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Table of Contents
Year : 2013  |  Volume : 3  |  Issue : 1  |  Page : 21-24

Evaluation of sealing ability of a root canal sealer with various antibiotic additives: An in vitro study

1 Department of Conservative Dentistry, Kantipur Dental College and Hospital, Kathmandu, Nepal
2 Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Manipal, Karnataka, India

Date of Web Publication25-Oct-2013

Correspondence Address:
Kundabala Mala
Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Manipal, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2229-5194.120521

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Introduction: One of the reasons for persistent endodontic infection is the retention of microorganism on root canal walls. Studies on endodontic prognosis have demonstrated that the addition of antibiotics to the root canal sealer is proven to be beneficial to prevent re-infection and impart antimicrobial property for a longer time. Aims and Objectives: The primary aim of this study is to determine and the secondary aim is to compare the sealing ability of Kerr Pulp Canal Sealer (extended working time) (PCS [EWT]) when used with or without various antibiotic additives viz.; amoxycillin, doxycycline and metronidazole using apical dye leakage method. Materials and Methods: An in vitro study was performed on extracted human teeth, obturated with sealer-antibiotic combinations and sealers alone. Rhodamine-B dye penetration was done for 10 days and the teeth were sectioned and viewed under light microscope; then linear dye penetration was measured and statistically analyzed. Results: Kerr PCS (EWT) showed mean apical leakage of 3.475 mm (P = 0.655, Z = 0.447), whereas PCS (EWT) combined with amoxycillin showed a mean apical leakage of 0.997 mm (P = 0.084, Z = 1.727) showing its clinical significance. PCS (EWT) + amoxycillin showed the best sealing ability with least apical leakage. Conclusion: Addition of antibiotics such as amoxycillin, doxycycline and metronidazole to Kerr PCS (EWT) sealer is recommended as it helps to improve the antibacterial property and the apical sealing ability.
Clinical Relevance to Interdisciplinary Dentistry

  1. Bacteria and by-products in the dentinal tubules can cause reinfection of root canal treated teeth.
  2. The continuous release of antibacterial agent is desirable to prevent reinfection in root canal treated teeth.
  3. This original research hopes to prevent reinfection under the restorations of endodontically treated teeth by the action of additives in root canal sealers and by controlling the microleakage.

Keywords: Antibiotic additives, apical leakage, persistent infections, root canal sealers

How to cite this article:
Shrestha S, Mala K. Evaluation of sealing ability of a root canal sealer with various antibiotic additives: An in vitro study. J Interdiscip Dentistry 2013;3:21-4

How to cite this URL:
Shrestha S, Mala K. Evaluation of sealing ability of a root canal sealer with various antibiotic additives: An in vitro study. J Interdiscip Dentistry [serial online] 2013 [cited 2023 Jun 3];3:21-4. Available from: https://www.jidonline.com/text.asp?2013/3/1/21/120521

   Introduction Top

The bacteria and their by-products are the primary etiologic agents for periapical lesions and pulpal necrosis causing failure of root canal therapy. Pulpal pathogens are typically polymicrobial in nature with equal proportion of Gram-positive and Gram-negative bacteria dominated by anaerobic species. The true significance of bacteria in endodontics was shown by Kakehashi in 1965. [1]

One of the parameters for successful endodontic therapy is to obturate the root canal system three dimensionally to get fluid tight seal of the apical foramina and accessory canals. Presence of microbes in the dentinal tubules can be counteracted by the antimicrobial properties of sealing and obturating materials. The continuous release of antibacterial agent is desirable where there are periapical lesions and unpredictable root morphology and canal shapes. [2]

Antibiotics are routinely administered in endodontic practice, either systemically or locally. Local application of antibiotics within the root canal is more effective mode for delivering the drug. [3] According to Abbott et al., chronic alveolar infections are associated with non-vital teeth and periapical lesions that have no blood supply reaching the pulp space. The main advantage of local antibiotics compared with the systemic use is the local concentration of the antimicrobial in the required site, substantially preventing its systemic complications. [4]

The first reported case of local use of an antibiotic in endodontics was in 1951 when Grossman used a poly antibiotic paste known as the mixture of penicillin, bacitracin, streptomycin and caprylate sodium (PBSC). Wide array of antibiotics, single or in combination are being used as intra-canal medicaments with satisfactory results. Some of the examples are tetracycline, clyndamycin, penicillin, bacitracin, streptomycin, nystatin (modification of PBSC by replacement of caprylate sodium by nystatin), Ladermix paste (demeclocycline 3.2% and triamcinolone 1%), Ladermix in combination with calcium hydroxide, Septomixine forte (neomycin + polymixin B sulphate). Recently triantibiotic paste consisting of metronidazole, ciprofloxacin and minocycline appears to be the most promising one. [4]

Kerr Pulp Canal Sealer (PCS) has more recently emerged as a popular sealer. However, one of its disadvantages was the rapid setting time in high heat and humid regions. To solve this problem, Kerr reconfigured Kerr PCS extended working time (EWT) (Sybron Endo/Kerr, Calif.) with 6 h extended working time. Recent apical microleakage studies have shown the regular PCS to be significantly better than Roth 801 and AH26 in 24 weeks. Additional research comparing sealing ability between regular PCS and the new EWT sealer found no significant difference.

Hoelscher et al. found that combining antibiotics in sealer enhance the antimicrobial activity of the sealer against Enterococcus faecalis. However, there is no literature available on evaluation of sealing ability of the sealer when combined with antibiotics. [5] Hence, the present study was conducted to evaluate and compare the sealing ability of Kerr PCS (EWT) when used alone and in combination with various antibiotics.

   Materials and Methods Top

The present study was conducted to evaluate the post-obturation apical seal obtained with Kerr PCS (EWT) and its combination with different antibiotics viz; amoxycillin, doxycycline and metronidazole and compare the quality of seal between the groups.

A total of 56 normally configured single rooted extracted human teeth with type I root canal anatomy were selected for the study. The access cavities were prepared through the crown as described by Ingle using endo access bur (Densply-Maillefer, Ballaigues, Switzerland) under high speed handpiece (NSK, Japan) with air-water spray. The pulp tissues were extirpated and working length was determined. The apical enlargement during cleaning and shaping were done until #25 or #30 K-files.

The canal preparation was carried out using rotary protaper files (#F2, F3Densply-Maillefer, Ballaigues, Switzerland) to clean and shape the canals according to the technique described by Yared [6] using contrangle Anthrogyr handpiece (Sybron Endo, Av. Andre Lasquin Sallanches, France). The irrigation was done with 3% sodium hypochlorite, (Novo Dental Products, Mumbai, India) recapitulation was done in between the preparations. Specimens were divided into four groups of 14 teeth each.

Sealer-antibiotic combination was prepared manually by mixing the antibiotic to the sealer. Sealer, antibiotic combinations used were; Group I: PCS (EWT), Group II: PCS (EWT) + amoxycillin (Ranbaxy Laboratories, Delhi, India), Group III: PCS (EWT) + doxycycline (Dr. Reddys laboratories Ltd., Yanam, India), Group IV: PCS (EWT) + metronidazole (Piramal Healthcare Ltd., Thane, India). The amount of antibiotic added to a root canal sealer was equivalent to 10% by weight of the sealer. The method of preparation followed the method described by Hoelscher in which enteric coatings of antibiotic tablets were removed then grounded in a mortar and pestle until fine particles were formed. [5] Then, the powdered antibiotic and sealers were weighed separately in a digital weighing machine to make 1:10 proportion of antibiotic with sealer and both the powders were mixed. The sealer was mixed according to manufacturer's specifications for obturation.

Canals were coated with sealer and obturated with gutta-percha (Protaper Gutta-percha #F 2 and #F 3 (Densply-Maillefer, Ballaigues, Switzerland) and compacted laterally with gutta-percha points (Densply- Maillefer, Ballaigues, Switzerland) and the access cavities were sealed with resin modified zinc oxide eugenol (Dental Products of India, Mumbai, India) All obturated teeth were placed in humidor (Pathak Electrical Works, Bombay, India) at 37°C with 100% relative humidity for 1 week. Teeth were removed; fan dried and coated with nail varnish except at apical 2-3 mm and let dry for an hour then the second coat of nail varnish was applied.

Dye preparation

Rhodamine-B dye (Loba Chemie P. Ltd., Mumbai, India) was prepared to 2% solution by dissolving 2 g of dye to 100 ml of distilled water and was filtered .

The apical portion of the teeth was immersed in 2% of Rhodamine-B dye in a dappen dish, which was sealed with modelling wax and was kept vertical. The samples were then kept in the humidifier for a period of 10 days; then the teeth were removed from the dye following which they were rinsed in the tap water and dried.

Nail varnish from the apical half of the roots were removed using the scalpel blade. Roots were trimmed to thin slices either from mesial or distal aspect using carborandum discs mounted on a straight handpiece (NSK, Japan).until the gutta-percha was seen and the thickness of the tooth was sufficient to allow passage of light under the microscope. Following the exposure of the canal space, gutta-percha was removed and teeth were examined under the microscope for the highest level of dye penetration.


The dye penetration in each tooth was examined under light microscope (Olympus C ×21TR) of ×40 magnification. Images were captured by the camera attached (Olympus SP-350) [Figure 1]. Thereafter, the captured images were transferred to the computer and the length of the linear dye penetration of all the images were estimated using ImageJ software (Java-based image processing program developed at the National Institutes of Health). The software was calibrated using the slide micrometer with graduation in millimeter. The scale was set at 56 pixel = 0.1 mm, which was obtained by linear measurement of the captured stage micrometer image. All images were then analyzed using the line tool.
Figure 1: Dye penetration under microscope

Click here to view

   Results Top

Data analyzed using Statistical Package for Social Sciences (SPSS), version 11.5 (SPSS Inc., Chicago IL). Descriptive statistics were calculated for linear apical leakage in millimetre for all groups is given in [Table 1]. Mann-Whitney U-test was done. Statistical program for the apical leakage values with P < 0.05. The statistical analysis was showed following results:

  1. Amoxycillin as additive to PCS (EWT) sealer (Group II) showed the best result with the least mean apical leakage value of 0.997 and standard deviation (SD) 0.640, which is clinically significant.
  2. Doxycycline as additive to PCS (EWT) (Group III) follows Group II with second least mean value 1.160, SD 0.270.
  3. Metronidazole as additive to PCS (EWT) (Group IV) showed highest leakage among the additive groups with a mean value 2.568, SD 1.541.
  4. PCS (EWT) sealer alone [Group I] has the highest mean apical leakage value of 3.475, SD-2.961.
Table 1: Descriptive statistics values for all groups

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   Discussion Top

The presence of bacteria in the dentinal tubules and cementum even after the endodontic treatment has been demonstrated by various studies. [7],[8],[9] Good obturating material and the sealer provide the fluid tight seal, thus prevents all the pathways of infection to prevent reinfection. Root canal sealer with high antimicrobial activity is desired to decrease the growth and prevent the re-entry of the microorganisms into the root canal system. [10],[11],[12],[13]

In the present study, Kerr PCSs (EWT) was selected because it is well- studied and proven with sufficient apical sealing ability. [14],[15]

Result of the present study showed that, whenever the antibiotic additives were added to the sealer, the apical leakage was reduced consistently irrespective of the type of antibiotic additive used. Even though, there is no statistically significant difference between the groups, it has shown clinical significance. This could be due to the additives that must be forming the composite material, which is not conducive to dye leakage. It can be assumed that, the additive may have increased the density of the combinations (sealer + antibiotic additives) when compared with sealer alone. Similar results were found by Gambarini et al. when they tested sealing ability of Kerr PCS and Bioseal (ZnOE with the addition of hydroxyapatite) sealer and found that additive did not adversely affect the sealing property of Bioseal. [16]

Among all experimental groups, when amoxicillin was added to Kerr PCS (EWT) sealer, the apical leakage was very less, which signifies the closer adaptation of the combination to the radicular dentin. Addition of doxycycline to PCS (EWT) showed equally good result with less apical leakage, which signifies that the sealing ability of this combination is equal to PCS (EWT) + amoxycillin without statistical significance.

Hoelscher et al. conducted a study to enhance the antimicrobial activity of sealer by adding antibiotics in the Kerr PCS (EWT) and performed agar diffusion test for common antibiotics namely amoxycillin, doxycyline and metronidazole. [5] They showed that combining antibiotics to sealer by 10% of sealer weight resulted in a significant increase in antibacterial efficacy of the sealer to E. faecalis, and recommended further research regarding how addition of antibiotic may affect the sealing properties.

Kreth et al. in 2008 evaluated the antimicrobial efficacy of silver ions added to an endodontic sealer (Kerr PCS) by performing growth inhibition studies and bacterial viability tests. The results showed that the silver ions enhanced the antimicrobial activity of the root canal sealer against Streptococcus mutans. [17]

Further in vivo studies are recommended to evaluate the efficacy these combinations and their systemic effects as well as SEM studies may show their sealability and action against various microbes in the root canal system.

   Conclusion Top

From the result of the present study, it can be concluded that;

  • Addition of antibiotics such as amoxycillin, doxycycline and metronidazole to Kerr PCS (EWT) sealer improves the post obturation apical seal
  • Metronidazole is not as good as amoxycillin and doxycycline as an additive to Kerr PCS (EWT) sealer to improve the sealing ability of the sealer to radicular dentin.

   Acknowledgment Top

We thank Dr. Ramya Shenoy, Department of Public Health Dentistry, M.C.O.D.S. Mangalore for the statistical analysis. We are also indebted to Dr. Manish Juneja, Former reader of Department of Oral Pathology, M.C.O.D.S. Mangalore for the microscopic evaluation of the samples.

   References Top

1.Ingle JI. Bakland LK. Endodontics. 5 th ed. Hamilton, Ontario, India: BC Decker, Elsevier; 2006. p. 65.  Back to cited text no. 1
2.Bergenholtz G, Spångberg L. Controversies in endodontics. Crit Rev Oral Biol Med 2004;15:99-114.  Back to cited text no. 2
3.Gilad JZ, Teles R, Goodson M, White RR, Stashenko P. Development of a clindamycin-impregnated fiber as an intracanal medication in endodontic therapy. J Endod 1999;25:722-7.  Back to cited text no. 3
4.Mohammadi Z, Abbott PV. On the local applications of antibiotics and antibiotic-based agents in endodontics and dental traumatology. Int Endod J 2009;42:555-67.  Back to cited text no. 4
5.Hoelscher AA, Bahcall JK, Maki JS. In vitro evaluation of the antimicrobial effects of a root canal sealer-antibiotic combination against Enterococcus faecalis. J Endod 2006;32:145-7.  Back to cited text no. 5
6.Yared G. Canal preparation using only one Ni-Ti rotary instrument: Preliminary observations. Int Endod J 2008;41:339-44.  Back to cited text no. 6
7.Clark-Holke D, Drake D, Walton R, Rivera E, Guthmiller JM. Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layer. J Dent 2003;31:275-81.  Back to cited text no. 7
8.Saleh IM, Ruyter IE, Haapasalo M, Ørstavik D. Bacterial penetration along different root canal filling materials in the presence or absence of smear layer. Int Endod J 2008;41:32-40.  Back to cited text no. 8
9.Love RM, Jenkinson HF. Invasion of dentinal tubules by oral bacteria. Crit Rev Oral Biol Med 2002;13:171-83.  Back to cited text no. 9
10.Smadi L, Mahafzah A, Khraisat A. An in vitro evaluation of the antimicrobial activity of nine root canal sealers. J Contemp Dent Pract 2008;9:60-7.  Back to cited text no. 10
11.Cobankara FK, Altinöz HC, Ergani O, Kav K, Belli S. In vitro antibacterial activities of root-canal sealers by using two different methods. J Endod 2004;30:57-60.  Back to cited text no. 11
12.Gomes BP, Pedroso JA, Jacinto RC, Vianna ME, Ferraz CC, Zaia AA, et al. In vitro evaluation of the antimicrobial activity of five root canal sealers. Braz Dent J 2004;15:30-5.  Back to cited text no. 12
13.Ingle JI, Bakland LK, Baumgartner JC. Ingle's endodontics. 6 th ed. Hamilton, Ontario, India: BC Decker; 2008. p. 1033.  Back to cited text no. 13
14.Yared GM, Bou Dagher F. Sealing ability of the vertical condensation with different root canal sealers. J Endod 1996;22:6-8.  Back to cited text no. 14
15.Rothier A, Leonardo MR, Bonetti I Jr, Mendes AJ. Leakage evaluation in vitro of two calcium hydroxide and two zinc oxide-eugenol-based sealers. J Endod 1987;13:336-8.  Back to cited text no. 15
16.Gambarini G, Tagger M. Sealing ability of a new hydroxyapatite- containing endodontic sealer using lateral condensation and thermatic compaction of gutta-percha, in vitro. J Endod 1996;22:165-7.  Back to cited text no. 16
17.Kreth J, Kim D, Nguyen M, Hsiao G, Mito R, Kang MK, et al. The antimicrobial effect of silver ion impregnation into endodontic sealer against streptococcus mutans. Open Dent J 2008;2:18-23.  Back to cited text no. 17


  [Figure 1]

  [Table 1]


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