Sterilization and disinfection in dentistry

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STERILIZATION & DISINFECTION

Presented by Dr. Aishwarya Hajare1st year post graduate student

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Contents- INTRODUCTION

TERMINOLOGIES

HISTORY

CLASSIFICATION

DETAILS OF INDIVIDUAL AGENTS

BIOLOGICAL CONTROLS

STERILIZATION IN DENTISTRY

STERILIZATION IN PERIODONTICS

INFECTION CONTROL

WASTE MANAGEMENT

RECENT ADVANCES IN STERILIZATION AND DISINFECTION

CONCLUSION

REFERENCES

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IntroductionMicroorganisms are ubiquitous.

Since pathogenic microorganisms cause contamination, infection and decay, it becomes necessary to remove or destroy them from materials and areas.

This is the objective of infection control and sterilization.

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STERILIZATION Sterilization (or sterilisation) is a term referring to any

process that eliminates or kills all forms of life and other biological

agents including transmissible agents (such as fungi, bacteria, viruses, prions,

spore forms, unicellular eukaryotic organisms such as Plasmodium, etc.) present

in a specified region, such as a surface, a volume of fluid, medication, or in a

compound such as biological culture media.

( WHO Glossary )

STERILE: Free from all living microorganisms; usually described as a

probability (e.g., the probability of a surviving microorganism being 1 in 1

million).(CDC guidelines 2008)

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DISINFECTION: Destruction of pathogenic and other kinds of

microorganisms by physical or chemical means. Disinfection is less lethal

than sterilization, because it destroys the majority of recognized pathogenic

microorganisms, but not necessarily all microbial forms (e.g., bacterial

spores).(CDC guidelines 2008)

Disinfection is a process of removing or killing most, but not all, viable

organisms.

MIMS-PLAYFAIR,5th

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ANTISEPSIS is the prevention of infection, usually by

inhibiting the growth of bacteria in wounds or tissues

BACTERICIDAL AGENTS: Those which are able to kill

bacteria.

BACTERIOSTATIC AGENTS: Only prevents the

multiplication of bacteria which may however remain alive.

DECONTAMINATION: The process of rendering an article

or area free of danger from contaminants, including microbial,

chemical, radioactive and other hazards.

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History of sterilizationHippocrates of Cos (460-377 BC), was the first to separate medicine from

philosophy and disproved the idea that disease was punishment for sin. He

also advocated irrigation of wounds with wine or boiled water,

foreshadowing asepsis.

Ignaz Semmelweis, an Hungarian obstetrician, advocated in 1847 the value

of handwashing and fingernail scrubbing.

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In 1862, French chemist and microbiologist

Louis Pasteur publishes his findings on how

germs cause disease, which he later uses to

develop the pasteurization process.

Joseph Lister, an English physician, reduced the

mortality rate of his patients in 1867 by using a

carbolic solution spray as he operated, he then

used it in the wound.

Charles Chamberland, Louis Pasteur’s pupil

and collaborator, developed the first pressure

steam sterilizer, or autoclave in 1876.

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The research of Robert Koch and his associates in 1881 on the disinfecting

properties of steam and hot air mark the beginning of the science of

disinfection and sterilization. They devised the first non pressure flowing

steam sterilizer.

Aesculap created the first rigid instrument container, originally made of

stainless steel, in Germany. In the early 1900’s, responding to the needs of

the military hospitals and aid stations, Aesculap manufactured chrome-

plated containers for safe transport of sterile instruments..

METHODS OF STERILIZATION AND DISINFECTION

PHYSICAL METHODS

• SUNLIGHT• DRYING• DRY HEAT• MOIST HEAT• FILTRATION• RADIATION• ULTRASONIC AND SONIC

VIBRATIONS

CHEMICAL METHODS

• ALCOHOLS• ALDEHYDES• DYES• HALOGENS• PHENOLS• SURFACE-ACTIVE

AGENTS• METALLIC SALTS• GASES

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Sunlight:- Active germicidal effect due to the combined effect of U.V and heat rays. e.g.:- river, tanks & lakes.

Drying:- 4/5ths of weight of bacterial cell consist of water and hence drying has a deleterious effect on many bacteria.

Heat :- most reliable and commonly applied way of sterilization Dry heat Flaming:- Inoculating loops or wires, the tip of

forceps & needles and spatulas are held in a bunsen flame till they become red hot in order to be sterilized.

Incineration :- Rapidly destroying materials such as soiled dressings, bedding, animal carcasses, pathological materials etc.

PHYSICAL AGENTS

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DRY HEAT

Principle- - Protein denaturation.

- Oxidative damage. - Toxic effects of elevated levels of electrolytes.

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HOT AIR OVEN:-

It’s the most widely used mode of sterilization

Temp.- 160°C ( 320° F ) for 1-2 hr.

Uses :- - Glasswares like glass syringes, petridishes, flasks,

pipettes & test tubes. - Surgical instruments like scalpels, scissors, forceps

etc..

- Chemicals such as liquid paraffin, fats, greases, Sulphonamide, dusting powder etc.

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Precautions:-1) Not to be overloaded.

2) Must be fitted with fans for even distribution of

hot air.

3) Materials to be sterilized should be perfectly dry.

4) Rubber materials (except silicone rubber) will

not withstand the temperature.

5) Allowed to cool for 2 hrs before opening the

doors.Advantage: Economical.

Does not rust metals

Easily monitored .

Used for anhydrous oils & powder.

Disadvantage :Hot air is bad conductor of heat hence it has less penetrating power

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• pasteurisation of milk.• Inspissation.• Vaccine bath.• Low temperature steam formaldehyde.

TEMPERATURE BELOW 100O C

• Boiling• Tyndallisation• Steam sterilizer at 1000 C

TEMPERATURE AT 100O C

• AutoclaveTEMPERATURE ABOVE 100O

MOIST HEAT

AUTOCLAVING 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.

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AUTOCLAVE

Three major factors for effective autoclave:

1. Pressure: 15psi.

2. Temperature: 121oC

3. Time: 15 mins. Higher temperature and pressure require shorter time

for sterilisation.

Pressure (psi)

• 15• 20• 20

Temperature (°C)

• 121• 126• 134

Time (mins)

• 15• 10• 3

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Types of autoclaveDOWNWARD DISPLACEMENT Also known as Gravity displacement unit. This is because of the method of air removal in the sterilization

chamber.

POSITIVE PRESSURE DISPLACEMENT It’s an improvement over downward displacement autoclave. Steam is created in a second, separate chamber and held until the

proper amount to displace all of the air in the sterilization chamber is accumulated.

The steam is then released into the sterilization chamber in a pressurized blast, forcing the air out through the drain hole and starting the sterilization process

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NEGATIVE PRESSURE DISPLACEMENT

one of the most accurate types of unit available

Once the sterilization chamber door is closed, a vacuum pump removes

the air.

Steam is created in a second, separate chamber.

Once the air has been completely removed from the sterilization

chamber, the steam is then released into the sterilization chamber in a

pressurized blast much like that of a positive pressure displacement

unit.

The negative pressure displacement unit is able to achieve a high

"Sterility Assurance Level" (SAL), but the system can be quite large

and costly.

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TRIPLE VACUUM AUTOCLAVE

A triple vacuum autoclave is set up/function in a

similar fashion to a negative pressure displacement.

This is repeated three times, hence the name "triple

vacuum" autoclave. This type of autoclave is suitable

for all types of instruments and is very versatile

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Classification of a autoclave

Classification Suitable for Processing Used by

N Type (Downward Displacement)

Unwrapped solid instruments for immediate use.

S Type (Vacuum) Items specified by the autoclave manufacturer. N.B. Eschmann units suitable for naked and single wrapped solid and hollow items.

Medical SurgeriesPodiatrist Tattooist Body Pierces

B Type (Vacuum) Unwrapped & wrapped solid and hollow instruments. Porous loads, e.g drapes & gowns.

DentistsPlastic surgeonsDay surgeries

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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.

Considerations during autoclaving

USES:

Disposable syringes, Non disposable syringes,

Glassware, Metal instruments, surgical dressing,

Surgical instruments, Laboratory equipment, Culture

media, Pharmaceutical products.

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Advantage:-

Economical.

Good penetration.

Short cycle time.

Easily monitored

No special chemicals or exhaust required.

Disadvantage:-

Moisture retention

Causes corrosion

Carbon steel gets damaged

Dulling of unprotected cutting edges.

Destruction of heat sensitive materials.

Filtration helps to remove bacteria from heat labile such as sera and solutions of sugars or antibiotics used for preparation of culture media.

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Candle Filter

Sintered Glass Filters Membrane Filters

Asbestos Filter

RADIATION

1) Non-ionising radiation: Uses longer wavelength and lower energy. And hence lose

the ability to penetrate substances, and can only be used for sterilizing surfaces

Eg. infrared radiation is used for rapid mass sterilization of prepacked items eg. Syringes, catheters.

UV radiation is used for disinfecting enclosed areas like operation theaters, laboratories.

2) Ionising radiation: Uses short wavelength, high-intensity radiation with high

penetrative power to destroy microorganisms. This radiation can come in the form of gamma or X-rays

that react with DNA resulting in a damaged cell. Since there is no appreciable increase in the temperature, it

is also known as COLD STERILIZATION. Used for sterilizing plastics, swabs, metal foils etc. 25

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Gamma radiation

The Nature of Gamma Radiation -A form of pure energy that is generally characterized by its deep penetration and low dose rates, Gamma Radiation effectively kills microorganisms throughout.

Benefits of Gamma Radiation include:

1. precise dosing

2. rapid processing

3. uniform dose distribution

4. system flexibility

5. dosimetric release–the immediate availability of product after processing.

Penetrating Sterilization: Even with High-Density Products Gamma Radiation is a penetrating sterilant.

Substantial Decrease in Organism Survival: Gamma Radiation kills microorganisms by attacking the DNA molecule.

ULTRASONIC and SONIC CLEANING

More effective than manual cleaning. Removes dried serum, whole blood, plaque, zinc phosphate

and polycarboxylate cements from instruments, metal surfaces and dentures.

Minimizes handling of contaminated instruments. During cleaning, totally submerge instruments in the

ultrasonic solution for 2 to 20 minutes . Ultrasonic solution should be changed atleast once a day.

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Flash sterilization

“Flash” steam sterilization was originally defined by Underwood and Perkins as sterilization of an unwrapped object at 1320C for 3 minutes at 27-28 lbs. of pressure in a gravity displacement sterilizer.

Currently, the time required for flash sterilization depends on the type of sterilizer and the type of item (i.e., porous vs non-porous items).

Uses:

- Flash sterilization is considered acceptable for processing cleaned patient-care items that cannot be packaged, sterilized, and stored before use.

- It also is used when there is insufficient time to sterilize an item by the preferred package method.

BIOLOGICAL CONTROLS FOR DIFFERENT STERILIZATION METHODS

METHOD OF STERILIZATION

BIOLOGICAL CONTROL

Hot Air Oven Bacillus subtilis subsp. NigerClostridium tetani

Autoclave Bacillus stearothermophilus

Filtration Serratia marcescens, Pseudomonas diminuta

Ionizing Radiation Bacillus pumilis 29

CHEMICAL AGENTS

LIQUIDS GASES• Alcohols• Aldehydes• Phenols• Halogens• Heavy Metals• Surface Active Agents• Dyes

• Formaldehyde• Ethylene Oxide• Plasma

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MODE OF ACTION OF CHEMICAL AGENTS

Protein coagulation

Disruption of the cell membrane

Removal of the free sulphydryl groups

Substrate competition

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CLASSIFICATION OF INSTRUMENTS

Critical instruments

Semi-criticalInstruments

Non-critical Instruments

Penetrate the soft tissue Contact the bone Enter into or contact the

blood stream They should be

thoroughly cleaned and heat sterilized if they are to be reused.

Eg: Surgical instruments,Scalers, ScissorsSurgical dental bursScalpel blades ForcepsBone grafts

Contact the mucous membrane but will not penetrate the soft tissue

Eg : Mouth mirror, impression trays, handpieces, probe, tweezers

Come into contact with intact skin

Eg : X-Ray tubes, Light handles, Counter tops

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ALCOHOL

Mechanism of Action : Denaturation of Proteins Isopropyl alcohol 70% ethyl alcohol

Ethyl alcohol is active against the fungal spores and used to treat cabinets and incubator

Suitable for skin preparation before venepuncture

Disadvantage : . Inflammable . Mucous membrane irritant.

. Promotes rusting.

Used as a skin disinfectant

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A)Formaldehyde (formalin)

In aqueous solution it acts as a bactericidal and sporicidal

Active against Gram -ve bacteria, spores, viruses (HB, HIV) & fungi

Aqueous soultion: Formalin(37% solution) - 10% formalin +

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.

ALDEHYDES

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High level disinfectant

Especially active against tubercle bacilli,f ungi and viruses

Less toxic than formaldehyde

Can be safely used to treat corrugated rubber anaesthetic tubes, face masks, metal instruments.

Exposure time: > 10hrs.

B.GLUTARALDEHYDE / CIDEX ( 2% alkaline NaHCO3)

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PHENOLS: Acts by cell membrane damage thus releasing cell contents and

causing lysis

Eg. Cresol ( LYSOL) ,chlorhexidine ( SAVLON),chloroxylenol (DETTOL)

Phenol is commonly found in mouthwashes, scrub soaps and surface disinfectants

Low efficiency disinfectant

Used for decontamination of the hospital environment, including laboratory surfaces, and noncritical medical items.

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HALOGENS :

A) Chlorine compounds:

Bleaching powder or hypochlorite solution

mostly used disinfectant for HIV infected

material.

in concentration of 0.05 or 0.5% used for

surface material and instruments disinfection

Should be prepared daily because of

instability of sodium hypochlorite solution

Active against bacteria, spores, fungi and

viruses (HB, HIV)

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B) IODOPHORS & IODINE Active against bacteria, spores & some

viruses & fungi

Suitable for skin preparation, mouthwash & as a surgical scrub

(7.5% Povidone+iodine= Betadine)

SALTS

Salts of heavy metals have toxic effect on bacteria.

The salts of copper , silver and mercury are used as disinfectant.

SURFACE ACTIVE AGENTS

substances which alter energy relationships at

interfaces,producing a reduction of surface tension, are known

as surface active agents. E.g. quaternary compounds

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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.

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RECOMMENDED CONCENTRATIONS

DISINFECTANT CONCENTRATION

Ethyl Alcohol 70%

Gluteraldehyde 2%

Lysol 2.5%

Savlon 2%

Dettol 4%

Bleaching powder (Calcium hypochlorite) 14 gm in 1 L water

Sodium hypocholorite 1%, 0.1%

Betadine (Iodophore) 2%

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STERILISATION AND DISINFECTION IN DENTAL CLINIC

The four accepted methods of sterilization in dental offices are:

Steam pressure sterilization (autoclave)

Chemical vapor pressure sterilization(chemiclave)

Dry heat sterilization(dryclave)

Ethylene oxide(ETOX) sterilization

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It is performed in a steam autoclave. For light load of

instruments the time required at 121o C is 15 minutes at 15lbs of

pressure. It works on principle as that of pressure cooker.

Advantages: rapid and effective.

Disadvantages: items sensitive

Tends to rust carbon steel instruments and burs.

Sterilization of burs in autoclaves.

burs can be protected by keeping them submerged in small

amounts of 2% sodium nitrite solution.

Steam pressure sterilization(autoclave)

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Performed in a chemiclave.

Operate at 131oC and 20lbs of pressure. they are similar to steam

sterilizer and have cycle of 30minutes.

• carbon steel and other corrosion sensitive instruments and pliers

are sterilized without rust or corrosion.

• items sensitive.

The 1938 patent of Dr. George Hollenback and the work of

hollenback and harvey in 1940s culminated in the development of

an unsaturated chemical vapor system , also called harvey

chemiclave.

Chemical vapor pressure sterilization

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Advantages

1. Carbon steel and other

corrosion-sensitive

instruments are said to be

sterilized without rust.

2. Relatively quick turnaround

time for instruments.

3. Load comes out dry.

4. Sterilization is verifiable.

Disadvantages

1. Items sensitive to the

elevated temperature will be

damaged. Vapor odor is

offensive, requires aeration.

2. Heavy cloth wrappings of

surgical instruments may not

be penetrated to provide

sterilization.

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Conventional dry heat ovens

Short cycle, high temperature dry heat oven.

They have heated chambers that allow air to circulate by gravity flow.

A rapid high temperature processing that uses forced draft oven(air circulates with a

fan or blower)

Operate at approximately 188oC-191oC

Dry heat sterilization

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Advantages1.Reasonable price

2. carbon steel instruments and

burs do not rust or corrode or lose

temper or cutting edges.

3. Rapid cycles possible at high

temperatures

Disadvantages 1.rubber and plastic materials

might damage.

2. heavy load of instruments

defeats sterilization.

3. Improper calibration may

damage instruments

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Etox sterilization is the best method for sterilizing complex instruments and delicate materials.

Advantages Operates effectively at low temperatures Gas is extremely penetrative Can be used for sensitive equipment like handpieces. Sterilization is verifiable

Disadvantages Potentially mutagenic and carcinogenic. Requires aeration chamber ,cycle time lasts hours Usually only hospital based.

Ethylene oxide sterilization

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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.

Plastic restaurant silverware bags it suction handles and

air water syringe handles.

Gigasept which contains succindialdehyde and

dimethoxytetrahydrofuran are used for disinfection of

plastic and rubber materials eg: dental chair

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Asepsis of surgery theaters Fumigation is done by two methods:

1. Electric boiler method- 500 ml of formaldehyde

(40%) added to distilled water in electric boiler.

When the water heats fumes are generated.

2. Potassium permanganate – heat is induced by

oxider action of potassium permanganate. 500ml

of formaldehyde is added to potassium

permanganate which reacts and generates fumes.

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DENTAL RADIOGRAPHY

CDC(MMWR),dec19,2003vol.52

• 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 :

1. Put on gloves.

2. Place the film packets and film holders in special tray.

3. Contaminated films(exposed films) to be placed in

separate tray.

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4. Film holding device to be rinsed in running water to remove

saliva.

5. Metallic part to be autoclaved.

6. Plastic attachments to be kept in chlorhexidine solution.

7. Wipe the x-ray tube head, exposure selector, timer button and film

packets with detergents.

8. Tube can be wrapped in disposable plastics.

9. Film packets to be discarded in yellow bags.

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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.

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• BIO-FILMS :


• Tubes connecting hand-pieces, air/water syringe &

ultrasonic scaler unit are harbor of wide range of micro-

organisms.

• They colonize and replicate on the inner surface of

tubings.

• They serve as reservoir for micro-organisms.

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Following measures should be taken to prevent this :

A) Anti-retraction valves : (one way flow check valve). To prevent

transfer or aspiration of potentially infected material in the tubings.

B) Bacterial filter : Filters to be fitted in water lines of hand-pieces &

water syringes.

C) Chemical Disinfectants : Tubings are flushed with disinfectants like

sodium hypochlorite.

D) Aspirators : Cleaned and flushed after every patient for 20 – 30

secs.

To be flushed with disinfectant at the end of the day.

Impression trays are sterilized as follows

metallic - autoclave

plastic – ethylene oxide

Disinfection of alginate impressions –

Methods

- Spraying

- Immersion

Iodophors, sodium hypochlorite (1:10 concentration ) ,

phenols, formaldehyde, glutaraldehyde.59

DENTAL CASTS CDC(MMWR),dec19,2003vol.52

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)

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ADA recommends use of Chlorine compounds Iodophors Combination of synthetic

phenols Glutaraldehyde.

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• Sterilize instruments like articulators, wax knives, spatula, shade

guide, acrylic bur etc.

• Custom impression trays, base plates, occlusal rim and all other

prosthesis must be disinfected, after construction & before use in

patient.

• Articulators, casts, base plates to be disinfected by 1:10 chlorine

solution following each session or before returning to laboratory.

• Dentures washed & soaked in sodium hypochlorite for 5 mins

before delivery.

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ROTARY INSTRUMENTS - BURS

Diamond and carbide burs:

After use they are placed in 0.2% gluteraldehyde and sodium phenate (Eg. Sporicidin) for at least 10 minutes,

cleaned with a bur brush or in an ultrasonic bath.

Sterilize in an autoclave or dry heat

Steel burs: May get damaged by autoclaving. Can be sterilized by using a chemical vapor sterilizer or glass bead sterilizer at 2300C for 20-30 seconds.

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ENDODONTIC INSTRUMENTS

CDC(MMWR),dec19,2003vol.52• Glass Bead or salt sterilizer is the best option, but they do not

sterilize the handle.

• Sterilization achieved in 10 seconds

• Dry heat is used, with instruments in closed metal or perforated metal

boxes.

• Sterilization achieved at 218oC for 15 seconds

• Gutta percha points are pre-sterilized.

• Contaminated points are sterilized by 5.25% sodium hypochlorite.(1

min immersion).

• Then rinse with hydrogen peroxide & dry it.

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• Silver cones sterilized by passing slowly over the flame

for 3-4 times.

• Can also be sterilized in hot salt sterilizer.

• Files to be handled with tweezer.

• Glass slab is sterilized by swabbing the surface with

tincture of thiomersal, followed by swabbing with

alcohol.

• Cement spatula is sterilized by flamming 3 or 4 times

over bunsen flame.

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HANDPIECE SURFACE CONTAMINATION CONTROL

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IMPLANTS Pre sterilized with Gamma radiation In case the implants needs to be re-sterilized conventional

sterilization techniques are not satisfactory Steam sterilization should not be used as it results in contamination

of surfaces with organic substances Dry heat sterilization also leaves organic and inorganic surface

residue Radio frequency glow discharge technique (RFGDT) or Plasma

cleaning is used. In this, material to be cleaned is bombarded by high energetic ions

formed in gas plasma in a vacuum chamber. Removes both organic and inorganic contaminants.

Sterilization in periodontal clinic All diagnostic instruments are sterilized by washing in korsolex and

sterilized. Periodontal instruments

SHARP

e.g. knives,

scissors,

Files

Tissue holding forceps

BLUNT

Mouth mirrors,

tweezers,

artery forceps,

suture holding forceps

Periosteal elevator

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Sharp instruments are ideally sterilized by :

conventional hot air oven

by not sterilized: Boiling Autoclave 2% glutaraldehyde

Blunt instruments are sterilized by Autoclave

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Sutures Sutures are pre sterilized by gamma radiation Sutures are re- sterilized by two recommed methods are

1. Soak for a full 10 minutes completely immersed in povidone iodine 10% solution, then rinse in sterile saline/water.

2. Ethylene Oxide – gas sterilisation.

Sterilising/disinfecting by other methods (autoclaving, boiling, alcohol-soaking) are not recommended. Glutaraldehyde has been taken off the market since May 2002. It was never intended to be a suture soaking solution due to its high toxicity and the inability to ensure that all the solution is rinsed off before use

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ULTRASONIC SCALERS

CDC(MMWR),dec19,2003vol.52 Soak inserts in a container containing 70% isopropyl alcohol for removal

of organic debris. Rinse cleaned inserts thoroughly in warm water to remove all chemicals.

As a final rinse, replace the insert into the scaler handpiece and operate the scaler for 10 seconds at the maximum water flow setting to flush out any retained chemicals

Dry inserts completely with air syringe Package in proper wrap, bags, pouches, trays, or cassettes. Add spore

tests and chemical indicators. Ethylene Oxide is the preferred method of choice Dry heat and chemical vapor methods of sterilization are considered

ineffective methods with risk of damage to materials as per American Dental association Supplement to J.A.D.A. 8/92.

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Effect of sterilization on instruments

Sterilization Type of instrument

Stainless steel Carbon steel

Saturated steam at 250°F Amorphous substance formed near cutting edge; no dulling.

Dulling and oxidation of cutting surfaces

Formalin-alcohol vapor at 270°F

Cracking of wire edge; no dulling.

Some oxidation of surfaces; no dulling.

Dry heat at 320°F Chipping of wire edge; no dulling.

No visual change.


No visual change

Effects of Sterilization on Periodontal Instruments Roger B. Parkes,* and Robert A. Kolstadf Accepted for publication 31 August 1981

Recent advances in sterilization and disinfection Various new methods of sterilization are under investigation and

development.

Peroxide vapor sterilization - an aqueous hydrogen peroxide

solution boils in a heated vaporizer and then flows as a vapor into

a sterilization chamber containing a load of instruments at low

pressure and low temperature

Ultraviolet light - exposes the contaminants with a lethal dose of

energy in the form of light. The UV light will alter the DNA of

the pathogens. Not effective against RNA viruses like HIV.

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Plasma Sterilization 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.

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Ozone Ozone sterilization is the newest low-temperature sterilization

method recently introduced in the US and is suitable for many

heat sensitive and moisture sensitive or moisture stable

medical devices

Ozone sterilization is compatible with stainless steel

instruments.

Ozone Parameters • The cycle time is approximately 4.5

hours, at a temperature of 850F – 940F.

Newer Disinfectants Persistent antimicrobial-drug coating that can be applied to inanimate and

animate objects containing silver (Surfacine)

A high-level disinfectant with reduced exposure time (ortho-

phthalaldehyde)

An antimicrobial drug that can be applied to animate and inanimate objects

(superoxidized water)

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INFECTION AND INFECTION CONTROL

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BASIC CONCEPT OF INFECTION CONTROL

Prevent spread of infection from the Clinician to the patient

Prevent the spread of infection from the Patient to the Clinician

Prevent the spread of infection from one patient to another

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Patient

OperatorOther personnel

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For routine dental examination procedures, hand washing is achieved by

using either a plain or antimicrobial soap and water.

The purpose of surgical hand antisepsis is to eliminate transient flora and

reduce resident flora to prevent introduction of organisms in the operative

wound, if gloves become punctured or torn.

At the beginning of a routine treatment period, watches and jewelry must

be removed and hands must be washed with a suitable cleanser.

Hands must be lathered for at least 10 seconds, rubbing all surfaces and

rinsed.

Clean brushes can be used to scrub under and around the nails.

Must be repeated at least once to remove all soil.

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Hegde et al in their study stated that the bar soap under

the "in use" condition is a reservoir of microorganisms and washing hands with such a soap may lead to spread of infection. (Microbial contamination of "in use" bar soaps in dental clinics. Indian J Dent Res 2006;17:70-3)

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Methods of hand drying

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HOW TO WEARSURGICAL GLOVES

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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.

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N95 PARTICULATE RESPIRATOR

National Institute for Occupational Safety and Health (NIOSH) introduced a rating system which identifies the abilities of respirators to remove the most difficult particles to filter, referred to as the most penetrating particle size (MPPS), which is 0.3µm in size.

The “N” means “Not resistant to oil”. N95: captures at least 95% of particles at MPPS. N99: captures 99% of particles at MPPS. N100: captures 99.97% of particles at MPPS.

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When should I wear an N95 respirator?

N95 particulate respirator

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Eye wear

CAUSES OF EYE DAMAGE:

1. Aerosols and spatter may transmit infection

2. Sharp debris projected from mouth while using air turbine

handpiece, ultrasonic scaler may cause eye injury.

3. Injuries to eyes of patients caused by sharp instruments

especially in supine position

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Over garmentsGown type Situation and Rationale

Cotton/linen, reusable or disposable, long-sleeved isolation gowns

Use if contamination of uniform or clothing is likely or anticipated

Fluid resistant isolation gown or plastic apron over isolation gown

Use if contamination of uniform or clothing from significant volumes of blood or body fluids is likely or anticipated (fluids may wick through non-fluid resistant reusable or disposable isolation gowns)

Fluid impervious gowns e.g., Gortex®

Use if extended contact or large volume exposure (e.g., large volume blood loss during resuscitation of MVA victim or surgical assist)

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Footwear

Most hospitals have their own policies regarding footwear.

Footwear with open heels and/or holes across the top can

increase the risk of harm to the person wearing them due to

more direct exposure to blood/body fluids or of sharps being

dropped for examples.

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OCCUPATIONALLY ACQUIRED INFECTIONS

HIV : 0.3%

Hepatitis C : 1.8%

Hepatitis B (HBeAg +ve) : 30%

Occupational exposures that may result in HIV, HBV, or HCV transmission include needlestick and other sharps injuries; direct inoculation of virus into cutaneous scratches, skin lesions, abrasions, or burns; and inoculation of virus onto mucosal surfaces of the eyes, nose, or mouth through accidental splashes

All health care professionals should be immunized against Hepatitis A, Hepatitis B, Varicella, MMR, DPT, Rubeola, Meningitis, Polio, Influenza, Tetanus, Diptheria, Rubella. 91

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Post exposure prophylaxis-HIV

Wound care: Clean wounds with soap and water Flush mucous membrane with water. No evidence of benefit for: – application of antiseptics or

disinfectants

– squeezing puncture sites

Chemoprophylaxis Initiating occupational 4 week regimen of PEP

(zidovudine+ lamivudine+nevirapine)as soon as possible, ideally within 2 hours of exposure.

HIV- antibody testing should be performed for atleast 6 months post exposure

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HIV Infection Control(OSHA regulations)

• Measures at the time of Surgery :• Proper hand washing.• Surgical attire for operation theater.• Cover the operation table with waterproof &

disposable sheet.• Patient to be posted at the end of the operation list.• Staff with laceration or abrasion on their hands are

excluded from the theatre.

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• Number of staff member to be kept minimum.• Separate members outside the operation theater for fetching the

drugs, equipments etc.• Disposable foot covers, caps, mask, plastic gowns and

protective eye wear.• Wearing of double gloves.• Face mask or cap, if contaminated with splatter of blood, should

be replaced immediately.• Scissors & diathermy should be used instead of blade or

scalpels.

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• Sharp instruments not to be handed directly, but to be delivered via kidney tray.

• Patient allowed to recover in operation theater instead of recovery room and directly transferred to ward.

• In case of spillage of blood or body fluid, it should be moped up using gloves and old linen/paper towel or news paper.

• Sent for incineration in plastic bag.• Area to be covered with 1% sodium Hypochlorite.• Floor is wiped with soap and water followed by 1% sodium

hypochlorite.

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• Gloves removed at last after removing mask, cap and gowns.

• All sharp instruments kept in puncture proof plastic container.

• Proper labeling done & sent for incineration.• Needles to be capped before shredding.• Non sharp waste kept in large plastic bag, labeled and sent

for incineration.• Reusable instruments autoclaved.• Then washed with soap and water.• Re-autoclaved.

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• Non-autoclavable instruments immersed in 2% glutaraldehyde solution for 1 hour.

• Then cleaned with warm water and detergents.• Again soaked in glutaraldehyde for 3 hours.• Suction bottle should contain 30 ml of 2%

glutaraldehyde or 60 ml of 1% sodium hypochlorite.• It is carefully emptied out, rinsed and autoclaved after

surgery.• Ventilator tubes rinsed in running tap water and

immersed in 2% glutaraldehyde for 2 hours.

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• Laboratory specimen placed in 10 % formalin jar, with tight leak proof cork.

• It is kept in a bag and tightly closed and sealed, before transportation to laboratory.

• Operating table, floor and walls to be thoroughly cleaned with 1% sodium hypochlorite.

• Equipments or surfaces that cannot be easily disinfected are covered with aluminium foil or disposable plastic covers during surgery.

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• Measures for Health Care workers (OSHA regulations)

A proper staff education and training.

Vaccination of all employees.• Universal precautions to be observed.• Proper hand washing.• Careful handling of sharp objects & instruments.• Proper sterilization, disinfection or disposal of instruments

after use.• Use of gloves, mask, gowns etc.

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PRINCIPLES AND PROCEDURES FOR HANDLING AND CLEANING INSTRUMENTS AFTER TREATMENT The safest and most efficient instrument cleaning procedures

involve ultrasonic cleaning of used instruments kept in a perforated basket or cassette throughout the cleaning procedure.

Used instruments are commonly placed in an anti microbial solution as this softens and loosens debris.

Next, move the instruments or basket of instruments into an ultrasonic cleaning device, rinse them, and then carefully inspect the instruments for debris.

instruments likely to rust , dip into a rust inhibitor solution. Drain & dry instruments with absorbent towel.

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INSTRUMENT PROCESSING

ADA guidelines for sterilization

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Effect of sterilization on instruments

Sterilization Type of instrument

Stainless steel Carbon steel

Saturated steam at 250°F Amorphous substance formed near cutting edge; no dulling.

Dulling and oxidation of cutting surfaces

Formalin-alcohol vapor at 270°F

Cracking of wire edge; no dulling.

Some oxidation of surfaces; no dulling.


No visual change.


No visual change

Effects of Sterilization on Periodontal Instruments Roger B. Parkes,* and Robert A. Kolstadf Accepted for publication 31 August 1981

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• Divided into two categories :

A) Bio-hazardous materials.

B) Non-bio-hazardous materials.

A) Bio-hazardous materials consist of waste materials :– 1. Soaked with blood or other body secretions.

– 2. Capable of causing infectious disease.

– 3. Having a poisonous effect.

– 4. Human tissue removed during surgery.

– 5. Teeth and associated tissues.

– 6. Gloves.

Waste management

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• B) Non-bio-hazardous materials consist of waste materials :

– 1. Matrix bands.

– 2. Masks, caps, gloves, patient’s napkin’s.

– 3. Impression materials.

– 4. X- ray packets & surface covers.

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Waste Management Categories of bio-medical waste in india

Options Waste category

Category 1 Human anatomical waste(tissues ,organs,body parts)

Category 2 Animal wasteCategory 3 Microbiology and

biotechnology waste

Category 4 Waste sharps (needles,syringe,scalpels…)

Category 5 Discarded medicine and cytotoxic drugs

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Waste ManagementCategory 6 Solid waste(items

contaminated with blood and fluid including cotton dressing….)

Category 7 Solid waste (waste generated from disposable items )

Category 8 Liquid waste(waste generated from laboratory and washing cleaning …)

Category 9 Incineration ashCategory 10

Chemicals used in production of biological, chemical used in disinfection

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COLOUR CODESCOLOUR TYPE OF

CONTAINERWASTE CATEGORY

TREATMENT OPTIONS

YELLOW PLASTIC BAGS Human and animal

wastes, Microbial and

Biological wastes and soiled

Wastes, eg. human tissues, body parts, organs, lab cultures, specimens, items contaminated with blood

Incineration, deep burial

RED DISINFECTED CONTAINER/PLASTIC BAGS

Microbiological and

Biological wastes, Soiled wastes,

Solid waste, eg. Disposable items like catheters, IV set, lab cultures , specimens etc.

Autoclave, microwave, chemical burial

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COLOUR CODE

TYPE OF CONTAINER

WASTE CATEGORY

TREATMENT OPTIONS

BLUE/WHITE TRANSPARENT

PLASTIC BAG,PUNCTURE PROOF CONTAINER

Waste sharps and solid waste, eg. .Sharps, needles , scalpels, disposable items like catheter, IV set etc

Autoclave/ Microwave/

Chemical Treatment Destruction

BLACK PLASTIC BAG Discarded medicines, incinerated ashes, chemicals used for disinfection etc.

DISPOSAL IN SECURED LAND FILLS

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CONCLUSION A steady increase in the serious transmissible diseases over the

last few decades have created a global concern and impacted the

treatment mode of all health care practitioners.

Emphasis has now expanded to assuring and demonstrating to

patients that they are well protected from risks of infectious

disease.

The dental health care provider has to follow high standards of

infection control for the safety of the patients and the dental

health care workers

References Texbook of microbiology by Prof. CP Baveja.(3rd edition) Operative dentistry chp- infection control by Studervant.

(4th edition) Essentials of preventive and community dentistry Soben

peter (3rd edition) Textbook of clinical periodontology, Newman, Takei,

Carranza, 11th edition. WHO glossary Article on Sterilization of Suture material by Ingrid Cox

dated 2004 17(50) from Community Eye Health Journal. Article on effects of sterilisation on periodontal instruments

by Roger B. Parkes and Robert A. Kolstadf Accepted for publication 31 August 1981 Journ Periodont

Article on recent advances in sterilization by William A.Rutala and David Weber( Emerging Inectious Diseases dated april 2001 vol.7)

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Sterilization and disinfection of dental instruments by ADA Disinfection & sterilization of dental instruments TB MED

266, 1995 CDC, guidelines for disinfection & sterilization in health

care facilities 2008. Infection prevention and control, college of respiratory

therapists Ontario, june 2011 New CDC guidelines for selected infection control

procedures, chris miller. CDC guidelines for infection control in dental health care

settings, Dec19, 2003/vol.52. Sterilization of ultrasonic inserts

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Sterilization and disinfection in dentistry

Healthcare

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