COVID-19 and oral diseases: Assessing manifestations of a new pathogen in oral infections.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a recently identified virus responsible for life-threatening coronavirus disease 19 (COVID-19). The SARS-CoV-2 infected subjects can be asymptomatic or symptomatic; the later may present a wide spectrum of clinical manifestations. However, the impact of SARS-CoV-2 on oral diseases remain poorly studied. Detection of SARS-CoV-2 in saliva indicates existence of virus in the oral cavity. Recent studies demonstrating the expression of ACE-2, a SARS-CoV-2 entry receptor, in oral tissues further strengthens this observation. Cytokine storm in severe COVID-19 patients and copious secretion of pro-inflammatory cytokines (IL-6, IL-1ß and TNF-α) in multiple symptomatic oral pathologies including periodontitis and periapical periodontitis suggests that inflammatory microenvironment is a hallmark of both COVID-19 and oral diseases. Hyperinflammation may provide conducive microenvironment for the growth of local oral pathogens or opportunistic microbes and exert detrimental impact on the oral tissue integrity. Multiple case reports have indicated uncharacterized oral lesions, symptomatic irreversible pulpitis, higher plaque index, necrotizing/desquamative gingivitis in COVID-19 patients suggesting that SARS-CoV-2 may worsen the manifestations of oral infections. However, the underlying factors and pathways remain elusive. Here we summarize current literature and suggest mechanisms for viral pathogenesis of oral dental pathology derived from oral microbiome and oral mucosa-dental tissue interactions. Longitudinal studies will reveal how the virus impairs disease progression and resolution post-therapy. Some relationships we suggest provide the basis for novel monitoring and treatment of oral viral disease in the era of SARS-CoV-2 pandemic, promoting evidence-based dentistry guidelines to diagnose virus-infected patients to improve oral health.

Covid-19 and oral diseases: Crosstalk, synergy or association?

The coronavirus disease 2019 (Covid-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that clinically affects multiple organs of the human body. Cells in the oral cavity express viral entry receptor angiotensin-converting enzyme 2 that allows viral replication and may cause tissue inflammation and destruction. Recent studies have reported that Covid-19 patients present oral manifestations with multiple clinical aspects. In this review, we aim to summarise main signs and symptoms of Covid-19 in the oral cavity, its possible association with oral diseases, and the plausible underlying mechanisms of hyperinflammation reflecting crosstalk between Covid-19 and oral diseases. Ulcers, blisters, necrotising gingivitis, opportunistic coinfections, salivary gland alterations, white and erythematous plaques and gustatory dysfunction were the most reported clinical oral manifestations in patients with Covid-19. In general, the lesions appear concomitant with the loss of smell and taste. Multiple reports show evidences of necrotic/ulcerative gingiva, oral blisters and hypergrowth of opportunistic oral pathogens. SARS-CoV-2 exhibits tropism for endothelial cells and Covid-19-mediated endotheliitis can not only promote inflammation in oral tissues but can also facilitate virus spread. In addition, elevated levels of proinflammatory mediators in patients with Covid-19 and oral infectious disease can impair tissue homeostasis and cause delayed disease resolution. This suggests potential crosstalk of immune-mediated pathways underlying pathogenesis. Interestingly, few reports suggest recurrent herpetic lesions and higher bacterial growth in Covid-19 subjects, indicating SARS-CoV-2 and oral virus/bacteria interaction. Larger cohort studies comparing SARS-CoV-2 negative and positive subjects will reveal oral manifestation of the virus on oral health and its role in exacerbating oral infection.