Is oral hygiene as important as hand hygiene during COVID-19 pandemic?

INTRODUCTION

The recent global outbreak of the novel coronavirus disease (COVID-19) has once again brought to the forefront the importance of hand-hygiene and sanitization in preventing highly contagious viral infections.^[1,2] Although direct inhalation of infected respiratory or nasal droplets remains the primary mode of transmission of SARS-CoV-2, hand-hygiene is a very effective method of disease prevention by stopping the indirect transmission.^[3] The leading health organizations such as World Health Organization and Center for Disease Prevention have endorsed the role of correctly performed hand hygiene as a primary and easy to implement preventive measure for breaking the chain of transmission of the disease.^[4,5] It is advised to wash hands with soap and water for 40–60 s, and if it is not available, then with an alcohol-based hand rub (ABHR) for at least 20 s.^[6] Unlike the germicidal action of ABHR that involves protein denaturation and cell membrane disruption, surfactant in the soap reduces water tension, lifts soil and microbes, and thus clean them from the skin. Scrubbing with soap and water results in the mechanical removal of microflora.^[7,8] Popularly known in India as SUIMAN [Seedha (Rubbing palm to palm and between fingers), Ulta (Back or dorsum of each hand), Interlacing fingers, Muthi (Back of fingers to opposing palm with interlacing fingers), Angutha (Rotation and rubbing of thumb clasped), Nakhun (Nails), and Kalai (Wrist)] method of hand hygiene practices are propagated among the healthcare workers and the general public. Government and non-government organizations have utilized various platforms such as social media, newspapers, and posters campaigns to promulgate and instill the practice of correct handwashing techniques among the public. In health-care settings, one can see the pictorial presentation of the five moments of hand hygiene and the steps of handwashing displayed in the patients’ waiting area and the operatory. Handwashing is not a new thing. It has always been a part of culture and religious belief systems all over the world. But surprisingly, it was not an integral part of health-care settings until the late 1800s.^[9] Hands are a potential reservoir and vector for various pathological microorganisms. They come in contact with numerous already contaminated animate and inanimate surfaces.^[1] Studies have shown that people touch their face approximately 23 times in an hour, which poses a threat for virus transmission through oral, nasal, or conjunctival mucosa.^[10]

Since the oral cavity is portal for the virus’s entry into the human body, it is sensible to state that, like hand hygiene, oral hygiene is essential in reducing infection from the oral cavity, and thus, its transfer to the upper and lower respiratory tract. Scientific evidence suggests maintaining optimal oral health status minimizes the incidence of hospital-acquired pneumonia.^[11,12] Self or professional- driven standard oral hygiene practices can reduce the rate of complications that may occur secondarily due to the aspiration of oropharyngeal microorganisms.^[12] Further, evidence supporting the enhancement of tooth-brushing- induced bacteremia due to diseased breached oral mucosa, gingival, and periodontal tissues in poor oro-dental health patients,^[13-16] further emphasizes maintaining optimum oral health in critically ill hospitalized patients. Thus, understanding the importance of oral health care is essential for patients who are hospitalized.^[17] Although there is no randomized clinical trial, yet oral hygiene maintenance may be a potentially effective method to reduce the morbidity and mortality related to COVID-19 pandemic.

CONTEXTUAL OPINION

In a letter to the editor to the British Dental Journal, Addy^[18] wrote that he was surprised that why dental community is not propagating tooth brushing on the same scale as handwashing to help in the prevention of COVID-19 and said that oral hygiene recommendations should be re-enforced by the governments, authorities, and the media. Authors opine that meticulous oral hygiene may reduce the probabilities of SARS-CoV-2 spread in quarantine and isolation centers, as well as in hospitalized COVID-19 patients. The reason for this opinion is based on the following shreds of evidence:

1. Scientific evidence suggests that due to a higher level of angiotensin-converting enzyme-2 expression in the salivary glands, the epithelial lining of salivary ducts, and oral mucosa, these are early target cells for coronavirus,^[19-22] thus SARS-CoV-2 virus colonizes in the oral cavity.

2. The most common portal for entrance and outlet of viral infectious disease transmission through droplets and aerosol is the oral cavity.^[23,24] Oral cavity harbors numerous pathogens, including viruses, and in dysbiosis condition, the oral ecosystem becomes more conducive for the colonization of potential oral and respiratory pathogens. Viral infection colonizes in the oral and periodontal environment, lower and upper respiratory tract, gingival crevicular fluid, and major or minor salivary glands.^[22,24]

3. Saliva contains discharges from nasopharynx and lung (due to ciliary actions in airway lining);^[25,26] therefore, the potential of a microorganisms-spillover from the oral cavity to the respiratory system and vice-versa cannot be ruled out.

STANDARD ORAL HYGIENE PRACTICES

Similar to hand hygiene, ancient literature reports various preparations and methods of oral hygiene maintenance among the Sumerians, the Babylonians, and the Assyrians.^[27] At present, standard oral hygiene measures consist of thorough cleaning of all surfaces of teeth using a toothbrush with toothpaste, interdental areas, and tongue daily. An interesting article stated that a suitable time of brushing during COVID-19 pandemic maybe just before stepping out and coming home.^[28] Recommended timing for tooth brushing should not be less than 2 min, and more than 5 min revealed no additional benefit. Toothbrushes should be changed every 3 months or when visibly frayed. If toothbrush is fraying early than 3 months, it means a person is brushing too hard and forcefully. If toothbrush is not fraying even after 3 months, it means the person is not brushing correctly. The measures for healthy oral hygiene practices during and even after the COVID times are summarized in Table 1.

The toothbrush is the most common tool for cleaning teeth and comes in contact with microbial dental plaque and saliva. Thus, retaining microbes in the brush after cleaning the teeth may re-contaminate the mouth.^[29] Studies show that after a single use for a duration ranging from the 30 s to 4 min, toothbrushes may become contaminated by various microorganisms such as bacteria, viruses, yeasts, and fungi.^[30] Often the toothbrushes are stored in bathrooms or combined toilet/bathrooms, which are warm and moist, and are an ideal place for the growth of microorganisms.^[31]

Disinfection of toothbrushes after use is often neglected practice. It is seen that the majority of people just rinse the brushes with plain water and then dry it to prevent contamination with potential disease-producing bacteria fungi and viruses.^[32,33] In a survey-based study conducted by Peker et al.^[34] to assess knowledge of toothbrush hygiene among dental students, 62.6% of the respondents reported that they did not know about toothbrush disinfection and did not disinfect their toothbrushes. It is advisable to dip the toothbrushes into an antiseptic mouthwash a few minutes after rinsing with water after each use. Studies have shown that toothbrush sanitization with UV rays for 2 h,^[35] and overnight immersion in 0.12% or 0.2% chlorhexidine is highly effective for toothbrush decontamination.^[36] Other studies have reported the use of microwave sterilization and herbal agents for toothbrush disinfection [Table 2].^[37,38] Furthermore, the disinfection of the brush handles with an alcohol-based sanitizer should be done after use. It is wise not to keep all toothbrushes of family members in a common holder. They should never be shared and can be color-coded to avoid confusion of mistakenly being used by anyone else in the family.

Toothpaste most often contain the same detergent-based cleaning agents (sodium lauryl sulfates [SLSs]), which have proven to be effective in handwashing methods.^[18] Besides having antimicrobial and plaque inhibitory properties, anionic surfactant SLS imparts foam, and dissolves and inactivates various nonenveloped as well as enveloped viruses including retrovirus, rotavirus, poliovirus, HSV2, and HIV infectivity.^[39,40] Mechanism of action through which SLS inactivates viruses is denaturing of the viral envelope and capsid protein. It has been shown to have moderate substantivity of 5–7 h.^[41] However, in patients allergic to SLS or patients with diseased-sensitive oral and gingival tissue, SLS-free toothpaste is recommended.

The use of antiseptic mouthwashes as oral rinses and gargles is also a commonly performed oral health-care measure. In Japan, daily gargling was recommended by government officials as a protective hygiene practice to prevent upper respiratory tract infections in both healthy and diseased individuals after the H1N1 swine flu outbreak in 2009.^[42] The leading dental societies and associations like the American Dental Association and American Association of Endodontics advise the use of pre-procedural mouthwashes such s 0.2% Povidone-iodine and 1% hydrogen peroxide before performing any dental treatment to reduce the viral/ microbial load of the aerosols.^[21,43] According to a meta- analysis by Marui et al.,^[44] pre-procedural mouth-rinse with 10 ml of chlorhexidine (0.1% or 0.2%), cetylpyridinium chloride, and essential oils led to a mean reduction of 68.4% colony-forming units in dental aerosols. Based on the previous studies on SARS and MERS, the SARS- CoV-2 is also considered to be vulnerable to oxidizing agents. Sodium bicarbonate normal saline relieves pain and promotes healing of oral wounds and after surgery, but does not inhibit microbes.^[45] Slots,^[46] while reviewing the low-cost periodontal treatment option, suggested that Povidone-iodine and dilute sodium hypochlorite may be the first choice antiseptics for treatment and periodontal disease prevention. Being a highly active cytotoxic oxidant, sodium hypochlorite (NaOCl) is an effective antiseptic and disinfectant agent against bacteria, fungi, and viruses. The recommended dosage is 8–10 ml (2 teaspoonfuls) of 6% household bleach, diluted in 250 ml of glass water, yielding 0.25% of sodium hypochlorite rinse to be used orally for 30 s for about 2–3 times a week.^[46,47] It reacts with proteins, nucleic acids, and lipids, and inactivates enzymes essential in the energy-yielding metabolism of microorganisms.^[47] Thus a routine use of the mouthwashes may help in reducing the viral load of saliva and oro-pharyngeal cavity.

ORAL HYGIENE AND COVID-19 PANDEMIC

Oral hygiene is an integral part of personal hygiene practices and should not be neglected. While it is necessary to follow rigorous oral hygiene procedures, it is also essential to keep our toothbrushes clean and free of infection, regularly. First and foremost, one should wash hands with soap and water, or sanitize with ABHR before touching the toothbrush. COVID-19 positive patients should have personal oral hygiene products that include a new soft toothbrush, toothpaste, and a mouthwash/gargle that should be discarded after the condition is improved. They should store their oral health products separately and disinfect their brush regularly. Powered toothbrushes and water-pik/oral irrigators may have the potential to produce more aerosols than manual toothbrushes and should be avoided. There is a need to develop professionally driven need-based standard oral hygiene programs (e.g., soft triple head toothbrushes, and associated suction toothbrushes) in critically ill patients with disability and limited manual dexterity.^[17,48]

Oral health-care providers should emphasize maintaining oral hygiene in the general public and hospitalized patients. Similar to the “Fit For School” public health program that includes tooth brushing, hand hygiene, and anti-helminthics in school children in the Philippines and Indonesia,^[49] general public oral health awareness campaigns can be adapted globally in the current COVID-19 pandemic. Thorough tooth brushing for “Two Times For Two Minutes” in a day is an easy key to remember, and is equally essential as 20 s of hand hygiene in the current COVID-19 pandemic scenario.