Apical transportation induced by reciprocating files in removal of GuttaCore and single- cone from curved root canals: A micro-CT analysis

doi:10.21203/rs.3.rs-2991378/v1

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Apical transportation induced by reciprocating files in removal of GuttaCore and single- cone from curved root canals: A micro-CT analysis

https://doi.org/10.21203/rs.3.rs-2991378/v1

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Objectives: Endodontic instruments tend to diverge from the long axis of root canal during preparation. This tendency increases with increasing canal curvature and retreatment cases. The purpose of this study was to assess and compare the apical transportation induced by different reciprocating single file systems in curved canals obturated with GuttaCore and single-cone obturation techniques using microcomputed tomography.

Materials and methods: Sixty-four mandibular molar teeth with root canal systems that have two independent severely curved canals in the mesial root have been chosen for the current study. The root canals have been instrumented with WaveOne Gold primary file and obturated by Single-cone and GuttaCore obturation techniques. First micro-CT scan has been taken and the samples have been subdivided into 4 groups for each obturation technique (n=16 canals each group) according to the retreatment system: Group R: Reciproc (R25 file), group RB: Reciproc Blue (R25 file), group WO: WaveOne (Primary file 25) and group WOG: WaveOne Gold (Primary file 25). After the retreatment procedures, the second micro-CT scan has been taken and then the apical transportation at 2, 3 and 4 mm from the apex were calculated.

Results: Apical transportation caused by Reciproc and WaveOne groups was significantly higher than the Reciproc Blue and WaveOne Gold groups.

Conclusion: Under the circumstances of the current study, Reciproc and WaveOne files caused higher apical transportation than the Reciporc Blue and WaveOne Gold files. The lowest apical transportation occurred at 2 mm from the apex.

Clinically relevant: The use of Reciproc blue and WaveOne Gold files can be considered safer in the removal of GuttaCore and single-cone obturation materials

Reciproc

Reciproc Blue

WaveOne

WaveOne Gold

GuttaCore

Single-cone

severely curved root canal

Micro-CT

Root canal retreatment is a common procedure used to treat teeth that have failed previous root canal treatment. [17]. The goal of retreatment is to remove the old filling material, disinfect the root canals, and then fill them with a new material [‎30].

One of the challenges of root canal retreatment is the potential for apical transportation during filling removal in curved canals and can make it difficult to achieve adequate cleaning, disinfection, and refilling. Additionally, apical transportation may favor apical extrusion of irrigation solution, debris and/or filling materials [‎29,‎16].

The single file systems are the product of the latest revolution and development of endodontic instruments science concerning cross-sectional design and alloy treatment. These files have shown to be more successful and efficient in root canal preparation than conventional multifile systems in addressing additional walls of the root canal systems. Their enhanced mechanical capabilities make them appropriate for the effective removal of gutta-percha [‎4,‎7].

The Reciproc (VDW) and WaveOne (Dentsply Sirona) file systems, which are single file systems with different cross-sectional designs. Those two file systems are used in reciprocation mode and were developed utilizing M-Wire technology. M-Wire files can be more safely used in curved canals, and they are more fatigue resistant than traditional nickel-titanium (NiTi) alloy files [3,‎44].

he upgradation of Reciproc and waveOne single-file system has generated Reciproc Blue (VDW) and waveOne gold (Dentsply Sirona) file systems. Both are manufactured utilizing a brand-new heat treatment technique which significantly improved strength and flexibility of those files compared to their predecessors [‎15,‎43,‎13].

Carrier-based obturation systems have been developed to simplify root filling procedures. However, in retreatment cases, carrier-based systems removal may be more time-consuming and more difficult to be removed [19, 9]. A new core-carrier system was introduced by the manufacturer of Thermafil (Dentsply Sirona) that consists of a cross-linked gutta-percha core (GuttaCore) instead of a plastic carrier. [25].

In endodontics, it is quite uncommon to encounter a tooth with straight root canals because most teeth display some degree of curvature (‎10). Teeth with curved roots make it extremely difficult to completely disinfect the canals and remove the obturation material [‎5].

Micro-computed tomographic (micro-CT) imaging provides a reliable, non-invasive method for evaluating root canals in three dimensions (3D). Comparing the effects of various files on the removal of different obturation materials in severely curved canals during non-surgical retreatment procedures using micro-computed tomographic imaging is limited in the literature [‎1].

Therefore, this study aimed to measure and compare the apical transportation induced in the removal of different obturation materials (single-cone and GuttaCore) in the curved root canal systems retreated with Reciproc, Reciproc Blue, WaveOne, WaveOne Gold files using micro-computed tomographic imaging.

Sample selection

Sixty-four extracted human lower (mandibular) molar teeth have been selected under the inclusion criteria and soaked in thymol 0.1% until use. The extracted teeth have been examined by CBCT for the following inclusion criteria: Mesial roots with type IV Vertucci’s classification [45], with completely formed apex, no canal calcification; no previous root canal treatments and no external or internal resorption. After access cavity preparation, the radius and angle of curvature of the teeth have been examined using standardized periapical radiographs.

The root apex of each tooth has been embedded in wax and mounted for radiography in order to keep it in a constant and stable position. The dental sensor has been positioned in the paralleling device with the center of the X-ray beam aligned perpendicular to the root canal and the long axis of the root canal being parallel and as close to the surface of the sensor as possible.

All radiographs have been taken at the same source-to-sensor and object-to-sensor distances with the same exposure time. A computerized program for processing digital images (AutoCad 2021 v.24.1 program) was utilized to calculate the canal curvature degree and radius. [12].

The angle and radius of the root canals curvature have been measured using Schneider’s and Schafer’s method. (‎40; ‎39). Teeth with root canal curvatures 25–40 angle and radius curvatures of curvature between 1.23–2.57 mm have been selected.

Preparation and instrumentation of the samples

The teeth crowns have been flattened with a diamond disc to obtain an 18-mm tooth length, initially established with a digital caliper. K-file no.10 had been scouted into the canal to the level when it becomes visible in the apical foramen, then 0.5 mm have been subtracted, and the determined length have been the working length. The glide path has been created using a no. 15 K-file

Each tooth has been placed in polyvinylsiloxane impression material and stabilized on a vise to clinically simulate the alveolar position. All endodontic procedures were performed with the roots being in the aforementioned stabilized position [‎34].

The WaveOne Gold (Dentsply Sirona) primary file with the endomotor device (VDW Silver) have been used to instrument all canals. The WaveOne All mode has been chosen in the devise. The file has been taken out, cleaned, and the canals have been irrigated with 2 ml 5.25% sodium hypochlorite (NaOCl) after each of three pecking movements instrumenting the canal. During the final irrigation, 1 ml 17% EDTA was applied for 1 minute, followed by 1 ml 5.25% NaOCl for 30 seconds, and finally 1 ml normal saline. With paper points, the root canals have been dried.

Root canal obturation

The instrumented teeth have been divided into two obturation techniques (32 teeth: 64 canals each):

Group SC: Single-cone technique

Using single point gutta-percha and AH Plus (Dentsply Sirona) canal paste, each canal has been obturated.

Group GC: GuttaCore technique

Each canal was obturated using AH Plus (Dentsply Sirona) canal paste and a warmed gutta-percha carrier-based system (Dentsply Sirona) by heating a size 25 GuttaCore obturator in the ThermaPrep heater obturator oven (Dentsply Sirona) and subsequently introducing it into the root canal system at the working length. Following the manufacturer's instructions, the GuttaCore obturator was cut at the cement-enamel junction and compacted.

Following the root canal obturation, the access cavities have been sealed with temporary filling material (Cavit; 3 M ESPE, St Paul, MN). In an incubator with 37°C temperature and humidity of 100%, the teeth were stored for a week to allow the sealers to set.

Skyscan 1275 (Bruker microCT, Kontich, Belgium) micro-CT device was used to separately scan each sample. The parameters that to be used have been as follows: an isotropic voxel size of 18 um with a copper-aluminum filter, x-ray voltage of 80 kV and 125 mA, 360 rotations, and a 0.3 rotation step.

All the samples have been stored in an incubator at 37°C temperature and humidity of 100% for 1 month.

Removal of obturation material

The samples have been randomly subdivided into 4 groups per each obturation technique (n16 canals each) according to the retreatment system to be used. Each instrument has been used in the removal of obturation materials from three canals in each group.

Group R: Reciproc system

The VDW endomotor was utilized with the Reciproc R25 file (tip size 25; variable taper 0.08) in reciprocation Reciproc All mode. According to the manufacturer's instructions, the file was advanced apically using an in-and-out pecking motion with an extent of around 3 mm; light apical pressure was applied with a brushing motion on the lateral walls. The file is taken out of the canal after three pecks, cleaned with sterile gauze, and then 5.25% NaOCl is used to irrigate the canal. Up till the instrument reached the WL, this technique was repeated.

Group RB: Reciproc Blue system

The removal of obturation material has been performed with the Reciproc Blue (RB) R25 file (tip size 25; variable taper 0.08) using the same retreatment technique described for Group R.

Group WO: Wave One system

WaveOne (WO) 25.08 Primary file have been used with the VDW motor set at reciprocation Wave One All mode. The retreatment technique is the same as used in the previous groups.

Group WOG: Wave One Gold system

The WaveOne Gold (WOG) primary file (tip size 25; variable taper 0.07; Dentsply Sirona Endodontics) have been used with the VDW motor set at reciprocation WaveOne All mode. The retreatment technique is the same as used in the previous groups.

Prior to each file reinsertion, around 2 ml of 5.25% NaOCl was used to irrigate the canal, and an overall of 20 ml have been used for each canal. Following the retreatment procedures. 3 ml of 17% EDTA have been used in order to remove the smear layer followed by the final rinsing protocol: rinsing with 3 ml of 5.25% NaOCl for 30 s then 1 ml of saline solution for 30s.

Retreatment is considered complete when each instrument reached the WL for five consecutive times and when there is no remaining filling material visible on the file. The canals have been dried with paper points.

After removal of obturation materials, the samples have been scanned individually employing the same micro-CT device with the same parameters used for the first scan.

Apical transportation evaluation

The horizontal cross-sectional micro-CT images at 2-, 3-, and 4-mm level form the apex have been selected for the apical transportation evaluation. The apical transportation to be measured during the pre- and post-retreatment periods using the method described by Gambill et al, 1996 [‎21]. The formula that was used to measure the transportation is: (X1 – X2) - (Y1 - Y2). In this formula, X1 is the shortest distance from the mesial end of the canal to the mesial end of the root, and Y1 is the shortest distance from the distal end of the canal to the distal end of the root; X2 and Y2 are the shortest distances between the mesial and distal corners after the retreatment (Fig. 1). If the result is 0, this means that there is no apical transportation. Negative results show that the transportation is toward the furcation (distal side), whereas positive results indicate that the transportation is backwards (mesial side).

Statistical analysis

Descriptive statistics: Means, standard deviations, tables and charts were used. For the evaluation of normality of data, the Kolmogorov-Smirnov test was used.

Kruskal Wallis, Mann-Whitney U, Dunn tests were used in the evaluation of apical transportation for comparison between the experimental groups. All the results were analyzed utilizing IBM SPSS Statistic software (v.25.0; IBM Corp).

All the four files induced transportation to some extend (Fig. 2)

1. Apical transportation induced by different file systems used in the removal of single-cone obturation materials.

Table 1 and Fig. 3 presents and summarize the descriptive and statistical analysis of intergroups and intragroup results of apical transportation. It can be observed that the lowest mean of apical transportation is at the 2mm of RBSC group (-0.02 mm) while the highest value of apical transportation is at the 4mm of RSC group (0.127 mm). Intergroup comparison shows that there was statistically significant difference (P < .05) between the four groups in all measured levels. RSC and WOSC were significantly different from RBSC and WOGSC. Comparing the apical transportation at the three levels in each group after removal of obturation materials, RSC, WOSC and WOGSC presented higher AT at the 4mm (0.127 ± 0.074), (0.084 ± 0.12) and (0.032 ± 0.029) respectively, while RBSC presented higher AT at the 3mm (0.026 ± 0.037). Intragroup comparison shows that no significant difference observed between the 2mm, 3mm and 4mm in the WOSC group while there is significant difference between the three levels in other groups. 2mm were significantly different from 3mm and 4mm in the RBSC group. In the RSC and WOGSC groups 2mm were significantly different from the 4mm.

Table 1

Mean and standard deviation (± SD) of apical transportation (mm) of each group after removal of Single-cone obturation materials, considering root canal levels
Level			Study groups (Mean ± SD)
Level		N	RSC	RBSC	WOSC	WOGSC		P-values
2mm		16	0.044 ± 0.046 A^a	-0.02 ± 0.03 B^a	0.041 ± 0.045 A		0.009 ± 0.026 B^a	0.000**
3mm		16	0.067 ± 0.038 A^ab	0.026 ± 0.037 B^b	0.046 ± 0.041 A		0.021 ± 0.022 B^ab	0.003**
4mm		16	0.127 ± 0.074 A^b	0.023 ± 0.09 B^b	0.084 ± 0.12 A		0.032 ± 0.029 B^b	0.000**
P-values			0.000 **	0.006**	0.46		0.04*
	Kruskal Wallis test was performed for statistical analyses. The pairwise comparisons were examined in nonparametric comparisons for all pairs using Dunn method for joint ranking. * Significant difference at the 5.0% level ** highly Significant difference at the 5.0% level Different uppercase letters in rows represent statistical difference between evaluated groups. Different lowercase letters in column represent statistical difference between the evaluated millimeters in each group. (P < .05)

2. Apical transportation induced by different file systems used in the removal of GuttaCore obturation materials.

Table 2 and Fig. 4 presents and summarize the descriptive and statistical analysis of intergroups and intragroup results of apical transportation.

The WOGGC group at 2mm presented the lowest transportation, evidenced by the lowest mean values (0.004 ± 0.02), while the WOGC group at 2mm presented the highest values (0.104 ± 0.041) of apical transportation

Inter group comparison showed significant differences (P < .05) between the groups at 2mm and 3mm levels, RGC and WOGC were significantly different from RBGC and WOGGC at 2mm, WOGC were significantly different from the other three groups at 3mm. No significant difference was observed between the four groups at 4mm level.

Comparing the apical transportation at the three levels in each group after removal of obturation materials, WOGC and RBGC presented higher AT at the 2mm (0.104 ± 0.041), (0.073 ± 0.062) respectively, while RBGC and WOGGC higher AT at the 4mm (0.045 ± 0.034), (0.04 ± 0.093) respectively.

Intragroup comparison shows that no significant difference observed between the 2mm, 3mm and 4mm in the RGC group while there is significant difference between the three levels in other groups. 4mm were significantly different from 2mm and 3mm in the RBGC and WOGC groups. In the WOGGC groups 2mm were significantly different from 3mm and 4mm

Table 2

Mean and standard deviation (± SD) of apical transportation (mm) of each group after removal of Guttacore obturation materials, considering root canal levels
Levels		Study groups (Mean ± SD)
Levels	N	RGC	RBGC	WOGC		WOGGC	P-values
2mm	16	0.073 ± 0.062 A	0.026 ± 0.082 B^a	0.104 ± 0.041 A^a	0.004 ± 0.021 B^a		0.000**
3mm	16	0.057 ± 0.05 AB	0.029 ± 0.052 B^a	0.08 ± 0.052 A^a	0.038 ± 0.061 AB^b		0.044*
4mm	16	0.066 ± 0.075	0.045 ± 0.034 ^b	0.023 ± 0.049 ^b	0.04 ± 0.093 ^b		0.657
P-values		0.64	0.033*	0.000**	0.043*

3. Apical transportation induced by different file systems used regardless of the obturation materials removed.

Table 3 and Fig. 5 illustrate the descriptive and statistical analysis of intergroups and intragroup results of apical transportation.

The RB group at 2mm had the lowest apical transportation, evidenced by the lowest mean values (0.004 ± 0.065), while the R group at 4mm had the highest values (0.096 ± 0.08)

Inter group comparison showed significant differences (P > .05) between the groups at 2mm, 3mm and 4mm levels, R and WO were significantly different from RB and WOG.

Comparing the apical transportation at the three levels in each group after removal of obturation materials, R, WOG and RB groups presented higher AT at the 4mm (0.096 ± 0.08), (0.036 ± 0.068) and (0.034 ± 0.068) respectively, while WO presented higher AT at the 2mm (0.073 ± 0.053).

Intragroup comparison shows that no significant difference observed between the 2mm, 3mm and 4mm levels in the R and WO groups while there is significant difference between the three levels in RB and WOG groups. 2mm were significantly different from 3mm and 4mm in the RB and WOG groups.

Table 3

Mean and standard deviation (± SD) of apical transportation (mm) induced by the reciprocating single file systems regardless of the obturation material removed, considering root canal levels
Levels		Study groups (Mean ± SD)
Levels	N	R	RB	WO	WOG	P-values
2mm	32	0.058 ± 0.056 A	0.004 ± 0.065 B^a	0.073 ± 0.053 A	0.007 ± 0.023 B^a	0.000**
3mm	32	0.062 ± 0.044 A	0.028 ± 0.044 B^b	0.063 ± 0.049 A	0.03 ± 0.046 B^b	0.000**
4mm	32	0.096 ± 0.08 A	0.034 ± 0.068 B^b	0.053 ± 0.095 A	0.036 ± 0.068 B^b	.002**
P-values		0.089	0.001**	0.146	0.002**

4. Apical transportation induced by removal of obturation materials regardless of the file systems used

Table 4 and Fig. 6 shows the descriptive and statistical analysis of intergroups and intragroup results of apical transportation.

The SC group at 2mm had the lowest apical transportation, evidenced by the lowest mean values (0.019 ± 0.045), while the SC group at 4mm had the highest values (0.066 ± 0.093)

Inter group comparison showed significant differences (P > .05) between the two groups at 2mm.

Comparing the apical transportation at the three levels in each group after removal of obturation materials, SC group presented higher AT at the 4mm (0.066 ± 0.093), while GC group presented higher AT at the 2mm (0.052 ± 0.068).

Intragroup comparison shows that no significant difference was observed between the 2mm, 3mm and 4mm levels in the induced apical transportation in the GC group. AT induced by the removal of single cone at the 2mm level were significantly different from the 3mm and 4mm

Table 4

Mean and standard deviation (± SD) of apical transportation (mm) induced by removal of obturation materials regardless of the file systems used, considering root canal levels
Levels		Study groups (Mean ± SD)
Levels	N	SC	GC	P-values
2mm	64	0.019 ± 0.045 A^a	0.052 ± 0.068 B	0.016*
3mm	64	0.040 ± 0.039 ^b	0.051 ± 0.056	0.401
4mm	64	0.066 ± 0.093 ^b	0.043 ± 0.067	0.262
P-values		0.000**	0.815

5. Apical transportation induced at the different level of apical third

Table 5 shows that the highest apical transportation was occurred at the 4mm (0.055 ± 0.082) while the lowest apical transportation has been occurred at the 2mm (0.036 ± 0.059)

Statistically there was significant difference between the three levels. 2mm were significantly different from 3mm and 4mm

Table 5

Mean and standard deviation (± SD) of apical transportation (mm) induced in the apical third at different root canal levels
Levels	N	Mean ± SD	P-value	Dunn
2mm	128	0.036 ± 0.059	0.006**	A
3mm	128	0.046 ± 0.049		B
4mm	128	0.055 ± 0.082		B
Kruskal Wallis test was performed for statistical analyses. The pairwise comparisons were examined in nonparametric comparisons for all pairs using Dunn method for joint ranking. ** highly Significant difference at the 5.0% level Different uppercase letters in column represent statistical difference between the evaluated millimeters in all group. (P < .05)

Endodontic instruments tend to diverge from the long axis of root canal during preparation [‎22]. This tendency increases with increasing canal curvature. Root canal transportation increases the risk of ledging, zipping, and perforation, particularly in the apical third, and weakens the tooth structure [20].

In order to ensure creating enough space for irrigation solution and instrument, comprehensive removal of the bulk of obturation material is mandatory. Regardless of the morphology of the root canal systems, the reciprocating files are just as effective in retreatment as the rotary ones [36].

The reciprocating instruments R, RB, WO, and WOG employed in this investigation were not specifically developed for retreatment but have been already tested for this purpose in other studies [‎8,‎28,‎29,‎2,27] with controversial results.

In the present study, GuttaCore were investigated which consists of cross-linked gutta-percha carriers that can be removed during retreatment by simply trephining through the core [38]. The brittleness of GuttaCore’s carrier, insolubility in solvents, heat resistance, and inability to remove the core in one piece are all potential drawbacks to its retrieval [‎18].

In this study for standardization, the same tip size of 0.25 of the four file systems was used since the larger file of the four systems have different tip sizes. Additionally, the removal of too much dentine could induce dentinal defects that may lead to vertical root fracture [‎42]. Nevertheless, the use of the same file tip size or larger than that used for the initial canal instrumentation is mandatory for the retreatment procedures [‎8,14].

In the present study, mesial roots of Vertucci’s class IV mandibular molars that have two separated mesial canals were analyzed which are particularly interesting not only because of the anatomical difficulty of the usually curved and narrow canals but also because of the possibility to test both systems in the same root. This strategy reduces the bias related to canal selection. [‎23]

To precisely mimic and simulate the clinical practice, the crowns were maintained and used as a reference for working length and the dentine could create tensions on the files while negotiating the curved part of the canal [‎24].

The samples have been mounted in silicone impression material to simulate periodontal ligaments. The Silicon layer allows limited freedom of movement while avoiding external reinforcement [‎26].

Micro-computed tomography is utilized in this study for assessing the residual filling material, as it is a non-destructive technology that accurately reproduces the tooth in three dimensions without destroying the specimens or losing root material during sectioning [‎1].

In the present study, Apical preparation was limited to size 25, i.e., the choice of the size of the file of each system was based on the fact that with apical preparation larger than size 25, the measurement of apical transportion also tends to increase [‎41]. Thus, consequently, higher apical transport values would be obtained, bringing a bias to the research.

The file systems that are used in reciprocating movement have been implemented in this study to increase the centralization of the preparation and to reduce the risk of deformation of the canals. These points are all related to the relief of the torsional and flexural tensions that occur during reciprocating motion [‎33]. Instruments with this movement have exhibited the ability to maintain the original axis of curved canals [‎11].

Numerous studies have compared the apical transportation caused by different instruments during the preparation of root canals for initial treatment, but only a few have been evaluated for retreatment [29,‎6,‎37].

This study aimed to evaluate the morphological alterations of severely curved root canals represented in apical transportation, resulting from the removal of single cone and GuttaCore obturation materials with four reciprocating single file systems that have different designs and metallurgical properties.

All the files used in this study induced apical transportation to some extent which is in line with previous studies (‎35, ‎27,‎16,29].

The mean apical transport observed in this study ranged from − 0.02 to 0.127 mm, which are within the limit considered acceptable of 0.15mm as exposed by Pinto et al., 2019 [‎32] who evaluated lower molar mesial canals through micro-CT. Some studies in the literature have shown that the prognosis of the canal treatment is not negatively affected when the apical transportation is less than 0.3 mm [‎46]. The maximum transportation value in the present study was 0.127 mm. This indicates that the four reciprocating single files used in this study did not pose risks in terms of complications, such as perforations, stepping, and zipping, in the curved root teeth during the retreatment.

In the current study, three different levels in the apical third of the canals were evaluated, in order to review the apical transportation, which were analyzed in levels: 2, 3 and 4 mm from the apical foramen.

Based on the finding of this study when the four file systems were compared statistically for apical transportation as general (Table 3), and also when single- cone obturation group compared (Table 1), the M-wire files Reciproc and WaveOne files caused statistically significantly greater transportation than the heat-treated Reciproc Blue and WaveOne Gold files at the 2mm, 3mm and the 4mm sections. Files with more flexible structure seem to be less likely to cause transportation (‎46). However, the results of the current study on the contrary to those of the studies conducted by Romeiro et al., 2020 [‎35]; Kırıcı et al., 2020 [‎27] in their study they found no significant difference between Reciproc and Reciproc Blue files in term of apical transportation induced by the two files after the removal of single cone obturation materials.

In the removal of GuttaCore no significant differences were observed between the groups at 4mm level. At 3mm level only WaveOne file group was significantly different from Reciproc Blue. At 2mm level Reciproc and WaveOne files significantly caused more apical transportation than the Reciproc Blue and WaveOne Gold files. However, to date, no research has evaluated the effect of those files on inducing apical transportation during the removal of GuttaCore obturation materials.

Comparing the apical transportation induced in the three levels of apical third of the teeth (Table 5), the lowest apical transportation occurred at 2 mm from the apex and this was significantly different from that occurred in the 3mm and 4mm in this study and in other studies [16,29] which probably is due to the action of the instruments in the cervical third, having been able to result in more direct access to the apical portion of the canal and reducing transport in this level.

Although there was no significant difference between the removal of two obturation materials at 3mm and 4mm, the groups filled with GuttaCore (Table 2) showed a tendency to transport higher at 2mm region which can be explained by the fact that GuttaCore had higher rigidities (indentation resisting ability) as it is stated by Patel and Owen, 2016 [‎31] and this might have caused the file to deviate the obturation materials and the original path of the canal in the more apical location.

Under the condition of this study and according to the numerical measurements, it can be concluded that Reciproc and WaveOne files caused higher apical transportation than the Reciporc Blue and WaveOne Gold files. The removal of GuttaCore induced a tendency to transport higher at 2mm region than the removal of single-cone obturation materials.

Corresponding author

Correspondence to Regir Ramadhan Hassan¹

[email protected]

Declaration Section

Corresponding author

Correspondence to Regir Ramadhan Hassan¹

[email protected]

Author contributions

Regir Ramadhan Hassan and Abdulkareem Ramadhan Ibrahim contributed to the design and implementation of the research, to the analysis of the results and to the writing of the manuscript.

Ethics Approval and Consent to Participate

Not applicable

Funding

No funding was obtained for this study.

Conflict of interest

All the Authors have no conflict of interest.

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Apical transportation induced by reciprocating files in removal of GuttaCore and single- cone from curved root canals: A micro-CT analysis

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Abstract

Figures

Introduction

Material and methods

Sample selection

Preparation and instrumentation of the samples

Root canal obturation

Removal of obturation material

Apical transportation evaluation

Statistical analysis

Results

1. Apical transportation induced by different file systems used in the removal of single-cone obturation materials.

2. Apical transportation induced by different file systems used in the removal of GuttaCore obturation materials.

4. Apical transportation induced by removal of obturation materials regardless of the file systems used

5. Apical transportation induced at the different level of apical third

Discussion

Conclusion

Declaration Section

Declarations

Corresponding author

Conflict of interest

References

Additional Declarations

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