Abstract :
Amongst the bacterial species which most often cause endodontic failure, Enterococcus faecalis is the most important. This study compared the effectiveness of cinnamon bark extract and 2% sodium hypochlorite against Enterococcus faecalis by using the agar-diffusion test. Plates of Mueller-Hinton agar were inoculated with Enterococcus faecalis. Each plate had wells saturated with the medicaments. The samples were incubated at 37
0 C for 24 hrs in an incubator. The diameter of bacterial inhibition zones around each well was recorded. Statistical analysis was performed using analysis of variance (ANOVA). Cinnamon bark extract showed better antibacterial efficacy (
p < 0.05) against Enterococcus faecalis. Further studies are needed to confirm the value of cinnamon bark extract as root canal irrigant.
Keeping this in view the present study was undertaken.
Keywords :
Cinnamon, Endodontic irrigant,
Enterococcus faecalis
Introduction :
In the centre of the tooth is a hollow chamber called root canal. In a healthy state entire root canal is filled with blood vessels and nerves. This is called the pulp of the tooth. The vitality of pulp can be compromised by decay or trauma, requiring the removal of all tissues and debris in the root canal and filling of the canal with an inert material. This is called an endodontic treatment.
Several factors may interfere with the success of the endodontic treatment in the daily clinic. It has been demonstrated that eradication of infection enhances the success rate of the endodontic treatment.
1 Enterococcus faecalis is the most commonly isolated species from the canals of teeth presenting post-treatment diseases.
2 Enterococcus faecalis account for up to 77% of therapeutic failures.
3
Among the procedure involved in endodontic treatment, irrigation is an important step in eliminating microorganisms from the root canal system.
4 Sodium hypochlorite has been the most widely used root canal irrigating solution.
5 The main advantages of sodium hypochlorite are its ability to dissolve necrotic tissues and its antibacterial properties against most microorganisms. However it has several undesirable characteristics such as tissue toxicity, risk of emphysema when overfilling, allergic potential, and disagreeable smell and taste.
6
The constant increase in antibiotic resistant strains and side effects caused by synthetic drugs has prompted researchers to look for herbal alternatives. Recently, Prabhakar et al.
7 evaluated triphala and green tea polyphenols as a possible alternative to sodium hypochlorite. The literature has shown that bark of cinnamon (Botanical name- cinnamomum zylancium, Indian Name- dalchini) has antimicrobial and therapeutic effects,
8 suggesting its potential to be used as root canal irrigant, but there is lack of any documentation or data regarding cinnamon research in endodontics.
The purpose of this in vitro study was to evaluate antimicrobial efficacy of cinnamon bark extract and 2% sodium hypochlorite against Enterococcus faecalis, using agar diffusion method.
Materials and Methods :
Cinnamon bark extract, 2% sodium hypochlorite, diethyl ether,
Enterococcus faecalis culture were the materials used in this study.
Preparation of cinnamon bark extract: Cinnamon bark was obtained from retail spice seller and taxonomic identification was performed. 20 g of sample was kept in closed containers after being chopped into small pieces. For the preparation of extract, the method reported by Rahman et. al.
9 was used. For this purpose, 50 ml of diethyl ether was added into 20 g of chopped cinnamon bark and the mixture was left for 6 hours. The mixture was periodically agitated during this period (15 min). Afterwards, it was filtered and the ether was vaporized in an evaporator (60
0 C). The extract obtained at the end of this process was used in a non diluted form for analysis. Antimicrobial activity test was started on the same day. The extract was kept in the refrigerator (4
0 C) until the analysis was accomplished.
Agar-diffusion test: The bacterial stock culture
Enterococcus Faecalis (ATCC 29212) was obtained from National Chemical Laboratory, Pune, India. Cultures were grown overnight in brain heart infusion (BHI) broth, adjusted to a 0.5 turbidity reading on McFarland scale (1.5 X 108 bacteria/ml) and inoculated in Mueller-Hinton agar plates. Inoculation was performed by using sterile swab brushed across the media. Three round wells, 4 mm deep and 8 mm diameter were punched using sterile cork-borer. Control, sodium hypochlorite and cinnamon bark extract each of 50 µl was added to I, II, III wells respectively. Control used in the study was the solvent used for extraction of cinnamon bark – diethyl ether. A total of six such inoculation agar plates with medicament were prepared. Agar plates were incubated at 37
0 C for 24 hrs. in an incubator. The diameter of bacterial inhibition zones around each well was recorded to the nearest size in mm (Fig. 1).
Results :
The results were tabulated and statistically analyzed using analysis of variance (ANOVA) (Table 1). Cinnamon bark extract showed significant inhibition of bacterial growth compared with sodium hypochlorite (
p < 0.05). No zone of inhibition was shown by diethyl ether.
Table 1. Mean Zones of Inhibition.
Test Solution |
Mean Zones of Inhibition (mm) |
Control |
0 |
2% Sodium hypochlorite |
21 |
Cinnamon bark Extract |
31 |
Statistical Analysis |
p<0.05
Significant |
Discussion :
Healing potential in plants is an ancient idea, but in recent times it has gained renewed interest and importance. The major advantages of using herbal alternatives are easy availability, cost-effectiveness, increased shelf life, low toxicity, and lack of microbial resistance reported so far.
10 Spices are one of the most commonly used natural antimicrobial agents in foods and have been used traditionally for thousands of years by many cultures for preserving foods and as food additives to enhance aroma and flavor.
11 Major antimicrobial components in cinnamon have been reported to be cinnamaldehyde, which have been given special attention to find their antibacterial activity against food borne pathogens.
12
Our study showed that, cinnamon bark extract had good inhibitory efficacy against
Enterococcus faecalis. This result is comparable with other studies. Rahman et al.
9 while evaluating antimicrobial and biological analysis of some spices extract against food spoilage pathogens, reported cinnamon extract to have inhibitory effect against
A. aureus, E. faecalis, M. Smegmatis, C. albicans and K. pneumoniae. Agaoglu et al.
13 evaluated antimicrobial activity of spices used in the meat industry, cinnamon was detected to exhibit inhibitory effect against
P. aeruginosa and
Enterococcus faecalis and its weakest activity was against E. coli and M. luteus. Hoque et al
8 reported that the ethanol extract of cinnamon were more effective against Gram positive bacteria than Gram negative bacteria in vitro.
When assessing the effectiveness of any root canal irrigant,
Enterococcus faecalis is often chosen as a model since this species is mainly responsible for endodontic failures.
14 The available scientific evidence suggests that irrigation solutions must be effective against
Enterococcus faecalis to become successful in clinical endodontic practice.
The microbial inhibition potential of cinnamon bark extract observed in this study opens perspectives for its use as a root canal irrigant. The use of cinnamon bark extract in endodontic treatment might be of interest to patients and dental professionals as part of growing trend to seek natural remedies as part of dental treatment.
15 Research in this area has barely begun, but it will not be surprising if research into many of compounds contained in seeds, roots, flowers, bark and fruits will identify further compounds with the potential to be used in dentistry.
All in vitro experiment methods have advantages and disadvantages. In the agar diffusion test, the size of the microbial inhibition zone depends upon the solubility and diffusibility of test substance and, therefore, may not express direct effective potential. It is very important to treat extrapolations of in vitro to in vivo studies with care. Other properties beyond antimicrobial activity must also be investigated before the final choice of an irrigant solution for clinical use, such as minimum inhibitory concentration, tissue dissolution capacity, detoxification of endotoxin and acceptable biologic compatibility.
Conclusion :
Within the limitations of this study, cinnamon bark extract showed statistically significant activity against
Enterococcus faecalis. Further research is needed to conclusively recommend herbal solutions as a root canal irrigant.
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* Professor and Head, Dept. of Conservative Dentistry and Endodontics,** Scientific In-charge
