June 25, 2021

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The role of the oral cavity in the transmission of Covid-19 is analyzed | PRESENT

A group of researchers from the School of Dental Medicine of the Medical Sciences Campus (RCM) of the University of Puerto Rico (UPR), announced that they have been conducting an analysis of a growing set of scientific publications for the purpose to evaluate the role of the oral cavity in the transmission of Covid-19.

This, in collaboration with Professor Pedro Antonio Del Valle López, Librarian of the RCM.

“The oral tissues express high levels of the ACE2 receptor that SARS-CoV-2 is used to invade human epithelial cells. For this reason, the oral cavity can be a reservoir of the virus and can play a fundamental role in the diagnosis, evolution and epidemiological transmission of Covid-19 infection patterns, ”said Dr. Augusto Elías, Research Assistant Dean of the School of Dental Medicine (EMD) of the UPR.

In turn, Dr. Francisco Bermúdez, a maxillofacial surgeon and expert in biochemistry and physiology of saliva, explains that the expression of the ACE2 receptor in the minor salivary glands and the epithelium of the tongue may be the cause, in part, of the loss of the sense of taste, which is one of the initial symptoms of Covid-19. Furthermore, it can cause sialoadenitis, an inflammation of the salivary glands

“Saliva plays a natural role in protecting oral tissues, maintaining hydration of the epithelium and protecting it against infections through specific protein components in saliva, including antiviral activity. The risk of infection with Covid-19 is higher in the elderly population and the prevalence of hyposalivation is higher in this group due to a higher incidence of multiple health conditions and / or the use of multiple medications. Both situations could reduce saliva secretion, "explained Dr. Bermúdez.

According to Dr. Lydia López, clinical researcher, several additional oral manifestations have been reported in adults infected with the coronavirus, including blisters, dermatitis, bruising in the mouth, fissures in the lips, ulcers in the mouth and skin lesions.

"Children infected with Covid-19 can also present oral manifestations compatible with Pediatric Multisystemic Inflammatory Syndrome", in some cases, similar to those observed in Kawasaki Syndrome ", such as blisters, fissures on the lips, strawberry tongue, bruising of the mucosa, erythema, sialoadenitis and loss of the sense of taste, among others. These symptoms may worsen as the infection progresses and they have been linked to the detection of IgG and IgM antibodies in saliva tests, "explained López.

It should be noted that the Federal Administration d e Food and Drug Administration (FDA) recently approved the use of Covid-19 devices or kits for saliva sampling or molecular testing kits.

“Once validated, these collection methods of Saliva can have considerable advantages compared to nasopharyngeal swab cultures because they are a faster, painless, less invasive, and less uncomfortable alternative that can help minimize exposure of healthcare personnel to potential infected patients during sampling. The kits include a preservation solution that inactivates the live virus in saliva after extraction, which offers greater protection to laboratory personnel and during the transport of samples, "said Dr. Carmen Buxó, genetic epidemiologist and principal investigator of the The Caribbean Dental Biorepository (CariDen) of the School of Dental Medicine.

The researchers explain that the first device for taking saliva samples available in the market approved by the FDA through an Emergency Use Authorization (USA), by its acronym in English) due to the coronavirus pandemic was SDNA-1000 from Spectrum Solutions. This kit allows the person to take their own saliva sample under the supervision of a health professional. Recently, these kits were approved to include home sampling using instructions or videos, and even under remote supervision of healthcare professionals. Samples are sent at room temperature or extreme temperatures to Rutgers University and other laboratories that have received approval under the Clinical Laboratory Improvement Amendments (CLIA) and the FDA for saliva testing and polymerase chain reaction (PCR) analysis. Results are available within 2-5 days. Two additional saliva sampling kits from OraSure Technologies Inc., using Genotek DNA saliva collection devices, were recently authorized for emergency use (USA) for Covid-19 testing. The number of other similar kits is expected to increase rapidly.

Evidence on symptomatics

For her part, Dr. Sona Rivas Tumanyan, specialist in oral epidemiology, explained that, at present, the evidence on the precision of these tests is largely limited to sensitivity estimates obtained from confirmed symptomatic cases of the virus, while only one study included high-risk asymptomatic / presymptomatic participants (health workers).

“Overall detection rates of Saliva tests among samples obtained from confirmed symptomatic cases (i.e., sensitivity) ranged from 68% to 89%. The sensitivity of saliva tests to detect Covid-19 was reported to decrease as the disease progressed, from 86% in samples obtained during the first week of symptom onset to 77% during the second week. and 64% during the third week. Overall, when compared to nasopharyngeal swab cultures, saliva tests offered increased sensitivity in 3 studies, while only one study revealed lower detection rates in saliva samples (68%) than nasopharyngeal swab cultures ( 79%). Saliva testing for Covid-19 was evaluated among asymptomatic / presymptomatic participants in a study of 98 asymptomatic healthcare workers in which 2 participants tested positive for saliva, while none were detected by nasopharyngeal swab culture. This suggests that the detection rate is possibly higher in saliva tests, "said Dr. Rivas.

Likewise, Dr. Sona Rivas Tumanyan warned that," the results of studies on the validity of tests of saliva should be interpreted with care, due to the limited sample size in the available studies. ”

Dr. Milagros Toro, an oral biologist, noted that“ detection of the Covid-19 virus in children's saliva is slightly less than that of nasopharyngeal swab cultures (73% vs. 92% in symptomatic children and 67% vs. 100% in asymptomatic children). ” However, saliva tests to detect Covid-19 may be a good alternative for children because they are less invasive than a nasopharyngeal swab culture. ”

Commensal bacteria in the mouth contribute to the production of nitric oxide through the entero-salivary pathway. "Nitric oxide has many biological functions that could be important for the prognosis of Covid-19 infection and the development of complications. Nitric oxide has also been shown to have antiviral activity against SARS-CoV-2; therefore, commensal bacteria in the mouth could act as a protective barrier against Covid-19 infection. It is necessary to determine to what extent oral bacteria contribute to these functions, "said Dr. Evangelia Morou, a specialist in oral microbiology, who is currently a principal investigator with the epidemiologist Dr. Kaumudi Joshipura, from a study funded by the National Institutes of Health (NIH) to evaluate the role of commensal bacteria in the mouth in the production of nitric oxide through the entero-salivary pathway, which plays a fundamental role in maintaining endothelial function and in the cardiometabolic health.

According to a recent pilot study, a substantial reduction in SARS-CoV-2 in saliva has been demonstrated after rinsing with chlorhexidine. However, the viral load in the saliva returned to the reference levels in a period of four hours. The extent to which the use of mouthwashes can prevent transmission has not been established, as well as the type, frequency and duration necessary to achieve this. The antiviral effects of some short-term mouthwashes could also potentially reduce the validity of Covid-19 tests performed on oral or oropharyngeal specimens.

Dr. Joshipura expressed concern that, “the use of mouthwash has been on the rise since the pandemic. Regular long-term use of non-prescription mouthwashes could increase the risk of complications from Covid-19 due to its impact on the entero-salivary nitrate pathway and cardiometabolic disease, despite its possible short-term antiviral effect. ” .

In turn, epidemiologist Oelisoa M Andriankaja raises additional concerns regarding the possible link between periodontal disease and chronic health conditions, such as hypertension, obesity, chronic lung disease, diabetes, cardiovascular disease, and kidney disease, which are known to increase the risk of complications with Covid-19. According to Andriankaja, “the oral cavity is considered to be a reservoir of respiratory pathogens; periodontitis is related to a risk of mortality from aspiration pneumonia in the elderly. ”

Risks for dentists

Rosana Hanke, a pediatric dentist and clinical researcher, states that so far no Cases of Covid-19 infection due to exposure during dental procedures have been reported. However, it notes that dentists and dental personnel are exposed to a high risk of Covid-19 infection and must implement evidence-based recommendations to protect their health and the health of their patients.

"Dentists have always taken universal standard precautions for infection control in their offices. With the advent of Covid-19, they have taken additional precautions against respiratory pathogens to offer greater protection to their patients and staff. Examples of additional precautionary measures dentists have taken include the use of higher quality face masks, disposable waterproof gowns, high volume suctions in and out of the mouth to control the dispersion of small droplets and sprays, and mandatory disinfection hands for everyone who enters the office. Definitely, in the future we will have better scientific evidence regarding Covid-19 and effective infection control in dental offices. At the moment, we are trying to take the best precautionary measures for our staff and our patients, "said Dr. Hanke.

The researchers argue that dentists can play a critical role in the early diagnosis of Covid-19 by Observe signs of the presence of SARS-CoV-2 in asymptomatic patients, such as loss of sense of taste, inflammation of the salivary glands, hyposalivation and intraoral manifestations described above. Since dentists are also properly trained and possess the necessary equipment to take saliva samples to perform Covid-19 tests on asymptomatic patients, including children. More importantly, a healthy mouth and oral microbiome can help control cardiometabolic conditions that increase the risk of contracting Covid-19.

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