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- Research Article Cleaning protocols to enhance bond strength of fiberglass posts on root canals filled with bioceramic sealer: an in vitro comparative study
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Thiago Bessa Marconato Antunes1
, Juliana Delatorre Bronzato1, Joice Graciani1, Ana Cristina Padilha Janini1, Rocharles Cavalcante Fontenele2, Francisco Haiter Neto2, Brenda Paula Figueiredo de Almeida Gomes1, Marciano Marina Angélica1,* -
Restor Dent Endod 2025;50(2):e20.
DOI: https://doi.org/10.5395/rde.2025.50.e20
Published online: May 21, 2025
1Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/ |er˭|I|-fGK.rΛp8XV1%K6mvG+tc+qE &ǸC_Nm:l=_/m5^[dߌڇ.c<%:)tQ$Ow~-aY;UJ >=F)2[nk؆?훐 M=l6[4(O.]2#-H^n#->&mp5~Fӛ+|| S,xag% qkEUzUgæBhߕP(7]kFnq?֖Cpru Z6*rEڊtS|*tI*E}7R<,nUU֫^I7Q*mSly%rdȓd8hE<9oHhMfNSRj[i7D[Rj݊+kდq{"$$H?p \̅S?㭻;t~ R߁ )^/>Qj`yt[w ԛ;² ~+ ߔ_ YW~|o] ?x^ᯛ `ʼn;g)T@vWn]>&4l p+$D̢1l|ȨF%-} .9[}w~
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2Department of Stomatology, Public Health, and Forensic Dentistry, Ribeirão Preto School of Dentistry, University of São Paulo (USP), Ribeirão Preto, São Paulo, Brazil JFIF d d Ducky d qhttp://ns.adobe.com/xap/1.0/ |er˭|I|-fGK.rΛp8XV1%K6mvG+tc+qE &ǸC_Nm:l=_/m5^[dߌڇ.c<%:)tQ$Ow~-aY;UJ >=F)2[nk؆?훐 M=l6[4(O.]2#-H^n#->&mp5~Fӛ+|| S,xag% qkEUzUgæBhߕP(7]kFnq?֖Cpru Z6*rEڊtS|*tI*E}7R<,nUU֫^I7Q*mSly%rdȓd8hE<9oHhMfNSRj[i7D[Rj݊+kდq{"$$H?p \̅S?㭻;t~ R߁ )^/>Qj`yt[w ԛ;² ~+ ߔ_ YW~|o] ?x^ᯛ `ʼn;g)T@vWn]>&4l p+$D̢1l|ȨF%-} .9[}w~
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- *Correspondence to Marina Angélica Marciano, DDS, PhD Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Areião, Piracicaba SP13414-903, Brazil Email: marinama@unicamp.br
• Received: February 4, 2025 • Revised: March 12, 2025 • Accepted: March 12, 2025
© 2025 The Korean Academy of Conservative Dentistry
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Abstract
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Objectives This study aimed to evaluate whether the agitation protocols using ultrasonic inserts or the XP-endo Finisher R file improved the removal of two different endodontic sealer remnants and the bond strength of fiberglass posts to dentin.
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Methods Seventy-two human teeth were selected. The canals were prepared with Reciproc 50 and Easy ProDesign 30/.10 and root filled according to the endodontic sealer groups: AH Plus or EndoSequence BC Sealer HiFlow. The samples were kept at 37ºC and 95% humidity for 28 days. During the post space preparation, the obturation was removed with Largo burs, and the groups were divided according to the irrigant agitation protocols (n = 12): no agitation, agitation with R1-Clearsonic associated with E1-Irrisonic ultrasonic inserts, or agitation with XP-endo Finisher R file. The fiberglass posts were cemented with RelyX ARC. The roots were sectioned into slices and submitted to the push-out test. Micro-computed tomography analysis was used to check the effectiveness of irrigating solution agitation in the elimination of remnants.
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Results The cleaning protocols with agitation were more effective in increasing the bond strength of posts to dentin for both sealer groups compared to non-agitation (p < 0.05). There was no difference between the same cleaning protocols for the different sealers. Among the different thirds, there was no statistical difference for the same sealer in the different cleaning protocols (p > 0.05).
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Conclusions Both agitation protocols effectively clean root-filled canals sealed with resin-based and calcium silicate-based sealers during fiberglass post space preparation. These protocols result in improved bond strength compared to non-agitation methods.
INTRODUCTION
Endodontically treated teeth often exhibit significant coronal destruction, requiring intraradicular retainers before coronal reconstruction [1]. Fiberglass posts are widely used due to their esthetic properties and favorable mechanical characteristics, such as an elastic modulus (18 GPa) similar to dentin (20 GPa). Additionally, their translucency allows light transmission into the canal, enhancing resin cement polymerization [2].
However, the bond strength of fiberglass posts can be affected by the type of endodontic sealer used for root canal filling. Some studies suggest that bioceramic sealers may compromise adhesion, advising against their use when post placement is required [3–8]. Research consistently reports that canals filled with bioceramic sealers exhibit lower bond strength compared to those obturated with epoxy resin-based sealers. This reduced adhesion is attributed to the interaction between calcium ions released by bioceramic sealers and phosphate ions in dentin, leading to the formation of apatite crystals and tag-like structures [9–11]. These mineral precipitates obstruct dentinal tubules, making their removal challenging using conventional endodontic techniques [12].
EndoSequence BC Sealer HiFlow (Brasseler USA, Savannah, GA, USA) is a ready-to-use bioceramic sealer that, according to the manufacturer, has low viscosity and greater radiopacity compared to its predecessor, BC Sealer. AH Plus (Dentsply Maillefer, Ballaigues, Switzerland), on the other hand, is a well-established epoxy resin-based sealer widely recognized for its excellent physicochemical properties [13]. Comparative studies indicate that BC HiFlow leaves fewer remnants after retreatment [14] and exhibits higher cell viability [15]. However, AH Plus has lower solubility compared to BC HiFlow [15].
To enhance fiberglass post retention after removal of root canal filling, ultrasonic agitation has been proposed as a cleaning strategy to eliminate residual sealer and improve dentin adhesion. The R2-Flatsonic ultrasonic insert (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) has shown promising results in increasing bond strength when resin-based sealers are used. However, its efficacy in removing bioceramic sealers remains uncertain [16]. Other instruments frequently used in obturation removal include the R1-Clearsonic and E1-Irrisonic ultrasonic inserts (Helse Ultrasonic), and the XP-endo Finisher R file (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which will be evaluated in this study.
The R1-Clearsonic ultrasonic insert provides mechanical action, scraping dentin walls to remove residual sealer [17]. The E1-Irrisonic insert facilitates irrigant agitation, enhancing fluid penetration into dentinal tubules [18]. Both inserts generate acoustic energy and vibration to break down mineral residues, potentially improving smear layer removal and hybrid layer formation for resin cement penetration.
The XP-endo Finisher R file is another promising alternative for removing residual root canal filling. This file assumes a serpentine shape upon activation, allowing it to stir the irrigating solution and reach complex anatomical areas. Studies indicate that it is more effective than ultrasonic inserts in removing bioceramic sealer [18–20]. Its MaxWire alloy composition enables an 8% taper expansion when transitioning from martensitic to austenitic phase at body temperature, improving its adaptability to irregular canal anatomy [18]. However, its impact on fiberglass post bond strength after sealer removal remains unclear.
Given these uncertainties, this study aimed to evaluate whether agitation protocols using ultrasonic inserts (R1-Clearsonic and E1-Irrisonic) or the XP-endo Finisher R file improve the removal of residual endodontic sealers (bioceramic and resin-based) and enhance the bond strength of fiberglass posts to dentin after cementation.
METHODS
The sample size was justified through the sample calculation based on the previous methodologies by Özcan et al. [21] and Soares et al. [7]. The G*Power ver. 3.1 program for Mac (Heinrich Heine University Dusseldorf, Germany) was used to compare more than two means with independent groups (analysis of variance, ANOVA), with a total of three groups, with an alpha error (α) of 0.05, a beta power (β) of 0.80, a standard deviation estimates of 2.53, and a minimum difference to be detected at the value of 6.90. Twelve samples per group were indicated as the ideal size required.
The approval of the Human Ethics Committee of the Piracicaba Dental School (FOP/Unicamp) (CAAE: 30059020.9.0000.5418) was obtained before starting the research. This study used 72 single-rooted maxillary incisor teeth. The teeth were radiographed using a digital sensor on the mesiobuccal and buccolingual planes to check the degree of curvature. Inclusion criteria: teeth with a curvature of at most 5° according to Schneider’s classification, single-rooted teeth with a single canal according to Vertucci’s classification, and teeth with fully formed apices. Teeth with endodontic treatment, internal or external reabsorptions, root caries, cracks, and/or calcifications were excluded from the research [22].
The teeth were cleaned, and the crown was removed from the cementoenamel junction using a water-cooled diamond disc (Isomet100 PrecisionSaw; Buehler Ltd., Lake Bluff, IL, USA), leaving approximately 15 mm of root. The root canal cervical preparation was carried out with a 30./10 file at 6 mm from the apex (Easy ProDesign S; Easy Equipamentos Odontológicos, Belo Horizonte, Brazil) in continuous rotation at a speed of 950 revolutions/min (rpm) and torque of 4 Ncm mounted on a VDW Silver motor (VDW GmbH, Munich, Germany). The Reciproc file system in sequence R25, R40, and R50 instrumented the entire canal length at the foramen level and operated in “Reciproc all” mode using the same motor. During instrumentation, the canals were irrigated with a solution of 2.5% sodium hypochlorite (NaOCl) using a 30-gauge needle (NaviTip; Ultradent Products Inc., South Jordan, UT, USA) for a total of 10 mL in the whole irrigation. For this purpose, a layer of sticky wax was applied to the apical foramen to prevent liquid from leaking out of the canal. At the end of the instrumentation, passive ultrasonic irrigation was performed using the E1-Irrisonic insert mounted on a Newtron Booster ultrasonic device (Acteon North America, Mount Laurel, NJ, USA) at 30% power. The agitation was carried out at 2 mm short of the working length, where it was applied 2 mL of 2.5% NaOCl was applied into the root canal for three cycles of 20 seconds, totaling 6 mL and 1 minute. Soon after that, the same process was performed for ethylenediaminetetraacetic acid (EDTA) 17% and then with hypochlorite again. Finally, 5 mL of distilled water was introduced into the root canal for the final wash, and the canal was dried with absorbent Reciproc R50 paper points (VDW GmbH).
The root was randomized and distributed in two groups (n = 36) according to the sealer used in the canal filling, either EndoSequence BC Sealer HiFlow or AH Plus. Table 1 displays the components of the endodontic sealers.
Single cone was the technique used for the obturation, and the sealers were prepared according to the manufacturer’s instructions. R50 gutta-percha points were coated with the sealer and inserted into the canal with apical pressure until reaching the working length. Posteriorly, the heated condenser cut the gutta-percha, and other cold condensers vertically condensed the filling material. The roots were kept at 37ºC and 95% humidity for 28 days to ensure a complete bioceramic set.
After this period, the filling material was removed from the 15 mm-long canals using Largo burs corresponding to No. 1 Exact Pin Kit (Angelus, Londrina, Brazil), leaving 4 mm of gutta-percha in the apical third. A periapical radiograph was taken to confirm the complete removal of the filling material from the dentinal walls.
At this time, the root was randomized and subdivided into three groups (n = 20) corresponding to the cleaning protocol after root filling removal: group 1, ultrasonic agitation using R1-Clearsonic followed by E1-Irrisonic; group 2, agitation with XP-endo Finisher R; and group 3, no agitation. The cleaning sequence for each group was the following [18]:
Group 1 (US): The R1-Clearsonic tip mounted on a Newtron Booster ultrasonic device was used to remove and scrape clinging filling material in the dentinal wall of canals immersed with 2.5% NaOCl. After this process, the E1-Irrisonic tip, inserted 0.5 mm from the apical gutta-percha filling, and agitated 1 mL of this same solution for 30 seconds. Both the tips were set at power 1. Then, 5 mL of NaOCl washed the entire canal. After this, E1-Irrisonic agitated 1 mL of 17% EDTA for 30 seconds, and then the canal was washed with 5 mL of the same solution. In the next step, 1 mL of 2.5% NaOCl was agitated for 30 seconds according to the previous protocol. Finally, irrigation with 5 mL of distilled water concluded the cleaning of the canal.
Group 2 (XP): The XP-endo Finisher R file was coupled to a VDW Silver motor and operated in continuous rotation at a speed of 800 rpm with a torque of 1 Ncm inserted 0.5 mm from the apical gutta-percha filling. The file was agitated with 1 mL of 2.5% NaOCl, which was inserted into the root canal for 30 seconds. Then, 5 mL of NaOCl washed the entire canal. After this, the file was agitated with 1 mL of 17% EDTA for 30 seconds, and then the canal was washed with 5 mL of the same solution. In the next step, 1 mL of 2.5% NaOCl was agitated for 30 seconds according to the previous protocol. Finally, irrigation with 5 mL of distilled water concluded the cleaning of the canal.
Group 3 (control): A volume of 5 mL of 0.9% saline solution irrigated the canals without any agitation protocol using a 5 mL irrigation syringe and a 30-gauge NaviTip at 0.5 mm from the apical gutta-percha filling.
Cleaning efficiency was evaluated by micro-computed tomographic (micro-CT) images. For this quantitative analysis, five teeth from each group were selected and scanned after root filling removal and after the established cleaning protocols using a micro-CT device, the SkyScan 1174 (Bruker microCT, Kontich, Belgium). The scanning parameters were standardized as follows: 50 kV, 800 µA, 23.2-µm voxel side, 0.5-mm aluminum filter, and rotation steps of 0.7 and 3 frames. All scans were reconstructed with NRecon software (ver. 1.6.9; Bruker microCT) using the following parameters: smoothing level of 5, ring artifact correction of 6, and 30% of beam-hardening correction. Afterward, the alignment of the scans of each tooth acquired after root filling removal and after the cleaning protocol was performed using the 3D registration tool in Data Viewer software (Data Viewer ver. 1.5.1; Bruker microCT). Finally, the volume (mm3) of the filling remnant was quantified with the CTAn software (ver. 1.13; Bruker microCT) using a standardized threshold of gray values that allowed to distinguish of the root dentin from the filling remnant material.
For the post cementation, 37% phosphoric acid etched the post space for 15 seconds, and 5 mL of distilled water rinsed the canal for 30 seconds. Then, absorbent paper points dried the entire dentinal walls. The adhesion was performed using the Scotch Bond Multipurpose system (3M ESPE, St. Paul, MN, USA). Initially, the activator was applied into the canal with a microbrush, followed by the removal of excess with a paper point. The same process was carried out with the primer and catalyst. For the fiberglass post conditioning, 37% phosphoric acid was applied to the fiberglass post for 15 seconds and rinsed with distilled water. Sequentially, the post received a silane layer (Ultradent Products Inc.) using a microbrush. The RelyX ARC dual resin cement (3M ESPE) was handled, following the manufacturer’s instructions, and taken to the Centrix-type syringe system (DFL, Rio de Janeiro, Brazil) to be applied inside the canal. Then, the post was inserted, adapted, and pressed for 20 seconds into the canal. The excess material on the root surface was removed. At the end, a Valo light curing unit (Ultradent Products Inc.) photopolymerized the system for 40 seconds. Each root was inserted into an individual Eppendorf tube containing moistened cotton at the base and labeled according to the corresponding group. The moistened cotton was used to maintain humidity and prevent dentin dehydration, avoiding potential bias in the push-out bond strength tests. The Eppendorf tubes were kept at 37ºC for 5 days. Table 2 summarizes the cleaning and cementation protocol for the posts.
The 5-day-old samples were cut into three slices with a 1-mm thickness, each corresponding to one-third of the root canal (cervical, middle, and apical), using a water-cooled diamond disc. In sequence, the sample slice was positioned on the universal testing machine (Instron 4411; Instron, Norwood, MA, USA) with a 0.5-mm diameter metal rod positioned in the center of the fiberglass post, applying mechanical load in a crown-to-apex direction at a speed of 0.5 mm/min until the post displacement from the root slice. This loading was quantified in newtons (N). To calculate the area of the truncated cone, the following formula was used: A = π (R + r) √h2 + (R − r)2. R is the radius of the coronal portion; r is the radius of the apical portion; and h is the height of the slice. The bond strength was calculated by dividing the force in N by the area in mm2 and expressed in megapascals (MPa).
The failure mode after the push-out test was evaluated using a stereomicroscope (LEICA MZ7.5; Leica Microsystems, Wetzlar, Germany) under 50× magnification. The fractures were classified as adhesive between dentin and cement, adhesive between post and cement, cohesive into dentin, cohesive into fiberglass post, cohesive into cement, or mixed failure.
A root from each group was selected to obtain an extra slice to analyze the adhesive interface and nanoleakage. For this test, the slice of each group was immersed in ammoniacal silver nitrate solution in an Eppendorf tube covered with aluminum foil for 24 hours at 37ºC. After this time, the slices were rinsed with distilled water for 1 minute. Then, in other labeled Eppendorf tubes, containing 1 mL of developer solution, the sections were immersed and kept under fluorescent light for 8 hours. Next, the slices were rinsed with distilled water irrigation for 1 minute and embedded in epoxy resin to make stubs. After inclusion and resin polymerization, the stubs were polished with constant irrigation in the order of sandpaper 600 for 4 minutes, 1000 for 5 minutes, and 2000 for 5 minutes, respectively. At each sandpaper change, the stubs were cleaned in an ultrasonic vat with distilled water for 5 minutes. Sequentially, the stubs were polished with a felt disk, applying a small proportion of 1-µm diamond paste for 2 minutes. Finally, the stub was cleaned in an ultrasonic vat for 10 minutes. After polishing and dehydration, double-sided carbon tapes were glued to one side of the stubs, which were then subjected to carbon coverage and evaluated in a scanning electron microscope (SEM; JSM-5600LV, JEOL Ltd., Tokyo, Japan) at magnifications of ×270.
Statistical analyses were performed using JASP software (University of Amsterdam, Amsterdam, The Netherlands), ver. 0.14.1.0 (2021). A mixed ANOVA (considering both within- and between-subject effects) was conducted. The assumptions of normality and sphericity were assessed using the Shapiro-Wilk and Levene tests, respectively. When significant differences were found, the Tukey post-hoc test was applied for multiple comparisons. A significance level of 5% (p < 0.05) was adopted for all statistical tests.
RESULTS
There was no statistical difference between HiFlow and AH Plus sealers for the same cleaning protocols (p > 0.05). The ultrasonic and XP agitation groups did not show a statistical difference for canals obturated with AH Plus (p > 0.05). However, in the AH Plus group, both ultrasonic and XP agitation achieved higher bond strength than irrigation with saline solution during post preparation (p < 0.05). The ultrasonic and XP agitation groups did not show a statistical difference for canals obturated with HiFlow (p > 0.05). Both the US and XP groups achieved higher bond strengths compared to the saline irrigation group in the canals obturated with HiFlow (p < 0.05) (Table 3).
In micro-CT, there was no statistical difference between the different types of sealers for the same cleaning protocol. Only for the HiFlow group was a statistical difference observed in the removal of remnants after the cleaning protocol with ultrasonic tips (p = 0.03) (Table 4). The failure mode analysis indicated mostly mixed failures after the push-out analysis (Figure 1).
SEM images showing the post-cement dentin-cement line of the AH Plus and HiFlow groups and their respective cleaning subgroups are shown in Figure 2.
The agitation effect in cleaning the remnants adhered to the dentin wall after the root canal filling removal protocol is represented in Figure 3.
DISCUSSION
Endodontic sealer type has been found to influence the bond strength of fiberglass posts to root dentin [6,21,23]. Based on that, this study assessed the agitation effect of the irrigating solution after post space preparation on bond strength. This is the first study in the literature to assess this objective using the HiFlow bioceramic sealer and agitating with the Clerasonic/Irrisonic inserts and XP-endo Finisher R file.
The push-out test was used to evaluate bond strength. This test is frequently used in endodontics to evaluate the bond strength of root canal posts. The key advantage over different tests, such as the microtensile technique, is the presence of material within the canal surrounded by dentin [24]. Furthermore, the push-out test evaluates bonding throughout different canal regions and thirds [21].
In the current investigation, cleaning the root canals using an ultrasonic tip or an XP-endo Finisher R file resulted in a stronger bond strength than the control group in both canals filled with AH Plus and HiFlow. The XP-endo Finisher R file is extremely flexible and whips when inserted into the canals and exposed to body temperature. The file forms a sickle shape and presses against the dentin walls, causing the irrigation solution to spout into the dentinal tubules. This technique allows the tip file to whip to scrape the dentin wall, displacing adherent fragments [18,20,23]. Because of the agitation during cleaning, the XP file allowed for deep penetration of the resin cement into the dentin, resulting in a high bond strength. There were no statistical differences in bonding strength between canal thirds.
Cleaning with ultrasonic inserts also resulted in greater bond strength values and effective agitation and cleaning, which differed significantly from the control group. The Irrisonic does not come into contact with the canal walls; instead, it works through vibration and acoustic transmission to spout the solution into the canal wall by cavitation and acoustic flow, which splits material off the walls [23]. However, the Clearsonic tip works directly and mechanically, scraping the remaining material from the dentin wall with its arrow-shaped tip [17]. The combination of Irrisonic and Clearsonic was shown to improve cleaning while also allowing resin cement to adhere to and penetrate dentin more effectively.
Although there was no statistical difference, HiFlow sealer had lower bond strength values than AH Plus. The literature [21,25,26] found similar results. Other studies that did not use ultrasonic cleaning found lower bioceramic sealer bond strength values than AH Plus [3,5,6,8]. Furthermore, similar experiments employing an ultrasonic insert to clean the post area demonstrated that AH Plus had a stronger bond strength than a bioceramic sealer [16]. Except for one study [27], which reported a greater result for iRoot SP (Innovative BioCeramix Inc., Vancouver, BC, Canada) in comparison to AH Plus.
While there was no statistical difference between AH Plus and HiFlow in this study, the literature indicates that resin-based cements have superior bond strength due to their similar composition to resin and the absence of components that affect polymerization [28]. Additionally, epoxy resin does not interfere with the free radicals that initiate the polymerization of composite resins [7].
HiFlow was chosen because it is a bioceramic sealer with a higher flow rate, which could show the effectiveness of agitation protocols to remove them from the dentinal tubules. Bioceramic sealers are harder to remove from canals [12]. In contact with dentin moisture, they release calcium hydroxide that binds to phosphates in the dentinal fluid and forms lath-like apatite crystals [9–11], which adhere to the dentin mineral and precipitate in the dentinal tubule [9,29], making removal difficult. In addition to crystal formation, the calcium hydroxide release creates an alkaline environment that reduces the effectiveness of acid etching, resulting in a weak hybrid layer with a resinous tag [6,7].
According to micro-CT analysis, the HiFlow ultrasonic group showed greater remaining removal after cleaning protocols than the XP group, owing to the combined efficiency of the two inserts, making it an alternative to removing bioceramic sealers from the wall canal. This is consistent with the literature [23], which demonstrated that the ultrasonic insert removed the remaining material from the canal better than the XP instrument. Both agitation groups for HiFlow and AH Plus sealers showed a significant reduction in remnants, demonstrating that the ultrasonic group had a higher cleaning percentage. This micro-CT analysis allowed us to conclude that agitation of the irrigant solution is suggested for post space preparation. In root canal retreatment, some authors [18–20] found that the Irrisonic insert eliminated fewer remains from the canal than the XP file. In contrast, another study [23] showed that the ultrasonic insert removed the most remains when compared to the XP file.
Our study was the first to apply the nanoleakage methodology with an ammoniacal silver nitrate solution to measure cementation density in SEM using backscattered electrons (BSE), which is more accurate than secondary electrons. In SEM, the post-cement-dentin interface cementation is shown hermetically, with no bubbles evident. The round bundles illustrate fiberglass that has been wrapped in epoxy resin (black). The cement line depicts the inorganic zirconia and silica particles that are covered by the bisphenol A-glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) organic matrix. The black rays from the cement show the adhesive that has penetrated the dentinal tubules, indicating a high level of adhesion. White spots in the cement-dentin interface indicate gaps filled with silver particles. All groups show good adherence. However, there is a thicker adhesive layer for groups with agitation, particularly the AH Plus group. Furthermore, the HiFlow sealer no-agitation group contains voids filled with silver particles, represented by white rays, indicating a failure in adhesive adherence and penetration.
Regarding the failure mode, the highest frequency was the mixed type. This can be explained by the sum of the failure types. Cohesive failures could be invisible during push-out test execution, and the remaining endodontic sealer influences adhesive failures, especially those of cement-dentin. Adhesive failure between cement and dentin, only, was the least observed. The post-cement adhesive failure was the second most observed failure type and was the most frequent in other work [6]. The difference from the literature may be attributed to the use of silane in our study, which the authors did not use.
The limitation of this study includes the variability in root canal anatomy, with some being more flattened and others being more irregular. Besides the attempt to standardize as closely as possible to each other, this was not totally possible. Furthermore, despite the advantages of the push-out test, it does not show the true clinical situation, making it difficult to draw definitive conclusions from the study [30].
The findings of this study have significant clinical implications for root canal cleaning after the removal of filling material for fiber post preparation. The use of ultrasonic instruments and the XP-endo Finisher R proved effective in reducing intracanal residues, creating a cleaner and more suitable surface for adhesion, which may enhance the cementation of resin-based cements.
CONCLUSIONS
Both agitation protocols using the XP-endo Finisher file or Clearsonic combined with Irrisonic ultrasonic inserts effectively clean root-filled canals sealed with resin-based and calcium silicate-based sealers during fiberglass post space preparation. These protocols result in improved bond strength compared to non-agitation methods.
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CONFLICT OF INTEREST
No potential conflict of interest relevant to this article was reported.
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FUNDING/SUPPORT
This study was supported by the State of São Paulo Research Foundation (FAPESP; 2021/11992-0 and 2021/07920-4). This study was also financed in part by the Coordination for the Improvement of Higher Education Personnel (CAPES) – Finance Code 001.
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AUTHOR CONTRIBUTIONS
Conceptualization: Marciano MA, Antunes TBM. Data curation: Antunes TBM, Fontenele RC. Formal analysis: Bronzato JD, Marciano MA, Janini ACP. Funding acquisition, Supervision: Marciano MA. Investigation: Graciani J. Methodology: Graciani J, Antunes TBM. Project administration, Validation: Marciano MA, Gomes BPFA. Software: Fontenele RC, Janini ACP. Visualization: Marciano MA, Gomes BPFA, Haiter Neto F. Writing - original draft: Antunes TBM. Writing - review & editing: Marciano MA, Bronzato JD, Haiter Neto F. All authors read and approved the final manuscript.
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DATA SHARING STATEMENT
The datasets are not publicly available but are available from the corresponding author upon reasonable request.
Figure 1.
Failure mode analysis indicating mostly mixed failures after the push-out analysis. Symbols (*, #) indicate the significance between failures within the tested sealer. AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. RelyX: RelyX ARC; 3M ESPE, St. Paul, MN, USA. XP-endo: XP-endo Finisher R file; FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Figure 2.
Scanning electron microscope images (250× and 15 kV) indicating the middle third adhesive interface of each sealer group and agitation subgroup. Yellow arrows indicate the glass fibers around the epoxy resin. Black arrows indicate the cement line. White arrows indicate adhesive penetration into the dentin. AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Clearsonic and Irrisonic: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil. XP-endo Finisher R: FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Figure 3.
Representative micro-computed tomographic images showing remaining materials before and after cleaning with ultrasonics and the XP-endo Finisher R (FKG Dentaire, La Chaux-de-Fonds, Switzerland). AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Clearsonic and Irrisonic: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil.
Table 1.
Composition of AH Plus and EndoSequence HiFlow sealers
Table 2.
Summary of the cleaning and cementation protocol
EDTA, ethylenediaminetetraacetic acid; NaOCl, sodium hypochlorite; US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file.
Centrix-type syringe system: DFL, Rio de Janeiro, Brazil. E1-Irrisonic and R1-Clearsonic tips: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil. NaviTip and Valo curing light: Ultradent Products Inc., South Jordan, UT, USA. RelyX ARC and Scotchbond Multipurpose: 3M ESPE, St. Paul, MN, USA. XP-endo Finisher R file: FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Table 3.
The bond strength (Mpa) of the total of all thirds for each cleaning protocol and sealer type
Values are presented as mean ± standard deviation.
US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file (FKG Dentaire, La Chaux-de-Fonds, Switzerland).
AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA.
Different capital letters in the same column indicate statistical differences for the same sealer among different cleaning protocols (p < 0.05). Different lowercase letters in the same line indicate the absence of statistical differences among different sealers for the same type of cleaning protocol (p > 0.05).
Table 4.
The remaining material volume (mm3) in the root canals after obturation and after cleaning
Values are presented as mean ± standard deviation.
US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file (FKG Dentaire, La Chaux-de-Fonds, Switzerland).
AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA.
Different uppercase letters mean statistical differences for the same type of sealer and cleaning protocol (p < 0.05). Different lowercase letters indicate a statistically significant difference for the same sealer among the different cleaning protocols (p < 0.05).
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XML DownloadCleaning protocols to enhance bond strength of fiberglass posts on root canals filled with bioceramic sealer: an in vitro comparative study
Figure 1. Failure mode analysis indicating mostly mixed failures after the push-out analysis. Symbols (*, #) indicate the significance between failures within the tested sealer. AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. RelyX: RelyX ARC; 3M ESPE, St. Paul, MN, USA. XP-endo: XP-endo Finisher R file; FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Figure 2. Scanning electron microscope images (250× and 15 kV) indicating the middle third adhesive interface of each sealer group and agitation subgroup. Yellow arrows indicate the glass fibers around the epoxy resin. Black arrows indicate the cement line. White arrows indicate adhesive penetration into the dentin. AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Clearsonic and Irrisonic: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil. XP-endo Finisher R: FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Figure 3. Representative micro-computed tomographic images showing remaining materials before and after cleaning with ultrasonics and the XP-endo Finisher R (FKG Dentaire, La Chaux-de-Fonds, Switzerland). AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Clearsonic and Irrisonic: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil.
Figure 1.
Figure 2.
Figure 3.
Cleaning protocols to enhance bond strength of fiberglass posts on root canals filled with bioceramic sealer: an in vitro comparative study
| Cement | Batch | Composition |
|---|---|---|
| EndoSequence BC Sealer HiFlow (Brasseler USA, Savannah, GA, USA) | 1901SPWF | Tricalcium silicate, dicalcium silicate, calcium hydroxide, zirconium oxide, and fillers |
| AH Plus (Dentsply Maillefer, Ballaigues, Switzerland) | 1810000183 | Paste A: Epoxide paste: bisphenol-A epoxy resin, bisphenol-F epoxy resin, calcium tungstate, zirconium oxide, aerosol, and pigment |
| Paste B: 1-adamantane amine N, N’-dibenzyl-5-oxa-nonandiamine-1,9TCD-Diamine, calcium tungstate, zirconium oxide, aerosol, and silicone |
| Group | Cleaning protocol | Fiber post cementation |
|---|---|---|
| Control | • 5 mL of 0.9% saline solution irrigated the canals without any agitation protocol using a 5-mL irrigation syringe and a 30-gauge NaviTip at 0.5 mm from the apical gutta-percha filling. | • Step 1: 37% phosphoric acid etched the post space for 15 seconds, and 5 mL of distilled water rinsed the canal for 30 seconds. |
| • Step 2: absorbent paper points dried the entire dentinal walls. | ||
| • Step 3: The activator (Scotch Bond Multipurpose system) was applied into the canal with a microbrush, followed by the removal of excess with a paper point. | ||
| • Step 4: The same process (step 3) was carried out with the primer and catalyst. | ||
| • Step 5: 37% phosphoric acid was applied to the fiberglass post for 15 seconds and rinsed with distilled water. | ||
| • Step 6: the post received a silane layer. | ||
| US | • Step 1: R1-Clearsonic tip was used to remove and scrape clinging filling material in the dentinal wall of canals immersed with 2.5% NaOCl. | • Step 7: The RelyX ARC dual resin cement was handled and taken to the Centrix syringe system to be applied inside the canal. |
| • Step 2: E1-Irrisonic tip, inserted 0.5 mm from the apical gutta-percha filling, agitated 1 mL of this same solution for 30 seconds. Then, 5 mL of NaOCl washed the entire canal. | • Step 8: the post was inserted, adapted, and pressed for 20 seconds into the canal. The excess material on the root surface was removed. At the end, a Valo light curing unit (Ultradent Products) photopolymerized the system for 40 seconds. | |
| • Step 3: E1-Irrisonic agitated 1 mL of 17% EDTA for 30 seconds, and then the canal was washed with 5 mL of the same solution. | ||
| • Step 4: E1-Irrisonic agitated 1 mL of 2.5% NaOCl for 30 seconds according to the previous protocol. | ||
| • Step 5: irrigation with 5 mL of distilled water concluded the cleaning of the canal. | ||
| XP | • Step 1: XP-endo Finisher R file agitated 1 mL of 2.5% NaOCl inserted into the root canal for 30 seconds. Then, 5 mL of NaOCl washed the entire canal. | |
| • Step 2: XP-endo Finisher R agitated with 1 mL of 17% EDTA for 30 seconds, and then the canal was washed with 5 ml of the same solution. | ||
| • Step 3: XP-endo Finisher R agitated 1 mL of 2.5% NaOCl for 30 seconds according to the previous protocol. | ||
| • Step 4: irrigation with 5 mL of distilled water concluded the cleaning of the canal. |
| Cleaning | AH Plus |
HiFlow |
AH Plus | HiFlow | ||||
|---|---|---|---|---|---|---|---|---|
| Cervical | Middle | Apical | Cervical | Middle | Apical | Total | Total | |
| No agitation | 8.35 ± 1.86 | 8.80 ± 2.66 | 7.91 ± 2.84 | 7.46 ± 2.20 | 7.71 ± 2.18 | 6.41 ± 2.28 | 8.35 ± 0.57Aa | 7.19 ± 0.05Aa |
| US | 13.49 ± 3.27 | 11.31 ± 2.14 | 10.37 ± 2.86 | 12.22 ± 6.18 | 11.12 ± 5.59 | 8.10 ± 3.40 | 11.72 ± 0.44Ba | 10.48 ± 1.40Ba |
| XP | 13.22 ± 5.16 | 13.37 ± 8.17 | 10.92 ± 5.94 | 13.25 ± 5.04 | 11.41 ± 3.76 | 9.80 ± 3.80 | 12.50 ± 1.19Ba | 11.49 ± 0.70Ba |
| Cleaning | AH Plus |
HiFlow |
||
|---|---|---|---|---|
| After filling removal | After cleaning | After filling removal | After cleaning | |
| US | 0.95 ± 0.71Aa | 0.03 ± 0.03Aa | 1.56 ± 0.43Aa | 0.16 ± 0.36Ba |
| XP | 1.9 ± 1.89Aa | 1.12 ± 1.12Aa | 3.0 ± 1.53Aa | 2.2 ± 1.58Ab |
Table 1. Composition of AH Plus and EndoSequence HiFlow sealers
Table 2. Summary of the cleaning and cementation protocol
EDTA, ethylenediaminetetraacetic acid; NaOCl, sodium hypochlorite; US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file. Centrix-type syringe system: DFL, Rio de Janeiro, Brazil. E1-Irrisonic and R1-Clearsonic tips: Helse Ultrasonic, Santa Rosa de Viterbo, Brazil. NaviTip and Valo curing light: Ultradent Products Inc., South Jordan, UT, USA. RelyX ARC and Scotchbond Multipurpose: 3M ESPE, St. Paul, MN, USA. XP-endo Finisher R file: FKG Dentaire, La Chaux-de-Fonds, Switzerland.
Table 3. The bond strength (Mpa) of the total of all thirds for each cleaning protocol and sealer type
Values are presented as mean ± standard deviation. US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file (FKG Dentaire, La Chaux-de-Fonds, Switzerland). AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Different capital letters in the same column indicate statistical differences for the same sealer among different cleaning protocols (
Table 4. The remaining material volume (mm3) in the root canals after obturation and after cleaning
Values are presented as mean ± standard deviation. US, experimental group using an ultrasonic irrigation protocol; XP, experimental group based on the XP-endo Finisher R file (FKG Dentaire, La Chaux-de-Fonds, Switzerland). AH Plus: Dentsply Maillefer, Ballaigues, Switzerland. HiFlow: EndoSequence BC Sealer HiFlow; Brasseler USA, Savannah, GA, USA. Different uppercase letters mean statistical differences for the same type of sealer and cleaning protocol (
