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Sterilization in Dentistry

Presented by;M. Humayun

Afridi

Assisted By; Taif Ahmad And

Saqib Habib

Khyber College Of Dentistry

Peshawar

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STERILIZATION IN

DENTISTRY

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OBJECTIVE

At the end of the presentation the 2nd

year BDS students will know all about

the sterilization.

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Contents

Definition

Introduction

Need of sterilization

Classification of Instruments

Methods of sterilization

Sterilization monitoring

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What is Sterilization?

DEFINITION

“Sterilization is the process by

which all forms of microbial life

from surface,medium and

instruments are destroyed by

various physical and chemical

methods”

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Sterilization in Dentistry

Sterilization procedures are very

important to any good dental practice

Patients mouth are teeming with

microbes.

As Dental unit come across large

number of patients , an inherent

potential for spreading infectious

germs between patients and dental

staff, through contaminated

instruments and surfaces.7

Why we need

Sterilization? Microorganisms capable of causing

infection are constantly present in the

external environment and on the

human body.

Microorganisms are responsible for

contamination and infection.

The aim of sterilization is to remove or

destroy them from materials or from

surfaces.

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How sterilization destroys

microbes?

a) Alteration of cell

wall or

cytoplasmic

membrane;

Cell wall

maintains the

integrity of cell.

When disrupted

cannot prevent cell

from bursting and

cellular contents leak

out.9

b) Protein denaturing

Functions of

protein depends on

its specific 3-D

shape.

Various sterilization

methods denature

proteins and as a

result 3-D shape

and their functions

are lost.

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c) Interference with Nucleic Acid

Nucleic Acid is

considered as

controlling centre

of the cell.

Various methods of

sterilization

methods can

I. Produce mutation,

II. Interfere the process

of transcription.

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Sterilization of Dental

Instruments

Spaulding in 1968, classify dental instruments into three categories depending on the risk of transmitting infection.

Critical

Semi critical

Non critical

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CRITICAL INSTRUMENTS

Critical instruments are those that penetrate soft tissue, bone or blood stream.

They have the greatest risk of transmitting infection

They should be heat sterilized between patient uses.

Examples of critical instruments include surgical instruments,forceps, scalpels, scalers, and burs.

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SEMI CRITICAL

INSTRUMENTS Semi-critical

instruments are those

that do not penetrate

soft tissues or bone

but contact mucous

membranes

These instruments

should be sterilized or

high-level disinfection

is appropriate.

Examples: Mirrors,

reusable impression

trays and amalgam

condensers etc14

NON CRITICAL INSTRUMENTS

Non-critical

instruments are

those that come in

contact with intact

skin.

Risk of transmission

of infection is

minimum.

Examples:X-ray

heads,pulse

oximeter,BP cuff

,dental chair etc.15

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DENTAL

CHAIR

Methods of Sterilization

There are two types of sterilization:

1. Physical

2. Chemical

Physical Methods

Heat

Radiation

Microbial ControlMethods

Physical Agents

Chemical Agents

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Agents used in sterilization

Physical

agents:

1. Dry heat: flaming,

Moist heat: boiling,

steam under

pressure.

2. Radiation

Chemical

agents:

1. Phenols

2. Alcohols

3. Aldehydes

4. Gases: ethylene

oxide,

Formaldehyde

gas, ozone……

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Physical

Agents

Heat

Dry

Direct Flaming

Moist

Steam Under

Pressure

(autoclaving)

Radiation

Ionizing

X Ray,

Cathode,

Gamma

Non Ionizing

UV

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Dry Heat:“To sterilize

Forceps,

Scissors,

Scalpels.”

• Direct Flaming:

Used to sterilize

inoculating loops

and needles. Heat

metal until it has a

red glow.

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MOIST HEAT

Moist heat is more effective than dry

heat because water is good conductor

of heat than air

Mode of action: Denaturing of protein

TYPES

◦ Boiling

◦ Steam under pressure(autoclaving)

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AUTOCLAVING

Invented by Charles Chamberland in

1879

Most economical method of sterilization

Time required at 121 C is 15 mins at 15

lbs of pressure

Main Components of autoclave:

• Consists of vertical or horizontal

cylinder of stainless steel

• Lid , pressure gauge and a safety valve.

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ADVANTAGES

1. Short efficient cycle time.

2. Rapid and effective

3. Ability to process a wide range of

materials

4.Good penetration

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AUTOCLAVE

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RADIATION

There are mainly two types of

Radiations used in dentistry.

1. Ionizing radiation

2. Non Ionizing radiation.

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Ionizing radiations:

Ionizing radiation includes X-Rays and Gamma rays.

Cause mutations in DNA and produce peroxides.

These are commercially used for sterilization of disposable items. (cold sterilization).

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Nonionizing radiation

Non ionizing radiation includes

UV light and Infrared.

Affects 3-D structure of Proteins and nucleic acids.

Suitable for transparent fluids, and surfaces of objects.

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CHEMICAL METHODS

In Chemical methods of Sterilization

we use various chemical agents that

includes,

1) Phenolic compounds

2) Alcohols

3) Aldehydes

4) Gaseous sterilizers

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1. Phenols and Phenolics:

Phenol acts as protoplasmic

poison, penetrates & disrupts cell

wall and cause bacterial death by

inactivation of essential enzyme

systems.

Used for decontamination of

hospital environment including

laboratory surfaces, & for

noncritical medical & surgical

items.29

2. Alcohols:

Kill bacteria (bactericidal), fungiand viruses.

Act by denaturing proteins and disrupting cell membranes.

. Used as skin antiseptic to wipe microbes off skin before injections.

Also used for disinfection of thermometer, probes and external surfaces of stethoscope.

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3. Aldehydes:

Inactivate proteins by forming covalent cross links with several functional groups.

Commonly used aldehyde is FORMALIN (37% aqueous solution).

used extensively to inactivate viruses & bacteria in vaccines.

Also used to sterilize metal instruments.

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4. Gaseous Sterilizers:

Denature proteins, by

replacing functional

groups with alkyl

groups. Also reacts with

DNA & RNA.

These includes

1) Ethylene Oxide

2) Formaldehyde gas

3) Ozone…….

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Sterilization

Heat

Radiation

Gases

Chemicals

Methods of Sterilization

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STERILIZATION MONITORING

There are 3 methods of monitoring

sterilization:

Mechanical techniques

Chemical indicators

Biological indicators

These parameters evaluate both the

sterilization conditions and

procedure’s effectiveness 34

MECHANICAL INDICATORS: Includes

assessing cycle time,temperature and

pressure by observing the displays on the

sterlizers

CHEMICAL INDICATORS: They allow

detection of equipment malfuctioning and

help in identifying procedural errors

BIOLOGICAL INDICATORS: Most

accepted for monitoring sterilization

process

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References

Wikipedia

SS Hiremath

Google Images

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