COVID-19 modes of transmission and/or infection in dental practice

COVID-19 is more virulent than MERS-CoV and SARS-CoV.¹ Transmission occurs from person to person (direct contact)² via droplets containing the virus and produced by infected people. This transmission mode, also called “direct,” occurs when talking, sneezing, laughing, spitting, and other actions that disseminate infected saliva. When the virus enters the body, it causes respiratory distress, dry cough, coryza, odynophagia, fever, respiratory failure, pneumonia, kidney failure, and death if not treated in time. The virus also spreads through indirect transmission, which does not occur through direct contact, i.e., when people do not interact simultaneously. According to Araya-Salas, the virus can remain on inert surfaces up to 9 days after the infected person expels the droplets with the virus. In this period, another person can be infected if their oral mucosa, nasal or ocular conjunctiva is exposed to that environment, and it can also be transmitted through fomites. This high infectiousness and 3.4% mortality rate has caused concern among health professionals.^1-3

The importance of biosafety in the dental practice

The World Health Organization (WHO) defines biosafety as a set of rules and measures to protect the health of personnel when performing their duties, patients, and the environment from biological, chemical, and physical hazards.⁴

Before the existence and development of the COVID-19 pandemic, dental professionals already had biosafety protocols in place given the high exposure to microorganisms in the oral cavity, which can cause infections when there is an occupational accident during a dental procedure.² The study conducted by Ramos Lages illustrates this point. The author evaluated the knowledge of students from two universities in Brazil on infections due to exposure to biological material in accidents during dental practice. The study found that accidents are quite frequent. However, the institutions that have a protocol and biosafety committee to address this type of situation have greater knowledge of Personal Protective Equipment (PPE), fewer accidents, and improved monitoring of immunity against infectious diseases such as hepatitis B.⁵ Additionally, the study conducted by Martins at the School of Aracatuba among academics and cleaning staff found a high number of accidents with biological material, lack of knowledge of the protocols to be followed after such exposure, and lack of preventive measures.⁶ This shows us that biosafety measures have always been necessary to reduce the spread of diseases to which patients and dentists are constantly exposed. However, not many people implemented them or had sufficient knowledge about them, as seen in the study conducted by Lee Garcés et al. among dental practitioners in a clinic in the province of Guantánamo: most of them were not trained in the subject.⁷⁾ Therefore, dental practitioners need ongoing training to reduce this knowledge gap. To this end, biosafety courses should be included in the studies programs of undergraduate and graduate schools.

Protocols in Latin America: a comparison between countries

Latin American countries have implemented new biosafety measures during the COVID-19 pandemic. They have been grouped into specific protocols. These protocols were developed for the field of dentistry to reduce infections among patients, dentists, and their entire healthcare team.

This review compared the protocols of nine South American countries: Paraguay, Uruguay, Peru, Chile, Argentina, Colombia, Ecuador, Brazil, and Bolivia, which were issued by the ministry and/or department of health of each country.

Triage

Triage is done electronically in all the countries evaluated, either by phone or virtually. Questions are asked to assess whether the patient has symptoms of the disease or has been in contact with a diagnosed person. If everything is all right, the patient should be seen in person, as long as the situation falls within the urgencies or emergencies provided for in each country’s protocols. The process is different only in Peru and Bolivia, where triage can be performed at the health center if there is an impromptu dental visit.^8,9 All countries indicate that the patient should attend alone and comply with the necessary safety measures, except for Brazil, where a support person may accompany children, very ill patients, or patients with special needs.¹⁰

Patient care

All countries state that once the patient is equipped with the necessary PPE and enters the office, they should use mouthwash before any procedure to reduce the viral load. However, rinse type and duration vary in each country. Brazil and Paraguay require 1% or 1.5% hydrogen peroxide for 30 seconds and then 0.12% chlorhexidine.^10,11 In Argentina, Chile, Ecuador, Colombia, Bolivia, Peru, and Uruguay, 1% hydrogen peroxide, 0.12% chlorhexidine, or 0.2% povidone can be used for 30 seconds to 1 minute: only one of them is necessary.^8,11-16 Bolivia is the only country that indicates cleaning the patient’s skin with diluted DG-6 or soap and water.⁹

All countries agree on decreasing the use of high-speed handpieces due to the large amount of particulate matter produced.^9-16

Handwashing

All the protocols agree on using soap and water for effective handwashing; however, there are some variations in time, technique, and use of 70% alcohol. In Ecuador, Brazil, and Colombia, the time indicated is a minimum of 60 seconds^9,10,12 without a specific technique; Bolivia does not specify time but does indicate using an antiseptic after washing.⁹ Regarding techniques, Argentina implements the technique suggested by the Ministry of Health of the City of Buenos Aires, which completes handwashing with alcohol.¹² Uruguay uses the World Health Organization (WHO) technique, which recommends a duration of between 30 and 40 seconds, as does Chile.^13,16 Peru suggests the WHO technique, indicating a minimum time of 20 seconds.⁸

Handwashing is indicated in all countries before and after patient care.

Personal Protective Equipment (PPE)

This is one of the most critical biosafety barrier measures. The following elements are indicated:

The countries that indicate this PPE are Chile, Ecuador, Uruguay, Paraguay, Brazil, Peru, and Bolivia.^{8-11,13,14,16)} Colombia does not indicate the use of protective goggles, and Argentina does not mention the use of surgical caps.^12,15 All countries agree on double gloving and changing masks every two hours, as indicated by the WHO. This equipment should be worn by dentists, patients, and the assistants in charge of the dental office and/or clinic.

Waste management

Waste disposal measures are not uniform in the countries evaluated, so each country will be mentioned separately.

In Paraguay, the following items must be available for waste disposal: a container with a black plastic bag for non-pathological waste, a container with a white plastic bag for waste containing biological material, a container with a red plastic bag for biological and/or anatomical material waste, a container for sharp waste. All disposable materials should be sprayed with 0.1% sodium hypochlorite disinfectant in the garbage can.¹¹

In Peru and Uruguay, COVID-19 biosafety protocols indicate that the measures set forth by the Ministry of Health must be implemented, i.e., no modifications are made.^8,16 In Peru, waste must be classified into three categories: class A as biohazardous waste, class B as special waste, and class C as common waste. Each type of waste is taken to a central or final storage place where all the waste coming from the intermediate or primary storage is stored. It is kept there until transported to the treatment or definitive disposal site.¹⁷ In Uruguay, we found no document providing further details on these measures.

In Chile, waste disposal measures include intraoral radiographs: the plastic protectors covering the radiographs must be discarded. The trash can should be sprayed with 0.1% sodium hypochlorite to decontaminate the waste. The personnel in charge must not take off the PPE until everything has been decontaminated.¹³

Argentina states that office garments must be transported to the washing area in a closed bag and washed without other garments at a temperature higher than 60°C. They also stipulate that N95 respirators must be used for a maximum of 15 days.¹³

Colombia follows the regulations of the Ministry of Health and Social Protection and the Ministry of Environment and Sustainable Development, which state that waste must be separated and deposited, washed, and disinfected. Personnel must have PPE for handling waste when there is a hazard at the time of handling.¹⁵

Brazil indicates that waste from suspected or confirmed cases of COVID19 should be placed in red bags and replaced when they reach 2/3 of their capacity or at least once every 48 hours, regardless of volume. They should be identified with the symbol of the infectious substance. These bags shall be placed in containers made of washable, break-resistant material and have an opening system that does not require manual contact. This waste must be treated before its environmentally sound final disposal. Waste from regular dental care should be specified as category A1.¹⁰

Finally, Bolivia adheres to the protocol outlined in the Biosafety Standards in Dentistry, which follows the regulations for managing the solid waste produced in health facilities. Waste should be classified as infectious (class A), special (class B), and common (class C). All bags should be labeled according to the type of biohazard and should be made of single-use low-density polyethylene. The bags go through a process before collection and external transport for final disposal.⁹

Disinfection and cleaning

All countries agree on the disinfectants used to decontaminate offices and/or equipment. In this case, the recommended solutions are sodium hypochlorite for fumigation, floors, shoes, and 70% alcohol for equipment.^8-16 In Bolivia, no particular concentration is indicated for sodium hypochlorite,⁹ unlike Argentina, Chile, and Paraguay, where 0.1% sodium hypochlorite is recommended.^11-13 Peru recommends soapy water, quaternary ammonium, 62% - 71% ethanol, hydrogen peroxide, and 0.1% sodium hypochlorite. Protective barriers are also recommended after disinfection to cover clinical contact surfaces and to change them between patients.⁸

Colombia also recommends a disinfectant solution based on quaternary ammonium salts for 30 seconds and then rinsing with running water.¹⁵ Finally, disinfectants are used according to their effectiveness and simplicity in Ecuador. An intermediate-level disinfectant should be applied, such as sodium hypochlorite and 70% ethyl alcohol, and the insulating material must be vinyl-type plastic or aluminum foil.¹⁴ Special attention must be paid to surfaces potentially contaminated with blood, saliva, and organic matter, including those near the patient: the reflector and its support, the dental chair, the table with instruments, suction hoses, faucet handles, handpiece hoses, and other surfaces that are frequently touched. All these elements should be disinfected every time a patient leaves the office, so there should be at least one hour between patients. This appears in the protocols of all the countries evaluated.

Sterilization of dental instruments

Most countries have different guidelines regarding instrument sterilization: some provide specific indications while others adhere to their pre-pandemic biosafety technical regulations.

Paraguay and Uruguay state that all the instruments should be autoclaved, and their sterilization should be verified. Uruguay also recommends environmental or UV disinfection.^11,16

Colombia specifies the sterilization of high and low-speed parts, orthodontic forceps, and scalers, which should be autoclaved between patients.¹⁵

Ecuador recommends sterilization according to the type of instruments used, classified as follows:¹⁴

Peru recommends the sterilization process be assigned to someone with specific training. Enzymatic detergent should be used for the instrument cleaning process; then, each instrument should be wrapped and packed in containers for heat sterilization. Handpieces should be disinfected with heat and according to the manufacturer’s instructions.⁸

In Bolivia, instruments are sterilized according to pre-pandemic protocols. There are various methods: autoclaving (the most recommended one), microwaves, radiation, and chemical disinfection.⁹

Care protocols in various associations, departments, and dental centers in Chile and Argentina provide no guidelines on instrument sterilization.^12,13

The sterilization process also has a potential biological risk, as demonstrated by Sánchez et al. in their study on workers in a sterilization area in the province of Guantánamo, Cuba. After completing the study, preventive measures were proposed to reduce the potential spread of diseases at work. Accordingly, the relevant personnel must be fully trained, as highlighted in some country protocols, and have sufficient knowledge to reduce the probability of accidents with biological material.¹⁸

Changes in dental biosafety

Health professionals should take universal precautions and consider any patient as a carrier of pathogenic microorganisms regardless of their economic status, religion, sexual orientation, etc. This becomes even more important in the current SARS-CoV-2 pandemic, which has led to modifications in biosafety measures in the health sciences (Table 1). Dentistry is one of the professions that is highly exposed to virus infection, so it must prioritize the biosafety of personnel and patients.^19-24

Impact of COVID-19 on dental practice

As the dental practice is a health science, it is characterized by direct contact with patients. This contact should be reduced as much as possible in the SARS-CoV2 pandemic. Before the pandemic, dentists were already at risk of infection and had to be careful. However, many of these infections could be avoided with a thorough dental history.

The dental practice involves a high risk of disease transmissibility since it involves fluids like saliva because the aerosols produced by the high-speed handpiece can come into direct contact with the dentist and/or patient, exposing them to infection.²⁵ This is why each country has implemented biosafety protocols that must be respected to protect all the participants in health care.

Currently, as the virus has an incubation period of approximately two weeks, many patients do not know they carry it, which forces us to consider all of them potentially infectious. Therefore we must follow an evaluation guide that reviews clinical manifestations followed by a questionnaire that allows us to make treatment decisions, considering that the case is an urgent or emergency case.²⁶ This classification of the dental processes aims to postpone the visits that can wait until the quarantine period is completed to reduce potential new infections. As a result, the number of patients seen in a dental office is much lower than before the pandemic, which causes concern among professionals in this field, as seen in the study conducted by Castro-Rodríguez²⁷ among several dentists of different specialties in Peru. The study shows concern about the consequences of the pandemic since dental offices were temporarily closed and the disease was spreading dramatically. The financial impact of COVID-19 on dentists can still be seen after months of social isolation, as it has reduced their income due to the low number of patients and the reduced workload because they were not included in the first line of defense. There is also the emotional impact of knowing that seeing patients might entail becoming infected.

As mentioned above, basic protective measures should be taken, such as eye and face protection, masks, caps, gowns, and shoe covers, to protect the health of those involved in a regular dental visit. Additionally, instruments that can be disposed of or sterilized must be used, and the correct disposal protocol must be in place.²⁸ Protective measures will provide patients with security against contagion and emotional security since they might lack the necessary knowledge on biosafety issues and be unable to take the necessary precautions to protect themselves from infection. There is also a preconception and fear towards patients who carry an infectious disease: they always check that the professionals wear their PPE and the surrounding hygiene and work environment.²⁹ In other words, if patients see that the dentist or the dental office where they are treated does not comply with the general measures set forth by the ministry of health, they will not trust the dental clinic, which will harm the practitioner’s reputation. In turn, health personnel should wear their PPE rationally, as concluded by Santos’ study,³⁰ where health personnel are urged to implement strategies to minimize the need for PPE and guarantee its appropriate use. Dentists need to implement more protective measures, which creates additional costs. This adds to the income reduction due to the low number of patients, which has a strong financial impact on practitioners and their families. Patients might complain or feel uncomfortable if they have to bear the additional cost in the fees they pay. An agreement on the fees must be reached considering the current contracting economy.

The new biosafety protocols must be implemented effectively and involve training dentists, assistants, and cleaning staff. Some studies show that these professionals have sufficient knowledge on the subject, as in the study conducted by Silva³¹ in the Unified Health System of the Municipality of Arcoverde in Pernambuco, where positive results were obtained. However, it is also likely that knowledge is insufficient to put this into practice, as observed in the study conducted by Hernandez.³² Although the students knew about biosafety measures, these were not reflected in practice. In turn, a study conducted by Lee Garcés⁷ on dentistry personnel showed that they did not have the necessary knowledge of biosafety protocols. All this indicates that training is essential and must be frequent to be effective, and even more so in the context of a pandemic. The study conducted by Giraldo³³ on the experience in virtual training on biosafety measures reflects that most dentists are interested in training on this subject, especially now that the world is forced to live with the SARS-CoV2 virus, and virtual tools have become very useful when confined. Training is important. However, it impacts dentists financially, as they must invest more in training for them, their assistants, cleaning staff, and receptionists to guarantee and provide quality health service. The measures above are some of those included in most dental practice biosafety protocols in South American countries, which require dentists to invest their time, knowledge, and money.

Pandemic viruses are a health and social risk that affects different areas of life. Consensual biosafety measures should be consolidated in the training of future health professionals to face and prevent many complications.