INFECTION CONTROL IN

OPERATIVE DENTISTRY

S. MANEESH AHAMED FINAL YEAR PART 1 ROLL .NO: 12

• Pervasive increase in serious transmissible diseases over the last few decades have created global concern and affected the treatment approach of health care practitioners all over the globe.

• Every health care speciality that involves contact with mucosa, blood, or blood contaminated body fluids should be regulated for the prevention of transmission of certain infective diseases.

INTRODUCTION

• Operative dentistry in its prime objective to provide the highest standard of care, emphasis on ensuring maximum protection against infectious diseases.

• In Operative dentistry, we generally deal with ambulatory, relatively healthy patients who may carry many infectious diseases unknowingly. Also, the dentist or any member or staff may be suffering from some infection.

• It is therefore essential that all members of the dental team have a clear understanding of infection transmission and various methods of controlling the same.

ENVIONMENT OF THE DENTAL OPERATORY

Microbial exposures in the dental operatory include :

1. Air-borne contamination 2. Direct contamination of surfaces 3. Indirect contamination of surfaces. 4. Cross-infections 5. Patient vulnerability 6. Personal vulnerability.

To comprehend the problem of microbial contamination that confronts dentistry, it is necessary to examine the dental treatment environment.

AIR-BORNE CONTAMINATION

• A high speed handpiece is capable of producing air-brone contaminants from bacterial residents in the dental unit water spray system and from microbial contaminants from saliva, tissues, blood, plaque, and fine debris cut from carious teeth.

• Air borne contaminants exist in 3 forms; with respect to the particle size :

1. AEROSOLS : • Particle size ranges from 50 mm to 5

mm. • Remain suspended in the air and

breathed for hours.• They may carry agents of respiratory

infection borne by the patient. • Aerosols produced by the cough of a

patient with unrecognized active pulmonary or pharyngeal tuberculosis are likely to transmit the infection.

2. MIST : • Consist of particles that approach or exceeds

50mm in size • They usually become visible in a beam of

light .• Heavy mists tend to settle gradually from the

air after 5 to 15 minutes. • Combined with Aerosol, mists can also

transmit respiratory infections like tuberculosis. 3. SPLATTER :

• Consist of particles generally larger than 50 mm and even visible splashes.

• They have a distinct trajectory, usually falling within 3ft of the patient’s mouth,

• have the potential for clotting the face and outer garments of the attending personnel.

• Splatter or splashing of mucosa is considered a potential route of infection for dental personnel by blood – borne pathogens.

CONTROL MEASURES :

• Use masks, protection eyewear, gloves, and gowns.

• Pre-treatment mouth rinse• Rubber dam, high velocity air evacuation.• Adequate air circulation • Masks should be kept in place until air

exchange in the room has occurred or until personnel leave the operatory.

DIRECT CONTAMINATION

• Direct contamination occurs when there is direct contact with body fluids.

• This is a major exposure concern for dental personnel.

INDIRECT CONTAMINATION

• With saliva-contaminated hands, the hygienist, dentist, and assistant could repeatedly contact or handle unprotected operatory surfaces during treatments.

• The invisible trail of saliva left on such contaminated surfaces often defies either awareness or effective clean up.

• Moreover, it may act as a source of cross-contamination of patients.

• Items or areas which usually get contaminated include handpieces, unprotected lamp handles, air-water syringe handle, control switches on the patient’s chair etc. CONTROL

MEASURES

• Barrier protection of personal and equipment, proper instrument sterilization.

• Methods of avoiding direct contact with various surfaces are required.

CROSS-INFECTIONS

• Infected patients who are usually unaware of their infection go elsewhere for diagnosis and treatment of oral and non-oral conditions.

• Infection outbreaks are recognized in epidemiological studies where they usually occur in clusters.

PATIENT VULNERABILITY• Although infection risks for dental patients have not been as

well investigated as risks of hospital patients, they seem to be low.

• Nine cluster cases of dentist to patient transmission of HBV and one cluster case of HIV have been documented since 1971.

• Since 1986, after the widespread implementation of infection control practices no new cluster cases of HBV is reported.

PERSONNEL VULNERABILITY

• Dental personnel who is exposed to saliva, blood, and possible injury from sharp instrumentation while treating patients are more vulnerable to infections.

• Vulnerability of dental personnel before the institution of infection control standards provide the best barometer of this.

• Proper immunisation and protective barriers are thus essential for reducing the vulnerability to infections.

IMPACT OF HEPATITIS B VIRUS• HBV was the first infection disease to gain attention as a risk

for health care personnel• HBV vaccine has curtailed HBV infection dramatically among

dental personnel who have been infectively immunised.• Infection control procedures remain a major concern,

however, to prevent cross-infection among patients.

• In history, several cluster cases of HIV infection transmitted by dental personnel have been reported. (Eg: Florida dentist, USA )

• Evidences indicates that the HIV infections from infected clinicians took to patients could have been prevented by use of infection control procedures.

IMPACT OF HIV AND AIDS

OSHA (Occupation Safety and Health Administration)

• OSHA is a Federal regulatory agency under the US Department of Labor.

• OSHA Blood borne pathogens program addresses control of occupational exposure to blood and other potentially infectious materials.

• It describes infection control as ‘Exposure control plan’. ‘Housekeeping’ is the term used to describe the clean up and sterilization procedures.

• Several other terminologies introduced in OSHA regulations are ‘work practice controls’ and ‘engineering controls’. The term ‘personal protective equipment’ (PPE) is used for barriers such as gloves, gowns, or masks.

• Only in dentistry is saliva considered a potentially infectious material because oral manipulations and dental treatments routinely cause saliva to become contaminated with the patients blood.

ASEPSIS : The prevention of contact with pathogens. In dentistry this

includes the technique of barrier protection, sterilization and disinfection.STERILIZATION :

The destruction of all forms of life including the most heat resistant bacterial spores. Practically, sterilization denotes the use of physical and chemical agents to eliminate all viable microorganisms, including bacteria, fungi, virus and spores.

DISINFECTION : The destruction of pathogenic agents by directly applied

physical or chemical means. Here spores are not destructed. ANTISEPTICS :

Agents that prevent the growth or action of microorganisms on living tissues.

DISINFECTANTS : Chemicals capable of killing pathogenic organisms when

applied to inanimate objects.

VARIOUS ASPECTS OF INFECTION CONTROL

INFECTION CONTROL IN DENTAL CLINIC

• Spread of infection in a dental clinic occur either by direct inoculation or inhalation.

• Infection control measures can be broadly categorized as follows:1. PERSONAL BARRIER PROTECTION.

2. DISPOSAL OF CLINICAL WASTES.

3. STERILIZATION AND DISINFECTION.

GLOVES• OSHA regulations specify that all clinical personnel must

wear treatment gloves during treatment procedures.• Fresh gloves must be used for every patient.• Torn or punctured gloves must be discarded

immediately. • Instead of acting as a barrier gloves worn for a longer

periods can harbor blood-borne and saliva-borne pathogens.

• Gloves must not be washed with hand soaps. Washing reduces glove integrity, leaving personnel more vulnerable.

PERSONAL BARRIER PROTECTION

HANDWASHING

• Meticulous hand care can prevent the transmission of infections to a major extend.

• At the beginning of the routine treatment period, the clinician should remove watches, jewellery, and rings and wash the hands with a suitable cleanser.

• Hands should be lathered for at least 10 seconds, rubbing all surfaces, and rinsed.

• Hand cleansers having containing a mild antiseptic, such as 3% parachlorometaxylenol (PCMX) or 4% chlorhexidine, are preferred to control transient pathogens and to suppress overgrowth of skin bacteria.

PROTECTIVE EYEWEAR, MASKS, AND HAIR PROTECTION• Protective eye wear may consist of goggles or glasses with

solid side shields.• A mask should be worn to protect against aerosols. • Face shields are appropriate for heavy splatter, but masks are

still required to protect against aerosols that drift behind the shield.

• Eyewear is worn with a lean hand before gloving and removed after the removal of gloves and hand washing.

• Masks should be grasped only by the strings or bands on its side or back of the head to remove it.

• The mask should be changed between every patient or whenever it becomes moist or visibly soiled.

• Masks with the highest filtration are rectangular, folded types used for surgeries.

• Dome-shaped masks are adequate barriers against splatter and are considered to prevent HBV and HIV infection.

PROTECTIVE OVERGARMENTS

• An overgarment must be protective of clothing and skin.• Overgarments must be changed whenever becoming moist

or visibly soiled. • Used overgarments require a minimum handling and must be

laundered easily. • Wearing contaminated garments home or out of the clinical

area should not occur.

DISPOSAL OF CLINICAL WASTE• Infected blood and other liquid clinical waste generally can be

poured down a sanitary sewer or drain designated for that purpose.

• Mercury, silver or other heavy metals are however should be disposed separately.

• Contaminated material such as used masks , gloves, blood-soaked or saliva-soaked cotton rolls, must be discarded safely.

• Pathologic waste, excised tissues require separate disposal and may not be discarded into the trash.

• Needle disposal is done in a hard walled, leak proof, and sealed container, which has biohazard label

• Judgement is essential in bagging medical waste so that injury or direct contact with liquids does not occur because HIV and HBV can survive beyond a few days while wet.

OPERATORY ASEPSIS The dental operatory must be maintained spotlessly clean. The items in the dental operatory can be categorized into three groups :

1. CRITICAL ITEMS : These include instruments that contact cut tissue or those that penetrate the soft tissues. Eg : Needles, scalpels, endodontic instruments.

2. SEMICRITICAL ITEMS : These include all instruments that enter the patient’s mouth. These also include items attached to the dental unit which are used intra-orally during treatment. Eg: Air/water syringe tip, suction tips, hand pieces,

3. NON-CRITICAL ITEMS : These are environmental surfaces such as chairs, benches, floors, walls and supporting equipments of the dental unit which are not ordinarily touched during treatments.

STERILIZATION

PROCEDURES BEFORE STERILIZATION

1. PRESOAKING OF INSTRUMENTS : Contaminated instruments are kept soaked in a chemical disinfectant like Gluteraldehyde or synthetic phenol for 30 minutes. This will prevent blood and saliva from drying on the instruments thus facilitating cleaning.

2. PRESTERILIZATION CLEANING OF INSTRUMENTS : After soaking the contaminated instruments for some time, they must be thoroughly cleaned before sterilization in order to remove gross organic debris, blood and saliva.

Cleaning can be done by :

A. MANUAL METHOD : after wearing protective utility gloves the instruments may be cleaned using a hard brush with stiff bristles along with a detergent solution or using soap and water.

B. ULTRA SONIC METHOD : it is much more effective and safer than hand cleaning. Presoaked instruments may be immersed in an ultrasonic cleaner and kept in bath for 5 minutes.

• Pizoelectric cleaners operates at 40◦ C and 35 KHz frequency.

• The tank is usually filled with a detergent solution to increase the effectiveness of cleaning.

• Ultrasonic cleaners employ pizoelectric oscillators situated underneath stainless steel enclosures to create oscillations in a fluid filled tank.

• The cavitation effect produces microscopic bubbles that effectively clean inaccessible areas on instrument surfaces.

METHODS OF STERILIZATION

A. STEAM PRESSURE STERILIAZATION (AUTOCLAVE)

B. DRY HEAT STERILIZATION (DRYCLAVE)

C. CHEMICAL VAPOUR PRESSURE STERILIZATION (CHEMICLAVE)

D.ETHYLENE OXIDE (ETOX) STERILIZATION

STEAM PRESSURE STERILIZATION / AUTOCLAVING

• The steam autoclaving is the most commonly used method of sterilization.

• Autoclaves uses super heated steam under pressure which have high degree of penetration.

• Moist heat produced inside the autoclave kills microorganisms by protein coagulation and breakdown of DNA and RNA.

• The autoclave consist of a double walled chamber to hold the instruments and the steam circulates inside it under pressure.

• It is the most rapid and effective method of sterilization.

STERILIZATION CYCLES• Standard : 121◦C (250◦F), 15 lbs pressure for 15

minutes. • Flash method : 134◦C (273◦F), 30 lbs pressure for 7-10

minutes.

TYPES OF AUTOCLAVES

1. DOWNWARD DISPLACEMENT AUTOCLAVES : They cause downward displacement of air as steam enters the top of the chamber. Their efficacy is low.

2. HIGH VACUUM AUTOCLAVES : They are also known as rapid cycle autoclaves. In these, air is evacuated by vacuum suction before steam enters the chamber. These autoclaves perform rapid and effective sterilization than conventional autoclaves and are presently popular in dentistry.

DISADVANTAGES OF AUTOCLAVES • Corrosion of carbon steel instruments and burs, steel

neck and shank of some diamond instruments and carbide burs.

• May damage plastic and rubber items• Dulls unprotected cutting edges.

DRY HEAT STERILIZATION / DRYCLAVE

• This method effectively sterilizes instruments at high temperature above 160◦C

• The apparatus is a dry heat oven which has heated chambers to allow air to circulate by gravity flow

• Dry heat kills microorganisms by an oxidation process• It has less penetration capacity as compared to moist heat in

autoclaves• Burs and carbon steel instruments do not rust if they are well

dried before sterilization. • Rapid cycles are possible at high temperatures in a dry heat oven.

STERILIZATION CYCLES• Conventional dry heat oven : 160◦C for 90 minutes

• Mechanical convection oven : 320-375◦C for 6-12 minutes

CHEMICAL VAPOUR PRESSURE STERILIZATION / CHEMICLAVE

• This method employs chemical vapour under pressure for sterilization.

• The apparatus is similar to the autoclave but uses a mixture of formaldehyde, alcohol, ketone, acetone, and water.

• When solution is heated under pressure it forms a gas that sterilizes instruments.

• The chemical vapour kills microorganisms by destroying vital protein systems.

• They does not corrode metals. Hand pieces however cannot be sterilized by this method.

STERILIZATION CYCLE• 131◦C (270◦F) under 20 lbs pressure for 20

minutes.

ETHYLENE OXIDE STERILIZATION• This method uses automatic devices filled with ethylene oxide

gas at temperatures below 100C • They are designed to sterilize complex instruments and

delicate materials. • Ethylene oxide is highly penetrable and kills microorganisms by

chemically reacting with nucleic acids. • The sterilization cycles takes several hours and once over,

aeration for 24 hours or more is needed before the instruments can be used.

• A major concern about using this method is the potential mutagenic / carcinogenic property of ethylene oxide gas.

MONITORING STERILIZATION

1. PROCESS INDICATORS : strips, tapes, tubes or paper marked with special ink that change colour on exposure appropriate sterilization cycle.

2. BIOLOGICAL INDICATORS : non pathogenic stains of microbial spores in the form of strips. It is done on a weekly basis. Eg: Bacillus stearothermophillus ( for Autoclaves) , Clostridium sp (Hot air oven).

NEWER MODALITIES OF STERILIZATION

• Several newer methods of sterilization are employed for specific purposes.

• Gamma rays are used to sterilize suture materials, syringes, disposable needles and other heat sensitive items.

• Ultraviolet light is used to purify air in the dental operatory but is not very effective.

• Hydrogen peroxide vapour, Gas plasma sterilization and the use of Lasers are still under investigation but are not yet practical for dentistry.

HANDPIECE STERILIZATION1. Prior to the removal of hand piece from the

dental unit, clean it by wiping visible debris using a suitable disinfectant such as alcohol.

2. Following this, run it for a minimum of 30 seconds to discharge residual water and air.

3. Next, clean the hand piece thoroughly with a soap or detergent solution.

4. Next, reattach hand piece to the unit and dry.

5. Lubricate the hand piece. (some manufacturers recommend lubrication after sterilization)

6. Finally, place the hand piece in a paper pack and seal it.

7. Now the hand piece can be sterilized by autoclaving.

DISINFECTION• They are used mainly for semi-critical and non-critical

items• Complete removal of all biologic forms of infective

organisms does not occur. • Some viruses and bacterial spores are resistant to

disinfection procedures. PHYSICAL METHOD – BOILING :Boiling water at 98C to 100C for 10 minutes. This method can be used to kill blood borne pathogens. But they cause extensive rusting of instruments.

CHEMICAL METHODS Chemical agents like Gluteraldehyde, Sodidum hypochlorite, Iodophores, Alcohols, Phenolics and Quaternary ammonium compounds can be used as disinfectants.

DENTAL WATER LINE CONTAMINATION AND BIOFILM• Dental unit water lines may be contaminated by biofilm. • Since biofilm is formed by the colonization and proliferation of

microorganisms, the water emitted by these water lines may contain high concentration of microorganisms.

• While using handpieces and air/water syringes, these microorganisms can be introduced into patients oral cavity.

METHODS TO REDUCE BIOFILM FORMATION IN WATER LINES 1. PERIODIC FLUSHING OF DENTAL UNIT WATER LINES

: This is done with sterile water or 1:10 dilution of 5.25% sodium hypochlorite is recommended. A minimum of 20 to 30 seconds of flushing o waterlines between patients is recommended.

2. USING FILTERS AND ANTIETRACTION VALVES : This is attached to the waterline which prevent the retraction of fluid back into the tubing.

3. USE OF STERILE WATER DELEVERY SYSTEMS

INFECTION CONTOL FOR IMPRESSIONS AND OTHER PROSTHETIC ITEMS• Thoroughly wash the impression or other prosthetic items

under running tap water to remove saliva, blood and debris. • Disinfect the surface of moist items including elastomeric

impressions by immersion in 2% Gluteraldehyde or chlorine compounds for 10 minutes.

• For alginate impressions, spray an Iodophor as soaking may distort the impression

• Store the items in separate sealed plastic bags before transfer to the laboratory.

CONCLUSIONAdequate asepsis is a highly critical step in treatment. Proper infection control measures are very much essential for the prevention of spread of serious infective diseases like TB, HBV, HIV etc. Personal barrier methods, proper disposal of waste and proper sterilization and disinfection insures adequate infection control in dental settings. Various personal barriers are available which has to be properly used during treatment and examination. Sterilization procedures used in dentistry should be simple, effective and of relatively short duration so that there is a readily available supply of sterile instruments and other materials. Disposal of waste and other biohazard materials should also be properly executed.

BIBLIOGRAPHY• STURDEVANT’S ART AND SCIENCE OF OPERATIVE DENTISTRY – 5TH

EDITION • CLINICAL OPERATIVE DENTISTRY –PRINCIPLES AND PRACTICE

THANK YOU !