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Year : 2021  |  Volume : 11  |  Issue : 2  |  Page : 235-239

A comparative assessment of apical debris extrusion by various glide path establishing endodontic instruments: An in vitro study

Department of Conservative Dentistry and Endodontics, Vokkaligara Sangha Dental College and Hospital, Bengaluru, Karnataka, India

Date of Submission26-Jun-2020
Date of Decision17-Jul-2020
Date of Acceptance31-Aug-2020
Date of Web Publication8-May-2021

Correspondence Address:
Dr. V P Anshida
Department of Conservative Dentistry and Endodontics, Vokkaligara Sangha Dental College and Hospital, Bengaluru, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sej.sej_158_20

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Introduction: A reproducible glide path provides guidance to fulfil the mechanical objective of cleaning and shaping root canals with minimal procedural errors. Debris expelled during this procedure contributes to inter-appointment flare-up. The objective of this in vitro study was to estimate and compare the quantity of debris extruded by; hand, rotary and reciprocating glide path preparation instruments.
Materials and Methods: Seventy-five human single rooted, matured mandibular incisors with single canal and comparable lengths were randomly allocated into three groups (n = 25): group A – Stainless steel (SS) K-file (No 15), Group B – ProGlider, and Group C –WaveOne Gold Glider. Customized apparatus using Meyers and Montgomery method was utilized to accumulate the debris expelled apically in the Eppendorf tubes weighed priorly in digital analytical balance of 10−6 g accuracy. All groups were instrumented as per the manufacturer's guidelines. After instrumentation, teeth were detached from the Eppendorf tubes and tubes incubated at 70°C for 5 days to vaporize the irrigating solution. The tubes with dry debris were later weighed in the same weighing balance. The collected information was analyzed by one-way ANOVA and Tukeys honest significant difference post hoc test at significance level (P < 0.05).
Results: The ProGlider group expressed statistically significant result with least quantity of extruded debris in the comparison to other groups (P < 0.0001). The SS group and WaveOne Gold Glider group exhibited no significant difference, but the debris expelled was less for WaveOne Gold Glider group than SS group.
Conclusion: Glide path preparations with rotary ProGlider resulted in the minimal extrusion of debris in comparison to the reciprocating WaveOne Gold Glider and the manual stainless-steel K-files.

Keywords: Debris extrusion, glide-path, nickel-titanium, proglider, WaveOne gold glider

How to cite this article:
Anshida V P, Sudhanva M E, Vikram R, Gowda VS. A comparative assessment of apical debris extrusion by various glide path establishing endodontic instruments: An in vitro study. Saudi Endod J 2021;11:235-9

How to cite this URL:
Anshida V P, Sudhanva M E, Vikram R, Gowda VS. A comparative assessment of apical debris extrusion by various glide path establishing endodontic instruments: An in vitro study. Saudi Endod J [serial online] 2021 [cited 2021 Jun 17];11:235-9. Available from: https://www.saudiendodj.com/text.asp?2021/11/2/235/315641

  Introduction Top

In 1974, Schilder laid the foundation for a predictable and successful endodontic treatment, and since then, his objectives of cleaning, shaping, and three-dimensional obturation outweigh all the revolutionary advances.[1] Clinicians often sense complications during initial canal exploration and preflaring, the primary phase of root canal instrumentation.[2] Effective and adequate instrumentation is enhanced by first scouting with small size K-files, thus creating a hand generated “glide path,” reproducing this hand glide path by rotary file and then continuing the preparation with hand/rotary/reciprocating shaping instruments.[3]

John West defined endodontic glide path as a smooth, though possibly narrow, tunnel or passage from the coronal orifice of the canal to the radiographic terminus or electronically determined portal of exit.[4] Glide path preparation helps the clinicians in maintaining the original canal morphology with reduced alteration in the curvature of the canal, procedural complications, and also increasing the life span of mechanical instruments.[5],[6],[7]

Nevertheless, while instrumenting the canal space, and at some point of the irrigation procedures, there lies a risk of debris getting extruded from the canal space into periapical vicinity. Apically expelled debris consisting of necrotic tissue, dentin shred and microorganisms, in periapical zone may have the potential to evoke an acute inflammatory reaction, resulting in pain and swelling called flare up.[8] Glide path preparation can also bring about debris extrusion. Even though, they produce minimal quantity of debris extrusion, toxicity of the pioneer expelled debris is greater in comparison to the debris produced later by shaping files.[9] Debris expelled by an instrument can be influenced by filing techniques, instrument movements, cross section, tip diameter, taper, pitch as well as single- or multiple-file systems.[10]

Stainless steel (SS) hand K-files have been used to prepare glide path since the beginning. With the introduction of nickel-titanium (NiTi) glide path files, they granted a promising advantage over the traditional stiff SS hand K-files in preserving the canal anatomy, reducing the procedural errors, debris expulsion, and subsequent postoperative pain.[11] Since then, there has been a considerable improvement in NiTi metallurgy and thermo mechanical treatments to reduce cyclic fatigue and improve flexibility and torsional resistance.[12] One such advanced thermal treatment gave rise to a special NiTi alloy called M-wire technology.[13],[14] ProGlider is a glide path establishing instrument made of M-wire technology with improved flexibility and high cyclic fatigue resistance.[15] Later in 1958, reciprocating motion, described as any repeated back and forth movement, was introduced into endodontics.[16] Initially, it began with equal bi-directional movement but shifted to unequal bi-directional motion because of their striking benefits over continuous rotary motion such as better cutting efficiency and augering debris into the flute space.[16],[17] WaveOne Gold Glider is the first reciprocating glide path file which uses reciprocating motion.

There may be no dependable proof regarding the assessment and comparison of the expelled apical debris while creating glide path with hand, rotary, and reciprocating instruments. Hence, this research was conducted to estimate and compare the quantity of apically expelled debris with various glide path preparation instruments.

  Materials and Methods Top

Specimen preparation

This present study's research protocol was accepted by Kempegowda Institute of Medical Science, Institutional University Ethics Committee with registration number-ECR/216/Inst/Kar/2013/RR-19, on November 10, 2017. Seventy five human single rooted mandibular incisors with matured apex and those free from cracks and fractures were acquired for the purpose of the study by confirming under the digital operating microscope. Teeth with curvatures (0°–10°) were selected by following Schneider's method[18] and single canal was confirmed by examining buccolingual and mesiodistal directions with digital radiograph (RVG6100; Carestream Dental LLC, Atlanta, GA, USA). Teeth with calcified canals, internal resorption, and root canal without apical patency were omitted. Teeth were then cleaned off of soft-tissue debris and calculus and disinfected in 0.5% chloramine-T solution storing for <6 months. Endodontic access was performed for all the specimens with endo access bur #2. Working length of each sample was assessed by inserting a size 8 K-file till the tip appeared out of the apex and reducing 0.5 mm from the anatomic apex. To standardize the apical foramen diameter and to establish patency, a 10 K-file was utilized and those with properly adapted 10 K-file at the apex were only used for the study purpose. After standardizing the working length to 17 mm by decoronating the samples, they were randomly designated into groups of three with 25 samples each based on the glide path preparation instruments.

Grouping of the teeth

  • Group A (n = 25): SS 15 K Hand file (Dentsply Tulsa Dental Specialties, Tulsa York, Pennsylvania,)
  • Group B (n = 25): ProGlider (Dentsply Sirona, Ballaigues, Switzerland)
  • Group C (n = 25): Wave One Gold Glider (Dentsply Sirona, Ballaigues, Switzerland).

Apparatus setup and initial weighing

Myers and Montgomery's model[19] was adopted in the study to assess the apically extruded debris. For every sample in the study, an Eppendorf tube was marked and weighed individually on an analytical weighing balance of 10−6 g accuracy. The mean weight of each tube was determined and recorded by calculating the average of three successive weights. The orifice of the glass vials with inserted Eppendorf tubes was closed with modelling wax. Opening of the glass vial was such that the end of Eppendorf tube exactly fits within the glass vial. Each teeth was squeezed through the modelling wax into the tube up to cemento-enamel junction and fixed with cyanoacrylate adhesive. A 27G needle was inserted next to the teeth to equalize the pressure in and out of the tube. A suction was used to remove the overflowing irrigant while instrumenting the samples. Each glass vial was covered with aluminum foil to forbid the operator from making any error during the procedure.

Irrigation and instrumentation procedure

Instrumentation for respective groups were carried out as per the manufacturer's instruction and using 2 ml bi-distilled water as the irrigating solution.

  • For Group A-(K-file No 15 size): SS 15 K-file was used with balanced force technique to create glide path, while the canal was filled with 1 ml of distilled water
  • For Group B-(ProGlider): File was used in continuous rotation as per the manufacturer's instructions using X-Smart Endo Motor (Dentsply Sirona, Tulsa Dental Specialties Tulsa York, Pennsylvania) setting at 300 RPM with a torque of 2 N cm. While the canal was filled with 1 ml of distilled water
  • For Group C – (Wave One Gold Glider): File was used in reciprocating motion as per manufacturer's instruction using Torque controlled motor-X smart plus (XSM, Dentsply Maillefer, Ballaigues, Switzerland) with an inbuilt program for WaveOne instruments, while the canal was filled with 1 ml of distilled water.

After each file reached the full working length, the glide path was established by using repetitive up and down motion three times with the corresponding file.

Debris collection and weighing

The teeth were detached from the tube after instrumentation and debris sticking to the surface of the root was accumulated to the Eppendorf tube by rinsing off the tooth apex with 1 ml distilled water. The tubes were later incubated in trays with lid slightly open in a KEMI temperature controlled incubator for 5 days at 70°C, for the accumulation of dry debris after vaporizing the water content. Weight of the tube with the dry debris was calculated by taking the average of three successive weights. Net weight of dry debris was estimated by deducting the weight of the empty tube from the weight of the tube with dry debris.

Statistical analysis

The fresh collected data were analyzed statistically, using the Shapiro–Wilk test for normal distribution and homogeneity. The results were analyzed using the one-way ANOVA test followed by Tukey's honest significant difference post hoc test using the Statistical Package SPSS 22.0 (SPSS Inc., Chicago, IL, USA). P < 0.05 was deemed to imply a significant difference in all tests.

  Results Top

Mean and standard deviations of apically expelled debris by respective groups are depicted in [Table 1]. ProGlider Group extruded the least amount of debris and differed significantly from the other groups (P < 0.0001). The Groups SS K-file and Wave One Gold gilder showed no significant difference; however, WaveOne Gold Glider produced less debris than SS Group, which had the highest amount of debris extruded (P < 0.05).{Table 1}

  Discussion Top

An endodontists emergency which alarms most of the endodontics after beginning a root canal treatment is the inter-appointment flare-up. Numerous factors can contribute to this pain and swelling, including mechanical instrumentation, chemical irrigant and microbial extrusion evoking an acute inflammatory reaction in the periapical zone.[9],[20] Shovelton through his study, provided evidence for the bacterial extrusion into the periapical area.[21] The count of apically expelled debris has a strong association with the quantity of debris extruded (quantitative factor) and the bacterial forms and virulence are coupled with the intensity of inflammation formed in the periapical zone (qualitative factor).[21]

Hence, it is relevant to understand the quantity of debris that is expelled periapically with the different systems available for glide path preparation as creating glide path produces debris with greater toxicity in comparison to the instruments used for shaping.

For a fair comparison of the systems, teeth samples in which 10 K-file got properly adapted at the apex was included. Working length was methodized to 17 mm and kept 1 mm short of anatomical apex as less debris is extruded when the canal is instrumented short of anatomical apex[22] and to exclude the errors with varying working length on the extrusion of debris as well as to control the irrigant penetration.

Sodium hypochlorite can form crystals and might alter the weight of debris extruded. Hence, bi-distilled water was the alternate irrigating solution used in the study. Side vented needles were used for the irrigant delivery as they reduce the chance of irrigant extrusion in comparison to the regular needles with open end.[23]

Meyers and Montgomery method[19] was adopted for assessing the quantity of apically extruded debris. This experimental setup does not mimic the original surrounding tooth architecture in ways such as lacking the physical barrier and back pressure from the surrounding periapical tissues which is said to withstand irrigant and debris extrusion, and not resembling to a close system and gravity which can influence aforementioned extrusion out of the canal. Simulation of back pressure from the periapical tissue can be mimicked by using floral foam,[23],[24] but this setup might absorb irrigants and debris affecting the outcome of the study. Hence, it was not adopted in the present study. In spite of the drawbacks of Myers and Montgomery model, it was adopted as a means of calculating debris as it is feasible and can be replicated in conjunction with most approaches.

The present study showed minimal apical extrusion of debris with rotary ProGlider compared to the stiffer SS hand file and reciprocating WaveOne Gold Glider. The unique design feature of ProGlider with its kinematic movement can be the reason for producing the above mentioned result. ProGlider has a tip diameter of 0.16 mm and a variable progressive taper with 2% taper at the tip (D0) which progresses to 8% (D16) giving an expanded coronal preflaring.[25] This simulates the crown down preparations removing dentin from the coronal and middle third in particular, during the beginning of glide path preparation. Rotary movement of ProGlider helps in augering the debris into the fluid space and transport it coronally.[10],[11],[26] The result obtained from the study was analogous to another study by Ha et al., wherein four glide path establishing instruments-SS, ProGlider, One G, Scout Race glide were evaluated for apical debris extrusion and ProGlider being the one with least extrusion of debris.[8] A study done by Sen et al.,[27] Karatus et al.,[28] and Arora et al.[29] provided consistent result with the present study conveying rotary instruments expel less debris in comparison to hand instruments.

Stiffer SS K-files with their piston action and push-pull movement pumps the irrigants from the canal space apically. Furthermore, the small chip space and less taper of the file limits their ability to flush out the debris along with the irrigants coronally.[30] This gives substantial evidence to the inference that SS manual glide path file extruded maximum amount of debris apically among all the three groups.

The WaveOne Gold Glider comes with a tip diameter of 0.15 mm at D0 along with a progressively increasing taper from 2% at D0 to 6% at D16. The file operating in a 150° counter clockwise rotation and a 30° clockwise rotation results in better cutting efficiency, and the parallelogram shaped cross-section helps in augering the debris into the chips space but their reciprocating motion may enhance this debris toward the apex rather than coronally. The aforementioned proposition was also found in the study of Bürklein and Schäfer[31] According to the study, all glide paths preparing instruments induced the extrusion of debris during instrumentation. Rotary ProGlider glide path file expelled less debris in comparison to reciprocating WaveOne Gold Glider and hand K-file with statistical relevance (P < 0.0001).

In general, it is recommended to enlarge the canals till 20 size hand K-file before the usage of instruments in rotary or reciprocating motion, but the quantity of debris extruded due to the piston action of K-file is more compared to any other instruments.[32] The findings of this in vitro study suggests the preferential usage of a rotary NiTi glide path as it extrudes less debris, after initial canal scouting with 10 size K-file. The limitation of the present study was that it has only paid attention to the quantitative aspect of debris extrusion with an experimental setup trying to mimic the original surrounding tooth architecture. Therefore, the results of this study cannot be completely adopted to the clinical situations. However, further studies and clinical trials on the aspect of extrusion of substance P and calcitonin G peptide expression in the periodontal ligament as a result of glide path preparation instruments and various motions are required to assess their impact on clinical outcome.

  Conclusion Top

All glide path establishing instruments do extrude debris apically in some variable quantity. ProGlider instrument resulted in the minimal amount of debris expulsion in comparison to the SS hand K-files and WaveOne Gold Glider.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Berutti E, Paolino DS, Chiandussi G, Alovisi M, Cantatore G, Castellucci A, et al. Root canal anatomy preservation of WaveOne reciprocating files with or without glide path. J Endod 2012;38:101-4.  Back to cited text no. 5
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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. 22
Altundasar E, Nagas E, Uyanik O, Serper A. Debris and irrigant extrusion potential of 2 rotary systems and irrigation needles. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:e31-5.  Back to cited text no. 23
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[PUBMED]  [Full text]  
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[PUBMED]  [Full text]  
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Hof R, Perevalov V, Eltanani M, Zary R, Metzger Z. The self-adjusting file (SAF). Part 2: Mechanical analysis. J Endod 2010;36:691-6.  Back to cited text no. 32


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