OBJECTIVE: This study aimed to assess the efficacy of different activation techniques in removing calcium hydroxide (Ultracal XS), Ledermix, and Bio-C Temp from simulated internal root resorption (IRR) cavities.
METHODS: 108 single-rooted maxillary incisors were prepared using Reciproc R50 files. Simulated IRR cavities, 2 mm in diameter and located 8 mm from the apex, were created. Ultracal XS, Ledermix, and Bio-C Temp were applied to the samples, grouped by irrigation activation techniques: Standard Needle Irrigation (SNI), EDDY, Passive Ultrasonic Irrigation (PUI), and XP-endo Finisher (XPF). Medicament removal efficacy was evaluated using a standardized scoring system. Statistical analysis was performed using the Kruskal-Wallis test.
RESULTS: XPF and PUI were more effective than SNI in medicament removal across the groups, with no significant difference. EDDY showed no significant difference than other groups. Ledermix was more effectively removed in all activation groups compared to Bio-C Temp. The XPF was superior in removing Ultracal XS compared to Bio-C Temp. However, none of the groups achieved complete medicament removal.
CONCLUSIONS: XPF and PUI techniques enhance medicament removal efficacy. Bio-C Temp was more difficult to remove from the IRR cavities than other medicaments.
CONCLUSIONS: Bio-C Temp could be removed from the canals less effectively compared to calcium hydroxide and Ledermix. Among the tested irrigation activation methods, XPF and PUI were found to be more effective at removing the tested medicaments.

BACKGROUND: The probability of a positive outcome of root canal therapy is substantially higher if the infection is eradicated successfully before the obturation of the root canal system. Irrigation is an essential aspect of root canal debridement, as it enables more thorough cleaning than is possible with root canal instrumentation alone. To overcome the side effects of chemical irrigants, there has been a search for herbal medicines as substitutes.
OBJECTIVE: The aim of the present study was to explore the antimicrobial efficacy of white tea-mediated silver nanoparticles (AgNPs) formulated as an intracanal irrigant against Enterococcus faecalis, and to compare it with the efficacy of chlorhexidine and sodium hypochlorite irrigants.
METHODS: The experimental groups were as follows: group I - white tea-mediated AgNPs; group II - 2% chlorhexidine; and group III - 2.5% sodium hypochlorite. The characterization of AgNPs was performed using ultraviolet-visible (UV-Vis) spectroscopy and transmission electron microscopy (TEM) analysis. Enterococcus faecalis was inoculated onto Mueller-Hinton agar plates. The disks impregnated with irrigants were placed on the inoculated plates and incubated aerobically at 37°C for 24 h. Then, the growth inhibition zones were measured. Statistical analysis was performed using the one-way analysis of variance (ANOVA) and the post hoc tests.
RESULTS: A concentration of 50 μL of white tea-mediated AgNPs exhibited the greatest zone of inhibition (32 ±2 mm), followed by 2% chlorhexidine (25 ±1 mm) and 2.5% sodium hypochlorite (23 ±3 mm).
CONCLUSIONS: White tea-mediated AgNPs showed promising results in the elimination of E. faecalis, being superior to chlorhexidine and sodium hypochlorite irrigants.

This experimental study investigated the effect of different intracanal irrigants on the push-out bond strength of dentin in damaged anterior primary teeth. The crowns of 90 anterior primary teeth were sectioned horizontally, 1 mm above the cementoenamel junction (CEJ). Following canal preparation with K-files, all groups except the negative control received normal saline irrigation. Canals were then irrigated with either 3% or 5.25% sodium hypochlorite (NaOCl), 2% or 0.2% chlorhexidine (CHX) solution (except negative and positive controls). The roots were filled with Metapex material and covered with a calcium hydroxide liner. In root canals, the bond was applied by self-etching and then light-cured for 20 seconds before canals were restored incrementally with composite. Stereomicroscopes were used to assess failure patterns. Push-out bond strengths (MPa ± SD) were: 3% NaOCl (16.92 ± 5.78), 5.25% NaOCl (8.96 ± 3.55), 2% CHX (14.76 ± 5.56), and 0.2% CHX (7.76 ± 2.93). Significant differences were seen across the irrigants regarding the push-out bond strength of dentin sections (P <0.001). The most frequent failures were adhesive and cohesive. NaOCl and CHX irrigants increased the push-out bond strength compared to controls. Compared to controls, both 3% NaOCl and 2% CHX irrigants significantly increased the push-out bond strength of dentin in non-vital anterior primary teeth.

The aim of this study is to evaluate the effect of different irrigation activation methods on root canal sealer penetration in teeth with simulated internal root resorption (IRR) and calcium hydroxide (CH) applied using a confocal laser scanning microscope (CLSM). 60 incisors with a single root and a single canal were included in the study. IRR cavities were created in the middle third of the root canal, and CH was placed. The samples were randomly divided into 4 groups (n = 15) according to the irrigation activation method to be tested: standard needle irrigation (SNI), sonic activation (EDDY), photon-induced photoacoustic flow (PIPS), and shock wave enhanced emission photoacoustic flow (SWEEPS). After irrigation activation applications, the root canals were obturated. Sections of 1.0 ± 0.1 mm were taken from the apical, middle, and coronal regions of each sample. The penetration area (µm2) and maximum penetration depth (µm) of the root canal sealer were examined by CLSM and analyzed using ImageJ software. Statistical analysis was performed with a one-way ANOVA and post-hoc Tukey test at the P < 0.05 significance level. Among all irrigation activation methods tested, both the penetration area and maximum penetration depth of the root canal sealer were greater in the coronal region than in the apical region (p < 0.05). In the IRR region, there was no difference in terms of maximum penetration depth between PIPS and SWEEPS (p > 0.05), it was highest in SWEEPS (p < 0.05). PIPS and SWEEPS were better than other irrigation activation methods in the penetration of root canal sealer in the resorption areas of teeth with IRR.

OBJECTIVE: This study aimed to compare the effectiveness of initial irrigation with sodium hypochlorite (NaOCl) and final irrigation with QMix, 40% citric acid, and 17% ethylenediaminetetraacetic acid (EDTA) on smear layer removal and dentin erosion.
METHODS: Forty extracted human mandibular premolar teeth were randomly divided into four groups (n = 10) according to the type of final irrigants used: 17% EDTA, QMix, citric acid, and control (normal saline). Canals were mechanically prepared using ProTaper Next instruments to an apical size of X3. Subsequently, the roots were sectioned in a buccolingual direction. Scanning electron microscopy (SEM) was used to assess the presence of the smear layer and the amount of dentin erosion in the coronal, middle, and apical thirds of the root canals.
RESULTS: In regards to smear layer removal, there was a significant difference between the control group and the other tested groups. Moreover, it was significantly higher in the coronal and middle thirds than in the apical third. However, there were no significant differences between the groups of EDTA, QMix, and citric acid. Concerning dentin erosion, citric acid produced significantly more dentin erosion than the other tested groups.
CONCLUSIONS: Final irrigation with solutions had a higher ability to remove the smear layer in the coronal and middle thirds compared to the apical third. Of all the solutions tested, 40% citric acid had the most pronounced impact on dentin erosion, followed by 17% EDTA and QMix.

OBJECTIVE: To establish molar root canal model with micro-computed tomography (Micro-CT) and evaluate the removal efficiency of calcium hydroxide by different methods.
METHODS: Eight molar teeth (24 root canals) extracted from the Department of General Dentistry, Shanghai Ninth People\'s Hospital from October 2023 to February 2024 were collected. Root canal preparation was instrumented by M3 according to standard root canal treatment procedures, then calcium hydroxide was injected into the root canal. One week later, the samples were randomly divided into 3 groups according to different irrigation methods(n=8): lateral opening syringe group, ultrasonic group and sonic vibration group. Micro-CT was used to reconstruct the root canal system before and after irrigation, and independent root canals were marked with different colors. The root canals were divided into upper root segment, middle root segment and apex segment. The volume of calcium hydroxide in each canal was calculated, and the clearance rate of calcium hydroxide was compared among the groups. SPSS 19.0 software package was used for statistical analysis.
RESULTS: None of the three methods could completely remove calcium hydroxide from the root canal. When sodium hypochlorite was used as the flushing solution, the removal effect of ultrasonic group and sonic vibration group was significantly better than that of lateral opening syringe group(P＜0.05). The removal efficiency of calcium hydroxide by ultrasonic group and sonic vibration group was similar, and the difference was not statistically significant(P＞0.05). The removal rate of calcium hydroxide in apical segment was low.
CONCLUSIONS: Micro-CT can reconstruct the molar root canal model efficiently for evaluating the removal effect of calcium hydroxide. The removal efficiency of calcium hydroxide in ultrasonic group and sonic vibration group is similar, and both are better than that in lateral syringe group.

BACKGROUND: Regenerative endodontics involves the use of various root canal medicaments and scaffolds, which may cause crown discoloration.
OBJECTIVE: This study aimed to investigate the combined crown discoloration of scaffolds [platelet-rich fibrin (PRF) and blood clot] applied after administration of different medicaments [modified triple antibiotic paste including doxycycline (mTAPd), modified double antibiotic paste (mDAP), calcium hydroxide (CH), and propolis].
METHODS: In total, 100 human mandibular premolar teeth were selected and prepared. The teeth were apically resected to simulate immature teeth. The positive and negative control groups (n = 10) consisted solely of blood-only and serum-only samples. The remaining 80 teeth were used for the experimental groups with four different medicaments. Three weeks later, either blood or PRF was applied as a scaffold after removing the medicaments (n = 10). Color changes were assessed before medication placement and at the end of the first, second, and third weeks, as well as on days 0, 1, 30, 60, and 90 after scaffold application. Analysis was carried out using repeated measures of variance, Friedman, one-way ANOVA, Kruskal-Wallis, the dependent paired t-test, and Wilcoxon test.
RESULTS: Statistical significance was determined at P = 0.05. All groups including blood and the group including propolis and PRF combination, resulted in a significant increase in discoloration (P < 0.05) and discoloration exceeding clinically acceptable thresholds.
CONCLUSIONS: CH and the modified versions of TAP (mTAPd) and DAP (mDAP) demonstrated an acceptable level of discoloration when used with a combination of PRF at day 90.

This review article explores the fundamental principles of modern endodontics with a focus on root canal cleaning and shaping. It reviews commonly used endodontic irrigant, namely sodium hypochlorite (NaOCl), herbal extracts, chlorhexidine (CHX), and chelating agents, highlighting their properties, applications, and potential drawbacks. NaOCl, a key antimicrobial agent, demonstrates effectiveness against various microorganisms but poses challenges such as high cytotoxicity. Herbal extracts, gaining recognition in endodontics, present an alternative with potential advantages in preserving dentin integrity. CHX, known for its broad-spectrum antimicrobial activity, is discussed in both liquid and gel formulations, emphasizing its role in reducing smear layer formation and preserving hybrid layer durability. Chelating agents, specifically ethylenediaminetetraacetic acid and citric acid, play a vital role in removing the smear layer, enhancing dentin permeability, and facilitating the penetration of antimicrobial agents. The review article underscores the importance of careful application and consideration of each irrigant\'s properties to ensure safe and effective endodontic procedures. It serves as a valuable guide for clinicians in selecting appropriate irrigants based on specific treatment requirements.

BACKGROUND: Root canal irrigation is crucial for infection control during root canal treatment. Side-vented needles for positive pressure irrigation are commonly used in clinical practice. However, variations in needle design among manufacturers can impact the fluid dynamics of irrigation. This study aims to use computational fluid dynamics to explore the flow characteristics of different needle aperture lengths and positions, and their effects on the effectiveness and safety of irrigation, using a validated passive scalar transport numerical model.
METHODS: The validation of the CFD irrigant model was achieved by comparing it with an in vitro irrigation experiment model. The CFD model used scalar concentration, while the in vitro experiment model used red dye tracing. Using a standard 30G side-vented needle as a reference, virtual needle models featuring four aperture lengths and three positions were created. These virtual irrigation needles were then placed in two root canal geometries for CFD simulation to evaluate fluid exchange capabilities and related fluid dynamic parameters.
RESULTS: The results of the CFD simulation, using a scalar transport model, closely matched the in vitro tracer tests for irrigation experiments across seven root canal geometries. The CFD analysis indicated that positioning the aperture lower increased the irrigant exchange distance. Notably, decreasing the aperture length to 0.25x, and positioning it at the lower end of the needle significantly increased exchange distance and shear stress, while reducing apical pressure.
CONCLUSIONS: These results indicate that the position and length of the aperture affect the exchange distance of irrigant flow, wall shear stress, and apical pressure. The CFD validation model for scalar transport, based on a steady state, can function as a valuable tool for optimizing the side-vented needle in research. Further research on the design of side-vented needles will enhance the understanding of flow characteristics beneficial for irrigation efficiency in clinical practice.

OBJECTIVE: This study compared the effects of conventional, ultrasonic, and laser-activated irrigation (LAI) on penetration depth of three photosensitizers (PSs) in the root canal system.
METHODS: In this in vitro, experimental study, 120 extracted anterior teeth were decoronated such that the remaining root length was standardized at 12 mm. After root canal instrumentation with the ProTaper rotary system and irrigation with 5.25% NaOCl, the roots were assigned to 12 groups for the application of toluidine blue (TB), curcumin, and phycocyanin PSs combined with the LAI using erbium laser with 0.4 mm and 0.6 mm tips, ultrasonic activation, and conventional irrigation. The specimens were sectioned apicocoronally, and the dye penetration depth was quantified in the coronal, middle, and apical thirds under a stereomicroscope at x20 magnification. Data were analyzed by the Kruskal-Wallis and Dunn test (alpha=0.05).
RESULTS: The effects of irrigation technique, PS type, and their interaction on dye penetration depth were significant at the apical, middle, and coronal thirds (P<0.0001). TB + LAI with 0.4- and 0.6-mm laser tips showed the highest penetration depth while phycocyanin + LAI or conventional irrigation showed the lowest penetration depth at all areas. Dye penetration depth was the highest in the coronal, and the lowest in the apical third.
CONCLUSIONS: The LAI technique with erbium laser (0.4- and 0.6-mm tips) enhanced the penetration depth of TB. The tested irrigation techniques had no significant efficacy for enhancement of the penetration depth of curcumin and phycocyanin.