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An evaluation of the action of different root canal irrigants on facultative aerobic-anaerobic, obligate anaerobic, and microaerophilic bacteria
JOURNALOF ENDODONTICS Copyright © 1999 by The American Association of Endodontists
Printed in U.S.A. VOL. 25, No. 5, MAY 1999
An Evaluation of the Action of Different Root Canal Irrigants on Facultative Aerobic-Anaerobic, Obligate Anaerobic, and Microaerophilic Bacteria Camillo D'Arcangelo, DDS, Giuseppe Varvara, DDS, and Pietro De Fazio, MD, DDS
The aim of this study was to test the effect of different concentrations of sodium hypochlorite, chlorhexidine, and cetrimide on the following bacterial strains:
richia coli, Pseudomonas aeruginosa, Streptococcus mitis, Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguis), and microaerophiles (Actinobacillus actinomycetemcomitans) (2). Root canal irrigation plays a key role in the success of endodontic treatment, because it helps in the progressive removal of the smear layer and neutralizes the root canal microbic flora. In the last few years, several investigators have provided evidence that the degree of cleaning of a prepared root canal, although certainly related to the instrumentation techniques used, is also dependent on the accuracy of the irrigation procedures (3). Several irrigating solutions have been described in the literature. Currently, the most frequently used are several different sodium hypochlorite solutions, EDTA and other chelating solutions, and chlorhexidine combined with cetrimide. The objective of this study was to test the antimicrobial efficiency of sodium hypochlorite in different concentrations and of new generation irrigants composed of different concentrations of chlorhexidine and cetrimide on the microorganisms that are most frequently found inside the root canal system.
• Facultative aerobes-anaerobes: Candida albicans ATCC 10231; Enterococcus faecalis ATCC 29212; Escherichia coil ATCC 25 922; Pseudomonas aeruginosa ATCC 27 853; Streptococcus mitis ATCC 9811; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; and Streptococcus sanguis ATCC 10556. • Microaerophiles: Actinobacillus actinomycetemcornitans ATCC 29522. • Obligate anaerobes: Actinomyces odontolyticus ATCC 17929; Fusobacterium nucleatum ATCC 25 586; Porphyromonas gingivalis ATCC 33277; and Prevotella melaninogenica ATCC 25845. Each irrigant was kept in contact with the bacterial species used for the experiment for 10, 20, or 30 min. Results showed that all irrigants had a bactericidal effect on both facultative aerobes-anaerobes and on microaerophilic and obligate anaerobic strains, in all concentrations and even after short periods of contact.
M A T E R I A L S AND M E T H O D S The following bacterial strains were evaluated:
• Facultative aerobes-anaerobes: Candida albicans ATCC 10231; Enterococcus faecalis ATCC 29212; Escherichia coli ATCC 25 922; Pseudomonas aeruginosa ATCC 27 853; Streptococcus mitis ATCC 9811 ; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; and Streptococcus sanguis ATCC 10556. • Microaerophiles: Actinobacillus actinomycetemcomitans ATCC
The primary cause of endodontic failure is to be sought in the persistence of infection in the root canal system, that prevents healing of the periapical area. The presence of necrotic tissue and bacteria may determine the persistence of infection in the root canal. Zavistosky et al. (1) have studied the quantity of bacteria that are present in the root canals of necrotic teeth. The amount is similar to the bacterial concentration in other anatomical areas in the presence of infections. The bacteria that are most frequently found inside the root canals of infected teeth are obligate anaerobes
29522.
• Obligate anaerobes: Actinomyces odontolyticus ATCC 17929; Fusobacterium nucleatum ATCC 25 586; Porphyromonas gingivalis ATCC 33277; and Prevotella melaninogenica ATCC 25845. The work concentration (CFU/ml) was defined at 0.5 McFarland, which corresponded to a microorganism concentration equal to approximately 1.5 x 108 bacteria. For a reading of bacterial opacity, we used the spectrophotometer at a wavelength of 55 nm. Root Canal irrigants were used in the following concentrations: 0.2% cetrimide + 0.2% chlorhexidine; 0.2% cetrimide + 1% chlorhexidine; 0.2% cetrimide + 0.5% chlorhexidine; 0.2% cet-
(Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella melaninogenica, and Actinomyces odontolyticus), facultative aerobes-anaerobes (Candida albicans, Enterococcus faecaIis, Esche-
351
352
Journal of Endodontics
D'Arcangelo et al.
rimide + 0.4% chlorhexidine; 0.2% cetrimide + 0.3% chlorhexidine; 0.2% chlorhexidine + 1% cetrimide; 0.2% chlorhexidine + 0.5% cetrimide; 0.2% chlorhexidine + 0.4% cetrimide; 0.2% chlorhexidine + 0.3% cetrimide; 5% NaOC1; 3% NaOCl (60 ml + 40 ml sterile distilled H20); 1% NaOCI (20 ml + 80 ml sterile distilled H20); and 0.5% NaOCI (10 ml + 90 ml sterile distilled H20). Each substance was kept in contact with the bacterial species for 10, 20, or 30 rain. For every bacterial strain, starting from a concentration equal to 1.5 × l0 s CFU/ml, we diluted it to 1:10, 1100, and 1:1000. That is, we introduced 1 ml of broth into 9 ml of Ringer's solution (Unipath, Milan, Italy) obtaining a final dilution of 1:1000, thus passing from an initial concentration equal to 108 CFU/ml to a final concentration equal to 10 CFU/ml. We took 1 ml of this new concentration and placed it once again in 9 ml of Ringer's solution, thus obtaining a further I:10 dilution corresponding to 104 CFU/ml. From this broth culture, we placed 0.1 ml in Brain Heart Infusion Agar plates (Unipath), obtaining a concentration equal to 1000 CFUIml, which served as a control plate; 1 ml of the same bacterial suspension was placed in a test tube containing 9 ml of each irrigant. This same procedure was used for all eight facultative aerobic-anaerobic bacterial strains under examination. We then placed the 112 test tubes (14 solutions × 8 strains) in a water bath equipped with a shaking mechanism at 37°C, and after 10, 20, and 30 rain, respectively, we placed 1 ml of bacterial suspension plus root canal irrigant in a plate containing Brain Heart Infusion Agar and incubated it at 37°C for 24 h. The Candida albicans ATCC 10231 strain was incubated at 30°C for 24 h. The same procedure was applied for the microaerophilic and anaerobic bacteria, which were plated in different media. Actinobacillus actinomycetemcomitans ATCC 29522 was cultured in Tryptone Soya Broth (Unipath), with the addition of 75 mg/L of bacitracin and 5 mg/L of ancornicine, at 37°C, in carboxyphilia (10% CO2) in a Gas-Pack jar for 72 h. Actinomyces odontolyticus ATCC 17929 was cultured in Brain Heart Infusion Agar plates (Unipath S.p.A.), with the addition of 30 mg/L of Nalidixo acid and 10 mg/L of metronidazole, and kept for 7 days at 35°C in an anaerobiotic hood (Don Whitley Scientific Ltd., London, UK) fed with a gas mix equal to 10% H 2 + 10% CO2 + 80% N 2. Fusobacterium nucleatum ATCC 25 586, Porphyromonas gingivalis ATCC 33277, and Prevotella melaninogenica ATCC 25845 were cultured in Wilkins Chalgren Anaerobic Agar (with the addition of 5% defibrinated ovine blood), and kept at 35°C in anaerobiotic hood for 7 days. This procedure was applied to all the root canal irrigants under examination.
RESULTS All irrigants tested had a strong bactericidal effect on all bacteria strains. There was no difference among the irrigants tested: sodium hypochlorite in different concentrations and solutions of cetrimide and chlorhexidine in different concentrations. The vitality of all microorganisms tested was always 0 after a contact period of l0 rain with each root canal irrigant. The same results were obtained after a period of 20 or 30 rain of contact.
DISCUSSION The irrigation procedure seems to play a key role in the success of endodontic treatment (3). Sodium hypochlorite, due to its powerful germicidal and bactericidal properties, is still the most fre-
quently used root canal irrigant (4). However, several investigators have suggested the use of chlorhexidine gluconate as an equally valuable root canal irrigant (5, 6). Our results showed that all evaluated irrigants have a strong bactericidal action in vitro toward obligate anaerobes, microaerophiles, and aerobic-anaerobic strains after a contact period of 10 rain. Our findings are in agreement with the results of other investigators who bare showed the bactericidal property of chlorexidine, when used as root canal irrigant (7). The efficacy of chlorexidine as root canal irrigant was proved for the first time by Parson et al. (5). In that study, chlorhexidine was absorbed and released from dentin and enamel even after 48 to 72 h of root instrumentation. On the other hand, Ringer et al. (8) demonstrated the presence of living microorganism after root canal instrumentation with a 0.2% chlorexidine solution. Delany et al. (6) demonstrated the bactericidal efficacy of 0.2% chlorexidine gluconate solution. Their findings were based on a comparative study between bacteriological samples obtained before, during, and immediately after instrumentation and use of a 0.2% chlorexidine gluconate solution and a control group of root canals treated with sterile saline solution. The outcome was a decrease of microorganisms in the samples treated with chlorexidine. An even more marked decrease in the number of microorganisms was found after 24 h. That study showed that chlorexidine gluconate in 0.2% solution is not only an excellent antimicrobial agent if used as an irrigant during an endodontic treatment, but also helps to reduce the microbial population left in the canal system after instrumentation when used as an intermediate medication. White et al. (7) reported that 2% chlorexidine has a higher bactericidal capability with a longer duration than a solution of 0.12% chlorexidine. Our results show that 0.2% chlorexidine, or at a lower concentration, has an optimal bactericidal effect toward the bacteria most frequently present in the root canal system. From a microbiological point of view, no difference was found between 1% and 0.2% chlorhexidine. It is possible that the combined use of cetrimide and chlorexidine could explain our different data. Cetrimide is a good tensioactive agent with consistent bactericidal properties. Concerning the clinical use of sodium hypochlorite, the optimal concentration that should be adopted is still under question. Different investigators have different recommendations, ranging from 0.5% to 5% (4, 9). On the other hand, our findings do not show any differences in bactericidal efficacy between the different irrigants used. Comparable results were obtained in Sundquists' study, in which different sodium hypochlorite concentrations showed similar bactericidal properties (9). Bystrom and Sundqvist (4) suggested that a concentration of 0.5% sodium hypochlorite has a good bactericidal activity. Jeansonne and White (10) claimed that sodium hypochlorite and chlorexidine have similar bactericidal effects in vitro. In conclusion, it must be stressed that we tested just the microbiological action of sodium hypochlorite and a solution of chlorexidine and cetrimide at different concentrations, but antimicrobial activity is not the only requirement of an endodontic irrigant. Root canal irrigants should also have other characteristics, such as high detergent power, low surface tension, the capability to be kept in a liquid state, ease of handling, and high proteolytic and tissuedissolving power (1). Most clinicians consider dissolution of pulp tissue to be of significant importance in root canal inigation. It has been reported (10) that, until chlorexidine is also shown to be effective in pulp tissue debridement, sodium hypochlorite must be considered the irrigant of choice because it has tissue-dissolving properties. Chlorexidine may still be useful as an alternative end-
Vol. 25, No. 5, May 1999
Root Canal Irrigants
odontic irrigant. Its excellent antimicrobial properties indicate it could be a useful substitute in patients who are allergic to sodium hypochlorite (10). This work was partially supported by the National Research Council (C.N.R.) and by the Ministry of University, Research and Technology (MU.R.S.T.) Dr. D'Arcangelo is a former graduate student of the Advanced Education Program, Department of Endodontics, School of Dentistry, University of Chieti; Dr. Varvara is a member of the Department of Endodontics, School of Dentistry, University of Chieti; and Dr. De Fazio is professor and chairman, Department of Endodontics, School of Dentistry, University of Chieti, Chiet), Italy. Address reprint requests to Dr. Camillo D'Arcangelo, Via S. Baroncini 16, 66100 Chieti, Italy.
References 1. Zavistosky J, Dzink J, Orderdonk A, Bartlett J. Quantitative bacteriology of endodontic infections. Oral Surg 1980;49:171-4.
353
2. Keudell K, Conte M, Fujmoto L, Ernest M, Berry HG. Microorganisms isolated from pulp chamber. J Endodon 1976;2:146-8. 3. Moodnik RM. Efficacy of biomechanicar instrumentations: a scanning electron microscope study. J Endodon 1976;2:261-6. 4. Bystrom A, Sundqvist G. Bacteriologic evaluation of the effect of 0.5% sodium hypochlorite in endodontic therapy. Oral Surg 1983;55:307-12. 5. Parson G J, Patterson SS, Mileer CH, Katz S, Katrawy AH, Newtone CW. Uptake and release of chlorhexidine by bovine pulp and dentine specimens and their subsequent acquisition of antibacterial properties. Oral Surg 1980; 49:455-9. 6. Delany GM, Patterson SS, Miller CH, Newton CW. The effect of chlorhexidine gluconate irrigation on the root canal flora of freshly extracted necrotic teeth. Oral Surg 1982;53:518-23. 7. White RR, Hays GL, Janer LR. Residual antimicrobial activity after canal irrigation with chlorhexidine. J Endodon 1997;23:229-31. 8. Ringer AM, Patterson SP, Newton CW, Miller CH, Mulhern JM. In vitro evaluation of chlorhexidine gluconate solution and sodium hypochrorite solution as root canal irrigants. J Endodon 1982;8:200-4. 9. Sundqvist G. Bakterien im wurzelkanaL Philiips J 1988;5:162-6. 10. Jeansonne MJ, White RR. A comparison of 2.0% chlorexidine gluconate and 5.25% sodium hypochrorite as antimicrobial endodontic irrigants. J Endodon 1994;20:276-8.
You Might Be Interested Political and legal maneuvering continue about who to blame for cigarette smoking and from whom monetary damages may be extracted. Some data are of interest (BMJ 314:654). Lung cancer is the most prevalent cancer in developed nations. Roughly 90% of patients with this condition die within 1 year of diagnosis. Cigarette smoking is directly responsible for 90% of lung cancer. Regardless of who's to blame for tobacco use, there is really not much doubt who pays, is there?
W. Raleigh
Printed in U.S.A. VOL. 25, No. 5, MAY 1999
An Evaluation of the Action of Different Root Canal Irrigants on Facultative Aerobic-Anaerobic, Obligate Anaerobic, and Microaerophilic Bacteria Camillo D'Arcangelo, DDS, Giuseppe Varvara, DDS, and Pietro De Fazio, MD, DDS
The aim of this study was to test the effect of different concentrations of sodium hypochlorite, chlorhexidine, and cetrimide on the following bacterial strains:
richia coli, Pseudomonas aeruginosa, Streptococcus mitis, Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguis), and microaerophiles (Actinobacillus actinomycetemcomitans) (2). Root canal irrigation plays a key role in the success of endodontic treatment, because it helps in the progressive removal of the smear layer and neutralizes the root canal microbic flora. In the last few years, several investigators have provided evidence that the degree of cleaning of a prepared root canal, although certainly related to the instrumentation techniques used, is also dependent on the accuracy of the irrigation procedures (3). Several irrigating solutions have been described in the literature. Currently, the most frequently used are several different sodium hypochlorite solutions, EDTA and other chelating solutions, and chlorhexidine combined with cetrimide. The objective of this study was to test the antimicrobial efficiency of sodium hypochlorite in different concentrations and of new generation irrigants composed of different concentrations of chlorhexidine and cetrimide on the microorganisms that are most frequently found inside the root canal system.
• Facultative aerobes-anaerobes: Candida albicans ATCC 10231; Enterococcus faecalis ATCC 29212; Escherichia coil ATCC 25 922; Pseudomonas aeruginosa ATCC 27 853; Streptococcus mitis ATCC 9811; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; and Streptococcus sanguis ATCC 10556. • Microaerophiles: Actinobacillus actinomycetemcornitans ATCC 29522. • Obligate anaerobes: Actinomyces odontolyticus ATCC 17929; Fusobacterium nucleatum ATCC 25 586; Porphyromonas gingivalis ATCC 33277; and Prevotella melaninogenica ATCC 25845. Each irrigant was kept in contact with the bacterial species used for the experiment for 10, 20, or 30 min. Results showed that all irrigants had a bactericidal effect on both facultative aerobes-anaerobes and on microaerophilic and obligate anaerobic strains, in all concentrations and even after short periods of contact.
M A T E R I A L S AND M E T H O D S The following bacterial strains were evaluated:
• Facultative aerobes-anaerobes: Candida albicans ATCC 10231; Enterococcus faecalis ATCC 29212; Escherichia coli ATCC 25 922; Pseudomonas aeruginosa ATCC 27 853; Streptococcus mitis ATCC 9811 ; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; and Streptococcus sanguis ATCC 10556. • Microaerophiles: Actinobacillus actinomycetemcomitans ATCC
The primary cause of endodontic failure is to be sought in the persistence of infection in the root canal system, that prevents healing of the periapical area. The presence of necrotic tissue and bacteria may determine the persistence of infection in the root canal. Zavistosky et al. (1) have studied the quantity of bacteria that are present in the root canals of necrotic teeth. The amount is similar to the bacterial concentration in other anatomical areas in the presence of infections. The bacteria that are most frequently found inside the root canals of infected teeth are obligate anaerobes
29522.
• Obligate anaerobes: Actinomyces odontolyticus ATCC 17929; Fusobacterium nucleatum ATCC 25 586; Porphyromonas gingivalis ATCC 33277; and Prevotella melaninogenica ATCC 25845. The work concentration (CFU/ml) was defined at 0.5 McFarland, which corresponded to a microorganism concentration equal to approximately 1.5 x 108 bacteria. For a reading of bacterial opacity, we used the spectrophotometer at a wavelength of 55 nm. Root Canal irrigants were used in the following concentrations: 0.2% cetrimide + 0.2% chlorhexidine; 0.2% cetrimide + 1% chlorhexidine; 0.2% cetrimide + 0.5% chlorhexidine; 0.2% cet-
(Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella melaninogenica, and Actinomyces odontolyticus), facultative aerobes-anaerobes (Candida albicans, Enterococcus faecaIis, Esche-
351
352
Journal of Endodontics
D'Arcangelo et al.
rimide + 0.4% chlorhexidine; 0.2% cetrimide + 0.3% chlorhexidine; 0.2% chlorhexidine + 1% cetrimide; 0.2% chlorhexidine + 0.5% cetrimide; 0.2% chlorhexidine + 0.4% cetrimide; 0.2% chlorhexidine + 0.3% cetrimide; 5% NaOC1; 3% NaOCl (60 ml + 40 ml sterile distilled H20); 1% NaOCI (20 ml + 80 ml sterile distilled H20); and 0.5% NaOCI (10 ml + 90 ml sterile distilled H20). Each substance was kept in contact with the bacterial species for 10, 20, or 30 rain. For every bacterial strain, starting from a concentration equal to 1.5 × l0 s CFU/ml, we diluted it to 1:10, 1100, and 1:1000. That is, we introduced 1 ml of broth into 9 ml of Ringer's solution (Unipath, Milan, Italy) obtaining a final dilution of 1:1000, thus passing from an initial concentration equal to 108 CFU/ml to a final concentration equal to 10 CFU/ml. We took 1 ml of this new concentration and placed it once again in 9 ml of Ringer's solution, thus obtaining a further I:10 dilution corresponding to 104 CFU/ml. From this broth culture, we placed 0.1 ml in Brain Heart Infusion Agar plates (Unipath), obtaining a concentration equal to 1000 CFUIml, which served as a control plate; 1 ml of the same bacterial suspension was placed in a test tube containing 9 ml of each irrigant. This same procedure was used for all eight facultative aerobic-anaerobic bacterial strains under examination. We then placed the 112 test tubes (14 solutions × 8 strains) in a water bath equipped with a shaking mechanism at 37°C, and after 10, 20, and 30 rain, respectively, we placed 1 ml of bacterial suspension plus root canal irrigant in a plate containing Brain Heart Infusion Agar and incubated it at 37°C for 24 h. The Candida albicans ATCC 10231 strain was incubated at 30°C for 24 h. The same procedure was applied for the microaerophilic and anaerobic bacteria, which were plated in different media. Actinobacillus actinomycetemcomitans ATCC 29522 was cultured in Tryptone Soya Broth (Unipath), with the addition of 75 mg/L of bacitracin and 5 mg/L of ancornicine, at 37°C, in carboxyphilia (10% CO2) in a Gas-Pack jar for 72 h. Actinomyces odontolyticus ATCC 17929 was cultured in Brain Heart Infusion Agar plates (Unipath S.p.A.), with the addition of 30 mg/L of Nalidixo acid and 10 mg/L of metronidazole, and kept for 7 days at 35°C in an anaerobiotic hood (Don Whitley Scientific Ltd., London, UK) fed with a gas mix equal to 10% H 2 + 10% CO2 + 80% N 2. Fusobacterium nucleatum ATCC 25 586, Porphyromonas gingivalis ATCC 33277, and Prevotella melaninogenica ATCC 25845 were cultured in Wilkins Chalgren Anaerobic Agar (with the addition of 5% defibrinated ovine blood), and kept at 35°C in anaerobiotic hood for 7 days. This procedure was applied to all the root canal irrigants under examination.
RESULTS All irrigants tested had a strong bactericidal effect on all bacteria strains. There was no difference among the irrigants tested: sodium hypochlorite in different concentrations and solutions of cetrimide and chlorhexidine in different concentrations. The vitality of all microorganisms tested was always 0 after a contact period of l0 rain with each root canal irrigant. The same results were obtained after a period of 20 or 30 rain of contact.
DISCUSSION The irrigation procedure seems to play a key role in the success of endodontic treatment (3). Sodium hypochlorite, due to its powerful germicidal and bactericidal properties, is still the most fre-
quently used root canal irrigant (4). However, several investigators have suggested the use of chlorhexidine gluconate as an equally valuable root canal irrigant (5, 6). Our results showed that all evaluated irrigants have a strong bactericidal action in vitro toward obligate anaerobes, microaerophiles, and aerobic-anaerobic strains after a contact period of 10 rain. Our findings are in agreement with the results of other investigators who bare showed the bactericidal property of chlorexidine, when used as root canal irrigant (7). The efficacy of chlorexidine as root canal irrigant was proved for the first time by Parson et al. (5). In that study, chlorhexidine was absorbed and released from dentin and enamel even after 48 to 72 h of root instrumentation. On the other hand, Ringer et al. (8) demonstrated the presence of living microorganism after root canal instrumentation with a 0.2% chlorexidine solution. Delany et al. (6) demonstrated the bactericidal efficacy of 0.2% chlorexidine gluconate solution. Their findings were based on a comparative study between bacteriological samples obtained before, during, and immediately after instrumentation and use of a 0.2% chlorexidine gluconate solution and a control group of root canals treated with sterile saline solution. The outcome was a decrease of microorganisms in the samples treated with chlorexidine. An even more marked decrease in the number of microorganisms was found after 24 h. That study showed that chlorexidine gluconate in 0.2% solution is not only an excellent antimicrobial agent if used as an irrigant during an endodontic treatment, but also helps to reduce the microbial population left in the canal system after instrumentation when used as an intermediate medication. White et al. (7) reported that 2% chlorexidine has a higher bactericidal capability with a longer duration than a solution of 0.12% chlorexidine. Our results show that 0.2% chlorexidine, or at a lower concentration, has an optimal bactericidal effect toward the bacteria most frequently present in the root canal system. From a microbiological point of view, no difference was found between 1% and 0.2% chlorhexidine. It is possible that the combined use of cetrimide and chlorexidine could explain our different data. Cetrimide is a good tensioactive agent with consistent bactericidal properties. Concerning the clinical use of sodium hypochlorite, the optimal concentration that should be adopted is still under question. Different investigators have different recommendations, ranging from 0.5% to 5% (4, 9). On the other hand, our findings do not show any differences in bactericidal efficacy between the different irrigants used. Comparable results were obtained in Sundquists' study, in which different sodium hypochlorite concentrations showed similar bactericidal properties (9). Bystrom and Sundqvist (4) suggested that a concentration of 0.5% sodium hypochlorite has a good bactericidal activity. Jeansonne and White (10) claimed that sodium hypochlorite and chlorexidine have similar bactericidal effects in vitro. In conclusion, it must be stressed that we tested just the microbiological action of sodium hypochlorite and a solution of chlorexidine and cetrimide at different concentrations, but antimicrobial activity is not the only requirement of an endodontic irrigant. Root canal irrigants should also have other characteristics, such as high detergent power, low surface tension, the capability to be kept in a liquid state, ease of handling, and high proteolytic and tissuedissolving power (1). Most clinicians consider dissolution of pulp tissue to be of significant importance in root canal inigation. It has been reported (10) that, until chlorexidine is also shown to be effective in pulp tissue debridement, sodium hypochlorite must be considered the irrigant of choice because it has tissue-dissolving properties. Chlorexidine may still be useful as an alternative end-
Vol. 25, No. 5, May 1999
Root Canal Irrigants
odontic irrigant. Its excellent antimicrobial properties indicate it could be a useful substitute in patients who are allergic to sodium hypochlorite (10). This work was partially supported by the National Research Council (C.N.R.) and by the Ministry of University, Research and Technology (MU.R.S.T.) Dr. D'Arcangelo is a former graduate student of the Advanced Education Program, Department of Endodontics, School of Dentistry, University of Chieti; Dr. Varvara is a member of the Department of Endodontics, School of Dentistry, University of Chieti; and Dr. De Fazio is professor and chairman, Department of Endodontics, School of Dentistry, University of Chieti, Chiet), Italy. Address reprint requests to Dr. Camillo D'Arcangelo, Via S. Baroncini 16, 66100 Chieti, Italy.
References 1. Zavistosky J, Dzink J, Orderdonk A, Bartlett J. Quantitative bacteriology of endodontic infections. Oral Surg 1980;49:171-4.
353
2. Keudell K, Conte M, Fujmoto L, Ernest M, Berry HG. Microorganisms isolated from pulp chamber. J Endodon 1976;2:146-8. 3. Moodnik RM. Efficacy of biomechanicar instrumentations: a scanning electron microscope study. J Endodon 1976;2:261-6. 4. Bystrom A, Sundqvist G. Bacteriologic evaluation of the effect of 0.5% sodium hypochlorite in endodontic therapy. Oral Surg 1983;55:307-12. 5. Parson G J, Patterson SS, Mileer CH, Katz S, Katrawy AH, Newtone CW. Uptake and release of chlorhexidine by bovine pulp and dentine specimens and their subsequent acquisition of antibacterial properties. Oral Surg 1980; 49:455-9. 6. Delany GM, Patterson SS, Miller CH, Newton CW. The effect of chlorhexidine gluconate irrigation on the root canal flora of freshly extracted necrotic teeth. Oral Surg 1982;53:518-23. 7. White RR, Hays GL, Janer LR. Residual antimicrobial activity after canal irrigation with chlorhexidine. J Endodon 1997;23:229-31. 8. Ringer AM, Patterson SP, Newton CW, Miller CH, Mulhern JM. In vitro evaluation of chlorhexidine gluconate solution and sodium hypochrorite solution as root canal irrigants. J Endodon 1982;8:200-4. 9. Sundqvist G. Bakterien im wurzelkanaL Philiips J 1988;5:162-6. 10. Jeansonne MJ, White RR. A comparison of 2.0% chlorexidine gluconate and 5.25% sodium hypochrorite as antimicrobial endodontic irrigants. J Endodon 1994;20:276-8.
You Might Be Interested Political and legal maneuvering continue about who to blame for cigarette smoking and from whom monetary damages may be extracted. Some data are of interest (BMJ 314:654). Lung cancer is the most prevalent cancer in developed nations. Roughly 90% of patients with this condition die within 1 year of diagnosis. Cigarette smoking is directly responsible for 90% of lung cancer. Regardless of who's to blame for tobacco use, there is really not much doubt who pays, is there?
W. Raleigh