How Is Coronavirus Transmitted Via Oral Cavity?
The oral tissues are a potential reservoir for harboring and transmitting the SARS-CoV-2 virus. Mouth washing is a suggested adjunct oral therapy to prevent the virulence of this pathogen. It has always been considered a significantly impactful technique for maintaining gingival and oral health and is a productive method of chemical plaque control to prevent gingival inflammation and halitosis or bad breath.
Several researchers have delved into the study of the effectiveness of mouth washing in preventing the SARS-CoV-2 pathogen from the invasion of host tissue. This is based upon the research-based evidence models and frequently by the virus's transmission through aerosols that the COVID-19 virus gains entry into the lung pathway via the oral cavity because of the concentrated viral load with saliva as a medium to be incorporated into the patient’s bloodstream. Also, periodontitis or gum disease is not the only link for this transmission route, according to this theory proposed by the journal of oral medicine. The other breach that makes oral defenses vulnerable to viral attack by the pathogen is attachment to the ACE2 (angiotensin-converting enzyme) receptors in the tongue.
Although research remains elusive into why some people affected by COVID experience a loss of taste, it is also frequently accompanied by loss of smell in these individuals. Ageusia or loss of taste sensation may be attributed to the alterations in saliva's protein and substance composition due to the harmful microbial load after a viral infection.
Also, some oral viral lesions do tend to mimic those clinical features associated with the SARS-CoV-2 virus but maybe more often inflammatory lesions associated with viral infections of the oral cavity.
What Is the Clinical Trial Efficacy of Some Commonly Recommended Mouthwashes?
Listed below are the recommended mouthwashes by your dental surgeon and the research conducted in clinical trials specifically for the efficacy against the SARS-CoV-2 pathogen:
A. Hydrogen Peroxide or Peroxyl Mouthwash (1 %) - It is a widely used antimicrobial agent with antiviral properties demonstrated in both influenza and SARS-CoV-2 virus. It significantly reduces viral load and may help balance the oral microenvironment and initiate a local innate response by catalyzing reactions.
B. Povidone-Iodine (1 %) Mouthwash - It reduces the viral load for a short period of up to 3 hours. In povidone-iodine varying concentrations, the antimicrobial agent (water-soluble polymer and polyvinyl pyrrolidine) dissociates to release iodine that interrupts the microbial membrane protein. It is also commonly used for antiseptic skin disinfection pre and post-surgery. The American Dental Association (ADA) recommends using pre-procedural povidone-iodine mouthwash before any oral procedure at the dentists’ office for the safety of both the healthcare professional and the patient.
C. Chlorhexidine Gluconate or CHX - Itis a broad-spectrum antiseptic mouthwash that mainly counteracts the microbial action of lipid membrane enveloped viruses. It hence would be most helpful in clinical alleviation of symptoms. Chlorhexidine gluconate (0.12 %) shows significant viral load reduction after immediate rinsing for a brief period and then at 2 to 4 hours post mouth washing.
D. Phthalocyanine Derivative (5 ml), Chlorine Dioxide 0.1 %, CHX 0.2 % - These are other mouthwashes that have also demonstrated a significant reduction in clinical symptoms.
E. Cetylpyridinium Mouthwashes - These contain CPC or cetylpyridinium chloride that is a quaternary ammonium compound with a lysosomotropic action against gram-positive bacteria, yeast, and viral pathogens. It significantly reduces clinical symptoms as well.
What Are the Limitations of These Clinical Trials?
These numerous in vitro studies carried out similarly have tested the viricidal activity of the commonly prescribed mouthwashes and nasal rinses as well yielding promising results. However, the need to assess these clinical trials for testing the long-term safety and effectiveness on a large scale is needed globally. The limitations of these clinical trials are due to the smaller sample size population and no control groups present. However, they imply these evidential results against the CoV-2 pathogen.
What Do the Evidence-Based Models for Mouthwashes in Minimizing COVID Risk Suggest?
The dilutions of the mouthwash in question recommended by the dental surgeons for public use vary in concentrations and indications for use. As per traditional dental research, mouth washing can significantly reduce the viral load in the oral cavity.
The dentist can also recommend mouthwash immediately post dental treatment because the viral transmission can be reduced in a clinical setting when the dentist needs to examine or assess the oropharyngeal region physically or during dental surgical procedures when the patient cannot wear a mask.
In the evidence-based research models conducted on the efficacy of various mouthwashes by the Rutgers School of Dental Medicine, on testing the antiviral properties of the mouthwashes, 3 % (v/v) dilution of Listerine and 1.5 % (v/v) dilution of Chlorhexidine gluconate tended to reduce or minimize the SARS-CoV-2 infection by 40 % and 70 %, respectively without any significant effect on the cell morphology.
On comparison between 0.05 % (v/v) dilution of Colgate Peroxyl and 0.1 % (v/v) dilution of Povidone-Iodine mouthwash, the results showed antiviral properties, however with the side effect of significant cell damage. This result was conclusive that the antiviral effect of Colgate Peroxyl and Povidone-Iodine is a result of its cytotoxic properties.
On testing the direct effect of mouthwash on the SARS-CoV-2 pathogen, both these types of mouthwash, that is, Colgate Peroxyl and Povidone-Iodine, inactivate COVID-19 more effectively than the result obtained with Chlorhexidine gluconate and Listerine mouthwashes. But, the inhibitory effect on the virus is interlinked with cytotoxicity, and hence Chlorhexidine remains a preferable mouthwash over the other suggested mouthwashes to all age groups.
Conclusion:
The antimicrobial elements in mouthwash are definitely beneficial to prevent an individual's risk for SARS-CoV-2 or even the other viral infections of the oral cavity. However, it is so important not to forget that though mouth washing is an effective measure to combat the viral properties of the pathogens, it is not the only substitute to prevent the entry of the viral pathogen. Face masking, social distancing, the use of N95 respiratory masks, avoiding crowded and damp places, particularly in the cases of immunosuppressive patients coupled with proper oral hygiene are the key measures to prevent COVID in a public setting.
