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Infection Control Instrument Management: Cleaning and Sterilization in the Dental Office Introduction The Centers for Disease Control and Prevention (CDC) estimates that approximately 46.5 million surgical procedures will be performed on ambulatory and inpatients in the U.S. each year.[1,2] Tens of millions additional surgical procedures will be performed in outpatient dental, podiatry, and other health care related facilities. During each and every one of these surgical procedures, there will be contact with a medical/dental device or surgical instrument with a patient’s sterile tissue or mucous membranes. If contaminated, the instruments/devices used during the surgery can introduce pathogens into those tissues, which can result in an infection, a risk inherent in all surgical procedures.[1] However, the risk of infection can be significantly reduced with adherence to recommended infection control practices that include proper cleaning and sterilization of instruments/devices used during the procedure.[1] Inadequate or improper sterilization not only poses a risk for the patient undergoing the procedure but also introduces an opportunity for person-to-person transmission and dissemination of pathogens throughout the health care facility.[1] Therefore, disinfection and sterilization are absolutely mandatory to ensure that medical, dental and surgical instruments do not serve as sources of transmission of infectious microorganisms.[1,3] Unfortunately, sterilization is often incomplete, and numerous outbreaks from improperly sterilized instruments/devices have been documented.[4-10] In the dental office, the potential for transmission of disease from contaminated dental instrumentation is well supported.[3,11,12] Several studies show a very worrisome, high degree of inconsistency in sterilization practices in dental offices.[13,14] Most notably, in 1996, a review of sterilization practices showed that 68 percent of dentists/dental offices surveyed believed they were sterilizing their instruments but did not use appropriate chemical sterilants or exposure times; and 49 percent of those surveyed did not challenge autoclaves with biological indicators.[13] In another investigation, biologic indicators were used to test the efficacy of sterilizers used in dental offices; 15 percent to 65 percent of the sterilizers were found to have positive spore tests.[14] Operator error, rather than mechanical malfunction, was shown to have caused 87 percent of sterilization failures.[15] Clearly, the results from these studies are a matter of concern for the dental profession. However, these studies were conducted in the late 1990s and early 2000s, before the widespread acceptance of standard precautions in dental practice. Fortunately, dentistry has developed definitive guidelines for infection control, which, if followed, can produce sterile instrumentation on a consistent basis.[1,3] In November 2008, CDC published an updated Guideline for Disinfection and Sterilization in Healthcare Facilities, which “presents a pragmatic approach to the judicious selection and proper use of disinfection and sterilization processes; the approach is based on well-designed studies assessing the efficacy (through laboratory investigations) and effectiveness (through clinical studies) of disinfection and sterilization procedures.”[1] The topic of instrument management in the dental office is of critical importance to the profession. In order to provide a comprehensive review, this article will address instrument classification, and handling and packaging of contaminated instruments, with emphasis on evidence-based recommendations contained in the new 2008 guideline.[1] The principles of sterilization in the dental office will be covered in a follow-up article. As dental hygienists are integral to infection control practices in the dental office, this review should be particularly relevant.
Categories of Patient-Care Items A classification for patient-care items and equipment was developed by Spaulding over 30 years ago, and because of its logical approach, it is still in use, with modification, today.16 Both CDC and the American Dental Association (ADA) utilize the Spaulding Classification and categorize dental instruments, devices and equipment, commonly referred to as patient-care items, based on the potential risk for infection associated with that particular instrument/device’s intended use. These instruments/devices fall into three categories: critical, semi-critical or noncritical.[1,3,17] A synopses of categories of patient-care items and examples of each in dentistry is presented in Table I.[1,3] Critical items present the most significant risk and include any instruments and/or devices that are used to penetrate soft tissue, contact bone, enter into or contact the bloodstream or other normally sterile tissues of the body/mouth.[1,3,17] Surgical instruments, periodontal scalers/curets, scalpel blades and surgical dental burs are considered critical items.[1,3,17] Because of the very high risk they impose, all critical items must be sterilized by heat. Semi-critical items do not penetrate soft tissue, contact bone or enter into or contact the bloodstream or other normally sterile tissue of the body/mouth, and they have a lower risk of transmission. The dental mouth mirror, amalgam condenser, reusable dental impression trays and dental handpieces are all considered semi-critical items. A semi-critical item should, at a minimum, be processed with high-level disinfection, but because the majority of semi-critical items in dentistry are heat-tolerant, they also should be heat sterilized. Please note that although dental handpieces are considered a semi-critical item, they should always be heat sterilized between uses and not high-level disinfected.[3,17] The updated 2008 CDC Guideline further states, “handpieces can be contaminated internally with patient material and should be heat sterilized after each patient. Handpieces that cannot be heat sterilized should not be used.”[1] This straightforward and unambiguous recommendation must be met in all practice settings and should be implemented immediately. The least risk is classified as noncritical. These patient-care items pose much lower risk of transmission of infection and contact only intact skin, which can serve as an effective barrier to most microorganisms.[1,3,17] Noncritical items include the X-ray head/cone, blood pressure cuff, stethoscope and facebow. In the majority of cases, cleaning, or if visibly soiled, cleaning followed by disinfection with an EPA-registered hospital disinfectant is adequate. However, should the item become visibly contaminated with blood, an EPA-registered hospital disinfectant with a tuberculocidal claim (i.e., intermediate-level disinfectant) should be used.1 Although cleaning or disinfection of noncritical patient-care items is essential, these processes can be difficult to perform and may damage the surface(s). Therefore, use of a disposable, impervious barrier on these surfaces might be preferred.[1,3]
Handling of Contaminated Patient-Care Items Dental instruments are designed to cut tissue and remove tooth structure and adherent calculus. By design, they contain sharp edges and points that can easily cause injury to anyone who handles them. Therefore, all contaminated patient-care items should be handled with care to minimize the risk of percutaneous injury. Instruments should be placed in a puncture-proof container at the point of use to prevent cuts, scrapes and punctures during transport to the instrument-processing area. When handling contaminated patient-care items, the dental staff must employ standard precautions.[3]
Instrument Processing If one compared instrument processing to an assembly line, the contaminated (dirty) instruments would be the raw material and the finished product would be clean, sterile dental instruments. All of this would be accomplished with the least amount of time and effort, and as safely as possible. The best way to accomplish this task is to develop an instrument processing area that is well-designed and conducive to accomplishing the multiple steps to achieve sterilization or high-level disinfection. Sterilization is a complex process requiring specialized equipment, adequate space and, most importantly, qualified personnel who are provided with ongoing training.[3] Monitoring on a routine basis for quality assurance must accompany this process.[3] Every member of the dental team must have a clear understanding of her/his role in the process, as well as a clear understanding of the fundamental techniques and procedures involved. Instrument processing, when performed properly, can be hard work. Proper cleaning, packaging, sterilizer loading procedures and sterilization or high-level disinfection methods must be followed—the same way every day for every instrument.[3] All dental staff and clinicians should clearly understand the principles of instrument processing and sterilization and their responsibilities for these processes in the dental office.[3]
Instrument Processing Area The flow and management of instruments throughout a dental office are important and are facilitated with a well-designed instrument processing area where all instruments/patient-care items should be processed. Such a design ensures safety and aids in quality control. The ideal instrument processing area should be divided into sections based on the following steps of instrument processing: • receiving/decontamination The flow of instruments should move in an organized, logical progression from “dirty/contaminated” to “clean.” The closer the central sterilization to the operatories, the less time and distance required in transporting contaminated instruments into the area.[3] In order to minimize potential contamination and facilitate cleaning/disinfection, counter surfaces should be as smooth and seamless as possible and constructed with water- and chemical-resistant, nonporous materials. There should be adequate spatial separation between the “dirty” and “clean”; dental staff who process instruments should be trained in work practices to prevent contamination of clean areas.[3] Walls or partitions that isolate the various sections to control instrument flow would be ideal; however, this may not be possible due to space or other restraints. In too many dental offices, the instrument processing area is crammed into a corner or closet. Adequate space must be allocated for instrument processing. If the space is insufficient for the volume of work anticipated and the items to be stored, significant compromise of the sterilization process may occur.
Receiving, Decontamination and Cleaning Contaminated instruments/devices, supplies and equipment should be transported to the instrument processing area as soon and as safely as possible. Upon arrival into the processing area, they should be sorted, decontaminated (removal of pathogenic microorganisms from the items so they are safe to handle, use or discard) and then cleaned. Cleaning, which is defined by CDC as “the removal of visible soil (e.g., organic and inorganic material) from objects and surfaces,” is absolutely essential.[1] Any debris, dried blood and/or tissue fragments, known as bioburden, must be completely removed. If cleaning is incomplete, sterilization/disinfection may be compromised, posing a risk to patients as well as the dental staff who handle them.[1,3,17] Cleaning, therefore, must precede all disinfection and sterilization processes. Cleaning can be achieved either by scrubbing with a surfactant, detergent and water, or by automation using an ultrasonic cleaner or washer-disinfector using chemical agents.[1,3,17] As soon as possible after cleaning, instruments should be rinsed with water to remove chemical or detergent residue that could potentially corrode or otherwise damage instrument surfaces.[1,3] During the receiving/decontamination/cleaning process, all instruments/devices should be considered contaminated, and standard precautions should be utilized to protect all personnel in the area. Splashing should be minimized during cleaning and rinsing.[1,3] All surfaces in the instrument processing area that have been exposed to contaminated items or splash/splatter should be disinfected using an EPA-registered surface disinfectant.[1,3] Cleaning should be performed by the most efficient and safest methodology. There is a multitude of cleaning methods and equipment available, and each must be evaluated in order for the practice to select the best fit. Considerations include: • Efficacy of the cleaning method, process and equipment Automation allows for greater efficiency and safety. Automated cleaning equipment, such as ultrasonic cleaners or washer-disinfectors, does not require presoaking or scrubbing of instruments.[1,3] Ultrasonic devices clean by cavitation and implosion of the liquid solution producing waves of acoustic energy that are propagated throughout the aqueous solutions that disrupt the bonds that hold particulate matter to surfaces. The end result is removal of debris/bioburden adherent on the instruments.[1,3] Contaminated instruments should be placed in a wire basket that is lowered into the solution chamber where the sonic action/ detergent removes the debris. To assure thorough cleaning, instruments should be completely submerged in the detergent solution in the chamber.[1,3] Hinged instruments should be opened fully to allow adequate contact with the detergent solution. Stacking of instruments in washers should be avoided; and complex instruments should be disassembled as much as possible.[1,3] Because ultrasonic cavitation is a completely mechanical process, physical contact of the staff with contaminated instruments is significantly reduced.[1,3] Staff are available to perform other duties and cleaning is more effective than when compared to manual cleaning. More advanced technology includes washer-disinfectors that use heated high-water flow rates and formulated detergents to automatically clean and disinfect patient-care items.[1,3] These automated devices greatly simplify the cleaning process by eliminating the need for presoaking, hand scrubbing, rinsing and drying.[1,3] Although more expensive at initial purchase, automated processes of washer-disinfectors are far more efficient and can increase productivity, improve cleaning effectiveness and decrease worker exposure to blood and body fluids.[1,3] The traditional method of manual cleaning (hand scrubbing) relies primarily on friction produced by rubbing/scrubbing the soiled area with a brush to remove debris. This process places dental workers in close proximity to contaminated instruments and is not the recommended method for routine instrument cleaning (Figure 1). Hand scrubbing should be used only when mechanical cleaning fails to remove debris. When hand scrubbing is performed, work-practice controls should be in place including using a long-handled brush to keep the scrubbing hand away from sharp ends. Wear heavy-duty, puncture-resistant utility gloves when handling or manually cleaning contaminated instruments and devices; and avoiding reaching into trays or containers holding sharp instruments that cannot be seen, such as ultrasonic chambers or sinks filled with soapy water in which sharp instruments have been placed. Other work-practice controls should include use of a strainer-type basket to hold instruments and forceps to remove them. Because splashing is likely to occur, a mask, protective eyewear or face shield, and gown or jacket should be worn.[1,2] The solutions in the ultrasonic chamber, because of their primary function, are rapidly contaminated. The chambers should be cleaned and the liquid disposed of on a frequent basis, daily at the minimum. Any surface or device/instrument that contacts the ultrasonic chamber liquid should be considered contaminated and should be disinfected or sterilized as indicated. Covers (lids) of the ultrasonic should be closed when running ultrasonic cleaners to minimize spatter and bioaerosol.
Preparation and Packaging Once cleaned, instruments need to be inspected for breakage/damage; assembled into sets or trays; and wrapped, packaged, or placed into container systems for sterilization.[1,3] Special considerations should be addressed at this time; for example, hinged instruments should be opened and unlocked for processing, and devices with concave surfaces should be positioned to facilitate drainage of water.[1,3] An internal chemical indicator should be placed in every package, and an external chemical indicator (chemical indicator tape) should be used when the internal indicator cannot be seen from outside the package.[1,3] Chemical indicators are convenient, inexpensive and indicate that the item has been exposed to the sterilization process. While they do indicate that the process has occurred, this is not an indicator of sterilization (biological monitoring confirms sterilization).[1,3] Chemical indicators should be placed on the outside of each instrument pack or kit; it is recommended that a chemical indicator also be placed on the inside of each pack to verify sterilant penetration. Chemical indicators are usually heat- or chemical-sensitive inks that change color when one or more of the three sterilization parameter (time, temperature or presence of steam) has been met. Any internal and/or external indicator that does not change color suggests inadequate processing, and that item should not be used and should be reprocessed.[1,3] Until recently, technological limitations in sterilization pouches enabled only single-parameter chemical indicators printed on either the inside and/or outside of the pouch. Although convenient, these “process” indicators react to only a single sterilization parameter: temperature. A new product has recently been introduced that confirms all three sterilization parameters with an internal/external multi-parameter steam indicator printed directly on the pouch (Figure 2). This new product eliminates the extra step of adding separate multi-parameter indicators to each pouch, thereby making the process more convenient, cost-effective and compliant with CDC Infection Control Guidelines for effective sterilization. Repetitive failures of a chemical indicator warrant investigation and may indicate a serious malfunction of the sterilization device employed. Packaging materials (e.g., wraps or container systems) must allow penetration of the sterilization agent and maintain sterility of the processed item after sterilization.[1,3] Materials for maintaining sterility of instruments during transport and storage include wrapped perforated instrument cassettes, peel pouches of plastic or paper and sterilization wraps.[1,3]
Conclusions 1. Patient-care items are classified by the Spaulding Classification as critical, semi-critical or noncritical based on the potential risk for infection associated with that particular instrument/device’s intended use.
References
Louis G. DePaola, DDS, MS, is a professor in the Department of Oncology and Diagnostic Sciences, Dental School, University of Maryland, Baltimore. He received his DDS in 1975, completed a master’s degree in oral biology, is a diplomate of the American Board of Oral Medicine and the American College of Dentists and has a certificate in prosthodontics. He is an international lecturer and executive director of Biosafety and Continuous Quality Improvement, Dental School, University of Maryland, Baltimore. Active in research, he has authored and co-authored of over 130 journal articles, book chapters and abstracts and serves as a consultant to the American Dental Association and numerous other professional groups and private industry. Jacquelyn L. Fried, RDH, MS, received her Bachelor of Arts in political science and her Certificate in Dental Hygiene from Ohio State University. She also holds a Master of Science in Dental Hygiene from Old Dominion University. She is associate professor and director of the Dental Hygiene Program in the Department of Health Promotion and Policy at the University of Maryland Dental School. She has been in dental hygiene education for almost 30 years. She has been involved with clinical, research, didactic and community activities related to tobacco. She currently serves as principal investigator for a tobacco training grant funded by the State of Maryland. An active member of the American Dental Hygienists’ Association, Fried is widely published and has authored numerous manuscripts and book chapters. She teaches both didactically and clinically and has received student awards for her teaching abilities. This article is sponsored by an educational grant from Crosstex International. |
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