Journal of Conservative Dentistry
Home About us Editorial Board Instructions Submission Subscribe Advertise Contact e-Alerts Login 
Users Online: 28
Print this page  Email this page Bookmark this page Small font sizeDefault font sizeIncrease font size
 


 
Table of Contents   
ORIGINAL ARTICLE  
Year : 2012  |  Volume : 15  |  Issue : 2  |  Page : 141-145
Dissolving efficacy of different organic solvents on gutta-percha and resilon root canal obturating materials at different immersion time intervals


1 Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital Srinagar, Kashmir, India
2 Department of Periodontics and Oral Implantology, Government Dental College and Hospital Srinagar, Kashmir, India

Click here for correspondence address and email

Date of Submission07-Aug-2011
Date of Decision14-Dec-2011
Date of Acceptance18-Jan-2012
Date of Web Publication2-Apr-2012
 

   Abstract 

Background Aim: The purpose of this study was to compare and evaluate the dissolving capability of various endodontic solvents used during endodontic retreatment on resilon and gutta-percha at different immersion time intervals.
Materials and Methods: 160 ISO no. 40 cones (0.06 taper), 80 each of resilon and gutta-percha were taken as samples for the study. Both resilon and gutta-percha were divided into eight experimental groups of 20 cones (four groups each of resilon and gutta-percha) for immersion in xylene, tetrachloroethylene, refined orange oil and distilled water. Each group was further divided into two equal subgroups (n=10) for 2- and 5-minute immersion time intervals at room temperature to investigate the potential of these solvents for clinical use in dissolving resilon and gutta-percha. Each sample was weighed initially before immersing in the solvent on a digital analytical scale. Distilled water served as a control. Samples were removed from the respective solvents after the specified immersion period and washed in 100 ml of distilled water and allowed to dry for 24 h at 37°C in a humidifier. The samples were then again weighed after immersion in the specific solvent on a digital analytical scale. The extent of gutta-percha or resilon removed from the specimen was calculated from the difference between the original weight of gutta-percha or resilon sample and its final weight. Means and standard deviations of percentage loss of weight were calculated at each time interval for each group of specimens. The values were compared by statistical parametric tests using SPSS 16.0 Software. The data was subjected to paired 't ' test, independent 't' test, one-way ANOVA test and multiple comparisons with Scheffe's test.
Results: There was no significance in the amount of gutta-percha dissolved at 2- and 5-minute immersion time intervals in all groups (P>0.05) except the tetrachloroethylene group (P=0.00). There was a very high significance in the amount of resilon dissolved at 2- and 5-minute immersion time intervals in all groups (P=0.00) except the xylene and distilled water (Control) groups (P>0.05).
Conclusion: The results showed that xylene, refined orange oil and tetrachloroethylene can be used for softening gutta-percha/resilon during retreatment with various techniques- xylene being the best solvent both for gutta-percha and resilon.

Keywords: Endodontic retreatment; gutta-percha; resilon; solvents

How to cite this article:
Mushtaq M, Farooq R, Ibrahim M, Khan FY. Dissolving efficacy of different organic solvents on gutta-percha and resilon root canal obturating materials at different immersion time intervals. J Conserv Dent 2012;15:141-5

How to cite this URL:
Mushtaq M, Farooq R, Ibrahim M, Khan FY. Dissolving efficacy of different organic solvents on gutta-percha and resilon root canal obturating materials at different immersion time intervals. J Conserv Dent [serial online] 2012 [cited 2014 Nov 24];15:141-5. Available from: http://www.jcd.org.in/text.asp?2012/15/2/141/94584

   Introduction Top


Non surgical endodontic retreatment is an attempt to re-establish healthy periapical tissues after inefficient treatment or reinfection of an obturated root canal system because of coronal or apical leakage. It requires regaining access to the entire root canal system through removal of the defective root canal filling, further cleaning and shaping if required and reobturation. [1] Success rate of endodontically treated teeth ranges from 86 to 95% [2] and retreatment should be done for failure of root canal treated teeth. For over 100 years, gutta-percha has been the most commonly used material to obturate the root canal system. One of the disadvantages of gutta-percha as an obturating material is the lack of an effective seal. [3] However, when the coronal restoration is defective or absent, contamination with saliva may cause root canal sealer dissolution, thus providing a space for bacterial penetration that may contribute to the failure of the treatment. [4]

Resilon is a thermoplastic synthetic polymer based root canal filling material containing bioactive glass and radiopaque fillers. [5] The manufacturer claims that its handling characteristics are similar to gutta-percha. The significant improvement of resilon when compared to gutta-percha is claimed to be its bonding to the dentin walls when used in conjunction with its sealer, and forms a "monoblock" within the canal. [6] Preliminary studies have shown that resilon has less microleakage when compared to gutta-percha. [5],[7],[8],[9] Because of its acclaimed superior characteristics, resilon is emerging as a promising alternative to gutta-percha. The number of teeth obturated with resilon is expected to rise significantly in the near future. Although the long-term success rate of this new system is unknown, a number of reasons will necessitate retreatment of resilon-filled teeth. A recent study demonstrated the susceptibility of biodegradation of resilon by "bacterial/salivary enzymes. [10] In such cases nonsurgical endodontic retreatment would be indicated to clean and shape the previously root treated tooth.

Gutta-percha is the most popular core material used for obturation. [11] Removal of gutta-percha can be done with several techniques. These include rotary files, ultrasonic instruments, and hand files in combination with heat or chemicals. [12] Solvents have been used in the past to soften and dissolve gutta-percha. [13] However, all solvents are known to be toxic to the periapical tissues and should be used with caution. [13] In clinical practice, refined orange oil, tetrachloroethylene and xylene are used for softening the gutta-percha during nonsurgical endodontic retreatment. There are no studies using above solvents to remove synthetic polymer based root canal filling material.

Hence the purpose of this study was to compare and evaluate the dissolving capability of various endodontic solvents such as xylene, tetrachloroethylene and refined orange oil on resilon and gutta-percha at different immersion time intervals.


   Materials and Methods Top


160 ISO no. 40 cones (0.06 taper), 80 each of resilon (SybronEndo, USA) and gutta-percha (SureEndo, Korea) were taken as samples for the study. Both resilon and gutta-percha were divided into eight experimental groups of 20 cones (four groups each of resilon and gutta-percha) for immersion in xylene (Fischer Scientific, Mumbai, India), tetrachloroethylene (Ammdent, India), refined orange oil (Nipponshika, Yakuhin Co. Ltd, Shimonoseki, Japan) and distilled water (Milli-Q water system, Millipore Corporation, Bedford, MA, USA). Each group was further divided into two equal subgroups (n=10) for 2- and 5-minute immersion time intervals at room temperature to investigate the potential of these solvents for clinical use in dissolving resilon and gutta-percha. Each sample was weighed initially before immersing in the solvent on a digital analytical scale (Shimadzu Electronic Weighing Machine, Japan, Model: AEL-200). Distilled water served as a control.

The samples of solvents were prepared by taking 5 ml of each solvent in a glass vial. Immediately after the gutta-percha/resilon cone was immersed in the solvent, timing was started with a stop watch and the lid of the screw top bottle was replaced. If the gutta-percha/resilon sample stuck to the glass vial during testing, it was dislodged with vibrations on vortex shaker to prevent clumping of partially dissolved gutta-percha/resilon, respectively. Samples were removed from the glass vial after the specified immersion period and washed in 100 ml of distilled water and allowed to dry for 24 h at 37°C in a humidifier. The samples were then again weighed after immersion in the specific solvent on a digital analytical scale (Shimadzu Electronic Weighing Machine, Japan, Model: AEL-200).

The extent of gutta-percha or resilon removed from the specimen was calculated from the difference between the original weight of gutta-percha or resilon and its final weight using the following equation:

Where:

M2 =post-immersion weight.

M1 =pre-immersion weight.

Means and standard deviations of percentage loss of weight were calculated at each time interval for each group of specimens. The values were compared by statistical parametric tests using SPSS 16.0 Software. The data was subjected to paired 't' test, independent 't' test, one-way ANOVA test and multiple comparisons with Scheffe's test.


   Results Top


The weight loss of gutta-percha in different solvents as a function of time [Figure 1]a showed that there was no significance in the amount of material dissolved at 2- and 5-minute immersion time intervals in all groups (P>0.05) except the tetrachloroethylene group (P=0.00).
Figure 1a: Weight loss of gutta-percha in different solvents as a function of time
Figure 1b: Weight loss of resilon in different solvents as a function of time


Click here to view


The weight loss of resilon in different solvents as a function of time [Figure 1]b showed that there was a very high significance in the amount of material dissolved at 2- and 5-minute immersion time intervals in all groups (P=0.00) except the xylene and distilled water (Control) groups (P>0.05).

Comparison of solubility- effect of different solvents on gutta-percha and resilon at 2-minute immersion time interval [Figure 2]a showed that there was a very highly significant difference in the amount of gutta-percha and resilon dissolved in all the solvents (P=0.00) except the distilled water (Control) groups (P>0.05). Xylene exhibited the best dissolving capacity both for gutta-percha and resilon followed by refined orange oil and the least dissolving capacity was seen with tetrachloroethylene as is evident from the graph. All the solvents tested displayed a better dissolving capacity in dissolving gutta-percha as compared to resilon (P=0.00).
Figure 2a: Comparison of solubility effect of different solvents on gutta-percha and resilon at 2-minute immersion time interval
Figure 2b: Comparison of solubility effect of different solvents on gutta-percha and resilon at 5-minute immersion time interval


Click here to view


Comparison of solubility- effect of different solvents on gutta-percha and resilon at 5-minute immersion time interval [Figure 2]b showed that there was a very highly significant difference in the amount of gutta-percha and resilon dissolved in all the solvents (P=0.00) except the distilled water (Control) groups (P>0.05). For gutta-percha, xylene exhibited the best dissolving capacity followed by refined orange oil and the least dissolving capacity was seen with tetrachloroethylene as is evident from the graph. For resilon, the test solvents displayed no significant difference in dissolving resilon. Xylene displayed a better dissolving capacity in dissolving gutta-percha as compared to resilon (P=0.00). Refined orange oil and tetrachloroethylene did not show a statistically significant difference in dissolving gutta-percha as compared to resilon (P>0.05).


   Discussion Top


The basic aim of nonsurgical endodontic retreatment is to re-establish healthy periapical tissues after inefficient treatment or reinfection of an obturated root canal system because of coronal or apical leakage. The procedure involves regaining access to the entire root canal system through removal of the original root canal filling, further cleaning and reobturation. [1] Removing as much sealer and filling material as possible from inadequately prepared and filled root canal is critical to uncover remnants of necrotic tissue or bacteria that may be responsible for periapical inflammation or failure. [14]

Removal of gutta-percha can be done with several techniques. Removal of coronal portion of the gutta-percha can be achieved with heat carriers such as Touch N. Heat or System B. Gates-Glidden burs also are quite effective in the removal of the coronal portion of the filling material. [15] Recent studies have demonstrated the successful use of Nickel Titanium rotary files as well. [15] Solvents have been used in the past to soften and dissolve gutta-percha. Solvents available for dissolution of gutta-percha filling material are as follows; chloroform, eucalyptol oil, xylene, halothane, turpentine oil and pine needle oil. [15] When small, underprepared and curved canals need negotiation, solvents and small K-type files are best suited. The sequential technique involves refilling the created reservoir in the canal orifice with drops of solvent and picking into the dissolving gutta-percha while filing with a size 10, 15 and 20 stainless steel files. This is continued until the terminals is negotiated after which all the solvents should be discontinued. Sequentially larger K-type files are then inserted into the canal until all the gutta-percha mass is removed. In many cases combined use of different techniques may be the most efficient and time-saving method. [15]

Resilon is a recent advance in root canal filling materials and chemically it is a thermoplastic synthetic polymer based root canal filling material containing bioactive glass and radiopaque fillers. [5] The manufacturer claims that its handling characteristics are similar to gutta-percha. The significant improvement in resilon when compared to gutta-percha is claimed to be its bonding to the dentinal walls when used in conjunction with its sealer. Epiphany root canal sealer forms a monoblock with the canal. [6] Because of its acclaimed superior characteristics; resilon is emerging as a promising alternative to gutta-percha. The number of teeth obturated with resilon in expected to rise significantly in the near future. Although the long-term success rate of this new system is unknown a number of reasons will necessitate retreatment of resilon-filled teeth.

So, we conducted a study in our department to comparatively evaluate the dissolving capability of various endodontic solvents such as xylene, tetrachloroethylene and refined orange oil on resilon and gutta-percha at different immersion time intervals.

In clinical practice chloroform is the most effective and most widely used solvent for gutta-percha. Other solvents include refined orange oil, halothane, tetrachloroethylene and xylene. There are no studies reported using above solvents to remove synthetic polymer based root canal filling material (resilon). Tamse et al. found that chloroform was the most effective solvent for all brands of gutta-percha tested. They also reported a difference in solubility between various brands of gutta-percha. [13] The strongest and most commonly used of the solvents, it is quickly effective. Its rapid evaporation also makes it a useful chair side material. [13] However, it has been identified as a potential carcinogen. Because of concerns of carcinogenicity of chloroform clinicians and researchers have developed a renewed interest in finding alternative solvents. [16] Of the possible alternative solvents to chloroform is halothane, a fluorinated hydrocarbon used for induction anesthesia seems to be the most promising due to its biocompatibility. It is nearly as effective as chloroform in dissolving gutta-percha. [16] Halothane, however, is not without any drawbacks. Idiosyncratic hepatic necrosis is a potential side effect following repeated use of halothane-induced anesthesia. Idiosyncratic toxicities are a major concern because they are difficult to predict and are usually not present until the patient has been previously exposed to the agent. They are host-dependent and dose-dependent. [17] The incidence of halothane hepatitis is in the order of one in 10,000 exposures. Other chlorine containing solvents like tetrachloroethylene are not hepatotoxic. [18] So tetrachloroethylene can be considered as a quite safe alternative to chloroform as compared to halothane.

The dissolution of gutta-percha in xylene is considered poorer than in chloroform. For this reason and because of its slow evaporation, xylene is impractical for use at the chair side. However, chloroform tends to be messy and inconvenient in such procedures as it dissolves rather than softens the gutta-percha, leaving residues on the walls of the pulp chamber. It is fast evaporating makes it essential to add more and more solvent as soon as it evaporates. Xylene on the other hand dissolves the gutta-percha more slowly thus allowing a better control and removal of softened rather than liquefied gutta-percha. Softening and mechanical removal of gutta-percha rather than dissolving it may prove to be not only efficient but also a biologically safer procedure. [19] This can be accomplished by a cotton pellet moistened with a solvent in the chamber and removing the root canal filling at the following appointment. Because the aged root canal filing tender to become harder and more difficult to remove, such a procedure is of potential importance because it softens the root canal filling slowly before any attempt is done to remove it. [19] Essential oil extracted from the peel of sweet orange, Citrus aurantium, is easy to obtain and suitable for rapid opening of the root canal, mainly in zinc-oxide cement root fillings associated or not with gutta-percha cones. Orange oil is an excellent alternative solvent as compared to potentially toxic solvents, being used either on zinc-oxide eugenol cement or to soften and dissolve gutta-percha. [20] d-Limonene (refined orange oil) is found widely in citrus and many other plant species and is a major constituent of many essential oils. It is used extensively as a component for flavorings and fragrances, as a chemical intermediate, and in insect repellants. The use of essential oils in endodontics is growing because of their proved safety, biocompatibility and noncarcinogenicity. [21]

In this study ISO no.40 (0.06 taper) gutta-percha and resilon cones were used for checking their dissolution in the respective solvents and did consider the weight of gutta-percha/resilon dissolved although it varied from the specimens in the same lot because the solvent contacts only part of the gutta-percha (surface area); there by dissolving it slowly. Evaluation criteria for the amount of material dissolved was according to Tamse et al. [13] In our study, xylene exhibited the best dissolving capacity both for gutta-percha and resilon followed by refined orange oil and tetrachloroethylene in descending order at 2-minute immersion time interval. However, at 2-minute immersion time interval all of the solvents included in the study showed a better efficacy in dissolving gutta-percha as compared to resilon. At 5-minute immersion time interval, xylene displayed the best dissolving efficacy in dissolving gutta-percha followed by refined orange oil and tetrachloroethylene in descending order. At 5-minute immersion time interval, all of the test solvents exhibited the same dissolving capacity in dissolving resilon. At 5-minute immersion time interval, only xylene showed a better dissolving capacity in dissolving gutta-percha as compared to resilon whereas rest of the solvents dissolved the two obturating materials to the same extent.

The finding in this study indicates that xylene is more effective in dissolving gutta-percha compared to other commonly used solvents such as; refined orange oil as in most other studies. [20] In our study there is significant difference between the dissolution of gutta-percha and resilon in different solvents. The reason might be difference in chemical composition of gutta-percha which contains 17% of gutta-percha, with zinc oxide; zinc silicate forms most of its weight [13] whereas resilon has thermoplastic synthetic polymer based (polyester) root canal core material containing bioactive glass, bismuth oxy-chlorides and barium-sulfate. The filler content is approximately 65% by weight. [5]


   Conclusions Top


Within the limitations imposed by this in vitro investigation, the present study suggests that xylene, refined orange oil and tetrachloroethylene can be used for softening gutta-percha/resilon during retreatment with various techniques. Xylene being the best solvent both for gutta-percha and resilon.

For gutta-percha, none of the solvents except for the tetrachloroethylene showed any significant increase in dissolving capacity as the immersion time was increased from 2 minutes to 5 minutes.

For resilon all of the solvents except xylene and distilled water (control) showed a significant increased dissolving capacity as the immersion time was increased from 2 to 5 minutes.

 
   References Top

1.Stabholz A, Friedman S. Endodontic retreatment: Case selection and technique. Part 2: Treatment planning for retreatment. J Endod 1988;14:607-14.  Back to cited text no. 1
[PUBMED]  [FULLTEXT]  
2.Ingle JI, Bakaland LK: Outcome of endodontic treatment and retreatment: Endodontics, 5 th ed. Hamilton: BC Decker Inc; 2002. p. 747-68.  Back to cited text no. 2
    
3.Younis O, Hembree JH. Leakage of different canal sealants. Oral Surg Oral Med Oral Pathol 1976;41:777-84.  Back to cited text no. 3
[PUBMED]    
4.Madison S, Swanson K, Chlles S. Comparison of coronal microleakage in endodontically treated teeth obturated with gutta percha and various sealers. J Dent Res 1986;65:298.  Back to cited text no. 4
    
5.Shipper G, Orstavik D, Teixeira FB, Trope M. An evaluation of microbial leakage in roots filled with a thermoplastic synthetic polymer based root canal filling material. J Endod 2004;30:342-7.  Back to cited text no. 5
    
6.Teixeira FB, Teixeira EC, Thompson JY, Trope M. Fracture resistance of roots endodontically treated with a new resin filling material. J Am Dent Assoc 2004;135:646-52.  Back to cited text no. 6
[PUBMED]  [FULLTEXT]  
7.Shipper G, Teixeira FB, Arnold RR, Trope M. Periapical inflammation after coronal microbial inoculation of dog roots filled with gutta percha or resilon. J Endod 2005;31:91-6.  Back to cited text no. 7
[PUBMED]    
8.Shashidhar C, Shivanna V, Shivamurthy GB, Shashidhar J. The comparison of microbial leakage in roots filled with resilon and gutta-percha: An in vitro study. J Conserv Dent 2011;14:21-7.  Back to cited text no. 8
[PUBMED]  Medknow Journal  
9.Punia SK, Nadig P, Punia V. An in vitro assessment of apical microleakage in root canals obturated with gutta-flow, resilon, thermafil and lateral condensation: A stereomicroscopic study. J Conserv Dent 2011;14:173-7.  Back to cited text no. 9
[PUBMED]  Medknow Journal  
10.Tay FR, Pashley DH, Williams MC. Susceptibility of a polycaprolactone based root canal filling material to degradation. J Endod 2005;3193-8.  Back to cited text no. 10
    
11.Cohen S, Hargreaves KM. Pathways of the pulp, 9 th ed. London: Mosby; 2005. p. 372.  Back to cited text no. 11
    
12.Wilcox LR, Krell KV, Madison S, Rittman B. Endodontic retreatment: Evaluation of gutta percha and sealer removal and canal reinstrumentation. J Endod 1987;13:453-7.  Back to cited text no. 12
    
13.Tamse A, Unger U, Metzger Z, Rosenberg M. Gutta percha solvents - a comparative study. J Endod 1986;12:337-9.  Back to cited text no. 13
[PUBMED]  [FULLTEXT]  
14.De Oliveira DP, Barbizam JV, Trope M, Teixeira FB. Comparison between gutta-percha and resilon removal using two different techniques in endodontic retreatment. J Endod 2006;32:362-4.  Back to cited text no. 14
[PUBMED]  [FULLTEXT]  
15.Wong R. Conventional endodontic failure and retreatment. Dent Clin N Am 2004;48:265-89.  Back to cited text no. 15
[PUBMED]  [FULLTEXT]  
16.Wourms DJ, Campbell AD, Hicks ML, Pelleu GB. Alternative solvents to chloroform for gutta-percha removal. J Endod 1990;16:224-6.  Back to cited text no. 16
    
17.Chutich MJ, Kaminski EJ, Miller DA, Lautenschlager EP. Risk assessment of the toxicity of solvents of gutta-percha used in endodontic retreatment. J Endod 1998;24:213-6.  Back to cited text no. 17
[PUBMED]  [FULLTEXT]  
18.Hepatitis.org[Internet]. Strasbourg: Hepatitis and employement: Liver and toxic substances in the work place by Dr. Christine Collat; April 1999. Available from http://www.hepatitis.org/hepaetravail_angl.htm  Back to cited text no. 18
    
19.Metzger Z, Marian-Kfir V, Tamse A. Gutta-percha softening: "Hemo-De" as a xylene substitute. J Endod 2000;26:385-8.  Back to cited text no. 19
[PUBMED]  [FULLTEXT]  
20.Oyama KO, Siqueira EL, Santos M. In vitro study of effect of solvent on root canal retreatment. Braz Dent J 2002;13:208-11.  Back to cited text no. 20
[PUBMED]    
21.Vajrabhaya LO, Suwannawong SK, Kamolroongwarakul R, Pewklieng L. Cytotoxicity evaluation of gutta-percha solvents: Chloroform and GP-Solvent (limonene). Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;98:756-9.  Back to cited text no. 21
[PUBMED]  [FULLTEXT]  

Top
Correspondence Address:
Mubashir Mushtaq
Room no.117, Post graduate Clinic, Post graduate Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital Srinagar, Jammu and Kashmir - 190 010
India
Login to access the Email id


DOI: 10.4103/0972-0707.94584

PMID: 22557812

Get Permissions



    Figures

  [Figure 1], [Figure 2]



 

Top
 
 
 
  Search
 
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  
 


    Abstract
   Introduction
    Materials and Me...
   Results
   Discussion
   Conclusions
    References
    Article Figures

 Article Access Statistics
    Viewed2164    
    Printed70    
    Emailed0    
    PDF Downloaded168    
    Comments [Add]    

Recommend this journal