Comparative Effectiveness of New Mechanical Irrigant Agitating Devices for Debris Removal from the Canal and Isthmus of Mesial Roots of Mandibular Molars

The various forms of tooth resorption

Tooth resorption refers to the loss of the organic and inorganic components of tooth structure by clastic cells. The complex and multifaceted nature of its aetiology, along with the several classification schemes published in the area, are likely to create confusion amongst researchers and clinicians, and may lead to compromised treatment decisions. Therefore, this paper will categorise and address tooth resorption based on aetiology in order to help clinicians diagnose and filter treatment options based on the pathophysiology of the resorption at hand. With recent advancements in the literature, the purpose of this paper is to provide clinicians with a current, clinically relevant summary of the various forms of tooth resorption, with a focus on aetiologically driven treatment strategies and suggestions that facilitate their recognition, diagnosis and management.

Antibacterial ability of different activated irrigation after root canal preparation: intratubular analyses

This study assessed the intratubular antibacterial ability of different activated irrigations after chemical mechanical preparation. Seventy-two palatal root canals of upper molars were infected with Enterococcus faecalis for 4 weeks, and then initial bacterial collection from the main root canal was performed. The root canals were prepared by using a WaveOne Gold large (45/.05) and distributed into 6 groups according to the activation of the final irrigation: ultrasonic activation (UA), XP-Endo Finisher (25/.00), XP Clean (25/.02), EasyClean (25/.04) in reciprocating motion and continuous rotary motion (ECRot), and conventional irrigation. After final irrigation, another bacterial collection from the main root canal was performed, and the root was sectioned transversely in three-thirds and stained for analysis by confocal laser microscopy. Intratubular bacteria were collected through dentin powder and plated for bacterial viability analysis. Intergroup and intragroup comparisons were performed by using analysis of variance and repeated measures analysis of variance, respectively, both at 5% significance. ECRot had higher antibacterial ability than UA (p<0.05), and both were superior to the other groups (p<0.05) in both methodologies. It can be concluded that activation of final irrigation enhances the disinfection of the root canal system, and activators have different efficacies.

Impact of different agitation methods on smear layer cleaning of mesial canals with accentuated curvature

Objectives

This study evaluated the impact of different methods of irrigant agitation on smear layer removal in the apical third of curved mesial canals of 3 dimensionally (D) printed mandibular molars.

Materials and Methods

Sixty 3D-printed mandibular second molars were used, presenting a 70° curvature and a Vertucci type II configuration in the mesial root. A round cavity was cut 2 mm from the apex using a trephine of 2 mm in diameter, 60 bovine dentin disks were made, and a smear layer was formed. The dentin disks had the adaptation checked in the apical third of the teeth with wax. The dentin disks were evaluated in environmental scanning electron microscope before and after the following irrigant agitation methods: G1(PIK Ultrasonic Tip), G2 (Passive Ultrasonic Irrigation with Irrisonic- PUI), G3 (Easy Clean), G4 (HBW Ultrasonic Tip), G5 (Ultramint X Ultrasonic tip), and G6 (conventional irrigation-CI) (n = 10). All groups were irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid.

Results

All dentin disks were 100% covered by the smear layer before treatment, and all groups significantly reduced the percentage of the smear layer after treatment. After the irrigation protocols, the Ultra-X group showed the lowest coverage percentage, statistically differing from the conventional, PIK, and HBW groups (p < 0.05). There was no significant difference among Ultramint X, PUI-Irrisonic, and Easy Clean (p > 0.05). None of the agitation methods could remove the smear layer altogether.

Conclusions

Ultramint X resulted in the most significant number of completely clean specimens.

Root canal dentin wear during final irrigation in endodontic retreatment with passive ultrasonic irrigation and easy clean instruments

Context

Complementary procedures have been proposed to improve the endodontic retreatments.

Aim

The aim of this study was to evaluate, by microcomputed tomography (micro-CT), the dentin wear caused by passive ultrasonic irrigation (PUI) and easy clean (EC) instruments, when used for the final removal of filling material during endodontic retreatment.

Methods

Thirty-six mesial roots of the lower first molars were divided into four groups (n = 9), according to the final irrigation and sealer: PUI/AH Plus, EC/AH Plus, PUI/Total Fill (TF), and EC/TF. Canal volume was evaluated, both before and after the final irrigation, by micro-CT analysis. The Kruskal-Wallis test was used to compare the volumes among groups and the paired Wilcoxon test was used to compare the volume values before and after the final irrigation within each group.

Results

Both complementary cleaning procedures promoted dentin wear that was observed only when the volume was analyzed for each third of the root canal. In the apical third, both instruments showed significant wear, where the use of the EC instrument resulted in greater wear than the PUI, in teeth filled with both AH Plus and TF BC Sealers (P < 0.05).

Conclusion

Both complementary cleaning procedures promoted dentin wear and must be used cautiously.

The use of sodium hypochlorite mixed with etidronic acid during canal preparation increases debris extrusion

The purpose of this study was to compare the impact of different irrigation protocols on debris extrusion. Single-rooted teeth were distributed into groups based on the irrigation protocols (n = 40): 2.5% NaOCl (biomechanical preparation: 20 mL and final irrigation: 5 mL); 2.5% NaOCl (biomechanical preparation: 20 mL) + 17% EDTA (final irrigation: 2 mL) + 2.5% NaOCl (final irrigation: 3 mL); and a mixture of 5% NaOCl +18% HEDP (biomechanical preparation: 20 mL and final irrigation: 5 mL). The canals were prepared using a reciprocating instrument size 40/0.06. For final irrigation, the groups were reassigned based on the agitation methods (n = 10): (a) no agitation; (b) ultrasonic; (c) sonic; and (d) continuous rotation. The control group (n = 10) received saline solution without agitation. The amount of debris extruded was measured by weight and analysed using One-way ANOVA (α < 0.05). The subgroups treated with NaOCl + HEDP mixture showed a significantly higher amount of extruded debris (p < 0.05), while there was no difference among agitation methods in all groups (p > 0.05).

Impact of the final agitation system in the irrigant diffusion inside the root canal: A micro-CT analysis

This study evaluated, through micro-computed tomography (micro-CT), the volume of irrigant diffusion by different techniques of final agitation. Sixty mesiobuccal canals were scanned in a micro-CT and standardised according to the volume. They were instrumented with the MTwo 40/04 system and using the Terebrix 35 contrast solution as irrigant, were divided into six groups (n = 10): Conventional irrigation with syringe and needle (CI), EndoActivator (EA), EasyClean (EC), RinsEndo (RE), Utrasonic agitation (UI) and XP-Clean (XP). A second micro-CT scan was performed and the total irrigant volume and in the final 3 mm apical were determined. The data were analysed using the Anova, Kruskal-Wallis and Dunn tests (p < 0.05). UI and XP showed a higher percentage of total diffusion than CI, EA and RS groups (p < 0.05). In apical diffusion, there was no significant difference between groups (p > 0.05). The final agitation system increases the diffusion of irrigating agents inside the root canal.

Efficacy of different irrigant activation devices in removing dentin debris from an artificial isthmus connecting curved canals

The aim of this study was to evaluate the debridement efficacy of sonic irrigation (EDDY; VDW, Munich, Germany and EndoActivator; Dentsply-Sirona, Ballaigues, Switzerland) and ultrasonically activated irrigation (Irrısafe; Satelec Acteon, Merignac, France) in a simulated canal isthmus connecting curved canals. Transparent resin blocks were produced containing two curved canals connected with an isthmus. The isthmus was then filled with dentin debris. Three irrigant activation cycles were performed and the amount of remaining debris was compared analysing pictures taken after each activation cycle. Data were statistically analysed using one-way ANOVA and post hoc Tukey tests at a significance level of p < 0.05. EDDY showed greater efficiency in removing dentin debris from the simulated isthmus than the other techniques tested. An increase in the activation time enhanced the efficiency of both EDDY and ultrasonically activated irrigation in debris removal.

Effect of different activation methods on the intratubular penetration of CaOH2 paste: Ex-vivo analysis by confocal laser scanning microscopy

The aim of this study was to evaluate the maximum penetration depth (MPD) and penetration area (PA) of CaOH2 paste agitated by different methods and to measure the pH after performing these methods. Fifty-five mandibular premolars were divided into control, GL and 4 experimental groups, GEC, GXP, GEDDY and GI (n = 11), where the paste was agitated with Easy Clean, XP-endo Finisher, EDDY and Irrisonic, respectively. The canals were instrumented and irrigated with NaOCl. The paste was manipulated with propylene glycol and rhodamine B dye. Root sections were examined using confocal laser scanning microscopy. There was no difference between groups regarding PA (p > 0.05). At 5 mm, MPD was greater in GEC than in GL or GEDDY, and greater in GI than in GL (p < 0.05). At 2 mm, MPD was greater in GEC than in the other groups (p < 0.05). In conclusion, both Easy Clean and Irrisonic promoted deeper paste penetration and were associated with higher pH levels.

Effect of irrigation protocols on smear layer removal, bond strength and nanoleakage of fiber posts using a self-adhesive resin cement

Objectives

This study aimed to investigate the effect of the application method of 2% chlorhexidine (CHX) and its influence on the adhesion of fiberglass posts cemented with a self-adhesive resin cement.

Materials and Methods

Sixty human mandibular premolars were endodontically treated and divided into 5 groups (n = 12), according to the canal irrigant and its application method: 2 groups with conventional syringe irrigation (CSI)-2.5% sodium hypochlorite (NaOCl) (control) and 2% CHX- and 3 groups with 2% CHX irrigation/activation-by passive ultrasonic irrigation (PUI), Easy Clean file, and XP-Endo Finisher file. Two roots per group were evaluated for smear layer (SL) removal by scanning electron microscopy. For other roots, fiber posts were luted using a self-adhesive resin cement. The roots were sectioned into 6 slices for push-out bond strength (BS) (7/group) and nanoleakage (NL) (3/group). Data from SL removal were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS and NL were evaluated by 2-way analysis of variance and Tukey's test (α = 0.05).

Results

For SL removal and BS, the CHX irrigation/activation promoted better values than CSI with CHX (p < 0.05), but it was not significantly different from CSI with NaOCl (p > 0.05). For NL, the lowest values were obtained by the chlorhexidine irrigation/activation groups (p < 0.05).

Conclusions

Active 2% CHX irrigation can be used to improve the post space cleaning and adhesion before fiber post cementation with self-adhesive resin cements.

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.

Irrigants and irrigation activation systems in Endodontics

Root canal infections are typically polymicrobial and involve strong bacterial interactions. The goal of endodontic treatment is to remove infected content from the root canal system to allow the healing of a pre-existing periapical lesion or to prevent infection of the periradicular tissues. Instrumentation alone is not capable of touching all of the root canal walls. Therefore, the irrigation process is an essential step in the endodontic treatment. However, due to the complex anatomy of the root canal system, this cleaning is very challenging. Although syringe and needle irrigation associated with the use of chemical substances is still the most used method, it does not guarantee optimal cleaning of the root canals. As a result, not only alternative irrigating substances but also numerous activation systems - which are technologies that aim to optimize the action of irrigating substances, both chemically and physically - have been developed. This work aimed to review the characteristics of both classic and current alternatives of irrigating substances and irrigation activation systems.

Assessment of the root surface temperature during the use of intracanal agitation systems: In vitro study

This study aimed to evaluate the temperature changes that the different methods of agitation of irrigants promote on the external dental root surface. Nine extracted human lower premolars were standardized by cone-beam computed tomography and used. The root canal was instrumented with a Reciproc 40.06 file. Temperature measurement was performed using K-type thermocouple sensors attached to the middle, cervical, and apical thirds of the teeth. The teeth had their roots immersed in distilled water at 37ºC, which were distributed into 3 experimental groups according to the mechanical agitation methods to be studied. US Group (n=3), Irrisonic Ultrasonic Tip activated through ultrasound; EC Group (n=3), Easyclean Tip coupled to a contra-angle low-speed handpiece; XP Group (n=3), XP-endo Finisher file coupled to an endodontic electrical motor. Temperature measurements were performed simultaneously with agitation and irrigation of intracanal irrigants. Statistical analysis was performed using SPSS software with a significance level of 5%. For multiple comparisons, the Tukey test was used. The association between mechanical agitation methods and root third was statistically significant. Regarding the temperatures recorded on the external surface of the roots, the ultrasonic tip was significantly higher than the XP-endo Finisher file and the Easyclean tip, which did not differ from each other. Regarding the ultrasonic tip, the external temperature in the middle third (39.46ºC) of the root was significantly lower than in the cervical (40.41ºC) and apical third (40.53ºC). None of the agitation methods of irrigants studied presented heating above 47ºC, and their use is safe for periodontal tissues.

Comparative Evaluation of Different Irrigant Agitating Devices for Debris Removal from the Mesial Roots of Mandibular Molars: An In Vitro Study

AIM

To evaluate the efficiency of debris removal from the mesial root canals and isthmus of mesial roots of mandibular molars after final irrigant agitation with XP-endo Shaper, EndoVac (EV), plastic finishing file, and conventional needle irrigation.

METHODS AND MATERIALS

Forty extracted human mandibular first molar teeth with the isthmus between the mesial roots were selected, access cavities were prepared and distal roots were decoronated. All the mesial root specimens were mounted in acrylic, sectioned at the coronal, middle, and apical thirds, along with the resin block, and examined for debris in the canals and isthmus before the start of the procedure using a stereomicroscope and were mounted back in a custom-made jig. After determination of the working length, they were allocated to the following four different irrigant activation groups (n = 10): Group I-XP-endo Finisher; group II-EndoVac; group III-plastic finishing file; and group IV-standard needle irrigation. After biomechanical preparation (BMP) till F3, final agitation was done for debris removal with the respective agitating devices, and all the samples were examined under a stereomicroscope for the amount of debris in the canal after final agitation.

RESULTS

Of all the irrigation devices used, the XP-endo Finisher and EV showed more debris removal when compared to other groups (p < 0.05). The plastic finishing file in continuous rotation was more efficient in cleaning debris compared with conventional needle irrigation (p < 0.05).

CONCLUSION

The XP-endo Finisher and EV showed a significant difference in cleaning efficacy than the plastic finishing files. So, these can be used as adjunctive for agitating the final irrigant.

CLINICAL SIGNIFICANCE

The irrigant agitation devices promote the penetration of irrigants into the intricate root canal anatomy and increase their antibacterial and tissue-dissolving effectiveness thereby improving the success rate and treatment outcome.

How does nano-focus computed tomography impact the quantification of debris within the root canal system?

The aim of this study was to compare the quantification of hard-tissue debris by using micro-computed tomography (micro-CT) and nano-focus computed tomography (nano-CT) after root canal instrumentation. Ten mandibular molars containing an isthmus in the mesial root were scanned in a SkyScan 1172 micro-CT device with a voxel size of 12.8 µm and in a NanoTom nano-CT device with 5.5 µm. The mesial root canals were irrigated with 5 mL of saline solution at the orifice level, instrumented with Reciproc R25 files and a second scanning was performed by micro-CT and nano-CT devices for post-instrumentation images. DataViewer software was used for registering the pre- and post-operative micro-CT and nano-CT images. The root canal and the debris were segmented for quantitative analysis of the volume of the canal and volume of debris using CTAn software. Statistical analysis was performed using the T test for comparison between volume of the canal after instrumentation and volume of debris in both image modalities. The level of significance was set at p < 0.05. Nano-CT images showed higher values of debris when compared with micro-CT (p < 0.05) after root canal instrumentation. No difference was observed between the volume of the root canal after instrumentation in the two imaging methods used (p > 0.05). Nano-CT technology can be recommended as a more precise method for quantitative analysis of hard-tissue debris. Moreover, in Endodontic research it is a promising method, as it is capable of providing higher spatial and contrast resolution, faster scanning and higher image quality.

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.

Postoperative pain after using passive ultrasonic irrigation and EasyClean device, irrigation activation techniques: a randomized clinical trial

INTRODUCTION

This randomized clinical trial aimed to compare postoperative pain after the use of two different irrigation activation techniques, passive ultrasonic irrigation and the EasyClean device.

METHODS

Sixty-six single-rooted teeth diagnosed with asymptomatic pulp necrosis and apical periodontitis were randomly assigned to two experimental groups (n=33), which differed in the irrigation activation technique. Postoperative pain levels were assessed after 24, 48, and 72 hours using a verbal rating scale; the ibuprofen intake amount was recorded at the same time intervals. Data were analyzed using Student's t-test, Mann-Whitney U and Fisher's exact tests, with a significance level of 5%.

RESULTS

Postoperative pain levels and analgesic intake frequency were not significantly different across the two irrigation activation techniques (P > .05). The frequencies obtained in relation to the prevalence of postoperative pain were 3.1-25.8% for all participants of the two studied groups.

CONCLUSION

The irrigation activation techniques of passive ultrasonic irrigation and the EasyClean device were found to be equivalent in terms of postoperative pain and analgesic intake.

Efficacy of different irrigant activation techniques for cleaning root canal anastomosis

OBJECTIVE

This study compared in vitro the anastomosis cleaning efficacy of different irrigant activation techniques at different levels; control group non-activation (NA), passive ultrasonic irrigation (PUI) using Irrisafe, and EDDY sonic activation.

METHODS

Sixty anastomosis-containing mesial roots of mandibular molars were mounted in resin, sectioned at 2, 4, and 6 mm from the apex. Then reassembled and instrumented in a copper cube. For the irrigation technique roots were randomly divided into 3 groups (n = 20): group 1: NA, group 2: Irrisafe, group 3: EDDY. Stereomicroscopic images of anastomoses were taken after instrumentation and after irrigant activation. ImageJ program was used to calculate the percentage of anastomosis cleanliness. The percentage of cleanliness was calculated before and after final irrigation within each group and were then compared using paired t-tests. Intergroup and intragroup analyses were performed to compare between different activation techniques at the same root canal level (2, 4 and 6 mm) (intergroup) and to evaluate if each technique had different cleanliness efficacy according to the root canal level (intragroup) using one-way analysis of variance and post hoc tests (p < 0.05).

RESULTS

All three irrigation techniques significantly improved anastomosis cleanliness (p < 0.001). Both activation techniques were significantly better than the control group at all levels. Intergroup comparison revealed that EDDY significantly achieved the best overall anastomosis cleanliness. The difference between EDDY and Irrisafe was significant in favor to EDDY at 2 mm and insignificant at 4 and 6 mm. The intragroup comparison showed that improvement in anastomosis cleanliness (i2-i1) in the needle irrigation without activation group (NA) was significantly higher in the apical 2 mm level compared to the 4 & 6 levels. While the difference in anastomosis cleanliness improvement (i2-i1) between levels in both Irrisafe and EDDY groups was insignificant.

CONCLUSIONS

Irrigant activation improves anastomosis cleanliness. EDDY was the most efficient in cleaning anastomoses located in the critical apical part of the root canal.

CLINICAL RELEVANCE

Cleaning and disinfection of the root canal system followed by apical and coronal sealing is the key for healing or prevention of apical periodontitis. Remnants of debris and microorganisms retained within the anastomoses (isthmuses), or other root canal irregularities may lead to persistent apical periodontitis. Proper irrigation and activation are essential for cleaning root canal anastomoses.

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.

Apical extrusion of sodium hypochlorite in immature teeth: comparison of three different cleaning protocols

This study compared standard needle irrigation, passive ultrasonic irrigation, XP-Endo Finisher and Easy Clean in the apical extrusion of sodium hypochlorite (NaOCl) in a model simulating immature teeth. Ten bovine teeth were maintained in suspension in a container with the apical portion in contact with 0.2% agarose gel containing 0.1% metacresol purple. The canals were irrigated with 2.5% NaOCl, according to each irrigation protocol. After 3 min, apical extrusion of NaOCl was observed by the colour gel change when in contact with NaOCl. The containers were photographed, and the NaOCl extrusion area was measured. All protocols showed NaOCl extrusion, providing similar area (P > 0.05). Considering the similarity among the studied protocols, all of them can be considered during the endodontic treatment of immature teeth. Further studies on the particularities of immature teeth should be performed to evaluate cell viability, cleaning efficiency, disinfection capacity and dentin removal promoted by the irrigation protocols.

Micro-CT evaluation of four final irrigation protocols on hard-tissue debris removal from mesial roots of mandibular molars containing isthmus

OBJECTIVES

To evaluate by means of microcomputed tomography (micro-CT), the efficacy of four final irrigation protocols in the removal of hard-tissue debris (HTD) in mesial roots of mandibular molars containing isthmus.

MATERIALS AND METHODS

Forty standardized mesial roots of extracted mandibular molars presenting isthmus were selected. The root canals were prepared and randomly divided into 4 groups (n = 10): EA, EndoActivator (Dentsply Sirona); EC, Easy Clean (Easy Dental Equipment, Belo Horizonte, Brazil); XPF, XP-Endo Finisher (FKG Dentaire, La Chaus-de Fonds, Switzerland); and PUI, passive ultrasonic irrigation using Irrisafe tip (Satelec Acteon, Merignac, France). Each final irrigation protocol was performed in two cycles (60 s), using, respectively, 2.5% sodium hypochlorite and 17% EDTA. Micro-CT scans were obtained pre-operatory, post-preparation, and post-irrigation. The percentage of HTD reduction was calculated. Data was analyzed statistically (ANOVA and Kruskal-Wallis, significance set at 5%).

RESULTS

The percentage of HTD reduction was greatest for the XPF group (77.92%), followed by EA (62.92%), PUI (47.48%), and EC (32.65%). Statistical differences (p < .05) were found between XPF and EC only. A significant difference (p < .05) was found between XPF and EC in all thirds and between PUI and EC in the middle third.

CONCLUSIONS

XPF, EA, and PUI were similarly effective in HTD reduction. However, none of the evaluated protocols was able to completely remove all the debris.

CLINICAL RELEVANCE

Final irrigation protocols aim to clean the canal complexities that are not addressed by the shaping procedures. Micro-CT allowed to assess the removal of hard-tissue debris in the isthmus and canals of mandibular molars.

Present status and future directions - irrigants and irrigation methods

Irrigation is considered the primary means of cleaning and disinfection of the root canal system. The purpose of this review was to set the framework for the obstacles that irrigation needs to overcome, to critically appraise currently used irrigants and irrigation methods, to highlight knowledge gaps and methodological limitations in the available studies and to provide directions for future developments. Organization of bacteria in biofilms located in anatomic intricacies of the root canal system and the difficulty to eliminate them is the main challenge for irrigants. Sodium hypochlorite remains the primary irrigant of choice, but it needs to be supplemented by a chelator. Delivery of the irrigants using a syringe and needle and activation by an ultrasonic file are the most popular irrigation methods. There is no evidence that any adjunct irrigation method, including ultrasonic activation, can improve the long‐term outcome of root canal treatment beyond what can be achieved by instrumentation and syringe irrigation. It is necessary to redefine the research priorities in this field and investigate in greater depth the penetration of the irrigants, their effect on the biofilm and the long‐term treatment outcome. New studies must also focus on clinically relevant comparisons, avoid methodological flaws and have sufficiently large sample sizes to reach reliable conclusions. Future multidisciplinary efforts combining the knowledge from basic sciences such as Chemistry, Microbiology and Fluid Dynamics may lead to more effective antimicrobials and improved activation methods to bring them closer to the residual biofilm in the root canal system.

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.

Effect of Chemical Debridement and Irrigant Activation on Endodontic Treatment Outcomes: An Updated Overview

Chemical debridement is considered one of the most important steps during root canal treatment to target unreached areas and provide thorough disinfection of the canals. The efficiency of this step efficiency can be increased using different agitation and irrigation techniques/devices. This comprehensive review aimed to summarize the effect of various irrigant activation and agitation techniques/devices on endodontic treatment outcomes. Using mechanical active irrigation, which enables the activation or agitation of the irrigating solution, is beneficial in root canal treatment by increasing the efficiency of delivering the irrigant up to working length and ensuring isthmus cleanliness. However, considerable variation was noticed between the protocols used in each technique with a lack of well-designed randomized clinical trials to focus on the long-term outcome. Moreover, a low level of evidence was noticed regarding the effectiveness of certain activation techniques over others. Therefore, each study needs to be carefully weighed before using its results and embracing its conclusion. Future studies need to focus more on the antimicrobial effect of each technique and its effect on the healing of apical periodontitis. Also, recent advances, such as multisonic and laser activation, are promising tools that need more clinical investigations to show their efficiency.

Impact of sodium hypochlorite on organic tissue dissolution in the periapical region of immature permanent teeth: an ex vivo study

INTRODUCTION

To evaluate the impact of different sodium hypochlorite irrigation protocols on organic tissue dissolution in the periapical region of simulated immature permanent teeth.

METHODS

Eight single-rooted premolars and 48 samples of porcine palatal mucosa were used. Acrylic resin prototypes were constructed, placing the tissue in close contact with the dental apices. Specimens were then divided into six groups (n=8): two control groups, of saline irrigation with (NS/WA) or without (NS/NA) ultrasonic activation, and four experimental groups, of 1.5% and 2.5% sodium hypochlorite irrigation, with (NaOCl 1.5%/WA and NaOCl 2.5%/WA) or without (NaOCl 1.5%/NA and NaOCl 2.5%/NA) activation. Root canals were irrigated with 20 mL of the solution for 5 minutes, distributed over four irrigation cycles. In each cycle, after irrigation, the solution was either kept stagnant or activated for 30 seconds and then replaced. Specimens were weighed on a precision balance before and after the irrigation protocols. Tissue dissolution was measured by the difference between the initial and final weights. One-way ANOVA was applied, followed by Tukey's HSD test (α=0.05).

RESULTS

The NS/NA and NS/WA groups had mean weight reductions similar to the 1.5% NaOCl/NA group (p>0.05) and lower than the others (p<0.05). The 2.5% NaOCl/NA and 2.5% NaOCl/WA groups had the highest mean weight loss (p<0.05), while the 1.5% NaOCl/WA group had intermediate values (p<0.05).

CONCLUSIONS

Periapical tissue dissolution occurred in all groups, with greater impact observed with 2.5% NaOCl, with or without ultrasonic activation.

Effect of irrigation protocols on root canal wall after post preparation: a micro-CT and microhardness study

The aim of this study was to investigate the effects of different post space irrigation protocols for removing residual filling material from dentin walls, by using microcomputed tomography (micro-CT), and the influence of these protocols on dentin microhardness. Bovine incisors (n = 35) were filled with the single-cone technique and MTA Fillapex (Angelus, Londrina, PR, Brazil). Post space preparation (PSP) was performed 7 days after filling, using the Odous Touch electrical system (Odous De Deus Ind. e Com., Belo Horizonte, MG, Brazil), followed by post space irrigation using manual irrigation, passive ultrasonic irrigation, or Easy Clean, together with 2.5% sodium hypochlorite (NaOCl), or with 2.5% NaOCl and 17% EDTA (NaOCl/EDTA). Micro-CT scans were performed at three time points. The residual filling material was evaluated at three levels: cervical, middle and apical. The Knoop test was measured with four indentations around the canal lumen at three dentin depths: X (100 μm), Y (200 μm) and Z (400 μm). Statistical analysis was performed using ANOVA (p < 0.05). The effects of the activation method (p < 0.001), and the root level (p = 0.013), as well as the interaction between the irrigant and the activation method (p = 0.041), led to different percentages of residual filling material. Lower amounts of residual filling material were observed at the cervical versus the middle and apical levels (p < 0.05). No significant differences were observed in dentin microhardness (p > 0.05). The best removal of the residual filling material was performed using the Easy Clean tip and NaOCl/EDTA, regardless of the activation methods.

Effect of passive ultrasonic irrigation on hard tissue debris removal: a systematic review and meta-analysis

Accumulated hard tissue debris (AHTD) in root canal irregularities may negatively impact adequate root canal disinfection. In light of this, the efficacy of passive ultrasonic irrigation (PUI) to reduce AHTD has been largely studied in in vitro studies, which have adopted different analytic methods of varying accuracy to determine the extent of AHTD more correctly. Therefore, the aim of this study was to compare how well PUI and non-activated irrigation (NAI) systems perform in reducing AHTD during final irrigation protocols, based exclusively on studies whose analyses used microCT scanning. A systematic search of the studies published up to April 2020 was performed using MeSH terms and free terms, in the following databases: PubMed, Scopus, Web of Science, BVS (Lilacs and BBO) and Embase. The inclusion criteria consisted of laboratory studies that evaluated the amount of AHTD, and compared PUI with NAI protocols using microCT analysis. The risk of bias in the selected studies was assessed critically by two reviewers. A meta-analysis was performed using the RevMan software program (P<0.05), and included studies providing the standardized mean difference (SMD), using a fixed effect model, and adopting a confidence interval of 95%. In all, 3495 studies were identified, three of which met the inclusion criteria. All three were considered as having a low risk of bias. The meta-analysis comparing the ability of PUI and NAI protocols to remove hard tissue debris showed a higher percentage of AHTD reduction (P<0.01) for PUI, with a confidence interval of 1.41 [0.79, 2.02]. The heterogeneity among the studies was 82% (I2). Considering the limitations of the present study, this systematic review and meta-analysis showed that PUI was more effective than NAI in removing hard tissue debris, based exclusively on studies that used microCT scanning to provide a more precise analysis of the two techniques used. The findings presented in the present study reinforce the concept that PUI can increase residue removal and improve the cleanliness of the root canal in endodontic treatments.

The effectiveness of passive ultrasonic irrigation and the easy-clean instrument for removing remnants of filling material

Objective

This study aimed to evaluate the efficacy of passive ultrasonic irrigation (PUI) and the easy clean instrument by micro-computed tomography (CT) for removing remnant filling materials during endodontic retreatment.

Materials and Methods

Forty mesial roots of mandibular molars were divided into four groups (n = 10) according to the agitation system and sealer used: Group 1: PUI/AH Plus; Group 2: PUI/TotalFill; Group 3: Easy Clean/AH Plus; and Group 4: Easy Clean/TotalFill. The groups were compared by micro-CT analysis according to the volumes of the obturation and the remaining material before and after the agitation systems were used.

Results

There was no difference between the groups for total filling volume and initial and final remaining filling volume (P > 0.05).

Conclusions

Both the PUI and easy-clean instrument are effective for removing remnants of filling material with no difference between the groups.

Protocols for Mechanical Cleaning of the Post Space on the Bond Strength Between Root Dentin and Cementation System

OBJECTIVE

To evaluate the effects of mechanical versus chemical cleaning protocols for cleaning the root dentin surface before cementation of fiberglass posts for their effect on the bond strength, failure mode, and dentinal penetration of the cementing agent using an etch-and-rinse adhesive system on dentin prepared to receive a fiberglass post.

METHODS

Forty roots of bovine teeth were endodontically treated and prepared for fiber post cementation. The specimens were randomized into 4 groups of 10: Control group (CO) - irrigation with 2.5% NaOCl; DW group- irrigation with distilled water; RB group - rotating brush for cleaning root canals, and CUI group - continuous ultrasonic irrigation. The fiberglass posts were cemented, and the specimens were immersed in distilled water for 6 months. A push-out test was performed on the cervical, middle, and apical thirds of the samples. Dentinal penetration of the cementing agent and the fracture pattern were evaluated by laser confocal microscopy. Statistical analysis was performed using analysis of variance (ANOVA) and post hoc Tukey tests (α=0.05). Results: The RB and CUI groups showed significantly higher bond strength values when compared to the Control and DW groups (p<0.05). In addition, in the control and DW groups, the apical third presented lower bond strength values when compared to middle and cervical thirds.

CONCLUSION

While DW showed the highest incidence of adhesive type failure, CUI resulted in the highest dentinal penetration of the cementing agent (p<0.05). RB and CUI resulted in the highest bond strength between cementation system and root dentin. In addition, CUI favored greater dentinal penetration of fiberglass post cementing agent.

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.

Cleaning efficacy and uncontrolled removal of dentin of two methods of irrigant activation in curved canals connected by an isthmus

The aim of this study was to compare the efficacy of UAI with ESI, sonic activation with Eddy^® and syringe irrigation in removing debris, and dentin removal during canal irrigation. Twenty-four mandibular molars containing isthmus type V and with a mean curvature of 32.5º were instrumented and divided into three groups for final irrigation: UAI with ESI, sonic activation with Eddy and syringe irrigation. The samples were scanned in a SkyScan 1172 micro-CT device for pre-, post-instrumentation and post-irrigation images and analysis of dentin removal. Statistical analysis was performed using Wilcoxon, Kruskal-Wallis and Dunn tests. UAI and sonic activation significantly improved debris removal (P < 0.05). No significant difference was observed regarding dentin removal between the groups (P > 0.05), although higher values were found for UAI. Sonic activation with Eddy^® showed to be an effective and safe device since it was able to remove debris without causing damage to the canal walls.

Bacterial Reduction in Oval-Shaped Root Canals After Different Irrigant Agitation Methods

Objective:

This study aimed to assess the antibacterial effect of Easy Clean®, passive ultrasonic irrigation and sonic irrigation against Enterococcus faecalis biofilm in oval-shaped canals.

Methods:

Fifty-five extracted human teeth with similar dimensions were selected. Access cavities were prepared and the root canals were instrumented using Wave One® Primary files (25.08). The root canals were then contaminated with an E. faecalis suspension following incubation for thirty days. The contaminated roots were divided into three experimental groups (n=15) according to the irrigant agitation protocol (Easy Clean, passive ultrassonic irrigation and sonic irrigation), in addition to a positive control group (n=5) and a negative control group (n=5). Microbiological samples were taken from the root canals before instrumentation (S1), after instrumentation (S2) and after the final irrigation protocol (S3). The samples were assayed and incubated for 48 hours in order to obtain the residual titer of E. faecalis cells. Viable cells were quantified by colony-forming units (CFU) measurement. The collected data was submitted to statistical analysis by using Shapiro-Wilk`s test, Wilcoxon paired test, Kruskal–Wallis test and Dunn’s post-hoc test. The level of significance was set at 5%.

Results:

All experimental groups presented significant reduction on bacterial load after instrumentation (P<0.05) with similar reduction among the groups. After the agitation protocols, significant reduction in bacterial load was demonstrated for all groups (P<0.05). However, no differences were shown among Easy Clean®, PUI and SI (P>0.05).

Conclusion:

The results showed that all tested groups exhibited similar disinfection effectiveness. However, none of them was able to render all root canals free from microorganisms.

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.

Chemical and mechanical influence of root canal irrigation on biofilm removal from lateral morphological features of simulated root canals, dentine discs and dentinal tubules

Aim

To investigate the anti‐biofilm efficacy of irrigation using a simulated root canal model, the chemical effect of irrigants against biofilms grown on dentine discs and their impact on biofilm viscoelasticity, the efficacy of the irrigants in decontaminating infected dentinal tubules and the capacity of bacteria to regrow.

Methodology

Biofilm removal, viscoelastic analysis of remaining biofilms and bacterial viability were evaluated using a simulated root canal model with lateral morphological features, dentine discs and a dentinal tubule model, respectively. Experiments were conducted using a two‐phase irrigation protocol. Phase 1: a modified salt solution (RISA) and sodium hypochlorite (NaOCl) were used at a low flow rate to evaluate the chemical action of the irrigants. Ultrasonic activation (US) of a chemically inert solution (buffer) was used to evaluate the mechanical efficacy of irrigation. Phase 2: a final irrigation with buffer at a high flow rate was performed for all groups. Optical coherence tomography (OCT), low load compression testing (LLCT) and confocal scanning laser microscopy analysis were used in the different models. One‐way analysis of variance (anova) was performed for the OCT and LLCT analysis, whilst Kruskal–Wallis and Wilcoxon ranked tests for the dentinal tubule model.

Results

US and high flow rate removed significantly more biofilm from the artificial lateral canal. For biofilm removal from the artificial isthmus, no significant differences were found between the groups. Within‐group analysis revealed significant differences between the steps of the experiment, with the exception of NaOCl. For the dentine discs, no significant differences regarding biofilm removal and viscoelasticity were detected. In the dentinal tubule model, NaOCl exhibited the greatest anti‐biofilm efficacy.

Conclusions

The mechanical effect of irrigation is important for biofilm removal. An extra high flow irrigation rate resulted in greater biofilm removal than US in the artificial isthmus. The mechanical effect of US seemed to be more effective when the surface contact biofilm–irrigant was small. After the irrigation procedures, the remaining biofilm could survive after a 5‐day period. RISA and NaOCl seemed to alter post‐treatment remaining biofilms.

Efficacy of a Nickel-Titanium Ultrasonic Instrument for Biofilm Removal in a Simulated Complex Root Canal

This study evaluated the effectiveness of NiTi ultrasonic tips for Enterococcus faecalis (E. faecalis) biofilm removal in simulated complex root canals. Sixty root canal models consisting of a 30-degree curved main canal and two lateral canals were constructed from polydimethylsiloxane and incubated with E. faecalis. Irrigants in root canals were activated using a manual syringe (SI), a stainless steel (SS) instrument, a nickel-titanium (Ni-Ti) ultrasonic instrument, or a sonic instrument (EA). Instruments of SI, SS, and NiTi-9 groups were placed 9 mm from the apex, whereas those in NiTi-2 and EA groups were placed 2 mm from the apex. The efficacy of each method was determined as the ratio of fluorescence concentration before and after activation. In the apical curved canal, the highest efficacy was found in the NiTi-2 group (99.40%), followed by SI (84.25%), EA (80.38%), SS (76.93%), and NiTi-9 (67.29%) groups. In lateral canals 1 and 2, the efficacy was the highest in the NiTi-2 group and the lowest in the SI group. The NiTi ultrasonic instrument could effectively remove biofilms in the curved canal and lateral canals. This instrument should be introduced close to the working length. An up-and-down motion of the activation instrument is recommended.

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.

Current perspectives on dental adhesion: (3) Adhesion to intraradicular dentin: Concepts and applications

Adhesion science is one of the greatest contributions to restorative dentistry. Adhesion not only established the current principles of tissue preservation, but also allowed for the production of more hermetic and long-lasting restorations. Although adhesive strategies are routinely used in most clinical situations, adhesion to root dentin is still a major challenge. The presence of humidity together with less intertubular dentin are factors that limit the adhesive potential of root dentin. This situation is more unfavorable in endodontically treated teeth prepared for prefabricated or custom-made intraradicular posts; these procedures may alter the mechanical properties of teeth by modifying the viable dentin surface for adhesion. Also, contaminants deposited on the dentin surface are difficult to remove through conventional techniques. Moreover, root canal morphology has a very unfavorable C-factor, bringing undesirable effects resulting from polymerization contraction of resin-based materials. However, the differences between coronal and root dentin are not a barrier for dentin adhesion. Standardization of procedures and care during clinical steps are fundamental to the success of adhesion to coronal or intraradicular dentin. Thus, it is essential to know the anatomy of the root structure, the factors that interfere with intraradicular adhesion, as well as the current adhesive materials and techniques.

The Effectiveness of Three Irrigation Systems in the Enterococcus faecalis Reduction after Instrumentation with a Reciprocating Instrument

OBJECTIVE

 This study aimed to analyze the effectiveness of three irrigation systems: EndoActivator, passive ultrasonic irrigation (PUI), and Easy Clean in the reduction of Enterococcus faecalis, after instrumentation with the reciprocating system, through microbiological collection and culture method.

MATERIALS AND METHODS

 A total of 60 extracted human lower premolars were used and standardized at 16 mm in length. The teeth were accessed, contaminated with E. faecalis, and incubated for 21 days at 37°C. Initial collections (S1) were made with an absorbent paper cone to confirm the contamination; subsequently, instrumentation was performed with WaveOne Primary. The teeth were divided into four groups according to the final irrigation protocol (n = 15): group 1. EndoActivator; group 2, PUI; group 3, Easy Clean; and group 4, control group irrigated with saline solution sterile and without agitation. In the final irrigation, the agitation of the 17% ethylene amine tetra-acetic acid (EDTA) solutions was used, then 2.5% sodium hypochlorite (NaOCl); in both for this, three cycles of 20 seconds each. After the chemical-mechanical preparation and agitation of the irrigating solutions, the final collections (S2) for counting the colony-forming units (CFU/mL) occurred.

RESULTS

 The Kruskal-Wallis test revealed that all the agitation systems reduced by 100% and the control group by 65.7%.

CONCLUSION

 The control group presented a significantly higher amount of CFU/mL after the chemical-mechanical preparation than the other groups, which were similar to each other (p > 0.05).

Relationship between canal morphology and isthmus in mesio-buccal roots of maxillary first molars in 9- to 12-year-old children: An in-vivo cone-beam computed tomography analysis

OBJECTIVES

This study aims to analysis the distribution of root canal isthmuses (RCIs), and its relationship with canal morphology in the mesio-buccal roots of maxillary first molars in children aged 9-12 in a Chinese sub-population.

METHODS

494 healthy, untreated maxillary first molars with fully developed mesio-buccal roots were examined. Cone-beam computed tomography (CBCT) scans were acquired as part of diagnosis and treatment plannings unrelated to the present study. The images were evaluated to identify the canal morphology of mesio-buccal roots according to Vertucci's classification. A map-reading strategy was used to identify RCIs.

RESULTS

In mesio-buccal roots, the most common canal morphology was type Ⅳ (38.5 %). The frequency of type I (1.6 %) was much lower than adults. RCIs were found in 92.5 % mesio-buccal roots. The RCIs which began in the cervical third and ended in the middle third (CT-MT) (31.0 %) had the highest frequency. In type III, the RCIs which began and ended in the middle third (MT-MT) (30.3 %) were most common. For type V, 30.8 % RCIs began in the cervical third and ended in the apical third (CT-AT). No significant differences were found between sexes and sides (P > 0.05).

CONCLUSIONS

For children aged 9-12, the frequency of type I canals was much lower in mesio-buccal roots of maxillary permanent first molars, while the frequency of RCIs was higher than adults, especially in the apical third. The distribution of RCIs had its own characteristics in each canal type, closely related to the structures.

Ultrasonic Irrigant Activation during Root Canal Treatment: A Systematic Review

INTRODUCTION

The aim of this study was to systematically review the evidence on the cleaning and disinfection of root canals and the healing of apical periodontitis when ultrasonic irrigant activation is applied during primary root canal treatment of mature permanent teeth compared with syringe irrigation.

METHODS

An electronic search was conducted of the Cochrane Library, Embase, LILACS, PubMed, SciELO, and Scopus databases using both free-text key words and controlled vocabulary. Additional studies were sought through hand searching of endodontic journals and textbooks. The retrieved studies were screened by 2 reviewers according to predefined criteria. The included studies were critically appraised, and the extracted data were arranged in tables.

RESULTS

The electronic and hand search retrieved 1966 titles. Three clinical studies and 45 in vitro studies were included in this review. Ultrasonic activation did not improve the healing rate of apical periodontitis compared with syringe irrigation after primary root canal treatment of teeth with a single root canal. Conflicting results were reported by the in vitro microbiological studies. Ultrasonic activation was more effective than syringe irrigation in the removal of pulp tissue remnants and hard tissue debris based on both clinical and in vitro studies. Ultrasonic activation groups were possibly favored in 13 studies, whereas syringe irrigation groups may have been favored in 3 studies.

CONCLUSIONS

The level of the available evidence was low, so no strong clinical recommendations could be formulated. Future studies should focus on the antimicrobial effect and healing of apical periodontitis in teeth with multiple root canals.

Passive Ultrasonic Irrigation Efficacy in the Vapor Lock Removal: Systematic Review and Meta-Analysis

Passive Ultrasonic Irrigation (PUI) represents one of the most used systems to improve the endodontic irrigants activity. PUI acts increasing the reaction rate of NaOCl, with an increase of dentinal debris and smear layer removal. There is a stronger shear stress and a vapor lock reduction. Aim of this systematic review was to figure out the effects of the PUI on the vapor lock removal, during irrigation. Literature research has been carried out by two reviewers, consulting online databases such as PubMed, EBSCO, and Google Scholar, using keywords like Vapor Lock, Vapour Lock, and Vapor Lock Endodontic. The articles list has been screened based on titles and abstracts, applying eligibility and inclusion criteria. The three articles were eligible for quantitative and statistical analysis, by using RevManager Software Version 5.3. Results show statistical heterogeneity (P=0.08; I² index=61%) in the vapor lock elimination between the use of PUI and PPI, with an overall Odds Ratio=0.08, CI=95% [0.03;0.25]. PUI resulted to be a useful technique to improve NaOCl activity for vapor lock removal, despite PPI alone using a needle.

Cleaning effectiveness of a nickel-titanium ultrasonic tip in ultrasonically activated irrigation: a SEM study

In endodontic treatment, regardless of the instrumentation technique, the presence of a smear layer covering contaminated dentin walls is always a concern. Thus, irrigation plays an essential role in reducing bacterial load. To enhance irrigation effectiveness, different ultrasonic activation methods and the use of different tips have been studied. This study assessed the cleaning capacity of the novel NiTi ultrasonic tip for smear layer removal using ultrasonically activated irrigation (UAI) with passive or continuous ultrasonic irrigation (PUI or CUI, respectively), compared with conventional irrigation. Forty-five single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. Instrumentation was performed using the Genius system up to size 50.04 and irrigated with 3% NaOCl. The specimens were divided into three groups (n = 15) according to the final irrigation activation technique: conventional irrigation (CI), as control group; PUI; and CUI, following the manufacturer's protocol. The samples were longitudinally cleaved and analyzed under a scanning electron microscope for smear layer removal according to a cleanliness score for the cervical, middle, and apical thirds. Data were evaluated by means of the Kruskal-Wallis and Tukey's tests, with a 5% level of significance. UAI enhanced cleaning compared to conventional irrigation, mainly at the apical third. CUI showed the best results, with statistically significant lower scores than PUI and CI (p < 0.05). Final irrigant activation with the NiTi tip showed better cleaning capacity than conventional irrigation. In addition, CUI resulted in better smear layer removal than PUI.

Micro-CT evaluation of sonically and ultrasonically activated irrigation on the removal of hard-tissue debris from isthmus-containing mesial root canal systems of mandibular molars

AIM

To evaluate the efficacy of sonically and ultrasonically activated irrigation on removal of accumulated hard-tissue debris (AHTD) in mesial root canal systems of mandibular molars using micro-computed tomographic (micro-CT) analysis.

METHODOLOGY

Forty mesial roots of mandibular molars with two independent canals joined apically by an isthmus (Vertucci type II) were selected. The root canals were instrumented using Reciproc R25 instruments, and specimens were scanned at a resolution of 10.5 μm. Subsequently, n = 10 roots were assigned to each of the four final irrigation groups such that the group means and variances were almost identical: sonically activated irrigation with EndoActivator (EA) or EDDY (ED), ultrasonically activated irrigation (UAI) and manual irrigation without activation (MI). The final irrigation procedures were performed using a total of 5 mL 1% NaOCl and 5 mL 15% EDTA per canal over 5 min with activation time of 4 × 20 s. Reconstructed data sets were coregistered, and the mean percentage reduction of AHTD after final irrigation was compared statistically between groups using analysis of variance at a significance level set at 5%.

RESULTS

A significant reduction of AHTD was achieved after final irrigation in all groups (P < 0.05), ranging from 44.1% to 66.8%. The vol% of debris after irrigation was 3.7 ± 1.9% for EA, 3.3 ± 2.3% for ED, 2.1 ± 1.6% for UAI and 4.4 ± 2.3% for MI, with no significant difference between groups (P > 0.05).

CONCLUSIONS

None of the final irrigation protocols completely removed AHTD from mesial root canal systems in extracted human mandibular molars. Sonically and ultrasonically activated irrigation performed no better compared to manual irrigation.

Computed microtomography evaluation of calcium hydroxide-based root canal dressing removal from oval root canals by different methods of irrigation

The aim of this study was to evaluate the capacity of conventional irrigation, passive ultrasonic irrigation (PUI), and Easy Clean for removing calcium hydroxide-based root canal dressing from oval root canals. Thirty mandibular uniradicular incisors with oval canals were used, and subjected to chemical-mechanical preparation with Reciproc R40 instruments. The main canal was filled with a paste based on Ca(OH)₂ P.A., iodoform and propylene glycol in the ratio of 3:1:1. The teeth were stored in 100% humidity at a temperature of 37°C for 14 days. Afterwards, the teeth were divided into three groups (n = 10) according to the method of irrigation used (conventional irrigation, PUI, and Easy Clean). The specimens were analyzed by computed microtomography at three time intervals: before placing the root canal dressing, with the root canal dressing in place, and after application of the irrigation methods for removing it. The data were submitted to Kruskal-Wallis and Dunn tests for analyzing the canal as a whole, and Friedman and Dunn for analyzing the root thirds. The results showed that conventional irrigation was less efficient for removing the root canal dressing in comparison with the methods that agitated the irrigant solution (p < .05). When the root canal was analyzed as a whole, Easy Clean, and PUI were similar (p > .05). In analysis of the thirds, Easy Clean was more efficient than conventional irrigation in all the thirds, while PUI showed this behavior only in the cervical third (p < .05). The authors concluded that in oval canals, none of the irrigation methods were capable of removing all the root canal dressing, however, the methods that agitated the irrigant solution were more efficient than conventional irrigation.

Isthmus Incidence in Human Permanent Mandibular First Molars of a South Indian Population: A Cone-Beam Computerized Tomographic Study

Aim:

This study aimed to analyze incidence of isthmus in human permanent mandibular first molar teeth using cone-beam computed tomographic imaging techniques in a South Indian population.

Materials and Methods:

Three hundred permanent mandibular first molar teeth were collected, cleaned, and stored in normal saline. They were divided into groups (GPs) I and II based on number of roots, and were further subdivided (right and left [RL] subgroups A and B for GP I; and RL subgroups C and D for GP-II). Samples were processed and isthmus incidence was evaluated by cone-beam tomography, compared, and statistically analyzed.

Results:

Overall in mandibular first molars, the isthmus incidence in mesial root was 97.2%, distal root was 39%, and distolingual root was 0%. There was no statistically significant difference between the right and left mandibular first molar teeth with regard to incidence of isthmus (P > 0.05). There was an incidence of type I (38.67%), type II (56.33%), type III (3%), and type IV (2%) isthmuses in mesial root and type I (12.33%), type II (16%), and type III (10.67%) in distal root.

Conclusion:

Incidence of isthmus was very high in the mesial root of the mandibular first molar and should be factored during nonsurgical and surgical endodontic treatment procedures to achieve successful treatment outcomes.

Evaluation of chemical and morphological changes in radicular dentin after different final surface treatments

The aim of this study was to evaluate the chemical and morphological effects of different lasers as a final surface treatment for endodontic therapy through energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Twenty-five maxillary canines were selected and instrumented with K3 system. Roots were randomly distributed into five groups (n = 5) according to the surface treatment: GI (distilled water), GII (NaOCl + EDTA), GIII (NaOCl + EDTA + 980 nm diode laser), GIV (NaOCl + EDTA+ 1,064 nm Nd:YAG laser), and GV (NaOCl + EDTA+ 2,780 nm Er, Cr:YSGG laser). Lasers were applied for 20 s and samples were bisected, exposing the treated surface and then subjected to elements quantification by EDS and morphological evaluation by scanning electron microscope (SEM). EDS data were submitted to ANOVA-two way, and SEM scores were submitted to two-way Kruskal-Wallis and Dunn's tests. The EDS analysis showed no difference for the chemical elements and Ca/P ratio between groups (p > .05). Statistical analysis showed more intense results for GV and less intense results for GI (p < .05). The GIII showed an amorphous organic matrix surface, while GV provided greater removal of intertubular dentin forming craters, and GIV promoted dentin fusion. The EDS method used in this study was not able to verify any chemical changes in root canal dentin; Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser were capable of modifying the dentin morphology, correlating characteristics features for each one, which are essential clinical knowledge to establish the correct indication for each case. RESEARCH HIGHLIGHTS: EDS was not able to verify any chemical changes in root canal dentin after 980 nm diode, Nd:YAG and Er;Cr:YSGG laser treatments Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser modified dentin morphology, correlating characteristics features for each one.