Oral Hygiene Habits and Possible Transmission of COVID-19 Among Cohabitants

Maria Jose Gonzalez-Olmo; Bendicion Delgado-Ramos; Ana Ruiz-Guillen; Martin Romero-Maroto; Maria Carrillo-Diaz


BMC Oral Health. 2020;20(286) 

In This Article


The new coronavirus (SARS-CoV-2) is causing concern in the medical community, as the virus is spreading globally. The fact that asymptomatic people are potential sources of infection[1] justifies a thorough analysis of the dynamics of the transmission of the current outbreak. The virus is mainly transmitted through direct or indirect contact with the mucous membranes of the eyes, nose or mouth.[2,3] In this context, the detection of SARS-CoV-2 and a high viral load in the sputum of a convalescent patient raises concerns about the potential transmissibility after recovery.

The SARS-CoV-2 virus, commonly referred to as a coronavirus because of its unique appearance, has a glycoprotein configuration on its exterior, forming spicules, through which it binds to human cells. In order to protect its genetic contribution, it has a double layer made of lipids in its lower part that performs this protective function.[4] The SARS-CoV-2 virus infects human cells using the ACE2 receptors, which are widely distributed in the upper respiratory tract (hence the lung lesions it causes in affected people) and the epithelial cells lining the ducts of the salivary glands, these being early targets of infection.[5–7] They can also be in the mouth, mainly on the tongue, which is a great reservoir of viral germs. Therefore, tooth brushing, interproximal hygiene and tongue cleaning are essential in order to reduce the viral load in the oral area.[3,8]

In addition, in order to prevent cross-contamination, it is important to ensure that tooth brushes within the family are not in the same container. After use, cleaning devices become contaminated and, if not disinfected, can be a reservoir of microorganisms[9] (including bacteria, viruses and fungi) that maintain their viability for a significant amount of time, ranging from 24 h to 7 days. Microbial survival promotes the reintroduction of potential pathogens into the oral cavity or the spread to other individuals when cleaning devices are stored together or shared.[10]

This has always been a bad idea, but today this separation has become a real necessity, as if we are asymptomatic carriers of the virus without knowledge of it and the brushes are placed together, it can encourage cross-contamination. Recent studies have observed that COVID-19, through friction with the oral mucosa, can be transmitted to the individual.[11]

The same tube of toothpaste should also not be used between members of the same family, as this is another way of facilitating cross-contamination. It is also necessary to store the toothbrush with the brush head upwards, as this facilitates faster drying and hinders the spread of microorganisms.[12–14] Even if the brush is accompanied by a wrapper, it must have openings to facilitate drying.

Toilets should be considered as a possible source of viral contamination of indoor and surface air. In fact, constant microbial contamination of the indoor environment often occurs after toilet flushing, and this can be a major source of spread, not only for enteric but also for respiratory viruses, which are also often eliminated by faecal means. Toilet flushing generates a large number of droplets of different sizes: the larger droplets settle quickly on surrounding surfaces, while the smaller ones can be inhaled or remain in the air for a long time.[15] The level of contamination in the toilet environment has been studied, concluding that the highest levels of surface contamination were located near the source of the aerosol, at the level of the toilet seat. However, contaminated surfaces were also found at a distance of 83 cm from the toilet. This is the reason why the toothbrush should also be kept away from the toilet (at least 1 m) to avoid possible contamination, as the virus is also found in feces and urine.[16,17]

At the end of an eventual infectious, process it is necessary to be cautious and use a new brush, as even if the power of reinfestation of the virus is not known, it is necessary to bear in mind that the brush can constitute an emitter of germs to other brushes used by other members of the family or even to one's self.

Disinfection of the brush head after use with povidone-iodine at 0.2% or hydrogen peroxide diluted at 1% for 1 min[18] is very necessary to maintain good cleanliness,[19] as the brush filaments can be infected by germs from the environment. It is necessary to know and take into account the temporary duration of the stay of the coronavirus on different surfaces;[18] in order to be prevent infection, it is important to know that the duration for the stay of coronavirus on plastic is 72 h.

When there is an active development of COVID-19, a 0.2% povidone-iodine mouthwash or 1% dilution of hydrogen peroxide can be used for 1 min[18] to try to control the oral load of germs, as although scientific evidence is limited,[1,18] it has been observed that such products can be effective in rendering the lipid envelope of the virus inoperative.

There are many families who are currently confined to their homes because they are positive for COVID-19. Precautionary measures regarding cleanliness and asepsis to be performed in the homes by family members are well-known in order to prevent infection among them.[20] However, less emphasis has been placed on oral care to reduce the viral load and on the dental environment to prevent the risk of cross-contamination of COVID-19.

Taking into account the above considerations, the aim of this research is to find out whether misuse of dental hygiene, in terms of certain dental habits, may facilitate the spread of COVID-19 among cohabiting individuals.