Tanta Dental Journal

: 2019  |  Volume : 16  |  Issue : 1  |  Page : 6--11

Antibacterial efficacy of green tea mouth rinse in children with early childhood caries

Amro M Moness Ali1, Wael H Ahmed1, Rehab M Abd El-Baky2, Maha E Amer1,  
1 Department of Pediatric and Community Dentistry, Faculty of Dentistry, Minia University, El Minya, Egypt
2 Department of Oral Radiology, Faculty of Dentistry; Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, El Minya, Egypt

Correspondence Address:
Amro M Moness Ali
Department of Pediatric and Community Dentistry, Faculty of Dentistry, Minia University, Cairo Aswan Road, El Minya


Purpose Of this study was to compare the antimicrobial efficacy of green tea (0.5%) mouth rinse to that of chlorhexidine (CHX) (0.125%) against Streptococcus mutans and Lactobacilli spp. Participants and methods Forty-two children had early childhood cairns were recruited in this study, and randomly divided, using lottery method, into three groups; group A: children using green tea mouthwash; group B: children using CHX (0.12%) mouthwash; group C: children using colored flavored nonsweetened tape water. They were instructed to rinse the mouth for 1 min using 5 ml of the respective mouth rinse 30 min after the tooth brushing for 2 weeks. A volume of 2 ml saliva samples were collected prior to the commencement of mouth rinsing, and after 2 weeks rinsing, data were collected and statistically analyzed. Results Revealed both CHX and green tea mouth rinses showed a statistically significant fall in the colony counts of S. mutans and Lactobacilli spp. (P < 0.001 and <0.001), while in the third group not statistically significant (P = 0.003 and 0.183) for S. mutans and Lactobacilli spp., respectively). When the antimicrobial efficacy of CHX and green tea was evaluated against both S. mutans and Lactobacillus spp., no statistically significant difference was found (P = 0.462 and 0.824, respectively).

How to cite this article:
Moness Ali AM, Ahmed WH, Abd El-Baky RM, Amer ME. Antibacterial efficacy of green tea mouth rinse in children with early childhood caries.Tanta Dent J 2019;16:6-11

How to cite this URL:
Moness Ali AM, Ahmed WH, Abd El-Baky RM, Amer ME. Antibacterial efficacy of green tea mouth rinse in children with early childhood caries. Tanta Dent J [serial online] 2019 [cited 2023 Feb 5 ];16:6-11
Available from: http://www.tmj.eg.net/text.asp?2019/16/1/6/260280

Full Text


Early childhood caries (ECC) is one of the most infectious disease affecting children worldwide. It takes place due to imbalance between the host's oral immunity and oral microflora. This discrepancy is created by the emergence of cariogenic microorganisms in dental biofilm[1]. Moreover, poor oral hygiene and/or inadequate dental plaque control lead to the rapid progression of ECC[2].

Chlorhexidine (CHX) was developed in 1950, which is the most used antiplaque agent. However, the long-term usage of CHX is limited by altered taste perception and staining of tooth with prolonged usage, as reported by Varoni et al.[3]. Though CHX has been the gold standard mouthwash in controlling plaque formation[4], its undesirable side effects such as enhanced ability of calculus formation, bitter taste, and interference with taste[5] have inspired a search for alternatives. Green tea (Camellia sinensis), which contains adequate amounts of catechins and various other polyphenol compounds, has been shown to possess antibacterial, antioxidant, anti-inflammatory, antidiabetic, antiviral, and antimutagenic properties with a proper effect against efficacious against caries and periodontal diseases[6]. The aromatic constituents of green tea have exhibited anti-inflammatory properties at the site of inflammation. In-vivo and in-vitro studies have reported green tea to have a prominent anticariogenic effect[7],[8],[9]. This effect could be mainly attributed to the antibacterial activities of green tea catechins[10],[11] and other components such as caffeic acid, quercetin, chlorogenic acid, gallic acid, myricetin, kaempferol, etc.[6],[12].

To our knowledge, there is a paucity of reports on comparing the antimicrobial efficacy of a commercial green tea mouth rinse to that of CHX, the 'gold standard'. Thus, the main purpose of this study was to evaluate and compare the antimicrobial efficacy of green tea (0.5%) mouth rinse to that of CHX (0.125%) against Streptococcus mutans and Lactobacilli spp.

 Participants and Methods

The present double blinded randomized controlled trial in which the authors as well as the children were blinded to the type of the tested mouthwash.


Our study was performed in accordance with the Consolidated Standards of Reporting Trials statement. Sixty-one healthy children aged between 60 and 71 months old were selected from children with ECC as per the definition given by the American Academy of Pediatric Dentistry attending Pediatric Dentistry and Dental Public Health department, Faculty of Dentistry, Minia University between March 2017 till July from the same year in accidence to the inclusion criteria. Only 42 children were enrolled in the current study [Figure 1].{Figure 1}

Inclusion criteria

Children aged between 60 and 71 months old of both sexes.Physically fit apparently healthy children who suffered from ECC.Patient and parents cooperation were mandatory.Children had fair oral hygiene, normal occlusion, were brushing their teeth twice daily using toothbrush and toothpaste and practicing no other oral hygiene measures.

Exclusion criteria

Children who were unable to expectorate completely or brush their teeth on their own.Children who had positive history of taking antibiotics 3 months prior to and during the study period,Children undergoing orthodontic treatment or with an intraoral prosthesis.Children with known history of allergy to any mouth rinse or drug.Medically compromised children.Presence of any intraoral pathology.Children for whom parental consent will not be given.

Study groups

The study was conducted according to the principles of Helsinki declaration and was approved by the research ethics committee, faculty of dentistry, Minia University (reference number# 203/27.2.2017). Verbal assent from the child and an informed written consent from the parents of enrolled children were obtained. Included children had been randomly divided, using lottery method, into three groups:

Group A: children using green tea mouthwash (study group).Group B: children using CHX (0.12%) mouthwash (positive control).Group C: children using colored flavored nonsweetened tape water (negative control).

The dmft of the children were recorded on the dental chair using dental light, mouth mirror, and community periodontal index probe. The sum total of dmft were considered and based on the caries experience. All the study participants were given. a tube of nonfluoridated toothpaste (Parodontax classic; GSK, Warren, New Jersey, USA), a toothbrush and a prenumbered identical mouth rinse bottle. The brushing and mouth rinsing technique were demonstrated to all involved participants and their parents as well, they were advised to brush twice daily and to rinse the mouth for 1 min using 5 ml of the respective mouth rinse 30 min after the tooth brushing for 2 weeks. Rinsing was carried out under parental supervision.

Mouth rinses

Commercially available Camellia Sinensis Leaf 'green tea (Colgate plax fresh tea; Colgate-Palmolive Company, New York City, New York, USA)' and CHX mouth rinse (Hexitol 0.125%; Adco, Cairo, Egypt) were used in this study.

Saliva samples

A volume of 2 ml saliva samples were collected prior to the commencement of mouth rinsing, that is, at baseline and after 2 weeks rinsing, that is, postrinsing. Unstimulated whole saliva samples were collected by asking the children to drool into a sterile container for 3–5 min, sitting in an upright position in on the dental chair. All samples were collected in the morning between 10.00 and 11.00 a.m. Children were instructed not to eat or drink anything (except water) 1 h before saliva collection.

Microbial evaluation

The samples were transported to the microbiological laboratory in box with ice-packs to be cultured and tested for the presence of S. mutans and Lactobacilli spp.

All saliva samples were serially diluted using physiological saline to obtain three concentrations. A volume of 0.1 ml saliva sample was spread on trypticase soy agar (Oxoid limited, Cheshire, UK) and de Man, Rogosa and Sharpe agar (HiMedia, Mumbai, India) (for Lactobacillus spp. isolation) plates using a sterile glass spreader. The plates were incubated for 48 h at 37°C in the incubation chamber to obtain maximum growth of microbial colonies. Colonies were identified by morphology, size, color and conventional biochemical tests. Counting was done with a handheld digital colony counter. The colony count was expressed as the number of CFUs per millimeter (CFU/ml) of saliva. Semiquantification of the number of colonies will be done by multiplying the actual colony count with 1×103 to adjust for the dilution factor. The colony counting was done by the same observer under the same conditions and at the same time of the day to avoid the intraobserver variability in the results.

Statistical testing

Data were collected, revised, verified, coded, then entered PC for statistical analysis done by using SPSS statistical package, version 20 (IBM Corp., Armonk, New York, USA). For quantitative data: range, mean, and SD[13]. Comparison between three studied groups by Kruskal–Wallis test (H-test) and post-hoc test. Comparison within each group before and after by Wilcoxon's signed-rank test. For comparison of antimicrobial efficacy of different used mouth rinses, the following was calculated: absolute difference (CFU before−CFU after), Percentage reduction (absolute difference×100/CFU before). For all tests probability (P) was considered significant if less than 0.05.


Forty-two children were distributed among study groups with no significant difference in regards to age, sex, caries index 'dmfs' [Table 1].{Table 1}

Both CHX and green tea mouth rinses showed a statistically significant fall in the colony counts of S. mutans and Lactobacilli spp. (P < 0.001 and <0.001, respectively; [Table 2]), while in the third group only a numerical reduction in bacterial CFU count was found, which was not statistically significant (P = 0.003 and 0.183 for S. mutans and Lactobacilli spp., respectively; [Table 1]). When the antimicrobial efficacy of CHX and green tea was evaluated against both S. mutans and Lactobacillus spp., no statistically significant difference was found (P = 0.462 and 0.824, respectively; [Table 3] and [Table 4]).{Table 2}{Table 3}{Table 4}


Evaluating a commercially available green tea mouth rinse was carried out with the aim of excluding the diversity of factors that mostly affect the biological properties of green tea extract[14], and also to reduce time consumed for extract preparation. In addition, preparation of green tea extract needs its brewing at 90°C that affect the activity of it upon time. It was found that the longer the time the leaves infused with hot water, the lesser antibacterial activity shown by the extract due to the increase of the antibacterial polyphenolic compounds breakdown, rendering the tea less effective. Also, other methods of green tea extraction including the use of ethyl alcohol which may results in dissolving some ingredients. Green tea contains a myriad of other compounds including gallic acid, quercetin, kaempferol, myricetin, caffeic acid, and chlorogenic acid in addition to polyphenols which upon its use in high concentrations can result in undesirable side effects[15],[16].

Previous studies reported that despite of being of chlorohexidine a good antibacterial against oral pathogens, it causes extrinsic tooth staining, altered taste perception, and enhanced supragingival calculus formation but lower rate of teeth staining was observed with green tea mouth washes. It was found also that green tea polyphenols can stimulate and energize aged keratinocytes in the suprabasal layers of skin in vitro, leading to accelerated wound healing and the prevention of scar formation[17],[18]. According to the previous findings we studied and compare the activity of green tea mouthwash (alcohol free) to that of chlorohexidine.

ECC is a multifactorial disease with several well-known components collectively acting for the disease to manifest. It is recognized to require a host (tooth), a dietary substrate and acidogenic bacteria[2]. Among pathogenic flora, S. mutans and Lactobacilli spp. are considered two of the main causative microorganisms associated with dental caries[2]. In the present study, children at high risk of dental caries were taken in accordance with AAPD guidelines for caries risk assessment[19],[20].

Although saliva plays an important role in decreasing the ability of oral pathogens to grow due to its antioxidant activity, it was found that the antioxidant activity of saliva in periodontitis patients than in healthy people by 40–50%. Also, the total antioxidant capacity in plasma decreases in periodontitis[21],[22]. In addition, S. mutans and Lactopacillus spp. can accommodate the acidic environment by the production of lactic acids[23]. Another factor is that it can promote the growth of oral pathogens is the development of biofilm which acts as a protective barrier for the diffusion of antimicrobials and immunological factors[24]. The previous findings increase the risk of the development and growth of oral pathogens. So, there is a need to fight these pathogens. The main disadvantage of using antimicrobials is their destructive effect on the oral normal flora which results in the flourishment of Candida albicans and the development of fungal infections[25]. As result, we studied the effect of green tea (popular health drink) as a mouthwash due to the previous knowledge of being a good antioxidant, antibacterial, antibiofilm, anticancer and its role in cardiovascular diseases[26].

Forty-two children fulfilling the set inclusion criteria participated in the current study, they were randomly allocated to one of three groups; experimental, positive control, and negative control group using lottery method to avoid allocation bias. They were elder than 5 years old to be able to use mouthwash efficiently and safely and in the same time to fulfill the criteria of ECC. Also, children with fair or poor oral hygiene and/or carious teeth were selected to insure initial measurable level of the tested cariogenic microorganisms. Also, children with a history of administration of antibiotics 3 months prior to or during the study period were excluded to avoid any possible antibacterial effect on the assessed microbes.

The present study was simulating the real-life conditions without altering the participants' routine oral hygiene practices except that they were advised to use a nonfluoridated dentifrice for cleaning their teeth. This was done to eliminate the antimicrobial confounding result from fluoridated dentifrice. In attempt of standardizing rinsing, the second contributor demonstrated the rinsing procedure in front of children and their parent(s) also each child was instructed to rinse under parent supervision. Thus, rinsing was carried out after breakfast and this could have also contributed toward reducing the microbial challenge.

All samples were collected in the morning between 10.00 and 11.00 a.m. to prevent any bias in the concentration of saliva due to circadian rhythm[27]. Instructing children not to eat or drink anything, except water, 1 h before samples collection was in order to minimize stimulation of saliva, avoid impact of food consumption and to avoid contamination of saliva with food debris[28].

According to the results of this study, green tea was found to be a very effective antibacterial mouth rinse against S. mutans and Lactobacilli spp. The antibacterial effect of green tea mouth rinse is in accordance to the many reports which stated that usage of green tea mouth rinse had considerable anticariogenic activities including inhibitory effect on cariogenic bacteria by inhibiting the adherence of bacterial cells to the tooth surfaces[8],[9],[29],[30]. Moreover, green tea catechins maintain the salivary pH at a normal range, which is not a favorable condition for cariogenic bacteria to flourish[11],[31].

Hamilton-Miller[32] showed that green tea can reduce the amount of S. mutans in the saliva decreasing dental caries and showed that green tea has an indirect antibacterial effect by stimulating the protective components such as immunoglobulins, lysosome, lactoferrin, histatin, and mucin. Another mechanism of green tea action was stated by Narotzki et al.[33] which is its ability to inhibit lactate dehydrogenase enzyme decreasing acid production after sugar consumption. Suyama et al.[34] reported that consumption of green tea gum prevent dental caries by increasing the resistance of enamel to acid, and reinforcing its remineralization.


From the results of our study, it can be concluded that a commercially available green tea mouth rinse could be effective as CHX mouth rinse. However, further studies are required to evaluate plaque rate formation, cost effectiveness, and acceptability.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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