Presented by

Dr. Neetu Singh

Sterilization and infection control

:

IntroductionImportant definitionClassificationClassification of methods of sterilizationAsepsis in dentistry : Barrier techniquesInfection control in dental clinicFrom prosthetic point of viewInfection controlConclusion References

Contents

The concept of asepsis and its role in the prevention of infection was put forward nearly Two centuries ago..

Lister, working on antisepsis, initially used phenol (dilute carbolic acid) for contaminated wounds, later applied it in all surgical wounds, also in operating room by nebulization of the solution.

Further developments occurred with the introduction of steam sterilization surgical masks, sterile gloves, sterile gowns and drapes etc.

INTRODUCTION

General principles of asepsis are laid down by Hungarian physician, Ignaz semmelweiss in Europe in early 1850’s and Oliver Holmes in USA.

These principles were accepted after Joseph Lister (Father of antiseptic surgery) studied prevention of wound infection(1865-1891).

C. P. Baveja.,Text book of microbiology. 2nd edition. Arya publication

In present days certain guidelines and regulations are recommended by accepted bodies, which have to be followed in dental practice and up graded in every general body meeting.

Guidelines are given by • American Dental Association (ADA), • Centers for Disease Control (CDC)• British Dental Association Advisory service to name few and regulations by Environmental

Protection Agency (EPA), Occupational Safety and Health Administration (OSHA) and

Health and Safety at Work act 1974 

Infection control recommendation for the dental office and dental laboratory- JADA 78;3:1998

DEFINITIONS

CLEANING - It is a process which removes visible contamination but does not necessarily destroy micro organisms. It is necessary prerequisite for effective disinfection or sterilization.

ASEPSIS -Term used to describe methods which prevent contamination of wounds and other sites, by ensuring that only sterile object and fluids come into contact with them.

Text book of microbiology by Ananth Narayan

ANTISEPSIS - It is the procedure or application of an antiseptic solution or an agent which inhibits the growth of microorganisms, while remaining in the contact with them.

DISINFECTION - it is a process which reduces the number of viable microorganisms to an acceptable level but may not inactive some viruses and bacterial spores.

STERLIZATION - it is the process of destruction or removal of all microorganisms from article, surface or medium, including spores.

Text book of microbiology by Ananth Narayan

critical, semi critical, or non critical depending on their risk of transmitting infection and the need to sterilize them between uses.

Dental instruments are classified into three categories –

Each dental practice should classify all instruments as follows: As per May 28, 1993

Critical Semicritical Noncritical

Spaulding Classification

INSTRUMENT CLASSIFICATION

Critical instruments Semi-critical instruments Non-critical instruments

(I) Critical instruments:• Are instruments that penetrate soft tissues or bone• Critical instruments must be heat sterilized between each use or

disposable items (eg. Scalpel) are used.

Eg. Periodontal probes

Explorers

Scaling or root planning instruments tip insert of an ultrasonic scaling unit.

Periodontal probe

(II) SEMI-CRITICAL INSTRUMENTS:• Are not intended to penetrate soft tissues or bone but come into contact

with oral fluids.

Eg. Ultrasonic scaling handpiece

Mouth mirror

Impression trays

Oral photography retractor

Two methods

Heat Sterilization Chemical disinfectants

(Eg. germicides)

(iii) Non-critical instruments:Are those items that come into contact only with intact skin

Eg. Light handle

• High and low volume evacuators

• Tubing for handpieces

• Instrument trays

• Chair surfaces

To achieve sterilization of any instrument three definite stages are to be completed-

Pre sterilization cleaning Sterilization process Aseptic storage

PRE STERILIZATION CLEANING

Objective-Removal of the organic matters, blood and saliva which provide protective barrier for microorganisms and prevents its destruction.

There are three methods for cleaning-Manual-Ultrasonic-Mechanical washing

MANUAL CLEANING

Simplest and the cheapest method, but time consuming and difficult to achieve.

Heavy duty gloves and glasses must be worn to protect needle stick injury and to protect eye.

Material used for manual cleaning-Soaps-Detergents

ULTRASONIC CLEANING

Principle- conversion of electrical energy into vibratory sound waves which pass through a soap solution containing the instrument.

Used mainly for burs, bone files, bone cutter, artery forceps, saw etc.

CYCLE:- usually 6 mins, if cassest then 12 min

DECONTAMINATING INSTRUMENTS WITH AN ULTRASONIC CLEANSER

PRIOR TO STERILIZATIONEquipments: Nitrile gloves Face mask and protective eye wear Cleaning solution Contaminated instruments Instruments cassette

Ultrasonic cleaning unit

Decant holding solution into sink

Drain excess water

Immerse instrument cassette into ultrasonic cleaner solution

Set ultrasonic cleaning unit time

Lift basket to drain excess solution

Rinse instrument cassette

MECHANICAL WASHING

Principle- High-pressure jets of water with or without a detergent which removes debris from instrument. Small instrument like burs, blade are not suitable for this type of cleaning.

Classification of the method of sterilization/Disinfection

A. PHYSICAL

1- Sun Light

2- Drying

3- Heat i- Dry

                    ii-Moist

4- Filtration

5- Gas

6- Irradiation

B. CHEMICAL

1. Phenol Derivatives : Phenol, Cresol, resorcinol, chloroxylenol

2. Oxidizing agents :Pot.Permanganate, Hydrogen Peroxide,Benzoyol Peroxide

3. Halogens : Iodine, chlorine

4. Biguanide : Chlorhexidine

5. Quarternary Ammonium (Cationic) : Cetrimide, Zephiran

6. Alcohols : Ethanol, Isopropanol.

7. Aldehydes : Formaldehyde, Glutaraldehyde

8. Acids : Boric acid, acetic acid

9. Metallic salts ; Silver Nitrate, Zince Sulfate, Zinc Oxide, calamine,

10. Dyes : Gentian violet, proflamine, Acriflamine

11. Furan derivatives : Nitro flurazone  

HEATMost common and one of the most effective methods of sterilization.

Factors influencing sterilization by heat are : -

i. Nature of heat

a.        Dry

b.       Moist

ii.Temperature & time

iii. No. of organism present

iv.Whether organism has sporing capacity

v. Type of material from which organism is to be eradicated

A. DRY HEAT

Killing is due to :

- Dehydration and oxidation of organisms

- Protein denaturation

- Toxic effects of elevated levels of electrolytes

1. Red Heat : It is used to sterilize metallic objects by holding them in flame till they are red hot. Example : inoculating wires, needles, forceps etc.

2. Flaming : The article is passed over flame without allowing it to become red hot. Example : Glass plates, mouth of culture tubes and glass slides.

3. Hot air oven :It is used to sterilize items, which do not get damaged by high temp.

such as laboratory

glass,

flasks,

instruments with sharp cutting edges, B.P. handles,

Powders,

Dapen dishes,

mouth mirrors.

Precautions

The heat should be uniformly distributed in side the oven.

All the instruments must be clean of dry prior to wrapping.

It should not be over loaded.

Oven must be allowed to cool for about 2 hours before opening otherwise glass will crack. 

Temp. & Time: The sterilization is complete if these two factors are achieved throughout the load.

Temperature Time(Min)

140oC 180

150oC 150

160oC 60

170oC 45

180oC 18

190oC 7.5

Sterilization Control of Hot Air Oven • The spores of non-toxigenic strain of Bacillus subtilis and

Clostridium tetani are used as a microbiological test of dry heat.

• Browne’s test strip available that contain a chemical indicator.

MOIST HEAT STERILISATION This method of sterilisation may be used at different temperature as follows

At temp below 100 c

At a temp of 100 c

At a temp above 100 c

B. Moist heat Causes denaturation and coagulation of proteins.

1. Pasteurization : below 100 cThe temperature employed is either 630C for 30mins (Holder method) or 720C for 15-20 seconds (Flash method) followed by cooling quickly to 130C.

Method is used for heat sensitive liquid and pharmaceutical products.

2. Tyndallisation : at 100cNamed after John Tyndall.

Exposure of 1000C for 20 min for 3 successive day.

Principle: 1st exposure kills all vegetative bacteria & spores, since they are in a favorable medium, will germinate and be killed on subsequent occasions.

Auto Clave: above 100cMost common method in dental office1210C for 20 minutesTo sterilize heat stable instruments

To Avoid corrosion Crawford and Oldenburg recommended addition of ammonia to the autoclave

AUTOCLAVE :

Steam is the effective means of sterilization, because of its

1. High penetrating capacity.

2. It gives of large amount of heat to surface with which it comes in contact.

Autoclaves, or steam sterilizers essentially consist of following: i) A cylindrical or rectangular chamber, with capacities ranging from 400 to 800 liters. ii) Water heating system or steam generating system iii) Steam outlet and inlet valves iv) Single or double doors with locking mechanism. v) Thermometer or temperature gauge vi) Pressure gauges

WRAPPING INSTRUMENTS FOR AUTOCLAVING

Instruments must be clean, but not necessarily dry. Closed (non-perforated) containers (closed metal trays, capped glass vials) and aluminium foils cannot be used, because they prevent the steam from reaching the inner sections of the packs.

Cassettes, drums, trays with opening on all sides may be used.

Packaging used for autoclaving must be porous, to permit steam to penetrate through ; and reach the instruments.

The materials used for packaging could be fabric or sealed biofilm/paper pouches, nylon tubing, sterilization wrap, and paper wrapped cassettes.

The bag or wrap is sealed with tape.

Notes:1. Use distilled water or deionized water instead of water from community supply

(because hard water leaves deposits on instruments).

2. Avoid use of sealed or closed containers or aluminium foil for packaging materials because there is no direct contact of steam.

Close-up of autoclave showing gauages.

Packages loaded into autoclave.

Nitrile- gloved and washing interior of

autoclave for maintenance care.

USES

To sterilise culture media, rubber material, gowns, dressing, gloves etc.It is particularly useful for materials which cannot withstand the higher temperature of hot air oven.For all glass syringes, hot air is a bettter sterilising method.

Unsaturated chemical vapor sterilizer:Similar to autoclave but in

place of stream, a chemical

vapor is generated under pressure.

Chemiclave

4. GLASS BEADS STERILIZER : •The media used are glass beads, molten metal and salt. •The temperature achieved is of 220oC. •The method employs submersion of small instruments such as Endodontic files,artery forceps,scissors and burs, into the beads; and are sterilized in 10 seconds provided they are clean. •A warm-up time of at least 20 minutes to ensure uniform temperatures in these sterilizers.

FILTRATION

Help to remove bacteria from heat labile liquids.

As viruses pass through ordinary filters, it can be used to obtain bacteria free filtrates of virus isolation.

TYPES: Candle filterAsbestos filterSintered glass filterMembrane filter

USES OF FILTRATION1. To sterile sera, sugars and antibiotics

solutions2. Separation of toxins and bacteriophages from

bacteria.3. Purification of water4. Filter discs retain the organism which can be

cultured e.g testing of water samples for cholera vibrios or typhoid bacilli

IRRADIATION Radiation used for sterilization is of two types

1. Ionizing radiation, e.g., X-rays, gamma rays, and high speed electrons .

2. Non-ionizing radiation, e.g. ultraviolet light, and infrared light.

These forms of radiation can be used to kill or inactivate microorganisms.

1. Ionizing Radiation

X-rays, gamma rays and cosmic rays are highly lethal to DNA and other vital constituents.

They have high penetration power.

There is no appreciable increase in temperature, thus referred to as cold sterilization.

Commercial plants use gamma radiation for sterilizing plastics, syringes, swabs, catheters etc.

.M. R. Cleland, X-Ray Processing: A Review of the Status and Prospects, Radiation Physics and Chemistry, Vol. 42, Nos. 1-3, pp. 499-503, 1993.

2. Non-ionizing radiation

Two types of non-ionizing radiations are used for sterilization:-

A. Ultraviolet -Short range UV is considered “germicidal UV”.At a wavelength of 240 nm to 280 nm UV will destroy micro-organismal DNA.Used mainly for air purification and water purification in hospitals.

B. Infrared –It is most commonly used to purify air, such as in the operating room. Infrared is effective, however, it has no penetrating ability.

ETHYLENE OXIDE STERILIZATION (ETO)

Used almost exclusively to sterilize medical products that cannot be steam sterilized or sensitive to radiation.

Mechanism of action: It destroys micro-organisms by alkylation and cause denaturation of nucleic acids of micro-organisms.

At 30 °C - 60°C with relative humidity above 30 % and gas conc. between 200 and 800 mg/l for at least 3 hours.

Ethylene oxide is a colorless liquid with a boiling point of 10.7 °C.

Highly penetrating gas with sweet ethereal smell.

Highly inflammable & in conc. greater than 3%, highly explosive.

By mixing with inert gases such as CO2, explosive tendency is eliminated.

Plastics, rubber & photographic equipments can be sterilized by this method.

Also used for mass sterilization of disposable items, plastic syringes, needles, catheters,blades etc.

Disadvantages– Lengthy cycle time– Cost– Potential hazards to patients & staff

Advantage: Can sterilize heat or moisture sensitive medical equipments.

CHEMICAL METHODS

No available chemical solution will sterilize instruments immersed in it.

Secondly, there is a risk of producing tissue damage if residual solution is carried over into the wound while it is being used.  

Mechanism of action of chemical disinfectants :

The mechanism of action of most of the chemicals are nonspecific and complex but most of them effect microorganisms by one of the following mechanisms.

1. Cell membrane injury.

2. Coagulation and Denaturation.

3. Interactions with functional groups of proteins.

1. ALDEHYDE COMPOUNDS

a. Formaldehyde:

Commonly called formalin

A broad-spectrum antimicrobial agent, used for disinfection, has limited sporicidal activity.

Hazardous substance, inflammable and irritant to the eye, skin and respiratory tract.

USES:

Preservation of tissue for historical examination.

To sterilise bacterial vaccine.

To prepare toxoid from toxin.

 

Formaldehyde in dentistry: a review of mutagenic and carcinogenic potential.Lewis BB, Chr.esten SB J AM Dent Assc. 1981 Sep;103(3):429-34.

STUDY ON FORMOCRESOLFor many years there has been controversy over the value

of antimicrobial drugs for intracanal dressings in endodontic.

Formaldehyde has a known toxic mutagenic and carcinogenic potential.

Many investigations have been conducted to measure the risk of exposure to formaldehyde; it is clear that formaldehyde poses a carcinogenic risk in humans. There is a need to reevaluate the rationale underlying the use of formaldehyde in dentistry particularly in light of its deleterious effects.

Formaldehyde in dentistry: a review of mutagenic and carcinogenic potential.Lewis BB, Chr.esten SB J AM Dent Assc. 1981 Sep;103(3):429-34.

Glutaraldehyde:

It is a high level disinfectant• A solution of 2% glutaraldehyde (Cidex),

requires immersion of 20 minutes for disinfection

• 6 to 10 hours of immersion for sterilization.USES: • For sterilisation of endoscopes and

bronchoscope• Face mask• Corrugated rubber anaesthetic tubes and

metal instruments • Hardener in x-ray film processing. •

Stonehill et al (1963) reported that glutaraldehyde kills vegetative bacteria, spores, fungi and virus by alkylation on a 10-hour contact.

It is activated by addition of sodium bicarbonate, but in its activated form in remains potent only for 14 days

It is toxic, irritant and allergenic. It is a high level disinfectant. It is applicable where heat cannot be used.

 

2. ALCOHOLS

Act by denaturing bacterial proteins.

Solutions of 70% ethanol are more effective than higher concentrations, as the presence of water speeds up the process of protein denaturation as reported by Lawrence and Block (1968).

Frequently used for skin antisepsis prior to needle puncture.

Isopropyl alcohol is preferred as it is a better fat solvent, more bactericidal and less volatile.

Used for disinfection of clinical thermometer .

3. IODOPHOR COMPOUNDS

Many studies have shown, that, iodophor

compounds are the most effective antiseptics.

Iodine is complexed with organic surface-active agents, such as, polyvinylpyrrolidone (Betadine, Isodine).

Their activity is dependent on the release of iodine from the complex.

These compounds are effective against most bacteria, spores, viruses, and fungi. These are the most commonly used surface disinfectants along with hypochlorite.

4. Biguanide :Most commonly used biguanide

compound is chlorhexidine.

It is a powerful non-irritating antiseptic that disrupts bacterial cell membrane.

It persists on skin for longer period of time and that is why it is extensively used for

surgical scrubbing,

neonatal bath,

mouth wash and a general skin anti-septic.

5.HYDROGEN PEROXIDEStrong oxidant.

Oxidizing properties allow it to destroy wide range of pathogens.

Biggest advantage is short cycle time.

Used in 35% to 90% concentration.

• Uses:-Disinfect Small Wounds. • Whitening Tooth• Antiseptic Mouth Rinse. ...• Disinfect Toothbrushes. ...

SterIlization of prosthetics

Immersion disinfectant- Glutaraldehyde iodophore

Surface disinfectant- Bleach (sodium hypochlorite) Phenolic disinfectant Quaternary Ammonia compounds /disinfectants

Iodophor disinfectant

• DISINFECTANTS USED

Infection control in the prosthodontic laboratoryVidya S. Bhat , Mallik a S. Shet t y, Kam alak ant h K. Shenoy

58

ALL DISINFECTION PROCEDURES SHOULD BE DONE IN DENTAL OPERATORY PRIOR TO DELIVERING PROSTHESIS TO LAB

INCOMING ITEMS

Annotate the DD Form 2322: “Disinfected with ______ for _____minutes”

HANDLING OF WORK RECIEVED IN LABORATORY

Label the plastic bag with dispatch date & mention : “This case shipment has

been disinfected with

______for_____ minutes”

OUTGOING ITEMS

Follow dental materials’ manufacturers instructions regarding disinfectants

Do an in-office “test run” before using new combinations of impression materials and disinfectants

IMPRESSIONS

DISINFECTING IMPRESSIONSTECHNIQUES OF DISINFECTION :- Immerse/ dip

Spray (Rinse impression Place impression in bag spray with disinfectants Seal bag to create charged atmosphere)

Spray tech. is probably not as effective as immersion

D I S I N F E C TA N T S F O R VA R I O U SI M P R E SS I O N

M AT E R I A L S

POLYSULPHIDES Use immersion in disinfectants of proven effectiveness*

SILICONES Use immersion in disinfectants of proven effectiveness*

POLY ETHERS Use immersion in disinfectants of proven effectiveness*

ALGINATE Use immersion in disinfectants of proven effectiveness* or spray with adequate coverage with disinfectants

AGAR Use immersion in hypochlorite, iodophore or glutaraldehyde with phenolic buffer

STONE CAST Use immersion in hypochlorite, iodophors, alternately use spray disinfectants

ZINC OXIDE EUGENOL Use immersion in glutaraldehyde or iodophor.

TABLE 1 DISINFECTION OF IMPRESSIONS AND STONE CASTS

*Disinfectants: Chorine compounds, hypochlorite, glutaraldehyde/phenolic combinations, 2% acidic glutaraldehydes, 2% alkaline glutaraldehydes, 2% neutral glutaraldehydes, idophors, and phenolic alcohol cominations.

ALGINATE

Alginate is a complete carbohydrate that imbibes water.

Immersion disinfection for long periods will cause a distortion of alginate impressions due to the intake of water and the action of the disinfectant.

Avoid prolonged immersion.

THE EFFECT OF STEAM STERILIZATION ON THE PROPERTIES OF SET DENTAL GYPSUM MODELS.

study was to investigate the viability of autoclave sterilization of set dental gypsum models.

The effects of autoclaving on the strength, surface hardness and dimensions of specimens of plaster, stone and diestone were investigated.

In addition, sodium succinate was used to minimize any changes produced by autoclaving.

It has been shown that dental gypsum casts can be successfully steam sterilized. The results showed that for fully-dried gypsum products, autoclaving at 132 degrees C for 5 minutes rendered the casts unacceptable for use.

Autoclaving at 121 degrees C for 16 minutes had less effect although casts were still not satisfactory, with the main problems being excessive expansion for plaster and significant strength and surface hardness loss for stone and diestone.

Matyas J, Dao N, Caputo AA, Lucatorto FM. Effects of disinfectants on dimensional accuracy of impression materials. J Prosthet Dent 1990;64:25-31.

IMPRESSION TRAYSALUMINUM -

♪ Heat sterilize via autoclave ♪ Chemical vapor or dry heat ♪ Ethylene oxide sterilization

CHROME-PLATED -

♪ Same As above

CUSTOM ACRYL IC RES IN -

♪ Discard after use ♪ Disinfect if it reused in same patient

PLAST IC –

D I S C A R D A F T E R U S E

DENTAL CAST DISINFECTION

Prefer disinfection of impressionTo Disinfect castSpray with iodophor or chlorine product then rinseAnother option Soak casts for 30 minutes in 0.5% conc. of sodium hypochlorite and saturated calcium dihydrate solution(SDS)

METAL DENTURES

Recent research indicates that the use of sodium hypochlorite for 10 minutes will not damage denture base metals.

One study recommends 2% hypochlorite 1: 5 for 5 minutes, as 1% does not remove all micro-organisms.

Other studies conclude that sodium hypochlorite should not be used and that iodophors are the first choice disinfectants.

Iodophor or 1:10 diluted sodium hypochlorite be used for single or infrequent disinfection

However, both disinfectants should be used are as either can be corrosive with repeated or prolonged exposure.

 

 Effect of denture cleansers on metal ion release and surface roughness of denture base materials. Braz. Dent. J. vol.23 no.4 Ribeirão Preto  2012

 

ACRYLIC DENTURES

Sodium hypochlorite is recommended for disinfection of complete acrylic dentures.

BleachVinegar Baking soda mouthwash

A study by de sousa porta 2013 evaluated the use of soak in bleach

for 3 min i.e sodium hypochroride 5.25 % in 1:10 for 90 days. He

found redution in number of microorganisms, including candida.

There was no significance color change and surface roughness was

observed

DIRECTIONS FOR USEBefore using Nitradine® Seniors, brush,

cleanse and rinse the denture as usual.Immerse the denture in a glass of lukewarm

water (approx.150ml), or in a Sonic Denture Cleaner filled with lukewarm water.

Add one tablet to the water.Make sure the denture is fully covered with

water. For regular bacteria and yeast infection,

allow the denture to soak for 15 minutes in the solution.

To ensure that your denture is free of all viruses, soak your denture for 1 hour in the solution.

Remove the denture from the solution and rinse well under water before replacing the denture in the mouth.

If a taste should remain on your denture after replacing it in your mouth, place the denture in lukewarm water for 10 minutes.

DISINFECTION OF ORALLY SOILED PROSTHESES PROCEDURE

Scrub prosthesis (with brush & soap)

Place in sealable plastic bag containing ultrasonic cleaning solution

Cover ultrasonic cleaner (4-5mins)

Remove and rinse

Use spray disinfection (idophor)

Heavy-body bite registration materials can be disinfected in same manner as an impression of the same material

WAX BITES/RIMS, BITE REGISTRATIONS

DISINFECTION

Alcohol torch, facebow, articulator, mixing spatula, mixing bowl, lab knife, shade/mold guide should be disinfected (by spray or

immersion technique based on type of item) after each use

LATHE

Pumice has been shown to pose a potential contamination risk (Via aerosol or direct contact)

Use protective eyewear Ensure plexiglass shield is in position Activate vacuum

Procedure of disinfection

Mix pumice with Clean water, diluted 1:10 bleach, or other appropriate disinfectant Add tincture of green soap if desired

TO PREVENT DISINFECTION FROM LATHEChange pumice daily

Machine should be cleaned and disinfected daily

Clean and disinfect pumice brushes and rag wheels everyday.

Daily heat sterilization is preferable.

SANITIZATION

CLEANING BY WIPING WITH A DISINFECTANT/DETERGENT

SONICATION OF INSTRUMENTS WITH A CLEANER

DISINFECTION

RINSE MAKE IMPRESSION

SPRAY & WAIT RINSE

Aseptic storageThe maintenance of sterility during transportation and storage is of utmost importance.

• Instruments are kept wrapped until ready for use .• To reduce the risk of contamination, sterile packs must be handled as

little as possible.• Sterilized packs should be allowed to cool before storage; otherwise

condensation will occur inside the packs.• Sterile packs must be stored and issued in correct date order. • The packs, preferably, are stored in drums which can be locked. • Preset trays and cassettes, are useful as, the instruments can be

organized as per the procedure

    

Aspesis in Dental Clinic

DEFINITION:Infection control refers to a comprehensive and

systematic program that, when applied, prevents the transmission of infection agents among persons who are in direct or indirect contact with health care environment.

GOALS OF INFECTION CONTROL:To create and maintain a safe clinical environment to

eliminate the potential for disease transmission from

Clinician to client/patient

Patient to clinician

Patient to patient

Patient to Technician &

Technician to Patient.

OBJECTIVES• Assess risk of disease transmission in oral health care and

plan appropriate control measures.

• Interpret emerging guidelines for infection control

• Identify infectious disease that pose a risk of transmission in oral health care.

• Apply active and passive mechanisms of infections disease transmission prevention.

• Prepare the dental environment prior to and after patient’s care.

CDC and OSHAThese two agencies of U.S. government play key role in

infection control.

CDC: Centres for disease control and prevention Public health agencies It’s mission is to promote health and quality of life by preventing and controlling disease, injury and disability.

OSHA: Occupational safety and health administration. Protect persons by ensuring a safe and health workplace.

Most government regulatory entities private agencies and health care professional organizations list six infection control procedures as mandatory for control of infectious diseases in dental practice regardless of disciplines. They are

Dental treatment personnel (DTP)

1. All DTP should wear latex examination gloves during patient treatment

2. All DTP should wear protective eye were during patient treatment

3. All DTP should wear masks covering the nose and mouth

4. All items used in the oral cavity should be sterilized in a heat or heat pressure sterilizer whenever possible.

5. All touch and splash surface should be disinfected with an accepted disinfectant whenever sterilization is not possible.

6. Contaminated materials to be disposed off carefully by placing it in a sealed appropriately marked container..

Operation theatre procedure :

Antiseptic environment :

The principle is to minimize bacterial contamination especially, in the vicinity of operating table the concept of zones is useful and must be employed.Outer and general access zone- patient reception area and general office.Clean or limited access zone- the area between reception & general office and corridors & staff room.Restricted access zone- for those properly clothed personnel engaged in operating theatre activities, anesthetic room.Aseptic or operating zone- the operation theatre.

FUMIGATION OF OPERATION THEATRE

- Fumigation of the operation theatre is achieved by fumigator and potassium permanganate reaction technique.

- The chemical used is 40% formaline.

HAND WASHING

Three types of hand washing-

Social hand washingClinical hand washingSurgical hand washing

SOCIAL HAND WASHING

Recommended following social-type contact with clients, after going to the toilet and after covering a cough or sneeze.

A plain liquid soap is often used.

CLINICAL HAND WASHING

A clinical hand wash is used before clinical procedures on clients, when a client is being managed in isolation, or in outbreak situations.

An anti-microbial soap, containing an antiseptic agent, is used.

SURGICAL HAND WASHING

A surgical hand wash is required before any invasive or surgical procedure requiring the use of sterile gloves.

An antimicrobial skin cleanser, usually containing chlorhexidine or detergent-based povidone-iodine, is used.

Surgical Scrubbing :The purpose is to reduce resident and transient skin flora (bacteria) to a minimum.

Proper hand scrubbing and the wearing of sterile gloves and a sterile gown provide the patient with the best possible barrier against pathogenic bacteria in the environment and against bacteria from the surgical team.

The following steps comprise the generally accepted method for the surgical hand scrub-

DISINFECTION OF CHAIR SIDE EQUIPMENTS

High speed evacuation

Plastic tip :- Discarded

Metal tip :- Autoclaved• Dental handpieces and other

devices attached to air and water linesUse autoclavable

handpiecesUse Suck-back featured handpieces

Infection control recommendations for the dental offi ce and the dental laboratory. ADA Council on Scientifi c Affairs and ADA Council on Dental Practice. J Am Dent Assoc 1996;127:672-80.

ENGINEERING CONTROLS:Engineering controls are devices or equipment that reduce or eliminate a hazard.• Devices that provides protective guarding of sharp instruments such as needles or scalpels.• Devices that replace sharp items such as needles with systems that do not contain a sharp surface.• Devices that eliminate work exposure to sharp items

eg. Sharp containersNeedle covers with built in retractionNeedle destroyer

Needle destroyer

GOVT. DENTAL COLLEGE JAIPUR 97

PERSONAL PROTECTIVE EQUIPMENTS (PPE)

Disposable Gloves• Polyureth

ane gloves

• Latex gloves

• Nitrile utility gloves

Disposable

Masks

Protective

eyewear, chin

length face

shield

Protective

clothing (i.e., lab coat/jack

et)

EYE PROTECTION: Eye wear (Glasses) and face shields To protect eyes from spatter or spray of body fluids or calculus etc.

MASKS: To protect airway from airosol, spatter etc. Recommendations to change the mask after 20 minutes in aerosol or 60 minutes in non-aerosol environment.

PERSONAL PROTECTIVE EQUIPMENTS

PROTECTIVE CLOTHING:To protect intact and non intact skin from

spray or splash of body fluid during course of treatment.

This protection can be provided by high neck, long sleeve, knee-length garments.

Protective clothing for instrument cleaning and sterilization in the clinic may be of fluid proof variety.

OSHA ADVISE THE FOLLOWING CONCERNING GOWNS 1.The clinic attire should be worn only in the dental

environment and should be changed at the end of the treatment schedule.

2. The day should begin with freshly laundered garments and the garments should be changed immediately it soaked or spattered with blood or other contaminants.

3. Clinic attire should be handled separately from family laundry.

GLOVES: 4 categories

a). Medical exam gloves: vinyl gloves Non sterile gloves Available in variety of size, materials. Right/left hand specific.

b). Surgical gloves: Individually packaged in pairs Sterile untill the package is opened or bracked. Used for surgical procedures.

c). Over gloves:

Loosely fitting gloves Worn over surgical gloves in order to avoid the cross contamination of surgical gloves.Non sterile gloves

d). Nitrile gloves: Also known as heavy duty gloves Used during cleaning and disinfection procedure

Hand protection:Practices that reduce the risk of dermatitis include:

1. Thorough drying of hands after hand washing2. Use powder free gloves or low amount of powder.3. Use of lubricating hand lotions.4. Use of cool water when washing hands.5. Protecting hands from cuts and scratches.

Hand washing: Equipments : Liquid anti microbial soap

Sink with running waterPersonel protective equipment

Steps of hand washing:1. Remove jewelry from hands and forearms

(Otherwise harbors micro organisms and perforates gloves)

2. Keep hands and protective clothing away from sink surface (If hand touch sink during hand washing, repeat process) to prevent contamination.3. Control water flow

By pressing foot pedals with footBy pushing knee pedals with kneeBy turning of hand operated faucets by using elbow

TREATMENT AREA PREPARATION AND CLEAN UPHealth care environment must be managed to prevent cross contamination

Most items and surface areas in the dental care environment cannot be sterilized, therefore these must be cleaned and disinfected with disinfactant or covered with plastic barrier.

ITEMS:Dental chair

Operator chair

Dental unit

Dental light

X-ray unit

Air/water syringe handle

Pencils, pens, face mirrors, safety glasses

Saline ejector holder

Ultrasonic scaler

SURFACE BARRIERS

Barriers used to prevent contamination of nonsterilizable items.

Disinfectant Air Water syringe being flushed

Environment disinfection.

Spraying nitrile gloves with environmental surface disinfectant

INFECTION CONTROL AND THE DENTIST

The areas of risk in

infection

control

Hands Eyes Aerosols

J A I P U R

ROUTES OF DISEASE TRANSMISSION IN DENTISTRY

INHALATION

INDIRECT CONTACT CONTACT/SPLASH

PERCUTANEOUS

VEHICLES OF TRANSMISSION OF PATHOGENS

CROSS CONTAMINATION:Cross contamination is the transfer of oral fluids and debris from a

client to surfaces, equipments, materials, workers hand or another clients.

Because Saliva is invisible yet capable of cross contamination.

Direct Cross Contamination Indirect Cross Contamination

DIRECT CROSS CONTAMINATION:

When workers fails to change gloves between clientsWhen instruments are not cleaned or sterilized between useUse of disposable dental products such as saliva ejector on multiple patients.

WORK PRACTICE CONTROL:

Improper positioning of operator’s fingers placing the dental hygienist at risk of a puncture wound.

INDIRECT CROSS CONTAMINATION:1. When instruments, dental materials and their containers, equipment and

environmental surfaces are contaminated with a client’s oral fluid, either through touch or spatter and are not decontaminated before touched again.

2. When a chart or dental material is handled with contaminated gloves and then handled again with gloved hands when treating another client.

Indirect cross-contamination from a chart handled with a contaminated gloved hand.

COMMON INFECTIOUS DISEASES ENCOUNTERED IN DENTISTRY

Hepatitis A

Hepatitis B

Hepatitis C

Hepatitis E

Herpes

HIV

Tuberculosis

REQUIREMENTS FOR LAB PERSONNEL

Laboratory operators & employees should follow the Occupational Safety and Health Administration’s (OSHA) BBP Standard

Employees must provide Hepatitis B vaccine

They must use appropriate personal protective equipment

Must be given annual BBP training & reviewed annually and updated whenever necessary

All patients should be treated as if they could transmit a BLOOD BORNE PATHOGEN (BBP) disease

STRATEGIES TO PREVENT DISEASE TRANSMISSION

1. Vaccination eg. BCG, DPT, MMR, etc.2. Work Restriction:

• Work restrictions are recommended by the U.S. public health services for health care worker with certain infections and following exposure to some diseases.

• Hepatitis B3. Universal Precaution:

Universal precautions are the practices by which health care worker follow the same infection control for all patient irrespective of infection status or health history.

4. Standard Precaution:To - blood and other body fluids

- non intact skin5. Transmission based precautions: For patients who are infected with highly transmissible disease

immunization

All clinical staff should be vaccinated against the common illnesses.

Infection Timing and route Length of protection

1. Tetanus 2. Poliomyelitis 3. Hepatitis B4. Tuberculosis

IMOral IMK 0,1,6 monthsSubdermal

5 yrs5 yrs 3.5 yrs5 yrs

Inoculation injuriesInoculation injuries are the most likely route for transmission of blood borne viral infections in dentistry.

The definition of an inoculation injury includes all incidents where a contaminated object or substance breaches the integrity of the skin or mucous membranes or comes into contact with the eyes.

The following are typical examples –

sticking or stabbing with a used needle or other instrument splashes with a contaminated substance to the eye or other open lesion cuts with contaminated equipment bites or scratches inflicted by patients.

Treatment sequence for injuries : • Injury • Wash in running water and encourage wound to bleed • Cover the wound • Seek medical advice councelling • Take blood simple from wound recipient • Identify instrument or needle • Test for hepatitis B virus and HIV • Take blood sample from donor • Record details of injury in an accident book.

Regulation on Hazardous Waste Management

The Hazardous Waste (Management & Handling) Rules, 1989 and amendments made thereafter are now superseded by the new Hazardous Waste (Management, Handling & Transboundary Movement) Rules, 2008.

Hazardous Waste as defined in the Rules

Any waste which by reason of any of its physical, chemical,

reactive, toxic, flammable, explosive or corrosive characteristics

causes danger or is likely to cause danger to health or environment, whether alone or when in contact with other wastes or substances,

and shall include wastes listed in schedules I, II

& III of the rules

TYPE AND NATURE OF HWS

Recyclable – wastes having potential for recovery of useful /valuable material

Incinerable – wastes having high calorific value, mainly organic wastes like solvents, tars, off-spec. Organic products etc.

Land Disposable – wastes that can neither be recycled or incinerated

STORAGE OF HAZARDOUS WASTE

Till disposal for recycling/ treatment/ land filling, HWs are to be stored onsite in bags/ containers in a covered area.Storage permitted for a period not exceeding 90 days

SPCB may extend the storage period, in case of Small generator, Recyclers, reprocessors and facility operators upto 6 months of their annual capacityWastes which need to be specifically stored for development of a process for its recycling, reuse.

COLOR CODE FOR STORAGE

CONCLUSIONPrevention is better than cure. The main way of

control is by discarding all the contaminated instruments and materials and try to use as much as disposable items.

The dentist and assistant should take proper vaccination in proper time. The material, which is sent to the laboratory, should be disinfected before the technician contact. It should be kept in a separate room for disinfection, for all the patients’ work, which is sent.

For each patient the material used should be separate or it should be discarded after each patient work or disinfect it before use of it.

The dentist should not think only their health, they should consider the environment also when the dispose of the used materials.

They should be discarded in sturdy, impervious plastic bags to minimize human contact.

Blood and disinfectants be carefully poured into a drain connected to a sanitary sewer system.

Sharp instruments should be paced in puncture resistant containers marked with the bio hazard label.

referencesBOOKS:Harsh mohanCross infection control in dentistry-P.R.WoodARTICLES:• Chiaji Shen :A study on the effects of glutarldehyde base disinfectants on denture base

resins JPD 1989; 61-5;583

• J.A. Bell : A study on the effectiveness of two disinfectants on denture base acrylic resin with an organic load of staphylococcus aureus. JPD 1989; 61-5; 580.

• David G. Drennon : A study on the accuracy and efficiency of disinfection by spray automization on elastomeric impression. JPD 1989; 62-4; 468.

• Robert W. Schutt :A study on bactericidal effect of a disinfectant dental stone on irreversible hydrocolloid impression and stone casts. JPD 1989; 62-5; 605.

• Shogo Minagi :A study on prevention of AIDS and Hepatitis B disinfection of hydrophilic silicone rubber impression material. JPD 1990; 64-4; 463.

• J. Matyas :A study on the effects of disinfectant on dimensional accuracy of impression materials. JPD 1990; 64-1-25.

Thankyou , next seminar will be presented by Dr. Humaira on ceramics- history and recent.

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