Infection control

INFECTION CONTROL
IN DENTISTRY
“IT IS IN YOUR HAND”
By Dr. Lilavanti Vaghela
MDS in Pediatric and Preventive Dentistry

Introduction
➢ The concept of asepsis and it role in the prevention of infection control was put
forward nearly two century ago.
➢ 1850- general principle laid down by Ignaz semmelweiss in Europe and oliver holmes
in USA
➢ The scientific study of hospital or nosocomial cross infection began during the first
half of 18th century, and from that time until the start of the “Bacteriological Era ”
many notable contributions originated and remarkable among these early pioneers
was the physician SIR JOHN PRINGLE, who strongly belive that over crowding and
poor ventilation added greatly to the problem of hospital infection.
➢ With the opening of numerous hospitals in the 20th century,it was soon realized that
infections occurred not only in obstetric, surgical and medical patients but in dental
patients as well.
➢ This was not until JOSEPH LISTER in1867,in scotland proposed his germ theory and
put forward the idea of asepsis to reduce infections in surgical patients
➢ W D MILLER who authored a book “micro organisms of the human mouth “in 1890
associated the presence of bacteria with pulpal and periapical disease.
Centre for disease control and prevention guidelines for infection control in dental health care settings-2003,2016
Public health dentistry by soben peter 4th edi

➢ WILLIEM HUNTER presented a lecture on the role sepsis and antisepsis to the
faculty of McGill University in united state which emphasized restorations over
tooth extraction.
➢ Antony van Leeuwenhoek, the inventor of single lens microscope, was the first
to observe oral flora and his descriptions of animalcules observed in the
microscope included those from dental plaque and from an exposed pulp cavity.

Definition
➢ Infection-is the process of invasion of the tissue by organisms
characterized by their multiplication in the body of the
host to produce disease.
• Infection can be….
• Primary infection-initial infection with a parasite in a host
• Reinfection-subsequent infections by the same parasite in the host
• Secondary infection-when a new parasite set up an infection in a host whose
resistance Is lowered by preexisting infectious disease.
• Focal infection- indicates a condition where, due to infection or sepsis at
localized sites, generalized effects are produced
• Cross infection-when a patient already suffering from a disease , a new infection
is set up from another host or another external sourse, it is
termed as cross infection.
• Atypical infection-is one where the typical or characteristic clinical
manifestations of the particular infectious disease are not
present
Anantnarayan and panicar’s text book of microbiolory 7th edi

DEFINITION
➢ Asepsis- prevention of microbial contamination of living tissues or sterile
materials by excluding, removing or killing microorganisms
➢Infectin control-
OSHA- Also called“exposure control plan”
It is a required office program that is designed to protect
personnel against risks of exposure to infection.
➢Sterilization-is a process by means of which an article , surface or
medium made free from all living micro-organism including
spores.
➢Disinfection- is a process of destruction of vegetative forms of pathogen
organisms which are capable of producing infection but not
including spores.
Anantnarayan and panicar’s text book of microbiolory 7th edi

Infectious agent concern in dental practice
✓ Viral
✓ Bacterial
✓ Fungal
✓ Parasitic

Route of transmission
• Through a several route
• Direct route-blood, oral fluid, and other secretions.
• Indirect route-with contaminated instruments
-operatory equipments
-environmental surface
-contact with airborne contaminants
(present in either droplets spatter or aerosols of oral and respiratory
fluids)
• Infection via any of these routes requires that all of the following condition
present …..
1) A susceptible host
2) A pathogen with sufficient infectivity and numbers to cause infection
3) A portal through which the pathogen may enter the host.
Centre for disease control and prevention guidelines for infection control in dental health care
settings-2003,2016

• Effective infective control stratergies are intended to break one or more of these
“links” in the chain there by preventing infection.

➢ The purpose of infection control in dental practice is to prevent the transmission
of disease producing agent such as bacteria,viruses, fungi,from one patient to
another, from dental practitioner and dental staff to patients and from patient
to dental practitioner or other dental staff.
➢ It is necessary that endogenous spread of infection is also prevented by limiting
the spread of infectious agents.

Successful infection control involves:
• Understanding the basic principle of infection control.
• Creating system that allow infection control procedures to be implemented
effectively and make compliance with them easily.
• Keeping up to date regarding specific infectious disease, particularly newly
involving infectious challenges such as AVIAN (H5N1 or H7N9) influenza ,
emerging influenza virus and multiple resistant organism and how to take
precautions against them.
• Identifying settings that need modified procedures .(eg. Nursing home)
American dental association ,infection control guidelines,2016.

Fundamental elements need to transmission of
infectious agents in dental setting
A. Administrative measures/Administrative recommendations.
• Develop and maintain infection prevention and occupational health programms
• Provide supplies necessary for adherence to standered precautions
eg. Hand hygiene products,
Safer devices to reduce injuries
Personal protective equipments.
• Assign at least one individual trained in infection prevention responsibilities for
co-ordinating the program .
• Develop and maintain written infection prevention polices and procedures
appropriate for the services provided by the facility and evidence based
guidance, regulation, or standard
settings-2003,2016

B. Infection control education and training
• Provide a job or task specific infection prevention education and training to all
DHCP.
(this includes those employed by outside agencies and available by
contract or on a volunteer basis to the facility)
• Provide training on principle of both DHCP safety and patient safety.
• Provide training during orientation and regular intervals.
• Maintain training records according to state and federal requirements.

Categories of task in relation to risk
• Category -1
that involves exposure to blood , body fluid/tissue.
• Category -2
do not involve routine exposure to blood, body fluid/tissue
• Category -3
a front office receptionist, book keeper or insurance clerk who does not
handle dental instruments or materials would be a category 3 worker.
• Acc to ADA and OSHA guidelines advice that all dental office staff in cat 1,2 and
dentist be trained in infection control to protect themselves and their patiens.
settings-2003,2016

Standerd precautions of infection control
• Hand hygiene
• is a general term applying to processes aiming to reduce the number of micro-
organisms on hand
• This includes, either the application of waterless antimicrobial agent
eg. Alcohol based hand rub(ABHR)
or use of soup /solution and water followed by patting dry with single use towel
➢ Perform hand hygiene technique when….
• When hands are visibly soiled
• After barehanded touching of instruments, equipments,materials,and other
objects likely to be contaminated by blood, saliva or other secretions.
• Before and after treating each patient.
• Before putting on gloves and again immediately after removing gloves.
settings-2003,2016

Hand care
• Hand care must be there, because intact skin is a first line defense mechanism
against infection.
• Damaged skin for dental practitioner and clinical support staff is an important
issue because of high frequency dry, itchy skin from irritant contact dermatitis ,
primarily caused by frequent and repeated use of hand washing products
resulting in drying skin.
• Lacerated , chafed or cracked skin can allow entry of micro organisms.
• Any cuts /open wounds need to be covered with a waterproof dressing.
• All hand, wrist and nail jewellary must be removed prior to putting on gloves as
their presence compromise the fit, integrity of gloves, and promotes significant
growth of skin microorganism.
• All finger nails must be kept short to prevent tears and to allow thorough hand
cleaning .
settings-2003,2016

Personal protective equipments
• Refers to wearable equipment that is designed to protect DHCP from exposure
to or contact with infectious agents.
• These includes…
• Gloves
• Facemask
• Protective eye wear
• Face shield
• Foot wear
• protective clothing
(reusable/disposable gown,jacket/laboratory coat).

Gloves
• For protection of personnel and patients, gloves must be worn by the dentist
when there is potential for contacting blood, blood contaminated saliva, or
mucous membrane.
• Before treatment of each patient, dentist should wash their hands and put on a
new gloves, and after treatment should discard the gloves and wash their hands.
➢ Classification of gloves
• Natural rubber latex(NRL)
• Acrylonitrile-butadine(nitrile)
• Ploy vinyl chloride(PVC- vinyl)

• Classification
• Powderd gloves
• Unpowdered gloves
• Classification acc to use
• Examination gloves
• Surgical gloves

• Powdered gloes
• To facilitate donning of gloves, powders have been used as lubricant.
• Early powder derived from pines/club moss were found to be toxic.
• Then talcum powder was used but linked to post operative itching and other
skin reactions.
• Later on corn-starch and lycopodium powder were used and they found as
potential irritating agent

Chlorination of gloves
• It is a process where in examination gloves are exposed to chlorine gas or a
hypochloride-hydrochloric acid mixture in order to harden the surface of glove.
• The hardening of the glove surface decrease the surface friction of the glove,
thereby allowing for glove to be easily donned without powder.
• This process significantly reduces the level of extractable latex proteins , making
the glove less likely to cause latex allergy in the wearer
Polymer-coated disposable gloves
• In this newer process, a polymer coating is applied to the interior surface of the
glove,giving a smooth finish for fast and easy donning.
• This coating normally used on medical gloves include hydrogels, acrylics,
silicone polymer, polyurethane, etc.
• Most white nitrile examination gloves are polymer coated ,as chlorination
causes yellowing

• In latex gloves, polymer coating provide a barrier between the latex glove
material and the wearer, which helping to limit the migration of latex protein.
And cause less latex allergy.

Steps in gloving

Doble gloving
• It is the practice of wearing two layers of gloves to reduce the danger of
infection from glove failure or penetration of the glove by sharp objects during
clinical procedures.

Masks
Types:
1. Surgical masks (required to have fluid-resistant properties).
2. Procedure/isolation masks
• Made up from a melt blown placed between non-woven fabric
Layers of a Mask
1. an outer layer
2. a microfiber middle layer - filter large wearer-generated particles
3. a soft, absorbent inner layer - absorbs moisture.
• Available in 2 sizes: regular and petite.

Masks must:
• be put on before performing hand hygiene and donning gloves;
• be fitted and worn according to the manufacturer’s instructions – this means
using both tie strings where the mask has two ties, and adapting the mask to the
bridge of the nose;
• cover both the nose and mouth, and where possible be folded out fully to cover
the chin and upper neck; and
• be removed by touching the strings and loops only.
Masks must not:
• be touched by the hands while being worn; or
• be worn loosely around the neck while the dental practitioner or clinical support
staff member walks around the premises, but be removed and discarded as soon
as practical after use.

Eye wear
Dental practitioners and clinical support staff must wear protective eyewear
to protect the mucous membranes of the eyes during procedures where
there is the potential for penetrating injury or exposure to aerosols,
splattering or spraying with blood, saliva or body substances.
Eyewear must be optically clear, anti-fog, distortion-free, close-fitting and
should be shielded at the sides.
Patients must be provided with protective eyewear to minimise the risk of
possible injury from materials or chemicals used during treatment.

Face shield
• An alternative to protective eyewear is a face shield. However, this does not
protect from inhaled microorganisms and must be worn in conjunction with a
surgical mask.

Protective clothing-gown
• Protective clothing (e.g. disposable gown), should be worn while treating
patients when it is possible aerosols or splatter are likely to be generated or
when contaminated with blood or saliva. The most suitable type of protective
clothing and equipment used varies according to the nature of the procedure
and is a matter of professional judgement.
• Protective garments are worn over street clothes to protect them from
contamination.
• Wear protective clothing that covers persona.
• Wear long sleeved gown

How to put a gown
• First select the appropriate type for the task and the right size for you.
• The opening of the gown should be in the back.
• Secure the gown at the neck and wirst.

FOOTWEAR
• Dental practitioners and clinical support staff should wear enclosed footwear
that will protect them from injury or contact with sharp objects (e.g.
accidentally dropped sharps or spilt chemicals).

How to remove gown
• Unfasten ties
• Peel gown away from neck and shoulder.
• Turn contaminated outside toward the inside
• Fold or roll into a bundle

Sequence for donning PPE
Gown
Mask
Eye wear/face shield
Gloves
Sequence of removing PPE
Gloves
Eye wear/face shield
Gown
Mask

Sharps safety
• 1. Consider sharp items (e.g., needles, scalers, burs, lab knives, and wires) that are
contaminated with patient blood and saliva as potentially infective and establish
engineering controls and work practices to prevent injuries.
• 2. Do not recap used needles by using both hands or any other technique that involves
directing the point of a needle toward any part of the body.
• 3. Use either a one-handed scoop technique or a mechanical device designed for holding
the needle cap when recapping needles (e.g., between multiple injections and before
removing from a non-disposable aspirating syringe).
• 4. Place used disposable syringes and needles, scalpel blades, and other sharp items in
appropriate puncture-resistant containers located as close as possible to the area where
the items are used.

Immunization procedure
• Dental health care workers are at a greater risk than the general population,of
acquiring hepatitis B and AIDS through contact with patient.
➢ Vaccines available for dental health care workers.
Disease vaccine
Diphtharia , DPT
Pertusis,tetanus
Tuberculosis BCG
Measles/mumps MMR
/rubella
Hepatitis Heptavax-B,recombivax HB
Influenza inactivated virus vaccine/
aqueous subunit
Prevention and disease control by soben peter, 6th edi

Prevention and disease control by soben peter, 6th edi

Sterilization and disinfection
• According to the Centers for Disease Control, dental instruments are classified
into three categories depending on the risk of transmitting infection.
1) Critical instruments :
- those penetrate soft tissue or bone, or enter into or contact the bloodstream or
other normally sterile tissue.
- 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,
scalers and surgical burs.
CDC guideline for sterilization and disinfection in healthcare facilities,2008

2) Semi-critical instruments :
• those that do not penetrate soft tissues or bone but contact mucous membranes or
non-intact skin,
• such as mirrors, reusable impression trays and amalgam condensers.
• These devices also should be sterilized after each use. In some cases, however,
sterilization is not feasible and, therefore, high-level disinfection is appropriate.
3) Non-critical instruments
• those that come into contact only with intact skin such as external components of
x-ray heads, blood pressure cuffs and pulse oximeters.
• Such devices have a relatively low risk of transmitting infection; and, therefore, may
be reprocessed between patients by intermediate-level or low-level disinfection.
CDC guideline for sterilization and disinfection in healthcare facilities,2008

Ref- Grossman’s endodontic practice 12th edi

Transport of instruments to the sterilization area
• Most dental offices have a designated area for instrument reprocessing that is separate
from the dental treatment room.
• This is ideal, since cleaning, sterilizing and storing instruments in the same room where
the delivery of patient care is provided increases the risk of cross-contamination.
• The Centers for Disease Control and Prevention (CDC) states that, “Contaminated
instruments should be handled carefully to prevent exposure to sharp instruments that
can cause percutaneous injury.
• Instruments should be placed in an appropriate container at the point of use to prevent
percutaneous injuries during transport to the instrument processing area.”
• Some instruments and materials are single-use only. Single use items should be segregated
in the operatory, and those that are sharp or otherwise pose a risk of injury must be
discarded into a sharps container
• Finally, the tray or cassette of reusable instruments is taken to the cleaning and
sterilization area for processing.
CDC guideline for sterilization and disinfection in healthcare facilities,2008,2013

• In addition, the Occupational Safety and Health Administration (OSHA) says, “The person
handling the instruments through removal, cleaning, packaging and sterilization needs to
use heavy-duty gloves and other personal protective equipment to help prevent injury
with sharp contaminated instruments.”
• Although heavy-duty gloves (utility gloves) may feel more awkward than examination
gloves, they provide extra protection while handling instruments during the cleaning,
rinsing, drying, packaging and sorting procedures that take place during instrument
reprocessing.
• The fine tactile sensitivity needed during dental procedures is not necessary during
instrument cleaning and sterilization; therefore heavy-duty gloves pose no problem in this
regard.
CDC guideline for sterilization and disinfection in healthcare facilities,2008,2013

Presoaking (Holding)
• It facilitates the cleaning process by preventing the debris from drying
PROCEDURES
• Wear puncture resistant heavy utility gloves and personal protective equipments.
• Place loose instruments in a perforated cleaning basket and then place the basket into the
holding solution for 5-15mins.
• Perforated cleaning basket reduces the direct handling of instruments, so chances of
contamination are decreased.
• Holding solution should be discarded at least once a day or earlier if seems to be soiled.
• Avoid instrument soaking for long time (more than an hour) as it increases the chances of
corrosion of instruments.
• It aids in the subsequent cleaning process by removing gross debris.
Holding solution for instruments can be:
• Water
• Enzymatic detergents –Empower -Klenzyme
-Metrizyme -Enzol
-Detergezyme -Asepti-zyme
Textbook of Endodontics by Nisha gerg 3rd edi

• Typically enzymatic detergents are used to break down organic material and
presoaking makes later processing easier by helping to prevent blood and other
matter from drying on instruments.
• Presoak detergents come in 2 main varieties: dual-enzymatic & single-enzymatic.
• Dual-enzymatic detergents have a dual-enzyme formula that breaks down protein
deposits, starch, and carbohydrates that accumulate on the instruments.
• Single-enzymatic detergents have a single-enzyme formula that cleans proteins.
• Detergents are available in liquid or dry tablets.

Cleaning
METHODS
• Manual scrubbing
• Ultrasonic cleaning
• Mechanical –instrument washer

MANUAL SCRUBBING
• One of the most effective methods for removing debris, if performed properly
PROCEDURE
• Always wear heavy utility gloves and PPE
• Brush delicately all surfaces of instruments while submerged in cleaning solution
• Use long handed stiff nylon brush to keep the scrubbing hand away from sharp instrument
surfaces.
• Instrument’s surface should be visibly clean and free from stains and tissues
DISADVANTAGE
• This procedure is not recommended as there are maximum chances of direct contact with
instrument surface and of cuts and punctures.

Ultrasonic cleaning devices
• An excellent cleaning method as it reduces direct handling of instruments. So it is
considered safer and more effective then manual scrubbing.
PROCEDURE
Mechanism of action
• Ultrasonic energy (20 – 400kHz) generated in ultrasonic cleaner produces billions of tiny
bubbles which in further, collapse and create high turbulence at the surface of instruments
This turbulence dislodge the debris.
• Time ranges vary from 4 – 16 mins
• Time may vary due to –nature of instruments
-amount of debris
-efficiency of ultrasonic unit

• SOLUTIONS FOR ULTRASONIC CLEANER
• Alkaline solution
• High caustic solution
• Acidic solution
• Enzymatic solution
• De-ionized solution
Available solutions are-
Omega clean
Omega maxx
Kleer kleen
Citrisurf 2050
Omegazyme

The procedure for cleaning the instruments in the ultrasonic cleaner is as follows
➢ Suspend instruments in the ultrasonic bath using a rack or basket fitted to the unit.
➢ Do not lay instruments directly on the bottom of the ultra sonic cleaner, as this can
interfere with cleaning and cause damage to instruments and the ultrasonic machine.
➢ Avoid overloading the ultrasonic device, since that could inhibit its cleaning ability.
• It is important to follow the manufacturer’s instructions for the ultrasonic cleaning cycle.
• While the ultrasonic device is running, the lid or cover should be kept on to reduce the
release of aerosol and spatter into the area from the ultrasonic cleaner.
• Routinely replacing the cleaning solution in the ultrasonic machine is important, and is
necessary at least once a day, more often with heavy usage.

Mechanical instrument washer
• Dental instrument washers are a highly efficient way to wash clinical instruments prior to
sterilization.
• These systems clean and remove debris from instruments using hot water and specialized
surfactant solutions to ensure the instruments do not retain any material build-up that
might interfere with the effectiveness of sterilization.
• Using an automated washer can provide both more effective and more efficient cleaning
than other instrument cleaning options, and it can be safer for staff than washing
instruments by hand.
• Instrument washers for dental offices come in two different designs. One is a counter-top
model. This type does not require professional installation.
• The other type is built-in and resembles a kitchen dishwasher . It functions much the same
as the counter-top model, but it has a larger capacity and requires professional
installation.
• Some models have the ability to dry the instruments after washing, some do not.

Packaging
• Packaging used for instruments and cassettes prior to sterilization includes wrap paper
pouches, plastic pouches, combination paper/plastic pouches
• Peel pouches are most common and convenient to use
• Sterilization packaging is specifically designed to allow penetration of heat, steam or
vapour and then to seal the sterilized instruments inside the package for sterile storage .
• After sterilization, instruments should remain in packages until use.
• Different materials are appropriate for different types of sterilizers.
• Unless otherwise specified, all packaging is single use only.
• Using tape to reseal previously used packaging material may inhibit its ability to continue
to function as intended by the manufacturer.

Various agents used in sterilization can be classified as:
➢ Physical agents
▪ Sunlight
▪ Drying
▪ Dry heat
▪ Moist heat
▪ Filtration
▪ Radiation
▪ Ultrasonic and sonic
vibrations
➢ Chemicals
▪ Alcohol
▪ Aldehyde
▪ Dyes
▪ Halogens
▪ Phenols
▪ Surface active agents
▪ Metallic salts
▪ gases
Ref –Anantnarayan and paniker’s textbook of microbiology 7th edi

SUNLIGHT
• Possesses appreciable bactericidal activity.
• Play imp role in spontaneous sterilization that occurs under natural conditions.
• The action is primarily due to its content of ultra violet rays
• Under natural conditions,its sterilizing power varies according to circumstances
eg,direct sunlight, as in tropical countryside where it is not filtered by impurities
in the atmosphere,has an active giemicidal effect due to the combined effect of ultraviolet
and heat rays
• Semple and Grieg showed that in india, typhoid bacilli exposed to the sun on
piece of white drill cloth were killed in two hours, whereas control kept in dark
were still alive after six days.
• Bacteria suspended in water are readily destroyed by exposure to light.

DRYING
• Moisture is essential for growth of bacteria
• 4/5th of the weight of bacterial wall is due to water.
• Drying in air has deleterious effect on many bacteria
• However, this method is unreliable and is only theoretical interest.
• Spores are unaffected by drying.

HEAT
• Most reliable method of sterilization.
• Materials that may be damaged by heat can be sterilized at lower temperature,
for longer periods or by repeated cycles
The factors influencing sterilization by heat are:
✓ Nature of heat—dry heat / moist heat
✓ Temp and time
✓ Number of micro organism present
✓ Characteristics of the organism (such as species, strain, sporing capacity)
✓ Type of material from which the organisms have to be eradicated.
• The time required for sterilization is inversely proportional to the temperature
of exposure and can be expressed as “thermal death time” which is minimum
time required to kill a suspension of organism at a predetermined temperature
in a specified environment.
• Presence of organic substances , proteins , nucleic acid, starch, gelatin, sugar,
fats and oil, increase the thermal death time

DRY HEAT
• The killing effect of dry heat is due to…
✓ Protien denaturation
✓ Oxidative damage
✓ The toxic effect of elevated levels of electrolytes.
➢ Divide in to..
➢ Flaming
➢ Incineration
➢ Hot air oven

FLAMING
• Inoculating loop or wire, the tip of forceps and searing spatulas are held in a
bunsen flame till they become red and hot.
• Inoculation loops carrying infective material may be dipped in a disinfectant
before flaming to prevent spattering.

INCINERATION
• An excellent method for destroying materials such as ,contaminated cloths ,
animal carcasses, pathological material.
HOT AIR OVEN
Principle
• Sterilizing by dry heat is accomplished by conduction. The heat is absorbed by the
outside surface of the item, then passes towards the Centre of the item, layer by
layer. The entire item will eventually reach the temperature required for sterilization
to take place.
• Dry heat does most of the damage by oxidizing molecules. The essential cell
constituents are destroyed and the organism dies. The temperature is maintained for
almost an hour to kill the most difficult of the resistant spores.
• It’s the most widely used mode of sterilization
• Temp.- 160°C ( 320° F ) for 1 hr.

PRECAUTIONS
• Not to be overloaded.
• Must be fitted with fans for even distribution of hot air.
• Materials to be sterilized should be perfectly dry.
• Rubber materials (except silicone rubber) will not withstand the temperature.
• Allowed to cool for 2 hr before opening the doors.

• USES
• Glasswares like glass syringes, petridishes, flasks,
pipettes & test tubes.
• Surgical instruments like scalpels, scissors, forceps
• Chemicals such as liquid paraffin, fats, greases,
• Sulphonamide, dusting powder etc.

ADVANTAGES DISADVANTAGE
Economical.
Does not rust metals
Easily monitored
Used for anhydrous
oils & powder
Hot air is bad
conductor of heat
hence it has less
penetrating power

MOIST HEAT
• Pasteurisation of milk.
• Vaccine bath.
• Low temperature steam strlilizer.
TEMPERATURE
BELOW 100 ◦C
• Boiling
• Steam sterilizer at 100 ◦C
TEMPERATURE AT
100 ◦C
• Autoclave
TEMPERATURE
ABOVE 100 ◦C

• Heat-tolerant dental instruments usually are sterilized by
1) steam under pressure (autoclaving),
2) dry heat, or
3) unsaturated chemical vapor
STEAM STERILIZER/AUTOCLAVE
CONSIDERATIONS
➢ Items to be sterilized should be arranged to permit free circulation of the sterilizing agent
(e.g., steam, chemical vapor, or dry heat); manufacturer's instructions for loading the
sterilizer should be followed
➢ Instrument packs should be allowed to dry inside the sterilizer chamber before removing
and handling.
➢ Packs should not be touched until they are cool and dry because hot packs act as wicks,
absorbing moisture, and hence, bacteria from hands
➢ The ability of equipment to attain physical parameters required to achieve sterilization
should be monitored by mechanical, chemical, and biological indicators.
65

• Among sterilization methods, steam sterilization, which is dependable and economical, is
the most widely used for wrapped and unwrapped critical and semicritical items that are
not sensitive to heat and moisture
• Steam sterilization requires exposure of each item to direct steam contact at a required
temperature and pressure for a specified time needed to kill microorganisms.

AUTOCLAVE
• Boiling water alone is INSUFFICIENT to kill spores and viruses
• water boils when its vapour pressure equals to that of surrounding atmosphere
• Hence, when pressure increases inside closed vessel
• Temperature at which water boils increases
• saturated steam has penetrative power
• When steam comes in contact with a cooler surface it condenses to water
• and gives up latent heat to that surface. The large reduction in volume of steam
sucks in more steam to the site and the process continues till the temperature of
article is raised to that of steam.

• Three major factors for effective autoclave
➢ Pressure- 15psi
➢ Temperature -121◦c
➢ Time -15 mins
Method Temp Time
autoclave 121 15
126 10
134 3
Hot air oven 160 45
170 18
180 7.5
190 1.5

Types of sterilization cycle for autoclave
• N class cycles – used for unwrapped, solid items. Steam pushes the air downwards using
gravity and forces it out a port in the bottom of the chamber.
• S class cycles – specified by the manufacturer and used with multi-pulse vacuum steam
sterilizer to suit loads of certain types and configurations
• B class cycles – for hollow objects where the ratio of the length of the hollow portion to its
diameter is more than 1:5. In these cycles there is a greater challenge for
air removal. Air is exhausted by a mechanical pump to create a vacuum
before steam is introduced into the chamber.

Considerations during autoclaving
1. Ensure complete air removal for temperature to reach 121°C.
2. Ensure loose packing in the chamber.
3. Tightly sealed materials may become dangerously pressurized causing injury when
removed.
USES
• Non disposable syringes,
• Glassware, Metal instruments, surgical dressing,
• Surgical instruments, Laboratory equipment, Culture media,
• Pharmaceutical products.

ADVANTAGES
• Economic
• Good penetration
• Short cycle time
• Easily monitored
• No special chemicals required
DISADVANTAGE
• Moisture retention
• Causes corrosion
• Carbon steel gets damaged
• Dulling of unprotected cutting edges.
• Destruction of heat sensitive materials

Types autoclave
• Autoclave function primarily through either gravity , vacuum or prevacuum
sterilization methods.
• Two types of processes employ steam under pressure.
• The difference between the two is the manner in which the machine evacuates
the air from the sterilization chamber and then introduces the steam.
➢ Downward displacement autoclave
➢ Vacuum /Pre-vacuum autoclave
74

Downward displacement autoclave
• Gravity displacement autoclave
• Rely on the forces of gravity to force air out of the chamber through air escape
vents.
• The steam entering the chamber from the water reservoir displaces the air as it
leaves the chamber.
• The combination of pressurization of the chamber, steam and a high
temperature for a prolonged period has the ability to kill virtually all
microorganisms.
• This is the most common type of autoclave found in dental offices in the United
States.
75

Prevacuum sterilizer
• Prevacuum sterilizers are fitted with a pump to create a vacuum in the chamber
and ensure air removal from the sterilizing chamber before the chamber is
pressurized with steam.
• Relative to gravity displacement, this procedure allows faster and more positive
steam penetration throughout the entire load.
• Prevacuum sterilizers should be tested periodically for adequate air removal, as
recommended by the manufacturer.
• temperature of 132°C-135°C for 3-10 minutes to achieve sterilization.
• Total time for pressurization, sterilization, venting and drying is generally
considerably shorter than that for gravity sterilizers - about 45 minutes.
76

Chemical-Vapor Sterilization. (chemiclave)
• Sterilization by chemical vapour under pressure is known as chemical vapor sterilization
• In this, special chemical solution is heated in a closed chamber,producing a hot chemical
vapors that kill micro organisms
• 132◦c at 20 lbs for 30 mins
CHEMICAL SOLUTION
• Active ingredient- 0.23% formaldehyde
• Other ingredients-72.38% ethanol+acetone+water
• Four cycles are required for this sterilizer
• Vaporization cycle
• Sterilization cycle
• Depressurization cycle
• Purge cycle (which collects chemicals from vapors in the chamber at the end of cycle

Advantages
Eliminates corrosion of carbon steel instruments, burs and pliers
Disadvantages
• The instruments or items which are sensitive to elevated temp are damaged.
• Sterilization of fabric or paper towel is not recommended
Precautions to be taken
• Use gloves and PPE while handling the solution
• Use paper/plastic peel pouches or bag recommended for use in chemiclave
• Water should not be left on the instruments
78

Sterilization of Unwrapped Instruments/flash sterilization
• is a method for sterilizing unwrapped patient-care items for immediate use.
• The time required for unwrapped sterilization cycles depends on the type of sterilizer and
the type of item (i.e., porous or nonporous) to be sterilized
• 132 C for 3minutes at 27-28 lbs
• It also is used when there is insufficient time to sterilize an item by the preferred package
method.
• If the unwrapped sterilization cycle in a steam sterilizer does not include a drying phase,
or has only a minimal drying phase, items retrieved from the sterilizer will be hot and wet,
making aseptic transport to the point of use more difficult. For dry-heat and chemical-
vapor sterilizers, a drying phase is not required.
79

OTHER MSTERILIZATION METHODS
• Heat-sensitive critical and semicritical instruments and devices can be sterilized by
immersing them in liquid chemical germicides registered by FDA as sterilants
• When using a liquid chemical germicide for sterilization, certain poststerilization
procedures are essential.
1) rinsed with sterile water after removal to remove toxic or irritating residues;
2) handled using sterile gloves and dried with sterile towels;
3) delivered to the point of use in an aseptic manner.
• If stored before use, the instrument should not be considered sterile and should be
sterilized again just before use.
• In addition, the sterilization process with liquid chemical sterilants cannot be verified with
biological indicators
80

• ETHYLENE OXIDE STERILIZATION
• Use to sterilize critical items (sometimes semicritical items) that are moisture or heat
sensitive and can not be sterilized by steam sterilization
• ETO is highly penetrative , non corrosive gas above 10.8◦c with a cidal action against
bacteria, spores, viruses.
MECHANISM OF ACTION
• It destroys micro organisms by alkylation and causes denaturation of nucleic acids of micro
organism
• The duration that the gas should be in contact with the material to be sterilized is depend
on temp., humidity , pressure and amount of material.

• Advantages
• It leaves no residue
• Good penetration power
• Can be used as low temp
• Suited for heat sensitive articles
• Disadvantage
• High cost of equipment
• Toxicity of the gas
• Can be inflammable

IRRADIATION
• IONIZING RADIATION( X-Ray, Gamma Rays ,and high speed electrons)
• Are effective for heat labile items
• Use- commonly used by industry to sterilize disposable materials such as needle ,
syringes, culture plates, suture materials, cannulas and pharmaceuticals that are sensitive
to heat
• High energy gamma rays from cobalt-60 are used to sterilize such articles
• NONIONIZING RADIATION (ultra violet light and infrared)
• These are absorbed by proteins and nucleic acids and kill micro organisms
• Their main application is purification of air in operating rooms to reduce the bacteria in air,
water, and contaminated surfaces

GLASS BEAD STRILIZER
• Rapid method of sterilization of small metallic instruments (endodontic files, diagnostic
instruments, forceps etc.)
• It uses table salt which consists approximately of 1% sodium silico aluminate, sodium
carbonate or magnesium carbonate.
• So it can be poured more radily and does not fuse under heat
• This salt can be replaced by glass beads provided the beads are smaller than 1 mm in
diameter because larger beads are not efficient in transferring the heat to instrtuments
due to presence of large air space between the beads.
• Time 2 -15 secs at a temp of 437 to 465◦ F

MAINTENANCE
• Sterilized glass beads must be cleaned at least once per week.
• Wait until the instrument has cooled completely when getting out the glass beads.
• ADVANTAGES
• Commoly used salt is table salt which is easily available and cheap
• Salt does not clog the root canal. If it is carried in to the canal it can be readily removed by
irrigation.
• DISADVANTAGE
• Handle portion is not sterilized, so instruments are not entirely ‘sterile’

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.
➢ Indicators are specific to the type of sterilization used.

• Mechanical Monitoring
• Monitor each load with mechanical (physical) indicators:
• Time.
• Temperature.
• Pressure.

Chemical indicators
• Chemical indicators indicate the presence of certain conditions during the sterilization
cycle, such as the presence of heat and steam.
• There are five classifications of indicators recognized by the FDA, and it is important to
note that it is now recommended that all packs or cassettes include internal and external
indicators.
Class 1 - Process Indicators:
➢ These are placed on the outside of packs and are useful in determining which packs have
been properly processed versus those that have not.
➢ Class 1 process indicators include autoclave tape and the colour change indicators
embedded on the outside of sterilization packaging materials.
Class 2 - Bowie-Dick Indicators:
➢ These show the pass/fail in pre vacuum sterilizers. This test is conducted daily with the
chamber empty, during the first cycle of the sterilizer, and is available as a kit from
commercial sterilization monitoring companies.
Class 3 - Temperature-Specific Indicator:
➢ These react to one of the critical parameters of sterilization and indicate exposure to a
specific value such as temperature or psi.

Class 4 - Multi-parameter Indicators:
➢ These react to two or more of the critical parameters in the same manner as Class 3
indicators.
Class 5 - Integrating indicators:
➢ These are designed to react to all critical parameters of sterilization cycles.
➢ When used properly, integrating indicators may serve as the basis for the release of
processed items
➢ It is important to follow the manufacturer’s
specific instructions for use regarding a test challenge pack.

• Biological Monitoring
• These are standerized population of resistant bacterial spores such as geobacillus
stearothermophilus spore
• This test is used to determine if the sterilization cycle parameters were sufficient to kill the
test micro organism.
• Use biological indicators (spore tests) at least weekly.

• Record Keeping
• Sterilization monitoring (e.g., biological, mechanical, chemical) and equipment
maintenance records are important components of a dental infection prevention
program.
• Ensures cycle parameters have been met and establishes accountability.

Storage of Sterilized Items and Clean Dental Supplies
• The storage area should contain enclosed storage for sterile items and disposable (single-
use) items .
• Storage practices for wrapped sterilized instruments can be either date- or event-related.
Packages containing sterile supplies should be inspected before use to verify barrier
integrity and dryness.
• Although some healthcare facilities continue to date every sterilized package and use
shelf-life practices, other facilities have switched to event-related practices .
• This approach recognizes that the product should remain sterile indefinitely, unless an
event causes it to become contaminated (e.g., torn or wet packaging) .
• Even for event-related packaging, minimally, the date of sterilization should be placed on
the package, and if multiple sterilizers are used in the facility, the sterilizer used should be
indicated on the outside of the packaging material to facilitate the retrieval of processed
items in the event of a sterilization failure .
• If packaging is compromised, the instruments should be recleaned, packaged in new wrap,
and sterilized again. Clean supplies and instruments should be stored in closed or covered
cabinets, if possible .
• Dental supplies and instruments should not be stored under sinks or in other locations
where they might become wet

• Ultraviolet storage chamber
• Commonly available in dental practice
• UV chamber has ability to maintain/preserve instruments without any fear of
contamination of micro organisms once they are autoclaved or sterilized.
• Uv radiation range from 210-328nm
• Maximum bactericidal effect occurs at 240-280nm
• Can store instruments for 7 days

CHEMICAL AGENTS
• Alcohols
• Aldehydes
• Dyes
• Halogens
• Phenols
LIQUID GAS
• Ethylene oxide
• Formaldehyde gas
• Betapropiolactone(BPL)

MODE OF ACTION OF CHEMICAL AGENTS
• Protein coagulation
• Disruption of the cell membrane
• Removal of the free sulphydryl groups
• Substrate competition

Hand disinfectants
• Alcohol based
• Non alcohol based
• Formulations of the alcohol-based type are preferable to hand washing with soap and
water in most situations in the healthcare setting.
• It is generally more effective at killing microorganisms and better tolerated than soap and
water.
• Alcohol-based hand rubs are extensively used in the hospital environment as an
alternative to antiseptic soaps.
• Hand-rubs in the hospital environment have two applications: hygienic hand rubbing and
surgical hand disinfection. Alcohol based hand rubs provide a better skin tolerance as
compared to antiseptic soap. Hand rubs also prove to have more effective microbiological
properties as compared to antiseptic soaps.
• alcohols such ethanol ,propanol and isopropanol, sometimes combined
with quats (quaternary ammonium cations) such as benzalkonium chloride. Quats are
added at levels up to 200 parts per million to increase antimicrobial effectiveness.
• Allergy to alcohol based hand rub is rare, fragrances, preservatives and quats can cause
contact allergies.These other ingredients do not evaporate like alcohol and accumulate
leaving a "sticky" residue until they are removed with soap and water.

• The most common brands of alcohol hand rubs include Aniosgel, Avant, Sterillium,
Desderman and Allsept S
• The level of alcohol varies between 60% and 95%
• ALCOHOL FREE
• Some hand sanitizer products use agents other than alcohol to kill microorganisms, such
as povidone-iodine, benzalkonium chloride or triclosan
• Alcohol-free hand sanitizers may be effective immediately while on the skin, but the
solutions themselves can become contaminated because alcohol is an in-solution
preservative and without it, the alcohol-free solution itself is susceptible to contamination.
• However, even alcohol-containing hand sanitizers can become contaminated if the alcohol
content is not properly controlled or the sanitizer is grossly contaminated with
microorganisms during manufacture.

• Chlorhexidine based – these contain 2- 4% chlorhexidine gluconate with 4% isopropyl
alcohol in a detergent solution with a pH of 5.0 to 6.5. They have broader activity for
special cleansing(e.g: for surgery, glove leaks, or when clinician experiences injury).
• Povidone iodone – contain 7.5-10% povidone iodine, used as a surgical hand scrub.
• Parachlorometexylenol(PCMX) – they are bactericidal and fungicidal at 2% concentration.
Non irritating and recommended for routine use.

Spirit in dentistry
• Rubbing alcohol
• either isopropyl alcohol (propan-2-ol) or ethanol based liquids,
• British Pharmacopoeia defined surgical spirit, with isopropyl alcohol products being the
most widely available.
• They are liquids used primarily as a topical antiseptic
• The term "rubbing alcohol" has become a general non-specific term for either isopropyl
alcohol (isopropanol) or ethyl alcohol (ethanol) rubbing-alcohol products.
• The United States Pharmacopeia defines 'isopropyl rubbing alcohol' as containing
approximately 70 percent by volume of pure isopropyl alcohol.
• It is used to clean instruments, contaminated surface, etc.

ALDEHYDE
A)Formaldehyde (formalin)
• In aqueous solution it acts as a bactericidal and sporicidal
• Active against Gram -ve bacteria, spores, viruses & fungi
• Aqueous soultion: Formalin(37% solution) +0.5% Na tetraborate used to
clean metal instrument e.g Endoscope, dialysis equipment.
• Gaseous form: Fumigation of wards/corridors/ICU’s
DISADVANTAGE:
• Have pungent odour
• irritating effect on skin & mucous membrane.

• B.GLUTARALDEHYDE / CIDEX
• High level disinfectant
• Active against most vegetative bacteria, fungi, bacterial spores.
• Frequently used for heat sensitive material.
• A solution of 2% glut. requires immersion of 20 mins for disinfection and 6-
10hrs of immersion for sterilization.
• Safely used on metals instruments, rubber, plastics, and porcelain
• Activated by addition of sod bicarbonate,but it remains
potent only for 14 days

Phenolic compounds
• At high conc, these compounds are protoplasmic poison and act by precipitating the
proteins and destroy the cell wall.
• These compounds are used for disinfection of inanimate objects such as walls , floors and
furniture.
• They may cause damage to some plastics and they do not corrode certain metal such as
brass, aluminum and carbon steel.

• HALOGENS :
Chlorine compounds:
• Commonly used are sod hypochlorite and chlorine dioxide
• Sod hyp. has rapid action
• A solution of 1 part of 5% sod hyp with 9 parts of water is used.
• Chlorous acid and chlorine dioxide provides disinfection in 3 mins

• IODOPHOR
• Active against bacteria, spores & some viruses & fungi
• Suitable for skin preparation, mouthwash & as a surgical scrub
• 7.5% Povidone iodine (Betadine) used for scrubing
• 10% used for painting and dressing

DYES
• Two group of dyes,anilin dyes and acridine dyes are used extensively as skin and
wound antiseptics.
• But both are bacteriostatic as high dilution but are of low bactericidal activity.
• The anilin dyes in use are brilliant green, malachite green, and crystal violet(they
are more active against gram +ve than gram –ve organism.
• Though they are non irritant to the tissue and non toxic , they are considerably
inhibited by organic material such as pus.
• The acridine dyes are also more active against gram +ve organism but are not
selective as anilin dyes
• Affected very little by the presence of organic matter
• Imp dyes are—proflavine, acriflavine, euflavin, aminacrine
• If it impregnated in gauze, they are slowly released in a moist environment, and
hence their advantage and use in clinical medicine.
• Kill or destroy the reproductive capacity of the cell.

GASES
ETHYLENE OXIDE
• Highly inflammable and in concentration more than 3% highly explosive and
hence not used for fumigation of rooms
• Mix with carbon dioxide or nitrogen to eliminate its explosive tendency
• Effective against all types of micro-organism including viruses and spores

FORMALDEHYDE GAS
• This is widely employed for fumigation of operation theatre and other clinics
• After sealing the windows and other outlets, formaldehyde gas is generated by
adding 150g of KMno4 to 280ml formalin for every 1000cu ft of room volume
• The reaction produces considerable heat and so heat resistant vessels should be
used
• After starting generation of formaldehyde vapour,the door should be sealed and
left unopened for 48 hours.

BETAPROPIOLACTONE
• It is a condensation product of ketone and formaldehyde with a boliling point of
163◦C
• Though as a gas it has a low penetrating power,it is more efficient for fumigating
purposes than formaldehyde
• For sterilization of biological products 0.2%BPL is used.

Dental operatory asepsis
• In the dental operatory, operatory surfaces that are repeatedly touched or soiled are
best protected with disposable covers(barriers)that can be discarded after each
treatment.
• For dental unit trays, paper, plastic film or surgical pack wraps (paper or towels) should
cover the entire tray.
• Clear plastic 15-gallon waste container bags fit many chair backs , control units , and x-ray
equipment
• Gigasept used to disinfect the dental chair.

Cleaning and disinfection strategies for blood spills
• The person assigned to clean the spill should wear gloves and other PPE as needed.
• Visible organic material should be removed with absorbent material (e.g., disposable
paper towels discarded in a leak-proof, appropriately labeled container).
• Nonporous surfaces should be cleaned and then decontaminated with either an hospital
disinfectant effective against HBV and HIV or an disinfectant with a tuberculocidal claim
(i.e., intermediate-level disinfectant).
• However, if such products are unavailable, a 1:100 dilution of sodium hypochlorite (e.g.,
approximately ¼ cup of household chlorine bleach to 1 gallon of water) is an inexpensive
and effective disinfecting agent

Asepsis of surgery theatre
• Fumigation is done by
1). Electric boiler method- 500 ml of formaldehyde (40%) added to distilled water in electric
boiler. When the water heats fumes are generated.

For dental radiograph
• Contamination of working area occurs from saliva.
• X-ray tube head, exposure selector and timer button are likely to get
contaminated by saliva.
• Precaution to be taken up :
• Put on gloves
• Place the film packets and film holders in special tray.
• Contaminated films(exposed films) to be placed in separate tray.
• Film holding device to be rinsed in running water to remove saliva.
• Metallic part to be autoclaved.
• Plastic attachments to be kept in chlorhexidine solution.
• Tube can be wrapped in disposable plastics.
• Film packets to be discarded in yellow bags.

For Biopsy specimen
• Biopsy collection & transportation can also be a source of infection.
• It should be kept in sturdy containers with secure lid.
• Avoid contaminating the external surface of the container.
• Swab used for collecting micro-organisms should be transferred slowly and carefully to
the swab container.

For cotton and gauze piece
• Packing or wrapping of the unsterilized cotton/ gauze piece in to a suitable container or
packaging material , for this purpose metal drums (small drum) are used.
• These drums are perforated in order to facilitate the free flow of steam during
sterilization.
• These material can also be wrapped with fabrics like nylon film bags or muslin cloth or
calico cloth
• The suitable packed material are correctly loaded into the sterilizer.
• The packing should do in such a way that it ensures satisfactory steam penetration and air
removal
• The sterilizer is closed and inside the sterilizer is replaced by steam.
• The material is exposed for 30-45 min at 121.c in autoclave.
• Switch off the sterilizer and condense the steam inside it., content of sterilizer are then
removed. The warm packs are not placed on a cold surface. It is done to avoid
condensation of steam in to water which may cause contamination through porous
wrappers.
• The container are labeled indicating the date of sterilization so as to prevent overlong
storage.

Impression disinfection
• Once an impression has been taken, rinse it under running water to remove any visible
debris.
• 5.25% sod. Hypochloride, /2% glutaraldehyde solution
Immersion Method
• This is the preferred method
• The impression is submerged in disinfection solution for 10 mins
• Every surface is disinfected.
• The impression can be left submerged for the manufacturer’s specified amount of time
without constant checking.
Spray Method
• This is not the preferred method because:
• Aerosols may be produced.
• Spraying does not guarantee that all areas are covered.
• Contact time is difficult to judge.

For dental cast
• Spraying until wet or Immersing in a 1:10 dilution of sodium hypochlorite or an iodophor
then rinse
• Casts to be disinfected should be fully set (i.e. stored for at least 24 hours)
• ADA recommends use of
Chlorine compounds
Iodophors
Glutaraldehyde.

Sterilization of bur
• Step 1.
• A necessary step prior to sterilizing a burr is meticulous cleaning from tooth tissue debris,
residues of dental materials, blood clots or a paste-like mixture of all the above with saliva.
• The most widely accepted cleaning method for burs and other micro instruments are
ultrasonic devices (baths) using suitable fluids and with the addition of enzymes with
proteolytic action.
• In these baths using suitable fluids at a temperature of about 60°C, burs vibrate at a
frequency of 60-80 kHz for at least 15 minutes. After the end of this procedure, burs are
free from foreign matter as well as oxides very often being deposited on their stem.
• Step 2.
• After taken out of the ultrasonic bath, burrs must be dried using an absorbent paper and
hot air.

• Step 3.
• They must be placed in an appropriate device for sterilization, depending on the material
• they are made of:
• 1) burs made of common carbon steel should not be placed in the autoclave because they
are oxidized. 2) on the contrary, burs made of stainless steel or tungsten carbide are not
affected. 3) dry heat ovens, ovens for chemical vapor sterilization and ethylene oxide
ovens are suitable for sterilizing all types of burs.
• However, dry heat ovens, due to prolonged heating involved, may seriously damage the
cutting edge of the burrs.
• 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.

Handpiece
• Routine between patient use of a heating process capable of sterilization (autoclaving , dry
heat, or heat/chemical vapor) is recommended for all high speed dental hand piece and
low speed hand piece
• Manufactures instruction for cleaning, lubricating and sterilization procedure should be
followed closely to ensure both the effectiveness and longevity of these instruments
• clean the outside of the handpiece with detergent and water – never clean or immerse the
handpiece in disinfectant solutions or the ultrasonic cleaner;
• lubricate the handpiece with pressurized oil for the recommended period;
• clean off excess oil;
• sterilize in a steam sterilizer; and
• run the handpiece briefly before use to clear excess lubricant. This step is not needed if an
air purge has been run at the end of the lubricating process prior to sterilization.

Endodontic instruments
• Glass Bead or salt sterilizers have been commonly used in endodontic offices.
• Sterilization of clean endodontic files, reames, lenturospiral can be achieved with glass
beads at 218◦C (424.4◦F) for 15 sec.
• Guttapercha points are sterile in the manufactures package. Contaminated points can be
sterilized with 5.25% sod. hypochloride for 1min.
• Researchers have found that gutta percha can be sterilized after exposure to gm+ve,
gm-ve and spore forming micro organism within a 1min after immersion in undiluted sod
hypochloride (Clorox)
• Immersion in polyvinyl pyrrolidone iodine for 6min is an alternative method for
disinfection of gutta-percha.
Ref –Microbiology of Endodontics and Asepsis in endodontic practice by John Ide ingle vol 1

• Silver cones sterilized by passing slowly over the flame for 3-4 time. Can also be sterilized
in hot salt sterilizer.
• Glass slab is sterilized by swabbing the surface with tincture of thiomersal, followed
by swabbing with alcohol
• Cement spatula is sterilized by flaming 3 or 4 times over bunsen flame.
Ref –Microbiology of Endodontics and Asepsis in endodontic practice by John Ide ingle vol 1

Handling of Extracted Teeth
• Disposal
• Extracted teeth that are being discarded are subject to the containerization and labeling
provisions outlined by OSHA's bloodborne pathogens standard .
• OSHA considers extracted teeth to be potentially infectious material that should be
disposed in medical waste containers.
• Should be cleaned, surface-disinfected with an EPA-registered hospital disinfectant with
intermediate-level activity (i.e., tuberculocidal claim), and transported in a manner
consistent with OSHA regulations.
• Extracted teeth containing dental amalgam should not be placed in a medical waste
container that uses incineration for final disposal.
• Commercial metal-recycling companies also might accept extracted teeth with metal
restorations, including amalgam. State and local regulations should be consulted regarding
disposal of the amalgam.

• Educational Settings
• Extracted teeth are occasionally collected for use in preclinical educational training.
• These teeth should be cleaned of visible blood and gross debris and maintained in a
hydrated state in a well-constructed closed container during transport.
• The container should be labeled with the biohazard symbol .
• Before being used in an educational setting, the teeth should be heat-sterilized to allow
safe handling.
• Microbial growth can be eliminated by using an autoclave cycle for 40 minutes , but
because preclinical educational exercises simulate clinical experiences, students enrolled
in dental programs should still follow standard precautions.
• Autoclaving teeth for preclinical laboratory exercises does not appear to alter their
physical properties sufficiently to compromise the learning experience
• However, whether autoclave sterilization of extracted teeth affects dentinal structure to
the point that the chemical and microchemical relationship between dental materials and
the dentin would be affected for research purposes on dental materials is unknown.

• Use of teeth that do not contain amalgam is preferred in educational settings because
they can be safely autoclaved.
• Extracted teeth containing amalgam restorations should not be heat-sterilized because of
the potential health hazard from mercury vaporization and exposure.
• If extracted teeth containing amalgam restorations are to be used, immersion in 10%
formalin solution for 2 weeks should be effective in disinfecting both the internal and
external structures of the teeth.
• If using formalin, manufacturer MSDS should be reviewed for occupational safety and
health concerns and to ensure compliance with OSHA regulations

Dental waterline and water quality
Current guidelines for the proper treatment of dental unit water lines include the following:
• Dental line water should contain <200colony forming units per ml(CFU/mL)
• For surgical procedure, use sterile or saline water from a single use source.
• Start each day by purging all lines by flushing thoroughly with water
• Purge all air and water from high speed handpiece for 20 to 30 sec after each patient
• Consider separate reservoir, chemical treatment protocols, and water delivery system
• Use anti retraction valves and terminal flush devices into the dental unit
• Drain the water lines at the end of the day
• Disinfect dental units attached to hospital main water supplies every 4months with
500ppm chlorinated water.
Ref – MCDONALD AND AVERY’S dentistry for child and adolescent first south Asian edition

Recent advances in sterilization
Plasma sterilizer
• Plasma is basically ionized gas. When you apply an electric field to a gas, it gets ionized
into electrons and ions.
• Plasma is usually comprised of UV photons, ions, electrons and neutrals.
• A plasma is a quasi-neutral collection capable of collective behavior
• Their combined photolytic, chemical and electric action efficiently kills most micro-
organisms
New infection and sterilization methods, W.A.rutala,D.J. Weber
Emerg infect dis 2007 march-april

Ozone
• Ozone sterilization is the newest in low-temperature
• sterilization method recently introduced in the US and is suitable for many heat sensitive
and moisture sensitive or moisture unstable medical devices
• Ozone sterilization is compatible with stainless steel instruments also.
• Ozone Parameters -the cycle time is approximately 4.5 hours, at a temperature of 850F -
940F.
New infection and sterilization methods, W.A.rutala,D.J. Weber

• VIRKON :
• Nonaldehyde Fumigator with Oxone, sodium dodecylbenzenesulfonate, sulfamic
acid & inorganic buffers.
BACILLOID RASANT :
Short term disinfectant;
• Formaldehyde free

AVAGARD-
• Waterless surgical hand rub

Reference
• Centre for disease control and prevention guidelines for infection control in
dental health care settings-2003,2016
• American dental association ,infection control guidelines,2016.
• Anantnarayan and paniker’s textbook of microbiology 7th edi
• Grossman’s endodontic practice 12th edi
• MCDONALD AND AVERY’S dentistry for child and adolescent first south
Asian edition
• New infection and sterilization methods, W.A.rutala,D.J. Weber
• Prevention and disease control by soben peter, 6th edi

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