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Microorganisms are everywhere. They are on clinicians and their patients, in the air and water, and on virtually all surfaces. Although the presence of microbes is inevitable, it is the responsibility of healthcare providers to prevent the transmission of microorganisms to and from their patients. Infection control measures, such as the use of personal protective equipment (PPE), standard precautions, and proper disinfection protocols, are implemented in order to prevent the spread of infection. Formalizing protocols and properly implementing these measures will provide the most reliable exposure prevention. On the other hand, improper implementation of infection control protocols can result in the reduced efficacy of associated materials or an increased risk of infection. One way to ensure the proper use of infection control materials and their protocols is to review each material's instructions for use. The instructions for use can be found on or within the packaging of all dental materials or within the material safety data sheets.
Infections occur when a pathogen enters the body, increases in number, and causes a reaction. According to the US Centers for Disease Control and Prevention (CDC),1 three factors are necessary for an infection to occur: a source, a susceptible person, and a method of transmission. The pathogen must leave the original host and be transmitted to a susceptible host, which most commonly occurs through exposure to coughing, sneezing, or bleeding. To help it survive during the transmission from the source to a susceptible person, the organism may have protective properties, including viral envelopes, spores, or metabolic features. Moreover, environmental factors may facilitate the transmission of pathogens, including humidity, temperature, and surface type. The pathogens may be delivered directly via inhalation and splashes or indirectly via contact with contaminated surfaces, people, or water. Once in contact with a susceptible host, the pathogen must evade the host's inherent defenses to replicate and result in a reaction within the body. It is the responsibility of the dental healthcare provider to disrupt this chain of events. This is accomplished through handwashing, the appropriate use of PPE, and the implementation of proper disinfection and sterilization protocols.
In the dental healthcare setting, dental healthcare workers and patients are exposed to disease-causing microorganisms that are present in blood, oral secretions, and aerosols. The CDC has formulated guidelines for infection control that are specific to dental practices.2 These guidelines include recommendations for hand hygiene, the use of PPE, and disinfection and sterilization procedures.
Contact with the hands remains the most common mode of pathogen transmission; therefore, it is essential that dental healthcare workers are intentional and mindful of hand hygiene. Hand hygiene is a general term that incorporates handwashing, the use of antiseptic hand wash and hand rub, and the performance of surgical hand asepsis.3 Handwashing involves the use of plain soap and water, and antiseptic handwashing refers to washing the hands with a soap that contains an antiseptic, such as triclosan, an iodophor, or chlorhexidine. Handwashing is accomplished by removing any visible soil from the hands with either tepid or cool water; washing the hands with plain or antiseptic soap for a minimum of 15 seconds, concentrating on the thumbs, fingertips, and between the fingers; and then thoroughly rinsing and drying the hands with a disposable towel prior to donning gloves. Alcohol-based hand rubs (ie, hand sanitizers) contain 60% to 95% ethanol or isopropanol. Hand sanitizer should be used to reduce the number of microorganisms when there is no visible soil on the hands. When the hands are visibly soiled, they should be washed with soap and water. Surgical hand asepsis refers to a handwashing protocol that is performed prior to a surgical procedure, using an antiseptic hand wash that has long-lasting antimicrobial activity.4
The most effective use of soaps and alcohol-based hand rubs will be achieved if these materials are used according to the specific recommendations provided by their manufacturers. It is recommended that practitioners read the instructions for use for all of the products that are present within the dental office, especially those that are employed in infection control protocols. The instructions for use will describe the indications for use, the appropriate amount of product that should be dispensed, and the suggested time that the material should remain in contact with the hands.
Personal Protective Equipment
To minimize the risk of exposure to pathogens, practitioners should employ PPE, including the proper use of protective eyewear, masks, and gloves. Protective eyewear or face shields should be selected to prevent exposure to mechanical irritants, certain wavelengths of light, splatter, and other potentially infectious materials. They should not only provide protection from a facial perspective but also prevent contamination from the sides and below the inferior border of the eyewear.5 Eyewear should be comfortable for the dental healthcare worker and easy to properly disinfect; provide proper protection per the CDC, the Occupational Safety and Health Administration, and the American National Standards Institute's eye protection standards (ie, ANSI Z87.1); and offer a high level of visibility. Active compliance by dental healthcare workers is essential to ensure that they and their patients are protected from potential exposure of their eyes to irritants. An inadequate number of studies exist to properly describe the prevalence of dental healthcare worker compliance with wearing protective eyewear, but some studies suggest that compliance is still a challenge and poses an unnecessary risk.6
Face masks are FDA-approved to protect the mucous membranes of the nose and mouth from contact with sprays, splatter, or aerosols that are contaminated with the patient's oral fluids. In addition, masks can reduce the spread of potential respiratory pathogens. Masks are single-use items (Figure 1) and should be worn during direct patient care, during laboratory work, and during operatory disinfection and instrument processing.
There are multiple performance levels of face masks, which are based on criteria that include the following7:
Fluid resistance. This refers to a mask's resistance to penetration by fluids. The higher the fluid resistance, the greater the protection that is offered by the mask.
Bacterial filtration efficiency. This is a measure of how efficiently a mask is able to filter bacteria, based on a pore size of 1 µm to 5 µm.
Submicron particle filtrations efficiency. This is a measure of a mask's ability to filter particles ranging from 0.1 µm to 1.0 µm that pass through it.
Differential pressure. This rating reflects the force required by clinicians to breathe through a mask. Its measurement is referred to as Delta P. A higher Delta P value is indicative of greater filtration but less breathability.
Flame spread. This is a measure of the flammability of a mask's material.
These criteria are used to determine the American Society for Testing and Materials (ASTM) mask levels. Dental healthcare workers should ensure that the ASTM level of the mask that is utilized in practice corresponds with the type of care that is being provided. The ASTM mask performance levels and recommended uses include the following:
Level 1: dental exams, operatory disinfection, impression taking, laboratory work
Level 2: endodontics, prophylaxis, sealant placement, scaling and root planing
Level 3: oral surgery, prosthodontics, implant surgery, surgical periodontal procedures, ultrasonic scaler use, operative procedures
Regardless of the situation, dental face masks should fit comfortably, offer the appropriate level of protection, and provide adequate breathability for the clinician.
Gloves provide the clinician with protection against the microorganisms in patients' mouths as well as on contaminated surfaces and instruments. In addition, gloves protect the patient from any microorganisms present on the clinician's hands. Hands should be properly cleaned and dried prior to donning gloves. Gloves should be inspected for holes and tears and immediately removed and replaced if a hole or tear is detected. Preventive measures should be taken to avoid damage to a glove's surface, including removing any jewelry and keeping fingernails short and rounded. Gloves are considered a single-use item and should be changed for each patient, when damaged, when heavily contaminated, and when entering or leaving the operatory. During operatory breakdown and instrument processing, puncture- and chemical-resistant utility gloves should be worn.
The type of PPE selected by clinicians will vary based on the level of precautions required by the procedure. When putting on PPE, individual items should be donned in the following order: (1) gown; (2) mask; (3) goggles, loupes, or face shield; and (4) gloves. Once the procedure is complete, PPE should be removed, or doffed, in the following order: (1) gloves; (2) goggles, loupes, or face shield; (3) gown; and (4) mask. Additional, more detailed instructions for donning and doffing PPE in a manner that limits the spread of contamination are available from the CDC.
The literature supports the use of surface dis-infectants to prevent the spread of micro-organisms on contaminated surfaces in health-care settings. Unfortunately, most disinfection practices are suboptimal, and it has been suggested that consistent training and monitoring should be exercised in the clinical setting.9 This includes the disinfection of working surfaces (eg, computer keyboards), surfaces that are regularly touched by many people (eg, door handles, sink faucets), and surfaces in treatment rooms. An appropriate disinfectant should be selected for each task, and surface disinfection should be carried out on a consistent basis. Compliance is improved when a cleaning and disinfection program is created that includes written policies and procedures outlining the specific disinfectants and cleaning products to be used, explaining the method of applying the products, and specifying the process for educating staff, monitoring cleaning practices, and providing feedback.8
There are a multitude of commercially avail-able surface disinfectants, and for any one selected, it is recommended that dental healthcare workers read the instructions for use and the manufacturer's recommendations for its indications and appropriate applications in the dental practice. Variation exists among surface disinfectants, specifically regarding the microorganisms that are targeted and the recommended contact time. To prevent the transmission of microorganisms in the clinical setting, it is crucial that surface disinfectants are used appropriately. Surface disinfecting should be carried out via a two-step process. The initial step is the physical removal of debris from a surface by wiping it clean. The second step involves wetting the surface with disinfectant and leaving it wet for the amount of time that is suggested by the manufacturer. Disinfection procedures using disinfectants that are sprayed onto a surface are best accomplished with the "spray-wipe-spray" technique. This technique involves first spraying disinfectant and wiping the surface clean with a disposable paper towel. Then, once all of the visible contaminants are removed and the surface has been wiped clean, disinfectant is sprayed onto the surface and allowed to sit for the period of time that is prescribed by the manufacturer. When disinfectant wipes are used, the "wipe-discard-wipe" technique should be employed, which involves using a disinfectant wipe to manually remove contaminants, followed by a second wipe to accomplish chemical disinfection.
Another consideration for the appropriate use of surface disinfectants involves their use on elastomeric impression materials. The improper use of surface disinfectants on impression materials may result in incomplete disinfection of the impression, distortion of the impression, or cross-contamination in the dental laboratory. It is critical to ensure that the type of disinfectant that is used on impression materials is compatible with the material to be disinfected.10 Disinfection recommendations for elastomeric impression materials can be found in the instructions for use of the chosen impression material.
Although the focus of this article is limited to hand hygiene, PPE, and disinfection protocols, the instructions for use for every commercially available dental material should be read and followed by dental healthcare workers before using the material. Improper selection or handling of a product may result in inadequate protection of patients and clinicians from microorganisms or incomplete disinfection of surfaces. This can lead to many negative outcomes, including but not limited to cross-contamination, infection, an outbreak of pathogenic microorganisms, lawsuits, and a poor reputation within the community. Dental healthcare workers are urged to use the appropriate PPE for procedures that are carried out in clinical, laboratory, and sterilization settings. Furthermore, dental practices and clinics are urged to create formalized, written protocols that include the areas to be disinfected regularly, which disinfectants should be used, a schedule, a maintenance log, and a system for providing feedback.
About the Authors
Pamela Maragliano-Muniz, DMD, BSDH
American Board of Prosthodontics
Inside Dental Hygiene
Michelle Strange, MSDH, RDH
Volunteer Registered Dental Hygienist
Our Lady of Mercy Outreach
Charleston, South Carolina
Trident Technical College
Charleston, South Carolina
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4. Centers for Disease Control and Prevention. Guidelines for infection control in dental health-care settings. MMWR. 2003;52(RR17);1-61.
5. Arsenault P, Tayebi A. Eye safety in dentistry and associated liability. J Mass Dent Soc. 2016;64(4):12-16.
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7. Centers for Disease Control and Prevention. NIOSH personal protective equipment information. Centers for Disease Control and Prevention web site. https://wwwn.cdc.gov/PPEInfo/Standards/Info/ASTMF210011(2018). Updated November 20, 2015. Accessed March 19, 2019.
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10. Soganci G, Cinar D, Caglar A, et al. 3D evaluation of the effect of disinfectants on dimensional accuracy of two elastomeric impression materials. Dent Mater J. 2018;37(4):675-684.