1. Principles and Techniques of Disinfection
Chapter 20
Principles and Techniques of Disinfection

2. Introduction
During patient treatment, surfaces of equipment and treatment rooms are likely to become contaminated with saliva or by aerosol containing blood, saliva, or both.
Laboratory studies have shown that microorganisms may survive on environmental surfaces for varying periods.
Assume that if a surface has had contact with saliva, blood, or other potentially infectious materials, it contains live microorganisms.
What is one of the most difficult microorganisms to kill? (Mycobacterium tuberculosis)
The safest approach for avoiding contamination is to assume that if the surface has had contact with saliva, blood, or other potentially infectious material, live microorganisms are present.

3. Environmental Infection Control
The Centers for Disease Control and Prevention (CDC) Guidelines for Infection Control in Dental Health Care Settings 2003 divide environmental surfaces into clinical contact surfaces and housekeeping surfaces.
Housekeeping surfaces include floors, walls, and sinks
Because they have a much lower risk of disease transmission, cleaning and decontamination is not as rigorous as that for clinical areas and patient treatment items
Cleaning and decontaminating fabric used in carpet, drapes, and chairs is practically impossible without damaging the materials.
What is a logical alternative to disinfecting these challenging housekeeping surfaces? (Eliminating them from the clinical area)

4. Consider These When Cleaning and Disinfecting
Amount of direct patient contact
Type and frequency of hand contact
Potential amount of contamination by aerosol and spray
Other sources of microorganisms (e.g., dust, soil, and water)
Start cleaning and disinfecting the most contaminated areas first, then move toward the least contaminated surfaces.

5. Clinical Contact Surfaces
Can be directly contaminated either by spray or spatter generated during dental procedures or by contact with the dental professional’s gloved hands.
Current infection control guidelines of the Office Safety and Asepsis Procedures Research Foundation (OSAP) recommend that clinical surfaces be classified and maintained under three categories:
Touch
Transfer
Splash, spatter, and droplet
What are the two divisions of environmental surfaces, according to the 2003 CDC guidelines? (Clinical contact surfaces and housekeeping surfaces)

6. Clinical Contact Surfaces
Touch surfaces are directly touched and contaminated during treatment procedures.
Include handles of dental lights, controls of dental units, chair switches, chairside computers, pens, telephones, containers of dental materials, and drawer handles
Transfer surfaces are not directly touched but often are touched with contaminated instruments.
Include instrument trays and handpiece holders
Splash, spatter, and droplet surfaces do not actually come into contact with the members of the dental team or the contaminated instruments or supplies.
Countertops are a major example
Of these three categories, which area should be cleaned and disinfected first? (Touch surfaces should be cleaned first.)
Touch surfaces are directly touched and contaminated during treatment; they should be barrier-protected or disinfected between patients.
Transfer surfaces are not directly touched but often are touched by contaminated instruments.
Splash, spatter, and droplet surfaces do not come into direct contact with members of the dental team or contaminated instruments; they should be cleaned at least once daily.

7. Clinical Surfaces This photo depicts the three categories:
A areas: Touch surfaces are directly touched and contaminated.
B areas: Transfer surfaces are not directly touched but may be touched with contaminated instruments.
C areas: Splash, spatter, and droplet surfaces do not actually come into contact with contaminated instruments or supplies.

8. Surface Contamination
There are two methods of dealing with surface contamination:
Surface barriers
Precleaning and disinfecting surfaces between patients
Most dental offices and clinics use a combination of precleaning and disinfecting surfaces along with the use of barriers.

9. Surface Barriers
Wide variety of surface barriers are available on the market today
Should be resistant to fluids to keep microorganisms in saliva, blood, or other liquids from soaking through to the surface underneath.
Some plastic bags are designed in the shape of items such as the dental chair, air-water syringe, hoses, pens, and light handles.
Plastic barrier tape is frequently used to protect smooth surfaces such as touch pads on equipment, electrical switches on chairs, and x-ray equipment
Aluminum foil can also be used because it is easily formed around any shape
When removing contaminated barriers, avoid touching a contaminated clean surface underneath the barrier.
If a clean surface is inadvertently touched, the surface should be cleaned and disinfected.

10. Water on a Fluid-Resistant Material
Fluid, blood, and saliva should bead up on a fluid-resistant barrier.
It should look like a freshly waxed car on a rainy day.
Courtesy Crosstex, Hauppauge, NY.

11. Protective Barriers This picture shows protective barriers.
Surfaces touched during patient care should be covered with protective barriers.
If not protected, they must be cleaned and disinfected at the end of the procedure.
As you can see in this photo, barriers can be purchased in many shapes and sizes.
This variation helps ease application and removal and ensures a proper fit.
Well-fitting barriers reduce contamination of surfaces underneath the barriers.

12. Rolls of Plastic Tubing
This picture shows rolls of plastic tubing that can be cut to the desired length.
Barriers can be dispensed in convenient boxes for easy access in treatment areas.
Courtesy Certol, Commerce City, CO.

13. Courtesy Certol, Commerce City, CO.
Tube Socks
Because cords can be a variety of lengths and thicknesses, tube socks are convenient to cut to a custom length to provide barrier protection for difficult-to-clean areas.
Courtesy Certol, Commerce City, CO.

14. Single-Use (Disposable) Items
Used on only one patient and then discarded, so they help reduce the chance for patient-to-patient contamination.
Single-use items are often made of plastic or less expensive metals, and they are not intended to withstand cleaning, disinfection, or sterilization.
Never process (clean, disinfect/sterilize) single-use items for use on another patient
These items are meant to be used for one patient and then discarded. There are disposable prophy angles, saliva ejector tips, and HVE tips.

15. Single-Use (Disposable) Items
In most areas, contaminated disposable items that are not sharps and are not soaked or caked with blood may be discarded with the regular office trash.
There is no need to discard these items in a medical waste or biohazard container.
State and local regulations may vary, so always consult the regulatory agency for your area.
As the name suggests, single-use items should be used for one patient only.

16. Precleaning and Disinfection
Although no cases of cross-infection have been linked to dental treatment room surfaces, cleaning and disinfection of these surfaces are important components of an effective infection control program.
In addition, the OSHA Bloodborne Pathogens Standard requires that contaminated work surfaces be disinfected between patient visits.
What does OSHA stand for? (Occupational Safety and Health Administration)
Refer students to Procedure 20-2 (p. 329) for further information on cleaning and disinfecting a treatment room.

17. Precleaning Precleaning means to clean before disinfecting
All contaminated surfaces must be precleaned before they can be disinfected.
Even if there is no visible blood on a surface, it must be precleaned because even a thin layer of saliva on the surface can decrease the effectiveness of the disinfectant
Precleaning reduces the number of microbes and removes blood and saliva (also called bioburden)
Even though no cases of cross-infection have been linked to surfaces in dental treatment rooms, the OSHA standard for bloodborne pathogens requires that contaminated work surfaces be disinfected between patient visits.
Precleaning is cleaning before disinfection: if a surface is not clean, it cannot be disinfected.
Regular soap and water can be used for precleaning.

18. Precleaning
These techniques are most effective when used on contaminated surfaces that are smooth and easily accessible for cleaning.
Always wear utility gloves, mask, protective eyewear, and protective clothing when precleaning and disinfecting.
Surfaces that are irregular or textured are difficult or impossible to clean, thereby making them difficult to disinfect as well (use barriers for these surfaces).
Regular soap and water may be used for precleaning, but it is more efficient to select a disinfectant that can be used to clean as well as disinfect.
If barriers are not used, or a combination of barriers and disinfecting is used to maintain surfaces, the surfaces should be cleaned and disinfected using an EPA-registered hospital disinfectant with HIV and HBV claims.

19. Approaches to Precleaning and Disinfection
Spray-wipe-spray: using a liquid disinfectant/cleaner
Wipe-discard-wipe: using a disinfectant towelette
Disinfectant is used for both steps.
Using a disinfectant for the precleaning step starts the killing process early and reduces the chances of ­spreading the contamination to adjacent surfaces.
If it is difficult to remove all of the bioburden from a given surface, then consider protecting it with a ­surface cover during future use.

20. Disinfection
Intended to kill disease-producing microorganisms that remain on the surface after precleaning.
Spores are not killed during disinfecting procedures.
Do not confuse disinfection with sterilization.
Sterilization is a process in which all forms of life are destroyed.
What is autoclave sterilization? (In autoclave sterilization, heat, pressure, and steam kill all forms of life.)

21. Characteristics of Disinfectants
Four general types of antimicrobial chemicals:
Antibiotics: kills microorganisms in or on the body
Antiseptics: kills microorganisms on the skin
Disinfectants: kills microorganism on environmental/inanimate surfaces
Sterilants: kills all microorganisms including endospores on inanimate objects

22. Disinfectants
Disinfectants are chemicals that destroy or inactivate most species of pathogenic (disease-causing) microorganisms.
In dentistry, only those products that are EPA-registered hospital disinfectants with tuberculocidal (kills the tuberculosis bacteria) claims should be used to disinfect dental treatment areas.
Mycobacterium tuberculosis is highly resistant to disinfectants, and if a disinfectant will inactivate M. tuberculosis it will most certainly inactivate the less resistant microbial families (e.g., bacteria, viruses, and most fungi) on the treated surface.
Disinfectants are only effective if you follow the manufacturer’s guidelines for contact time.
Contact time is the amount of time the product must remain on the surface to destroy microorganisms.
Sporicidal means that product kills spores.
Virucidal means that a product kills some viruses.
Fungicidal means that a product kills fungi.

23. Categories of Disinfecting/Sterilizing Chemicals
Sterilant/High-level disinfectant: kills all or most microorganisms on submerged, inanimate, heat- sensitive objects
Intermediate-level disinfectant: kills vegetative bacteria, most fungi, viruses, and Mycobacterium tuberculosis var. bovis
Low-level disinfectant: kills most vegetative bacteria, some fungi, and some viruses (hospital level disinfectant)

24. Ideal Surface Disinfectant
An ideal surface disinfectant would:
Rapidly kill a broad spectrum of bacteria
Have residual activity and minimal toxicity
Not damage the surfaces to be treated
Be odorless and inexpensive
Work on surfaces with remaining bioburden
Be simple to use
NO single disinfectant product on the market today meets all these criteria.
When selecting a surface disinfectant, you must carefully consider the advantages and disadvantages of various products.
Often the manufacturers of dental equipment will recommend the type of surface disinfectant that is most appropriate for their dental chairs and units.
Disinfectant choice depends upon the type of equipment used in the office, plus any other criteria the staff would like to apply, such as a product that does not require daily mixing.

25. Disinfectant Precautions
Follow the manufacturers’ recommendations for:
Mixing and diluting
Application technique
Shelf life
Activated use life
All safety warnings
Following these recommendations ensures that the product will work as it was meant to work.
See Table 20-3 for information about disinfectant references (pp ).

26. EPA-Registered Surface Disinfectants for Dentistry
This chart is very helpful in determining which of the EPA-registered surface disinfectants will work best for a specific set of office criteria.
Note the contact time and the advantages and disadvantages of each product.

27. Iodophors
EPA-registered intermediate-level hospital disinfectants with tuberculocidal action.
Because iodophors contain iodine, they may corrode or discolor certain metals and may temporarily cause reddish or yellow stains on clothing and other surfaces
These will stain dental chairs.

28. Synthetic Phenol Compounds
EPA-registered intermediate-level hospital disinfectants with broad-spectrum disinfecting action.
Phenols can be used on metal, glass, rubber, or plastic.
May also be used as a holding solution for instruments; however, phenols leave a residual film on treated surfaces. Synthetic phenol compound is prepared daily.
Always check with the manufacturer of the impression material before using them.

29. Synthetic Phenol Surface Disinfectant
This iodophor comes in prepackaged individual doses for ease in daily preparation.
Typically the contents of the packet are placed in a spray container and water is added.
Courtesy Biotrol, Earth City, MO.

30. Sodium Hypochlorite
Sodium hypochlorite (household bleach) is a fast- acting, economical, and broad-spectrum intermediate-level disinfectant (1:100 dilution for surface decontamination).
Bleach solution is unstable, must be prepared daily, has a strong odor, and is corrosive to some metals, destructive to fabrics, and irritating to the eyes and skin; it may eventually cause plastic chair covers to crack.
In the past, both bleach and alcohol were routinely used in the disinfection process.
We now know they are not the best products to select.

31. Quaternary ammonium compounds
Quaternary ammonium compounds with alcohol
A intermediate level surface disinfectant
Quaternary ammonium compounds without alcohol
A low level surface disinfectant

32. Alcohol
Alcohols are not effective in the presence of blood and saliva.
Evaporate quickly and are damaging to certain materials such as plastics and vinyl.
Not recommended as a surface disinfectant by several agencies.
The American Dental Association (ADA), CDC, and the Office of Safety and Asepsis Procedures Research Foundation (OSAP) do not recommend alcohol as an environmental surface disinfectant.

33. Immersion Sterilants/Disinfectants
Some chemicals on the market can be used for sterilization or high- level disinfection
When used as sterilants, they destroy all microbial life, including bacterial endospores.
Depending on the type, time for sterilization can range from 6 hours to 30 hours.
At weaker dilutions or with shorter contact time, these chemicals provide high-level disinfection, which inactivates all microorganisms except endospores.
Most of these chemicals are toxic and can irritate the eyes, skin, and lungs.
PPE must always be worn when these chemicals are used.
Always keep the lids of containers closed to minimize the fumes.
They are to be used for immersion (soaking) of heat-sensitive instruments and should never be used as surface disinfectants.
If there are instruments that cannot withstand the heat of autoclaving and no disposable instruments are available, immersion disinfectants can be used to sterilize the instruments.

34. Covered Instrument Tray
Clear plastic instrument trays with lids are necessary to reduce fumes and evaporation.
Courtesy Zirc Company, Buffalo, MN.

35. Glutaraldehyde Immersion Disinfectant
Classified as a high-level disinfectant/sterilant; can also be used as a liquid sterilant when immersion time is greatly increased.
Useful for plastics and other items that cannot withstand heat sterilization.
Very toxic and should be handled carefully to avoid the fumes.
Glutaraldehyde-treated instruments should never be used on patients without first being thoroughly rinsed with water.
Prolonged contact of certain types of instruments with glutaraldehyde solutions can lead to discoloration and corrosion of the instruments’ surfaces and cutting edges.
Many states no longer allow glutaraldehyde to be used in the dental office or clinic unless proper ventilation is installed, and others suggest eliminating its use completely.

36. Chlorine Dioxide Immersion Disinfectant
Chlorine dioxide is an effective, rapid-acting environmental surface disinfectant (3 minutes) or chemical sterilant (6 hours).
Chlorine dioxide does not readily penetrate organic debris and must be used with a separate cleaner.
Chlorine dioxide must be prepared fresh daily, it must be used with good ventilation, and it is corrosive to aluminum containers.
It is important to maintain proper ventilation in a room in which immersion disinfectants are used.

37. Ortho-Phthalaldehyde Immersion Disinfectant (OPA)
Classified as a high-level disinfectant.
OPA is effective in achieving high-level disinfection within 12 minutes at room temperature.
More expensive than glutaraldehydes but may be a good alternative for individuals with a sensitivity to glutaraldehydes.
It has very little odor and does not require activation or mixing.
All immersion disinfectants have disadvantages. Products that work best for the dental office should be selected, bearing in mind the amount of contact time needed and the type of ventilation available.

38. Ortho-Phthalaldehyde Disadvantages
Costly
Can be used only half as long as most glutaraldehydes in dentistry
May stain skin and fabrics
Plastics turn a blue-green color where proteins have not been removed
Would require more than 30 hours to secure sterilization
It does not have a sterilization claim.

39. Evacuator System
High-volume evacuation reduces the risk of saliva escaping from patients’ mouths.
Regular cleanings help tubes and pipes flow easier.
Clean by flushing with detergent or water
Periodically clean the traps.
Should bleach be used on an evacuator system? (Never use a sodium hypochlorite [bleach] product because it may cause corrosion of the metal parts of the system.)
A safer approach is to use a disposable trap. These traps typically contain bits of organic tissue, fluo­ride gel, coagulated blood, and impression material, and may contain scrap amalgam that should be disposed of properly.
Be sure to always wear gloves.

40. Housekeeping Surfaces
No scientific evidence showing that housekeeping surfaces (e.g., floors, walls, and sinks) pose a risk for disease transmission in dental healthcare settings
Majority of housekeeping surfaces need to be cleaned only with a detergent and water or an EPA-registered hospital disinfectant/detergent.
However, used solutions of detergents or disinfectants— especially if prepared in dirty containers, stored for long periods of time, or prepared incorrectly—may be reservoirs for microorganisms.
Make fresh cleaning solution each day; discard any remaining solution and let the container dry to minimize bacterial contamination.
When cleaning, try to avoid producing mists and aerosols or dispersing dust in patient care areas.
To reduce aerosols, spray disinfectant directly into a paper towel.
Clean areas frequently to avoid dust buildup.

41. Carpeting and Cloth Furnishings
Carpeting is more difficult to clean than is nonporous hard- surface flooring, and it cannot be reliably disinfected, especially after contamination with blood and other body substances.
Studies have documented the presence of bacteria and fungi in carpeting.
Cloth furnishings pose similar contamination risks in areas where direct patient care is performed and where contaminated materials are handled.
CDC guideline: Avoid using carpeting and cloth-upholstered furnishings in dental operatories, laboratories, and instrument processing areas.
Any dental chair made of fabric should be covered with a large plastic barrier.

42. Spills of Blood and Body Substances
The majority of blood contamination in dentistry results from spatter and the use of rotary or ultrasonic instruments.
No scientific evidence shows that HIV, HBV, or HCV has been transmitted from a housekeeping surface.
OSHA requires that blood spills and other body fluids be removed and the surfaces disinfected.
CDC guideline: Clean spills of blood or other potentially infectious materials and decontaminate the surface with an EPA-registered hospital disinfectant with low-level to intermediate activity, depending on the size of the spill and the surface porosity.
Always wear gloves and other PPE when decontaminating areas of spills
What type of gloves should be worn in the management of blood spills? (Utility)
Reduce spatter by using suction constantly during the use of rotary or ultrasonic instruments.

43. Greener Infection Control
Protecting the environment has become an important part of our personal lives and in our homes.
That responsibility extends to the provision of dental care.
Many of the infection control products and procedures we must use to protect our patients and ourselves have a negative impact on the environment.
Many products are toxic to beneficial as well as non-beneficial plants and animals.

44. Greener Infection Control
By altering a process or a material, it is possible to minimize a potentially negative impact on the environment.
For example, using disinfectant wipes instead of spraying disinfectants could reduce the amount of chemicals in the air.
Going greener requires thoughtful planning, research, and experimentation.
Going green is a lot more complicated than many people realize.

45. Greener Infection Control
Paper
Digital patient records could have a significant impact on the amount of paper that is used.
Radiology
Digital radiology is rapidly becoming state-of-the- art.
Personal protective attire
Protective barriers present a challenge in the attempt to go greener; some are recyclable.
Surface barriers and precleaning/disinfection
Involves the use of chemicals and PPE.
We would like to minimize the environmental impact of our activities.