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How to clean, disinfect, and sterilize a dental operatory.

Products used must match the task at hand. Dental assistants are often responsible for preparing treatment rooms before and after each patient, by cleaning and disinfecting surfaces, and for instrument cleaning, disinfection and sterilization. Unless the appropriate product for the task is selected, the results can potentially be damaging to instruments and equipment and dangerous for both health care workers and their patients.

Since the release of the new CDC Guidelines for Infection Control in Dental Health Care Settings, there is a renewed emphasis on infection control products and procedures. It can be difficult to sort through the various products and their claims, make product selections, establish infection control protocols, and train staff to safely implement and maintain the appropriate use of products. Part of the confusion stems from the changes in regulatory approval and registration process (particularly related to the use of disinfectants and sterilants), the broad variability in marketing claims and inconsistency in terminology used to describe the product, its efficacy and intended use. A common misconception is that one chemical will serve all purposes. As a result chemical products may be used that are not intended for the surface or task at hand.

To determine which product to use, you must first assess what you plan to treat--is it a "patient care item" or an "environmental surface"?

Patient care items are categorized as critical, semicritical and noncritical.

a. Critical: These items penetrate or contact soft tissue, bone, bloodstream and normally sterile tissue. Examples include periodontal scalars, forceps, scalpels, and surgical burs.

b. Semicritical: These items typically contact mucous membranes and nonintact skin. Examples include such items as handpieces, mouth mirrors, reusable impression trays, and amalgam condensers.

c. Noncritical: These items come in contact with intact skin such as radiograph head, blood pressure cuff, or facebow.

Environmental Surfaces are divided into two categories: clinical contact and housekeeping.

a. Clinical Contact: These include surfaces in the treatment areas contaminated during patient care by bare hands, gloved hands, saliva, blood or other body fluids. Examples include light handles, switches, x-ray equipment, countertops, chairside computers, reusable containers, drawer handles, pens, telephones, doorknobs and tables.

b. Housekeeping: Surfaces such as floors, walls and sinks require regular removal of soil, dust, and debris.

Now that you have an understanding of the different surfaces, it is time to decide the next process. The new Guidelines include clear definitions of what products are suitable for infection control of these different surfaces.


Cleaning Patient Care Items

Until instruments are disinfected or sterilized, they should always be treated as if they are contaminated. Workers should wear appropriate Personal Protective Equipment (PPE), including heavy duty, puncture-resistant utility gloves to handle instruments. Because splashing often occurs, masks and protective eyewear (with side shields) or a face shield should always be worn.

Manual Cleaning: Scrubbing with a brush and a surfactant or detergent with water removes debris and contaminants. (The handscrubbing technique should only be used if the automated cleaner is out of order. Your dealer will provide you with a loaner cleaning unit if repairs will take longer than an in-office service call. If handscrubbing is necessary, using a submarine technique will eliminate splatter.) If critical and noncritical items cannot be cleaned immediately after use, they should be placed in a puncture-proof, covered container and soaked in a detergent, disinfectant/detergent or an enzymatic cleaner (holding solution) until the soil is dissolved and removed. High-level disinfectants/ sterilants are not appropriate for presoaking instruments.

Automated Cleaning: UItrasonic cleaners or washer-disinfecting units are safer and are recommended because they do not require presoaking or the manual scrubbing of instruments and therefore, minimize the exposure to blood and body fluids. A noncorrosive enzymatic cleaner used in an ultrasonic cleaning unit helps to break down any remaining bioburden. Always follow the manufacturer's instructions for selection and use of enzymatic detergents.

Reminder: Critical and semicritical items should be heat sterilized after cleaning.

Cleaning Environmental Surfaces

Clinical Contact: Even when a surface is barrier protected, (e.g., plastic wrap, bags, sheets, tubing, barrier film plastic-backed paper, etc.) it can be, and often is, contaminated either through direct contact by the patient or the dental professional or by spray or splatter generated during procedures. If not appropriately cleaned and decontaminated, these surfaces can contaminate hands, gloved hands, instruments, equipment and devices.

The recommended cleaning process begins with the removal of any barrier film from the surface with gloved hands. After removal and disposal of a barrier, visibly check for contamination. It is suggested the areas/items be wiped with a saturated intermediate level disinfectant cloth. This procedure protects against any small undetected break in the barrier.

Housekeeping: These surfaces can be cleaned by wiping or scrubbing with a detergent and water. If there is contamination with blood, saliva or other body fluids, surfaces must be disinfected with EPA registered disinfectant/detergent as required by Occupational Safety and Health Administration (OSHA) and recommended by the Centers for Disease Control (CDC). The selection of the product will depend on the surface and the level of contamination. Routine cleaning schedules should be set and if a spill occurs, it must be contained and cleaned up promptly to avoid contact by your patients or co-workers. Make sure your cleaning solutions are fresh and that your cleaning tools such as cloths, mop heads, buckets and brushes are disposable or are adequately cleaned, decontaminated and dried as necessary to minimize bacterial contamination. As with all cleaning procedures, appropriate PPE is required.


Disinfection is the killing of pathogenic agents. Choosing a disinfectant depends upon the nature of the item to be disinfected, the concentration of microorganisms present, the innate resistance of those microorganisms, the type and concentration of germicide, the duration and temperature of contact, and other factors specific to manufacturer's instructions. The term "hospital grade" is no longer allowed to describe disinfectants registered by the EPA (Environmental Protection Agency). The CDC has designated the terms High, Intermediate or Low level disinfectants based on the products' specific antimicrobial "kill factor," the baseline ability to destroy tuberculosis and other specific organisms.

Three levels of disinfection (High, Intermediate, and Low) are appropriate for "patient care items" that do not require sterilization and two levels (Intermediate and Low) for environmental surfaces. Again, the intended use of the patient care item will help determine the recommended level of disinfection.

High level disinfectants are required to destroy all microorganisms, including bacterial spores and must be proven to kill TB, HIV, and HBV once the items have been cleaned and heat sterilized, or cold sterilized at the appropriate temperature for the recommended amount of time. High-level disinfectants include chemicals such as glutaraldehyde, glutaraldehydes with phenol, hydrogen peroxide, hydrogen peroxide with peracetic acid, ortho-pthaldehyde. Appropriate PPE is essential when using these chemicals and should include chemical resistant utility gloves (not medical grade examination or surgical gloves), face shields, protective eyewear with side shields and splash-resistant garments.

Intermediate level disinfectants do not necessarily kill bacterial spores, but are tuberculocidal, with HBV and HIV kill claims. Examples of these EPA registered products include chlorine-based products, quaternary ammonium compounds with alcohols, phenolics, iodophors, and chlorine-based chemicals.

Low level disinfectants have HIV and HBV kill claims on the label. Examples of these EPA registered products include dual or synergized quaternary ammonium compounds, some phenolics, some iodophors, and citric acid.


Heat: After cleaning, critical and semicritical items should be prepared for sterilization. Heat steril ization is most commonly used in dental settings; however, steam and chemical vapor sterilization units are also used. High temperature methods include steam, dry heat and unsaturated chemical vapor while low temperature automated sterilization involves ethylene oxide (ETO) and plasma sterilization. (Steam, chemical vapor and dry heat are most often used in dental offices.) Prior to sterilization items are cleaned, dried and packaged in functional groups using a cassette system or medical grade sterilization wraps. All sterilization must be conducted in an FDA-approved sterilizer and operated according to manufacturer's instructions. Monitoring each cycle for efficacy is highly recommended, and weekly biological monitoring is necessary.

Liquid Sterilants used for "cold sterilization" are intended only for the reprocessing of heat-sensitive instruments and devices. If the critical or semicritical item is heat sensitive, it should be immersed in a liquid sterilant that has received FDA premarket approval. Manufacturer's instructions for the concentration, duration and temperature of immersion that is required must be followed along with PPE safety requirements.

Regulatory Agencies

Dental professionals should be aware of the regulations that govern the use of liquid chemical disinfectants and sterilants and should understand the relative roles played by the Environmental Protection Agency (EPA), the Food and Drug Administration (FDA), Occupational Safety and Health Administration (OSHA), and the Centers for Disease Control and Prevention (CDC). Both the EPA and the FDA regulate liquid chemical disinfectants. Each agency has a unique role in ensuring that the benefits of chemical usage for specific tasks are clear.

The EPA regulates disinfectants that are intended to prevent, destroy, repel or mitigate any pest (including microorganisms) and regulates the disinfectants that are intended for use on environmental surfaces. To receive EPA registration for a disinfectant that makes an antimicrobial claim, the manufacturer must provide proof of its efficacy (i.e., microbicidal activity, stability and toxicity). Once controlled by the EPA, the FDA now regulates liquid chemical sterilants and high level disinfectants and requires them to obtain a 510(k) premarket approval to market the products.


High Level

Glutaraldehyde is a dialdehyde that is slightly acidic in its natural state. In a buffered (pH balanced) alkaline solution, it is a highly effective microbicidal agent. Glutaraldehyde is corrosive to metal instruments and is not to be used as a holding solution prior to instrument cleaning and sterilization. It is widely used in the cold sterilization of dental items, such as suction hoses. Glutaraldehyde is usually a clear liquid that turns green when activated. It has a strong odor and is an irritant to the skin, eyes, and respiratory system. It can cause allergic reactions in some individuals. The chemical should be used in separate areas where there is control over ventilation and occupational exposure. Unused glutaraldehyde solution should be stored in tightly closed, properly labeled containers in a cool, secure, properly marked location. For disposal of solutions, consult with local and regional regulations.

Widely available from a number of manufacturers, glutaraldehyde is found in products with properties, e.g., buffered, potentiated, alkaline, acidic, etc. The percentage of concentration along with the temperature determines the time needed to achieve sterility. Glutaraldehydes are EPA registered as steriliant/disinfectant chemicals, effective at penetrating blood and bioburden. Most glutaraldehydes must be activated before use by adding an appropriate buffer. Activated solutions have an effective life of 14 to 30 days, depending on the product. Newer acidic potentiated (pH neutral) glutaraldehydes do not require activation. To measure appropriate strength of solutions, glutaraldehyde test strips are available. Manufacturers' instructions should be closely followed.

Slow acting, highly effective glutaraldehydes are not recommended for use on environmental surfaces. With glutaraldehyde as the active ingredient, products can contain other chemicals such as phenolic agents that alone are not rated for high-level disinfection. Hydrogen peroxide is a powerful oxidizing formulation that offers an alternative for high level disinfection and liquid sterilization. Some compounds use peracetic acid as a balancing agent. Hydrogen peroxide is virucidal, sporicidal, tuberculocidal, fungicidal, and bactericidal. Some find this type of product less irritating than glutaraldehydes; however, it can erode materials such as rubber, polyurethane, and polyethylene found in products such as mixing bowls, spatulas and some types of instruments. In addition, hydrogen peroxide can irritate skin and inhalation of vapors should be avoided.

Intermediate and Low Level

Alcohol-based products are low level surface disinfectants that must be used in conjunction with surface cleaners. When used for environmental surface disinfection, alcohol evaporates very rapidly leaving no residual kill capacity. It can damage adhesives, seals and certain plastics due to its drying effect. Alcohol-based disinfectants are not recommended for use in dental offices.

Synthetic phenolic compounds are EPA registered disinfectants with broad-spectrum disinfecting action including a tuberculocidal kill claim. If a surface has been thoroughly cleaned, phenols may be used for surface disinfection. Effective in the presence of detergents, they can be used on metal, glass, or rubber. Manufacturers of dental chairs caution against the use of phenols as they can damage or discolor upholstery. They can also erode plastic eyewear and face shields. Phenols leave a residual film on treated surfaces. Some diluted solutions must be prepared and discarded periodically according to their directions. Phenol-based compounds can irritate skin, eyes, and mucous membranes. Inhalation should be avoided.

Chlorine-based products are fast acting and economical intermediate level surface disinfectant. As an oxidizer, it has a strong odor and is corrosive to many metals. It is also destructive to fabrics and may cause plastic chair covers to fade and crack. Eye and skin irritation are drawbacks to using chlorine-based products. Only commercially available EPA-registered products are recommended in the CDC 2003 Guideline.

Intermediate or Low Level

Quaternary ammonium-based products are EPA registered intermediate or low level disinfectants with broad spectrum activity. Ideal for noncritical surfaces such as radiograph head or environmental surfaces such as floors, walls and tables. Quaternary ammonium compounds may contain added synthetic detergents for use as a one-step cleaner and disinfectant. In spray form or single use cloth wipes, these products are widely available from a number of manufacturers. The products may cause allergic or health problems if skin or mucous membranes are exposed to them.

Iodophors are EPA registered intermediate level disinfectants used for noncritical items as well as clinical contact of environmental surfaces. These have broad spectrum disinfecting action with residual biocidal activity and few reactions. Dilution and contact time are critical and product must be discarded daily. Iodophors can discolor countertops and equipment upholstery, and for this reason they are not routinely used in dental practice settings today.

With a greater understanding of the basic product types for the various sterilization and disinfection requirements in the dental office, dental health care workers will be better equipped to select and use the right products. By minimizing the risk of cross contamination, ultimately the dentist, staff and patients will all benefit.
Patient Care and Environmental Surface Disinfection and Sterilization

Care Items Activity Method Recommended

Critical & Destroys all High Steam, dry heat,
Semicritical microorganisms/ Temperature unsaturated
Heat tolerant bacterial spores chemical vapor

Critical & Destroys all Low Ethylene oxide,
Semicritical microorganisms/ Temperature plasma
Heat sensitive bacterial spores

Critical & Destroys all Immersion FDA Registered
Semicritical microorganisms/ Liquid chemical
Heat sensitive bacterial spores sterilants

Semicritical Destroys all Heat-Automated Washer-
Heat sensitive microorganisms Disinfector
 but limited
 bacterial spores

Semicritical Destroys all Immersion EPA Registered
Heat sensitive microorganisms Liquid chemical
 but limited sterilant/
 bacterial spores disinfectant

Noncritical Destroys Liquid contact EPA Registered
with visible vegetative "hospital"
blood bacteria, most disinfectant with
 fungi and tuberculocidal
 viruses-- activity.
 bovis, not
 capable of
 bacterial spores

Noncritical Destroys Liquid contact EPA Registered
without vegetative with no
visible bacteria, some tuberculocidal
blood fungi and activity. OSHA
 viruses. required label
 of HBV and HIV

Patient Environmental
Care Items Process Surfaces

Critical & Sterilization Not Applicable
Heat tolerant

Critical & Sterilization Not Applicable
Heat sensitive

Critical & Sterilization Not Applicable
Heat sensitive

Semicritical High Level Not Applicable
Heat sensitive Disinfection

Semicritical High Level Not Applicable
Heat sensitive Disinfection

Noncritical Intermediate Clinical contact
with visible Level surfaces; blood
blood Disinfection spills on

Noncritical Low Level Clinical contact
without Disinfection and housekeeping
visible surfaces

Dr. Hamann received his medical degree from Loma Linda University. He is currently the CEO and Medical Director of SmartPractice[R], a health care supply company. As an authority on rubber-based allergies and glove manufacturing, Dr. Hamann has developed novel latex-free polymers for use in medical gloves. His expertise in gloves, infection control and hand hygiene is highlighted by his contribution to the 2003 CDC dental infection control guidelines. Dr. Hamann is a/so committed to preventive dentistry and medicine, and improving patient communication. He is published in several peer-reviewed journals and speaks throughout the world on occupational allergies, infection control, and patient communication.
COPYRIGHT 2004 American Dental Assistants Association
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Copyright 2004, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Author:Hamann, Curtis P.
Publication:The Dental Assistant
Date:Nov 1, 2004
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