4. strelization and infection control

Presented by
Dr. Neetu Singh
Sterilization and infection control

:
Introduction
Important definition
Classification
Classification of methods of sterilization
Asepsis in dentistry : Barrier techniques
Infection control in dental clinic
From prosthetic point of view
Infection control
Conclusion
References
Contents

The concept of asepsis and its role in the prevention of
infection was put forward nearly Two centuries ago..
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.
INTRODUCTION

General principles of asepsis are laid down by
Hungarian physician, Ignaz semmelweiss in
Europe in early 1850’s and Oliver Holmes in USA.
These principles were accepted after Joseph Lister
(Father of antiseptic surgery) studied prevention
of wound infection(1865-1891).
C. P. Baveja.,Text book of microbiology. 2nd edition. Arya
publication

In present days certain guidelines and regulations are
recommended by accepted bodies, which have to be followed in
dental practice and up graded in every general body meeting.
Guidelines are given by
• American Dental Association (ADA),
• Centers for Disease Control (CDC)
• British Dental Association
Advisory service to name few and regulations by Environmental
Protection Agency (EPA),
Occupational Safety and Health Administration (OSHA) and
Health and Safety at Work act 1974
Infection control recommendation for the dental office and dental laboratory- JADA
78;3:1998

DEFINITIONS
CLEANING - It is a process which removes visible
contamination but does not necessarily destroy
micro organisms.
It is necessary prerequisite for effective disinfection
or sterilization.
ASEPSIS -Term used to describe methods which
prevent contamination of wounds and other sites, by
ensuring that only sterile object and fluids come into
contact with them.
Text book of microbiology by Ananth Narayan

ANTISEPSIS - It is the procedure or application of
an antiseptic solution or an agent which inhibits
the growth of microorganisms, while remaining in
the contact with them.
 DISINFECTION - it is a process which reduces the
number of viable microorganisms to an acceptable
level but may not inactive some viruses and
bacterial spores.
STERLIZATION - it is the process of destruction or
removal of all microorganisms from article, surface
or medium, including spores.
Text book of microbiology by Ananth Narayan

 critical,
 semi critical,
 or non critical
depending on their risk of transmitting
infection and the need to sterilize them
between uses.
Dental instruments are classified into three categories –
Each dental practice should classify all instruments as follows: As per May 28, 1993

Critical Semicritical Noncritical
SpauldingClassification

INSTRUMENT CLASSIFICATION
Critical instruments Semi-critical instruments Non-critical instruments
(I) Critical instruments:
• Are instruments that penetrate soft tissues or bone
• Critical instruments must be heat sterilized between each use or
disposable items (eg. Scalpel) are used.
Eg. Periodontal probes
Explorers
Scaling or root planning instruments tip insert of an ultrasonic scaling
unit.
Periodontal probe

(II) SEMI-CRITICAL INSTRUMENTS:
• Are not intended to penetrate soft tissues or bone but come into contact
with oral fluids.
Eg. Ultrasonic scaling handpiece
Mouth mirror
Impression trays
Oral photography retractor
Two methods
Heat Sterilization Chemical disinfectants
(Eg. germicides)

(iii) Non-critical instruments:
Are those items that come into contact only with intact skin
Eg. Light handle
• High and low volume evacuators
• Tubing for handpieces
• Instrument trays
• Chair surfaces

To achieve sterilization of any instrument
three definite stages are to be completed-
 Pre sterilization cleaning
 Sterilization process
 Aseptic storage

PRE STERILIZATION CLEANING
Objective-
Removal of the organic matters, blood
and saliva which provide protective
barrier for microorganisms and
prevents its destruction.
There are three methods for cleaning
-Manual
-Ultrasonic
-Mechanical washing

MANUAL CLEANING
Simplest and the cheapest method, but
time consuming and difficult to
achieve.
Heavy duty gloves and glasses must be
worn to protect needle stick injury and
to protect eye.
Material used for manual cleaning
-Soaps
-Detergents

ULTRASONIC CLEANING
Principle- conversion of electrical energy
into vibratory sound waves which pass
through a soap solution containing the
instrument.
Used mainly for burs, bone files, bone
cutter, artery forceps, saw etc.
CYCLE:- usually 6 mins, if cassest then
12 min

DECONTAMINATING INSTRUMENTS
WITH AN ULTRASONIC CLEANSER
PRIOR TO STERILIZATION
Equipments:
 Nitrile gloves
 Face mask and protective eye wear
 Cleaning solution
 Contaminated instruments
 Instruments cassette
Ultrasonic cleaning unit
Decant holding
solution into sink
Drain excess water

Immerse instrument cassette
into ultrasonic cleaner solution
Set ultrasonic cleaning unit
time
Lift basket to drain excess
solution
Rinse instrument cassette

MECHANICAL WASHING
Principle- High-pressure jets of
water with or without a detergent
which removes debris from
instrument.
Small instrument like burs, blade
are not suitable for this type of
cleaning.

Classification of the method of
sterilization/Disinfection
A. PHYSICAL
1- Sun Light
2- Drying
3- Heat i- Dry
ii-Moist
4- Filtration
5- Gas
6- Irradiation

B. CHEMICAL
1. Phenol Derivatives : Phenol, Cresol, resorcinol, chloroxylenol
2. Oxidizing agents :Pot.Permanganate, Hydrogen Peroxide,Benzoyol
Peroxide
3. Halogens : Iodine, chlorine
4. Biguanide : Chlorhexidine
5. Quarternary Ammonium (Cationic) : Cetrimide, Zephiran
6. Alcohols : Ethanol, Isopropanol.
7. Aldehydes : Formaldehyde, Glutaraldehyde
8. Acids : Boric acid, acetic acid
9. Metallic salts ; Silver Nitrate, Zince Sulfate, Zinc Oxide, calamine,
10. Dyes : Gentian violet, proflamine, Acriflamine
11. Furan derivatives : Nitro flurazone

HEAT
Most common and one of the most effective methods of sterilization.
Factors influencing sterilization by heat are : -
i. Nature of heat
a. Dry
b. Moist
ii.Temperature & time
iii. No. of organism present
iv.Whether organism has sporing capacity
v. Type of material from which organism is to be eradicated

A. DRY HEAT
Killing is due to :
- Dehydration and oxidation of organisms
- Protein denaturation
- Toxic effects of elevated levels of electrolytes
1. Red Heat : It is used to sterilize metallic objects by
holding them in flame till they are red hot. Example :
inoculating wires, needles, forceps etc.
2. Flaming : The article is passed over flame without
allowing it to become red hot. Example : Glass plates,
mouth of culture tubes and glass slides.

3. Hot air oven :
It is used to sterilize items, which do
not get damaged by high temp.
such as laboratory
glass,
flasks,
instruments with sharp cutting edges,
B.P. handles,
Powders,
Dapen dishes,
mouth mirrors.

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
otherwise glass will crack.

Temp. & Time: The sterilization is complete if these two
factors are achieved throughout the load.
Temperature Time(Min)
140oC 180
150oC 150
160oC 60
170oC 45
180oC 18
190oC 7.5

Sterilization Control of Hot Air Oven
• The spores of non-toxigenic strain of Bacillus subtilis and
Clostridium tetani are used as a microbiological test of dry heat.
• Browne’s test strip available that contain a chemical indicator.

MOIST HEAT STERILISATION
This method of sterilisation may be used at different
temperature as follows
At temp below 100 c
At a temp of 100 c
At a temp above 100 c

B. Moist heat
Causes denaturation and coagulation of proteins.
1. Pasteurization : below 100 c
The temperature employed is either 630C for 30mins (Holder method) or
720C for 15-20 seconds (Flash method) followed by cooling quickly to
130C.
Method is used for heat sensitive liquid and pharmaceutical products.
2. Tyndallisation : at 100c
Named after John Tyndall.
Exposure of 1000C for 20 min for 3 successive day.
Principle: 1st exposure kills all vegetative bacteria & spores, since they are
in a favorable medium, will germinate and be killed on subsequent
occasions.

Auto Clave: above 100c
Most common method in dental office
1210C for 20 minutes
To sterilize heat stable instruments
To Avoid corrosion Crawford
and Oldenburg recommended
addition of ammonia to the
autoclave

AUTOCLAVE :
Steam is the effective means of sterilization, because of its
1. High penetrating capacity.
2. It gives of large amount of heat to surface with which it comes in
contact.

Autoclaves, or steam sterilizers essentially consist of following:
i) A cylindrical or rectangular chamber, with capacities ranging from 400 to
800 liters.
ii) Water heating system or steam generating system
iii) Steam outlet and inlet valves
iv) Single or double doors with locking mechanism.
v) Thermometer or temperature gauge
vi) Pressure gauges

WRAPPING INSTRUMENTS FOR AUTOCLAVING
Instruments must be clean, but not necessarily dry.
Closed (non-perforated) containers (closed metal trays, capped glass
vials) and aluminium foils cannot be used, because they prevent the
steam from reaching the inner sections of the packs.
Cassettes, drums, trays with opening on all sides may be used.
Packaging used for autoclaving must be porous, to permit steam to
penetrate through ; and reach the instruments.
The materials used for packaging could be fabric or sealed biofilm/paper
pouches, nylon tubing, sterilization wrap, and paper wrapped cassettes.
The bag or wrap is sealed with tape.

Notes:
1. Use distilled water or deionized water instead of water from community supply
(because hard water leaves deposits on instruments).
2. Avoid use of sealed or closed containers or aluminium foil for packaging
materials because there is no direct contact of steam.
Close-up of autoclave
showing gauages.
Packages loaded
into autoclave.
Nitrile- gloved and
washing interior of
autoclave for
maintenance care.

USES
To sterilise culture media, rubber material,
gowns, dressing, gloves etc.
It is particularly useful for materials which cannot
withstand the higher temperature of hot air oven.
For all glass syringes, hot air is a bettter
sterilising method.

Unsaturated chemical vapor
sterilizer:
Similar to autoclave but in
place of stream, a chemical
vapor is generated under pressure.
Chemiclave

4. GLASS BEADS STERILIZER :
•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,artery forceps,scissors and burs, into the beads;
and are sterilized in 10 seconds provided they are clean.
•A warm-up time of at least 20 minutes to ensure uniform
temperatures in these sterilizers.

FILTRATION
Help to remove bacteria from heat labile
liquids.
As viruses pass through ordinary filters, it
can be used to obtain bacteria free
filtrates of virus isolation.
TYPES:
Candle filter
Asbestos filter
Sintered glass filter
Membrane filter

USES OF FILTRATION
1. To sterile sera, sugars and antibiotics
solutions
2. Separation of toxins and bacteriophages from
bacteria.
3. Purification of water
4. Filter discs retain the organism which can be
cultured e.g testing of water samples for
cholera vibrios or typhoid bacilli

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

1. Ionizing Radiation
X-rays, gamma rays and cosmic rays are highly
lethal to DNA and other vital constituents.
They have high penetration power.
There is no appreciable increase in temperature,
thus referred to as cold sterilization.
Commercial plants use gamma radiation for
sterilizing plastics, syringes, swabs, catheters etc.
.M. R. Cleland, X-Ray Processing: A Review of the Status and Prospects, Radiation
Physics and Chemistry, Vol. 42, Nos. 1-3, pp. 499-503, 1993.

2. Non-ionizing radiation
Two types of non-ionizing radiations are used for sterilization:-
A. Ultraviolet -
Short range UV is considered “germicidal UV”.
At a wavelength of 240 nm to 280 nm UV will destroy micro-
organismal DNA.
Used mainly for air purification and water purification in
hospitals.
B. Infrared –
It is most commonly used to purify air, such as in the operating
room. Infrared is effective, however, it has no penetrating
ability.

ETHYLENE OXIDE STERILIZATION
(ETO)
Used almost exclusively to sterilize
medical products that cannot be steam
sterilized or sensitive to radiation.
Mechanism of action: It destroys
micro-organisms by alkylation and
cause denaturation of nucleic acids of
micro-organisms.
At 30 °C - 60°C with relative humidity
above 30 % and gas conc. between 200
and 800 mg/l for at least 3 hours.

Ethylene oxide is a colorless liquid with a
boiling point of 10.7 °C.
 Highly penetrating gas with sweet ethereal
smell.
Highly inflammable & in conc. greater than
3%, highly explosive.
By mixing with inert gases such as CO2,
explosive tendency is eliminated.
Plastics, rubber & photographic equipments
can be sterilized by this method.
Also used for mass sterilization of
disposable items, plastic syringes, needles,
catheters,blades etc.

Disadvantages
– Lengthy cycle time
– Cost
– Potential hazards to patients & staff
Advantage:
Can sterilize heat or moisture sensitive medical
equipments.

CHEMICAL METHODS
No available chemical solution will sterilize instruments
immersed in it.
Secondly, there is a risk of producing tissue damage if residual
solution is carried over into the wound while it is being used.

Mechanism of action of chemical disinfectants :
The mechanism of action of most of the chemicals are
nonspecific and complex but most of them effect
microorganisms by one of the following mechanisms.
1. Cell membrane injury.
2. Coagulation and Denaturation.
3. Interactions with functional groups of proteins.

1. ALDEHYDE COMPOUNDS
a. Formaldehyde:
Commonly called formalin
A broad-spectrum antimicrobial agent, used for disinfection,
has limited sporicidal activity.
Hazardous substance, inflammable and irritant to the eye,
skin and respiratory tract.
USES:
Preservation of tissue for historical examination.
To sterilise bacterial vaccine.
To prepare toxoid from toxin.
Formaldehyde in dentistry: a review of mutagenic and carcinogenic potential.
Lewis BB, Chr.esten SB J AM Dent Assc. 1981 Sep;103(3):429-34.

STUDY ON FORMOCRESOL
For many years there has been controversy over the value
of antimicrobial drugs for intracanal dressings in
endodontic.
Formaldehyde has a known toxic mutagenic and
carcinogenic potential.
Many investigations have been conducted to measure the
risk of exposure to formaldehyde; it is clear that
formaldehyde poses a carcinogenic risk in humans.
There is a need to reevaluate the rationale underlying the
use of formaldehyde in dentistry particularly in light of
its deleterious effects.
Formaldehyde in dentistry: a review of mutagenic and carcinogenic potential.
Lewis BB, Chr.esten SB J AM Dent Assc. 1981 Sep;103(3):429-34.

Glutaraldehyde:
It is a high level disinfectant
• A solution of 2% glutaraldehyde (Cidex),
requires immersion of 20 minutes for
disinfection
• 6 to 10 hours of immersion for sterilization.
USES:
• For sterilisation of endoscopes and
bronchoscope
• Face mask
• Corrugated rubber anaesthetic tubes and
metal instruments
• Hardener in x-ray film processing.

Stonehill et al (1963) reported that
glutaraldehyde kills vegetative bacteria, spores,
fungi and virus by alkylation on a 10-hour
contact.
It is activated by addition of sodium bicarbonate,
but in its activated form in remains potent only
for 14 days
It is toxic, irritant and allergenic. It is a high level
disinfectant. It is applicable where heat cannot
be used.

2. ALCOHOLS
Act by denaturing bacterial proteins.
Solutions of 70% ethanol are more effective than higher
concentrations, as the presence of water speeds
up the process of protein denaturation as reported
by Lawrence and Block (1968).
Frequently used for skin antisepsis prior to needle
puncture.
Isopropyl alcohol is preferred as it is a better fat solvent,
more bactericidal and less volatile.
Used for disinfection of clinical thermometer .

3. IODOPHOR COMPOUNDS
Many studies have shown, that, iodophor
compounds are the most effective antiseptics.
Iodine is complexed with organic surface-active agents,
such as, polyvinylpyrrolidone (Betadine, Isodine).
Their activity is dependent on the release of iodine from the
complex.
These compounds are effective against most
bacteria, spores, viruses, and fungi. These are the most
commonly used surface disinfectants along with
hypochlorite.

4. Biguanide :
Most commonly used biguanide
compound is chlorhexidine.
It is a powerful non-irritating antiseptic that
disrupts bacterial cell membrane.
It persists on skin for longer period of time and
that is why it is extensively used for
surgical scrubbing,
neonatal bath,
mouth wash and a general skin anti-septic.

5.HYDROGEN PEROXIDE
Strong oxidant.
Oxidizing properties allow it to destroy wide
range of pathogens.
Biggest advantage is short cycle time.
Used in 35% to 90% concentration.
• Uses:-Disinfect Small Wounds.
• Whitening Tooth
• Antiseptic Mouth Rinse. ...
• Disinfect Toothbrushes. ...

 Immersion disinfectant-
Glutaraldehyde
iodophore
 Surface disinfectant-
 Bleach (sodium hypochlorite)
 Phenolic disinfectant
 Quaternary Ammonia compounds
/disinfectants
 Iodophor disinfectant
• DISINFECTANTS USED
Infection control in the prosthodontic laboratory
Vidya S. Bhat , Mallik a S. Shet t y, Kam alak ant h K. Shenoy

58
ALL DISINFECTION PROCEDURES SHOULD BE DONE
IN DENTAL OPERATORY PRIOR TO DELIVERING
PROSTHESIS TO LAB
INCOMING ITEMS
 Annotate the DD Form 2322:
“Disinfected with ______ for
_____minutes”
HANDLING OF WORK RECIEVED IN
LABORATORY

 Label the plastic
bag with dispatch
date & mention :
“This case shipment has been
disinfected with ______for_____
minutes”
OUTGOINGITEMS

Follow dental materials’
manufacturers
instructions regarding
disinfectants
Do an in-office “test run”
before using new
combinations of
impression materials and
disinfectants
IMPRESSIONS

DISINFECTING IMPRESSIONS
TECHNIQUES OF DISINFECTION :-
Immerse/ dip
Spray (Rinse impression Place impression in bag
spray with disinfectants Seal bag to create charged
atmosphere)
 Spray tech. is probably not as effective as immersion

4. strelization and infection control

POLYSULPHIDES Use immersion in disinfectants of proven effectiveness*
SILICONES Use immersion in disinfectants of proven effectiveness*
POLY ETHERS Use immersion in disinfectants of proven effectiveness*
ALGINATE Use immersion in disinfectants of proven effectiveness* or
spray with adequate coverage with disinfectants
AGAR
Use immersion in hypochlorite, iodophore or glutaraldehyde
with phenolic buffer
STONE CAST
Use immersion in hypochlorite, iodophors, alternately use
spray disinfectants
ZINC OXIDE EUGENOL Use immersion in glutaraldehyde or iodophor.
TABLE 1 DISINFECTION OF IMPRESSIONS AND STONE
CASTS
*Disinfectants: Chorine compounds, hypochlorite,
glutaraldehyde/phenolic combinations, 2% acidic glutaraldehydes, 2%
alkaline glutaraldehydes, 2% neutral glutaraldehydes, idophors, and
phenolic alcohol cominations.

ALGINATE
Alginate is a complete carbohydrate that imbibes
water.
Immersion disinfection for long periods will cause a
distortion of alginate impressions due to the intake of
water and the action of the disinfectant.
Avoid prolonged immersion.

THE EFFECT OF STEAM STERILIZATION ON THE
PROPERTIES OF SET DENTAL GYPSUM MODELS.
study was to investigate the viability of autoclave sterilization of set dental
gypsum models.
The effects of autoclaving on the strength, surface hardness and dimensions of
specimens of plaster, stone and diestone were investigated.
In addition, sodium succinate was used to minimize any changes produced by
autoclaving.
It has been shown that dental gypsum casts can be successfully steam sterilized.
The results showed that for fully-dried gypsum products, autoclaving at 132
degrees C for 5 minutes rendered the casts unacceptable for use.
Autoclaving at 121 degrees C for 16 minutes had less effect although casts were
still not satisfactory, with the main problems being excessive expansion for
plaster and significant strength and surface hardness loss for stone and diestone.
Matyas J, Dao N, Caputo AA, Lucatorto FM. Effects of disinfectants on dimensional
accuracy of impression materials. J Prosthet Dent 1990;64:25-31.

IMPRESSION TRAYS
A L U M I N U M -
♪ Heat sterilize via autoclave
♪ Chemical vapor or dry heat
♪ Ethylene oxide sterilization
C H R O M E - P L A T E D -
♪ Same As above
C U S T O M A C R Y L I C R E S I N -
♪ Discard after use
♪ Disinfect if it reused in same patient
P L A S T I C –
D I S C A R D A F T E R U S E

DENTAL CAST DISINFECTION
Prefer disinfection of
impression
To Disinfect cast
Spray with iodophor or chlorine
product then rinse
Another option
Soak casts for 30 minutes in 0.5% conc. of
sodium hypochlorite and saturated calcium
dihydrate solution(SDS)

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.
Other studies conclude that sodium hypochlorite should not be used and that
iodophors are the first choice disinfectants.
Iodophor or 1:10 diluted sodium hypochlorite be used for single or infrequent
disinfection
However, both disinfectants should be used are as either can be corrosive with
repeated or prolonged exposure.
Effect of denture cleansers on metal ion release and surface roughness of
denture base materials. Braz. Dent. J. vol.23 no.4 Ribeirão Preto 2012

ACRYLIC DENTURES
Sodium hypochlorite is recommended for disinfection of complete
acrylic dentures.
Bleach
Vinegar
Baking soda mouthwash
A study by de sousa porta 2013 evaluated the use of soak in bleach
for 3 min i.e sodium hypochroride 5.25 % in 1:10 for 90 days. He
found redution in number of microorganisms, including candida.
There was no significance color change and surface roughness was
observed

DIRECTIONS FOR USE
Before using Nitradine® Seniors, brush, cleanse
and rinse the denture as usual.
Immerse the denture in a glass of lukewarm water
(approx.150ml), or in a Sonic Denture Cleaner
filled with lukewarm water.
Add one tablet to the water.
Make sure the denture is fully covered with water.
For regular bacteria and yeast infection, allow the
denture to soak for 15 minutes in the solution.
To ensure that your denture is free of all viruses,
soak your denture for 1 hour in the solution.
Remove the denture from the solution and rinse
well under water before replacing the denture in
the mouth.
If a taste should remain on your denture after
replacing it in your mouth, place the denture in
lukewarm water for 10 minutes.

DISINFECTION OF ORALLY
SOILED PROSTHESES
PROCEDURE
Scrub prosthesis
(with brush & soap)
Place in sealable plastic bag
containing ultrasonic cleaning solution
Cover ultrasonic cleaner (4-5mins)
Remove and rinse

 Use spray disinfection (idophor)
 Heavy-body bite registration materials
can be disinfected in same manner as an
impression of the same material
WAX BITES/RIMS,
BITE REGISTRATIONS

DISINFECTION
Alcohol torch,
facebow,
articulator,
mixing spatula,
mixing bowl,
lab knife,
shade/mold guide
should be disinfected (by spray or immersion
technique based on type of item) after each
use

LATHE
Pumice has been shown to pose a
potential contamination risk (Via
aerosol or direct contact)
 Use protective eyewear
 Ensure plexiglass shield is in position
 Activate vacuum
 Procedure of disinfection
 Mix pumice with Clean water, diluted 1:10
bleach, or other appropriate disinfectant
 Add tincture of green soap if desired

TO PREVENT DISINFECTION
FROM LATHE
Change pumice daily
Machine should be cleaned
and disinfected daily
Clean and disinfect pumice
brushes and rag wheels
everyday.
Daily heat sterilization is
preferable.

SANITIZATION
CLEANING BY WIPING WITH A
DISINFECTANT/DETERGENT
SONICATION OF INSTRUMENTS WITH A
CLEANER

DISINFECTION
RINSEMAKE IMPRESSION
SPRAY & WAIT RINSE

Aseptic storage
The maintenance of sterility during transportation and storage is of
utmost importance.
• Instruments are kept wrapped until ready for use .
• To reduce the risk of contamination, sterile packs must be handled as
little as possible.
• Sterilized packs should be allowed to cool before storage; otherwise
condensation will occur inside the packs.
• Sterile packs must be stored and issued in correct date order.
• The packs, preferably, are stored in drums which can be locked.
• Preset trays and cassettes, are useful as, the instruments can be
organized as per the procedure

DEFINITION:
Infection control refers to a comprehensive and
systematic program that, when applied, prevents the
transmission of infection agents among persons who are in
direct or indirect contact with health care environment.
GOALS OF INFECTION CONTROL:
To create and maintain a safe clinical environment to
eliminate the potential for disease transmission from
Clinician to client/patient
Patient to clinician
Patient to patient
Patient to Technician &
Technician to Patient.

OBJECTIVES
• Assess risk of disease transmission in oral health care and
plan appropriate control measures.
• Interpret emerging guidelines for infection control
• Identify infectious disease that pose a risk of transmission in
oral health care.
• Apply active and passive mechanisms of infections disease
transmission prevention.
• Prepare the dental environment prior to and after patient’s
care.

CDC and OSHA
These two agencies of U.S. government play key role in
infection control.
CDC:
 Centres for disease control and prevention
 Public health agencies
 It’s mission is to promote health and quality of life by preventing
and controlling disease, injury and disability.
OSHA:
 Occupational safety and health administration.
 Protect persons by ensuring a safe and health workplace.

Most government regulatory entities private
agencies and health care professional organizations
list six infection control procedures as mandatory
for control of infectious diseases in dental practice
regardless of disciplines. They are

Dental treatment personnel (DTP)
1. All DTP should wear latex examination gloves during patient
treatment
2. All DTP should wear protective eye were during patient treatment
3. All DTP should wear masks covering the nose and mouth
4. All items used in the oral cavity should be sterilized in a heat or heat
pressure sterilizer whenever possible.
5. All touch and splash surface should be disinfected with an accepted
disinfectant whenever sterilization is not possible.
6. Contaminated materials to be disposed off carefully by placing it in a
sealed appropriately marked container..

Operation theatre procedure :
Antiseptic environment :
The principle is to minimize bacterial contamination especially, in the
vicinity of operating table the concept of zones is useful and must be
employed.
Outer and general access zone- patient reception area and general
office.
Clean or limited access zone- the area between reception & general
office and corridors & staff room.
Restricted access zone- for those properly clothed personnel
engaged in operating theatre activities, anesthetic room.
Aseptic or operating zone- the operation theatre.

FUMIGATION OF OPERATION THEATRE
- Fumigation of the operation theatre is achieved by
fumigator and potassium permanganate reaction technique.
- The chemical used is 40% formaline.

HAND WASHING
Three types of hand washing-
Social hand washing
Clinical hand washing
Surgical hand washing

SOCIAL HAND WASHING
Recommended following social-type contact
with clients, after going to the toilet and
after covering a cough or sneeze.
A plain liquid soap is often used.

CLINICAL HAND WASHING
A clinical hand wash is used before
clinical procedures on clients, when a
client is being managed in isolation, or
in outbreak situations.
An anti-microbial soap, containing an
antiseptic agent, is used.

SURGICAL HAND WASHING
A surgical hand wash is required before any
invasive or surgical procedure requiring the
use of sterile gloves.
An antimicrobial skin cleanser, usually
containing chlorhexidine or detergent-based
povidone-iodine, is used.

Surgical Scrubbing :
The purpose is to reduce resident and transient skin flora
(bacteria) to a minimum.
Proper hand scrubbing and the wearing of sterile gloves and
a sterile gown provide the patient with the best possible
barrier against pathogenic bacteria in the environment and
against bacteria from the surgical team.
The following steps comprise the generally accepted method
for the surgical hand scrub-

DISINFECTION OF CHAIR SIDE
EQUIPMENTS
High speed evacuation
Plastic tip :- Discarded
Metal tip :- Autoclaved
• Dental handpieces and other devices
attached to air and water lines
Use autoclavable handpieces
Use Suck-back featured handpieces
Infection control recommendations for the dental ofﬁ ce and the dental laboratory. ADA Council on Scientiﬁ c
Affairs and ADA Council on Dental Practice. J Am Dent Assoc 1996;127:672-80.

ENGINEERING CONTROLS:
Engineering controls are devices or equipment that reduce or
eliminate a hazard.
• Devices that provides protective guarding of sharp
instruments such as needles or scalpels.
• Devices that replace sharp items such as needles with
systems that do not contain a sharp surface.
• Devices that eliminate work exposure to sharp items
eg. Sharp containers
Needle covers with built in retraction
Needle destroyer
Needle destroyer

G O V T . D E N T A L C O L L E G E J A I P U R 97
PERSONAL PROTECTIVE
EQUIPMENTS (PPE)
Disposable
Gloves
•Polyurethane
gloves
•Latex gloves
•Nitrile utility
gloves
Disposable
Masks
Protective
eyewear,
chin length
face shield
Protective
clothing
(i.e., lab
coat/jacket)

EYE PROTECTION:
 Eye wear (Glasses) and face
shields
 To protect eyes from spatter or
spray of body fluids or calculus etc.
MASKS:
 To protect airway from airosol,
spatter etc.
 Recommendations to change
the mask after 20 minutes in
aerosol or 60 minutes in non-
aerosol environment.
PERSONAL PROTECTIVE
EQUIPMENTS

PROTECTIVE CLOTHING:
To protect intact and non intact skin from
spray or splash of body fluid during
course of treatment.
This protection can be provided by high
neck, long sleeve, knee-length garments.
Protective clothing for instrument cleaning
and sterilization in the clinic may be of
fluid proof variety.

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.

GLOVES: 4 categories
a). Medical exam gloves: vinyl gloves
 Non sterile gloves
 Available in variety of size, materials.
 Right/left hand specific.
b). Surgical gloves:
 Individually packaged in pairs
 Sterile untill the package is opened or bracked.
 Used for surgical procedures.
c). Over gloves:
Loosely fitting gloves
 Worn over surgical gloves in order to avoid the cross contamination
of surgical gloves.
Non sterile gloves
d). Nitrile gloves:
 Also known as heavy duty gloves

Hand protection:
Practices that reduce the risk of dermatitis
include:
1. Thorough drying of hands after hand washing
2. Use powder free gloves or low amount of powder.
3. Use of lubricating hand lotions.
4. Use of cool water when washing hands.
5. Protecting hands from cuts and scratches.

Hand washing:
Equipments : Liquid anti microbial soap
Sink with running water
Personel protective equipment
Steps of hand washing:
1. Remove jewelry from hands and forearms
(Otherwise harbors micro organisms and perforates gloves)
2. Keep hands and protective clothing away from sink surface (If hand touch
sink during hand washing, repeat process) to prevent contamination.
3. Control water flow
By pressing foot pedals with foot
By pushing knee pedals with knee
By turning of hand operated faucets by using elbow

TREATMENT AREA PREPARATION AND CLEAN UP
Health care environment must be managed to prevent cross contamination
Most items and surface areas in the dental care environment cannot be
sterilized, therefore these must be cleaned and disinfected with disinfactant or
covered with plastic barrier.
ITEMS:
Dental chair
Operator chair
Dental unit
Dental light
X-ray unit
Air/water syringe handle
Pencils, pens, face mirrors, safety glasses
Saline ejector holder
Ultrasonic scaler

Barriers used to prevent contamination of
nonsterilizable items.

Disinfectant Air Water syringe being
flushed
Environment
disinfection.
Spraying nitrile gloves with
environmental surface disinfectant

INFECTION CONTROL AND THE
DENTIST
The
areas of
risk in
infection
control
Hands
Eyes
Aerosols

J A I P U R
ROUTES OF DISEASE TRANSMISSION
IN DENTISTRY
INHALATION
INDIRECT CONTACTCONTACT/SPLASH
PERCUTANEOUS

VEHICLES OF TRANSMISSION OF PATHOGENS

CROSS CONTAMINATION:
Cross contamination is the transfer of oral fluids and debris from a
client to surfaces, equipments, materials, workers hand or another clients.
Because Saliva is invisible yet capable of cross contamination.
Direct Cross Contamination Indirect Cross Contamination
DIRECT CROSS CONTAMINATION:
When workers fails to change gloves between clients
When instruments are not cleaned or sterilized between use
Use of disposable dental products such as saliva ejector on multiple patients.

WORK PRACTICE CONTROL:
Improper positioning of operator’s fingers placing the dental
hygienist at risk of a puncture wound.

INDIRECT CROSS CONTAMINATION:
1. When instruments, dental materials and their containers, equipment and
environmental surfaces are contaminated with a client’s oral fluid, either through
touch or spatter and are not decontaminated before touched again.
2. When a chart or dental material is handled with contaminated gloves and then
handled again with gloved hands when treating another client.
Indirect cross-contamination from a chart
handled with a contaminated gloved hand.

COMMON INFECTIOUS DISEASES
ENCOUNTERED IN DENTISTRY
Hepatitis A
Hepatitis B
Hepatitis C
Hepatitis E
Herpes
HIV
Tuberculosis

REQUIREMENTS FOR LAB PERSONNEL
 Laboratory operators &
employees should follow the
Occupational Safety and Health
Administration’s (OSHA) BBP
Standard
 Employees must provide Hepatitis B vaccine
 They must use appropriate personal
protective equipment
 Must be given annual BBP training &
reviewed annually and updated
whenever necessary
All patients should be treated as if they could transmit a BLOOD BORNE
PATHOGEN (BBP) disease

STRATEGIES TO PREVENT DISEASE
TRANSMISSION
1. Vaccination eg. BCG, DPT, MMR, etc.
2. Work Restriction:
• Work restrictions are recommended by the U.S. public
health services for health care worker with certain
infections and following exposure to some diseases.
• Hepatitis B
3. Universal Precaution:
Universal precautions are the practices by which health
care worker follow the same infection control for all patient
irrespective of infection status or health history.
4. Standard Precaution:
To - blood and other body fluids
- non intact skin
5. Transmission based precautions:
For patients who are infected with highly transmissible disease

immunization
All clinical staff should be vaccinated against the common
illnesses.
Infection Timing and route Length of protection
1. Tetanus
2. Poliomyelitis
3. Hepatitis B
4. Tuberculosis
IM
Oral
IMK 0,1,6 months
Subdermal
5 yrs
5 yrs
3.5 yrs
5 yrs

Inoculation injuries
Inoculation injuries are the most likely route for transmission of
blood borne viral infections in dentistry.
The definition of an inoculation injury includes all incidents where a
contaminated object or substance breaches the integrity of the skin or mucous
membranes or comes into contact with the eyes.
The following are typical examples –
sticking or stabbing with a used needle or other instrument
splashes with a contaminated substance to the eye or other open lesion
cuts with contaminated equipment
bites or scratches inflicted by patients.

Treatment sequence for injuries :
• Injury
• Wash in running water and encourage wound to bleed
• Cover the wound
• Seek medical advice councelling
• Take blood simple from wound recipient
• Identify instrument or needle
• Test for hepatitis B virus and HIV
• Take blood sample from donor
• Record details of injury in an accident book.

Regulation on Hazardous Waste Management
The Hazardous Waste (Management & Handling) Rules, 1989
and amendments made thereafter are now superseded by the
new Hazardous Waste (Management, Handling &
Transboundary Movement) Rules, 2008.

Hazardous
Waste as defined
in the Rules
Any waste which by
reason of any of its
physical, chemical,
reactive, toxic, flammable,
explosive or corrosive
characteristics causes
danger or is likely to
cause danger to health or
environment, whether
alone or when in contact
with other wastes or
substances, and shall
include wastes listed in
schedules I, II & III of the
rules

TYPE AND NATURE OF HWS
Recyclable – wastes having potential for recovery
of useful /valuable material
Incinerable – wastes having high calorific value,
mainly organic wastes like solvents, tars, off-spec.
Organic products etc.
Land Disposable – wastes that can neither be
recycled or incinerated

STORAGE OF HAZARDOUS WASTE
Till disposal for recycling/ treatment/ land filling, HWs are to
be stored onsite in bags/ containers in a covered area.
Storage permitted for a period not exceeding 90 days
SPCB may extend the storage period, in case of Small
generator,
Recyclers, reprocessors and facility operators upto 6
months of their annual capacity
Wastes which need to be specifically stored for
development of a process for its recycling, reuse.

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.
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.

references
BOOKS:
Harsh mohan
Cross infection control in dentistry-P.R.Wood
ARTICLES:
• Chiaji Shen :A study on the effects of glutarldehyde base disinfectants on denture base
resins JPD 1989; 61-5;583
• J.A. Bell : A study on the effectiveness of two disinfectants on denture base acrylic resin
with an organic load of staphylococcus aureus. JPD 1989; 61-5; 580.
• David G. Drennon : A study on the accuracy and efficiency of disinfection by spray
automization on elastomeric impression. JPD 1989; 62-4; 468.
• Robert W. Schutt :A study on bactericidal effect of a disinfectant dental stone on
irreversible hydrocolloid impression and stone casts. JPD 1989; 62-5; 605.
• Shogo Minagi :A study on prevention of AIDS and Hepatitis B disinfection of hydrophilic
silicone rubber impression material. JPD 1990; 64-4; 463.
• J. Matyas :A study on the effects of disinfectant on dimensional accuracy of impression
materials. JPD 1990; 64-1-25.

Thankyou , next seminar will
be presented by Dr.
Humaira on ceramics-
history and recent.

HAVE MILES OF
SMILES
HAVE A BIG NICE
SMILE

4. strelization and infection control

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