sterilization - nosheen

8/3/2019 Sterilization - Nosheen

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INTRODUCTION

Infectious diseases can be transmitted from oneperson to another.

Dentist & dental staff can be exposed to seriousinfectious disease on daily basis.

The dentist has the responsibility to thoroughlyunderstand disease transmission & prevent crossinfection.


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SOURCES OF INFECTION

Hands

Saliva

Nasal secretions Blood

Instruments &

Equipments etc.


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STERILIZATION

Sterilization is a physical or chemical processthat completely destroys or removemicroorganisms and all their forms (spores)

OBJECTIVES OF STERILIZATION:- To provide the highest standard of care.

To minimize the risk of infections.

To provide a supportive, informal, relaxed &non-threating operatory environment to the pt.


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METHODS OF STERILIZATION

Antiseptics

Ethylene oxide gas

Disinfectants

CHEMICALPHYSICAL

Heat

Radiation

Filtration

Dry

Moist


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Heat sterilization

Intensedry heat

Prolongeddry heat

DRY HEAT

PROLONGED DRY HEAT:

It kills microorganism by an oxidationprocess of cell proteins, a processrequiring very high temperature.


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PROLONGED DRY HEAT (CONT.)

It is very slow to penetrate instrument loads A margin of safety requires instruments to be

sterilized at 160C for 2hrs.

GUIDE-LINES FOR DRY HEAT:-

Temperature Duration of exposure 121C 6-12hrs 140C 3hrs

150C 2-1/2hrs 160C 2hr 170C 1hr


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DISADVANTAGES:

Slow instrument turn around because of poor

heat exchange. Potential damage to heat-sensitive instruments.

INTENSE DRY HEAT: (GLASS BEADSTERILIZATION):

Chair side sterilization of endo files can beaccomplished by using this type of sterilization.

This device is a metal crucible that heats a

transfer medium of glass beads.


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GLASS BEAD STERILIZATION(CONT):

Process:

Clean endo instruments of small mass are keptin transfer medium at temperature of 220C for15secs.

Transfer medium heats the endo instruments

through heat convection & kills any adherentmicroorganism.

ADVANTAGES:

Small size & convenience of sterilizer.


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Serves as emergency back up to other methodsof sterilization.

DISADVANTAGES: Only instrument of small size can be sterilized.

Only a few instruments can be sterilized at atime.

It is non-verifiable.


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It kills microorganism denaturation of protein, RNA

or DNA breakdown. It is more efficient than dry heat because it is

effective at much lower temperatures & requires lesstime as water is better than air at transferring heat.

The method could be used at different temperatures Temperature below 100iC

Temperature at 100iC

Temperature above 100i

C

MOIST HEAT


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TEMPERATURE BELOW 100C

Pasteurization: Pasteur used heat to reduce theno. of pathogens in liquid for preservation. Fore.g. Milk is pasteurized by being held in water at63C for 30 mins and cooled suddenly.

Tyndallization: heating at 56C for 60 mins forthree successive days is known astyndallyzation.


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Boiling: at 100C for 5 mins

Steam at 100C: this is done in a steamer

TEMPERATURE AT 100C

TEMPERATURE ABOVE 100C

Autoclave sterilization:In this, sterilization takes place by the use of steam under

pressure.


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AUTOCLAVE STERILIZATION

When steam comes in contactwith an object, it condenses &almost instantly releases thatstored heat energy, whichquickly denatures vital cellproteins.

It takes place in 15-30min at121C at the pressure of15lbs/sq.i

Saturated steam is much moreefficient than either dry heat orboil water.


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GUIDE-LINES FOR DRY HEAT:-

Temperature Duration of exposure

116C 60min 118C 36min

121C 24min

125C 16min 132C 4min

138C 1-1/2min


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Time required depend on type of load placed &its permeability.

Instruments placed in autoclave must beproperly arranged.

Non stainless steel metal may oxidize unlessprotected by a reducing agent prior to packagingor autoclaving.

1-2% sodium nitrite is an effective rust inhibitor.


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ADVANTAGES:

Relatively quick turnaround time .

Excellent penetration of packages Will not destroy cotton or cloth product.

Verifiable.

DISADVANTAGES: Material must be air dried at completion of cycle.

Corrosion or dulling of certain material as carbonsteel.

Cost.


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RADIATION

Ultra violet rays inhibits DNA replication

Used for disinfecting surfaces, sterilization ofatmospheric air e.g. operation theatres.

Ionizing radiations: X-Rays, Particle radiations.These produces free radicals, which break thecovalent bond of DNA and thus kill organisms.


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This is used for sterilizing solutions that containssera or amino acids that would be denatured by

heating and water Types of filters are cellulose membrane,

earthenware candles, asbestos, sintered glass

FILTRATION


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CHEMICAL METHOD

AntisepticDisinfectionEthylene oxide

gas


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DISINFECTION

A process of destroying pathogenic organisms or

rendering them inert. Less lethal than sterilization as it does not

necessarily kill all microbial forms, hence lacks

the margin of safety. Is reserved for large environmental surfaces that

cannot be sterilized.

Or where instruments cant withstand heat.


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DISINFECTANTS:

Glutaraldehyde 2% Isopropyl Alcohol 70%

Formaldehyde 3%

Sodium Hypochlorite

Iodophores 1% Iodine O-phenylphenol 9% &

O-benzyl-p-chlorophenol 1%

Quartenary ammoniumcompounds.

GLUTERALDEHYDE


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GLUTERALDEHYDE:-

Most commonly used.

Action: Kills microorganism by altering proteincomponents.

Useful as immersion sol. for instruments like

contaminated with blood, saliva etc Can be used in small containers specifically

designed to hold dental instruments.

Sol. Should be discarded once a week.

USES


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USES:

Used for wiping down of largesurfaces such as dental unit etc

Heat sensitive plastics, rubbers, fibreoptics, hand piece can be safelysterilized.

Available in 3 forms:

GLUTERALDEHYDE 2% ACIDIC

GLUTERALDEHYDE 2% NEUTRAL

GLUTERALDEHYDE 2% ALKALINE



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Brand name: sterall, wavicide

Exposure time: 10min

Temperature: 25C

Disinfectant level: high, intermediate

Less effective sporocide.

corrosive.

Irritating to eyes, nose & skin.


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GLUTERALDEHYDE 2% ALKALINE: Brand name: Cidex, Omnicide

Exposure time: 10min Temperature: room temp Disinfectant level: high Irritating to nose & skin.

GLUTERALDEHYDE 2% NEUTRAL: Brand name: Glutarex Exposure time: 10min Temperature: room temp Disinfectant level: high Irritating to eyes, nose & skin.


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ADVANTAGES:

Can sterile heat sensitive equipments.

Is relatively non-corrosive & non toxic.

DISADVANTAGES:

Has some odor.

Non-verifiable

Irritating to mucous membrane.


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IODOPHORES-1% iodine:

Is a combination of iodine & solubilizing agent. Releases small amount of iodine when diluted with

water.

Used to wipe off surfaces, plastics, hand piece, other

instruments like mirror,etc

Brand name: isodine, betadine

Exposure time: 10min

Temperature: room temp

Disinfectant level: intermediate to high


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ADVANTAGES:

Effective & less irritating.

Less corrosive to metal.DISADVANTAGES:

Inactivated by heat.

Contraindicated in iodine sensitive pt.

Stains plastics.

SODIUM HYPOCHLORITE:


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SODIUM HYPOCHLORITE:

Brand name: House holdbleach

Exposure time: 10-30min Disinfectant level: high,

intermediate

Action: The free chlorine in sol.

Inactivate enzymes & nucleicacid & denatures protein.

Uses: In a dilute solution canbe used to wipe down large

environmental surfaces,instruments.

Also used to disinfect GP pointsin 5.25% conc. for 1min.


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DISADVANTAGES:

Corrosive to metal.

Irritable to eyes, skin. Has strong odor.

ISOPROPYL ALCOHOL:

Although it is a good cleaning agent, it is notsuitable as it evaporates too rapidly.

However can be used to disinfect L.A cartridges.

QUARTENARY AMMONIUM COMPOUND:


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ETHYLENE OXIDE GAS ( GASEOUSSTERILIZATION) :

Most gentle method for sterilizing complexinstrument & delicate material.

Highly flammable mixed with CO2 or N2.

Readily diffusable through porous material such

as plastic & rubber. Kills microorganism by chemically reacting with

nucleic acid.

Temperature: 50C

Time: kill all including spores within 3 hrs.


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ADVANTAGES:

Effective at low temperature.

Excellent penetration. Can be used for heat sensitive instruments like

hand piece.

DISADVANTAGES:

More time required to complete each cycle.

Requires aeration for 24 hrs or more before it issafe to use.

Cost.

ANTISEPTICS


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ANTISEPTICS

Agent that prevent the growth or action ofmicroorganism on living tissue.

Applied to the surface of body, open wounds orabraded tissue surfaces or mucous membrane.

Used to prep the hands before gloves are donned

EXAMPLES

Volatile: alcohol, chloroform

Phenols: Lysol, dettol

Metallic salts: mercuric chloride Detergents: soap

Iodophores , chlorhexidine etc


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PRACTICAL ASEPSIS

THE HANDS: Major route of

transmission of oralmicroorganism

Nails should be kept short All rings & bracelets be

removed prior to ptcontact

Hands should be cleaned

with anti-septic soap. Gloves must be worn. Poly ethylene over gloves

should also be be used

when talking on phone or


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FACIAL PROTECTION:

It includes

Protective eye wear Face mask

HAIR

CLOTHING


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MERCURY TOXICITY

It can produce a toxic effect ifsufficient amount is absorbedthrough lungs, skin or GIT.

PREVENTIVE MEASURES REQUIREDIN DENTAL OFFICE:

It should be kept in unbreakabletightly sealed container.

Spills & leaks should be cleanedimmediately

Wear mask as aerosol produceddurind cutting procedureinvolving Hg contains Hgvapours

Apply rubber dam to reduce


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OPERATORY ASEPSIS

It can be achieved in two ways:

First is to wipe off floors, flat

surfaces. Second to cover surfaces with

protective shields.

COVERINGS:

Most useful & simple are paper,plastic & foil

A new cover is used for each

patient.


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APPLICATION OF COVERINGS

Head rest, high velocity vaccum: plastic bag

Switches, controls: plastic or small pieces of foil

Triplex syringe: narrow plastic bag or use

disposable one Light handles of unit: sterile plastic sleeves

Light switch: short length of soda straw

Light cure device: plastic wrapper around the tip,handle & control trigger

X-ray cone & head: plastic wrap or paper securedwith tape.

sterilization - nosheen

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