FESEM evaluation of smear layer removal using different irrigant activation methods (EndoActivator, EndoVac, PUI and LAI). An in vitro study

Effectiveness of a new endodontic irrigation system for removing smear layer and dissolving simulated organic matter

OBJECTIVES

The study aimed to evaluate the potential for the dissolution of organic tissue in areas of simulated complexity and cleaning of root canal walls of the new iVac® endodontic irrigation system.

MATERIAL AND METHODS

Thirty mandibular premolars were evaluated by scanning electron microscopy before and after biomechanical preparation. Then, they were distributed according to the final irrigation protocol into groups with conventional irrigation, ultrasonic agitation with metallic insert (UA), and iVac® system, and new photomicrographs were obtained. For tissue dissolution analysis, glass capillaries filled with catgut were attached to the cervical and apical thirds of twenty-one prototyped upper incisors. They were weighed before and after the previously mentioned irrigation protocols. The data were statistically compared with a significance level of 5%.

RESULTS

The final irrigation provided greater cleaning of the root canal walls in the cervical, middle, and apical thirds of the root canals (P < 0.05), with no statistically significant difference between UA and iVac®, regardless of the analyzed thirds. Both ultrasonic irrigation protocols dissolved a significantly greater volume than the conventional irrigation protocol (P < 0.05), with no difference between the two protocols (P < 0.05).

CONCLUSIONS

The iVac® system showed root canal wall cleaning and tissue dissolution similar to UA with a metallic insert, and both were superior to conventional irrigation.

CLINICAL RELEVANCE

The new irrigation system iVac is more effective than conventional irrigation and has similar root canal wall cleaning and tissue dissolution to UA.

Minimally invasive management of vital teeth requiring root canal therapy

The present study aimed to investigate the possible use of a non-instrumentation technique including blue light irradiation for root canal cleaning. Extracted human single rooted teeth were selected. Nine different groups included distilled water, NaOCl, intra-canal heated NaOCl, and NaOCl + EDTA irrigation after either instrumentation or non-instrumentation, and a laser application group following non-instrumentation technique. The chemical assessment of the root canal dentine was evaluated using energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy. Surface microstructural analyses were performed by using scanning electron microscopy (SEM). The antimicrobial efficacy of different preparation techniques was evaluated using microbial tests. Light application didn't change the calcium/phosphorus, carbonate/phosphate and amide I/phosphate ratios of the root canal dentin. The root canal dentin preserved its original chemistry and microstructure after light application. The instrumentation decreased the carbonate/phosphate and amide I/phosphate ratios of the root canal dentin regardless of the irrigation solution or technique (p < 0.05). The application of light could not provide antibacterial efficacy to match the NaOCl irrigation. The NaOCl irrigation both in the non-instrumentation and instrumentation groups significantly reduced the number of bacteria (p < 0.05). The use of minimally invasive root canal preparation techniques where the root canal is not instrumented and is disinfected by light followed by obturation with a hydraulic cement sealer reduced the microbial load and preserved the dentin thus may be an attractive treatment option for management of vital teeth needing root canal therapy.

Influence of Chitosan 0.2% in Various Final Cleaning Methods on the Bond Strength of Fiberglass Post to Intrarradicular Dentin

The purpose of this study was to analyze the influence of Chitosan 0.2% in various final cleaning methods on the bond strength of fiberglass post (FP) to intrarradicular dentin. Ninety bovine incisors were sectioned to obtain root remnants measuring 18 mm in length. The roots were divided: G1: EDTA 17%; G2: EDTA 17% + PUI; G3: EDTA 17% + EA; G4: EDTA 17% + XPF; G5: Chitosan 2%; G6: Chitosan 2% + PUI; G7: Chitosan 2% + EA; G8: Chitosan 2% +XPF. After carrying out the cleaning methods, the posts were installed, and the root was cleaved to generate two disks from each root third. Bond strength values (MPa) obtained from the micro push-out test data were assessed by using Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner tests for multiple comparisons (α = 5%). Differences were observed in the cervical third between G1 and G8 (p = 0.038), G4 and G8 (p = 0.003), G6 and G8 (p = 0.049), and Control and G8 (p = 0.019). The final cleaning method influenced the adhesion strength of cemented FP to intrarradicular dentin. Chitosan 0.2% + XPF positively influenced adhesion strength, with the highest values in the cervical third.

Effect of silver diamine fluoride activation on bond strength to root dentin

BACKGROUND

To investigate the effect of silver diamine fluoride (SDF) application and activation on the bond strength of gutta-percha to dentin and resin bonded post to dentin.

METHODS

Thirty-six human premolar teeth were used. The coronal part tooth was removed, and endodontic mechanical preparation was performed for all the teeth. The teeth were divided according to final rinse protocol (n = 9) as follows: Control group; no SDF application, SDF/NA; 38% SDF as a final rinse with no activation, SDF/MDA; 38% SDF as a final rinse with manual dynamic activation and SDF/US; 38% SDF as a final rinse with ultrasonic activation. Root canal obturation using lateral condensation technique followed by fiber post insertion after 48 h in the root canal after corresponding preparations. The roots were cut with a low-speed precision saw creating 2 mm thickness sections. A total of 4 sections were obtained from each tooth, 2 coronal specimens (with post) and 2 apical specimens (with Gutta percha). Each specimen was subjected to push-out bond strength test with a universal testing machine. Data were analyzed using two-way ANOVA.

RESULTS

The Push-out bond strength at the apical root section was significantly higher in SDF/MDA and SDF/US groups compared to control group. While for the coronal part, all SDF treated specimen showed reduced Push-out bond strength.

CONCLUSION

SDF application as final rinse may reduce the bonding performance between fiber post and dentine. Activation with manual and ultrasonic methods improved the bond strength at the apical root section.

The effects of laser and ultrasonic irrigation activation methods on smear and debris removal in traditional and conservative endodontic access cavities

In this study, it was aimed to evaluate the smear and debris removal efficiency of laser and ultrasonic irrigation activation methods in traditional and conservative endodontic access cavity preparations. 60 freshly extracted human mandibular molar teeth were randomly divided into 2 groups according to the access cavity preparation (n = 30): Traditional endodontic access cavities (TEC) and Conservative endodontic access cavity (CEC). After the access cavity preparation, the mesiobuccal root canals were prepared to 35/0.4 with the VDW Rotate file system. Teeth with completed root canal preparation were randomly divided into 3 subgroups according to the final irrigation activation protocol (n = 30): Conventional needle irrigation, passive ultrasonic activation and laser activation. The crowns of the teeth were removed and the mesiobuccal roots were divided longitudinally into two halves, mesial and distal. Samples were scanned with scanning electron microscopy. Photomicrographs in the coronal, middle, and apical thirds of each specimen were taken at a magnification of 200 for debris and 1000 for evaluation of the smear layer. Data were analysed using the three-way Robust Anova test and Bonferroni test.The effect of access cavity design on remaining smear (p = 0.057) and debris (p = 0.5) was not statistically significant. The effect of the interaction of access cavity and irrigation activation on the remaining smear and debris was not statistically significant (p = 0.556, p = 0.333). Significantly fewer smears were detected in the laser activation group than in the ultrasonic activation and control groups. Conservative access cavities did not differ from conventional access cavities in terms of debris and smear.

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

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

Cleaning efficacy of EDDY versus ultrasonically-activated irrigation in root canals: a systematic review and meta-analysis

BACKGROUND

Ultrasonically-activated irrigation (UAI) is effective in root canal irrigation but may damage canal walls. EDDY is a sonic activation system with flexible working tips that cause no harm to dentinal walls. This review explores the intracanal cleaning efficacy of EDDY compared with UAI in vitro.

METHODS

The systematic review was registered in the PROSPERO database (CRD42021235826). A literature search was conducted in six electronic databases. In vitro studies that compared the removal of smear layer, debris, soft tissue or microbes in root canals between EDDY and UAI were included. Data extraction and quality assessment were performed. Meta-analyses were conducted on smear layer removal and debris elimination with the standardized mean difference (SMD). Heterogeneity was measured using the I² test and the Chi² test. The random-effect model was used when I² > 50%, or p < 0.1, otherwise the fixed-effect model was applied. The level of significance was set at p < 0.05.

RESULTS

19 articles were included in this systematic review and 7 articles were included in meta-analyses. Meta-analyses on smear layer removal showed unimportant differences between EDDY and UAI at any canal third (coronal [SMD = 0.08, 95% confidence interval (95%CI): -0.29 to 0.45; p = 0.44, I² = 0%]; middle [SMD = 0.02, 95% CI: -0.44 to 0.47; p = 0.94, I² = 0%]; apical [SMD = 0.01, 95%CI: -0.35 to 0.38; p = 0.70, I² = 0%]). Meta-analyses on debris removal evaluated by scanning electron microscope (coronal [SMD = 0.03, 95% CI: -0.41 to 0.46; p = 0.27, I² = 23%]; middle [SMD = -0.24, 95% CI: -0.83 to 0.35; p = 0.80, I² = 0%]; apical [SMD = 0.24, 95%CI: -0.20 to 0.67; p = 0.36, I² = 2%]) and micro-CT (SMD = 0.36, 95% CI: -0.67 to 1.40; p = 0.03, I² = 70%) both found insignificant differences. No meta-analysis was undertaken on soft-tissue removal and disinfection due to the various study designs, but the qualitative analyses implied that EDDY achieved similar performance to UAI in both aspects.

CONCLUSIONS

Limited evidence indicated that EDDY was comparable to UAI in removing smear layer, debris, soft tissue and microbes ex vivo. Considering UAI may damage canal walls, EDDY might be a substitute for UAI in irrigation activation. But more randomized clinical trials are required to explore the clinical extrapolation of the results in this review.

Effect of 0.2% Chitosan Associated with Different Final Irrigant Protocols on the Fiber Post Bond Strength to Root Canal Dentin of Bovine Teeth: An In-vitro Study

Objective:

This in-vitro study investigated the effect of 0.2% Chitosan associated with different final irrigant protocols on the bond strength of fiber posts (FP) to root canal dentin.

Methods:

Fifty bovine incisors roots were prepared using the ProTaper Universal system, irrigated with 2.5% sodium hypochlorite, and divided into one control group (n=10) with no final irrigant protocol and four experimental groups (n=10), which were defined according to the combination of chelating solution (17% EDTA and 0.2% Chitosan) and irrigant activation/delivery method [conventional irrigation (CI), and passive ultrasonic irrigation (PUI)]. Post spaces were prepared to a depth of 12 mm using #1-5 Largo drills, and the FP were cemented using self-adhesive resin cement. Two slices of 2 mm in thickness from each third were obtained and submitted to the micropush-out test. After testing the push-out strength, the slices were analyzed under a stereomicroscope at 40× magnification for bond failure patterns determination. Statistical analysis was performed using three-way ANOVA followed by Tukey’s test (α = 0.05).

Results:

The control and 17% EDTA + CI groups exhibited significantly lower bond strength than 0.2% Chitosan + CI, 17% EDTA + PUI, and 0.2% Chitosan + PUI groups in the cervical third (P = 0.00). The cervical third had higher values than the middle and apical thirds in control (P = 0.00), 17% EDTA + PUI (P = 0.00), and 0.2% Chitosan + PUI groups (P = 0.00). Adhesive cement-dentin failure type was predominant in all groups.

Conclusion:

The use of 0.2% chitosan did not affect the bond strength of FP to root dentin. Passive ultrasonic activation of chelating solutions resulted in an improvement in bonding strength.

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.

Influence of Commonly Used Endodontic Irrigants on the Setting Time and Metal Composition of Various Base Endodontic Sealers

The present study aimed to evaluate if commonly used endodontic irrigants such as 3% sodium hypochlorite (NaOCl, Prime Dental, Thane, India), 2% chlorhexidine (CHX, Sigma-Aldrich Co., St. Louis, MO, USA), and 17% ethylenediaminetetraacetic acid (EDTA, Meta-Biomed Co. Ltd., Cheongju-si, South Korea) influenced the setting time and metal composition of different base endodontic sealers on exposure. AH Plus (Dentsply De Trey GmbH, Konstanz, Germany), Sealapex (SybronEndo, Orange, CA, USA), mineral trioxide aggregate (MTA) Fillapex (Angelus Soluções Odontológicas, Londrina, Brazil), and Tubli-Seal (Kerr Dental, Orange, CA, USA) were selected as the different base representatives of endodontic sealers. These sealers were exposed to 3% NaOCl, 2% CHX, and 17% EDTA, and the individual setting time of the sealers was analyzed. The samples were analyzed for heavy metal elements such as chromium (Cr), nickel (Ni), cobalt (Co), cadmium (Cd), arsenic (As), mercury (Hg), lead (Pb), and beryllium (Be) by using inductively coupled plasma mass spectrometry (ICP-MS) analysis. For statistical analysis, one-way ANOVA and post hoc Tukey’s tests were used. All selected sealers showed variation in setting time post-exposure to different irrigants. MTA Fillapex had the shortest mean setting time (215.7 min, post-exposure at 187.3 min) (p < 0.05). Mean setting time was also affected for AH Plus (479.6 min, post-exposure at 423.9 min) (p < 0.05) and Tubli-Seal (514.7 min, post-exposure at 465.2 min) (p < 0.05). Sealapex showed the maximum reduction of setting time (864.8 min, post-exposure at 673.4 min) (p < 0.05). All tested sealers showed heavy metals (Cr, Ni, Co, Cd, As, Hg, and Pb) in their composition, and the quantities were influenced by interaction with different irrigants. The heavy metal Be was not seen in any of the samples. Sealapex showed the longest setting time in comparison to other test sealers. Heavy metals were most present in Sealapex, followed by AH Plus, Tubli-Seal, and MTA Fillapex. MTA Fillapex was seen to have the shortest setting time, and heavy metal composition was least affected on interaction with different commonly used endodontic irrigants. Further, this study provides significant insight into the influence of different endodontic irrigants on interaction with different base endodontic sealers, which has not been reported previously, and future studies should emphasize endodontic irrigant-sealer interactions and their possible effects in the long run.

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

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

An experimental intraradicular biofilm model in the pig for evaluating irrigation techniques

BACKGROUND

We established an in vivo intraradicular biofilm model of apical periodontitis in pigs in which we compared the efficacy of different irrigant activation techniques for biofilm removal.

METHODS

Twenty roots from the deciduous mandibular second premolar of 5 male pigs were used. After pulpectomy, canals were left open for 2 weeks and then sealed for 4 weeks to enable the development of an intracanal biofilm. The intraradicular biofilms was evaluated using SEM and bacterial 16S rRNA gene-sequencing. To investigate the efficacy of biofilm removal, root canal irrigations were performed using conventional needle, passive ultrasonic, subsonic, or laser-activated irrigation. Real-time PCR was conducted to quantitate the remaining biofilm components. Statistical analysis was performed using ANOVA followed by a Tukey kramer post-hoc test with α = 0.05.

RESULTS

The pulp exposure model was effective in inducing apical periodontitis and SEM analysis revealed a multi-layer biofilm formation inside the root canal. 16S rRNA sequence analysis identified Firmicutes, Bacteroidetes, and Fusobacteria as the predominant bacterial phyla components, which is similar to the microbiome profile seen in humans. None of the tested irrigation techniques completely eradicated the biofilm components from the root canal, but the subsonic and laser-activated irrigation methods produced the lowest bacterial counts (p < 0.05).

CONCLUSIONS

An experimental intraradicular biofilm model has been successfully established in pigs. Within the limitations of the study, subsonic or laser-activated irrigation demonstrated the best biofilm removal results in the pig system.

FESEM evaluation of smear layer removal from conservatively shaped canals: laser activated irrigation (PIPS and SWEEPS) compared to sonic and passive ultrasonic activation-an ex vivo study

Background

Irrigation of the pulp space is a mandatory step to get rid of all its organic and inorganic content. Activation of the irrigants play a key role in the era of minimally invasive endodontics. The aim of this study was to assess the effectiveness of different irrigants activation methods in removing the smear layer at 1, 3, 5 and 8 mm from the apex from conservatively shaped canals.

Methods

Eighty-five human mandibular premolars were selected. Specimens were shaped to TruShape 25/.06 and divided into 5 groups (1 control and 4 test groups) according to the final activation technique (EndoActivator, EA), Ultrasonic (EndoUltra, PUI) and Laser (PIPS and SWEEPS). EDTA (Ethylenediaminetetraacetic acid) followed by NaOCl (Sodium Hypochlorite) and again EDTA were activated for each test group. Specimens were then split longitudinally and observed by Field Emission Scanning Electron Microscopy (FESEM). Blinded evaluation of the presence of smear layer was performed at 1000X magnification, according to a 5-score index system. Comparison between groups were analysed statistically using the Kruskal–Wallis non-parametric analysis of variance. Bonferroni multiple comparison tests were used.

Results

At 1 mm only PIPS and SWEEPS performed better than the control group. At 3, 5 and 8 mm from the apex, every activation technique showed statistically significant reduction of smear layer when compared to the control group. PIPS and SWEEPS obtained better cleanliness result compared to EA, while only PIPS was superior to PUI in terms of cleanliness.

Conclusions

PIPS and SWEEPS showed the best results in conservative canal preparations. Nowadays, contemporary rotary instruments allow fast and minimally invasive shaping of the endodontic space. In this scenario irrigants’ activation may be regarded as a mandatory step to a favourable clinical outcome.

Evaluation and comparison on the wettability of three root canal sealers after three different irrigant activation techniques: An in vitro study

Background

Wettability of root canal sealers to the root canal wall plays a significant role in the attainment of a fluid-tight seal.

Aims

This study aimed to evaluate and compare the wettability of three different root canal sealers on the root canal walls after three different irrigant activation techniques using the contact angle meter.

Subjects and Methods

Thirty-six single-rooted mandibular premolars after decoronation and cleaning and shaping up to size #35 were randomly divided into three groups with 12 samples in each group (n = 12) based on the different activation techniques: Group I (passive irrigation with side-vented needle), Group II (manual dynamic agitation), and Group III (passive ultrasonic irrigation). Root segments were split longitudinally and were subdivided into three subgroups based on the root canal sealers tested with four samples in each subgroup (n = 4): Subgroup A (Tubliseal EWT), Subgroup B (AH Plus), and Subgroup C (Endosequence BC sealer). A controlled volume droplet of sealer was placed on each specimen and was subjected to the contact angle meter.

Statistical Analysis

Data were statistically analyzed using the one-way ANOVA and Tukey's post hoc test at a significance level of 0.05 (P < 0.05).

Results

A statistically significant difference was seen among all the groups and subgroups with the highest contact angle value for Group III and Subgroup C and the least value for Group I and Subgroup A.

Conclusions

Passive irrigation with side-vented needle and Tubli-Seal EWT showed better wettability on dentin.

Smear layer removal by passive ultrasonic irrigation and 2 new mechanical methods for activation of the chelating solution

Objectives

The aim of this study was to compare smear layer removal by conventional application (CA), passive ultrasonic irrigation (PUI), EasyClean (EC), and XP-Endo Finisher (XPF), using 17% ethylenediaminetetraacetic acid (EDTA) after chemomechanical preparation, as evaluated with scanning electron microscopy (SEM).

Materials and Methods

Forty-five single-rooted human mandibular premolars were selected for this study. After chemomechanical preparation, the teeth were randomly divided into 5 groups according to the protocol for smear layer removal, as follows: G1 (control): CA of distilled water; G2 (CA): CA of 17% EDTA; G3 (PUI): 17% EDTA activated by PUI; G4 (EC): 17% EDTA activated by EC; and G5 (XPF): 17% EDTA activated by XPF. SEM images (×1,000) were obtained from each root third and scored by 3 examiners. Data were evaluated using the Kruskal-Wallis and Dunn tests (p < 0.05).

Results

In the apical third, there were no statistically significant differences among the groups (p > 0.05). In the cervical and middle thirds, the experimental groups performed better than the control group (p < 0.05); however, G2 presented better results than G3, G4, and G5 (p < 0.05), which showed no differences among one another (p > 0.05).

Conclusions

No irrigation method was able to completely remove the smear layer, especially in the apical third. Using CA for the chelating solution performed better than any form of activation.

Impact of Warm Vertical Compaction on the Sealing Ability of Calcium Silicate-Based Sealers: A Confocal Microscopic Evaluation

The aim of this in vitro study was to evaluate the dentinal tubule penetration of two calcium silicate-based sealers used in warm vertical compaction (WVC) obturation technique in comparison with the single cone (SC) technique by confocal laser scanning microscopy (CLSM). The null hypothesis was that both obturation techniques produced similar sealer penetration depths at 1 and 5 mm from the apex. Forty-four mandibular single-rooted premolars were randomly divided into four equally experimental groups (n = 10) and two control groups (n = 2) according to the type of sealer (Bio-C Angelus, Londrína, PR, Brazil or HiFlow Brasseler, Savannah, GA, USA) with either SC or WVC. The sealers were mixed with a fluorescent dye Rhodamine B (0.1%) to enable the assessment under the CLSM. All the specimens were sectioned horizontally at 1 and 5 mm from the apex. The maximum penetration depth was calculated using the ImageJ Software (ImageJ, NIH). Data were analyzed by Mann-Whitney U and Kruskal-Wallis tests (p < 0.05). A significant difference was shown between the four groups at 1 mm (p = 0.0116), whereas similar results were observed at 5 mm (p = 0.20). WVC allowed better diffusion for both sealers at 1 mm (p = 0.01) and 5 mm (p = 0.034). The maximum penetration of the Bio-C and HiFlow sealers was more important at 5 mm with the two obturation techniques. Within the limitations of this study, WVC enhanced the penetration of calcium silicate-based sealers into the dentinal tubules in comparison with the SC technique at both levels.

The Efficiency of the Er: YAG Laser and PhotonInduced Photoacoustic Streaming (PIPS) as an Activation Method in Endodontic Irrigation: A Literature Review

In the field of endodontics, lasers have been used for a long time for the optimization of Endodontic irrigation in particular. The laser-activated irrigation (LAI) technique is based on the photomechanical effects of the lasers at low settings. They create specific cavitation phenomena and acoustic streaming in intracanal fluids. More recently, a new technique with a Er:YAG laser has been used with sub-ablative energy (20 mJ, 15 Hz) and ultra-short pulses (50 µs). This leads to intracanal cavitation and shockwaves as a result of photoacoustic and photomechanical effects. This phenomenon is called photon-induced photoacoustic streaming (PIPS). PIPS and Laser activated irrigation are described in the literature as a revolutionary and powerful method to activate the irrigant; however, systematic literature on this topic is missing. This review compares the literature on Er:YAG LAI and PIPS on endodontic irrigation with other irrigation methods. An article search was performed on the PubMed database using a series of keywords related to endodontic irrigation, including Er:YAG LAI and PIPS; 59 articles were selected for the review according to the inclusion and exclusion criteria. No in vivo study was found. The Er:YAG LAI and PIPS outperformed other methods in 33 of the 59 articles. There was a great variety in the study designs including bacterial incubation time, laser parameters, irrigation protocols, and irrigating solution used. The evidence suggests that the Er:YAG LAI and PIPS are promising in canal disinfection as well as debris and smear layer removal. However, the large variety in the study methods makes the results less significant. Further studies are needed to better evaluate the efficiency of these techniques, especially in vivo studies.

Quantitative analysis of SmearOFF and different irrigation activation techniques on removal of smear layer: A scanning electron microscope study

The aim of this study was to evaluate the effectiveness of SmearOFF solution on smear layer removal by using different irrigation activation techniques. One hundred and twenty mandibular premolars were decoronated, and instrumented with Reciproc up to size 50. Then, the specimens were divided into 6 groups according to the final irrigation activation technique: Group 1: SmearOFF + Conventional syringe irrigation (CSI); Group 2: SmearOFF + Sonic activation (SA); Group 3: SmearOFF + Passive ultrasonic activation (PUA); Group 4:17% EDTA + CSI; Group 5:17% EDTA + SA, and Group 6:17% EDTA + PUA. Teeth were split longitudinally, and specimens were observed under scanning electron microscope. Images were taken from the coronal, middle, and apical thirds of the teeth with 1,000× magnification and analyzed using ImageJ program to calculate total open dentinal tubule areas. Three-way ANOVA test was applied to reveal any significant differences among solutions, activation techniques and root thirds. There was no statistically significant difference among the groups in terms of irrigation solutions (p > .05). There was a statistically significant difference between PUA and CSI groups (p < .05). However, no significant difference was observed between PUA and SA, or between SA and CSI (p > .05). All experimental procedures were most effective in the middle region of the root, followed by cervical and apical thirds (p < .05). PUA showed higher efficacy in smear layer removal compared with CSI. SmearOFF and 17% EDTA showed similar results. The best results in removing smear layer were obtained in the middle region of the root.

Negative Pressure Irrigation Presents Mineralizing Potential in Dogs' Immature Teeth with Periapical Lesion

The objective of this in vivo study was to assess the effect of the root canal irrigation by negative and positive apical pressure on the expression of molecules that are an indicative of cell differentiation with mineralizing phenotype in teeth of dogs with incomplete rhizogenesis and induced periapical lesion. A total of 30 teeth (60 roots) were distributed into 3 groups (n=20): EndoVac®, Conventional and Control. After 90 days, the routine histotechnical procedures were performed and the sections were submitted to immunohistochemical technique for the staining of osteopontin (OPN), alkaline phosphatase (ALP) and the RUNX2 transcription factor in the apical and periapical regions of the roots. A semi-quantitative analysis of the positive immunostaining was performed and the intensity of the expression was classified in absent (0), mild (1), moderate (2), or intense (3). Scores data were statistically analyzed by the Kruskal-Wallis non-parametric test and Dunn post-test, and the significance level was set at 5%. RUNX2 immunostaining revealed that in the negative pressure group there was a significantly stronger (p<0.05) immunostaining in comparison to the control group. Regarding the OPN expression, it was not possible to detect a statistically significant difference between the groups (p>0.05). After analyzing ALP immunostaining, a statistically significant difference was observed between the groups (p<0.05), and the negative pressure group showed a markedly stronger mark immunostaining than the control group. The results of the present in vivo study allowed concluding that negative apical pressure irrigation presents mineralizing potential in immature teeth with apical periodontitis.

Debris and Smear Layer Removal in Curved Root Canals Using the Dual Wavelength Er,Cr:YSGG/Diode 940 nm Laser and the XP-Endoshaper and Finisher Technique

Objective: To validate the capability of the dual wavelength laser (Er,Cr:YSGG and diode 940 nm) and the XP-Endoshaper and finisher in removing the smear layer from curved canals. Methods: Forty curved root canals were prepared using the R25 file of the Reciproc^® system. The teeth were randomly divided into five groups: G1: negative control irrigated with distilled water, G2: positive control irrigated with EDTA 17% and a final rinse of NaOCl 3%, G3: XP-Endoshaper and finisher with EDTA 17%, G4: dual wavelength Er,Cr:YSGG (1.25 W, 50 Hz, 50 μs) and diode 940 nm (2 W, 50% DC), and G5: dual wavelength Er,Cr:YSGG (2 W, 20 Hz, 50 μs) and diode 940 nm (2 W, 50% DC). Laser scanning microscope images (1000 × ) were scored with the Hülsmann scoring system. Results: Superior smear layer removal was observed in G5 in comparison with G4, especially in the apical third of the canal. Furthermore, the XP-Endoshaper and finisher exhibited positive results in all parts of the canal. Conclusions: The higher power output of the Er,Cr:YSGG in the dual wavelength laser may be a suitable approach to remove the smear layer from the apical third of curved canals. Moreover, the XP-Endoshaper and finisher with EDTA could expose the dentinal tubules, however, the negative side effects of applying EDTA 17% for longer periods must be taken into consideration. This work is clinically significant as it addresses the main aim of endodontic treatment and provides a suitable method to remove the debris, smear layer, and bacterial remnants from the clinically challenging curved root canals.

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

Aim:

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

Materials and Methods:

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

Results:

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

Conclusion:

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

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

Introduction:

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

Methods and Materials:

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

Result:

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

Conclusion:

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