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An Official Publication of the Indian Association of Oral and Maxillofacial Pathologists

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Year : 2021  |  Volume : 25  |  Issue : 2  |  Page : 223-225

Understanding the mechanism of commonly occurring COVID-19-associated oral lesions

1 Department of Oral Pathology and Microbiology, ESIC Dental College and Hospital, New Delhi, India
2 Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, SGT University, Gurugram, Haryana, India

Date of Submission24-May-2021
Date of Acceptance29-Jul-2021
Date of Web Publication31-Aug-2021

Correspondence Address:
Susmita Saxena
Department of Oral Pathology and Microbiology, ESIC Dental College and Hospital, Rohini, New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-029X.325118

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Covid-19 pandemic is a novel disease with gradual emergence of its signs and symptoms. Oral healthcare providers had a setback in their dental practices due to the high rate of infectivity and the risk of contracting the disease through the patients carrying the virus. Once the dental practice resumed to its normalcy the dental surgeons came across a variety of oral manifestations in patients with a history of Covid and post recovery. An attempt is made to recognise the Covid-19 oral manifestations with plausible explanation of the mechanism of development of such oral signs.

Keywords: Covid-19, mechanism, oral manifestations

How to cite this article:
Saxena S, Kumar S. Understanding the mechanism of commonly occurring COVID-19-associated oral lesions. J Oral Maxillofac Pathol 2021;25:223-5

How to cite this URL:
Saxena S, Kumar S. Understanding the mechanism of commonly occurring COVID-19-associated oral lesions. J Oral Maxillofac Pathol [serial online] 2021 [cited 2023 Mar 29];25:223-5. Available from: https://www.jomfp.in/text.asp?2021/25/2/223/325118

   Introduction Top

The global spread of coronavirus disease 2019 (COVID-19) pandemic which started from Wuhan city of China is a novel viral disease with gradual emergence of signs and symptoms as reported worldwide. COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2) and the mortality associated with this disease is approximately 3.7% which is higher in comparison with influenza which is only 1%.[1] The common signs and symptoms of this disease include fever, dry cough, difficulty in breathing, sore throat, myalgia, headache and fatigue. Loss of smell and taste has been reported as one of the earliest manifestations of this infection.[2] Recently, several oral lesions associated with COVID-19 have also been reported. Dental professionals have to render their services keeping in mind the COVID status of the patient. However, patients may not disclose their status voluntarily either out of ignorance or fear. An awareness regarding the possible oral manifestations of this highly infective disease can prepare oral healthcare professionals to take extra precautions while treating such patients.

   Possible Oral Manifestations Associated With of Coronavirus Disease 2019 Infection Top

Erythematous lesions, ulcers and blisters

The direct involvement of the SARS Cov-2 virus in the etiopathogenesis of oral mucosal lesions is not established. However, the incidental finding of oral ulcers in COVID-19 infected patients is widely reported. These oral ulcers or erosions in COVID patients have been described by Sakaida et al. as possible drug reactions developing during the latency period.[3] Drug hypersensitivity and urticaria have also been reported by some patients.[3] In addition, drug eruptions may occur as a result of COVID-19-induced cytokine storm with dysregulation of T-helper 17 cells which are a subset of pro-inflammatory T helper cells defined by their production of interleukin17. It has also been suggested that the anxiety and stress related to the disease may also give rise to aphthous ulcer-like lesions in the oral cavity.[4] Thus, the finding of unexplained oral mucosal lesions can warrant the collection of an oral viral sample for reverse transcription-polymerase chain reaction (RT-PCR) to diagnose asymptomatic SARS Cov-2 patients [Figure 1].
Figure 1: Patient suffering from coronavirus disease 2019 with ulceration in the lateral border of tongue and coated dorsum of tongue

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Exacerbation of autoimmune disorders

The role of the SARS Cov-2 virus in autoimmune pathologies has been reported by several researchers including exacerbation of autoimmune disorders.[4],[5]
p> The development or relapse of autoimmune oral disorders should be monitored by dental practitioners throughout the progress of the disease. Disorders such as lichen planus, erythema multiforme and lupus erythematosus have been seen to exacerbate in some patients affected by COVID-19 infection.[5] Such occurrence could be related to the anxiety associated with the disease or the influence of the virus on the immune system or may be due to the drugs administered to such patients.

Loss of taste and smell

Onset of loss of taste (ageusia) and loss of smell (anosmia) have been reported quite early in the course of COVID-19, more so in mild-to-moderate severity of the disease (95%–98% of patients).[6] A sudden loss of taste or smell in the absence of any other inflammatory upper respiratory tract infection should alert the attending dental practitioner of potential COVID-19 disease in the patient which can facilitate early isolation of the patient. The mechanisms involved may include viral disruption of the cranial nerves 1, VII, IX and X and inflammatory exudate affecting the supporting cells of neural transmission.[7] Angiotensin-converting enzyme 2 (ACE-2), an important receptor for COVID-19, is abundant on cells found in the nose and mouth. Thus, there is a possibility that the virus could directly invade the nerve cells associated with the senses of smell and taste.

Limited data are available on the mechanisms involved in the pathogenesis of taste disorders in COVID-19.[8] Single-cell RNA-sequencing studies have demonstrated that epithelial cells of the tongue express abundant ACE-2 receptors. It could be hypothesized that, similar to what was suggested for olfactory disorders, the pathogenesis of taste disorders in COVID-19 may involve indirect damage of taste receptors through infection of epithelial cells and subsequent local inflammation. Better knowledge of the pathogenesis will help in the therapeutic management of prolonged smell and taste impairment as a postSARS Cov2 complication.

Salivary gland disease

Salivary glands can be involved in patients with CoV infection.[9] It is reported that ACE-2 expression in minor salivary glands is higher than that of lungs making the salivary glands a potential target for the COVID-19 virus.[10],[11]


Viral invasion of salivary glands can cause dry mouth in COVID patients. The psychological status of the patients along with poor oral hygiene and adverse drug effects may be the other contributory factors in xerostomia.[12]

Oral candidiasis

The most common complaints of patients having COVID-associated candidiasis is burning sensation and dysphagia. White membranous patches are seen spread over the dorsum of the tongue or lateral border of the tongue or palate or even the buccal mucosa.[13] Concomitant occurrence of xerostomia can cause dysphagia in such patients. Most often pseudomembranous candidiasis is manifested or erythematous atrophic candidiasis is seen which leads to a painful mouth in such patients. Candida colonisation is reported to be significantly associated with cognitive impairment, multiple comorbidities, poor oral hygiene and in patients on long-term antibiotics and steroids. This opportunistic fungal infection is commonly seen in COVID-19 patients causing discomfort and inability to eat or swallow. The damage exerted by SARS CoV-2 among patients with Acute respiratory distress syndrome, may allow commensal Candida species to invade the internal organs of the affected patients [Figure 2] and [Figure 3].[14]
Figure 2: Patient suffering from coronavirus disease 2019 with ulceration in the lateral border of tongue and coated dorsum of tongue

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Figure 3: Coronavirus disease 2019 patient with coated and discolored tongue due to candida and drug-induced discoloration

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Gingival inflammation

Gingival inflammation along with bleeding gums is noted in the majority of COVID-19 patients which may manifest as one of the early signs of the disease. This could be attributed to a lack of maintenance of oral hygiene during the disease state leading to biofilm production and bacterial colonization causing gingivitis and bleeding gums. High expression of ACE2 receptors in oral mucosal tissues could also be the contributory factor for inflammation of gingival tissues.[15]

   Conclusion Top

The common oral manifestations in patients suffering from COVID-19 are various forms of ulcerations, inflammation of oral mucosal tissues, loss of taste and smell and Candidial colonization. The oral signs and symptoms may arise even before the disease sets in or a positive RT-PCR report is obtained. Oral healthcare professionals must identify such manifestations and aid in the early diagnosis of the COVID status of such patients. Further studies can be undertaken to elicit the viral load of the patients and a correlation with the type and severity of the oral lesions.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Mehta P, McAuley DF, Brown M, Sanchez E, Tattersall RS, Manson JJ, et al. COVID-19: Consider cytokine storm syndromes and immunosuppression. Lancet 2020;395:1033-4.  Back to cited text no. 1
CDC Centers for Disease Control and Prevention. Symptoms of COVID-19 Updated February 2021. Available from: https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html. [Last accessed on 20 Apr 2021].  Back to cited text no. 2
Sakaida T, Tanimoto I, Matsubara A, Nakamura M, Morita A. Unique skin manifestations of COVID-19: Is drug eruption specific to COVID-19? J Dermatol Sci 2020;99:62-4.  Back to cited text no. 3
Rochefort J, Gaelle Chautx A. Oral mucosal lesions and COVID-19: Symptoms and/or complication? J Oral Med Oral Surg 2021;27:23.  Back to cited text no. 4
Halpert G, Shoenfeld Y. SARS-CoV-2, the autoimmune virus. Autoimmun Rev 2020;19:102695.  Back to cited text no. 5
Mullol J, Alobid I, Mariño-Sánchez F, Izquierdo-Domínguez A, Marin C, Klimek L, et al. The loss of smell and taste in the COVID-19 outbreak: A tale of many countries. Curr Allergy Asthma Rep 2020;20:61.  Back to cited text no. 6
Mariño-Sánchez F, Santamaría-Gadea A, de Los Santos G, Alobid I, Mullol J. Psychophysical olfactory testing in COVID-19: Is smell function really impaired in nearly all patients? Int Forum Allergy Rhinol 2020;10:951-2.  Back to cited text no. 7
Mastrangelo A, Bonato M, Cinque P. Smell and taste disorders in COVID-19: From pathogenesis to clinical features and outcomes. Neurosci Lett 2021;748:135694.  Back to cited text no. 8
Driggin E, Madhavan MV, Bikdeli B, Chuich T, Laracy J, Biondi-Zoccai G, et al. Cardiovascular considerations for patients, health care workers, and health systems during the COVID-19 pandemic. J Am Coll Cardiol 2020;75:2352-71.  Back to cited text no. 9
Xu H, Zhong L, Deng J, Peng J, Dan H, Zeng X, et al. High expression of ACE2 receptor of 2019-nCoV on the epithelial cells of oral mucosa. Int J Oral Sci 2020;12:8.  Back to cited text no. 10
Xu J, Li Y, Gan F, Du Y, Yao Y. Salivary glands: Potential reservoirs for COVID-19 asymptomatic infection. J Dent Res 2020;99:989.  Back to cited text no. 11
Keyhan SO, Fallahi HR, Cheshmi B. Dysosmia and dysgeusia due to the 2019 Novel Coronavirus; a hypothesis that needs further investigation. Maxillofac Plast Reconstr Surg 2020;42:9.  Back to cited text no. 12
Riad A, Gomaa E, Hockova B, Klugar M. Oral candidiasis of COVID-19 patients: Case report and review of evidence. J Cosmet Dermatol 2021;20:1580-4.  Back to cited text no. 13
Arastehfar A, Carvalho A, Nguyen MH, Hedayati MT, Netea MG, Perlin DS, et al. COVID-19-associated candidiasis (CAC): An underestimated complication in the absence of immunological predispositions? J Fungi 2020;6:211.  Back to cited text no. 14
Manzalawi R, Alhmamey K, Abdelrasoul M. Gingival bleeding associated with COVID-19 infection. Clin Case Rep 2021;9:294-7.  Back to cited text no. 15


  [Figure 1], [Figure 2], [Figure 3]


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