Indian Journal of Oral Health and Research

: 2021  |  Volume : 7  |  Issue : 1  |  Page : 7--13

Antibacterial properties of cinnamon: A concise review

Darren Yew Jie Lai, Lim Wei Chua, Jing Jade Chong, Pin Xuan Chong, Anand S Tegginamani, Ahmad Termizi Bin Zamzuri 
 Faculty of Dentistry, SEGI University, Kota Damansara, Selangor, Malaysia

Correspondence Address:
Mr. Darren Yew Jie Lai
Jalan Teknologi, Kota Damansara, 47810 Petaling Jaya, Selangor


Around 700–1000 kinds of microorganisms exist in the human mouth, the main inhabitants are Streptococcus mutans, Porphyromonas gingivalis, Staphylococcus, and Lactobacillus. Dental caries is a common chronic infectious disease in the world. Plaque-induced gingivitis is the inflammation confined to the gingiva only and is correlated with dental plaque. Periodontitis is the inflammation of supporting tissues of teeth, resulting in progressive destruction of the periodontal ligament. Antibacterial agents, including erythromycin, penicillin, and tetracycline are used to inhibit bacterial growth, but excessive use may cause side effects. Recently, natural products have been investigated and considered as promising agents to prevent plaque related diseases. Cinnamon has shown strong antibacterial activity against a large range of bacteria. It is high in cinnamaldehyde substance, which can reduce infections, caries, and bad breath as it has antifungal and antibacterial properties. This concise review is about the antibacterial properties of cinnamon mainly for dentistry.

How to cite this article:
Lai DY, Chua LW, Chong JJ, Chong PX, Tegginamani AS, Bin Zamzuri AT. Antibacterial properties of cinnamon: A concise review.Indian J Oral Health Res 2021;7:7-13

How to cite this URL:
Lai DY, Chua LW, Chong JJ, Chong PX, Tegginamani AS, Bin Zamzuri AT. Antibacterial properties of cinnamon: A concise review. Indian J Oral Health Res [serial online] 2021 [cited 2021 Jul 26 ];7:7-13
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Around 700-1000 kinds of microorganisms exist in the human mouth, these microbes constitute oral microbiota. Bacteria are the main inhabitants where Streptococcus mutans, Porphyromonas gingivalis, Staphylococcus, and Lactobacillus are the more common ones. These bacterial communities form the oral biofilms that reside on soft and hard tissues. Oral biofilm called dental plaque often causes dental caries, gingivitis, and periodontitis.[1],[2]

Dental caries is a common chronic infectious disease in the world. The three major hypotheses for the etiology of dental caries: the specific plaque, nonspecific plaque hypothesis, and the ecological plaque hypothesis.[3]

Plaque-induced gingivitis is the inflammation confined to the gingiva only and is correlated with dental plaque. Characteristic clinical features of this gingivitis include erythematic and sponginess; alteration in contour; bleeding on stimulation, and presence of calculus, or dental plaque without clinical attachment loss, or crestal bone loss shown radiographically.[4]

Periodontitis is the inflammation of supporting tissues of teeth resulting in progressive destruction of the periodontal ligament and alveolar bone with the formation of the periodontal pocket, gingival recession, or both. Risk factors such as smoking, poor oral hygiene, diabetes, medication, age, hereditary, and stress are associated with periodontal diseases.[5]

Treatment for such diseases requires the reduction and/or elimination of bacterial accumulations by toothbrushing and scaling. Antibacterial agents including erythromycin, penicillin, and tetracycline are used to inhibit bacterial growth, but the excessive use may cause side effects such as vomiting, diarrhea, and teeth staining. This necessitates a seek for natural antibacterial agents that are safe. Recently, natural products have been investigated and considered as promising agents to prevent plaque-related diseases.[6]

Numerous studies have reported as strong antibacterial effect of essential oils (EOs) which are a good source and very promising natural compounds for producing new antibacterial drugs among this cinnamon EO has been documented frequently as a potential antibacterial.[7]

Cinnamon has shown strong antibacterial activity against a large range of bacteria. It is high in cinnamaldehyde substance, which can reduce infections, caries, and bad breath as it has antifungal and antibacterial properties. It has been used as a flavor in sweets and chewing gum, thanks to the pleasant and refreshing effect that develops within the mouth. It also shows beneficial effects on oral health and used for toothaches, oral infections, and to get rid of bad breath.[8] Cinnamaldehyde react with nitrogen-containing compounds like nucleic acids and proteins, thereby discourage the growth of microorganisms and controlling plaque formation. Cinnamon extract influences the growth of S. mutans which is a cariogenic bacterium and it also produced the largest growth inhibition halos in S. mutans, Enterococcus faecalis., Lactococcus lactis., and S. aureus bacteria. Toothpaste containing EOs show important antimicrobial and antibiofilm activities against microorganisms associated with the caries formation (S. mutans and L. lactis.) and periodontal diseases (E. faecalis. and S. aureus). The antibacterial activity of cinnamon EO was like that of the control like chlorhexidine (CHX) gluconate, ciprofloxacin HCl, or metronidazole displayed an additive against S. aureus, cinnamon EO has been reported to inhibit bacteria through antiquorum sensing effects; inhibiting cell division, ATPase, biofilm formation membrane porin, and mobility; altering the lipid profile.[8],[9]

Toothpaste containing cinnamon EOs were able to completely disrupt S. mutans biofilms, not differing from the control.[10],[11],[12] Preventive medicine mostly relies upon reducing the bacterial biofilm by oral hygiene mostly used active ingredients in mouth wash and toothpaste are CHX, hyaluronic acid, and fluorides even though these are effective the chemical products can have some clinical disadvantages like teeth discoloration alteration in taste, dryness in the mouth, oral mucosal lesions and accumulation of supragingival calculus.[13],[14] Hence, the cinnamon EO or cinnamon extracts, due to their antibacterial, antifungal, and other properties can be beneficial in dentistry.[15]


Oral flora

The human body is home to trillions of microbes, and the rima oris is one of the largest sources of microbes. There are about 700–1000 microbial species that colonize the human mouth. The occurrence and development of oral diseases like dental caries, periodontal disease, and oral cancer are closely associated with oral microorganisms.[16]

Oral microorganisms, including bacteria, yeasts, viruses, mycoplasmas, protozoa, and archaea form a heterogeneous ecological system in the oral cavity, also known as oral microbiota. The oral cavity not only provides a warm and nutritious environment for the oral microbiota but also controls bacterial colonization to prevent invading pathogenic microorganisms. The oral microbiota plays an important role in maintaining oral health. Nevertheless, in some conditions, an imbalance of the host's commensal microbial community caused by invading microorganisms will result in dental disease.[17]

The rima oris, is a multiplex environment that circumscribes distinct, small microbial habitats. These habitats such as teeth, buccal mucosa, soft and hard palate, as well as the dorsal and ventral surface of the tongue, establishes a heterogeneous ecological system rich in different species.[1] About 700 species are present in the oral cavity, and most of them are indigenous. According to Human Oral Microbiome Database, there are around 54% of the species have been cultivated and named, 14% are cultivated but unnamed, and 32% are known only as uncultivated phylotypes. An increasing number of studies have indicated that the oral microbiota plays an essential role in the pathogenesis and development of many oral and systemic diseases.[18]

These types of bacteria do not change remarkably unlike gut microbiota. Factors such as diet and the environment have a significant impact on gut microbiota, however only influence the composition of oral bacteria minimally. Some of the more commonly known oral bacteria include S. mutans, P. gingivalis, Staphylococcus, and Lactobacillus. It's well known, one of the main components among the microorganisms is the bacteria and bacteria belonging to the genus Streptococcus can inhabit the oral cavity right after birth, thus, has an important role to play in the assembly of the oral microbiota. To allow the oral streptococci to efficiently colonize the different tissues in the mouth, they produce an arsenal of adhesive molecules. Besides that, they also have the ability to metabolize carbohydrates via fermentation thereby generating acids as byproducts. Similar compositions of oral microbiota can be found in healthy people from different countries. About 85 species of fungi can be found in a human oral cavity and among all these fungi, Candida is the most important type. Candida is neutral in nature when the oral microbiota is normal; however, when the oral microbiota balance is broken, Candida will look for the opportunity to invade oral tissue. A biofilm is formed by Candida with Streptococcus to play a pathogenic role.[1] The change in accessibility of oxygen, nutrients, and the pH-mediating effect of saliva can stimulate the growth of various organisms, and conversely, these organisms can be involved in their own small niche construction through biofilm formation and nutrient metabolism, which can produce effects both within the rima oris and systemically.[19] The oral microbiota also consists of viruses, mainly phages. During all stages of life, the type of phage in the mouth is constant. However, non-original viruses may present in the oral cavity when certain diseases exist in the human body and the most common virus is the mumps and HIV.[1]

Oral microbiome dysbiosis has been correlated with numerous local and systemic human diseases including dental caries, periodontal disease, obesity, and cardiovascular disease. Proper oral health care habits can help reduce plenty of taxa associated with pathogenic states. For instance, flossing has been related to the reduced amount of the dental pathogen S. mutans, and brushing of the teeth and tongue remarkably decreases microorganisms associated with dental diseases.[20]

Dental caries

Dental caries has various negative consequences, mostly on early adolescence life, via reducing the efficiency of masticatory function and general appearance which is reflected in growth and development because it affects emotional and social health.[21]

There are microorganisms in the oral cavity, and many of them are in biofilms, known as dental microbial plaque. S. mutans and Lactobacilli are one of the common bacteria living within dental plaque. It is believed that S. mutans (and its several sub-species) is the most common bacteria associated with the initiation of dental caries.[22]

Dental plaque is a biofilm, a community of microorganisms attached to a surface, which forms on teeth. Acidogenic bacteria, predominantly S. mutans, in the biofilm ferment carbohydrates into organic acid lowering the pH level at the enamel surface. If the pH falls to below 5.5 (critical pH), the tooth structure can demineralize.[23]

Previous studies have demonstrated the impact of dietary habits on the gut microbiome in infants and adults. In addition, although not statistically significant, some acidogenic species typically involved in the decrease of pH biofilm were highly abundant in the biofilm from patients with high carbohydrate consumption, like S. mutans, S. mitis, Lactobacillus johnsonii, Prevotella spp., Propionibacterium spp. and Actinomyces spp. Mutans and non-mutans streptococci of several types, including the S. sanguinis and S. salivarius, are immensely abundant in patients with high consumption of carbohydrates, and they have shown to have acidogenic and acid-tolerant properties. However, some data suggest an inverse relationship of the abundance of S. sanguinis and the S. mutans regarding its relation to caries development. The interaction between S. mutans and Actinomyces spp. has been also shown on which both are carbohydrate users, but are neither acidogenic nor acid tolerant. On the contrary, lactobacilli have shown to be highly acidogenic and extremely acid tolerant. In experiments with animals, there are some lactobacilli that are cariogenic and their cariogenicity depends on the consumption of carbohydrate-rich diets. Lactobacillus spp. showed higher counts in dental biofilms in situ, in the presence of glucose + fructose and sucrose, and correlations were also found between intake of confectionery-eating events and Lactobacillus levels among 12-year-old school children. Moreover, it is shown that the growth of lactobacilli is more favorable in pits and fissures or partially erupted third molars as they provide a retentive environment for the microorganisms.[24]

Plenty of studies have reported that the distinction between pathogenic biofilms and non-pathogenic biofilms in related to the proportion of cariogenic microorganisms. The accumulation of pathogenic biofilm is one of the major causes of dental caries. Therefore, agents with anti-biofilm effects have been proven to be effective in preventing dental caries.[17]

Dental caries is one of the most extensive childhood oral diseases in the world. Once it happens, its manifestation continues throughout life, even after it has been treated, maybe due to an experience with pain and anxiety associated with dental fear. Therefore, primary prevention in the early phase of childhood is needed to minimize the risk of caries initiation and to prevent its further progression.[25]


CHX is a gold standard antiplaque and antigingivitis agent, used by everyone including dental practitioners, due to its antimicrobial effects, CHX gluconate (1,1'-hexamethylene bi [5-(p-chlorophenyl) biguanide] di-D-gluconate) (CHX) is a gluconate salt; a biguanide compound, that has been commonly used around since the 1950s. The high usage of CHX is due to its broad-spectrum anti-microbial agent, causing disruption of cellular membranes. Thus, it is currently used as a disinfectant agent to clean non-living clinical surfaces and catheters. Generally, it is also biocompatible, and due to this factor, dental practitioners and the general public use it orally as antiseptic mouthwash to prevent bacterial biofilm and plaque accumulation. The latter is potentially causative for dental caries, plaque-induced gingivitis, periodontitis, and oral soft tissue disease. Nevertheless, as discussed henceforth, CHX has differing effects on bacteria, viruses and fungi, and the potential to have more clinical benefit with some oral diseases than others.[26],[27]

For the CHX mouth rinse formulations, individuals are advised to rinse with 10 ml of CHX twice daily for 30 s, but for individuals under 12 years, it is only to be used on the advice of a dental practitioner. It is also advised for short-term use only which is about 2–4 weeks. In patients with oral candida, dentures may also be soaked in CHX mouthwash once or twice daily for 15 min.[14],[28]

CHX mouthwash has a pH range of 5–7, and is only advised for topical use, never for any systemic administration. This is because CHX being cationic, binds to skin, mucosa, and tissues, which in turn make it poorly absorbed across these membranes. After a single rinse, 30% of CHX may remain in saliva for up to 5 h, and on the oral mucosa for up to 12 h, with plasma levels being undetectable. This is because even when large volumes are ingested, CHX is still poorly absorbed from the gastrointestinal tract. It is generally considered safe for oral use; however, some side effects and complications have been reported such as teeth staining, dry mouth (xerostomia), altered taste sensations (hypogeusia), specifically salt and bitter also a discoloured or coated tongue. It is used as an adjunct to oral hygiene and professional prophylaxis such as post oral surgery in periodontal surgery or root planing. Studies have shown that the daily use of mouth rinse combined with tooth brushing resulted in reduced interproximal plaque as compared to toothbrushing and daily flossing. In addition, CHX is used for patients who are prompted to oral candidiasis to inhibit the bacteremia and operatory contamination by oral bacteria. Other usages of CHX include sub-gingival irrigation, management of denture stomatitis, hypersensitivity, and halitosis. Wound healing is improved when CHX rinses are used before extractions and after scaling and root planing or periodontal surgery. CHX is used as a local drug delivery system in the form of a bio-degradable chip that is used in the subgingival environment. There is a controlled release of CHX to the periodontal pocket. Based on the results of several clinical trials, it has shown that the use of the CHX chip in conjunction with scaling and root planing is effective in decreasing periodontitis, clinical attachment loss, and bleeding on probing over a period of 6–9 months. The use of the controlled supply of CHX delivery system during maintenance therapy enables greater improvement in clinical signs of periodontitis.[29]

Dental plaque

Dental plaque is defined as a rich and diverse community of microorganisms residing on the tooth surface as a biofilm, which embeds themselves in an extracellular matrix of polymers of host and microbial origin. Organisms like S. mutans, P. gingivalis, Streptococcus gordinii, Streptococcus cristatus, Porphyromonas aeruginosa as commensals are all seen in dental plaque.

Dental plaque-host-associated biofilms are made of soft deposits and often mistaken as material alba, thus careful differentiation is necessary. Mineralization of these plaques leads to calculus formation which could be either supragingival or subgingival. Marginal plaque results in gingivitis and supragingival plaque to caries, while subgingival plaque leads to periodontitis and soft tissue destruction. According to a study by Tanner et al., it demonstrates dental plaque composition consists of varied diversity on anaerobic cultivation and isolation using enriched blood and acid agars. The formation of cariogenic biofilm is enabled by the diversity in different oral niche areas like occlusal surfaces and non-stimulated saliva along with macromorphology of tooth occlusal surfaces. This has been proven by Carvalho et al. using molecular techniques. More than 500 distinct microbial species can be seen colonizing within these plaque biofilms. This includes nonbacterial microorganisms like yeasts, protozoa, Mycoplasma spp. and viruses. Newer biofilm organisms like Streptococcus wiggsiae have also been recognized, identified, and have been implicated in the etiopathogenesis of early childhood caries. Visible occlusal plaque index has been used to assess the occurrence and distribution of occlusal biofilm in relation to caries. In recent studies, they have tried to explain the various patterns of oral biofilm induced responses of the host cells in altered surrounding microenvironment. Peyyala et al. used an in vitro system model that utilizes rigid gas permeable contact lenses to form bacterial biofilms and is able to correlate the inflammatory responses of the host cells through calibration of IL-8 liberation hence challenging the oral epithelial cells. These studies are helpful in determining the significance of the microbiome in the pathogenesis of any given oral lesion. Similarly, among the various tooth associated structures affected by the formation of biofilms, dental implants, orthodontic wires appliances and denture prosthesis are encompassed with the dental plaque and are the main reason for the formation of dental caries and certain inflammatory conditions like peri-implantitis, stomatitis, and implant failures.[30]

It is now understood that the matrix of extracellular polymers (EPS) allows habitat for cariogenic microorganisms which is pathological. A large body of evidence points out that dental caries is primarily a biofilm-induced disease, rather than an infectious disease, and the disease process starts off in the biofilm that covers the surface of the tooth. Caries biofilm is an immensely active and complicated ecosystem, rich in EPS. The formation of the biofilm starts when a salivary glycoprotein film, also known as a dental pellicle, coats a tooth surface. Gram-positive bacteria which include streptococci of the mitis and mutans species then form EPS, which enhance the adherence of other organisms. These bacteria are also are considered as initial colonizers of the biofilm. Recent studies also show that acid-producing bacterial species of the genera Veillonella, Scardovia, Lactobacillus and Propionibacterium are present within the dental biofilm as colonizers and ready to induce cariogenic conditions in the mouth itself.

The EPS give rise to new binding sites for other acid-producing microorganisms and increase their virulence. Early and previous studies concentrated more on the microbial composition of cariogenic biofilms; however, it is now being progressively recognized that in the formation of caries, the structural and biochemical properties of EPS may also have important roles to play. Protection and mechanical stability are provided by the matrix of EPS, making the biofilm recalcitrant to antimicrobials and difficult to remove. The microbes, embedded in a substrate of EPS, consistently produce acids that are physically protected and neutralized by the saliva's rapid buffering. The studies on caries concentrating on microbial behavior in biofilm communities using experimental biofilm models which may simulate the metabolic processes during carbohydrate exposure within the mouth and help assess the dose-response the sensitivity of anti-caries agents. In other words, this strategy is helpful in assessing the cariogenicity of dietary sugars and evaluating the anti-caries effects of substances in vitro.

S. mutans biofilm has been believed and accepted to possess the cariogenic potential which depends on three core attributes which is acid production, acid resistance which allows it not only to metabolize a variety of carbohydrates into organic acids but also able to thrive under low pH conditions, and the ability to synthesize EPS, which can be also seen as a growth-promoting process, providing protection for cells and hence allowing them to be able to survive under harsh environments. Three glucosyltransferases (GtfBCD) are matrix-producing enzymes of S. mutans that plays a part in the establishment of a cariogenic biofilm. However, it has become increasingly clear that simply targeting S. mutans and limiting sugar intake is not sufficient to prevent caries as the science of prevention and treatment of dental caries has evolved. The major EPS components in cariogenic biofilms are dominated by polysaccharides, mainly S. mutans-derived glucans as well as soluble glucans and fructans produced by other species such as Actinomyces, Streptococcus salivarius, and Streptococcus gordonii. Emerging molecular analyses have shown the presence of a pathogenic flora that has bacteria different from streptococci like Scardovia and Actinomyces and fungi like Candida albicans. Lactobacillus, Bifidobacterium, and Scardovia species are also considered as caries-associated colonizers besides S. mutans. Consistent to previous studies, they suggested that the susceptibility of biofilms to either antibiotics, preservatives, or anti-adhesion compounds is closely associated with its microbial diversity. Microbial abundance decreases during the maturation of cariogenic biofilms due to the strong competitiveness of cariogenic microorganisms. The dominance of cariogenic microorganisms over health-associated commensal species also attributes to the etiology of caries. Hence, challenges for the prevention of dental caries are posed by the complexity of the biofilm matrix as well as the abundance of microorganisms.[7],[31],[32],[33],[34],[35],[36]


Many researchers have put their attention on the antimicrobial properties of traditional medicinal substances such as EOs. EOs and extracts have shown how effective their antibacterial and antifungal properties are. Oral hygiene products based on herbal extracts are familiar in the field of dental medicine. One of the commonest substances used by dental professionals is eugenol, which is an active component in dental materials such as root canal sealers, cement, and others. Recently, another type of the EOs subjected to exploration in dentistry is cinnamon (Cinnamomum spp., Lauraceae family).[15],[37],[38],[39]

In general, approximately 250 species have been identified among the cinnamon genus, with trees being scattered all over the world. The key main constituents of cinnamon are cinnamaldehyde and trans-cinnamaldehyde (Cin), which are found in the EO, thus contributing to the fragrance and to the various biological activities observed with cinnamon.[40] Cinnamomum zeylanicum belongs to the Lauraceae family that is found in abundance in countries like India, Sri Lanka, Indochina, and Madagascar. It has been proven that its inner bark is very good and has been used as a potent therapeutic agent in ethnomedicine and also a flavoring ingredient in foods. The antioxidant, antimutagenic, and antimicrobial activities of C. zeylanicum extracts have also been previously evaluated and recognized. Unfortunately, there are only a few published reports explaining the mechanism behind the antibacterial activity of C. zeylanicum bark EO against the most resistant and sensitive food-borne pathogenic and spoilage bacteria to the oil.[41] Cinnamon is well-known as a culinary herb and traditionally used in medical applications. Researchers have studied the effect of cinnamon during pregnancy, diabetes control, and gynecological problems. Its anti-inflammatory, cardioprotective, antioxidative, and antimicrobial properties have also been explored and investigated. Hence, cinnamon EO, cinnamon extracts, and pure compounds, because of their antibacterial, antifungal, and other properties, are beneficial in mouth rinses, toothpaste, or as a root canal irrigate, showing their potential as an antimicrobial agent in dentistry.[37],[38],[39],[40],[41]

Periodontal disease

The periodontal disease which includes gingivitis and periodontitis is a common oral infection am that affects the periodontium. The condition usually started off as gingivitis, which is characterized by bleeding, swollen gums, and pain, and if left untreated, it further complicates periodontitis which now involves the loss of periodontal attachment and supporting bone.[42],[43]

According to reports, the prevalence of periodontal disease ranged from 20% to 50% around the globe. It is considered as one of the main causes of tooth loss which can compromise mastication, esthetics, self-confidence, and quality of life.[44] The major anaerobic gram-negative bacteria in the subgingival area are Actinobacillusactinomycetemcomitans, P. gingivalis, Prevotella intermedia, and Tannerella forsythensis. These bacteria play a major role in the onset and subsequent development of periodontitis by involving themselves in the periodontal pocket formation, connective tissue destruction, and alveolar bone resorption by an immunopathogenic mechanism. Most naturally occurring microorganisms especially dental plaque grow on the surfaces in the form of biofilm. The clinical features of the different types of periodontitis depend on the interaction between host-related factors, the environment, and the microbiological agents. An individual's susceptibility is determined by a favorable environment plus positive genetic factors. Furthermore, the varying degrees of severity of the clinical syndromes, rate of progression, relapse, and the random response to treatment will also have an important role to play. Periodontopathogenic bacterial microbiota is thus, necessary, however insufficient on its own for the disease to emerge, which means that a susceptible host must also be present. Epidemiological studies have shown a direct association between the severity of periodontal illnesses, the amount of dental plaque, and the degree of oral hygiene, together with a cause and effect relationship between the formation and accumulation of dental plaque and the formation of gingivitis. In this aspect, Löe's studies on experimental gingivitis conducted in Denmark are very notable. These studies demonstrated a pronounced association between the accumulation of bacterial plaque and gingivitis over the 21 days during which the experiment was carried out. When oral hygiene and plaque control methods were reinstated, the clinical manifestations of gingivitis disappeared. Following that, in another longitudinal study carried out using beagles, Lindhe demonstrated experimental periodontitis. The forces of bacterial aggression and host resistance are balanced under healthy conditions. The disease emerges when this equilibrium is disrupted, whether caused by an increase in the number and virulence of the germs or because of low defenses. The resulting diseases are therefore known as gingivitis, when only limited to the gum, and periodontitis, when they spread to underlying tissues. Periodontitis destroys the insertion of connective tissue to the cement and causing pocket formation, alveolar bone resorption, tooth mobility and eventually leading to tooth loss. Back in the 90s, the hypothesis has been proposed that predisposing factors in the host such as the lack of oral hygiene, age, systemic factors such as smoking, diabetes, genetic vulnerability, immunological alterations, etc., have a significant role to play in the pathogenesis of periodontal illness, in addition to microbial factors that influence the periodontal pathogenicity of the germs involved. At birth, the oral cavity is aseptic and uncontaminated, although bacterial colonization will quickly begin, forming oral microbial flora or microbiota, where aerobic, strictly anaerobic, saprophytic, and pathogenic species all coexist in the community. The natural balance (eubiosis) can lead to disease (dysbiosis) by exogenous or endogenous factors. Bacterial plaque located in the gingival margin, be it supra and subgingival, is what triggers the illness, whereby subgingival plaque is more harmful since it has greater contact with the periodontal tissues. This formation of subgingival plaque is initiated by anaerobic, Gram-negative bacteria, mobile forms, and spirochetes, located in an area with optimal conditions such as the pockets, anaerobic environments, Ph, oxidoreduction potential, less self-cleaning action, etc., Microbiota is hence polymicrobial and mixed, and therefore the resulting illnesses are frequently the consequence of complex bacterial associations.[45]

Recently, due to the outbreak of the COVID-19 pandemic, periodontal disease is being investigated for its association with severe COVID-19 illness. Oral medical history of periodontal disease could be a distinct characteristic to identify a risk group to severe COVID-19. The suggested relationship between periodontal disease and severe COVID-19 illness could be connected to closely shared risk factors among these affections. Most comorbidities and risk factors reported in patients with severe COVID-19, also aggravate the development of the periodontitis. Thus far, information on oral health history including periodontal status in patients with severe COVID-19 illness has yet been reported.[35],[46],[47]

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Conflicts of interest

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