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 Table of Contents  
Year : 2021  |  Volume : 33  |  Issue : 1  |  Page : 30-35

Cone-beam computed tomography assessment of root canal transportation and evaluation of remaining dentin thickness using XP EndoShaper and EndoStar E5

Department of Conservative Dentistry and Endodontics, PMNM Dental College, Bagalkot, Karnataka, India

Date of Submission04-Feb-2020
Date of Decision14-Jun-2020
Date of Acceptance20-Jul-2020
Date of Web Publication23-Mar-2021

Correspondence Address:
Dr. Nikita Arun Kamat
PMNM Dental College, Bagalkot - 587 103, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_16_20

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Introduction: The aim of this study was to compare canal transportation and remaining dentin thickness (RDT) of multiple-file system EndoStar E5 and single-file system XP EndoShaper (XPS) using cone-beam computed tomography (CBCT).
Materials and method: A total of 50 mesiobuccal canals of the maxillary first molars with curvatures of 15°°–30°° were chosen and randomly divided into two experimental groups (n = 25). Canals were shaped with XPS in Group 1 and with EndoStar E5 in Group 2. According to the manufacturer's instructions, canal preparation was made. Canals were scanned before and after instrumentation using CBCT scanner to evaluate the root canal transportation at 3, 5, and 7 mm from the apex. Data were statistically analyzed, and significance level was set at P < 0.05.
Results: Intergroup comparison mesiodistally showed that there was no significant canal transporation among both groups. Intergroup comparison buccolingually showed that there was statistically significant canal transporation at five millimeters when instrumented with XPS than EndoStar E5. With respect to RDT, intergroup comparison showed that mesially, distally, lingually, and bucally, there was no significant difference in the RDT.
Conclusion: The present study indicates safety in the preparation of root canals with XPS as well as EndoStar E5. Both the files maintained original canal curvature while preserving RDT.

Keywords: Canal transportation, cone-beam computed tomography, EndoStar E5, remaining dentin thickness, XP EndoShaper

How to cite this article:
Kamat NA, Vallabhaneni S, Saraf P, Kamatagi L, Totad S. Cone-beam computed tomography assessment of root canal transportation and evaluation of remaining dentin thickness using XP EndoShaper and EndoStar E5. Endodontology 2021;33:30-5

How to cite this URL:
Kamat NA, Vallabhaneni S, Saraf P, Kamatagi L, Totad S. Cone-beam computed tomography assessment of root canal transportation and evaluation of remaining dentin thickness using XP EndoShaper and EndoStar E5. Endodontology [serial online] 2021 [cited 2021 Jun 14];33:30-5. Available from: https://www.endodontologyonweb.org/text.asp?2021/33/1/30/311745

  Introduction Top

The ultimate goal of endodontic treatment is to remove infected pulpal remnants, destroy microorganisms, and adequately shape root canal system to fill the canal.[1] When curvatures are present, endodontic preparation becomes more difficult and there is a tendency for all preparation techniques to divert the prepared canal away from the original axis.[2] The curvature of the canal is considered to be a preeminent risk factor for procedural errors such as ledging, zipping, and transportation.[3]

Transportation occurs due to the tendency of endodontic instruments to straighten within the canal during chemomechanical preparation. Glossary of endodontic terms of American Association of Endodontists defines canal transportation as “the removal of canal wall structure on the outside curve in the apical half of the canal due to the tendency of files to restore themselves to their original linear shape during canal preparation may lead to ledge formation and possible perforation.”[4]

Excessive dentin removal in a single direction within the canal rather than all directions causes canal transportation that may lead to ledge formation and perforation. The thickness of the remaining dentin following intra-radicular procedures correlates to fracture resistance of the root. Preservation of dentin is of utmost importance.[5]

Introduction of rotary nickel titanium (Ni-Ti) instrumentation in endodontics is an important step in optimal root canal shaping procedure, as they maintain the original canal shape without creating severe irregularities such as zip, ledge or perforation, particularly in narrow curved canals, and also remains centered in the canal because of their superelasticity and shape memory.[6]

Recently, a classical multi-sequential rotary file system EndoStar five (E5) (Poldent Co, Warsaw, Poland) has been introduced, and these files easily fit even in most curved canals, minimizing risk of perforation. They have modified shape of S Ni-Ti file with two 90° cutting edges which form long, almost vertical spirals, ensuring better control of instrument progression. This file system is produced with different sizes (30/0.8, 30/0.6, 30/0.4, 25/0.4, and 20/0.4). They have shallower cuts, very elongated flutes, and safe rounded tip.[7]

Nowadays, there is a pursuit for simplifying endodontics using systems that use fewer files; decrease the learning curve, working time, cross-contamination; and increase efficiency and safety. Moreover, a single-file technique has been conceptualized for decades. However, from the past few years, these systems have come into reality.

Recently, XP EndoShaper (XPX) has been introduced; the XPS (FKG Dentaire, La Chaux- de-Fonds, Switzerland) is a single-file system which is a “Novel Adaptive core” Rotary instrument with an apical diameter of 0.30 mm and fixed smaller taper of 0.01. XPS is made up of Max wire alloy (FKG DENTAIRE SA), the martensite phase of the file at room temperature converts to austenite phase at body temperature, and the taper of 0.01 reaches to 0.04 assuming a “Snake” shape while preserving the original canal anatomy and curvature. XPS applies minimum stresses on the dentinal walls and thus can adapt easily to canal irregularities but operates in a clockwise continuous rotation movement. It combines the MaxWire alloy technology to give more flexibility and cyclic fatigue resistance to the instrument and a booster tip that enables the instrument to start shaping a canal with an initial diameter smaller than the instrument itself.[8]

To investigate the efficiency of instruments and techniques developed for root canal preparation, a number of methods have been used. Cone-beam computed tomography (CBCT) is a modern noninvasive diagnostic method with compact equipment and low-dose radiation and allows evaluation of detailed images.[9] It is useful in comparing the anatomy of root canal system before and after biomechanical preparation, allowing to detect deviations and transportation and amount of remaining dentin thickness (RDT).[10]

  Materials and method Top

In the present study, 50 mesiobuccal roots of the extracted maxillary first molar teeth with completely formed apices were collected from P. M. N. M. Dental College, Bagalkot. Teeth having root curvature ranging from 15° to 30° were selected. Canal curvature was assessed by Schneider's technique, and the samples were standardized.[11]

Access cavities were prepared with access preparation kit (Dentsply, Maillefer, Ballaigues, Switzerland), and the root canals were negotiated using #10 K-file (Dentsply, Maillefer, Ballaigues, Switzerland). Distobuccal and palatal roots of all teeth were separated using diamond disc at the furcation level. A size #10 K file was placed in the canal until it was visible at the apical foramen and WL was established one millimeter short of this length. For more uniform samples, the crowns were flattened and a final WL of 18 mm was standardized for each specimen. Roots were embedded in the acrylic blocks of 2.5 cm × 2.5 cm. Preinstrumentation CBCT scan was done.

The teeth were randomly divided into two experimental groups (n = 25). Group 1 (n = 25) canals were instrumented using XPS single-file system with 3–4 up-and-down strokes applying light apical pressure till working length was reached. XPS (size 30/0.4 taper) was used in the X-Smart Plus Endomotor in the continuous rotation for shaping the canals. Torque and speed values used for XPS were 1 Ncm and 800 rpm, respectively.

Group 2 (n = 25) canals were instrumented using EndoStar E5 multiple-file system which was used for shaping the canals. EndoStar E5 was used in the X-Smart Plus Endomotor in the continuous rotation for shaping the canals. The torque and speed values used for EndoStar E5 were 1 Ncm and 150 rpm, respectively.

The sequence for canal preparation was as follows:

  • A file with one strip (size 30/0.8) was used to prepare the first 8 mm
  • A file with two strips (size 30/0.06) was used to full working length of 18 mm
  • A file with three strips (size 30/0.04) was used to full working length of 18 mm.

The final apical preparation was standardized for all specimens at size 30. Instrumentation was done using Glyde (Dentsply Maillefer, Switzerland) as a lubricating agent. Canals were irrigated with two milliliters of 3% sodium hypochlorite during instrumentation. Once the instrumentation was completed, one millimeter of 17% ethylenediamine tetraacetic acid was used for 3 min followed by a final irrigation with two milliliters of saline. Each instrument was used to prepare five canals, and then, the files were discarded. Teeth were then again scanned under CBCT and data were analyzed.

Image analysis

All the teeth were scanned using CBCT (HDX WILL, North America) with the following setup: 90 kVp, 27 mA, 0.1 mm × 0.1 mm × 0.1 mm voxel size, and 0.1 mm axial thickness, to determine the root canal shape before instrumentation. The first section was at 3 mm from the apical end of the root (apical level), the second section at middle third (mid-root level) 5 mm from the apex, while the third section at the coronal third, 7 mm from the apex were recorded. After the initial scan, root canals were instrumented and image analysis was performed using On Demand 3D App software, Yokohama, Japan.

Cone-beam computed tomography measurements

The following formula was used for the calculation of canal transportation mesiodistally and buccolingually at each level for both the groups [Figure 1].[12]
Figure 1: Cone beam computed preinstrumentation and postinstrumentation images

Click here to view

Mesiodistally = (m1m2)(d1−d2)

Buccolingually = (l1−l2)(b1−b2)


  • mesial (m1)/lingual (l1) is the shortest distance from the mesial/lingual edge of the root to the mesial/lingual edge of the uninstrumented canal
  • distal (d1)/buccal (b1) is the shortest distance from the distal/buccal edge of the root to the distal/buccal edge of the uninstrumented canal
  • m/l is the shortest distance from the mesial/lingual edge 22 of the root to the mesial/lingual edge of the instrumented canal.
  • d2/b2 is the shortest distance from the distal/buccal edge of the root to the distal/buccal edge of the instrumented canal.

According to this formula, a negative result indicates transportation toward the distal/buccal portion, a positive result toward the mesial/lingual portion and zero, the absence of transportation.

Evaluation of remaining dentin thickness

The amount of RDT was calculated as the difference measured before and after instrumentation at three levels (coronal, middle, and apical) and four sides – mesial, distal, buccal, and lingual.

Statistical analysis

The intergroup comparison was made using independent sample t-test and Mann–Whitney U-test. The intragroup comparison was made using Friedman's test. SPSS software (SPSS version 17.0, SPSS, Chicago, IL, USA) was used for statistical analysis, and the level of significance was set at 0.05.

  Results Top

Canal transportation

In the intergroup comparison, mesiodistally, there was no statistically significant difference at 3 mm, 5 mm, and 7 mm between the groups [Graph 1].

Buccolingually, there was statistically significant difference in the canal transportation at 5 mm, when instrumented with XPS (Group 1) than EndoStar E5 (Group 2) [Graph 2].

Remaining dentin thickness 20 With respect to RDT, intergroup comparison showed that, mesially, distally, buccally, and lingually, there was no significant difference between the groups [Table 1], [Figure 2], [Figure 3].
Table 1: Comparison of the remaining dentin thickness (mesiodistally and buccolingually) at different levels between Group 1 and Group 2 using independent tests

Click here to view
Figure 2: Cone beam computed preinstrumentation and postinstrumentation images of XP EndoShaper (Group 1) Group 1: XP EndoShaper

Click here to view
Figure 3: Cone beam computed preinstrumentation and postinstrumentation images of EndoStar E5 (Group 2) Group 2: EndoStar E5

Click here to view

  Discussion Top

Root canal shaping is a critical aspect of endodontic treatment because it influences the outcome of the subsequent phases of canal irrigation, filling, and the overall success of the treatment itself. Ideally, during the root canal preparation, the instruments should always conform to and retain the original shape of the canal to maximize the cleaning effectiveness and minimize unnecessary weakening of tooth structure to achieve the optimal result. Ledge formation, blockage, perforation, and apical transportation are undesirable mishaps that can occur during preparation of curved root canals.[13],[14]

The present study aimed to compare the root canal transportation using XPS (single-file) and EndoStar E5 (multiple-file) systems in curved roots of the maxillary first molars using CBCT.

The mesiobuccal root of the maxillary first molars was chosen as they usually present with remarkable curvatures and had mesiodistal flattening.[15] Teeth having root curvature ranging from 15° to 30° were selected. Curved canals were selected for this study because they present greater challenges to instrumentation.[16] In the present study, three levels were chosen: 3, 5, and 7 mm. These measurements represent the apical, middle, and coronal thirds of the root canals where curvatures with high vulnerability to iatrogenic mishaps typically exist.[11] The apical preparation was standardized to size 30 so as to keep uniformity in the apical preparation of all samples.

In the intergroup comparison, with respect to canal transportation, no statistically significant difference was observed in transportation at 3 mm, 5 mm, and 7 mm mesiodistally; further, no statistical significance was observed at 3 mm and 7 mm buccolingually.

EndoStar E5 has shown no canal transportation at all three levels mesiodistally, and also buccolingually, these results can be attributed to its S-shaped cross-sectional design, resulting in aggressive cutting edges, positive rake angle, and helical pitch which increases from tip to handle; this design is claimed to reduce core diameter and increase flexibility. Transportation is determined by flexibility and movement of instrument during canal preparation. Thus, Rotary EndoStar E5 easily fits in most curved canals, minimizing risk of canal transportation.[17],[18]

XPS has also shown no significant canal transportation at all levels except at middle third buccolingually at 5 mm. These results could be attributed to the fact that XPS made from MaxWire alloy is characterized by superelasticity and shape memory causing no canal transportation. XP Shaper has the booster tip along with expanding type of movement which ensures better centering of the instrument, and its shorter time for preparation minimizes chances of transportation.[19],[20] Marzouk and Ghoneim stated multiple tapers along the cutting length of XPS could be the reason for increased canal transportation in the middle third.[21]

With respect to RDT, intergroup comparison showed that both the groups were effective in maintaining RDT, and this can be attributed to the continuous rotation motion of both the files in Group 1 and Group 2. According to Yoo and Cho as compared to reciprocation, continuous rotation of Ni-Ti files requires less inward pressure, reduces instrument screwing effect, and improves hauling capacity, leading to less dentin removal.[22]

This could be attributed to snake-like motion which is the swirling motion of XPS which causes file to engage and disengage along the wall, thus reducing stress between the file and canal with minimal apical pressure.[23],[24] Thus, the crown-down preparation and triangular cross-section of EndoStar E5 maintains the canal curvature while removing less dentin from surface.[25]

  Conclusion Top

Within the limitations of our study, it can be concluded both the files remained centered in the canal and maintained the original canal curvature while preserving the RDT. This indicates safety in the preparation of root canals with the new single-file system XPS and multiple-file system EndoStar E5.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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