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 Table of Contents  
Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 128-132

Apical debris extrusion of single-file systems in curved canals

1 Department of Endodontics, Faculty of Dentistry, Zonguldak Bülent Ecevit University, Zonguldak, Turkey
2 Department of Pediatric Dentistry, Faculty of Dentistry, Zonguldak Bülent Ecevit University, Zonguldak, Turkey

Date of Web Publication30-Sep-2021

Correspondence Address:
Dr. Ecehan Hazar
Department of Endodontics, Faculty of Dentistry, Zonguldak Bülent Ecevit University, Kozlu, Zonguldak
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_105_21

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Objectives: The aim of this study was to compare the apical debris extrusion after using three different single-file systems.
Materials and Methods: Mesial roots with curved canals of extracted mandibular molar teeth were randomly divided into three experimental groups according to preparation techniques: the XP-endo Shaper, WaveOne Gold, and One Curve. Previously weighed Eppendorf tubes were used to collect the debris which was placed in a 35°C hot water bath. The weight of the empty tube was subtracted from the final weight after instrumentation and recorded as the amount of extruded debris. The data were analyzed using the Kruskal–Wallis test at a 5% level of significance and compared all groups.
Results: XP-endo Shaper presented less debris extrusion than WaveOne Gold and One Curve (P < 0.05). There was no significant difference between the WaveOne Gold and the One Curve files (P > 0.05).
Conclusions: All the tested file systems caused debris extrusion. XP-endo Shaper caused less debris extrusion than WaveOne Gold and One Curve files.

Keywords: Dental instruments, nickel–titanium, root canal preparation

How to cite this article:
Hazar E, Özdemir O, Koçak MM, Sağlam BC, Koçak S. Apical debris extrusion of single-file systems in curved canals. Endodontology 2021;33:128-32

How to cite this URL:
Hazar E, Özdemir O, Koçak MM, Sağlam BC, Koçak S. Apical debris extrusion of single-file systems in curved canals. Endodontology [serial online] 2021 [cited 2022 Aug 9];33:128-32. Available from: https://www.endodontologyonweb.org/text.asp?2021/33/3/128/327266

  Introduction Top

The debris, including; microorganisms, irrigation solutions, pulp, and dentinal tissues may extrude beyond the apical foramen during instrumentation, which may result in a delay of the apical healing process, disrupt the balance between host defense and microbial aggression, and persistency of inflammation/infection and even failure of treatment.[1] Besides, convey of microorganisms and debris in the periapical area is the main cause of postoperative pain and flare-ups.[2] Therefore, the limitation of apical extrusion during the endodontic treatment can influence both comfort of the patient and the clinical outcome.

Recently, several novel nickel-titanium (NiTi) files have been produced with special alloying processes, different kinematics, and designs. All instrumentation techniques and instruments cause some degree of root canal content extrusion into periapical tissues.[1],[3],[4],[5] However, the amount of debris extrusion may vary due to different factors, including the blade design, cross-section, and the radial land of the instrument, or selected preparation techniques such as reciprocation, continuous rotation, or adaptive motion.[1],[3],[4],[5],[6],[7],[8]

WaveOne Gold (WOG, Dentsply Maillefer, Baillagues, Switzerland) is a reciprocating single-file system that is produced with a special gold alloy technology. Gold technology provides improved resistance to cyclic fatigue and higher flexibility.[9] WOG has a parallelogram-like cross-section with two cutting edges and an off-center design. The file engages 150° counterclockwise and 30° clockwise, turning 360° after three cycles of reciprocation. The apical size of the WOG primary file is #25 and has a variable taper along with the file (25/0.07). The XP-endo Shaper is a single-file rotary instrument produced from a MaxWire NiTi alloy with a constant taper of 1% and 0.30 mm apical diameter. Based on this special alloy, the instrument expands and contracts at the body temperature, and the taper increases to 4%.[10] The helical shaft design and six cutting edges at the tip of the file may be claimed to be the characteristic of the instrument. One Curve (OC, Micro-Mega, Besancon, France) is a single-file NiTi system produced by a C-Wire NiTi alloy using a proprietary heat treatment. Owing to the controlled memory NiTi alloy, the OC instruments allow the instrument pre-bending for consistency of root canal anatomy and conservation of the curvature as claimed by the manufacturer.[11] The apical size of the file is #25 and has a 0.06 taper with a variable cross-section design along the blade. The file has a variable cross-section consist of three-blades and two-blades to centered ability and increases cutting efficiency and also has an electropolished surface.[12],[13]

A comprehensive literature search revealed that apical debris extrusion of the OC system at the severely curved root canals has not been evaluated, and limited information is available about the comparison of these instruments. This study investigated the apical debris extrusion in curved root canals using WaveOne Gold, One Curve, and XP-endo Shaper systems. The null hypothesis tested was, there was no difference between WaveOne Gold, One Curve, and XP-endo Shaper files with regard to the debris extrusion in curved canals.

  Materials and Methods Top

This in vitro study was performed under the regulations of the ethics committee (protocol number: 2020-17-05/02). Forty-five extracted human mandibular molar teeth were selected. Teeth having mature apices with apical patency, without previous endodontic treatment or resorption/calcification, were included. All tissue remnants on the root surfaces were mechanically removed. Mesial and distal roots were separated from each other, and only mesial roots were used in the study. The coronal part of the specimens was flattened with a diamond disc for standardization. The mesial roots were inspected using a dental operating microscope (Leica Microsystems, Wetzlar, Germany) under ×16 magnification and examined by digital radiographs (MyRay, Imola, Italy), and those with two independent apical foramina (Vertucci class IV) were selected. The angle of curvature was measured using a software program (AutoCAD; Autodesk Inc., CA, USA) using Schneider's method.[14] The teeth with curvature angles between 25° and 45° were included. After coronal access preparation, a #10 K-file was inserted into the canal until its tip was visible at the apical foramen. The working length was determined by subtracting 1 mm from this length. In addition, the size of apical foramen was determined by a #15 K-file. The tooth in which the file extruded beyond the foramen without any resistance was discarded. During this procedure, the roots were examined under ×16 magnification using a dental operating microscope.

All instruments were used with a setup at 35°C hot water bath because of the special alloy XP-endo Shaper to ensure the standardization. All instruments were used only once for each specimen. In all groups, the file was taken out from the canal after three pecking movements, and the debris accumulation on the file was cleaned. Two milliliter of distilled water was used to irrigate the canals after each instrument, a #10 K-file was used for recapitulation. Then, the root canal was again irrigated with 2 ml distilled water. This procedure was repeated five times and a total of 20 ml distilled water was used for irrigation of each specimen to standardize the irrigation process. A single operator completed all procedures.

The specimens were randomly assigned to three experimental groups (n = 15) as follows:

  • Group 1: WOG Primary file (25/0.07) was used with an endodontic motor (X-Smart Plus, Dentsply Maillefer, Ballaigues, Switzerland) at the “WaveOne Gold” reciprocal mode
  • Group 2: One Curve file was used with the same endodontic motor; file (25/0.06) was used with continuous rotation at 300 rpm and 2.5 Ncm torque values
  • Group 3; XP-endo Shaper file was used with the same endodontic motor; file #30, with continuous rotation at 800 rpm and 1 Ncm torque values.

Myers and Montgomery method was used to collect the debris during preparation.[15] The cover of the tube was removed, and the initial weight was determined with a 10 −5 g precision scale (Radwag, Radom, Poland). The tubes were weighed three times and averaged. This was recorded as the initial weights.

The specimens were fixed in covers at the cementoenamel junction and a 27-G needle was inserted to balance the air pressure. After the instrumentation, the tooth, cover, and needle were removed. The root surface was irrigated with 1 ml distilled water to collect the debris. After the storage period in an incubator (5 days, 70°C) for evaporation, the tubes, including the debris, were reweighed three times and averaged to obtain the final weight. The initial weight was subtracted from the final weight and recorded as the amount of extruded debris. The distribution of data was determined using the Shapiro–Wilk test to verify the assumption of normality. The data were analyzed using the Kruskal–Wallis test at a 5% level of significance using SPSS 21.0 software (IBM Corp, Armonk, NY, USA).

  Results Top

The mean values and standard deviations of the groups are presented in [Table 1]. Measurable amounts of debris extrusion were obtained in all groups. XPS group showed less debris extrusion than WOG and OC groups (P < 0.05). The difference between WOG and OC files was not significant (P > 0.05).
Table 1: The mean values and standard deviations for the amount of apically extruded debris in each single-file system (g)

Click here to view

  Discussion Top

The infected debris extrusion may influence the occurrence and incidence of pain after root canal treatment. However, it is impossible to determine the amount and quantity of apical extrusion of debris or bacteria in clinical practice. Therefore, numerous laboratory studies are commonly used to compare NiTi systems and understand how different kinematics and design affect debris extrusion. It is well known that laboratory studies may not mimic the back pressure provided by vital periapical tissues. Therefore, in vitro results cannot directly correlate to clinical conditions. The current results may guide clinicians in the selection of instruments for the treatment of curved root canals.

A correlation between the amount of extruded debris and canal curvature was presented.[16] The correlation was related to less debris movement from the curvature in the coronal direction, and a possible need for more pecking movements to reach the full working length with the files. Therefore, to evaluate the instruments under difficult conditions, the curved mesiobuccal canals of mandibular molars were selected. Similarly, a positive correlation was reported between the amount of extruded debris and the diameter of the apical foramen.[17] Therefore, in the present study, in case of the extrusion of #15 K-file beyond the apical foramen, the tooth was excluded. A commonly used method to collect the debris that was described by Myers and Montgomery was used.[15]

Sodium hypochlorite was not used to irrigate the root canals to eliminate the formation of crystals or lead to the deposition of salts after evaporation.[18] Therefore, to prevent an increase in the debris weight, only distilled water was used as an irrigation solution, as shown in previous studies.[8],[15],[17],[18]

According to the present results, all single-file systems caused debris extrusion similar to the previous results. Different studies reported that all instrumentation systems, including using in different kinematics, hand instrumentation, and single or multiple file systems, various irrigation techniques cause different amounts of apical debris extrusion.[6],[7],[19],[20],[21],[22],[23] Within the tested instruments, the XPS caused significantly less debris extrusion compared with WOG and OC instruments. Thus, the null hypothesis was rejected. This finding supported previous results which reported that reciprocating movement may create more debris extrusion than continuous rotation.[1],[5],[20],[21],[24] On the contrary, WOG and OC files demonstrated comparable results. This conflicting result may be related to the physical properties of XPS which differs from both WOG and OC. The reduction of the contact area between the file and canal wall may result in less binding of the file and lead to more space around the file to accommodate the debris.[25],[26] Both the files have more mass areas compared to the XPS file, and the design of XPS which may provide a possible oscillation-like movement in the root canal, leading to a movement of debris in the coronal direction.

Several studies reported a correlation between the taper of the instrument and the amount of extruded debris. The greater taper was associated with higher levels of extrusion.[22],[27],[28] The results of the present study supported this finding, XPS file which has the lowest taper size, extruded less debris than both WOG and OC files.

In the present study, the next generations of WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) and One Shape (Micro-Mega, Besancon, France) single-file systems, which are claimed to have increased flexibility due to special heat treatments, were investigated. The taper and cross-section of the OC instrument are similar to the One Shape file. However, the cross-section of the WOG file is a parallelogram, and its taper (0.07) which is less than the WaveOne file. Gummadi et al. investigated the debris extrusion of WaveOne (25/0.08 reciprocal) and One Shape (25/0.06 rotational) systems in straight canals and reported less extrusion in the One Shape group.[21] Saricam and Kayaoglu reported that OC and its previous generation One Shape files caused similar debris extrusion in straight root canals.[29] The One Shape file has a triangular cross-section in the apical and an “S” shaped cross-section in the coronal part. WaveOne file has a modified convex triangular cross-section in the apical and convex triangle cross-section in the coronal. They considered that the reciprocating movement could act as a piston and extrude debris toward the periapical direction due to the file's triangular cross-section and high taper. On the contrary, our study revealed similar debris extrusion between OC and WOG files. This result may be related to the differences in methodology (such as canal curvatures), or variations in both cross-section and taper of the WOG file compared to the first generation. There are also a few studies that reported similar results in the debris extrusion between rotational and reciprocational instruments.[6],[22],[23] Tüfenkçi et al. evaluated the effect of the OC and Reciproc Blue (reciprocal movement, VDW, Munich, Germany) single-file systems on the amount of debris extrusion in the traditional and contracted endodontic cavity.[30] Similarly, they reported that there is no significant difference between file systems in traditionally prepared endodontic cavities.

There are a limited number of studies in the literature investigating debris extrusion of the XPS single-file system. Uslu et al. reported that debris extrusion of the XPS file was less than reciprocating Reciproc Blue single-file system.[8] Our results supported this finding and the XPS file extrudes less debris than the WOG single-file system which works in reciprocation.

Alves et al. found the volume of debris extruded by the XPS and Reciproc R25 (25/0.08) files similar under micro-computed tomography (micro-CT) analysis.[6] However, as a possible limitation of the micro-CT method, they reported that extruded debris may not reach a sufficient radiological density to be visualized.[6] In addition, the volume of debris was considered instead of weighing the amount of debris. Therefore, these conflicting results may be related to the differences in methodology.

  Conclusions Top

Recently, no report is available comparing OC, WOG, and XPS files with each other; thus, there is no possibility for a direct comparison with past studies. Under the in vitro conditions of this study, all the tested single-file systems caused extruded debris from the apical foramen. XPS files caused significantly less extrusion than WOG and OC files. The taper of the instrument may be a fact on the amount of extruded debris.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Caviedes-Bucheli J, Castellanos F, Vasquez N, Ulate E, Munoz HR. The influence of two reciprocating single-file and two rotary-file systems on the apical extrusion of debris and its biological relationship with symptomatic apical periodontitis. A systematic review and meta-analysis. Int Endod J 2016;49:255-70.  Back to cited text no. 1
Siqueira JF Jr. Microbial causes of endodontic flare-ups. Int Endod J 2003;36:453-63.  Back to cited text no. 2
Tanalp J, Güngör T. Apical extrusion of debris: A literature review of an inherent occurrence during root canal treatment. Int Endod J 2014;47:211-21.  Back to cited text no. 3
Koçak S, Koçak MM, Sağlam BC, Türker SA, Sağsen B, Er Ö. Apical extrusion of debris using self-adjusting file, reciprocating single-file, and 2 rotary instrumentation systems. J Endod 2013;39:1278-80.  Back to cited text no. 4
Bürklein S, Benten S, Schäfer E. Quantitative evaluation of apically extruded debris with different single-file systems: Reciproc, F360 and OneShape versus Mtwo. Int Endod J 2014;47:405-9.  Back to cited text no. 5
Alves FR, Paiva PL, Marceliano-Alves MF, Cabreira LJ, Lima KC, Siqueira JF Jr., et al. Bacteria and hard tissue debris extrusion and ıntracanal bacterial reduction promoted by XP-endo shaper and reciproc ınstruments. J Endod 2018;44:1173-8.  Back to cited text no. 6
Capar ID, Arslan H, Akcay M, Ertas H. An in vitro comparison of apically extruded debris and instrumentation times with ProTaper universal, ProTaper next, twisted file adaptive, and HyFlex instruments. J Endod 2014;40:1638-41.  Back to cited text no. 7
Uslu G, Özyürek T, Yılmaz K, Gündoğar M, Plotino G. Apically extruded debris during root canal ınstrumentation with reciproc blue, HyFlex EDM, and XP-endo shaper nickel-titanium files. J Endod 2018;44:856-9.  Back to cited text no. 8
FKG Dentaire. The XP endo Shaper Brochure Available from: https://www.fkg.ch/xpendo/files/FKG_XP-endo_Shaper_Flyer_EN_WEB_201902.pdf. [Last accessed on 2021 May02].  Back to cited text no. 10
Micro Mega. The One Curve Brochure. Available from: https://micro-mega.com/wp-content/uploads/2020/11/60301900-A_Flyer-One-Curve-Portfolio-EN_web.pdf. [Last accessed on 2021 May02]  Back to cited text no. 11
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Saleh AM, Vakili Gilani P, Tavanafar S, Schäfer E. Shaping ability of 4 different single-file systems in simulated S-shaped canals. J Endod 2015;41:548-52.  Back to cited text no. 13
Schneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg Oral Med Oral Pathol 1971;32:271-5.  Back to cited text no. 14
Myers GL, Montgomery S. A comparison of weights of debris extruded apically by conventional filing and canal master techniques. J Endod 1991;17:275-9.  Back to cited text no. 15
Karataslioglu E, Arslan H, Er G, Avci E. Influence of canal curvature on the amount of apically extruded debris determined by using three-dimensional determination method. Aust Endod J 2019;45:216-24.  Back to cited text no. 16
Tinaz AC, Alacam T, Uzun O, Maden M, Kayaoglu G. The effect of disruption of apical constriction on periapical extrusion. J Endod 2005;31:533-5.  Back to cited text no. 17
Borges ÁH, Pereira TM, Porto AN, de Araújo Estrela CR, Miranda Pedro FL, Aranha AM, et al. The Influence of cervical preflaring on the amount of apically extruded debris after root canal preparation using different ınstrumentation systems. J Endod 2016;42:465-9.  Back to cited text no. 18
Mendonça de Moura JD, Bueno CE, Fontana CE, Pelegrine RA. Extrusion of debris from curved root canals ınstrumented up to different working lengths using different reciprocating systems. J Endod 2019;45:930-4.  Back to cited text no. 19
Bürklein S, Schäfer E. Apically extruded debris with reciprocating single-file and full-sequence rotary instrumentation systems. J Endod 2012;38:850-2.  Back to cited text no. 20
Gummadi A, Panchajanya S, Ashwathnarayana S, Santhosh L, Jaykumar T, Shetty A. Apical extrusion of debris following the use of single-file rotary/reciprocating systems, combined with syringe or ultrasonically-facilitated canal irrigation. J Conserv Dent 2019;22:351-5.  Back to cited text no. 21
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Kirchhoff AL, Fariniuk LF, Mello I. Apical extrusion of debris in flat-oval root canals after using different instrumentation systems. J Endod 2015;41:237-41.  Back to cited text no. 23
Toyoğlu M, Altunbaş D. Influence of different kinematics on apical extrusion of ırrigant and debris during canal preparation using K3XF ınstruments. J Endod 2017;43:1565-8.  Back to cited text no. 24
Dincer AN, Guneser MB, Arslan D. Apical extrusion of debris during root canal preparation using a novel nickel-titanium file system: WaveOne gold. J Conserv Dent 2017;20:322-5.  Back to cited text no. 25
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Elashiry MM, Saber SE, Elashry SH. Apical extrusion of debris after canal shaping with three single-file systems. Niger J Clin Pract 2020;23:79-83.  Back to cited text no. 26
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Silva EJ, Carapiá MF, Lopes RM, Belladonna FG, Senna PM, Souza EM, et al. Comparison of apically extruded debris after large apical preparations by full-sequence rotary and single-file reciprocating systems. Int Endod J 2016;49:700-5.  Back to cited text no. 28
Saricam E, Kayaoglu G. Comparison of OneShape, 2Shape and one curve endodontic instruments for debris and irrigant extrusion. Dent Med Probl 2020;57:255-9.  Back to cited text no. 29
Tüfenkçi P, Yılmaz K, Adigüzel M. Effects of the endodontic access cavity on apical debris extrusion during root canal preparation using different single-file systems. Restor Dent Endod 2020;45:e33.  Back to cited text no. 30


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