Neem: a magical herb in endodontics

Preparation of neem leaf extract for endodontic use

There are several techniques of making the neem leaf extract,^[9] however, the most commonly used technique is described here. Twenty-five grams of mature neem leaves need to be collected [Figure 1A] and washed with sterilized distilled water. With 50 mL of absolute ethanol [Figure 1D] added to the neem leaves and this mixture is macerated for 1-2 min [Figure 1B]. The extract is filtered through filter paper [Figure 1C]. The extraction process is repeated using the coarse residue with 25 mL of ethanol and filtered again. Both of the extracts need to be mixed and filtered through fast filter paper. The alcohol portion has to be removed from the extract in a water bath [Figure 1E] until the volume becomes 25 mL. Care is taken not to allow the temperature of water bath to rise above 45-50 °C. The whole procedure usually takes approximately 6 h for completion.^[10] The liquid is now ready to be used as an irrigant and must be stored in an air tight container.

Figure 1. (A) Neem leaves; (B) maceration of neem leaves; (C) filtration process; (D) ethanol; (E) water bath

Rationale of using neem as endodontic irrigant

Antimicrobial drug resistance is a major problem in the medical and dental fields.^[7] It is for this reason that health professionals are looking for alternatives, such as herbal products, which possess significant antibacterial properties. Of all these natural medications, neem is drawing significant attention since the plant possesses excellent antibacterial and antifungal properties.^[1]

Endodontic infections have been studied extensively to highlight their microbial nature to help in managing cases clinically. It has been observed that the obligate anaerobic bacteria dominate the entire bacterial species found in primary infections.^[11] Sundqvist^[12] confirmed that the microorganisms present in root canal system play an important role in the progression of the periradicular lesion. A major biologic aim of endodontic treatment is to eliminate intracanal tissue and pathogens, aided by antimicrobial substances and optimized root canal obturation.^[13,14] The isoprenoid group (nimbin, nimbinin, nimbidinin, nimbolide and nimbidic acid) of constituents of neem has a broad range of therapeutic and antimicrobial effects suggesting its potential as an endodontic irrigant.^[6,15,16] The use of neem as an endodontic irrigant may be advantageous because neem is an excellent antioxidant with a very high biocompatibility, and thus there is no risk of tissue toxicity with its use. Biocompatibility of neem to the human periodontal ligament fibroblasts has already been proved, and this is an important factor favoring its clinical application in endodontics.^[17] However, the limitation of using this wonder drug is its characteristic bitter taste, which is because of the nimbidin present in neem. This drawback can be overcome by incorporating sweeteners into the neem extract.^[15,16]

Literature support for using neem extract

Various studies have been conducted by numerous researchers to evaluate the antimicrobial efficiency of neem leaf extract when used in endodontics. A careful review of these research studies should be completed to draw inferences about the clinical use of the neem leaf extract in endodontics.

Bohora et al.^[6] in 2010 compared the antibacterial efficacy of the neem leaf extract and 2% sodium hypochlorite against E. faecalis and C. albicans. For this in vitro study, Brain Heart Infusion agar plates were prepared, and respective bacterial cultures were spread onto agar plates. Wells of 6 mm diameter were prepared. With 50 μL of the respective irrigant (ethanol as the control) was added to the respective wells and the plates were incubated for 24 h at 37 °C. They found that there was a significant difference between the zone of inhibition of neem leaf extract and the 2% NaOCl against E. faecalis and a mixed culture. No significant difference was observed against C. albicans.

Hegde et al.^[10] in 2013 compared the antibacterial efficacy of 2% sodium hypochlorite, propolis, neem leaf extract, turmeric and liquorice against E. faecalis and C. albicans, using the agar diffusion method. They concluded in their study that the neem leaf extract showed the highest zone of inhibition against E. faecalis and C. albicans.

Ghonmode et al.^[3] in 2013 evaluated the efficacy of neem leaf extracts, grape seed extracts, 3% sodium hypochlorite, and absolute ethanol, against E. faecalis culture by performing an agar diffusion test. They found that neem leaf extracts showed significantly greater zones of inhibition as compared to the other test materials. They concluded that the neem leaf extract has a significant antimicrobial effect against E. faecalis, commonly found bacteria in the root canal system.

Dutta et al.^[15] in 2014 evaluated the in vivo antimicrobial efficacy of 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate, and an experimental irrigant formulated from the neem tree. The preoperative and postoperative samples were evaluated for colony forming units after irrigation with test irrigants. It was concluded that neem had good anti-microbial efficacy and could be considered for endodontic use.

In an interesting study by Damre^[18] in 2015 in which the antimicrobial efficacy of herbal irrigating agents (neem leaf extract, turmeric, honey, and aloe vera) was evaluated, it was observed that honey showed the highest zone of inhibition against E. faecalis. Honey was followed by neem, sodium hypochlorite, turmeric haldi, and aloe-vera. In another study by Arora et al.^[19] in 2015 the antimicrobial potential of herbal extracts, namely neem (Azadirachta indica), tulsi (Ocimum sanctum), bitter gourd (Momordia charantia), and arka (Calotropis procera) were used as endodontic irrigants against E. faecalis and C. albicans. It was observed that bitter gourd demonstrated the maximum zones of inhibition, followed by neem, tulsi, and calotropis for both E. faecalis and C. albicans.

Chandrappa et al.^[20] in 2015 also assessed the antimicrobial activity of herbal medicines (neem extract, tulsi extract) and chlorhexidine. They observed that all of the irrigants expressed significant antibacterial efficiency against E. faecalis. Babaji et al.^[21] in 2016 in their in vitro analysis, concluded that herbal medicines such as neem, M. citrifolia, and A. vera showed inhibitory zones against E. faecalis. Therefore, these can be used as root canal irrigating solutions. Sundaram et al.^[22] and Prasad et al.^[23] in 2016 also tested the herbal irrigants including neem for their antibacterial efficacy and had suggested its potential role in the future of endodontics.

In conclusion, it is a fact that the neem leaf extract has significant antibacterial properties. There is considerable support in the literature that favors using neem as an intracanal irrigant. It should be noted that the present studies have been in vitro. Researchers worldwide should explore potential benefits of this “wonder drug”. The research should focus on neem’s use in the clinical setting. This research may determine neem’s best use as an herbal alternative to the chemicals used in endodontics.

Authors’ contributions

Manuscript preparation: H. Singh, M. Kaur, J.S. Dhillon, M. Batra

Literature search: H. Singh, M. Kaur, J.S. Dhillon, M. Batra, J. Khurana

Concept design: H. Singh, J.S. Dhillon

Manuscript review: M. Kaur

References: J. Khurana

Acknowledgments

We thank Dr. Jon Wagner for his contribution in language editing.

Financial support and sponsorship

None.

Conflicts of interest

There are no conflicts of interest.

Patient consent

Not applicable.

Ethics approval

Not applicable.