INTRODUCTION

The pandemic caused by the SARS-CoV-2 virus or β-coronavirus (2019-nCoV), started in Wuhan, China and due to rapid expansion has become a major public health problem not only for China but also for others countries of the world1. The etiological agent presents a high transmissibility so that the world assists the isolation of people in their homes before the possibility of contagion. Although there are recent cases of epidemics, the majority originating from Asia², none have presented the level of contagion of the current infection. The WHO has previously warned that lack of awareness among health workers and the general public, coupled with inadequate prevention and control procedures, can lead to outbreaks based on nosocomial infection³.

It is sad that, despite the existence of previous scientific evidence, we resist learning from previous experiences. Eggers and cols. (2015), highlighted five main factors that contributed to the spread of the MERS-CoV; Today perfectly applicable to the SARS-CoV-2 pandemic. 1) a lack of awareness among health workers and the general public; 2) measures for the prevention and control of suboptimal infections in hospitals; 3) crowded emergency rooms and multi-bed hospital rooms; 4) patients seeking care in multiple hospitals; 5) multiple visitors housed with infected patients in hospital rooms⁴.

The SARS-CoV-2 virus has unfortunately spread globally resulting in the 2019–2020 pandemic, as declared by the World Health Organization (WHO) and the Public Health Emergency of International Concern (PHEIC)5. In Ecuador, the first case was confirmed on February 29, 2020, declaring a national health emergency on the following March 11. At the end of this article, there are more than 3,600 confirmed cases, with more than 180 people dead6. The experience of contagion in other countries, mainly China, Korea, Italy and Spain, shows that there are a considerable number of doctors and health personnel who have been infected and some have tragically died5, for which the entities in charge have issued urgently indications and recommendations for the management of affected patients⁷.

Participants in dental practice are exposed to an enormous risk of SARS-CoV-2 infection. On March 15, 2020, the New York Times published an article where a schematic figure describes that dentists are the workers most exposed to the risk of being affected by SARS-CoV-2, much more than nurses and general practitioners8,5; For this reason, dentists should be aware that the routine form of dental care will be modified forever or at least for a long period of time because there is a risk of contagion, particularly due to possible care for asymptomatic patients capable of transmitting the virus and because the way of working puts us in direct contact with potential transmitters and the ways of transmission of the virus are precisely through saliva, bioaerosols, contact with surfaces and work elements that we use daily in the dental office⁹.

There is a dilemma regarding dental treatment, mainly due to the risk of treating asymptomatic patients, potential transmitters of the disease. On the one hand, dental procedures increase the risk of cross infection; while, on the other hand, the well-being of patients is compromised if treatment is not administered and this can be considered unethical. Therefore, treatment planning and work practice should be modified to minimize aerosol generation procedures within a prevention and control environment and, according to some authorities, to consider an approach for cohort convalescence cases for up to 3 weeks from the beginning of the disease¹⁰.

 

The new coronavirus 2019 (SARS-CoV-2)

Viruses need to enter a cell to replicate, and there must be an affinity between the target cell and the virus, so they are tissue-specific and even species-specific, which would not allow contagion between different species¹¹; however, there may be mutations that allow the jump from an animal to a human; In the case of SARS-CoV-2, the natural host may be the bat Rhinolophus affinis, since it showed 96.2% of the complete genome identity to BatCoV RaTG13¹²; but, the differences may also suggest that there are one or more intermediate hosts between the bat and the human. A coronavirus isolated from the pangolin bat comprised 99% genome sequence similarity, indicating that the pangolin may be the intermediate host for SARS-CoV-2¹³.

Coronaviruses belong to the family of Coronaviridae, order of Nidovirals, which have the largest RNA genomes14. There are 4 Coronavirus subgroups (α, β, γ, δ), with SARS-CoV-2 belonging to the β-CoV subtype. Most of the coronavirus can cause infectious diseases in mammals and birds. Α-CoV and β-CoV mainly infect the respiratory, gastrointestinal and central nervous systems of humans and mammals, while γ-CoV and δ-CoV mainly infect birds15. SARS-CoV-2 has the typical protein spike structure of all coronaviruses and binds to target cell receptors via an S protein, facilitating entry into them. Two SARS-CoV-2 strains have been identified in recent weeks: the most aggressive L (70% of cases in China) and the S (least aggressive and 30% of cases)¹².

Figure 1: Electron micrograph and schematic representation. N, nucleocapsid protein; S, spike protein; M, membrane protein; E, envelope protein. The coronavirus M protein interacts with protein N

Fuente: Gorbalenya AE, 200614

Although coronavirus infections normally give mild symptoms, some strains have produced severe damage accompanied by death in many patients, such as the case of Acute Severe Respiratory Syndrome (SARS) in 2002 and Middle East Respiratory Syndrome (MERS ) in 2012¹⁶. The new coronavirus affects the airways and can cause anything from a mild condition, with a dry cough and fever, to much more severe symptoms, such as acute respiratory failure and death-causing pneumonia¹⁷.

The incubation period for SARS-CoV-2 is in a range of 5 or 6 days, but it has been evident that it can be up to 14 days during which many patients remain asymptomatic or with mild symptoms9. This period depends on the age of the patient and the state of his immune system. For example, it is shorter in patients older than 70 years. The most common symptoms are general malaise, fever, cough, and fatigue, while other symptoms include sputum production, headache, hemoptysis, diarrhea, dyspnea, and lymphopenia¹⁸.

 

Transmission of SARS-CoV-2

Being a new virus, various aspects of SARS-CoV-2 and its propagation mechanism are unknown; there was a suspicion of a zoonotic infection, but evidence has shown that mainly person-to-person transmission exists, as has occurred between close contacts since mid-December 201919. Current knowledge is largely derived from similar coronaviruses that are transmitted from person to person through respiratory fomites, but evidence shows that SARS-CoV-2 is more infectious than SARS-CoV and MERS-CoV12. Respiratory viruses are typically most contagious when a patient is symptomatic. However, there is evidence to suggest that transmission occurs during the asymptomatic incubation period^20,21.

Common routes of transmission of the new coronavirus include direct transmission (cough, sneeze, and inhalation of droplets) and contact transmission (with the oral, nasal, and ocular mucous membranes)¹². In the case of SARS-CoV-2, emphasis has been placed on the possibility of autoinoculation; the hands are considered as a vector and are involved in the transmission of respiratory infections. Touching the face with the hands is very frequent; therefore, the risk of autoinoculation must be taken seriously²².

It has been suggested that aerosols can transmit the virus. The saliva droplets discharged by people who sneeze or cough, have a particle size is generally 1 to 5 mm and spread in a space of approximately 1 to 2 m from the source of infection; however, the aerosol can travel tens of meters or more10. Other research has already shown that aerosols are involved in the spread of SARS, MERS, H1N1, and some other diseases^2,17. If aerosols can spread SARS-CoV-2, prevention and control will be much more difficult²³.

Furthermore, it has been confirmed that SARS-CoV-2 enters the cell in the same route as the SARS-CoV coronavirus, that is, through the ACE2 cell receptor (angiotensin II converting enzyme). SARS-CoV-2 can effectively use ACE2 as a receptor to invade cells, allowing human-to-human transmission24. Cells containing ACE2 receptor were found to be abundantly present throughout the respiratory tract, as well as cells morphologically compatible with the salivary gland duct and epithelium in the human mouth¹².

 

Risk of infection in dental environments

Dental patients and professionals may be exposed to pathogenic microorganisms, including viruses and bacteria that infect the oral cavity and respiratory tract. In the past decade, it has been established that, although it is evident that symptomatic patients do not seek dental care due to the characteristics of the infection, the probability of care for asymptomatic carriers who may have contracted the infection must be taken into account, which leads to a subclinical infection10. Additionally, and due to the expansion of SARS-CoV-2, we face a constant risk that an early-infected healthcare worker may bring the virus to our facilities and pass it on to others. Transmission of people with asymptomatic infection has been well documented, although it is unclear to what extent such transmission contributes to the overall spread of infection²⁵.

The risk of SARS-CoV-2 infection invariably occurs in dental care settings due to the specificity of its procedures such as face-to-face communication, exposure to saliva, blood or other fluids, and the handling of sharp or sharps instruments¹²; they can be transmitted through the inhalation of microorganisms suspended in the air for long periods; additionally, human coronaviruses can remain on inanimate surfaces at room temperature for up to 9 days. At a temperature of 30°C or more, the duration of persistence is shorter; therefore, surface contamination in healthcare settings is a potential source of viral transmission²⁶.

The asymptomatic incubation period for people infected with SARS-CoV-2 has been reported to be 1 to 14 days, and it was confirmed that people without symptoms can transmit the virus¹². Likewise, it is unknown if people who have recovered from SARS can carry the virus beyond the isolation period, and the infectivity of these patients is also unknown¹⁰. Since SARS-CoV-2 can be transmitted directly from one person to another by respiratory droplets, emerging evidence suggests that it can also be transmitted through contact and fomites¹². In addition, it has been shown that the viruses were present in the saliva of infected individuals, however, it should be noted that the saliva samples also contain secretions that come down from the nasopharynx or leave the lung through the action of cilia that they line the airways²⁷.

Evidence shows that SARS-CoV-2 is transmitted through droplets, close contact, and fomites. Particles or droplets greater than 100 µm in diameter, such as so-called splashes, are propelled through the air for short distances, generally 3 feet or less, and are quickly deposited on animate or inanimate surfaces. On the other hand, smaller droplets (or aerosols, usually less than 10 µm in size) or small particle debris from evaporated droplets are generally airborne and dragged through the air for an extended period and may settle in the surrounding areas in the clinic¹⁰.

Figura 2: Different transmission routes in the dental environment: aerosol, drops and fomites

Fuente: Ziyu GE, 2020²⁸

Aerosols have been defined as particles that can remain in the air for hours or days and can produce direct effects (they are inhaled, deposited or enter the body) or indirect effects (when the contaminated particles remain on the surfaces)29. Kutter et al. (2018), showed that aerosols from highly virulent pathogens like severe acute respiratory syndrome coronavirus (SARS-CoV) can travel more than 1.8 meters and are able to stay on different surfaces, air samples and surface swabs frequently touched in a room occupied by a SARS patient tested positive for polymerase chain reaction (PCR), even though viruses could not be cultured from these samples²⁹.

Prevention and control

The outbreak of COVID-19 has clearly put oral health professionals at risk of infection, it is of great importance that they are familiar with the identification of patients with SARS-CoV-2 and what are the protective measures that should be used for the dental care of these patients and thus avoid their transmission, taking into account that aerosol drops produced during dental practice are the main routes for the transmission and spread of this pathology^30,12. There is no consensus on the provision of dental services during the SARS-CoV-2 epidemic, the proposed measures are based on relevant experience, guidelines and research, and emergency management guidelines for the prevention and control of infections in the face of outbreak of new coronavirus pneumonia^{31,12,9,30,32}.

1. Patient evaluation or previous inspection (triage)

It is extremely important to identify possible suspicious cases that arise in the dental office. With the evidence given that the incubation period lasts up to 14 days, it is not always possible to identify asymptotic carriers early or without tests taking into account that SARS-CoV-2 is contagious during the incubation period12,30. Before entering the patient's dental chair, the temperature should be controlled with a digital forehead thermometer. In addition, a questionnaire must be completed that includes the following questions to know the personal history, travel history and epidemiological history:

• Have you had a fever or have you had a fever in the last 14 days? Have you experienced breathing problems, such as cough or shortness of breath in the past 14 days?
• Have you traveled or visited areas with documented transmission of SARS-CoV-2?
• Have you come in contact with a patient with confirmed SARS-CoV-2 infection in the last 14 days?
• Have you had contact with people who came from a place with a SARS-CoV-2 transmission notification or with people with fever or documented respiratory problems in the last 14 days?
• Have you had close contact with at least two people with fever or respiratory problems in the last 14 days
• Have you recently participated in any meetings, gatherings, or had close contact with many unknown people?^9,33.
  

 

For suspected / confirmed SARS-CoV-2 cases requiring urgent dental treatment, the highest level of personal protection should be implemented. If a patient answers "YES" to any of the screening questions, and their body temperature is below 37.3° C, the dentist may defer treatment up to 14 days later and suggest that the patient be quarantined at home. If the answer is "YES" to any of the questions and the temperature is above 37.3°C, the patient requires immediate quarantine and the corresponding health authorities should be notified. If the patient answers "NO" to the questions and his temperature is below 37.3°C, dental care is possible with additional protective measures and avoiding the production of aerosols as much as possible. If the patient answers "NO" to the questions and his temperature is above 37.3° C, he requires additional medical attention and no treatment is suggested^{30,12,9,33,34}.

2. Mouthwash before dental procedures

Gargling represents an effective personal hygiene measure against air / droplet transmission as it can reduce the microbe count in the pharynx. Along with hand washing and wearing masks, gargling has been proposed as one of the top three measures of personal hygiene protection against common airborne and droplet infections⁴.

The use of mouth rinses before dental care is one of the most effective methods to reduce the burden of microorganisms in oral sprays. The guide for the diagnosis and treatment of Coronavirus pneumonia, developed by the Chinese Government's National Health Commission, indicated that 0.12% chlorhexidine, which is commonly used as a mouthwash in practice, is not effective for SARS- CoV-2; This virus is susceptible to oxidation, so the suggested mouthwashes are 1% hydrogen peroxide or 2% iodopovidone^30,33.

The oxidative potency of povidone-iodine PVP-I enables the released iodine to react rapidly with functional groups of amino acids and nucleotides, as well as with fatty acid double bonds, resulting in multiple destruction of various structures and enzymes of microbes and viruses. The development of resistance mechanisms against very broad oxidative attack seems almost impossible³⁵.

 

3. Personal protection measures for dental professionals.

Hand hygiene:

Handwashing is always essential in dental practice, but its proper compliance is of utmost importance to avoid the transmission of SARS-CoV-2. A hand hygiene guideline is proposed (2 before 3 after) which are those suggested by the WHO (2009), oral professionals should wash their hands before examining the patient, before dental procedures, after touching the patient, after touching the environment or equipment without disinfection, and after exposure to body fluids. More caution should be exercised in avoiding touching your own eyes, mouth and nose^36,30.

The WHO (2020), stated that hand hygiene includes cleaning hands with an alcohol-based disinfectant or with soap and water; both equally effective. Handwashing must use an appropriate technique to achieve the objective: wet your hands and apply the necessary amount of liquid soap, rub your hands together for a minimum of 15 seconds so that the solution comes in contact with all the surfaces of the hand , paying special attention to the tips and folds of the fingers and thumb, rinse your hands well under running water, then dry them with disposable towels. Washing should take between 20 to 30 seconds. All accessories such as rings, bracelets, cords, earrings and watches should be removed prior to washing^12,36,10.

The technique of using alcohol-based disinfectants is to rub your hands so that the solution comes in contact with all the surfaces of the hand, paying special attention to the fingertips, thumbs and areas between the fingers continue rubbing until the solution has evaporated and hands are dry, approximately takes 20 seconds. The range of antimicrobial activity in alcohol-based hand sanitizers varies with the alcohol compound (ethanol, isopropanol, or n-propanol) used, 60% volumes of n-propanol is approximately equivalent to 70% volumes of isopropanol and 80% volumes of ethanol³⁶.

 

Personal Protective Equipment (PPE)

Since the transmission of infection by airborne droplets is considered the main route of spread, particularly in dental practice, the use of a suitable PPE is recommended, which includes protective glasses, masks, gloves, caps, face shields and protective clothing for all dental care during the epidemic period. It should be noted that protective equipment will only reduce the risk of transmission and cannot provide a failsafe barrier¹².

According to the possibility of spread of SARS-CoV-2 infection, according to Peng et al.12, three-level protection measures of dental professionals are recommended for specific situations:

1) Primary protection (standard protection for personnel in clinical settings). Wear disposable work cap, disposable surgical mask and work clothes (white coat), wear goggles or face shield, and disposable latex gloves or nitrile gloves if necessary.

2) Secondary protection (advanced protection for dental professionals). Wear disposable medical cap, disposable surgical mask, goggles, face shield, and disposable isolation work clothes or surgical clothing outside and disposable latex gloves.

3) Tertiary protection (reinforced protection when the patient is contacted with an infection suspected or confirmed by SARS-CoV-2). Although a patient with 2019-nCoV infection is not expected to be treated in the dental clinic, in the unlikely event that this occurs, and the dental professional cannot avoid close contact, special protective clothing is required. If no protective clothing is available, work clothing (white coat) should be worn with additional disposable protective clothing on the outside. In addition, disposable medical hat, goggles, face shield, disposable surgical mask, disposable latex gloves, and waterproof shoe cover should be worn¹².

 

Face masks

A mask is a core component of PPE that physicians need when caring for symptomatic patients with viral respiratory infections, along with a gown, gloves, and eye protection. But, in caring for a patient with unrecognized SARS-CoV-2, a mask alone in this setting will reduce the risk just a little, as it does not provide protection against drops that can get into the eyes or from patient fomites or in the environment that providers can pick up and carry to their mucosa (particularly given the concern that mask wearers may have a greater tendency to touch their faces). Additionally, a mask can reduce the likelihood of transmission of asymptomatic and minimally symptomatic healthcare workers with COVID-19 to other providers and patients²⁵.

Masks must meet certain conditions: marginal fit to the face and filtering capacity³⁷. A mask is effective when the diameter of the pores of your filter is up to 22 microns³⁸. The effectiveness of the masks has been compared, and it was determined that, when using aerosol powder with particles from 1 to 300 microns in diameter, they achieved 85 to 92% protection for surgical masks and 94 to 96% for masks with respirator³⁹.

Surgical masks commonly used in dentistry should be used if working at a distance of at least 1 m from the patient. When performing aerosol-generating procedures (using a high-speed handpiece, air-water syringe, or ultrasonic scalex), an N95 FFP2 respirator mask should be used when the risk is low or moderate. For emergency care of patients with suspected or confirmed SARS-CoV-2 infection, the use of FFP3 masks is suggested, which is the highest level of protection. Particulate respirator masks with a filtration efficiency of 95% of particles up to 0.3 μ are of the type N95, N99, N100, PFF2 or PFF3^10,30.

Additionally, consideration should be given to wearing face masks that should be changed when soiled or wet, should never be put back on after they have been removed, should not be left hanging around the neck, and should not touch the front of the head mask while wearing it³⁶.

 

Protective glasses

It is clinically evident that SARS-CoV-2 can also be transmitted through contact with the mucous membranes of the eyes, since infectious droplets could easily contaminate the human conjunctival epithelium. To protect the eyes from aerosols during dental procedures, safety glasses with side shields should be worn throughout the treatment and disinfected between patients^30,36.

The Brazilian Federal Council of Dentistry has recommended the use of face masks or "Face Shield". The eye or facial protection must cover the front and sides of the face, and must be used exclusively by each professional responsible for care. After use, it should be cleaned and disinfected with 70% alcohol or another disinfectant standardized by the health service for this purpose³².

 

Waterproof coats

The type of gown required depends on the degree of risk, including the anticipated degree of contact with infectious material, the possibility of blood and bodily substances entering through clothing or skin. Generally, when the procedure to be performed does not require total asepsis, the use of non-sterile waterproof gowns is indicated to protect the skin and avoid contamination of clothing that may be generated by splashes or sprays of blood or saliva. The gowns must be changed between patients, and they must also be long-sleeved and disposable³⁶. Surgical gowns with tight cuffs should be worn to protect both the physician and the patient from the transmission of microorganisms on the skin⁴⁰.

Uniforms are not considered personal protective equipment as they are made of absorbent materials and provide little protection against pathogens. Single-use plastic aprons should be worn to protect against splashes and should be changed between patients⁴⁰.

 

Use of gloves

Gloves avoid direct contact with blood or body substances, mucous membranes, lacerated skin and other potentially infectious materials and potentially contaminated material surfaces. Gloves must be disposable, they can be made of latex or nitrile, nitrile gloves being the most recommended because they have greater resistance to the entry of microorganisms³³.

 

Safe work with sharp objects

Injuries from "sharps" are among the most common types of injuries in dental practice, with an estimated half of these being preventable. These skin lesions are the main route of virus transmission by blood. Therefore, it is essential that appropriate risk assessments, accident reporting procedures and, most importantly, safe work practices are applied. Many sharps injuries occur outside the patient's mouth during rewinding, dismantling, or removal of needles, or during cleaning of sharp instruments such as drills, scanners, and probe tips. Used sharps must be placed in a container in accordance with sanitary regulations⁴⁰.

 

Four-hand operation:

Within dental practice it is important to avoid the generation of aerosols during dental procedures. The use of high-speed suctions, in addition to allowing a dry operating field for dental work, also helps to reduce the contamination of the environment generated by aerosols produced during dental practice by 93%, making it of great importance to implement the work with four hands¹². It is important to note that four-hand work, when applied correctly, prevents the professional who is contaminated with saliva and patient fluids from becoming a vector and spreading the infection in the dental environment.

 

Insulation with rubber dam

Isolation with rubber dams can significantly minimize the production of aerosols contaminated with saliva and blood, particularly in cases where high-speed hand pieces and ultrasound devices are used since many of the dental procedures include the production of aerosols such as : coronary and cavity preparations, removal of restorations, endodontic therapy, removal of orthodontic appliances, polishing restorations, among others. It is reported that the use of rubber dams could significantly reduce airborne particles by 70% combined with high speed suction²⁸.

According to Ge and cols.30, a disadvantage of using the rubber dam is that it is not feasible in procedures that require sub gingival instrumentation, for which some alternatives are proposed:

• In Restorative and Pediatric Dentistry prioritize the removal of caries with manual instruments or you can opt for non-traumatic restoration techniques. If rotary instrumentation is to be performed, rubber dam insulation and high-speed suction must be applied.
• In Periodontics, manual instrumentation should be preferred over ultrasonic because of the higher aerosol production of the latter. Manual root scraping and smoothing is recommended.
• In Prosthodontics, constant saliva suction must be done carefully to avoid nausea. When a dental prosthesis, impressions and other prosthodontics materials such as bite records are to be removed from the patient's mouth, they must be completely disinfected²⁸. Due to its antiviral effectiveness, chlorine solutions are recommended³⁶.

 

Anti-reflux hand piece

The anti-reflux high-speed dental hand piece can prevent cross-contamination, significantly reducing the return flow of bacteria and oral viruses in the tubes of the hand piece and dental unit compared to the hand piece without anti-reflux function. Therefore, the use of dental hand pieces without anti-reflux function should be prohibited during the SARS-CoV-2 epidemic period. Although it is already part of the biosecurity measures, the need to autoclave the hand pieces after daily care is reinforced here¹⁰.

 

Infection control to the dental laboratory

Dental impressions, bite records, trial prostheses, plaster models, can lead to transmit diseases, since they were in contact with body fluids. To reduce the possibility of cross infection among patients, dentists, assistants, and laboratory technicians, it is essential that all impressions and any prosthodontics work that came in contact with the patient's mouth be disinfected⁴¹.

The American Dental Academy (ADA) and the International Dental Federation (IDF) insist on disinfecting all impressions taken from patients before sending them to laboratories. Gupta et al^.41, carried out a comparative study between various methods of disinfection of impressions and concluded that washing the impression with water does not reduce the microbial load of the impression, the most effective and accurate disinfection method is pre-procedure mouthwash, which also did not cause distortion in the print. Together they established the following recommendations:

• Saliva, blood, and biological load must first be cleaned from the impression prior to disinfection.
• Cleaning should be done immediately after impression is taken, before blood and bioburden have a chance to dry.
• Impression materials are first washed in water, then disinfected taking into account that the materials used have a limited tolerance to liquid immersion, therefore, this should be minimized and after disinfection it is finally rinsed again with running water before further processing or shipment to the laboratory⁴¹.
  

 

Radiographic examinations

Intraoral X-ray examination is the most common radiographic technique in dentistry; however, it can stimulate saliva secretion and cough, therefore extraoral dental radiographs, such as panoramic radiography and tomography, are appropriate alternatives during the SARS-CoV-2 outbreak9. Digital Rx equipment sensors must be protected by disposable material and must be changed after each procedure.

 

4. Prevention and control of the diagnostic and treatment environment

Diagnosis and treatment of the environment disinfection method

Medical institutions, such as the dental office, must take effective and strict disinfection measures both in the clinical setting and in the public area³⁰.

It is recommended to mop the floor with water twice a day with 500 mg / L of disinfectant that contains chlorine; In case of suspected or confirmed SARS-CoV-2 cases, apply 1000 mg / L of disinfectant containing chlorine to disinfect the surface and floor of objects. Cleaning items such as rags and mops to disinfect the floor and surface of objects should be clearly marked and disinfected after use⁴².

Kariwa et al. (2006), evaluated the efficacy of a series of chemical agents and various physical conditions to determine their ability to inactivate the coronavirus of severe acute respiratory syndrome (SARS-CoV). Treatment with povidone-iodine (PVP-I) products for 2 minutes reduced virus infectivity to 1.17 X 106 TCID50/ml below the detectable level. The efficiency of 70% ethanol was equivalent to that of PVP-I products. Fixation of SARS CoV infected Vero E6 cells with a fixative including formalin, glutaraldehyde, methanol, and acetone for 5 minutes or more removed all infectivity. Heating the virus to 56°C for 60 minutes or more reduced the virus infectivity from 2.6 x 107 to undetectable levels. Irradiation with ultraviolet light at 134 µW/cm2 for 15 minutes reduced infectivity from 3.8 x 107 to 180 TCID50/ ml; however, prolonged irradiation (60 min) failed to eliminate the remaining virus, leaving 18.8 TCID50/ml⁴³.

Li et al.¹⁰, suggest several complementary measures to cleaning. Ultraviolet radiation can be used in the consulting room twice a day for 30 minutes each time. Good ventilation should be maintained 2-3 times a day for at least 30 minutes each time. The diagnosis and treatment area should increase the physical interval of the patients. Non-independent dental chair clinics can organize a dental chair to schedule a visit. Place as few items as possible on the counter in the consultation area and do not place personal household items⁴².

According to Ge et al.³⁰, in the waiting room, magazines should be removed to avoid cross-contamination, in addition, instruction signs should be placed on how to cough or sneeze, and suitable trash cans should be placed for disposable handkerchiefs. Cleaning and disinfection in public areas should include door handles, chairs, desks, elevators³⁰.

Human coronaviruses, like SARS and MERS, can persist on inanimate surfaces for up to 9 days. This can be minimized by disinfecting for one minute with disinfectants containing 62% -71% ethanol, 0.5% hydrogen peroxide or 0.1% (1 g / L) sodium hypochlorite, depending on the surface to be disinfected^10,30.

 

Device management and medical items

Instruments and reusable items should be pretreated (enzymatic detergents), washed, sterilized and stored properly¹². Indicators such as autoclave tape, sterilization packaging, or bags containing an indicator are useful for identifying items that have been sterilized, but cannot be used to validate the autoclave cycle. However, single-use devices provide a simple alternative to sterilizing sensitive equipment ⁴⁰.

Disinfection processes aim to reduce the microbial load to levels that are considered acceptable. Cleaning and disinfection can be done manually or, preferably, using automated systems. Ultrasonic baths provide excellent cleaning for intricate, jointed, or serrated stainless steel instruments prior to sterilization⁴⁰.

 

Medical waste management

Medical waste should be transported to the temporary storage area of the clinic or hospital. Medical waste (including disposable protective equipment after use) and household waste generated by the treatment of patients with suspected or confirmed SARS-CoV-2 infection are considered infectious medical waste, must be transported with all protections to the area of Temporary storage, using double yellow and ligature bags for closure, must be appropriately marked. These wastes must be transported by the appropriate companies for final disposal¹².

 

Professional vaccination:

Health professionals, being more exposed, have a high risk of contracting infectious diseases, so they must be immunized. The Brazilian Ministry of Health decided to anticipate the National Influenza Vaccination Campaign as a strategy to decrease the number of people with influenza this winter, this may well be applied by the dental professional since they appear stationary in our setting. The vaccine is not effective against COVID-19, but it is a way to help health professionals rule out influenza in detection and accelerate the diagnosis of COVID-19³².

Conclusions

Faced with the SARS-CoV-2 pandemic and due to the unique nature of dentistry, most dental procedures create or present potential risks of infection transmission. Understanding the importance of transmission and its implications in dentistry can facilitate the identification and correction of negligence in daily dental practice. In addition to standard precautions, this review has raised some special precautions that should be implemented during the SARS-CoV-2 outbreak. All staff should be aware of the importance of cross infection control and the underlying principles for maintaining a safe work environment. Understanding the modes of transmission of infectious agents is important in establishing appropriate barriers against transmission. Procedures need to be constantly updated to ensure that systems are operating correctly and that they comply with the latest international and local guidelines. In this process, dental students' awareness of their behavior must also be formed and their understanding improved to optimize compliance with prevention and control protocols.

Bibliografía

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	Suárez-Salgado S; https://orcid.org/0000-0002-7958-6918
	Campuzano R; https://orcid.org/0000-0001-8586-7575
	Dona-Vidale M; https://orcid.org/0000-0003-1282-4712
	Garrido-Cisneros E; https://orcid.org/0000-0001-7899-4576
	Gimenez-Miniello T; https://orcid.org/0000-0001-6583-4610