The Oral Cavity Potentially Serving as a Reservoir for SARS-CoV-2 but Not Necessarily Facilitating the Spread of COVID-19 in Dental Practice

Abstract

Intraoral tissues, secretions, and microenvironments may provide severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with the conditions necessary for viral cellular entry and inhabitation. The aim of the present study is to overview the oral cavity that potentially serves as a reservoir for SARS-CoV-2, and then discuss the possibility that such oral cavity facilitates the spread of coronavirus disease 2019 (COVID-19) in dental practice. Articles were retrieved from PubMed/Medline, LitCovid, ProQuest, Google Scholar, and preprint medRxiv databases. Results of the literature search indicated that SARS-CoV-2 host cell entry-relevant receptor and virus/cell membrane fusion mediators are expressed in major and minor salivary glands, tongue, taste bud, periodontal tissue, and dental pulp, which would be a target and reservoir for SARS-CoV-2. SARS-CoV-2 is present in saliva and gingival crevicular fluid of COVID-19 patients. These secretions would contaminate dental aerosol and droplet with SARS-CoV-2. SARS-CoV-2 inhabits periodontal pocket, gingival sulcus, and dental caries lesion, which could provide SARS-CoV-2 with a habitat. SARS-CoV-2 ribonucleic acid is preserved in dental calculus, which may inform of the previous infection with SARS-CoV-2. Despite involvement of the oral cavity in SARS-CoV-2 transmission and infection, to date, there have been no clusters of COVID-19 in dental practice. Dental settings are much less likely to facilitate the spread of COVID-19 compared with general medical settings, which may be explained by the situation of dentistry that the number of patients to visit dental offices/clinics was decreased during the COVID-19 pandemic, the characteristics of dentistry that dental professionals have maintained high awareness of viral infection prevention, adhered to a strict protocol for infection control, and been using personal protective equipment for a long time, the experimental results that dental devices generate only small amounts of aerosol responsible for the airborne viral transmission, irrigant from the dental unit contributes to the aerosol microbiota much rather than saliva, and the commonly used evacuation or suction system effectively reduces aerosol and droplet generation, and the possibility that human saliva exhibits the antiviral activity and the property to inhibit SARS-CoV-2 infection. It is considered that dental treatment and oral health care can be delivered safely in the COVID-19 era.

SARS‐CoV‐2, periodontal pathogens, and host factors: The trinity of oral post‐acute sequelae of COVID‐19

“…Even periopathogens need zinc, with concentrations ranging from 0.1 to 1.0 mm, for survival and aggregation between bacterial species, enabling virulence activities. The mechanism to achieve proper balance of zinc, extracellularly and intracellularly in oral epithelial cells, is unclear but may involve storage in the mitochondrion, Golgi, and endoplasmic reticulum, which would facilitate zinc availability during post‐translation and functional rearrangements for MMPs 43 . Taken together, we suggest that zinc deficiency associated with loss of taste is a possible indication of microbiome imbalance and improper metalloproteinase activity.…”

“…Crucial SARS-CoV-2 entry receptors, notably ACE2 (angiotensin-converting enzyme 2) and TMPRSS2 (transmembrane serine protease 2), are expressed throughout different cell types within oral tissues, including the epithelial cells of the major and minor salivary glands and the oral mucosa, encompassing both keratinised and nonkeratinised regions such as the gingiva, hard palate, buccal, labial, ventral tongue, and the oropharyngeal mucosa. 35,43 Indeed, saliva testing is an accepted and reliable method for SARS-CoV-2 detection. Importantly, this positive salivary detection corroborated viral detection via nasopharyngeal swabs.…”

Treatments of COVID-19-Associated Taste and Saliva Secretory Disorders

“…Given the expression of viral cellular entry-relevant bio-factors and the high viral load in saliva, major and minor salivary glands are targeted for the direct infection and invasion of SARS-CoV-2, and saliva secreted from them richly contains SARS-CoV-2. Salivary glands are the potential reservoir for SARS-CoV-2 and droplets of saliva contaminated with SARS-CoV-2 is potentially one of causes for COVID-19 transmission [125]. After entering the relevant cells via the ACE2-, TMPRSS2-, and Furin-mediated pathway, cytopathic SARS-CoV-2 could cause damage to salivary glands.…”

COVID-19 in Dental Practice Is Prevented by Eugenol Responsible for the Ambient Odor Specific to Dental Offices: Possibility and Speculation

“…Such dental settings should increase bidirectional SARS-CoV-2 infection between dental practitioners and patients [ 1 ]. In addition to the risk of infection associated with dental treatments, the oral cavity also serves as a reservoir for SARS-CoV-2 [ 2 ]. SARS-CoV-2 is present in and replicates in saliva [ 3 ], minor and major salivary glands [ 4 ], gingival crevicular fluid and gingival sulcus [ 5 ], periodontal tissue [ 6 ], periodontal pocket [ 7 ], dental plaque [ 8 ], and dental biofilm [ 9 ].…”