Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study

Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study Erdi KARATAŞ, Faruk ÖZTEKİN This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8434085/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Objective This study aimed to compare, using micro–computed tomography (µCT), the effects of the XP-Endo Finisher (XP-EF) and Gentlefile Brush (GFB) files—used as supplementary instrumentation following Ni–Ti retreatment—on the volume of remaining root canal filling material in oval-shaped root canals. Materials and Methods Twenty single-rooted, single-canal mandibular premolars with oval-shaped canals extracted for periodontal or orthodontic reasons were included. The canals were prepared up to size F4 using the ProTaper Universal system, obturated with gutta-percha and AH Plus, and incubated for one month. After initial µCT scanning, the filling material was removed using the ProTaper Universal Retreatment system, and the specimens were allocated into two groups according to the supplementary instrumentation: XP-EF or GFB. A second µCT scan was performed after the additional instrumentation procedures. Results A statistically significant reduction in the volume of filling material was observed in both groups (p < 0.05). However, the volumetric reduction achieved in the XP-EF group was significantly greater than that in the GFB group (p < 0.05). Complete removal of the filling material was not achieved with either method. Conclusion Although both supplementary systems were effective in reducing residual filling material, XP-Endo Finisher demonstrated superior performance in oval-shaped root canals. Root canal retreatment Oval-shaped root canals Removal of filling remnants Micro-computed tomography XP-Endo Finisher Gentlefile Brush Figures Figure 1 Figure 2 Figure 3 Introduction The primary objective of endodontic treatment is the elimination of microbial content from the root canal system, biomechanical shaping of the canal, and obturation of the prepared space with a hermetic filling material. Contemporary root canal treatment is considered a reliable therapeutic approach, with reported success rates exceeding 90% ( 1 ). Nevertheless, treatment failure may still occur in certain clinical situations ( 2 ). Residual necrotic pulp tissue ( 3 ), inadequate or overextended root canal fillings ( 4 ), the presence of fractured instruments within the canal ( 5 ), coronal leakage ( 6 ), mechanical perforations ( 7 ), root fractures ( 8 ), persistence of periradicular lesions ( 5 ), and periodontal diseases ( 9 ) are among the principal factors adversely affecting treatment outcomes. In cases of failure, the main treatment options aimed at retaining the tooth in the oral cavity include surgical endodontic procedures and nonsurgical root canal retreatment. Owing to its conservative nature, nonsurgical retreatment is preferred as the first-line approach in most cases. Both treatment modalities have been reported to demonstrate high short-term success rates ( 10 ). During retreatment procedures, various techniques are employed for the removal of root canal filling materials, including mechanical systems, ultrasonic devices, heat carriers, solvents, and laser-based methods ( 11 ). In recent years, nickel–titanium (Ni–Ti) rotary file systems used with torque-controlled motors have enabled more effective removal of filling materials from the root canal system ( 12 ). Several Ni–Ti retreatment systems, such as ProTaper Universal Retreatment, DRace, Mtwo, R-Endo, Reciproc, and OneShape, are currently available for clinical use. However, none of the currently available techniques is capable of completely eliminating root canal filling material ( 13 ). Residual filling material adhering to the canal walls should be removed, as it may harbor bacteria and adversely affect the sealing ability of the obturation ( 14 ). The circular preparation motion of Ni–Ti rotary instruments may leave extensive dentin surfaces uninstrumented, particularly in oval-shaped root canals ( 15 ). Previous studies have reported that, due to the complex morphology of oval canals, cleaning and shaping procedures are more challenging and a substantial portion of the dentinal walls does not come into adequate contact with the instruments ( 16 ). Various methods have been employed to evaluate the amount of residual filling material following retreatment, including radiographic assessment ( 17 ), clearing techniques ( 18 ), examination of root sections ( 19 ), and micro–computed tomography (micro-CT) analysis ( 20 ). Micro–computed tomography is a reliable, nondestructive method that provides both qualitative and quantitative data, allowing volumetric comparison of root canal morphology before and after instrumentation without causing structural damage to the specimens ( 21 , 22 ). In this context, the aim of the present study was to compare, using micro-CT, two different supplementary instrumentation systems designed to reduce the amount of residual filling material in oval-shaped root canals following retreatment. The ProTaper Universal system is a Ni–Ti rotary file system with a variable taper design, consisting of three shaping files (SX, S1, S2) and three finishing files (F1, F2, F3). Developed from the conventional ProTaper system, it aims to provide efficient canal preparation through increased flexibility and an optimized cross-sectional design ( 23 ). Its convex triangular cross-section, improved flute geometry, and non-cutting tip design enhance debris removal while allowing safe operation. Modified outer surfaces and a variable helical angle provide high cutting efficiency, while reduced contact with dentin decreases the screwing-in effect ( 23 ). The ProTaper Universal Retreatment (PTUR) system is a three-step filling removal system composed of D1, D2, and D3 files, which are used for the removal of filling material from the coronal, middle, and apical thirds of the canal, respectively. The D1 file, with an active tip, facilitates easy penetration into the filling material, while the files have taper angles of 9%, 8%, and 7% and tip sizes of 30, 25, and 20, respectively. Their working lengths are 16, 18, and 22 mm, and the convex triangular cross-section ensures effective cutting efficiency. The non-cutting tip design of the D2 and D3 files reduces the risk of perforation and ledge formation ( 24 ). The XP-Endo Finisher (FKG Dentaire, Switzerland) is a size 25, non-tapered instrument used during the final stage of root canal cleaning. Owing to its high flexibility, it adapts to the canal morphology and enhances the cleaning of irregular areas. Manufactured from a temperature-responsive Ni–Ti alloy, the file remains straight in the martensitic phase at room temperature and transforms into the austenitic phase at body temperature, exhibiting an approximate 1.5 mm expansion at its tip ( 25 ). When operated in continuous rotation, it provides three-dimensional cleaning in hard-to-reach areas without damaging dentin, while preserving the original canal anatomy. Root canal irrigation alone is known to be insufficient in generating adequate hydrodynamic forces to remove biofilms adhering to dentin walls ( 26 ); to overcome this limitation, irrigant activation techniques have been developed ( 27 ). The circular preparation pattern of rotary systems may lead to inadequate cleaning, particularly in oval canals, and residual organic debris on the canal walls can promote microbial recontamination ( 28 ). Consequently, adaptive systems such as the Self-Adjusting File (SAF) and Gentlefile Brush have been designed to enhance cleaning in complex canal anatomies. The Gentlefile Brush activates the irrigant at high speed, facilitating the removal of residual material, especially in the apical region, while the vortical flow generated by centrifugal forces increases contact between the irrigant and dentin surfaces, optimizing biofilm and debris removal ( 29 ) (Figs. 1 ). Micro–computed tomography (micro-CT) is based on principles similar to clinical computed tomography; however, its micrometer-level resolution enables detailed sectional evaluation of small specimens, making it a reliable imaging modality in endodontic research ( 30 , 31 ). A micro-CT system consists of an X-ray source, a motorized rotating stage, an image intensifier, a CCD camera, and an image processing unit ( 31 ). Compared with clinical CT, specimen rotation and a reduced focal spot size (5–10 µm) enhance image quality and spatial resolution ( 32 ). As a nondestructive three-dimensional imaging technique, micro-CT allows virtual sectioning without compromising specimen integrity and enables comprehensive qualitative and quantitative evaluation of dentin mineral density, root canal filling volume, canal morphology, and residual filling material before and after retreatment procedures ( 22 , 33 , 34 ). Materials and Methods This in vitro study was conducted using the shared infrastructure of the Department of Endodontics, Faculty of Dentistry, Fırat University, and the Research Laboratory of the Faculty of Dentistry, Erciyes University. Ethical approval was obtained from the Fırat University Non-Interventional Research Ethics Committee (04 March 2020, No. 382607). A total of 20 mandibular premolar teeth extracted for orthodontic or periodontal reasons were included in the study. Root canal morphology was evaluated using periapical radiographs obtained in the mesiodistal (MD) and buccolingual (BL) directions. Caries-free permanent mandibular premolars with fully developed apices, no previous endodontic treatment, and without resorption, cracks, fractures, or calcifications, presenting straight, single-rooted canals with an oval cross-sectional morphology, were selected. The teeth were stored in physiological saline solution until use. To determine oval canal morphology, periapical radiographs were taken in the buccolingual (BL) and mesiodistal (MD) directions for each tooth in accordance with a previously described method. Canals with a BL/MD ratio greater than 1.5 at 5 mm coronal to the apex were classified as oval and included in the study ( 35 ). After removal of hard and soft tissue remnants using periodontal instruments, the crowns were sectioned using a carborundum disc to obtain a standardized root length of 16 mm measured from the apical apex, and access cavities were prepared with a diamond round bur. The working length was determined by inserting a size 15 K-type file into the canal until its tip was visible at the apical foramen and subtracting 1 mm from this measurement. Root canal preparation was performed by a single operator using a conventional Ni-Ti rotary system, ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), in accordance with the manufacturer’s instructions, with the final apical file size set to F4. Instrumentation was carried out using an X-Smart Plus endodontic motor (Dentsply Maillefer) in auto-reverse mode. Irrigation and recapitulation were performed after the use of each instrument, and each file was used in a maximum of three canals. Between instrument changes, the canals were irrigated with 2 mL of 2.5% NaOCl. For the final irrigation protocol, 2 mL of 17% EDTA was applied for 1 minute, followed by 2 mL of distilled water. After drying the canals with paper points, obturation was performed using the cold lateral compaction technique with gutta-percha cones (Dentsply, Brazil) and AH Plus root canal sealer (DeTrey Dentsply, Germany). The access cavities were sealed with a temporary restorative material (Cavit, 3M ESPE), and the specimens were stored at 37°C and 100% humidity for 1 month to allow complete sealer polymerization. Following obturation, the specimens were scanned to determine the volume of the root canal filling material using a SkyScan 1272 micro-computed tomography (micro-CT) device (Bruker, Kontich, Belgium). During scanning, a 0.11-mm copper filter was used, and the parameters were set to 90 kV energy, 180° rotation, 0.6° rotation step, 7200 ms exposure time, and a pixel size of 8 µm. Each scan lasted approximately 40 minutes, and the raw images were saved in TIFF format (Fig. 2 ). According to the power analysis, a minimum of 9 specimens per subgroup was required to achieve 85% statistical power; therefore, 10 specimens were included in each group to ensure reliability. The samples were randomly assigned into two groups: ProTaper Universal Retreatment + XP-Endo Finisher and ProTaper Universal Retreatment + Gentlefile Brush. In both groups, the initial phase of root canal filling removal was performed using the ProTaper Universal Retreatment (PTUR) system with D1–D3 files at a torque of 3 Ncm and a speed of 500 rpm. The procedure was conducted with continuous irrigation and recapitulation and was terminated upon reaching the working length, after which the canals were irrigated with 5 mL of 2.5% NaOCl. In Group 1, following PTUR instrumentation, the XP-Endo Finisher was used to remove the remaining filling material according to the manufacturer’s instructions with the X-Smart Plus motor. The roots were maintained at 37°C, and the file was activated using gentle in-and-out movements until no visible filling remnants remained. During this procedure, irrigation was performed with 5 mL of 2.5% NaOCl, followed by a final rinse with 2 mL of 2.5% NaOCl. In Group 2, following PTUR instrumentation, the Gentlefile Brush was mounted on the Gentlefile handpiece and applied at the working length using gentle in-and-out motions in accordance with the manufacturer’s instructions to remove the remaining root canal filling material. During the procedure, irrigation was performed with 5 mL of 2.5% NaOCl, followed by a final rinse with 2 mL of 2.5% NaOCl. After the additional instrumentation procedures, all specimens in both groups were rescanned using micro-computed tomography under the same scanning parameters as the initial scan to determine the amount of residual filling material within the root canals. The raw images obtained from the second scan were also saved in TIFF format. Micro-CT data were reconstructed using NRecon software. Volumetric analyses and three-dimensional models were generated with CTAn, and image alignment was performed using CTVol and DataViewer. The percentage of residual root canal filling material was calculated by dividing the filling volume obtained from the second scan by that from the initial scan (Fig. 3 ). Statistical Analysis Prior to statistical analysis, the dataset was examined for data entry errors and distributional characteristics. Normality was assessed using skewness–kurtosis coefficients, the Shapiro–Wilk test, and histogram evaluations. As the variables did not exhibit a normal distribution, intergroup comparisons were performed using the Mann–Whitney U test, while pre- and post-procedural comparisons within groups were conducted using the Wilcoxon signed-rank test. Data were recorded in Microsoft Excel, analyzed using IBM SPSS Statistics version 23 (IBM Corp., Armonk, NY, USA), and the level of statistical significance was set at p < 0.05. Results In the present study, a total of 20 teeth were evaluated, with 10 specimens in each group. The initial root canal filling volumes, post-procedural residual filling volumes, and percentages of residual filling material for the PTUR + XP-Endo Finisher (XP-EF) and PTUR + Gentlefile Brush (GFB) groups are presented in Table 1 . Table 1 Initial and remaining filling volumes and residual filling percentages in the PTUR + XP-Endo Finisher and PTUR + Gentlefile Brush groups. Examples Group Initial Fill Volume (mm3) Remaining Fill Volume (mm3) Remaining Filler Percentage (%) A1 PTUR + XP-EF 16,22 0,32 1,99 A2 PTUR + XP-EF 20,09 1,37 6,81 A3 PTUR + XP-EF 16,69 0,15 0,91 A4 PTUR + XP-EF 19,81 1,15 5,80 A5 PTUR + XP-EF 18,05 0,80 4,45 A6 PTUR + XP-EF 16,61 0,14 0,81 A7 PTUR + XP-EF 17,13 1,17 6,85 A8 PTUR + XP-EF 15,65 0,75 4,76 A9 PTUR + XP-EF 16,86 0,67 3,96 A10 PTUR + XP-EF 16,67 0,69 4,15 A11 PTUR + GFB 14,67 1,36 9,28 A12 PTUR + GFB 24,69 3,54 14,34 A13 PTUR + GFB 19,32 4,54 23,49 A14 PTUR + GFB 13,20 0,96 7,27 A15 PTUR + GFB 13,52 1,06 7,81 A16 PTUR + GFB 20,95 4,14 19,74 A17 PTUR + GFB 16,56 2,81 17,00 A18 PTUR + GFB 17,29 2,20 12,73 A19 PTUR + GFB 19,26 1,23 6,40 A20 PTUR + GFB 20,64 1,09 5,28 In the PTUR + XP-EF group, pre- and post-procedural filling volumes were compared using the Wilcoxon signed-rank test. The initial filling volumes (median = 16.78) were found to be significantly higher than the residual filling volumes after the procedure (median = 0.72) (z = − 2.803, p = 0.005), indicating a substantial reduction in filling material following retreatment. Detailed results are provided in Table 2 . Table 2 Results of the Wilcoxon signed-rank test comparing pre- and post-procedural volume values in the first group. n Mean SD Med. Min. Max. z p 1. group (PTUR + XP-EF) Fill Volume 10 17,38 1,49 16,78 15,65 20,09 - - Remaining Substance Volume 10 0,72 0,43 0,72 0,14 1,37 -2,803 0,005 SD = standard deviation; Min = minimum; Max = maximum; Med = median. Similarly, in the PTUR + GFB group, comparison of pre- and post-procedural filling volumes using the Wilcoxon signed-rank test revealed that the initial filling volumes (median = 18.27) were significantly greater than the post-procedural residual volumes (median = 1.78) (z = − 2.803, p = 0.005). This finding also demonstrates a marked reduction in filling material after the procedure, with detailed data shown in Table 3 . Table 3 Results of the Wilcoxon signed-rank test comparing pre- and post-procedural volume values in the second group. n Mean SD Med. Min. Max. z p 2. group (PTUR + GFB) Fill Volume 10 18,01 3,66 18,27 13,20 24,69 - 0,005 Remaining Substance Volume 10 2,29 1,38 1,78 0,96 4,54 -2,803 - SD = standard deviation; Min = minimum; Max = maximum; Med = median. As shown in Table 4 , the percentage volumetric changes of the specimens in the PTUR + XP-Endo Finisher and PTUR + Gentlefile Brush groups were compared using the Mann–Whitney U test. The analysis revealed that the percentage change in the PTUR + XP-EF group (median = − 95.70) was significantly greater than that observed in the PTUR + GFB group (median = − 88.99) (z = − 3.402, p = 0.001). Table 4 Results of the Mann–Whitney U test comparing volumetric percentage changes between the groups. n Mean SD Med. Min. Max. MR z p Volume % change PTUR + XP- EF 10 -95,95 2,21 -95,70 -93,15 -99,19 6,00 -3,402 0,001 PTUR + GFB 10 -87,67 6,20 -88,99 -76,52 -94,72 15,00 - Total 20 -91,81 6,21 93,40 -76,52 -99,19 - - SD = standard deviation; Min = minimum; Max = maximum ; MR = mean rank; Med.=median. In addition, the changes in the percentage of residual filling material between the PTUR + XP-EF and PTUR + GFB groups were compared using the Mann–Whitney U test. The results demonstrated that the change in the residual filling percentage in the PTUR + XP-EF group (median = 4.30) was statistically significantly lower than that in the PTUR + GFB group (median = 11.01) (z = − 3.402, p = 0.001) (Table 5 ). Table 5 Results of the Mann–Whitney U test comparing residual filling percentages between the groups. n Mean SD Med. Min. Max. MR z p Remaining filler percentage PTUR + XP EF 10 4,05 2,21 4,30 - - 6,00 -3,402 0,001 PTUR + GFB 10 12,33 6,20 11,01 5,28 23,49 15,00 - - Total 20 8,19 6,21 6,60 0,81 23,49 - SD = standard deviation; Min = minimum; Max = maximum; MR = mean rank; Med.=median. Discussion The primary objectives of successful endodontic retreatment include the removal of the existing root canal filling material, re-shaping and disinfection of the canal system, and subsequent obturation with an adequate seal ( 36 ). However, complete elimination of gutta-percha from the root canal remains a significant challenge, and residual filling material may adversely affect treatment outcomes by reducing the effectiveness of endodontic instruments, irrigating solutions, and intracanal medicaments. Therefore, efficient removal of root canal filling materials represents a critical step in retreatment procedures ( 37 ). Although numerous techniques have been described for the removal of root canal filling materials, it has been reported that none of the currently available methods can achieve complete elimination of the filling material ( 11 , 38 ). In recent years, supplementary rotary instrumentation systems designed to better adapt to root canal anatomy have been introduced; however, evidence regarding their effectiveness, particularly in oval-shaped canals, remains limited ( 39 ). In this context, the present study comparatively evaluated the efficacy of Gentlefile Brush (GFB) and XP-Endo Finisher systems as adjuncts to ProTaper Universal Retreatment (PTUR) in removing root canal filling materials from oval canals using micro-computed tomography (micro-CT). Following the removal of root canal filling materials, various methods have been used to evaluate the residual material on canal walls, including tooth clearing techniques ( 40 ), sectioning methods ( 41 ), radiographic assessment ( 42 ), and scanning electron microscopy ( 43 ). However, these techniques present important limitations, as they may cause irreversible loss of tooth structure and do not allow for three-dimensional evaluation or quantitative analysis ( 44 ). Consequently, advanced imaging modalities such as computed tomography (CT) ( 45 ), cone-beam computed tomography (CBCT) ( 46 ), and micro-computed tomography (micro-CT) ( 34 ) have increasingly been preferred. Among these, micro-CT has emerged as a particularly advantageous method due to its ability to provide high-resolution three-dimensional imaging without compromising specimen integrity and to enable volumetric quantitative assessment of residual filling material throughout the entire root canal system. Moreover, despite the limited applicability of conventional CT in endodontics ( 45 ), the smaller voxel sizes and superior resolution of micro-CT allow for detailed evaluation of the root canal system, representing a significant methodological advantage ( 47 ). In root canal research, artificial acrylic blocks and extracted human teeth are commonly used as experimental models. Although artificial models offer a high degree of standardization ( 48 ), they are limited by their inability to accurately replicate clinical conditions ( 49 ) and by their lower microhardness compared with dentin ( 50 ). In contrast, extracted human teeth, despite inherent morphological variability, better represent clinical reality ( 48 ). Therefore, in line with previous in vitro studies, extracted human teeth were preferred in the present study ( 29 ). In addition, oval-shaped root canals, which represent a more challenging anatomy due to the increased difficulty in removing filling materials, were selected to better reflect clinically demanding conditions. Gu et al. reported that the ProTaper Universal Retreatment (PTUR) system removed root canal filling material more effectively and in a shorter time compared with stainless steel K- and H-type hand files, a finding attributed to the system’s three-step design consisting of D1–D3 files with varying tapers and lengths ( 40 ). Similarly, Giuliani et al. demonstrated that PTUR was more effective than the ProFile rotary system and K-type hand instruments in removing filling materials, and this superiority was associated with the cross-sectional design of the files ( 51 ). Although chemical solvents facilitate the removal of gutta-percha, they may increase the amount of residual filling material on the dentin surface and within dentinal tubules. Horvath et al. reported that eucalyptol and chloroform form a film layer on dentin that is difficult to remove ( 52 ). In contrast, previous studies have demonstrated that the friction generated by rotary instruments sufficiently softens gutta-percha; therefore, no solvent was used in the present study ( 24 ). The adjunctive use of the XP-Endo Finisher (XP-EF) has been reported to enhance both the removal of root canal filling materials and canal disinfection ( 25 ). Micro-CT studies conducted in oval and curved canals have shown that the additional use of XP-EF significantly reduces residual filling material and bacterial load within the canal system ( 25 , 53 ). This effectiveness has been attributed to the file’s ability to undergo shape transformation at body temperature, thereby increasing its contact area with the canal walls, as well as to its elliptical motion, which enables more effective action in hard-to-reach areas of the canal system ( 25 , 54 ). The Gentlefile Brush (GFB) is an adjunctive system that, when operated at high speed, expands into a brush-like configuration through centrifugal force, facilitating the removal of debris and biofilm from the canal walls while effectively activating the irrigating solution ( 29 ). Studies conducted in oval-shaped canals have reported that GFB significantly reduces residual material on canal walls compared with conventional irrigation methods ( 29 ). Furthermore, micro-CT analyses have demonstrated that GFB is particularly effective in removing residual filling material from the apical third of the canal when compared with other techniques ( 39 ). Conclusions Within the limitations of this study, both PTUR + XP-Endo Finisher (XP-EF) and PTUR + Gentlefile Brush (GFB) systems were found to be effective in removing root canal filling material; however, neither technique was able to completely eliminate the filling material. The XP-Endo Finisher demonstrated statistically superior performance compared with Gentlefile Brush in reducing the amount of residual filling material within the canal system. Micro-computed tomography (micro-CT) proved to be a reliable method due to its ability to provide high-resolution, three-dimensional quantitative analysis; however, its cost and time requirements may limit the number of specimens that can be included in experimental studies. The findings of the present study indicate a continued need for the development of more effective instrumentation strategies for endodontic retreatment procedures. These findings may assist clinicians in selecting supplementary instrumentation strategies to enhance cleaning efficacy in oval-shaped root canals during nonsurgical retreatment. Abbreviations BL Buccolingual CBCT Cone-beam computed tomography CT Computed tomography EDTA Ethylenediaminetetraacetic acid GFB Gentlefile Brush MD Mesiodistal micro-CT (µCT) Micro–computed tomography NaOCl Sodium hypochlorite Ni–Ti Nickel–titanium PTUR ProTaper Universal Retreatment ROI Region of interest SAF Self-Adjusting File XP-EF XP-Endo Finisher Declarations Ethical Approval and Participation Permission This study was approved by the Non-Interventional Clinical Research Ethics Committee of Firat University (Approval Date: March 4, 2020; Approval No: 382607). The extracted teeth used in this study were obtained from patients for clinical reasons, and prior to extraction, the patients were informed that their teeth could be used for scientific research purposes. Written informed consent was obtained from all participants. All procedures were performed in accordance with the relevant national regulations and the principles of the Declaration of Helsinki. Publication Permission Not applicable. Accessibility of Data and Materials The datasets used and/or analyzed in this study are available from the relevant author upon reasonable request. Conflict of Interest The authors declare that there is no conflict of interest. Funding This research was supported by the Firat University Scientific Research Projects unit. Authors' Contributions FO and EK designed and planned the study. FO performed the experimental procedures. FO performed the micro-CT analysis. EK performed the statistical analysis. FO and EK prepared the draft text. All authors have read and approved the final text. Acknowledgements The authors thank the Department of Endodontics, Faculty of Dentistry, Firat University, and the Research Laboratory, Faculty of Dentistry, Erciyes University, for providing the infrastructure used in this study. References Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 2—Tooth survival. Int Endod J. 2011;44(7):610–625. Ruddle CJ. Nonsurgical endodontic retreatment. CDA J. 2004;32:474–484. Seltzer S, Bender I, Smith J, Freedman I, Nazimov H. Endodontic failures—An analysis based on clinical, roentgenographic, and histologic findings. Part II. Oral Surg Oral Med Oral Pathol. 1967;23(4):517–530. Ruddle CJ. Micro-endodontic nonsurgical retreatment. Dent Clin North Am. 1997;41(3):429–454. Strindberg LZ. The dependence of the results of pulp therapy on certain factors: an analytical study based on radiographic and clinical follow-up examinations. Acta Odontol Scand. 1956;14:1–175. Saunders WP, Saunders EM. Coronal leakage as a cause of failure in root canal therapy: a review. Dent Traumatol. 1994;10(3):105–108. Lantz B, Persson P. Periodontal tissue reactions after root perforations in dog’s teeth: a histologic study. Odontol Tidskr. 1967;75(3):209–214. Walton RE, Michelich RJ, Smith GN. The histopathogenesis of vertical root fractures. J Endod. 1984;10(2):48–56. Lin LM, Skribner JE, Gaengler P. Factors associated with endodontic treatment failures. J Endod. 1992;18(12):625–627. Ng YL, Mann V, Gulabivala K. Outcome of secondary root canal treatment: a systematic review of the literature. Int Endod J. 2008;41(12):1026–1046. Hülsmann M, Stotz S. Efficacy, cleaning ability and safety of different devices for gutta-percha removal in root canal retreatment. Int Endod J. 1997;30(4):227–233. Schirrmeister JF. Revision of root canal fillings using engine-driven nickel–titanium instruments: a literature review. Endodontie. 2006;15:20–27. Kosti E, Lambrianidis T, Economides N, Neofitou C. Ex vivo study of the efficacy of H-files and rotary NiTi instruments to remove gutta-percha and four types of sealer. Int Endod J. 2006;39(1):48–54. Ricucci D, Siqueira JF Jr, Bate AL, Ford TRP. Histologic investigation of root canal–treated teeth with apical periodontitis: a retrospective study from twenty-four patients. J Endod. 2009;35(4):493–502. Taha NA, Ozawa T, Messer HH. Comparison of three techniques for preparing oval-shaped root canals. J Endod. 2010;36(3):532–535. Paqué F, Peters OA. Micro–computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file. J Endod. 2011;37(4):517–521. Ferreira JJ, Rhodes JS, Pitt Ford TR. The efficacy of gutta-percha removal using ProFiles. Int Endod J. 2001;34(4):267–274. Venturi M, Prati C, Capelli G, Falconi M, Breschi L. A preliminary analysis of the morphology of lateral canals after root canal filling using a tooth-clearing technique. Int Endod J. 2003;36:54–63. Hülsmann M, Bluhm V. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J. 2004;37(7):468–476. Roggendorf MJ, Legner M, Ebert J, Fillery E, Frankenberger R, Friedman S. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. Int Endod J. 2010;43(3):200–209. Şahin FÜ, Topuz Ö. Applications of micro-computed tomography in dental research. Acta Odontol Turc. 2014;31(2):114–120. Jung M, Lommel D, Klimek J. The imaging of root canal obturation using micro-CT. Int Endod J. 2005;38(9):617–626. Vaudt J, Bitter K, Neumann K, Kielbassa AM. Ex vivo study on root canal instrumentation of two rotary nickel–titanium systems compared with stainless steel hand instruments. Int Endod J. 2009;42(1):22–33. Takahashi CM, Cunha RS, De Martin AS, Fontana CE, Silveira CFM, Bueno CES. In vitro evaluation of the effectiveness of ProTaper Universal rotary retreatment system for gutta-percha removal with or without solvent. J Endod. 2009;35(11):1580–1583. Alves FRF, Marceliano-Alves MF, Sousa JCN, Silveira SB, Provenzano JC, Siqueira JF Jr. Removal of root canal fillings in curved canals using reciprocating or rotary systems with a supplementary XP-Endo Finisher step. J Endod. 2016;42(7):1114–1119. Chen JE, Nurbakhsh B, Layton G, Bussmann M, Kishen A. Irrigation dynamics associated with positive pressure, apical negative pressure, and passive ultrasonic irrigation: a computational fluid dynamics analysis. Aust Endod J. 2014;40(2):54–60. Plotino G, Cortese T, Grande NM, Leonardi DP, Di Giorgio G, Testarelli L, et al. New technologies to improve root canal disinfection. Braz Dent J. 2016;27(1):3–8. Busquim S, Cunha RS, Freire LG, Gavini G, Machado MEL, Santos M. Micro-CT evaluation of long oval canal preparation using reciprocating or rotary systems. Int Endod J. 2015;48(10):1001–1006. Neelakantan P, Khan K, Li KY, Shetty H, Xi W. Effectiveness of supplementary irrigant agitation with the Finisher GF Brush in oval root canals. Int Endod J. 2018;51(7):800–807. Elliott JC, Dover SD. X-ray microtomography. J Microsc. 1982;126(2):211–213. Rhodes JS, Ford TRP, Lynch JA, Liepins PJ, Curtis RV. Micro-computed tomography: a new tool for experimental endodontology. Int Endod J. 1999;32(3):165–170. Dyck V. Desktop X-ray microscopy and microtomography. J Microsc. 1998;191(2):151–158. Başer Can E, Keleş A, Aslan B. Micro-CT evaluation of the quality of root fillings using three obturation systems. Int Endod J. 2017;50(5):499–505. Crozeta BM, Silva-Sousa YTC, Leoni GB, Mazzi-Chaves JF, Fantinato T, Baratto-Filho F, et al. Micro-CT study of filling material removal from oval-shaped canals using rotary, reciprocating, and adaptive systems. J Endod. 2016;42(5):793–797. Wu MK, Kašt’áková A, Wesselink PR. Quality of cold and warm gutta-percha fillings in oval canals of mandibular premolars. Int Endod J. 2001;34(6):485–491. Ricucci D, Siqueira JF Jr. Biofilms and apical periodontitis: prevalence and association with clinical and histopathologic findings. J Endod. 2010;36(8):1277–1288. Silva EJNL, Orlowsky NB, Herrera DR, Machado R, Krebs RL, Coutinho-Filho TDS. Effectiveness of rotary and reciprocating movements in root canal filling removal. Braz Oral Res. 2015;29(1):1–6. Rossi-Fedele G, Ahmed HMA. Assessment of root canal filling removal using micro-CT: a systematic review. J Endod. 2017;43(4):520–526. Nguyen TA, Kim Y, Kim E, Shin SJ, Kim S. Comparison of techniques for root canal filling removal in artificial teeth: a micro-CT study. J Clin Med. 2019;8(7):984. Gu LS, Ling JQ, Wei X, Huang XY. Efficacy of ProTaper Universal retreatment system for gutta-percha removal. Int Endod J. 2008;41(4):288–295. Sae-Lim V, Lim BK, Lee HL. Effectiveness of ProFile .04 taper rotary instruments in retreatment. J Endod. 2000;26(2):100–104. Gergi R, Sabbagh C. Effectiveness of two NiTi rotary instruments and hand files in severely curved canals. Int Endod J. 2007;40(7):532–537. Keleş A, Şimşek N, Alcin H, Ahmetoglu F, Yologlu S. Retreatment of flat-oval canals with a self-adjusting file: an SEM study. Dent Mater J. 2014;33(6):786–791. Hammad M, Qualtrough A, Silikas N. Three-dimensional evaluation of retreatment techniques. J Endod. 2008;34(11):1370–1373. Tachibana H, Matsumoto K. Applicability of X-ray CT in endodontics. Dent Traumatol. 1990;6(1):16–20. Michetti J, Maret D, Mallet JP, Diemer F. Validation of CBCT for root canal anatomy assessment. J Endod. 2010;36(7):1187–1190. Plotino G, Grande NM, Pecci R, Bedini R, Pameijer CH, Somma F. Three-dimensional imaging using micro-CT for tooth morphology. J Am Dent Assoc. 2006;137(11):1555–1561. Hülsmann M, Peters OA, Dummer PMH. Mechanical preparation of root canals. Endod Topics. 2005;10(1):30–76. Campos JM, del Rio C. Comparison of mechanical and hand instrumentation techniques. J Endod. 1990;16(5):230–234. Craig RG, Gehring PE, Peyton FA. Relation of structure to microhardness of human dentin. J Dent Res. 1959;38(3):624–630. Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper Universal retreatment files. J Endod. 2008;34(11):1381–1384. Horvath S, Altenburger MJ, Naumann M, Wolkewitz M, Schirrmeister JF. Cleanliness of dentinal tubules after gutta-percha removal with and without solvents. Int Endod J. 2009;42(11):1032–1038. Carvalho MC, Zuolo ML, Arruda-Vasconcelos R, Marinho ACS, Louzada LM, Francisco PA, et al. Effectiveness of XP-Endo Finisher in reducing bacterial load in oval canals. Braz Oral Res. 2019;33:e021. Karamifar K, Mehrasa N, Pardis P, Saghiri MA. Canal wall cleanliness after gutta-percha removal: an in vitro analysis. Iran Endod J. 2017;12(2):242–246. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 15 Feb, 2026 Reviewers agreed at journal 13 Feb, 2026 Reviewers invited by journal 13 Feb, 2026 Editor assigned by journal 06 Jan, 2026 Editor invited by journal 26 Dec, 2025 Submission checks completed at journal 25 Dec, 2025 First submitted to journal 25 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8434085","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":591729539,"identity":"6cc1958a-461d-4597-9d33-5fccb06bc0f2","order_by":0,"name":"Erdi KARATAŞ","email":"","orcid":"","institution":"Fırat University","correspondingAuthor":false,"prefix":"","firstName":"Erdi","middleName":"","lastName":"KARATAŞ","suffix":""},{"id":591729549,"identity":"a0b42649-2ee1-422d-b0d9-316f5f9c3789","order_by":1,"name":"Faruk ÖZTEKİN","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYBAC9gYQeUCCgZ/5YANE6AABLTwHGBgbQFok2xKBWhLAWhgbiNDCwGBwDKScKC3s7c8ffDhjkWd8jLntw88fDHJ8NxLYH1fg08JzILFxxg2JYrNjjM0zexIYjCVvJDA2nsGjxV4i4WAzzweJxG33G5sZeBIYEjeAtOBzGY9EYmPzH6CWzW2MzYx/EhjqidCSzNjMcEMicQMbYzMz0JYEA4JaeI4xzuw5I5E4A+gXZpk0CcOZZx42zsSrhb39wYcfx+oS+9vYHzO+sbGR5zuefOAjPi3oQAKI8UfLKBgFo2AUjAIiAABwvVSaD+qKBQAAAABJRU5ErkJggg==","orcid":"","institution":"Fırat University","correspondingAuthor":true,"prefix":"","firstName":"Faruk","middleName":"","lastName":"ÖZTEKİN","suffix":""}],"badges":[],"createdAt":"2025-12-23 13:08:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8434085/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8434085/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103050109,"identity":"2f2fdd6a-0795-435b-8547-9b0c63e563e2","added_by":"auto","created_at":"2026-02-20 07:48:17","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":47804,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003eMorphological appearance of the XP-Endo Finisher file. \u003cstrong\u003e(B)\u003c/strong\u003e Morphological appearance of the Gentlefile Brush system file.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8434085/v1/ca49c5dfd871f8b99355599a.jpg"},{"id":103049998,"identity":"2a42a78c-aaa5-46b2-9094-05c210c1b539","added_by":"auto","created_at":"2026-02-20 07:47:36","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":25433,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative dimensional (left) and cross-sectional (right) images obtained after micro–computed tomography (micro-CT) scanning.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8434085/v1/446f957eeaa5f6207ffb30f6.jpg"},{"id":103049855,"identity":"3aa87c11-3b9a-484e-8d17-18a5d4ed49fb","added_by":"auto","created_at":"2026-02-20 07:46:52","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":16161,"visible":true,"origin":"","legend":"\u003cp\u003eThree-dimensional micro–computed tomography (micro-CT) images of representative specimens. \u003cstrong\u003e(A)\u003c/strong\u003eFirst group after root canal obturation and PTUR + XP-Endo Finisher–assisted retreatment. \u003cstrong\u003e(B)\u003c/strong\u003e Second group after root canal obturation and PTUR + Gentlefile Brush–assisted retreatment.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8434085/v1/bc623cad3cac3f4a3febc868.jpg"},{"id":103051307,"identity":"626e8067-aa8a-4b0e-b4bd-19ebe105e901","added_by":"auto","created_at":"2026-02-20 07:59:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":925423,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8434085/v1/f0dd155c-3687-483d-ad9c-3d182f7e5fa3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe primary objective of endodontic treatment is the elimination of microbial content from the root canal system, biomechanical shaping of the canal, and obturation of the prepared space with a hermetic filling material. Contemporary root canal treatment is considered a reliable therapeutic approach, with reported success rates exceeding 90% (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Nevertheless, treatment failure may still occur in certain clinical situations (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Residual necrotic pulp tissue (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e), inadequate or overextended root canal fillings (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e), the presence of fractured instruments within the canal (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), coronal leakage (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e), mechanical perforations (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e), root fractures (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e), persistence of periradicular lesions (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), and periodontal diseases (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e) are among the principal factors adversely affecting treatment outcomes.\u003c/p\u003e \u003cp\u003eIn cases of failure, the main treatment options aimed at retaining the tooth in the oral cavity include surgical endodontic procedures and nonsurgical root canal retreatment. Owing to its conservative nature, nonsurgical retreatment is preferred as the first-line approach in most cases. Both treatment modalities have been reported to demonstrate high short-term success rates (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). During retreatment procedures, various techniques are employed for the removal of root canal filling materials, including mechanical systems, ultrasonic devices, heat carriers, solvents, and laser-based methods (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). In recent years, nickel\u0026ndash;titanium (Ni\u0026ndash;Ti) rotary file systems used with torque-controlled motors have enabled more effective removal of filling materials from the root canal system (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Several Ni\u0026ndash;Ti retreatment systems, such as ProTaper Universal Retreatment, DRace, Mtwo, R-Endo, Reciproc, and OneShape, are currently available for clinical use.\u003c/p\u003e \u003cp\u003eHowever, none of the currently available techniques is capable of completely eliminating root canal filling material (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Residual filling material adhering to the canal walls should be removed, as it may harbor bacteria and adversely affect the sealing ability of the obturation (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). The circular preparation motion of Ni\u0026ndash;Ti rotary instruments may leave extensive dentin surfaces uninstrumented, particularly in oval-shaped root canals (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Previous studies have reported that, due to the complex morphology of oval canals, cleaning and shaping procedures are more challenging and a substantial portion of the dentinal walls does not come into adequate contact with the instruments (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eVarious methods have been employed to evaluate the amount of residual filling material following retreatment, including radiographic assessment (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e), clearing techniques (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e), examination of root sections (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e), and micro\u0026ndash;computed tomography (micro-CT) analysis (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Micro\u0026ndash;computed tomography is a reliable, nondestructive method that provides both qualitative and quantitative data, allowing volumetric comparison of root canal morphology before and after instrumentation without causing structural damage to the specimens (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). In this context, the aim of the present study was to compare, using micro-CT, two different supplementary instrumentation systems designed to reduce the amount of residual filling material in oval-shaped root canals following retreatment.\u003c/p\u003e \u003cp\u003eThe ProTaper Universal system is a Ni\u0026ndash;Ti rotary file system with a variable taper design, consisting of three shaping files (SX, S1, S2) and three finishing files (F1, F2, F3). Developed from the conventional ProTaper system, it aims to provide efficient canal preparation through increased flexibility and an optimized cross-sectional design (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Its convex triangular cross-section, improved flute geometry, and non-cutting tip design enhance debris removal while allowing safe operation. Modified outer surfaces and a variable helical angle provide high cutting efficiency, while reduced contact with dentin decreases the screwing-in effect (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe ProTaper Universal Retreatment (PTUR) system is a three-step filling removal system composed of D1, D2, and D3 files, which are used for the removal of filling material from the coronal, middle, and apical thirds of the canal, respectively. The D1 file, with an active tip, facilitates easy penetration into the filling material, while the files have taper angles of 9%, 8%, and 7% and tip sizes of 30, 25, and 20, respectively. Their working lengths are 16, 18, and 22 mm, and the convex triangular cross-section ensures effective cutting efficiency. The non-cutting tip design of the D2 and D3 files reduces the risk of perforation and ledge formation (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe XP-Endo Finisher (FKG Dentaire, Switzerland) is a size 25, non-tapered instrument used during the final stage of root canal cleaning. Owing to its high flexibility, it adapts to the canal morphology and enhances the cleaning of irregular areas. Manufactured from a temperature-responsive Ni\u0026ndash;Ti alloy, the file remains straight in the martensitic phase at room temperature and transforms into the austenitic phase at body temperature, exhibiting an approximate 1.5 mm expansion at its tip (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). When operated in continuous rotation, it provides three-dimensional cleaning in hard-to-reach areas without damaging dentin, while preserving the original canal anatomy.\u003c/p\u003e \u003cp\u003eRoot canal irrigation alone is known to be insufficient in generating adequate hydrodynamic forces to remove biofilms adhering to dentin walls (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e); to overcome this limitation, irrigant activation techniques have been developed (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). The circular preparation pattern of rotary systems may lead to inadequate cleaning, particularly in oval canals, and residual organic debris on the canal walls can promote microbial recontamination (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). Consequently, adaptive systems such as the Self-Adjusting File (SAF) and Gentlefile Brush have been designed to enhance cleaning in complex canal anatomies. The Gentlefile Brush activates the irrigant at high speed, facilitating the removal of residual material, especially in the apical region, while the vortical flow generated by centrifugal forces increases contact between the irrigant and dentin surfaces, optimizing biofilm and debris removal (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e) (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMicro\u0026ndash;computed tomography (micro-CT) is based on principles similar to clinical computed tomography; however, its micrometer-level resolution enables detailed sectional evaluation of small specimens, making it a reliable imaging modality in endodontic research (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA micro-CT system consists of an X-ray source, a motorized rotating stage, an image intensifier, a CCD camera, and an image processing unit (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Compared with clinical CT, specimen rotation and a reduced focal spot size (5\u0026ndash;10 \u0026micro;m) enhance image quality and spatial resolution (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAs a nondestructive three-dimensional imaging technique, micro-CT allows virtual sectioning without compromising specimen integrity and enables comprehensive qualitative and quantitative evaluation of dentin mineral density, root canal filling volume, canal morphology, and residual filling material before and after retreatment procedures (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e).\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis in vitro study was conducted using the shared infrastructure of the Department of Endodontics, Faculty of Dentistry, Fırat University, and the Research Laboratory of the Faculty of Dentistry, Erciyes University. Ethical approval was obtained from the Fırat University Non-Interventional Research Ethics Committee (04 March 2020, No. 382607). A total of 20 mandibular premolar teeth extracted for orthodontic or periodontal reasons were included in the study. Root canal morphology was evaluated using periapical radiographs obtained in the mesiodistal (MD) and buccolingual (BL) directions. Caries-free permanent mandibular premolars with fully developed apices, no previous endodontic treatment, and without resorption, cracks, fractures, or calcifications, presenting straight, single-rooted canals with an oval cross-sectional morphology, were selected. The teeth were stored in physiological saline solution until use.\u003c/p\u003e \u003cp\u003eTo determine oval canal morphology, periapical radiographs were taken in the buccolingual (BL) and mesiodistal (MD) directions for each tooth in accordance with a previously described method. Canals with a BL/MD ratio greater than 1.5 at 5 mm coronal to the apex were classified as oval and included in the study (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). After removal of hard and soft tissue remnants using periodontal instruments, the crowns were sectioned using a carborundum disc to obtain a standardized root length of 16 mm measured from the apical apex, and access cavities were prepared with a diamond round bur. The working length was determined by inserting a size 15 K-type file into the canal until its tip was visible at the apical foramen and subtracting 1 mm from this measurement.\u003c/p\u003e \u003cp\u003eRoot canal preparation was performed by a single operator using a conventional Ni-Ti rotary system, ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), in accordance with the manufacturer\u0026rsquo;s instructions, with the final apical file size set to F4. Instrumentation was carried out using an X-Smart Plus endodontic motor (Dentsply Maillefer) in auto-reverse mode. Irrigation and recapitulation were performed after the use of each instrument, and each file was used in a maximum of three canals. Between instrument changes, the canals were irrigated with 2 mL of 2.5% NaOCl. For the final irrigation protocol, 2 mL of 17% EDTA was applied for 1 minute, followed by 2 mL of distilled water. After drying the canals with paper points, obturation was performed using the cold lateral compaction technique with gutta-percha cones (Dentsply, Brazil) and AH Plus root canal sealer (DeTrey Dentsply, Germany). The access cavities were sealed with a temporary restorative material (Cavit, 3M ESPE), and the specimens were stored at 37\u0026deg;C and 100% humidity for 1 month to allow complete sealer polymerization.\u003c/p\u003e \u003cp\u003eFollowing obturation, the specimens were scanned to determine the volume of the root canal filling material using a SkyScan 1272 micro-computed tomography (micro-CT) device (Bruker, Kontich, Belgium). During scanning, a 0.11-mm copper filter was used, and the parameters were set to 90 kV energy, 180\u0026deg; rotation, 0.6\u0026deg; rotation step, 7200 ms exposure time, and a pixel size of 8 \u0026micro;m. Each scan lasted approximately 40 minutes, and the raw images were saved in TIFF format (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAccording to the power analysis, a minimum of 9 specimens per subgroup was required to achieve 85% statistical power; therefore, 10 specimens were included in each group to ensure reliability. The samples were randomly assigned into two groups: ProTaper Universal Retreatment\u0026thinsp;+\u0026thinsp;XP-Endo Finisher and ProTaper Universal Retreatment\u0026thinsp;+\u0026thinsp;Gentlefile Brush. In both groups, the initial phase of root canal filling removal was performed using the ProTaper Universal Retreatment (PTUR) system with D1\u0026ndash;D3 files at a torque of 3 Ncm and a speed of 500 rpm. The procedure was conducted with continuous irrigation and recapitulation and was terminated upon reaching the working length, after which the canals were irrigated with 5 mL of 2.5% NaOCl.\u003c/p\u003e \u003cp\u003eIn Group 1, following PTUR instrumentation, the XP-Endo Finisher was used to remove the remaining filling material according to the manufacturer\u0026rsquo;s instructions with the X-Smart Plus motor. The roots were maintained at 37\u0026deg;C, and the file was activated using gentle in-and-out movements until no visible filling remnants remained. During this procedure, irrigation was performed with 5 mL of 2.5% NaOCl, followed by a final rinse with 2 mL of 2.5% NaOCl.\u003c/p\u003e \u003cp\u003eIn Group 2, following PTUR instrumentation, the Gentlefile Brush was mounted on the Gentlefile handpiece and applied at the working length using gentle in-and-out motions in accordance with the manufacturer\u0026rsquo;s instructions to remove the remaining root canal filling material. During the procedure, irrigation was performed with 5 mL of 2.5% NaOCl, followed by a final rinse with 2 mL of 2.5% NaOCl.\u003c/p\u003e \u003cp\u003eAfter the additional instrumentation procedures, all specimens in both groups were rescanned using micro-computed tomography under the same scanning parameters as the initial scan to determine the amount of residual filling material within the root canals. The raw images obtained from the second scan were also saved in TIFF format.\u003c/p\u003e \u003cp\u003eMicro-CT data were reconstructed using NRecon software. Volumetric analyses and three-dimensional models were generated with CTAn, and image alignment was performed using CTVol and DataViewer. The percentage of residual root canal filling material was calculated by dividing the filling volume obtained from the second scan by that from the initial scan (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003ePrior to statistical analysis, the dataset was examined for data entry errors and distributional characteristics. Normality was assessed using skewness\u0026ndash;kurtosis coefficients, the Shapiro\u0026ndash;Wilk test, and histogram evaluations. As the variables did not exhibit a normal distribution, intergroup comparisons were performed using the Mann\u0026ndash;Whitney U test, while pre- and post-procedural comparisons within groups were conducted using the Wilcoxon signed-rank test. Data were recorded in Microsoft Excel, analyzed using IBM SPSS Statistics version 23 (IBM Corp., Armonk, NY, USA), and the level of statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eIn the present study, a total of 20 teeth were evaluated, with 10 specimens in each group. The initial root canal filling volumes, post-procedural residual filling volumes, and percentages of residual filling material for the PTUR\u0026thinsp;+\u0026thinsp;XP-Endo Finisher (XP-EF) and PTUR\u0026thinsp;+\u0026thinsp;Gentlefile Brush (GFB) groups are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInitial and remaining filling volumes and residual filling percentages in the PTUR\u0026thinsp;+\u0026thinsp;XP-Endo Finisher and PTUR\u0026thinsp;+\u0026thinsp;Gentlefile Brush groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExamples\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInitial Fill Volume (mm3)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRemaining Fill Volume (mm3)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRemaining Filler Percentage (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1,99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20,09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19,81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5,80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4,45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17,13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e15,65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4,76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3,96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-EF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4,15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9,28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e24,69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3,54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14,34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19,32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4,54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23,49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7,27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13,52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7,81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20,95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19,74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16,56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e17,00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17,29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12,73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19,26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20,64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5,28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the PTUR\u0026thinsp;+\u0026thinsp;XP-EF group, pre- and post-procedural filling volumes were compared using the Wilcoxon signed-rank test. The initial filling volumes (median\u0026thinsp;=\u0026thinsp;16.78) were found to be significantly higher than the residual filling volumes after the procedure (median\u0026thinsp;=\u0026thinsp;0.72) (z = \u0026minus;\u0026thinsp;2.803, p\u0026thinsp;=\u0026thinsp;0.005), indicating a substantial reduction in filling material following retreatment. Detailed results are provided in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of the Wilcoxon signed-rank test comparing pre- and post-procedural volume values in the first group.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMed.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMax.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ez\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e1. group\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(PTUR\u0026thinsp;+\u0026thinsp;XP-EF)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFill Volume\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e17,38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1,49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e16,78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15,65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e20,09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eRemaining Substance Volume\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1,37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-2,803\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0,005\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"10\"\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; Min\u0026thinsp;=\u0026thinsp;minimum; Max\u0026thinsp;=\u0026thinsp;maximum; Med\u0026thinsp;=\u0026thinsp;median.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSimilarly, in the PTUR\u0026thinsp;+\u0026thinsp;GFB group, comparison of pre- and post-procedural filling volumes using the Wilcoxon signed-rank test revealed that the initial filling volumes (median\u0026thinsp;=\u0026thinsp;18.27) were significantly greater than the post-procedural residual volumes (median\u0026thinsp;=\u0026thinsp;1.78) (z = \u0026minus;\u0026thinsp;2.803, p\u0026thinsp;=\u0026thinsp;0.005). This finding also demonstrates a marked reduction in filling material after the procedure, with detailed data shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of the Wilcoxon signed-rank test comparing pre- and post-procedural volume values in the second group.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMed.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMax.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ez\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e2. group\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(PTUR\u0026thinsp;+\u0026thinsp;GFB)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eFill Volume\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e18,01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3,66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e18,27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e24,69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0,005\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eRemaining Substance Volume\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1,38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1,78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0,96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4,54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-2,803\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"10\"\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; Min\u0026thinsp;=\u0026thinsp;minimum; Max\u0026thinsp;=\u0026thinsp;maximum; Med\u0026thinsp;=\u0026thinsp;median.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the percentage volumetric changes of the specimens in the PTUR\u0026thinsp;+\u0026thinsp;XP-Endo Finisher and PTUR\u0026thinsp;+\u0026thinsp;Gentlefile Brush groups were compared using the Mann\u0026ndash;Whitney U test. The analysis revealed that the percentage change in the PTUR\u0026thinsp;+\u0026thinsp;XP-EF group (median = \u0026minus;\u0026thinsp;95.70) was significantly greater than that observed in the PTUR\u0026thinsp;+\u0026thinsp;GFB group (median = \u0026minus;\u0026thinsp;88.99) (z = \u0026minus;\u0026thinsp;3.402, p\u0026thinsp;=\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of the Mann\u0026ndash;Whitney U test comparing volumetric percentage changes between the groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMed.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMax.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eMR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ez\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eVolume\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e%\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003echange\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePTUR\u0026thinsp;+\u0026thinsp;XP-\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eEF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-95,95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-95,70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-93,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-99,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e6,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-3,402\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0,001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-87,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-88,99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-76,52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-94,72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-91,81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e93,40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-76,52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-99,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; Min\u0026thinsp;=\u0026thinsp;minimum; Max\u0026thinsp;=\u0026thinsp;maximum ; MR\u0026thinsp;=\u0026thinsp;mean rank; Med.=median.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn addition, the changes in the percentage of residual filling material between the PTUR\u0026thinsp;+\u0026thinsp;XP-EF and PTUR\u0026thinsp;+\u0026thinsp;GFB groups were compared using the Mann\u0026ndash;Whitney U test. The results demonstrated that the change in the residual filling percentage in the PTUR\u0026thinsp;+\u0026thinsp;XP-EF group (median\u0026thinsp;=\u0026thinsp;4.30) was statistically significantly lower than that in the PTUR\u0026thinsp;+\u0026thinsp;GFB group (median\u0026thinsp;=\u0026thinsp;11.01) (z = \u0026minus;\u0026thinsp;3.402, p\u0026thinsp;=\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of the Mann\u0026ndash;Whitney U test comparing residual filling percentages between the groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMed.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMax.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eMR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ez\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eRemaining\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003efiller\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003epercentage\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePTUR\u0026thinsp;+\u0026thinsp;XP EF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4,30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e6,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-3,402\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0,001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePTUR\u0026thinsp;+\u0026thinsp;GFB\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12,33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e11,01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5,28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23,49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6,60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0,81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23,49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; Min\u0026thinsp;=\u0026thinsp;minimum; Max\u0026thinsp;=\u0026thinsp;maximum; MR\u0026thinsp;=\u0026thinsp;mean rank; Med.=median.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe primary objectives of successful endodontic retreatment include the removal of the existing root canal filling material, re-shaping and disinfection of the canal system, and subsequent obturation with an adequate seal (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). However, complete elimination of gutta-percha from the root canal remains a significant challenge, and residual filling material may adversely affect treatment outcomes by reducing the effectiveness of endodontic instruments, irrigating solutions, and intracanal medicaments. Therefore, efficient removal of root canal filling materials represents a critical step in retreatment procedures (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAlthough numerous techniques have been described for the removal of root canal filling materials, it has been reported that none of the currently available methods can achieve complete elimination of the filling material (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). In recent years, supplementary rotary instrumentation systems designed to better adapt to root canal anatomy have been introduced; however, evidence regarding their effectiveness, particularly in oval-shaped canals, remains limited (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). In this context, the present study comparatively evaluated the efficacy of Gentlefile Brush (GFB) and XP-Endo Finisher systems as adjuncts to ProTaper Universal Retreatment (PTUR) in removing root canal filling materials from oval canals using micro-computed tomography (micro-CT).\u003c/p\u003e \u003cp\u003eFollowing the removal of root canal filling materials, various methods have been used to evaluate the residual material on canal walls, including tooth clearing techniques (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e), sectioning methods (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e), radiographic assessment (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e), and scanning electron microscopy (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e). However, these techniques present important limitations, as they may cause irreversible loss of tooth structure and do not allow for three-dimensional evaluation or quantitative analysis (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). Consequently, advanced imaging modalities such as computed tomography (CT) (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e), cone-beam computed tomography (CBCT) (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e), and micro-computed tomography (micro-CT) (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) have increasingly been preferred. Among these, micro-CT has emerged as a particularly advantageous method due to its ability to provide high-resolution three-dimensional imaging without compromising specimen integrity and to enable volumetric quantitative assessment of residual filling material throughout the entire root canal system. Moreover, despite the limited applicability of conventional CT in endodontics (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e), the smaller voxel sizes and superior resolution of micro-CT allow for detailed evaluation of the root canal system, representing a significant methodological advantage (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn root canal research, artificial acrylic blocks and extracted human teeth are commonly used as experimental models. Although artificial models offer a high degree of standardization (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e), they are limited by their inability to accurately replicate clinical conditions (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e) and by their lower microhardness compared with dentin (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). In contrast, extracted human teeth, despite inherent morphological variability, better represent clinical reality (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e). Therefore, in line with previous in vitro studies, extracted human teeth were preferred in the present study (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). In addition, oval-shaped root canals, which represent a more challenging anatomy due to the increased difficulty in removing filling materials, were selected to better reflect clinically demanding conditions.\u003c/p\u003e \u003cp\u003eGu et al. reported that the ProTaper Universal Retreatment (PTUR) system removed root canal filling material more effectively and in a shorter time compared with stainless steel K- and H-type hand files, a finding attributed to the system\u0026rsquo;s three-step design consisting of D1\u0026ndash;D3 files with varying tapers and lengths (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). Similarly, Giuliani et al. demonstrated that PTUR was more effective than the ProFile rotary system and K-type hand instruments in removing filling materials, and this superiority was associated with the cross-sectional design of the files (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAlthough chemical solvents facilitate the removal of gutta-percha, they may increase the amount of residual filling material on the dentin surface and within dentinal tubules. Horvath et al. reported that eucalyptol and chloroform form a film layer on dentin that is difficult to remove (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e). In contrast, previous studies have demonstrated that the friction generated by rotary instruments sufficiently softens gutta-percha; therefore, no solvent was used in the present study (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe adjunctive use of the XP-Endo Finisher (XP-EF) has been reported to enhance both the removal of root canal filling materials and canal disinfection (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). Micro-CT studies conducted in oval and curved canals have shown that the additional use of XP-EF significantly reduces residual filling material and bacterial load within the canal system (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). This effectiveness has been attributed to the file\u0026rsquo;s ability to undergo shape transformation at body temperature, thereby increasing its contact area with the canal walls, as well as to its elliptical motion, which enables more effective action in hard-to-reach areas of the canal system (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Gentlefile Brush (GFB) is an adjunctive system that, when operated at high speed, expands into a brush-like configuration through centrifugal force, facilitating the removal of debris and biofilm from the canal walls while effectively activating the irrigating solution (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Studies conducted in oval-shaped canals have reported that GFB significantly reduces residual material on canal walls compared with conventional irrigation methods (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Furthermore, micro-CT analyses have demonstrated that GFB is particularly effective in\u003c/p\u003e \u003cp\u003eremoving residual filling material from the apical third of the canal when compared with other techniques (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWithin the limitations of this study, both PTUR\u0026thinsp;+\u0026thinsp;XP-Endo Finisher (XP-EF) and PTUR\u0026thinsp;+\u0026thinsp;Gentlefile Brush (GFB) systems were found to be effective in removing root canal filling material; however, neither technique was able to completely eliminate the filling material. The XP-Endo Finisher demonstrated statistically superior performance compared with Gentlefile Brush in reducing the amount of residual filling material within the canal system.\u003c/p\u003e \u003cp\u003eMicro-computed tomography (micro-CT) proved to be a reliable method due to its ability to provide high-resolution, three-dimensional quantitative analysis; however, its cost and time requirements may limit the number of specimens that can be included in experimental studies. The findings of the present study indicate a continued need for the development of more effective instrumentation strategies for endodontic retreatment procedures.\u003c/p\u003e \u003cp\u003eThese findings may assist clinicians in selecting supplementary instrumentation strategies to enhance cleaning efficacy in oval-shaped root canals during nonsurgical retreatment.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eBL\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBuccolingual\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCBCT\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCone-beam computed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCT\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eComputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eEDTA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEthylenediaminetetraacetic acid\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eGFB\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eGentlefile Brush\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eMD\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMesiodistal\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003emicro-CT (\u0026micro;CT)\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMicro\u0026ndash;computed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eNaOCl\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSodium hypochlorite\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eNi\u0026ndash;Ti\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNickel\u0026ndash;titanium\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003ePTUR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProTaper Universal Retreatment\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eROI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRegion of interest\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eSAF\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSelf-Adjusting File\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eXP-EF\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eXP-Endo Finisher\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval and Participation Permission\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Non-Interventional Clinical Research Ethics Committee of Firat University (Approval Date: March 4, 2020; Approval No: 382607). The extracted teeth used in this study were obtained from patients for clinical reasons, and prior to extraction, the patients were informed that their teeth could be used for scientific research purposes. Written informed consent was obtained from all participants. All procedures were performed in accordance with the relevant national regulations and the principles of the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePublication Permission\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAccessibility of Data and Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed in this study are available from the relevant author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there is no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by the Firat University Scientific Research Projects unit.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFO and EK designed and planned the study. FO performed the experimental procedures. FO performed the micro-CT analysis. EK performed the statistical analysis. FO and EK prepared the draft text. All authors have read and approved the final text.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Department of Endodontics, Faculty of Dentistry, Firat University, and the Research Laboratory, Faculty of Dentistry, Erciyes University, for providing the infrastructure used in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eNg YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 2\u0026mdash;Tooth survival. Int Endod J. 2011;44(7):610\u0026ndash;625.\u003c/li\u003e\n\u003cli\u003eRuddle CJ. Nonsurgical endodontic retreatment. CDA J. 2004;32:474\u0026ndash;484.\u003c/li\u003e\n\u003cli\u003eSeltzer S, Bender I, Smith J, Freedman I, Nazimov H. Endodontic failures\u0026mdash;An analysis based on clinical, roentgenographic, and histologic findings. Part II. Oral Surg Oral Med Oral Pathol. 1967;23(4):517\u0026ndash;530.\u003c/li\u003e\n\u003cli\u003eRuddle CJ. Micro-endodontic nonsurgical retreatment. Dent Clin North Am. 1997;41(3):429\u0026ndash;454.\u003c/li\u003e\n\u003cli\u003eStrindberg LZ. The dependence of the results of pulp therapy on certain factors: an analytical study based on radiographic and clinical follow-up examinations. Acta Odontol Scand. 1956;14:1\u0026ndash;175.\u003c/li\u003e\n\u003cli\u003eSaunders WP, Saunders EM. Coronal leakage as a cause of failure in root canal therapy: a review. Dent Traumatol. 1994;10(3):105\u0026ndash;108.\u003c/li\u003e\n\u003cli\u003eLantz B, Persson P. Periodontal tissue reactions after root perforations in dog\u0026rsquo;s teeth: a histologic study. Odontol Tidskr. 1967;75(3):209\u0026ndash;214.\u003c/li\u003e\n\u003cli\u003eWalton RE, Michelich RJ, Smith GN. The histopathogenesis of vertical root fractures. J Endod. 1984;10(2):48\u0026ndash;56.\u003c/li\u003e\n\u003cli\u003eLin LM, Skribner JE, Gaengler P. Factors associated with endodontic treatment failures. J Endod. 1992;18(12):625\u0026ndash;627.\u003c/li\u003e\n\u003cli\u003eNg YL, Mann V, Gulabivala K. Outcome of secondary root canal treatment: a systematic review of the literature. Int Endod J. 2008;41(12):1026\u0026ndash;1046.\u003c/li\u003e\n\u003cli\u003eH\u0026uuml;lsmann M, Stotz S. Efficacy, cleaning ability and safety of different devices for gutta-percha removal in root canal retreatment. Int Endod J. 1997;30(4):227\u0026ndash;233.\u003c/li\u003e\n\u003cli\u003eSchirrmeister JF. Revision of root canal fillings using engine-driven nickel\u0026ndash;titanium instruments: a literature review. Endodontie. 2006;15:20\u0026ndash;27.\u003c/li\u003e\n\u003cli\u003eKosti E, Lambrianidis T, Economides N, Neofitou C. Ex vivo study of the efficacy of H-files and rotary NiTi instruments to remove gutta-percha and four types of sealer. Int Endod J. 2006;39(1):48\u0026ndash;54.\u003c/li\u003e\n\u003cli\u003eRicucci D, Siqueira JF Jr, Bate AL, Ford TRP. Histologic investigation of root canal\u0026ndash;treated teeth with apical periodontitis: a retrospective study from twenty-four patients. J Endod. 2009;35(4):493\u0026ndash;502.\u003c/li\u003e\n\u003cli\u003eTaha NA, Ozawa T, Messer HH. Comparison of three techniques for preparing oval-shaped root canals. J Endod. 2010;36(3):532\u0026ndash;535.\u003c/li\u003e\n\u003cli\u003ePaqu\u0026eacute; F, Peters OA. Micro\u0026ndash;computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file. J Endod. 2011;37(4):517\u0026ndash;521.\u003c/li\u003e\n\u003cli\u003eFerreira JJ, Rhodes JS, Pitt Ford TR. The efficacy of gutta-percha removal using ProFiles. Int Endod J. 2001;34(4):267\u0026ndash;274.\u003c/li\u003e\n\u003cli\u003eVenturi M, Prati C, Capelli G, Falconi M, Breschi L. A preliminary analysis of the morphology of lateral canals after root canal filling using a tooth-clearing technique. Int Endod J. 2003;36:54\u0026ndash;63.\u003c/li\u003e\n\u003cli\u003eH\u0026uuml;lsmann M, Bluhm V. Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment. Int Endod J. 2004;37(7):468\u0026ndash;476.\u003c/li\u003e\n\u003cli\u003eRoggendorf MJ, Legner M, Ebert J, Fillery E, Frankenberger R, Friedman S. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. Int Endod J. 2010;43(3):200\u0026ndash;209.\u003c/li\u003e\n\u003cli\u003eŞahin F\u0026Uuml;, Topuz \u0026Ouml;. Applications of micro-computed tomography in dental research. Acta Odontol Turc. 2014;31(2):114\u0026ndash;120.\u003c/li\u003e\n\u003cli\u003eJung M, Lommel D, Klimek J. The imaging of root canal obturation using micro-CT. Int Endod J. 2005;38(9):617\u0026ndash;626.\u003c/li\u003e\n\u003cli\u003eVaudt J, Bitter K, Neumann K, Kielbassa AM. Ex vivo study on root canal instrumentation of two rotary nickel\u0026ndash;titanium systems compared with stainless steel hand instruments. Int Endod J. 2009;42(1):22\u0026ndash;33.\u003c/li\u003e\n\u003cli\u003eTakahashi CM, Cunha RS, De Martin AS, Fontana CE, Silveira CFM, Bueno CES. In vitro evaluation of the effectiveness of ProTaper Universal rotary retreatment system for gutta-percha removal with or without solvent. J Endod. 2009;35(11):1580\u0026ndash;1583.\u003c/li\u003e\n\u003cli\u003eAlves FRF, Marceliano-Alves MF, Sousa JCN, Silveira SB, Provenzano JC, Siqueira JF Jr. Removal of root canal fillings in curved canals using reciprocating or rotary systems with a supplementary XP-Endo Finisher step. J Endod. 2016;42(7):1114\u0026ndash;1119.\u003c/li\u003e\n\u003cli\u003eChen JE, Nurbakhsh B, Layton G, Bussmann M, Kishen A. Irrigation dynamics associated with positive pressure, apical negative pressure, and passive ultrasonic irrigation: a computational fluid dynamics analysis. Aust Endod J. 2014;40(2):54\u0026ndash;60.\u003c/li\u003e\n\u003cli\u003ePlotino G, Cortese T, Grande NM, Leonardi DP, Di Giorgio G, Testarelli L, et al. New technologies to improve root canal disinfection. Braz Dent J. 2016;27(1):3\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eBusquim S, Cunha RS, Freire LG, Gavini G, Machado MEL, Santos M. Micro-CT evaluation of long oval canal preparation using reciprocating or rotary systems. Int Endod J. 2015;48(10):1001\u0026ndash;1006.\u003c/li\u003e\n\u003cli\u003eNeelakantan P, Khan K, Li KY, Shetty H, Xi W. Effectiveness of supplementary irrigant agitation with the Finisher GF Brush in oval root canals. Int Endod J. 2018;51(7):800\u0026ndash;807.\u003c/li\u003e\n\u003cli\u003eElliott JC, Dover SD. X-ray microtomography. J Microsc. 1982;126(2):211\u0026ndash;213.\u003c/li\u003e\n\u003cli\u003eRhodes JS, Ford TRP, Lynch JA, Liepins PJ, Curtis RV. Micro-computed tomography: a new tool for experimental endodontology. Int Endod J. 1999;32(3):165\u0026ndash;170.\u003c/li\u003e\n\u003cli\u003eDyck V. Desktop X-ray microscopy and microtomography. J Microsc. 1998;191(2):151\u0026ndash;158.\u003c/li\u003e\n\u003cli\u003eBaşer Can E, Keleş A, Aslan B. Micro-CT evaluation of the quality of root fillings using three obturation systems. Int Endod J. 2017;50(5):499\u0026ndash;505.\u003c/li\u003e\n\u003cli\u003eCrozeta BM, Silva-Sousa YTC, Leoni GB, Mazzi-Chaves JF, Fantinato T, Baratto-Filho F, et al. Micro-CT study of filling material removal from oval-shaped canals using rotary, reciprocating, and adaptive systems. J Endod. 2016;42(5):793\u0026ndash;797.\u003c/li\u003e\n\u003cli\u003eWu MK, Ka\u0026scaron;t\u0026rsquo;\u0026aacute;kov\u0026aacute; A, Wesselink PR. Quality of cold and warm gutta-percha fillings in oval canals of mandibular premolars. Int Endod J. 2001;34(6):485\u0026ndash;491.\u003c/li\u003e\n\u003cli\u003eRicucci D, Siqueira JF Jr. Biofilms and apical periodontitis: prevalence and association with clinical and histopathologic findings. J Endod. 2010;36(8):1277\u0026ndash;1288.\u003c/li\u003e\n\u003cli\u003eSilva EJNL, Orlowsky NB, Herrera DR, Machado R, Krebs RL, Coutinho-Filho TDS. Effectiveness of rotary and reciprocating movements in root canal filling removal. Braz Oral Res. 2015;29(1):1\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eRossi-Fedele G, Ahmed HMA. Assessment of root canal filling removal using micro-CT: a systematic review. J Endod. 2017;43(4):520\u0026ndash;526.\u003c/li\u003e\n\u003cli\u003eNguyen TA, Kim Y, Kim E, Shin SJ, Kim S. Comparison of techniques for root canal filling removal in artificial teeth: a micro-CT study. J Clin Med. 2019;8(7):984.\u003c/li\u003e\n\u003cli\u003eGu LS, Ling JQ, Wei X, Huang XY. Efficacy of ProTaper Universal retreatment system for gutta-percha removal. Int Endod J. 2008;41(4):288\u0026ndash;295.\u003c/li\u003e\n\u003cli\u003eSae-Lim V, Lim BK, Lee HL. Effectiveness of ProFile .04 taper rotary instruments in retreatment. J Endod. 2000;26(2):100\u0026ndash;104.\u003c/li\u003e\n\u003cli\u003eGergi R, Sabbagh C. Effectiveness of two NiTi rotary instruments and hand files in severely curved canals. Int Endod J. 2007;40(7):532\u0026ndash;537.\u003c/li\u003e\n\u003cli\u003eKeleş A, Şimşek N, Alcin H, Ahmetoglu F, Yologlu S. Retreatment of flat-oval canals with a self-adjusting file: an SEM study. Dent Mater J. 2014;33(6):786\u0026ndash;791.\u003c/li\u003e\n\u003cli\u003eHammad M, Qualtrough A, Silikas N. Three-dimensional evaluation of retreatment techniques. J Endod. 2008;34(11):1370\u0026ndash;1373.\u003c/li\u003e\n\u003cli\u003eTachibana H, Matsumoto K. Applicability of X-ray CT in endodontics. Dent Traumatol. 1990;6(1):16\u0026ndash;20.\u003c/li\u003e\n\u003cli\u003eMichetti J, Maret D, Mallet JP, Diemer F. Validation of CBCT for root canal anatomy assessment. J Endod. 2010;36(7):1187\u0026ndash;1190.\u003c/li\u003e\n\u003cli\u003ePlotino G, Grande NM, Pecci R, Bedini R, Pameijer CH, Somma F. Three-dimensional imaging using micro-CT for tooth morphology. J Am Dent Assoc. 2006;137(11):1555\u0026ndash;1561.\u003c/li\u003e\n\u003cli\u003eH\u0026uuml;lsmann M, Peters OA, Dummer PMH. Mechanical preparation of root canals. Endod Topics. 2005;10(1):30\u0026ndash;76.\u003c/li\u003e\n\u003cli\u003eCampos JM, del Rio C. Comparison of mechanical and hand instrumentation techniques. J Endod. 1990;16(5):230\u0026ndash;234.\u003c/li\u003e\n\u003cli\u003eCraig RG, Gehring PE, Peyton FA. Relation of structure to microhardness of human dentin. J Dent Res. 1959;38(3):624\u0026ndash;630.\u003c/li\u003e\n\u003cli\u003eGiuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper Universal retreatment files. J Endod. 2008;34(11):1381\u0026ndash;1384.\u003c/li\u003e\n\u003cli\u003eHorvath S, Altenburger MJ, Naumann M, Wolkewitz M, Schirrmeister JF. Cleanliness of dentinal tubules after gutta-percha removal with and without solvents. Int Endod J. 2009;42(11):1032\u0026ndash;1038.\u003c/li\u003e\n\u003cli\u003eCarvalho MC, Zuolo ML, Arruda-Vasconcelos R, Marinho ACS, Louzada LM, Francisco PA, et al. Effectiveness of XP-Endo Finisher in reducing bacterial load in oval canals. Braz Oral Res. 2019;33:e021.\u003c/li\u003e\n\u003cli\u003eKaramifar K, Mehrasa N, Pardis P, Saghiri MA. Canal wall cleanliness after gutta-percha removal: an in vitro analysis. Iran Endod J. 2017;12(2):242\u0026ndash;246.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"Root canal retreatment, Oval-shaped root canals, Removal of filling remnants, Micro-computed tomography, XP-Endo Finisher, Gentlefile Brush","lastPublishedDoi":"10.21203/rs.3.rs-8434085/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8434085/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThis study aimed to compare, using micro\u0026ndash;computed tomography (\u0026micro;CT), the effects of the XP-Endo Finisher (XP-EF) and Gentlefile Brush (GFB) files\u0026mdash;used as supplementary instrumentation following Ni\u0026ndash;Ti retreatment\u0026mdash;on the volume of remaining root canal filling material in oval-shaped root canals.\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eTwenty single-rooted, single-canal mandibular premolars with oval-shaped canals extracted for periodontal or orthodontic reasons were included. The canals were prepared up to size F4 using the ProTaper Universal system, obturated with gutta-percha and AH Plus, and incubated for one month. After initial \u0026micro;CT scanning, the filling material was removed using the ProTaper Universal Retreatment system, and the specimens were allocated into two groups according to the supplementary instrumentation: XP-EF or GFB. A second \u0026micro;CT scan was performed after the additional instrumentation procedures.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eA statistically significant reduction in the volume of filling material was observed in both groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, the volumetric reduction achieved in the XP-EF group was significantly greater than that in the GFB group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Complete removal of the filling material was not achieved with either method.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAlthough both supplementary systems were effective in reducing residual filling material, XP-Endo Finisher demonstrated superior performance in oval-shaped root canals.\u003c/p\u003e","manuscriptTitle":"Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-19 11:35:31","doi":"10.21203/rs.3.rs-8434085/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-02-15T20:14:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"210872322563568945435138579009918863149","date":"2026-02-13T12:56:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-13T12:49:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-07T04:58:47+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-26T06:49:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-25T08:10:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-12-25T08:04:58+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":"8065bb35-db0a-456e-9fe4-3e58da4f5e52","owner":[],"postedDate":"February 19th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-19T11:35:31+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-19 11:35:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8434085","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8434085","identity":"rs-8434085","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}