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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.

The removal or modification of smear layers that cover the dentin is critical to allow the penetration of adhesive molecules and to ensure a strong bond between resin and dentin. Aiming to establish a model for clinically-relevant dentin-bond testing, we evaluated the effects of smear layers created by abrasives having similar coarseness (180-grit SiC paper; fine-grit diamond bur) and application modes (single application; double application) on the microtensile bond strengths (µTBS) of two currently available universal adhesives (G-Premio Bond; Scotchbond Universal Adhesive) and a two-step self-etch adhesive (Clearfil Megabond 2). Sixty extracted human third molars were used for the μTBS test. Data were analyzed by three-way ANOVA and Tukey’s test (α = 0.05). Fracture modes were determined using stereomicroscopy. An additional 24 third molars were prepared for observation of the resin–dentin interface by TEM and adhesive-smear layer interaction by SEM. μTBS was significantly affected by the adhesives and their application modes (p < 0.001), implying that the double application of universal adhesives should be recommended to improve their performance. The effect of smear layers was not significant (p > 0.05), indicating that 180-grit SiC papers could be used to prepare dentin as a substitute for fine-grit diamond burs for dentin-bond testing in laboratory settings.

The purpose of this research was to evaluate the impact of an 810 nm high-power diode laser on decontaminating both surface and intradentinal biofilm, as well as removing the smear layer. Forty human mandibular premolars were contaminated with a biofilm composed of Enterococcus faecalis and Streptococcus mutans. The teeth were divided into groups and treated with NaOCl 2.5% + PUI, saline solution + 810 nm laser, NaOCl 2.5% + PUI + 810 nm laser, and a control group. The samples were then evaluated using a confocal laser scanning microscope (CLSM). Another 40 teeth, prepared as dentin discs, were contaminated with the same biofilm to assess surface decontamination. Additionally, 80 bovine dentin discs with an induced smear layer, placed in the apical third of mesial root canals of 3D-printed teeth, underwent similar treatments. Pre- and post-treatment images were obtained using an environmental scanning electron microscope. Data were statistically analyzed with ANOVA test and Tukey’s test, respectively. Intradentinal disinfection rates were 67,33% for PUI, 51,50% for the 810 nm laser, and 55,32% for the PUI + 810 nm laser, with no statistically significant differences ( p  > 0.05). Surface decontamination rates were 39,52%, 51,27%, and 45,20% for the respective groups, also without significant differences ( p  > 0.05). No significant differences were found regarding smear layer removal ( p  > 0.05). The 810 nm diode laser with saline achieved disinfection similar to 2.5% sodium hypochlorite with ultrasound. Combining laser and PUI didn’t improve disinfection. None of the studied protocol removed the smear layer.

The effects of Easydo Activator (EA), a new sonic irrigation system, on sealer penetration at the root apex were compared to needle irrigation (NI) and passive ultrasonic irrigation (PUI) in this study. Forty-two single-rooted teeth were prepared and randomly divided into three groups (n = 14): group 1: NI; group 2: PUI; and group 3: EA. A solution of 3% sodium hypochlorite (NaOCl) was used for irrigation. Nine teeth in each group were filled with AH Plus sealer mixed with CY5 fluorescent dye and a single gutta-percha cone. The sealer penetration area, maximum penetration depth and percentage of sealer penetration at 5 mm and 1 mm from the apex were analyzed by confocal laser scanning microscopy (CLSM). The remaining 5 teeth in each group were subjected to test smear layer scores by scanning electron microscopy (SEM). The CLSM evaluation showed that increases in the area, depth and percentage of sealer penetration were detected at 1 and 5 mm from the root apex in the PUI group compared with the NI group, and greater increases were observed in the EA group ( P  < 0.05). The SEM experiment showed that the lowest scores for the smear layer and debris removal were achieved by the EA group when compared with the PUI and NI groups ( P  < 0.05). In conclusion, EA was superior to PUI and NI regarding sealer penetration at the root apex during endodontic treatment, and it could provide a new technical idea for clinical root canal therapy.

Introduction To evaluate the bacterial biofilm, smear layer and debris removal efficacy of a hydro-dynamic cavitation system with physiological saline using a new ex vivo model. Methods Seventy-five dentin discs were prepared from fifty-four extracted teeth. Seventy-five artificial root sockets were prepared. Sixty dentin discs were used to grow 3-week-old bacterial biofilms, while smear layer and debris were produced on fifteen dentin discs. These dentin discs were adhered to the middle third of the artificial root canals. The sixty ex vivo models with biofilm-covered dentin discs were divided into six groups: control, needle with physiological saline, ultrasonic with physiological saline, Odne™ Clean with physiological saline, needle with 3% NaOCl, and ultrasonic with 3% NaOCl. Biofilm removal efficacy was evaluated using confocal laser scanning microscopy. The fifteen ex vivo models with smear layer and debris-covered dentin discs were divided into three groups: control, Odne™ Clean with physiological saline, and 5% NaOCl followed by 17% EDTA. Smear layer and debris removal efficacy was evaluated using scanning electron microscopy. Statistical analysis was performed using one-way analysis of variance for comparisons involving more than two groups. Post-hoc pairwise comparisons were conducted using the Tukey test. Results Odne TM Clean with physiological saline (98%) performed significantly better than needle irrigation (47%) or ultrasonic activation (54%) with physiological saline ( P  < 0.05). Odne TM Clean with physiological saline removed biofilms as effectively as needle irrigation (97%) or ultrasonic activation (98%) with 3% NaOCl ( P  > 0.05). Additionally, 5% NaOCl followed by 17% EDTA (score: 1.33) removed the smear layer significantly better than Odne TM Clean with physiological saline (score: 4.47) ( P  < 0.05). However, Odne TM Clean with physiological saline (score: 1.27) removed debris as effectively as 5% NaOCl followed by 17% EDTA (score: 1.13) ( P  > 0.05). Conclusions Odne TM Clean with physiological saline can effectively remove bacterial biofilm and debris from the dentin surface but cannot effectively remove the smear layer. Utilizing Odne TM Clean during the final irrigation may enhance root canal cleaning efficacy.

Objective: This study aimed to evaluate the effectiveness of a polyether ether ketone (PEEK) activation tip in smear layer removal. Materials and Methods: Fifty maxillary upper incisors were prepared up to a size 50/05 instrument and embedded in tubes filled with heavy-body silicone to create a customised matrix for each specimen. The teeth were removed from the matrices, sectioned longitudinally, and standardised grooves were created at 3, 6, and 9 mm from the apex to delineate the buccal canal wall area for analysis. Specimens were then reassembled, repositioned in their respective matrices, and allocated to the following groups: ultrasonic activation with a PEEK tip, ultrasonic activation with a metallic tip, conventional non-activated irrigation, and 2 control groups (positive and negative). Smear layer removal at each level was evaluated using environmental scanning electron microscopy and scored according to a 4-point scale. Statistical analysis was performed using the Kruskal–Wallis test (P < .05). Results: Ultrasonic activation with both PEEK and metallic tips significantly enhanced smear layer removal compared to conventional non-activated irrigation at the 3 mm level. At the 6- and 9-mm levels, no significant differences were found between the PEEK and metallic tips; however, both outperformed the conventional method. Conclusion: These findings suggest that ultrasonic activation with PEEK tips is an effective option for smear layer removal, providing results comparable to those achieved with metallic tips across all evaluated canal levels.

Background and Objectives: Successful endodontic treatment requires thorough disinfection and removal of the smear layer to prevent reinfection. However, conventional irrigants like sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) can compromise dentin integrity. This study assessed the efficacy of the Synergistic Microbicidal and Ablative Root canal Technique (SMART), which integrates AromaRoot, a biocompatible irrigation solution based on quaternary ammonium compounds, with 980 nm diode laser activation, to enhance bacterial reduction and smear layer removal. Materials and Methods: Sixty extracted single-rooted human teeth were inoculated with Enterococcus faecalis and divided into four treatment groups using NaOCl, AromaRoot, and 980 nm laser, either alone or in combination. Bacterial counts were measured as colony-forming units per milliliter (CFU/mL). For smear layer analysis, 56 extracted teeth were prepared and irrigated using EDTA, AromaRoot, and laser activation, followed by scanning electron microscopy to evaluate dentinal tubule exposure. Data were analyzed using Kruskal–Wallis and ANOVA. Results: The combination of AromaRoot, NaOCl, and laser activation achieved a 99.00% bacterial reduction (from 8082 to 60 CFU/mL, p < 0.001), outperforming NaOCl alone (98.34%, 131 CFU/mL). For smear layer removal, AromaRoot with laser achieved 78.5% open dentinal tubules in the apical third, significantly higher than EDTA alone (64.5%, p < 0.05), though EDTA remained superior in the coronal third (89.0% vs. 81.0%, p > 0.05). Conclusions: The SMART technique significantly improves both disinfection and smear layer removal in root canal therapy, particularly in the apical region. These findings suggest that AromaRoot, especially when laser-activated, may serve as a safe and effective alternative to conventional irrigants, warranting further clinical evaluation.

Effective root canal therapy (RCT) depends on proper disinfection rather than complete sterilization of the root canal system. The smear layer created during instrumentation can inhibit disinfection, and its removal is crucial for successful treatment. Recently, various irrigant activation methods, including shock wave enhanced emission photoacoustic streaming (SWEEPS), passive ultrasonic irrigation (PUI), sonic activation (SA), and syringe irrigation (SI), have been developed to enhance cleaning efficacy. Sterilization of the root canal system is crucial for successful root canal therapy. Lasers have emerged as a popular choice for eliminating microorganisms from the root canal. This study aimed to compare the effectiveness of different irrigant activation techniques-SWEEPS, PUI, SA, and SI-in removing the smear layer from root canals prepared with either a conventional access cavity (ConvAC) or an ultraincisal access cavity (UincAC) design. This study aimed to clarify and compare the effectiveness of various irrigant activation techniques in removing the smear layer from canals with conservative and conventional cavity designs. Eighty extracted human maxillary incisors were prepared using a VDW 35/0.04 rotary system and randomly divided into eight groups (  = 10 per group), based on cavity configuration and activation technique: G1: SWEEPS-ConvAC, G2: SWEEPS-UincAC, G3: PUI-ConvAC, G4: PUI-UincAC, G5: SA-ConvAC, G6: SA-UincAC, G7: SI-ConvAC, G8: SI-UincAC. All samples were irrigated with 2.5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), followed by distilled water, and examined using scanning electron microscopy (SEM). Data were analyzed with Kruskal-Wallis and Bonferroni-adjusted Mann-Whitney tests (  = 0.05). No statistically significant difference was found in smear layer scores in the coronal and middle thirds among the groups. However, significant differences were observed in the apical third (  < 0.001). The SWEEPS-ConvAC group showed the least smear layer, while the SI-UincAC group exhibited the most. The effectiveness ranking was: SWEEPS, followed by PUI, SA, and SI. While access cavity design alone did not significantly affect smear layer removal, SWEEPS was the most effective activation method. The combination of SWEEPS with conventional cavity design yielded the most effective smear layer removal in the apical third. These results emphasize the importance of selecting not only an effective irrigant but also an appropriate cavity design to optimize apical disinfection in clinical endodontics.

This study aimed to compare the effectiveness of an experimental root canal irrigant and 17% Ethylene-di-amine tetra acetic acid for removal of the smear layer in the coronal, middle and apical portions of the root canal. Ninety human single rooted maxillary and mandibular teeth were selected for this study. The teeth were randomly divided into two experimental groups and one control group as follows: Group A (Ethanolic extract of Sapindus Mukorossi), Group B (17% EDTA), and Group C (Distilled water). The root canals of all three groups were prepared with stainless steel K-files by means of the standard step-back technique and irrigated with 5.25% sodium hypo chloride. The teeth were decoronated, following the irrigation and divided longitudinally into two-halves and visualized using scanning electron microscope (SEM) for the amount of smear layer present utilizing the three-point score system. The observations were noted both before and after the treatment. Nonparametric tests were applied for the comparison and -value ⩽ 0.05 was considered as statistically significant. It was evident from that smear layer was completely removed in coronal portion of 27 out of 30 teeth in-group A. For middle and apical areas of group A, 24 and 19 teeth showed complete smear layer removal. In-group B it was found that there were 24, 21, and 3 teeth at coronal, middle and apical, areas respectively where smear layer were completely absent. Intra group comparison showed a significant difference (  = 0.002) in smear layer removal was found for group A at coronal, middle and apical thirds. Similarly, a significant difference (  = 0.001) was also found for group B; however heavy smear layer was found among the three parts of the canal for group C. Ethanolic extract of Sapindus Mukorossi have higher effectiveness in removing the smear layer from the root canal in comparison to 17% EDTA.

Objective: This study aimed to evaluate the wall shear stress (WSS) and smear layer (SL) removal between EndoVac, modified apical negative pressure (mANP)- a novel system, and side-vented (SV) positive pressure irrigation techniques. Methods: (Phase 1): A simulated 3-dimensional (3D) root canal model and three types of needles (EndoVac, mANP, and SV-positive pressure) were simulated. Model parameters and computer solution were set to analyse the WSS magnitude and pattern using computational fluid dynamics (CFD). (Phase 2): 60 single-rooted extracted permanent lower premolars were decoronated (15.0mm) for standardisation. All samples were root canal prepared up to F4 Protaper size before being randomly divided into three groups according to the final irrigation protocols: Group 1 (EndoVac), Group 2 (mANP), and Group 3 (SV). The samples were vertically split into half and observed under scanning electron microscope (SEM). The SEM evaluation was compared using Fisher's exact test with the level of significance set at 0.05. Results: CFD analysis revealed that different irrigation systems and needle designs affect the WSS pattern and magnitude. The mANP showed the highest average WSS (11.06 Pa) compared to SV (10.72 Pa) and EndoVac (10.48 Pa). For SEM evaluation, the mANP demonstrated superior SL removal compared to the other groups. There were significant differences between the three groups in SL removal using Fisher's exact test. Conclusion: The mANP revealed the highest average WSS magnitude and the cleanest SL removal compared to the EndoVac and SV positive pressure technique. Thus, this proves, there is a direct correlation between average WSS magnitude and SL removal.(EEJ-2025-05-084)