A preliminary scanning electron microscopic study of root canals after endodontic procedures

Recent innovations in endodontic irrigation and effects on smear layer removal: an ex-vivo study

OBJECTIVES

To evaluate the cleaning efficacy of different irrigation activation techniques in removing smear layers from root canals.

MATERIALS AND METHODS

Ninety lower premolars with straight root canals were assigned to six experimental groups (n = 15 each): control group, conventional irrigation, passive ultrasonic activation (PUI), distilled water laser-activated irrigation (LAI), PulpSucker irrigation, and iVac irrigation. Each canal was shaped to size 30/04 and irrigated with 5% NaOCl. The final rinse was performed according to the experimental group. After chemo-mechanical procedures, the teeth were split longitudinally and subjected to scanning electron microscopic (SEM) analysis for each root canal third (coronal, middle, and apical). The presence of smear layer was evaluated using a 5-grade scoring system at 500× and 1000× magnification. Following the Shapiro-Wilk test, data were statistically analyzed using the nonparametric Kruskal-Wallis test, followed by the post-hoc Dunn test with Bonferroni correction (α = 5%), to compare the effectiveness of smear layer removal. The Friedman test and post-hoc Wilcoxon signed-rank test with Bonferroni correction (α = 5%) were performed to assess significant differences in smear layer removal among the different tooth thirds.

RESULTS

Activated irrigation techniques significantly outperformed conventional irrigation (p <.05), with the iVac technique demonstrating the best results in smear layer removal in the apical third. LAI and PUI showed comparable results across all tooth thirds. Significant differences in cleaning efficacy were observed among the different tooth thirds within each experimental group, with the apical third exhibiting the highest presence of smear layer.

CONCLUSION

Within the limitations of the study, irrigant activation demonstrated higher efficiency in smear layer removal from root canal systems compared to conventional irrigation techniques. iVac showed the best cleaning performance in each third, particularly in the apical third.

CLINICAL RELEVANCE

iVac technology offers significant potential for improving clinical outcomes.

Scanning Electron Microscopy analysis concerning the effect of 980 nm Diode Laser and Twin Kleen irrigant for the elimination of smear layer off the root canal wall

OBJECTIVE

The present research aims to examine the effectiveness of 980 nm Diode Laser and Twin Kleen irrigant individually in addition to the combo for removing the smear layer from tooth canals in single-rooted teeth.

MATERIALS AND METHODS

60 single-rooted mandibular premolar teeth were chosen and inspected clinically and by radiography. Protaper was employed to prepare teeth up to F4. Irrigation with 5.25% sodium hypochlorite followed each consecutive instrument. The collected, prepared teeth were distributed at random to four distinct groups of fifteen teeth each: (a) Group I: Normal saline; (b) Group II: Twin Kleen; (c) Group III: Diode Laser; (d) Group IV: Diode Laser in combo with Twin Kleen. Scanning Electron Microscope evaluation was performed. The topography of the surfaces of the 4 groups was studied, and the results were photographed. Microscopy images captured under 1000x. Using the Guttman grading methodology, the smear layer scores have been determined in the cervical, mid and apical root areas.

RESULTS

Smear layer removal scores in the cervical area were least in Group III and highest in Group I. Smear layer removal scores in the middle area were least in Group III and highest in Group I. Smear layer removal scores in the apical area were least in Group IV and highest in Group I.

CONCLUSION

It is determined that the diode laser, in combination with Twin Kleen, improves smear layer elimination, particularly from the apical region. 980 nm diode laser can be employed as an irrigant activating technique that allows for improved absorption into restricted root canal locations.

The Effectiveness of Triton Used With XP-3D Adaptive Files and Active Irrigation on Smear Layer Removal During Root Canal Preparation: A Qualitative Scanning Electron Microscopy (SEM) Study

BACKGROUND

Standard irrigating protocols during root canal treatment call for the use of sodium hypochlorite during chemo-mechanical preparation, followed by final irrigation with ethylenediaminetetraacetic acid (EDTA). This study determined the effectiveness of a new irrigant, Triton (Brasseler, USA), on smear layer removal during root canal treatment compared to that of 5.25% sodium hypochlorite and CanalPro EDTA 17% (Coltene).

METHODOLOGY

Twenty-one extracted anterior teeth were prepared for root canal treatment. The teeth were divided into three groups: five teeth were used as control with saline as the irrigant, eight teeth with sodium hypochlorite and 17% EDTA as irrigants, and eight teeth with Triton as the irrigant. Root canal preparation was done using the XP-3D shaper and finisher files (Brasseler, USA) for all teeth with respective irrigants. A single operator performed all root canal treatment procedures. The teeth were prepared for scanning electron microscopy (SEM), and analysis was performed by a second investigator. The smear layer removal was qualitatively assessed to determine the effectiveness of irrigants.

RESULTS

Smear layer removal was most effective for teeth irrigated with 5.25% sodium hypochlorite, followed by 17% EDTA (Group B). Teeth irrigated with Triton (Group A) showed a similar appearance to the hypochlorite/EDTA group but with isolated instances of inter-tubular debris.

CONCLUSION

Sodium hypochlorite use followed by a final rinse with EDTA remains the gold standard for the removal of the smear layer created during canal instrumentation.

Comparison of Debridement Efficacy of Two Irrigating Systems Endovac and Conventional Needle in Primary Tooth Root Canals: An In Vitro Study

Aim

The purpose of the study is to evaluate how well the Endovac system and conventional needle irrigation work to remove smear layers (SR) from primary teeth root canals.

Materials and methods

Fifty extracted human primary teeth were divided into two equal sections vertically, then positioned within an acrylic model that was secured with screws. Group A (Endovac), n = 25, and group B (traditional needle), n = 25. Next, a uniform irrigation technique was used in every tooth embedded in the study model. Sections were examined with a 100× magnification stereomicroscope and electron microscope. Statistical tests were used to analyze the data.

Results

Endovac removed the SR from the apical third of the root canal system more successfully than a traditional needle (<0.05).

Conclusion

Endovac has better performance than conventional needle irrigation in the removal of the SR in the deciduous teeth root canal system.

Clinical significance

(1) Removing the SR allows for more cleaning and disinfecting of root canal walls and better adaptation of root canal filling materials. (2) It is essential to remove the entire SR from the root dentin for successful endodontic treatment.

How to cite this article

Yadav P, Virdi MS, Saini C. Comparison of Debridement Efficacy of Two Irrigating Systems Endovac and Conventional Needle in Primary Tooth Root Canals: An In Vitro Study. Int J Clin Pediatr Dent 2024;17(11):1219-1223.

Numerical investigation of injection characteristics on normal saline irrigation quality in curved root canals using computational fluid dynamics

Objectives

The primary aim of this research was to find the effects of Normal saline injection rate and position on irrigation quality in curved root canals.

Methods

Computational Fluid Dynamics (CFD) was used to simulate irrigation in root canals. Root canal geometries were obtained by considering the complete shaping of a rotary file in four root groups with 0, 10, 30, and 60° of curvatures. Fluid surface tension, bouncy, gravity, and air entrance were considered in the numerical simulation using Ansys-CFX software. For each root canal, the flow regime and wall shear stresses were calculated at three different syringe plunger speeds, and three different injection locations of a beveled open-ended needle and their effects on the irrigation quality were investigated in this paper.

Results

Wall shear stress is considered the main parameter determining irrigation quality. It was calculated for all 36 test cases. Injection rate and normal saline accumulating near the apex and their effects on washed area ratio were shown for the test cases. Results showed significant effects of injection characteristics, incredibly faster injection, and deeper needle position on the irrigation quality of curved root canals.

Conclusions

A higher injection rate and deeper needle position are required to achieve the best irrigation quality and a more washed area ratio in root canals with greater curvature.

Effectiveness of continuous chelation irrigation protocol in endodontics: a scoping review of laboratory studies

This scoping review aimed to synthesize and explore the current boundaries and limitations of laboratory research on the effectiveness of continuous chelation irrigation protocol in endodontics. This scoping review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. Literature search was conducted on Pubmed and Scopus to identify all laboratory studies evaluating smear layer and hard-tissue debris removal or, antimicrobial efficacy, or dentine erosion induced by continuous chelation. Two independent reviewers performed the all review steps and the relevant items were recorded. Seventy-seven potentially relevant studies were identified. Finally, 23 laboratory studies met the eligibility criteria for qualitative synthesis. Seven studies focused on the smear layer/debris removal outcome, 10 on antimicrobial activity, and 10 on dentine erosion. In general, the continuous chelation protocol was equally or more effective in the cleanliness of root canals and antimicrobial activity compared with traditional sequential protocol. In addition, etidronate solutions seemed to be milder chelating agents compared to those with EDTA, thus resulting in reduced or no dentine erosion and roughness modification. Yet, the methodological differences among the included studies limit the results' generalizability. The continuous chelation seems to be equally or more effective in all investigated outcomes when compared with the traditional sequential protocol. The methodological variability among the studies and shortcomings in the methods employed limit the generalizability and clinical relevance of the results. Standardized laboratory conditions combined with reliable three-dimensional investigation approaches are necessary to obtain clinically informative findings.

2D and 3D Erosion Landscape Analysis of Endodontic-Treated Teeth Using EDTA and HEDP as Chelating Agents: A High-Resolution Micro-Computed Tomographic Study

This study aimed to assess the amount of erosion during activated endodontic irrigation with either HEDP or EDTA via high-resolution micro-computed tomography. Two root canals of twenty premolars were prepared with ProTaper Next and irrigated with sodium hypochlorite. Palatal canals, which served as control groups, were sealed, while buccal canals were further irrigated with either EDTA (n = 10) or HEDP (n = 10), which served as test groups. Micro-CT was performed to measure erosion depth. For 2D and 3D measurements, non-parametric repeated ANOVA measurements and post hoc tests were performed. 2D analysis showed highly significant differences between the case groups at each position of the root (p ≤ 0.01). The cervical and apical positions showed significant differences in the EDTA group (p = 0.03). The 3D analysis also showed significant differences between both chelating agents (p < 0.01) and the case and control groups (p = 0.01). The mean erosion depths in the cervical, middle, and apical thirds of the EDTA group were 45.75, 41.79, and 32.25 µm, and for the HEDP group were 20.25, 16.40, and 15.96 µm, respectively. HEDP seems to have a significantly less erosive effect. Different irrigation protocols with harsher conditions, as might be the case during endodontic retreatment, could be assessed with micro-CT.

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.

Effectiveness of root canal irrigation and dressing for the treatment of apical periodontitis: A systematic review and meta-analysis of clinical trials

BACKGROUND

Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) and/or calcium hydroxide (Ca(OH)2 ) are commonly used during root canal treatment. Evaluation of their effectiveness regarding clinical and patient-related outcomes requires further understanding.

OBJECTIVES

To assess the effectiveness of root canal irrigation and dressing for the treatment of teeth with apical periodontitis (AP).

METHODS

A search was conducted in the PubMed-MEDLINE, Scopus, EMBASE, Google scholar databases and available repositories, followed by hand searches, until July 2021. Eligibility criteria followed the a priori formulated Population, Intervention, Comparator, Outcomes, Timing, and Study design (PICOTS) framework. Clinical studies restricted to English language were included. The revised Cochrane risk-of-bias tool for randomised trials (RoB 2) was used to assess the quality of included studies. Meta-analyses were performed using the fixed-effect model to obtain Risk Ratio (RR) and 95% Confidence Interval (CI), with sensitivity analysis. Overall quality of evidence of meta-analyses was assessed through the Grading of Recommendations Assessment, Development, and Evaluation tool.

RESULTS

The search identified 1357 records of which six fulfilled the inclusion criteria, providing data for 'irrigation' from 212 teeth and for 'dressings' from 438 teeth. Two studies reported no significant difference regarding the outcome 'pain at 7 days' using 2% chlorhexidine vs. 5.25% NaOCl and EDTA or after using different concentrations of NaOCl (1% vs. 5%). No significant difference was detected between different NaOCl concentrations regarding the reduction of AP. A meta-analysis was possible for the comparison of single-visit (SV) versus multiple-visits including the use of Ca(OH)2 demonstrating a significant effect in favour of SV (RR: 1.10; 95% CI: 1.03-1.19; p = .007; I2  = 0). RoB of included studies was moderate to low.

DISCUSSION

The use of Ca(OH)2 for the treatment of AP may not be beneficial. There is scarce or no evidence fulfilling the proposed PICOTS regarding irrigants and dressings.

CONCLUSIONS

There is moderate certainty that SV treatment is associated with better radiographic evidence of normal periodontal ligament space (strict criteria) compared with the use of Ca(OH)2. Reduction of AP is comparable after irrigation with 1% and 5% NaOCl, whereas postoperative pain at 7 days for the irrigants assessed is similar.

REGISTRATION

PROSPERO database CRD42021260271.

XP-endo Finisher effectively reduces hard-tissue debris accumulated in root canals with isthmus after preparation with a reciprocating file system

This study compared the accumulated hard-tissue debris (AHTD) after preparation with WaveOne Gold (WOG) to XP-endo Shaper (XPS), without and with a supplementary step using XP-endo Finisher (XPF) using clinically applicable irrigation. Twenty-four mesial roots with two canals and single foramen were micro-CT-scanned and matched. Scans were also taken after preparation with WOG or XPS, and after XPF. Irrigation with 2.5% NaOCl (total: 17 ml per canal) and 17% EDTA (2.5 ml per canal) was performed using a 30ga Max-I-Probe needle placed up to the working length. Morphological parameters were calculated and compared within and among groups. XPF significantly reduced unprepared area within XPS and WOG groups, and AHTD within WOG (p < 0.05). There were no significant differences between WOG and XPS after preparation and after XPF (p > 0.05). In conclusion, WOG and XPS produced a similar volume of AHTD, but the supplementary step with XPF decreased the AHTD in the WOG group.

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.

Morphological Analyses of Effects of Endodontic Irrigant Solutions Using a Root Canal Model and an Immersion Model

Objective

This study aimed to compare an experimental model simulating clinical root canal irrigation (root canal model) with a conventional experimental model immersing dentin sample to irrigants (immersion model) to evaluate removal of the smear layer and decalcification of the root canal dentin using sodium hypochlorite (NaOCl) and two different concentrations of ethylenediaminetetraacetic acid (EDTA) solution.

Materials and Methods

Forty-five single-rooted extracted human teeth were prepared using a Ni-Ti rotary file. EDTA, NaOCl, and citric acid were used in the root canal models and the immersion models. After the irrigation protocol, root canal surfaces were observed under scanning electron microscopy. Residual smear and decalcification of the root canal dentin were evaluated objectively by measuring the percentage of the area occupied by visible dentin tubules, the number of visible dentin tubules, and the mean area of a visible single dentin tubule.

Results

Root canal and immersion models with the same irrigation protocol showed significantly different results for smear residues and decalcification of root canal dentin. In the root canal model, neither different EDTA concentrations nor the order of EDTA and NaOCl applications significantly impacted smear residues or decalcification of root canal dentin. Furthermore, no erosion of the root canal dentin surface was observed in any experimental groups in the root canal model using EDTA and NaOCl compared to intact dentin.

Conclusions

Experimental design affected results for residual smear layer and decalcification of root canal dentin. The order of EDTA and NaOCl use and the concentration of EDTA did not affect results. EDTA and NaOCl irrigation did not cause erosion in the root canal model in this study.

Knowledge, Attitude, and Practice towards Chelating Agents in Endodontic Treatment among Dental Practitioners

The use of chelating agents (CAs) in the endodontic irrigation protocol is required to dissolve the inorganic components of the smear layer. We aimed to assess the knowledge, attitude, and practice of dental professionals regarding the use of CAs during root canal treatment. A cross-sectional anonymous online survey was conducted among specialized endodontists and general dentists who routinely perform endodontic treatment and work in government-funded or private clinics in Moscow. The 8 min survey consisted of four parts: basic demographic data, knowledge (five items), attitude (four items), and practice (five items). We collected 376 completed questionnaires; a majority of the respondents were general dentists (87.5%) and worked in private clinics (77.4%). Most respondents (83.5%) showed a fair knowledge of the CAs used in endodontics, while 16.5% showed a poor knowledge of the topic. Small yet significant differences were found between endodontists and general practitioners and between dentists employed by private and government-funded clinics. A majority of dental practitioners (83%) demonstrated a positive attitude towards the use of CAs in endodontic treatment, and there were no differences among the study subgroups. Almost a third of the respondents always used chelating solutions during endodontic treatment, while 17% of the respondents did not use them at all. There were significant differences in this parameter between dentists working in private and government-funded clinics. Practice significantly correlated with attitude towards chelating agents and with knowledge of the topic. In conclusion, dental practitioners demonstrated a fair knowledge of CAs. Despite a positive attitude, 71% of the respondents did not use CAs for all endodontic patients.

A Novel Endodontic Approach in Removing Smear Layer Using Nano and Submicron Diamonds with Intracanal Oscillation Irrigation

Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are commonly recommended for effectively removing organic and inorganic components in the smear layer. This layer is found on root canal walls after root canal instrumentation. However, high-concentration EDTA reduces the strength of dentin and the dissolution efficacy of organic substances in NaOCl solution. The objective of this study was to investigate the efficacy of applying nano and submicron diamonds in irrigation solutions with sonic and ultrasonic oscillation for removing the smear layer during endodontic treatment. Extracted single-rooted human teeth were instrumented with ProTaper^® Gold (Dentsply Sirona) nickel-titanium rotary instruments. Subsequently, each canal was irrigated with 3% NaOCl, 17% EDTA, distilled water, and 10-1000 nm-sized nano and submicron diamond irrigation solutions, respectively. Sonic and ultrasonic instruments were compared for oscillating the irrigation solutions. The teeth were processed for scanning electron microscopy to observe the efficiency of smear layer removal on the canal walls. Our results indicated that diamond sizes of 50 nm and above irrigation solutions showed significant effectiveness in removing the smear layer following the oscillation of sonic instruments for 10 s. Ultrasonic assisted 500 nm and 1000 nm diamond solutions significantly differed from the other diamond-sized solution in their ability to remove the smear layer. These results suggest that sonic and ultrasonic oscillation with specific sizes of nano and submicron diamond irrigation solution can be used as an alternative approach to removing the smear layer during endodontic treatment. The potential clinical application of root canal treatments can be expected.

Comparative Evaluation of Smear Layer Removal Efficacy of Neem Leaf Extract, Propolis, and Orange Oil when used as Endodontic Irrigants: An in vitro Scanning Electron Microscopic Study

Introduction

In root canal treatment, chemical debridement of the root canal with the help of irrigants is important due to the complex internal anatomy of the teeth. Biomechanical root canal preparation produces a smear layer. It covers the dentinal tubules, which may interfere with the penetration of various irrigants and intracanal medicaments, so the smear layer has to be removed. The potential side effects and certain limitations of chemical irrigants for smear layer removal have led to a shift toward herbal alternatives.

Objective

The aim of the present study was to evaluate and compare the smear layer removal efficacy of Neem leaf extract, Propolis, and Orange oil as endodontic irrigants using the scanning electron microscope.

Materials and Methods

Ninety samples were taken and then randomly (simple random sampling method) divided into three experimental groups (n = 30) depending upon different endodontic irrigants used: Group 1-Neem leaf extract, Group 2-Orange oil and Group 3-Propolis and smear layer removal evaluation was done under the scanning electron microscope Scanning Electron Microscope (SEM) at all the levels, i.e., coronal, middle, and apical.

Results

The collected data were analyzed using the Chi-square test. Group 1 (Neem leaf extract) showed the highest smear layer removal efficacy, which was followed by Group 2 (Orange oil) and the least efficacy of smear layer removal was shown by Group 3 (Propolis) at coronal, middle, and apical levels.

Conclusion

Group 1 (Neem leaf extract) performed significantly better in removing the smear layer at coronal, middle, and apical levels as compared to the other two groups.

Efficacy of Laser-Activated Irrigation Versus Ultrasonic-Activated Irrigation: A Systematic Review

This study aimed to conduct a systematic review and critical analysis of the evidence pertaining to the efficacy of laser-activated irrigation (LAI) versus ultrasonic-activated irrigation (UAI) in mature permanent teeth. A comprehensive literature search was performed using PubMed and Google Scholar. Additionally, a hand search was performed to identify relevant studies related to UAI and LAI. The search covered all articles published from January 1997 to December 2021. The identified studies were screened for eligibility using the inclusion and exclusion criteria. The included articles were then subjected to data extraction and analysis. The search yielded 1,637 results. Of these, 23 articles were included in this systematic review. All included articles were assessed for the outcomes of antimicrobial efficacy, smear layer, and dentin debris removal. The majority of the articles reported the superiority of LAI over UAI. Within the confines of this systematic review, the current evidence mandates that LAI has superior efficacy over UAI in the elimination of microorganisms, dentin debris, and smear layer from the root canal system.

Formulation and Characterization of a Novel Palm-Oil-Based α-Mangostin Nano-Emulsion (PO-AMNE) as an Antimicrobial Endodontic Irrigant: An In Vitro Study

Aim: To formulate and characterize a palm-oil-in-water-based α-Mangostin nano-emulsion (PO-AMNE) endodontic irrigant, in order to evaluate its antibacterial efficacy against Enterococcus faecalis, Staphylococcus epidermidis, and Candida albicans biofilms, as well as its capacity to remove smear layer. Methods: The solubility of α-Mangostin in various oils was determined and selected, surfactants and co-surfactants were used for the nano-emulsion trial. PO-AMNE was prepared and optimized. The MIC was performed, and the antimicrobial efficacy was estimated against biofilms. The optimized 0.2% PO-AMNE irrigant antimicrobial efficacy in a tooth model was done using colony-forming units. The treated teeth were processed by scanning electron microscopic examination for debris and smear layer removal. An Alamar Blue assay was used to evaluate cell viability. The optimization of the PO-AMNE irrigant was performed using Box–Behnken statistical design. Results: The optimized 0.2% PO-AMNE irrigant was found to have a particle size of 340.9 nm with 0.246 PDI of the dispersed droplets, and a zeta potential (mV) of −27.2 ± 0.7 mV. The MIC values showed that 0.2% PO-AMNE (1.22 ± 0.02) were comparable to 2% CHX (1.33 ± 0.01), and 3.25% NaOCl (2.2 ± 0.09) had the least inhibition for E. faecalis. NaOCl (3.25%) showed the maximum inhibition of S. epidermidis (0.26 ± 0.05), whereas 0.2% PO-AMNE (1.25 ± 0.0) was comparable to 2% CHX (1.86 ± 0.07). For C. albicans, 2% CHX (8.12 ± 0.12) showed the least inhibition as compared to 0.2% PO-AMNE (1.23 ± 0.02) and 3.25% NaOCl (0.59 ± 0.02). The 0.2% PO-AMNE irrigant was then evaluated for its antimicrobial efficacy against the three biofilms, using colony-forming units. The 0.2% PO-AMNE was comparable to both 3.25% NaOCl and 2% CHX in inhibiting the growth of biofilms. The 0.2% PO-AMNE and 17% EDTA eliminated the smear layer with the lowest mean scores (p < 0.001). Finally, 0.2% PO-AMNE was shown to be biocompatible when compared to 17% EDTA, 3.25% NaOCl, and 2% CHX in immortalized oral keratinocyte cells. Conclusion: Overall, the formulated 0.2% PO-AMNE irrigant was an effective antimicrobial and biocompatible which could combat endodontic-infection-related polymicrobial biofilms.

The Effect of Calcium Hydroxide, Triple Antibiotic Paste and Chlorhexidine on Pain in Teeth with Symptomatic Apical Periodontitis: A Randomised Controlled Trial

BACKGROUND

One of the main reasons for post endodontic pain is the polymicrobial intracanal flora that may survive the initial disinfection. A single antimicrobial agent might not provide adequate disinfection, and an antimicrobial combination such as triple antibiotic paste was tested to achieve this goal.

AIM

The study aimed to assess the efficacy of three intra-canal medicaments on post root canal preparation pain.

MATERIALS AND METHODS

Eighty patients with single-rooted necrotic teeth and symptomatic apical periodontitis were randomly assigned to four treatment groups (n = 20). Their preoperative pain was recorded on Wong-Baker's FACES pain rating scale. After chemo-mechanical canal preparation, intracanal medications were applied to the groups (Group 1 (20% calcium hydroxide), Group 2 (2% chlorhexidine), Group 3 (tri-antibiotic paste), Group 4 (no medication (Control group)). Patients were instructed to record pain on the Wong-Baker FACES pain rating scale at 4, 48, 72 and 96 hrs, postoperatively. Pain scores were analyzed using a one-way ANOVA test and Tukey's post hoc test and, if significant, Dunn's test was used for pair-wise comparisons. The significance level was set at a p-value ≤ 0.05.

RESULTS

Tukey's post hoc test revealed significantly lower pain scores in Group 3 compared with other groups at all follow up intervals. Dunnett's test showed significantly lower pain in Group 3 compared with the Control group at 48, 72 and 96 hrs, postoperatively.

CONCLUSIONS

Triple-antibiotic paste showed effective pain control as an intracanal medication on necrotic teeth with symptomatic apical periodontitis.

Assessment of Irrigant Agitation Devices in Simulated Closed and Open Root Canal Systems

INTRODUCTION

The in vitro efficacy of irrigant activation devices has not been contrasted to their safety. This was attempted in this study using apically closed versus patent simulated root canal systems in epoxy resin models, with the latter featuring a simulated periapical lesion.

METHODS

All 72 models had 2 joining canals connected by an isthmus, which was filled with dentin debris. The simulated periapical lesion was filled with colored gelatin in the 36 respective models. Canals were irrigated with 1.3% sodium hypochlorite. Samples were divided into 4 subgroups per system (n = 9): conventional irrigation, sonic low (EndoActivator; Dentsply Sirona, Charlotte, NC) and high frequency (EDDY; VDW, Munich, Germany), and ultrasonic agitation of the irrigant (always applying 3 cycles of 20 seconds). The total cleared surface areas (mm²) in the simulated isthmus and periapical lesion were compared between systems and devices using parametric tests (P < .05).

RESULTS

The cleaning of the isthmus was more effective in the apically open compared with the closed systems and was also significantly influenced by the agitation method (P < .001). In the closed systems, EDDY and ultrasonic agitation achieved the significantly (P < .05) best cleaning of the isthmus. In the open systems, ultrasonic agitation showed the single best result (P < .05). EDDY caused by far the highest and ultrasonic agitation the lowest dissolution of the gelatin in the simulated periapical lesion.

CONCLUSIONS

Under the conditions of this study, ultrasonic agitation of a previously administered sodium hypochlorite irrigant was more laterally targeted and thus safer and more effective than sonic agitation methods.

Application of Reactive Oxygen Species in Dental Treatment

Reactive oxygen species (ROS) and free radicals, which have been implicated in inflammation, pain, carcinogenesis, and aging, are actually used in dental treatments such as tooth bleaching and composite resin polymerization. Recently, numerous studies have investigated the application of ROS in the medical and dental fields. In previous studies, ROS were generated intentionally through pathways such as photolysis, photocatalytic methods, and photodynamic therapy, which are used in the medical field to target cancer. In the field of dentistry, generated ROS are applied mainly for periodontal treatment and sterilization of the root canal, and its effectiveness as an antibacterial photodynamic therapy has been widely reported.. Given this background, the present article aimed to review the basic effects of ROS in dental medicine, especially endodontic therapy, and to discuss future applications of ROS.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Removal of Accumulated Hard Tissue Debris (AHTD) from Root Canals with an Electric Current Device: A MicroCT Preliminary Report

In modern endodontics, removal of accumulated hard tissue debris (AHTD) from root canals is requested. In the last decade, different irrigating solutions and activation methods have been successfully tested. Sonic activation has been shown to be effective in the removal of AHTD. Electric current has been tested before in restorative dentistry, but not in endodontics. An experimental electric current delivering device was compared in the removal of AHTD, using microCT analyses. Fifteen single-rooted teeth were shaped with TruNatomy system endodontic files and divided into three groups: negative control group: specimens underwent no activation; EA group: specimens were activated with EndoActivator (EA); EB group: specimens were activated with ElectroBond (EB). The 2D images, 3D images and morphometric analysis from the microCT showed a statistically significant increased AHTD removal when EB was used. Results of the present preliminary study showed that the irrigant activation with ElectroBond is encouraging when compared to EndoActivator along the entire root canal system. The AHTD was significantly statistically reduced, validating the clinical use of electric fields in endodontics.

A critical analysis of research methods and experimental models to study intracanal medicaments

In order to ensure predictable decontamination of the root canal system, chemo-mechanical preparation of the root canal space is sometimes supplemented with the use of intracanal medication. As microbial control of the root canal space is fundamental to the resolution of apical periodontitis, root canal disinfection strategies haven been researched intensively. The use of intracanal medication as a supplementary step to the chemo-mechanical preparation of the root canal space is one of them. Because of the costs and limitations of clinical research it is relevant and common practice to first evaluate alternative or new root canal disinfection modalities in laboratory studies. This involves the simulation of a root canal infection in a laboratory model, on which different disinfection strategies can be tested. When modelling the infected root canal, different levels of infection can be discriminated: suspended bacteria, microbial biofilms and infected dentine. This review describes the experimental models associated with these infection levels and critically appraises their value and methodological details. Suggestions for relevant research methods and experimental models are given, as well as some good practices for laboratory-based microbiological studies.

Irrigating Solutions and Activation Methods Used in Clinical Endodontics: A Systematic Review

Background

Ex vivo and in vitro studies have demonstrated the effectiveness of some irrigation protocols in reducing the bacterial load in the root canal system. However, standardized protocols have not yet been defined for the real clinical context due to many irrigation procedures available.

Objective

To evaluate the clinical endodontic protocols and limitations of irrigating solutions in the disinfection of the root canal system in patients with apical periodontitis.

Methods

PubMed, Scopus, Embase, Web of Science, and Cochrane databases were searched for randomized controlled trials (RCT) published until January 2021. Hand searching was also performed. Studies focused on evaluating the effectiveness of irrigating solutions and/or irrigation activation methods in reducing the bacterial load in the root canal system were considered. The Cochrane risk-of-bias tool for randomized trials (RoB2) was used to assess the quality of the studies.

Results

Four hundred and twenty eight published articles were identified. After removing the duplicate studies and analyzing full texts, seven RCTs were selected. Two studies compared pure NaOCl with some combination of NaOCl with HEDP and MTAD. Two studies analyzed the antibacterial efficacy of NaOCl and chlorhexidine (CHX). Three studies compared conventional needle irrigation with different irrigation activation methods (PUI, XP-endo finisher, F-file activator, EndoVac activator). The review attained a satisfactory methodology. The main results of each included study were described.

Discussion

Activation methods provide significantly higher biofilm reduction than conventional needle irrigation methods. Combinations of NaOCl with different chelating agents were ineffective in terms of antimicrobial, but it could potentially increase the risk of irrigant extrusion. However, the irrigating protocols were not carefully detailed, especially those regarding the irrigants application time or total volume. The existing literature lacks high-quality studies. The level of evidence is moderate.

Conclusions

The available data is too heterogeneous to compare and identify the superiority of specific valuable irrigation protocols in each clinical context. Application time, volume, and activation methods should be standardized to determine the optimal irrigating procedures to reduce the bacterial load and ensure higher predictability of the endodontic treatment.

Systematic Review Registration

(https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=218555), PROSPERO registration: CRD42020218555.

A Comparative Evaluation of Smear Layer Removal Using Erbium:YAG Laser-Activated Irrigation, Sonic Irrigation, and Manual Dynamic Irrigation: A Scanning Electron Microscope Study

Introduction: The conventional chemomechanical procedures are ineffective in complete disinfection of the pulp space due to the complexities of the root canal architecture. The present study aims to compare the efficacy of erbium: YAG laser-activated irrigation, sonic irrigation, and manual dynamic irrigation in the removal of the smear layer through a scanning electron microscope study. Methods: Fifty extracted single rooted mandibular premolars with single canal were used and instrumented until F3 ProTaper rotary file reached the working length. Upon the completion of the canal preparation, each specimen was irrigated with 3 mL of 4% NaOCl for 3 minutes, 3 mL saline for 1 minute and 3 mL of 17% EDTA for 3 minutes. The teeth were assigned to three experimental groups (n=15 each): manual dynamic irrigation, sonic irrigation (EndoActivator), and Er:YAG laser using an X pulse tip. Root canals were sectioned longitudinally and the smear layer at the apical, middle and coronal third was examined under a scanning electron microscope. Smear layer scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests at P = 0.05. Results: The Er:YAG laser group showed significantly lower smear layer scores in the apical third as compared to all other groups. EndoActivator resulted in better cleaning efficacy at the apical area compared to manual dynamic agitation. Conclusion: This study showed results in favor of Er:YAG with an X-pulse tip followed by EndoActivator activation.

Influence of the use of chelating agents as final irrigant on the push-out bond strength of epoxy resin-based root canal sealers: A systematic review

This systematic review (PROSPERO - CRD42020150722) was performed to answer the following question: Does the use of chelating agents affect the dislodgment resistance of epoxy resin-based root canal sealers? A search was conducted in PubMed, EMBASE, Scopus, LILACS and Web of Science, hand searching of two endodontic journals and grey literature until September 2020. Extracted data included: teeth used, sample size, root canal preparation, irrigant, chelating solution, neutralisation solution, type of resin-based sealer and obturation approach, storage method and duration, root third and slice thickness, plunger dimension and loading direction and the push-out testing parameters and values. The search retrieved a total of 2.389 studies. After analysis, 12 studies fulfilled the eligibility criteria and were included. Most of the final irrigation protocols with chelating agents had a positive impact and promoted an improvement in the dislodgment resistance of epoxy resin-based sealers to the root dentin.

Effect of Various Laser-Activated Irrigation Protocols on Endodontic Sealer Penetration into the Dentinal Tubules: A Confocal Laser Scanning Microscopy Study

Objective: To study the effect of various laser-activated irrigation protocols on endodontic sealer penetration into the dentinal tubules. Background data: Laser-activated irrigation is helpful for smear layer removal and thus might increase the penetration of endodontic sealer into the dentinal tubules. Methods: Forty-eight mandibular premolars with straight canals were instrumented and divided into four groups: C-I group, conventional needle irrigation with sodium hypochlorite (NaOCl) followed by ethylenediaminetetraacetic acid (EDTA); Er:YAG-I, Er,Cr:YSGG-I, and Nd:YAP-I groups, NaOCl and EDTA irrigations activated by erbium:yttrium-aluminum-garnet (Er:YAG), erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG), and neodymium:yttrium-aluminum-perovskite (Nd:YAP) lasers, respectively. The cleanness of the treated canals was evaluated by scanning electron microscopy (SEM). Then, canals were obturated with AH-Plus sealer labeled with rhodamine B (0.1%) and combined with gutta-percha. After setting, canals were sectioned at 2, 5, and 8 mm short from the root apex, and the penetration area of the AH-Plus into the dentinal tubules was observed using confocal laser scanning microscopy (CLSM). Results: SEM results indicated that the Er:YAG-I and Er,Cr:YSGG-I lasers were more effective than the Nd:YAP-I and C-I in removing the smear layer. CLSM results indicated that the average AH-Plus penetration areas among the tested groups were in ascending order: C-I < Nd:YAP-I < Er:YAG-I, Er,Cr:YSGG-I (p < 0.05). Conclusions: Laser-activated irrigations significantly increased the penetration of the endodontic sealer into the dentinal tubules, among which Er:YAG-I and Er,Cr:YSGG-I lasers were the most effective and may be considered routine protocols for endodontic treatment.

Scanning Electron Microscopic and Dye Penetration Evaluation of Hand Instrumentation Techniques on Formation of Smear Layer in Root Canal Preparation: An In vitro Study

AIMS AND OBJECTIVES

The present study was undertaken for evaluating various hand instrumentation techniques with different instruments in the formation of smear layer.

MATERIALS AND METHODS

One hundred and seventy-five extracted mandibular molars were collected and were cut at cementoenamel junction. Afterward, the distal roots were separated. Working length was determined, and roots were divided into five equal groups with 35 roots in each group as follows: Group A: K-type files with conventional step-back technique, Group B: Canal Master U instrument with clockwise-counterclockwise rotation, Group C: Flex-R® files with clockwise-counterclockwise rotation, Group D: FlexoFiles® with conventional step-back technique, and Group E: Nickel titanium files with conventional step-back technique. Biomechanical preparation was done according to their respective groups. The teeth in various groups were scanned under scanning electron microscope and scoring was done. All the results were analyzed by SPSS software version 17.0.

RESULTS

Scanning electron microscopic results indicated that apparently there seems to be a significant difference in the scoring of the smear layer between each group at all the three levels, but the difference was statistically nonsignificant. Microleakage was present in all the samples. Nonsignificant results were obtained while comparing the microleakage in between different the groups. However, microleakage was highest in Group D.

CONCLUSION

The amount of smear layer is maximum at the apical third and lesser in the middle third followed by the coronal third in all the groups. All the samples showed microleakage to a varying extent.

Effects of heat in the properties of NaOCl alone and mixed with etidronate and alkaline tetrasodium EDTA

AIM

To assess the free available chlorine concentration (FAC), organic tissue dissolution and smear layer removal capacity of sodium hypochlorite (NaOCl) alone and when mixtured with etidronate (HEDP) and tetrasodium EDTA (Na₄ EDTA), and heated to different temperatures.

METHODOLOGY

Mixtures at 1 : 1 ratio of 5% NaOCl with distilled water (considered NaOCl alone), 18% HEDP or 10% Na₄ EDTA were heated to 25 °C, 37 °C, 48 °C and 60 °C. The FAC in the mixtures was assessed at 5, 10, 20, 30, 60 and 120 min. Samples of bovine muscle tissue (n = 10) were prepared with similar size and weighed before and after 5, 10 and 15 min of immersion in the mixtures heated to the different temperatures to verify organic matter dissolution. The intergroup results were compared statistically using one-way analysis of variance (anova) and intragroup by two-way analysis of variance (anova), both followed by Tukey's multiple-comparison test (α < 0.01). Bovine dentine blocks (n = 10) were analysed by scanning electron microscopy before and after immersion in the mixtures, and the time taken to remove the smear layer from the surfaces of the samples was determined. The Friedman test was used to compare the scores of the same group (α < 0.01), and the Kruskal-Wallis test with Dunn's post hoc was used to compare the different groups (α < 0.01). Saline solution was used as a control in the experiments of tissue dissolution and smear layer removal, RESULTS: Heating NaOCl alone did not affect its FAC. The higher the temperature of the mixtures with the chelators, the lower the FAC. Organic tissue dissolution was improved by increases in temperature of NaOCl alone and its mixture with HEDP (P < 0.01); however, the mixture with Na₄ EDTA had no improvement (P > 0.01). Smear layer removal by NaOCl alone was enhanced by heating resulting in lower scores in some samples and became more rapid in the mixtures with the chelators. The saline solution did not promote tissue dissolution nor smear layer removal (P > 0.01).

CONCLUSION

In this laboratory study, heating NaOCl alone or when mixed with HEDP improved its capacity to dissolve organic matter and remove the smear layer. However, the mixture with HEDP required frequent refreshment to retain these effects when heated. Due to the acceleration in the reaction between the irrigants, very rapid reductions in the free available chlorine in the mixtures with Na₄ EDTA heated to the different temperatures occurred.

Postoperative pain after ultrasonically and laser-activated irrigation during root canal treatment: a randomized clinical trial

AIM

To compare the intensity of postoperative pain after primary root canal treatment of asymptomatic teeth when using ultrasonically (UAI) or laser-activated irrigation (LAI).

METHODOLOGY

In this superiority randomized clinical trial (ClinicalTrials.gov ID: NCT03981237) with parallel design, fifty-six patients with an asymptomatic tooth in need of primary root canal treatment were enrolled. After chemo-mechanical canal preparation using rotary instruments and NaOCl irrigation, teeth were randomly assigned to two groups and patients were blinded to the final irrigation protocol. In the UAI group (n = 28), 60s activation with an Irrisafe tip was done per canal. In the LAI group (n = 28), NaOCl was activated with a pulsed Er:YAG (2940 nm) laser, equipped with a conical tip, with settings of 50 µs, 20 mJ at 15 Hz for 60 s. Patients recorded their pain intensity 6, 24, 48 and 72 h after treatment on a 100 mm visual analogue scale (VAS), as well as their analgesic consumption. Pain levels and incidence were compared across groups using the Mann-Whitney U-test and chi-square test.

RESULTS

Overall, mean postoperative pain intensity was low, with the majority of patients having no or minimal pain 24 h postoperatively. At 6 h postoperatively, pain intensity and incidence were significantly higher in the UAI group compared to the LAI group (P < 0.05). For the other time intervals, no significant differences in postoperative pain incidence or intensity were found. The frequency of analgesic intake did not differ significantly between the two groups. Neither of the activation methods resulted in any adverse effects.

CONCLUSIONS

Ultrasonically and laser-activated irrigation resulted in low and comparable levels of postoperative pain in asymptomatic patients receiving primary root canal treatment.

Evaluation of debris and smear layer formation using three different NI-TI rotary instrument systems: An in vitro scanning electron microscope study

Aim:

The aim of the study is to evaluate of debris and smear layer formation after using rotary ProTaper Universal, Twisted File, and XP Endo file systems under scanning electron microscope.

Materials and Methods:

Forty freshly extracted mandibular second premolar teeth were taken to decoronate at the cementoenamel junction to make the remaining root length 15 mm. Specimens were divided into four groups of 10 teeth each, Group I (control) – no instrumentation. Group II – ProTaper Universal rotary file (F2), Group III – twisted file (ISO size 0.25 and 6% taper), Group IV – XP Endo file (ISO size 0.25). During instrumentation, 5 ml normal saline was used as irrigating agent. Grooves parallel to the longitudinal axis of the root were made on the mesial and distal surface of each specimen to split it into two halves and examined under scanning electron microscope at ×1500 and ×5000 magnification. Photomicrographs were taken to evaluate debris and smear layer. Evaluation of photomicrographs was done using a score index.

Results:

One-way analysis of variance (ANOVA) was used to compare more than one means at a time. Tukey's critical difference followed by ANOVA was used to compare the mean values pair wise. P <0.05 was considered to be statistically significant. Among all the file systems, Group II showed maximum amount of debris (3.50 ± 1.109) followed by Group III (2.83 ± 1.238) and least amount was showed by Group IV (2.65 ± 1.122) at all levels (cervical, middle, and apical third). Among all the experimental groups, Group II showed maximum amount of smear layer (2.75 ± 1.149) followed by Group III (2.40 ± 0.982) and least amount of smear layer shown by Group IV (2.10 ± 0.841) at all levels (cervical, middle and apical third), the result was statistically significant (P < 0.05).

Conclusions:

At all the levels (cervical third, middle third, and apical third), among all the experimental groups, highest amount of debris and smear layer was formed by ProTaper Universal rotary file followed by Twisted file and least amount showed by XP Endo file system. In all the levels, control group showed highest amount of debris but least amount of smear layer.

Candida albicans as an Essential "Keystone" Component within Polymicrobial Oral Biofilm Models?

Background: Existing standardized biofilm assays focus on simple mono-species or bacterial-only models. Incorporating Candida albicans into complex biofilm models can offer a more appropriate and relevant polymicrobial biofilm for the development of oral health products. Aims: This study aimed to assess the importance of interkingdom interactions in polymicrobial oral biofilm systems with or without C. albicans, and test how these models respond to oral therapeutic challenges in vitro. Materials and Methods: Polymicrobial biofilms (two models containing 5 and 10 bacterial species, respectively) were created in parallel in the presence and absence of C. albicans and challenged using clinically relevant antimicrobials. The metabolic profiles and biomasses of these complex biofilms were estimated using resazurin dye and crystal violet stain, respectively. Quantitative PCR was utilized to assess compositional changes in microbial load. Additional assays, for measurements of pH and lactate, were included to monitor fluctuations in virulence "biomarkers." Results: An increased level of metabolic activity and biomass in the presence of C. albicans was observed. Bacterial load was increased by more than a factor of 10 in the presence of C. albicans. Assays showed inclusion of C. albicans impacted the biofilm virulence profiles. C. albicans did not affect the biofilms' responses to the short-term incubations with different treatments. Conclusions: The interkingdom biofilms described herein are structurally robust and exhibit all the hallmarks of a reproducible model. To our knowledge, these data are the first to test the hypothesis that yeasts may act as potential "keystone" components of oral biofilms.

Smear Layer Removal from Root Canal Dentin and Antimicrobial Effect of Citric Acid-modified Chlorhexidine

Objective:

To study the effectiveness of various concentrations of citric acid (CA) added to 2% chlorhexidine (CHX) on smear layer removal from the root canal wall and antimicrobial efficacy against Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans).

Methods:

Fifty-three single-rooted mandibular premolars were decoronate and the root canals underwent mechanical instrumentation using MTwo rotary files to size 40/0.06. The samples were then randomly divided into 5 groups according to the root canal irrigants to be used: 17% ethylenediaminetetraacetic acid (EDTA), 2% CHX, 1%, 6%, and 10% citric acid-modified 2% chlorhexidine (CAmCHX). Three teeth irrigated with phosphate-buffered saline (PBS) were used as a negative control. The smear layer removal effectiveness was evaluated under scanning electron microscopy (SEM). Images were randomly taken at the apical, middle, and coronal third level. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests. Disc diffusion and direct exposure tests were performed along with three additional control groups consisting of 1%, 6%, and 10% CA groups to assess and compare the antimicrobial efficacy of irrigants against E. faecalis and C. albicans. Statistical analysis was conducted using one-way ANOVA and Dunnett’s T3 tests.

Results:

Smear layer removal effectiveness in 17% EDTA group and 6% and 10% CAmCHX groups were not significantly different in the coronal and apical third of the root canal (P>0.05), however at the middle third of the root canal, the 10% CAmCHX group had significantly less remaining smear layer than all of the other experimental groups (P<0.05). There was significantly more smear layer remnant in the CHX group (P<0.01). For antimicrobial efficacy, the largest growth inhibition zone against E. faecalis was recorded in the 10% CAmCHX group (P<0.05). For planktonic E. faecalis, 1%, 6%, and 10% CAmCHX demonstrated an insignificant difference in antimicrobial efficacy compared to CHX (P>0.05). CA demonstrated no antifungal effect against C. albicans. Whereas, 6% and 10% CAmCHX resulted in the largest growth inhibition zone. Also, adding CA to CHX resulted in an insignificant difference in antifungal effect against planktonic C. albicans compared to CHX (P>0.05).

Conclusion:

When CA was added into CHX, the mixed irrigant demonstrated smear layer removal ability. Additionally, its antimicrobial effect remained the same.

Evaluating the substantivity of silver diamine fluoride in a dentin model

Objectives

The goal of endodontic therapy is to prevent apical periodontitis. This is achieved by biomechanical preparation, microbial control using endodontic irrigants, and complete obturation of the canal space. In order to prevent possible post‐obturation complications and for an added antimicrobial effect, substantivity is a desired characteristic of endodontic irrigants. Currently the most commonly used endodontic irrigant that produces an antibacterial substantivity effect is chlorohexidine (CHX). Silver diamine fluoride (SDF) is a topically applied agent for managing dental caries and has shown to stop caries lesion progression. The objective of this study was to compare the antimicrobial substantivity effect of 3.8% SDF against other commonly used endodontic irrigants such as 2% CHX and 6.25% Sodium hypochlorite (NaOCl).

Material and methods

Using a diffusion disc assay we determined the antimicrobial activities of 38%, 3.8%, 0.38%, and 0.038% of SDF against the bacterium Enterococcus faecalis OG1RF. Subsequently, we compared the levels of colonization of E. faecalis by scanning electron microscopy (SEM) at 1.5‐ and 3‐week time intervals on dentin pretreated with 3.8% SDF, 6.25% NaOCl, 2% CHX or sterile phosphate buffered saline (PBS).

Results

The diffusion disc assay demonstrated that 38% and 3.8% of SDF inhibited the growth of E. faecalis. Moreover, the substantivity of 3.8% SDF (p < 0.01) was comparable to 2% CHX (p < 0.01) and it is significantly greater than 6.25% of NaOCl compared to the PBS treated samples after 1.5 and 3 weeks of incubation.

Conclusions

In this study, we demonstrate that SDF possesses antimicrobial properties against the opportunistic pathogen E. faecalis. Moreover, using a dentin model we show the substantivity of 3.8% SDF is significantly greater than 6.25% NaOCl, but is comparable to 2% CHX.

Evaluation of Cytotoxicity and Antibacterial Activity of a New Class of Silver Citrate-Based Compounds as Endodontic Irrigants

In the present study, the cytotoxicity and the antimicrobial activity of two silver citrate-based irrigant solutions were investigated. Cytotoxicity of various concentrations (0.25%, 0.5%, 1%, 2.5%, 5%) of both solutions (BioAKT and BioAKT Endo) was assessed on L-929 mouse fibroblasts using the MTT assay. For the quantitative analysis of components, an infrared (I.R.) spectroscopy was performed. The minimum inhibitory and minimal bactericidal concentrations (M.I.C. and M.B.C., respectively) were ascertained on Enterococcus faecalis strain ATCC 4083. For biofilm susceptibility after treatment with the irrigating agent, a minimum biofilm eradication concentration (M.B.E.C.) and confocal laser scanning microscope (C.L.S.M.) assays were performed. Quantification of E. faecalis cell biomass and percentage of live and dead cells in the biomass was appraised. Normality of data was analyzed using the D’Agostino & Pearson’s test and the Shapiro–Wilk test. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey’s test. Both silver citrate solutions showed mouse fibroblasts viability >70% when diluted to 0.25% and 0.5%. Conversely, at higher concentrations, they were extremely cytotoxic. F.T.-IR spectroscopy measurements of both liquids showed the same spectra, indicating similar chemical characteristics. No substantial contrast in antimicrobial activity was observed among the two silver citrate solutions by using broth microdilution methods, biofilm susceptibility (MBEC-HTP device), and biomass screening using confocal laser scanning microscopy (C.L.S.M.) technique. Both solutions, used as root canal irrigants, exhibited significant antimicrobial activity and low cytocompatibility at dilutions greater than 0.5%.

In Vitro Evaluation of Different Irrigation Protocols on Intracanal Smear Layer Removal in Teeth with or without Pre-Endodontic Proximal Wall Restoration

To investigate the influence of pre-endodontic coronal wall restoration on smear layer removal during different root canal irrigation strategies, single-root premolars were prepared with a mesio-occlusal cavity. Half were left untreated (G1), while the mesial walls of the remaining half were reconstructed using a resin composite (G2). The specimens were divided into control (ctrl) groups, which used the conventional needle irrigation method, and four experimental subgroups according to irrigation strategy: Sonic activation using the Endoactivator, sonic activation using the EQ-S, mechanical activation using the XP-Endo finisher, and ultrasonic activation using the EndoUltra. Smear layer removal was assessed through SEM and the results were statistically analyzed. At the coronal and middle thirds, no significant difference (p > 0.05) was detected for G1 and G2, except for the control subgroups (G1ctrl vs G2 ctrl) at the middle third. At the apical third, the smear layer removal was significantly greater for G2 than G1. In G1, both at the middle and apical level, EQ-S and EndoUltra showed greater smear layer removal (p < 0.05) compared to the others G1 subgroups. In G2, at the apical level, the EQ-S and EndoUltra were the most effective in smear layer removal. Pre-endodontic coronal wall restoration may improve the smear layer removal during root canal irrigation.

A comparative evaluation of smear layer removal by using ethylenediamine tetraacetic acid, citric acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study

Introduction:

Irrigants remove or dissolve smear layer formed during instrumentation. Thus it is important to study the effect of different irrigant solutions on smear layer removal.

Objectives:

The aim of this study is to determine which irrigant effectively removes the smear layer from the coronal, middle, and apical third of the root canal.

Materials and Methodology:

One hundred and twenty single-rooted mandibular premolars were decoronated and biomechanical preparation was done through hand instrumentation up to size 40 k file with 2.5% NaOCl irrigation between each successive filing, followed by irrigation with 5 ml of saline. The teeth were divided into Groups I, II, III, and IV containing 30 samples each and irrigated with 5 ml of 17% ethylenediamine tetraacetic acid (EDTA), 10% Citric acid, 7% Maleic acid and normal saline respectively for 1 min and final irrigation was done with 5 ml of distilled water of each sample. The canals were dried with 2% absorbent paper points. The roots were then split with a chisel and mallet. One-half of each tooth was selected and then was analyzed using a scanning electron microscope. The dentinal surfaces were observed at the cervical, middle, and apical third with ×2000 for the smear layer. The scores were attributed, according to Torabinejad et al. rating system.

Results:

7% maleic acid and 10% citric acid both are equally effective in smear layer removal from coronal and middle third, but in apical third 7% maleic acid is more effective than 10% citric acid. Between citric acid and EDTA, both are equally effective in smear layer removal from coronal and middle third, but in apical third, 10% citric acid is more efficacious than 17% EDTA.

Conclusion:

Within the limitations of the study, it can be concluded that all three tested irrigants removed the smear layer from coronal, middle, and apical third. However, in apical third 7% maleic acid is the most efficacious irrigant in smear layer removal.

Scanning electron microscopic evaluation of the efficacy of 5% ethylenediaminetetraacetic acid for smear layer removal

The purpose of the study was to evaluate the smear layer removal efficacy of novel Saver® irrigating solution including 5% EDTA and to compare the 17% EDTA as the most used counterpart. Forty-four single-rooted teeth were divided into four groups, were instrumented, and irrigated. The smear treatment groups were as follows: sterile distilled water; 5.25% sodium hypochlorite; Saver®; 17% EDTA. The root samples were blinded. The micrographic images of root samples were collected by scanning electron microscope. The percentages of open dentin tubules were quantified using an image analysis software on micrographs. Two-way ANOVA followed by Tukey's multiple comparisons was used (p < .05). The 17% EDTA showed the highest percentages of open dentin tubules than the other treatments (p < .01). The mean percentages of open dentin tubules of 17% EDTA revealed statistically highly significant differences than Saver® treatment in all root regions (p < .01). Dentin tubules were covered by dense smear layer in distilled water irrigation whereas, the tubular pattern of dentin structure was not observed in hypochlorite irrigation. The commercial Saver® product presented to be less cleaning property on the smear layer than 17% EDTA and failed to show any improvement in the removal of smear layer compared with its tested counterpart.

Can Herbal Extracts Serve as Antibacterial Root Canal Irrigating Solutions? Antimicrobial Efficacy of Tylophora indica, Curcumin longa, Phyllanthus amarus, and Sodium Hypochlorite on Enterococcus faecalis Biofilms Formed on Tooth Substrate: In Vitro Study

Aim:

The purpose of this study was to evaluate the antimicrobial efficacy of Tylophora indica, Curcumin longa, and Phyllanthus amarus on Enterococcus faecalis biofilms formed on the tooth substrate. Sodium hypochlorite was used as a positive control. DMSO (dimethyl sulfoxide), the vehicle for the herbal extracts, was used as the negative control.

Materials and Methods:

Extracted human teeth were biomechanically prepared, vertically sectioned, placed in the tissue culture wells exposing the root canal surface to E. faecalis to form a biofilm. At the end of the third week, all groups were treated for 15 min with the test solutions and the control. The results were analyzed both quantitatively and qualitatively.

Results:

Statistical analysis was performed by using one-way analysis of variance and compared by the Mann–Whitney test using the Statistical Package for the Social Sciences (SPSS) software, version 20.0. The qualitative assay with the 3-week biofilm on the canal portion showed complete inhibition of bacterial growth for NaOCl, whereas samples treated with herbal solutions showed significant reduction of bacterial growth compared to control group, which showed 139.9 × 10⁹ CFU/mL among the experimental herbal solutions groups. P. amarus has shown maximum bacterial count followed by C. longa and T. indica.

Conclusion:

NaOCl 5% showed maximum antibacterial activity against 3-week biofilm on tooth substrate. T. indica, P. amarus, and C. longa showed statistically significant antibacterial activity against 3-week biofilm. The use of herbal alternatives might prove to be advantageous considering the several undesirable characteristics of NaOCl.

A Comparative Evaluation of Phytic Acid as Final Rinse Solution with Other Chelating Agents for Elimination of Intraradicular Smear: A Scanning Electron Microscopy Study

AIM

The aim of this study was to compare radicular smear layer removal ability of different solutions of phytic acid (PA) with other chelating agents when used in specific irrigant protocols.

MATERIALS AND METHODS

Seventy four maxillary central incisors were collected, standardized, and canals were prepared. A total of 5% sodium hypochlorite was used as the initial rinse solution (8mL). Samples were divided into control (Group I-normal saline and II-7% ethylenediaminetetraacetic acid) and experimental groups (Group III, IV, V, VI, VII, and VIII) based on the type of final rinse solution used, that is, 5% PA, 10% PA, 17% PA, 5% citric acid (CA), 10% CA, and 17% CA (5mL). Samples were coded, buccolingually divided into two halves, dehydrated, mounted, splutter coated, and examined under scanning electron microscope.

RESULTS

Group IV had the least smear and debris in coronal, middle, and apical thirds with mean scores of 1.06 and 1.3, respectively. When compared with Group II, no statistically significant difference was found (P > 0.05). Overall, the Group III had the lowest erosion scores at apical, middle, and coronal one-third with a mean of 1.68. Group VII had the highest amount of erosion with loss of peritubular and intertubular dentin at all levels.

CONCLUSION

The role of PA as final rinse solution for the removal of radicular smear is promising and comparable to other chelating agents.

Analysis of the smear layer generated by different activation systems: an in vitro study

OBJECTIVES

To evaluate via scanning electron microscopy the amount of smear layer generated during the use of sonic and ultrasonic activation systems with standardized short-term intentional contacts with the canal walls.

METHODOLOGY

Seventy single-root human teeth were randomly assigned to 2 control (n = 5 each): NC (negative control), PC (positive control) and four experimental groups (n = 15 each): NC (negative control), PC (positive control), G1 (passive ultrasonic irrigation with Irrisafe), G2 (ultrasonic irrigation with EndoUltra), G3 (sonic irrigation with Endoactivator), G4 (sonic irrigation with Eddy). Samples were instrumented with ProTaper Next®. An irrigation protocol with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) was followed for both PC and the experimental groups. Standardized intentional contacts were made in the mesial walls during 5 s at WL - 2 mm in all experimental groups. Two calibrated evaluators scored the smear layer generated with an ordinal scale by scanning electron microscopy. The weighted kappa coefficient (K_w) was calculated to determine the inter-observer agreement. Post-consensus ordinal data were analyzed using the ordinal (linear) chi-square test.

RESULTS

When the agitation file is in contact with dentine walls, Irrisafe® significantly generated the least amount of smear layer in the coronal third (p < 0.05). Both in the middle and apical third, activation with Irrisafe® also showed statistically significant better results than Eddy™ and EndoUltra®. Endoactivator® showed significant better results than EndoUltra® and Eddy™ in the apical third (p < 0.05).

CONCLUSIONS

Irrisafe generated the least amount of smear layer in the entire canal and similar to Endoactivator in the apical third when the agitation file is in contact with dentine walls.

CLINICAL RELEVANCE

The smear layer is generated during activation. It is common to apply irrigation protocols where after the removal of the smear layer using chelants, a final rinse and activation is carried out but there are no previous studies analyzing the possible creation of a new smear layer with this final activation.

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).

Citation Classics in the Journal of Endodontics and a Comparative Bibliometric Analysis with the Most Downloaded Articles in 2017 and 2018

INTRODUCTION

Bibliometric analysis is the quantitative measure of the impact of a scientific article in its respective field of research. The aim of this study was to identify and analyze the main features of the top 50 most cited articles published in the Journal of Endodontics since its inception as well as the top 50 most downloaded articles in 2017 and 2018 in order to evaluate the changing trends and other bibliometric parameters of the contemporary literature compared with the classic literature.

METHODS

An electronic search was conducted on the Clarivate Analytics Web of Science "All Databases" to identify and analyze the top 50 most frequently cited scientific articles. After ranking the articles in a descending order based on their citation counts, each article was then crossmatched with the citation counts in Scopus, Google Scholar, and PubMed.

RESULTS

The citation counts of the 50 selected most cited articles ranged between 218 and 731 (Clarivate Analytics Web of Science). The years in which most top 50 articles were published were 2004 and 2008 (n = 5). Among 131 authors, the greatest contribution was made by M. Torabinejad (n = 14). Most of the articles originated from the United States (n = 38) with the greatest contributions from the School of Dentistry, Loma Linda University, Loma Linda, CA (n = 15). Basic research-technology was the most frequent study design (n = 18). A negative, significant correlation occurred between citation density and publication age (correlation coefficient = -0.708, P < .01).

CONCLUSIONS

Several interesting differences were found between the main characteristics of the most cited articles and the most downloaded articles.

Antimicrobial effectiveness of etidronate powder (Dual Rinse® HEDP) and two EDTA preparations against Enterococcus faecalis: a preliminary laboratory study

This study aimed to evaluate the antimicrobial and antibiofilm activity of two chelating agents: ethylenediaminetetraacetic acid (EDTA) combined or not with detergents, and etidronic acid combined with sterile saline. The bacterial inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined on Enterococcus faecalis ATCC 4083 strain. Antimicrobial tests were performed on a biofilm model after treatment with the chelating agents at different times (1, 3, and 5 min) using a biofilm eradication concentration (MBEC) and confocal laser scanning microscope (CLSM) assays. Quantification of cell biomass and percentage of live and dead cells in the biomass was assessed for each group. The normality of the distributions for each variable was assessed using the D'Agostino and Pearson's omnibus normality test. The comparison of bacterial viability among groups and between any two groups was performed using the non-parametric Kruskal-Wallis one-way analysis of variance and the Dunn's test, respectively. No significant between-group difference was observed regarding biomass reduction. On the other hand, EDTA combined with detergents displayed a substantial increase of the dead bacteria ranging between 35 and 43%; whereas, the number of cells killed in the control group and in the other treated groups always ranged between 1 and 6%, at all experimental times. The addition of detergents to EDTA can improve its anti-biofilm activity by reducing EPS production and enhancing the killing of sessile bacterial cells. Clinical relevance EDTA presents a relevant antimicrobial activity when combined with surface-active agents.

Comparison of Five Different Irrigation Techniques on Smear Layer Removal in Apical Thirds of Root Canals of Mandibular First Premolar: A Scanning Electron Microscopic Study

Aim:

This study was conducted to compare smear layer removal by five different irrigation techniques—conventional needle irrigation (CI), manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and negative apical pressure (NAP).

Materials and Methods:

Fifty freshly extracted mandibular first premolars were cleaned and shaped by One Curve rotary files and 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. The samples were divided into five equal groups (n = 10), according to the final irrigation activation technique: Group I, CI; Group II, MDA; Group III, PUI; Group IV, SI; and Group V, NAP. The samples were prepared and observed under a scanning electron microscope. The photomicrographs were recorded and evaluated with a scoring system.

Results:

Group I and Group II had the highest scores, which showed a statistically significant difference between the other groups (P < 0.05). This was followed by PUI, NAP, and SI.

Conclusion:

Final irrigation activation with SI and NAP resulted in the better removal of smear layer when compared to that with other groups.

Endodontic Instrumentation

Endodontic instruments are used within the tooth pulp chamber and root canal systems. An understanding of the armamentarium of endodontic instrumentation is necessary in the selection of, and proper use of, these instruments. This proper selection and use of instruments along with the meticulous use of the endodontic triad, can greatly increase the probability of success of endodontic procedures. The endodontic triad is canal preparation, sterilization, and obturation.1 The object of preparation is to prepare the canal to accept obturation with a positive seal and appropriate sealer. This article describes in detail, the types of endodontic instrumentation available.