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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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OBJECTIVEAt the end of the presentation

the 2nd year BDS students will know all about the sterilization.

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ContentsDefinitionIntroductionNeed of sterilizationClassification of InstrumentsMethods of sterilizationSterilization 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.

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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.

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b) Protein denaturingFunctions 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.

CriticalSemi 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 etc

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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.

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DENTAL CHAIR

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Methods of Sterilization

There are two types of

sterilization:1. Physical2. Chemical Physical Methods Heat Radiation

Microbial Control Methods

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. Phenols2. Alcohols3. 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 HEATMoist 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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AUTOCLAVINGInvented by Charles Chamberland in

1879Most economical method of sterilizationTime required at 121 C is 15 mins at 15

lbs of pressureMain 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 radiation2. Non Ionizing radiation.

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 METHODSIn Chemical methods of

Sterilization we use various chemical agents that includes,

1) Phenolic compounds2) Alcohols3) Aldehydes4) 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.

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2. Alcohols:

Kill bacteria (bactericidal), fungi and 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 includes1) Ethylene Oxide2) Formaldehyde gas3) 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 techniquesChemical indicatorsBiological indicators

These parameters evaluate both the sterilization conditions and procedure’s effectiveness

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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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ReferencesWikipediaSS HiremathGoogle ImagesSlide share

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