Effect of different final irrigating solutions on smear layer removal in apical third of root canal: A scanning electron microscope study

Comparative evaluation of effect of nisin-incorporated ethylenediamine tetraacetic acid and MTAD on endodontic biofilm eradication, smear layer removal, and depth of sealer penetration

OBJECTIVES

To comparatively evaluate the nisin-incorporated ethylenediamine tetraacetic acid (N-EDTA) and MTAD on cytotoxicity, endodontic biofilm eradication potential, smear layer removal ability, and sealer penetration depth.

MATERIALS AND METHODS

N-EDTA was prepared and characterized using high-performance liquid chromatography (HPLC). Minimum inhibitory, minimum bactericidal, and minimum biofilm inhibitory concentration (MBC, MIC, and MBIC) were determined on Enterococcus faecalis (E. faecalis) strain. The cytocompatibility of N-EDTA and MTAD was evaluated using 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based colorimetric assay. Dentin specimens (n = 88 for antibacterial analysis, n = 170 for sealer penetration depth) were prepared and subjected to the classical irrigating strategy and obturation, respectively. The scanning electron microscopic evaluation (SEM) was done for the evaluation of biofilm disruption and smear layer removal. Confocal laser scanning microscopy (CLSM) evaluation was done for determining percentage of bacterial viability and sealer penetration depth. Statistical analysis of one-way ANOVA and Tukey's HSD post hoc tests for bacterial viability and Kruskal-Wallis test and Mann-Whitney test for smear layer removal and depth of penetration were done with the significance level set at p < 0.05.

RESULTS

MTAD and N-EDTA showed cytocompatibility without any statistical differences from each other. For N-EDTA, the MIC and MBC values were 12.5 μg/ml (1:8), and MBIC values were 36 μg/ml. Biofilm disruption and killed bacterial percentage of N-EDTA was statistically higher than MTAD, whereas both the materials showed similar efficacy in the removal of the smear layer and sealer penetration depth.

CONCLUSION

N-EDTA had negligible cytotoxicity with similar smear layer removal ability, sealer penetration, and better antibiofilm potential than MTAD.

CLINICAL RELEVANCE

N-EDTA can serve as a viable alternative endodontic irrigant.

Comparison of smear layer removing efficacy of Cold Atmospheric Pressure (CAP) Plasma Jet with different chelating agents. An ex-vivo study

The present study aimed to assess the effectiveness of different final irrigation regimens (Cold Atmospheric Pressure Plasma Jet, MTAD, and EDTA) in removing the smear layer from intra-radicular dentin using a Scanning Electron Microscope (SEM). Eighty-four mandibular premolars were prepared with ProTaper Universal hand files and were equally divided into four groups i.e. Normal saline (control), EDTA, MTAD and CAP Plasma Jet. Prepared samples in the control, EDTA and MTAD groups were irrigated with 5 milliliters of the irrigant, and it was retained for 2 min. In the CAP Plasma Jet group, the plasma plume was directed towards the canal lumen for 2 min. The smear layer removal of all the groups was evaluated at the coronal, middle and apical thirds. Statistical analysis was performed using Kruskal-Wallis test followed by Dunn's test. Evaluation by SEM showed that the smear layer removal ability of MTAD and EDTA were significantly better than CAP Plasma Jet (p < 0.05). While CAP Plasma Jet showed results comparable to EDTA in the coronal third. In the middle and apical third of the canal, its effect was comparable to the control group (p > 0.05). MTAD and EDTA aided in better smear layer removal than the CAP Plasma Jet in the coronal, middle, and apical third of the test samples. CAP Plasma jet performed better in the coronal third.

Quantitative assessment of transforming growth factor-β1 release from dentin matrix upon conditioning with ethylene diamine tetra-acetate, doxycycline hydrochloride, and propolis: An in vitro study

Background

Transforming growth factor-beta 1 (TGF-β1) is a key morphogen in regenerative endodontics that plays a central role in regulating cellular functions. Various chelating agents have been shown to release this growth factor upon conditioning. The objective of the study was to evaluate TGF-β1 release from the dentin matrix upon conditioning with ethylene diamine tetra-acetate (EDTA), doxycycline hydrochloride, and propolis.

Materials and Methods

Forty-two human 3rd molar teeth were collected and coronal portion of the teeth was sectioned to obtain dentin blocks with dimensions 2 mm × 2 mm × 2 mm. The blocks were then randomly divided into three groups depending on the conditioning agent used; Group 1: 17% EDTA, Group 2: doxycycline hydrochloride (100 mg/mL), and Group 3: propolis (250 μg/mL). Conditioned blocks were placed in 0.5 mL of phosphate buffered saline and incubated for 1 week for quantification.

Results

Highest TGF-β1 release was noted for propolis (0.21 ng/mL), followed by doxycycline hydrochloride (0.18 ng/mL) and 17% EDTA (0.14 ng/mL).

Conclusion

Doxycycline hydrochloride and propolis significantly enhanced the release of TGF-β1 from the dentin matrix compared to EDTA (P < 0.05). No significant difference was observed between doxycycline hydrochloride and propolis (P > 0.05). Doxycycline and propolis can be used as effective alternatives to EDTA during regenerative endodontic procedures.

Scanning Electron Microscopy Analysis of Smear Layer Removal Ability of Conventional Endodontic Irrigation Regimen, MTAD, and QMix™ Versus a Mixture of Azadirachta indica and Citrus limon: An In Vitro Study

INTRODUCTION

Smear layer removal from root canals aid in the penetration of both irrigants and endodontic sealer into the dentinal tubules, thereby improving the efficacy of endodontic treatment. The aim of this in vitro study was to compare the smear layer removal ability of a conventional endodontic irrigation regimen, MTAD (mixture of tetracycline, acid, and detergent), and QMix™ (Dentsply Sirona, Charlotte, North Carolina, United States) with that of a mixture of herbal irrigants, namely, aqueous extracts of Azadirachta indica (neem) and Citrus limon (lemon), evaluated using scanning electron microscopy (SEM).

MATERIALS AND METHODS

We selected 40 extracted human premolar teeth for the study, which we randomly divided into five groups (eight samples each) according to irrigation solution: (i) Group A (normal saline); (ii) Group B (conventional endodontic regimen, 3% sodium hypochlorite (NaOCl) + 17% ethylenediamine tetraacetic acid (EDTA) + 2% chlorhexidine (CHX)); (iii) Group C (MTAD); (iv) Group D (QMix 2-in-1); and (v) Group E (aqueous extracts of Azadirachta indica and Citrus limon). After we prepared the canals with ProTaper Universal nickel-titanium (Ni-Ti) rotary files (Dentsply Sirona) and the respective irrigants, we split the teeth longitudinally to evaluate the amount of remnant smear layer in the coronal, middle, and apical thirds using SEM photomicrographs. We performed statistical analyses of the data using the Kruskal-Wallis and Mann-Whitney U tests, where the level of significance was set at 0.05.

RESULTS

The SEM analysis of the coronal third showed mean values of 3.83 in Group A, 3.67 in Group B, 2.79 in Group C, 3.63 in Group D, and 4.00 in Group E. The SEM analysis of the middle third showed mean values of 4.00 in Group A, 3.88 in Group B, 3.75 in Group C, 3.50 in Group D, and 3.50 in Group E. The SEM analysis of the apical third showed mean values of 3.92 in Group A, 3.63 in Group B, 3.71 in Group C, 3.88 in Group D, and 3.17 in Group E. Therefore, we found that there were significant statistical differences between the groups when an overall comparison was done for the coronal, middle, and apical third, with a p-value of 0.001. On multiple comparisons across the different tooth-section thirds. Groups A and B showed statistically significant differences in the apical third (p-value=0.017). Groups A and C showed statistically significant differences in the coronal third and middle third (p-values=0.001 and 0.010, respectively). Groups A and D showed statistically significant differences in the middle third (p-value=0.001). Groups A and E showed statistically significant differences in all thirds (p-values=0.039, 0.001, and 0.001, respectively) Conclusion: The conventional needle irrigation with MTAD showed the highest level of smear layer removal ability on the root canal surface, followed by QMix 2-in-1, the Azadirachta indica leaf and Citrus limon extract mixture, and the conventional endodontic regimen. Normal saline showed the lowest smear layer removal effect.

Comparative Evaluation of Intracanal Smear Layer Removal by Different Root Canal Irrigants: A Scanning Electron Microscope Study

Aim

The purpose of the study is to compare and evaluate the efficacy of different root canal irrigants-100, 75, 50, and 25% neem extract, 100, 75, 50, and 25% apple cider vinegar (ACV), a combination of 5.25% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), and saline on smear layer removal using a scanning electron microscope (SEM).

Materials and methods

A total of 80 freshly extracted single-rooted teeth were collected and divided into 10 groups-group I: normal saline (negative control), group II: NaOCl with EDTA (positive control), group III: 100% neem extract, group IV: 75% neem extract, group V: 50% neem extract, group VI: 25% neem extract, group VII: 100% ACV, group VIII: 75% ACV, group IX: 50% ACV, and group X: 25% ACV. The samples were irrigated with a specific group of irrigants, then split in a longitudinal axis and processed for analysis in an SEM. Microphotographs were obtained and scored according to Torabinejad et al.

Results

Microphotographs were assessed and showed that 100% neem extract was similar to NaOCl with EDTA, followed by 75% neem extract and 100% ACV.

Conclusion

This study showed that 100% neem extract removed the smear layer, similar to the NaOCl with EDTA.

How to cite this article

Sudhakar S, Gupta N, Ghambir N, et al. Comparative Evaluation of Intracanal Smear Layer Removal by Different Root Canal Irrigants: A Scanning Electron Microscope Study. Int J Clin Pediatr Dent 2023;16(4):633-638.

Evolution of the combined effect of different irrigation solutions and activation techniques on the removal of smear layer and dentin microhardness in oval-shaped root canal: An in-vitro study

The aim of this in vitro study was to evaluate the effect of three final irrigants, namely QMix, MTAD and EDTA, combined with three irrigation techniques, namely conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI) and photon-induced photoacoustic streaming (PIPS), on smear layer removal, dentin mineral content and microhardness in oval-shaped canals.    130 decoronated premolars with single, oval root canals were equally divided into1 blank control group and 12 treatment groups (n=10) according to the final irrigation protocols. Roots in treatment groups were instrumented with ProTaper Gold to size F4 and subjected to final irrigation. Smear layer removal was assessed by using a four-level scoring system under an environmental scanning electron microscope. Energy dispersive X-ray spectroscopy was performed to measure the dentin mineral content. Dentin microhardness was measured by Knoop microhardness testing. Statistical analysis of the data was performed by using Kruskal-Wallis test, followed by Dunn's post hoc test with Bonferroni correction. PUI- and PIPS-activated QMix and EDTA removed smear layer more effectively than MTAD groups (p<0.05). Regarding the dentin mineral content and microhardness, QMix groups yielded the least calcium (Ca), phosphorus (P)  and Ca/P ratio, followed by EDTA groups and MTAD groups (p<0.05). QMix groups produced significantly lower dentin microhardness values and higher hardness reduction percentages than MTAD groups (p<0.05).  Within the limitations of the present study, it was concluded that QMix and EDTA were superior to MTAD in smear layer removal, especially when activated by PUI and PIPS, but these agents produced more pronounced effect on dentin mineral content and microhardness than MTAD.

Influence of chelating solutions on tubular dentin sealer penetration: A systematic review with network meta-analysis

This systematic review assessed the influence of conventional final irrigation with chelating solutions (CS) on tubular dentin sealer penetration (TDSP). The literature search was conducted in eight electronic databases using MeSH, DeCS, EMTREE and free terms. The study protocol followed the PRISMA guidelines and was registered on the PROSPERO database (CRD42020203080). Twelve studies were included, and a qualitative synthesis and network meta-analysis of the data were performed. The risk of bias of the studies was assessed using an adaptation of the JBI Critical Appraisal tool. QMix was the solution with the highest probability of having the highest percentage of TDSP in the apical (34.1%), middle (86.5%) and coronal (97.7%) thirds. Eleven studies presented a moderate risk of bias, whereas one study presented a high risk of bias. In conclusion, CS improves sealer penetration into the dentinal tubules with QMix demonstrating superior results.

An Overview on a Promising Root Canal Irrigation Solution: QMix

Due to the complex micro-anatomy of the root canal system, mechanical instrumentation leaves significant portions of the root canal walls untouched; therefore, complete elimination of bacteria from the root canal by cleaning with instrumentation alone is unlikely. It has long been postulated but not demonstrated, that any pulp tissue left in the root canals can serve as bacterial/fungal/viral (microorganism nutrients) nutrients. Furthermore, tissue remnants also impede the antimicrobial effects of root canal irrigants and medicaments and prevent intimate adaptation of the root canal filling to the dentin. Therefore, specific irrigation/disinfection procedures are necessary to remove tissue from the root canals and to kill microorganisms, respectively. The purpose of this paper was to review different aspects of a promising root canal irrigant; QMix. This is a relatively new root canal irrigant composed of traditional materials like chlorhexidine (CHX), ethylele diamine tetraacetic acid (EDTA), saline and a detergent. QMix is antibacterial, antifungal and has antibiofilm activities, it displays substantivity, smear layer removing ability; moreover, its effect on dentin and retention of fiber posts etc. has been reviewed. There have been strong reports that show the chemical design of QMix prevents precipitation of CHX when together with EDTA and mixing with sodium hypochlorite does not produce the orange-brown precipitate. Furthermore, the smear layer removal ability of QMix is comparable to that of 17% EDTA and the antibacterial activity of QMix was greater than 1% and 2% sodium hypochlorite (NaOCl) and 2% CHX.

The effect of 17% EDTA and QMiX ultrasonic activation on smear layer removal and sealer penetration: ex vivo study

This study aimed to compare the effect of conventional irrigation (CI) and passive ultrasonic irrigation (PUI) with 17% EDTA and QMiX on the maximum depth and percentage of sealer penetration into the dentinal tubules by confocal laser scanning microscopy (CLSM) and to describe the cleaning of root canal walls by scanning electron microscopy (SEM). Eighty single-rooted human mandibular premolars were instrumented and randomly assigned to four groups (n = 20): EDTA + CI, QMiX + CI, EDTA + PUI, and QMiX + PUI. Ten samples from each group were examined by SEM (2,000×) and the remaining 40 roots were filled with a single gutta-percha cone and AH Plus sealer mixed with 0.1% rhodamine B for analysis by CLSM (10×). Images were assessed at distances of 2 mm (apical), 5 mm (middle), and 8 mm (coronal) from the apex with the Leica Application Suite V4.10 software. The EDTA + PUI and QMiX + PUI protocols presented higher rates of debris/smear layer removal in the apical and middle thirds. The PUI was superior to CI in the maximum depth of sealer penetration at the middle third. The QMiX + PUI group had a higher percentage of sealer penetration at the apical third. The PUI and QMiX protocol improved debris/smear layer removal and tubular dentin sealer penetration.

Removal of the root canal smear layer using Carisolv III and sodium hypochlorite

The present study investigated the effectiveness of a Carisolv III + 0.5% sodium hypochlorite (NaOCl)-based root canal irrigant for smear layer removal.Forty maxillary incisors were randomly divided into 4 groups (n = 10 per group). The canals in group A (experimental) were prepared with 0.5% NaOCl, and Carisolv III and 0.5% NaOCl was used for the final washing; groups B and C (positive controls) used 2% and 5.25% NaOCl, respectively; and group D (negative control) used phosphate-buffered saline (PBS). Ethylenediaminetetraacetic acid (EDTA) was used for all of the groups. A 5-point scoring scale and scanning electron microscopy were used to evaluate the effectiveness of the irrigants. The canals were consistently cleaner in the coronal and middle thirds than in the apical thirds (P < .05).For cleaning the root canals, 5.25% NaOCl was more effective than 2% NaOCl, 0.5% NaOCl + Carisolv III, and phosphate-buffered saline , respectively (P < .05). The 2% NaOCl solution showed similar results to 0.5% NaOCl + Carisolv III (P > .05). The combination of 5.25% NaOCl and 17% EDTA remains the most effective irrigant for removal of the root canal smear layer.A combination of Carisolv III + 0.5% NaOCl (with 17% EDTA) showed a cleaning ability similar to that of 2% NaOCl (with 17% EDTA).

Effect of QMix irrigant in removal of smear layer in root canal system: a systematic review of in vitro studies

Objectives

To evaluate the outcome of in vitro studies comparing the effectiveness of QMix irrigant in removing the smear layer in the root canal system compared with other irrigants.

Materials and Methods

The research question was developed by using Population, Intervention, Comparison, Outcome and Study design framework. Literature search was performed using 3 electronic databases PubMed, Scopus, and EBSCOhost until October 2019. Two reviewers were independently involved in the selection of the articles and data extraction process. Risk of bias of the studies was independently appraised using revised Cochrane Risk of Bias tool (RoB 2.0) based on 5 domains.

Results

Thirteen studies fulfilled the selection criteria. The overall risk of bias was moderate. QMix was found to have better smear layer removal ability than mixture of tetracycline isonomer, an acid and a detergent (MTAD), sodium hypochlorite (NaOCl), and phytic acid. The efficacy was less effective than 7% maleic acid and 10% citric acid. No conclusive results could be drawn between QMix and 17% ethylenediaminetetraacetic acid due to conflicting results. QMix was more effective when used for 3 minutes than 1 minute.

Conclusions

QMix has better smear layer removal ability compared to MTAD, NaOCl, Tubulicid Plus, and Phytic acid. In order to remove the smear layer more effectively with QMix, it is recommended to use it for a longer duration.

Effectiveness of Sodium Hypochlorite plus EDTA Compared with Peracetic Acid in Removing Smear Layer and Killing Enterococcus faecalis

Introduction

The aim of this study was to evaluate the effectiveness of 2.5% sodium hypochlorite associated with 17% Ethylenediaminetetraacetic acid (NaOCl-EDTA), versus that of 1% peracetic acid (PA), in removing the smear layer, as assessed by scanning electron microscopy (SEM), and in exerting bactericidal action against Enterococcus faecalis (E. faecalis ) , as assessed by the real-time polymerase chain reaction (real-time PCR).

Methods and Materials

Fifty-five extracted mandibular single-rooted premolars were selected, and divided into two experimental groups (NaOCl-EDTA and PA; n=25) and one control group (0.9% saline; n=5). Pre- and post-instrumentation samples were collected and assessed for the presence of E. faecalis using real-time PCR. The teeth were instrumented using hand files and the ProTaper Universal system (hybrid technique) for a standardized time of 7 min. A total of 20 mL of NaOCl followed by 5 mL of EDTA were applied during instrumentation in the NaOCl-EDTA group, whereas 20 mL of PA and 20 mL of saline were applied in the PA and control groups, respectively. An additional 5 mL of saline was applied in all the groups to neutralize the environment. A scoring system was used to conduct the SEM assessment. The results were submitted to the Kruskal-Wallis test, complemented by Dunn's test (SEM analysis) (P<0.05).

Results

A significant microbial reduction was observed in both the PA and the NaOCl-EDTA groups (P<0.05). In the PA group, the presence of a smear layer in the apical third was significantly greater than in the cervical third (P<0.05); no significant differences were observed between the middle and cervical thirds, or between the middle and apical thirds (P>0.05). In the NaOCl-EDTA group, the smear layer scores were significantly higher in the apical third than in the cervical and middle thirds (P<0.05).

Conclusion

This in vitro study showed that there was no significant difference between PA and NaOCl-EDTA irrigation regimens regarding either antimicrobial action against E. faecalis or removal of the smear layer, except for greater removal in the middle third by the NaOCl-EDTA group.

Cleaning Efficacy of Root Canal Irrigation with Positive and Negative Pressure System

Introduction:

The purpose of this study was to analyze the differences between irrigant replacement in the positive and negative pressure irrigation systems regarding root canal cleaning efficacy.

Methods and Materials:

A total of 27 extracted single-root mandibular premolars with 18-20 mm root canal length were decoronated and equally divided into three groups (n=9) based on the irrigation system used: positive irrigation with side-vented needle as the control group (C), positive irrigation with an open-ended needle as the first group (T1) and negative irrigation as the second group (T2). The root canals were irrigated with 2.5% NaOCl between each instrumentation, followed by a final irrigation with 5 mL of sterile distilled water. The irrigation replacements were monitored by means of computational fluid dynamic (CFD), while a scanning electrone microscope (SEM) was used to observe the smear layers and plug evaluations after the teeth had been sectioned longitudinally and buccolingually halves subsequently cut in apical third area. The result was analyzed using the Kruskal Wallis, Mann Whitney and Spearman correlation tests. The level of significance was set at 0.05.

Result:

Irrigant replacement in the negative pressure irrigation system tends to produce a greater effect in reaching the apical end compared to in the positive pressure irrigation system. This resulted in significantly superior smear layer removal in the apical third area (P<0.05).

Conclusion:

The irrigation solution exchange of the negative pressure irrigation system is more capable of reaching the apical end compared to the positive pressure irrigation system, resulting in a higher sanitation level in the apical third of the root canal.

Effectiveness of Three Different Irrigants - 17% Ethylenediaminetetraacetic Acid, Q-MIX, and Phytic Acid in Smear Layer Removal: A Comparative Scanning Electron Microscope Study

Background:

Removal of smear layer from the root canal walls is important for long-standing endodontic success.

Aim:

The aim of this study is to evaluate and compare smear layer removing ability among 17% ethylenediaminetetraacetic acid (EDTA), Q-MIX, and phytic acid by scanning electron microscopy (SEM).

Materials and Methods:

This in-vitro experimental study assessed smear layer removal using three different irrigants. Thirty single-rooted freshly extracted human permanent premolars were collected, disinfected, and decoronated to a standardized root length of 13 mm. Root canals were cleaned and shaped till F2 universal rotary protaper at working length 1 mm short of the apex. They were randomly divided into three groups, and final irrigation was done accordingly. Group 1 (n = 10): with 1 ml of 17% EDTA, Group 2 (n = 10): with 1 ml of Q-MIX, Group 3 (n = 10): with 1 ml of phytic acid. Samples were then longitudinally sectioned and evaluated under SEM at coronal, middle, and apical levels.

Statistical Analysis:

Two-way analysis of variance and Tukey's post hoc test were performed. The level of significance was set at 0.05.

Results:

Smear layer removing ability among irrigants and sections in descending order: 17 EDTA > Q-MIX > phytic acid; coronal > middle > apical.

Conclusion:

17% EDTA showed better and promising results followed by Q-MIX and then phytic acid.

[Research progress on QMix properties in root canal irrigation]

Mechanical instrumentation preparation alone is insufficient to completely remove root canal infection, and chemical irrigation is essential to eliminate infected remnants. An ideal root canal irrigant should completely remove the smear layer, lubricate the root canal, efficiently kill bacteria, induce mild or no inflammatory response in the tissues, and avoid damaging the dentin structure. However, a commercial irrigant that meets all these requirements is currently lacking. QMix is a root canal irrigation mixture of ethylenediamine tetraacetic acid (EDTA), chlorhexidine (CHX) and surfactant. This mixture can remove the smear layer efficiently, and it possesses strong antibacterial effect and good biocompatibility with minimal cytotoxicity. Furthermore, the influence of QMix on the color and micro-hardness of dentin is low, and it can improve the wettability of root canal sealant without affecting its adhesive properties. This review compares the efficiencies of QMix with other irrigants (sodium hypochlorite, CHX, EDTA, SmearClear, and MTAD) in term of smear layer removal, dentine and root canal sealing, cell cytotoxicity, and bacterial growth inhibition.