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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 6  |  Issue : 1  |  Page : 8-12

Micro-computed tomographic analysis of filling porosity of two different obturation techniques


1 Department of Restorative Dental Sciences, Endodontic division, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
2 College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia

Date of Web Publication12-Mar-2019

Correspondence Address:
Amal A Almohaimede
Department of Restorative Dental Sciences, Endodontic division, Dental College, King Saud University, P. O. Box 5967, Riyadh 11432
Kingdom of Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sjos.SJOralSci_43_18

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  Abstract 


Introduction: The ideal root filling material should have inert properties, good adhesive ability, and result in void-free obturation along the root canals. The aim of this in vitro study was to compare the quality of two root canal obturation techniques; cold lateral (CL) condensation and continuous wave (CW) condensation, through measuring the volume of gaps and voids by using micro-computed tomography (micro-CT).
Materials and Methods: Forty-extracted teeth with single canal were instrumented with profile rotary files, and divided into two groups as follows: CL condensation (n = 20), and CW obturation (n = 20). The teeth in each obturation group were scanned twice using micro-CT scan. The resultant images were rendered in proprietary software (NRecon version 1.6.9.4) to obtain three-dimensional (3D) pre- and post-obturation records of each specimen. The 3D images were imported into CT Analyser version 1.17.7.2 for volume measurement of voids and gaps in the apical third at 1 mm, 3 mm, and 5 mm. The analysis of variance test was used to compare the mean volume of voids and gaps between the two obturation groups in each level in the apical third (1 mm, 3 mm, and 5 mm). Furthermore, it was used to compare the mean volume of voids and gaps between the three different levels apically in each obturation technique.
Results: CW obturation technique had more voids volume at the three different apical levels (1 mm: 0.19 ± 0.16, 3 mm: 0.76 ± 0.81, and 5 mm: 1.36 ± 1.44) compared to CL condensation technique at the same three levels (1 mm: 0.14 ± 0.21, 3 mm: 0.46 ± 0.46, and 5 mm: 1.10 ± 0.93) with no statistical significant difference between them (P < 0.05).
Conclusions: None of the root canals filled teeth were voids-free, and there was no statistically significant difference between the two obturation techniques regarding the gaps volume apically.

Keywords: Cold lateral condensation, continuous wave condensation, filling techniques, micro-computed tomography, obturation


How to cite this article:
Almohaimede AA, Almutairi MM, Alyousef HM, Almadi EM. Micro-computed tomographic analysis of filling porosity of two different obturation techniques. Saudi J Oral Sci 2019;6:8-12

How to cite this URL:
Almohaimede AA, Almutairi MM, Alyousef HM, Almadi EM. Micro-computed tomographic analysis of filling porosity of two different obturation techniques. Saudi J Oral Sci [serial online] 2019 [cited 2019 Mar 24];6:8-12. Available from: http://www.saudijos.org/text.asp?2019/6/1/8/254030




  Introduction Top


The outcome of endodontic treatment does not only rely on proper disinfection process, but also on tight-sealed fillings of the canals to prevent the leakage of fluids, and the penetration of any microorganism and toxic bacterial products into the periapical tissues.[1] Therefore, a root-filling material is necessary to obturate the root canal in fluid-tight seal three-dimensionally on the main and accessory canals. The ideal root filling material should have inert properties, good adhesive ability, and result in void-free obturation along the root canals.[1] Gutta-percha is the most widely used obturation material due to its biocompatibility, inertness, dimensional stability, compactability, and ease of removal.[2]

There are different techniques that are used to obturate the root-canal system. Cold lateral (CL) condensation is the most widely used and considered to be the gold standard technique.[3],[4],[5] In 1996, Buchanan created the continuous wave (CW) obturation technique, which was a modification of Schilder's warm vertical condensation technique.[2] This obturation technique is considered less time consuming, provides less microbial coronal leakage, and adapts better to grooves and depressions of the canal walls and lateral canals than CL compaction.[6]

Some studies reported that fillings created using thermal methods demonstrate better adaptation than those using cold Gutta-percha.[7],[8] While others suggested the opposite.[9],[10] Therefore, no clear consensus exists on the efficacy of root canal filling methods.

The aim of the present study was to compare the obturation quality of two endodontic root canal filling techniques, CW condensation technique and CL condensation technique, through measuring the volume gaps and voids using micro-computed tomography (micro-CT).


  Materials and Methods Top


This study protocol was approved by the ethics committee at King Saud University, College of Medicine (IRB Project No. E-17-2641), and registered at the College of Dentistry Research Center (CDRC No. IR 0253).

A pilot study was carried out with two teeth in each of the obturation techniques to decide either to take one image (after obturation) or two superimposed images (after instrumentation and after obturation) using micro-CT scan.

Teeth preparation and obturation

Forty permanent extracted human teeth with single canals were collected and stored in 0.1% thymol solution. Teeth with calcified canals, dilacerated root, internal and external root resorption, fracture or immature apex, and root caries were excluded. The teeth were decoronated with a diamond wheel saw to achieve a length of 12 mm, the pulp was extirpated, and an initial working length with size 15K file was taken. The roots were instrumented using crown down technique with Profile nickel-titanium rotary files (DENTSPLY Maillefer, Switzerland). The sequence of file usage was file size 0.06/40, followed by 0.06/35, 0.06/30, 0.06/25, and 0.06/20.[11] Irrigation was done with a 5.25% sodium hypochlorite solution by using a 27G monoject needle. The canals were dried with paper points and divided randomly into two groups for obturation as follows: Group 1 (n = 20): CL condensation technique was used; a master cone of Gutta-percha (Sure Dent CO., Korea) corresponding to the final instrumentation size 0.06/40 and length of the canal is coated with AH Plus root canal sealer (DENTSPLY, Germany), inserted into the canal, laterally compacted with spreaders and filled with additional accessory cones size 0.02/15 (Spident, Korea).[11] Group 2 (n = 20): CW condensation technique was used; it is essentially a vertical compaction (down-packing) of core material (Gutta-percha, k3, USA) size (0.06/40) and AH Plus sealer (DENTSPLY, Germany) in the apical portion of the root canal using a heating device (System B, BL, USA), and then the remaining portion of the root canal was backfilled with thermoplasticized core material (Gutta-percha obturator, Sure Dent Co., Korean) using injection device (Obtura, BL, USA).[12] All teeth were stored for 72 h at 37°C and 100% humidity in air-tight containers.

Scanning teeth with micro-computed tomography scan

Each tooth was mounted on a custom-made holding device for imaging in a micro-CT scanner (Skyscan 1172, Bruker micro-CT, Kontich, Belgium) operating at 100 kV, 100 uA, 0.700° rotation steps, and 11.40 μm pixel size of the camera. Images were taken twice for each tooth in each group, before and after the obturation procedure. The resultant images were rendered in proprietary software (NRecon version 1.6.9.4) to obtain three-dimensional (3D) pre- and post-obturation records of each specimen. The 3D images were imported into CT Analyser version 1.17.7.2 for volume measurement.[13]

Finally, the micro-CT scan was used for the 3D volumetric visualization and analysis of the quality of the root canal filling material at the apical third (at 1 mm, 3 mm, and 5 mm), through measuring the volume of gaps and voids [Figure 1] and [Figure 2].[14]
Figure 1: Representative reconstruction of the filling material and cross-section of the root canal at three levels apically in one of the teeth within CL condensation group (the arrows point to the voids): (a) At 1 mm apically, (b) At 3 mm apically, (c) At 5 mm apically

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Figure 2: Representative reconstruction of the filling material and cross-section of the root canal at three levels apically in one of the teeth within CW condensation group (the arrows point to the voids): (a) At 1 mm apically, (b) At 3 mm apically, (c) At 5 mm apically

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Statistical analysis

Data were analyzed using SPSS software Version 17 (SPSS Inc., Chicago, IL, USA), using descriptive statistics. The analysis of variance test (ANOVA) was used to compare the mean volume of voids and gaps apically (1 mm, 3 mm, and 5 mm) between the two different obturation techniques (CW and CL), and between the three different levels (1 mm, 3 mm, and 5 mm) within the same technique. The level of significance 0.05 was used to compare the P value. A value of P < 0.05 was considered to be statistically significant.

Null hypothesis (H0)

There will be no statistically significant difference in the obturation quality of the two endodontic root canal filling techniques, CW and CL, regarding the volume gaps and voids measured using micro-CT scan.

Alternative hypothesis (Ha)

There will be a statistically significant difference in the obturation quality of the two endodontic root canal filling techniques, CW and CL, regarding the volume gaps and voids measured using micro-CT scan.


  Results Top


Results showed that CW obturation technique had more voids/gaps volume at the three different apical levels (1 mm, 3 mm, and 5 mm) compared to CL condensation technique at the same three levels. However, there was no statistically significant difference between the two obturation techniques [Table 1].
Table 1: Mean and standard deviation of volume of voids at 1, 2, and 3 mm among samples in the continuous wave and cold lateral groups

Click here to view


In the CW obturation group, the voids/gaps volume was higher coronally within the apical part (1 mm <3 mm <5 mm), with no statistically significant difference between 1 mm and 3 mm (P = 0.15), and between 3 mm and 5 mm (P = 0.13). However, there was a statistically significant difference between 1 mm and 5 mm (P = 0.001).

In the CL condensation group, the voids/gaps volume was also higher coronally within the apical part (1 mm <3 mm <5 mm), with no statistically significant difference between 1 mm and 3 mm (P = 0.244), and between 3 mm and 5 mm (P = 0.004). However, there was a statistically significant difference between 1 mm and 5 mm (P = 0.000).


  Discussion Top


Several factors contribute to the success of root canal treatment. An adequately prepared and filled root canal acts as one of these factors.[15],[16] However, voids can be entrapped during root filling procedures, especially if they involve multiple steps.[17] Internal voids, those that are not in communication with the canal walls, are considered less dangerous for the endodontic prognosis because the bacteria they might contain are imprisoned in an unfavorable environment.[18] Both external or combined voids constitute a gap between the filling materials and the canal walls and represent a space where bacteria can grow, and leakage occurs due to the failure of the sealer.[19] To avoid these gaps and to improve the quality of obturation, several obturation techniques, and materials were introduced.[7]

In this study, the quality of CL condensation and CW condensation techniques were compared for the presence of voids and gaps apically.

Micro-CT is a high-resolution technology and 3D analysis that has been used in many fields of dentistry including endodontics. This technology allows the visualization of filling materials, voids, and tooth structures with high accuracy and spatial resolution.[20] It was used in this study because it is highly accurate, noninvasive, and reproducible technology that enables a precise 3D quantitative evaluation of the presence of gaps and voids in root canal filling material.[21] Moreover, this technique not only overcomes the limitations of two-dimensional images but it may also limit potential operator bias in the interpretation of the results.[22]

Based on the present study results, voids were detected in all samples, and there was no significant difference in voids/gaps volume at the three different apical levels between both obturation techniques (CW and CL). However, the CW condensation technique showed more voids than CL condensation at the three apical levels (1 mm, 3 mm, and 5 mm). These findings were in contrast with a previousin vitro study, where their results showed that modified CW condensation technique resulted in better adaptation of Gutta-percha to canal walls than CL technique at all cross-sections with fewer voids and faster obturation time compared to other techniques.[18],[21] Another group also demonstrated that CL condensation technique resulted in lower filling densities in isthmuses in the apical region of the canals of human mandibular first molar mesial roots than continuous wave technique.[23] The reason could be the use of heat-softened Gutta-percha resulted in a better homogenous mass with fewer voids and improved adaptation to the canal walls in CW technique.[24],[25] On the other hand, KeÇeci et al. compared both obturation techniques, CL and continuous wave, and assessed the distribution of filling material by measuring areas of sealers, Gutta-percha, and voids using stereomicroscope.[26] Their results showed a similar distribution of filling materials in both obturation techniques.

The results of our study can be explained by air entrapment in-between the increments of filling materials that leads to voids formation in CW condensation techniques.[27]

In the current study, AH Plus sealer was used in both techniques. The use of this sealer is convenient for warm compaction procedures because it is heat tolerant and its setting reaction is not influenced by thermoplastic obturation techniques.[28]

It is important to obturate the entire root canal length. However, the apical seal is considered to be the most crucial factor for the success of root canal treatment. All the measurements were done for the apical third in our study. It was suggested that 60% of root canal treatment failures could be attributed to reentry of microorganisms from the peri-radicular area into the incompletely obturated root canal. Therefore, the apical sealing property of root canal filling materials is considered the most essential when obturating the root canal space.[27],[29]


  Conclusions Top


None of the root canal filled teeth were voids-free. There was no difference in voids and gaps volume between the two obturation techniques (CW and CL).

Acknowledgment

The authors would like to acknowledge the Dental Biomaterials Research Chair at King Saud University for their efforts and help.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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