Chapter 21

Question 1

Sterilization

Answer 1

is a process intended
to kill all microorganisms and is
the highest level of microbial
destruction

Question 2

Categories are based on

Answer 2

the risk of
infection associated with their intended
use

Question 3

Classifications are used to determine

Answer 3

the
minimal type of posttreatment processing

Question 4

Critical instruments

Answer 4

• Items used to penetrate soft tissue
  or bone
• Greatest risk of transmitting
  infection and must be sterilized by heat

Question 5

Semicritical instruments

Answer 5

• Touch mucous membranes or
  nonintact skin
• Lower transmission risk
• Sterilized by heat or receive
  minimum high-level disinfection if
  not heat tolerant

Question 6

Noncritical instruments

Answer 6

Contact only intact skin
 Low risk of infection transmission
 Cleaned and processed with EPA registered intermediate- or low level disinfectant

Question 7

Personal Protective Equipment
(PPE)

Answer 7

This includes utility gloves, mask,
eyewear, and protective clothing
Must be worn at all times when processing instruments.

Question 8

holding solution

Answer 8

may be any
noncorrosive liquid

Question 9

Dishwasher detergent

Answer 9

makes a good
holding solution because it is low-cost,
low-foaming, and readily available

Question 10

Holding Solution: The container must have a lid and must
be labeled with

Answer 10

A biohazard label (because of the
contaminated instruments)
A chemical label (because of the
cleaner/detergent)

Question 11

The holding solution should be changed

Answer 11

at least twice daily, and even more
frequently if it becomes clouded

Question 12

Hand scrubbing

Answer 12

is the least desirable
method of cleaning instruments
because it requires direct hand
contact with the contaminated
instrument

Question 13

Hand Scrubbing Precautions

Answer 13

 Wear goggle-type eyewear and
puncture-resistant gloves, as well as
your protective clothing
 Clean only one or two instruments at
a time
 Use only a long-handled brush,
preferably one with a hand guard or
wide surface
 Keep items above the waterline;
fully immersing them in a basin of
soapy water interferes with one’s
ability to see the sharp ends
 Allow instruments to air-dry or
carefully pat them with thick
toweling
 Never rub or roll instruments while
they are in a towel because of the
risk of accidental injury

Question 14

Ultrasonic Cleaning

Answer 14

Used to loosen and remove debris from instruments

Question 15

Ultrasonic Cleaner

Answer 15

Works by producing sound waves beyond the range
of human hearing

Question 16

The ultrasonic cleaning solution is highly contaminated

Answer 16

and must be discarded at
least once a day or sooner if it becomes visibly cloudy

Question 17

Packaging Instruments

Answer 17

Before sterilization, the instruments should be
wrapped or packaged to protect them from becoming
contaminated after sterilization

Question 18

An unwrapped cycle (sometimes called flash
sterilization)

Answer 18

is a method for sterilizing unwrapped patient care items for immediate use

Question 19

All reusable items (critical and
semicritical instruments)

Answer 19

that come into contact with the
patient’s blood, saliva, or mucous membranes must be heat sterilized

Question 20

The three most common forms of heat sterilization in the dental office are:

Answer 20

 Steam
 Chemical vapor
 Dry heat

Question 21

Autoclave

Answer 21

used to sterilize dental instruments and other items by means of steam under pressure

Question 22

Steam sterilization

Answer 22

involves heating water to
generate steam, producing a moist heat that rapidly
kills microorganisms

Question 23

Dental office steam sterilizers usually operate in four cycles

Answer 23

 Heat-up cycle
 Sterilizing cycle
 Depressurization cycle
 Drying cycle

Question 24

Unsaturated Chemical Vapor Sterilization

Answer 24

that a combination of
chemicals (alcohol, formaldehyde, ketone,
acetone, and water) is used instead of water to create a vapor for sterilization

Question 25

OSHA requires

Answer 25

a Safety Data Sheet (SDS) on the chemical vapor solution because of the chemicals’ toxicity

Question 26

major advantage of the chemical vapor sterilizer

Answer 26

is that it does not rust, dull, or corrode dry metal instruments prevents destruction of items wide range of items can be sterilized routinely without damage

Question 27

disadvantage of chemical vapor sterilizer

Answer 27

adequate ventilation is essential because residual chemical vapors containing formaldehyde and methyl alcohol may be released when the chamber door is opened at the end of the cycle

Question 28

The three major factors in chemical vapor sterilization are:

Answer 28

 Pressure, which should measure 20 psi  Temperature, which should measure 131º C (270º F)  Time, which should measure 20 to 40 minutes

Question 29

Dry Heat Sterilization

Answer 29

Operates by heating air and transferring that heat from the air to the instruments

Question 30

Dry heat sterilizers operate at

Answer 30

approximately 160º C to 190º C (320º F to 375º F), depending on the type of sterilizer

Question 31

Advantage of dry heat:

Answer 31

Instruments will not rust if they are thoroughly dry before being placed in the sterilizer

Question 32

Two types of dry heat

Answer 32

Static air and forced air

Question 33

Static Air Sterilizers

Answer 33

Similar to an oven  Heating coils are on the bottom of the chamber, and the hot air rises inside by way of natural convection

Question 34

Disadvantages of static air

Answer 34

include amount of time it takes and errors due to incorrect processing time The wrapping material must be heat resistant

Question 35

Forced Air Sterilizers Also called rapid heat transfer sterilizers

Answer 35

Circulate the hot air throughout the chamber at a high velocity This action permits rapid transfer of heat energy from the air to the instruments, reducing the time needed for sterilization

Question 36

Exposure time in a forced air sterilizer

Answer 36

after the sterilizing temperature has been reached, ranges from 6 minutes for unpackaged items to 12 minutes for packaged items

Question 37

static heat time

Answer 37

Heat is transferred from the static (nonmoving) air to the instruments in 1 to 2 hours

Question 38

Ethylene Oxide Sterilization

Answer 38

The use of ethylene oxide gas is a recognized method of sterilization  Carried out at low temperatures, which is an advantage for plastic and rubber items that would melt in heat sterilizers  Requires 4 to 12 hours, depending on the sterilizer model, and at least 16 hours of poststerilization aeration is required to remove the gas molecules bound to plastic and rubber surfaces  Ineffective on wet items  Toxicity is possible if gas is not handled properly

Question 39

Liquid Chemical Sterilants

Answer 39

 Some types of plastics, such as some rubber dam frames, shade guides, and x-ray film–holding devices, are damaged by heat sterilization  A liquid sterilant such as 2.0% to 3.4% glutaraldehyde must be used for sterilization of these items  Glutaraldehyde requires 10 hours of contact time; anything less than 10 hours is disinfection, not sterilization  Be sure you have an MSDS for these products

Question 40

three forms of sterilization monitoring are used

Answer 40

 Physical  Chemical  Biologic

Question 41

There are two types of chemical indicators

Answer 41

 Process indicators  Process integrators

Question 42

Process indicators (external)

Answer 42

are placed outside the instrument packages before sterilization Examples: Autoclave tape and color-change markings on packages or bags

Question 43

Process Integrators

Answer 43

 Placed inside instrument packages  They respond to a combination of pressure, temperature, and time  Process integrators are also known as multiparameter indicators  All sterilization factors are integrated  Examples: Strips, tabs, or tubes of colored liquid  The advantage of placing integrators inside each package is that penetration of the packaging by the sterilizing agent is ensured

Question 44

Limitations of Process Integrators

Answer 44

 Process indicators and integrators provide immediate visual control of sterilizing conditions  They do not indicate sterility and are not a replacement for biologic monitoring

Question 45

The CDC, American Dental Association, and Office of Safety and Asepsis Procedures Research Foundation recommend

Answer 45

at least weekly biologic testing of sterilization equipment

Question 46

Biologic monitoring (spore testing)

Answer 46

is the only way to determine whether sterilization has occurred and all bacteria and endospores have been killed

Question 47

Handpiece Sterilizing Techniques

Answer 47

Only steam sterilization and chemical vapor sterilizers are recommended Handpieces should NEVER be placed in the ultrasonic cleaner Never run a handpiece “hot” out of the sterilizer If handpieces need to be cooled quickly after sterilization, use an air fan to blow room temperature air over them