|Year : 2019 | Volume
| Issue : 1 | Page : 89-97
Assessment of shaping ability of rotary and reciprocating file systems using cone-beam computed tomography in mandibular molars: An in vitro study
Anju Abraham, Anika Mittal, Sarita Singh, Aditi Dhaundiyal, Bidya Yendrembam, Shilpa Kumari
Department of Conservative Dentistry and Endodontics, Inderprastha Dental College and Hospital, Sahibabad, Ghaziabad, Uttar Pradesh, India
|Date of Web Publication||19-Jun-2019|
Dr. Anju Abraham
Inderprastha Dental College and Hospital 46/1, Site IV, Industrial Area, Sahibabad, Ghaziabad - 201 010, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Aim: The purpose of this study was to compare the canal transportation, centering ability, canal curvature, dentin removal, the volume of the curved root canals, and time taken during and after instrumentation with Wave One, Reciproc, F360, and One shape (OS) by using cone-beam computed tomography (CBCT).
Materials and Methods: According to the file systems used for canal preparation, eighty mesiobuccal canals of mandibular molars were distributed into four groups (20 samples each): OS (Group 1), F360 (Group 2), Wave One (Group 3), and reciproc (Group 4). According to the manufacturer's instructions, all groups were prepared until size 25 taper. Canals were scanned using CS three-dimensional CBCT scanner (Carestream) before and after preparation at 2 mm, 5 mm, and 8 mm from the apex. The data collected were evaluated using SPSS software with ANOVA and post hoc for a significant difference.
Results: Significant difference was found between the entire group at 2 mm and 5 mm (P = 0.021) and at 8 mm (P = 0.037), where F360 showed the least canal transportation. The mean values for centering ability were not found significant at 2 mm and 5 mm. OS proved to remain more centered than the other groups. Curved canals were instrumented better with minor canal straightening by using Reciproc. The dentin was removed more by using Wave One, whereas least dentin was removed by F360. During pre- and post-instrumentation scans the change in volume of the root canal were not found statistically significant. Wave One showed the maximum increase in the volume of the canal after instrumentation. For the preparation of the canal, the time taken was less with reciproc as compared to other groups.
Conclusion: Therefore, according to the study single-file rotary instrument like F360 used in the continuous rotation is suitable instrument for the root canal preparation followed by Reciproc, OS, and Wave One.
Keywords: Canal transportation, centering ability, cone-beam computed tomography, reciprocating, rotary, volume of the root canal
|How to cite this article:|
Abraham A, Mittal A, Singh S, Dhaundiyal A, Yendrembam B, Kumari S. Assessment of shaping ability of rotary and reciprocating file systems using cone-beam computed tomography in mandibular molars: An in vitro study. Endodontology 2019;31:89-97
|How to cite this URL:|
Abraham A, Mittal A, Singh S, Dhaundiyal A, Yendrembam B, Kumari S. Assessment of shaping ability of rotary and reciprocating file systems using cone-beam computed tomography in mandibular molars: An in vitro study. Endodontology [serial online] 2019 [cited 2019 Jul 23];31:89-97. Available from: http://www.endodontologyonweb.org/text.asp?2019/31/1/89/260536
| Introduction|| |
In the root canal treatment, the important and foremost procedure is the cleaning and shaping of the canal system. The main objective of cleaning and shaping is proper irrigation of the root canal system while preserving the original root canal anatomy.,
Numerous microorganisms are present in the apical third area which makes it most difficult. Apical enlargement helps to reduce the level of microorganisms, but this can also cause iatrogenic problems, such as apical transportation, zip, elbow, and ledge formation.
The greatest advantage of using single file is a tremendous reduction in instrument fracture which helps to decrease the cross contamination and saves both time and cost. Single file NiTi-rotary systems were divided into reciprocating file system, i.e., Wave One and reciproc and in continuous motion file system, i.e., One shape (OS) and F360.
For quicker and safer root canal preparation, fifth generation single file system, i.e., OS (Micro Mega, Besancon, France) is used in rotary motion that consists of one instrument made up of 55-NiTi alloy. This instrument has a 25 tip size and a constant taper of 0.06. The rotational speed for OS is 400 rpm.
The F360 file (KometBrasseler, Lemgo Germany) is a single file system used in rotary motion. Due to its unique S-shaped design and a thin core of the instrument, it helps to promote improved cutting efficiency. This system allows most of the root canal preparation with only two files, with tip diameter of 25 and 35 and taper of 0.04. These files are used in a pecking motion up to the acquired working length.
Rotary instruments might get engaged and/or screw into canals during shaping procedure and consequently, leads to high level of stress. This may frequently lead to instrument separation or deformation. With the reciprocating motion, there is decrease in the risk of instrument fracture as it has a sequence of working mode in counterclockwise (CCW) (cutting direction) and a CW direction (releasing of the instrument).
The reciprocating motion of Ni-Ti instruments is better in many ways as compared to continuous rotation:
- Locking of the instrument into the root canal dentine wall gets reduced
- Reduction in the number of cycles during the root canal preparation, causing less flexural stress on the instrument
- Risk of instrument separation gets reduced.
Reciproc (VDW, Munich, Germany) is used using a reciprocal motion (back-and-forward) with 150° CCW and 30° CW rotation. It has a unique S-shaped cross-section with a noncutting tip and progressive taper with sharp cutting edges. The R25 instrument (Reciproc) has a tip diameter of 0.25 mm with 8% of taper.
Wave One (DentsplyMaillefer, Ballaigues, Switzerland) is another single file system used to prepare the canal completely to a constantly tapering shape. In 2010, the Wave One NiTiFile System was introduced that has a reverse taper, variable helical angle with a noncutting edge. The 150° CCW movement enables the instrument to insert apically. With 30° CW movement, it assures that the instrument does not get locked into the root canal and extreme torsional stress is transmitted onto the instrument.
Currently, in the Wave One single-file system three files are available in 21, 25, and 31 mm of length with a constant taper of 6%–8% (for both ISO 25 and 31).
The present study evaluated and compared the shaping ability of NiTi rotary i.e., OS, F360 and reciprocating file systems, i.e., Wave One and reciproc regarding various parameters such as canal transportation, centering ability, canal curvature, dentin removed, the volume of the root canal and the time taken in mandibular molar curved canals using cone beam computed tomography (CBCT).
| Materials and Methods|| |
Eighty extracted human mandibular molars with two separate mesial canals with intact, mature root apices were selected, disinfected and stored in saline at 4°C until use for this study. The teeth were selected on the basis of their similar characteristics regarding an average length (20–21 mm) and mesiobuccal canal curvature (25°–35°) which was measured according to Schneider's method. Distal roots including the part of its crown were split and discarded at the furcation level.
With the help of an Endo access bur (DentsplyMaillefer) the access opening was performed under a continuous supply of water and the mesiobuccal canals were located using size10K-file. Working length was then determined by inserting the file up to the root canal terminus and subtracting 1 mm from this instrument.
Specimens were divided randomly into four experimental groups (n = 20) [Table 1] according to the NiTi rotary and reciprocating file system used in canal instrumentation.
The apical preparation was achieved till #25 in each group, to gain constant master apical size. During root canal preparation, using ISO #10K file recapitulation was done with 17% EDTA, and frequent irrigation with 2 mL of 5.25% NaOCl after every use of instrument was achieved.
The teeth were placed one by one from the root in an upright position on a modeling wax that was fixed horizontally onto the machine. Pre and postinstrumentation scans were performed using CBCT (CS9000 3D, Carestream Imaging) at two different resolutions: 0.125 and 0.100 mm3 voxel sizes and at 74 kVp and 2.5 mA. The field of view was 5 cm × 5 cm in diameter and in height.
The teeth were then scanned at the level of 2 mm (apical third), 5 mm (middle third), and 8 mm (cervical third) from the root apex, based on the parameters included in the study using CBCT imaging [Figure 1], [Figure 2], [Figure 3], [Figure 4].
|Figure 1: Scanned cone-beam computed tomography images of one shape file systems at different levels|
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|Figure 2: Scanned cone-beam computed tomography images of F360 file systems at different levels|
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|Figure 3: Scanned cone-beam computed tomography images of wave one file systems at different levels|
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|Figure 4: Scanned cone-beam computed tomography images of reciproc file systems at different levels|
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The data collected was then evaluated using SPSS software (IBM SPSS Statistics) for statistical analysis.
Evaluation of root canal preparation
Measurements were noted both before and after instrumentation for the following calculation:
- The formula for canal transportation values calculated at each level is: (x1 − x2) − (y1 − y2)
- Similarly for canal centering ratio at each level its formulated as: (x1 − x2)/(y1 − y2) or (y1 − y2)/(x1 − x2), where x1 is the short distance measured from the mesial end of the root to the mesial end of the unprepared canal, x2 is the short distance from the mesial end of the root to the mesial end of the prepared canal, y1 is measured from the distal end of the root to the distal end of the unprepared canal, and y2 is measured from the distal end of the root to the distal end of the prepared canal [Figure 5]
- Canal curvature was calculated where two equal length of straight lines were used using the three-dimensional (3D)in vivo software. The first line denoted the steadiness of the apical region, followed by the second line representing the middle and coronal thirds of the root canal. After crossing the midpoint from each line, a circle was drawn. The two lines that signified the radius were drawn to the midpoints where the center of the circle was marked. The angle between the radius was calculated, and canal curvature was measured. According to Estrela et al. radius of the curvature <4 mm, was considered as a severe curvature (25°–35°)
- The difference between the preinstrumentation and postinstrumentation area was represented as the amount of dentine removed
- Using the software (3D in vivo) the mesiobuccal canal volume was calculated before and after instrumentation. The images were then transferred in DICOM file format (1024 × 1024 matrix) collected from the CBCT data and transported into the in vivo software
- The working time was calculated using a stopwatch. Time for changing the file and irrigation was excluded.
| Results|| |
All the readings were noted in the master chart. The data were entered into excel sheet and were analyzed statistically using SPSS software. The statistical tests used were ANOVA and post hoc tests.
[Table 2] shows the means difference of canal transportation between OS, Reciproc, Wave one and F360 at 2 mm, 5 mm, and 8 mm and it is statistically significant at each level, wherein at 2 mm, the canal transportation was maximum showed by Wave One followed by Reciproc, OS and least by F360.
|Table 2: Statistical analysis of mean canal transportation values for the tested groups|
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Statistically, significant difference was observed between and within the groups [Table 3]. [Table 4] depicts the mean difference of centering ability between all the groups and at 2 mm and 5 mm the values were not statistically significant (P > 0.05), whereas at 8 mm statistically significant difference was found (P < 0.05). F360 showed the least centering ability at all the levels followed by Reciproc, Wave One and the maximum centering ability was shown by OS.
|Table 3: Comparison of canal transportation between groups and within groups|
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|Table 4: Statistical analysis of mean centering ability values for the tested groups|
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Most deviations were observed at 8mm between the groups [Table 5]. [Table 6] depicts the comparable mean values of canal curvature at pre- and postinstrumentation scans between all the groups and both were not statistically significant. Reciproc maintained the curvature of the canal better, whereas OS showed the least canal curvature. No statistical difference was found in either situation [Table 7].
|Table 5: Comparison of centering ability between groups and within groups|
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|Table 6: Statistical analysis of mean canal curvature values for the tested groups|
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[Table 8] shows the comparable mean values of both pre- and postinstrumentation at 2 mm, 5 mm, and 8 mm and they were statistically significant between all the groups. At 2 mm Wave One showed the maximum removal of the dentin followed by OS and reciproc at 5 mm and 8 mm, whereas F360 showed the least removal of the dentin. Statistical significant difference was observed within and between the groups [Table 9].
|Table 8: Statistical analysis of mean values of dentin removed for the tested groups|
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[Table 10] shows that during both pre- and post-instrumentation the mean values of canal volume between all the groups were statistically not significant. Wave One showed the maximum increase in the volume of the canal after instrumentation and the least removal of the dentinal wall was observed with F360. No statistical difference was found between and within the groups [Table 11].
|Table 10: Statistical analysis of mean volume of the canal values for the tested groups|
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The mean values between all the groups were statistically significant as reciproc showed significantly lower mean preparation time (26.70 ± 1.34) as compared to other groups [Table 12].
|Table 12: Statistical analysis of the mean values for the time taken for preparation (s) for the tested groups|
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| Discussion|| |
The factors contributing for the success of root canal treatment depends on: providing a precise diagnosis; obtaining a proper treatment plan; complete information of the anatomy; morphology (shape) of the tooth; executing proper irrigation, disinfection, and obturation of the root canal system.
For evaluation of canal instrumentation, several techniques have been promoted, such as scanning electron microscope, photographic, and radiographic evaluation. Recently, CBCT has been encouraged for use and it consists of an X-ray beam that is cone-shaped and a detector that captures an area of the cylindrical volume of data in one attainment. CBCT can render cross-sectional slices and produce 3D images that are highly accurate compared with conventional radiographs, have higher resolution, lower radiation dose and are fully quantifiable and eliminates structural superimpositions.
Hence, CBCT was used for the current study where evaluations of the shaping ability of four file systems including Wave One, F360, OS and reciproc on extracted mandibular molars were compared.
In the present study, the degree of canal transportation at each level, i.e., 2 mm, 5 mm, and 8 mm from the apex was calculated according to the formula given by Gambill et al.
On assessing the canal transportation of four file systems at each level [Table 2] and [Table 3], the maximum transportation was showed by Wave One, whereas the least was observed by F360 at 2 mm followed by OS. Furthermore, statistically significant difference was found at all the levels, for 2 mm and 5 mm and 8 mm shown by F360 because of the 4% taper present and the ability to produce a high level of cutting efficiency while respecting the natural root canal morphology.
Alrahabi and Alkady observed in their study that OS and TF showed less transportation than Wave One and ProTaper Next. The decreased apical transportation with OS may be due to its 6% regular taper and its asymmetrical cutting profile which helps to preserve the original canal shape.
Contradictory to our study, You et al. obtained that during instrumentation the reciprocating motion resulted in less apical transportation when compared with continuous rotation motion even in the apical portion.
In the present study, the least centering ability was observed by F360 at all the levels whereas the maximum centering ability was observed by OS, the reason attributed was that it has a variable cross-section at three different levels with 6% taper. However, the mean values of centering ability at 2 mm and 5 mm were not statistically significant (P = 0.596 and 0.304), whereas at 8 mm, statistically significant difference was found (P < 0.001) [Table 4] and [Table 5].
This was in agreement with the study conducted by Saleh et al. where OS and F360 showed better centering ability as compared to reciproc and Wave One because instruments with minimum taper i.e., OS with 6% taper and F360 with 4% taper causes reduced transportation when compared with larger tapered single-file instruments.
On the contrary, results found in the study conducted by Bürklein et al. observed that regarding canal straightening no difference was found between Reciproc, F360, and OneShape file systems.
The current study showed that reciproc maintained the curvature of the canal better, followed by Wave One. There was no significant difference found in both pre (P = 0.592) and postinstrumentation scans (P = 0.372) [Table 6] and [Table 7]. The possible reason for this could be that the reciproc files have increased flexibility, progressive taper with a noncutting tip.
Bürklein et al. also observed in their study that the original anatomy of severely curved canals in extracted teeth was maintained properly by Reciproc, Wave One and OS.
According to Anil Dhingra and Parimoo; there was a significant difference found in remaining dentine thickness of the tooth where it was recorded that OS system removed less residual dentine than Wave One. However, in the present study Wave One showed the maximum removal of dentin as compared to other groups whereas the least removal was done with F360 [Table 8] and [Table 9]. The reason attributed was the differences in the cross-sectional designs and tapers of reciproc and Wave One.
[Table 10] and [Table 11] observed that Wave One showed the maximum increase in the volume of the canal after instrumentation and the least was seen with F360. There was statistically no significant difference found between all the groups for both pre- (P = 0.849) and post-instrumentation scans (P = 0.781). As Wave One has greater taper (0.08), it can be concluded that this feature could be related to the significant increase in canal width and apical region being rounded.
This was in agreement with the study conducted by Rashid and Saleh where the F360 file system (4% taper) eliminates less resin than OS (6% taper). These differences were due to the alteration in their taper.
The time taken for the preparation in the present study was less with reciproc than the other groups [Table 12] which might be due to the high speed of rotation used during instrumentation. As Bürklein et al. concluded that the single-file systems were considerably faster by up to 60% in preparation than the multiple-file systems.
| Conclusion|| |
- Reciproc showed the maximum canal transportation whereas F360 showed the least canal transportation at 2 mm
- The mean values for centering ability were not found significant at 2 mm and 5 mm where OS proved to remain more centered in the canal than the other groups
- Curved canals were instrumented better with minor canal straightening by using one instrument in reciprocating motion, i.e., reciproc
- The dentin was removed more by using Wave one, whereas least dentin was removed by F360 and the result was statistically significant.
- Wave One showed the maximum increase in the volume of the canal after instrumentation and the least was observed with F360. There was statistically no significant difference found between all the groups for both pre- and post-instrumentation scans.
- For the preparation of the canal, the time taken was less with reciproc as compared to other groups.
Therefore, according to our study, single-file instrument like F360 used in continuous rotation are suitable instruments for the root canal preparation followed by Reciproc, OS, and Wave One. However, further studies should be conducted to investigate specifically the performance of new endodontic instruments within the root canal with different techniques and parameters.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12]