T.HARI RAMACHANDRAN

Intern (2009-2010)

Dept of periodontics & implant dentistry

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INTRODUCTION TRANSMISSION OF INFECTION MODE OF TRANSMISSIONINFECTION CONCERN IN DNTISTRYOBJECTIVES OF INFECTION

CONTROLPERSONAL BARRIER PROTECTIONEMERGENCY & EXPOSURE INCIDENT

PLANOPERATORY ASEPSIS 2

DISINFECTIONCLINICAL WASTE DISPOSALINSTRUMENT HANDLING &

CLEANINGSTERILIZATIONMONITORS OF STERILIZATONSTORAGE OF STERILIZED ITEMS HANDPIECE ASEPSISCONCLUSION.

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Microorganisms 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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INFECTION CONTROL – Also called “exposure control plan” by OSHA is a required office program that is designed to protect personnel against risks of exposure to infection.

EXPOSURE – is defined as specific eye, mouth, other mucous membrane, non intact skin, or parenteral contact with blood or other potentially infectious materials.

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UNIVERAL PRECAUTIONS - means that all patients and blood contaminated body fluids are treated as infectious.

WORK PRACTICE AND ENGINEERING CONTROLS – are terms that describe precautions(e.g; careful handling of sharps) and use of devices to reduce contamination risks(high volume suction)

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PERSONAL PROTECTIVE EQUIPMENT (PPE) – is a term used for barriers, such as gloves, gown, or mask.

HOUSEKEEPING – is a term that relates to cleanup of treatment-soiled operatory equipment, instruments, counters, and floors, as well as to management of used gowns and waste.

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STERILIZATION: Use of a physical or chemical procedure to destroy all microorganisms including substantial numbers of resistant bacterial spores.

Sterilization means the destruction of all life forms. (Ronald B Luftig)

Sterilization is the process of killing or removing all viable organisms. (MIMS – PLAYFAIR)

STERILE: Free from all living microorganisms; usually described as a probability (e.g., the probability of a surviving microorganism being 1 in 1 million).

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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).

Disinfection is a process of removing or killing most, but not all, viable organisms.(MIMS-PLAYFAIR).

Disinfection refers to the destruction of pathogenic organisms.(Ronald B Luftig).

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DISINFECTANT: A chemical agent used on inanimate objects to destroy virtually all recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., bacterial endospores).

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Infection transmission during dental procedures is dependent on four factors:

1. Source of infection – may be a patient or a member of the dental team who is suffering from, or is a carrier of, an infectious disease.

SOURCE

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Patients suffering from acute infection

Patients in prodromal

stage

carriers

known unknown

2. Means of transmission – Micro organisms capable of causing disease are present in human blood and saliva.Contact with blood or saliva may transmit such pathogenic organisms causing infection.

3. Route of transmission – Transmission may occur due to inhalation or inoculation.

4. Susceptible host – Is a person who lacks effective resistance to a particular micro organism. E.g immunocompromised patients, pregnant women and children.

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Direct contact with blood or body fluids 

Indirect contact with a contaminated instrument or surface  

Contact of mucosa of the eyes, nose or mouth with droplets or spatter  

Inhalation of airborne microorganisms

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Infection through any of these routes requires that all of the following conditions be present:

An adequate number of pathogens, or disease-causing organisms.

A reservoir or source that allows the pathogen to survive and multiply (e.g., blood).

A mode of transmission from the source to the host.

An entrance through which the pathogen may enter the host.

A susceptible host (i.e., one who is not immune).

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TRANSMITTED BY INHALATION

Varicella virus Chicken pox

Paramyxovirus Measles & mumps

Rhino/ adeno virus Common cold

Rubella German measles

Mycobacterium Tuberculosis

Candida sp. Candidosis.

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TRANSMITTED BY INOCULATION

Hepatitis B,C,D virus

Hepatitis B, hep C,

Hepatitis D

Herpes simplex I Oral herpes, herpetic whitlow

Herpes simplex II Genital herpes

HIV AIDS & ARC

Neisseria gonorrhoeae

Gonorrhea

Treponema pallidum

Syphilis

S.aureus/albus Wound abscesses

To protect the patient and members of the dental team from contracting infections during dental procedures

To reduce the numbers of pathogenic micro-organisms in the dental operatory to the lowest possible level.

To implement a high standard of infection control when treating every patient (universal precautions)

To simplify infection control, thus allowing the dental team to complete treatment with minimal inconvenience.

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All patients must be screened.Barriers for personal protection.Careful aseptic techniques.Sterilization & disinfection.Disposal of contaminated waste safely.Laboratory asepsis.

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Personal protective equipment (PPE), or barrier precautions, are a major component of Standard precautions.

PPE is essential to protect the skin and the mucous membranes of personnel from exposure to infectious or potentially infectious materials.

The various barriers are gloves, masks, protective eye wear, surgical head cap & overgarments

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All clinical personnel must wear treatment gloves during all procedures.

Types:1. Latex gloves2. Vinyl gloves3. Nitile gloves4. General purpose utility gloves Latex gloves are the preferred operatory

gloves. Gloves manufactured by DOUBLE DIP

process are better than single dip because they have less pinholes & use less irritating catalyzing coagulants.

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Gloves powdered using cornstarch or cetylpyridium chloride is better than talcum powder (mineral) which may cause irritation.

Medical gloves, both patient examination and surgeon's gloves, are manufactured as single-use disposable items that should be used for only one patient, then discarded.

Gloves should be changed between patients and when torn or punctured.

Gloves must have < than 4% leak detectable by a water test.( FDA regulation).

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Hand hygiene (e.g., handwashing, hand antisepsis, or surgical hand antisepsisis) considered the single most critical measure for reducing the risk of transmitting organisms to patients and health care professionals.

The microbial flora of the skin, consist of transient and resident microorganisms . Transient flora, which colonize the superficial layers of the skin, are easier to remove by routine handwashing.

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They are often acquired by personnel during direct contact with patients or contaminated environmental surfaces; these organisms are most frequently associated with health-care associated infections.

Resident flora attached to deeper layers of the skin are more resistant to removal and less likely to be associated with such infections.

For routine dental examinations procedures, handwashing is achieved by using either a plain or antimicrobial soap and water.

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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.

Skin bacteria can rapidly multiply under surgical gloves if hands are washed with soap that is not antimicrobial . Thus, an antimicrobial soap or alcohol hand rub with persistent activity should be used before surgical procedures.

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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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CHLORHEXIDINE BASED – these contain 2- 4% chlorhexidine gluconate with 4% isopropyl alcohol in a detergent solution with a pH of 5.0 to 6.5. They have broader activity for special cleansing(e.g: for surgery, glove leaks, or when clinician experiences injury). But it can be hazardous to eyes.

POVIDONE IODONE – contain 7.5-10% povidone iodine, used as a surgical hand scrub.

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PARACHLOROMETEXYLENOL(PCMX) – they are bactericidal and fungicidal at 2% concentration. Non irritating and recommended for routine use.

ALCOHOL HAND RUBS- ethyl alcohol and isopropyl alcohol are widely used at 70% concentration. They are rapidly germicidal when applied to the skin.

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Masks protect the face from splatter and prevent inhalation of aerosols.

Aerosols are airborne debris, smaller than 5ųm in dia, that remain suspended in air.

Splatter are larger blood contaminated droplets which may contain sharp debris.

A mask should have a bacterial filtration efficiency of 95% or more.

It should have a close fit around the entire periphery.

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Masks with highest filtration are rectangular folded types.

Dome shaped masks are adequate barriers against spatter but not against respiratory viruses.

The mask's outer surface can become contaminated with infectious droplets from spray of oral fluids or from touching the mask with contaminated fingers.

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When airborne infection isolation precautions are necessary (e.g., for TB patients), a National Institute for Occupational Safety and Health (NIOSH)-certified particulate-filter respirator (e.g., N95, N99, or N100) should be used.

N95 refers to the ability to filter 1-µm particles in the unloaded state with a filter efficiency of >95% (i.e., filter leakage <5%), given flow rates of <50 L/min (i.e., approximate maximum airflow rate during breathing).

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Available data indicate infectious droplet nuclei measure 1-5 µm; therefore, respirators used in health-care settings should be able to efficiently filter the smallest particles in this range.

Face shields are appropriate for heavy spatter but should not be used without a mask.

A new surgical mask has to be used for each patient.

Mask must be changed every hour or sooner if it becomes wet.

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Masks must be removed by grasping only the string or band at the sides or back of the head.

Personnel must also protect their hair with a surgical cap when encountering heavy spatter.

Appropriate work practices, including use of dental dams and high-velocity air evacuation, should minimize dissemination of droplets, spatter, and aerosols.

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CAUSES OF EYE DAMAGE: Aerosols and spatter may transmit

infectionSharp debris projected from mouth while

using air turbine handpiece, ultrasonic scaler may cause eye injury.

Injuries to eyes of patients caused by sharp instruments especially in supine position.

Therefore both the clinician and patients must use protective eyewear.

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Protective eyewear consists of glasses with solid eyeshields.

Eyewear must be put on with clean hands before gloving and must be removed after gloves are removed.

Eyewear and shields must be cleaned and disinfected with water based disinfectant that is allowed to stand for 5 mins.

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Protective clothing (e.g., gowns, lab coats) should be worn to prevent contamination of street clothing and to protect the skin of clinician from exposures to blood and body substances.

OSHA bloodborne pathogens standard requires sleeves to be long enough to protect the forearms when the gown is worn (i.e., when spatter and spray of blood, saliva to the forearms is anticipated).

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A simple, lightweight garment that covers the arms and chest up to the neck as well as the lap when seated appears to provide adequate protection.

Overgarments must be changed whenever becoming moist or visibly soiled.

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Engineering controls are the primary method to reduce exposures to blood from sharp instruments and needles.

Work-practice controls establish practices to protect personnel whose responsibilities include handling, using, or processing sharp devices.

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Work-practice controls for needles and other sharps include placing them in appropriate puncture-resistant containers located as close as feasible to where the items were used.

Sharp end of instruments must be pointed away from the hand

Avoid handling large number of sharp devices.

Work-practice controls include removing burs before disassembling the handpiece from the dental unit, restricting use of fingers in tissue retraction during suturing and administration of anesthesia, and minimizing uncontrolled movements of sharp instruments.

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Used needles should never be recapped or otherwise manipulated by using both hands, or any other technique that involves directing the point of a needle toward any part of the body.

A one-handed scoop technique, a mechanical device designed for holding the needle cap to facilitate one-handed recapping, or an engineered sharps injury protection device (e.g., needles with resheathing mechanisms) should be employed for recapping needles.

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Personnel should never bend or break needles before disposal because this practice requires unnecessary manipulation.

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Management of exposure includes:A. General wound care and cleaning.B. Counseling of the exposed worker

regarding bloodborne pathogens.C. Source patient testing for HBV,HCV and

HIV (consent required).D. Documentation of the incident and review.E. Postexposure assessment and prophylaxis

for the health care worker.F. Baseline and follow up serology of the

worker.

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IF AND THEN

Source pt is +ve for HBsAG

Exposed worker not vaccinated

Worker should receive vaccine series should receive single dose of HB immunoglobulin within 7 days.

Exposed worker has been vaccinated

Should be tested for anti-HBs & given 1 dose of vaccine & 1 dose of HBIG if < 10 IU

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IF AND THEN

Source pt is –ve for HBsAg

Exposed worker not vaccinated

Worker should be encouraged to receive hepatitis B vaccine.

Exposed worker has been vaccinated

No further action is needed.

Source pt refuses testing or not identified

Exposed worker not vaccinated

Should receive HB seriesHBIG should be considered

Exposed worker has been vaccinated

Management should be individualized.

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IF THEN AND

Source pt has AIDS

ORSource pt is HIV+ve

ORSource Pt refuses to be tested

Exposed worker should be counseled about risk of infection.Should be tested for HIV infection immediatelyShould be asked to seek medical advice for any febrile illness within12 weeksRefrain from blood donation & take appropriate precautions

Exposed worker testing –ve initially should be retested 6 weeks, 12 weeks & 6 months after exposure.

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IF THEN AND

Source pt is tested & found -ve

Baseline testing of the exposed worker with follow up testing 12 weeks later

Source cannot be identified

Serological testing must be done &

decisions must be individualized

In the dental operatory, environmental surfaces (i.e., a surface or equipment that does not contact patients directly) can become contaminated during patient care. Certain surfaces, especially ones touched frequently (e.g., light handles, unit switches, and drawer knobs) can serve as reservoirs of microbial contamination, although they have not been associated directly with transmission of infection to either personnel or patients.

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Transfer of microorganisms from contaminated environmental surfaces to patients occurs primarily through personnel hand contact.

When these surfaces are touched, microbial agents can be transferred to instruments, other environmental surfaces, or to the nose, mouth, or eyes of workers or patients.

Although hand hygiene is key to minimizing this transfer, barrier protection or cleaning and disinfecting of environmental surfaces also protects against infections.

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Strategies for cleaning and disinfecting surfaces in patient-care areas should consider the

1) potential for direct patient contact; 2) degree and frequency of hand

contact; and 3) potential contamination of the

surface with body substances or environmental sources of microorganisms (e.g., soil, dust, or water)

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Protect surfaces and equipment that are not sterilized with disposable, single-use covers (barriers).

Discard them after every appointment. Use disposable covers on portable items (e.g., curing lamp handles, amalgam mixers, and plastic air-water syringe tips).

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Almost 40 years ago, Dr. E. H. Spaulding proposed a classification system for disinfecting and sterilizing medical and surgical instruments. This system, or variations of it, has been used in infection control over the years.

According to the CDC, patient-care items (eg, dental instruments, devices, and equipment) are categorized as critical, semicritical, or noncritical, based on the potential risk of transmitting infection if the item becomes contaminated during use.

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Instruments that contact cut tissues or penetrate tissues are considered to be critical items that require thorough cleaning and sterilization for reuse. E.g dental burs, endodontic files etc.

Semicritical items that touch mucosa are the air/water syringe tip, suction tips, prophy angle, and handpieces. Others (air/water syringe handle etc) are handled or touched interchangeably with treatment instruments that become contaminated with blood and saliva.

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Semicritical items must be removed for cleaning and sterilization unless they are either disposable or can be protected from contamination with disposable plastic covers.

Noncritical items are environmental surfaces such as chairs, benches, floors, walls, and supporting equipment of the dental unit that are not ordinarily touched during treatments.

Contaminated noncritical items require cleaning and disinfection.

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Disinfection is always at least a two-step procedure:

The initial step involves vigorous scrubbing of the surfaces to be disinfected and wiping them clean.

The second step involves wetting the surface with a disinfectant and leaving it wet for the time prescribed by the manufacturer.

There is no such thing as a “one-step disinfectant” The disinfectant step must always be preceded by cleaning.

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The ideal disinfectant has the following properties:

Broad spectrum of activityActs rapidlyNon corrosiveEnvironment friendlyIs free of volatile organic compoundsNontoxic & nonstaining

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High-level disinfection: Disinfection process that inactivates vegetative bacteria, mycobacteria, fungi, and viruses but not necessarily high numbers of bacterial spores. FDA further defines a high-level disinfectant as a sterilant used for a shorter contact time.

Intermediate-level disinfection: Disinfection process that inactivates vegetative bacteria, the majority of fungi, mycobacteria, and the majority of viruses (particularly enveloped viruses) but not bacterial spores.

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Low-level disinfectant: Liquid chemical germicide registered with EPA as a hospital disinfectant. OSHA requires low-level hospital disinfectants also to have a label claim for potency against HIV and HBV.

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Strategies for decontaminating spills of blood and other body fluids differ by setting and volume of the spill.

The person assigned to clean the spill should wear gloves and other PPE as needed.

Visible organic material should be removed with absorbent material (e.g., disposable paper towels discarded in a leak-proof, appropriately labeled container).

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Nonporous surfaces should be cleaned and then decontaminated with either an hospital disinfectant effective against HBV and HIV or an disinfectant with a tuberculocidal claim (i.e., intermediate-level disinfectant).

However, if such products are unavailable, a 1:100 dilution of sodium hypochlorite (e.g., approximately ¼ cup of 5.25% household chlorine bleach to 1 gallon of water) is an inexpensive and effective disinfecting agent.

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Regulated medical waste is only a limited subset of waste: 9%-15% of total waste in hospitals and 1%-2% of total waste in dental offices.

Examples of regulated waste found in dental-practice settings are solid waste soaked or saturated with blood or saliva (e.g., gauze saturated with blood after surgery), extracted teeth, surgically removed hard and soft tissues, and contaminated sharp items (e.g., needles, scalpel blades, and wires.

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Regulated medical waste requires careful containment for treatment or disposal.

A single leak-resistant biohazard bag is usually adequate for containment of nonsharp regulated medical waste.

Puncture-resistant containers with a biohazard label, located at the point of use (i.e., sharps containers), are used as containment for scalpel blades, needles, syringes, and unused sterile sharps.

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All containers with blood or saliva (e.g., suctioned fluids) can be carefully poured down a utility sink or drain.

Adding 5% hypochlorite in water to suctioned fluids is recommended before disposing into the drain.

Multiple bloodborne pathogens, are not stable in the environment for long periods, and the discharge of limited quantities of blood into the sanitary sewer is considered a safe method for disposing of these waste materials.

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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.

Wear protective utility gloves at all times to handle contaminated instruments.

Organic debris on instruments is likely to reduce activity of the disinfectant.

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

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

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

Still wearing protective gloves, properly package the instruments together with internal and external sterilization indicators suited to the sterilization process use.

Cloth packs, wraps, or commercial paper/plastic bags are suitable for instrument containment if they are compatible with the method of sterilization.

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Ultrasonic cleaning is the safest and most efficient way to clean sharp instruments.

An ultrasonic cleaning device should provide fast and thorough cleaning without damage to instruments; have a lid, well-designed basket, and audible timer; and be engineered to prevent electronic interference with other electronic equipment

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Operate the tank at one-half to three-fourths full of cleaning solution at all times- Use only cleaning solutions recommended by ultrasonic device manufacturers.

Operate the ultrasonic cleaner for 5 minutes or longer as directed by the manufacturer to give optimal cleaning.

Devices, that-have less than two transducers do not pass the foil test and are not suitable for instrument cleaning.

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There are 4 distinct stages for instrument sterilization:

1) Pre cleaning disinfection, using holding solutions

2) Pre – sterilization cleaning.3) Sterilization4) Aseptic storage.

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The four accepted methods of sterilization are :

A. Steam pressure sterilization (autoclave) B. Chemical vapor pressure sterilization-

(chemiclave)C. Dry heat sterilization (dryclave) D. Ethylene oxide sterilization Patient load, turnaround time for

instrument reuse, instrument variety and quality must all be balanced against the type of sterilizer selected.

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The autoclave basically consists of cylinder of gun metal or stainless steel with an air tight lid.

Has an discharge tap for air and a pressure gauge.

Two basic types of steam sterilizers are the gravity displacement and the high-speed prevacuum sterilizer.

Unlike hospital autoclaves, bench models depend on gravity flow to distribute steam throughout the load rather than first evacuating air from the sterilizer and then refilling it with steam.

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For a light load of instruments, the time required at 250° F (121° C) is a minimum of 15 minutes at 15 lbs of pressure.

Time for wrapped instruments can be reduced to 7 minutes if the temperature is raised to approximately 273° F (134° C) to give 30 pounds of pressure.

Time required for the sterilizer to reach the correct temperature is not included.

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Steam must enter and circulate around packs easily. Instrument pans or other impermeable instrument containers must be left open so steam can enter.

Moist heat kills microorganisms through protein coagulation, RNA and DNA breakdown and release of low molecular weight intracellular constituents.

Instruments made of alloys of carbon steel and tungsten carbide are susceptible to corrosion during repeated autoclaving. The use of 2% sodium nitrite solution coating minimizes such damage.

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Advantages of Autoclaves. Autoclaving is the most rapid and

effective method for sterilizing cloth surgical packs and towel packs.

Is dependable and economicalSterilization is verifiable.

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Disadvantages of Autoclaves. Items sensitive to the elevated

temperature cannot be autoclaved.Autoclaving tends to rust carbon steel

instruments and burs. Instruments must be air dried at

completion of cycle.

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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.

Principle is that although some water is necessary to catalyze the destruction of all microorganisms in a relatively short time, water saturation is not necessary.

Kills microorganisms by destroying vital proteins.

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Chemical vapor pressure sterilizers operate at 270° F (131° C) and 20 pounds of pressure.

They must be used with a prescribed chemical and should be properly labeled to satisfy OSHA's Chemical Hazard Communication Standard.

Unsaturated chemical-vapor sterilization involves heating a chemical solution of primarily alcohol with 0.23% formaldehyde in a closed pressurized chamber

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Advantages of Chemiclaves Carbon steel and other corrosion-sensitive

instruments are said to be sterilized without rust.

Relatively quick turnaround time for instruments.

Load comes out dry. Sterilization is verifiable.Disadvantages of Chemiclaves Items sensitive to the elevated temperature

will be damaged. Vapor odor is offensive, requires aeration.

Heavy cloth wrappings of surgical instruments may not be penetrated to provide sterilization.

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Conventional Dry Heat Ovens Dry heat sterilization is readily achieved at

temperatures above 320° F (160° C) for 30 mins.

Instrument loads may take 30- 90 mins to reach that temperature, so to provide a margin of safety, instruments must be sterilized at 160ºC for 2 hours.

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

Packs of instruments must be placed at least 1 cm apart to allow heated air to circulate.

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Kills microoragnisms primarily by an oxidation process. Protein coagulation also occurs depending on the water content of protein.

High concentrations of mercury vapor can develop in a dry heat oven that has been used to sterilize amalgam instruments. Thus great care must be taken to scrap amalgam of any instrument.

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Short-Cycle, High-Temperature Dry Heat Ovens

It is a high-temperature process that uses a forced-draft oven (a mechanical convection oven that circulates air with a fan or blower)

It reduces total sterilization time to 6 minutes for unwrapped and 12 minutes for wrapped instruments.

These short-cycle high-temperature dry heat ovens operate at approximately 370° to 375° F .

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Advantages of Dry Heat SterilizationCarbon steel instruments and burs do not rust,

corrode, if they are well dried before processing. Industrial forced-draft hot air ovens usually

provide a larger capacity at a reasonable price. Rapid cycles are possible at high temperatures.Low initial cost and sterilization is verifiable.Disadvantages of Dry Heat SterilizationHigh temperatures may damage more heat-

sensitive items, such as- rubber or plastic goods.

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Sterilization cycles are prolonged at the lower temperatures.

Must be calibrated and monitored.

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ETHYLENE OXIDE STERILIZATION (ETO)

Was first used in 1940’s by US army.Ethylene oxide sterilization is the best

method for sterilizing complex instruments and delicate materials because of extreme penetrability of the ETO molecule and low temperature(70ºF- 140ºF).

Kills microorganisms by reacting chemically with nucleic acids. The basic reaction is alkylation of hydroxyl groups. 82

Porous and plastic materials absorb the gas and require aeration for 24 hours or more before it is safe for them to contact skin or tissues.

Advantages:Operates effectively at low temperaturesGas is extremely penetrativeCan be used for sensitive equipment like

handpieces.Sterilization is verifiableDisadvantages:Potentially mutagenic and carcinogenic.Requires aeration chamber ,cycle time lasts

hoursUsually only hospital based.

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Heat-sensitive critical and semicritical instruments and devices can be sterilized by immersing them in liquid chemical germicides registered by FDA as sterilants.

Items need to be 1) rinsed with sterile water to remove toxic or irritating residues;

2) handled using sterile gloves and dried with sterile towels; and

3) delivered to the point of use in an aseptic manner. 84

They can kill bacterial spores in 6 to 10 hours.

Sterilants used for high-level disinfection of items for reuse are glutaraldehydes at 2% to 3% concentrations which kills by altering essential protein components.

Glutraldehyde molecules has two active carbonyl groups which react with proteins through cross linking reactions.

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High-level disinfection is used mainly for plastic items that enter the mouth and that cannot withstand heat sterilization like plastic cheek retractors and photographic mirrors.

Disadvantages include prolonged time taken, irritating to skin & cannot be monitored with biological indicators.

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NEW METHODS OF STERILIZATION Various new methods of sterilization are

under investigation and development. 1. 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

2. 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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The storage area should contain enclosed storage for sterile items and disposable (single-use) items.

Storage practices for wrapped sterilized instruments can be either date- or event-related

Dental supplies and instruments should not be stored under sinks or in other locations where they might become wet.

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There are 3 methods of monitoring sterilization:

Mechanical techniques for monitoring sterilization include assessing cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer and noting these parameters for each load . Correct readings do not ensure sterilization, but incorrect readings can be the first indication of a problem with the sterilization cycle.

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Chemical indicators, internal and external, use sensitive chemicals to assess physical conditions (e.g., time and temperature) during the sterilization process.

External indicators applied to the outside of a package (e.g., chemical indicator tape or special markings) change color rapidly when a specific parameter is reached, and they verify that the package has been exposed to the sterilization process.

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Internal chemical indicators should be used inside each package to ensure the sterilizing agent has penetrated the packaging material and actually reached the instruments inside.

Biological indicators (BIs) (i.e., spore tests) are the most accepted method for monitoring the sterilization process because they assess it directly by killing known highly resistant microorganisms (e.g., Geobacillus or Bacillus species), rather than merely testing the physical and chemical conditions necessary for sterilization.

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Spores dried on absorbent paper strips are calibrated to be killed when sterilization conditions are reached and maintained for the necessary time to kill all pathogenic microorganisms.

Tests can be evaluated in the office. However, by sending the strip to a licensed reference laboratory for testing, the dentist obtains independent documentation of monitoring frequency and sterilization effectiveness.

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STERILIZATION METHOD

SPORE TYPE INCUBATION TEMPERATURE

AUTOCLAVE Baccilus stearothemophilus

56°C

CHEMICAL VAPOR

DRY HEAT Baccilus subtilis 37°C

ETHYLENE OXIDE

Sterilization monitoring has four components:

(1) a sterilization indicator on the instrument bag, stamped with the date it is sterilized,

(2) daily color-change process-indicator strips,

(3) weekly biologic spore test, and (4) documentation notebook.In dental offices, sterilization must be

monitored weekly with biologic spore tests using heat-resistant spores and tested daily with color-change process-indicator strips.

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Oral fluid contamination problems of rotary equipment and especially the high-speed handpiece involve:

1. contamination of hand-piece external surfaces and crevices,

2. turbine chamber contamination that enters the mouth,

3. water spray retraction and aspiration of oral fluids into the water lines of older dental units

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4. growth of environmental aquatic bacteria in water lines, and

5. exposure of personnel to spatter and aerosols generated by intraoral use of rotary equipment.

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Blood and saliva contaminate the surfaces of handpieces during various dental treatments.

Irregular surfaces and especially crevices around the bur chuck are difficult to clean and disinfect.

Submersion of a high-speed handpiece in a high-level disinfectant has not been an accepted option.

Only sterilization can approach complete infection control of handpiece surfaces.

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Pervasive increases in serious transmissible diseases over the last few decades have created 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.

Infection control has helped to allay concerns of the health care personnel and instill confidence and in providing a safe environment for both patient and personnel.

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The art & science of operative dentistry- Sturdevant.

Pathways of the pulp – Cohen.Endodontic practice – Grossman.Infection control in dentistry- PeterWoodsGuidelines of infection control in

dentistry – CDC – MMWR reports. (Dec2003).

Textbook of microbiology – DavisTextbook of operative dentistry- Baum,

Phillips, Lund

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