|Year : 2020 | Volume
| Issue : 5 | Page : 455-462
Effect of four different root canal obturation techniques on marginal adaptation of bioceramic sealer: An in vitro scanning electron microscopic study
Nawal A Al-Sabawi1, Maha M Yahya2, Njwan F Shehab1
1 Department of Conservative Dentistry, College of Dentistry, University of Mosul, Mosul, Iraq
2 Department of Operative Dentistry, College of Dentistry, University of Mustansiriyah, Baghdad, Iraq
|Date of Submission||25-Feb-2020|
|Date of Decision||13-Apr-2020|
|Date of Acceptance||15-Apr-2020|
|Date of Web Publication||21-Oct-2020|
Dr. Nawal A Al-Sabawi
Department of Conservative Dentistry, College of Dentistry, University of Mosul, Al Majmoaa Street, Mosul.
Source of Support: None, Conflict of Interest: None
Aim: Successful endodontic treatment can be achieved with techniques and materials that have the ability to seal root canal space. The aim of this study was to investigate the effect of four techniques of obturation (single cone [SC], cold lateral [CL], continuous wave [CW], and carrier based [CB]) on the marginal adaptation of bioceramic sealer to the root canal walls using scanning electron microscope (SEM). Materials and Methods: Forty, single-rooted lower premolars were included in this study. The teeth were segmented at the level of cementoenamel junction (CEJ). Then, root canals were shaped with rotary ProTaper nickel–titanium (NiTi) files to F3. Instrumented teeth were assigned randomly into four experimental groups (n = 10/group) as follows: (1) SC, (2) CL, (3) CW, and (4) CB. EndoSequence BC sealer was used for the four groups. After root canal obturation, the roots were horizontally cut into three levels and the interface was examined under SEM in the apical, middle, and cervical thirds of each group. The data collected were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc multiple range tests at P ≤ 0.05. Results: CW of obturation technique showed the best marginal adaptation and the least mean of gaps along the interface between the obturating material and the root canal dentine at all sections of the root (apical, middle, and coronal), followed by the CL technique. Also, results found that CW and CL were significantly different from SC and CB techniques. Conclusion: Techniques of obturation had an effect on the marginal adaptation of bioceramic sealer to the root canal walls. CW technique showed the best marginal adaptation for bioceramic sealer followed by the CL technique. Less marginal adaptation was observed in the SC and CB techniques.
Keywords: Carrier Based, Cold Lateral, Continuous Wave, Marginal Adaptation, Single Cone
|How to cite this article:|
Al-Sabawi NA, Yahya MM, Shehab NF. Effect of four different root canal obturation techniques on marginal adaptation of bioceramic sealer: An in vitro scanning electron microscopic study. J Int Oral Health 2020;12:455-62
|How to cite this URL:|
Al-Sabawi NA, Yahya MM, Shehab NF. Effect of four different root canal obturation techniques on marginal adaptation of bioceramic sealer: An in vitro scanning electron microscopic study. J Int Oral Health [serial online] 2020 [cited 2020 Nov 25];12:455-62. Available from: https://www.jioh.org/text.asp?2020/12/5/455/298800
| Introduction|| |
The optimal goal of root canal obturation is to achieve three-dimensional (3D) seal of the entire shaped and cleaned root canal systems. The success of root canal filling not only depends on endodontic sealer, but also on proper compaction of the gutta-percha against root canal walls. Close marginal adaptation of root canal filling material to the canal walls is required to prevent the formation of gaps between the root canal walls and the root filling material. Gab formation between root filling material and dentinal walls may permit to reinfection of root canal system, leading to endodontic failure. Therefore, hermitic seal of the root canal is required for preventing of microorganism colonization within the root canal systems.
Many root canal sealers used in endodontics, which serve as lubricants for gutta-percha, fill the accessory canals, voids, and irregularities in the root canals, and seal the space between the root filling material and dentinal wall. Recently, calcium-silicate-based materials have been introduced in endodontics and have attracted considerable attention due to their good bioactivity and biocompatibility. EndoSequence BC (also known as iRoot SP) is a premixed, injectable, and ready-to-use calcium-silicate-based sealer (bioceramic). It consists of calcium phosphate monobasic, calcium hydroxide, calcium silicates, zirconium oxide, filler, and thickening agents.
Various obturation techniques have been used in endodontics aiming to achieve marginal adaptation and to minimize the film thickness of the cement to a minimum. Cold lateral (CL) is a widely used technique, but it gives poor compaction of gutta-percha to the canal walls, nonhomogenous, and in between the cones had gaps. But, this technique is still the “gold standard” and is used for comparison purposes in many studies of new obturation systems.
With the advancement of the rotary instrumentation systems, the single cone (SC) has been greatly used. This technique uses larger master cone that to the highest degree match the geometry of the nickel–titanium (NiTi) rotary systems. When the root canal is prepared by rotary instruments, gutta-percha point is used without accessory points. This technique accelerates the root canal filling with minimum application of pressure on the canal walls. Application of SC and sealer in a combination leads to a constant mass, which prohibits failures detected among multiple cones.
Also, there are several thermoplastic obturation techniques used in endodontics including carrier-based (CB) and continuous-wave (CW) techniques. CB is a central carrier (made from plastic or metal such as gold wire, endodontic files, and silver points) with thermoplasticized gutta-percha precoating. It is requested to enhance adaptation of obturation to the root canal, and flow into the lateral canal. CW technique is a combination of vertical (downpack) and thermoplastic injection (backfill). It produced 3D obturation of the main root canals, the lateral and accessory canals, and decreased the risk of root canal fracture.
Different experimental approaches have been used to evaluate the quality of root fillings such as stereomicroscopy, microcomputed tomography, confocal laser microscopy, scanning electron microscope (SEM), digital imaging, acid dissolution of roots, leakage tests, electrochemical method, dye penetration, fluid filtration, and radiographs.,,,,
SEM enabled investigation of the root canal sealer penetration into the dentinal tubules, examination of ultrastructure morphology, and evaluation of the sealer adaptation to the radicular dentinal walls on the different levels of sectioning because it has high depth of field, excellent magnification at the interface, and higher resolution.
Therefore, the aim of this in vitro study was to investigate the effect of four techniques of obturation (SC, CL, CW, and CB) on the marginal adaptation of EndoSequence BC sealer to the root canal walls using SEM.
| Materials and Methods|| |
Forty, single-rooted and caries-free lower premolars were collected from the Department of Orthodontics at the College of Dentistry, Mosul city. The teeth were scaled and polished by using rubber cup and pumice, and then stored in distilled water. Radiographs were taken for each tooth to exclude the teeth with more than one canal, tortuous, and calcified canal. The crown was decoronated using a diamond sectioning disk (KG Sorensen, São Paulo, Brazil) to standardize root fragments of 15 mm length. Pulp extirpation for each root was carried out using a barbed broach (Dеntѕрly-Maillеfеr, Ballaiguеѕ, Switzerland), then K-file size 10 (Dеntѕрly-Maillеfеr) was inserted into the canal to the full working length till it could be observed at the apical foramen. After that, 1 mm was subtracted from this length to assess the working length. Then, each root was fixed in a block of rubber base impression material (Zhermach, Badia Polesine, Italy) for more control of obturation technique. ProTaper NiTi rotary files (Dentsply-Maillefer) were used for instrumentation of the root canals with contra-angled Endo-Motor (Endo-Mate DT, NSK Nakanishi, Tochigi, Japan). Speed was determined at 200rpm and 2N/cm torque according to manufacturer’s instructions. K-file size 15 was pushed within the canal to the 14 mm working length. Then, shaping file S1 was used for shaping the coronal two sections in a brushing motion, followed by shaping file S2 that was used until the full working length was reached. Then, finishing of the instrumentation was performed using F1, F2, and F3 files (Dentsply-Maillefer) in a nonbrushing manner to the full working length. Irrigation with 2-mL 2.5% sodium hypochlorite (NaOCl) (Chloraxid, Poland) was carried out after each file. Then, after completion of instrumentation, the canals were irrigated with 2-mL 17% ethylenediaminetetraacetic acid (EDTA) (PD, Vevey, Switzerland). Finally, rinsing with 5-mL distilled water was used to remove any remnant of the irrigating solution. Then, the canal was dried using ProTaper paper point size F3 (Dentsply-Maillefer).
Samples grouping and obturation techniques
The samples were assigned randomly into four groups (n = 10/group) as follows:
Group 1 (SC): ProTaper gutta-percha size F3 was checked for tug-back to the full working length of root canal. The cone was coated with EndoSequence BC sealer (Brasseler, Savannh, Georgia) and inserted within the canal. Then, the access gutta-percha was sheared off with hot spoon excavator.
Group 2 (CL): ISO-standardized gutta-percha cone size 30 (Dеntѕрly-Maillеfеr) was checked for tug-back to the full working length of canal. Later, the master cone was coated with EndoSequence BC sealer and inserted within the canal. After that, accessory cones (size 20) were coated with a sealer and placed into the canal. Fingered spreader (size 20) was used to compact gutta-percha laterally and apically. Compaction and addition of accessory cones continued till the spreader no further extended than 2–3 mm into the canal. The remaining gutta-percha was sheared off with hot spoon excavator.
Group 3 (CW): Diapen-Diagun cordless obturation system (DiaDent, Korea) was used for this technique. ProTaper gutta-percha size F3 was applied into 1 mm short of the working length and checked for tug-back. EndoSequence BC sealer was also applied as for the first two groups. According to the manufacturer’s instructions, the Diapen’s tip was introduced into the canal to the 4 mm short of the working length, and then rubber stopper was set. Diapen’s devise was set at 200°C temperature mode, then pen tip was placed in the canal orifice, and the middle part of the cone was sheared and compacted for 2s using hand plugger. For coronal back filling, Diagun’s tip set at 200°C was quickly inserted inside the canal, and thermoplasticized gutta-percha (Dеntѕрly-Maillеfеr) was injected into it and pulled out backward till it was completely filled.
Group 4 (CB): Softcore size 30 verifier (SybronEndo, Denmark) was checked out in the canal to the full working length. Then, thermafil obturator size 30 (SybronEndo) was heated in the Softcore DT oven (CMS Dental ApS, Njalsgade 21 G, 2300 Copenhagen, Denmark). EndoSequence BC sealer was applied to the canal, and then the obturator was inserted inside the canal at the working length in a single motion. After cooling, the handle twisted to remove the handle and metal pin of the obturator. Therefore, only the carrier and gutta-percha will be remained in the canal.
In all techniques, hand plugger was used to adapt the gutta-percha vertically. After obturations, composite resin (Dentsply Sirona, USA) was used for sealing all of specimen coronally. Later, to permit complete setting of the sealer, the roots were removed from the blocks and stored for 7 days at 37°C in 100% humidity.
Scanning electron microscopic evaluation
After storage period, the teeth were sectioned horizontally at three different points: one at the cervical third, at the middle, and apical thirds using a minitom (Struers, Ballerup, Denmark) with water irrigation to prevent overheating. A 1-mm-thick section from each third was prepared. Sandpaper was used to remove damages or deformed surface material. Then, the samples were polished, cleaned using 10% orthophosphoric acid for 5s, and then rinsed with air water spray for 15s to eliminate the smear layer. After that, all the specimens were dehydrated by increasing concentrations of ethyl alcohol (BDL Limited Pool, England) (30%, 50%, 70%, 90%, and 100%). Then the specimen mounted with silver paste on metallic stubs, gold coated with sputtering system under vacuum desiccation, and then the internal gaps between the root canal dentine and the obturating materials (at three different randomly selected points of each root specimen) were tested using SEM (VEGA Easy Probe, Germany), at voltage of 10–30kV. Then, photomicrographs were taken at a magnification power of ×500–1000. Then, internal gaps at three randomly selected points in each root specimen and at three different levels (apical, middle, and coronal) were measured, and the mean (micron) was estimated.,,,
The collected data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc multiple range test at P ≤ 0.05, with assistance of Statistical Package for the Social Sciences (SPSS) software, version 19.0 for Windows (IBM, Armonk, New York).
| Results|| |
[Figure 1],[Figure 2],[Figure 3],[Figure 4] show the SEM micrographs of the root canal regions (apical, middle, and coronal) obturated by SC, CL, CW, and CB techniques. [Figure 5] and [Table 1] and [Table 2] show the mean of gaps at the interface between the obturation materials and the root canal dentine for the four experimental groups. Samples that were obturated with the CW of obturation technique showed the best marginal adaptation and the least mean of gaps along the interface between the obturating material and the root canal dentine at all sections of the root (apical, middle, and coronal), followed by the CL technique.
|Figure 1: Scanning electron microscope (SEM) micrograph (500–1000X) of root canal regions (A: apical, B: middle, C: coronal) of Group 1 (single-cone technique) |
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|Figure 2: Scanning electron microscope (SEM) micrograph (500–1000X) of root canal regions (A: apical, B: middle, C: coronal) of Group 2 (cold lateral compaction technique)|
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|Figure 3: Scanning electron microscope (SEM) micrograph (500–1000X) of root canal regions (A: apical, B: middle, C: coronal) of Group 3 (continuous-wave technique)|
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|Figure 4: Scanning electron microscope (SEM) micrograph (500–1000X) of root canal regions (A: apical, M: middle, C: coronal) of Group 4 (carrier-based technique).|
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|Figure 5: Comparison for the differences on the mean gaps width of different techniques at different root sections. |
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|Table 1: Comparison for the differences on the mean gaps width of different groups at different root sections|
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|Table 2: Comparison for the differences on the mean gaps width at different root sections for each group|
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The difference was not significant (P > 0.05) between the apical, middle, and coronal sections in both the CW and CL techniques. Also, results found that CW and CL were significantly different from SC and CB techniques.
The SC technique showed less marginal adaptation and larger mean of gaps especially at the apical section of the root, but the difference was not significant from the middle and coronal sections (P > 0.05). Also the difference was not significant between the SC technique and the CB technique (P > 0.05), except at the apical section in which there was a significant difference.
The larger mean of gaps was observed at the apical section of the root canals that were obturated with the CB technique, but the difference was not significant from the middle and coronal sections (P > 0.05).
| Discussion|| |
The ultimate goals for endodontic treatment are a complete obturation of the root canal space with an inert material and the formation of a hermetic seal. Any defect in obturation is considered the most common cause of failure in endodontics. Various obturating techniques and materials have been advanced to increase the success rate of root canal treatment.
In this study, all samples were shaped with ProTaper NiTi rotary files to F3, which have tip diameter of ISO 0.30 and apical taper of 9%. Rotary system have been popular for preparing root canals, and some studies suggested that this system will result in preparing a canal that is more uniform, better centered, and rounder. It also provides a unique geometries, flexibility, efficiency, safety, and simplicity., NaOCl irrigant at 2.5% has been used in this study for its pulp solvent activity and antimicrobial properties. Smear layer was removed by rinsing with 2 mL of 2.5% NaOCl at the end of instrumentation of the root canals followed by 2 mL of 17% EDTA. Gençoğlu et al. manifested that better gutta-percha adaptation is achieved with two different techniques when the smear layer is removed. Other studies found that the presence of smear layer may impede the penetration of sealers into the dentinal tubules of root canal and also interfere with the adhesion and penetration of thermoplasticized gutta-percha.,
Root canal sealer has a great importance, because a sealing material is essential to adhere the gutta-percha to the root canal walls and to fill lateral canal, accessory canal, void, and irregularities. It has been shown that regardless of the chemical composition of the sealer, adhesive failures between the gutta-percha/sealer and dentin walls may occur. Endodontic sealers may have a reduced union with dentin and gutta-percha, even though the sealer plugs penetrating into dentinal tubules afford mechanical interlocking and better adaptation of the obturation materials. EndoSequence BC was used in this study because it is the most commonly used to date. Various in vitro studies have shown its good antibacterial activity, excellent sealing ability and bond strength, good flowability, low shrinkage, and insoluble properties. It has fine particle size, it consumes moisture in dentinal tubule to harden and set, and its chemical composition was more stronger, which help it to penetrates deeper into the surface microirregularities, as well within the lateral root canals.,,, Several studies have estimated that a common cause of the root canal obturation failure is the presence of porosities and gaps at the sealer–dentin interface. Analysis of the dentin–sealer interface permits the estimation of which material and filling technique could fill the root canals with minimum voids and gaps.,,
In this study, the CW of obturation technique showed the least mean of marginal gaps and was significantly not different from the CL technique. CW that was a single apical master cone was used in combination with a heat source and compression from the heated plugger. Thus, it gives a potent apical seal as well as to fill lateral canals. The CW used a plugger connected to a heat source. This heated plugger is used to compact gutta-percha vertically in one motion.
Therefore, CW has been introduced in an attempt to enhance the obturation of irregularities of the canal, to increase compactness of the filling, and to decrease voids. Olczak et al. found that there are no significant differences for the percentage of content for gutta-percha, sealer, and void of three obturating techniques (CL, CW, and ProTaper thermoplasticized obturator). Also, Crasta et al. used spiral computed tomography to evaluate the volume percentage of root canal filled with gutta-percha of different obturating techniques, and no significant difference was observed between CW and Cl. However, Oh et al. found that filling adaptation and density of filling were inferior in the CL compared to CW. The differences between our study and other previous studies may be related to the differences of methodology, type of sealer, irrigation, and techniques of obturation used.
In this study, the results have verified that the root canals that were obturated with the SC and CB techniques showed less marginal adaptation and larger mean of gaps along the interface between the obturating material and the root dentine, and significantly different from CL and CW. The most important disadvantages of SC appear when the cone was not adaptable with canal irregularities at the middle and coronal thirds of the root canal. Consequently, the sealer accumulates in these areas and also more sealer will be required resulting in poor marginal adaptation, porosities, setting contraction, and dissolution of the sealer. Low marginal adaptation of CB which might be related to Softcore, has less taper core so more friction to the canal walls can result into gutta-percha losing from the carrier particularly in the apical part of the root canal, this may account for the poor adaptation of sealer to the canal. The findings of this study were not consistent with Kabini et al., who reported that CB technique produced good adaptation to the canal walls with least amount of void and gap formation compared with SC. The inconsistency might be related to the differences in method used for evaluation of gap and the type of sealer used.
Regarding the effect of obturating techniques into marginal adaptation of bioceramic sealer to root canal walls, Dabaj et al. evaluated the bond strength of EndoSequence BC to radicular dentine in roots filled with thermoplasticized injectable gutta-percha and CL techniques in comparison with AH Plus sealer. Results showed that AH Plus sealer had higher bond strength than EndoSequence BC, but there was no significant difference between the two EndoSequence BC groups. However, Asawaworarit et al. used SEM and confirmed that EndoSequence BC sealer had higher tubular penetration and better adaptation to the canal wall than AH Plus with CW. Also, Salem et al. evaluated the apical sealing ability of Total Fill BC sealer (new calcium silicate sealer) and AH Plus sealer with SC and CW techniques. They found that Total Fill BC sealer was similar to AH Plus sealer in the apical seal, and SC can produce equivalent seal of canal filling as can be obtained with CW. However, Wang et al. compared the dentinal tubule penetration of iRoot SP and AH Plus sealer using SC and warm vertical compaction technique. The results found that irrespective of the obturating technique used, iRoot SP sealer can achieve comparable obturating quality and better tubular adaptation than AH Plus sealer. Similarly, Huang et al. confirmed with SEM and micro-CT study that EndoSequence BC sealer had equivalent sealing abilities concerning the whole root canal as AH Plus sealer. However, Hegde and Arora concluded that SC results in superior sealing ability of EndoSequence BC compared to CL. Also, McMichael et al. reported that SC and CW produced equivalent dentinal tubular penetration for EndoSequence BC sealer. Similarly, Kim et al. evaluated filling quality of calcium-silicate-based sealer using two obturation techniques (SC and CW), and results found that there was no significant difference between them. However in our study, it was confirmed that CW and CL techniques result in higher marginal adaptation of EndoSequence BC sealer to radicular dentine walls than SC and CB techniques. The differences of this study from other previous studies may be related to the differences in methodology and experimental skill of the authors.
Also, we showed that regardless of the type of techniques used, the mean of marginal gaps between root canal walls and filling material increased from coronal to apical part. This may be attributable to the decrease in the diameter and number of dentinal tubules, and decrease in removal of smear layer in the middle and apical parts area of root canals. These findings agree with the findings of Dabaj et al., Wang et al., and Huang et al., who reported that better sealing ability could be achieved in the coronal and middle parts of the root canal than the apical section.
According to the previous findings, we can conclude that the highest marginal adaptation of bioceramic sealer was in the root canals that were obturated with the CW and CL techniques. Further studies are required to verify this study.
Under the conditions of this study, it was confirmed that the techniques of obturation had an effect on the marginal adaptation of bioceramic sealer to the root canal walls. We observed that the best marginal adaptation of bioceramic sealer was obtained when the CW of obturation and the CL compaction techniques were used for obturation of root canals. Larger marginal gaps were observed with the CB and the SC techniques. Also, it was found that regardless of the type of techniques used, the mean of marginal gaps between root canal walls and filling material increased from coronal to apical part.
We would like to thank College of Dentistry at University of Mosul for its continuous help and support. We would also like to thank Eng. Ahmed A. Saleh for his assistance in statistical analysis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
All the authors Nawal A. Al-Sabawi, Maha M. Yahya, Njwan F. Shehab1 contributed equally in the preparation of the manuscript.
Ethical policy and Institutional Review board statement
This study was approved by Ethics Committee at Department of Conservative Dentistry, College of Dentistry, University of Mosul, Mosul, Iraq (4C/74 in 13/1/2020).
Patient declaration of consent
Informed consent was got from patients to include their teeth in the study.
Data availability statement
The data of the study results are available from the author (Dr. Nawal A. Al-Sabawi, email: [email protected]) on request.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]