972 D3000 new imprint Word template Vol 13, No 1 (2025) ISSN 2167-8677 (online) DOI 10.5195/d3000.2025.972 http://dentistry3000.pitt.edu Citric Acid Irrigation Protocols for Bioceramic Sealers for Root Canal Retreatments Mustafa Imad Saleh, Emad Farhan Alkhalidi College of Den*stry, University of Mosul, Mosul, Iraq Abstract Objec;ve: Root canals treated with bioceramic sealers that need retreatment present a clin- ical challenge. The presented study assessed 20% citric acid (with and without acNvaNon) in removing bioceramic sealer remnants. Material and Methods: Thirty extracted human lower premolars teeth were obturated with guQa-percha using bioceramic sealer, and have been split into three groups, each consisNng of ten teeth: (1) 20% citric acid without acNva- Non, (2) 20% citric acid with ultrasonic acNvaNon, and (3) control group uNlizing ProTaper Universal retreatment files exclusively. A scanning electron microscope (SEM) was used to invesNgate the remaining sealer remnants at the coronal, middle and apical thirds. The per- centage of the uncleaned canal areas was determined quanNtaNvely with the use of ImageJ so\ware. Results: One-Way ANOVA had shown a significant difference between groups (p less than 0.001). At 64.8% ± 3.1, the control group had the greatest mean residual debris. While ultrasonic acNvaNon further improved cleaning efficacy (44.0% 2.6), irrigaNon with cit- ric acid greatly reduced remnants (50.8% 4.9). Applying ultrasonic acNvaNon had the biggest cleaning impact in the apical third. In the apical third, the lowest debris was observed in the acNvaNon group (41.1% ± 0.9) vs. 45.3% (citric alone) and 65.7% (control). In the middle third, respecNve values were 44.1%, 51.5%, and 64.1%. In the coronal third, results were 64.8%, 55.5%, and 64.5%, respecNvely. Conclusion: According to our results, citric acid irrigaNon sig- nificantly enhances the removal of bioceramic sealer remnants from root canal walls, parNc- ularly when combined with ultrasonic acNvaNon. Compared to mechanical retreatment alone, the combinaNon of chemical irrigaNon and acNvaNon resulted in a greater reducNon of residual material. Citric acid signifi- cantly enhances the removal of bioc- eramic sealer remnants, parNcularly in the middle and apical thirds. Ultrasonic acNvaNon further improves efficacy, with the apical third showing the most nota- ble improvement (41.1% vs. 65.7% in control). This protocol demonstrates a clinically effecNve and pracNcal approach to improving the efficiency of endodonNc retreatment procedures. Open Access Cita%on: Saleh MI, et al. (2025) Citric Acid Irriga%on Pro- tocols for Bioceramic Sealers for Root Canal Retreat- ments. Den%stry 3000. 1:a001 doi:10.5195/d3000.2025.972 Received: June 27, 2025 Accepted: July 26, 2025 Published: August 15, 2025 Copyright: ©2025 Saleh MI, et al. This is an open access ar%cle licensed under a Crea%ve Commons ARribu%on Work 4.0 United States License. Email: emadfarhanalkhalidi@uomosul.edu.iq Introduc)on Preserving the periapical and apical tissues' health and avoiding recontamination of the root-7illed canal are the two main objec- tives of endodontic treatment [1]. The quality related to root canal obturation as well as the materials utilized, such as en- dodontic sealers, have a major impact on outcomes of endodontic treatments. For the endodontically treated tooth to be successful and survive over the long run, such materials should guarantee a 3D seal within the root canal system, avoiding re-infection. An endo- dontic sealer is essential to root canal treat- ment. To create a coherent mass, it 7ills in the spaces, imperfections, and small differences between core 7iller material and canal walls [2]. Regarding the obturation of the root canal, gutta percha has been utilized with various sealers. Bio-ceramics, a new high-purity tricalcium silicate sealer class, has just been introduced and may have some advantages when compared to other types of sealers. The two main advantages of using hydrau- lic calcium silicate-based (HCS) bio-ceramic materials as sealants of the root canal are their biocompatibility in addition to the ex- istence of calcium phosphate. Bonding to the dentin of the root canal has been improved due to the composition and crystalline struc- tures that have near resemblance to the tooth and bone apatite materials [3]. Primary endodontics never achieve 100% success rates. Endodontic retreatment is typically required when an infection is Citric Acid IrrigaNon Protocols for Bioceramic Sealers for Root Canal Retreatments Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.972 http://dentistry3000.pitt.edu 2 ongoing or recurrent and the tooth still shows symptoms, such as ongoing pain, in- 7lammation, or swelling. Furthermore, a sec- ond intervention could be necessary for sev- eral complications and problems, including inadequate pulp tissue removal, non-her- metic root canal sealing, and missing root ca- nals [4]. Over the past 15 years, bioceramic sealers based on calcium silicate have become more and more popular. A recent survey found that 27% of American Dental Association (ADA) members and 49% of American Asso- ciation of Endodontists (AAE) members re- ported utilizing bioceramic sealers, which have overtaken resin-based sealers as the most popular form of sealer among endo- dontists [5]. However, one of the major disadvantages of the bioceramic materials is the dif7iculty to remove them from the root canal through- out retreatment. Bioceramic sealer cannot be removed using traditional retreatment processes [6]. Heat-carrying tools, hand 7iles, ultrasonic de- vices, chemical solvents, and lasers are only a few of the materials and methods that were suggested for the appropriate removal of the root canal 7illings. Yet, it is typically very dif7icult to retreat root canals that have previously been sealed with bioceramic seal- ers. Because bioceramic materials adhere to the dentin through the formation of mineral in7iltration zones and penetrate further into the dentinal tubules, they are seldom re- moved from the root canal system, even when manually [7]. The bioceramic sealers were not successfully dissolved or dislodged by the irrigating solutions that have been previously tested, which included NaOCl, EDTA, carbonated water, and formic and acetic acids. Thus, the requirement for sol- vents for HCS materials continues to be a fo- cus of therapeutic interest [8]. Additional techniques were developed to make the re- moval of the set bioceramic sealers easier. These procedures involve mechanical re- moval, active irrigation, and using substitute solvents [7]. Regarding endodontic research, citric acid is a colorless organic acid that is frequently studied for various objectives [9]. Citric acid hasn't received much attention, neverthe- less, as a possible solvent for bioceramic sealers. According to evidence-based litera- ture currently available on the chemistry of the HCS cements, citric acid causes calcium- based hydration products to gradually dis- solve, ultimately compromising the materi- al's structural integrity [10]. Consequently, if the citric acid dissolves the HCS components, it is reasonable to anticipate that the solution might be utilized as a solvent throughout en- dodontic retreatment as necessary. To determine how well 20% citric acid, without or with ultrasonic activation, removed bioc- eramic sealers from root canals during endo- dontic retreatment. The presented work was conducted. In particular, the research aimed to ascertain whether ultrasonic activation may improve the effectiveness of HCS-based sealers in removing residual material from the middle, coronal, and apical thirds of ca- nal, as well as whether citric acid could func- tion as a chemical solvent for these sealers. Material and Methods Sample Preparation Thirty extracted human lower premolars were collected from patients aged between 18 and 28 years who had undergone extrac- tion for orthodontic treatment purposes. All selected teeth exhibited straight canals, fully formed apices, and no signs of internal or ex- ternal resorption (Garg et al., 2015) [11]. Af- ter extraction, the teeth have been rinsed un- der running water, disinfected, and after that stored in 1% thymol solution in a closed con- tainer to prevent microbial growth, as de- scribed by D’Attilio et al. (2005) [12]. Diagnostic periapical radiographs have been taken in order to verify the inclusion requirements. Tooth length was measured using a digital Vernier caliper; specimens that were excessively short were not in- cluded. A diamond disc bur mounted on straight handpiece attached to a surveyor under continuous water coolant was utilized in order to section the crowns of the last 30 teeth, standardizing their length to 17 mm from apex. A diamond round bur was used to construct access cavities, and pulp chamber's whole roof was taken off. A size 10K-7ile and a size 15 K-7ile were used to con7irm canal patency. Through deducting 0.5 mm from the length at which the 7ile tip has been visible at the ap- ical foramen, the working length has been determined to be 16.5 mm (Bernardes et al., 2016). The Protaper universal rotary system was utilized for preparing the root canal in crown down procedure, beginning with SX and pro- ceeding to S2, S1, F2, F1, and F3 after each sample was placed in a mold 7illed with heavy body silicon imprint material and mounted on the surveyor (Iqbal et al., 2004). The rotary device's default settings for speed and torque have been followed. The coronal two thirds of the canal were enlarged using SX, after that S1 and S2 were utilized to reach the working length. Finally, 7iles F1 through F3 were 7inished, with irrigation (5.25% so- dium hypochlorite) employed in between each 7ile. Following instrumentation, the ca- nals were cleaned with normal saline, irri- gated for one minute with 17% EDTA, rinsed again with normal saline, and dried with F3 paper points. A heated instrument was after that used for removing the excess core materials after the sealer has been initially placed in the ca- nal and after that the F3 Gutta perch cone was placed into the canal to working length utilizing the single cone technique [13]. The heavy body's obturated teeth were taken out, wrapped in moist cotton, 7illed with GIC, and put in separate test tubes. To fully set the sealer and age the 7illing material, the tubes were put on a tray and kept in an incubator set at 37o Celsius and 95% humidity for four weeks [14]. Sample Grouping Three sets of ten samples each have been randomly selected from all the sam- ples. • Group 1: Retreatment was carried out uti- lizing a combination of chemical and me- chanical procedures following obturation with bioceramic sealer and subsequent incu- bation. ProTaper Universal retreatment files (D1, D2, D3) have been utilized in order to instrument canals in such group for remov- ing the majority of filling material. After in- strumentation, 20% citric acid has been manually added to help remove any re- maining sealer remnants. A 30-gauge side- vented needle that was inserted up to 2 mm short of the working length (WL) was used for irrigation. In this group, no supplemen- tary activation—such as ultrasonic—was used. • Group 2: ProTaper Universal retreatment files (D1, D2, D3) have been utilized in order to mechanically remove the obturation ma- terial as part of the retreatment methodol- ogy. Following mechanical retreatment, an ultrasonic tip (size 20, taper 0.01) inserted 2 mm short of the WL was used for activat- ing the canals as well as irrigate them with 20% citric acid. With three activation cycles per canal, the ultrasonic device was run at low to medium power for 20 seconds each cycle. To optimize its chemical impact, the solution was refilled in between activations. • Group 3: the control group: ProTaper Uni- versal Retreatment files that have been con- nected to an endodontic motor were used to perform the retreatment operation. ProTa- per Universal Retreatment files (D1, D2, D3) have been used for retreatment; no extra ir- rigation or activation was necessary. The coronal third of the canal was represented by the D1 file, the middle third by the D2 file, and the apical third by the D3 file. Evaluation of the Residual Bioceramic Sealer After retreatment, all samples were sec- tioned longitudinally utilizing a diamond Citric Acid IrrigaNon Protocols for Bioceramic Sealers for Root Canal Retreatments Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.972 http://dentistry3000.pitt.edu 3 disc bur that is mounted on a straight slow- speed handpiece under continuous water coolant. The sectioned specimens were ini- tially evaluated using a digital stereomicro- scope connected to a computer. Images have been captured at 5x magni7ication to visual- ize full root surface and at 10x magni7ication to focus on coronal, middle, and apical thirds in a separate manner. Those images have en- sured the standardized documentation of every one of the regions and have later been utilized for the quantitative analyses. For ad- ditional characterization of the surface, rep- resentative samples from every one of the groups have been selected then analyzed un- der an SEM. Six images were taken per sam- ple—3 per root third—captured from the center of every one of the regions. Images have been obtained at 100x magni7ication for the general observation, 250x for the evaluation of the smear layer, and 1000x for high-resolution inspection of the sealer rem- nants and dentinal tubule exposure. SEM analysis had provided a qualitative compre- hension of the structural detail and cleanli- ness of the surface, consistent with methods that have been described by Hess etal. (2011) and Zuolo etal. (2021) [4,15]. For quantifying residual sealer, all of the SEM im- ages had been analyzed utilizing ImageJ soft- ware (v1.53, National Institutes of Health, Bethesda, MD, U.S.). The software was cali- brated using the embedded scale bar in each image. The canal wall area has been manu- ally outlined using the polygon tool, and the remaining bioceramic sealer was isolated us- ing the Color Threshold function. The sealer- covered regions were measured in square millimeters using the Analyze > Measure tool, and the percentage of uncleaned area was calculated relative to the total canal sur- face. Each image was analyzed three times to ensure consistency, and the mean value was used for statistical comparisons [16,17]. Results A total of 90 root canals area (apical, middle, coronal) were analyzed, divided equally among three groups (2 experimental and one control groups), (n=30 each). The out- come was the percentage of uncleaned canal surface area following different irrigation protocols. Table 1 shows the mean percentages of un- cleaned areas across the groups. The control group showed the highest mean percentage of uncleaned area (64.8% ± 3.1). Shapiro- Wilk test results confirmed normal distribution in all groups (p > 0.05). A One- Way ANOVA revealed a statistically signifi- cant difference among the groups (Table 2). Comparative Evaluation: Control vs. Cit- ric Acid Groups Comparative Evaluation in Coronal Third The mean percentages of uncleaned areas in the coronal part for selected groups (Table 3) showed the highest residual debris in both the Control (64.5% ± 3.4) and Citric Acid + Activation (64.8% ± 1.3) groups. Citric Acid alone had a lower mean value (55.5% ± 2.4). Comparative Evaluation in the Middle Third Table 4 presents the average percentages of uncleaned areas in the middle part of the root canals for the Control and Citric Acid groups. The Control group exhibited the highest mean residual debris (64.1% ± 3.4), followed by Citric Acid (51.5% ± 2.5). Citric Acid + Activation showed improved cleaning efficacy (44.1% ± 1.1). Comparative Evaluation in Apical Third The apical portion of the root canal (Table 5) revealed the highest percentage of un- cleaned areas in the Control group (65.7% ± 2.5). Citric Acid alone resulted in a mean of 45.3% ± 2.9, while the Citric Acid + Activa- tion group achieved better cleaning out- comes with a mean of 41.1% ± 0.9. Discussion The present study examined the effective- ness of 20% citric acid, both with and with- out ultrasonic activation, in the removal of bioceramic sealer remnants from root ca- nals. Compared with mechanical file-only re- treatment, this approach provided more substantial cleaning, especially in the middle and apical thirds. Mechanical instrumentation alone, as seen in the control group, was insufficient to elimi- nate bioceramic sealers, a finding echoed in multiple studies. For instance, Hess et al. (2011) [15] reported that even with ad- vanced rotary systems, significant residues of bioceramic sealers persist due to their chemical bonding to dentin. Similarly, Neelakantan et al. (2015) [18] have demon- strated that the physical integrity and apa- tite-forming capacity of calcium silicate- based sealers contribute to their resistance to mechanical removal, Mahmmod and Al- Sabawi (2022) [19], who demonstrated that mechanical retreatment using rotary files alone left extensive amounts of sealer resi- due. Similar observations were reported by Chybowski et al. (2021) [5], highlighting the difficulty in removing bioceramic sealers due to their strong adhesion and formation of a mineral infiltration zone. Our findings expand on previous research. Attash and Al-Ashou (2022) [2] emphasized the bond strength and tubule penetration of bioceramic sealers as major obstacles during retreatment, which explains the difficulty seen in our control group. Meriem Fejjer et al. (2024) [6] showed that EDTA and NaOCl are inadequate against HCS sealers—a no- tion supported here, as citric acid alone proved more effective. In contrast to Mahmmod and Al-Sabawi (2022) [19], who focused on XP-Endo fin- isher retreatment, our study used conven- tional ProTaper retreatment files and still demonstrated significant improvements when supplemented with citric acid proto- cols. While they achieved improved cleaning using XP-Endo, they noted high residue with- out activation—supporting our finding that activation significantly enhances retreat- ment outcomes. Citric acid irrigation alone significantly re- duced residual sealer levels (mean 50.8% ± 4.9), and ultrasonic activation further en- hanced this efficacy (44.0% ± 2.6). This con- firms findings by Yang et al. (2018) [10] that citric acid effectively chelates calcium ions in HCS sealers, weakening their integrity. Gómez et al. (2023) [9] also supported the role of citric acid as a viable chelating agent, showing improved outcomes over EDTA and NaOCl in terms of smear layer and material dissolution. Regional Differences in Cleaning Efficacy Coronal-Third Unexpectedly, both the control group and the Citric Acid + Activation group showed high debris retention in the coronal third (64.5% and 64.8%, respectively). This may be due to debris compaction during coronal activation, as also noted in the root canal rre- treatment study by Zuolo et al. (2021) [4]. Similar issues were described by Fejjer et al. (2024), who suggested that excessive pres- sure or ultrasonic turbulence may lead to lo- calized reinsertion of dislodged debris in larger canal areas. Middle-Third The Citric Acid + Activation group outper- formed others in the middle third (44.1% vs. 51.5% in citric alone and 64.1% in control). These findings are consistent with studies by Carrillo et al. (2022) and Garrib and Camil- leri (2020) [7,8], who emphasized the role of agitation in improving irrigant reach and dis- lodging particles embedded in canal walls. Citric Acid IrrigaNon Protocols for Bioceramic Sealers for Root Canal Retreatments Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.972 http://dentistry3000.pitt.edu 4 Apical-Third The apical third presented the most striking differences. Activation led to the lowest sealer remnants (41.1%), followed by citric acid alone (45.3%) and control (65.7%). These results strongly correlate with da Silva et al. (2012) [14], who found ultrasonic acti- vation most beneficial in narrow apical re- gions. Additionally, D’Attilio et al. (2005) [12] highlighted how mechanical-only ap- proaches often fail in this region due to re- stricted access. Conclusions This study investigated the ef7icacy of 20% citric acid, both with and without ultrasonic activation, for removing bioceramic sealer remnants during endodontic retreatment. The 7indings revealed that mechanical in- strumentation alone (control group) was sig- ni7icantly less effective, especially in the api- cal third of the root canal. Citric acid irriga- tion signi7icantly improved cleaning perfor- mance, and its combination with ultrasonic activation yielded the lowest residual debris levels across all root thirds, particularly in the apical region. These results underscore the limitations of conventional retreatment using rotary 7iles and highlight the importance of chemical support, especially when dealing with bioc- eramic sealers. The use of 20% citric acid, particularly with ultrasonic activation, emerges as a clinically viable and effective supplement to mechanical retreatment tech- niques. The study supports integrating these protocols into routine retreatment proce- dures to enhance debridement and improve clinical outcomes. References [1] Alalaf, N. and Alkhalidi, M. (2022) ‘Comparative assessment of root canal sealer’s apical sealing ability’, Al-RaLidain Dental Journal, 22(1), pp. 124– 135. https://doi.org/10.33899/rdenj.2022.129250.10 77. [2] Attash, I. and Al-Ashou, W. (2022) ‘Push-out bond strength evaluation for different endodontic sealers: A comparative study’, Al-RaLidain Dental Journal, 22(2), pp. 301–312. https://doi.org/10.33899/rdenj.2022.130209.11 05 [3] de Oliveira, D. S., Galo, R. and Tanomaru-Filho, M. (2019) ‘Biocompatibility and bioactivity of cal- cium silicate-based sealers: A review’, Dental Ma- terials Journal, 38(1), pp. 14–25. [4] Zuolo, A. S., Carvalho, M. C. and De-Deus, G. (2021) ‘Retreatability of bioceramic sealers: A mi- cro-CT study’, International Endodontic Journal, 54(3), pp. 514–522. [5] Chybowski, E. A., et al. (2021) ‘Bioceramic seal- ers in clinical endodontics’, Journal of Endodon- tics, 47(5), pp. 651–659. [6] Meriem Fejjer, M., et al. (2024) ‘Evaluation of bioceramic sealer removal: A comparative study of various irrigants’, Journal of Endodontic Research, 18(1), pp. 33–42. [7] Carrillo, C. M., Arias, A. and de la Macorra, J. C. (2022) ‘Solubility and disintegration of hydraulic calcium silicate sealers’, Clinical Oral Investiga- tions, 26(1), pp. 103–111. [8] Garrib, A. and Camilleri, J. (2020) ‘Evaluation of the solubility of hydraulic sealers in different solu- tions’, International Endodontic Journal, 53(2), pp. 273–281. [9] Gómez, M. P., Muñoz, C. and Cárdenas, M. (2023) ‘The use of citric acid in endodontics: A sys- tematic review’, Journal of Dentistry, 136, p. 104288. [10] Yang, Q., Sun, X. and Wang, X. (2018) ‘Dissolu- tion behavior of calcium silicate cements in weak acid solutions’, Materials Science and Engineering: C, 82, pp. 98–106. [11] Garg, N. and Garg, A. (2015) ‘The Effect of Resin and Bioceramic Sealer on Microleakage Af- ter Bacterial Penetration’, JIDA: Journal of Indian Dental Association. [12] D’Attilio, M., et al. (2005) ‘SEM evaluation of canal preparation using rotary NiTi instruments’, Journal of Clinical Pediatric Dentistry, 30(1), pp. 65–70. [13] Kaşıkçı Bilgi, I., Köseler, I., Güneri, P., Hüls- mann, M. and Çalışkan, M. K. (2017) ‘EfLiciency and apical extrusion of debris: a comparative ex vivo study of four retreatment techniques in severely curved root canals’, International Endodontic Journal, 50(9), pp. 910–918. [14] da Silva, E. J. N. L., et al. (2012) ‘Sealing ability of bioceramic and epoxy-resin sealers: A bacterial leakage study’, International Endodontic Journal, 45(1), pp. 1–7. [15] Hess, D., et al. (2011) ‘Effectiveness of rotary instruments in removing bioceramic sealers’, Jour- nal of Endodontics, 37(10), pp. 1352–1356. [16] Akcay, M., et al. (2016) ‘Quantitative evalua- tion of residual sealer using ImageJ software’, Journal of Dental Research, 95(6), pp. 1–7. [17] Pereira, T. C., et al. (2017) ‘Standardized anal- ysis of endodontic sealer remnants using digital tools’, Clinical Oral Investigations, 21(8), pp. 2511–2518. [18] Neelakantan, P., Nandagopal, M., Shemesh, H. and Wesselink, P. R. (2015) ‘The effect of root den- tin conditioning protocols on the push-out bond strength of three calcium silicate sealers’, Interna- tional Journal of Adhesion and Adhesives, 60, pp. 104–108. [19] Mahmmod, A. and Al-Sabawi, N. (2022) ‘CBCT evaluation of two rotary systems with and without XP-Endo Finisher for retreatability of canals obtu- rated with bioceramic sealer’, Al-RaLidain Dental Journal, 22(2), pp. 220–232. https://doi.org/10.33899/rdenj.2021.130773.11 14 Table 1. Uncleaned areas values. Groups N Mean % SD SE Minimum Maximum Control 30 64.8 3.1 0.5 60.0 70.0 Citric Acid 30 50.8 4.9 0.9 40.0 60.0 Citric Acid + Activa- tion 30 44.0 2.6 0.4 40.0 50.0 Table 2. Summary of the comparisons. Percentage of unclean areas Groups N Mean SD Statistics df *P-Value Citric Acid 30 50.8 4.9 310.4 3 < 0.001 Citric Acid + Activation 30 44.0 2.6 Citric Acid + Laser activa- tion 30 39.2 2.5 Control 30 64.8 3.1 Citric Acid IrrigaNon Protocols for Bioceramic Sealers for Root Canal Retreatments Vol 13, No 1 (2025) DOI 10.5195/d3000.2025.972 http://dentistry3000.pitt.edu 5 Table 3. The mean percentage of uncleaned areas in the coronal third (selected groups). Group N Mean % SD SE Min Max Control 10 64.5 3.4 1.1 60.0 69.0 Citric Acid 10 55.5 2.4 0.7 52.3 60.0 Citric Acid + Activation 10 64.8 1.3 0.4 45.5 50.0 Table 4. The mean percentage of uncleaned areas in the middle third (selected groups). Group N Mean % SD SE Min Max Control 10 64.1 3.4 1.1 60.2 70.0 Citric Acid 10 51.5 2.5 0.8 47.6 56.9 Citric Acid + Activation 10 44.1 1.1 0.3 42.2 45.5 Table 5. The mean percentage of uncleaned areas in the apical third (selected groups). Group N Mean % SD SE Min Max Control 10 65.7 2.5 0.8 60.0 68.9 Citric Acid 10 45.3 2.9 0.9 40.0 49.2 Citric Acid + Activation 10 41.1 0.9 0.2 40.0 42.2