Asepsis sterilization and infection control /certified fixed orthodontic courses by Indian dental academy

ASEPSIS STERILIZATION AND
INFECTION CONTROL
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

• Sterilization: Complete destruction of all
micro-organisms on an inanimate object
or instrument.
• Disinfection : The destruction of
organisms in the non-sporing or
vegetative state.

INTRODUCTION
• The concept of asepsis and its role in the prevention of
infection was put forward nearly
• Two centuries ago. The general principles for asepsis
were laid down by Hungarian abstetrician, Ignaz
semmelweiss in europe in early 1850’s and Oliver
Holmes in USA. These principles were accepted after
Joseph Lister’s studies on prevention of wound infection
carried out between 1865-91. Lister, working on
antisepsis, initially used phenol (dilute carbolic acid) for
contaminated wounds, later applied it in all surgical
wounds, also in operating room by nebulization of the
solution. Further developments occurred with the
introduction of steam sterilization surgical masks, sterile
gloves, sterile gowns and drapes etc.

IMPORTANT DEFINITIONS
• ASEPSIS: It is the avoidance of pathogenic organisms from
coming in contact with the wound and other sites and
ensuring that only sterile objects and fluids come into contact.
• STERILIZATION: It is a process by which articles are freed
of all microorganisms both in vegetative or spore state.
• *DISINFECTION: It is a process, which reduces the number
of viable microorganisms to an acceptable level, but may not
in activate some viruses and bacterial spores.
• CDC Dental Guidelines For Sterilization Instruments -As
with other medical and surgical instruments, dental
instruments are classified into three categories - critical, semi
critical, or no critical - depending on their risk of transmitting
infection and the need to sterilize them between uses.

CLASSIFICATION OF METHODS
OF STERILIZATION
•
• A. PHYSICAL
• Sun Light
• Drying
•
• Heat
– Dry
– Moist
• Filtration
• Gas
• Irradiation
• Ultra sonic cleaning
• Oil

• B. CHEMICAL
• Phenol Derivatives : Phenol, Cresol, resorcinol,
chloroxylenol
• Oxidizing agents : Pot. Permanganate, Hydrogen
Peroxide, Benzoyol Peroxide
• Halogens : Iodine, chlorine
• Biguanide : Chlorhexidine
• Quarternary Ammonium (Cationic) : Cetrimide, Zephiran
• Soaps : of Sodium & Potassious
• Alcohols : Ethanol, Isopropanol.
• Aldehydes : Formaldehyde, Glutaraldehyde
• Acids : Boric acid, acetic acid
• Metallic salts ; Silver Nitrate, Zince Sulfate, Zinc Oxide,
calamine, Ammoniated mercury.
• Dyes : Gentian violet, proflamine, Acriflamine
• Furan derivatives : Nitro flurazonewww.indiandentalacademy.com

PHYSICAL METHODS
• Sunlight : Most old & still effective. It possesses
appreciable bactericidal activity. The action is due to
ultra violet rays. This is one of the natural methods of
sterilization in case of water in tanks, rivers and lakes.
• Drying : It air has deleterious effect on many bacteria.
Spores are unaffected by drying. Hence it is very
unreliable method.
• Heat : Is the most common and one of the most
effective methods of sterilization. Factors influencing
sterilization by heat are : -
– Nature of heat
• Dry
• Moist
– Temperature & time
– No of organism present
– Whether organism has sparing capacity
• Type of material from which organism is to be eradicatedwww.indiandentalacademy.com

• DRY HEAT
• Killing is due to :
• Protein denaturation
• Toxic effects of elevated levels of electrolytes
• a. Red Heat : It is used to sterilize metallic objects by holding them in
flome bill they are red hot. Example : inoculating wires, needles, forceps
etc.
• b. Flaming : The article is passed over flame without allowing it to
become red hot. Example : Glass plates, Cotton wool plays and glass
slides.
• c. Hot Air Oven: It is used to sterilize items, which do not get damaged by
high temp. such as laboratory glass wave, flasks, scissors, impression trays
(metal), all stainless steel instruments with sharp cutting edges, (preferred)
B.P. handles, Dapen dishes, mouth mirrors and poles. Hot air is poor
conductor of heat and poor penetrating capacity. So grease, oils, powders
plastics, rubber-containing substances should be sterilized by other
methods. High temp. can damage fabrics or melt them.
• Temp. & Time: The sterilization is complete if these two factors are
achieved throughout the load.
• Temp. Time (Min.)
• 160oC 320oF - 120/60
• 170oC 340oF - 60
• 150oC 300oF - 150
• 140oC 280oF - 180

• Precautions
• The heat should be uniformly distributed in side the
oven.
• All the instruments must be clean of dry prior to
wrapping.
• It should not be over loaded.
• Oven must be allowed to cool for about 2 hours before
opening other wire glass will crack.
•
• Sterilization Control of Hot Air Oven
• Detectors as spores of non-pathogenous strains of
clostridium tetani are used to test dry heat efficiency.
• Browne’s tube (green spot) is available for checking
sterilization by dry heat. A green color is produced after
60 min. at 160oC.
• Thermocouples may be used.

• GLASS BEADS STERILIZER:
• This method employs a heat transfer device.
The media used are glass beads, molten metal
and salt. The temperature achieved is of
220oC. The method employs submersion of
small instruments such as endodontic files and
burs, into the beads; and are sterilized in 10
seconds provided they are clean. A warm-up
time of at least 20 minutes is recommended to
ensure uniform temperatures in these sterilizers.
• Some hand piece can be sterilized by dry
heat. The hand pieces should be carefully
cleaned and lubricated with special heat
resistant oils.

•
• MOIST HEAT:
• Effective by denaturation and coagulation of
proteins.
•
• a. Temperature below 100oC.
– Pasteurization – milk by Hold Method and Flash Method.
– Vaccine bath – for vaccines
– Inspissation
•
•
• b. Temperature at 100oC
• Tyndallization
• Boiling
• Steam Baths
•
• c. Temperature above 100oC

• AUTOCLAVE
• These are three major factors required for effective
autoclave ; Pressure, temperature and Time.
• Pressure: It is expressed in pressure (Pounds) pre
square inch and it is 15-PSI pressure.
• Temperature: To achieve required pressure, the
temp. must be reached and maintained at 121oC with
the increase in temperature and pressure super heated
steam is formed and removed Air from chamber and this
brings about sterilization.
• Time: Wrapped loads require a minimum of 20 min.
after reaching full temperature
• and time cycle, a wide variety of materials can be
sterilized by this method.
• Example: Diagnostic and prognostic Instruments, plastic
filling Instrument, impression trays, laboratory
equipments, surgical instruments etc. Higher
temperature and greater pressure shorter the time
required for sterilization.www.indiandentalacademy.com

•
• also varies with the amount of material for
the thickness of the wrap.
Pressure Temperature Time (Min.)
15psi 121oC 15
20 psi 126oC 10
20 psi 134oC 3

. IRRADIATION
• Radiation used for sterilization is of two
types
• Ionizing radiation, e.g., X-rays, gamma
rays, and high speed electrons and
• Non-ionizing radiation, e.g. ultraviolet light,
and infrared light. These forms of
radiation can be used to kill or inactivate
microorganisms

• It is effective for heat labile items.
Bellamy (1959) reported that it has great
penetrating properties. It is commonly
used by the industry to sterilize disposable
materials such as needles, syringes and
swabs.
Ionizing Radiation

Ultraviolet
• It is absorbed by proteins and nucleic acids
and kills microorganisms by the chemical
reactions it sets up in the bacterial cell. It has
low penetrating capacity and its main application
is purification of air in operating rooms; viz, to
reduce the bacteria in air, water and on the
contaminated surfaces. All forms of bacteria
and viruses are vulnerable to ultraviolet rays
below 3000 atmospheric pressure. Excessive
exposure of skin can produce serious burns.
Care must be taken to protect the eyes while
using U-V radiation for sterilization.

ULTRASONIC CLEANING
• Several studies have shown that, when
performed correctly, ultrasonic cleaning
will remove dried serum, whole blood,
plaque, zinc phosphate cement, and
polycarboxylate cement from instruments,
metal surfaces and dentures. It has been
found to be more effective than manual
cleaning.

ULTRASONIC CLEANERS AND
SOLUTIONS
• The Clinical Research Associates (CRA)
recommended the following ultrasonic
cleaners:
• BIOSONIC – Whaledent
• T33C – Health Sonics Group
• CLOSTER 3 – Provides ultrasonic clean,
rinse and dry, but is noisy

OIL
• Hot oils baths have been used for
sterilization of metallic instruments. At a
temperature of 175oC, submersion for 15
minutes is required for sterilization. The
disadvantages of using oil include; poor
penetration, poor sporicidal activity, presents a
fire hazard, and is difficult to remove from
instruments such as hand pieces without
recontamination. It should not be used for
hypodermic syringes or needles because of the
danger of oil embolization

CHEMICAL METHODS
• ALDEHYDE COMPOUNDS
• Aqueous solution of formaldehyde
(formalin) and
• Glutaraldehyde (cidex) are effective
disinfectants

ALCOHOLS
• Ethanol and isopropyl alcohols are frequently
used as antiseptic. Alcohols possess some
antibacterial activity, against some Gram-
positive and negative bacteria, and especially
against M tuberculosis. Alcohols act by
denaturing proteins. They are not effective
against spores and viruses.
• The alcohols do not function as disinfectants
when instruments, hand pieces, or other
equipment are simply wiped with them, since
they evaporate quickly

PHENOLIC COMPOUNDS
• Phenol itself toxic to skin and bone
marrow. The phenolic compounds were
developed to reduce their side effects but
are still toxic to living tissues. These
compounds, in high concentration, are
protoplasmic poison, and act by
precipitating the proteins and destroy the
cell wall.

AQUEOUS QUARTERNARY
AMMONIUM COMPOUNDS
• Benzalkonium chloride (Zephiran) is
the most commonly used antiseptic. Its
spectrum of activity is primarily Gram-
positive bacteria. It is well tolerated by
living tissues. It is not widely used
because of its narrow spectrum of activity

IODOPHOR COMPOUNDS
• These compounds are effective against most
bacteria, spores, viruses, and fungi. These are
the most commonly used surface disinfectants
along with hypochlorite. Concentrated solutions
have less free ioidine. Iodine is released as the
solution is diluted. An appropriate dilution is 1 :
2 : 3 parts of iodophor and distilled water,
respectively.
• Advantages are
• Low toxicity.
• Prolonged residual effect
• Inexpensive and
• Odorless.

ASEPSIS IN DENTISTRY:
BARRIER TECHNIQUES

GLOVES
• PRACTICAL POINTS ESSENTIAL FOR
GLOVE USE
• Wash hands before doing gloves
• Choose a glove that fits tightly
• Replace gloves immediately if born
• Ensure chair side assistants wear gloves
• Wash hands immediately after glove removal.
• Treat gloves as surgical waste and dispose of
them accordingly.

• OSHA ADVISE THE FOLLOWING
CONCERNING GOWNS
• 1.The clinic attire should be worn only in
the dental environment and should be
changed at the end of the treatment
schedule. 2. The day should begin with
freshly laundered garments and the
garments should be changed immediately
it soaked or spattered with blood or other
contaminants.3. Clinic attire should be
handled separately from family laundry.

MASKS
• PROPER MASK SHOULD BE
• Fit comfortably
• Not look air out the sides
• Fit around the entire periphery of the face
• Not touch lips or nostrils
• Not irritate skin
• Provide breath ability
• Not cause jogging or protective eyewear.
• Not have an object able odor.

• PROTECTIVE EYE WEAR
• Protective eyewear in combination with
a mask must be worn to protect the eye
when spatter and splash of body fluids is
anticipated and a fan shield is not used

ANTISEPTICS USED IN HAND
WASHING
• Chlorhexidine: i.e. 2-4% Chlorhexidine gluconate
with 4% isopropyl alcohol in a detergent solution with
a pH of 5.0 to 6.5.
• Povidone iodine: 7.5 to 10% Povidone iodine (3
minutes duration)
• Phenolic compound: Hexachlorophene (it is toxic if
the blood concentration rises with repeated exr.)
Parachlorometexylenol (is bactericidal and fungicidal at
2% concentration).
• Alcohols: Ethyl alcohol and isopropyl alcohol used
in 70% concentration
•

• FOOTWEAR
• A pair of smooth, ship on shoes should be
kept exclusively for use in the surgery. These
should be cleaned at the end of each clinical
session.
• HEAD COVERS
• Head covers provide an effective barrier.
They are recommended during invasive dental
procedures, which are likely to involve extensive
blood splatter.

• DRAPING THE PATIENT
• The purpose of draping a patient is to
isolate the field of surgery from other parts
of body that have not been prepared for
surgery, and also from non-sterile
equipment and equipment.

DISINFECTION OF
IMPRESSIONS
• Immersion disinfection has been preferred to
spraying. This is based on the assumption that
immersion is more likely to assure exposure of
all surfaces of the impression to the disinfectant
for the recommended time.
• Spraying disinfectants onto the surface of the
impression reduces the chance of distortion,
especially in the case of alginate, hydrocolloid,
and polyether materials, but may not adequately
cover areas of undercut. Two studies have
indicated that there is no difference in accuracy
of casts obtained by spraying with or immersion
in recommended disinfectants.

• Thorough rinsing of the impression is
necessary before and after disinfection.
Rinsing before re moves the bioburden
present, which may exposure of the
surface to the disinfectant. Rinsing after
disinfection removes residual disinfectant,
which may affect the stone surface after
casting.

• ADA recommended disinfectants must be
used.
• Chlorine compounds
• Iodophors
• Combination synthetic phenolics
• Glutaraldehydes
• Distortion of impressions following
disinfection is determined by the brand of
impression material and the disinfectant
used.
• When an alginate is disinfected the choice
of product is very important.www.indiandentalacademy.com

POLYSULPHIDES AND
ADDITION-CURED SILICONES
• Addition-cured silicone materials appear
to be able to withstand damage by
disinfectants, exception of neutral
glutaraldehyde.
• Alternative disinfectant: iodophore

Immersion of alginate
• Immersion of alginates in disinfectants is very much
dependant on the product used.
• Algioplast and New Kromopan may be immersed in
sodium hypochlorite solution (1:10) for 10 minutes
without distortion.
• Jeltrate Plus may be immersed in iodophor (wesco-
dyne) for 10-15 minutes, or for 10 minutes in sodium
hypo chlorite, without distortion.
• It is strongly recommended that alginate impressions are
cast as soon as possible after disinfection. This is
possible if the dental office has its own laboratory, but
difficult if commercial laboratories are employed.

IMPRESSION TRAYS
• If plastic disposable trays are used, the handle
is removed and heat sterilized.
• If aluminum or chrome-plated trays are used,
routine examination of the trays is essential to
monitor corrosion if sodium hypochlorite is
used. If corrosion occurs, use an alternative
disinfectant.

CHOICE OF DISINFECTANT
• METAL DENTURES
• Some concern has been expressed over the use
dilute sodium hypochlorite on metal dentures.
Recent research indicates that the use of
sodium hypochlorite for 10 minutes will not
damage denture base metals. One study
recommends 2% hypochlorite 1: 5 for 5 minutes,
as 1% does not remove all micro-organisms
• Iodophor or 1:10 diluted sodium hypochlorite be
used for single or infrequent disinfection cy
However, both disinfectants should be used :;are
as either can be corrosive with repeated or
prolonged exposure

ACRYLIC DENTURES
• Sodium hypochlorite is recommended for
disinfection of complete acrylic dentures.
Glutaraldehyde with phenolic buffer (Sporacidin)
should not be used.
• “In-office” adjustments
• Care must be taken with in-office adjustments.
Use sterilized rag wheels and unit doses of
pumice and polishing compounds. These will
prevent cross contamination of prostheses and
the need for multiple disinfections when repeat
try-ins are necessary

BURS
• Steel Burs:- Single use. Dispose of these
in Sharps bin
• Diamond Burs
• Clean with bur brush.
• Place in ultrasonic bath.
• Dry, bag and autoclave.

DISPOSAL OF WASTES
• Contaminated sharp disposable objects, (broken
glass, disposable sharp blades), must be
handled with extreme care to avoid injuries.
They must be placed in a rigid impervious
container which can be sealed prior to disposal.
• Liquid wastes should be disposed of by carefully
pouring into the mains drainage system followed
by a free flow of running water.

• CONCLUSION
• Prevention is better than cure. The main way
of control is by discarding all the contaminated
instruments and materials and try to use as much
as disposable items. The dentist and assistant
should take proper vaccination in proper time. It
should be done any treatment with minimal
instruments using.
• The material, which is sent to the laboratory,
should be disinfected before the technician
contact it should be kept in a separate room for
disinfection, for all the patients’ work, which is
sent. For each patient the material used should
be separate or it should be discarded after each
patient work or disinfect it before use of it.

• The dentist should not think only their
health, they should consider the
environment also when the dispose of the
used materials. They should be
discarded in sturdy, impervious plastic
bags to minimize human contact. Blood
and disinfectants be carefully poured into
a drain connected to a sanitary sewer
system. Sharp instruments should be
paced in puncture resistant containers
marked with the bio hazard label.

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Asepsis sterilization and infection control /certified fixed orthodontic courses by Indian dental academy

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