ISSN   0974-3618  (Print)          

            0974-360X (Online)





Essential oils in prevention of Dental Caries - An In-Vitro study


S. Subasree1*, Geetha R. V.2

1BDS Student, Saveetha Dental College and Hospitals, Chennai.

2Faculty of Microbiology, Saveetha Dental College and Hospitals, Chennai.

*Corresponding Author E-mail:



Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, medicinal and cosmetic applications, especially nowadays in pharmaceutical, sanitary, cosmetic, and agricultural and food industries. Because of the mode of extraction, mostly by distillation from aromatic plants, they contain a variety of volatile molecules such as terpenes and terpenoids, phenol-derived aromatic components and aliphatic components. So the aim of the present study was to evaluate the role of essential oils Wintergreen and Rosemary oil in prevention of dental caries worldwide. Their curative effect has been known since antiquity. It is based on a variety of pharmacological properties which are specific for each plant species. Antibacterial activity of the two essential oils, Wintergreen and Rosemary oil were screened against Streptococcus mutans, using disc diffusion technique.  The results of this study showed that the extracts at different concentrations exhibited anti bacterial activity against the bacterial species tested.


KEY WORDS: Essential oils, wintergreen oil, rosemary oil, dental caries, Streptococcus mutans.




Dental caries is an infectious microbiologic disease of the teeth that causes localised dissolution and destruction of calcified tissues. The bacteria most responsible for dental cavities are Streptococcus mutans, and lactobacilli [1]. Natural remedies obtained by using essential oils are preferred in treating caries. So the aim of this study to check the antibacterial activity of the essential oils on bacterial that initiates dental caries. Essential oils can be used as an alternative for conventional medications. They typically have widespread availability, fewer side effects, and safer to use over time.


Essential oils are aromatic oily liquids obtained from plant materials (buds, flowers, barks, seeds, leaves, twigs, wood, herbs, fruits and roots). An estimated 3000 essential oils are known to us, out of which 300 are commercially important in fragrance market [2].






Received on 11.05.2015          Modified on 30.05.2015

Accepted on 12.06.2015        © RJPT All right reserved

Research J. Pharm. and Tech. 8(7): July, 2015; Page 909-911

DOI: 10.5958/0974-360X.2015.00148.1


Chemically, they are derived from terpenes and their oxygenated compounds. Each of them contributes to the beneficial effects of these oils [3]. Essential oils have been shown to possess antibacterial, antiviral, insecticidal and antioxidant properties. Some oils have also been used in cancer treatment. They have been used as food preservatives, for aroma therapy and in the fragrance industry. They are a rich source of biologically active compounds [3,4]. The spread of drug-resistant pathogens is one of the most serious threats to successful treatment of microbial diseases. Down the ages, essential oils and other extracts of plants have evoked interest as sources of natural products. They have been screened for their potential use as alternative remedies for the treatment of many infectious diseases [5].


Wintergreen oil is extracted from a shrubby evergreen plant called Gaultheria procumbens, which is from the Ericaceae plant family [6]. It is native to North America, mainly in Northeast United States and Canada and  is characterized by its long stem, oval and glossy green leaves, and white blooms, which turn into handsome and edible bright red berries that birds and other wildlife feed on. The leaves of the plant are used to make the oil. Wintergreen oil is mostly made up of methyl salicylate (85 to 99 percent), which accounts for almost all the healing and health-promoting properties of this essential oil [7]. It also contains 3, 7 guaiadiene, a-pinene, myrcene, delta 3-carene, limonene, and delta-cadinene [8]. It is said to have analgesic, antirheumatic and antiarthritic, antispasmodic, antiseptic, aromatic, and astringent properties [9-11]. The most popular health benefit of wintergreen oil is its pain-relieving effects, which can help alleviate headache, muscle cramps, joint pain, tendonitis, and bone pain. Wintergreen oil also helps drive out stress and tension [7]. Other benefits include relief for rheumatism and arthritis [7], prevents infections caused by bacteria (such as staphylococcus aureus), Protozoa and fungi. However it is not advisable to take the oil orally to fight infections in the internal organs, nor is it recommended to be used on open wounds.


Rosemary oil is extracted from Rosmarinus officinalis (also known as Rosmarinus coronarium) of the Labiatae family [12]. It is native to the Mediterranean and Asia, but is reasonably hardy in cool climates. It can with stand droughts, surviving a severe lack of water for lengthy periods. This oil is extracted from the fresh flowering tops by steam distillation. It yields 1.0 - 2.0 % [13]. The main chemical components of rosemary oil are a-pinene, borneol, b-pinene, camphor, bornyl acetate, camphene, 1, 8-cineole and limonene [14]. Rosemary oil has therapeutic potential in treatment or prevention of bronchial asthma, spasmogenic disorders, peptic ulcer, inflammatory diseases, hepatotoxicity, atherosclerosis, ischaemic heart disease, cataract, cancer and poor sperm motility [15-17]. 



Test microorganisms:

Bacterial strain used was Streptococcus mutans.  The organism was isolated using selective media Mutans -Sanguis agar [Hi Media M977], and maintained in nutrient agar slope at 4°C   in department of Microbiology, Saveetha Dental College.



The essential oils, wintergreen and rose mary were loaded on sterile filter paper discs measuring 6mm diameter in the following concentrations 50µl, 100µl, 200µl, respectively. The discs were dried and kept aseptically.

Screening of antibacterial activity [Disc diffusion technique]:

Broth culture of the bacterial strain compared to Mac Farland’s standard [18, 19] 0.5 was prepared. Lawn culture of the test organisms were made on the Muller Hinton agar [MHA-Hi Media M1084] plates using sterile cotton swab and the plates were dried for 15 minutes. Filter paper discs loaded with different concentrations of the essential oils were placed on the respective plates. The plates were incubated at 37°C overnight and the zone of inhibition of growth was measured in millimeters. All the tests were done in triplicate to minimize the test error.



The antibacterial activity of the essential oils at different concentrations was screened by disc diffusion technique and the zone of inhibition was measured in mm diameter. The results are given in the table 1. The Wintergreen oil was more effective against  Streptococcus mutans with a zone of  inhibition of  24 mm diameter (at conc 200 µl.), rosemary oil showed a zone of 20mm diameter. Dental caries is a microbial disease that result in the destruction of mineralized  tissue of the teeth. Streptococcus mutans is the potent initiator and leading cause of dental caries worldwide. It is considered to be the most cariogenic of all of the oral Streptococci. The results obtained from our study shows that the two essential oils have got a very good antibacterial activity against Streptococcus mutans.



Herbs, which are powerful healing agents, must be used appropriately. Herbs contain active ingredients that may interact negatively with prescribed medications or other remedies. It is wise, therefore, to consult a health-care professional in situations in which you question the appropriateness of the herb or its interaction with other remedies. The use of herbs in dentistry should be based on evidence of effectiveness and safety. The anti-bacterial activities could be enhanced if active components are purified and adequate dosage determined for proper administration.  Thus, the study ascertains the value of plants and their products used in Ayurveda which could be of considerable interest in the development of new drugs




Table 1:     

Anti bacterial activity of Wintergreen and Rosemary oil on Streptococcus mutans


Conc µl


[Zone of inhibition in mm diameter]


[Zone of inhibition in mm diameter]

Chlorhexidine [Zone of inhibition in mm diameter]

Streptococcus mutans













 E 1 – Wintergreen oil,     E 2 – Rosemary oil


1        Hardie JM (May 1982). "The microbiology of dental caries". Dent Update 9 (4): 199–200, 202–4, 206–8.

2        Burt S. Essential oils: Their antibacterial properties and potential applications in foods: A review. Int J Food Microbiol 2004; 94: 223-53. 

3        Prabuseenivasan S, Jayakumar M, Ignacimuthu S. In vitro antibacterial activity of some plant essential oils. BMC Complementary and Alternative Medicine 2006;6:39.

4        Cristiane Da Silva, Gutteres SS, Weisheimer V, Schapoval EES. Antibacterial activity of lemongrass oil and citral against candida spp. The Brazilian Journal of Infectious Diseases 2008; 12 (1): 63-66. 

5        Tepe B, Daferera D, Sokmen M, Polissiou M, Sokmen A. In vitro antimicrobial and antioxidant activities of the essential oils and various extracts of Thymus eigii M Zohary et PH Davis. J Agric Food Chem 2004; 52:1132-37.

6        Essential oil profile of wintergreen by Ingrid Krein

7        Cecilia W. Lo, 2000. Developmental biology protocols, Volume 1, Springer

8        Khilendra Gurung 2007. Analysis of wintergreen oil, Ecology Agriculture and Rural Development Society, Dolakha, Nepal

9        Chevallier A. The Encyclopedia of Medicinal Plants . New York, NY: DK Publishing Inc.; 1996.

10     Duke JA, Ducellier J, Bogunschutz-Godwin MJ. Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press; 1985.

11     Johnson PN: Methyl salicylate/aspirin equivalence: Vet Hum Toxicol 1985; 26:317-318

12     Room, Adrian (1988). A Dictionary of True Etymologies.Taylor and Francis.

13     Extraction of rosemary essential oil by steam distillation and hydrodistillation: Flavour and Fragrance Journal, Volume 18, Issue 6.

14     Chemical composition and antimicrobial activity of Rosmarinus officinalis L.oils from Sardinia and Corsica: Flavour and Fragrance Journal, Volume 17, Issue1.

15     Al-Sereiti M R and Said S A, First Medical Conference of Libya, 1992, 2.

16     Englberger W, Hadding U, Etschenberg E, Graf E, Leyck S, Winkelmann J and Parnham M J, Int J Immunopharmacol, 10 (1988) 729.

17     Hoefler C, Fleurentin J, Mortier F, Pelt J M and Guillemain J, J Ethnopharmacol, 19 (1987) 133.

18     Collins,CH and Lyne, P.M 1976.Microbiological methods, London, Butterworths and co.288p

 19    Betty A.Forbes., Daniel F.Sahm., Alice S. Weissfeld. Bailey and Scott’s Diagnostic Microbiology 11th edition Mosby page 229 – 257