Infection control in the dental clinic

1. By Mohammed Saad

2. As a matter of fact, the dentist, dental assistant, dental
hygienist and dental technician are at risk of exposure
to disease agents through contact with blood or other
potentially infectious materials. So by studying and by
carefully following the infection control and safety
guidelines, all the team work can minimize the risks of
disease transmission to himself and to the patients in
the dental office.
All practitioners should incorporate recommended CDC
, ADA and OSHA infection control guidelines into their
daily practice .

3. CHAIN OF INFECTION
All links must be connected for infection to take
place
Pathogen
Source
ModeEntry
Susceptible Host
(sufficient virulence
& adequate numbers)
(allows pathogen to
survive & multiply)
(of transmission
from source to host)(portal that the
pathogen can
enter the host)
(i.e., one that is not immune)

4. Definitions:
CDC:
Center of Disease Control and Prevention .
ADA:
American Dental Association.
ADAA:
American Dental Assistants Association.
OSHA:
Occupational Safety and Health Administration.
OSAP:
Organization for Safety and Asepsis Procedures.
EPA:
Environmental Protection Agency.
FDA :
Food and Drug Administration.
NIOSH:
National Institute for Occupational Safety and Health.

5. Why , Who and what
Why is infection control necessary in dentistry ?
Dental staff and patients may be exposed to a wide variety of pathogenic
microorganisms .
Who is responsible for infection control in the dental office ?
Each member of the dental team must follow the recommended guidelines .
What should be done to prevent the transmission of disease in the dental
office ?
The most effective ways to prevent the transmission of diseases includes :
1) Hand washing
2) Gloves
3) Face masks
4) Protective eye wear
5) protective clothing
6) instrument sterilization and disinfection

6. Diseases Transmission in Dental Office
The dental office should have an infection control program to prevent the
transmission of disease from the following :
Patient to dental team
Dental team to patient
Patient to patient
Dental office to community ( include dental team’s family )
Community to dental office to patient
To prevent such infections, following is a list of all those procedures and
precautions that together constitute infection control. These guidelines
should be followed each time treatment is performed because we are never
certain of the patient's status, either because they themselves do not know
or because they have chosen not to inform their healthcare providers of their
condition. Following these guidelines for every patient is called "Standard
Precautions".
Diseases Transmission in Dental Office

7. 1. IMMUNIZATION
2. PATIENT SCREENING
3. HAND WASHING
4. BARRIER TECHNIQUES -
• Personal Protective Equipment (PPE)
• Rubber dam, Pre-procedural rinsing
6. INSTRUMENT STERILIZATION AND DISINFECTION
5. NEEDLE & SHARP INSTRUMENT SAFETY
• Occupational Exposure To Blood/Body Fluids
7. SURFACE DISINFECTION
8. radiographic asepsis
9. laboratory asepsis
10. infectious dental waste management & disposal
Standard Precautions

8.  Direct contact with blood or body fluids
 Indirect contact with a contaminated
instrument or surface
 Contact of mucosa of the eyes, nose, or
mouth with droplets or spatter
 Inhalation of airborne microorganisms
Modes of Diseases Transmission

9. • It is the period of protective equipment :
An essential pretreatment procedure is the preparation
of all personnel involved in patient care. This includes
the utilization of personal protective equipment (gown,
eyewear, mask and gloves) and hand hygiene.
A) Infection Control during the Pretreatment
Period

10. Infection Control During the Pretreatment Period
The process of infection control begins during the period of
preparation for clinical treatment. Paying attention to infection
control at this time has several payoffs. In addition to reducing the
risk of transmission of infectious agents during patient care,
thinking ahead will make the treatment session more efficient and
will also make the post treatment infection control process easier
and more effective.
1. Remove unnecessary items from the dental procedure area :
The dental procedure area should be arranged to facilitate a
thorough cleaning following each patient.
2. Preplan the materials needed during treatment.
Set out all instruments, medications, impression materials,
and other items that are needed for a procedure. Thinking
ahead minimizes the need to search for additional items or to
enter cabinets and drawers once gloves have become
contaminated.

11. 3. Utilize disposable items whenever possible :
The use of disposable items saves time during cleanup
and decontamination and solves the problem of proper
reprocessing.
4. Use prearranged tray set-ups for routine or frequently
performed procedures.
Helps to eliminate the need to go into cabinets once you have
started a procedure.
5. Use individualized, sterilized bur blocks for each procedure
. Using individualized bur blocks containing only the burs required
for that procedure helps to eliminate the contamination of other,
unneeded burs and to make clean-up easier.

13. 6. If indicated, have the rubber dam setup on the tray.
When a rubber dam will be used during a clinical procedure, it
also should be included on the tray setup. In addition, include
those items needed for high-velocity evacuation.

14. 7. Identify those items that will become contaminated during
treatment.
While preparing the dental procedure area prior to beginning a
clinical procedure, consider which items will become
contaminated during treatment. Examples of such surfaces include
countertops, light handles, X-ray unit heads, tray tables etc. Decide
whether to use a barrier, e.g., plastic wrap to prevent
contamination of these surfaces and items or to disinfect them
when the procedure is complete.
8. Review patient records before initiating treatment and place
radiographs on the view box.
Do not leave the record on the countertop or handle it after
beginning treatment. Place the record in a drawer or out of the
dental procedure area, so that it doesn’t become contaminated.
Entries into the record should be done before and after the
procedure.

16. 9. Prepare personnel involved in patient care.
An essential pretreatment procedure is the preparation of all
personnel involved in patient care. This includes the utilization of
personal protective equipment (gown, eyewear, mask and gloves)
and hand hygiene.

17. A .Handwashing and hand care :
According to the U.S. Centers for Disease
Control (CDC) , hand washing is the single most
important procedure for preventing the spread of
infection. So , you must wash your hands each time
before you put on gloves and immediately after you
remove gloves . Handwashing is also required if you
touch contaminated instruments or surfaces during
working .
We should always use liquid soap during handwashing
. Bar soap should never be used because it may
transmit contamination .

18. Hands Need to be Cleaned When
Visibly dirty
After touching contaminated objects with bare
hands
Before and after patient treatment (before
glove placement and after glove removal)

20. Personal protective equipment ( PPE )
OSHA requires the employer to provide employees
with appropriate personal protective equipment .
Examples of PPE :
1- Protective clothing
2- Surgical masks
3- Face shields
4- Protective eyewear
5- Disposable patient treatment gloves , and
6- Heavy-duty utility gloves .

21. These PPE must be used whenever
you :
• Performing tasks that could produce
splash or spatter .
• Any contact with body fluids
• Perform other clinical activities that
require handling contaminated items e.g.
radiographs , impressions , dentures or
contaminated equipment and surfaces .

22. We will study 4 aspects of each
one of these equipments :
• The purpose of using .
• Types .
• Guidelines for the use .
• Requirements .

23. 1) Protective clothing :
Purpose : to protect the skin
and underclothing from the
exposure to saliva , blood ,
aerosol , and other
contaminated materials .
Types
1) Laboratory coats

24. 2) Gown

25. 3) Surgical scrubs

26. Guidelines for the use of protective clothing
1) It should not be worn out of the office for any reason .
2) Change these work clothes at least daily, or more often
if soiled, especially if they become visibly contaminated
with blood.
3) It must not be worn during eating or in resting rooms .
4) It should be washed and laundered separately .
Protective clothing requirements :
1) Should be made of fluid-resistant material ( cotton ,
cotton/polyester, or disposable jackets or gowns .
2) Clothing should have long sleeves and a high neckline
to minimize the amount of uncovered skin .
3) Must cover dental personnel at least to the knees
when seated

27. 2) Protective masks :
Purpose the mask worn over the nose and mouth to
protect the person from inhaling infectious organisms
spread by the aerosol spray of the handpiece or air-water
syringe .
Types the two most common types of masks are the
dome-shaped and flat types .
The dome-shaped Flat types

28. Guidelines for the use of protective masks :
• Masks should be changed for every patient or more
often, particularly if heavy spatter is generated during the
treatment or if the mask becomes damp.
•Masks should be handled by touching only the side edges
to avoid contact with the more heavily contaminated body
of the mask.
•Masks should conform to the shape of the face .
•Masks should not contact the mouth when being worn
because the moisture generated will decrease the mask
filtration efficiency .
Requirements : masks should be at least with 95% filtration
efficiency to remove particles 3 – 5 microns in diameter .

29. 3) Protective eyewear :
Purpose eyewear is worn to protect the eyes against
damage from :
• Aerosolized pathogens .
• Flying sharp debris such as scrap amalgam and tooth
fragments .
• Splattered solutions
• Caustic chemicals
Guidelines for the use of protective eyewear :
1) OSHA requires the use of eyewear with both front and
side protection ( solid side shields ) .
2) Members who wear correction glasses or contact lenses
must wear protective eyewear with a side shields or a face
shield .

30. 3) It must be cleaned and
decontaminated after each
treatment or patient visit
according to the manufacture’s
instructions .
Types :
Two types of protective
eyewear used during patient
care :
1) Glasses with protective side
shield , and
2) Clear face shields .

31. Face shields :
a chin-length plastic face shield
that protects your eyes, nose, and
mouth from spatter may be worn
and replace the protective
eyewear .However , a shield
cannot replace the mask because
it does not protect against
inhalation of contaminated aerosol
Face shield worn in addition to the mask

33. Patient eyewear :
Patients should be provided with protective eyewear
because they may subjected to eye damage from :
1) Handpiece spatter
2) Splashed dental materials
3) Airborne bits of acrylic or tooth fragments

34. 4) Gloves :
Purpose :
Gloves must be worn by the dentist , dental assistant , and
dental hygienist during all dental treatment to avoid
contact with the patient’s blood , saliva , or mucous
membranes or with contaminated items or surfaces .
Types :
The type of gloves used in dental practice should
be determined by the various procedures that are
performed in the practice as follow :
1) Examination gloves usually are latex or vinyl . These are
the gloves most frequently worn by the dental team
during patient care .

35. Examination gloves are
inexpensive , available in a range
of sizes from extra small to extra
large , and are ambidextrous (
used for both right and left hands )
. These gloves are nonsterile and
serve only as a protective barrier
for the wearer .
Examination gloves

36. 2) Overgloves are made of lightweight , inexpensive ,
clear plastic . Overgloves may be worn over contaminated
treatment gloves ( overgloving ) to prevent
contamination of clean objects ( telephone , pen ,opening
drawers and cabinets ) that may be handled during
treatment . Overgloves are discarded after a single use .
To prevent contamination , an Overgloves is
worn while using a pen .

37. 3) Sterile surgical gloves are used during surgical
procedures such as oral surgery or periodontal treatment .
Sterile surgical gloves are supplied in specific sizes and
prepackaged unites to maintain sterility before use .
Sterile surgical gloves

38. 4) Utility gloves are made from a puncture-resistant , heavy
material which are not used for direct patient care . Utility
gloves may be washed , disinfected , or sterilized and
reused and must be discarded when they become old .

39. Guidelines for the use of gloves :
• All gloves used in patient care must be discarded after
a single use.
• Torn or damaged gloves must be replaced immediately .
• Do not wear jewelry under gloves because , it may tear
the gloves .
• If the procedure is long , change the gloves each hour .
• Contaminated gloves should be removed before leaving
the chair side during patient car.
• Hands must be washed after glove removal and dried
well before regloving .

40. 5) Non-latex containing gloves occasionally , the health
care providers or patients may experience serious allergic
reactions to latex . The person who is sensitive to latex can
substitute with gloves made from vinyl , nitrile
and other non-latex containing materials .
Hand dermatitis that developed
from wearing latex gloves.

41. B) Infection Control during the treatment Period
(Chairside Infection Control ) :
1) Use care when receiving, handling, or
passing sharp instruments.
2) Take special precautions with syringes and
needles.
3) Use a rubber dam whenever possible.
The infection control procedures described in
the previous period will help you to reduce
the risk of transmission of infectious agents.
During treatment there are additional
precautions that can be taken to further
reduce infection risks.

42. 4) Avoid touching unprotected switches, handles and other
equipment once gloves have been contaminated.
5) Avoid entering cabinets once gloves have been contaminated.

44. After patient treatment , dental unite and treatment
room surfaces are likely to become contaminated with
saliva or by aerosol containing blood . Also a primary
source of cross-contamination occurs when a member
of the dental team touches surfaces with contaminated
gloves .
The laboratory studies have proved that microorganisms
may survive on environmental surfaces for long time . For
example, Mycobacterium tuberculosis may survive for
weeks .
c) Infection Control during the Post-Treatment Period

45. Dental treatment room surfaces :
Dental treatment room surfaces are classified as either :
• Clinical contact surfaces or
• General housekeeping surfaces .
Clinical contact surfaces are those that are touched
by contaminated hands , instruments or by spatter
during treatment . It should be cleaned and
disinfected between patients .
All the other surfaces , such as the walls and floors
, are considered general housekeeping surfaces

46. Clinical contact surfaces :
The clinical surfaces can be classified into three
categories :
A) Touch surfaces : are directly touched and
contaminated during treatment procedures . Touch
surfaces include ;
Dental light handles
Dental unite controls and
Chair switches

48. B) Transfer surfaces :
are touched by contaminated instruments such as
instruments trays .
C) Splash , spatter , and droplet surfaces :
countertops are a major example .
Touch and transfer surfaces should be either barrier-
protected or cleaned and disinfected between patients . In
the same time , splash , spatter , and droplet surfaces should
be cleaned at least once daily .

49. Dealing with surface contamination
The goal of the two methods to deal with surface
contamination are :
1- To prevent the surface from becoming contaminated
by the use of a surface barrier .
2- To preclean and disinfect the surfaces between
Patients .
Each method has advantages and disadvantages , and most
dental offices use a combination of surface disinfection and
surface barriers .

50. Surface barriers :
Surface barriers are used to
prevent contamination on the
surface underneath .
All the surface barriers should
be resistant to fluids in order
to prevent microorganisms in
saliva , blood , and other
liquids from soaking through
the barrier and reach the
surface underneath .
Chair Drapes

51. Film Dispenser

52. Some plastic bags are specially designed to the shapes of
the dental chair , air-water syringe , and light handles .

53. Sticky tape as a plastic barrier is frequently used to
protect smooth surfaces , such as electrical switches on
chairs and x- ray unite

59. 1. Continue to wear personal protective equipment during
clean-up: After patient care is completed, begin the
cleaning and disinfection process by removing
contaminated gloves used during treatment, wash your
hands and use the utility gloves before beginning the
clean up. Continue to wear protective eyewear, mask,
and gown.
2. Remove all disposable barriers : All of the barriers
placed before treatment, including light handle covers
and countertop barriers, should be removed.
3. Clean and disinfect all items not protected by barriers.
Infection Control During the Post-Treatment
Period

60. Cleaning and disinfection of the dental treatment room
surfaces are important components in an effective
infection control program .
Precleaning
Precleaning means that all contaminated surfaces must be
precleaned before they can be disinfected . Precleaning
reduces the number of microbes and remove blood , saliva
, and other body fluids .
Precleaning techniques are most effective when
used on contaminated surfaces that are smooth and easily
accessible for cleaning .

61. Materials used for precleaning regular soap and water
always used for precleaning . However , a disinfectants
that can cleans as well as disinfect are present today .
Disinfection
Disinfection is directed to kill disease-causing
microorganisms that remain on the surface after
precleaning .
N.B always do not confuse disinfection with sterilization .
Sterilization is the process in which all forms of life
organisms are destroyed .
The term disinfectant is used for chemicals that are
applied for cleaning surfaces , such as countertops and
dental equipment .

63. Disinfectants
Disinfectants are chemicals that destroy or inactivate most
species of pathogenic ( disease-causing ) micro-organisms .
In dentistry , only those products that registered with the
U.S Environmental protection Agency ( EPA ) with
tuberculocidal action should be used to disinfect dental
treatment areas .
Ideal surface disinfectant
The ideal surface disinfectant must be rabidly kills a broad
spectrum of bacteria , has residual activity , minimal
toxicity , odorless , inexpensive and does not damage
surfaces to be treated .

64. Disinfectant such as :
Iodophors :
• Iodophors are EPA-registered hospital disinfectants with
tuberculocidal action .
• It is recommended for disinfecting surfaces after dental
treatment .
• Iodophors are usually effective within 5 to 10 minutes .
• Non-irritant and non-toxic .
• Unstable solution → must be changed regularly .
• Because they contain iodine , iodophors may corrode or
discolor certain metals and temporarily may cause red or
yellow stains on clothing and other surfaces .

65. Synthetic phenol compounds :
• Are EPA-registered intermediate-level hospital
disinfectants with broad-spectrum activity ( can kill a wide
rang of microbes ) that used for surface disinfection .
• Phenol can be used on metal , glass , rubber , or plastic .
• They also may be used as a holding solution for
instruments , however , phenols leave a residual film on
treated surfaces .
• Synthetic phenol compounds must be prepared daily .
• Non irritant , non-toxic and non-corrosive .

66. Sodium hypochlorite :
Sodium hypochlorite is a fast-acting , economic and broad-
spectrum intermediate-level disinfectant .
Disinfectant effect observed after 10 minutes .
The Centers for Disease Control and prevention ( CDC )
currently recommended the use of up to 1 – 100 dilution
of sodium hypochlorite for surface decontamination .
The disadvantages →
• Unstable solution need daily preparation .
• It has a strong and unpleasant odor .
• Irritant for skin and eyes .
• Corrosive for some metals .
hypochlorite is destructive to fabrics and may eventually
cause plastic chair covers to crack .

67. Alcohol :
Ethyl alcohol and isopropyl alcohol have been used over the
years as skin antiseptics and surface disinfectants . However
, alcohol are not effective in the presence of blood and
saliva droplets because of the rapid rate of evaporation will
limits the antimicrobial activity of alcohol . In addition ,
alcohols are damaging to certain materials , such as plastics
and vinyl .
The American Dental Association ( ADA ) , CDC , and OSAP
do not recommend alcohol as an environmental surface
disinfectant .

68. Chlorine dioxide :
Chlorine dioxide can be used as an effective , rapid-acting
, environmental surface disinfectant ( 3 minutes ) or as a
chemical sterilant ( 6 hours ) .
The disadvantages →
(1) it must be prepared fresh daily .
(2) it is corrosive to aluminum containers

69. Classification of instruments and equipment :
According to the Centers for Disease Control and
Prevention, dental instruments are classified into three
categories depending on the risk of transmitting infection.
1) Critical instruments are those used to penetrate soft
tissue or bone and should be sterilized after each use.
Sterilization is achieved by steam under pressure
(autoclaving), dry heat, or heat/chemical vapor .
Critical instruments include forceps, scalpels, bone chisels,
scalars, and burs .

71. 2) Semicritical instruments
are those that do not penetrate softtissues or bone but
contact oral tissues, such as amalgam condensers,
air/water syringe , tips mirrors, intraoral radiography
accessories, digital radiography sensors, and other dental
high-technology instruments . These devices should also
be sterilized after each use. In some cases, however, high-
leveldisinfection is appropriate. A high-level disinfectant is
registered with the U.S. Environmental Protection Agency
(EPA) as a "sterilant/disinfectant" and must be labeled as
such.

73. 3) Noncritical instruments
are those that come into contact only with intact skin
such as externalcomponents of X-ray heads. Such
devices have a relatively low risk of transmitting
infection and, therefore, may be reprocessed
between patients by intermediate-level or low-level
disinfection.

74. Managing contaminated sharps :
Contaminated needles and other disposable sharps ,
such as scalpel blades , orthodontic wires , and broken
glass must be placed into a sharps container .
OSHA , CDC and the EPA classify sharps as infectious
waste .
According to OSHA regulations , disposable sharps
must be placed in a puncture resistant , closable , and
color-coded or labeled with the biohazard symbol
container immediately after use .

75. Biohazard symbol

77. Proper processing of contaminated dental instruments in
a six-steps process as :
1) Transport : transport contaminated instruments to the
processing area .
2) Cleaning : clean instruments with a hand-free ,
mechanical process such as an ultrasonic cleaner or
instrument washer.
3) Packing : warp/package instruments in appropriate
materials containing an external process indicator .
4) Sterilization : place the packages in a single layers or in
racks to increase circulation of the sterilizing agent
around the instruments . Operate the sterilizer according to
the manufacture’s instructions . Allow packages to cool
before removing them from the sterilizer .

78. 5) Storage: Store instruments in a clean , dry
environment in a manner that maintains the integrity of
the package . Rotate packages so that those with the
oldest sterilization date will be used first .
6) Delivery : deliver packages to point of use in a manner
that maintains sterility of the instruments until they are
used . Inspect each package for damage .

84. Holding solution :
If the instruments can't be cleaned immediately after
procedures, they should be placed in a holding solution to
prevent drying of blood and debris on the instruments .
A holding solution is a liquid disinfectant/sterilizing
solution used to soak contaminated instruments before
they are cleaned and sterilized. It has the purpose to:
• Decrease infectious microbes on instruments .
• Loosen and minimize debris before scrubbing or
ultrasonic cleaning .
• Minimize the physical handling of the instruments .

85. The holding solution must be:
Non-corrosive liquid,
Of low cost,
Non-staining and
Readily available.
The holding solution should be changed at least twice daily
It is important to use a covered container with a separate
instrument basket to ensure complete immersion.
Remember , a holding solution is necessary only when
contaminated instruments cannot be processed
immediately .

86. The holding solution

87. Precleaning and packaging instruments
Precleaning is done in three ways:
- Hand scrubbing
- Ultrasonic cleaning
-Instrument washing machine

88. Hand scrubbing
This method is unfavorable because it requires direct
hand contact with the contaminated instrument and
accidental injury from these contaminated items may
happen.
During hand scrubbing we must follow the following
precautions
1- Wear eye wear and puncture-resistant gloves (P.P.E ) .
1- Clean only one by one .
2- Use only a long-handled brush .
3- Do not immerse items in soapy water or deep basin
so you can see the sharp edges.

90. Ultra-sonic cleaning
• Ultrasonic cleaning is recommended in place of hand-
scrubbing in order to reduce direct staff contact with
contaminated instruments.
• The ultrasonic cleaner works by producing sound waves
which causes formation of bubbles in liquid . The bubbles
are too small to be seen .
• The mechanical cleaning action of the bubbles
combined with the chemical action of the ultrasonic
solution removes the debris from the instruments .
• Instruments should be processed in the ultrasonic
cleaner until they are visibly clean . The time may vary
from 5 to 15 minutes .

93. Automated washer
It looks similar to a household
dishwasher. It uses a
combination of very hot
water together with a
detergent to remove the
organic material. It is
considered as disinfector
because it subjects the
instruments to a level of heat
that kills most vegetative
microorganisms.

96. Packaging instruments
Before sterilization the instruments must be packaged to
protect them from becoming contaminated after
sterilization .
They can be contaminated by aerosols in the air , dust ,
or contact with nonsterile surfaces .
An additional advantage to packaging instruments is that
they can be grouped into special setups .

100. Sterilization monitoring
Sterilization monitoring
Because sterilization failure can occur at any time, it is
critical to determine that dental instruments are properly
sterilized or not because microorganisms can not be seen
by naked eye.
Nowadays, three forms for sterilization monitoring are
used :
PHYSICAL CHEMICAL BIOLOGICAL

101. Physical monitoring:
Physical monitoring of the
sterilization process involves
looking at the gauges and
readings on the sterilizer and
recording the temperatures,
pressure, and exposure time.
Remember that the temperature
recorded is for the chamber, not
the inside of the pack. Therefore,
problems with overloading or
improper packaging would not
be detected from the reading on
the gauges.

102. Chemical monitoring:
Chemical monitoring involves the use of heat-sensitive
chemicals that change color when exposed to certain
conditions.
The two types of chemical indicators are process
indicators and process integrators.
Process indicators
This is used externally outside the instruments packages
like autoclave tape and color change marking. Its aim is to
determine if the package is processed or not.
They simply identify instrument packs that have been
exposed to a certain temperature.

103. They do not measure the duration or the pressure. They
are useful only in distinguishing between packages that
were processed and those that were not processed. This
can prevent accidental use of unprocessed instruments.

104. Process integrators
Process integrators are placed inside instrument
packages. They respond to a combination of pressure,
temperature, and time. All sterilization factors are
integrated. Examples of process integrators include
strips, tabs, or tubes of colored liquid.

105. Biologic monitoring
This is the best way to determine if sterilization has
occurred.
Biologic monitoring , or spore testing, is the only way to
determine if sterilization has occurred. The CDC, American
Dental Association recommend at least weekly biologic
monitoring of sterilization equipment .
Biologic indicators (BIs), also known as spore tests, are
vials or strips of paper that contain harmless bacterial
spores (spores are highly resistant to heat).
Method :
Three BIs are used in testing. Two BIs are placed inside
instrument packs, and the sterilizer is operated under
normal conditions.

106. The third strip is set aside as a control. After the load has
been sterilized, all BIs are cultured. If the spores survive
the sterilization cycle (a positive culture), a sterilization
failure has occurred. If the spores are killed (a negative
culture), the sterilization cycle was successful.

107. Sterilization in the dental office :
The three most common forms of heat sterilization in the
dental office are :
Steam sterilization,
Chemical vapor sterilization, and
Dry heat sterilization.

108. 1) Steam sterilization : involves heating water to
generate steam, producing a moist heat that
rapidly kills microorganisms. As the steam
completely fills the sterilizing chamber, the
cooler air is pushed out of an escape valve,
which then closes and allows the pressure to
increase which increase the temperature
reaches up to 120 C which is higher than boiling
water . It is the heat, not the pressure that
actually kills the microorganisms.

109. A disadvantage of steam sterilization is that the moisture
may cause corrosion on some high-carbon steel
instruments. Distilled water should be used in autoclaves
instead of tap water, which often contains minerals and
impurities. Distilled water can minimize corrosion and
pitting.
0peration cycles :
Dental office steam sterilizers usually operate through four
cycles :
1) heat-up cycle 2) sterilizing cycle
3) depressurization cycle 4) drying cycle

110. Flash Sterilization
involves sterilizing unpackaged instruments using short
exposure times. The instruments are placed in the
chamber unwrapped. The sterility of the instruments is
defeated immediately when the instruments are
removed from the sterilizer.
Flash sterilization should be used only for instruments
that are to be used promptly on removal from the
sterilizer.

111. Dry-heat Sterilizers
Dry-heat sterilizers operate by heating air and transferring
that heat from the air to the instruments. This form of
sterilization requires higher temperatures than steam or
chemical vapor sterilization . temperature ranges between
(160 C to 190 C) .
The total cycle time :
placing instruments in oven, heating to 170 C, timing for 1
hour, and then cooling it from 2–2.5 hours .
The advantage of dry heat is that the instruments will not
rust if they are thoroughly dry before they are placed in
the sterilizer.
The disadvantage of dry heat is the risk of damaging
plastic and rubber instruments and also it need long time .

112. Chemical liquid sterilization
Used for some types of plastics items that can damaged
by heat such as some rubber dam frames , shade guides ,
and x-ray film-holding devices .
A liquid sterilizer such as 2% to 3.4% Glutaraldehyde
must be used for sterilizing these items .
Sterilizing in Glutaraldehyde requires a 10 hours contact
time, but if it is less than 10 hours, it is only disinfection,
not sterilization .
Glutaraldehyde must be used full strength ( not diluted (
This material is highly toxic .

113. STERILIZATION FAILURE
Several factors can cause the sterilization process to fail .
Examples of common mistakes include :
• overloading of sterilizer chamber .
• lack of separation between packs or trays in the
chamber .
• wrong packaging material for method of sterilization .
• more than two layers of wrap, inhibiting penetration .
• sterilizer timer malfunction .
• improper cleaning of items to be sterilized.

115. Sterilization of hand pieces is recommended
whenever possible :
Hand pieces that are designed for steam sterilization
between uses are preferred. When a hand piece cannot
be heat or steam sterilized, chemical disinfection can be
used as an alternative.

118. The End