Assessment of smear layer removal utilizing a conservative root canal instrumentation technique involving magnetically agitated irrigation with iron paramagnetic nanoparticles

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Al-Mustwfi, Hussain F. Al-Huwaizi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6196305/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 08 Jul, 2025 Read the published version in BMC Oral Health → Version 1 posted 10 You are reading this latest preprint version Abstract Background : The development of new technology in mechanical instrumentation does not completely clean all the root canal walls because of the disparity between the complexities of canal anatomical and instrument design. This study aimed to determine the optimum effect of iron oxide nanomagnet particles (IONPs) in cleaning the surface of the root canal and open dentin tubules, as well as analyze the dispersion of iron ions on the dentinal walls. Material and methods: Sixty intact extraction teeth were used and divided into six groups as stated by agitation protocol of irrigant: Group 1: Control, Group 2: Normal saline with ultrasound, Group 3: IONP with ultrasound. Group 4: IONP with magnetic field using an endodontic needle. Group 5: IONP with magnetic field using ultrasound, and Group 6: 17% ethylenediaminetetraacetic acid (EDTA). Field emission scan electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine cleaning root canal surfaces, opening dentinal tubules, removing the smear layer, and the percentage dispersion of ions on the root canal wall. The nonparametric tests of the Kruskal-Wallis, Mann-Whitney, and parametric test of One-Way ANOVA and Tuckey posthoc tests were used to compare irrigation protocols. Results : Compared to the other groups, the agitation of irrigant IONP using a combination of a magnetic field and an ultrasound device proved to be the most effective. Additionally, the agitation of irrigant IONP using only an ultrasound device was more effective than using only normal saline with an ultrasound device. Iron ions have low percentages, perfect dispersions, and minimal precipitation in the apical section of the root canal wall. Conclusion: Compared to the control group, the utilization of IONP irrigant agitation with a magnetic field did not affect dentinal structure while enhancing the cleaning of the canal surface, opening dentin tubules, and achieving a uniform distribution of iron ions with minimal precipitation. These findings may hold promise as a tool for endodontic treatment while preserving tooth structure. Magnetic agitation open dentinal tubules irrigation nanoparticles iron ions. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Background Endodontic infection is primarily caused by bacteria, which is considered as an essential etiological factor for both initial and recurrent infection (Nair et al., 2005 ). The bacterial cells' attachment to the surface using a self-manufactured extracellular polymeric substance (EPS) (Donlan and Costerton, 2002, Balaban, 2008) leads to the formation of a biofilm of multicellular microbial communities that may include one or more species. These biofilms are recognized as significant virulence factors, exhibiting resistance levels up to 1500 times greater than planktonic cells (Socransky and Haffajee, 2002 ) (Hall-Stoodley et al., 2004). The entire removal of these microbes during treatment not only affects the successful treatment but also prevents the recolonization of microbes within the treated root canal system (Byström and Sundqvist, 1983 ). The movement of bacteria within the tubules is associated with canal infections (Siqueira Jr and de Uzeda, 1996 ), and it can penetrate through the tubules at a distance (300–1500 µm). Unfortunately, the conventional protocol of the root canal irrigant cannot approach this depth into the dentinal tubules (de Paz, 2007 ), because of the anatomic complexities (Nair et al., 2005 ). As a result, bacteria and their byproduct may persist around dentinal tubules even after conventional endodontic treatment (Tennert et al., 2014 ). Furthermore, research by Vera et al. ( 2012 ) investigated the mechanical cleaning and disinfection of root canals, revealing that microorganisms might inevitably persist within the canal even after treatment (Vera et al., 2012 ). Paqué et al. ( 2010 ) showed that the areas of the flattened, oval, or C-shaped canals may stay untouched by instruments, especially at the wide canal diameter with varying cross-sections (Paqué et al., 2010 ). The agitation of irrigant inside the root canal system can be performed manually (Cunningham et al., 1982) or automatically (Sabins et al., 2003). Conventional irrigation techniques using sonic or ultrasonic activation, which involve transverse oscillation, is an inefficient method because of multiple touch points between the root canal walls and the file, especially at a narrow apical area (Boutsioukis et al., 2013 ) and cannot clean the root canal system efficiently (Sequeira et al., 2007 ). Since the development of new technology in mechanical instrumentation and cleaning, still not all the root canal walls are cleaned because of the disparity between the complexities of the canal anatomy and instrument design (Del Fabbro et al., 2018 ). Nanotechnology is the manufacture of structures at a scale of 100 nm or smaller, a near-atomic scale, to form new materials, structures, and devices (Samiei et al., 2016 ). Magnetic nanoparticles (MNPs) are used in different fields of technology such as biomedicine (El-Boubbou, 2018a ), root canal irrigant (Bukhari et al., 2018 ), enhancement of antibacterial activity to disinfection technology (Al-Bazaz et al., 2018 ), improved dentin’s adhesion without changing adhesive properties (Garcia et al., 2021 ), and modified root canal sealer under the process of a magnetic field to penetrate more deeply with enhanced periapical healing (Guo et al., 2022 ). In nanomedicine, the primary application involves the application of an external magnetic field to guide nanoparticles toward the target area, particularly employing superparamagnetic iron oxide nanoparticles (SPIONs) coated with organic or inorganic materials for drug delivery (El-Boubbou, 2018b ) (Al-Badr and Al-Huwaizi, 2020 ). The magnetite (Fe₃O₄) is better than natural iron oxide (black iron oxide) in spinel structure and displays the highest magnetism compared with another phase of IONP (Teja and Koh, 2009 ). The tooth structure may be affected throughout exposure to irrigant solutions, potentially altering the integrity of the mechanical and chemical properties of natural enamel and dentin. Successful endodontic treatment depends on the use of irrigant solutions that do not alter the properties of the tooth structure (Ari et al., 2004 ). This research aims to develop a new endodontic irrigant containing superparamagnetic iron oxide nanoparticles (SPIONs) to enhance root canal cleaning without the need for extensive canal shaping instruments, using an external magnetic field for guidance of the irrigant toward the target area and agitate the irrigant inside the root canal system. This novel approach showed the potential to bypass traditional instrumentation methods and prevent the loss of root structure when superparamagnetic iron oxide nanoparticles (SPIONs) and a magnetic field are employed and can be considered a promising strategy to enhance the cleaning efficiency of root canal systems. This study aimed to determine the optimum effect of iron oxide nanomagnet particles (IONPs) in cleaning the surface of the root canal and open dentin tubules and analyzing the dispersion of iron ions with measurement concentration on the dentinal walls. The null hypothesis was that iron oxide nanomagnet particles (IONP) irrigant agitation with a magnetic field would not enhance root canal cleaning and be effective in dentin structure. Materials and methods Sample collection Sixty intact, non-carious human maxillary first molars were collected from the mixed population for the therapeutic case and stored in a 0.2% thymol solution for decontamination, not exceeding one month (Unnikrishnan et al., 2019 ). Samples selection The magnifying lens was employed to inspect and exclude any teeth with anomalies, carious lesions, cracks, or open root apex (Aksel et al., 2019 ). Buccal and proximal radiographs were utilized to confirm the existence of a single straight palatal canal with a closed apex. To eliminate any variability in access preparation, palatal roots of the teeth were sectioned perpendicular to the longitudinal axis of the roots using 0.3 diamond discs No.913 (Komet, Germany) mounted on a straight handpiece at a low-speed (1500 rpm) (NSK, Japan) with a continuous flow of tap water. Hence, all the roots were measured 12 mm in length from the apex coronally and fixed longitudinally in clear acrylic molds using additional silicon (Zermak, Italy) to facilitate handling during the instrumentation process. Sample preparation To achieve standardized procedures throughout the study, a single operator performed all the experiments to minimize variables during specimen preparation. The barbed broach was used to remove pulpal tissue, and a stainless-steel K-file size 10 (Dentsply, Maillefer, Switzerland) was inserted into the root canal until the tip was seen just exiting at the apical foramen, observing under a magnifying lens. The critical working length was obtained by subtracting 1 mm from the length. All the roots were instrumented with the conventional stainless-steel K-files sizes from size 15 until size 20, except the control group. The file was rotated clockwise in the root canal with slight pressure; then debris was removed by pulling the file slightly outward with clockwise rotations (Ardila et al., 2003 ). The instruments were regularly cleaned to remove debris from the flutes. Each specimen requiring enlargement of more than file size 20 (Dentsply, Maillefer, Switzerland) was rejected and replaced by another one. A double-sided diamond disc, attached to a straight handpiece with water cooling, was used to create two longitudinal grooves on both the buccal and lingual sides (without deeply reaching the canal). This step aimed to aid in splitting the teeth into two segments with a chisel, following the groove's path. The specimens were subsequently placed in phosphate-buffered saline (PBS) (Sigma, USA). The tooth samples were then randomly assigned to six experimental groups. Generation of the magnetic field to agitation of iron oxide nanoparticles The magnets used in the study to generate the magnetic field consisted of two parts (Fig. 1 ): First permanent magnet: Super magnet neodymium 35, round-shaped, and diameter 18 mm (K&J Magnetics Inc., USA: Neodymium 35). The magnetic field strength remains constant, with 1000 gauss in the peripheral zone and 750 gauss in the central zone, and it does not lose its magnetic property when magnetism. The magnet is positioned 10 mm from the palatal side of the root. Second electromagnet: It consisted of a coil of wire wrapped around the iron core (self-made). When an electrical current is applied to this device, a magnetic field is generated, and then a magnet is manufactured. The magnetic field strength can be adjusted using a self-made device that controls the electric current from a direct current (DC) power supply of 30 V. The device allows changes in the polarity and frequency (on-off cycles option, 10 times per second). The magnetic field strength in this study is 1300 gauss in the peripheral zone and 900 gauss in the central zone, which is stronger than the permanent magnet to ensure the agitation of iron oxide nanoparticles (IONP) within the root canal system. The electromagnet is located 10 mm from the buccal side of the root. The field strength between the two magnets is 450 gauss. Preparation of irrigation solution A solution consisting of 100 mg of the iron oxide nanoparticles (Fe₃O₄) (Us research nanomaterials Inc., Huston, USA) of dried powder (weighed using an electronic weight scale) (Radwag, Poland) was mixed with 10 ml of deionized water (10 grams of IONPs powder in one litre of deionized water whereas the concentration of the iron oxide nanoparticles solution was 1%) according to the pilot study, bacteriological test, and cytotoxicity test, and then using ultrasonic mixing device at twenty minutes to obtain a clear colloidal dispersion (Al Bazaz et al., 2023). Sample Grouping Group 1(protocol 1): Control. Group 2 (protocol 2): Irrigation with ultrasound with no nanomagnet particles: Agitation of irrigant 50 ml of normal saline using an ultrasound device (Weedpecker U600, China) for 5 minutes. Group 3 (protocol 3): Agitation of irrigant 50 ml of IONP using an ultrasound device for 5 minutes. Group 4 (protocol 4): Agitation of irrigant 50 ml of IONP using a magnetic field with endodontic needle double side vented, gauge 30 (Hunterline, China) for 5 minutes. The syringe was attached to an electrically programmable syringe pump to release the irrigant at a flow rate of 10 ml /min. Group 5 (protocol 5): Agitation of irrigant 50 ml of IONP using a magnetic field with an ultrasound device for 5 minutes. Group 6 (protocol 6): Irrigation with EDTA 17% for 1 minute. The stainless-steel instrument E 62 used in the ultrasound device has a file diameter of 0.3 mm, taper 0%, and a working part length of 16 mm (Weedpecker U600, China). The tip of the file is held 2 mm shorter than the working length in the centre of the channel and moved in a 2–3 mm up and down direction. The file was set at power 50% as per the manufacturer's instructions. The roots were finally irrigated with 50 ml of normal saline through ultrasound devices for 5 minutes in each treatment was performed with IONP or EDTA 17%. Utilize field emission scanning electron microscopy ( FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. Tooth specimens were isolated from clear acrylic molds, and two longitudinal grooves were opened by using a chisel and mallet. One half was prepared for SEM evaluation, and the second was for a microhardness test. The halves of the roots were washed with phosphate-buffered saline (PBS), then fixated by immersing in a solution containing 4% Glutaraldehyde in 0.1 mol/L sodium cacodylate buffer (BDH, England) (pH 7.4) at 4°C overnight. Then, dehydrated in a step sequence of alcohol (Honeywell, Germany) (30, 50, and 70%) at 10 minutes, (90, and 100%) at 20 minutes, followed by immersion in hexamethyldisilazane (Merk, Germany) for 5 min, and air-drying (George and Kishen, 2007 ) (Mohmmed et al., 2017 ). The halving of the root was mounted on aluminum stubs, sputter-coated with gold, and analyzed using field emission scanning electron microscopy (FE-SEM) (InspectTM F50) (Hülsmann et al., 1997 ) (Schäfer and Zapke, 2000 ) (Ahlquist et al., 2001 ) (Hülsmann et al., 2003). Each root was divided into three regions: coronal, middle, and apical, with one point selected from the center of the canal in each region for examination under magnifications 2500 X (George and Kishen, 2007 ). The Hulsmann scoring with a 5-score index was used to determine the optimum effect of iron oxide nanomagnet particles (IONP) cleaning the root canal surface, opening dentinal tubules, and removing the smear layer in each specimen section (Hülsmann et al., 1997 ) (Abdelkafy et al., 2023 ): Score 1 No smear layer; dentinal tubules are uncovered. Score 2 Small quantity of smear layer; some dentinal tubules are covered. Score 3 Uniform distribution of smear layer; only a few dentinal tubules are uncovered. Score 4 A large quantity of uniform smear covers the entire root canal wall. Score 5 Lack of uniformity and heavy smear layer. The scoring was confirmed by a second examiner who was unaware of the treatment methods or experimental irrigants used. The energy dispersive X-ray spectroscopy (EDS) (Thermo Fisher Scientific, Nederland) (EDS)(Zheng et al., 2011 ) (Ali, 2017 ) was used to determine the concentrations of iron (Fe) elements and measure the effect of magnetism on the dispersive Fe ions in the root canal walls of each section of groups. Statistical analysis Data were analyzed using SPSS 26. The Shapiro-Wilks test checked the data's normality. Nonparametric Kruskal Wallis and Mann Whitney test compared scores of groups at coronal, middle, and apical sections in each group. Parametric test of One-Way ANOVA and Tuckey posthoc tests were used to compare between continuous data. Statistical significance was set at p < 0.05. Results 1. Assessment of root canal surface debridement and open dentin tubules by FESEM The result of comparing the amount of smear layer of all protocols with group 1 (control) (Fig. 2), group 2 (agitation of irrigant normal saline using an ultrasound device) showed a higher mean rank of smear layer score (Fig. 3) than group 3 (agitation of irrigant IONP using ultrasound device) (Fig. 4), group 4 (agitation of irrigant IONP using a magnetic field with endodontic needle) (Fig. 5) showed the higher mean rank of smear layer score than group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device) (Fig. 6), group 6 (EDTA 17%) showed the higher mean rank of smear layer score especially in middle and apical section (Fig. 7) than group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device) In all study groups, there were significant differences in the mean rank between groups in coronal, middle, and apical sections, as shown in Table 1 . Table 1 Descriptive data of smear layer removal scoring between groups after the use of different protocols. Section Group N Median Mean rank Minimum Maximum p-value* Coronal G1 10 5.00 56.20 c,f,i 4 5 < 0.001 G2 10 4.00 52.80 b,e,h 4 5 G3 10 2.50 30.05 2 4 G4 10 2.00 24.70 g,h,i 2 3 G5 10 2.00 19.15 d,e,f 1 4 G6 10 1.00 11.10 a,b,c 1 2 Middle G1 10 5.00 55.10 d,g,h 4 5 < 0.001 G2 10 4.00 46.25 b,f 3 5 G3 10 3.00 27.70 h 2 4 G4 10 3.50 36.80 c 2 5 G5 10 1.00 7.45 a,b,c,d 1 2 G6 10 2.00 21.70 e,f,g 2 3 Apical G1 10 5.00 57.00 c,e,g 5 5 < 0.001 G2 10 5.00 57.002 a,d,f 5 5 G3 10 3.50 23.00 f,g 3 4 G4 10 4.00 31.50 4 4 G5 10 1.00 10.65 a,b,c 1 4 G6 10 5.00 46.80 b 4 5 When comparing the amount of smear layer, group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device) showed the lowest mean ranks of smear layer score in the middle and apical section, while showing higher mean ranks in the coronal section. In contrast, group 4 (agitation of irrigant IONP using a magnetic field with an endodontic needle) showed the lowest mean ranks of smear layer score in the coronal section and higher mean ranks in the middle and apical sections. Group 6 (EDTA 17%) showed a lower mean rank of smear layer score in the coronal section while a higher mean rank in the apical section (Fig. 7). There was a significant difference in the mean rank of smear layer scores between coronal, middle and apical section in groups 2,4 and 6 (p < 0.05). The most effective irrigation protocol was observed in group 5 (agitation of irrigant IONP using a magnetic field with an ultrasound device). This method significantly lowers the amount of smear layer, particularly in the middle and apical sections. 2. Assessment of the concentrations of Iron (Fe) elements and measurement of the effect of magnet in dispersive Fe ions on the root canal wall by Energy Dispersive X-ray (EDS). The data followed a normal distribution. A one-way ANOVA and Tukey post hoc tests were used to compare the groups and sections. There were significant differences in the level of iron element weight percentage between groups at coronal, middle, and apical sections. There was a minimum precipitation of ions in group 3 (agitation of irrigant IONP using an ultrasound device) at the apical section compared to the middle and coronal sections, followed by group 5 (agitation of irrigant IONP using a magnetic field with an ultrasound device) there was a minimum precipitation in the middle section compared to the coronal and apical sections, and followed by group 4 (agitation of irrigant IONP using a magnetic field with an endodontic needle) there was a minimum precipitation in the apical section compared to the middle and coronal sections. This is presented in Table 2 . Table 2 Descriptive data of iron weight between groups at coronal, middle, and apical sections. Section Group N Mean Std. Deviation Minimum Maximum p-value Coronal G1 10 0.00 0.00 0.00 0.00 < 0.001 G2 10 0.00 0.00 0.00 0.00 G3 10 1.32 0.54 0.60 2.00 G4 10 1.62 0.92 0.30 2.90 G5 10 1.19 0.38 0.60 1.70 G6 10 0.00 0.00 0.00 0.00 Middle G1 10 0.00 0.00 0.00 0.00 < 0.001 G2 10 0.00 0.00 0.00 0.00 G3 10 1.13 0.36 0.50 1.60 G4 10 1.37 0.90 0.40 2.90 G5 10 0.85 0.35 0.30 1.30 G6 10 0.00 0.00 0.00 0.00 Apical G1 10 0.00 0.00 0.00 0.00 < 0.001 G2 10 0.00 0.00 0.00 0.00 G3 10 0.55 0.07 0.50 0.70 G4 10 1.24 0.89 0.30 2.70 G5 10 1.27 0.86 0.20 3.20 G6 10 0.00 0.00 0.00 0.00 Discussion The smear layer is a thin film, approximately 1-2 μm thickness, that forms on the root canal wall (Mader et al., 1984). It comprises remnants of vital or necrotic pulp tissue, dentin particles, bacterial biofilm, and irrigants that block the opening of the dentinal tubule (Virdee et al., 2018). This layer must be removed because it serves as a microbial reservoir (Pashley, 1984), limit the penetration action of the disinfecting agent, and separation between filling materials and the canal wall, ultimately compromising the sealing ability of the root canal (Yang and Bae, 2002). The success of endodontic treatment has an impact relation with the irrigation protocol, as no single irrigant solution can meet all the required criteria (Haapasalo et al., 2010). The irrigation protocols should also remove the smear layer and debris from all root canal system (Baugh and Wallace, 2005). In this study utilized various irrigant solutions, including normal saline, IONP, and 17% EDTA. To optimize the cleaning of the root canal system while conservating the maximum tooth structure, six groups were activated using different activation techniques, including ultrasonic oscillation (Van der Sluis et al., 2007), and using an external magnetic field (Al-Badr and Al-Huwaizi, 2020), either alone or in combination with ultrasonic oscillation. In this investigation, the passive ultrasound protocol of irrigation is more effective than syringe needle irrigation in eliminating the remnants of pulpal tissue, bacterial biofilm, and smear layer (Van der Sluis et al., 2007). This finding aligns with another study that recommends using nanoparticles with an ultrasound device in biomedical applications (Xu et al., 2023). Another study investigated the direct effect when using a sterile normal saline irrigant to remove planktonic bacteria from the root canal (Spoleti et al., 2003). In this study, normal saline irrigant with ultrasound was less effective than other nanoparticle irrigants. The irrigant was delivered through the hollow, smooth wire to the root canal (Gutarts et al., 2005). The apical region of root canals showed less debris and smear layer than the coronal region because of the high density of acoustic streaming at the apical regions. Cameron, in 1983, found that a 3-min and 5-min period of passive ultrasound irrigation was most effective in removing the smear layer, whilst a 1-min irrigation was ineffective (Cameron, 1983). These results are coincident in the study as irrigation at 5-min periods. In contrast to another study, it was found that ultrasonic irrigation was unable to remove the smear layer (Baker et al., 1988), but in this study, it was found that applying nano irrigant with file size 15 of an ultrasound device can remove the smear layer with a conservative tooth structure. Lumley et al. 1992 recommended a high volume of microstreaming only with a file size of 15, especially when the tips of the file vibrate freely in an irrigant solution with maximizing removal of debris (Lumley et al., 1992). Other study found that the benefits of using ultrasonic irrigation technique only for the final irrigation after finished of hand instrumentation (Van der Sluis et al., 2007). In this study, the agitation of IONP irrigant demonstrated a lower mean rank of smear layer score compared to normal saline when using an ultrasound device. This finding aligns with the results of Murugesan et al., who showed a higher smear layer score after using normal saline irrigant activated by ultrasound (Murugesan et al., 2022). In this study, EDTA 17% was used as an irrigant, which binds to calcium ions in dentin and dissolves the inorganic part of smear layers (Koga et al., 2015). However, complete removal of the smear layer is not achievable (O’Connell et al., 2000), with its most effective action occurring during the first minutes of application (Spangberg, 2002) (Serper and Çalt, 2002). Also, the research showed catastrophic damage to peritubular dentin when the time of application remains between 1-10 minutes (Calt and Serper, 2002). Another study reported that applying 10 ml of EDTA 17 % solution for one minute effectively removed the smear layer from the canal walls. In contrast, prolonged exposure to dentin increases the degree of demineralization (Calt and Serper, 2002, Ali et al., 2022, Ratih et al., 2020). Additionally, in this study, it was observed that the apical section of the canals showed inferior cleaning efficiency compared to the middle and coronal sections. The reason for the incomplete removal may be due to the failure of irrigants to reach the apical section, and the coincidence with other studies (Yang et al., 2008) (Gambarini and Laszkiewicz, 2002). There is no published data about the efficiency of the magnet activation system with IONP in cleaning the root canal, opening dentinal tubules, and removing the smear layer in the coronal, middle, and apical sections of straight root canals. Two methods have been used to evaluate this effect of IONP: one uses extracted natural teeth, and the other simulates root canals. Otherwise, simulated root canals allow a uniform root canal diameter and length but are not used in this study because dentin structures may not be identical. All the investigations of root canal treatment techniques, cleaning and shaping, irrigation protocol, and irrigant solution have focused on the cleaning ability of each system as the main objective but excluded the core goal of treatment, which involves the conservative structure of the root canal and removes the probability of instrument fracture. Hence, new strategies are essential, as achieving optimal root canal cleaning can significantly enhance the success of treatment outcomes. To conform to this goal, we propose using iron oxide nanoparticles (IONPs) in combination with an external magnetic field and ultrasound activation as an innovative approach to more effectively open dentinal tubules compared to existing methods. The use of ultrasonic activation with a magnetic field better results in the penetration depth of the irrigant. This is in agreement with another study that found hydrodynamic irrigation improved the penetration depth of irrigant solution into the root canal wall dentine (Paragliola et al., 2010). The application of an external magnetic field to guide nanoparticles toward the target area is the major application in nanomedicine with superparamagnetic iron oxide nanoparticles in drug delivery (El-Boubbou, 2018a) (Al-Badr and Al-Huwaizi, 2020). Under the situation of this study, all irrigation activation protocols using IONP were best compared to ultrasonic irrigation with normal saline. Importantly, the findings demonstrated that utilizing IONP as an irrigant, combined with magnet activation and ultrasonic techniques, yielded the most effective results for removing debris and the smear layer throughout the canal system. This study showed that activating the IONP irrigant was significantly more effective in removing the smear layer, regardless of the agitation method used. This was evident when comparing the results with the use of saline solution alone, which did not exhibit any effect on cleaning the root canal and removing the smear layer. Conclusion Compared to the control group, the use of IONP irrigant agitation with a magnetic field did not affect dentinal structure while enhancing root structure compared to EDTA irrigation, cleaning the surface of the canal, open dentin tubules, uniform distributions of Fe ions with minimum precipitation, which may indicate only a negligible extrusion beyond the root canal and can be regarded as effective options for endodontic treatment while preserving the tooth structure. Abbreviations SPIONs Superparamagnetic iron oxide nanoparticles solution IONP iron oxide nanomagnet particles Fe Iron FE-SEM Field emission scan electron microscopy EDS Energy-dispersive X-ray spectroscopy EPS Extracellular polymeric substance PBS Phosphate-buffered saline mol/L Moles per liter ml /min Milliliters per minute. MNPs Magnetic nanoparticles nm Nanometer µm Micrometer mm Millimeter DC Direct current Fe₃O₄ Iron oxide V Voltage Declarations Acknowledgments The authors declare no acknowledgments. Author contributions Funding This project did not receive any funding. Data availability The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request. Ethics approval This experimental study was executed according to the ethical principles of the World Medical Association Declaration of Helsinki (version 2008). The Scientific Committee of the College of Dentistry-University of Baghdad (No. 1024 on 30/1/2025) has approved the collection of the teeth extracted for different purposes. Consent for application Not applicable. Competing interests The authors declare that they have no competing interests. References ABDELKAFY, H., ELSHEIKH, H. M., KATAIA, M. M., MARZOUK, R. M., ABDELTWAB, E., ATTA, A. & TAHER, F. A. E.-R. 2023. 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Confocal laser scanning, scanning electron, and transmission electron microscopy investigation of Enterococcus faecalis biofilm degradation using passive and active sodium hypochlorite irrigation within a simulated root canal model. Microbiologyopen, 6 , e00455. MURUGESAN, K., VISHWANATH, S., KADANDALE, S., THANIKACHALAM, Y., PARTHASARATHY, R. & ILANGO, S. 2022. Comparative evaluation of smear layer removal in apical third using four different irrigants with ultrasonic agitation: An in vitro scanning electron microscopy (SEM) analysis. Cureus, 14. NAIR, P., HENRY, S., CANO, V. & VERA, J. 2005. Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after “one-visit” endodontic treatment. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 99 , 231-252. O’CONNELL, M. S., MORGAN, L. A., BEELER, W. J. & BAUMGARTNER, J. C. 2000. A comparative study of smear layer removal using different salts of EDTA. Journal of endodontics, 26 , 739-743. PAQUÉ, F., BALMER, M., ATTIN, T. & PETERS, O. A. 2010. Preparation of oval-shaped root canals in mandibular molars using nickel-titanium rotary instruments: a micro-computed tomography study. Journal of endodontics, 36 , 703-707. PARAGLIOLA, R., FRANCO, V., FABIANI, C., MAZZONI, A., NATO, F., TAY, F. R., BRESCHI, L. & GRANDINI, S. 2010. Final rinse optimization: influence of different agitation protocols. Journal of endodontics, 36 , 282-285. PASHLEY, D. H. 1984. Smear layer: physiological considerations. RATIH, D. N., ENGGARDIPTA, R. A. & KARTIKANINGTYAS, A. T. 2020. The effect of chitosan nanoparticle as a final irrigation solution on the smear layer removal, micro-hardness and surface roughness of root canal dentin. The Open Dentistry Journal, 14. SABINS, R. A., JOHNSON, J. D. & HELLSTEIN, J. W. 2003. A comparison of the cleaning efficacy of short-term sonic and ultrasonic passive irrigation after hand instrumentation in molar root canals. Journal of endodontics, 29 , 674-678. SAMIEI, M., FARJAMI, A., DIZAJ, S. M. & LOTFIPOUR, F. 2016. Nanoparticles for antimicrobial purposes in Endodontics: A systematic review of in vitro studies. Materials Science and Engineering: C, 58 , 1269-1278. SCHÄFER, E. & ZAPKE, K. 2000. A comparative scanning electron microscopic investigation of the efficacy of manual and automated instrumentation of root canals. Journal of Endodontics, 26 , 660-664. SEQUEIRA, P., FEDOROWICZ, Z., NASSER, M. & PEDRAZZI, V. 2007. Ultrasonic versus hand instrumentation for orthograde root canal treatment of permanent teeth. Cochrane Database of Systematic Reviews . SERPER, A. & ÇALT, S. 2002. The demineralizing effects of EDTA at different concentrations and pH. Journal of Endodontics, 28 , 501-502. SIQUEIRA JR, J. F. & DE UZEDA, M. 1996. Disinfection by calcium hydroxide pastes of dentinal tubules infected with two obligate and one facultative anaerobic bacteria. Journal of endodontics, 22 , 674-676. SOCRANSKY, S. S. & HAFFAJEE, A. D. 2002. Dental biofilms: difficult therapeutic targets. Periodontology 2000, 28 , 12-55. SPANGBERG, L. 2002. Instruments, materials, and devices. Pathways of the pulp . SPOLETI, P., SIRAGUSA, M. & SPOLETI, M. J. 2003. Bacteriological evaluation of passive ultrasonic activation. Journal of endodontics, 29 , 12-14. TEJA, A. S. & KOH, P.-Y. 2009. Synthesis, properties, and applications of magnetic iron oxide nanoparticles. Progress in crystal growth and characterization of materials, 55 , 22-45. TENNERT, C., FUHRMANN, M., WITTMER, A., KARYGIANNI, L., ALTENBURGER, M. J., PELZ, K., HELLWIG, E. & AL-AHMAD, A. 2014. New bacterial composition in primary and persistent/secondary endodontic infections with respect to clinical and radiographic findings. Journal of endodontics, 40 , 670-677. UNNIKRISHNAN, M., MATHAI, V., SADASIVA, K., SANTAKUMARI, R. S. M., GIRISH, S. & SHAILAJAKUMARI, A. K. 2019. The Evaluation of Dentin Microhardness After Use of 17% EDTA, 17% EGTA, 10% Citric Acid, MTAD Used as Chelating Agents Combined With 2.5% Sodium Hypochlorite After Rotary Instrumentation: An: In Vitro: SEM Study. Journal of Pharmacy And Bioallied Sciences, 11 , S156-S163. VAN DER SLUIS, L., VERSLUIS, M., WU, M. & WESSELINK, P. 2007. Passive ultrasonic irrigation of the root canal: a review of the literature. International endodontic journal, 40 , 415-426. VERA, J., SIQUEIRA JR, J. F., RICUCCI, D., LOGHIN, S., FERNÁNDEZ, N., FLORES, B. & CRUZ, A. G. 2012. One-versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study. Journal of endodontics, 38 , 1040-1052. VIRDEE, S., SEYMOUR, D., FARNELL, D., BHAMRA, G. & BHAKTA, S. 2018. Efficacy of irrigant activation techniques in removing intracanal smear layer and debris from mature permanent teeth: a systematic review and meta‐analysis. International endodontic journal, 51 , 605-621. XU, C., HUANG, J., JIANG, Y., HE, S., ZHANG, C. & PU, K. 2023. Nanoparticles with ultrasound-induced afterglow luminescence for tumour-specific theranostics. Nature Biomedical Engineering, 7 , 298-312. YANG, G., WU, H., ZHENG, Y., ZHANG, H., LI, H. & ZHOU, X. 2008. Scanning electron microscopic evaluation of debris and smear layer remaining following use of ProTaper and Hero Shaper instruments in combination with NaOCl and EDTA irrigation. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 106 , e63-e71. YANG, S.-E. & BAE, K.-S. 2002. Scanning electron microscopy study of the adhesion of Prevotella nigrescens to the dentin of prepared root canals. Journal of Endodontics, 28 , 433-437. ZHENG, J., NAGASHIMA, K., PARMITER, D., DE LA CRUZ, J. & PATRI, A. K. 2011. SEM X-ray microanalysis of nanoparticles present in tissue or cultured cell thin sections. Characterization of nanoparticles intended for drug delivery , 93-99. 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Al-Mustwfi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYDACCTBpU88vf/gAiCtDrJa0BMkZbAkgLg+xWg4nGNzgMQCxCGvhl25/+OHnDuY8hts9n1/dqLHgYWA/fHQDPi2Sc84YS/aeYStmnHN2m3XOMaDDeNLSbuDTYnAjh0GCt42HsZkhd5txDhtQiwSPGV4t9jfSH//82ybB2MaQ88w45x8RWgwkEsykedsMEnskcpgf57YRoUXiRo6ZtWxbgrEEzzEz5tw+CR42Qn7hn5H++Obbtv9y9sebH3/O+VYnx89++BheLciADRxHbMQqBwHmD6SoHgWjYBSMgpEDAO+MR0aFjjy6AAAAAElFTkSuQmCC","orcid":"","institution":"University of Baghdad","correspondingAuthor":true,"prefix":"","firstName":"Ehsaan","middleName":"S.","lastName":"Al-Mustwfi","suffix":""},{"id":435711004,"identity":"7d448220-92b3-4d76-8846-a662cd929b59","order_by":1,"name":"Hussain F. Al-Huwaizi","email":"","orcid":"","institution":"University of Baghdad","correspondingAuthor":false,"prefix":"","firstName":"Hussain","middleName":"F.","lastName":"Al-Huwaizi","suffix":""}],"badges":[],"createdAt":"2025-03-10 14:08:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6196305/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6196305/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12903-025-06431-2","type":"published","date":"2025-07-08T15:56:57+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79750601,"identity":"4ad5a9a0-bcbf-440b-a8e0-fa1e02a2ae00","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":87238,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic diagram of magnetic field device.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/bd447ac388b4de2dc85cf3a7.png"},{"id":79750612,"identity":"5ac1a9ad-80aa-4410-b1b4-3bff3e8c4600","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":305491,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 1), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/28c4970effb760ef5b4582cf.png"},{"id":79750605,"identity":"120bc3b5-516a-45df-a1de-1fd24493ae1e","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":333606,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 2), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/ead069a6bc00f23eb679f8c5.png"},{"id":79751843,"identity":"28a365ea-30fe-4dd9-9abb-3967c224f32c","added_by":"auto","created_at":"2025-04-02 09:28:16","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":318796,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 3), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/d240941f3559fe5fdc016ed4.png"},{"id":79750603,"identity":"70227132-506b-44fe-9a3c-6cedf98cf6d5","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":345317,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 4), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/5d92991b504fbdf74933cda4.png"},{"id":79750610,"identity":"af0cddb8-a115-4a10-a95a-222ac1de35b7","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":304140,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 5), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/3319b1d15c351769c83e26e3.png"},{"id":79750614,"identity":"8f3f187d-179d-4df0-ad44-5b5033082beb","added_by":"auto","created_at":"2025-04-02 09:20:16","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":308951,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM of canal wall in (protocol 6), A) coronal, B) middle, and C) apical sections.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/4c9adaf56ba3ccda48431c86.png"},{"id":86699241,"identity":"fddc36cf-91e4-485b-8993-e36ddc5bb5ff","added_by":"auto","created_at":"2025-07-14 16:04:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2956130,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6196305/v1/8e50f997-044d-4fd3-9d73-04ee22a8246f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessment of smear layer removal utilizing a conservative root canal instrumentation technique involving magnetically agitated irrigation with iron paramagnetic nanoparticles","fulltext":[{"header":"Background","content":"\u003cp\u003eEndodontic infection is primarily caused by bacteria, which is considered as an essential etiological factor for both initial and recurrent infection (Nair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). The bacterial cells' attachment to the surface using a self-manufactured extracellular polymeric substance (EPS) (Donlan and Costerton, 2002, Balaban, 2008) leads to the formation of a biofilm of multicellular microbial communities that may include one or more species. These biofilms are recognized as significant virulence factors, exhibiting resistance levels up to 1500 times greater than planktonic cells (Socransky and Haffajee, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2002\u003c/span\u003e) (Hall-Stoodley et al., 2004). The entire removal of these microbes during treatment not only affects the successful treatment but also prevents the recolonization of microbes within the treated root canal system (Bystr\u0026ouml;m and Sundqvist, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1983\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe movement of bacteria within the tubules is associated with canal infections (Siqueira Jr and de Uzeda, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1996\u003c/span\u003e), and it can penetrate through the tubules at a distance (300\u0026ndash;1500 \u0026micro;m). Unfortunately, the conventional protocol of the root canal irrigant cannot approach this depth into the dentinal tubules (de Paz, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), because of the anatomic complexities (Nair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). As a result, bacteria and their byproduct may persist around dentinal tubules even after conventional endodontic treatment (Tennert et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, research by Vera et al. (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) investigated the mechanical cleaning and disinfection of root canals, revealing that microorganisms might inevitably persist within the canal even after treatment (Vera et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Paqu\u0026eacute; et al. (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) showed that the areas of the flattened, oval, or C-shaped canals may stay untouched by instruments, especially at the wide canal diameter with varying cross-sections (Paqu\u0026eacute; et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe agitation of irrigant inside the root canal system can be performed manually (Cunningham et al., 1982) or automatically (Sabins et al., 2003). Conventional irrigation techniques using sonic or ultrasonic activation, which involve transverse oscillation, is an inefficient method because of multiple touch points between the root canal walls and the file, especially at a narrow apical area (Boutsioukis et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) and cannot clean the root canal system efficiently (Sequeira et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Since the development of new technology in mechanical instrumentation and cleaning, still not all the root canal walls are cleaned because of the disparity between the complexities of the canal anatomy and instrument design (Del Fabbro et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNanotechnology is the manufacture of structures at a scale of 100 nm or smaller, a near-atomic scale, to form new materials, structures, and devices (Samiei et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Magnetic nanoparticles (MNPs) are used in different fields of technology such as biomedicine (El-Boubbou, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e), root canal irrigant (Bukhari et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), enhancement of antibacterial activity to disinfection technology (Al-Bazaz et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), improved dentin\u0026rsquo;s adhesion without changing adhesive properties (Garcia et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), and modified root canal sealer under the process of a magnetic field to penetrate more deeply with enhanced periapical healing (Guo et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn nanomedicine, the primary application involves the application of an external magnetic field to guide nanoparticles toward the target area, particularly employing superparamagnetic iron oxide nanoparticles (SPIONs) coated with organic or inorganic materials for drug delivery (El-Boubbou, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2018b\u003c/span\u003e) (Al-Badr and Al-Huwaizi, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The magnetite (Fe₃O₄) is better than natural iron oxide (black iron oxide) in spinel structure and displays the highest magnetism compared with another phase of IONP (Teja and Koh, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe tooth structure may be affected throughout exposure to irrigant solutions, potentially altering the integrity of the mechanical and chemical properties of natural enamel and dentin. Successful endodontic treatment depends on the use of irrigant solutions that do not alter the properties of the tooth structure (Ari et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis research aims to develop a new endodontic irrigant containing superparamagnetic iron oxide nanoparticles (SPIONs) to enhance root canal cleaning without the need for extensive canal shaping instruments, using an external magnetic field for guidance of the irrigant toward the target area and agitate the irrigant inside the root canal system. This novel approach showed the potential to bypass traditional instrumentation methods and prevent the loss of root structure when superparamagnetic iron oxide nanoparticles (SPIONs) and a magnetic field are employed and can be considered a promising strategy to enhance the cleaning efficiency of root canal systems.\u003c/p\u003e \u003cp\u003eThis study aimed to determine the optimum effect of iron oxide nanomagnet particles (IONPs) in cleaning the surface of the root canal and open dentin tubules and analyzing the dispersion of iron ions with measurement concentration on the dentinal walls.\u003c/p\u003e \u003cp\u003eThe null hypothesis was that iron oxide nanomagnet particles (IONP) irrigant agitation with a magnetic field would not enhance root canal cleaning and be effective in dentin structure.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSample collection\u003c/h2\u003e \u003cp\u003eSixty intact, non-carious human maxillary first molars were collected from the mixed population for the therapeutic case and stored in a 0.2% thymol solution for decontamination, not exceeding one month (Unnikrishnan et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSamples selection\u003c/h3\u003e\n\u003cp\u003eThe magnifying lens was employed to inspect and exclude any teeth with anomalies, carious lesions, cracks, or open root apex (Aksel et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Buccal and proximal radiographs were utilized to confirm the existence of a single straight palatal canal with a closed apex. To eliminate any variability in access preparation, palatal roots of the teeth were sectioned perpendicular to the longitudinal axis of the roots using 0.3 diamond discs No.913 (Komet, Germany) mounted on a straight handpiece at a low-speed (1500 rpm) (NSK, Japan) with a continuous flow of tap water. Hence, all the roots were measured 12 mm in length from the apex coronally and fixed longitudinally in clear acrylic molds using additional silicon (Zermak, Italy) to facilitate handling during the instrumentation process.\u003c/p\u003e\n\u003ch3\u003eSample preparation\u003c/h3\u003e\n\u003cp\u003eTo achieve standardized procedures throughout the study, a single operator performed all the experiments to minimize variables during specimen preparation. The barbed broach was used to remove pulpal tissue, and a stainless-steel K-file size 10 (Dentsply, Maillefer, Switzerland) was inserted into the root canal until the tip was seen just exiting at the apical foramen, observing under a magnifying lens. The critical working length was obtained by subtracting 1 mm from the length. All the roots were instrumented with the conventional stainless-steel K-files sizes from size 15 until size 20, except the control group. The file was rotated clockwise in the root canal with slight pressure; then debris was removed by pulling the file slightly outward with clockwise rotations (Ardila et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The instruments were regularly cleaned to remove debris from the flutes. Each specimen requiring enlargement of more than file size 20 (Dentsply, Maillefer, Switzerland) was rejected and replaced by another one. A double-sided diamond disc, attached to a straight handpiece with water cooling, was used to create two longitudinal grooves on both the buccal and lingual sides (without deeply reaching the canal). This step aimed to aid in splitting the teeth into two segments with a chisel, following the groove's path. The specimens were subsequently placed in phosphate-buffered saline (PBS) (Sigma, USA). The tooth samples were then randomly assigned to six experimental groups.\u003c/p\u003e\n\u003ch3\u003eGeneration of the magnetic field to agitation of iron oxide nanoparticles\u003c/h3\u003e\n\u003cp\u003eThe magnets used in the study to generate the magnetic field consisted of two parts (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e):\u003c/p\u003e \u003cp\u003eFirst permanent magnet: Super magnet neodymium 35, round-shaped, and diameter 18 mm (K\u0026amp;J Magnetics Inc., USA: Neodymium 35). The magnetic field strength remains constant, with 1000 gauss in the peripheral zone and 750 gauss in the central zone, and it does not lose its magnetic property when magnetism. The magnet is positioned 10 mm from the palatal side of the root.\u003c/p\u003e \u003cp\u003eSecond electromagnet: It consisted of a coil of wire wrapped around the iron core (self-made). When an electrical current is applied to this device, a magnetic field is generated, and then a magnet is manufactured. The magnetic field strength can be adjusted using a self-made device that controls the electric current from a direct current (DC) power supply of 30 V. The device allows changes in the polarity and frequency (on-off cycles option, 10 times per second). The magnetic field strength in this study is 1300 gauss in the peripheral zone and 900 gauss in the central zone, which is stronger than the permanent magnet to ensure the agitation of iron oxide nanoparticles (IONP) within the root canal system. The electromagnet is located 10 mm from the buccal side of the root. The field strength between the two magnets is 450 gauss.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003ePreparation of irrigation solution\u003c/h3\u003e\n\u003cp\u003eA solution consisting of 100 mg of the iron oxide nanoparticles (Fe₃O₄) (Us research nanomaterials Inc., Huston, USA) of dried powder (weighed using an electronic weight scale) (Radwag, Poland) was mixed with 10 ml of deionized water (10 grams of IONPs powder in one litre of deionized water whereas the concentration of the iron oxide nanoparticles solution was 1%) according to the pilot study, bacteriological test, and cytotoxicity test, and then using ultrasonic mixing device at twenty minutes to obtain a clear colloidal dispersion (Al Bazaz et al., 2023).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSample Grouping\u003c/h2\u003e \u003cp\u003eGroup 1(protocol 1): Control.\u003c/p\u003e \u003cp\u003eGroup 2 (protocol 2): Irrigation with ultrasound with no nanomagnet particles: Agitation of irrigant 50 ml of normal saline using an ultrasound device (Weedpecker U600, China) for 5 minutes.\u003c/p\u003e \u003cp\u003eGroup 3 (protocol 3): Agitation of irrigant 50 ml of IONP using an ultrasound device for 5 minutes.\u003c/p\u003e \u003cp\u003eGroup 4 (protocol 4): Agitation of irrigant 50 ml of IONP using a magnetic field with endodontic needle double side vented, gauge 30 (Hunterline, China) for 5 minutes. The syringe was attached to an electrically programmable syringe pump to release the irrigant at a flow rate of 10 ml /min.\u003c/p\u003e \u003cp\u003eGroup 5 (protocol 5): Agitation of irrigant 50 ml of IONP using a magnetic field with an ultrasound device for 5 minutes.\u003c/p\u003e \u003cp\u003eGroup 6 (protocol 6): Irrigation with EDTA 17% for 1 minute.\u003c/p\u003e \u003cp\u003eThe stainless-steel instrument E 62 used in the ultrasound device has a file diameter of 0.3 mm, taper 0%, and a working part length of 16 mm (Weedpecker U600, China). The tip of the file is held 2 mm shorter than the working length in the centre of the channel and moved in a 2\u0026ndash;3 mm up and down direction. The file was set at power 50% as per the manufacturer's instructions.\u003c/p\u003e \u003cp\u003eThe roots were finally irrigated with 50 ml of normal saline through ultrasound devices for 5 minutes in each treatment was performed with IONP or EDTA 17%.\u003c/p\u003e \u003cp\u003e \u003cb\u003eUtilize field emission scanning electron microscopy\u003c/b\u003e (\u003cb\u003eFE-SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis.\u003c/b\u003e\u003c/p\u003e \u003cp\u003eTooth specimens were isolated from clear acrylic molds, and two longitudinal grooves were opened by using a chisel and mallet. One half was prepared for SEM evaluation, and the second was for a microhardness test. The halves of the roots were washed with phosphate-buffered saline (PBS), then fixated by immersing in a solution containing 4% Glutaraldehyde in 0.1 mol/L sodium cacodylate buffer (BDH, England) (pH 7.4) at 4\u0026deg;C overnight. Then, dehydrated in a step sequence of alcohol (Honeywell, Germany) (30, 50, and 70%) at 10 minutes, (90, and 100%) at 20 minutes, followed by immersion in hexamethyldisilazane (Merk, Germany) for 5 min, and air-drying (George and Kishen, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) (Mohmmed et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The halving of the root was mounted on aluminum stubs, sputter-coated with gold, and analyzed using field emission scanning electron microscopy (FE-SEM) (InspectTM F50) (H\u0026uuml;lsmann et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1997\u003c/span\u003e) (Sch\u0026auml;fer and Zapke, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e) (Ahlquist et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) (H\u0026uuml;lsmann et al., 2003). Each root was divided into three regions: coronal, middle, and apical, with one point selected from the center of the canal in each region for examination under magnifications 2500 X (George and Kishen, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Hulsmann scoring with a 5-score index was used to determine the optimum effect of iron oxide nanomagnet particles (IONP) cleaning the root canal surface, opening dentinal tubules, and removing the smear layer in each specimen section (H\u0026uuml;lsmann et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1997\u003c/span\u003e) (Abdelkafy et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e):\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eScore 1\u003c/strong\u003e \u003cp\u003eNo smear layer; dentinal tubules are uncovered.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eScore 2\u003c/strong\u003e \u003cp\u003eSmall quantity of smear layer; some dentinal tubules are covered.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eScore 3\u003c/strong\u003e \u003cp\u003eUniform distribution of smear layer; only a few dentinal tubules are uncovered.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eScore 4\u003c/strong\u003e \u003cp\u003eA large quantity of uniform smear covers the entire root canal wall.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eScore 5\u003c/strong\u003e \u003cp\u003eLack of uniformity and heavy smear layer.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThe scoring was confirmed by a second examiner who was unaware of the treatment methods or experimental irrigants used.\u003c/p\u003e \u003cp\u003eThe energy dispersive X-ray spectroscopy (EDS) (Thermo Fisher Scientific, Nederland) (EDS)(Zheng et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) (Ali, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) was used to determine the concentrations of iron (Fe) elements and measure the effect of magnetism on the dispersive Fe ions in the root canal walls of each section of groups.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS 26. The Shapiro-Wilks test checked the data's normality. Nonparametric Kruskal Wallis and Mann Whitney test compared scores of groups at coronal, middle, and apical sections in each group. Parametric test of One-Way ANOVA and Tuckey posthoc tests were used to compare between continuous data. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e1. Assessment of root canal surface debridement and open dentin tubules by FESEM\u003c/h2\u003e\n \u003cp\u003eThe result of comparing the amount of smear layer of all protocols with group 1 (control) (Fig.\u0026nbsp;2), group 2 (agitation of irrigant normal saline using an ultrasound device) showed a higher mean rank of smear layer score (Fig.\u0026nbsp;3) than group 3 (agitation of irrigant IONP using ultrasound device) (Fig.\u0026nbsp;4), group 4 (agitation of irrigant IONP using a magnetic field with endodontic needle) (Fig.\u0026nbsp;5) showed the higher mean rank of smear layer score than group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device) (Fig.\u0026nbsp;6), group 6 (EDTA 17%) showed the higher mean rank of smear layer score especially in middle and apical section (Fig.\u0026nbsp;7) than group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device)\u003c/p\u003e\n \u003cp\u003eIn all study groups, there were significant differences in the mean rank between groups in coronal, middle, and apical sections, as shown in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDescriptive data of smear layer removal scoring between groups after the use of different protocols.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"8\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSection\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGroup\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean rank\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value*\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003e\u003cstrong\u003eCoronal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56.20\u003csup\u003ec,f,i\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52.80\u003csup\u003eb,e,h\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.70\u003csup\u003eg,h,i\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.15\u003csup\u003ed,e,f\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.10\u003csup\u003ea,b,c\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003e\u003cstrong\u003eMiddle\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55.10\u003csup\u003ed,g,h\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46.25\u003csup\u003eb,f\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.70\u003csup\u003eh\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36.80\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.45\u003csup\u003ea,b,c,d\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.70\u003csup\u003ee,f,g\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003e\u003cstrong\u003eApical\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57.00\u003csup\u003ec,e,g\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57.002\u003csup\u003ea,d,f\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.00\u003csup\u003ef,g\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.65\u003csup\u003ea,b,c\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46.80\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eWhen comparing the amount of smear layer, group 5 (agitation of irrigant IONP using a magnetic field with ultrasound device) showed the lowest mean ranks of smear layer score in the middle and apical section, while showing higher mean ranks in the coronal section. In contrast, group 4 (agitation of irrigant IONP using a magnetic field with an endodontic needle) showed the lowest mean ranks of smear layer score in the coronal section and higher mean ranks in the middle and apical sections. Group 6 (EDTA 17%) showed a lower mean rank of smear layer score in the coronal section while a higher mean rank in the apical section (Fig. 7). There was a significant difference in the mean rank of smear layer scores between coronal, middle and apical section in groups 2,4 and 6 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The most effective irrigation protocol was observed in group 5 (agitation of irrigant IONP using a magnetic field with an ultrasound device). This method significantly lowers the amount of smear layer, particularly in the middle and apical sections.\u003c/p\u003e\u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e2. Assessment of the concentrations of Iron (Fe) elements and measurement of the effect of magnet in dispersive Fe ions on the root canal wall by Energy Dispersive X-ray (EDS).\u003c/strong\u003e\u003c/p\u003e\n \u003c/span\u003e\n \u003cp\u003eThe data followed a normal distribution. A one-way ANOVA and Tukey post hoc tests were used to compare the groups and sections. There were significant differences in the level of iron element weight percentage between groups at coronal, middle, and apical sections. There was a minimum precipitation of ions in group 3 (agitation of irrigant IONP using an ultrasound device) at the apical section compared to the middle and coronal sections, followed by group 5 (agitation of irrigant IONP using a magnetic field with an ultrasound device) there was a minimum precipitation in the middle section compared to the coronal and apical sections, and followed by group 4 (agitation of irrigant IONP using a magnetic field with an endodontic needle) there was a minimum precipitation in the apical section compared to the middle and coronal sections. This is presented in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDescriptive data of iron weight between groups at coronal, middle, and apical sections.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"8\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSection\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGroup\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStd. Deviation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003eCoronal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003eMiddle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"6\"\u003e\n \u003cp\u003eApical\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"6\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eG6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe smear layer is a thin film, approximately 1-2 μm thickness, that forms on the root canal wall (Mader et al., 1984). It comprises remnants of vital or necrotic pulp tissue, dentin particles, bacterial biofilm, and irrigants that block the opening of the dentinal tubule (Virdee et al., 2018). This layer must be removed because it serves as a microbial reservoir (Pashley, 1984), limit the penetration action of the disinfecting agent, and separation between filling materials and the canal wall, ultimately compromising the sealing ability of the root canal (Yang and Bae, 2002).\u003c/p\u003e\n\u003cp\u003eThe success of endodontic treatment has an impact relation with the irrigation protocol, as no single irrigant solution can meet all the required criteria (Haapasalo et al., 2010). The irrigation protocols should also remove the smear layer and debris from all root canal system (Baugh and Wallace, 2005).\u003c/p\u003e\n\u003cp\u003eIn this study utilized various irrigant solutions, including normal saline, IONP, and 17% EDTA. To optimize the cleaning of the root canal system while conservating the maximum tooth structure, six groups were activated using different activation techniques, including ultrasonic oscillation (Van der Sluis et al., 2007), and using an external magnetic field (Al-Badr and Al-Huwaizi, 2020), either alone or in combination with ultrasonic oscillation.\u003c/p\u003e\n\u003cp\u003eIn this investigation, the passive ultrasound protocol of irrigation is more effective than syringe needle irrigation in eliminating the remnants of pulpal tissue, bacterial biofilm, and smear layer (Van der Sluis et al., 2007). This finding aligns with another study that recommends using nanoparticles with an ultrasound device in biomedical applications (Xu et al., 2023). Another study investigated the direct effect when using a sterile normal saline irrigant to remove planktonic bacteria from the root canal\u0026nbsp;(Spoleti et al., 2003). In this study, normal saline irrigant with ultrasound was less effective than other nanoparticle irrigants. The irrigant was delivered through the hollow, smooth wire to the root canal\u0026nbsp;(Gutarts et al., 2005). The apical region of root canals showed less debris and smear layer than the coronal region because of the high density of acoustic streaming at the apical regions. Cameron, in 1983, found that a 3-min and 5-min period of passive ultrasound irrigation was most effective in removing the smear layer, whilst a 1-min irrigation was ineffective\u0026nbsp;(Cameron, 1983). These results are coincident in the study as irrigation at 5-min periods. In contrast to another study, it was found that ultrasonic irrigation was unable to remove the smear layer (Baker et al., 1988), but in this study, it was found that applying nano irrigant with file size 15 of an ultrasound device can remove the smear layer with a conservative tooth structure. Lumley et al. 1992 recommended a high volume of microstreaming only with a file size of 15, especially when the tips of the file vibrate freely in an irrigant solution with maximizing removal of debris\u0026nbsp;(Lumley et al., 1992). Other study found that the benefits of using ultrasonic irrigation technique only for the final irrigation after finished of hand instrumentation\u0026nbsp;(Van der Sluis et al., 2007).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn this study, the agitation of IONP irrigant demonstrated a lower mean rank of smear layer score compared to normal saline when using an ultrasound device. This finding aligns with the results of Murugesan et al., who showed a higher smear layer score after using normal saline irrigant activated by ultrasound (Murugesan et al., 2022).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;In this study, EDTA 17% was used as an irrigant, which binds to calcium ions in dentin and dissolves the inorganic part of smear layers (Koga et al., 2015). However, complete removal of the smear layer is not achievable (O’Connell et al., 2000), with its most effective action occurring during the first minutes of application (Spangberg, 2002) (Serper and Çalt, 2002). Also, the research showed catastrophic damage to peritubular dentin when the time of application remains between 1-10 minutes (Calt and Serper, 2002). Another study reported that applying 10 ml of EDTA 17 % solution for one minute effectively removed the smear layer from the canal walls. In contrast, prolonged exposure to dentin increases the degree of demineralization (Calt and Serper, 2002, Ali et al., 2022, Ratih et al., 2020). Additionally, in this study, it was observed that the apical section of the canals showed inferior cleaning efficiency compared to the middle and coronal sections. The reason for the incomplete removal may be due to the failure of irrigants to reach the apical section, and the coincidence with other studies (Yang et al., 2008) (Gambarini and Laszkiewicz, 2002).\u003c/p\u003e\n\u003cp\u003eThere is no published data about the efficiency of the magnet activation system with IONP in cleaning the root canal, opening dentinal tubules, and removing the smear layer in the coronal, middle, and apical sections of straight root canals. Two methods have been used to evaluate this effect of IONP: one uses extracted natural teeth, and the other simulates root canals. \u0026nbsp;Otherwise, simulated root canals allow a uniform root canal diameter and length but are not used in this study because dentin structures may not be identical. All the investigations of root canal treatment techniques, cleaning and shaping, irrigation protocol, and irrigant solution have focused on the cleaning ability of each system as the main objective but excluded the core goal of treatment, which involves the conservative structure of the root canal and removes the probability of instrument fracture.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHence, new strategies are essential, as achieving optimal root canal cleaning can significantly enhance the success of treatment outcomes. To conform to this goal, we propose using iron oxide nanoparticles (IONPs) in combination with an external magnetic field and ultrasound activation as an innovative approach to more effectively open dentinal tubules compared to existing methods.\u003c/p\u003e\n\u003cp\u003eThe use of ultrasonic activation with a magnetic field better results in the penetration depth of the irrigant. This is in agreement with another study that found hydrodynamic irrigation improved the penetration depth of irrigant solution into the root canal wall dentine\u0026nbsp;(Paragliola et al., 2010). The application of an external magnetic field to guide nanoparticles toward the target area is the major application in nanomedicine with superparamagnetic iron oxide nanoparticles in drug delivery (El-Boubbou, 2018a) (Al-Badr and Al-Huwaizi, 2020).\u003c/p\u003e\n\u003cp\u003eUnder the situation of this study, all irrigation activation protocols using IONP were best compared to ultrasonic irrigation with normal saline. Importantly, the findings demonstrated that utilizing IONP as an irrigant, combined with magnet activation and ultrasonic techniques, yielded the most effective results for removing debris and the smear layer throughout the canal system.\u003c/p\u003e\n\u003cp\u003eThis study showed that activating the IONP irrigant was significantly more effective in removing the smear layer, regardless of the agitation method used. This was evident when comparing the results with the use of saline solution alone, which did not exhibit any effect on cleaning the root canal and removing the smear layer.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eCompared to the control group, the use of IONP irrigant agitation with a magnetic field did not affect dentinal structure while enhancing root structure compared to EDTA irrigation, cleaning the surface of the canal, open dentin tubules, uniform distributions of Fe ions with minimum precipitation, which may indicate only a negligible extrusion beyond the root canal and can be regarded as effective options for endodontic treatment while preserving the tooth structure.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eSPIONs \u0026nbsp; \u0026nbsp;Superparamagnetic iron oxide nanoparticles solution\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIONP \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;iron oxide nanomagnet particles\u003c/p\u003e\n\u003cp\u003eFe \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Iron\u003c/p\u003e\n\u003cp\u003eFE-SEM \u0026nbsp; Field emission scan electron microscopy\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEDS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Energy-dispersive X-ray spectroscopy\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEPS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Extracellular polymeric substance\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePBS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Phosphate-buffered saline\u0026nbsp;\u003c/p\u003e\n\u003cp\u003emol/L \u0026nbsp; \u0026nbsp; \u0026nbsp; Moles per liter\u003c/p\u003e\n\u003cp\u003eml /min\u0026nbsp; \u0026nbsp; \u0026nbsp;Milliliters per minute.\u003c/p\u003e\n\u003cp\u003eMNPs \u0026nbsp; \u0026nbsp; \u0026nbsp;Magnetic nanoparticles\u0026nbsp;\u003c/p\u003e\n\u003cp\u003enm \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Nanometer\u003c/p\u003e\n\u003cp\u003eµm \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Micrometer\u003c/p\u003e\n\u003cp\u003emm \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Millimeter\u003c/p\u003e\n\u003cp\u003eDC \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Direct current\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFe₃O₄ \u0026nbsp; \u0026nbsp; \u0026nbsp; Iron oxide\u003c/p\u003e\n\u003cp\u003eV \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Voltage\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no acknowledgments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis project did not receive any funding.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis experimental study was executed according to the ethical principles of the World Medical Association Declaration of Helsinki (version 2008). The Scientific Committee of the College of Dentistry-University of Baghdad (No. 1024\u0026nbsp;on 30/1/2025) has approved the collection of the teeth extracted for different purposes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for application\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eABDELKAFY, H., ELSHEIKH, H. M., KATAIA, M. M., MARZOUK, R. M., ABDELTWAB, E., ATTA, A. \u0026amp; TAHER, F. A. E.-R. 2023. 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SEM X-ray microanalysis of nanoparticles present in tissue or cultured cell thin sections. \u003cem\u003eCharacterization of nanoparticles intended for drug delivery\u003c/em\u003e\u003cstrong\u003e,\u003c/strong\u003e 93-99.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Magnetic agitation, open dentinal tubules, irrigation, nanoparticles, iron ions.","lastPublishedDoi":"10.21203/rs.3.rs-6196305/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6196305/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: The development of new technology in mechanical instrumentation does not completely clean all the root canal walls because of the disparity between the complexities of canal anatomical and instrument design. This study aimed to determine the optimum effect of iron oxide nanomagnet particles (IONPs) in cleaning the surface of the root canal and open dentin tubules, as well as analyze the dispersion of iron ions on the dentinal walls.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterial and methods: \u003c/strong\u003eSixty intact extraction teeth were used and divided into six groups as stated by agitation protocol of irrigant: Group 1: Control, Group 2: Normal saline with ultrasound, Group 3: IONP with ultrasound. Group 4: IONP with magnetic field using an endodontic needle. Group 5: IONP with magnetic field using ultrasound, and Group 6: 17% ethylenediaminetetraacetic acid (EDTA). Field emission scan electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine cleaning root canal surfaces, opening dentinal tubules, removing the smear layer, and the percentage dispersion of ions on the root canal wall. \u0026nbsp;The nonparametric tests of the Kruskal-Wallis, Mann-Whitney, and parametric test of One-Way ANOVA and Tuckey posthoc tests were used to compare irrigation protocols.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: Compared to the other groups, the agitation of irrigant IONP using a combination of a magnetic field and an ultrasound device proved to be the most effective. Additionally, the agitation of irrigant IONP using only an ultrasound device was more effective than using only normal saline with an ultrasound device. Iron ions have low percentages, perfect dispersions, and minimal precipitation in the apical section of the root canal wall.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Compared to the control group, the utilization of IONP irrigant agitation with a magnetic field did not affect dentinal structure while enhancing the cleaning of the canal surface, opening dentin tubules, and achieving a uniform distribution of iron ions with minimal precipitation. These findings may hold promise as a tool for endodontic treatment while preserving tooth structure.\u003c/p\u003e","manuscriptTitle":"Assessment of smear layer removal utilizing a conservative root canal instrumentation technique involving magnetically agitated irrigation with iron paramagnetic nanoparticles","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-02 09:20:11","doi":"10.21203/rs.3.rs-6196305/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-28T07:41:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-25T23:18:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"246710306231156122206282153897868935293","date":"2025-04-25T16:41:19+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-29T12:33:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"205402668110830857790818971172430384662","date":"2025-03-24T13:09:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-24T08:57:31+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-24T08:54:32+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-24T08:14:22+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-23T14:25:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-03-23T14:24:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"35687da2-e35a-4908-ac19-fb9b805b3c25","owner":[],"postedDate":"April 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-14T15:58:37+00:00","versionOfRecord":{"articleIdentity":"rs-6196305","link":"https://doi.org/10.1186/s12903-025-06431-2","journal":{"identity":"bmc-oral-health","isVorOnly":false,"title":"BMC Oral Health"},"publishedOn":"2025-07-08 15:56:57","publishedOnDateReadable":"July 8th, 2025"},"versionCreatedAt":"2025-04-02 09:20:11","video":"","vorDoi":"10.1186/s12903-025-06431-2","vorDoiUrl":"https://doi.org/10.1186/s12903-025-06431-2","workflowStages":[]},"version":"v1","identity":"rs-6196305","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6196305","identity":"rs-6196305","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}