Comparative evaluation ofantimicrobial activity of herbal oils and their ability in disinfection of gutta percha cones - Aninvitro study

Introduction

Enormous efforts should be made to remove microorganisms from root canal during routine endodontic procedures¹ . Gutta percha cones are most commonly used obturating material for root canal system because they are biocompatible, dimensionally stable, radiopaque, and thermoplastic² . Gutta percha cones are manufactured in proper aseptic conditions and possess antimicrobial properties. But these cones can be easily contaminated by glove handling or while removing them from their packages. These cones cannot be sterilized by conventional heat process because they are sensitive toheat and may cause alteration to GP structure³ . Among all chair side disinfectants, Sodium hypochlorite is the most commonly used disinfectant. But one of its main disadvantages is that, in all concentration crystal deposition within the canal is reported which affects bond between sealer and canal walls⁴ .

Herbs are known to have antimicrobial, antiseptic, antiviral, antifungal, and immunomodulatory properties which make their use common in food and pharmaceutical industries.⁵

Therefore, the objective of the present study is to evaluate the antimicrobial properties of Lemon grass oil, Peppermint oil and Cinnamon oil against the commonly isolated root canal microorganisms like E. faecalis and S. aureus.

Further the study was carried out to check contamination of gutta percha cones during glove handling and to evaluate the effectiveness of herbal oils in disinfection of gutta percha cones within one minute.

Materials and methods

Materials

This was an experimental in vitro study using microorganisms E.faecalis [ {ATCC}-29212], S. aureus [ATCC25923] and herbal oils namely Lemon grass oil, Peppermint oil and cinnamon oil.

Methodology

The study was carried out in three steps:

Firstly, inoculums of E.faecalis and Staphylococcus aureus were prepared in nutrient broth to check antimicrobial efficacy of lemon oil, cinnamon oil, peppermint oil and sodium hypochlorite. Ten petri dishes were used in this study to culture each species. Then, template was used to make wells of 4mm in each petri dish and was named according to respective medicament dispensed (0.5 ml). Strains were incubated at 37 C for 24 hours to check the antimicrobial efficacy by measuring zone of inhibition.

Group1- Lemon grass oil

Group 2- Cinnamon oil

Group 3-Peppermint oil

Group 4 –Sodium hypochlorite

(positive control)

Then to evaluate the contamination of gutta percha cones. Sixty gp cones were taken out from freshly opened packet and glove handled to mimic clinical situation. These cones were carried to Department of Microbiology in sterile container. Gutta percha cone cutter was used to cut these gp into two equal halves.

First half of cones were placed in eppendorf tubes containing BHI broth and then incubated for 24 hours. Turbidity was observed in all tubes which shows that GP cones get contaminated during handling.

Second halves were divided into four groups containing 15 cones in each group and treated with respective medicament for one min. Excess oil or medicament was wiped with sterile tissue paper.

Group 1- Lemon grass oil

Group 2 - Cinnamon oil

Group 3- Peppermint oil

Group 4- Sodium hypochlorite Each cone was then placed in the eppendorf tube containing BHI broth and incubated for 24 hours to check turbidity.

Statistical analysis

Statistical Package for Social Sciences [SPSS] for Windows Version 22.0 Released 2013. Armonk, NY: IBMCorp.was used to perform statistical analysis. Inferential Statistics: Oneway ANOVA test was used to comparemean zone of inhibition between 04 group. The level of significance was set at P<0.05.

Results

For both tested micro-organisms, group 2 (Cinnamon oil) showed largest zones of inhibition (mean ± SD), 28.6 ± 1.18 mm, 30.8 ± 1.4mm against E. faecalis, S. aureus.

One-way ANOVA for tested micro organisms revealed statistically significant difference in all possible pair wise comparisons for all groups.

Microbial assays showed maximum efficacy with group 2 Cinnamon oil for decontamination of GP cones in 1 minute, followed by NaOCl, Lemon grass oil and Peppermint oil.

Discussion

Most important step during endodontic treatment is tomaintain aseptic chain during cleaning, shaping andobturation. Therefore, disinfection of gutta percha cones isimportant for success of root canal therapy⁶ .

E.faecalis and Staphylococcus aureus are the mostcommon microbial species isolated from root canals. Presence of resistant microbial species like E. faecalis and Staphylococcus aureus affect the outcome of root canaltreatment.

E. faecalis is a gram-positive facultative anaerobe and an outstanding survivor in the root canal system. It causes failure of endodontically treated teeth (5% in untreated teeth whereas 29%–77% in root filled teeth.⁷

Baumgartner et al. proved that microbial biofilm of S. aureus on tissue or biomaterial surface is the cause of refractory periapical diseases. Therefore, these microbial species were selected for this experimental study⁸ .

various herbal extracts are used in treatment of many systemicdiseases because of their antimicrobial and anti-inflammatory properties⁵ . So, this study was done to check antimicrobial property of herbal oils and their ability indisinfection of gutta percha cones in one minute.

Saddiq et al. and Falcao et al. reported, citral epoxide is responsible for antimicrobial activity of lemon grass oil^9,10.

Mentha piperita is extensively used in, various products like toothpastes, mouthwashes and digestive tablets. It includes monoterpinic alcohols mainly menthol (38-48%), ketones (2030%), some monoterpens and oxides. It is a good antiseptic, antibacterial and antiviral.

Vasconcelos et al. reported, Cinnamon oil possess antibacterial activity because of its ability of inhibiting ATPase, cell division inhibition etc¹¹.

In this study the antimicrobial efficacy of herbal oils was analyzed by comparing the diameters of inhibition zone against E. faecalis, S. aureus. All the groups (control and experimental) showed significant zones of inhibition suggesting potent antimicrobial activity. Inhibition zones for Cinnamon oil was reported largest, followed by sodium hypochlorite, Lemon grass oil and Peppermint oil.

In the second part of study, Cinnamon Oil showed 100% decontamination followed by Sodium hypochlorite, Lemon grass oil, and Peppermint oil in 1 minute.

Gutta percha cones can be easily contaminated if nothandled correctly³ . So,cinnamon oil is a potentantimicrobial agent for rapid disinfection of GP cones inoneminute and can be an alternative to sodiumhypochlorite.

Conclusion

Within the limit of this study it can be concluded that herbal oils are effective substitutes to the chemical disinfectants. Cinnamon oil is most effective in chair side disinfection of gutta percha cones in one minute.