ABSTRACT
Objective:
This research aims to analyze the antimicrobial efficacy of “sodium hypochlorite (NaOCl)” and “chlorhexidine (CHX)” as canal irrigants, evaluating their effects on bacterial load during “Root canal treatment (RCT)”.
Materials and Methods:
In this randomized controlled trial, 80 subjects requiring RCT were included. The participants were randomly allocated into two groups: Group A received 2.5% NaOCl as the irrigant, while Group B received 2% CHX. Microbial samples were gathered from the root canals using sterile paper points both before and after irrigation. The bacterial load was evaluated by counting “colony-forming units (CFUs)” following bacterial culture. Statistical analyzes were conducted using paired t-tests and ANOVA, with a significance level of P < 0.05.
Results:
Both NaOCl and CHX demonstrated substantial reductions in the bacterial load within the canal system. Group A (NaOCl) achieved a post-irrigation mean CFU count of 1.9 million, reflecting a 96% reduction in bacterial load. Group B (CHX) recorded a mean CFU count of 6.7 million, corresponding to an 86% reduction. The difference in bacterial reduction between the two groups was statistically significant (P < 0.01), indicating that NaOCl was more effective than CHX as an irrigant.
Conclusion:
Sodium hypochlorite proved to be more efficient than chlorhexidine in reducing microbial counts in root canals. While NaOCl appears to offer superior bacterial reduction, CHX, due to its substantivity and lower cytotoxicity, may still have valuable roles in particular clinical contexts.
KEYWORDS: Antimicrobial efficacy, chlorhexidine, endodontic irrigation, root canal therapy, sodium hypochlorite
INTRODUCTION
Root canal treatment (RCT) relies on both mechanical and chemical debridement of the root canal system to effectively eliminate bacteria and prevent reinfection. Enterococcus faecalis is frequently identified as the primary pathogen associated with failed RCT.[1,2] The successful eradication of bacterial infections within the canal largely depends on the efficacy of the irrigation process, using antimicrobial solutions. Commonly used irrigants include NaOCl and CHX.[3,4,5] This research aims to assess and compare the antimicrobial effects of 2.5% NaOCl and 0.02% CHX in vitro, focusing on their ability to reduce microbial presence in infected root canals.
METHODOLOGY
Research design
This randomized controlled research included 80 subjects with infected root canals undergoing RCT. Participants were randomly divided into two groups: Group A (n = 40), treated with 2.5% sodium hypochlorite as the primary irrigant and Group B (n = 40), treated with 2% chlorhexidine.
Inclusion Criteria:
Subjects aged between 18 and 50 requiring RCT.
Radiographic evidence confirming infection within the canal system.
Subjects provided informed consent for participation.
Exclusion Criteria:
Pregnant or breastfeeding women.
Individuals with systemic diseases or allergic reactions to the irrigants.
Subjects with prior RCT on the affected tooth.
Sampling and irrigation procedure
Microbial samples were taken from the canal system using sterile paper points both before and after irrigation. The samples were then cultured on agar plates to allow for bacterial growth and identification. Group A was irrigated with 5 mL of 2.5% NaOCl, while Group B received 5 mL of 2% CHX, following standard clinical protocols. Irrigation was performed using a syringe and needle, lasting for one minute between instrumentation steps.
Microbial assessment
The pre- and post-irrigation samples were processed for microbial growth, and CFUs were counted to assess the bacterial load. Bacterial species were identified using appropriate biochemical tests.
Statistical analysis
Data analysis was conducted using paired t-tests and ANOVA to compare the reduction in CFUs between the two groups. A P value of less than 0.05 was considered statistically significant.
RESULTS
Table 1 illustrates that the baseline characteristics of the research participants, including age, gender distribution, and pre-irrigation bacterial load, were comparable between the two groups (P > 0.05). The average age in Group A (sodium hypochlorite) was 35.6 ± 8.2 years, while in Group B (chlorhexidine), it was 36.1 ± 7.9 years, with no significant age difference between the groups (P = 0.78). Similarly, gender distribution showed no statistically significant variation (P = 0.64). Both groups exhibited nearly identical pre-irrigation bacterial loads, with a mean CFU count of 4.7 million in Group A and 4.8 million in Group B (P = 0.82), indicating that the groups were well balanced at the start of the research.
Table 1.
Baseline characteristics of research population
| Characteristic | Group A (sodium hypochlorite) | Group B (chlorhexidine) | P |
|---|---|---|---|
| Number of subjects | 40 | 40 | N/A |
| Mean Age (years) | 35.6±8.2 | 36.1±7.9 | 0.78 |
| Gender (male/female) | 20/20 | 22/18 | 0.64 |
| Pre-irrigation CFU count (×million) | 4.7±1.3 | 4.8±1.4 | 0.82 |
| Tooth involved (anterior/posterior) | 15/25 | 18/22 | 0.52 |
Table 2 indicates that both irrigants were effective in significantly reducing the bacterial load in the canal system. However, sodium hypochlorite (Group A) demonstrated greater antimicrobial efficacy compared to chlorhexidine (Group B). The mean post-irrigation CFU count for Group A was 1.9 million, representing a 96% reduction in bacterial load, while Group B showed a mean CFU count of 6.7 million post-irrigation, corresponding to an 86% decrease. The difference in bacterial load reduction between the two groups was statistically significant (P < 0.01), indicating that NaOCl was more effective than CHX in eliminating microorganisms from infected root canals.
Table 2.
Comparison of pre- and post-irrigation bacterial load
| Bacterial load (CFU × million) | Group A (sodium hypochlorite) | Group B (chlorhexidine) | P |
|---|---|---|---|
| Pre-irrigation CFU (mean) | 4.7±1.3 | 4.8±1.4 | 0.82 |
| Post-irrigation CFU (mean) | 1.9±0.9 | 6.7±1.1 | <0.01 |
| Reduction in CFU (%) | 96% | 86% | <0.01 |
DISCUSSION
NaOCl demonstrated significantly higher efficacy in reducing the bacterial population in infected root canals compared to CHX. Both irrigants showed a considerable antimicrobial effect, but NaOCl achieved a remarkable 96% reduction in bacterial load, compared to CHX’s 86%. This difference was statistically significant (P < 0.01), suggesting that NaOCl is more effective for canal disinfection, particularly in cases with complex anatomical features where bacteria may persist.[1]
The superior performance of NaOCl can be attributed to its unique properties, including its capacity to dissolve necrotic tissue and organic material while releasing chlorine, which acts as a potent antimicrobial agent.[2] These characteristics enable NaOCl to penetrate deeper into the canal system, effectively disrupting biofilms and eliminating a wide range of microorganisms.[3] However, the tissue-dissolving ability of NaOCl also raises concerns about potential cytotoxicity, especially if the solution extrudes beyond the root apex, causing irritation to surrounding tissues.[4]
Chlorhexidine, while also possessing strong antimicrobial effects—especially against Enterococcus faecalis, a common cause of persistent canal infections—has a lower cytotoxicity profile and offers substantivity, meaning it continues to exert antimicrobial effects for an extended period after irrigation.[5,6] However, CHX lacks the tissue-dissolving properties of NaOCl, limiting its ability to remove necrotic tissue and biofilms from the canal system.[7]
Clinically, these findings suggest that NaOCl is the preferred irrigant for canal therapy due to its superior bacterial reduction and tissue-dissolving capabilities.[8] Nonetheless, its potential cytotoxic effects must be carefully managed, especially in situations where it might extrude into periapical tissues. CHX could serve as a beneficial adjunct in cases requiring prolonged antimicrobial effects, particularly in subjects with sensitive periapical tissues or compromised healing capacity.[9]
Future research should investigate the combined use of NaOCl and CHX in sequential irrigation protocols, aiming to optimize bacterial reduction while minimizing the associated risks, ultimately enhancing treatment outcomes in endodontic therapy.[10]
CONCLUSION
This research highlights that NaOCl is significantly more effective than CHX in reducing bacterial load during canal therapy, achieving a 96% reduction compared to CHX’s 86%. NaOCl’s ability to dissolve tissues and its broad-spectrum antimicrobial action make it the preferred choice for canal disinfection, although care must be taken to manage its cytotoxicity. While CHX offers antimicrobial benefits, particularly in cases with periapical sensitivity, NaOCl remains the irrigant of choice. Future studies should explore using a combination of these agents to improve disinfection and minimize risks for better clinical outcomes.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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