Routinely dental care professionals are at an increased risk of crossinfection while treating patients. This occupational potential for disease transmission becomes evident initially when one realizes that most human microbial pathogens have been isolated from oral secretions. Because of repeated exposure to the microorganisms present in blood and saliva, the incidence of certain infectious diseases has been significantly higher among dental professionals than observed for the general population.
2. Contents
• Introduction
• Sterilization
• Autoclaves
• Radiation
• Disinfection
• Spaulding’s classification
• Sterilization in prosthodontics
• Disinfection in prosthodontics
• IDA CoViD 19 protocol
3. Introduction
One of the primary responsibilities of dental healthcare professionals is
to create a safe and comfortable environment for their patients. Keeping
this in view, the American Dental Association (ADA), Indian Dental
Association (IDA)and the Centers for Disease Control (CDC) have
devised protocols to prevent cross-infection among dental patients. This
involves thorough cleaning and sterilization of all types of dental
instruments, each time they are used on a patient.
4. Organisms can be transmitted in dental
settings through
1) Direct contact with blood, oral fluids, or other patient materials
2) Indirect contact with contaminated objects
3) Contact of conjunctival, nasal, or oral mucosa with droplets
4) Inhalation of airborne micro organisms that can remain suspended
in the air for long periods.
5. • Cleaning: cleaning is an essential process which is performed before sterilization
and disinfection of dental instruments. This involves cleaning all surfaces of
dental instruments to remove blood, microbes, and debris, and to prepare
instruments for the dental sterilization process. Cleaning of instruments is usually
performed with water or detergents.
• Disinfection: disinfection is a process in which all microbes are removed, except
bacterial spores. Disinfection of dental instruments is usually performed with
liquid disinfectants.
• Sterilization: Sterilization is a process, which if performed properly, kills all
microbes, including bacterial spores, present on the surface of dental
instruments.
6. Process
Presoaking : A presoaking
solution (phenolic
compounds) prevents drying
of debris, helps to dissolve or
soften organic debris and
sometimes helps in microbial
killing.
Cleaning : Cleaning can be
done either by hand,
scrubbing or with the use of
ultrasonic devices.
Corrosion control
: Instruments must be dried
prior to sterilization to
decrease chances of corrosion.
Packaging : The instruments
can be packed individually or
in small groups and
distributed on sterile or
disposable disinfected trays
for use at chair side
Sterilization
Storage : Sterile packs and
trays should be kept in dry,
low dust, low traffic areas
away from sinks and sewer of
water pipes, at least a few
inches above the floor.
Distribution
8. Different methods of sterilization are used in dentistry, based on required
depth of sterilization as well as the type of dental material:
1. Sterilization using steam autoclave
• This is the most effective and most commonly used method
of sterilization in dental practice. Instruments in an
autoclave are sterilized at 121ᵒ C for 15 minutes and 15
pounds pressure.
2. Dry Heat Ovens
• These are electrical devices, which use dry heat to sterilize
dental instruments. Dry heat ovens are used to sterilize
those instruments which do not get burnt during heating,
such as glass slabs or powders.
9. 3. Chemical Vapor Sterilization
During chemical vapor sterilization, a mixture of various
chemicals such as alcohol, ketones, formaldehyde, and water
are heated under pressure to form a sterilization gas. A
typical sterilization procedure requires 20 minutes at 270ᵒF,
under 20 psi pressure to complete.
4. Cold Sterilization
This type sterilization is used on heat-sensitive dental
instruments. Solutions such as glutaraldehyde or Sodium
hypochlorite may be used for this purpose.
10. Autoclave
• The autoclave is a sealed device that kills
microorganisms using saturated steam
under pressure.
• The use of moist heat facilitates the killing
of all microorganisms, including heat-
resistant endospores which is achieved by
heating the materials inside the device at
temperatures above the boiling point of
water.
11. The sterilization cycle
• The sterilization cycle can be divided into
three periods: the heating-up period,
the holding period and the cooling
period.
1. Removal of air by a vacuum pump while
the chamber is heated to the selected
temperature.
2. Holding the load, which is sterilized, for
the appropriate period at the selected
temperature and pressure.
3. Drying the load to its original condition by
a partial vacuum
4. Restoration of the chamber to
atmospheric pressure by rapid exhaustion of
steam.
12. Types of autoclaves
Vacuum autoclaves in which air is evacuated from a metal
chamber by vacuum pump. These vacuum autoclaves are more
desirable for routine dentistry than the gravity displacement type
for the sterilization of hollow devices such as dental handpieces.
Gravity displacement autoclaves are small, automatic bench-
top autoclaves. They work on the principle of downward
displacement of air as a consequence of steam entering at the top of
the chamber.
Autoclaves used in dentistry
• Type N: air removal in type N sterilizers is achieved by passive
displacement with steam. They are non-vacuum sterilizers
designed for non-wrapped solid instruments.
• Type B (vacuum): these sterilizers incorporate a vacuum stage
and are designed to reprocess load types such as hollow, air-
retentive and packaged loads.
13.
14. Sterilization Monitoring: Types of Indicators
Mechanical:
– Measures time, temperature, and pressure.
Chemical:
– Change in color when physical parameter is reached.
Biological (spore tests):
– Uses biological spores to asses the sterilization process directly.
16. Chemical Monitoring
Use an internal chemical indicator in every
package. If the internal indicator is not visible
from the outside, then also use an external
indicator.
– Chemical indicators may be integrated into
the package design.
Inspect indicator(s) after sterilization and at time
of use.
If the appropriate color change did not
occur, do not use the instruments.
17. Biological Monitoring
Assess sterilization process directly by killing known highly resistant
microorganisms.
Use biological indicators (spore tests) at least weekly.
18. Radiation
Two types of radiation are used for sterilization.
1. Non ionizing and
2. Ionizing.
• Infrared and ultraviolet rays are of the non-ionizing, low-energy
type, while gamma rays and high-energy electrons are the ionizing,
high energy type.
19. 1.Sterilization of operating theatre
2.Sterilization of the interiors of
biological safety cabinets
Used for sterilization of an article that
does not stand heat as rubber
catheters, gloves, plastic syringes.
20. Ultrasonic Vibrators:
• Used instruments are soaked into a container containing
70% isopropyl alcohol for removal of organic debris.
After removing instruments rinse thoroughly in warm
water to remove all chemicals.
• As a final step insert the instruments into the ultrasonic
vibrator and operate for 30 minutes, after which sterile
instruments are rendered.
• Ultrasonic vibrators are generally used for non-critical
items.
21. Recent advances in sterilization
Plasma sterilization:
• Plasma is known as the fourth state of matter and consists
of ions, electrons or neutral particles. A radio frequency
energy is applied to create an electromagnetic field.
• Into this, hydrogen peroxide vapors are introduced which
generates a state of plasma containing free radicals of
hydrogen and oxygen.
• This state renders the articles sterile by denaturing all
microorganisms. Arthroscopes, urethroscopes, etc., are
sterilized by plasma sterilization.
23. Alcohols
Ethyl alcohol (ethanol) and isopropyl alcohol
• most frequently used. They are used mainly as skin
antiseptics at a concentration of 60- 90% in water.
• They act by denaturing bacterial proteins. They have no
action on spores
Aldehydes
• Formaldehyde gas is used for sterilizing instruments,
heatsensitive catheters and for fumigating wards,
isolation rooms and laboratories
24. Glutaraldehyde
• Has an action similar to that of formaldehyde.
• It is especially effective against the tubercle bacilli, fungi
and viruses. It has no deleterious effect on cement or
lenses of instruments.
Hypochlorous acid
• is generated from the reverse reaction of sodium
hypochlorite and hydrogen peroxide. It has bactericidal
activity against common pathogenic organisms.
Chlorine
• have been used as disinfectants over time.
• They are markedly bactericidal and virucidal.
25. Iodine
• in an aqueous and alcoholic solution has been widely used as a
skin disinfectant.
• It is bactericidal, with moderate action against spores. It is
active against the tubercle bacteria and viruses.
• Phenols is widely used as disinfectants in hospital.
Phenols
• Commonly used compounds are Lysol and cresol
• They are not readily inactivated by the presence of organic
matter; hence, they are good general disinfectants.
Chlorhexidine
• a relatively non-toxic skin antiseptic and wound dressing.
They are active against most Gram-positive organisms and
fairly effective against Gram-negative bacteria.
26. Gases
Ethylene oxide:
• This is a colorless liquid highly penetrating at
normal temperature and pressure.
• It diffuses through many types of porous materials
and readily penetrates some plastics.
• It is unsuitable for fumigating rooms because of its
explosive property.
Formaldehyde gas:
• This is employed for fumigation of operation
theatres and other rooms.
27. Levels of disinfection
High-level
disinfectant:
• kills all microbial
pathogens except
large numbers of
spores. It may have
some activity
against a smaller
number of spores if
the contact time is
increased.
• For example,
glutaraldehyde and
hydrogen peroxide.
Intermediate-level
disinfectant:
• kills all microbial
pathogens including
mycobacteria and
non-enveloped
viruses except
spores.
• For example,
alcohol, phenolic
compounds and
iodophores.
Low-level
disinfectant:
• kills only vegetative
bacteria, fungi and
lipid enveloped
viruses.
• For example,
quaternary
ammonium
compound.
30. Categories of Patient-Care Items
Three categories:
1. Critical.
2. Semicritical.
3. Noncritical.
Based on intended use and the potential risk of disease
transmission
31. Critical Items
• Penetrate soft tissue or contact bone, enter into or contact
the vascular system or other normally sterile tissue.
• Greatest risk of transmitting infection.
• Must be heat sterilized between use, or sterile single-use,
disposable devices must be used.
• Examples: surgical instruments and periodontal
scalers.
32. Semi-critical Items
Contact mucous membranes or non-intact skin
(e.g., exposed skin that is chapped, abraded, or
has dermatitis).
Lower risk of transmission.
Should be heat sterilized or high-level
disinfected.
Examples: mouth mirrors, amalgam condensers,
and reusable impression trays.
33. Non-critical Items
Contact intact skin.
Barrier protect or clean and disinfect (if visibly soiled)
using a low to intermediate-level
(i.e., tuberculocidal) disinfectant.
Examples: x-ray head or cone, facebows, blood
pressure cuff.
34. Special Considerations—Dental Handpieces
Follow manufacturer’s instructions to safely reprocess
dental handpieces and accessories (e.g., low-speed
motor, reusable prophylaxis angles).
Clean and heat sterilize between patient uses.
Do not subject the handpiece to high-level disinfection and do
not simply wipe the surface with a low-level disinfectant.
Special Considerations—Digital Sensors
Follow manufacturer’s instructions to safely
reprocess digital radiography equipment.
Ideally, barrier protection should be used,
followed by cleaning and heat sterilization
or high-level disinfection between patients.
35. Single-Use (Disposable) Devices
Intended for use on one patient during a single
procedure.
Usually not heat-tolerant.
Cannot be reliably cleaned.
Do NOT reprocess.
Examples: syringe needles, prophylaxis cups,
and plastic orthodontic brackets.
36. Environmental Infection Control
Clinical Contact Surfaces can be directly contaminated from patient materials either by
direct spray or spatter generated during dental procedures or by contact with DHCP’s
gloved hands.
• light handles
• switches,
• dental radiograph equipment,
• dental chairside computers,
• reusable containers of dental materials,
• drawer handles,
• faucet handles,
• countertops,
• pens,
• telephones,
• doorknobs.
37. Reducing aerosols
• One study found that ultrasonic
instrumentation can transmit 100,000
microbes per cubic foot up to six feet, and, if
improper air current is present, microbes can
last anywhere from 35 minutes to 17 hours.
• Preoperative mouth rinses with suitable
disinfectant help reduce infectious load
• use of high-velocity air evacuation
• by flushing waterlines at the beginning of the
workday and between each patient
• using air purifications systems (high efficiency
particulate air- HEPA filters)
• use of personal barrier protection such as
masks, gloves and eye protection
Aerosols are differentiated into:
• spatter (> 50 µm)
• droplet (≤ 50 µm)
• droplet nuclei (≤ 10 µm)
In dental settings, 90% of the aerosols
produced are extremely small (< 5 µm).
39. Sterilization of Diagnostic Instruments
• Dry the diagnostic instrument with
help of wipes. Only absolutely dry
instruments must be placed in the
sterilizer, in order to avoid calciferous
deposits and/or water spots.
Instruments are autoclaved at 121° C.
40. Sterilization of Impression Trays
• After the impression has been removed from
the metallic impression trays the trays are
washed with running water and are made free
from the particles adhering to it.
• The trays are the properly dried and placed in
autoclave for sterilization at 121° C.
41. Sterilization of Handpiece
• Moist heat using saturated water vapor's (autoclave) offers the best results as
regards the sterilization of handpieces in the short time.
42. Sterilization of Burs
• Step 1. meticulous cleaning to remove tooth debris,
residues of dental materials, blood clots or a paste-like
mixture with saliva of all the above.
• Step 2. After removal from the ultrasonic bath, burs must
be dried using absorbent paper and hot air.
• Step 3. They must then be placed in an appropriate device
for sterilization, depending on the material they are made
of.
• The most widely accepted cleaning method for burs and
other micro instruments are ultrasonic devices at a
temperature of about 60°C, burs vibrate at a frequency of
60-80 kHz for at least 15 minutes.
43. More specifically:
1) Burs made of common carbon steel should not be placed in the
autoclave because they will undergo oxidation.
2) Dry heat ovens, ovens for chemical vapor sterilization and ethylene
oxide ovens are suitable for sterilizing all types of burs. However, it may
seriously damage the cutting edge of the burs.
3) Using various aldehydes and phenols for at least 30 minutes offers
adequate sterilization while after 10 hours chemical sterilization is
achieved. Nevertheless, they may damage the integrity of rotating
cutting instruments.
44. Sterilization of Facebows & Bite forks
• Parts of facebow which are made of metal
can be sterilized in autoclave.
• It is important to note that earpieces of
facebow be removed before sterilization.
• Before facebow and bite fork is kept in
autoclave it is necessary to wipe it with dry
cloth.
• Facebow and bite fork can be autoclaved at
121⁰C.
45. Sterilization of Dental Implants.
• The following products are delivered non sterile:
Transfers, Analogs, Drivers, Overdenture, Abutments, Transfer
screws, Drill Extension, Parallel pin and plastic handle.
• Sterilization using Moist heat (autoclaving), Dry heat, Ethylene
Oxide (EtO), Vapor phase Hydrogen Peroxide (H 2 O 2), Low
temperature gas plasma, Glutaraldehyde solution, are some of
the techniques frequently used.
48. Different Impressions
• Alginate Impressions: can be done with 0.5%
sodium hypochlorite. Iodophores immersion
disinfection for prolonged periods will cause
distortion due to imbibition.
• •Agar- Reversible Hydrocolloid: Found to be
stable when immersed in 1:10 dilution sodium
hypochlorite or 1:2 iodophor. Recommended
immersion time is 10 minutes.
49. • Zinc Oxide Eugenol Immersion: It
can be disinfected in 2%
glutaraldehyde, Iodophores or Chlorine
compounds. Adverse effect have been
reported on ZOE immersed for 16
hours in diluted hypochlorite.
• Impression Compound: Immersion
in 1:10 dilution sodium hypochlorite or
iodophor for specified time period has
been found to be useful for disinfecting
impression compound, impressions.
50. • Polysulphide and Addition
Silicone: Glutaraldehyde,
Iodophor,0.5% sodium hypochlorite
should be used for its disinfection.
• Polyether: Spraying in iodophor, 0.5%
Sodium hypochlorite should be used.
Prolonged immersion causes distortion.
Polyether shows dimensional changes
on immersion in 2% glutaraldehyde.
51. Disinfection Of Wax Bites & Wax Rims
• Wax rims and wax bites should be disinfected
by the spray wipe spray method using an
iodophor. Rinse & spray may be more
appropriate for wax bites.
• After the second spray, they can be enclosed
in a sealed plaster bag for the recommended
time.
• These items should be rinsed again after
disinfection to remove any residual
disinfectant.
52. Disinfection Of Bite Registrations
• These registrations can be disinfected, using the
rinse spray rinse technique, with most hospital
level tuberculocidal disinfectants used as sprays
(chlorine compounds should not be applied to
ZOE).
• After disinfection, the registration should be
rinsed again to remove residual disinfectant.
53. Disinfection of Casts
• ADA recommends that stone casts be disinfected
by the spraying until wet or immersing in a 1:10
dilution of sodium hypochlorite or an iodophor.
• Casts to be disinfected should be fully set (i.e.
stored for at least 24 hours).
• Microwave irradiation of casts for 5 mins at 900W
gives high level disinfection of the gypsum casts
54. Disinfection Of Custom acrylic resin
impression trays
• Custom acrylic resin impression trays
should be disinfected by spraying with
surface disinfectants or immersing in
either 1:2 iodophor or 1:10 sodium
hypochlorite.
• They should be rinsed thoroughly to
remove any residual disinfectant and
allowed to dry fully before use.
56. CLINICAL MANAGEMENT DURING AND
AFTER COVID 19 PANDEMIC
Before Dental Procedure
• Ensure safety by getting vaccinated
• OFFICE SET UP – Remove all the clutter and things from the practice that
cannot be disinfected easily
• Schedule appointments with at least 30 mins between patients to minimise
possible contact with other patients in the waiting room and disinfect the
entire working area
• Request patients to come alone
• History of travel or any exposure or symptoms related to COVID-19 must be
discussed on phone or text before the patients comes into the clinic
• Appointments to be scheduled and spaced to avoid crowding the waiting area
57. During The Dental Procedure
• Hand Hygiene to minimize the risk of
contamination. Indications for hand hygiene
include :
a. when hands are visibly soiled
b. after barehanded touching of inanimate
objects likely to be contaminated by blood,
saliva, or respiratory secretions
c. before and after treating each patient
d. before donning gloves
e. immediately after removing gloves
• Prefer extraoral radiologic techniques
• Minimize aerosol production and its
distribution in the air
• Prefer manual instrumentation
58.
59. The Patient Treatment Area
• Areas and items of equipment local to the dental
chair that need to be cleansed between each patient
with 1% sodium hypochloride or 70% alcohol
• Disposable single-use covers are available for many
of the devices like inspection light handles and
headrests.
• For blood spillages, care should be taken to observe
a protocol that ensures protection against infection.
The use of hypochlorite at 1000 ppm available
chlorine is recommended.
• Keep the Air conditioning vent facing upwards, use
of air purifiers with HEPA filters.
• If the dental chairs are not six feet apart, then 2
patients should not be treated at the same time.
60. PPE
Masks, Protective Eyewear, and Face Shields
1. Wear a surgical mask and eye protection with
a face shield to protect mucous membranes
of the eyes, nose, and mouth during
procedures
2. Change masks between patients or during
patient treatment if the mask becomes wet
Protective Clothing
1. Wear protective clothing (e.g., reusable or
disposable gown) that covers personal
clothing and skin
Gloves
1. Wear a new pair of medical gloves for each
patient, remove them promptly after use
61.
62.
63.
64. Conclusion
Dentists must use effective infection control procedures in their practices. One
should determine and practice infection control and build upon them by
adding new procedures to the dental routine.
The implementation of correct procedures to mitigate cross infection and the
spread of SARS-CoV-2 in the dental office will improve the safety and restore
the confidence required to provide dental care to the population during the
COVID-19 pandemic.
65. Resources
CDC. Guidelines for Infection Control in Dental Health-Care Settings—2003
https://www.ida.org.in/Membership/Details/SterilizationandDisinfection
CDC. Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008
CDC. Summary of Infection Prevention Practices in Dental Settings: Basic Expectations
for Safe Care
Indian Dental Association PROTOCOL COVID-19
William A. Rutala and David J. Weber; Disinfection and Sterilization in
Health Care Facilities
