Sterilization
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This document discusses sterilization methods used in dentistry. It defines sterilization as killing all microorganisms including bacterial spores. It categorizes dental clinic items as critical, semi-critical, and non-critical based on contact with tissues and describes appropriate handling for each. Critical items that cut or penetrate tissues must be sterilized after every use. Semi-critical items contacting oral tissues and operative instruments are also sterilized after each use. Non-critical surfaces are disinfected if contaminated. Common sterilization methods include autoclaving using moist heat above 100°C, dry heat sterilization above 160°C, and chemical vapor sterilization using formaldehyde gas above 132°C. Each method
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Sterilization
- 1. PRESENTED BY: DR. ANUBHUTI DENTAL INSTITUTE RIMS Sterilization
- 2. Sterilization is the killing or removal of all microorganisms, including bacterial spores which are highly resistant. Sterilization is an absolute term, i.e. the article must be sterile meaning the absence of all microorganisms.
- 4. Items Critical items Description Items that cut or penetrate soft tissues Examples needles, scalpels, surgical burs ,endodontic instruments Method of handling To be discarded whenever possible/ sterilized after every use
- 5. Dry and store Sterilization Critical items Clean
- 6. Items Semi critical Description Items that contact the oral tissue Items that are handled during treatment Examples All operative instruments , handpieces, suction tips Method of handling To be sterilized after every use
- 7. Dry and store High level disinfection or Sterilization Semi Critical items Clean
- 8. Items Non critical Description Environmental surfaces not touched during treatment Examples Chairs, floors, walls, supporting dental equipments Method of handling To be disinfected if they are contaminated
- 9. Dry and store Low level disinfection Non Critical items Clean
- 10. Instruments used in dental clinics contact mucosa or penetrate oral tissue So they must be cleaned and sterilized by accepted methods before reuse .
- 12. S T E R L I Z A T I O N HEAT MOIST DRY RADIATION NON-IONISING RADIATION IONIZING RADIATION ULTRAVIOLET RAYS FILTERATION AGENTS ACTING ON CELL MEMBRANE SURFACE ACTING AGENTS PHENOLS ORGANIC SOLVENTS AGENTS THAT DENATURES PROTEINS,ACIDS AND ALKALIES HEAVY METALS OXIDIZING AGENTS DYES ALKYLATING AGENTS PHYSICAL AGENTS CHEMICAL AGENTS
- 13. Moist heat sterilization Moist heat at Below 1000C pasteurization Moist heat at 1000C Boiling , Tyndalization Moist heat at above 1000C Autoclave
- 14. This is the more efficient method of sterilization where saturated steam is used. Works on the same principal as a pressure cooker
- 15. •Protein coagulation •Breakdown of DNA & RNA releasing low molecular weight intracellular constituents Moist heat kills microorganisms by the following mechanisms
- 16. REQUREMENTS FOR PROPER AUTOCLAVING Wrap instruments in thin cloth, paper, steam- permebable plastic or perforated cassettes
- 17. REQUREMENTS FOR PROPER AUTOCLAVING Instruments and packages must v properly arranged to allow free circulation of the pressurized steam
- 18. REQUREMENTS FOR PROPER AUTOCLAVING Use fresh distilled water for each cycle
- 19. REQUREMENTS FOR PROPER AUTOCLAVING Carbon steel instruments and burs should be dipped in a corrosion –inhibitor solution (2% sodium nitrite) before being wrapped. This will prevent corroding
- 20. Sterilization will not occur unless the autoclaves is operated at the appropriate pressure and temperature for an adequate length of time.
- 21. Sterilization cycles for autoclaves Cycle Temperatures (0C) Pressure (lbs) Time (minutes ) Standard 121 15 20 Flash 134 30 7-10
- 22. Advantages Most rapid and effective Doesn’t destroy cotton or cloth products Excellent penetration of packages Disadvantages Corrosion of carbon steel instruments Damage plastic and rubber items Dulls unprotected cutting edges
- 23. This method effectively sterilize instruments at high temperature above 1500C but more time is required to warm-up the instrument load. Dry heat sterilization /Dryclave
- 24. It’s a dry heat oven which has heated chambers to allow air to circulate by gravity flow. As its very slow in penetrating instruments packs, they must be placed at least 1 cm apart to allow the heated air to circulate
- 25. To speed up the sterilization process, mechanical convection ovens are available that circulates the air rapidly by means of fan or blower. Instruments should be wrapped lightly in aluminum foil . Paper & cloth pack should be avoided as they may char
- 26. Sterilization cycles for Dry heat oven Appratus Temperatures (0C) Time (minutes ) Conventional dry heat oven 160 90 mechanical convection ovens 320-375 6-12
- 27. Advantages Rapid cycles are possible at high temperature Burs & carbon steel instruments don’t rust if they are well dried Large load can be placed Low cost of the equipment Disadvantages Sterilization is ineffective if there is heavy instrument loading and crowding Damage plastic and rubber items At lower temperature sterilization cycles are prolonged
- 28. Sterilization by radiation NON- IONISING RADIATION I R RAYS U V Rays IONIZING RADIATION Gamma rays High energy electrons
- 29. Infra red are used for rapid mass sterilization of pre packed items such as syringes ,catheters . I R RAYS
- 30. For storage of sterilized instruments U V RAYS
- 31. They have wavelength shorter than UV light. Used for syringe ,catheter sterilization . IONIZING RADIATION
- 32. This method employs chemical vapor under pressure for sterilization Chemical vapour pressure/chemiclave
- 33. Apparatus is similar to autoclave but uses a mixture of formaldehyde, alcohol, ketone, acetone, & water
- 34. When the solution is heated under pressure it forms a gas that sterilizes instruments • Sterlizer must be pre heated before use It kills microorganisms by destroying vital protein systems • Instruments are packed in paper, muslins or semi-permeable plastic.
- 35. Advantages Will not corrode metals Rapid & efficient cycles load comes out dry Disadvantages High cost Vapor odor may be offensive & requires increased ventilation Hand piece cant be sterilized by this method
- 36. Sterilization cycles for chemiclaves Temperatures (0C) Pressure (lbs) Time (minutes ) 132 20 20
- 37. TYPES OF INSTRUMENTS AND STERLIZATION METHODS INSTRUMENTS METHOD OF STERLIZATION Stainless steel operative instruments Autoclave Endodontic instruments Autoclave Dental Handpiece Autoclave Carbon steel instruments Dry heat oven or chemiclave Dental Burs & abrasives Dry heat oven or chemiclave
- 38. •Continued…………….
- 39. Essay Discuss the various sterilization methods in dentistry Short notes Autoclave Dry heat sterlization Chemiclave Handpiece sterlization