|Year : 2014 | Volume
| Issue : 2 | Page : 64-69
Volumetric analysis of root canals obturated with cold lateral condensation, single-cone and thermoplasticized gutta-percha techniques using spiral computed tomography: An in vitro study
Shanol Anusha Crasta, Jyothi Kashi Nanjundasetty, Venugopal Panuganti, Jayashankara Chatra Marigowda, Sharath Kumar, Anil Kumar
Departments of Conservative Dentistry and Endodontics, Sri Siddhartha Dental College, Tumkur, Karnataka, India
|Date of Web Publication||19-May-2014|
Shanol Anusha Crasta
#788/112, 58th cross, 3rd main, 4th block, Rajajinagar, Bangalore 560 010, Karnataka
Source of Support: None, Conflict of Interest: None
Aim: To evaluate and compare the volume percentage of root canals obturated with gutta percha (POV), with various techniques using spiral computed tomography (SCT). Materials and Methods: Forty-five mandibular first premolar teeth were instrumented using Race files and randomly divided into three groups of 15 teeth each (n = 15). The volume of root canal space was measured using SCT and the root canals were obturated as follows: Group 1-lateral condensation, Group 2-single-cone obturation and Group 3-thermoplasticized gutta-percha technique. The filled volume of root canals was measured using SCT and POV was calculated in total and at apical, middle and coronal third individually. The data was statistically analyzed using one-way ANOVA and Tukeys post hoc multiple comparison tests. Results: An intergroup comparison of the mean value of POV showed a statistically significant difference ( P < 0.05) in the middle third and in total when group 1 was compared to group 2. Conclusion: All the groups showed 100% POV at the apical third. Group 2 showed least POV at the middle third of the root canal.
Keywords: Cold lateral condensation, single-cone obturation, spiral CT, thermoplasticized gutta-percha technique, volumetric analysis
|How to cite this article:|
Crasta SA, Nanjundasetty JK, Panuganti V, Marigowda JC, Kumar S, Kumar A. Volumetric analysis of root canals obturated with cold lateral condensation, single-cone and thermoplasticized gutta-percha techniques using spiral computed tomography: An in vitro study. Saudi Endod J 2014;4:64-9
|How to cite this URL:|
Crasta SA, Nanjundasetty JK, Panuganti V, Marigowda JC, Kumar S, Kumar A. Volumetric analysis of root canals obturated with cold lateral condensation, single-cone and thermoplasticized gutta-percha techniques using spiral computed tomography: An in vitro study. Saudi Endod J [serial online] 2014 [cited 2019 Nov 20];4:64-9. Available from: http://www.saudiendodj.com/text.asp?2014/4/2/64/132720
| Introduction|| |
The most important factors for successful root canal treatment are biomechanical instrumentation, disinfection of the "corridors of sepsis" and three-dimensional (3D) obturation of this root canal space that is challenging.  Voids created by inadequate fusion of the gutta-percha (GP) cones, penetration of bacterial toxins and their flow into periapical tissue from oral cavity jeopardize the endodontic treatment success.  The Washington study of endodontic success and failures indicates that nearly 60% of the failures is apparently caused by incomplete obturation and it is indispensable that the obturation should have a fluid tight seal. 
Among several materials developed for obturation, GP is the most popular one whose physical properties have made it possible to use it in several different techniques with differing opinion regarding the effective sealing of root canals. 
Cold lateral condensation is the technique of choice by many dental practitioners for years and serves as the gold standard against the new techniques for comparison and has an advantage of excellent controlled placement of GP.  Injected thermoplasticized GP obturation technique is another popular technique for canal obturation introduced by Yee et al. in 1977 which can replicate the intricacies of the root canal system as well as improve the homogeneity and surface adaptation of GP.  With the introduction of Ni-Ti rotary instruments for canal preparation, a simple and time efficient obturation technique i.e. matched tapered single-cone obturation has become popular which closely matches the geometry of rotary instrumentation systems. 
The quality of root fillings has been assessed through different experimental approaches such as acid dissolution of roots, electrochemical method, fluid filtration, dye penetration, radiographs, sections of the sample and SEM analysis of interface between the filling material and the canal wall. They provide semi-quantitative results showing a high level of variation.  Hence, the rationale of this study was to check the 3D obturation of the root canal using spiral computed tomography (SCT) without sectioning the specimens and loss of material. It is a non-invasive technique and the specimens can be used for further research. It is possible to reconstruct overlapping structures at arbitrary intervals and thus the ability to resolve small objects.  Among the previous studies which have compared the POV of various obturating techniques using different methods, very limited studies involve the single-cone technique which is the most common method of obturation in recent years. ,,,,
Hence, the aim of this study was to assess and compare the total volume percentage (POV) of the root canal filled with GP, as well as POV at three different levels-coronal, middle and apical third of root canals, obturated with cold lateral condensation, single-cone obturation and thermoplasticized GP techniques using SCT.
| Materials and methods|| |
Forty-five human mandibular first premolar teeth extracted for the orthodontic purpose were used for the study and ethical clearance was obtained for the same from the Institutional ethical clearance, Sri Siddhartha Dental College. The collected teeth were stored in 3% sodium hypochlorite solution for 1 week and later transferred to normal saline. Single rooted teeth with mature apices without any defects (cracks and calcifications) were selected for the study after confirmation by taking radiographs.
Preparation of specimens
Preparation of a root canal
The selected teeth were sectioned at the cemento-enamel junction (CEJ) with a diamond disc to standardize root length to 13 mm. Working length was determined by placing a 15 size K file (Mani, Tochigi, Japan) in the canal till the file tip can be seen at the apex and then retrieving 0.5 mm short of the apex. Glyde file prep (Densply Maillefer, North America) was used as a lubricant. Apical enlargement was done to size 40 and 6% taper with the crown down technique using Race files (FKG DENTAIRE, Switzerland). 1 ml of 3% Sodium hypochlorite was used as an irrigant after each instrumentation for a 1 minute period. Unolok syringe Luer lock 26 gauge (Hindustan syringes and Medical devices LTD, Faridabad, India, LOT-153021USL1) was used for irrigation passively. Finally, 1 ml of 17% EDTA was used for canal irrigation to enable the removal of the smear layer. The teeth were then randomly divided into three groups (n = 15) according to the method of canal obturation.
Scanning the specimens using SCT
The specimens were mounted on modeling wax and scanned using a Light Speed VCT scanner (GE Electricals, Milwaukee, WI, USA). They were then viewed under high resolution both in cross section and longitudinal section with a constant thickness of 0.625 mm/slice and a constant spiral or table speed of 0.5 and 140 kvp. The scanner was then transferred to Advantage windows work station (GE system, Milwaukee, WI, USA) for image analysis. Each tooth was viewed for section of 20 slices where coronal third was calculated for 6 sections, middle and apical third was calculated for 7 sections each. The inner area of each slice was measured and the volume was calculated by multiplying the area by the slice thickness (0.625 mm). Finally, the total volume of each canal was calculated by summing up. The volume was also calculated separately for apical, middle and coronal third of root canals.
Obturation of a root canal
AH plus (Densply, Germany, LOT 1106000705) was used as a root canal sealer in all the groups. All the canals were dried with paper points (Diadent group international, Korea, LOT 010512). The canals were coated with the sealer using a lentulospiral (Mani, Japan) placed in low speed hand piece. Lentulospiral was introduced into the root canal to a location 3 to 4 mm short of the working length and then slowly withdrawn from the canal, with continuous rotation.
Obturation was done as follows:
- Group 1-Cold lateral condensation: A size 40 GP (Densply Maillefer) with 2% taper was coated with the sealer and placed in the canal to the working length with tugback. Lateral condensation was achieved, with additional accessory cones which were also coated with the sealer, using a standardized finger spreader (Densply Maillefer, Switzerland, LOT 9596220) starting 1 mm short of working length. When the points prevented the spreader penetration beyond the coronal third of the canal, the canal was considered to be adequately filled and excess GP was removed at CEJ using a heated condenser. The GP at the CEJ was compacted using a cold plugger.
- Group 2-Single-cone obturation: A size 40 GP point of 6% taper (Meta Co, Korea) coated with the sealer was used as a master cone and was placed in the canal up to the working length. The excess cone was removed at CEJ using a heated condenser. The GP at the CEJ was compacted using a cold plugger.
- Group 3-Thermoplasticized gutta-percha technique: Elements obturation unit (Sybron Endo, California, USA) was used for this technique. A 40 size GP cone with 2% taper (Densply Maillefer) was coated with the sealer and placed in the canal up to the working length. A medium-sized System B insert tip which bound in the canal 3 mm short of working length was used at a temperature of 200°C and pressed against the cone so that the remaining cone in the canal was 3 mm. It was then condensed using a plugger.
- The 23-gauge cartridge's needle tip was placed next to the master point to a depth at which the tip was neither forced nor bound to the canal wall. The backfill was achieved by setting the temperature to 100°C and pressing the trigger so that the molten GP flowed in the tip was withdrawn slowly out of the canal. The GP at the CEJ was compacted using a cold plugger.
- A second SCT scan was performed to determine the POV of GP. POV in the coronal, middle and apical third was also calculated individually.
- Each tooth was viewed for a section of 20 slices for the presence of void space. In the specimens where the void space was seen, the inner area of the void was measured and multiplied by a slice thickness to get the volume of the void.
- The Volume percentage (POV) was calculated by the formula:
(a - b × 100/a)
- Where, a is volume of a root canal space; b is volume of void space.
The data was subjected to statistical analysis using SPSS version 16. The level of significance was set at a P < 0.05 and with a confidence interval level of 95%.
Inter and intra group comparisons were done with one-way ANOVA followed by a pairwise comparison with Tukey's post hoc test.
| Results|| |
All the groups showed 100% POV at the apical third.
Intergroup comparison of the mean value of POV as shown in [Table 1] showed statistically significant difference in the middle third and in total when group 1 is compared to group 2.
|Table 1: Inter group comparison of volume percentage (POV) of root canals at coronal third, middle third,|
apical third and total
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An intragroup comparison of POV at apical, middle and coronal third of the root canal as shown in [Table 2] did not show any statistically significant difference.
|Table 2: Intra group comparison of volume percentage (POV) of root canals at coronal, middle and apical third|
Click here to view
[Figure 1] and [Figure 2] show the longitudinal and cross sectional images of selected samples in SCT indicating the presence of voids in group 2 and group 3 in the middle third.
|Figure 1: Longitudinal section of SCT image of selected samples in three groups|
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|Figure 2: Cross section of SCT image of selected samples in three groups at middle third|
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| Discussion|| |
An adequately prepared and filled root canal should contribute to a high probability of success. GP popularized by Bowman in 1867 is the most widely used root canal-filling material. It has been modified over the years in various forms and techniques to accommodate the growing trends in Endodontics. Root canal sealers enhance the adaptation of the core material to root dentin and are used in conjunction with GP.
In the present study GP is used for obturation of the root canal using the lateral condensation technique (LCT), single-cone obturation and thermoplastisized GP technique with epoxy resin-based AH plus as a root canal sealer that has proved to have less shrinkage and dimensional stability.  Volume analysis of the obturated root canal is done using SCT as it gives the 3D interpretation and allows the specific location of voids accurately. , The study design is an "active arm controlled trial" which does not require a parallel placebo arm. Hence, there is no control group included in the study.
The LCT showed 100% POV in the present study unlike the observations by Anbu et al.  who felt that the spreader tracts can be devoid of sealer resulting in reduced POV. Each accessory cone was coated with the sealer in our study which may be the reason for 100% POV and indicates the possibility of more sealer in LCT as explained by Gencoglu and Garip  and SCT cannot differentiate a sealer from GP. Prashanth and Vasundhara,  Tasdemir  et al. also found significantly less POV in apical third of the root canal. This may be due to different methods used for evaluation.
The thermoplasticized GP technique and LCT showed no statistically significant difference at all the three different levels and in total in the present study which is similar to the observations by Kavitha and Anil,  Chokkalingam,  and Ansari et al. 
The voids seen with thermoplasticized GP (group 3 in Figures 1 and 2) in the present study were internal voids probably created by air entrapment during the backfill and are not in communication with the canal walls so it can be regarded as less dangerous for the endodontic prognosis because the bacteria which they might contain are imprisoned in an unfavorable environment and the adaptation of GP in the root canal is almost complete. , Overextension of GP is seen in the thermoplasticized GP technique in various studies, , therefore it was used as a backfill to obtain controlled placement in the present study.
Voids seen at the middle third of root canals in single-cone obturation (group 2 in Figures 1 and 2) can be attributed to the root canal anatomy of mandibular first premolar where the single cone has failed to fill the canal space completely. A matched taper single-cone obturation technique may be more effective in narrow round canals, as observed by Gordan et al.  and Daniele et al.  who stated that the single-point technique is simple but its application must be limited to round canals that have assumed a precise shape given by the instrumentation procedure.
There are several studies available in the literature conducted to know the sealing ability of various root canal obturation techniques by microleakage testing, with varying results and significance. ,, Only few microns space is required for observation for leakage with microleakage testing whereas in SCT, voids less than 0.625 mm cannot be detected which is a limitation.
There are no clinical studies conducted to know the efficacy of single-cone obturation technique. So, clinical studies in this regard will be helpful and also the studies evaluating the long-term performance are needed for further insight into the success of endodontic treatment with various techniques for canal obturation.
| Conclusion|| |
Within the limitations and parameters considered in the present study.
- There is 100% POV with la ateral condensation technique at all the three levels in root canal-apical, middle and coronal third
- All the techniques showed 100% POV in the apical third region
- Single-cone obturation showed the least POV in the middle third.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]