Dept. Of Conservative Dentistry & Endodontics

NORTH BENGAL DENTAL COLLEGE & HOSPITAL

Sterilization Of Operative & Endodontic Instruments

Sterilization of Instruments With the whole world

looking at eradication of existing infectious diseases & preventing any new infections,sterilization of instruments is significant to ensure optimal patient care.

Today the universal norm is if you can sterilize an instrument,sterilize it,otherwise dispose it off.

Definitions:Sterilization: Process by which an articles, surface or medium is freed of all microorganism either in vegetative or spore form.Disinfection : Process which reduces the number of viable microorganism to an acceptable level but may not inactivate some virus and bacterial spores.Antiseptic : Chemical which can be safely applied to skin or mucus membrane surfaces and used for preventing infection by inhibiting growth of bacteria.Cross infection control :Is the sum total of all the measures taken to prevent subsequent infection.

STERILIZATION

Most instruments contact mucosa or penetrate oral tissues, it is essential that reused instruments be thoroughly cleaned and sterilized by accepted method that can be routinely tested and monitored.

Infection control measures in dentistry are most vital for mutual health safety of patient and health care professionals.

Instrument processing Contaminated instruments can

transmit infections between patients, correct reprocessing of instruments between each patient use is essential

Steps Involved Presoaking Cleaning Packaging Sterilization Drying or cooling

Categories of instruments Spaulding’s Classification

Presoaking: Most disinfectants do not act in the

presence of debris, so they should be removed. It is easier to remove the debris before it dries.

Placing the instrument in a presoak solution until time is available for full cleaning prevents drying and begins to dissolve or soften the debris.

Presoak solutions used are detergents, enzymes, phenols, quaternary ammonium compounds.

Cleaning:All items to be sterilized must be properly

cleaned first to reduces bio-burdenUltrasonic cleaners These are safest and most efficient ways

to clean instruments Ultrasonic cleaning is 9 times more

effective than hand cleaning An ultrasonic cleaning device provides

fast and thorough cleaning without damage to instruments

Ultrasonic cleaners

Instrument ContainmentCloth packs, wraps, or plastic bags are

suitable for instrument containment if they are compatible with the method and temperature of sterilization.

Various kinds of instrument trays and cassettes are manufactured to contain the instruments at chairside, and they can be placed in an ultrasonic cleaner, rinsed, and packaged ready for sterilization.

Selection of packaging materialsMethod of sterilization

Packaging materials

Steam Paper / Plastic pouches / Wrapped cassettes / Thin cloth

Chemical vapour Paper wrap / Paper peel pouches

Dry heat Nylon plastic tubing / Sterilization paper wrap / Foil

METHODS OF STERILIZATION

Though there are many methods of sterilization, the accepted methods of sterilization in our dental practices are:

i. Steam pressure sterilization (AUTOCLAVE)

ii. Chemical vapor pressure sterilization (CHEMICLAVE)

iii. Dry heat sterilization (DRYCLAVE)

iv. Ethylene oxide sterilization (ETOX)

Others- -BOILING WATER -IONIZING RADIATION

AUTOCLAVE • Sterilization with STEAM UNDER

PRESSURE• Time required at 1210 C is 15 mins at 15 lbs of pressure.

Advantages• Rapid and effective • Effective for sterilizing cloth

surgical packs and towel packs

Disadvantages• Items sensitive to heat cannot be

sterilized• It tends to corrode carbon steel

burs and instruments

Sterilization Monitoring Types of Indicators

Physical Routine observations of dials

/gauges indicating time ,temperature &

pressure Chemical Color change – strips or tapes

Biological (spore tests) Bacillus stereothermophilus ( steam or chemiclave )

Bacillus subtilus (dry heat )

Sterilization Of Burs In Autoclaves

Burs can be protected by keeping them submerged in a small amount of 2% sodium nitrite solution.

Prepare fresh sodium nitrite solution by adding 20gms of crystal to 1 liter of water and place it in a perforated beaker containing burs.

The solution should be above the burs by approximately 1cm

Handpieces sterilization: The internal surfaces of handpieces become contaminated with blood & debris,but limited access to internal surfaces limits its cleaning & disinfection,thus,surface disinfection is not adequate. Hand piece must be first cleaned & then sterilize after each patient.Cleaning can be done by using water & detergent or wiping the handpiece using a suitable disinfectant like alcohol (Fig.11.11).Lubricate the handpiece prior to sterilization (Fig.11.12) & finally sterilize it by autoclaving.

The handpiece which are not autoclavable should be treated by a disinfection regimen.For this,wrap the handpiece in gauze soaked with disinfectant & keep it in a sealed plastic bag for a specific time.

Steam sterilization (Autoclave):Temperature & pressure settingsItems Pressure

(pound)Temperature(⁰c)

Time (mins)

Blunt instruments dressing,glass etc.

20 121 30

Rubber items

20 121 20

Liquids 20 110 20

Sterilization Recommendations:

1. It is preferable to protect the points of instruments with cotton in order to prevent bag perforation.

2. Sterilize instruments with hinges in an open position.

3. Never overfill a sterilizer.4. In a desktop autoclave,place the

bags & trays vertically & not horizontally.

5. Allow the drying cycle to finish completely.

6. All instruments that have been sterilized should be bagged prior to storage.

7. Instruments that have been bagged are considered sterilized for 4 months if the bag is intact.

8. Store sterilized instruments in a dry & low-traffic area

CHEMICLAV Sterilization by CHEMICAL VAPOR

UNDER PRESSURE • operates at 1310 C and 20 lbs of pressure.

• They have a cycle time of half an hour.

Advantages • Carbon steel and other carbon

sensitive burs, instruments and pliers are sterilized without

rust or corrosionDisadvantages• Items sensitive to elevated

temperature will be damaged• Instruments must be very lightly

packed.• Towel and heavy clothing cannot

be sterilized.

Dry Heat Sterilization Conventional dry heat

ovens:• Most common time temperature cycles

are 170°C (340°F) for 60 minutes, 160°C (320°F) for 120 minutes, and 150°C (300°F) for 150 minutes.

Recently, more rapid dry heat sterilizers (COX sterilizers) have become available; these can be operated at 370°F for 6-, 8- or 12-minute cycles

Advantages • Carbon steel instruments and burs do not

rust, corrode, or lose their temper or cutting edges if they are well dried before processing.

Disadvantages• High temperatures may damage more

heat-sensitive items such as rubber or plastic goods.

• Sterilization cycles are prolonged at lower temperatures.

Ethylene oxide sterilizationBest method of sterilization of complex

instruments and delicate materials.Automatic devices sterilize items in

several hours and operate at elevated temperature well below 1000 C

Less expensive device operates at room temperature to sterilize overnight

AdvantagesUnits with large chambers hold more

instruments or packs per cycleDisadvantagesPorous or plastic materials absorb the

gas and require aeration for 24 hours or more before it is safe for them to contact skin or tissues.

Boiling WaterBoiling water does not kill spores

and cannot sterilize instrumentsIncase of sterilizer breakdown - this

method should be followedWell cleaned items must be

completely submerged and allowed to boil at 1000 C for 10 mins

Cold sterilization: Sterilization by cold chemical solutions (quaternary ammonium compounds,ethyl alcohol,isopropyl alcohol,sporicidin etc) are not recommended for three reasons:1. The process is not effective against all

varities of microbial life.2. The length of time necessary of

sterilization is too long,a minimum of 2o minutes.

3. Cold sterilization can be incorporated into the dental sterilization protocol as a method for chair-side disinfection of noncritical instrunents & chair-side accessories & can not replace the role of steam sterilization.

Features Steam pressure sterilization

Chemi-claving

Dry heat sterilization

Ethylene oxide sterilization(ETOX)

Technique 121-134⁰c at 15-30 pounds for 15 minutes

Chemical vapour under pressure at 131⁰c at 30 pounds

Dry heat exceeding 160⁰c for 60-90 minutes

Operates at temperature below 100⁰c

Clinical recommendations

It is the most effective method for sterilizing most endodontic instruments.

Carbon steel & corrosion-sensitive instruments can be sterilized without rusting.

Currently replaced by more effective alternative techniques of sterilization.

Best way to sterilize rotary handpieces.

Techniques of sterilization

Endodontic instruments sterilization

Proper steam autoclaving reliably produced completely sterile instruments.

Salt sterilization and glutaraldehyde solutions may not be adequate sterilization methods for endodontic hand files and should not be relied on to provide completely sterile instruments

Files sterilized by autoclave and lasers were completely sterile. Those sterilized by glass bead were 90% sterile and those with glutaraldehyde were 80% sterile.

Glass bead sterilizerGlass bead (hot salt) sterilizers used to consist of hot salt or glass beads as a medium for dry heat sterilization.The temperature range employed was between 425⁰F (218⁰C) & 475⁰F (246⁰C).However,these are no longer in clinical use.

Individual instruments can be sterilized in the following ways -

Glass slab by swabbing with tincture of thimerosal, followed by a double swabbing with alcohol.

Gutta-percha cones may be kept in sterile screw capped vials containing alcohol.

To sterilize gutta-percha cone freshly removed from the box- immerse in 5.2% sodium hypochlorite for 1 min, then rinse with hydrogen peroxide and dry between 2 layers of sterile gauze.

Silver cones are sterilized by passing them through a flame 3-4 times or by immersion in hot salt sterilizer for 5 secs.

Rubber dam is sterilized by ethylene oxide.

Carbon steel instruments and burs are best sterilized by dry heat or chemiclave.

Sterilization dental cements, calcium sulphate is done by gamma radiation“Whatever is touched is contaminated”

Objectives of these document

The objectives of this document when implemented, is to control patient-to-patient infectious disease transmission, and occupational exposure of dental health care personnel (DHCP) to infectious, chemical and other hazards present/encountered during the practice of dentistry.

This document provides a framework for developing a concise yet practical curriculum in dental safety to be implemented in the didactic and clinical curriculum of undergraduate dentistry, post-graduate dentistry, and dental auxiliary programs as an integral part of educational requirements.

This document provides the framework in initial and regular periodic continuing dental education requirements and documentation of training for all active dental practitioners, including dental auxiliaries involved in patient care, as well as supervisory and educational duties as in clinical faculty.

REFERENCE

1. Grossman’s ENDODONTIC PRACTICE-13th edition

2. Sturdevant’s ART & SCIENCE OF OPERATIVE DENTISTRY-South Asian Edition

3. Text book of Operative Dentistry-NISHA GARG & AMIT GARG-2nd edition

4. www.google.com

Under the guidance of-1.Prof.Dr.Soumen Chakroborty2.Dr.Anuradha Mukherjee3.Dr.Debjyoti Karmakar4.Dr.Dwipayan Bhattacharjee5.Dr.Partha Sarathi Mandal

Thank you