Antimicrobial Activity of Curcuma longa L. Extract on Periodontal Pathogens.

AIM: The aim of this study was to evaluate the antimicrobial activity of Curcuma longa L. extract (CLE) on periodontal pathogens.
MATERIALS AND METHODS: Sixty patients were divided into three groups: Group I (n = 20) patients treated with scaling and root planning (SRP) only, Group II (n = 20) patients treated with SRP followed by subgingival irrigation with 1% CLE solution, and Group III (n = 20) patients treated with SRP followed by subgingival irrigation with 0.2% chlorhexidine (CHX) solution. The clinical parameters (plaque index [PI], gingival index [GI] scores, probing pocket depths) were recorded at baseline, 4 weeks, and 8 weeks. The antimicrobial efficacy of 1% CLE and 0.2% CHX solutions against Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans were evaluated by disk diffusion method.
RESULTS: There was no significant difference in the mean values of zone of inhibition exhibited by both CLE and CHX solutions. All the groups showed significant improvement in the clinical parameters when compared to baseline values. The improvement in the PI and GI scores in the CLE group was lesser than that in CHX group by the end of the study period.
CONCLUSION: CLE possess antimicrobial efficacy against the common periodontopathic bacteria. However, further large-scale studies evaluating the substantivity of C. longa are required to support its beneficial use in the treatment of periodontal diseases.

INTRODUCTION

Globally, periodontal diseases (chiefly gingivitis and periodontitis) are considered as one of the most common diseases affecting the oral cavity.[12] The main etiological agent of the periodontal diseases is the persistent dental plaque.[3] Periodontitis is a chronic inflammatory disease of the supporting tissues of the teeth.[4] The untreated periodontitis eventually results in loss of teeth, thus negatively impacting mastication, nutrition, and quality of life in adults. Furthermore, periodontitis is closely associated with other medical conditions such as diabetes, heart disease, cancer, and chronic respiratory disease.[456]

Of the several hundreds of microbial species that are present in the subgingival plaque, the bacteria that are most commonly isolated from the periodontal pockets in patients with chronic periodontitis are Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans.[7]

Scaling and root planning (SRP) is the standard treatment of care for periodontal diseases.[8] Current reviews have summarized the beneficial effects of herbal medicines for periodontitis.[9] One such kind is turmeric (also known as Curcuma longa) that belongs to the Zingiberaceae family. The role of curcumin in overpowering the actions of toll-like receptors (TLRs) has led to its identification and expansion as a potential therapeutic agent in controlling or stopping periodontitis.[7]

The objective of this study was to investigate the efficacy of subgingival 1% Curcuma longa L. extract (CLE) as an adjunct to mechanical oral hygiene procedures and compare it with 0.2% chlorhexidine (CHX) solution, the gold standard among antiplaque agents.

MATERIALS AND METHODS

Patients

Sixty patients, aged between 25 and 45 years, who consented for the study, were selected from the Department of Periodontics, Kalinga Institute of Dental Sciences, Bhubaneswar, India. The included patients were healthy and free from any systemic disease. All the patients were diagnosed with chronic periodontitis and had probing pocket depth (PPD) of ≥5mm in different quadrants of the mouth. Patients who received periodontal treatment in the last 3 months, who had known history of systemic diseases and allergies, pregnancy, and used tobacco or tobacco related products, were excluded from the study.

The clinical parameters were recorded and subgingival plaque samples were collected from all the groups at baseline. Following this, Group I (n = 20) patients were treated with SRP only; Group II (n = 20) patients were treated with SRP followed by subgingival irrigation with 1% CLE solution; and Group III (n = 20) patients were treated with SRP followed by subgingival irrigation with 0.2% CHX solution. Patients were trained to maintain good plaque control. The subgingival irrigation was repeated at subsequent visits at 7 and 14 days. The clinical parameters were assessed again at 4 and 8 weeks.

Subgingival irrigants

The CLE solution (1%) was prepared by dissolving 1000 µg CLE in 5 mL ethanol and 95 mL glycerol. Commercially available 0.2% CHX was used.

Clinical evaluation

The following clinical parameters were recorded at baseline, 4 weeks, and 8 weeks: plaque index (PI), gingival index (GI), and PPD (measured using a UNC-15 probe and standardized using acrylic stent with a groove so as to ascertain the point of entry of probe each time).

Microbiologic processing of samples

Each sterile paper point was inoculated into 5 mL of brain heart infusion (BHI) broth and maintained anaerobically for 48 hours at 37°C and 5% CO2. Bacteria from BHI broth were then subcultured on tryptone soya agar (TSA) plates and kept at 37°C under anaerobic conditions in the presence of 5% CO2 for 72 hours. The pathogenic bacteria causing periodontitis were isolated and characterized as reported by Fani and Kohanteb.[10]

Standard agar disk diffusion method was used to determine the inhibitory activity of both CLE and CHX. The test organisms were A. actinomycetemcomitans (ATCC 43727), P. gingivalis (ATCC 33287), and Prevotella intermedia (ATCC 25611). The respective bacterial strains were recovered by plating on blood agar medium. The isolated colonies were transferred to a sterile BHI broth and incubated again. The growth concentration was adjusted to 0.5 McFarland’s turbidity standard. After removing the excess inoculums, the agar plate was swabbed three times with intermittent rotation of the plates.

Three wells of 5 mm diameters each were made on each plate using a hollow tube of 5 mm diameter. Different concentrations of 1% CLE, 0.2% CHX mouthwash, and distilled water (negative control) were added in the wells allocating each plate for each of the solution. The inoculated plates were maintained under anaerobic conditions at 37°C for 48 hours. A digital vernier caliper was used to measure the diameter of zones of inhibition in all the wells in the plates. The mean values of zones of inhibition were calculated for each solution.

Statistical analysis

The data obtained were analyzed statistically using SPSS software. To compare the groups, analysis of variance was used followed by post hoc Tukey’s test.

RESULTS

Plaque index

The mean scores of PI reduced significantly in all the groups when compared with the baseline values [Table 1]. Intergroup analysis [Tables 2 and 3] showed significant difference between the Groups I and II (P = 0.48, P = 0.44 at 4 and 8 weeks, respectively) and between the Groups I and III (P = 0.47, P = 0.001 at 4 and 8 weeks, respectively). At 4 weeks, no significant difference was noticed between Groups II and III. However, the mean (± SD) values for the PI scores in Group II (0.836 ± 0.146) were more than those in Group III (0.602 ± 0.126) at 8 weeks, with a significant difference (P = 0.49).

Table 1

Comparison of plaque index scores at baseline, 4 weeks, and 8 weeks

Groups	PI scores (mean ± SD)			P value
	Baseline	4 weeks	8 weeks	Baseline to 4 weeks	Baseline to 8 weeks	4 weeks to 8 weeks
Group I (SRP)	1.691 ± 0.154	0.824 ± 0.110	0.840 ± 0.171	0.40*	0.49*	0.52 ns
Group II (SRP + CLE)	1.637 ± 0.177	0.732 ± 0.012	0.836 ± 0.146	0.30*	0.38*	0.41*
Group III (SRP + CHX)	1.659 ± 0.177	0.690 ± 0.812	0.602 ± 0.126	0.35*	0.25*	0.001**

CHX = chlorhexidine, CLE = Curcuma longa extract, ns = not significant, PI = plaque index, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant; **P ≤ 0.001, highly significant.

Table 2

Comparison of clinical parameters between the Groups I and II

Clinical Parameters	Duration	Groups (mean ± SD)		P-value
		Group I (SRP)	Group II (SRP+ CLE)
PI	Baseline	1.691 ± 0.154	1.637 ± 0.177	0.65 ns
	4 weeks	0.824 ± 0.110	0.732 ± 0.012	0.48*
	8 weeks	0.840 ± 0.171	0.836 ± 0.146	0.44*
GI	Baseline	1.580 ± 0.244	1.600 ± 0.167	0.54 ns
	4 weeks	0.975 ± 0.432	0.814 ± 0.437	0.42*
	8 weeks	1.020 ± 0.111	0.906 ± 0.133	0.38*
PPDs	Baseline	1.631 ± 0.713	1.610 ± 0.826	0.71 ns
	4 weeks	0.998 ± 0.002	0.814 ± 0.487	0.42*
	8 weeks	1.009 ± 0.111	0.754 ± 0.109	0.001**

CLE = Curcuma Longa Extract, GI = gingival index, ns = not significant, PI = plaque index, PPD = probing pocket depth, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant; **P ≤ 0.001, highly significant.

Table 3

Comparison of clinical parameters between the Groups I and III

Clinical Parameters	Duration	Groups (mean ± SD)		P-value
		Group I (SRP)	Group III (SRP + CHX)
PI	Baseline	1.691 ± 0.154	1.659 ± 0.177	0.78 ns
	4 weeks	0.824 ± 0.110	0.690 ± 0.812	0.47*
	8 weeks	0.840 ± 0.171	0.602 ± 0.126	0.001**
GI	Baseline	1.580 ± 0.244	1.690 ± 0.129	0.82 ns
	4 weeks	0.975 ± 0.432	0.690 ± 0.900	0.001**
	8 weeks	1.020 ± 0.111	0.532 ± 0.257	0.000**
PPDs	Baseline	1.631 ± 0.713	1.702 ± 0.001	0.87 ns
	4 weeks	0.998 ± 0.002	0.713 ± 0.810	0.27*
	8 weeks	1.009 ± 0.111	0.601 ± 0.009	0.000**

CHX = chlorhexidine, GI = gingival index, ns = not significant, PI = plaque index, PPD = probing pocket depth, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant; **P ≤ 0.001, highly significant.

Gingival index

In this study, the GI decreased significantly in all the groups [Table 4]. By the fourth week, the test groups (CLE and CHX) demonstrated significantly better reduction in the GI scores compared with the control group. At 8 weeks, the reductions in the GI scores were significantly different between the test groups. The mean (± SD) values for GI scores [Table 5] increased from 4 weeks (0.814 ± 0.437) to 8 weeks (0.906 ± 0.133) in the CLE group. There was a significant difference (P = 0.27) between the test groups in the improvement of GI scores by 8 weeks.

Table 4

Comparison of gingival index scores at baseline, 4 weeks, and 8 weeks

Groups	GI scores (mean ± SD)			P-value
	Baseline	4 weeks	8 weeks	Baseline to 4 weeks	Baseline to 8 weeks	4 weeks to 8 weeks
Group I (SRP)	1.580 ± 0.244	0.975 ± 0.432	1.020 ± 0.111	0.49*	0.45*	0.54 ns
Group II (SRP + CLE)	1.600 ± 0.167	0.814 ± 0.437	0.906 ± 0.133	0.40*	0.39*	0.46*
Group III (SRP + CHX)	1.690 ± 0.129	0.690 ± 0.900	0.532 ± 0.257	0.41*	0.37*	0.000**

CHX = chlorhexidine, CLE = Curcuma longa extract, GI = gingival index, ns = not significant, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant; **P ≤ 0.001, highly significant.

Table 5

Comparison of clinical parameters between the Groups II and III

Clinical Parameters	Duration	Groups (mean ± SD)		P-value
		Group II (SRP + CLE)	Group III (SRP+ CHX)
PI	Baseline	1.637 ± 0.177	1.659 ± 0.177	0.62 ns
	4 weeks	0.732 ± 0.012	0.690 ± 0.812	0.56 ns
	8 weeks	0.836 ± 0.146	0.602 ± 0.126	0.49*
GI	Baseline	1.600 ± 0.167	1.690 ± 0.129	0.60 ns
	4 weeks	0.814 ± 0.437	0.690 ± 0.900	0.51 ns
	8 weeks	0.906 ± 0.133	0.532 ± 0.257	0.27*
PPDs	Baseline	1.610 ± 0.826	1.702 ± 0.001	0.87 ns
	4 weeks	0.814 ± 0.487	0.713 ± 0.810	0.50 ns
	8 weeks	0.754 ± 0.109	0.601 ± 0.009	0.51 ns

CHX = chlorhexidine, CLE = Curcuma longa extract, GI = gingival index, ns = not significant, PI = plaque index, PPD = probing pocket depth, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant.

Periodontal probing depths

The values for PPDs reduced significantly in all the three groups [Table 6]. The reductions were least in the groups that were treated with SRP alone. The highest reductions were obtained in the CHX group compared to CLE group. However, the difference was not significant.

Table 6

Comparison of probing pocket depth scores at baseline, 4 weeks, and 8 weeks

Groups	GI scores (mean ± SD)			P-value
	Baseline	4 weeks	8 weeks	Baseline to 4 weeks	Baseline to 8 weeks	4 weeks to 8 weeks
Group I (SRP)	1.631 ± 0.713	0.998 ± 0.002	1.009 ± 0.111	0.47*	0.43*	0.51 ns
Group II (SRP + CLE)	1.610 ± 0.826	0.814 ± 0.487	0.754 ± 0.109	0.41*	0.39*	0.47*
Group III (SRP + CHX)	1.702 ± 0.001	0.713 ± 0.810	0.601 ± 0.009	0.40*	0.34*	0.26*

CHX = chlorhexidine, CLE = Curcuma longa extract, ns = not significant, PPD = probing pocket depth, SD = standard deviation, SRP = scaling and root planning

*P ≤ 0.5, significant.

Antibacterial sensitivity

The mean values of zone of inhibitions against A. actinomycetemcomitans, P. gingivalis, and Prevotella intermedia produced by CLE were 26.94 ± 1.52, 23.81 ± 1.35, and 21.83 ± 1.66 mm, respectively and those of CHX were 24.67 ± 1.23, 24.92 ± 1.22, and 23.71 ± 1.41 mm, respectively. There was no statistically significant difference between the test groups in the inhibition of growth of the common periodontopathic bacteria [Table 7].

Table 7

Mean values of zone of inhibition of periodontopathic bacteria

Groups	Periodontopathic bacteria (mean ± SD)
	Aggregatibacter actinomycetemcomitans	Porphyromonas gingivalis	Prevotella intermedia
1% CLE solution	26.94 ± 1.52	23.81 ± 1.35	21.83 ± 1.66
0.2% CHX solution	24.67 ± 1.23	24.92 ± 1.22	23.71 ± 1.41
P-value	0.55 ns	0.62 ns	0.61 ns

CHX = chlorhexidine, CLE = Curcuma longa extract, ns = not significant, SD = standard deviation

*P ≤ 0.5, significant.

DISCUSSION

Periodontal diseases are silent diseases with a high global disease burden and related morbidity and socioeconomic effects.[11] Mechanical removal of plaque is the backbone of periodontal therapy. As the etiology of periodontitis is manifold, the response to periodontal treatment is not universal. So, the dentists have to be aware of various available treatment approaches.[12]

This study compared two local drug delivery systems, CLE and CHX subgingival irrigants. Curcumin has been recognized throughout the world for its numerous health benefits.[13] Clinical use of curcumin as a possible adjunct in treating periodontitis has been studied by Gottumukkala et al.[14], Bhatia et al.[15], Nagasri et al.[16], and several others. Although, curcumin is a known for its antibacterial properties, studies on the antibacterial efficacy of CLE against periodontal pathogens are limited in the literature.

Several studies have demonstrated the antibacterial properties of CHX. Chlorhexidine can destroy aerobic and anaerobic bacteria as well as fungi and viruses.[17] On intragroup analysis, a significant reduction was found in the PI, GI, and PPD scores between all the groups but with more pronounced improvement in the test groups at 4 and 8 weeks, when compared to baseline. The improvements in the clinical parameters in the SRP group can be attributed to mechanical removal of subgingival plaque that contains disease-causing bacteria.[16] This was in accordance with Ivić-Kardum et al.[18] and Choi et al.[19]

The inhibitory action of curcumin at different stages of the arachidonic acid inflammatory pathway explains its anti-inflammatory effects. Curcumin inhibits various inflammation-related enzymes and cytokines.[2021] Bhatia et al.[15] and Nagasri et al.[16] found similar results with improvement in the clinical parameters and a beneficial effect in patients with chronic periodontitis when curcumin was used as an adjunct to SRP.

Izui et al.[22] used the standard strains of P. gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Treponema denticola and demonstrated their inhibition by curcumin at various concentrations. They could, however, not show the suppression of growth of A. actinomycetemcomitans. Similarly, Mandroli and Bhat[23] used the standard strains of most predominant organisms of deep carious lesions namely Streptococcus mutans, Lactobacillus casei, A. actinomycetemcomitans, and most widespread strains of root canal bacteria, namely P. gingivalis, Prevotella intermedia, and Enterococcus faecalis. Their findings indicated the antibacterial activity of curcumin against all the investigated organisms except E. faecalis.

CONCLUSION

In this study we demonstrated CLEs as a potential subgingival irrigant. CLEs can be used as a better and safe alternative to CHX.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.