key: cord-0034978-gegboxgs
authors: Schneiderman, MaryAnn T.; Cartee, Deborah L.
title: Surface Disinfection
date: 2019-11-18
journal: Infection Control in the Dental Office
DOI: 10.1007/978-3-030-30085-2_12
sha: 43b8a4b29ea8a7ff0642807f10aa0e2f30cbaee6
doc_id: 34978
cord_uid: gegboxgs

The patient-care areas in a dental setting become contaminated with bacterial and viral pathogens during patient treatment. Incorporating standard precautions set forth by CDC and OSHA guidelines will reduce the risk of disease transmission. Contaminated environmental surfaces, including clinical contact and housekeeping surfaces, become a reservoir of infectious material with the potential to spread an infection to health-care personnel and patients. Transmission of pathogens can occur by direct or indirect contact of clinical contact surfaces and the hands of health-care personnel. Proper infection control protocol of these surfaces includes cleaning, disinfecting, and the use of barriers to prevent the spread of infectious pathogens. This chapter will provide an overview of the disinfection protocol of environmental surfaces in the dental setting. The topics include the various chemical formulations of hospital disinfectants and their proper use, as well as physical barriers that aim to reduce the degree of contamination in the dental treatment area thus decreasing the probability of cross-infection and disease transmission.

In the dental treatment area, any surface or equipment that does not directly contact a patient is designated as an environmental surface. Environmental surfaces in the dental treatment area are divided into two categories based on the degree and type of contamination to which the surface is exposed [1] . These categories include clinical contact surfaces and housekeeping surfaces. Clinical contact surfaces are any surfaces that might be directly or indirectly contacted or touched and become contaminated with blood or other potentially infectious materials by gloved hands, aerosol, instruments, devices, or other items in the course of providing dental care. Table 12 .1 [5] provides a list of the most common clinical contact surfaces in the dental treatment area. All other surfaces that are not involved with patient contact and not directly touched during dental treatment, such as floors, walls, sinks etc., are designated as housekeeping surfaces. 

Dental personnel and the dental treatment areas are typically exposed to blood, saliva, and other potentially infectious materials during the course of patient care. Environmental surfaces in the dental treatment area are exposed to a multitude of contaminated items on a routine basis. Contamination from any of these organisms may result in disease transmission that may occur from direct contact with infected body fluids and tissues or indirectly by contacting surfaces and/or devices that have been contaminated [1] . Anything that is placed into a patient's mouth is contaminated with that patient's microflora. Additionally, any dental provider who touches an instrument, device, or material that was in a patient's mouth is also contaminated with that patient's microflora and has the potential to spread contamination to other surfaces and/or instruments and devices throughout the dental office. Furthermore, any environmental surface that comes in contact with an instrument, device, or material that was in a patient's mouth is also contaminated. This microbial contamination can be disseminated through the following potential routes of transmission:

1. Direct contact with blood, oral fluids including saliva, other body fluids, or other patient materials. 2. Indirect contact with contaminated objects including instruments, equipment, or environmental surfaces. 3. Contact of eyes, nose, mouth, and/or mucous membranes with droplets/spatter containing microorganisms generated from an infected person when they cough, sneeze, or talk. 4. By inhalation of airborne microorganisms that can remain suspended in the air for long periods [1] .

Instruments used frequently in routine dental procedures include rotary high-and low-speed dental handpieces, air abrasion, sonic and ultrasonic scalers, air polishers, and air-water syringes. All produce an aerosol spray and/or dental splatter. Depending on the dental procedure performed, aerosol from any of these instruments has the potential to contain droplets of water, saliva, blood, microorganisms, and other potentially infectious materials. Dental aerosols and splatter travel through the air, settle on treatment area environmental surfaces and equipment, the patient, dental personnel, or on the floor.

The area contaminated by aerosols produced during dental procedures using highspeed rotary instruments is far larger than previously thought [6] . Additionally, when using an ultrasonic scaling instrument, aerosols have been found to remain in the air for up to 30 min after the procedure [7] . Aerosols produced during dental procedures have the potential to transmit infectious diseases that can be transmitted by an airborne route. Numerous infections have been documented as being transmitted by an airborne route, the most common being the apparent transmission of cold and influenza viruses. There is evidence in the medical literature of the airborne spread of measles, tuberculosis, and severe acute respiratory syndrome (SARS) [8] . Therefore, aerosols generated in the dental treatment area create an additional potential risk for disease transmission to the immunocompromised patient and dental personnel [6, 7] . Reduction of the transmission of infections from aerosols and subsequent contaminated environmental surfaces in all health-care settings, including the dental treatment areas, is best accomplished by incorporating recommended infection control guidelines and standards into the routine practice of dentistry [1, 9] .

Among the most important lapses of fundamental infection control principles are failure to perform hand hygiene and adequately disinfect environmental surfaces/ devices [10, 11] . Contaminated environmental surfaces can serve as a reservoir for microbial pathogens. These bacterial, fungal, and viral pathogens can persist on inanimate surfaces for considerable periods of time (see Table 12 .2a-c); for example, most Gram-positive bacteria can survive for months on dry surfaces [2] . Many Gramnegative species can also survive for weeks to months, and Candida albicans can survive up to 4 months on surfaces [2] . In one investigation, hepatitis C virus (HCV) was shown to maintain infectivity on surfaces for up to 6 weeks at 4 and 22 °C supporting the hypothesis that the increasing incidence of nosocomial HCV infections may be due to accidental contact with HCV-contaminated fomites and other hospital equipment even after prolonged periods following their deposition [11] . Antibiotic resistance is one of the biggest threats to global health [12] . Many resistant microorganisms cause infections that result in significant morbidity and mortality on a global scale [12, 13] . One of the most significant contributing factors in the spread of resistant infections, including MRSA as well as other drug-resistant organisms, is noncompliance with recommended infection control practices [14, 15] . The CDC estimates that more than two million people in the United States are sickened every year with antibiotic-resistant infections; and at least 23,000 Americans die each year from these infections [12] . Antibiotic-resistant infections are caused by numerous organisms such as:

• Clostridium difficile.

• Carbapenem-resistant Enterobacteriaceae. [12] [13] [14] [15] .

Regarding level of concern, in 2013, the CDC prioritized bacterial concerns for the first time as "Urgent, Serious, and Concerning" [12] . 

Combating these emerging microbial threats necessitates strict adherence to the principles of infection control as delineated by the CDC [1, 16, 17] . Performing disinfection of environmental surfaces with an EPA-registered disinfectant after every patient contact is an essential component of this process that will help reduce the impact of antimicrobial resistance.

The CDC recommends that DHCP use chemical disinfectants approved by the EPA and FDA to disinfect environmental surfaces and medical equipment [18] . However, if no registered or approved products are available for a specific pathogen or use situation, DHCP are advised to follow the specific guidance regarding unregistered or unapproved (e.g., off-label) uses for various chemical germicides established by the CDC [18] . For example, no antimicrobial products are registered for use specifically against certain emerging pathogens (e.g., Norwalk virus), potential terrorism agents (e.g., variola major or Yersinia pestis), or disease agents [19] .

Infection control includes basic principles and guidelines that are designed to prevent disease transmission. Standard Precautions encompasses a broad range of infection control practices designed to reduce the risk of disease transmission in any health-care setting. These guidelines established by the Centers for Disease Control and Prevention (CDC) in 1996 replaced the Universal Precautions that were created in the 1980s to protect against the disease transmission of blood-borne pathogens. Standard Precautions guidelines are based on risk assessment and should be the foundation of infection control standards for all patient care [10] . They are designed to protect health-care personnel from infection and prevent cross-infection among patients from pathogens that can be spread by blood and any other body fluid [1] . Table 12 .3 provides a list of the recommended CDC Standard Precautions in the dental setting [10] . Essential components of Standard Precautions include proper cleaning, management, and disinfection of all environmental surfaces [10] .

Overall, the majority of dental practitioners accept and practice Standard Precautions. Because of this high degree of compliance, the rate of disease transmission in the dental office in the past three decades has been very low, but not inconsequential [1] . In 2007, a case of patient-to-patient transmission of hepatitis B virus infection associated with an oral surgery procedure was reported. Although the cause of infection could not be conclusively identified, this transmission was most likely linked to a contaminated surface and/or device [20, 21] . In 2014, a case of patient-to-patient transmission of hepatitis C virus was reported, again associated with oral surgery. While the exact mechanism, in this case, was not identified, contaminated surfaces may have played a role in the transmission [22] . In recent times, the increasing importance of contaminated surfaces that contribute to the spread of infectious diseases and the emergence and propagation of antimicrobial resistance raises the importance of adherence to Standard Precautions. Among the most important lapses of fundamental infection control principles are the failure to perform hand hygiene and adequately disinfect environmental surfaces/devices [23] . Performing disinfection of environmental surfaces in the dental setting is an essential component of infection control guidelines as established by the CDC [1].

The management of clinical contact surfaces in the dental setting is accomplished by either the use of surface barriers or the process of cleaning and disinfecting surfaces that are not barrier-protected. While disinfection and application of surface barriers are both effective, some surfaces are easier to cover, while disinfection may be the best methodology with other surfaces. The use of barrier protection or chemical disinfection is largely a matter of practicality and personal choice. Effectively managing clinical contact surfaces in the dental settings uses a combination of both approaches to reduce contamination. Each has advantages and disadvantages as well as specific indications. Table 12 .4 provides a list of the advantages and disadvantages of surface barriers versus cleaning and disinfection of clinical contact environmental surfaces [24] .

The purpose of surface barriers is to prevent contamination of the surface or equipment and reduce the need to clean and disinfect that surface or equipment before reuse [5] . Barrier protection is the most efficient way to protect difficult-to-clean, Use of personal protective equipment (PPE) 3.

Respiratory hygiene/cough etiquette principles 4.

Sharps safety (engineering and work practice controls) 5.

Safe injection practices (i.e., aseptic technique for parenteral medications 6.

Sterile instruments and devices 7.

Clean and disinfect environmental surfaces Centers for Disease Control and Prevention (CDC). Standard Precautions, Updated June 18, 2018. Available at: https://www.cdc.gov/oralhealth/infectioncontrol/summary-infection-preventionpractices/standard-precautions.html electronic, and smaller surfaces. Surface barriers should be used on as many surfaces as possible, particularly on surfaces that are difficult to disinfect or access, and surfaces that are touched frequently by gloved hands during patient care and likely to become contaminated [1] . A variety of barrier materials are available, such as clear plastic wrap, bags, sheets, tubing, and plastic-backed paper. Any barrier material chosen to be used on clinical contact surfaces must be impervious to both moisture and fluid. Once properly affixed to the clinical contact surface, barriers are very effective in preventing both direct and indirect contamination [1] . Any barrier is considered a single-use disposable device and must be discarded after every patient encounter and replaced with a new barrier at the end of each patient contact. barriers in a dental treatment area. Barriers should never be used for more than one patient [1, 16, 17] . No surface disinfection is necessary if the barrier has remained intact throughout the entire procedure [1, 16, 17] . However, if a barrier has been breached (ripped, torn, fallen off) or the covered surface has evidence of contamination upon barrier removal, that surface needs to be cleaned and disinfected [1, 16, 17] . Barriers should be removed and discarded while the health-care personnel is 

A surface barrier cannot effectively cover many surfaces in the dental treatment area. Clinical contact surfaces that do not have a surface barrier, or become contaminated during removal of a barrier, should be cleaned and disinfected after every patient contact with the use of an EPA-registered hospital disinfectant [1] .

Earle H. Spaulding created an approach to disinfection and sterilization of patientcare items and equipment in health care. This classification system categorizes instruments and patient-care items that are intended for reuse as critical, semicritical, and noncritical based on the potential risk of infection posed to the patient from contamination on the device [26] . In 1991, the CDC proposed an additional category to Spaulding's classification system designated as "environmental surfaces", which further subdivided environmental surfaces into housekeeping surfaces and medical equipment surfaces [27] . Medical equipment surfaces are referred to in this text as clinical contact surfaces. Environmental surfaces are designated as noncritical because these surfaces generally do not come into direct contact with a patient or contact intact skin, and therefore carry the least risk of disease transmission [1] . Chemical disinfectants are categorized as high level, intermediate level, or low level based on the ability of the disinfectant to destroy or inactivate living organisms.

High-level disinfectants destroy all microorganisms, but not all bacterial spores.

Intermediate-level disinfectants destroy vegetative bacteria and the majority of fungi and viruses. Inactivates Mycobacterium tuberculosis. Does not necessarily kill bacterial spores. Low-level disinfectants inactivate vegetative bacteria, fungi, enveloped viruses (e.g., human immunodeficiency virus (HIV), and influenza viruses), and some nonenveloped viruses (e.g., adenoviruses) [25] . Figure 12 .5 lists the microbes inactivated by intermediate-and low-level disinfectants [28] 

Cleaning and disinfection of all clinical contact surfaces that are not covered with a surface barrier must be done between all patient contacts by using an EPA-registered hospital disinfectant. In 2003, the CDC broadened the list of agents acceptable for surface disinfection to include the use of a low-level disinfectant with an HIV/HBV claim on surfaces not visibly contaminated with blood [1] . However, an intermediatelevel disinfectant may be used on any clinical contact surface regardless of the presence or absence of blood.

It is important to note that an intermediate-level disinfectant is specifically indicated when the surface is visibly contaminated with blood, and a low-level disinfectant is not appropriate to be used on surfaces contaminated with blood [1] . There is little if any cost differential between low-and intermediate-level disinfectants, and [1] . Additionally, while low-level disinfectants may effectively inactivate blood-borne pathogens such as HIV and HBV, they are not effective against more resistant organisms that would be inactivated with a tuberculocidal product (an intermediate-level disinfectant) [1] . The use of a tuberculocidal agent that is effective against nonenveloped viruses offers a broader spectrum of antimicrobial activity, a property that is highly desirable for environmental surface disinfection in the dental office.

The EPA regulates liquid chemical disinfectants intended for use on clinical contact surfaces in the health-care setting [29] . Any other sterilants/disinfectants are regulated by the Food and Drug Administration (FDA) [30, 31] . Disinfectants intended for use on clinical contact surfaces (e.g., light handles, radiographic-ray heads, or drawer knobs) or housekeeping surfaces (e.g., floors, walls, or sinks) are regulated in interstate commerce by the Antimicrobials Division, Office of Pesticide Programs, EPA, under the authority of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) of 1947, as amended in 1996 [32] . Enforcing FIFRA, the EPA requires registration of any substance or mixture of substances intended to prevent, destroy, repel, or mitigate any pest, including microorganisms [32] . Furthermore, FIFRA explicitly requires users of products to follow the labeling directions on each product: all EPA-registered product labels states under the Directions for Use heading: "It is a violation of federal law to use this product inconsistent with its labeling." [28] The CDC 2003 Guidelines state that only EPA-registered chemical disinfectants should be used in the dental setting to disinfect clinical contact surfaces. Therefore, the use of unregistered products is not recommended, and because it violates FIFRA, the user may be subject to fines and/or sanctions. Household bleach is not EPA-registered for this purpose, and diluted bleach is not acceptable to use on clinical contact surfaces in the dental office. Additionally, the use of liquid chemical sterilants/high-level disinfectants (such as glutaraldehyde and related chemicals) is not recommended for disinfecting environmental surfaces [1] . Whatever product a clinician elects to use, they must comply with all federal and state regulations regarding disinfectants. Clinicians must be aware of and adhere to manufacturer's directions for precleaning, appropriate personal protective equipment (PPE), safe handling, proper storage, and disposal of any product regulated by either the EPA or FDA.

The CDC/FDA designates any EPA-registered hospital disinfectant without a tuberculocidal claim as a low-level disinfectant and any EPA-registered hospital disinfectant with a tuberculocidal claim as an intermediate-level disinfectant [28] . However, EPA registers environmental surface disinfectants based on the manufacturer's microbiological activity claims when registering its disinfectant and does not use the terms intermediate-level or low-level disinfectants as used in CDC guidelines [33] . In order for a product to be labeled as an EPA hospital disinfectant, the manufacturer must submit data regarding the safety and effectiveness of the product. Additionally, the product must pass the Association of Official Analytical Chemists (AOAC) effectiveness tests against three target organisms:

1. Salmonella choleraesuis for effectiveness against Gram-negative bacteria. 2. Staphylococcus aureus for effectiveness against Gram-positive bacteria. 3. Pseudomonas aeruginosa for effectiveness against a primarily nosocomial pathogen [1] .

The EPA allows manufacturers to test specifically against organisms of known concern in health-care settings (HIV, HBV, HCV, and herpes). Any agents satisfying AOAC tests for hospital disinfectant designation would also be effective against these relatively fragile organisms when the product is used as directed by the manufacturer.

Although tuberculosis is transmitted by airborne infective droplets and not transmitted by contaminated environmental surfaces, the ability to kill Mycobacterium tuberculosis is used as a benchmark to measure how effectively a disinfectant will kill microorganisms [34] . Tuberculosis is a very difficult organism to kill; only bacterial spores are more difficult to inactivate than Mycobacterium tuberculosis. Any chemical germicide with a tuberculocidal claim (Intermediate-level disinfectant) is considered capable of inactivating a broad spectrum of microorganisms of most concern in the dental setting, including less-resistant organisms such as blood-borne pathogens (e.g., hepatitis B and C viruses, HIV). More importantly, nonenveloped viruses such as coxsackievirus and rhinovirus (the cause of many upper respiratory infections), human papillomavirus (HPV, the cause of cervical and oropharyngeal cancer), and multiple species of fungi are inactivated by an intermediate-level disinfectant, but these organisms are not inactivated by low-level disinfectants [1, 15, 16] .

Although no perfect product for surface disinfection has been introduced to date, there is a large number of acceptable EPA-registered hospital disinfectants available for use in the dental setting. Table 12 .5 [24, 35] describes the properties of an ideal disinfectant. The essential components for effective surface disinfection are the selection of the appropriate product for the intended purpose and correct application of the product while adhering to the manufacturer's label instructions [35] . The product selected for surface disinfection should be effective against the most common causes of health-care-associated infections (HAIs). Check the disinfectant label to verify the product is EPA-registered as effective against the microorganisms that are most commonly linked to HAIs. The contact time (or kill time) for a chemical disinfectant is the length of time it must remain in contact with a microorganism to achieve complete inactivation. A short contact time, of approximately 1-2 min, is desirable to ensure the product has killed the microorganisms before the disinfectant dries on the surface, and before staff or patient retouch the treated surface. A surface must remain wet for the length of the required contact time. If a product dries too quickly, it will not achieve the required contact time to kill the microorganisms [35] .

The fundamental first step in the disinfection process is cleaning the surface. The success of the disinfection process is compromised if the surface is not adequately cleaned first [34] . Incomplete removal of dust, dirt, and organic matter will interfere with the effectiveness of the chemical disinfectant by protecting the pathogen from adequate exposure to the disinfectant or reducing the antimicrobial activity of the disinfectant [35] . Products that accomplish both cleaning and disinfection offer a more efficient approach. A consideration for the selection of a chemical disinfectant is the product's ability to penetrate and preclean surfaces contaminated with blood and other organic matter [36] . 

The one-step disinfectant contains a chemical formulation and/or detergent that allows for cleaning and disinfection with one single application, hence the terminology "One

Step". A one-step product is effective in most clinical applications, and precleaning of the contaminated surface would only be required when the surface is visibly contaminated with organic or inorganic matter. The chemical composition of some disinfectants prevents them from being good cleaners. The use of these agents would require precleaning followed by disinfection under all conditions. Consequently, these are referred to as "Two-Step" germicides [21] . As suggested by the name, with the two-step product, the surface must first be cleaned with a detergent, and once the surface is thoroughly cleaned, it can be disinfected [3] . A second spray/wipe with an EPA-registered liquid chemical germicide is applied to the surface in the second phase of the two-step process [1] . The two-step process is commonly referred to as spray-wipe-spray, or wipe-discard-wipe when using a disposable disinfectant wipe [5] .

The majority of disinfectants used in health-care settings are one-step products that clean and disinfect using the same product in one step rather than requiring two independent steps [35] . The most significant advantages of the one-step product are the application of a single disinfectant versus the use of two products saves considerable time and uses less product. The adverse effect that a disinfectant has on dental equipment such as chair upholstery, vinyl surfaces, etc., is an important consideration when choosing a product. Clinicians should check the manufacturer's label for surface compatibility of any chemical agent before application to the various surfaces in the dental office.

Many EPA-registered hospital disinfectants are now available as presoaked wipes. The use of disinfectant wipes is becoming more widespread in the health-care environment [37, 38] . These products offer a convenient option for use of disinfectants and have a number of advantages. First, the wipe significantly limits the indiscriminate application of any chemical agent. The chemical is only applied to the area that the wipe contacts. This decreases human contact and the amount of chemical introduced into the environment. Wipes are also easy to use and store. The ease of use of ready-to-use cleaning-disinfection products has the potential to increase cleaningdisinfection compliance when compared to products that require daily preparation of solutions [38] .

One drawback is that all staff must be educated to immediately close the lid on the wipe container. Leaving the next wipe exposed to air allows evaporation of the disinfectant liquid which may result in a reduction of the antimicrobial activity of the product [37] . Dental personnel who use the wipe for an insufficient amount of contact time, as stated on the manufacturer's label, may reduce the expected microbial decontamination of environmental surfaces and risk the spread of localized contamination over a wider area [37] .

When using liquid germicide in either a premixed formula spray bottle or concentrate intended for dilution, it is important to follow the manufacturer's label instructions for proper use. When using a one-step liquid cleaner disinfectant, the dental personnel should spray the surface with the disinfectant and wipe it with a disposable towel. If precleaning is required for visible contamination, the user would discard the towel and use a second spray to disinfect the surface [34] . Gauze sponges saturated with liquid germicide should not be stored in containers as this shortens the effectiveness of the solution [36] . Pump spray bottles, in most instances, are an appropriate method of applying liquid germicides, with the exception being the application of hypochlorite solutions. An advantage of a pump spray bottle is better penetration of the liquid germicide into crevices in the equipment where wipes may not effectively contact [36] .

There is a lack of research about the safety implications of using spray disinfectant by health-care personnel [38] . The potential exists for a variety of clinical manifestations to be experienced by people exposed to chemical germicides. Symptoms that can occur from the excessive spraying of a disinfectant may include respiratory problems such as sneezing or wheezing, allergies, ocular irritation, and headaches [36] . Regardless of the type of surface disinfectant used, appropriate PPE must be utilized to protect the dental personnel from contact with any chemical agent. 

There are many formulations of disinfectants and a product that contains a detergent has the obvious advantage of providing the clinician with a cleaner/disinfectant in one formulation. This reduces the number of items in the office inventory, is more convenient, and usually decreases cost. No two formulations of surface disinfectants are alike and they may vary greatly. Consequently, different chemical compositions afford different properties. Many disinfectants are used alone or in combinations (e.g., hydrogen peroxide and peracetic acid) in the health-care setting. These include alcohols, chlorine and chlorine compounds, formaldehyde, glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, iodophors, peracetic acid, phenolics, and quaternary ammonium compounds, see Table 12 .7 [42] . Commercial formulations based on these chemicals are considered unique products and must be registered with EPA or cleared by FDA [42] .

The FDI World Dental Federation has published Infection Control in Dental Practice guidelines adopted in 2009 urge all dental health-care professionals to adhere to the principles of Standard Precautions [9, 39] . The stated general measures direct the dental team to incorporate principles of cleaning and disinfecting environmental surfaces in the workplace to protect themselves and patients against transmissible infections. The references for these guidelines are from the CDC [1] and the World Health Organization which indicate that the principles for surface disinfection of environmental surfaces are almost universally accepted [40] . The manufacturing and registration of environmental surface disinfectants is regulated by the Environmental Protection Agency (EPA) in the United States and by Health Canada as disinfectant drugs under the Food and Drugs Act and Regulations in Canada [32, 41] . Both regulatory agencies have similar disinfectant registration processes which review a manufacturer's test submissions of efficacy and safety data prior to approving their products and issuing an EPA registration number or a Health Canada drug identification number (DIN) for use and distribution in the respective countries [41] .

Since 1998, with legislative revisions ongoing, the European Chemical Agency (ECHA), an agent of the European Union (EU), has been the regulatory authority for biocidal products such as household pesticides or disinfectants available on the European market. The current Directive establishes an approval procedure for biocides (disinfectants) and requires manufacturers, importers, or downstream users of substances or mixtures to: classify, label, and package hazardous chemicals appropriately before placing them on the European market [42] . The Health and Safety Executive (HSE) provides details of biocidal products authorized by the UK [43] . 

Disinfection of noncritical environmental surfaces in the dental setting is an essential component of infection control guidelines. All clinical contact surfaces should be covered with a barrier or disinfected according to CDC recommendations [1] . Proper chemical disinfection can reduce the number of pathogens present in the dental environment and thereby reduce potential risk of infection to patients and dental health-care personnel. 

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