Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2011  |  Volume : 22  |  Issue : 1  |  Page : 103--106

Effect of cavity varnish and intermediate restorative material on coronal microleakage in endodontically treated tooth


S Vijay Singh1, Vineeta Nikhil1, Suman Yadav2,  
1 Department of Conservative Dentistry and Endodontics, D.A.V. (C) Dental College and Hospital, Yamuna Nagar, India
2 SGT Dental College and Hospital, Gurgaon, Haryana, India

Correspondence Address:
S Vijay Singh
Department of Conservative Dentistry and Endodontics, D.A.V. (C) Dental College and Hospital, Yamuna Nagar
India

Abstract

Aim: Evaluation of microleakage in endodontically treated teeth that have been coronally sealed with eugenol and noneugenol containing zinc oxide cement, with and without the use of cavity varnish. Materials and Methods: The crowns of single rooted teeth were removed at the cementoenamel junction (CEJ) and the root canals were prepared and obturated with gutta-percha points and zinc oxide eugenol (ZOE) sealer using lateral condensation technique. The samples were randomly divided into four groups-group 1, coronal seal was obtained with ZOE cement; in group 2, three coats of cavity varnish followed with coronal seal of ZOE cement; in group 3, Litark a (noneugenol cement) was placed in the prepared cavity as in group 1; and in group 4, cavity varnish and Litark were placed instead of ZOE as in group 2. The specimens were immersed in 2% methylene blue dye and examined under traveling microscope for evidence of dye penetration of the material. Statistical Analysis: In this study, Kruskal-Wallis test, Mann-Whitney U, and Wilcoxon W tests were used. Results: Kruskal-Wallis test with P=0.000 indicated that a significant difference exists between the four groups. Mann-Whitney U test and Wilcoxon W test showed a significant difference at 0.05 levels as follows: group 1 with group 3 and 4, group 2 with group 3 and 4, and group 3 with group 4. There was no significant difference at 0.05 levels between group 1 and group 2. Conclusion: Group 4 showed significant less amount of dye penetration as compared with other groups.



How to cite this article:
Singh S V, Nikhil V, Yadav S. Effect of cavity varnish and intermediate restorative material on coronal microleakage in endodontically treated tooth.Indian J Dent Res 2011;22:103-106


How to cite this URL:
Singh S V, Nikhil V, Yadav S. Effect of cavity varnish and intermediate restorative material on coronal microleakage in endodontically treated tooth. Indian J Dent Res [serial online] 2011 [cited 2020 Dec 4 ];22:103-106
Available from: https://www.ijdr.in/text.asp?2011/22/1/103/80007


Full Text

Microleakage plays a vital role in endodontic success and failures. The important factors for the success of root canal therapy (RCT), is obturation of root canal in three dimensions, so as to achieve a fluid tight apical and coronal seal, thus decreasing or eliminating the risk of infection or reinfection of the root canal system.

Tempawat et al.[1] reported from the study that inadequate coronal seal can cause bacterial leakage. Studies by Swanson [2] and Madison [3] have shown that coronal seal is probably as important as or more important than the apical seal in long-term success of endodontic therapy. Wein [4] has indicated that improper restoration leads to the loss of more endodontically treated teeth than actual failure of endodontic therapy. According to Seltzer, [5] seepage of irritants from the oral cavity through the leaky coronal restoration, and root canal filling can lead to apical reaction.

Various studies on coronal leakage after completion of endodontic therapy have shown that canal obturation techniques and material do not provide a hermetic seal. Studies of coronal microleakage by Swanson and Madison have shown dye penetration of 79%-85% of root canal length from 3 to 56 days. According to Siqueira et al., [6] 80% root canal obturation with seal apex showed complete recontamination at 60 days. Bobotis et al.[7] demonstrated in their study that intermediate restorative material (IRM) exhibited extensive microleakage when subjected to thermal stresses. Barthel et al.[8] showed that IRM when combined with glass ionomer cement, may prevent bacterial penetration.

The aim of the present study was to compare coronal microleakage in endodontically treated teeth that has been coronally sealed with eugenol and noneugenol-containing zinc oxide cement, as this is commonly used during RCT or obturation and before the placement of permanent restoration, so as to evaluate the effect of cavity varnish on the sealing ability of temporary coronal sealing material with an objective to find out cheap, effective, and easily available sealing material.

 Materials and Methods



One hundred and thirty freshly extracted, intact, noncarious human single-rooted teeth were selected for the study. The crowns were removed at the CEJ with a carborundum disk in the presence of water. The working length was kept 1 mm short of the point at which the #15 file exited the apical foramen. The coronal portion of the canal was flared with gates-glidden burs #2 and #3 and the root canal was prepared by step back technique using K-file (Mani, India) to a size of 40 numbers, using 2.5% solution of sodium hypochlorite as an irrigant. Apical patency was maintained by recapitulation with #15 file, throughout the cleaning and shaping procedure. The canals were then dried with sterile absorbent point followed by obturation with gutta-percha points (Deadent, Korea) and ZOE sealer (DPI, India) using lateral condensation technique.

The prepared samples were randomly divided into four experimental groups of 30 teeth each and two control groups as positive and negative controls of 5 teeth each. Gutta-percha was removed from the coronal part of the teeth by using a marked heated plugger to prepare a 3 mm clean deep cavity.

In group 1, ZOE cement (DPI, India) was mixed with powder liquid in the ratio of 6:1 and was placed in the prepared cavity over the gutta-percha. The cement was condensed and excess was removed.

In group 2, a thin coat of cavity varnish (Harvard, Germany) was applied with the help of a brush over the prepared cavity and dried with gentle air stream for 30 s, this was repeated till 3 layers of cavity varnish was applied and dried. ZOE cement (DPI, India) with powder liquid in the ratio of 6:1 was then placed in the prepared cavity over the gutta-percha as in group 1.

In group 3, a thick layer of Litark (Lascod, Italy) noneugenol cement was placed in the prepared cavity as in group 1.

In group 4, cavity varnish and Litark were placed instead of ZOE as in group 2.

Gutta-percha was kept intact at the coronal seal of the specimen in group 5 and group 6, which consisted of 5 positive and 5 negative controls.

The specimens were then stored in a humidor at 37°C for 48 h. The specimens were then subjected to thermo cycling at 7°C and 55°C for 100 cycles. A complete cycle lasted for 2 min and consisted of 30 s at each bath. After thermo cycling, the samples were coated with sticky wax, leaving the canal orifice uncovered except in group 6, that is, the negative control group in which the whole tooth was covered.

All samples were immersed in 2% methylene blue dye for 1, 3, and 7 days. After immersion in the dye for 1, 3, and 7 days, the teeth were rinsed in tap water and dried. Nail polish and sticky wax was completely removed. The mesial and distal surface of all the teeth were grooved with the use of a tapered fissure carbide bur in a high speed hand piece without water spray nearly to the depth of the canal. The tooth was then split through its longitudinal aspect using a mallet and chisel.

The tooth-sealing material interface was examined under traveling microscope for evidence of dye penetration into the material. All sealing material and gutta-percha were removed from the entire wall, and the surface was examined for evidence of dye penetration. In this study, dye penetration was considered if the leakage was more than 3 mm and no leakage if it was less than 3 mm as shown in [Figure 1].{Figure 1}

Statistics

In this study, Kruskal-Wallis test, Mann-Whitney U, and Wilcoxon W tests were used. The P values less than 0.05 were considered as significant.

 Result



The positive control group showed complete dye penetration, whereas the negative group showed no dye penetration. In group 1 and group 2, 100% dye leakage was observed from day 1 and continued to day 3 and 7, whereas group 3 showed 50% leakage on day 1 followed by 95% on day 3 and 100% on day 7, and in group 4, there was no dye penetration on day 1, 20% dye penetration on day 3 and 40% on day 7. The result showed a significant less amount of dye penetration when litark was used along with cavity varnish (group 4) as compared with the other groups.

In this study, the Kruskal-Wallis test as shown in [Table 1], with P=0.000, indicated that a significant difference exists between the four groups.

According to Mann-Whitney U test and Wilcoxon W test, as shown in [Table 2], there is a significant difference at 0.05 levels between the groups: group 1 with group 3 and 4, group 2 with group 3 and 4, and between group 3 with group 4. There was no significant difference at 0.05 levels between group 1 and group 2.{Table 1}{Table 2}

 Discussion



Root canal treatment with an excellent obturation of the canal is incomplete if the restoration of the access cavity results in microleakage. According to Roghanizad and Jones, [9] coronal seal is of critical importance for successful treatment, and obturated root canal is not an adequate barrier to leakage. Coronal leakage can occur due to various factors: dissolution of cement by saliva, improperly placed restoration that results in fracture or dislodgement, lack of bond between tooth and restoration, coefficient of thermal expansion, and so on. Coronal seal that is improper results in recontamination of root canal and periapical tissues due to the penetration of bacteria and their products and other irritants from the oral cavity. Methylene blue dye 2% was used because of its low molecular weight and as it penetrates more deeply than other dyes. [10] Moreover, Pitout et al. (2006) [11] found a dye penetration method to produce similar results to bacterial leakage method. In this study, the tooth was split using a chisel after giving a deep groove on the mesial and distal surface of the tooth using tapered fissure carbide bur in a high-speed hand piece without water spray nearly to the depth of the canal, so as to obtain an accurate dye penetration reading and to avoid any spread of dye, which might occur along the specimen if cut the whole length using the diamond disk or tapered fissure carbide bur.

Evaluation of microleakage when ZOE and ZOE with varnish were used showed extensive leakage during day 1, 3, and 7 days. However, when litark was used, the dye leakage was found to be comparatively less than ZOE and ZOE with varnish. Moreover, when litark was used along with varnish, the number of samples with dye leakage was minimum at day 1 and significantly less on day 3 and day 7 as shown in [Table 3].{Table 3}

This study is in contrast to the study done by Guerra et al., [12] Bergenholtz et al., [13] and Brannstrom, [14] which stated that ZOE provides a fluid tight seal. The extensive microleakage when ZOE was used correlates to the study by Tewari and Tewari, [15] according to which microleakage can be due to dissolution or disintegration of ZOE. Set ZOE cement consists of a loose matrix of zinc eugenolate, which is easily hydrolyzed by moisture to eugenol and zinc hydroxide. Moreover, a high degree of microleakage was observed when ZOE was used along with cavity varnish. This may be due to eugenol that is present, which softens the resin present in the cavity varnish.

The better sealing ability of litark at day 1 and litark with cavity varnish at day 1, 3, and 7 may be because of less dissolution of the cement and non-interference of cement with varnish as eugenol is not present.

This study corresponds to the study by Galvan et al.[16] where IRM showed extensive leakage, contraindicating its use for an extended period of time.

 Conclusion



The present study concludes that IRM or temporary cements are ineffective when used as coronal seal in endodontically treated teeth. However, when used for a short duration, noneugenol-containing zinc oxide cement with varnish is advisable. A better alternative may be to place a permanent restoration, which has an effective coronal seal right after obturation. However, more studies are required to evaluate different temporary coronal sealing material and methods to provide an easy, effective, and inexpensive solution to prevent the problem of coronal leakage.

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