by Leslie Canham, CDA, RDA

Six common areas of cross-contamination in an orthodontic practice

As new patients join your practice, the welcoming process should include a statement about your concern for patient safety through proper sterilization and infection-control techniques as well as strict adherence to OSHA regulations. But today’s orthodontic practices are often busy, and staff members need to work at top speed to perform efficiently and stay on schedule. Sometimes, in the rush to stay on time, they can forget to perform some basic infection-control protocols. Other times, the protocols are followed but sabotaged by recontamination. Let’s look at some of the common areas of cross-contamination and how to eliminate them.

Leslie Canham, CDA, RDA

Hand Hygiene

Hand hygiene is defined as any method that removes or destroys microorganisms on hands. It is well-documented that the most important measure for preventing the spread of pathogens is effective handwashing.1 Effective handwashing includes vigorously rubbing together all surfaces of lathered hands for at least 20 seconds, followed by rinsing under a stream of water. Handwashing suspends microorganisms and mechanically removes them by rinsing the hands with water. The fundamental principle of handwashing is removal, not killing. The amount of time spent washing hands is important to reduce the transmission of pathogens to your patients, inanimate objects, and other frequently touched surfaces.

Drying hands is important, too, because wet hands can transfer pathogens much more readily than dry hands or unwashed hands. The residual moisture determines the level of bacterial and viral transfer following handwashing. Careful hand drying is critical to preventing bacterial transfer to skin, food, and environmental surfaces. Also, be certain that hands are dry before donning gloves to reduce the chances of developing skin irritation.

If the hands are not visibly soiled, an alcohol-based hand rub is adequate. Alcohol hand rubs are rapidly germicidal when applied to the skin and should include such antiseptics as chlorhexidine, quaternary ammonium compounds, octenidine, or triclosan to achieve persistent activity. Some products marketed to the public as antimicrobial hand sanitizers are not effective in reducing bacterial counts on hands. For alcohol-based hand sanitizers used in the health care professions, the FDA recommends a concentration of 60% to 95% ethanol or isopropanol—the concentration range of greatest germicidal efficacy.


Gloves are considered single-use, disposable items, which means they should be used on one patient and then discarded. Hand hygiene should be performed after removing and discarding gloves. Occasionally, in the middle of treatment, the orthodontist or assistant needs to leave the patient to get an instrument or device. If the gloves are not removed, cross contamination could occur when you touch a surface with your gloved hand.

Removing only one glove to open a drawer or cabinet creates another concern because handwashing would not take place. After retrieving the desired instrument, if the same previously worn glove is reworn, cross contamination occurs again.

Touching a keyboard or mouse with a gloved hand is a common cause of cross-contamination. Here, a black light shows the spreading of simulated spray contamination. One possible solution is to wear overgloves.

The three cross-contamination issues here are the following:

  • The gloved hand may contaminate the surface touched.
  • If only one glove is removed, the ungloved hand cannot be effectively washed, thus further spreading contamination.
  • The provider may have contaminated his or her hand by rewearing the dirty glove.

One solution is to have food handlers’ gloves or overgloves available. Another method would be to use a cotton pliers or a drawer tweezers to open the drawer and grasp the needed item. Salad tongs or forceps can be used as well. As always, be sure to disinfect between patients.

These solutions help to avoid the time-consuming process of removing both gloves, performing hand hygiene, and regloving. If you do need to unglove and leave the patient, remember that you must discard the gloves and perform hand hygiene.

Street Clothes Versus Clinical Jackets

Clothing worn by the orthodontic team is an important area of cross contamination. A clinical jacket protects the orthodontist’s or assistant’s street clothing and skin from the patient’s oral materials generated during patient treatment. A visible spray is created during the use of dental instruments such as handpieces, ultrasonic scalers, and air-water syringes. This spray travels only a short distance and settles quickly, landing on either the floor, the nearby operatory surfaces, the dental health care personnel providing care, or the patient. OSHA mandates that protective clothing such as gowns, clinic jackets, or similar outer garments shall be worn in occupational exposure situations. General work clothes such as uniforms, scrubs, pants, and shirts are not intended to protect against a hazard, nor are they considered personal protective equipment.

Masks, Face Shields, and Protective Eyewear

OSHA requires dental health care providers (DHCPs) to wear masks and face shields or protective eyewear to protect the skin and the mucous membranes of the eyes, nose, and mouth from exposure to spray generated during a dental procedure. This spray may land on and contaminate masks and protective eyewear but not be visible. To prevent cross-contamination, you must disinfect the contaminated eyewear after each patient and be careful to avoid touching the contaminated eyewear with your bare hand.

A surgical mask protects the patient against microorganisms generated by the wearer with greater than 95% bacterial filtration efficiency, and also protects the DHCP from large-particle droplet spatter that might contain blood-borne pathogens or other infectious microorganisms. The mask’s outer surface can become contaminated with infectious droplets from spray of oral fluids or from touching the mask with contaminated fingers. Also, when a mask becomes wet from exhaled moist air, the resistance to airflow through the mask increases, causing more airflow to pass around the edges of the mask. If the mask becomes wet, it should be changed between patients or even during patient treatment, when possible.2

As shown by a black light, a surgical mask’s outer surface can become contaminated with infectious droplets from spray of oral fluids or from touching the mask with contaminated fingers. Wet masks should be changed.

Environmental Surfaces

Environmental surfaces include surfaces or equipment that do not contact patients directly but can become contaminated during patient treatment. This occurs as a result of spray generated during treatment, contact with contaminated instruments or devices, or when a member of the orthodontic team touches the surfaces with contaminated gloves. These surfaces can serve as reservoirs of microbial contamination. Transfer of microorganisms from contaminated environmental surfaces to patients occurs primarily through DHCP hand contact. When you touch these surfaces, microbial agents can be transferred to instruments; other environmental surfaces; or to the nose, mouth, or eyes of workers or patients.

Environmental surfaces are divided into clinical contact surfaces and housekeeping surfaces. Clinical contact surfaces are surfaces that come in contact with sprays, spatters, contaminated instruments, and your gloved hand. These include:

  • dental light handles;
  • chair switches;
  • dental radiograph equipment;
  • chairside computer keyboards;
  • reusable containers of dental materials;
  • drawer handles;
  • faucet handles;
  • countertops;
  • pens;
  • telephones;
  • doorknobs; and
  • contaminated instruments or devices.

An effective way to protect some surfaces is to use barriers. Barriers can be clear plastic wrap, bags, sheets, tubing, and plastic-backed paper or other materials impervious to moisture. Because barriers can become contaminated, they should be removed and discarded after each patient while you are still gloved. After you remove the barrier, if the surface becomes soiled, then it must be cleaned and disinfected. Otherwise, after removing gloves and performing hand hygiene, you should place clean barriers on these surfaces before the next patient.

Clinical contact surfaces that are not barrier-protected must be disinfected between patients. There are a number of surface disinfectants to choose from. The CDC Guidelines state that an EPA-registered disinfectant with a minimum kill claim of HBV and HIV should be used on clinical contact surfaces. When the surface is visibly contaminated with blood or other potentially infectious material, an intermediate-level disinfectant (with a tuberculocidal kill claim) should be used.

There are two steps to proper surface disinfection: First, you must clean the surface; and second, you must disinfect the surface. Always follow the manufacturer’s directions for correct use of the product. When using spray disinfectants, the system of “spray-wipe-spray” means spray the surface to moisten, then wipe up to remove any debris. Once the surface is clean, spray the surface again and allow the product to remain on the surface for the recommended contact time. When using premoistened wipes, the manufacturer’s directions indicate a system of “wipe-discard-wipe,” which means wipe the surface to remove any debris, discard the contaminated wipe, and then use a fresh wipe to disinfect the surface for the recommended contact time. While it may seem that you use twice as many wipes when you follow the manufacturer’s directions, you may not achieve disinfection by using only one wipe. Another issue to address is placing disinfectant solutions in a container with 4×4 gauze for use on dental equipment. This is not listed on the manufacturer’s label as proper use of the product, primarily because the cotton fibers contained in the gauze may shorten the effectiveness of some disinfecting agents when they are stored together in containers. If gauze is used to apply disinfectant to surfaces, it should be saturated with the disinfecting agent at the time of use.

Examples of housekeeping surfaces include floors, walls, and sinks. Housekeeping surfaces pose little risk for disease transmission in dental health care settings. The majority of housekeeping surfaces need to be cleaned only with a detergent and water or an EPA-registered hospital disinfectant/detergent, depending on the nature of the surface and the type and degree of contamination.

Instruments and Other Patient Care Items

To determine if you are processing instruments properly, ask yourself three questions:

  • Would I feel comfortable putting this instrument in my mouth?
  • Have I sterilized this item according to the CDC guidelines?
  • Is there any event that might have caused this item to become contaminated after it was sterilized?

Here are four common pitfalls to be aware of in instrument reprocessing:

• Cleaning

Ultrasonic cleaners are an efficient way to remove debris from instruments. Use ultrasonic solutions that are specifically designed for ultrasonic cleaner use. Other products such as disinfectants can “fix” blood and debris onto the instrument. Be sure to use the appropriate baskets or cassettes to suspend the instruments in the ultrasonic solution. While bundling instruments together with a hair tie will keep sets of instruments organized, it defeats the cleaning process by preventing the instruments from being exposed on all sides to the action of the bubbles and solution. Be sure to close the lid of the ultrasonic tank when in use to prevent contaminated solution from being aerosolized.

• Packaging

Make sure instruments are rinsed and dried thoroughly prior to packaging. The packaging or wrap should be designed for the type of sterilization process being used. In orthodontic practices, most of the instruments fall into the category of “semicritical instruments,” those that touch mucous membranes but will not touch bone or penetrate soft tissue. Semicritical instruments that are sterilized unwrapped on a tray or in a container system should be used immediately or within a short time. When sterile items are open to the air, they will eventually become contaminated. Even temporary storage of unwrapped semicritical instruments should be discouraged because it permits exposure to dust, airborne organisms, and other unnecessary contamination before use on a patient.

• Sterilizing

Load the sterilizer according to the manufacturer’s instructions. Do not overload it, since too many instruments in the chamber can cause the cycle to fail. Use the full recommended cycle times for wrapped instruments. Allow packages to cool down and dry before removing them from the sterilizer.

Cross-contamination can occur to instruments when autoclave bags are handled when they are still wet. Wet bags may wick (draw in) bacteria from hands, dust, and contaminates from surfaces. Wet bags can also puncture more easily, which compromises the sterility of the instruments.

Use chemical indicators to distinguish processed and unprocessed instruments. Test each sterilizer weekly, and maintain results as required by state and federal regulations. Biological indicators commonly known as spore tests are the most accepted method for monitoring the sterilization process.

• Storing

Store instruments in a clean, dry environment to maintain the integrity of the package. Clean supplies and instruments should be stored in closed cabinets. Dental supplies and instruments should not be stored under sinks or in other locations where they might become wet or torn. If the packaging is compromised, instruments must be recleaned, repackaged, and sterilized again.

In today’s busy orthodontic practices, patients expect your infection-control practices to protect them from diseases. You must meet their concern for safety with proper sterilization and infection-control techniques as well as strict adherence to OSHA regulations. With a little extra attention to the daily routine of infection control, everyone can eliminate cross-contamination.

Leslie Canham, CDA, RDA, is a dental speaker and consultant specializing in infection control and OSHA compliance. She is the founder of Leslie Seminars, which provides in-office training, mock inspections, consulting, and online seminars to help the dental team navigate state and federal regulations. She is recognized as a provider of continuing education and is authorized by the Department of Labor as an OSHA Outreach Trainer in General Industry Standards. She can be reached through her Web site, For a complimentary OSHA training checklist, please send an e-mail to


  1. OPRP-General Information on Hand Hygiene.” Centers for Disease Control and Prevention Available at: Accessed March 20, 2007.
  2. Kohn WG, Collins AS, Cleveland JC, Harte JA, Eklund KJ, and Malvitz DM. Guidelines for Infection Control In Dental Health-Care Settings – 2003. Available Accessed March 14, 2007


Bird DL, Robinson DS. Modern Dental Assisting. 8th ed. St. Louis: Elseivier Saunders, 2005.

Boyce JM and Pittet D. Guideline for Hand Hygiene in Health-Care Setting. Available at: Accessed March 14, 2007.

Larson E. Hygiene of the skin: When is clean too clean? Available at: Accessed March 14, 2007.

Molinari JA, Cottone JA, Terezhalmy GT, eds. Practical Infection Control In Dentistry, 2nd ed. Philadelphia: Williams & Wilkins, 1996:195.