL and ISI Web of Knowledge literature searches with specific indexing terms and a subsequent hand search were made with stated limits and criteria. Relevant publications were retrieved, followed by interpretation. The quality of each included publication was assessed as high, moderate or low. The initial search process yielded 234 publications. All abstracts of these publications were read, and the reference lists of relevant publications were hand-searched. Ten articles were read in full text and interpreted according to a data extraction form. Five were included in the systematic review and were assessed. A meta-analysis was impossible to perform because the included studies were heterogeneous with regard to study design, treatment and outcome measures. Positive effects were reported; however, no concluding evidence grade could be made because each included study was judged to have low quality, primarily due to lack of a power analysis, blinding and reproducibility. The evidence grade for whether lasers can be recommended as an adjunct to chemo-mechanical disinfection of infected root canals was insufficient. This does not necessarily imply that laser should not be used as an adjunct to root canal treatment but instead underscores the need for future high-quality studies.
... Therefore, it is very difficult to eradicate this strain from infected root canals. Since this bacterium is highly resistant to different antibacterial agents, the antimicrobial efficacy of endodontic irrigants against this bacterium has been assessed in various studies (5)(6)(7)14,16,25). Because of its high resistance and ease of handling in microbiological sampling, this bacterium was selected for assessment of the antibacterial activity of selected irrigants in the present study. ...
Article
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The aim of the present study was to compare the in vitro antibacterial activity of common root canal irrigants with a combination technique against intratubular Enterococcus faecalis. Seventy-five human single-rooted teeth were selected and their crowns and root-ends were removed to obtain specimens 5 mm in length. The specimens were contaminated with E. faecalis and divided into five experimental groups (n = 15). These groups were irrigated with 2% chlorhexidine (CHX), 3% hydrogen peroxide (H2O2), 5.25% sodium hypochlorite (NaOCl), CHX/H2O2 and sterile saline (control). Surface and deep dentinal chips were collected for each sample. After incubation, the numbers of colony-forming units (CFUs) were counted. The Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis (α = 0.05). In the surface dentin, CHX, NaOCl, and CHX/H2O2 had significantly higher antibacterial activity than H2O2 (P < 0.05). In the deep dentin, NaOCl and CHX/H2O2 had significantly higher antibacterial activity than CHX and H2O2 (P < 0.05). CHX/H2O2 had similar antibacterial effectiveness to NaOCl in both surface and deep dentinal tubules. This combination can be considered a potentially useful irrigant for root canal treatment. (J Oral Sci 55, 275-280, 2013).
... Above a pH of 7, a major portion of the hypohalous acid dissociates to hypohalite. Hypohalous acid, hypohalite, and singlet oxygen all have antimicrobial activity (11,12). ...
Article
Previous research showed an antimicrobial effect of vanadium chloroperoxidase (VCPO) on in vitro Enterococcus faecalis biofilms. The current study aimed to optimize the use of this enzyme at the root canal pH using a modified VCPO (mVCPO) that was adapted to function at a higher pH and to explore the biocompatibility of mVCPO. The activity of the original and modified VCPO was assessed using the monochlorodimedone assay. For antimicrobial assessment, 48-hour biofilms of E. faecalis OS-16 were incubated 5 or 30 minutes with mVCPO, bromide, and hydrogen peroxide, and colony-forming units were determined. A metabolic activity assay was used to evaluate the cytotoxic effect of mVCPO on oral fibroblasts. Reaction products generated by mVCPO at a root canal pH of 7.7 significantly inactivated the biofilm after 5 minutes and even more after 30 minutes (Mann-Whitney U test, P < .05). The mVCPO reaction products showed less cytotoxic effects than control solutions and 0.5% sodium hypochlorite (Kruskal-Wallis test, P < .05). The incubation of mVCPO in the presence of its substrates with in vitro E. faecalis biofilms showed a significant antimicrobial effect at the root canal pH. Also, cytotoxicity tests showed preliminary biocompatibility. Therefore, an interappointment dressing containing mVCPO could aid in improving current endodontic treatment through continuous and local generation of antimicrobials.
... 15,16 Apical diameter standardization was done by instrumentation of the canal using K files up to #20. This was in agreement with berber et al. 17 and Mercade et al. 18 The prepared canal and length of the tooth did provide a standard volume of the gel placed (6) Nawal M. Moqbel, et al. E.D.J. Vol. ...
Article
Aim: The purpose of the present study was to evaluate in-vitro the removal efficacy of induced smear layer by the prepared dressing gel materials; ECHXT (0.01% EDTA, 0.01% CHX and 6% Triss buffer), ENaOCl (used separate dressing gel 2.5% NaOCl / 18.6% EDTA gel) and ECHX (used separate dressing gel 18.6% EDTA and 17% CHX gel). Materials and Methods: The dressing gel materials were prepared followed by rheological determination. Fifty-five distal roots of extracted lower molars were standardized to 12± 1 mm length and up to #20 Kfile apex’s width. A cervical seat was created of 1x1 mm dimensions at the coronal third of the root. The root surfaces were coated with varnish and root apices were sealed with cyanoacrylate. Each root was placed separately inside Eppendorf tube. Initially prepared roots were divided into two control groups (smear layer formation confirmation and proper sterilization confirmation, N=5 for each) and experimental group which were subdivided into three equal groups (N=15) according to the used dressing gel for 1, 24 hour and 1-week period of time. After mechanical preparation, randomly selected samples were used to confirm the formation of smear layer by ESEM. Dressing of the canals were done using standard volume (0.1 ml) for each dressing gel and the roots were incubated for 1, 24 hour and 1-week. Debris and smear layer removal evaluation were done using the stereomicroscope and ESEM, respectively. Results: The statistically significant lowest mean smear layer percentage at the apical third showed after 1 hour in ECHX group while it was after 1 and 24 hour in ENaOCl group. Conclusion: Under the limitations of the present study, we conclude that: Variation in the physical nature of irrigate did improve its role and one week could not be recommended. The combined use of conventional irrigate with chelating agent as intracanal medicament may be promising in removal of smear layer and their effect could be improved by increase concentration and minimizing the time of application
... The methodology used to assess the antimicrobial activity of endodontic irrigants in this study was the artificial infection of extracted teeth with the selected microorganism and in situ irrigation with the test antimicrobial agents, which according with some authors is an effective method to evaluate anti-fungal as well as antibacterial properties of any solution [12][13] . After 48 h of incubation, all initial samples were recovered with pure cultures of viable microorganisms confirming the efficiency of the infection methodology adopted for the present research. ...
Article
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Aim: The purpose of the present study was to evaluate the antimicrobial activity of 0.2%, 1%, and 2% chlorhexidine in root canals instrumented with the ProTaper Universal™ system. Methods: Fifty human mandibular premolar teeth were infected with a mixture of Candida albicans, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus. The specimens were randomly divided into 5 groups with 10 root canals according to the irrigant used. All root canals were instrumented with the ProTaper Universal™ system. Assessment of the antimicrobial action of the irrigant was performed before, during, and after instrumentation. Data were analyzed statistically by Chi-squared test and the Fisher exact test at 5% significance level. Results: The 0.2% chlorhexidine solution was ineffective against all test microorganisms. The 1% chlorhexidine solution was effective in eliminating P. aeruginosa and C. albicans after the use of the F1 and F3 instruments, respectively. The 2% chlorhexidine solution was effective at killing S. aureus, P. aeruginosa and C. albicans after the use of the S1 instrument. There were statistically significant differences (p<0.05) between the concentrations of chlorhexidine and the instruments used. Conclusions: The 0.2% chlorhexidine solution in combination with rotary instrumentation was ineffective against all test microorganisms. The 1% chlorhexidine solution was ineffective against S. aureus and E. faecalis. The 2% chlorhexidine solution was not sufficient to inactivate E. faecalis.
... The use of paper point technique has the advantage that it can be performed in vitro and in vivo. 5,23 On the other hand, bacteriologic sampling with paper points is limited, because only the microorganisms that are present in the main root canal can be sampled, and the ones that are located inside the dentin tubules are inaccessible. The method of obtaining dentinal samples using burs of different diameters can evaluate the presence of bacterial cells inside the dentinal tubules; however, it was not included in this study. ...
Article
The purpose of this in vitro study was to evaluate the antimicrobial activity of 0.5%, 1% and 2.5% sodium hypochlorite in root canals instrumented with the ProTaper Universal system. Fifty human mandibular premolar teeth with single root canals were infected with a mixture of C. albicans, P. aeruginosa, E. faecalis, and S. aureus. The specimens were randomly divided into 5 groups with 10 root canals each according to the irrigant used: group 1: 0.5% NaOCl; group 2: 1% NaOCl; group 3: 2.5% NaOCl; group 4 (positive control): 0.85% sterile saline solution; group 5 (negative control, without microorganisms): 0.85% sterile saline solution. All root canals were instrumented with the ProTaper Universal system. The assessment of the antimicrobial action of the irrigant was performed before the biomechanical preparation (0), and after instrumentation with S1 (1), S2 (2), F1 (3), F2 (4), and F3 (5) files. All positive control samples showed microbial growth, whereas negative control samples showed no microbial growth before the biomechanical preparation and after the instrumentation with S1, S2, F1, F2, and F3 files. The microorganisms were eliminated after the instrumentation with S1 file in all tested irrigants, except for 1 sample in S1 at 0.5% NaOCl which showed positive growth. There was no significant statistical difference (P = 1.000) among the tested irrigants. Sodium hypochlorite, at all tested concentrations, was effective in eliminating C. albicans, P. aeruginosa, E. faecalis, and S. aureus in combination with the NiTi rotary instrumentation with the ProTaper Universal system.
... A significant increase in the disinfecting capacity of the pH 6.5 solution against the pH 12 solution group was shown; however, the intermediate value (pH 7.5) showed no difference with the other group. (Mercade et al. 2009 ...
Article
Rossi-Fedele G, Guastalli AR, Doğramacı EJ, Steier L, De Figueiredo JAP. Influence of pH changes on chlorine-containing endodontic irrigating solutions. International Endodontic Journal, 44, 792–799, 2011. Chlorine-containing solutions are used for broad disinfection purposes. Water disinfection literature suggests that their disinfectant action depends on pH values as this will influence the available free chlorine forms. Hypochlorous acid (HOCl) has been suggested to have an antimicrobial effect around 80–100 times stronger than the hypochlorite ion. The aim of this paper was to review the influence of pH changes on the efficacy of chlorine-containing endodontic irrigating solutions. An electronic and hand search (articles published through to 2010, including ‘in press’ articles; English language; search terms ‘root canal irrigants AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution’; ‘antimicrobial action AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution’; ‘tissue dissolution AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution’; ‘smear layer AND sodium hypochlorite or hypochlorous acid or superoxidized water or electrochemically activated solution’) was performed to identify publications that compared chlorine water solutions with different pH. Of 1304 publications identified, 20 were considered for inclusion in the review. The search resulted in the retrieval of articles studying sodium hypochlorite (NaOCl), superoxidized waters (SOW) and sodium dichloroisocyanurate (NaDCC). Regarding antimicrobial efficacy, the literature suggested that reducing the pH value of NaOCl to between 6 and 7.5 would lead to improved action; SOW was described as having a lower antimicrobial effect. The tissue dissolution activity NaOCl decreased when the pH reached values between 6 and 7.5; NaDCC and SOW had no clinically relevant tissue dissolution capability. Chlorine solutions of different characteristics appeared to have some cleaning efficacy although they should to be used in conjunction with chelating and/or detergent agents.
... Int. J. Adv. Res. 5 (9), 1388-1394 1389 enterococcal surface proteins (Esp), gelatinase, cytolysin toxin, extracellular superoxide production, capsular polysaccharides, antibiotic resistance determinant) can facilitate the adherence of host cells and extracellular matrix, tissue invasions, immunomodulation effect and cause toxin mediated damage. 12 Actual thinking has recommended the implementation of evidence-based dentistry, which organizes studies involving the systematic review or meta-analysis. ...
... The NaOCl solution presents a high and stable pH, slowly releasing chloride [24]. However, its efficacy may be affected by concentration, temperature, and pH [25,26]. When the pH is low, the free chloride of NaOCl joins the hypochlorous acid (HOCl), which is more active than hypochlorite anion (OCl) [24]. ...
Article
OBJECTIVE: This study aimed to assess the antimicrobial action of calcium hypochlorite [Ca(OCl)2] at concentrations of 2.5% and 6%, and of grape seed extract (GSE) at concentrations of 10%, 30%, and 50%, against Enterococcus faecalis, comparing it to the action of 6% sodium hypochlorite (NaOCl).METHODS: Saline solution was used as negative control. The inhibition halos of microbial growth were verified by the agar disk diffusion method. Twelve Petri plates were used for seeding with culture medium of approximately 5 mm in thickness. In each plate, 5 disks of pure and sterile antibiogram, soaked in the substances to be tested, were used and taken to the plate containing the seededbacterial strain. The plates remained in aerobic bacteriological incubator for 24 h at 37°C temperature. After 24 h, the inhibition halos were measured with a digital caliper. Analysis of Variance (ANOVA) was used for statistical analysis followed by Tukey's complementary test, at 5% significance.RESULTS: The 6% Ca(ClO)2 presented inhibition halo statistically higher than the other solutions (p<0.05), followed by 2.5% Ca(ClO)2, which was statistically similar to 6% NaOCl (p>0.05). The GSE concentrations resulted in lower inhibition halos of active substances and the different concentrations were similar to each other. Lastly, saline solution presented the same inhibition halos in all groups (p<0.05).CONCLUSION: It may be concluded that 6% Ca(OCl)2 presented higher antimicrobial activity than 6% NaOCl. On the other hand, all GSE concentrations were lower than NaOCl and Ca(OCl)2.
... or pure water, wounds cleansed with HClO solution showed significantly lower bacterial loads. HClO is relatively stable under weakly acidic conditions (pH 5-7) and serves as the predominant microbicidal component in chlorine-based disinfectants [31,32]. However, HClO reacts readily with various NH 2 -or CHO-containing organic (e.g., protein, amino acid, and carbohydrate) and inorganic compounds, resulting in rapid consumption of HClO by oxidation reactions, significantly decreasing HClO's microbicidal activity [21,31]. ...
Article
Weakly acidic hypochlorous acid (HClO; 200 ppm, pH 6.5) is effective against a broad range of microorganisms. We have previously reported a study of developing antimicrobial biomaterials made up of chitin-nanofiber sheet (CNFS) -immobilized silver nanoparticles (CNFS/Ag NPs) and showed that either cleansing with HClO or covering with CNFS/Ag NPs daily for more than 7 days resulted in delayed wound healing. This study aimed to evaluate disinfection and wound healing by a combination of cleansing with HClO and covering with CNFS/Ag NPs daily for 3 days. Applying HClO + CNFS/Ag NPs daily for 3 days and then cleansing with just pure water and covering with CNFS alone daily for 9 days were performed for Pseudomonas aeruginosa-infected wounds in db/db diabetic mice. We found a significant enhancement of wound healing and a reduction of bacteria counts compared to the controls. Histological examination showed significantly advanced granulation tissue and capillary formations in the wounds on Day 12. These results suggest that limited disinfection to 3 days with HClO + CNFS/Ag NPs may be sufficient to avoid negative effects on wound repair.
... On the other hand, the decrease to pH 6.5 and 7.5 of a 4.2% NaOCl solution statistically increased its antibacterial effectiveness against Enterococcus faecalis in artificially infected teeth. 13 However, besides the abovementioned positive aspect, adjusting the pH of an NaOCl solution to its pKa is likely to have 2 negative consequences. The manufacturers add sodium hydroxide to the commercial NaOCl solutions to ensure a long shelf life. ...
Article
The aim was to evaluate the shelf life and the dissolving and antibacterial properties of a neutralized 2.5% NaOCl solution. The loss of available chlorine and the pH of the neutralized 2.5% NaOCl solution were recorded to determine its shelf life. The dissolving action on bovine dental pulp was assessed measuring weight loss, pH variation, and decrease in available chlorine content. The antibacterial activity was evaluated on artificially infected human teeth. The roots were endodontically prepared, sterilized, and inoculated with Enterococcus faecalis before irrigation with the neutralized solution. The presence of intracanal bacteria after irrigation was recorded. The neutralized solution presented a shelf life of 2 hours, dissolving capacities equivalent to control for the first 5 minutes, and a better antibacterial efficiency. The neutralized 2.5% NaOCl solution must be used within 2 hours after mixing, should be frequently renewed to maintain its dissolving capacities, and presented enhanced antibacterial properties.
... Many studies have shown that the antibacterial activity of NaOCl depends on its concentration, contact time, pH and temperature (Vianna et al. 2004, De-Queiroz & Day 2008, Mercade et al. 2009; however, few studies have reported on the precise relationship between the antibacterial activity of NaOCl and the factors influencing the antibacterial activity of NaOCl in E. faecalis biofilms. Furthermore, although the physiological differences between early and mature E. faecalis biofilms can show different patterns of antimicrobial resistance (Shen et al. 2011), little has been reported on the precise relationship in early or mature E. faecalis biofilms. ...
Article
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AimTo determine the relationships between the antibacterial activity of NaOCl and treatment time and biofilm age in early Enterococcus faecalis biofilms using a linear-fitting procedure.MethodologyE. faecalis biofilms were formed on hydroxyapatite discs. To investigate the relationship between the antibacterial activity of NaOCl and biofilm age, 22-, 46-, 70-, and 94-h-old biofilms were exposed to NaOCl (0 – 3%) for 5 min. To investigate the relationship between the antibacterial activity of NaOCl and treatment time, 70-h-old biofilms were exposed to NaOCl (0 – 3%) for 1, 3, 5, and 7 min. After treatment, colony forming units (CFUs) were counted. To determine the relationships between these variables, linear-fitting was performed.ResultsThe change in the minimum biofilm eradication concentration (MBEC) of NaOCl followed a linear pattern of biofilm age (R = 0.941, R2 = 0.886) or treatment time dependence (R = −0.948, R2 = 0.898). Below the MBEC, the fitting lines for bacterial CFU count versus NaOCl concentration (R ≤ −0.973, R2 ≥ 0.948) in the 22-, 46-, 70-, and 94-h-old biofilms implied that the antibacterial activity of NaOCl decreased as the biofilm age increased. The fitting lines for bacterial CFU count versus NaOCl concentration (R ≤ −0.970, R2 ≥ 0.942) in the 1, 3, 5, and 7 min treatments implied that the antibacterial activity of NaOCl increased with treatment time.Conclusions These results suggest that the antibacterial activity of NaOCl against early E. faecalis biofilms in root canals may follow a linear pattern depending on biofilm age or treatment time.This article is protected by copyright. All rights reserved.
Article
Root canal irrigants play a significant role in the elimination of microorganisms, tissue dissolution, and the removal of debris and smear layer. No single solution is able to fulfill these actions completely; therefore, their association is required. The aim of this investigation was to review the antagonistic interactions occurring when sodium hypochlorite (NaOCl), chlorhexidine (CHX), EDTA, and citric acid (CA) are used together during endodontic treatment. A search was performed in the electronic database Medline (articles published through 2011; English language; and the following search terms or combinations: "interaction AND root canal irrigant or endodontic irrigant or sodium hypochlorite or chlorhexidine," "sodium hypochlorite AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent or chlorhexidine," and "chlorhexidine AND EDTA or ethylenediaminetetraacetic acid or citric acid or chelating agent") to identify publications that studied unwanted chemical interactions between NaOCl, CHX, and EDTA and CA. The search identified 1,285 publications; 19 fulfilled the inclusion/exclusion criteria of the review. Their research methodology was classified as either in vitro or ex vivo. Antagonistic interactions included the loss of free available chlorine for NaOCl when in contact with chelators, which consequently reduced the tissue dissolution capability and to a lesser extent antimicrobial activities. When CHX and NaOCl are mixed, a precipitate forms that can present detrimental consequences for endodontic treatment, including a risk of discoloration and potential leaching of unidentified chemicals into the periradicular tissues. CHX and EDTA mixtures cause a precipitate, whereas CHX and CA do not exhibit interaction.
Article
The objective of this study was to evaluate the antibacterial efficacy of irrigating solutions and their combinations against Enterococcus faecalis. One hundred ten single-rooted human teeth were inoculated with E. faecalis and incubated for 21 days. Teeth were divided according to the irrigant: Group I (GI), 2.5% sodium hypochlorite solution (NaOCl); GII, 2.5% NaOCl + 10% citric acid; GIII, 2.5% NaOCl + apple cider vinegar; GIV, apple cider vinegar; GV, 2% chlorhexidine solution; GVI, 1% peracetic acid; GVII, saline solution. Microbiological samples were taken after root canal preparation and 7 days later. Data were submitted to ANOVA (5%). All solutions promoted reduction of E. faecalis after instrumentation, but bacterial counts were higher in the final sample. GI, GV, and GVI had lower bacterial counts than the other groups. The irrigating solutions may present activity but do not eradicate E. faecalis in the root canal system.
Article
The objectives of this study were to evaluate pH, available chlorine content, and antibacterial activity of endodontic irrigants and their combinations. The pH and chlorine content of sodium hypochlorite (NaOCl) were analyzed pure and in combination with 10% citric acid (CA) and apple vinegar (AV). The antibacterial effect of the following solutions was measured by direct contact test against Enterococcus faecalis: 2.5% NaOCl, 2.5% NaOCl +10% CA (7:3), 2.5% NaOCl + AV (5:5), 10% CA, and AV. Sterile saline was used as control. The colony-forming units were determined by serial decimal dilutions. The combination of 2.5% NaOCl with CA or AV lowered the pH and the chlorine content. NaOCl, alone or in combination was able to eliminate E. faecalis in 30 seconds, and CA, after 10 minutes. AV promoted reduction (32.2%) after 10 minutes. NaOCl with acidic solutions lowered the pH and the chlorine content, but did not alter its antibacterial effect.
Article
Root canal irrigation is an essential step for ensuring successful root canal therapy (RCT). Among available irrigants, sodium hypochlorite (NaClO) (0.5%-5.25%) is the most used irrigant solution because of its comprehensive ability to kill bacteria and dissolve organic tissues. Hence, high concentration of NaClO may have negative effects that would lead to devastating complications, and low concentration of NaOCl is safe but shows decreased efficacy. Therefore, a safe and efficient novel catalysis-enhanced root canal irrigant system consisting of 0.5% neutral-NaClO (pH=7.5), TiO2-x nanoparticles (5 mg mL⁻¹), and visible light irradiation (LED, 10 W, 405-800 nm) was proposed. The effect of the photocatalytic chlorine activation rapidly increased the generation of reactive oxygen species (ROS, •OH) and reactive chlorine species (RCS, •Cl and •ClO) in the system. Consequently, the system exhibited greatly enhanced degradation ability toward methylene blue and typical biological macromolecules, implying its good antibacterial and tissue dissolution activities. Additionally, the antibacterial rates against Enterococcus faecalis in both planktonic and biofilm forms were >99% after treatment with the proposed system for 5 min, which was comparable to that of the 3% alkaline NaClO. Meanwhile, the system showed desirable pulp tissue-dissolving efficacy, successfully solving the dilemma caused by neutralization. L929 cell experiments as well as rats subcutaneous injection experiments demonstrated the biocompatibility and safety of the system. This work describes a safe and effective endodontic irrigant and proposes a promising strategy for developing NaClO-based disinfectants for wider application.
Article
Alicyclobacillus acidoterrestris can be difficult to control in fruit juices as their spores survive juice pasteurization temperatures and may subsequently germinate and grow. Contaminated fruits can be regarded as a major source of spoilage caused by A. acidoterrestris in fruit juices. The objective of this study was to evaluate the efficacy of neutral electrolyzed water (NEW) in reducing the number of A. acidoterrestris spores in aqueous suspension and on surface-inoculated apples. Its effectiveness was compared with that of sodium hypochlorite (SH) solutions at free chlorine concentrations of 50 and 200mg/L. Viable spore counts in test suspensions were significantly (P<0.05) reduced after exposure to NEW (200mg/L free chlorine) for 1min. However, NEW (50mg/L free chlorine) and SH solutions were unable to significantly (P>0.05) reduce the number of viable spore during the same exposure period. More than 5 log reduction in spore counts was achieved by NEW solution containing 200mg/L free chlorine after 5min of exposure. Exposure to NEW solutions for 3min yielded more than 4 log reductions in the number of viable spores on apple surfaces. At the same concentrations of free chlorine, NEW was three to more than ten-fold effective than SH in reducing viability of A. acidoterrestris spores in aqueous suspension and on apple surfaces. This finding suggests that NEW can be considered as an effective disinfectant for the control of A. acidoterrestris on fruits.
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BACKGROUND Tuberculosis (TB) is endemic in Nigeria due mainly to the high burden of HIV/AIDS and especially in Benue state which has the highest prevalence of HIV in Nigeria.Sputum smear examination is of importance in the diagnosis of pulmonary TB and can be smear-positive or negative. In this study, we analyzed the sputum smear results of all patients diagnosed to have PTB during the time under review. METHODS The study was a retrospective study done with records of patients diagnosed with PTB between July 2009 and July 2011.The sample size was 305. AIM To determine the smear patterns in pulmonary tuberculosis and its relationship with HIV status. RESULTS There was slight male preponderance among the study group. 37% were found to be smear positive,out of which 63.7% and 36.3% were males and females respectively.The highest frequency was between 21 – 40 years and in this age group there were more males than females.72.1% were TB/HIV co-infected and 29.1% of the TB/HIV co-infected patients had smear-positive Tuberculosis. CONCLUSION There is a high burden of TB/HIV co-infection affecting predominantly the youths.Sputum smear results in TB/HIV co-infection are largely negative.There is the need for provision of other diagnostic tests to improve the diagnosis of TB in our environment and targeted intervention among the youth to reduce the burden of TB/HIV
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BACKGROUND Tuberculosis (TB) is endemic in Nigeria due mainly to the high burden of HIV/AIDS and especially in Benue state which has the highest prevalence of HIV in Nigeria.Sputum smear examination is of importance in the diagnosis of pulmonary TB and can be smear-positive or negative. In this study, we analyzed the sputum smear results of all patients diagnosed to have PTB during the time under review. METHODS The study was a retrospective study done with records of patients diagnosed with PTB between July 2009 and July 2011.The sample size was 305. AIM To determine the smear patterns in pulmonary tuberculosis and its relationship with HIV status. RESULTS There was slight male preponderance among the study group. 37% were found to be smear positive,out of which 63.7% and 36.3% were males and females respectively. The highest frequency was between 21 – 40 years and in this age group there were more males than females.72.1% were TB/HIV co-infected and 29.1% of the TB/HIV co-infected patients had smear-positive Tuberculosis. CONCLUSION There is a high burden of TB/HIV co-infection affecting predominantly the youths.Sputum smear results in TB/HIV co-infection are largely negative.There is the need for provision of other diagnostic tests to improve the diagnosis of TB in our environment and targeted intervention among the youth to reduce the burden of TB/HIV
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RESULTS: It seems that, although some both sodium hypochlorite and chlorhexidine were very effective against E. faecalis. The other discussed irrigant and Tetraclean, MTAD, were effective against E. faecalis in both agar diffusion test and tooth model experiments.
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OBJECTIVE: This study examined medical specialty selection by Nigerian resident doctors using a marketing research approach to determine the selection criteria and the role of perceptions, expected remuneration, and job placement prospects of various specialties in the selection process.
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The inactivation of Tubifex tubifex is important to prevent contamination of drinking water. Chlorine is a widely-used disinfectant and the key factor in the inactivation of T. tubifex. This study investigated the inactivation kinetics of chlorine on T. tubifex and the synergistic effect of the sequential use of chlorine and UV irradiation. The experimental results indicated that the Ct (concentration × timereaction) concept could be used to evaluate the inactivation kinetics of T. tubifex with chlorine, thus allowing for the use of a simpler Ct approach for the assessment of T. tubifex chlorine inactivation requirements. The inactivation kinetics of T. tubifex by chlorine was found to be well-fitted to a delayed pseudo first-order Chick-Watson expression. Sequential experiments revealed that UV irradiation and chlorine worked synergistically to effectively inactivate T. tubifex as a result of the decreased activation energy, Ea, induced by primary UV irradiation. Furthermore, the inactivation effectiveness of T. tubifex by chlorine was found to be affected by several drinking water quality parameters including pH, turbidity, and chemical oxygen demand with potassium permanganate (CODMn) concentration. High pH exhibited pronounced inactivation effectiveness and the decrease in turbidity and CODMn concentrations contributed to the inactivation of T. tubifex.
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Introduction: This article reports for the first time the effects of multiple additives (polyethylene glycol 400, Triton X-100, benzalkonium chloride, and ethyl formate) on the surface tension, pH, and viscosity of 5.25% sodium hypochlorite (NaOCl) irrigant solution. Advanced statistical approaches based on unsupervised multivariate analysis (cluster analysis and principal component analysis) were used to quantify the variability of the physicochemical properties of the modified NaOCl solution for the first time in dentistry. Methods: Solutions of 5.25% NaOCl were modified with multiple additives in various concentrations, physicochemical parameters were measured at 22°C and 37°C, and the results were statistically analyzed to group the solutions and reveal the effects of additives. Results: Cluster analysis and principal component analysis revealed that pH and surface tension were the significant parameters (P < .05) for grouping the modified solutions. Four principal components, accounting for 90.6% of the total variance, were associated with flow characteristics (37.3%) determined by polyethylene glycol; the wetting property (22.5% and 10.5%), which was dependent on cationic and nonionic surfactant; and the antimicrobial effect (20.3%) influenced by ethyl formate. Varimax rotation of the principal components showed that the cationic surfactant (benzalkonium chloride) had significantly decreased surface tension compared with the nonionic surfactant (Triton-X). Although ethyl formate was introduced as an odor modifier, it had a significant effect on pH decrease and the occurrence of effervescence with O2 and hypochlorous acid release. Conclusions: The statistical results revealed that the 5.25% NaOCl irrigant solution should be modified with a mixture of 0.1% benzalkonium chloride, 1% ethyl formate, and 7% polyethylene glycol for obtaining a low pH and low surface tension.
Chapter
Sodium hypochlorite is mostly bactericidal at 5,000 mg/l (30 min) and yeasticidal at 1,000 mg/l (5 min). An almost comprehensive fungicidal activity was seen with 30,000 mg/l (10 min). High MIC values indicating tolerance to sodium hypochlorite have been reported for Methylobacterium spp. and R. erythropolis. Epidemiological cut-off values to determine acquired resistance have been proposed for eight species (4,100 or 8,200 mg/l active chlorine). Resistance to sodium hypochlorite is explained by genes which also involved in resistance to hydrogen peroxide. No cross-tolerance to antibiotics has been reported in S. aureus but in selected strains of Salmonella spp. In most bacterial species, there is no or only a small MIC increase after low-level exposure. Low-level exposure can induce the VBNC state in E. coli with enhanced antibiotic tolerance. Cross-tolerance can be found to benzalkonium chloride, another quaternary ammonium compound and alkylamine (L. monocytogenes) or sodium nitrite and hydrogen peroxide (E. coli). Sodium hypochlorite can increase biofilm formation in E. coli, MRSA and S. Typhimurium, whereas it is inhibited in E. faecalis and Candida spp. Biofilm removal is variable in single-species biofilms and very poor in mixed natural biofilms. The potential to cause biofilm fixation is unknown.
Chapter
The antimicrobial activities of microbicides can be profoundly affected by factors such as concentration of the active(s), contact time, temperature, pH, degree and type of soiling, nature and topography of the target surface/object, excipients in the formulation, type and level of microbial contamination and the presence of microbial biofilms. Thus, understanding the influence of these factors, singly or in various combinations, is vital not only to design effective and safer microbicides but also to apply them optimally in the field. Such knowledge is more essential now than ever due to increasing numbers of microbicidal products and their widening applications. Inappropriate and/or sub-optimal use of such products may contribute to human and environmental toxicity and also induce resistance to antibiotics and other microbicides. This chapter is a general review on how the above-mentioned factors may influence the microbicidal activity of chemicals during the initial development of a given formulation, its actual field use and in assessing the outcome of its application.
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An in vitro model for dentinal tubule infection of root canals was developed. Cylindrical dentin specimens, 4 mm high with a diameter of 6 mm and a canal 2.3 mm wide, were prepared from freshly extracted bovine incisors. The cementum was removed from all dentin blocks. The tubules were opened by four-minute treatments with 17% EDTA and 5.25% NaOCl before being infected with Enterococcus faecalis ATCC 29212 in yeast extract-glucose broth. Bacteria rapidly invaded the tubules. After three weeks of incubation, a heavy infection was found 400 micron from the canal lumen, and the front of the infection reached 1000 micron in some blocks. Camphorated paramonochlorophenol (CMCP) and a calcium hydroxide compound, Calasept, were tested for their disinfecting efficacy toward E. faecalis-infected dentin. Liquid CMCP rapidly and completely disinfected the dentinal tubules, whereas CMCP in gaseous form disinfected tubules less rapidly. Calasept failed to eliminate, even superficially, E. faecalis in the tubules. The method used in bacteriological sampling allowed for sequential removal of 100-micron-thick zones of dentin from the central canal toward the periphery. Control specimens were uniformly infected and yielded growth in bur samples up to some 500 microns from the surface. The model proved quite sensitive and seems suitable for in vitro testing of root canal medicaments.
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The purposes of this study were to determine what microbial flora were present in teeth after failed root canal therapy and to establish the outcome of conservative re-treatment. Fifty-four root-filled teeth with persisting periapical lesions were selected for re-treatment. After removal of the root filling, canals were sampled by means of advanced microbiologic techniques. The teeth were then re-treated and followed for up to 5 years. The microbial flora was mainly single species of predominantly gram-positive organisms. The isolates most commonly recovered were bacteria of the species Enterococcus faecalis. The overall success rate of re-treatment was 74%. The microbial flora in canals after failed endodontic therapy differed markedly from the flora in untreated teeth. Infection at the time of root filling and size of the periapical lesion were factors that had a negative influence on the prognosis. Three of four endodontic failures were successfully managed by re-treatment.
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This study investigated the role of infection on the prognosis of endodontic therapy by following-up teeth that had had their canals cleaned and obturated during a single appointment. The root canals of 55 single-rooted teeth with apical periodontitis were thoroughly instrumented and irrigated with sodium hypochlorite solution. Using advanced anaerobic bacteriological techniques, post-instrumentation samples were taken and the teeth were then root-filled during the same appointment. All teeth were initially infected; after instrumentation low numbers of bacteria were detected in 22 of 55 root canals. Periapical healing was followed-up for 5 years. Complete periapical healing occurred in 94% of cases that yielded a negative culture. Where the samples were positive prior to root filling, the success rate of treatment was just 68%--a statistically significant difference. Further investigation of three failures revealed the presence of Actinomyces species in each case; no other specific bacteria were implicated in failure cases. These findings emphasize the importance of completely eliminating bacteria from the root canal system before obturation. This objective cannot be reliably achieved in a one-visit treatment because it is not possible to eradicate all infection from the root canal without the support of an inter-appointment antimicrobial dressing.
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The efficacy of five instrumentation techniques for cleaning the apical third of curved root canals was assessed by histological examination. Mesial root canals of freshly extracted human mandibular molars were prepared by the following instrumentation methods: step-back technique using stainless steel files; step-back technique using nickel-titanium files; ultrasonic technique; balanced force technique; and Canal Master U technique and instruments. The apical portion of the root was histologically processed, and cross-sections were examined for remaining soft tissue, predentin, and debris. The results showed no significant differences among the techniques. Although the five instrumentation methods were effective in removal of major amounts of tissue from the canals, none totally debrided the entire root canal system, especially when variations in the internal anatomy were present.
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The choice of an irrigating solution for use in infected root canals requires previous knowledge of the microorganisms responsible for the infectious process as well as the properties of different irrigating solutions. Complex internal anatomy, host defenses and microorganism virulence are important factors in the treatment of teeth with asymptomatic apical periodontitis. Irrigating solutions must have expressive antimicrobial action and tissue dissolution capacity. Sodium hypochlorite is the most used irrigating solution in endodontics, because its mechanism of action causes biosynthetic alterations in cellular metabolism and phospholipid destruction, formation of chloramines that interfere in cellular metabolism, oxidative action with irreversible enzymatic inactivation in bacteria, and lipid and fatty acid degradation. The aim of this work is to discuss the mechanism of action of sodium hypochlorite based on its antimicrobial and physico-chemical properties.
Article
The effect of endodontic irrigants and dressings was tested on bacteria in bovine dentin specimens experimentally infected with Enterococcus faecalis, Streptococcus sanguis, Escherichia coli, or Pseudomonas aeruginosa. Standardized, cylindrical dentin test pieces were prepared and cleaned by ultrasonic treatment with EDTA and sodium hypochlorite. The specimens were infected with the test organism for periods up to 14 days, and the degree of infection into the tubules was monitored using Brown & Brenn stain, scanning electron microscopy, and culturing of dentin dust from sequential bur samples starting from the pulpal side. E. faecalis rapidly infected the whole length of the tubules; S. sanguis required up to 2 weeks for complete infection; E. coli only penetrated to some 600 microns, even after prolonged incubation periods. P. aeruginosa infected dentin quickly, but apparently in very low numbers. E. faecalis persisted for at least 10 d after withdrawal of nutrient support, whereas the other 3 organisms died within 4 to 48 h. Endodontic medicaments were applied to infected specimen for comparison of antibacterial potency. Camphorated p-monochlorophenol was generally more efficient than Calasept, and of the irrigants tested, iodine potassium iodide appeared more potent than sodium hypochlorite or chlorhexidine. The presence of a smear layer delayed, but did not eliminate, the effect of the medicaments.
Article
In this study the antibacterial effect of irrigating infected root canals with 0.5 and 5 per cent sodium hypochlorite solutions was evaluated clinically. The results indicated that there was no difference between the antibacterial effect of these two solutions. The combined use of EDTA and S per cent sodium hypochlorite solution was more efficient than the use of sodium hypochlorite solutions alone.An important observation was that bacteria surviving instrumentation and irrigation rapidly increased in number in the period between appointments when no intracanal medicament was used.
Article
The antimicrobial properties of two different compositions of sodium hypochlorite were compared in a tube dilution study. Absorbent paper points were contaminated with Streptococcus faecalis or Candida albicans and exposed to 5.25% or 2.62% concentrations of "regular" or "fresh scent" sodium hypochlorite (Clorox) for periods ranging from 15 to 120 s. The points were then removed from the sodium hypochlorite solution, placed into a growth medium, incubated, and the presence or absence of growth recorded. Results showed that formulary changes involved in the manufacture of the "fresh scent" sodium hypochlorite had no apparent effect on its antimicrobial properties, as both compositions proved equally effective against the test organisms at each concentration evaluated.
Article
The effect of endodontic irrigants and dressings was tested on bacteria in bovine dentin specimens experimentally infected with Enterococcus faecalis, Streptococcus sanguis, Escherichia coli, or Pseudomonas aeruginosa. Standardized, cylindrical dentin test pieces were prepared and cleaned by ultrasonic treatment with EDTA and sodium hypochlorite. The specimens were infected with the test organism for periods up to 14 days, and the degree of infection into the tubules was monitored using Brown & Brenn stain, scanning electron microscopy, and culturing of dentin dust from sequential bur samples starting from the pulpal side. E. faecalis rapidly infected the whole length of the tubules; S. sanguis required up to 2 weeks for complete infection; E. coli only penetrated to some 600 microns, even after prolonged incubation periods. P. aeruginosa infected dentin quickly, but apparently in very low numbers. E. faecalis persisted for at least 10 d after withdrawal of nutrient support, whereas the other 3 organisms died within 4 to 48 h. Endodontic medicaments were applied to infected specimen for comparison of antibacterial potency. Camphorated p-monochlorophenol was generally more efficient than Calasept, and of the irrigants tested, iodine potassium iodide appeared more potent than sodium hypochlorite or chlorhexidine. The presence of a smear layer delayed, but did not eliminate, the effect of the medicaments.
Article
In nine monkeys (Macaca fascicularis) the pulps of 78 teeth were aseptically necrotized. Twenty-six of the pulp chambers were kept bacteria-free by sealing, while 52 were infected by the indigenous oral flora. The results were recorded clinically, radiographically and microbiologically at the beginning of the experiment and after 6-7 months. The final examination also included histologic recordings. The initially noninfected root canals were all sterile at the final samplings, indicating that the risk of contamination (including hematogenous) of root canals of this animal is very slight. It was shown that noninfected necrotic pulp tissue did not induce inflammatory reactions in the apical tissues. By contrast, teeth with infected pulp tissue showed inflammatory reactions clinically (12/52 teeth) and radiographically (47/52 teeth). Facultatively anaerobic streptococci, coliform rods and obligately anaerobic bacterial strains were most frequently found. In the final samples the number of obligately anaerobic strains increased. Some microorganisms which were isolated in the initial samples were not detected in the final samples. All infected teeth histologically examined showed strong inflammatory reactions in the periapical region.
Article
This study was undertaken to determine the antibacterial effects of various endodontic irrigants against six selected anaerobic bacteria. The organisms were mixed separately with dilutions of each of the irrigants in tubes containing fluid thioglycollate broth and allowed to remain in contact for specific time periods before being evaluated for growth. Of the six irrigants tested, chlorhexidine appeared to be the most effective antibacterial substance. Hydrogen peroxide, sodium hypochlorite and REDTA were less effective while the calcium hydroxide and saline solutions proved to be totally ineffective.
Article
Compared with exponential growing bacteria, carbohydrate-starved cells of Enterococcus faecalis exhibit a high level of resistance to sodium hypochlorite with maximal resistance observed in cultures entering stationary phase. Chloramphenicol treatment, at various stages of growing phase, does not abolish the hypochlorite resistance of starved cells. However, Enterococcus faecalis conditioned by low sodium hypochlorite concentrations does not develop tolerance towards a lethal dose of the disinfectant. Two-dimensional gel analysis shows that protein synthesis is drastically turned off by hypochlorite treatment, whereas synthesis of a few proteins is enhanced by a low concentration of this chemical agent.
Article
We previously reported that the in vitro antimicrobial activity of a 2.0% chlorhexidine endodontic irrigant was equivalent to that of 5.25% sodium hypochlorite. The purpose of this study was to determine if chlorhexidine irrigants could instill substantive antimicrobial activity in instrumented root canals in vitro. Human teeth were instrumented using 2.0% or 0.12% chlorhexidine as irrigants. After instrumentation, the root canals were filled with sterile water, and samples of the root canal fluid were absorbed with paper points at 6, 12, 24, 48, and 72 h after treatment. The paper points were assayed for antimicrobial activity by placing them on agar plate surfaces inoculated with Streptococcus mutans and measuring zones of inhibition. Antimicrobial activity was present in all 2.0% chlorhexidine-treated teeth throughout the 72-h testing period and in most teeth, in relatively lower concentrations, for 6 to 24 h after irrigation with 0.12% chlorhexidine. These results indicate that chlorhexidine instills substantive antimicrobial activity when used as an endodontic irrigant.
Article
The antibacterial effect of endodontic irrigants was evaluated against four black-pigmented Gram-negative anaerobes and four facultative anaerobic bacteria by means of the agar diffusion test. All solutions used were inhibitory against all bacterial strains tested. A 4% NaOCl solution provided the largest average zone of bacterial inhibition of this study that was significantly superior when compared with the other solutions, except 2.5% NaOCl (p < 0.05). Based on the averages of the diameters of the zones of bacterial growth inhibition, the antibacterial effects of the solutions could be ranked from strongest to weakest as follows: 4% NaOCl; 2.5% NaOCl; 2% chlorhexidine; 0.2% chlorhexidine, EDTA, and citric acid; and 0.5% NaOCl.
Article
This study was undertaken to determine the antimicrobial effect of various endodontic irrigants against six selected microorganisms. Staphylococcus aureus, Enterococcus faecalis, Streptococcus salivarius, Str. pyogenes, Escherichia coli and Candida albicans were included in the study. Pre-sterilized Whatman paper discs, 6 mm in diameter and soaked with the test solution, were prepared and placed onto the previously seeded agar Petri plates. Each plate was incubated aerobically. A zone of inhibition was recorded for each plate and the results were analysed statistically. 5.25% NaOCl was effective against all test microorganisms with a substantial zone of inhibition. Saline was always ineffective. Decreased concentration of NaOCl significantly reduced its antimicrobial effect. Cresophene showed a significantly larger (P < 0.05) average zone of inhibition compared to the other experimental irrigants. Alcohol had smaller but not significantly different zones of inhibition than chlorhexidine. 5.25% NaOCl was superior in its antimicrobial abilities compared with other irrigants used. A reduced concentration of NaOCl (0.5%) resulted in significantly decreased antimicrobial effects. When compared with 21% alcohol, 0.5% NaOCl and 2% chlorhexidine, paramonochlorophenol (cresophene) showed a greater antimicrobial effect.
Article
The aim of this study was to evaluate the susceptibility of seven strains of Candida albicans to four disinfectants: iodine potassium iodide, chlorhexidine acetate, sodium hypochlorite and calcium hydroxide. In addition, all possible pairs of the disinfectants were tested in order to compare the effect of the combination and its components. Filter paper discs were immersed in standardized yeast suspensions and then transferred to disinfectant solutions of different concentrations and incubated at 37 degrees C for 30 s, 5 min, 1 h and 24 h. After incubation the filter paper discs were transferred to vials with PBS and glass beads that were then vigorously shaken for dispersal of the yeast cells. PBS with resuspended yeasts was serially diluted 10-fold. Droplets of 25 microL from each dilution were inoculated on TSB agar plates and incubated in air at 37 degrees C for 24 h. The number of colony-forming units was then calculated from appropriate dilutions. C. albicans cells were highly resistant to calcium hydroxide. Sodium hypochlorite (5% and 0.5%) and iodine (2%) potassium iodide (4%) killed all yeast cells within 30 s, whilst chlorhexidine acetate (0.5%) showed complete killing after 5 min. Combinations of disinfectants were equally or less effective than the more effective component. All C. albicans strains tested showed similar susceptibility to the medicaments tested. This study indicates that sodium hypochlorite, iodine potassium iodide and chlorhexidine acetate are more effective than calcium hydroxide against C. albicans in vitro. However, combining calcium hydroxide with sodium hypochlorite or chlorhexidine may provide a wide-spectrum antimicrobial preparation with a long-lasting effect.
Article
The bactericidal effect of four antimicrobial agents was investigated against single-species biofilms derived from a range of root canal isolates. Single-species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony-forming units calculated. Iodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl elicited a 100% kill after 1 h incubation for all strains used. However, after 15 min, they showed differing bactericidal effects depending on the strain. None of the agents were effective against F. nucleatum after 15 min but NaOCl, iodine and chlorhexidine were all effective after 1 h. Colloidal silver was generally ineffective. The effectiveness of a particular agent was dependent on the nature of the organism in the biofilm and on the contact time. NaOCl was generally the most effective agent tested, followed by iodine. However the clinical efficacy of these agents must be considered in light of the complex root canal anatomy and polymicrobial nature of root canal infections.
Article
The objective of this study was to assess the chlorhexidine gluconate gel as an endodontic irrigant. First the ability of chlorhexidine gel to disinfect root canals contaminated in vitro with Enterococcus faecalis was investigated. A scanning electron microscope was also used to evaluate its cleansing ability compared with endodontic irrigants commonly used, such as sodium hypochlorite and chlorhexidine gluconate liquid. The results indicated that the chlorhexidine gel produced a cleaner root canal surface and had an antimicrobial ability comparable with that obtained with the other solutions tested. It was concluded that chlorhexidine gluconate in gel form has potential for use as an endodontic irrigant.
Article
The aim of this study was to assess, in vitro, the effectiveness of several concentrations of NaOCl (0.5%, 1%, 2.5%, 4% and 5.25%) and two forms of chlorhexidine gluconate (gel and liquid) in three concentrations (0.2%, 1% and 2%) in the elimination of E. faecalis. A broth dilution test using 24-well cell culture plates was performed and the time taken for the irrigants to kill bacterial cells was recorded. Isolated 24 h colonies of pure cultures of E. faecalis grown on 10% sheep blood plus Brain Heart Infusion (BHI) agar plates were suspended in sterile 0.85% NaCI solution. The cell suspension was adjusted spectrophotometrically to match the turbidity of a McFarland 0.5 scale. One mL of each tested substance was placed on the bottom of wells of 24-well cell culture plates (Corning, NY), including the control group (sterile saline). Six wells were used for each time period and irrigant concentration. Two mL of the bacterial suspension were ultrasonically mixed for 10 s with the irrigants and placed in contact with them for 10, 30, and 45 s; 1, 3, 5, 10, 20, and 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared BHI + neutralizers in order to prevent a residual action of the irrigants. All tubes were incubated at 37 degrees C for 7 days. The tubes considered to have positive growth were those which presented medium turbidity during the incubation period. Data were analysed statistically by the Kruskal-Wallis test. with the level of significance set at P < 0.05. All irrigants were effective in killing E. faecalis. but at different times. Chlorhexidine in the liquid form at all concentrations tested (0.2%, 1% and 2%) and NaOCI (5.25%) were the most effective irrigants. However, the time required by 0.2% chlorhexidine liquid and 2% chlorhexidine gel to promote negative cultures was only 30 s and 1 min, respectively. Even though all tested irrigants possessed antibacterial activity, the time required to eliminate E. faecalis depended on the concentration and type of irrigant used.
Article
To determine the effect of chlorine on mixed bacterial biofilms on stainless steel (SS) and conveyor belt surfaces. Biofilms were exposed to pH-adjusted (6.5) and non-pH-adjusted solutions of chlorine (200, 400 and 600 ppm) for either 2, 10 or 20 min and survivors enumerated. There were significant differences in cell death relating to chlorine concentration and exposure time for the cells attached to the SS, with solutions adjusted to pH 6.5 being more effective at reducing numbers. In contrast, on conveyor belt surfaces cell numbers decreased by less than two logs after 20 min regardless of treatment. Chlorine effectiveness is dependent on its concentration, solution pH, exposure time, the nature of the surface and the microbial species present. SIGNIFICANCE AND IMPACT OF THE STUDY the interests of food safety it is important that sanitizer users are aware of the conditions that effect their performance.
Article
Bactericidal activity of chlorine solution is enhanced by weak acidification. We compared the effects of various acids on the bactericidal activity of hypochlorite solution to establish a method for safe and effective use of an acidic hypochlorite solution. The bactericidal activities of acidic hypochlorite solutions that had been adjusted to pH 5.0 with hydrochloric acid, acetic acid, citric acid, lactic acid, formic acid, phosphoric acid or sulphuric acid against Bacillus subtilis spores were compared. The acidic solutions prepared with hydrochloric acid and acetic acid showed the highest bactericidal activity, and all of the spores (5 x 106 cfu ml(-1)) were killed within 10 min. On the other hand, the solutions prepared with citric acid and lactic acid showed no bactericidal activity against any bacterial strains tested in this study despite the low pH. The amount of chlorine gas produced by the preparation using acetic acid was sixfold less than that produced from the preparation using hydrochloric acid. Acetic acid is the most suitable and safe acid for the preparation of an acidic hypochlorite solution. The results of this study provide useful information for establishing a method for safe and effective use of an acidic hypochlorite solution.
Article
To evaluate the effectiveness of 2% chlorhexidine gluconate gel and calcium hydroxide (Ca(OH)2) as intracanal medicaments against Enterococcus faecalis. One hundred and eighty dentine tubes prepared from intact freshly extracted bovine maxillary central incisors were infected in vitro for 7 days with E. faecalis. The specimens were divided into four groups, according to the intracanal medicament used, as follows: Group 1: 2% chlorhexidine gluconate gel; Group 2: calcium hydroxide in a viscous vehicle (polyethyleneglycol 400); Group 3: 2% chlorhexidine gluconate gel + calcium hydroxide and Group 4: Brain Heart Infusion (BHI) broth (control group). The medicaments were placed into the canal lumen and left there for experimental times of 1, 2, 7, 15 and 30 days. After each period, irrigation with sterile saline to remove the medicament was performed and the canals were dried with sterile paper points. Dentine chips were removed from the canals with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing BHI broth. The tubes were incubated at 37 degrees C and daily observed for microbial growth, visualized by the medium turbidity. Chlorhexidine gel alone completely inhibited the growth of E. faecalis after 1, 2, 7 and 15 days. Calcium hydroxide allowed microbial growth at all experimental times. The combination of chlorhexidine and Ca(OH)2 was effective after 1 and 2 days demonstrating 100% antibacterial action; however, its antibacterial activity reduced between 7 and 15 days. Under the conditions of this study, it can be concluded that 2% chlorhexidine gel alone was more effective against E. faecalis than calcium hydroxide (P < 0.05). However, its antibacterial activity depended on how long it remained inside the root canal.
The purpose of this study was to observe the pathologic changes resulting from untreated experimental pulp exposures in germ-free rats as compared with conventional rats with a normally complex microflora. The pulp tissues of these rats were exposed by drilling through the occlusal surface of the maxillary right first molar with a carbide round bur mounted in a jeweler's spindle-topped hand mandrel. After varying postoperative time intervals (1 to 42 days), the animals were killed and the appropriate tissues were serially sectioned.By the eighth day, vital pulp tissue remained only in the apical half of the roots in the conventional animals. Complete pulpal necrosis with granulomas and abscess formation occurred in all older specimens. Evidence of repair was uniformly lacking.In contrast, no devitalized pulps, apical granulomas, or abscesses were found in the germ-free animals. Dentinal bridging began at 14 days and by 21 and 28 days was complete, regardless of the angle or severity of the exposure.These results, even in the face of gross food impactions, indicate that the presence or absence of a microbial flora is the major determinant in the healing of exposed rodent pulps.
Article
To evaluate in vitro the effectiveness of sodium hypochlorite (NaOCl), chlorhexidine (CHX) and five intracanal medicaments on microorganisms within root canals. Ninety-six human single-rooted extracted teeth were used. After removing the crowns, canal preparation was completed and the external root surfaces were coated with epoxy resin. Following sterilization, the teeth were contaminated with Candida albicans and Enterococcus faecalis, and were incubated at 37 +/- 1 degrees C for 7 days. The teeth were divided according to the irrigant solution or intracanal medicament: group 1, sterile physiologic solution (SPS) and calcium hydroxide (Ca(OH)2) paste; group 2, SPS and camphorated paramonochlorophenol (CPMC); group 3, SPS and tricresol formalin; group 4, SPS and CaOH2 + CPMC paste; group 5, SPS and PMC furacin; group 6, 2.5% NaOCl without intracanal medication; group 7, 2.0% CHX without intracanal medication and group 8, SPS without intracanal medication (control group). Microbiological samples were collected with sterile paper points, and bacterial growth was determined. The data were submitted to the analysis of variance (anova, P = 0.05). For C. albicans, groups 3 and 8 were statistically less effective than groups 1, 2, 4 and 5 (Kruskal-Wallis (K-W) = 65.241; gl = 7; P = 0.001). For E. faecalis, groups 6 and 8 were statistically less effective than groups 1-4 and 7 (K-W = 61.048; gl = 7; P = 0.001). Ca(OH)2 + CPMC paste was the most effective intracanal medicament for the elimination of the two microorganisms; 2.0% CHX solution was more effective than 2.5% NaOCl against E. faecalis.
Article
To determine the resistance of microorganisms associated with refractory endodontic infections to sodium hypochlorite used as a root canal irrigant. Two strains each of Actinomyces naeslundii, Candida albicans and Enterococcus faecalis were tested as late logarithmic phase inocula, against sodium hypochlorite adjusted to 0.5, 1.0, 2.5 and 5.25% w/v. Contact times used were 0, 10, 20, 30, 60 and 120 s. In the case of E. faecalis, additional experiments used contact times of 1.0, 2.0, 5.0, 10.0 and 30.0 min. Anti-microbial action was halted by sodium thiosulphate addition. Survivors were measured primarily using viable counts on drop plates. Additionally, pour plates were used to count low colony-forming units (cfu) and dilutions to 10(-6) were used to count high cfu. All concentrations of NaOCl lowered cfu below the limit of detection after 10 s in the case of A. naeslundii and C. albicans. However, E. faecalis proved to be more resistant to NaOCl. Using 0.5% NaOCl for 30 min reduced cfu to zero for both strains tested. This compares with 10 min for 1.0%, 5 min for 2.5% and 2 min for 5.25% (P < 0.001). Regression analysis for the dependent variable log(e)(count + 1) with log(e)(time + 1) and concentration as explanatory variables gave rise to a significant interaction between time and concentration (P < 0.001). The published association of E. faecalis with refractory endodontic infection may result, at least partially, from high resistance of this species to NaOCl. This does not appear to be the case with A. naeslundii or C. albicans.
Article
To test the effectiveness of electrochemically activated aqueous solutions in the debridement of Enterococcus faecalis biofilms in root canals of extracted teeth. Extracted, human, single-rooted teeth (198) assembled into 11 sets (n = 18) with matching anatomical characteristics were randomly assigned to eight experimental groups. After decoronation, the root canals were prepared to a standard size. Enterococcus faecalis biofilms were grown in the root canals of autoclaved, individually mounted teeth over 48 h. Electrolysed saline collected as anolyte at the anode and catholyte at the cathode were the test agents. The four ultrasonication and four without ultrasonication irrigant groups included: neutral anolyte (NA) (pH 6.5), acidic anolyte (AA) (pH 3.0), catholyte (C) (pH 11.5) and C alternated with neutral anolyte (C/NA). Phosphate-buffered saline (PBS) with and without ultrasonication formed negative and NaOCl (3%) positive control groups. After irrigation, root canal samples were serially diluted, cultured and enumerated. The data were analysed as ratios of residual colony-forming units (CFUs) in PBS versus the test irrigants and using multivariate regression. The NA and NA (ultrasonicated, U), C/NA and AA (U) groups had significantly (alpha = 0.05) less and C (U) and C/NA (U) significantly (alpha = 0.05) more bacteria (CFUs mL(-1)) compared with their respective PBS controls. Ultrasonicated C/NA had significantly (alpha = 0.05) higher CFU counts than the nonultrasonicated solution. Other comparisons between ultrasonic and nonultrasonic groups were not significant. Of the nonultrasonicated groups, C/NA and NA were most effective, whilst of the ultrasonicated groups, AA and NA were most effective. None of these was as effective as 3% NaOCl. All but two groups (AA and C) were significantly different from their PBS controls. There was a significant difference between the C/NA groups with and without ultrasonication but not between other combinations. NA (U) and AA (U) were the most effective test solutions but NaOCl (3%) gave by far the highest bacterial kills.
Article
To assess the in vivo intracanal microbial status of apical root canal system of mesial roots of human mandibular first molars with primary apical periodontitis immediately after one-visit endodontic treatment. The residual intracanal infection was confirmed by correlative light and transmission electron microscopy. Sixteen diseased mesial roots of mandibular first molars were treated endodontically, each in one visit. Mesio-buccal canals were instrumented using stainless steel hand files and mesio-lingual canals with a nickel-titanium rotary system. The canals were irrigated with 5.25% sodium hypochlorite (NaOCl) during the instrumentation procedures, rinsed with 10 mL of 17% ethylenediamine tetraacetic acid (EDTA), and obturated with gutta-percha and zinc oxide eugenol cement. Thereafter, the apical portion of the root of each tooth was removed by flap-surgery. The specimens were fixed, decalcified, subdivided in horizontal plane, embedded in plastic, processed, and evaluated by correlative light and transmission electron microscopy. Fourteen of the 16 endodontically treated teeth revealed residual intracanal infection after instrumentation, antimicrobial irrigation, and obturation. The microbes were located in inaccessible recesses and diverticula of instrumented main canals, the intercanal isthmus, and accessory canals, mostly as biofilms. The results show (1) the anatomical complexity of the root canal system of mandibular first molar roots and (2) the organization of the flora as biofilms in inaccessible areas of the canal system that cannot be removed by contemporary instruments and irrigation alone in one-visit treatment. These findings demonstrate the importance of stringent application of all nonantibiotic chemo-mechanical measures to treat teeth with infected and necrotic root canals so as to disrupt the biofilms and reduce the intraradicular microbial load to the lowest possible level so as to expect a highly favorable long-term prognosis of the root canal treatment.
Article
The aim of this study was to assess interactions of EDTA and citric acid (CA) with sodium hypochlorite (NaOCl), the indispensable endodontic irrigant. Other chelators were simultaneously evaluated as possible alternatives: sodium triphosphate (STP), amino tris methylenephosphonic acid (ATMA), and 1- hydroxyethylidene-1, 1-bisphosphonate (HEBP). Available chlorine was titrated in chelator-NaOCl solutions. All chelators other than HEBP and STP caused an almost complete, immediate loss of available chlorine in solution. Atomic absorbtion spectrometry and SEM evaluation of root canal walls of instrumented teeth indicated that NaOCl had no negative effect on calcium-complexing ability of chelators. STP was too weak a complexing agent to warrant further studies. Finally, CA-, EDTA-, and HEBP-NaOCl mixtures were evaluated for their antimicrobial capacity. Again, EDTA and CA negatively interfered with NaOCl, while HEBP did not.
Article
In this study, the antibacterial activity of the different antibacterial solutions using as root canal irrigant was compared in the teeth with pulpal necrosis and with periapical pathosis. Thirty root canals of incisors and premolars of 20 patients were used. Before and after the root canal preparation, two canal samples were obtained by a harvesting method using a sterile paper point in the first appointment. During the biomechanical preparation, both irrigant solutions were used for each tooth which were randomly divided into two groups. Last samples were also obtained before the root filling procedure. Samples obtained from the root canals were subjected to microbiologic processing, including anaerobic incubation on trypticase soy agar for 5 to 7 days. After counting of CFU on the plates, we concluded that both chlorhexidine gluconate and sodium hypochlorite were significantly effective to reduce the microorganisms in the teeth with necrotic pulp, periapical pathologies, or both, and could be used successfully as an irrigant solution.
Article
This paper analyses the evolution of hypochlorite as strong disinfectant. The electrochemical production of hypochloric acid or sodium hypochlorite represents the best method to obtain a pure product. To have a good production (as quality and quantity), it is necessary to optimize the electrochemical process with the optimal of electrocatalytic electrodes (cathode and anode) the gap between electrodes, the temperature of electrochemical cell. It is very important for the product stability during a long period, avoid the presence of heavy metal ions and particulate as impurity-like carbon micro-powders in suspension. It is necessary a rigorous control of the pH of final product to have the optimal disinfection power of hypochlorite solution. The most stable sodium hypochlorite solutions are those that show the following characteristics: (1) low concentration of hypochlorite; (2) pH -> 11.5 and <13; (3) absence of graphite particulate and metallic ions; (4) storage at controlled temperature <30 degrees C. Packing in containers impermeable to light.
Article
Sodium hypochlorite (NaOCl) is the most widely used disinfectant in the food industry despite the increasing availability of other disinfectants. Sodium hypochlorite fulfills many requirements as the ideal disinfectant and furthermore it has an excellent cleaning action. The effectiveness of sodium hypochlorite in the cleaning and disinfection processes depends on the concentration of available chlorine and the pH of the solution. Hypochlorous acid (HOCl) is a weak acid and dissociates to the hypochlorite ion (-OCl) and proton (H+) depending on the solution pH. It is generally believed that HOCl is the active species in the germicidal action, whereas the concentration of -OCl is a key factor determining the cleaning efficiency. This implies that the optimal pH region of the germicidal activity of sodium hypochlorite differs from that of its cleaning activity. This paper describes the theory and practice of the cleaning and disinfecting operations based on the use of sodium hypochlorite solution.
Antibacterial effects of various endodontic irrigants on selected anaerobic bacteria In vitro susceptibility of Candida albicans to four disinfectants and their combinations
  • P Ohara
  • M Torabinejad
  • Kettering
  • Tm Waltimo
  • D Orstavik
  • Ek Siren
  • Haapasalo
Ohara P, Torabinejad M, Kettering JD. Antibacterial effects of various endodontic irrigants on selected anaerobic bacteria. Endod Dent Traumatol 1993;9:95-100. 18. Waltimo TM, Orstavik D, Siren EK, Haapasalo MP. In vitro susceptibility of Candida albicans to four disinfectants and their combinations. Int Endod J 1999;32:421-9.
Mechanisms of actions of sodium hypochlorite in cleaning and disinfection processes Reprint requests: Montserrat Mercadé, DDS, PhD Dentistry Faculty Universitat Internacional de Catalunya C/Josep Trueta s/n 08195 Sant Cugat del Vallès Barcelona, Spain monmer9@hotmail.com OOOOE 298 Mercade et al
  • S Fukuzaki
Fukuzaki S. Mechanisms of actions of sodium hypochlorite in cleaning and disinfection processes. Biocontrol Sci 2006;11: 147-57. Reprint requests: Montserrat Mercadé, DDS, PhD Dentistry Faculty Universitat Internacional de Catalunya C/Josep Trueta s/n 08195 Sant Cugat del Vallès Barcelona, Spain monmer9@hotmail.com OOOOE 298 Mercade et al. February 2009
PhD Dentistry Faculty Universitat Internacional de Catalunya C/Josep Trueta s
  • Montserrat Mercadé
  • Dds
Montserrat Mercadé, DDS, PhD Dentistry Faculty Universitat Internacional de Catalunya C/Josep Trueta s/n 08195