Effect Of Nanoparticles Based Root Canal Disinfectants On Enterococcus Faecalis - A Systematic Review

Keywords

Antibacterial; Endodontic Infection; Intracanal Medicaments; Irrigants; Periapical Disease; Nanotechnology.

Introduction

Background

The presence of bacteria and their by-products are responsible for various pulpal and periapical diseases. Enterococcus faecalis is the most dominant biofilm forming bacteria found in teeth with periradicular pathologies. It has an intrinsic resistance to irrigant solutions, intracanal medicaments, several antibiotics, and highly alkaline pH. It has the ability to tolerate starvation, harsh environment, and invade deeply into the dentinal tubules. To achieve complete success in root canal treatment, suppression of the biofilm is necessary [1, 2]. Cleaning and shaping of the root canal along with irrigation protocol have been shown to effectively decrease the number of microorganisms in the root canal. However, these procedures are unable to completely eliminate bacteria from lateral canals, isthmuses, and apical deltas. Therefore, the antibacterial protocol is achieved by utilizing intracanal medicaments [3].

Calcium hydroxide and chlorhexidine have been used since long time as effective intracanal medicaments. In endodontics, nanoparticles have been used as irrigants, intracanal medicaments or root canal sealers [4]. Nanoparticles are a class of newer materials which are hypothesized to have antibacterial effects. They cause disruption of the biofilm due to their nano size and structure. The nano size provides increased surface area which can absorb other medicaments and exert antimicrobial effects [5]. Silver nanoparticles are commonly used as they show strong bactericidal potential against Gram - positive, Gram- negative and multidrug- resistant bacteria. Nanoparticles have an ability to interact with bacterial cell wall leading to structural changes and then damaging the tissue protein [5-7]. The advantage of the use of nanotechnology is an increase in the surface- to- volume ratio of the materials, which increases the solubility, chemical activity and antibacterial efficacy of these agents as intracanal medicaments [3, 8]. Advances in nanotechnology have provided new and promising opportunities to kill bacteria, disrupt biofilm, and control dentinal tubule infection [9, 10]. A wide range of nanoparticles with antimicrobial activity have been developed in the recent years. Although these NPs are a potentially effective technology for endodontic disinfection, the prolonged contact time required to achieve effective bacterial killing and the toxicity issues in silver NPs impose significant drawbacks. Newer nanoparticles formulations as well as other technologies (such as photodynamic therapy) have been reported to enhance biofilm elimination [11, 12]. Previously our team has a rich experience in working on various research projects across multiple disciplines [13-27] Now the growing trend in this area motivated us to pursue this project.

The effect of Nanoparticles based root canal disinfectants on Enterococcus faecalis is evaluated in the current systematic review.

Structured Question

Does Nanoparticle based root canal disinfectants have any effect on the reduction of Enterococcus faecalis in the root canal system?

PICOS Analysis

Population- Inoculated root canals, Extracted teeth with microbial species, Cell culture plates

Intervention- Nanoparticles based root canal disinfectants (Irrigants / Intracanal Medicaments)

Comparison- Treatment with commonly used irrigants/ intracanal medicaments

Outcome- Eradication of Enterococcus faecalis bacterial load Study Design- All experimental studies, randomized controlled studies, In vitro, In vivo and ex-vivo studies

Null Hypothesis

There is no significant difference in the reduction of Enterococcus faecalis in the root canal system between nanoparticles based root canal disinfectants and other antimicrobial agents.

Alternate Hypothesis

There is a significant difference in the reduction of Enterococcus faecalis in the root canal system between nanoparticles based root canal disinfectants and other antimicrobial agents.

Materials And Methods

Sources Used

For identification of studies included or considered for this review, detailed search strategies were developed for the database searched. The MEDLINE search used the combination of controlled vocabulary and free text terms.

Searched Databases:

PUBMED

PUBMED Advanced Search

SCIENCE DIRECT

Cochrane Database of Systematic Review

Google Scholar

Language

There were no language restrictions

Hand Search

The following journals were hand searched:-

Journal of Research in Medical and Dental Science

Journal of Nanomaterials

Journal of Conservative Dentistry

Iranian Endodontic Journal

Indian Journal of Dental Research

Inclusion Criteria

Criteria For Considering Studies In This Review:-

In vitro studies assessing the efficacy of nanoparticles based root canal disinfectants against Enterococcus faecalis. In vivo studies assessing the efficacy of nanoparticles based root canal disinfectants on reduction of Enterococcus faecalis. Studies evaluating elimination or reduction of bacteria from root canal system.

Randomized controlled studies

Exclusion Criteria

The Following Studies Were Excluded:-

Studies evaluating the effect of nanoparticles in bovine & animal studies.

Studies in which comparison between nanoparticle based root canal disinfectant & commonly used disinfectant was not done. Studies in which reduction in Enterococcus faecalis microbial load was not evaluated.

Characteristics Of Excluded Studies

A total of 439 studies were excluded from the electronic search owing to the irrelevance. Animal studies and the studies that showed the effect of nanoparticles based root canal disinfectants against oral microorganisms other than oral origin were excluded. A total of 9 articles have been included [Table 2].

Results

Description of Studies

The search identified 448 publications out of which 437 were excluded after reviewing the title/ abstract and 2 were excluded after reviewing the full articles. A total of 9 publications that fulfilled all criteria for inclusion were selected.

Quality Assessment

The quality assessment of included trials was undertaken independently as a part of the data extraction process. Four main quality criteria were examined:

1. Method of Randomization, recorded as

a. Yes - Adequate as described in the text
b. No - Inadequate as described in the text
c. Unclear in the text

2. Allocation Concealment, recorded as

a. Yes - Adequate as described in the text
b. No - Inadequate as described in the text
c. Unclear in the text

3. Outcome assessors blinded to intervention, recorded as

a. Yes - Adequate as described in the text
b. No - Inadequate as described in the text
c. Unclear in the text

4. Completeness of follow- up (was there a clear explanation for withdrawals and dropouts in each treatment group) assessed as:

a. Yes - Dropouts were explained
b. No - Dropouts were not explained
c. None- No dropouts or withdrawals

Other methodological criteria examined included:

1. Presence or absence of sample size calculation
2. Comparability of groups at the start
3. Clear inclusion/ exclusion criteria
Presence/absence of estimate of measurement error. The validity and reproducibility of the method of assessment.
Risk of Bias in Included Studies

The assessments for the four main methodological quality items are shown in table. The study was assessed to have a ‘’ High risk’’ of bias if it did not record a ‘’Yes’’ in three or more of the four main categories, ‘’ Moderate ‘’ if two out of four categories did not record a ‘’ Yes’’, and ‘’ Low’’ if randomization assessor blinding and completeness of follow - up were considered adequate.

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Table 1:

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Table 1. Response given by 3rd years , 4th years, Interns.

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Table 2:

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Table 2. Response given by 3rd years , 4th years, Interns.

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Table 3:

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Table 3. Response given by 3rd years , 4th years, Interns.

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Table 4:

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Table 4. Response given by 3rd years , 4th years, Interns.

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Table 5:

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Table 5. Response given by 3rd years , 4th years, Interns.

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Figure 1:

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Figure 1. Representing the Search Flow chart.

Discussion

Interpretation Of Results

The purpose of this systematic review was to evaluate the efficacy of nanoparticles based root canal disinfectants against Enterococcus faecalis. Eleven in vitro studies fulfilled the criteria for being included in this review.

No in vivo studies are reported in the literature. Thus, this Systematic Review reported only in- vitro studies.

[28] conducted a study where they evaluated antimicrobial efficacy of silver (Ag Np) and gold nanoparticles ( Au Np) with and without Nd: YAG laser ( L) irradiation against inoculated enterococcus faecalis in infected human root dentin. The result has shown that the application of Nd:YAG laser in combination with silver nanoparticles irrigation had shown significant effects in the reduction of microbial colonies of enterococcus faecalis when compared to other groups. There was no significant difference between Au + Nd: YAG laser & CHX.

[29] conducted a study to evaluate the efficacy of nanosilver (NS) solution as an endodontic irrigation solution of primary teeth against enterococcus faecalis with colony forming unit test and found that the sodium hypochlorite showed the highest antimicrobial effectiveness against E. faecalis when compared with normal saline and NS solution.

[30], tested the efficacy of iron oxide nanoparticles against E. faecalis and compared with 3% H2O2, Io-Np’s, Io-Np’s + 3% H2O2, 3% NaoCl and 2% CHX. It has shown that the IO-NP’s/ H2O2 was significantly better & shows better antibacterial activity when compared to conventional irrigants.

In a study conducted by [31] used MB- loaded PLGA (Poly lacticco- glycolic acid) nanoparticles for evaluation of in vitro against E. faecalis. It has also shown that the photodynamic effects of the nanoparticles play an important role against E. faecalis. Hence, concluded that the utilization of PLGA nanoparticles with photodynamic therapy can be used as an adjunct in antimicrobial endodontic treatment.

Aseel Haidar MJ AL- Haidar conducted a study wherein he investigated the antibacterial effect of silver nanoparticles, sodium hypochlorite & chlorhexidine in reducing the bacterial infection of the root canals by colony forming unit. AgNP’s proved to be as effective as NaOCl & CHX in terms of antibacterial action. [32] conducted a study to determine the bactericidal effect of silver nanoparticles as a final irrigation used in endodontics when compared with the sodium hypochlorite solution, silver nanoparticles + EDTA and saline solution.Silver nanoparticles as an endodontic irrigant can be used against E.faecalis as it shows same effect with 2.25% NaOCl. In a study conducted by [33] he compared the antibacterial effects of silver nanoparticle gel alone & in combination of silver nanoparticle gel with various medicaments by using agar diffusion test. It has found that when silver nanoparticles were combined with CaOH & CHX, the antibacterial activity was enhanced.

[34], compared the antibacterial effects of two gels containing Zinc oxide & Zinc oxide ( Silver nanoparticles & a mixture of calcium hydroxide , 0.12 % CHX as an intracanal medicament in root canals which was contaminated with E. faecalis. It has shown that the mixture of calcium hydroxide / CHX was effective against E.faecalis &show better antibacterial effect as compared to other groups. Addition of silver nanoparticles to ZnO did not reduce the bacterial count.

[35] compared the efficacy of silver & zinc oxide nanoparticles with conventional endodontic irrigants against E. faecalis biofilm in root canals tested by using colony forming unit analysis & SEM and found that the 1% AgNp + 26% ZnO nanoparticles were as effective as conventional endodontic irrigants against E. faecalis. Our institution is passionate about high quality evidence based research and has excelled in various fields [17, 36-45]. Out of 11 studies included in this systematic review, 4 studies showed that nanoparticles based disinfectants were better in eradicating Enterococcus faecalis as compared to the commonly used disinfectants. 1 study showed that there is no significant difference between nanoparticle based disinfectant and commonly used disinfectants. 4 studies showed that the combination of nanoparticles with other agents was effective and showed a significant difference. Studies by Samiei et.al, Moradi & Haghgoo et.al showed that commonly used disinfectants were better than the nanoparticles.

Meta- analysis

Mostly systematic reviews will perform meta analysis, which involves the statistical pooling of data from individual studies when the studies are similar. A meta - analysis can yield a more precise overall estimate of the treatment effect. However, meta- analysis may not be appropriate in many situations. Owing to the heterogeneity among the studies, we could not perform a meta- analysis to summarize the data of included articles. Hence, only descriptive evaluation of data has been provided.

Quality of Evidence

All the studies included in this review have a level of evidence 5. All are in vitro studies, thus the level of evidence is low.

Implications for practice

Nanoparticles based root canal disinfectants can be used as an antimicrobial agent either solely or in combination with other disinfectants for root canal treatment.

Implications for Research

In future, research should be aimed at utilizing this nanoparticles based root canal disinfectants in animal and human populations to exert its associations with other products.

Conclusion

Nanoparticles based root canal disinfectants can be considered as an alternative disinfectant or can be combined with other disinfectants to exert antimicrobial effect. However, no clinical trials exist on the topic; randomized controlled trials need to be performed to extrapolate the results to the clinical scenario.

Acknowledgement And Declarations

The authors would like to acknowledge the institution and all the staff members of the Department of Conservative Dentistry and Endodontics for their support towards completion of this research. The authors deny any conflicts of interest associated with this paper.