Evaluation of the Antibacterial Activity of Triclosan-incorporated Root Canal Filling Materials for Primary Teeth against Enterococcus faecalis

INTRODUCTION

Pediatric dentistry has been offering comprehensive care for children for ages. A pulpectomy is one of the specialized forms of dental treatment in pediatric dentistry rendered to the primary tooth to retain them, till the time they exfoliate.¹ The main objective of pulpectomy is the total elimination of microorganisms from the root canal and the prevention of subsequent reinfection. This is achieved when a good chemomechanical preparation of the root canal system is followed by impervious obturation with a suitable obturating material.²

Thus, among the various factors properties of the obturating material used also play a key role in determining the prognosis of the pulpectomy-treated tooth. Due to the inability in achieving complete debridement of primary root canals owing to their anatomic complexities, one of the requirements expected from root canal filling materials is antimicrobial property.³ The antimicrobial property of the obturating materials help in eliminating the residual pathogens, which persist in the root canal even after cleaning and shaping while neutralizing their toxins, thereby minimizing the possibility of reinfection.⁴ It is therefore important to study the antimicrobial spectrum of the root canal filling materials used in primary teeth.

Although zinc oxide-eugenol cement (ZOE) has been the commonest choice as a root canal filling material for deciduous teeth, concerns about its limited antimicrobial activity keep the search still on for a suitable alternative.⁵ Endoflas FS is one of the recent root canal filling materials which is an iodoform-based resorbable paste. It contains components similar to that of Vitapex, with the addition of zinc oxide and eugenol. Endoflas FS can disinfect dentinal tubules and difficult-to-reach accessory canals that cannot be disinfected or cleaned mechanically.² However, the long-lasting antimicrobial activity of this root canal filling material over a period of time has not been proven.

On the other hand, triclosan is a broad-spectrum antimicrobial agent active against gram-positive and gram-negative bacteria as well as some fungi and viruses. Although it is most often used for antisepsis of the skin and other surfaces, incorporation of triclosan into the medical devices and dentifrices has well established its effective intraoral use too.⁶ Aim of the present study was to comparatively evaluate the antibacterial activity of the root canal filling materials for deciduous teeth such as zinc oxide eugenol and Endoflas FS when incorporated with 2.5% triclosan. The null hypothesis for the study was set as there will not be any difference in the antibacterial activity of the root canal filling materials for deciduous teeth such as zinc oxide eugenol and Endoflas FS with or without 2.5% triclosan.

MATERIALS AND METHODS

This study was an in vitro intergroup comparative study, which was initiated after obtaining ethical clearance from the Institutional Ethics Committee. It consisted of four groups: group I: zinc oxide and eugenol paste (SS White, Rio de Janeiro, RJ, Brazil), group Ia: zinc oxide + 2.5% Triclosan, group II: Endoflas-FS (Sanlor laboratories, Colombia), and group IIa: Endoflas-FS + 2.5% Triclosan.

The obtained sample size per group was 15 and to detect differences among the means at 0.05 significance level.

RESULTS

At the end of 24 hours, a statistically significant difference in the antibacterial property was observed between all the groups (p < 0.001). The highest zone of inhibition was observed in group IIa followed by group II and group Ia least being in group I (Table 1). Even at the end of the 6th day and 29th day, while a similar trend of antibacterial activity was seen (p < 0.001), pairwise comparison between group I and group Ia showed statistically no significant difference (Tables 2 and 3). Pairwise comparison also revealed statistically no significant difference between group II and group IIa at the end of 29th day.

When intragroup comparison was done at different time intervals using repeated measures of ANOVA, the zones of inhibition produced after 24 hours, 6th day, and 29th day were in the decreasing order. This difference seen between various time intervals was statistically significant for all the groups (p ≤ 0.001) except for group I. Group I showed no significant difference statistically when the antimicrobial activities shown after 24 hours and at the end of the 6th day were compared (p = 0/06) (Fig. 3).

DISCUSSION

While the literature has shown that periapical lesions heal at a higher rate in teeth with negative root canal bacterial cultures obtained at the time of canal filling in comparison with those with positive cultures,¹⁰ it is also been concluded that the part of the root canal space often remains untouched during chemomechanical preparation regardless of the technique and instruments employed.¹¹ Love and Jenkinson,¹² Molander et al.,¹³ Sundqvist and Figdor¹⁴ reported the presence of microorganisms in areas such as isthmus, ramifications, deltas, irregularities, and dentinal tubules even after thorough chemomechanical debridement of the root canal system.

Hence, obtaining a hermetic seal of the root canals with a root canal filling material that possesses an excellent antimicrobial property is critical for endodontic success. Thus, the present study was conducted to evaluate if there is an enhanced antimicrobial activity when a broad-spectrum antimicrobial agent namely triclosan was incorporated into zinc oxide eugenol and Endoflas FS.

It is advised to test the dental materials immediately after mixing, once the final chemical setting stage has been reached. This is because of the formation of various temporary or permanent by-products during the setting reaction which may influence the original results.¹⁵ Thus in the present study, the freshly prepared root canal filling materials were placed into agar plates. The agar diffusion method was used in our study to evaluate the antibacterial efficacy as it has been widely used to test the antimicrobial activity of dental materials and medicaments. The advantages of this method include simplicity, low cost, the ability to test enormous numbers of microorganisms and antimicrobial agents, and the ease to interpret results. Moreover, it demonstrates a good clinical correlation.¹⁶ However, this procedure is influenced by two factors: the material’s microbial toxicity as well as the materials affinity and diffusibility in the culture medium. A material that easily diffuses will produce larger zones of inhibition of bacteria.¹⁵

The results of the present study showed Endoflas FS has better antimicrobial properties when compared with zinc oxide eugenol. This is in accordance with a study done by Kaiwar et al.¹⁷ and Navit et al.¹⁸ who attributed the superior antibacterial efficacy of Endoflas to the presence of both Eugenol and Iodoform in its composition. Iodoform acts by the liberation of iodine. It is believed that iodine, which is an oxidizing agent, can irreversibly oxidize and thus, inactivate essential metabolic compounds like proteins, nucleotides, and fatty acids resulting in cell death.¹⁸ Eugenol, a phenolic compound acts on microorganisms by protein denaturation whereby the protein becomes non-functional.¹⁷ However, the in vitro study by Kothari and Langalia¹⁹ concluded that there is no significant difference in the antimicrobial activity between zinc oxide eugenol and Endoflas FS on E. faecalis.

Another important finding of the present study 2.5% triclosan incorporated Endoflas (group IIa) and zinc oxide eugenol (group 1a) showed higher antimicrobial activity compared with their plain counterparts (group II and group I, respectively). The highest antibacterial activity was shown by Triclosan incorporated Endoflas, the lowest being shown by plain zinc oxide eugenol.

Triclosan is a broad-spectrum antimicrobial agent active against gram-positive and gram-negative bacteria as well as some fungi and viruses. Keeping this in mind, Nudera et al.⁶ conducted a study to evaluate, the antimicrobial effect of triclosan and triclosan with Gantrez on five common endodontic pathogens and concluded triclosan with or without the addition of the copolymer Gantrez S-97 might emerge as a valuable antimicrobial agent for use in endodontic treatment. In a pilot study conducted by Sainulabdeen et al.⁹ evaluating the antibacterial activity of glass ionomer cement incorporated with different concentrations (0.5, 1.25, and 2.5%) of a non-releasing bactericide triclosan against two common cariogenic bacteria—Lactobacillus acidophilus and Streptococcus mutans, triclosan at a concentration of 2.5% was more effective than at lower concentrations. So, in our study, triclosan at a concentration of 2.5% was incorporated into the experimental group.

In the present study, the antimicrobial activity of all the tested root canal filling materials gradually decreased with time, the highest being at the end of 24 hours and the lowest being at the end of the 29th day. The endodontic sealers have shown to give the greatest antimicrobial effects immediately after spatulation, following which there is a gradual loss in antibacterial effect over time which can be supported with the results obtained by Cobankara et al.,²⁰ Fuss et al.,²¹ and Kaplan et al.²²

Based on the results of the present study, we recommend the use of 2.5% triclosan with zinc oxide eugenol or Endoflas as root canal filling materials in highly infected primary teeth requiring pulpectomy to improve the success of the endodontic therapy. Further studies evaluating the same under in vivo conditions may help in substantiating the obtained results of this study.

CONCLUSION

The following conclusions can be drawn from the present study:

• The root canal filling pastes had different inhibitory effects on E. faecalis which gradually decreased with time.
• The incorporation of 2.5% triclosan significantly enhanced the antimicrobial activity of zinc oxide eugenol and Endoflas.

CLINICAL SIGNIFICANCE

The antimicrobial efficacy of a root canal filling material is an ideal requirement, which will help in combating the residual microflora present in the root canal system following chemomechanical preparation. The addition of an antimicrobial agent such as triclosan to the root canal filling materials, enhances their antimicrobial efficacy significantly and thus, rendering the pulpectomy-treated tooth with a better prognosis.

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