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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 2  |  Page : 101-106

Comparison of canal volume sealing capacity at different levels from the root apex using various cold and thermal obturating techniques: An in vitro study


1 Department of Conservative, Kalka Dental College, Meerut, India
2 Department of Endodontics, Institute of Dental Studies and Technology, Modinagar, Uttar Pradesh, India

Date of Web Publication6-Nov-2017

Correspondence Address:
Neha Kapoor
7, Rose Avenue, Amritsar - 143 001, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/endo.endo_27_17

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  Abstract 


Aim: The aim of this study is to compare canal volume sealing capacity at different levels from the root apex using various cold and thermal obturating techniques.
Materials and Methods: Fifty extracted human maxillary molars were collected with the mesiobuccal root curvature more than 30°. They were divided into five experimental groups (I–V) with ten teeth in each group. Biomechanical preparation was done using ProTaper rotary system. For all the groups, resin-based sealer resinoseal mixed with methylene blue dye (contrast) was used as the sealer. Groups I and II were obturated with 2% and 4% gutta-percha (GP) cones, respectively, using lateral compaction technique. Group III was obturated with 6% GP cones using single cone technique. Group IV was obturated using Thermafil system and Group V was obturated with 6% GP cones using downpack with Touch n Heat (Sybron Endo) device. All the specimens were sectioned at different levels, i.e., 3, 6, and 9 mm, from the root apex and three-dimensional apical seal was evaluated under stereomicroscope.
Results: The stereomicroscopic images showed that all obturation techniques resulted in good apical seal with comparable results. Six percent single cone obturation technique resulted in poor seal (i.e., 6 and 9 mm from the root apex). The best results were shown by Thermafil endodontic obturators at all three levels from root apex.
Conclusion: Although various obturation techniques resulted in achieving good three-dimensional obturation with satisfactory apical seal, only thermal systems were successful in achieving good seal at all the levels from the root apex.

Keywords: Apical seal, downpack technique, dye penetration, lateral compaction, thermal obturation


How to cite this article:
Bahuguna N, Kapoor N. Comparison of canal volume sealing capacity at different levels from the root apex using various cold and thermal obturating techniques: An in vitro study. Endodontology 2017;29:101-6

How to cite this URL:
Bahuguna N, Kapoor N. Comparison of canal volume sealing capacity at different levels from the root apex using various cold and thermal obturating techniques: An in vitro study. Endodontology [serial online] 2017 [cited 2018 Apr 24];29:101-6. Available from: http://www.endodontologyonweb.org/text.asp?2017/29/2/101/217710




  Introduction Top


Schilder states, “The objective of root canal procedures should be the total three-dimensional filling of the root canal and all accessory canals.” A three-dimensional well-fitted root canal prevents percolation, and microleakage of periapical exudates into the root canal space prevents reinfection.[1]

No other filling material has been as successful and widely accepted as gutta-percha (GP), probably owing to its favorable properties; however, despite these beneficial features, GP shows no adhesion to dentine, resulting in gaps between the cone and root canal walls.[2] In root canal treatment, the ideal result is to insert the largest volume of GP and minimum amount of sealer inside the root canal, enabling the sealer to penetrate the irregularities of the dentine walls and tubules.[2]

Till date, various obturation techniques (cold, thermal, single cone) have been used and assessed for obturation of root canal system. Cold lateral condensation (LC) 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.[3]

More recently, GP points of the ProTaper system were launched into the market emphasizing that they are simpler and result in faster obturation. In this system, root canals are shaped with ProTaper instruments and filled with the GP point size matching the size of the last instrument used.[4]

In 1978, Johnson introduced a technique in which alpha phase GP was placed on a metal carrier, heated, and used to obturate the root canal. This system is commercially available as Thermafil endodontic obturators (Tulsa Dental Products, Tulsa). Currently, there are three different types of Thermafil obturators available as stainless steel, titanium, and plastic carriers which are coated with alpha phase GP and become part of the final obturation.[1]

The System B obturation (Analytic Endodontics, Orange, USA) technique, developed by LS Buchanan in 1987, is regarded as a simplification of the original vertical compaction of hot GP technique of Dr. Schilder using Buchanan pluggers which are designed to fill by heating, plugging, softening, and compacting GP during continuous wave of condensation.[5] A nonstandardized (4%, 6%, or feathered tip) GP cone is carefully fitted to the canal. Using a selected plugger, a continuous wave of heat is applied to soften and downpack a cone, resulting in very well-compacted obturation of the apical portion of the canal. The remainder of the canal may be obturated by further increments or by another method.[6]

The three-dimensional obturation technique is difficult to evaluate with intraoral periapical radiographs as it gives a two-dimensional view of the obturated canals, so this study was performed by sectioning teeth at different levels from the root apex with the objective to compare canal volume sealing capacity using various cold and thermal obturating techniques.


  Materials and Methods Top


Fifty human intact molars were selected randomly with the mesiobuccal root curvature more than 30° (measured using Schneider's method for root curvature) from the Department of Oral and Maxillofacial Surgery, Institute of Dental Studies and Technologies, Modinagar.

The teeth were stored at room temperature in 3% NaOCl for dissolution of the organic debris. Ultrasonic scaling was followed and the teeth were washed with distilled water to remove any calculus or soft tissue debris. Root surfaces were verified with a magnifying eye lens for any visible cracks or fractures. The teeth were further immersed in 10% formalin solution for complete disinfection of the teeth. The teeth were divided into five experimental groups (I–V) with ten teeth in each group. Coronal access was achieved, and working length for all the teeth was determined by subtracting 1 mm from length at which file tip extruded apically. Then, biomechanical preparation was done in mesiobuccal canals of maxillary molars using ProTaper rotary files to apical size same as F1–F2, i.e., finishing ProTaper rotary files. Teeth with apical gauging F1 and F2 were selected. Seventeen percent ethylenediaminetetraacetic acid (EDTA) gel (Glyde, Dentsply Co.) was used to coat the ProTaper files while they were used. The root canals were irrigated in between each file with 3% sodium hypochlorite, followed by EDTA, and saline was used as the last irrigant to neutralize any residual chemicals.

Patency was maintained using 10 k-file. On completion of instrumentation, the canals were dried utilizing corresponding absorbent points.

Tug back for Groups I, II, III, and V was confirmed with their respective GP points and for Group IV with respective verifiers. For all the groups, resinoseal mixed with methylene blue dye (contrast) was used as the sealer.

Then, the teeth were divided into five groups with ten teeth in each group:

  • Group I - Obturated with 2% GP cones using lateral compaction technique with 2% accessory cones
  • Group II - Obturated with 4% GP cones using lateral compaction technique with 2% accessory cones
  • Group III - Obturated with 6% GP cones using single cone compaction technique
  • Group IV - Obturated using Thermafil system
  • Group V - Obturated with 6% GP cones using downpack technique with Touch n Heat device and remaining canal with increments.


Obturated teeth were stored in 100% humidity at 37°C for 24 h to allow complete setting of sealer cement. Later, using a disk at slow speed, each root was sectioned horizontally at 3, 6, and 9 mm from apex. Colored photographs of sections at each cut of 3, 6, and 9 mm were taken at a magnification of ×20 using a digital camera which was connected to stereo-operating microscope (Olympus ZX). Following which the images were scanned into a computer.


  Results Top


The samples of the study were analyzed by two independent observers, and the results were evaluated photographically [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5] by observing the dye penetration in gaps at different levels of sectioned teeth samples.
Figure 1: Thermafil obturation technique (Group IV) (a) 3 mm, (b) 6 mm, (c) 9 mm from root apex

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Figure 2: System B obturation technique (Group V) (a) 3 mm, (b) 6 mm, (c) 9 mm from root apex

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Figure 3: 4% gutta percha with lateral compaction obturation technique (Group II) (a) 3 mm, (b) 6 mm, (c) 9 mm from root apex

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Figure 4: 2% gutta percha with lateral compaction obturation technique (Group I) (a) 3 mm, (b) 6 mm, (c) 9 mm from root apex

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Figure 5: 6% single cone gutta percha obturation technique (a) 3 mm, (b) 6 mm, (c) 9 mm from root apex (Group III)

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The stereomicroscopic images of the study showed that the Thermafil obturation technique resulted in best seal at all the levels [Figure 1]a,[Figure 1]b,[Figure 1]c. All other obturation techniques resulted in good apical seal at 3 mm from apex [Figure 1]a, [Figure 2]a, [Figure 3]a, [Figure 4]a, and [Figure 5]a.

Six percent single cone obturation showed poor seal [Figure 5]b and [Figure 5]c (i.e., 6 and 9 mm from the root apex), whereas 2% GP using lateral compaction [Figure 4]b and [Figure 4]c shows dye penetration at 6 and 9 mm from the root apex, whereas 4% GP [Figure 3]b and [Figure 3]c shows good seal at 6 and 9 mm from the root apex. The downpack obturation technique with Touch n Heat showed better seal at all levels from root apex [Figure 2]a,[Figure 2]b,[Figure 2]c.


  Discussion Top


A major objective of endodontic treatment is to completely obliterate and seal the root canal system while maintaining accurate apical control of the filling material. The Washington study of endodontic success and failures suggested apical percolation of periradicular exudates into incompletely filled canals as greater cause of endodontic failures.[7]

The present study investigated the canal volume sealing capacity at different levels from the root apex using various cold and thermal obturating techniques.

Stereomicroscopic examination was chosen for this study as this provides a three-dimensional view of the surface to be examined. It requires no pretreatment of the specimen as in the scanning electron microscopic examination.[8]

In this study, methylene blue dye was used as it allows easy quantitative assessment of the extent of the dye penetration and provides a color contrast to the sealer for better visualization to view leakage assessment under a microscope. The molecular size of this dye is similar to bacterial by-products such as butyric acid which have the ability to leak out of infected root canals simulating the bacterial egress into the periapical tissues.[9]

Customized GP master cones, with the same size and taper as the preparation, are fitted as the last step of the cleaning and shaping of the root canal. Only when the cone fits, the canal is thought to be ready for packing. The customization of the master GP cone is considered to be the only factor affecting the prevalence of voids in the apical third of the root canal.[10]

Wu et al.[12] (2001) reported that there was no statistically significant difference between LC and warm vertical compaction; however, the percentage of GP (PGP)-filled canal area was greater using the warm GP technique than that of the cold GP technique in oval canals.[12]

The literature shows wide diversification with respect to the apical infiltration caused by the LC technique. LC produces a less homogeneous obturation with poorer adaptation to the canal walls as compared the techniques that use thermoplasticized GP. This may possibly explain the fact that the root canals obturated with this technique numerically presented the highest mean apical infiltration.[13]

In conclusion to the results of our study, Mittal et al. conducted a clinical study to evaluate the obturation of root canal using various obturation techniques, namely, cold lateral, warm lateral, warm vertical, and mixed (warm lateral in middle and apical 1/3rd and warm vertical in coronal 1/3rd). Cold lateral obturation technique resulted in definite voids and gaps between GP and canal interface at all levels of root canal as GP cones are merely laminated together whereas warm obturation techniques resulted good apical seal at all the levels.[11]

In support of results of our study, Hale et al. carried out a retrospective clinical outcome stating that apical voids in the LC group are hypothesized to be due to a lack of deep spreader penetration after master cone placement, thus prohibiting accessory cones from reaching the apical 1–3 mm. Allison et al. demonstrated thatin vitro apical dye leakage correlated to the apical extent of the spreader penetration when obturating with LC. Several factors seem to affect spreader penetration. Nickel-titanium (NiTi) spreaders are more effective than stainless steel spreaders, and the use of 0.02 taper GP cones is more effective than greater taper cones. When voids were present in the carrier-based obturation group, they were almost always related to a gap between a post and obturation material. This is likely due to improper postfitting and cementation techniques. The combination of thermoplasticized GP and a plastic carrier acting as a compactor inserted close to working length seems to minimize the presence of voids when compared to lateral compaction.[14]

Souza et al. conducted a study to determine the influence of filling technique and root canal area on the PGP in laterally compacted root fillings. According to the findings of this study, canal anatomy potentially interferes with the PGP of LC fillings. Variations in canal anatomy in extracted teeth (not present in simulated canals) might be the reason for such a variation in the PGP of root fillings (Gordon et al. 2005).[15]

However, single cone technique has advantage of being fastest endodontic treatment obturation. The single-cone technique comprises the use of a single GP point at environment temperature, with a variable cement thickness depending on the adaptation of the point to the root canal walls. This technique has been considered less effective in sealing root canal because of the greater volume of cement that can be expected in the absence of condensation and of the possible anatomic variations of the root canal, which cannot always be filled with larger master cones corresponding to the geometry of the NiTi rotary instruments. Porosities in large volumes, contraction, cement dissolution, and a lower adaptation of the single cone in the middle and coronal thirds of the canal with irregular shape are the main disadvantages of this technique.[4]

According to the results of our study, Pommel and Camps compared the single-cone, LC, Thermafil, and System B techniques and reported that the single-cone technique showed the highest infiltration, similarly to the results found by Yücel and Çiftçi.[16]

On the other hand, the results of the study of Holland et al. showed that the single cone technique exhibited a better sealing than the LC technique; however, the teeth exhibited straight and relatively large root canals. In cases of curved canals, the single-cone technique would probably exhibit the greatest deficiencies compared with the LC.[4]

Rodrigues et al. conducted a study to compare the PGP in mesial root canals of mandibular molars obturated with lateral compaction or single cone using ProTaper Universal System techniques at different levels of the root (3, 5, and 7 mm from the root apex). It was concluded that single technique provided greater PGP-filled area (PGFA) than the LC technique in the apical third of mesial root canals of mandibular molars. There was no difference between the two techniques regarding the PGP in the cervical and middle thirds.[17]

In accordance with results of our study, Crasta et al. conducted a study 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 LC, single cone obturation, and thermoplasticized GP techniques using Spiral computed tomography. It was concluded that voids seen with thermoplasticized GP 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, whereas voids seen at the middle third of root canals in single cone obturation 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.[3]

Hegde et al. measured and compared the apical sealing ability of laterally compacted GP using 2% GP with 2% accessory cones, 6% GP with 2% accessory cones with single cone compacted ProTaper GP point corresponding to ProTaper preparation, using fluorescent dye penetration technique. In this study, single cone compaction of ProTaper GP points corresponding to its respective preparation showed better apical sealing ability because teeth used in this study were straight with single canals that could be prepared in a standardized manner with rotary instruments.[18]

According to results of our study, Farea et al. conducted a study to determine the PGFA in the apical third of root canals after filling with either System B or cold LC techniques at different levels 1, 2, 3, 4 mm from the working length. System B resulted into better and homogenous obturation of the root canal with a minimal amount of sealer.[19]

In conclusion with the results of our study, Ozawa et al. compared obturation techniques (single cone, LC, and Thermafil) in irregular oval canals. The roots were assessed in thirds of the length, which revealed that in the middle and coronal third, Thermafil had the lowest percentage of sealer and the highest volume of filling material, whereas in the apical third, the filling material was generally well adapted to the canal wall for all techniques.[2]

In corroboration with the results of our study, Rajeswari et al. conducted a study to evaluate the apical microleakage of Thermafil and Obtura II in comparison with cold LC using fluid filtration system. Thermafil obturators proved a better seal than LC this because the plastic carrier in might act as plunger, which effectively forces the thermoplasticized GP into the lateral walls of the canal. Thermafil obturators are flexible plastic carriers coated with alpha-phase GP that has low melting temperature and good adhesiveness.[1]

However, none of the obturation techniques resulted in gaps free obturation.


  Conclusion Top


Within the limitations of this study, it can be concluded that none of the obturation technique is able to seal root canal completely. Hence, all the obturation techniques (cold and thermal) resulted in comparable apical seal whereas single cone obturation results into poor seal at 6 and 9 mm from apex of the root. However, furtherin vivo studies have to be carried out to make a direct correlation between these results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Rajeswari P, Gopikrishna V, Parameswaran A, Gupta T, Kandaswamy D. In-vitro evaluation of apical micro leakage of thermafil and obtura II heated gutta percha in comparison with cold lateral condensation using fluid filtration system. Endodontology 2005;17:24-31.  Back to cited text no. 1
    
2.
Araújo VL, Souza-Gabriel AE, Cruz Filho AM, Pécora JD, Silva RG. Volume of sealer in the apical region of teeth filled by different techniques: A micro-CT analysis. Braz Oral Res 2016;30. pii: S1806-83242016000100234.  Back to cited text no. 2
    
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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: Anin vitro study. Saudi Endod J 2014;4:64-9.  Back to cited text no. 3
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Aarvendh Kumar PR, Kumar DP, Kaipa BK, Bachu N. Evaluation and comparison of apical sealing ability of three different obturation methods - warm lateral condensation, warm vertical condensation, cold lateral condensation-anin vitro study. Int J Prev Clin Dent Res 2014;1:20-3.  Back to cited text no. 7
    
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Kumar NS, Prabu PS, Prabu N, Rathinasamy S. Sealing ability of lateral condensation, thermoplasticized gutta-percha and flowable gutta-percha obturation techniques: A comparativein vitro study. J Pharm Bioallied Sci 2012;4 Suppl 2:S131-5.  Back to cited text no. 8
    
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De Deus G, Murad CF, Reis CM, Gurgel-Filho E, Coutinho Filho T. Analysis of the sealing ability of different obturation techniques in ovalshaped canals: A study using a bacterial leakage model. Braz Oral Res 2006;20:64-9.  Back to cited text no. 11
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Mittal N, Dewan N, Gupta P, Sharma GM. In-vivo radiographic evaluation of sealing ability of root canals with various obturation techniques. Endodontology 2002;14:46-51.  Back to cited text no. 13
    
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Hegde MN, Arvind MS, Naik S, Hegde ND. Comparison of apical sealing ability of laterally compacted gutta-percha versus single cone compaction technique using nickel titanium rotary system - Anin vitro study. Endodontology 2011;23:49-56.  Back to cited text no. 18
    
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