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.

Temporomandibular Disorders and Oral Features in Idiopathic Inflammatory Myopathies (IIMs) Patients: An Observational Study.

Aim: Inflammatory idiopathic myopathies (IIMs) are inflammatory processes affecting skeletal musculature and extramuscular organs. Temporomandibular disorders (TMD) involve jaw muscles and temporomandibular joint. The aim of this observational study was to investigate the prevalence of the main TMD symptoms and signs as well as oral implications in IIM patients. Methods: The study group included 54 patients (42 women and 12 men), 22 of whom affected by dermatomyositis (DM), 29 by polymyositis (PM) and 3 by inclusion body myositis (IBM). A group of 54 patients not affected by this disease, served as CG. Oral and TMD signs and symptoms were evaluated by means of a questionnaire and through clinical examination. Results: About oral symptoms, the study group complained more frequently dysgeusia, with loss of taste or unpleasant taste (p<0.0001) and feeling of burning mouth (9.4% versus 0 controls). Xerostomia was more prevalent in the study group respect to the CG (p<0.0001). Dysphagia was reported by 48.1% of IIM patients while was absent in CG (p<0.0001). About oral signs, cheilitis (p<0.05) and oral ulcers (p<0.05) were significantly more frequent in CG. As regard to TMD symptoms, arthralgia and tinnitus didn't showed significant differences between the two groups, while neck/shoulders and masticatory muscle pain was significantly more referred in IIM patients than in the CG (p<0.05). About TMJ signs, sounds were overlapping in the two groups: click=11.1% in both IIM patients and CG (p>0.05), crepitation in 11.1% of IIM and 9.3% of controls (p>0.05). No significant difference was detected about deflection (9.3%, p>0.05), while deviation was wider in CG (p<0.05). Active opening and lateralities showed no significant differences, while endfeel was significantly increased in IIM group for a higher presence of muscular contracture. Bruxism was present only in CG. Conclusion: The data collected from this observational study seem to support the existence of a relationship between the prevalence of TMD symptoms and signs as well as oral features in patients with myositis. A remarkable reduction of salivary flow and dysphagia were more frequent and severe in IIM patients, as well as muscle contracture and myofacial pain evoked by palpation, this result being highly significant.

Taste genetics and gastrointestinal symptoms experienced in chronic kidney disease.

BACKGROUND/OBJECTIVES: It is unknown what causes uraemic symptoms in renal disease. Chronic kidney disease (CKD) patients are known to have increased levels of urea, sodium, potassium and phosphate in their saliva compared with those without renal disease. The present cross-sectional study investigated associations between known genetic traits of taste and self-reported upper gastrointestinal (GI) symptoms experienced in CKD patients with the changes in saliva composition found in renal failure. SUBJECTS/METHODS: Fifty-six CKD patients (35 males, 21 females, age 67±14 years), with stages 4 and 5 renal failure, selected from a tertiary hospital renal outpatient clinic participated in this study. Subjects answered a questionnaire to assess upper GI symptoms and tested for the genetic taste recognition thresholds of thiourea, phenylthiocarbamide and sodium benzoate. Saliva samples were collected to determine biochemical composition. Possible associations between genetic taste variations, saliva composition and upper GI symptoms were investigated. RESULTS: Of the 56 patients enroled, 29 (52%) reported major upper GI uraemic symptoms, whereas 27 (48%) had no symptoms or only minor complaints of dry mouth. There was a strong association between the symptomatic burden a patient experienced and the genetic ability to taste thiourea (P<0.0003). Uraemic symptoms of taste changes (P<0.004) and nausea (P<0.002) were found to be related to a patient's genetic ability to taste thiourea. CONCLUSIONS: This study provides evidence that the genetic ability to taste thiourea as bitter, in combination with the increase in active compounds found in CKD patient's saliva, impacts on the uraemic upper GI symptoms experienced.

[A case of myasthenia gravis with invasive thymoma associated with diffuse panbronchiolitis, alopecia, dysgeusia, cholangitis and myositis].

A 43-year-old man was admitted to our hospital because of diplopia, ptosis, and dysphagia that had begun three years previously. He was diagnosed with myasthenia gravis (MG) and invasive thymoma and treated with corticosteroid, thymectomy, and radiation therapy. Ten years after the thymectomy, computed tomography (CT) showed metastasis of the thymoma in the left lower lobe of the lung. Two years after this recurrence, when the patient was 55, respiratory symptoms such as wheezing, persistent cough, and dyspnea appeared. Chronic sinusitis, diffuse centrilobular opacities on CT, and positivity for HLA-B54 led to a diagnosis of diffuse panbronchiolitis (DPB). Despite treatment with clarithromycin, the respiratory symptoms worsened. The patient developed alopecia and body hair loss at the age of 56 followed by dysgeusia, cholangitis, and myositis with positivity for anti-Kv1.4 antibodies. Although treatment with an increased dose of corticosteroid improved hair loss, dysgeusia, cholangitis, and myositis, he died of progression of DPB and serious respiratory infection at the age of 58. In this case, various autoimmune disorders occurred together with MG as complications of thymoma. Although alopecia, dysgeusia, and myositis are already known as complications of MG associated with thymoma, cholangitis is not well-recognized since there have been few reports suggesting a causal relationship between cholangitis and thymoma. Furthermore, DPB caused by immunodeficiency and respiratory tract hypersensitivity associated with thymoma and HLA-B54, respectively, is the distinctive feature of our case. Neurologists should be aware that various organs can be damaged directly and indirectly by abnormal T cells from thymoma in patients with MG.

Dysgeusia limited to sweet taste in myasthenia gravis.

Total dysgeusia, an inability to interpret all of the basic tastes, often occurs with zinc deficiency. Partial dysgeusia (dissociation dysgeusia) is a rare inability to interpret a limited number of these basic tastes. We present the case of a patient with myasthenia gravis who became unable to discern sweet taste, but other basic tastes were unaffected. Such dysgeusia can be explained by obstruction of selective taste receptors in taste cells. We considered that this symptom was induced by an autoimmune mechanism related to myasthenia gravis.