Lemongrass essential oil gel as a local drug delivery agent for the treatment of periodontitis.

BACKGROUND: It has been long recognized that periodontal diseases are infections of the periodontium, comprising the bacterial etiology, an immune response, and tissue destruction. Treatment strategies aiming primarily at suppressing or eliminating specific periodontal pathogens include adjunct use of local and systemic antibiotics as part of nonsurgical periodontal therapy. Unwanted side effects and resistance of microorganisms toward antibiotics due to their widespread use have modified the general perception about their efficacy. Research in phytosciences has revealed various medicinal plants offering a new choice of optional antimicrobial therapy. Cymbopogon citratus, Stapf. (lemongrass) is a popular medicinal plant. At a concentration ≤2%, lemongrass essential oil inhibits the growth of several kinds of microorganisms including periodontal pathogens, especially the reference strains Actinomyces naeslundii and Porphyromonas gingivalis, which were resistant to tetracycline hydrochloride. AIMS: To evaluate the efficacy of locally delivered 2% lemongrass essential oil in gel form as an adjunct to scaling and root planing, as compared to scaling and root planing alone for the treatment of chronic periodontitis.
MATERIALS AND METHODS: 2% Lemongrass essential oil gel was prepared and placed in moderate to deep periodontal pockets after scaling and root planing.
RESULTS: Statistically significant reduction in probing depth and gingival index and gain in relative attachment level were noted in the experimental group as compared to the control group at 1 and 3 months.
CONCLUSION: Locally delivered 2% lemongrass essential oil gel offers a new choice of safe and effective adjunct to scaling and root planing in periodontal therapy.

INTRODUCTION

It has been long recognized that periodontal diseases i.e. the infections of the periodontium, comprise the bacterial etiology, an immune response, and tissue destruction.[1] The aim of periodontal treatment is primarily focused on eliminating the microorganisms and their by-products by means of mechanical instrumentation like scaling and root planing (SRP).[2] Failure of mechanical instrumentation to eliminate the penetrating bacteria completely from the sulcus and the surrounding tissue, and at the same time, the role of certain specific bacteria in the etiology or progression of periodontal disease has directed the use of antimicrobial agents in periodontal therapy.[345] Various antimicrobial drugs (e.g., tetracycline, minocycline, clindamycin, metronidazole, and chlorhexidine) have also been used as adjuncts to mechanical treatment.[6] Treatment strategies aiming primarily at suppressing or eliminating specific periodontal pathogens include adjunctive use of local and systemic antibiotics as a part of nonsurgical periodontal therapy.[7]

Over a period of time, the unwanted side effects and resistance of microorganisms to antibiotics have altered the general perception of the capabilities of these antimicrobial agents. In light of this, there is a need to look for alternate options that are effective, relatively safe, and economical.[8] Research in phytosciences, an emerging multidisciplinary science, has revealed various medicinal plants possessing antimicrobial activity with fewer side effects and reduced toxicity. Extracts of these medicinal plants offer a new choice for optional antimicrobial therapy against various oral microorganisms.[9]

Cymbopogon citratus, Stapf. (lemongrass) is a popular medicinal plant used for treating different diseases. This plant is commonly used in teas, cosmetics, and folk medicine for its antiseptic, antiemetic, anti-rheumatic, analgesic, antispasmodic, and antipyretic properties.[10]

Its chemical components like phenol and flavanoid substances were reported to show many in vitro and in vivo biological activities such as antioxidant, anti-inflammatory, and antimutagenic activities.[11] Apart from these biological activities, lemongrass essential oil has a wide range of antimicrobial effects such as anti-amebic, antifungal, antimycobacterial, and antibacterial against both gram-positive and gram-negative organisms.[10] At a concentration ≤2%, lemongrass essential oil could inhibit the growth of several kinds of microorganisms.[12] An in vitro study by Khongkhunthian et al. showed the antimicrobial activity of lemongrass essential oil against periodontal pathogens, especially the reference strains Actinomyces naeslundii and Porphyromonas gingivalis, which were resistant to tetracycline hydrochloride.[13] Lemongrass essential oil in the form of mouthwash was shown to be an effective adjunct to SRP as a part of nonsurgical therapy for the treatment of gingivitis.[1415]

For effective antimicrobial action, an agent used in periodontal therapy needs to be available at a sufficiently high concentration within the periodontal tissues and in the environment of the periodontal pocket. Also, the inability of antiseptic mouthrinses to penetrate into periodontal pockets, the short residence time of conventional topical agents at the site, and the potential side effects of administering systemic antibiotics have fuelled interest in the sustained delivery of therapeutic agents within the periodontal pocket.[16] Semi-solid formulations consisting of mucoadhesive polymers such as polycarbophil, hydroxypropyl cellulose, polyvinylpyrrolidone, and carbopol have been proposed to improve the contact intimacy and also increase the residence time of the dosage form in the periodontal pocket.[17]

In the present study, an attempt was made to compare the efficacy of locally delivered 2% lemongrass essential oil gel as an adjunct to SRP and SRP alone in the treatment of patients with chronic periodontitis with moderate to deep periodontal pockets.

MATERIALS AND METHODS

Source and subjects

A total of 60 sites were selected randomly from 15 subjects with moderate to severe chronic periodontitis in the age group of 18-55 years (mean age 43.9 ± 5.4 years) who reported to the outpatient Department of Periodontics, P. M. N. M. Dental College and Hospital at Bagalkot.

Exclusion criteria

The exclusion criteria for the patients were: (1) regular use of mouthwash/other chemical plaque control agents; (2) tobacco users in any form, alcohol use; (3) patients with systemic diseases like diabetes mellitus or with other diseases which compromise the immune system and are known to influence the periodontal disease; (4) patients having oral hard and soft tissue diseases except caries and periodontitis; (5) chronic use of antimicrobial, ant-inflammatory drugs and medication within 3 months prior to the study; (6) patients who had undergone periodontal therapy within 6 months prior to the study; and (7) pregnant females and lactating mothers.

Inclusion criteria

Systemically healthy subjects having at least four isolated periodontal pockets with a probing depth between 5 and 8 mm were included in the study.

Informed consent

All potential participants were explained about the need and design of the study. Only those subjects who agreed to participate were enrolled in the study after obtaining their written informed consent.

Study design

This was a randomized controlled clinical trial. After the initial oral examination of all the patients, the sites were selected and assigned randomly either to experimental or control group as follows:

Group I experimental: 30 sites treated with SRP and 2% lemongrass essential oil gel

Group II control: 30 sites treated with SRP alone

Clinical parameters including gingival index (GI), probing depth (PD), and relative attachment level (RAL) were recorded at baseline (before SRP) [Figure 1] and at 1 and 3 months interval. A custom-made acrylic stent and a William's periodontal probe was used to standardize the measurement of PD and RAL. RAL was calculated by measuring the distance from the stent (apical extent) to the base of the pocket.[18] A single clinician provided treatment to both groups, and all pre- and post-treatment clinical parameters were recorded by another examiner who was masked to the type of treatment received by subjects.

Figure 1

Baseline probing depth

Gel preparation

Lemongrass essential oil was obtained by distillation process, and the gel was prepared in Department of Pharmacognosy and Pharmaceutics, H. S. K. College of Pharmacy, Bagalkot. 2% Lemongrass essential oil gel was prepared by a method similar to those described for other anti-inflammatory gel formulations. Briefly, appropriate quantity of carbopol 934 was soaked in water for a period of 2 h. Carbopol was then neutralized with triethanolamine (TEA) by stirring. Then 2% lemongrass essential oil was dissolved in appropriate and pre-weighted amounts of propylene glycol and ethanol. The solvent blend was transferred to carbopol container and agitated for an additional 20 min. The dispersion was then allowed to hydrate and swell for 60 min, and finally the pH was adjusted with 98% TEA until the desired pH value was approximately reached (6.8-7). During pH adjustment, the mixture was stirred gently with a spatula until a homogeneous gel was formed.[19]

Local drug delivery

The gel was administered by means of a syringe with a bent, blunt-end needle. The needle was carefully inserted into the periodontal pocket and the gel was applied in the test sites in a gentle probing manner, attempting to fill the full extent of the pocket. The gel was applied up to the gingival margin and the excess gel was removed with a sterile gauze. No periodontal dressing was applied after delivery of the drug [Figure 2].

Figure 2

2% Lemongrass essential oil gel placement

After placement of the gel in situ, patients were instructed to follow strict oral hygiene protocol but were discouraged from using any interdental cleaning aids for 1 week. They were also asked not to chew hard or sticky foods at the gel placement sites. Patients’ oral hygiene status was reassessed at 1 week interval. All patients were recalled for follow-up measurements at 1 and 3 months intervals.

Statistical analysis

Statistical analysis of the data was performed by using Statistical Package for the Social Sciences (SPSS) software 16. Student's paired t-test was used to test the mean changes in scores at different time points within each study group.

One-way analysis of variance (ANOVA) was used to compare the mean scores between different study groups. Tukey's “honestly significant difference” procedure was used to identify the significant groups, if the test of significance in one-way ANOVA was significant. P < 0.05 was considered as the level of significance in this study.

RESULTS

The mean PD in the control group at baseline was 6.33 ± 0.95 mm, after 1 month was 5.66 ± 1.12 mm, and after 3 months was 4.93 ± 0.90 mm. Mean reduction in PD in the control group from baseline at 1 month was 0.66 ± 0.67 mm and at 3 months interval was 1.40 ± 0.75 mm, which was statistically significant [Table 1 and Graph 1].

Table 1

Comparison of changes in probing pocket depth between control group and experimental group

Graph 1

Probing pocket depths at baseline, 1 and 3 months interval

In the experimental group, the mean PD was 6.60 ± 0.81 mm at baseline and 5.17 ± 0.79 mm and 4.20 ± 0.71 mm after 1 and 3 months respectively. Mean PD reduction was 1.43 ± 0.67 mm and 2.40 ± 0.73 mm at 1 and 3 months, respectively, which was statistically significant. There was more statistically significant PD reduction in the experimental group than in the control group at 1 and 3 months [Table 1, Graph 1].

The mean RAL was 9.43 ± 0.97 mm at baseline, 8.46 ± 1.13 mm after 1 month, and 7.46 ± 1.16 mm after 3 months. Mean difference in RAL in the control group between baseline and 1 month values was 0.96 ± 0.74 mm and between baseline and 3 months values was 0.96 ± 0.74 mm, which was statistically significant. In the experimental group, the mean RAL was 9.83 ± 0.94 mm at baseline and 8.16 ± 0.94 mm and 6.63 ± 0.80 mm after 1 and 3 months, respectively. Mean RAL gain was 1.66 ± 0.81 and 3.20 ± 0.75 mm at 1 and 3 months, respectively, which was statistically significant. There was statistically significant RAL gain in the experimental group than in the control group at 3 months [Table 2, Graph 2]

Table 2

Comparison of changes in relative attachment level between control group and experimental group

Graph 2

Relative attachment level at baseline, 1 and 3 months interval

Statistically significant reduction in PD and gain in RAL were noted in the experimental group as compared to the control group at 1 and 3 months.

In the control group, the mean GI was 1.99 ± 0.76 mm at baseline, 1.78 ± 0.61 mm after 1 month, and 1.70 ± 0.40 mm after 3 months. The mean difference in GI in the control group between baseline and 1 month values was statistically nonsignificant (0.21 ± 0.64 mm), and at 3 months, it was 0.29 ± 0.44 mm, which was statistically significant. In the experimental group, the mean GI was 1.99 ± 0.61 mm at baseline and 1.77 ± 0.65 mm and 1.63 ± 0.75 mm after 1 and 3 months, respectively. Mean reduction in GI was 0.22 ± 0.61 and 0.34 ± 0.38 mm at 1 and 3 months, respectively. At 3 months, the mean GI reduction was statistically significant. There was statistically significant reduction in GI in the experimental group and control group from baseline, and after 3 months, it was not statistically significant. Although there was statistically significant reduction in GI in the experimental group than in the control group, it was not statistically significant [Table 3, Graph 3].

Table 3

Comparison of changes in gingival index between control group and experimental group

Graph 3

Gingival index at baseline, 1 and 3 months interval

DISCUSSION

Local delivery of antimicrobial agent to periodontal pockets, combined with SRP appears to provide additional benefits in PD reduction and clinical attachment level CAL gain, compared to SRP alone.[20] Although various locally delivered antimicrobial agents are commercially available, the need for safe, effective, and economical agents has motivated the use of various natural extracts. Various herbal products and their extracts such as guava, pomegranate, neem, propolis, tulsi, green tea, cranberry, grapefruit etc. in the form of mouthwashes and gels have shown significant advantages over the chemical ones in the treatment of periodontal diseases.[212223]

In the present study, we used 2% lemongrass essential oil in the form of gel as an adjunct to SRP. Statistically significant reduction in PD and gain in RAL were seen in the experimental group as compared to the control group at 1 and 3 months [Figures 1, 3, and 4]. Also, there was increased reduction of GI in the experimental group than in the control group, though it was statistically nonsignificant [Figure 5]. Overall, the improved clinical resolution of inflammation and destruction seen in the experimental group can be explained by the effectiveness of lemongrass essential oil gel as an anti-inflammatory and antimicrobial agent against periodontal pathogens, which might have prevented microbial recolonization of periodontal pockets.

Figure 3

Probing depth at 1 month interval

Figure 4

Probing depth at 3 months interval

Figure 5

Healthy gingiva at 3 months

Increased tissue healing response seen in the experimental group can also be explained by the antioxidant activity of lemongrass essential oil gel components, which prevents further periodontal tissue destruction.

Results of the present study cannot be directly compared with that of any other study because to the best of our knowledge, it is one of the first studies of its kind, evaluating the effectiveness of 2% lemongrass essential oil gel as a local drug delivery agent. But the findings in the present study are indirectly similar to those of the previous studies, where lemongrass essential oil solution in the form of mouthwash accelerated gingivitis healing process through its antioxidant activity.

Susanto et al. (2010) determined the salivary glutathione level of moderate gingivitis patients after they gargled with different concentrations like 0.5%, 1%, 2%, or 4% of lemongrass essential oil. Glutathione, also known as sulfhydryl glutathione (GSH), is one of the nonenzymatic antioxidants in the body found in every cell and plays an important role in protection against oxidative stress. Gargling with different concentrations of lemongrass essential oil increased the salivary GSH levels in moderate gingivitis patients, especially 2% and 4% lemongrass essential oil showed the same potency as hexetidine 0.1%. It was concluded that 2% lemongrass essential oil solution can accelerate the gingivitis healing process better than at other concentrations.[14]

Anand et al. (2011) studied the efficacy of lemongrass oil mouthwash and evaluated its antioxidant property by estimating salivary and gingival crevicular fluid GCF superoxide dismutase levels before and after its administration. Lemongrass oil mouthwash was used along with nonsurgical treatment in various concentrations (0.1%, 0.25%, and 0.5%). Superoxide dismutase levels increased when compared with the initial values in all the groups, with reduction in gingivitis. It was implied that the lemongrass oil mouthwash may have an additive effect on the treatment outcome, when it is used along with scaling.[15]

At a concentration less than or equal to 2%, lemongrass essential oil could inhibit the growth of several kinds of microorganisms. An in vitro study Koba et al. showed that at the concentrations of 1.3% and 1.6%, lemongrass essential oil has a bright yellow color with its contents such as citral (neral and geranial) and citronellal contributing to its antioxidant activity. In the present study, 2% lemongrass essential oil was used in the gel preparation to achieve both antimicrobial and antioxidant activities.[14]

Carbopol mucoadhesive polymer used in the present study for gel formulation helped to obtain effective 2% concentrations, and also could achieve adequate subgingival delivery of the lemongrass essential oil and sufficient contact time for its antimicrobial activity.

However, in the present study, the main outcome of therapy was measured purely based on clinical parameters like PD and GI reduction and gain in RAL. Though acrylic stent was used for standardization of RAL measurements with William's periodontal probe, it has its own limitations. While the effects of 2% lemongrass essential oil gel on subgingival microbiota and its antioxidant activity were not assessed, further studies with large sample size need to be conducted to evaluate its definitive role in periodontal therapy. Further standardization of the gel formulations should be done and their efficacy should be compared with the gold standard local drug delivery therapeutic agents like chlorhexidine.

C. citratus (lemongrass) plant is native to South India and has various medicinal properties. Isolation and characterization of phytochemical extract from this plant offers new choice of therapy as an adjunct to mechanical instrumentation in the treatment of chronic periodontitis with moderate to deep periodontal pockets.

CONCLUSION

Within the limitations of the present study, it can be concluded that 2% lemongrass essential oil gel appears to be an attractive alternating agent that can be used for effective and safe local drug delivery as an adjunct to mechanical nonsurgical periodontal therapy.

Cymbopogon citratus, Stapf. (lemongrass) is termed as bhūtīkam in The Ayurvedic Formulary of India. Bhūtīkam is mentioned in classical texts like Aṣṭṅgahṛdayam, Caraka Saṃhitā and Suśruta Saṃhitā. It has been used as an ingredient in many formulations with various combinations in conditions like fever, abdominal complaints, hemorrhoids, pain, etc. It is one of the ingredients in Pañcamūlādi yavāgu[1] which is prescribed for worms, skin diseases and diabetes. In the chapter Anuvāsanottarabasticikitsitā of Suśruta Saṃhitā. Suśruta advocates the use of vasti with bhūtīkam as one of the ingredients for diseases related to vāta in manya and śiras.[2] In jvarapratiṣedhādhyāyaḥ of Suśruta Saṃhitā, a decoction with bhūtīkam and other drugs have been mentioned for throat related disorders.[3]

The Bhāvaprakāśa and Kaiyadeva nighaṇṭu-s deal with Bhūtīkam under the titles bhūtṛṇam and bhūstṛṇam respectively. Bhūtīkam, guhyabījam, sugandham, jambukapriyam, bhūtṛṇam, chatrā, mālātṛṇa, etc are its synonyms. The plant is mentioned in Dhanvantari nighaṇṭu and is advised for diseases occurring due to kṛmi[4] (worm infestation). The karma of bhūtīkam comprises of mukha śodhanam[5]/vaktra śodhanam[6] (cleansing of mouth) along with the other actions like dīpanam (carminative), vidāhi (causing burning sensation), netryam (good for the eyes), avṛṣyam (anaphrodisiac), bahuviṭkam (causing formation of excess faeces) and doṣa karmas like pitta rakta pradūṣaṇam.

The botanical name of Bhūtīkam as per the translation of Bhāva prakāśa is Andropogan citrarum.[7]

The commentators have given the synonyms of bhūtīkam as kattṛṇam (Hemādri, Dalhaṇa), rohiṣam (Hemādri, Dalhaṇa) and yavāni.

-Editorial Board