Distribution of sodium hypochlorite throughout the mesial root canal system of mandibular molars after adjunctive irrigant activation procedures: a micro-computed tomographic study

Comparative evaluation of the effect of ultrasonic and rotary agitation of herbal irrigating solutions on smear layer: A SEM study

Context

Instrumentation and irrigation balance helps in effective removal of endodontic microbes housing inside the smear layer.

Aim

This study aimed to (1) evaluate whether activation of the irrigating solutions with two different systems during the final irrigation step can lead to smear layer formation in the middle and apical third of the root canal and (2) evaluate and compare the smear layer removal ability of the aqueous extracts of Emblica officinalis and Morinda citrifolia.

Materials and Methods

A total of 72 single-rooted teeth were prepared up to F4 ProTaper. The specimens were assigned into eight groups of nine teeth each, according to the final irrigant and activation techniques. Further, the teeth were evaluated under SEM for endodontic smear layer at the middle and apical third.

Statistical Analysis

Inferential statistics included Pearson's Chi-square. Level of significance was set at 0.05 at 95% confidence level.

Results

Ultrasonic activation system showed significant (P = 0.000) amount of smear layer compared to XP-Endo Finisher file. A significant difference (P = 0.00) in the smear layer removal was observed when 6% M. citrifolia was activated with XP-Endo Finisher file both in the middle and apical third.

Conclusion

Within the limitations of this in vitro study, it can be concluded that smear layer formation was noted with ultrasonic and XP-Endo Finisher file when saline was used as an irrigant. 6% M. citrifolia when activated with XP-Endo Finisher file showed best results among all other experimental groups.

Effect of different sealer activation techniques on dentinal tubule penetration

The aim of this study was to evaluate the influence of different activation techniques on dentin tubule penetration of root canal sealer. Seventy-five teeth with single canals were chemomechanically prepared. A calcium silicate-based sealer was stained with a fluorescent dye (rhodamine B), placed into the canals and activated according to the following groups: control (no activation), EDDY, EndoActivator, ultrasonic and XP-Endo Finisher. Then, the samples were obturated. The percentages of sealer penetration at various depth levels of root sections were measured with confocal laser scanning microscopy. XP-Endo Finisher presented the highest penetration at 50 μm (p < 0.05). XP-Endo Finisher showed similar penetration with EDDY at 100 and 200 μm (p > 0.05) while presented higher penetration than the other groups (p < 0.05). At 500 μm, XP-Endo Finisher presented higher penetration than EndoActivator (p < 0.05) while similar penetration with the other groups (p > 0.05). XP-Endo Finisher can be recommended for activation during sealer placement for better penetration into dentin tubules.

Impact XP-endo finisher on the 1-year follow-up success of posterior root canal treatments: a randomized clinical trial

OBJECTIVE

To evaluate the clinical relevance of using the XP-endo Finisher as a supplementary tool to improve the success of root canal treatment of posterior teeth with apical periodontitis, as assessed by 1-year follow-up.

METHODS

A randomized clinical trial was conducted with 92 posterior teeth with apical periodontitis. Root canal treatment was performed using a single reciprocating file, with or without the supplementary use of the XP-endo Finisher. The status of apical periodontitis was assessed using the periapical index (PAI) at baseline and 1 year follow-up. Changes on PAI indicated that the lesions were healed, healing, or not healed. Successful treatments were defined as healed or healing lesions without clinical symptoms. Chi-square analysis and logistic regression were used for data analysis (α = 0.05).

RESULTS

There was no significant difference in the distribution of healing status between the XP-endo Finisher group and the control group (p = 0.690). The success rates were also similar, with 81% in the XP-endo Finisher group and 78% in the control group. However, gender had a significant impact on success rates, with higher rates observed in females.

CONCLUSIONS

The use of the XP-endo Finisher file as a supplementary tool did not affect the success rate of root canal treatment in posterior teeth with apical periodontitis. The findings indicate that the XP-endo Finisher file has limited clinical relevance in improving treatment outcomes for root canal treatment in posterior teeth with apical periodontitis.

CLINICAL TRIAL REGISTRATION

The study protocol was registered in the Brazilian Clinical Trials Registry under identification number RBR-76w7cj (June 19, 2018).

Enhancing debris removal in curved canals: a comparative evaluation of XP-endo Finisher and Passive Ultrasonic Irrigation

OBJECTIVES

The study aimed to compare the efficacy of XP-endo Finisher and Passive Ultrasonic Irrigation (PUI) in removing hard tissue debris from curved canals.

MATERIALS AND METHODS

Thirty-four mandibular molars with Vertucci's type II mesial canals were scanned in microcomputed tomography before and after preparation with HyFlex EDM, and accumulated hard tissue debris was quantified. Subsequently, the teeth were randomly divided into two groups according to the supplementary procedure: PUI with the Ultra-X insert or XP-endo Finisher. After the intervention, the specimens underwent another scanning. Two separate analyses were conducted, one for the total canal and another for the isthmus area. Unpaired and paired T-tests were used for inter- and intergroup comparisons, with a significance level set at 5%.

RESULTS

Both supplementary methods reduced the amount of debris compared to the initial volume. Remarkably, the XP-endo Finisher achieved a significantly higher percentage of debris removal (71% for the total canal and 74% for the isthmus areas) compared to PUI (41% for the total canal and 52% for the isthmus area) (P < 0.05).

CONCLUSIONS

Both supplementary approaches reduced the amount of hard tissue debris from canal preparation, still XP-endo Finisher showed a higher reduction compared to PUI (p < 0.05).

CLINICAL RELEVANCE

None of the supplementary methods rendered canals completely free of hard tissue debris. However, the supplementary approach with XP-endo Finisher resulted in lower levels of hard tissue debris than PUI in curved canals with isthmuses.

Is XP-endo Finisher a better treatment option for its efficacy against intracanal bacteria for post-treatment apical periodontitis cases than EndoActivator?

To investigate the efficacy of the supplementary use of a rotary agitation method [XP-endo Finisher (XPF)] and sonically-activated irrigation [EndoActivator (EA)], using droplet digital PCR (ddPCR) on reducing the bacterial load in previously root canal treated teeth with apical periodontitis. Twenty patients with post-treatment apical periodontitis were allocated into two groups according to the irrigation activation method used: XPF and EA group. Total bacterial loads, as well as the amount of Enterococcus faecalis (E. faecalis) were determined before (S1) and after (S2) chemomechanical preparation, and after final irrigation activation (S3) by means of ddPCR. The bacterial copy numbers were compared between groups using the Friedman test (Nonparametric Repeated Measures ANOVA). When the groups were examined in terms of gender, age, number of root canals, periapical index score, sterility control total bacteria (SCTB), S1- and S2-total bacteria copy number, it was found that there was no statistical difference between the XPF group and the EA group (p > 0.05). Subsequent activation (S3) resulted in a significant microbial reduction in both XPF and EA groups, both of which reduced significantly more bacteria than chemomechanical instrumentation (S2) (p < 0.0001). On the contrary, S3-total bacteria copy number of the EA group was lower than the XPF group (p < 0.0147). There was no statistical difference between the XPF group and the EA group in terms of E. faecalis copy number (p > 0.05). Although both the XPF and the EA optimised the antibacterial efficiency of chemomechanical preparation in previously root canal-treated teeth with apical periodontitis, a lower total bacterial copy number was achieved with the EA application than the XPF application.

The efficacy of a novel SWEEPS laser-activated irrigation compared to ultrasonic activation in the removal of pulp tissue from an isthmus area in the apical third of the root canal

This study aimed to evaluate the efficacy of Shock Wave Enhanced Emission Photoacoustic Streaming (SWEEPS) in the removal of remaining pulp tissue from the root canal isthmus area in lower molars and compare it with ultrasonically activated irrigation (UAI) and conventional needle irrigation (NI). Forty-one lower molars with isthmuses between mesial canals were included in the study. The teeth were randomly distributed into experimental groups (n = 12/each) based on the final irrigation protocol (SWEEPS, UAI, or NI) and a control group (C) (n = 5). The traditional access cavity of the mesial part of each tooth was made in all samples. The mesial root canals in the experimental groups were instrumented with a Wave One Gold Primary (25/.07) file using 3% sodium hypochlorite (NaOCl) while the distal canal served as a control for the presence of pulp tissue. No treatment was performed in the C group. Sections from the isthmus region were processed for histopathology to measure the remaining pulp tissue (RPT). The results were analyzed using analysis of variance and the Kruskal-Wallis test (α = 0.05). There were no significant differences in the relative surface area of root canals and isthmus among the groups (p > 0.05). Samples in the SWEEPS group had significantly less RPT than UAI, NI, and C (p = 0.003, 0.014, 0.003, respectively). There were no significant differences between the UAI and NI (p = 0.583). SWEEPS was the most efficient in debridement of the root canal isthmus area. UAI and NI showed similar but lower efficiency.

Mechanical activation with Easy Clean device enhanced organic tissue removal from simulated internal root resorption in a laboratory evaluation

BACKGROUND

Considering the irregular shape of the root canal, removing inflamed pulp and granulation tissue completely from internal resorption cavities during chemomechanical preparation can be challenging. This study aimed to evaluate the effectiveness of passive ultrasonic irrigation (PUI) compared to mechanical activation with Easy Clean in the removal of organic tissue from simulated areas of internal root resorption.

METHODS

The root canals of 72 extracted single-rooted teeth with oval canals were instrumented with Reciproc R25 instruments. After root canal preparations, the specimens were split longitudinally, and semicircular cavities were prepared using a round bur on each half of the roots. Samples obtained from bovine muscle tissue were weighed and adapted into semicircular cavities. The roots were reassembled and joined, and the teeth were divided into six groups (n = 12) according to the irrigation protocol: Sodium hypochlorite (NaOCl) without activation; NaOCl + PUI; NaOCl + Easy Clean; distilled water without activation; distilled water + PUI; and distilled water + Easy Clean. After irrigation protocols, the teeth were disassembled, and the remaining organic tissue was weighed. Data were analyzed by two-way ANOVA and Tukey's post hoc test (p < 0.05).

RESULTS

None of the experimental protocols totally removed the bovine tissue from simulated cavities. Tissue weight reduction was significantly affected by the activation method (p < 0.05) and by irrigation solution (p < 0.05). Groups with NaOCl irrigation presented higher tissue weight loss when compared to distilled water, for all irrigation methods (p < 0.05). The use of Easy Clean resulted in the greatest tissue weight loss (42.0%-Distilled water/45.5%- NaOCl) compared to those of PUI (33.3%-Distilled water/37.7%- NaOCl) and no activation (33.4%-Distilled water/38.8%- NaOCl) (p < 0.05). However, no differences were observed between PUI and no activation groups (p > 0.05).

CONCLUSIONS

Mechanical activation with Easy Clean enhanced organic tissue removal from simulated internal resorption more effectively than PUI. Easy Clean for agitation of the irrigating solution is effective in removing simulated organic tissues from artificial internal resorption cavities, being an alternative to the use of PUI.

Comparable Effectiveness of Photon-Induced Photoacoustic Streaming with XP-Endo Finisher and Passive Ultrasonic Irrigation on Removing Residual Root Canal Filling Materials from Oval Canals

Objective: This study aimed to evaluate the effectiveness of photon-induced photoacoustic streaming (PIPS), XP-endo Finisher (XPF), and passive ultrasonic irrigation (PUI) for the removal of root canal filling materials from oval root canals. Background: Various adjunctive irrigation techniques following mechanical preparation have been applied to enhance removal of fillings during root canal retreatment. However, whether there is superiority of one approach over others remains controversial. Methods: Thirty extracted single-rooted teeth with oval-shaped canals were instrumented with the ProTaper Next (PTN) system and obturated with the warm vertical compaction technique. After storage at 37°C for 1 month, retreatment was performed with the PTN system up to size X4. The teeth were then randomly assigned into three groups (n = 10) that were, respectively, subjected to supplementary irrigation with different protocols: PIPS, PUI, and XPF, followed by measurement of filling material volumes using high-resolution micro-computed tomography. Results: The PTN preparation resulted in significant reductions in residual filling materials (p < 0.05), whereas PIPS, PUI, and XPF moderately improved the removal of the remnants (p > 0.05). The residual filling materials after supplementary irrigation ranged from 0.384 ± 0.181 to 0.421 ± 0.143 mm³ in oval canals. There was no significant difference in the effectiveness among the PIPS, PUI, and XPF approaches (p > 0.05). Conclusions: Mechanical preparations are useful for removing most root fillings during retreatment in oval-shaped canals. PIPS can reduce residual root-filling materials to the similar extent as PUI and XPF.

Root and canal anatomy of mandibular first molars using micro-computed tomography: a systematic review

BACKGROUND

A thorough understanding of root and canal anatomy is crucial for successful root canal treatment outcomes. This systematic review aims to explore the published micro-CT studies investigated the anatomy of root and canal system in permanent mandibular first molars.

METHOD

An electronic search was performed on Web of science, PubMed, and Scopus. Micro-CT journal studies investigated the root and canal anatomy of permanent double-rooted mandibular first molars were included. Data on study characteristics, objectives of interest, specifications of the studies, and micro-CT specifications were extracted. Risk of bias assessment (ROB) of the included studies was performed using Anatomical Quality Assessment (AQUA) tool. The extracted data were presented in tables and figures to present and synthesise the results. A meta-analysis was performed for the studies related to the prevalence of Vertucci's canal configurations, middle mesial canal (MMC) configurations, and Fan's isthmus types.

RESULTS

Amongst 1358 identified studies, thirty met the inclusion criteria. In terms of the objectives, the selected studies showed high anatomical variability in mandibular first molars. Twenty-two (73%), 25 (83%), and 12 (40%) of the studies reported the population/ethnicity, micro-CT specifications, and ethical approval, respectively. 28 (93%) studies did not disclose the method of sample size estimation. In only 6 (20%) of the studies, the authors had calibrated the assessment approaches. Mostly, a potential ROB was reported in domain 1 (objective(s) and subject characteristics) and domain 3 (methodology characterization). Whilst, low risk was reported in domains 2 (study design), 4 (descriptive anatomy), and 5 (reporting of results). The overall ROB was reported to be ''moderate'' in the vast majority of the studies (27/30). Meta-analysis results showed high levels of heterogeneity among the studies related to MMCs (I² = 86%) and Fan's isthmus (I² = 87%). As for the root canal configuration, pooled prevalence showed that Vertucci type IV and type I were the most prevalent in mesial and distal root canals, respectively.

CONCLUSION

Based on moderate risk of bias level of evidence, micro-CT studies have shown wide range of qualitative and quantitative data presentations of the roots and canals in mandibular first molars. Protocol and registration. The protocol of this systematic review was prospectively registered in the Open Science Framework database ( https://osf.io ) on 2022-06-20 with the registration number 10.17605/OSF.IO/EZP7K.

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.

Effect of different irrigation activation techniques on irrigation penetration into the simulated lateral canals

This study, in which a hundred human teeth with single straight canal were used, focused on the evaluation of contrast solution penetration ability into the simulated lateral canals activated by XP-endo Finisher (XPF), EDDY, Nd:YAG, and Er:YAG laser systems with three different observation methods. The root canals were prepared up to X4 at working length using the ProTaper Next system. The teeth were decalcified and simulated lateral canals were created with #8 K-file at 2, 4, and 6 mm levels. Then the teeth were cleared using methyl salicylate and divided into 5 equal groups according to irrigation activation techniques (CSI, XPF, EDDY, Nd:YAG, and Er:YAG laser). After the contrast solution was activated, images of the simulated lateral canals were obtained by a dental microscope, digital radiography, and CBCT. The contrast solution penetration scores at the 2, 4, and 6 mm levels according to irrigation activation techniques and observation methods were analyzed statistically using Kruskal-Wallis non-parametric analysis of variance Bonferroni test post hoc comparisons. With the other 2 parameters are ignored, the highest and lowest contrast solution penetration were observed at 6 and 2 mm simulated lateral canal levels (p < 0.05), in Er:YAG irrigation activation and CSI technique (p < 0.05), and in direct visual and digital radiographic observation method (p < 0.05), respectively. Within the limits of this study, it was determined that the contrast solution penetration into the simulated lateral canals decreased from the coronal to the apical and achieved with the most effective Er:YAG laser activation technique. In addition, direct visual observation was found to be the best method for the assessment of contrast solution penetration.

Analysis of the Efficacy and Safety of Pulpitis Treated with Different Root Canal Flushing Fluids Based on VAS and Temporomandibular Joint Function

Pulpitis is one of the common diseases indicated by the department of stomatology that is located in the tooth and contains abundant nerve vessels. In order to evaluate the pain degree and functional recovery of patients after treatment by visual analogue pain scale (VAS) and temporomandibular joint function score, a retrospective analysis was performed on 128 patients diagnosed with pulpitis who received root canal treatment in the department of stomatology from January 2020 to March 2021. The results show that 3%NaClO combined with 0.9% sodium chloride injection can effectively relieve the pain degree of patients after treatment, and the antibacterial effect is significantly better than 3%H2O2 combined with 0.9% normal saline. Meanwhile, it can effectively improve the temporomandibular joint function and reduce the recurrence rate, which has good clinical application value.

Successful regenerative endodontic treatment in a tooth with incomplete root apex and posttreatment apical periodontitis: A case report

This case report describes the procedure and outcome of regenerative endodontic treatment (RET) in a tooth with incomplete root apex and posttreatment apical periodontitis. A 44-year-old patient was referred to the endodontist because of a periapical lesion on tooth #21 and a recent episode of acute periapical abscess. On clinical and radiographic examination, this tooth presented with tenderness to percussion and palpation, periapical radiolucent lesion, external apical resorption, and incomplete apex formation. After coronal access, the filling material was removed, and the canal was gently prepared with hand files, using 1% NaOCl as the main irrigant followed by final irrigation with 17% EDTA, activated with XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The root canal was filled with a double antibiotic paste with ciprofloxacin and metronidazole (1:1). After three weeks, RET was performed by stimulating bleeding into the canal, and when a clot was formed, a bioceramic (EndoSequence BC Sealer, Brasseler USA, Savannah, GA) plug was placed on it, followed by coronal restoration. The tooth remained asymptomatic since RET was concluded. Clinical and radiographic follow-ups showed complete repair of the apical periodontitis lesion and the absence of symptoms after eight months. This satisfactory outcome was confirmed after 34 months.

Key words:Bioceramic material; ciprofloxacin; metronidazole; persistent apical periodontitis; regenerative endodontic treatment.

Impact of agitation/activation strategies on the antibiofilm potential of sodium hypochlorite/etidronate mixture in vitro

Background

To investigate the effect of a rotary agitation method or ultrasonically activated irrigation on the antibiofilm effect of a mixture of sodium hypochlorite (NaOCl) and etidronate (1-hydroxyethylidene-1,1-bisphosphonate, HEBP) using a dual-species biofilm model in root canal system.

Methods

Mature dual-species biofilms of Enterococcus faecalis and Streptococcus gordonii were formed in root canals of mandibular premolars. Teeth were randomly allotted (n = 12) to group 1, XP-endo Finisher (XPF); group 2, ultrasonically activated irrigation (UAI); group 3, syringe-and-needle irrigation (SNI). In all groups, canals were instrumented with a rotary instrument (XP-endo Shaper) prior to irrigant agitation/activation. A mixture containing 2.5% NaOCl and 9% HEBP was used throughout the experiment. Bacterial counts from the canal were determined using qPCR before preparation (S1), after preparation (S2), and after final irrigation agitation/activation (S3). Bacterial viability within the dentinal tubules in the coronal, middle and apical root-thirds was quantified using confocal microscopy after Live/Dead staining. The bacterial counts and viability were compared between groups using one-way ANOVA and post-hoc Tukey’s tests. Paired t-test was used to compare the bacterial counts within groups.

Results

Instrumentation alone could significantly reduce the microbial counts in all the groups (P < 0.0001). Subsequent agitation/activation resulted in significant microbial reduction only in XPF and UAI (P < 0.05), both of which reduced significantly more microbial counts than SNI (P < 0.05). Live/Dead staining revealed that XPF and UAI showed significantly greater percentage of dead bacteria within the dentinal tubules than SNI in the coronal third (P < 0.05); UAI resulted in the significantly highest percentage of dead bacteria in the middle third (P < 0.05); while there was no significant difference between the groups in the apical third (P > 0.05).

Conclusions

When using the sodium hypochlorite/etidronate mixture for irrigation, final irrigant agitation/activation with XP-endo Finisher or ultrasonic can improve disinfection of the main root canal space and the dentinal tubules in the coronal third, while ultrasonically activated irrigation appears to exhibit better disinfection within dentinal tubules in the middle third.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02222-1.

Influence of different agitation techniques on bacterial reduction in curved root canals

The aim of this study was to evaluate the influence of agitation techniques on bacterial reduction in curved root canals. Eighty human mandibular molars were prepared, inoculated with Enterococcus faecalis and incubated at 37°C for 60 days. Then, specimens were randomly separated into two test groups (n = 36) and two control groups (n = 04) according to agitation technique: Passive ultrasonic irrigation (PUI, Irrisonic) and XP-endo Finisher (XPF). Microbial samples were collected before and after instrumentation and after final agitation using sterile paper points. Bacterial growth was analysed by turbidity of culture medium and UV spectrophotometry. The Wilcoxon rank test was used for the paired analysis, while the Mann-Whitney U-test was used for the non-paired analysis. The samples collected after final agitation were significantly different between test groups (p < 0.05). Bacterial reduction was greater in the PUI than in the XPF (p < 0.05) group. The irrigant agitation provided significant bacterial reduction. The use of the PUI showed better results.

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.

Different biomechanical preparation protocols on the penetration and bond strength of the filling material to dentin

The aim of this study was to evaluate the influence of different instruments and mechanisms of agitation of the irrigating solution on the penetration by confocal laser scanning microscopy (CLSM), and the bond strength (BS) of the filling material to the dentin by push-out test. Human premolars were distributed in two experimental groups (n=30), according to the instrumentation system: ProTaper Next (PN) or XP-endo Shaper (XS) and three irrigation protocol (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). The 2.5% NaOCl and 17% EDTA were the irrigating solutions used. The filling was performed using a lateral condensation technique, with AH Plus added to 0.1% rodhamine B. The roots were sectioned, obtaining 2 slices for each third of the root. The first slice was submitted to the sealer penetration analysis and the push-out test. The second slice was submitted to qualitative analysis (SEM) of the union interface. For the penetration (%) Tukey showed that PNXF (82.38±13.48), PNPUIXF (82.48± 12.02), XSXF (82.24±11.28) and XSPUIXP (86.23±10.45) presented the highest values, different (p<0.05) from PNNv (68.29±15.12) and XSNv (71.41±16.50). The BS (MPa) test evidenced that in the cervical third, PNPF (4.92±1.04) and XPSPF (5.03±0.70) obtained the highest values differing from the others groups (p<0.05). CSLM and SEM showed greater penetration of the sealer on the entire length of the root canal when the irrigation solution was stirred. In conclusion that the association PUI and XP-endo Finisher favored the penetration and bond strength of the filling material to the root dentin.

Impact of irrigation protocols with some chelators and mechanical agitation on intratubular decontamination

This study evaluated main canal and intratubular decontamination using different irrigation solutions followed by adjunctive agitation steps for infected root canals. Sixty-eight lower incisors were contaminated with Enterococcus faecalis and allocated to groups according to canal treatment (n = 10): G1, NaOCl followed by ethylenediaminetetraacetic acid (EDTA); G2, a mixture of NaOCl with hydroxyethylidene bisphosphonate (HEBP); and G3, NaOCl followed by EDTA-T (EDTA with sodium lauryl ether sulfate). All three groups of teeth were agitated with passive ultrasonic irrigation (PUI) using saline solution, whereby G4, G5, and G6 were prepared as above, and agitation was performed using an XP-Endo Finisher instrument. Microbiological samples were collected from the root canals with paper points at three times: before and after chemomechanical preparation and after agitation. The colony-forming units (CFU)/mL count was determined, and bacterial intratubular viability was analyzed via confocal laser scanning microscopy using Live/Dead staining. Statistical analysis was performed using a Kruskal-Wallis test followed by Dunn tests. A Friedman test was applied for colony-counting data (α = 0.05). CFU/mL counting indicated equally effective decontamination in the experimental groups (p > 0.05). According to microscopy images, the use of irrigation solutions followed by agitation with the XP-Endo Finisher yielded better results. Moreover, NaOCl+EDTA-T followed by XP-Endo Finisher resulted in significantly lower viability than in the PUI-activated groups (p < 0.05). The cervical and medium thirds of the specimens presented similar results. Overall, NaOCl+EDTA-T exhibited the best intratubular antibacterial activity, mainly for canals that were subsequently agitated using XP-Endo Finisher.

The effectiveness of the supplementary use of the XP-endo Finisher on bacteria content reduction: a systematic review and meta-analysis

Objectives

This systematic review evaluated the efficacy of the supplementary use of the XP-endo Finisher on bacteria content reduction in the root canal system.

Materials and Methods

In-vitro studies evaluating the use of the XP-endo Finisher on bacteria content were searched in four databases in July 2020. Two authors independently screened the studies for eligibility. Data were extracted, and risk of bias was assessed. Data were meta-analyzed by using random-effects model to compare the effect of the supplementary use (experimental) or not (control) of the XP-endo Finisher on bacteria counting reduction, and results from different endodontic protocols were combined. Four studies met the inclusion criteria while 1 study was excluded from the meta-analysis due to its high risk of bias and outlier data. The 3 studies that made it to the meta-analysis had an unclear risk of bias for at least one criterion.

Results

No heterogeneity was observed among the results of the studies included in the meta-analysis. The study excluded from the meta-analysis assessing the bacteria counting deep in the dentin demonstrated further bacteria reduction upon the use of the XP-endo Finisher.

Conclusions

This systematic review found no evidence supporting the supplementary use of the XP-endo Finisher on further bacteria counting the reduction in the root canal.

Candida albicans Antimicrobial and Antibiofilm Activity of Novel Endodontic Solvents

Background: Candida albicans is the most prevalent fungi isolated in endodontic infections. In this study, the ability of C. albicans biofilm to tolerate the novel solvent mixtures methyl ethyl ketone (MEK)/tetrachloroethylene (TCE) and MEK/orange oil (OOil) sequentially to the standard irrigation of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic (EDTA) was evaluated. Methods: Biofilm cell cultures of C. albicans SC 5314 were treated sequentially with NaOCl and EDTA and exposed to MEK/TCE or MEK/OOil. The effect of the antimicrobial treatment was evaluated using the disk diffusion method for planktonic culture, and the enumeration of colony-forming units (CFUs) and scanning electron microscope (SEM) for biofilm cell culture. Results: C. albicans mature biofilm (24 h) was significantly reduced in biomass and cell viability after solvent mixtures’ exposure, compared with the previous NaOCl and EDTA treatments. MEK/OOil combination caused a total reduction of biofilm, while with MEK/TCE, there was a 3-log (CFU/cm2) reduction compared with the sequence NaOCl and EDTA, and a 4-log (CFU/cm2) reduction compared with the control. Conclusions: The additional exposure of a preformed 24 h C. albicans biofilm to novel solvent mixtures MEK/TCE and MEK/OOil caused a positive antibiofilm impact, overcoming the performance of the conventional endodontic irrigating protocol.

Antibacterial Ability of Sodium Hypochlorite Activated with PUI vs. XPF File against Bacteria Growth on Enterococcus faecalis Mature Biofilm

The objectives of the present study were to assess the antibacterial effectiveness of two sodium hypochlorite (NaOCl) concentrations (2.5% and 5.25%) activated by means of two techniques, passive ultrasonic irrigation (PUI) and XP-endo^® Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) (XPF) against bacteria growth in intracanal mature biofilm. Our aim was to determine if the effect of heating up NaOCl at body temperature (BT) contributed to an improvement of the efficacy of XPF. Sixty-two single-canal human roots previously instrumented were infected with E. faecalis inoculum at 0.5 McFarland and incubated at 37 °C for two weeks. Twelve specimens were randomly selected as positive control, and the remaining fifty were divided into five experimental groups (n = 10). The first two were irrigated with 2.5 vs. 5.25% NaOCl at room temperature (RT), activated with PUI, and the other three were irrigated with XPF. Of these three, two were irrigated using 2.5 vs. 5.25% NaOCl at RT and one was irrigated with 5.25% NaOCl at BT. Our results showed that NaOCl was effective in biofilm removal for all experimental groups (p > 0.05), especially in the groups irrigated with 5.25% NaOCl at room temperature (RT) activated with PUI and the group treated with 5.25% NaOCl at BT with XPF. These groups were the most successful ones (p < 0.001). NaOCl, activated with XPF, was as effective as PUI in biofilm removal from the apical third of the canal when it was used at higher concentration and heated up. This study indicates that XPF only reached the efficacy of PUI when NaOCl was heated up.

Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study

INTRODUCTION

This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals.

METHODS

Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction.

RESULTS

Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05).

CONCLUSIONS

The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.

A laboratory study of root canal and isthmus disinfection in extracted teeth using various activation methods with a mixture of sodium hypochlorite and etidronic acid

AIM

To evaluate in a laboratory setting the antibiofilm activity of several irrigating protocols including conventional irrigation, ultrasonic activation and XP-endo Finisher, with a mixture of sodium hypochlorite and etidronic acid in infected isthmuses and root canals of extracted human mandibular molar teeth.

METHODOLOGY

Fifty-six mesial roots of mandibular molars, half of them with a continuous isthmus from the cervical to the apical third between the two root canals (type 1), and the other half with a continuous isthmus from the cervical to the middle third and one canal in the apical third (type 2), were included. The root canals were contaminated for 7 days with an Enterococcus faecalis suspension. There were three experimental groups plus a control group (n = 7 per type of root canal anatomy). All the root canals, except for the control group that was not treated, were chemomechanically prepared and then assigned to one of the experimental groups according to the final adjunctive procedure: conventional irrigation, ultrasonic activation or XP-endo Finisher activation. The irrigating solution used was a combination of 2.5% sodium hypochlorite and 9% etidronic acid, and the final protocols were applied for three cycles of 30 s with a 3 mL volume. The antibiofilm activity was evaluated at each location (root canal and isthmus) and third (cervical, middle and apical) using confocal laser scanning microscopy and the live/dead technique. Statistical analysis was performed using SPSS (descriptive statistics) and SUDAAN (P-value calculations).

RESULTS

Root canals had significantly lower biovolume values than the isthmuses (P < 0.05). The biovolume in the root canals was significantly reduced in all the experimental groups in all the thirds except for conventional irrigation in the apical third (P > 0.05). In the cervical and middle thirds, ultrasonic activation was associated with the lowest biovolumes (P < 0.05), followed by XP-endo Finisher. In the isthmus, disinfection was similar in all the thirds for all the protocols. Conventional irrigation was associated with intermediate values with no significant differences from the control group or from the activated protocols (P > 0.05), although the latter were significantly different from the control group (P < 0.05). No differences were found between ultrasonic activation and XP-endo Finisher in the middle and apical thirds (P > 0.05) in the isthmuses.

CONCLUSIONS

In this laboratory study on extracted teeth, the isthmus was more difficult to disinfect than root canals. In the root canals, ultrasonic activation and XP-endo Finisher had a greater effectiveness than conventional irrigation. In the isthmuses, no differences were observed between the two activation techniques and conventional irrigation.

Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement-A Micro-CT Study

BACKGROUND

This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size.

METHODS

Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents-methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%.

RESULTS

The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p < 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p > 0.05).

CONCLUSIONS

An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.

Electrochemical Disinfection of Experimentally Infected Teeth by Boron-Doped Diamond Electrode Treatment

Disinfection and prevention of re-infection are the decisive treatment steps in endodontic therapy. In this study, boron-doped diamond (BDD) electrodes have been fabricated and used for disinfecting the root canals of extracted human teeth, which had been covered with bacterial biofilms formed by Bacillus subtilis and Staphylococcus epidermidis. The growth of B. subtilis could be successfully impaired, achieving a complete disinfection after 8.5 min treatment time with the success of disinfection depending on the insertion depth of the electrode in the root canal. S. epidermidis could completely be removed after 3.5 min treatment time. A clinically applicable electrode array led to complete disinfection after treatment times of 10 min for S. epidermidis and 25 min for B. subtilis. BDD electrode application allowed for the improved disinfection of root canals and dentin tubules based on a continuous production of reactive oxygen species and their enhanced penetration of dentin tubules most likely due the formation of a continuous stream of small gas bubbles. The treatment times that are required here will be shortened in clinical application, as mechanical shaping of the canal system would precede the disinfection process.