Evaluation of antimicrobial efficacy of Aloe vera and its effectiveness in decontaminating gutta percha cones

Abstract

Aim:

The aim of this study was to evaluate the antimicrobial efficacy of Aloe vera and to determine its effectiveness in decontaminating gutta percha cones.

Materials and Methods:

A concentrated extract of Aloe vera was used to check for the antimicrobial efficacy using the agar well diffusion method. Presence of zones’ of diffusion was identified against three common GP contaminants namely, E.coli, E.faecalis and Staph. aureus. New GP Cones, freshly taken out of the packet were then decontaminated for 1minute using Aloe vera gel and then placed in thioglycolate broth to check for the presence of turbidity.

Results:

The zones of inhibition on the agar plate were measured as 24mm,21mm and 24mm respectively. The broth remained clear even after 48 hours of incubation.

Conclusion:

We conclude that Aloe vera is indeed effective as a GP decontaminant and it holds a promising future as a medium for storage of GP cones.

INTRODUCTION

The primary objective of endodontic therapy is to maintain an aseptic chain right from the access opening to the permanent coronal restoration of the tooth. Eliminating or decreasing the number of micro-organisms is of considerable importance for endodontic success. Gutta percha (GP) is a dried coagulated extract of plants of palaquiam of the blanco genus of sapotaceae family, and was introduced to dentistry in 1847 by Edwin Truman.[1,2] It still continues to maintain its position as an important dental material and has emerged as the prime root canal filling material. The SS White Company began marketing GP points for dental use in 1887. GP supplied commercially is not usually sterilized or decontaminated before obturation. Also, it cannot be sterilized by moist or dry heat as this carries a risk of physical deformation. However, chair side decontamination prior to obturation cannot be ignored. Many chemicals such as, hydrogen peroxide, chlorhexidine, ethyl alcohol, polyvinyl pyrolidone iodine, quartenary ammonium compounds have been tried for GP decontamination. Recently, the use of electron beam sterilization has also been tried. However, none of these methods have been proven as fully effective. The recommended method for decontamination of GP points consists of treating the cones using a 1% Sodium hypochlorite for 1 minute (Milton's solution), or 0.5% Sodium hypochlorite for 5 minutes (Dakin's solution).[3] Here, the risk of Sodium hypochlorite causing crystal deposition within the canals which can impede the obturation cannot be ignored. The purpose of this study was to evaluate the effectiveness of a herbal alternative, Aloe vera gel for rapid decontamination of gutta percha cones.

Aloe barbadensis Mill, is a short succulent herb resembling a cactus, with green dagger shaped fleshy, spiny and marginated leaves, filled with a clear viscous gel. Aloe vera has potent antibacterial, antifungal, and antiviral properties.[4,5] The antimicrobial effects of Aloe vera have been attributed to the plant's natural anthraquinones which have demonstrated in vitro inhibition of Mycobacterium tuberculosis and Bacillus subtilis. Aloe juice has been found to be bacteriostatic against Staphylococcus aureus, Streptococcus pyogenes and also Salmonella paratyphi.[6,7] In an in vitro disc diffusion study by Suleyman et al Streptococcus faecalis and Candida albicans were cultured to contain 10⁸-10⁹ CFU mL/1 levels of organism. A 100% Aloe vera juice obtained from the cold pressed leaves of the plant were used and the results obtained showed significant zones of inhibition of 20mm and 30mm against both these organisms[8]. Aloe vera is also known to be virucidal, especially against herpes virus.

MATERIALS AND METHODS

Test organisms

Reference strains of three most common GP contaminants, Eschericia coli, Enterococcus faecalis and Staphylococcus aureus were obtained from the Department of Microbiology, JIPMER, Puducherry.

Preparation of the extract

The leaves of the plant were washed with distilled water, cut opened, and fresh pulp was collected. The gel was dried in an oven at 80°C for 48 hours and then powdered. An ethanol extract was obtained by dissolving 20 grams of the powder in 200 ml of ethanol. The contents were then filtered through Whatmann filter paper no1, and the filtrate was evaporated for dryness.

Antimicrobial activity of Aloe vera

The antibacterial activity of the extract was tested using Agar well diffusion technique. The reference strains were cultured overnight in thioglycolate broth, and the culture was streaked on a plate of blood agar. Three wells of 5 mm × 5 mm measure were made with the help of a template on the surface of the agar plate. About 0.1 ml of the extract was delivered into the well using a micropipette. The other two wells were filled with 5.25% of sodium hypochlorite and 0.9% normal saline as positive and negative controls, respectively. They were then incubated at 37°C for 24 hours, and closely monitored for the development of clear zones around the extracts. The antibacterial activity was assessed by the diameter of the inhibition zone. A clear zone of inhibition was obtained against all the three organisms.

Gutta Percha decontamination

A new pack of Dia-ProT^plus (Diadent Europe.B.V,Almere, Netherlands) F2 Size Protaper gutta percha points were used for the procedure. The pack was opened under sterile conditions and four points were taken out using a sterile tweezer. The points were then placed inside the freshly prepared thioglycolate broth, and incubated for 24 hours. Simultaneously, four new GP cones were removed, and decontaminated for one minute in 90% Aloe vera gel. The cones were then removed from the gel, and cleaned free of the gel using a sterile gauze, and then incubated in thioglycolate broth for 24 hours. Both the tubes were then closely monitored for the development of turbidity.

RESULTS

The antimicrobial efficacy was assessed by the presence of zones of inhibition. Escherichia coli, Enterococcus faecalis, Staphylococcus aureus showed 24 mm, 21 mm and 24 mm inhibition zones respectively, which was almost equivalent to 5.25% Sodium hypochlorite used as the control [Table 1]. The decontaminating efficacy was then assessed by the occurrence of turbidity in the thioglycolate broth. The GP cones which were not decontaminated and directly placed in the broth developed turbidity. The cones decontaminated with Aloe vera and then placed in the broth remained clear even after 24 hours, indicating the absence of the microbial contaminants.

Table 1.

Zones of inhibition in millimeters(mm) obtained against the test organisms

DISCUSSION

The importance of GP decontamination to prevent any bacterial contamination of the root canal during the obturation procedure is now widely recognized in endodontic practice. Thus, it is imperative to employ a rapid, reliable, inexpensive and effective decontaminant. Glutaraldehyde has been effectively used as a chemosterilizer or a high level disinfectant. Aqueous solutions of 2% glutaraldehyde have a broad spectrum of action and thus effective against most of the micro-organisms, and has been used effectively for decontaminating endodontic files prior to sterilization in a glass bead sterilizer However, Boucher found that Bacillus subtilis spores are resistant to treatment with Glutaraldehyde.[9–11] 70% concentrated Ethanol is widely used in dentistry. However, studies indicate that it provides an intermediate level of disinfection, and the surface requiring decontamination requires to be submerged atleast for 10 minutes.[12] 2% Chlorhexidine kills bacteria by disruption of the cell membranes and by inducing precipitation of the cytoplasm. It has however been reported by Sequeira et al. that it is ineffective even after 10 minutes of surface exposure and requires much longer durations of contact.[13–15]

Sodium hypochlorite has a strong antibacterial and sporicidal effect, and acts by a mechanism involving the liberation of active chlorine, (a powerful oxidizing agent) which in turn inactivates the bacterial enzymes. Sodium hypochlorite 5.25% has been found to be effective in decontaminating GP cones. However, it is imperative that after disinfection, the GP cone should be rinsed in ethyl alcohol to remove crystallized sodium hypochlorite before obturation as the crystals may impair the hermetic seal. Aloe vera has been used from time immemorial for the treatment of a multitude of ailments ranging from peptic ulcers to its use in cosmetics. It has a well-established antimicrobial activity ascribed to compounds that are now specifically identified as p-coumaric acid, ascorbic acid, pyrocatechol and cinnamic acid.[15] Another major advantage is that Aloe vera gel has been found to be effective in decontaminating GP cones within one minute. To substantiate these results, further in depth studies incorporating more isolates from clinical samples are required.

CONCLUSION

Within the limits of this study, it can be concluded that Aloe vera gel can be used effectively for decontaminating GP cones within a short duration, and holds a promising future as a medium for storage of GP points.