Impact of Ultrasonic Activation on the Effectiveness of Sodium Hypochlorite: A Review

Comparative evaluation of smear layer removal by using different irrigant activation techniques: An in vitro scanning electron microscopic study

Aim

This in vitro study aims to assess and compare the effectiveness of different irrigation activation techniques in removing the smear layer from the root canal dentin using Scanning electron microscope (SEM) analysis.

Materials and Methods

A total of 60 extracted single-rooted premolar with straight canal and mature apex were used for this study. After the selection of teeth, all the samples were decoronated followed by biomechanical preparation. The sample after preparation was irrigated with sodium hypochlorite and randomly divided into three groups with 20 sample in each group (n = 20), (Group 1) control, (Group 2) ultrasonic, and (Group 3) laser. The irrigant activation was done in all the groups and then sample was prepared for the scanning electron microscope analysis.

Statistical Analysis

The statistical analysis was performed using the Mann-Whitney-U-test.

Results

The findings suggested that the diode laser irrigant activation technique was superior to the ultrasonic and conventional techniques to eradicate smear layers.

Conclusion

With the limitation of this study, diode laser activation showed better cleaning of root dentinal walls compared to ultrasonic activator and traditional method.

To Evaluate Different Endodontic Instrumentation Systems Regarding Post-Operative Pain After Endodontic Therapy: A Clinical Study

BACKGROUND

Despite substantial breakthroughs in instrumentation systems and pharmaceutical interventions, pain following endodontic therapy remains a serious concern. The effect of the type of endodontic instrumentation system in post-operative pain after endodontic therapy has been a matter of debate.

AIM

To evaluate different endodontic instrumentation systems, namely Reciproc (GmbH, Munich), OneShape® (MicroMega, France), Protaper Gold (Dentsply Sirona, USA), and Hyflex® EDM (Coltène/Whaledent Inc., USA) file systems, regarding post-operative pain after endodontic therapy Methods and materials: The endodontic department treated healthy patients aged 20 to 50 years who were experiencing symptoms of irreparable pulpitis in one or more maxillary molars or mandibular molars. Five hundred was the determined size of the sample. The study participants were divided into five categories, each comprising 100 participants. These categories were: Category 1: Reciproc instrumentation system. Category 2: OneShape® instrumentation system. Category 3: ProtaperGold instrumentation system. Category 4: HyFlex® EDM instrumentation system. Category 5: Control (stainless steel K-files). Following endodontic therapy, these scores were recorded at 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours using the VAS scale.

RESULTS

The visual analog scale (VAS) score (mean±SD) in the control group was 0.73± 0.40 (<0.001). The VAS score in the Reciproc group was 0.43± 0.05 (<0.001). The VAS score in the OneShape® group was 0.36±0.09 (<0.001). The VAS score in the Protaper Gold group was 0.41 ±0.08 (<0.001). The VAS score in the HyFlex® EDM group was 0.55 ±0.02 (<0.001). The VAS score in all instrumentation techniques at 72 hours follow-up was lesser in comparison to a control group with meaningful statistical significance (<0.001). However, the post-operative pain among the Reciproc, OneShape®, Protaper Gold, and HyFlex® EDM instrumentation systems was not different clinically when compared among themselves. However, VAS values were greater in OneShape® and HyFlex® EDM compared to Reciproc and Protaper Gold, showing increased post-operative pain in OneShape and HyFlex® EDM compared to Reciproc and Protaper Gold. It was also observed that there was a decline in the VAS score in all instrumentation systems as the follow-up period increased from 6 hours to 72 hours, with maximum post-operative pain at 6 hours of follow-up and minimum post-operative pain at 72 hours of follow-up. However, the decline was lesser in OneShape® and HyFlex® EDM in comparison to Reciproc and Protaper Gold, with increased post-operative pain in OneShape® and HyFlex® EDM in comparison to Reciproc and Protaper Gold.

CONCLUSION

Post-operative pain at all follow-ups of endodontic procedures was less in Reciproc, OneShape®, Protaper Gold, and HyFlex® EDM than in the control group. VAS scores were higher in the OneShape® and HyFlex® EDM groups compared to the Reciproc and Protaper Gold groups, indicating increased post-operative pain with OneShape® and HyFlex® EDM instruments in comparison to Reciproc and Protaper Gold.

Advances in the Role of Sodium Hypochlorite Irrigant in Chemical Preparation of Root Canal Treatment

Irrigation of root canal system is of great significance to the success of endodontic treatment, where sodium hypochlorite (NaOCl) is the most widely used irrigant in chemical preparation. NaOCl functions by eliminating bacterial biofilms and dissolving organic tissue, which may vary according to several factors such as the microbiology of root canal infection and the concentration of the irrigant. It has been proposed that the effectiveness of NaOCl could be enhanced via several methods, including heating the irrigant, applying in conjunction with certain reagents, or activating by agitation techniques. Despite its antibacterial and tissue-dissolving capacities, NaOCl should be used with caution to avoid detrimental effect due to its cytotoxicity and negative effect on dentin properties. In this narrative review, we discussed the factors that affect the properties of NaOCl, the methods to improve its efficacy, and the side effects that might occur in clinical practice.

A Scoping Review of Highly Cited Published Articles in the Iranian Endodontic Journal: A Reflection of Trends in Endodontic Research

Introduction

Highly cited published articles play a critical role in shaping clinical practice, research directions, and advancements in a specific field of science. The current comprehensive scoping review aimed to provide an overview of highly cited articles published in the "Iranian Endodontic Journal" (IEJ), based on the IEJ's H-index (=29); highlighting their key findings and prominent implications in the field of endodontics.

Materials and Methods

A systematic search was conducted in Scopus database to identify the top 29 highly cited published articles. The articles were selected based on their citation count (h-index); reflecting their impact and influence within the scientific community. Data extraction was performed to gather relevant information; including authors, titles, publication years, and the main topic(s) of each article.

Results

The selected highly cited published articles covered a broad range of endodontic topics; demonstrating the diversity and depth of research in the field. Key findings include significant contributions in vital pulp therapy, antimicrobial agents, root canal disinfection, regenerative techniques, cone-beam computed tomography applications, and intracanal medicaments. The distribution of research areas reflects the importance of evidence-based practice in clinical decision-making and patient care.

Conclusions

These highly cited published articles have shown to have substantial impact on the field of endodontics. They have influenced clinical practice, guided research directions, and have improved patient care. The summary of key findings from each topic and the number of articles related to each area can provide readers with valuable insights into the distribution of research areas, and the significance of contributions made by the aforementioned highly cited published articles.

Assessment of Dentinal Tubules Penetration by Hyben X Delivered into the Root Canal System as an Irrigant; An in Vitro Study

Introduction

Disinfection of the root canal system is crucial for a successful endodontic treatment. Several factors influence the performance of effective irrigation. Diverse irrigating substances have been used but none has proved to completely penetrate the root canal system. HybenX dries biofilm due to its hygroscopic properties; therefore, it is effective in the treatment of biofilm-related diseases. This investigation aimed to estimate HybenX's degree of penetration into the dentinal tubules of upper first premolars.

Materials and Methods

Experimental in vitro intervention where 30 extracted maxillary premolars were evaluated to determine HybenX's degree of penetration and 5% sodium hypochlorite in the dentinal tubules using three different irrigation techniques (passive ultrasonic irrigation, dynamic manual irrigation and conventional single jet irrigation technique). After preparation, the root canals were irrigated with fluorescent rhodamine 6G; then 500-micrometer sections were made to be analyzed under a fluorescence microscope. Measurements were made in micrometer in ZEN software to determine the penetration degree of each substance in the different root thirds.

Results

In the apical third, significant differences between the 3 irrigation techniques were found (P<0.05), similarly, for the middle and cervical thirds. Significant statistical differences between the HybenX and sodium hypochlorite were found at the cervical and middle levels when using the conventional Monoject irrigation and passive ultrasonic irrigation techniques. As for the apical level, differences were found between the passive ultrasonic irrigation techniques and the dynamic manual irrigation technique.

Conclusions

Based on this in vitro study, HybenX proved to highly penetrate into the dentinal tubules, especially when using the passive ultrasonic irrigation technique. HybenX may be a useful option for root canal irrigation in endodontics.

An approach of preserving a mandibular primary second molar by a hemisection procedure: A case report with 36-month follow up

Primary teeth play a crucial role in functional, aesthetic and speech tasks. They are also responsible for maintaining the jaw space for successor permanent teeth. Thus, dentists should understand that extraction might be the easiest decision but not always the correct one, especially, in the case of multiple loss of primary molars. On the other hand, endodontic treatments should be accurately diagnosed - necrotic and irreversibly inflamed teeth - and performed with suitable dental tools and materials. Then it is important to provide a good sealing with a suitable final restoration. This case report discusses an approach for preserving a mandibular primary second molar which had a radiographic lesion in the mesial root and the furcation area with multiple loss of primary molars (before eruption of first permanent molar). This treatment was done by performing a root canal treatment (pulpectomy) just for the distal root and a hemisection procedure by extracting the mesial root, followed by applying SSC crown and space maintainer (band and loop). To conclude, this type of treatment should be temporary until the eruption of the first permanent molar and then changed to be a lingual arch appliance. Moreover, hemisection was a suitable alternative approach to extraction over 36 months of following up.

Efficacy of Laser Photoacoustic Streaming in Paediatric Root Canal Disinfection - An Ex-Vivo Study

Background

Various techniques have been employed to enhance the root canal disinfection rate using sodium hypochlorite (NaOCl) as an irrigant. Photon initiated photo-acoustic streaming using lasers is a newer method of endodontic disinfection.

Aim

The aim of this study is to evaluate and compare the efficacy of photo-initiated photoacoustic streaming and conventional irrigation technique using 2.5% NaOCl for root canal disinfection in primary teeth.

Setting and Design

Laboratory setting and ex-vivo design.

Materials and Methods

Twenty extracted primary teeth were selected in which Enterococcus faecalis incubation was done in the root canals and bacterial counts were obtained before the intervention. The teeth were randomly allocated into two groups. Group I samples were irrigated with conventional syringe method using 2.5% NaOCl and Group II samples were irrigated using photon-initiated photo-acoustic streaming method with erbium-doped yttrium aluminum garnet laser (wavelength - 2940 nm). Postintervention samples were obtained, and bacterial colony count was done. Wilcoxon Signed- Ranks Test and Mann-Whitney test were applied to test the intragroup and intergroup differences in the bacterial counts.

Results

Postintervention results showed no bacterial growth in the canals irrigated using Laser (P = 0.004) whereas, fewer bacterial colonies were observed in NaOCl group (P = 0.005). There was statistically significantly higher reduction in E. faecalis counts in Laser Activated irrigation (LAI) group compared to NaOCl group (P < 0.05).

Conclusion

Total elimination of E. faecalis counts was obtained by the use of laser activated NaOCl irrigation in the infected root canals, hence, it can be considered as an effective method for pediatric endodontic disinfection.

Irrigant Agitation Techniques versus Passive Ultrasonic Irrigation for Removing Debris from Curved Root Canals: An Environmental Scanning Electron Microscopic Study

Introduction

The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus mechanical agitation of the irrigant promoted by the EasyClean (EC) and XP-Endo Finisher (XP-F) systems in removing debris from root canal walls, using environmental scanning electron microscopy (ESEM).

Methods and Materials

Twelve curved mesiobuccal canals of mandibular molars were prepared with the ProTaper Next system up to file X2 (25/0.06). The specimens were embedded in flasks containing silicone putty, sectioned lengthwise, and a 4-mm long groove was made on the canal wall of the buccal half of the specimen, extending from 2 mm up to 6 mm short of the apex. Five cross-sectional markings were made along this groove to establish standardized locations for imaging. The same specimens were used to prepare a negative control group (without debris), a positive control group (completely covered by debris), and 3 experimental groups according to the final irrigation protocol employed: PUI, EC or XP-F. ESEM images were obtained and evaluated by 3 examiners. The amount of debris observed on the images was classified according to a 4-category scoring system. The kappa test was used to assess inter-examiner agreement, and the Kruskal-Wallis and Dunn tests were used to compare the scores (P<0.05).

Results

The scores attributed to the PUI, EC, and XP-F groups were statistically similar to those attributed to the negative control group (P>0.05).

Conclusion

Based on this in-vitro study, the mechanical agitation of the irrigant promoted by EC and XP-F was as effective as using PUI to remove debris from the root canal walls.

Effect of Reciprocating and Rotary Systems on Postoperative Pain: A Systematic Review and Meta-Analysis

Introduction

Our study aimed to compare the incidence and intensity of postoperative pain after endodontic instrumentation with reciprocating and rotary systems.

Methods and Materials

An electronic literature search was performed with MEDLINE via PubMed, Scopus, and Web of Science databases from January 2008 to June 2020. Two high-impact endodontic journals were also hand searched. The selection criteria were: 1) Population; patients requiring endodontic treatment (primary or secondary), 2) Intervention and Comparison; endodontic instrumentation with reciprocating versus rotary systems, and 3) Outcome; postoperative pain. We extrapolated all included research data and reported them as dichotomized ordinal variables to evaluate the incidence of pain and continuous variables to assess pain intensity. Standardized mean difference (SMD) was calculated with Inverse Variance method for pain intensity; the incidence of postoperative pain was calculated using relative risk (RR) with the Mantel-Haenszel method. Random-effects model and 95% confidence interval (CI) were used for all meta-analyses. The I² statistic was used to evaluate the statistical heterogeneity among studies (P<0.05).

Results

Twenty-one articles were selected and 17 of them were included in the meta-analysis for the evaluation of postoperative pain in the first 24 h. The meta-analysis was performed in two steps: a) all studies were included; b) subsequently studies with preoperative pain were excluded. A significant difference was observed in the intensity of postoperative pain; with rotary system having more favorable in both steps [a) SMD: 0.27; 95% CI: 0.13 to 0.41; P=0.0002; b) SMD: 0.37; 95% CI: 0.15 to 0.58; P=0.0010]. There was no significant difference in the incidence of pain, and the incidence of mild, moderate and severe pain (P>0.05).

Conclusion

The meta-analysis results revealed that rotary system were the instrument of choice as they had lower intensity of postoperative pain. Further controlled studies are advocated to provide clarification for intensity/incidence of postoperative pain in endodontic treatment with mechanized instruments.

Comparative evaluation of pulp tissue dissolution ability of sodium hypochlorite by various activation techniques: An in vitro study

Background:

The success in endodontic therapy is dependent largely on the absolute elimination of pulp tissue remnants and the maximum reduction of pathologic microbial load present within the root canal system.

Aim:

The aim of this in vitro study was to compare and evaluate the ability of pulp tissue dissolution with and without activation of 5.25% sodium hypochlorite (NaOCl).

Materials and Methods:

Pulp tissue samples collected from intact, noncarious extracted third molars were standardized to 8 mg in each group. These samples were placed in conical Eppendorf tubes of 15 ml with 10 ml 5.25% NaOCl for 4 min and were activated suitably according to the group specifications. All the procedures in this study were carried out at room temperature. The preweighed pulp tissue samples were further weighed again after the dissolution phase, and residual weight loss in each group along with its percentage was obtained. The results were then statistically analyzed using one-way analysis of variance and Tukey post hoc test.

Results:

The maximum amount of pulp tissue dissolution was found in the laser-assisted irrigation group, i.e., NaOCl with Er, Cr: YSGG (P < 0.05) and showed a statistically significant result in comparison with other groups.

Conclusion:

Within the limitations of the study, laser-assisted irrigation with a radial firing tip (NaOCl activated by Er, Cr: YSGG) was the most effective in dissolving the pulp tissue in comparison with other groups. The ultrasonic activation also showed a considerable amount of pulp tissue dissolution comparable to laser-activated irrigation in this study.

Endodontic irrigants: Different methods to improve efficacy and related problems

Shaping and cleaning a root canal system along with the preservation of the surrounding periodontal tissues are the principal goals of an endodontic treatment. While most of the attention is paid to the mechanical aspects of a root canal treatment, an essential feature of it is the irrigation. All over the years, many materials have been used to clean the root canal of a tooth, and certainly, the sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid solutions are the most used and most reliable ones. Putting them inside of a canal is mostly done using a normal syringe, but many techniques have been involved in this process, including the use of sonic/ultrasonic instruments, the use of shaping files, and even laser, to increase the efficacy of irrigant solutions, especially of NaOCl one. Each one of this technique faces some disadvantages, just as the vapor lock effect and the apical extrusion, and has a different action on features such as the reaction rate and the shear stress of an endodontic irrigant solution. In this narrative review, we describe the different features of many irrigant solutions and the different ways of upgrading their efficacy in the cleaning of a root canal system, with the use of tables to summarize the entire description, and drawing the readers' attention to a photographic illustration for a better understanding of the topic.

Reciprocating kinematics leads to lower incidences of postoperative pain than rotary kinematics after endodontic treatment: A systematic review and meta-analysis of randomized controlled trial

Background:

Extrusion of infected debris into the periapical tissue has been cited as the major cause of postoperative pain, regardless of instrumentation technique.

Aim:

Comprehensively review two different kinematics of instrumentation (reciprocating and rotary) and association to the postoperative pain after endodontic treatment.

Methods:

Two investigators performed a systematic review with meta-analysis. MEDLINE/PubMed, Cochrane Library, and Scopus supplied relevant data from studies published until February 2018 to answer the PICO question. Primary outcome was overall postoperative pain, and the secondary outcomes were nature of the pain (mild, moderate, and severe) at 12, 24, and 48 h.

Results:

Ten randomized clinical trials fulfilled eligibility criteria, and five of them were submitted in the meta-analysis. Primary outcome indicated that reciprocating system results in less postoperative pain compared to rotary system (P < 0.05). As a secondary outcome, there was no statistical difference for mild, moderate, and severe pain after 12 and 24 h using reciprocating or rotary systems (P > 0.05). However, the reciprocation system showed less severe pain after 48 h (P < 0.05).

Conclusion:

Rotary motion had a negative impact on postoperative pain after endodontic treatment. Furthermore, after 48 h, more patients presented severe pain under rotary motion. More randomized clinical studies would be helpful.

Efficacy of Different Irrigation Techniques in Removing Ledermix Paste from Simulated Root Canal Irregularities

Introduction

Root discoloration is reported after using Ledermix paste for prevention of external inflammatory root resorption in traumatically injured teeth. Therefore, it seems necessary to remove Ledermix completely from the root canal prior to root canal filling. The aim of this study was to evaluate the efficacy of sodium hypochlorite or alcohol with or without passive ultrasonic irrigation in removing Ledermix from standardized grooves in coronal and apical root canal thirds.

Methods and Materials

Root canals of ten extracted single-rooted teeth were prepared to size 35 and split longitudinally. Standardized grooves were cut in the coronal and apical part of the root canal and filled with Ledermix paste. The reassembled specimens were irrigated with 1% NaOCl or 80% alcohol delivered with a size 30 syringe or with an ultrasonic device. The amount of remaining Ledermix paste was evaluated by three calibrated observers under 30× magnification using a four-grade scoring system. The data was analysed with a nonparametric ANOVA-type method for longitudinal data in factorial experiments. Pairwise comparisons were adjusted by using the Bonferroni corrections (P=0.05).

Results

For the coronal groove, no statistical difference between passive ultrasonic irrigation with NaOCl or alcohol was found (P=0.089). Irrigation with ultrasonically activated alcohol was significantly more effective than manual irrigation irrespective of the irrigant (P=0.0118). Ultrasonic activation of alcohol removed Ledermix paste significantly better from the apical groove than the other irrigation procedures (P<0.05).

Conclusion

This in vitro study showed that ultrasonic activation of alcohol was the most effective irrigation technique for removal of Ledermix paste, especially in the apical third of the root canal.

Comparison of Antimicrobial Substantivity of Six Root Canal Irrigants against Enterococcus faecalis

Introduction

The antimicrobial substantivity of Mixture of Doxycycline, Citric acid, and Tween 80 (MTAD), Tetraclean, Tetraclean NA, Q-Mix, 2% Chlorhexidine (CHX) and Octenisept was assessed in human root dentine blocks infected with Enterococcus (E.) faecalis.

Methods and Materials

A total of 170 dentine tubes were prepared from human maxillary incisors. After crown and apical third removal, cementum was abraded. The remaining center-holed pieces were cut into 4-mm blocks, infected with E. faecalis in Brain Heart Infusion (BHI) broth for 28 days, then randomly divided into 6 experimental groups (n=25) and 2 controls (n=10). At 0, 7, 14, 21 and 28 days, dentine chips were removed from the canals, with sequential round burs with increasing diameters, and collected into freshly prepared BHI broth. After culturing, growing colonies were counted as colony forming units (CFU). Conventional non-parametric tests (Kruskal-Wallis and Mann-Whitney tests) were used to assess intra-group (at different time frames) and inter-group (at each experimental time) differences (P=0.05).

Results

Tetraclean yielded the lowest CFU counts (P<0.001) at each observation time. Tetraclean NA and Q-Mix showed better (P<0.001) substantivity than 2% CHX and MTAD (except for Q-Mix versus MTAD at 14 days, P=0.21). Conclusions: In this in vitro study, Tetraclean NA and Q-Mix displayed the best antimicrobial substantivity against E. faecalis after Tetraclean in infected human root dentine. Considering the findings of our study and potential drawbacks of antibiotic-based irrigants, free-antibiotic irrigants may represent viable alternative for final rinse in root canal treatment.

Comparison of Postoperative Pain after Root Canal Preparation with Two Reciprocating and Rotary Single-File Systems: A Randomized Clinical Trial

Introduction:

Root canal preparation techniques may cause postoperative pain. The aim of the present study was to compare the intensity of postoperative pain after endodontic treatment using hand files, single file rotary (OneShape), and single file reciprocating (Reciproc) systems.

Methods and Materials:

In this single-blind, parallel-grouped randomized clinical trial a total of 150 healthy patients aged between 20 to 50 years old were diagnosed with symptomatic irreversible pulpitis of one maxillary or mandibular molars. The teeth were randomly assigned to three groups according to the root canal instrumentation technique: hand files (control), OneShape and Reciproc. Treatment was performed in a single visit by an endodontist. The severity of the postoperative pain was assessed by the visual analogue scale (VAS) after 6, 12, 24, 48 and 72 h. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests.

Results:

The patients in control group reported significantly higher mean postoperative pain intensity at 12, 24, 48, and 72 h compared to the patients in the two other groups (P<0.05). There was no significant difference in mean intensity of postoperative pain between Reciproc and OneShape at 5 time points (P>0.05).

Conclusion:

The instrumentation kinematics (single-file reciprocating or single-file rotary) had no impact on intensity of postoperative pain.

The in Vitro Antibacterial Efficacy of Persian Green Tea Extract as an Intracanal Irrigant on Enterococcus faecalis Biofilm

Introduction:

The aim of this study was to compare the antibacterial effect of Persian green tea extract (GTE) and 2.5% sodium hypochlorite (NaOCl) against Enterococcus faecalis (E. faecalis) as an intracanal irrigant.

Methods and Materials:

Thirty freshly extracted teeth were instrumented and sectioned into mesial and distal segments. The specimens were put into wells containing 2 mL of E. faecalis-containing medium. After 3 weeks, the specimens were removed and divided randomly into three groups (n=20). Each group was exposed to 3 mL of different irrigants for 3 min. Groups 1, 2 and 3 were irrigated with GTE, 2.5% NaOCl and normal saline, respectively. Biofilm formed in the middle third of the root canal was carved by sterile scalpel and cultured in Mueller-Hinton medium. Number of colony forming units (CFU) was counted on each plate. In addition, antimicrobial activity of the irrigants was evaluated by the agar disc diffusion test. The diameter of inhibition zone (IZ) around each irrigant was evaluated. The Kruskal-Wallis and Dunn tests were used to analysis the data.

Results:

While in NaOCl group no bacterial colonies were observed, the mean number of E. faecalis in GTE and control groups were 275±74 CFU/mL (P<0.001) and 119×10⁸±11×10⁸ (P<0.001), respectively. The mean of IZ in NaOCl and GTE groups were 24.35±0.78 and 6.9±0.87 mm, in order of appearance (P<0.001). Zone of inhibition was not observed around the control group (P<0.001).

Conclusion:

This research highlighted the potential role of plant extracts in antimicrobial root canal irrigation protocol.

Outcomes of Endodontic Therapy Comparing Conventional Sodium Hypochlorite Irrigation with Passive Ultrasonic Irrigation Using Sodium Hypochlorite and Ethylenediaminetetraacetate. A Retrospective Analysis

The aim of the present study was to investigate the clinical outcomes of two different standardized endodontic irrigation protocols. It was assumed that the additional use of ethylenediaminetetraacetate (EDTA) and passive ultrasonic irrigation (PUI) would result in an increased rate of absence of symptoms and remission based on the periapical index (PAI) compared to passive irrigation using only sodium hypochlorite (NaOCl).

Data and radiographs from 199 teeth retrieved from the institutional endodontic database were analyzed retrospectively. In 106 teeth irrigation was performed using only NaOCl (protocol 1). Ninety-three teeth were irrigated using NaOCl and EDTA (protocol 2). Chlorhexidine (CHX) was additionally used in revision treatments in both groups. All irrigants in group 2 were activated by PUI.

Mean follow-up periods were: protocol 1 = 9.2 ± 4.4 and protocol 2 = 6.6 ± 2.5 months (p < 0.0001 (chi-square test). The frequencies of the PAI_masterpoint and PAI_follow-up scores did not differ significantly between teeth, which received either protocol 1 or 2 (p = 0.555 and 0.138). Statistical analysis revealed no significant association between treatment success (absence of clinical symptoms and PAI_follow-up = I or PAI_masterpoint > PAI_follow-up > I) and the applied protocol (success rates: protocol 1 = 72.6% vs. protocol 2 = 82.8%; p = 0.203). Furthermore, the frequency of extractions did not differ significantly between the two protocols (p = 0.102). No association was found between follow-up time and treatment success (p = 0.888).

The hypothesis was not confirmed. Even though the obtained success rate was higher after supplementing the irrigation protocol with EDTA and PUI, no significance was recorded. Hence, protocol 2 was not superior to protocol 1 regarding therapy success, at least within the limited follow-up period. It may be cautiously concluded that sufficient mechanical debridement combined with passive NaOCl irrigation results in comparably high success rates compared to EDTA and PUI.

Antimicrobial Efficacy and Cytocompatibility of Calcium Hypochlorite Solution as a Root Canal Irrigant: An in Vitro Investigation

INTRODUCTION

The purpose of this study was to compare the antimicrobial efficacy of sodium hypochlorite (SH) and calcium hypochlorite (CH) against Enterococcus faecalis (E. faecalis) using quantitative real-time polymerase chain reaction (qPCR) analysis and also to compare their cytocompatibility on L929 murine fibroblasts using Mossman's tetrazolium toxicity (MTT) assay.

METHODS AND MATERIALS

A broth micro-dilution susceptibility test was used to determine the minimum inhibitory concentration (MIC) of each irrigant against E. faecalis. Then, the root canals of 50 mature extracted human mandibular premolars were contaminated with E. faecalis and were randomly divided into three groups according to the irrigant used (n=20). Canals were irrigated with SH in group I (n=20) and CH in group II (n=20) at their obtained MIC. In group III (n=10), sterile saline was used. Microbial sampling was performed before and after biomechanical preparation. Quantitative PCR was used to quantify E. faecalis in the root canal samples. For cytocompatibility assessment, L929 murine fibroblasts were exposed to various concentrations of the irrigants.

RESULTS

Irrigation with test materials resulted in significant reduction in colony forming units (CFU) in post-instrumentation samples (with the MIC values of SH and CH against E. faecalis being 0.5% and 5%, respectively). However, the reduction in the normal saline group was not significant (P=0.203). In addition, 5% CH was more effective than 0.5% SH (P=0.006) in eliminating E. faecalis. Among the different concentrations of tested irrigants, 0.5% CH and 5% SH showed the least and the most cytotoxicity, respectively (P<0.001). The cytotoxicity of 5% CH and 0.5% SH was similar (P=0.99), and lower than 2.5% SH (P<0.001).

CONCLUSION

CH at an MIC of 5% was effective in eliminating E. faecalis in planktonic state and also its biofilm and exhibited comparable cytocompatibility to that of 0.5% SH.