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Table of Contents   
ORIGINAL ARTICLE  
Year : 2011  |  Volume : 14  |  Issue : 3  |  Page : 273-276
Three-dimensional helical computed tomographic evaluation of three obturation techniques: In vitro study


1 Department of Conservative Dentistry and Endodontics, VMS Dental College, Salem, India
2 Department of Conservative Dentistry and Endodontics, TN Government Dental College, Porur, Chennai, India
3 Department of Conservative Dentistry and Endodontics, Sri Ramachandra Dental College, Porur, Chennai, India

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Date of Submission08-Oct-2010
Date of Decision02-Dec-2010
Date of Acceptance29-Jan-2011
Date of Web Publication10-Oct-2011
 

   Abstract 

Aim: The purpose of this study was to evaluate the adequacy of three obturation techniques namely lateral condensation, EQ Fil (backfill obturation) and thermafil (core carrier obturation) techniques using three-dimensional (3D) helical computed tomography (CT) by volume rendering method.
Materials and Methods: Thirty freshly extracted teeth were randomly divided into three groups of 10 teeth each. Biomechanical preparation was done in all the teeth using rotary instruments. All three sets of teeth were placed in helical CT slice scanner and were imaged before obturation. The three sets were then obturated by following methods: Group I: lateral condensation, Group II: EQ Fil (backfill) and Group III: thermafil (core carrier obturation).Volume of the pulp chamber and gutta-percha after obturation were calculated using volume rendering technique and adequacy of the obturation techniques were calculated.
Statistical Analysis Used: One-way ANOVA and Multiple-Range Tukey Test by Tukey-HSD procedure
Results: Mean change in lateral condensation (0.005±0.002) was significantly higher than that of thermafil obturation (0.002±0.001) [P<0.05].
Conclusions: Conventional lateral condensation technique showed maximal inadequacy of obturation and thermafil obturation technique showed the least inadequacy of obturation when the volume of the specimens were calculated and reconstructed

Keywords: 3D multislice helical CT scan, lateral condensation, thermoplasticized gutta-percha, volume rendering

How to cite this article:
Chokkalingam M, Ramaprabha, Kandaswamy D. Three-dimensional helical computed tomographic evaluation of three obturation techniques: In vitro study. J Conserv Dent 2011;14:273-6

How to cite this URL:
Chokkalingam M, Ramaprabha, Kandaswamy D. Three-dimensional helical computed tomographic evaluation of three obturation techniques: In vitro study. J Conserv Dent [serial online] 2011 [cited 2019 Jun 24];14:273-6. Available from: http://www.jcd.org.in/text.asp?2011/14/3/273/85815

   Introduction Top


Complete obturation of root canal system to the cementodentinal junction is an important goal in endodontic treatment. To achieve this, it is believed that root canal fillings must seal the pulp space both apically and laterally to prevent further apical irritation from incomplete elimination of bacterial products or continuous communication between apical tissues and oral cavity.

Many techniques and materials have been used to obturate anatomically complicated root canal spaces. Gutta-percha, popularized by Bowman in 1867 is the most widely used and accepted root canal-filling material. It seems to be the least toxic, least tissue-irritating, and least allergenic root canal-filling material available. [1] A variety of thermoplasticized gutta-percha techniques have been introduced recently and a number of investigations have evaluated the apical seal obtained by these techniques. Although, there are numerous studies evaluating the sealing ability and wall adaptation of thermoplasticized gutta-percha, there are only a few regarding the volume occupied by gutta-percha and the 3D adequacy of these techniques.

The present study evaluates three different obturation techniques, lateral condensation, EQ Fil obturation and thermafil obturation using volume rendering option of three dimensional (3D) helical computed tomogram by separating the intracanal filling from the lumen and by measuring the radiolucent space and radiopaque filling to evaluate the inadequacy of obturation


   Materials and Methods Top


Thirty freshly extracted non-carious human mandibular premolars with single straight canal were used for the study. Teeth with incompletely formed apices, calcified canals, fractures and resorption were discarded. After extraction, all teeth were stored in 10% formalin. After clearing the organic debris the teeth were subsequently stored in saline until use.

Glass plates of dimension 9x 10 cm were selected. It was divided into three equal parts of dimension 3 cm in height and 10 cm in width. Graph sheets of same measurement were made and attached to the base of each glass plate. The graph sheets were used to guide proper placement of teeth over the glass plates. Teeth were then randomly divided into groups of 10 teeth each. A set of 10 teeth were placed on to the glass plate with central vertical axis in correspondence with 0.5 cm base of each 1 m division. Care has been taken to arrange all the apices of teeth to correspond to 0.8 cm from the horizontal base line of the glass plate.

Access opening and canal preparation

Access cavity preparation was done in all teeth using No.4 round bur through the occlusal surface. Gates Glidden drills were used to enlarge the coronal preparation to facilitate further instrumentation. Canal preparation was done in all the teeth using Protaper (A) 4049, 21 mm, (Dentsply, Mailleffer) rotary instruments (SX, F1, F2 series). Calcific obstructions if any were negotiated with EDTA preparations (RC Help-Prime dental products, Mumbai, India). Copious irrigation was done with 5% sodium hypochlorite and normal saline. All the canals are dried with sterile paper points.

Obturation

Zinc oxide Eugenol (DPI, Mumbai) was selected as sealant for all the groups [Table 1].
Table 1: Different groups of obturation

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3D Helical Scanning (Before and after Obturation):

The combination of helical CT and 3D reconstruction with volume rendering allow rapid and detailed examination of the system to be examined. It is a rapid, non-invasive tool that supports effective differential diagnosis of hard and soft tissue structures. It shows flexible 3D simulation that offers less time consuming module for the dentist. It offers increased patient comfort and convenience; it allows real time reformation, sagittal, coronal and oblique views. [2] All three sets of teeth were placed in GE Multislice Helical slice scanner (Light Speed, GE, USA) separately and aligned such that axis of roots are perpendicular to the beam. The teeth were imaged before and after obturation using 2.5 mm slice thickness. It was subsequently, reconstructed to 1.25-mm thickness with 1-mm spacing. Volumetric analysis was done by capturing lumen with paintbrush tool in the Dicom software utilized in the 3D helical CT for each slice from 7 th slice to 20 th slice. Thus, the volume of each slice is calculated and manipulated by the computer which give the final volume of given prepared canal from which 3D reconstruction done. Raw data were reconstructed using bone algorithm. The slice data from scan was stored in computer magnetic tape. [Figure 1]
Figure 1: Before and after obturation- Backfill technique

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   Results Top


The mean and standard deviation of different obturation techniques were calculated before and after the completion of obturation and their volume inadequacy determined [Table 2]. One way ANOVA was used to calculate the P value. Multiple-Range Tukey Test by Tukey-HSD procedure was employed to identify the significant groups at 5% level [Table 3].
Table 2: Volume of the root canals and their inadequacy in different obturation techniques (Cubic centimetres)

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Table 3: Test of significance between different obturation techniques

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   Discussion Top


Gutta-percha is by far the most universally used solid core root canal filling materials and may be classified as plastic. When heated to temperature range of 4249°C, gutta-percha undergoes a phase change to the aphase. In this phase it is runny, tacky, sticky and non-compactable. When cooled down to the beta phase, shrinkage occurs of similar percentiles, but the degree of shrinkage almost always is greater than degree of expansion and may differ by as much as 2%. [3]

The purpose of obturating the prepared root canal space are (1) to eliminate all avenues of leakage from the oral cavity or the periradicular tissues into the root canal system (2) to seal within the system any irritants that cannot be fully removed during canal cleaning and shaping procedures.

Contemporary perspectives on the assessment of quality of root canal obturation have placed an undue reliance on apical leakage studies in addition to two-dimensional radiographical evaluations and there is a poor correlation between the quality of the root canal obturation (especially an impervious seal) and what is viewed on a buccal radiograph. Likewise, when the radiographical appearance of the root canal filling is unacceptable, the likelihood of leakage is high. The importance of 3D obturation of the root canal system is important at this stage. Vannier et al demonstrated the feasibility of spiral volumetric CT for quantitative study of oral hard tissues in the presence of metal restorations. [4] Blake Nielson R et al evaluated the value of microcomputed tomography in morphological relationships in endodontic research. [5] Kleoniki Lyroundi et al studied the application of both digital 3D image processing and virtual reality techniques in endodontics. [6] The volume-rendering technique used with the help of 3D helical CT is the most accurate mode of depiction of 3D volume of the obturated canals. It allows the clinician to visualize the filling from all angles unlike radiographs which give two-dimensional reproductions. The voids at various axial levels can be calculated. Venkateshbabu et al evaluated the pulp chamber of maxillary first premolars and its relationship with cementoenamel junction. [7] Joseph Reuben et al evaluated the root canal morphology of mandibular first molar in Indian population. [8]

Spiral CT have been documented as an aid in successfully treating teeth with complicated anatomy like maxillary first molar with a single root and a single canal [9] , maxillary molar with two palatal roots [10] ,fused mandibular second molar and paramolar. [11]

Volume of the pulp chamber is the maximum amount of space which gutta-percha has to accommodate for hermetic seal of the canal. The total volume of all permanent pulp organs is 0.38 cc and means volume of a single adult human pulp is 0.02 as put forth by Fanibunda KB. [12]

The effect of heating on the volumetric change of gutta-percha is most important to dentistry. Although the material is thought to be compressed with force that would reduce its volume, studies have shown that it is actually compacted not compressed and increased volumetric changes are due to heating. [13] Gulabivala K et al showed thermafil sealed significantly better than lateral condensation in canals with curvatures greater than 25 degrees. [14] Gencoglu N et al compared six different gutta-percha obturation techniques and concluded that core techniques (Thermafil, JS Quick-Fill and soft core) produced higher gutta-percha content than the Microseal, System B and lateral condensation techniques. [15] Gencoglu N and Garip Y in 2002 calculated the core (gutta-percha and carrier)/sealer ratio and the sealing ability of four different gutta-percha techniques and they concluded thatthermafil and JS quick-fill with carrier and System B were found to be superior to the lateral condensation technique in terms of core/sealer ratio. [16] Weller et al compared the ability of Thermafil, Obtura II and the lateral condensation techniques and showed Obtura II demonstrated the best adaptation to the prepared canal walls. [17] Clinton K Van Himal T et al compared warm gutta-percha obturation with thermafil plus and lateral condensation and concluded thermafil was better able to flow into lateral spaces but found to extrude out of the apical foramen more than in lateral condensation. [18]

In this study, lateral condensation showed the high deviation from root canal volume of prepared canal without obturation, followed by EQ Fil. Lowest inadequacy was shown by thermafil core carrier obturation. This can be explained by the fact that lateral condensation contained more voids and the inability to adapt to the walls as explained by Schilder. The inability to adapt to the walls of root canal and the isolated concave areas in the canal creates a less dense mass which gives difference in the measured volume calculation before and after obturation. On the other hand, thermoplasticized gutta-percha techniques on application of heat, flows and adapt well onto the walls of the root canal. Application of heat by plugging further compensates for any voids within the mass and results in a whole compact mass with good marginal adaptation to the canal walls. Moreover thermafil carries warm gutta-percha up to the apical third which ensures hermetic seal rather than EQ Fil system which utilizes regular mode of vertical condensation for the apical third. This is effectively depicted in the difference in the mean value of inadequacy obtained between the EQ Fil and thermafil technique.

From the study, it is evident that there is no significant difference in mean values between different study groups before obturation (P=0.45). Similarly, there is no significant difference in mean values between different study groups after obturation. Mean change in lateral condensation (0.005±0.002) is significantly higher than the mean change in thermafil obturation (0.002±0.001) [P<0.05]. This shows that the thermafil obturation technique shows more accuracy in reaching the maximum level of root canal volume possible when compared to the lateral condensation.

Lateral condensation of gutta-percha has remained the most widely used method of obturating canals. The advantages of this technique include its predictability, relative ease of use, conservative preparation and controlled placement of materials. Disadvantages include a lack of homogeneity of gutta-percha mass, an increased number of voids and sealer pools and less adaptation to canal walls and irregularities. Gutmann et al evaluated thermafil versus vertical condensation in a series of studies and reported that thermafil resulted in more dense and well-adapted root canal fillings throughout the entire root canal system than lateral condensation with standard gutta-percha. Both fillings demonstrated accepted root canal fillings in the apical on third of the canal. [19] Walcott and coworkers found that the movement of thermafil gutta-percha and sealer into the lateral canals was comparable to lateral condensation; however, thermafil was most effective in the main canal. [20]


   Conclusion Top


  • Conventional lateral condensation technique showed the maximal inadequacy of obturation when the volume of the specimens were calculated and reconstructed.
  • Thermafil obturation showed the least inadequacy of obturation when the volume of the specimens were calculated and reconstructed.
  • There is no statistical significance between the lateral condensation with EQ Fil and EQ Fil with thermafil with regards to the adequacy of obturation.
  • There is statistical significant difference between the lateral condensation and thermafil obturation technique with regards to the adequacy of obturation.


 
   References Top

1.Stephen Cohen, Richard Burns. Pathways of Pulp. 6 th ed. United States: Mosby Publications; 2000. p. 225.  Back to cited text no. 1
    
2.Pretorius ES, Fishman EK. Volume-rendered Three-Dimensional Spiral CT: Musculoskeletal applications, presented as scientific exhibit, Chicago,RSNA Scientific Assembly,1997.  Back to cited text no. 2
    
3.Franklin Weine. Endodontic therapy. 5 th ed. United States: Mosby Publications; 2000. p. 429.  Back to cited text no. 3
    
4.Vannier MW, Hildebolt CF, Conover G, Knapp RH, Yokoyama-Crothers N, Wang G. Three-dimensional dental imaging by spiral CT, A Progress report. Oral surg Oral Med oral Pathol oral Radiol Endod 1997;84:561-70.  Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Nielson B, Abdalmajeid MA Peters D, Carnes DI, Lancester J. Microcomputed Tomography: Advanced system for detailed Endodontic Research. J Endod 1995;21:561-8.  Back to cited text no. 5
    
6.Lyroudia K, Mikrogeorgis G, Bakaloudi P, Kechagias E, Nikolaidis N, Pitas I. Virtual endodontics: three-dimensional tooth volume representations and their pulp cavity access. J Endod 2002;28:599-602.  Back to cited text no. 6
[PUBMED]  [FULLTEXT]  
7.Venkateshbabu N, Velmurugan N, Roy A, Kandaswamy D. Evaluation of the pulp chamber morphological measurements in maxillary first premolar in Indian population - an in-vitro study. J Conserv Dent 2007;10:119-21.  Back to cited text no. 7
  Medknow Journal  
8.Reuben J, Velmurugan N, Kandasamy D. The Evaluation of Root Canal Morphology of the Mandibular First Molar in an Indian Population Using Spiral Computed Tomography Scan: An In Vitro Study. J Endod 2008;34:2125.  Back to cited text no. 8
    
9.Gopikrishna V, Bhargavi N, Kandasamy D. Endodontic management of single root and single canal diagnosed with the aid of spiral CT: A case report. J Endod 2006;32:68791.  Back to cited text no. 9
    
10.Agarwal V, Singla M, Logani A, Shah N. Endodontic management of maxillary first molar with two palatal canals with the aid of spiral computed tomography: A case report. J Endod 2009:35:1379.  Back to cited text no. 10
    
11.Ballal S, Sachdeva GS, Kandasamy D. Endodontic management of fused mandibular second molar and paramolar with the aid of spiral computed tomography: A case report. J Endod 2007;33:1247-51.  Back to cited text no. 11
    
12.Bhaskar SN. Orban's Oral Histology and Embryology. 10 th ed United States: CBS Publications; 1990. p. 136.  Back to cited text no. 12
    
13.Ingle J, Bakland LK. Endodontics, 5 th ed. BC Decker, editor. United States: Harcourt Publications; 2002. p. 576.  Back to cited text no. 13
    
14.Gulabivala K, Holt R, Long B. An in vitro comparison of thermoplasticized gutta-percha obturation techniques with cold lateral condensation. Endod Dent Traumtol 1998;14:262-9.  Back to cited text no. 14
    
15.Gencoglu N, Garip Y, Bas M, Samani S. Comparison of different gutta-percha filling techniques; Thermafil, Quick-Fill, Soft Core, Microseal, System B and the lateral condensation. Oral Surg Oral Med Oral Path Oral Radio Endod 2003;96:91-5.  Back to cited text no. 15
    
16.Gencoglu N, Garip Y, Bas M, Samani S. Comparison of different gutta-percha filling techniques; Thermafil, Quick-Fill, System B and the lateral condensation. Oral Surg Oral Med Oral Path Oral Radio Endod 2002;93:333-6.  Back to cited text no. 16
    
17.Weller RN, Kimbrough WF, Anderson RW. A comparison of thermoplastic obturation techniques; Adaptation to the canal walls. J Endod 1997;23:703-6.  Back to cited text no. 17
[PUBMED]  [FULLTEXT]  
18.Clinton K, Van Himel T. Comparison of a warm gutta-percha obturation technique and lateral condensation. J Endod 200127:692-5.  Back to cited text no. 18
    
19.Gutmann JL, Saunders WP, Saunders EM, Nguyen L. An assessment of the plastic Thermafil obturation technique. Part 2. Material adaptation and sealability. Int Endod J 1993;26:179-83.  Back to cited text no. 19
    
20.Wolcott J, Himel VT, Powell W, Penney J. Effect of two obturation techniques on the filling of lateral canals and the main canal. J Endod 1997;23:632-5.  Back to cited text no. 20
[PUBMED]  [FULLTEXT]  

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Correspondence Address:
M Chokkalingam
3B-1, Angammal Colony, Salem-636009, Tamilnadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-0707.85815

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