Efficacy of Reciprocating Instruments in Retreatment of Bioactive and Resin-Based Root Canal Sealers

Abstract

Objective

To compare the effectiveness of reciprocating instruments in removing gutta-percha and bioactive-based (BioRoot RCS and MTA Fillapex) and epoxy resin-based (AH Plus) sealers from root canals based on filling residues and the time required for root canal revision.

Material and methods

Root canals of 90 teeth were instrumented with Reciproc R40. All root canals were obturated using the single-cone technique with Reciproc R40 gutta-percha and with one of the selected sealers. Samples with oval, straight canals were used and randomly divided into three groups: (i) filled with AH Plus sealer and gutta-percha (n=30); (ii) filled with MTA Fillapex and gutta-percha (n=30); (iii) filled with BioRoot RCS and gutta-percha (n=30). Each group was divided into two subgroups (n=15) according to the retreatment instrument used (Reciproc M-Wire R25/R40 or Reciproc blue RB25/RB40). Root canals were longitudinally split and analyzed with a stereomicroscope at 15 × magnifications in the coronal, middle, and apical third. Computational analyses were performed with the Image J software. Data were compared using the Kruskal-Wallis test and Mann-Whitney U test.

Results

While no statistically significant differences in the residual material surface were found for Reciproc Blue, Reciproc M-Wire showed significantly higher residual material surface for AH Plus and MTA Fillapex compared to BioRoot RCS. For AH plus. Residual material surface was significantly lower for Reciproc Blue than for Reciproc M-Wire. In contrast, BioRoot RCS showed a significantly higher residual material surface for Reciproc Blue.

Conclusions

Calcium silicate-containing sealers were more retrievable compared to AH Plus, with fewer sealer remnants and shorter retreatment time. Retreatment with Reciproc M-Wire instruments was superior to Reciproc blue instruments in retreatment of BioRoot RCS. However, none of the sealers were removed completely.

Introduction

The failure of primary endodontic treatment necessitates retreatment of the entire endodontic space (1). This procedure is successful if it results in a healed condition and long-term dental retention. There are different retreatment approaches (2, 3), the success of which is closely related to the retreatment method and type of root filler (4).

Despite improved and efficient endodontic techniques and materials, remnants of old fillers can remain in the cavity (5–7). The root canal is usually obturated with gutta-percha and a sealer. Appropriate chemo-mechanical preparation of the root canal system and good obturation with a central gutta-percha cone surrounded by a sealer are considered the major factors for the success of the primary endodontic treatment (8, 9). Failures of endodontic treatment may occur due to various procedural errors, leading to the need for retreatment. The complete removal of the old filling, despite the development of new technologies, methodologies, fillings, and solvents, remains challenging in modern endodontics (10). The fast development of NiTi rotary instruments resulted in many different systems which simplified shaping and increased the predictability and effectiveness of the endodontic treatment. The sequences have become less invasive, the coronal taper is less pronounced, and apical finishing procedures have become more sophisticated to improve sealing (11).

Gutta-percha combined with an epoxy-resin sealer or zinc oxide eugenol sealer are considered the gold-standard endodontic materials for root canal obturation (12, 13). To date, numerous studies have examined the removal efficacy of the aforementioned filling materials (14–16). AH Plus is popular because of its good sealing ability and adhesion (14) and low solubility and disintegration (17). Bioactive sealers have been developed to provide improved materials for root canal filling. Newer sealers are based on a bioactive technology to provide a better root canal obturation with minimal postoperative complications and are known for their antibacterial effect (16–18) and good biocompatibility (19, 20).

Mineral trioxide-based sealers have been introduced based on the biological properties of mineral trioxide aggregates (MTAs). However, some studies have obtained conflicting results on their bioactivity. The bioactive properties of a salicylate resin-based sealer with 13.2% set MTA mixed in as a filler could not be determined in vivo (21). However, several studies have shown the bioactive potential of MTA Fillapex, the mineralizing ions (Ca²⁺) of which bind biological active ions and nucleation of apatite precursors on the material surface with lower calcium release and less apatite deposition after aging in Hank’s balanced salt solution (HBSS) compared to the BioRoot RCS (22). MTA Fillapex, on the other hand, is a salicylate resin-based sealer with 13.2% set MTA admixed as a filler (21, 23). Furthermore, MTA Fillapex has also expressed bioactive potential in subcutaneous tissue in vivo (24). Therefore, ex vivo and in vivo studies are required to confirm the suitability of these salicylate resin-based sealers with MTA filler for clinical application.

The positive bioactive and regenerative properties of BioRoot RCS have shown the potential of bioactive materials to (19) create a hard barrier (19, 22), provide antimicrobial activity (4, 16, 17) and high pH (>11) (4), and prolong calcium ion release, which are key factors in endodontic and periodontal tissue regeneration (22). Previous studies on the retrievability of hydraulic sealers have mostly used AH Plus sealers (25), but no consensus on its removal has been reached. Therefore, this study examines the success of hydraulic sealer retreatment to resolve the previously reported conflicting results.

The development of Nickel-Titanium motor-driven instruments has made mechanical retreatment easier and more effective (5, 14, 26), thus improving processing and the ability to clean (26) and reshaping of root canal system (27). Reciprocating one-instrument systems emerged in the autumn of 2011, enabling retention of the original root shape due to their improved mechanical properties and reciprocating movement (14) and simplifying the retreatment procedure of the endodontic space by saving time (12, 26) and avoiding cross-infection (7, 14). Reciproc blue instruments represent the next generation of reciprocating instruments, subjected to high temperatures after manufacturing procedures to improve their flexibility and cyclic fatigue resistance (28) and increase their life span. Their design and operation are the same as those of the Reciproc M-wire system. Reciproc blue and Reciproc M-wire instruments were previously used in initial root treatment and retreatment (29, 30).

This ex vivo study uses extracted teeth to compare the efficacy and retreatment times of reciprocating instruments Reciproc M-Wire and Reciproc blue files in removing gold-standard epoxy resin-based sealer and two calcium silicate-based sealers, MTA Fillapex and BioRoot RCS. Various retreatment techniques have been used for many years, but the ideal method is still being sought. Our first null hypothesis was that retreatment remnants do not differ significantly among the three different sealers (AH Plus, MTA Fillapex, and BioRoot RCS) when treating root thirds and entire root canal using reciprocating instruments Reciproc blue and Reciproc M-Wire files. Our second null hypothesis was that time required for the retreatment procedure with reciprocating files would not differ significantly among the three materials.

Material and methods

Sample Size Calculation

Sample size calculation was performed considering the percentage of residual material surface as a primary parameter of interest. For an initial (orientational) power analysis, the article by Katunarić et al. (12) was used due to a similar methodology of evaluating the residual material. This power analysis determined an orientational sample size of n=15 and was followed by our preliminary study in which the root canals were retreated using Reciproc M-Wire, with the aim to evaluate the suitability of the determined sample size for identifying statistically significant differences between filing materials of 15% with a probability (statistical power) of 80% at a significance level of 0.05. This power analysis showed that a comparatively higher data variability obtained in our measurements compared to those from the article by Katunarić et al. (12) required increasing the sample size to n=30. Hence, this value was selected as a final sample size to be used in the study. To obtain n=30 by using 15 teeth per experimental group, both sides of the cross-sectioned specimens were used for the measurements. Due to the pronounced locality of residual material throughout the root canal and the amount of material removed in the process of sectioning and polishing, the two sides of the same canal were considered to be sufficiently unrelated to each other to be used in the statistical analysis as independent observations.

Sample Selection and Preparation

This study was approved by the Ethics Committee of the Faculty of Dentistry at the University of Zagreb (Zagreb, Croatia; 01-PA-35-29-14.1.2/2018). It was performed using 90 human teeth with oval, straight canals extracted for periodontal, orthodontic, or other health reasons that were immediately rinsed under tap water, cleaned of blood residues by immersion in a 3% hydrogen solution (Beyers GmbH; Mönchengladbach, Germany), and stored in a 0.5% chloramine solution (Stadt Apotheke; Gaggenau, Germany) until needed. The inclusion criteria were teeth with fully developed roots, no signs of external resorption or root caries, and no previous endodontic treatment. The soft tissue of the periodontal ligament and the calculus on the root surface were removed with manual curettes (ASA Dental; Bozzano, Brazil). Samples were cleaned and sterilized in an autoclave. Before being used for instrumentation and obturation, all teeth were trimmed to a length of 16 mm in order to establish a standardized working length of 15 mm. Then the markings for apical, middle, and cervical sections were made by dividing the working length into three parts (each 5 mm long). The root canal orifice was prepared with a diamond fissure drill No. 016 (Comet; Rock Hill, SC, USA) mounted on a turbine with water cooling. The dental pulp was removed with a pulp extirpator (Maillefer; Ballaigues, Switzerland). The length of each root canal was measured using an endodontic instrument, ISO 10 K-file (Maillefer), that was inserted into the canal up to the tip of the root and then pulled back 1 mm. The average canal length was 15 mm.

All 90 root canals were instrumented using a motor-driven Reciproc Gold device (VDW GmbH; Munich, Germany) and a Reciproc M-Wire instrument R40. During instrumentation, each root canal was rinsed with 2.5% sodium hypochlorite (NaOCl; Legeartis Pharma GmbH; Dettenhausen, Germany) using a 30G needle (BD Microlance; Becton Dickinson; Madrid, Spain) and 5 mL syringe. The residual layer was removed by rinsing the root canals with 1mL of 15% ethylenediaminetetraacetic acid (EDTA [Calcinase]; Legeartis) that was left inside the canal for 3 min. The canals were finally rinsed with 1 mL of 0.9% saline (NaCl; Braun; Melsungen, Germany) and dried with sterile R40 paper points (VDW GmbH). All endodontic procedures were performed by a single experienced operator in random order. Due to visually apparent differences and different handling properties of the sealers, the operator blinding was not possible. Only single-rooted teeth with round or oval canals were used to limit the heterogeneity of the root canal anatomy.

Obturation

The prepared samples were randomly divided into three experimental groups (n=30 each) that were filled with a Reciproc R40 gutta-percha (GP) point (VDW GmbH) and three different sealers during the retreatment procedure (Table1): AH Plus sealer (De Trey; Ballaignes, Switzerland) - AHP/GP; MTA Fillapex (Angelus; Londrina, Brazil) - MTAF/GP; BioRoot RCS (Septodont; Saint-Maur-des Fosses, France) - BRRCS/GP. All root canals were filled using a single cone technique. The filling materials were prepared according to the manufacturer’s instructions and entered the root canal with the master point gutta-percha point R40. Excess material was removed with a heated plugger 1mm below the root canal entrance, and the cavities were temporarily closed with Cavit (ESPE, Seefeld, Germany). Digital X-rays were recorded for homogeneity and lengths check of canal fillings. According to the manufacturers, the setting times of MTA Fillapex, Bio Root, and AH Plus amount to 2, 4, and 8 hours, respectively. To ensure the setting of hydraulic sealers in a moist environment (31), specimens were stored in an incubator at 37 °C and 100% humidity for seven days. The storage in a humidified incubator was performed according to the previous studies (32, 33).

Table 1. Composition of the three root canal sealers.

Root canal sealers	Manufacture	Composition
BioRoot RCS	Septodont (Saint-Maur-des Fosses, France)	Powder: tricalcium silicate, zirconium oxide, and povidone. Liquid: aqueous solution of calcium chloride and polycarboxylate.
MTA Fillapex	Angelus (Londrina, Brazil)	Base paste: salicylate resin, natural resin, calcium tungstate, nanoparticulated silica, and pigments. Catalyst paste: diluting resin, mineral trioxide aggregate (set), nanoparticulated silica, and pigments.
AH Plus	Dentsply (Konstanz, Germany)	Paste A: bisphenol-A epoxy resin, bisphenol-F epoxy resin, calcium tungstate, zirconium oxide, silica, and iron oxide pigments. Paste B: dibenzyldiamine, aminoadamantane, tricyclodecane-diamine, calcium tungstate, zirconium oxide, silica, and silicone oil.

Root canal retreatment

An R25 file with a taper of 0.08 over the first apical mm was used to remove filling material until a working length was reached, followed by an R40 file with a taper of 0.06 over the first apical mm (5). Reciproc M-Wire R25, followed by Reciproc R40 instruments (VDW GmbH; n=15) and Reciproc blue RB25, and Reciproc blue RB40 instruments (VDW GmbH; n=15), were used for root canal retreatment in all groups. Alternate rinsing was performed using NaOCl and EDTA and drying using standard paper points (size #40/0.04; VDW GmbH). The protocol was performed according to the manufacturer`s instructions (12). The retreatment was considered complete when there were no visible traces of filling material on the instruments, and the retreatment time was recorded. The total time required to remove the root fillings was measured from when the instruments were first applied in the canal until they regained apical patency. The stopwatch was started when the retreatment proceeded and stopped when the instrument was removed from the canal. Time to reach working length (T1) and that for complete gutta-percha removal and preparation to size 40 (T2) were recorded. Time for instrument changes and irrigation was excluded. Total working time was calculated by adding T1 and T2.

Stereomicroscope images

After retreatment, samples were placed in marked acrylic blocks and split longitudinally into two equal parts (Figure 1.), each consisting of three sections, apical, middle, and coronal. The length of each section was 5 mm. The samples were analyzed using a stereomicroscope (SZX12; Olympus; Tokyo, Japan) calibrated at 40 micrometers under a 15× magnification (Figure 2.). The areas of the residual filling material were measured using the Image J software (US National Institutes of Health; Bethesda, MD, USA).

Figure 1.

Specimens placed in marked acrylic blocks, and split longitudinally into two equal parts.

Figure 2.

The area of the entire root canal wall and residual filling material (BioRoot RCS) under a stereomicroscope (15x magnification).

Statistical analysis

Since the Shapiro-Wilk’s test indicated significant deviations from normality, a statistical analysis was performed using non-parametric tests. The values of the residual material surface were compared among three obturation materials using the Kruskal-Wallis test (a non-parametric equivalent of one-way ANOVA) followed by multiple comparisons with Bonferroni adjustment. The comparisons were performed separately for each instrument and each root canal section, as well as for the entire root canal. Analogously, retreatment time was compared among three obturation materials using the Kruskal-Wallis test with Bonferroni adjustment, separately for each instrument.

The effects of the retreatment instrument on residual material surface and retreatment time were evaluated by comparing the values measured for Reciproc Blue to those for Reciproc M-Wire using the nonparametric Mann-Whitney U test for independent observations, separately for each material. Additionally, the analysis of residual root canal surface was performed separately for each of the three root canal sections, as well as for the entire root canal. All analyses were performed at an overall significance level of 0.05, using the software SPSS (version 25; IBM, Armonk, NY, USA).

Results

Figure 3 shows percentages of root canal surfaces covered with residual material as a function of the root canal section, filling material, and instruments used in retreatment. For Reciproc Blue, no statistically significant differences in the residual material surface were found for any root canal section (p=0.162-0.823). In contrast, all sections of the root canal instrumented with Reciproc M-Wire had significantly higher residual material surface if previously obturated with AH Plus and MTA Fillapex compared to BioRoot RCS (p<0.001 for all root canal sections). At the same time, there was no significant difference between AH Plus and MTA Fillapex instrumented with Reciproc M-Wire.

Figure 3.

Percentages of root canal surface covered with residual material. The boxplots show the medians (bold black lines), the boxes represent the 25% and 75% quartiles, while the whiskers represent 1.5 × interquartile range (IQR), or minima and maxima of the distribution if below 1.5 × IQR. Outliers are presented by circles. For comparisons among retreatment instruments, arrows denote significantly higher (↑) or significantly lower (↓) values for Reciproc Blue compared to Reciproc M-Wire. Horizontal lines with asterisks (*) denote statistically significant differences among root filling materials. These differences were identified only for Reciproc M-Wire, while for Reciproc Blue all materials showed statistically similar values.

The pairwise comparisons between instruments showed that for AH plus residual material the surface was significantly lower for Reciproc Blue than for Reciproc M-Wire at the apical (p=0.030) and coronal (p=0.011) sections of the canal. The opposite was the case for BioRoot RCS, which showed a significantly higher residual material surface for Reciproc Blue at all canal sections (p<0.001). For MTA, the residual material surface was statistically similar for both instruments at all root canal sections.

Figure 4 shows retreatment time as a function of root canal filling material and retreatment instrument. Comparisons for retreatment time identified a statistically significant difference between MTA Fillapex and BioRoot RCS, while the direction of the difference differed between the instruments; Reciproc Blue took significantly longer to retreat BioRoot RCS than MTA Fillapex (p=0.005), while with Reciproc M-Wire, BioRoot RCS was re-treated significantly faster than MTA Fillapex (p=0.048). It should be noted that the latter difference was only marginally significant.

Figure 4.

Retreatment time as a function of root canal filling material and retreatment instrument. The boxplots show the medians (bold black lines), the boxes represent the 25% and 75% quartiles, while the whiskers represent 1.5 × interquartile range (IQR), or minima and maxima of the distribution if below 1.5 × IQR. Outliers are presented by circles. For comparisons among retreatment instruments, arrows denote significantly higher (↑) or significantly lower (↓) values for Reciproc Blue compared to Reciproc M-Wire. Horizontal lines with asterisks (*) denote statistically significant differences among root filling materials.

In comparisons for retreatment time between instruments, a significant effect was found only for BioRoot RCS, which took a significantly longer time to retreat with Reciproc Blue compared to Reciproc M-Wire (p<0.001).

Discussion

Our study showed that the retreatment ability of the two instrument types varied depending on the sealer used. While Reciproc Blue was more effective than Reciproc M-Wire in the retreatment of canals sealed with AH Plus, the opposite was the case for BioRoot RCS, for which Reciproc M-Wire was more effective. In the retreatment of MTA Fillapex, no statistically significant effect between the instruments was observed. When Reciproc M-Wire was used, the bioactive filler BioRoot RCS showed a better ability to be re-treated than the other two materials, as evidenced by a significantly lower amount of remaining material and a shorter retreatment time.

Significant differences were found between reciprocating files, with greater efficiency and fewer BioRoot RCS remnants with Reciproc M-Wire files (10%) compared to Reciproc blue files (18%) in the entire root canal. Consequently, we rejected our first null hypothesis. These results are consistent with the results of previous studies (25, 32, 34) and might be explained by the lower bond strengths of hydraulic sealers (4). However, AH Plus chemically interacts with root dentin collagen via covalent bonds between epoxy rings and the amine groups exposed in collagen (16). Moreover, its high flow ability and penetration in the dentine tubules prevent its removal from the root canal (17, 32), which is consistent with the sealer remnant and retreatment time findings of this study. However, contrary to our findings, more sealer remnants were found with hydraulic sealers than resin-based sealers in some previous studies (6, 35). Therefore, further studies are required to provide a definitive assessment.

Retreatment time with M-Wire reciprocating files was significantly faster than with Reciproc blue files for BRRCS/GP. Consequently, we rejected our second null hypothesis. The success of removing the old filling is closely related to the retreatment method (2). Differences in efficiency and duration of the retreatment procedure were recorded within the Reciproc technique. In previous research (28, 29), Reciproc blue showed significantly higher cyclic resistance as Reciproc and retreatment time was significantly lower for epoxy resin-based sealer compared with hydraulic sealers, which is not in accordance with this study.

With the development of Reciproc technology, a new chapter in endodontics has begun due to its simplicity. Moreover, the reciprocating motion shows good effectiveness in the retreatment procedure while keeping the file centered throughout the canal (15). This study showed that the greatest amount of remaining filling material was in the apical third of root canals, which is consistent with previous studies (36) and potentially reflecting the filling material lodging into the canal irregularities, thus making it difficult to remove during retreatment.

The Reciproc system includes Reciproc Gutta-Percha cones for use with the single-cone technique with apical sizes of #25, #40, and #50. In prior research, the obturation of straight root canals using reciprocating file-matched single cones was shown to result in a similar quality as that obtained with manual instrumentation followed by the lateral compaction technique (37). Single-cone filling is attractive from a clinical standpoint as it produces good results, while also being simpler and less time-consuming compared to other obturation techniques (38).

Only straight root canals were retreated in this study. Consequently, our findings cannot be specifically applied to the teeth with curved, ramified canals. The final apical preparation size R40 was based on the previous filling R40 because a re-instrumentation that is excessively wide might weaken the root and make it more prone to fractures, which should be avoided (18). Therefore, the preparation size of the primary treatment has not increased following the removal of the obturation material, potentially causing a greater volume of the residual filling material to remain in the apical third. Consequently, further studies are needed to evaluate the effect of canal retreatment with larger-sized instruments after the retreatment procedure to obtain better apical cleaning. The results of this study may vary from in vivo conditions based on the setting characteristics of the sealer in the root canal system. In this study, a stereomicroscope with its illumination and magnification of 15× was used to assess the remaining amount of filling material because it is sufficiently sensitive to measure the size of a small area of residual sealer/gutta-percha on the root canal walls, which were calculated using the Image J software for root thirds and the entire root canal. Therefore, regardless of the retreatment technique or the filling material used, a complete removal of the previous root filling has not yet been achieved (5, 7, 14).

Since the literature data on the retreatment ability of hydraulic sealers compared to epoxy resin-based sealer are inconclusive, the present study aimed to provide more insight into this topic by evaluating the amounts of remaining sealer on root canal walls and the time needed for retreatment. Donnermeyer et al. reported significantly greater amounts of remnants for an epoxy-based sealer (AH Plus) compared to a hydraulic sealer, as well as a longer retreatment time for the epoxy-based sealer, which is in accordance with this study (32). Crozeta et al. also reported less residual material for a hydraulic sealer compared to AH Plus (27). These results could be explained by the adhesion of epoxy resin-based sealer to dentin (16, 39), differences in quality of adaptation to root canal walls that is related to initial material flowability (e.g., AH Plus is more flowable than BioRoot RCS (40), as well as differences in the cohesive properties of the materials that affect the capability of reciprocal instruments to remove them from the root canal walls. In contrast, a study by Kim et al. showed that AH Plus sealer has retreatment characteristics comparable to those of a hydraulic sealer (41). The retreatment ability of the two instrument types in the present study varied depending on the sealer used. In this context, our results partly agree with a study by De-Deus et al., which showed similar effectiveness of Reciproc M-Wire and Reciproc Blue for removing filling materials from oval-shaped straight canals (42).

The comparability of results from different studies is made difficult by methodological differences regarding root canal selection (straight vs. curved canals), obturation techniques used, time period between obturation and retreatment, as well as instruments and methods used for retreatment. Some of these factors are likely to have interaction effects. For example, a particular type of sealant may not be generally easier to remove than another in all cases but particular instruments may be more effective for removing certain sealers and can be less effective for others. The same reasoning may be applied to different obturation techniques. Hence, the results of the present should be viewed considering the conditions under which the evaluation was performed, i.e., in straight, round to slightly oval canals that were retreated relatively early (7 days post-obturation), while avoiding extrapolations to other clinical scenarios.

It has been a known fact that hydraulic sealers are difficult to remove in retreatment procedures, which is probably due to their interaction with dentin (15–18), which results in a certain extent of chemical bonding (19). Since the post-setting maturation of sealers can occur slowly over an extended time period (43) and the kinetics of this process can be additionally modulated by multiple proprietary additives that are never completely disclosed by the manufacturers (44), the timing of the retreatment may be another important factor leading to differences in retreatment ability between hydraulic and epoxy resin-based sealers.

A limitation of the present study is the short period of 7 days between obturation and retreatment. Although this period is longer than the nominal setting times for all sealers as specified by the manufacturers (2-8 hours), the chemical changes in the sealers are known to continue beyond the initial setting and may have lasted longer than 7 days, thus improving both the cohesive strength of the sealers and their adhesion to dentin. Retreatment after 7 days may simulate the clinical scenario of "early revision" due to unsatisfactory obturation noted shortly after the completion of root canal treatment. However, for simulating the retreatment of late failures, longer time periods between obturation and revision are needed.

An additional limitation was the fact that the data in several experimental groups deviated significantly from normal distribution, which precluded the use of a full-factorial ANOVA with three factors (retreatment instrument, root canal sealer, and root canal section). Such an analysis would allow evaluation of the relative effect sizes for each factor and their possible interactions. Nevertheless, the nonparametric evaluation performed due to non-normal data distributions was able to identify the effects of individual factors that were compared and performed at fixed levels of other factors.

The main strength of this study was the simulation of a realistic clinical scenario in which retreatments were performed with reciprocating files commonly used for initial root canal treatment, rather than an idealized scenario in which specialized retreatment instruments (45) are used. This is similar to the situation in a general practice where the practitioner often has only a basic set of instruments available, resulting in "universal" instruments being used for multiple purposes (e.g., initial treatment and retreatment) rather than having multiple sets of instruments for specific purposes. An additional strength in terms of specimen standardization is the selection of only straight canals, with round to oval cross-sections, which helped reduce data variability, and the preparation of samples in random order to avoid bias due to the training curve and various extrinsic factors.

Conclusions

Removal of bioactive-based sealers with Reciproc M-Wire was better compared to AH Plus because fewer sealant residues were found in the root canals, and a shorter time was required to remove these two fillers compared to AH Plus. In contrast, Reciproc Blue was similarly effective for the retreatment of all three filler types tested. However, the sealers were not completely removed in any experimental group. Nevertheless, the type of sealant changed the amount of sealant remaining in the root canal system.

Clinical significance

The calcium silicate-containing sealers showed significantly fewer sealer remnants and shorter retreatment times than epoxy resin-based sealers.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.