Chapter. 20 Principles and Techniques of Disinfection

Question 1

Introductions

Answer 1

During patient treatment, surfaces in
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

Question 2

Environmental Infection Control

Answer 2

The Centers for Disease Control and
Prevention (CDC) Guidelines for Infection
Control in Dental Healthcare 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 are not as rigorous as that
for clinical areas and patient treatment items

Question 3

Cleaning and Disinfecting
Considerations

Answer 3

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)

Question 4

Clinical Contact Surfaces.1

Answer 4

Can be directly contaminated either by spray or
spatter generated during dental procedures or
by contact with 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

Question 4

Clinical Contact Surfaces.2

Answer 4

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

Question 5

Surface Contamination

Answer 5

There are two methods of dealing with
surface contamination
 Surface barriers
 Precleaning and disinfecting surfaces
between patients

Question 5

Surface Barriers

Answer 5

Wide variety of surface barriers available 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 (e.g., 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

Question 6

Single-Use (Disposable) Items.1

Answer 6

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

Question 7

Single-Use (Disposable) Items.2

Answer 7

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

Question 8

Precleaning and Disinfection

Answer 8

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 Blood-Borne
Pathogens Standard requires that
contaminated work surfaces be
disinfected between patient visits

Question 9

Precleaning.1

Answer 9

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

Question 10

Precleaning.2

Answer 10

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 or to disinfect
 Regular soap and water may be used to
preclean, but it is more efficient to select a
disinfectant that can be used to clean as
well as disinfect

Question 11

Disinfection

Answer 11

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

Question 12

Disinfectants.1

Answer 12

Chemicals that are applied to inanimate
surfaces (e.g., countertops and dental
equipment)
 Antiseptics are antimicrobial agents that
are applied to living tissue
 Disinfectants and antiseptics should
never be used interchangeably because
tissue toxicity and damage to
equipment can result

Question 13

Disinfectants.2

Answer 13

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 inactivate the less resistant microbial
families (e.g., bacteria, viruses, and most

Question 14

Ideal Surface Disinfectant

Answer 14

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

Question 15

Disinfectant Precautions

Answer 15

Follow manufacturers’
recommendations for:
 Mixing and diluting
 Application technique
 Shelf life
 Activated use life
 All safety warnings

Question 15

Iodophors

Answer 15

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

Question 16

Synthetic Phenol Compounds

Answer 16

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

Question 17

Sodium Hypochlorite

Answer 17

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

Question 18

Alcohol

Answer 18

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

Question 19

Glutaraldehyde

Answer 19

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; 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

Question 19

Immersion Disinfectants

Answer 19

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, inactivating all microorganisms
except endospores
 Most of these chemicals are toxic and can
irritate the eyes, skin, and lungs
 PPE must be worn when these chemicals are use

Question 20

Chlorine Dioxide

Answer 20

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

Question 21

Ortho-Phthalaldehyde

Answer 21

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

Question 22

Ortho-Phthalaldehyde Disadvantages

Answer 22

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

Question 23

Evacuator System

Answer 23

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

Question 24

Housekeeping Surfaces

Answer 24

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

Question 25

Carpeting and Cloth Furnishings

Answer 25

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,

Question 26

Spills of Blood and Body Substances

Answer 26

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

Question 27

Greener Infection Control.1

Answer 27

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

Question 28

Greener Infection Control.2

Answer 28

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

Question 28

Greener Infection Control.3

Answer 28

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