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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 11  |  Issue : 1  |  Page : 42-48

Retreatability of bioceramic and GuttaFlow bioseal root canal sealers using ProTaper universal system retreatment files: An Ex vivo study


1 Department of Endodontic, Eastern Riyadh Dental Center, Riyadh, Saudi Arabia
2 Department of Restorative Dentistry, Riyadh Elm University; Quality Assurance and Accreditation Center, Riyadh Elm University, Riyadh, Saudi Arabia

Date of Submission20-Nov-2019
Date of Decision23-Dec-2019
Date of Acceptance16-Feb-2020
Date of Web Publication09-Jan-2021

Correspondence Address:
Dr. Yousef Al-Dahman
Department of Endodontic, Qassim Regional Dental Center, P.O. Box: 30254, Buraydah 51477
Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sej.sej_173_19

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  Abstract 


Introduction: To evaluate the retreatability of Bioceramic and GuttaFlow Bioseal sealers using ProTaper Universal System Retreatment files aided by dental microscope analysis.
Materials and Methods: Root canals of forty single-rooted human mandibular premolar teeth were prepared with ProTaper Next rotary system and obturated with single-cone obturation technique (n = 20 each) using EndoSequence Bioceramic root canal sealer (Group 1) and GuttaFlow Bioseal root canal sealer (Group 2). All specimens were retreated with ProTaper Universal Retreatment System files. The working time of retreatment procedure was calculated. Samples were sectioned, and the residual filling remnants were observed under dental operating microscope. Statistical analysis was performed using SPSS software.
Results: The least total working time was observed in GuttaFlow Bioseal group (2.35 min). Overall, less residual filling materials was found in Bioceramic sealer group specimens in all root levels compared to GuttaFlow Bioseal group (P = 0.000, 0.022, and 0.000, respectively).
Conclusion: The retreatment technique used was incapable of complete removal of filling material within root canal walls.

Keywords: Bioceramic sealer, dental microscope, GuttaFlow Bioseal sealer, gutta-percha, root canal retreatment


How to cite this article:
Al-Dahman Y, Al-Omari M. Retreatability of bioceramic and GuttaFlow bioseal root canal sealers using ProTaper universal system retreatment files: An Ex vivo study. Saudi Endod J 2021;11:42-8

How to cite this URL:
Al-Dahman Y, Al-Omari M. Retreatability of bioceramic and GuttaFlow bioseal root canal sealers using ProTaper universal system retreatment files: An Ex vivo study. Saudi Endod J [serial online] 2021 [cited 2021 Apr 15];11:42-8. Available from: https://www.saudiendodj.com/text.asp?2021/11/1/42/306602




  Introduction Top


The objective of root canal treatment is to remove inflamed or diseased tissue from root canal system and place a filling in order to prevent reinfection.[1] However, 15%–22% of the treatment could fail due to different reasons.[2]

In such cases, nonsurgical root canal retreatment is the best option to manage posttreatment disease. Retreatment consists of the removal of the existing root canal obturation material to allow disinfection of the root canal system through a biomechanical cleaning followed by placement of good biocompatible filling to provide a suitable environment for periradicular healing.[3]

Root canal obturation aids in blocking the movement of fluids from the periradicular tissues or saliva into the canal system as well as bacteria and their by-products from the canal to the periradicular tissues.[4]

The combination technique of using root canal sealer in conjunction with gutta-percha core material remains the most widely accepted obturation technique in endodontics. Since the lack of adhesion of gutta-percha to the canal walls, a sealer is primarily used to fill the irregularities between them as well as the lateral or accessory canals and bond the gutta-percha and dentin.[4]

Grossman listed the basic requirements for an ideal root canal sealer. One of the requierement is to be soluble in a common solvent in case of the need to remove the root canal filling.[5]

EndoSequence Bioceramic root canal sealer (Brasseler USA, Savannah, GA, USA) was introduced in the market a few years ago. It is a premixed bioceramic endodontic sealer with good biocompatibility and antimicrobial activity that requires the presence of water for setting.[6],[7],[8]

Recently, GuttaFlow Bioseal sealer (Coltene Whaledent, GmBH + Co KG, Langenau, Switzerland), a new formula of polydimethyl-siloxane-gutta-percha doped with calcium silicate particles has been introduced to dental field in late 2015. It has been found to be biocompatible, less toxicity, and able to nucleate deposits of hydroxyapatite and Ca-poor apatite precursors.[9],[10]

However, retreatability of bioceramic sealer has been studied by different investigators with significantly varying results,[11],[12],[13],[14],[15] while only one study in literature investigated the retreatability of guttaflow bioseal root canal sealer.[16]

Remnants of root canal filling materials have been reported in many studies with different retreatment techniques.[14],[15],[17] These remnants in the canal wall and dentinal tubules could potentially cause mechanical barriers that protect the underlying microorganisms from the disinfecting action of the irrigants and intracanal medicaments.[18] These microorganisms could be responsible for the persistence of periapical disease.[19] Therefore, the aim of this study was to evaluate the retreatability of Bioceramic and GuttaFlow Bioseal sealers using ProTaper Universal System Retreatment files aided by dental operating microscope.


  Materials and Methods Top


Specimen preparation

Forty single-rooted human mandibular premolar teeth were used. The teeth were extracted for orthodontic purposes. The inclusion criteria were as follows: Straight root with single root canal; no visible root caries, fractures, or cracks; and a completely formed apex on visual examination. Roots with curvatures higher than twenty degrees were excluded. Mesiodistal and buccolingual preoperative radiographs were taken for each tooth to confirm the canal anatomy.

Teeth were immersed in 2.5% sodium hypochlorite (NaOCl) at room temperature for 2 days to remove organic debris. Then, the external root surfaces were cleaned using ultrasonic instruments to remove any calculus or soft tissue from the root surface. Then, the teeth were decoronated at cementoenamel junction or below to obtain a standardized root length of 15 mm by using a diamond disk. K-file sizes #10 and #15 (Dentsply Maillefer, Ballaigues, Switzerland) were inserted into the canal until it becomes visible at the apical foramen then 1 mm was subtracted to achieve a working length of 14 mm.

Every sample was mounted on a plastic cup (by inserting the root in a center hole keeping 4 mm of the coronal third above the up surface and fixed with the aid of soft putty (Aquasil Soft Putty/Regular Set, Dentsply Detrey, Germany). This monoblock will facilitate the sample handling during root canal preparation.

All root canals were prepared by one operator following the manfacturer's instructions. A Protaper Next System (Dentsply Maillefer, Ballaigues, Switzerland) X1, X2, and X3 at speed of 300 rotations/min (rpm), and torque of 3 Ncm was used to instrument the canals. Between each instrument change, the canals were abundantly irrigated with 2 ml of 2.5% NaOCl, then the instruments' flutes were cleaned with a wetted gauze and the file was coated with ethylenediaminetetraacetic acid gel in order to lubricate the canal and make the instrumentation easier. A size #10 K-file was inserted up to the working length after each rotary file used to keep the canal patent. The files were rotated in the canal up to the working length in a pecking motion. Each file was discarded after being used to prepare three canals only. After that, final rinse was performed with 5 ml of NaOCl solution, followed by 5 ml normal saline then dried with paper points (#30, Dentsply Maillefer, Ballaigues, Switzerland).

Then, samples were randomly divided into two groups (n = 20) based on root filling material: Group 1/(n = 20): Obturated with single gutta-percha cone technique (size X3, Dentsply Maillefer, Ballaigues, Switzerland) and EndoSequence Bioceramic root canal sealer (Brasseler USA, Savannah, GA, USA). Group 2/(n = 20): Obturated with single gutta-percha cone technique (size X3, Dentsply Maillefer, Ballaigues, Switzerland) and GuttaFlow Bioseal root canal sealer (Coltene Whaledent, GmBH + Co KG, Langenau, Switzerland).

All canals were filled with a matched-taper single gutta-percha cone technique to maintain consistency amongest the groups. The gutta-percha cone was coated with the tested root canal sealer and inserted into the root canal to the full working length. Excess gutta-percha was removed with System B 0.06-tapered plugger (SybronEndo, Orange, CA) allowing 2 mm of temporary filling to be placed in the cavity (Cavit-G, ESPE-Premier, Norristown, PA, USA). Mesiodistal and buccolingual periapical radiographs were taken to confirm the filling adequacy. The samples were stored in an incubator with 100% humidity at 37°C for 2 weeks to ensure complete setting of the materials.

Retreatment technique

All specimens were retreated with ProTaper Universal Retreatment System (Dentsply Maillefer, Ballaigues, Switzerland). A No. 3 Gates-Glidden drill (Dentsply Maillefer, Switzerland) was used to remove the coronal 2 mm of the root canal filling materials. ProTaper Universal Retreatment Files D1, D2, and D3 were sequentially used in a pecking motion in a crown-down manner. The D1 (size 30, 0.09 taper) was used for the removal of the coronal third of the filling materials, followed by the D2 (size 25, 0.08 taper) for the middle third and finally, D3 (size 20, 0.07 taper) up to the working length. The rotational speed was set at 500 rpm as recommended by the manufacturer. File penetration was carried out by using light apical pressure.

The whole procedures of root canal retreatment were done under dental operaring microscope (Global Surgical Corp., St. Louis, MO, USA). No solvent was used in all the groups. The canals were constantly irrigated at each instrument change with 2.5% NaOCl solution. Instruments were used to prepare 5 canals and then replaced, and also routinely checked and discarded when they were fractured or distorted. Retreatment was deemed complete when no debris of gutta-percha/sealer was visible on the surface of instruments and canal walls were smooth.[20] The time required to retreat each canal, the ability to reach the working length, and regaining of apical patency were determined for each canal. Regaining apical patency was checked by using a new #10 K-file. Patency was defined as visualization of the file from the anatomic apex.

Evaluation

The specimens were grooved vertically with slow speed cutting saw (BUEHLER Isomet 2000 Precision Saw, Illinois, USA) under water cooling on the buccal and lingual surfaces. Then, splitted longitudinally with a chisel into two-halves and observed under the dental operating microscope at ×20 magnification.

Lambrianidis et al.[21] and Boutsioukis et al.[22] scoring system to assess the quantity of the residue materials on the canal walls was followed. Evaluation scales of the remnants were as follow: (1) none, (2) scattered, (3) distinct masses, and (4) densely packed remnants [Figure 1]. Remnants were evaluated in each level (coronal, middle, and apical) of all sections, and the highest score on the two sections of each specimen was recorded.
Figure 1: Characteristic patterns of material remnants corresponding to the four evaluation scores (arrows). Evaluation scores: (1) none, (2) scattered, (3) distinct masses, and (4) densely packed remnants

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The working time needed to remove gutta-percha until reaching the original working length was recorded as Time 1. The time required to achieve satisfactory gutta-percha removal was recorded as Time 2. The total working time required to complete retreatment procedure was the sum of Time 1 and 2.

Evaluation of the specimens was made by two investigators whom were blinded to the sealer applied in each specimen. In cases of disagreement, sections were re-evaluated jointly by the observers.

Statistical analysis

Statistical analysis was performed using SPSS software (version 20.0; SPSS Inc, Chicago, IL, USA). Shapiro test was performed to test the normality of the data. The working time needed to remove gutta-percha until reaching the original working length (T1) and the total working time required to complete retreatment procedure (TT) were not normally distributed (P < 0.05), and the time required to achieve satisfactory gutta-percha removal (T2) was normally distributed (P > 0.05). The Mann–Whitney U test was used to test the equality of median time of retreatment files (T1 and TT) between the two sealers, while independent sample t-test was used to test the mean time of T2.

The Chi-square and Fisher's exact tests were used to assess the significant difference of residual of root canal filling materials between the sealer type and retreatment system files in all root levels. P < 0.05 was considered to indicate statistical significance.


  Results Top


The Kappa value was calculated to estimate the reliability of the measurements taken by the two observers. In this study, the value of the kappa test was completely reliable for coronal, middle, and apical thirds evaluation, kappa = 1.0, 1.0, and 0.88, respectively.

Retreatment time

Time 1 and total working time were measured in minutes and expressed as mean values, while Time 2 was measured in minutes and expressed as median values. Retreatment time of GuttaFlow Bioseal sealer was shorter (1.79 min) than that of Bioceramic sealer group (2.25 min). The Mann–Whitney U-test showed a statistically significant difference at Time 1 (P < 0.05).

For the time required to achieve satisfactory gutta-percha removal, the shortest time was recorded in retreatment of GuttaFlow Bioseal sealer (0.35 ± 0.095 min), while it was 0.45 ± 0.057 min for Bioceramic sealer group. The independent sample t-test showed a statistically significant difference at Time 2 (P < 0.05).

The least total working time required for retreatment was recorded in the removal of GuttaFlow Bioseal sealer (2.35 min), while the longest time was found in Bioceramic sealer group (3.13 min). The Mann–Whitney U-test showed a statistically significant difference at total time (P < 0.05) [Table 1].
Table 1: Time 1, Time 2, and total working time required to complete the retreatment procedure

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Residual of root canal filling materials

When the Bioceramic sealer removed with ProTaper Universal System Retreatment files was evaluated, the Chi-square test showed a statistically significant difference in the amount of residual root filling material between sealer type and ProTaper Universal System Retreatment files in coronal and apical thirds (P = 0.000 and 0.000, respectively), while Fisher's exact test showed a statistically significant difference in the middle third (P = 0.022). Scattered and distinct masses remnants were mostly found in the coronal third (50% each), while distinct masses remnants were more in the middle third (60%). In the apical third, scattered and densely packed remnants were the mostly observed scores (50% each).

In evaluation of the removal of root filling from GuttaFlow Bioseal sealer group, the Chi-square test showed a statistically significant difference in the amount of residual root filling material between sealer type and retreatment files in coronal and apical thirds (P = 0.000 and 0.000, respectively), while Fisher's exact test showed a statistically significant difference in the middle third (P = 0.022). Distinct masses remnants were mostly found in the coronal third (80%), while densely packed remnants were more in the middle third (80%). In the apical third, distinct masses remnants were the mostly observed score (70%).

For the apical third evaluation of the two groups, the Chi-square test showed a statistically significant association in residual of filling material between the sealer type and retreatment with ProTaper Universal System retreatment files (P = 0.000). In Bioceramic sealer group, scattered and densely packed remnants were mostly found in (50% each) of the samples, while in GuttaFlow Bioseal group, distinct masses remnants (70%) were more dominant. Residual of root canal filling material in study groups observed in coronal, middle, and apical third sections were illustrated in [Figure 2].
Figure 2: Residual of root canal filling material in study groups observed in coronal, middle, and apical third sections

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  Discussion Top


Many new root canal sealers have been recently introduced to dental field; however, the retrievability of some of these sealers is still unknown. Two of these sealers “EndoSequence Bioceramic and GuttaFlow Bioseal” were recommended by manufacturers to be used with the concept of single-cone obturation technique https://www.endoexperience. com/userfiles/file/endo_bcsealer.pdf, https://www.coltene.com/fileadmin/Data/EN/Products/Endodontics/Root_Canal_Obturation/GuttaFlow_bioseal/60013816_02-15_GuttaFlow_bioseal_EN.pdf). High-quality root canal fillings with single-cone techniques and endo-sequence BC and Guttaflow sealers have been reported. This is due to strong bonds along the sealer–gutta-percha interface.[23],[24]

Single rooted teeth were used in order to demonstrate differences in less complex anatomy.[25] The method used to evaluate the root canal filling remnant materials plays an important role in the results observed in each study.[12] Different methods have been used including radiographs,[26] clearing techniques and digitized images,[27] dental operating microscopes,[28] scanning electron microscopy,[29] and more recently, micro computed tomography.[30] In this study, dental operating microscope was used to simulate the clinical scenario during root canal retreatment. The use of dental operating microscope with its illumination and magnification during root canal retreatment reported to facilitate the detection of residual root filling materials, the cleanliness of the canal wall, and evaluation of the retreatment files.[28]

EndoSequence Bioceramic sealer was reported to require at least 168 h before being completely set,[31] while Zhou et al. reported that it takes 2.7 h to be completely set.[32] Loushine et al.[31] attributed the prolonged setting time to the overly wet canals. In the current study, the canals were dried before applying the EndoSequence Bioceramic sealer. In the other hand, GuttaFlow Bioseal root canal sealer was reported to have a setting time of 17.4 ± 0.55 min.[33]

The flow rate for EndoSequence Bioceramic sealer has been reported to be 23.1 mm and 26.96 mm.[32],[34] Akcay et al. assessed dentinal tubule penetration by different root canal sealers, including GuttaFlow Bioseal, and reported that it has similar dentinal tubule penetration to that of MTA Fillapex and AH-Plus.[9]

The results of this study demonstrated that none of the root filling materials could be completely removed which is in accordance with the results reported in previous studies.[11],[12],[14],[35],[36],[37]

It is worth mentioning that, no solvents were used in this study because solvents may create a fine layer of softened gutta-percha, which adheres to the root canal wall and accentuates the challenge of root canal filling materials removal which will need a longer working time.[37]

In this study, the median time for removal of Bioceramic material was 3.13 min compared to 2.35 min of GuttaFlow Bioseal material. The time required to remove Bioceramic sealer has been reported to be 7.14 ± 2.27 min using EndoSequence rotary instruments,[11] and 337 s using ProFile rotary instruments.[13] These differences could be attributed to the cutting efficiency of the retreatment files used, the use of one size of gates-glidden drills, and no use of heat nor solvent in retreatment procedure.

Residual filling of Bioceramic sealer materials removed using ProTaper Universal Retreatment system was evaluated by Sherif et al.[38] and Prasad el al.[39] Sherif et al.[38] showed mild/moderate (53.33%) followed by moderate/severe (26.67%) in the coronal third, and moderate/severe in the middle third (53.33%). The findings of the current study were similar to Sherif et al.[38] In contrast, the presence of residual debris in the apical third were lower than those observed by Sherif et al.,[38] although no reshaping procedures of root canal walls were used in this study.

Pedullà et al.[16] has reported that overall smaller volume of root filling remnants of guttaflow bioseal sealer were detected compared with BioRoot root canal sealer after removal and reshaping with rotary instruments in addition to the use of different supplementary irrigant agitation techniques. The findings of this study were in contrast with Pedullà et al.,[16] which could be attributed to that no reshaping nor supplementary irrigant agitation procedures were used in the current study.

ProTaper Universal System Retreatment files had the ability to remove large amounts of root filling through spirals running around the instruments, which produce both cutting and softening actions as well as the speed used to run the file. Furthermore, the presence of negative cutting angle and absence of radial land exert a cutting not a planning action on root filling materials, which may facilitate the removal of root canal filling material.[40] Moreover, the ProTaper Universal System Retreatment files' sequence and different tapers used during removal procedure could contribute to the residual filling materials found in the canal walls.

The working length and apical patency were re-established in 100% of samples which is different from the results obtained by Hess et al. in which only 80% of the samples the patency was regaind,[11] and Oltra et al. in which only 14% of the samples the patency was regaind,[15] and that of Kontogiannis et al. who reported that bioceramic sealer group was more difficult to regain patency compared with the MTA and AH Plus groups.[41] This reflect that retreatment of both Bioceramic and GuttaFlow Bioseal root canal sealers can be achieved clinically.

The limitations of the present study were having small sample size. Moreover, the findings cannot be explorated to all types of teeth as the samples used in this study relativley have straight roots. In addition, the use of a nondestructive method such as: Micro-computed tomography, in evaluation of the residual root filling materials is recommended.

Clinicians should be aware of the new endodontic sealer materials introduced in the dental field, their properties, application, and also their retreatability to be able to have a proper management achieving favorable treatment outcomes.


  Conclusion Top


Under the limitations of this ex vivo study, it can be concluded that the retreatment technique used was incapable of complete remove of the filling material within root canal walls.

Acknowledgment

The authors thank the Institutional Review Board of Riyadh Elm University, Riyadh, Kingdom of Saudi Arabia for their support in conducting this project (registration number: FPGRP/43633002/172). The authors also thank Professor Saad Al-Nazhan (Department of Restorative Dental Sciences, Riyadh Elm University, College of Dentistry, Riyadh, Kingdom of Saudi Arabia) for his valuable support and comments on this article.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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