STERILIZATION-PRINCIPLES OF STERILIZATION
- 1. Principles of Sterilization and Disinfection DR LEKSHMI S NAIR 1ST MDS
- 2. CONTENT INTRODUCTION TERMINOLOGIES HISTORY METHOD OF STERILIZATION STERILIZING AGENTS RECENT ADVANCES IN STERLIZATION STERLIZATION IN DENTISTRY INFECTION CONTROL INFECTION CONTROL AS PER COVID PROTOCOL WASTE MANAGEMENT CONCLUSION REFRENCES
- 3. INTRODUCTION
- 4. STERILIZATION- Validated process used to render a product free of all forms of viable microorganism. In a sterilization process, the presence of microorganism on any individual item can be expressed in terms of probability. Although this probability can be reduced to a very low number it can never be reduced to zero.(CDC glossary 2008) TERMINOLOGIES
- 5. DISINFECTION-Thermal or chemical destruction of pathogenic and other types of microorganisms. Disinfection is less lethal than sterilization because it destroys most recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores).(CDC glossary 2008) High-level disinfectant Intermediate-level disinfectant Low-level disinfectant
- 6. Decontamination-According to OSHA, “the use of physical or chemical means to remove, inactivate, or destroy blood borne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal”. In health-care facilities, the term generally refers to all pathogenic organisms. Cleaning-removal, usually with detergent and water or enzyme cleaner and water, of adherent visible soil, blood, protein substances, microorganisms and other debris from the surfaces, crevices, serrations, joints, and lumens of instruments, devices, and equipment by a manual or mechanical process that prepares the items for safe handling and/or further decontamination.
- 7. Antiseptic-Substance that prevents or arrests the growth or action of microorganisms by inhibiting their activity or by destroying them. The term is used especially for preparations applied topically to living tissue.(e.g.- chlorhexidine, povidone iodine, hydrogen peroxide) Germicide-Agent that destroys microorganisms, especially pathogenic organisms.
- 8. HISTORY • 3000 BC-Tar ,pitch, resins were used as antiseptics by Egyptians in embalming bodies • 300 BC – Hippocrates kept wounds clean by using boiled water and wine for disinfection • 1800s heat sterilization was introduced • 1885- Gaston Poupinel introduced 1st dry heat sterilization device which was being used in many hospital
- 9. • 1860-Louis Pasteur French chemist and microbiologist gave germ theory and later developed the method of pasteurization • 1867- Jospeh Lister “Father of Antiseptic Surgery”. Used carbolic acid solution to disinfect operating area
- 10. • 1879- Robert Koch demonstrate the usefulness of steam for sterilizing surgical instruments and dressings • 1879- Charles Chamberland a French microbiologist developed the Chamberland filter which led to the invention of autoclave device
- 11. METHODS OF STERLIZATION AND DISINFECTION PHYSICAL CHEMICAL SUNLIGHT HEAT RADIATION FILTRATION DRY HEAT MOIST HEAT NON IONIZATION IONIZATION EARHTENWARE ASBESTOS SINTERED GLASS MEMBRANE LIQUID GASEEOUS INCINERTION FLAMING RED HEAT HOT AIR OVEN BELOW100 AT 100 ABOVE 100 ALCOHOL ALDEHYDE HALOGEN PHENOLS ETHYLENE OXIDE FORMALDEHYDE PLASMA
- 12. PHYSICAL AGENTS 1.HEAT- The most reliable method of sterilization. Factors influencing heat sterilization • Nature of heat • Time and temperature • Number of micro organism • Characteristics of organism • Type of material to be sterilized Dry heat – Mechanism of action can be due to • Protein denaturation • Oxidative damage • Toxic effect of elevated electrolyte levels 1. Flaming 2. Red heat 3. Incineration 4. Hot air oven
- 13. • PRINCIPLE- Works on the principle of conduction. The heat is absorbed by the outer surface of the item and then moves to the centre, layer by layer. The item will eventually reach the temperature required for sterilization. Most damage is done by oxidizing molecules. Essential cell constituents are destroyed and organisms die. • Most common temperatures used- 170 for 30mins 160 for 60mins 150 fro 110mins PARTS OF HOT AIR OVEN HOT AIR OVEN
- 14. • Precautions to be taken-Not be overloaded Not be crowded Glassware should be wrapped and dry Cooled slowly before opening • Materials sterilised-glassware, swabs, liquid paraffin, dusting powder, fat and grease, scissors, scalpels, glass syringes • Quality Controls- Chemical- Browne’s tube Physical-Thermocouple Biological-paper strips containing 106 spores of Clostridium tetani
- 15. 1. Temperature below 1000C • Pasteurisation- Usually used for food like milk. Non sporing bacteria like mycobacterium, salmonella destroyed • Vaccine Bath- 600C for 1 hour Water bath used to sterilize vaccines 2. At 1000C • Boiling- Means of disinfection. Not used for surgical instruments • Tyndallisation/intermittent sterilization – Steam at atmospheric pressure used to sterilize culture media 3. Above 1000C • Autoclave Moist Heat
- 16. Autoclave Steam under pressure used. Principle- • Water boils when vapour pressure equals atmospheric pressure. • When pressure inside closed vessel increases the temperature at which water boils increases. • The steam produced condenses to water on cool surfaces giving out latent heat. • Steam has high penetrative power. • Process continues till temperature of surfaces rises to that of steam.
- 17. Common operating parameters- TEMPERATURE TIME PRESSURE 121 15mins 15psi 126 10mins 20psi 130 3min 25psi Several steps involved in sterilization process • Instrument reception • Pre cleaning disinfection • Pre sterilization cleaning • Packing • Autoclaving • Drying • Storage
- 19. Types of autoclaves useful for dental surgeries 1. Displacement autoclave-Utilize superheated steam to displace air downwards and out of the chamber Used for sterilization of unwrapped instruments. Typically small bench units 2. Vacuum autoclaves - Pump air from the chamber before entry of super heated steam Preferred for porous load. Larger and more costly units
- 20. Advantage • Absolute sterility • Short cycle time • Loose or bagged instruments are acceptable • Good penetration of steam • Ability to process a variety of material • Readily monitored Disadvantage • Corrosion of materials • Cutting edges may dull • Damage heat sensitive materials • Wrapped items remain wet without drying cycle • Wrapped items need longer cycle
- 21. Errors in effective use of autoclave • Human error- Inadequate cleaning, improper packaging, over loading, incorrect choice of cycle, items not dried after, improper storage, manual alteration of cycle • Equipment factors-Clogged filters, leaking door gaskets, faulty timer, out of calibration of sensors, low water level, controller malfunction Quality control Physical- Monitoring gauges and Thermocouples Chemical- Browne’s tube Biological- Strips or tapes of Bacillius stearothermophillus
- 22. Filtration Help remove bacteria from heat labile liquids ASBESTOS FILTER SINTERED GLASS FILTER CANDLE FILTER MEMBRANE FILTER
- 23. Radiation 2 types radiation • Ionising • Non ionising • Ionising radiation- Gamma, X ray o Short wavelength o Cold sterilization ,as no temperature increase o High penetrating power damages DNA and other cell components o Sterilization of implants ,sutures ,swabs, plastics
- 24. • Nonionizing- UV radiation ,Infrared • UV has bactericidal action at 240-280nm o Long wavelength o Low penetrating power o Germicidal radiation o Breaks down chemical bond and disrupts DNA,RNA and proteins o Used for surface sterilization, syringes, catheters, operating rooms
- 25. Ultrasonic and sonic cleaning • Vibrations used fro cleaning instruments • More effective than manual cleaning • Used before autoclaving • Removes plaque, calculus and other dental materials from the surfaces of instruments • Minimises handling of contaminated instrument • Instruments are submerged in ultrasonic solution
- 26. Chemical agents Ideal requisites • Wide spectrum of action • Active in the presence of organic material • Speedy action • Effective in acid and alkaline environment • High penetrating power • Stable
- 27. • Compatible • Non irritating and non allergic • Non toxic • Inexpensive Methods of action • Protein coagulation • Disruption of cell membrane • Remove free sulfhydryl groups • Substrate competition
- 28. ALCOHOL • Commonly used ethyl alcohol and isopropyl alcohol • Acts by denaturing proteins Used as • Skin antiseptic • Surface disinfectant • Hand sanitizer Disadvantages • Inflammable • Irritant • Promotes rusting
- 29. ALDEHYDE FORMALDEHYDE • Aqueous and gaseous form • Bactericidal and sporecidal Liquid- • 37% formaldehyde solution, water based- FORMALIN Mode of action- • Inactivates microorganism by alkylating the amino and sulfhydryl groups of proteins and ring nitrogen atoms of purine bases , alter RNA ,DNA ,protein synthesis
- 30. Gaseous-Fumigation • 150gms of KMNO4 in 280 ml of formalin for 1000cu. feet room volume • Operation theatres labs and wards • Doors should be left sealed for 48hrs. Disadvantage • Can be fatal to health • Skin irritation and respiratory disorders on long term use. GLUTARALDEHYDE • 2.4% Cidex • Less toxic • High level disinfectant and chemical sterilant
- 31. HALOGEN Chlorine Compounds • Hypochlorite, sodium hypochlorite(0.5%-1%) • Most commonly used for canal irrigation and antiseptic • Antimicrobial activity by reacting with fatty acid and amino acids • Unaffected by water hardness and do not leave toxic residue • Should be prepare daily because of its instability
- 32. Iodine • Povidone iodine • Antimicrobial action • Used as mouth rinse (2%,5%),surgical scrub(7.5%,10%), antiseptic for wound dressing • Iodine penetrates cell membranes and interact with proteins, nucleotides and fatty acids
- 33. PHENOL • Used as germicide • Penetrating and disrupting cell wall and precipitating cell protein • Used as surface disinfectants and for non critical item • LISTERINE Mouth was contains phenolic compounds
- 34. HYDROGEN PEROXIDE • Germicidal effect • Active against wide range of organisms • Destructive hydroxyl free radicals released that attacks DNA and other cell components • 3% used as canal irrigant, flushing debris,antiseptic ETHYLENE OXIDE GAS • Reacts with DNA and RNA and has alkylating effect • Highly inflammable and explosive long cycle time, cost, potential occupational hazard • Used to sterilize critical and semi critical items that are heat sensitive and cannot he sterilized by heat
- 35. RECENT ADVANCES Hydrogen Peroxide Gas Plasma • Generated in a closed chamber under deep vacuum using radiofrequency or microwave to excite gas molecules and produce large molecules which are in the form for free radicles • Free radicals interact with essential cell components and disrupt them • Used for materials that are not heat stable, plastics, electrical devices corrosion susceptible metal alloys OZONE • Low temperature sterilization method • Stainless steel instruments compatible • Cycle time 4.5 hours
- 36. Factors Affecting the Efficacy of Disinfection and Sterilization • Number and location of microorganisms • Innate resistance • Concentration and potency of disinfectant • Physical and chemical factors • Organic and inorganic matters • Duration of exposure • Biofilms
- 37. Sterilization And Disinfection In Dental Clinics • To determine the type of method used for disinfection or sterilization Spaulding classified the instruments into CRITICAL • Those that entre tissue and vascular system • Infection transmission maximum • Heat sterilization followed • Surgical instruments, scalpels, scaler, implants SEMI-CRITICAL • Come in contact with mucous membrane and non intact skin • If heat stable sterilized by heat and if heat sensitive high level disinfectant used • Dental mouth mirror, amalgam condenser, impression trays, dental hand pieces NON CRITICAL • Contact intact skin • Chances of transmitting infection least • Disposable barrier protection can be used • Radiograph head, blood pressure cuff, pulse oximeter, other environmental surfaces
- 38. STERILIZATION OF DENTAL OPRATORY 1. DENTAL CHAIR • Control unit should be covered by disposable plastic covers and disinfected using formaldehyde or alcohol based disinfectant • Tubes connecting water pipes , air and water syringes and scaler units also serve as reservoir for microorganisms • Water units should be maintained and monitored • Discharge water and air syringe for a minimum for 20-30 seconds after each patients • Use anti retraction valve or one way flow check valve to prevent backflow • Use bacterial filters and chemical disinfection
- 39. 2. DENTAL RADIOGRAPH • Gloves should be worn • Heat tolerant accessories available should be heat sterilized • Films should be dried and disposable towels should be used • Digital sensors can be disinfected and plastic barriers can be used • Plastic attachments disinfected using chlorhexidine solution • X ray tube and head buttons cleaned with detergent
- 40. 3.ULTRASONIC SCALERS • Hand piece is disinfected • The inserts are removed and cleaned of all debris with water and then disinfected and places in cassettes or pouched and autoclaves 5.ROTARY INSTRUMENT • Diamond carbide bur-0.2% Gluteraldehyde and sodium phenate for 10mins • Autoclave or dry heat • Steel burs- Glass bead sterilizer 230 degree for 20-30 mins
- 41. 4.DENTAL HANDPIECE CONTAMINATION CONTROL • Run under water • Scrub • Clean fibre optic surface with alcohol • Lubricate and run hand piece • Place in sterilization pouch • Autoclave
- 42. INFECTION CONTROL • Transmission of infection within the dental clinic can occur from • Infection control begins at taking a proper case history and making sure all protective measures are in place • Protective coverings, hand protection, immunisation of operator, protective shields, instrument sterilization helps control infections PATIENT OPERATOR OTHER PERSONAL
- 44. GLOVES AND GLOVING TECHNIQUE
- 48. Principles And Procedure For Handling And Cleaning Instruments After Treatment • Receiving • Cleaning • Decontamination • Preparation • Packaging • Sterilization • Storage
- 49. INFECTION CONTROL AS PER COVID PROTOCOL Zones and Dental clinics • Containment zone- Closed • Red zone-Emergency procedure • Orange and green- Emergency and urgent treatment consults Phase1- Preparatory Phase Doctors and other health care workers • Testing and prophylaxis should be taken before resuming work • Proper training should be given, use of N95 masks, proper donning and doffing of PPE, hand hygiene should be practiced
- 50. Dental clinics • Ventilation and air circulation should be checked • Fan should not be used while performing procedure • Window ac filter should be cleaned regularly • Strong exhaust should be used • Visual alters and instructions should be displayed • Sanitizer and masks should be provide to the patient
- 51. • Distant waiting chairs should be placed- 1m apart • Consultation should be based on appointments spaced out properly • Cashless or contactless payment • Changing area for PPE donning and doffing • Dedicated areas for sterilization
- 52. Equipment and instruments • Fumigation system in place • High volume suction • Hand piece with anti retraction valve • Indoor air cleaning system • Environmental surfaces disinfected using 1%sodium hypochlorite for 10 mins • Delicate electronics alcohol based disinfectant used
- 53. Phase2-Implentation phase • Telconsult • Protocols to handle patients in clinic area • For consultation- 3 layered mask, face shield and gloves • For procedure- N95 and PPE used • Rubber dams should be used and practice non aerosol generating procedures • Patients draped • Patient made to rinse mouth with 10ml 0.5% povidone iodine • Patient discharge- drape removed, patient made to wash hands • Procedure and prescription recorded after doffing PPE • Disinfection done • Hand piece washed under water
- 54. • Forced ventilation using high efficiency particulate air filter • 3 way syringe run for 30-40sec and flushed with disinfectant solution • Remove water container and disinfect with 1%sodium hypochlorite, refill • Disinfect chair and auxiliary parts within 3 feet with 1% sodium hypochlorite • Fogging-hydrogen peroxide 11% solution stabilized with 0.01% silver nitrate 20% working solution prepared. 1000 ml per 100 cu feet. Time 45 mins, after procedure close room for half an hour. Phase 3- • Patient follow up • Patient contacted with 24hrs and 1 week to know if he has developed and symptoms.
- 55. WASTE MANAGEMENT • The collection ,transport , recovery and disposal of waste including the supervision of such operations and after care of disposal sites • Biomedical waste- Any waste generated during diagnosis , treatment or immunisation of human beings or animals or research activities. CLASSIFICATION • Infectious waste • Sharps • Pharmaceutical waste • Chemical waste • Heavy metal waste • Pressurized containers • Radioactive waste
- 57. CONCLUSION With the increase in number of transmissible diseases and increasing hospital acquired diseases ,the risk of infection increases for both the patient and health care workers. Hence it is important to follow high standards of infection control for the safety of the patients and the dental health care workers
- 58. REFERENCES 1. Text book of microbiology, Anantanarayan 9thed. 2. CDC Recommendations from the guidelines for infection control in dental health care settings-2003 3. CDC Guidelines of infection control in dental clinics 4. COVID19 Pandemic: What changes for dentists and oral medicine experts? A narrative review and novel approaches to infection containment, Maria Elenora Bizzoca et al, International Journal of Environmental Research and Public Health 2020,17,3793 5. WHO recommendation for hand hygiene procedure
- 59. 6. Government of India Guidelines for dental professionals in covid19 pandemic situation-2019 7. Sterilization protocols in dentistry-A review, Lakshya Rani and Dr Pradeep, Journal of Pharmaceutical Sciences and Research.vol.8(6), 2016,558-564 8. CDC guidelines for disinfection and sterilization in healthcare facilities, William A Rutala et al,2008 9. The use of autoclaves in dental surgery, N W Savage and L J Walsh, Australian Dental Journal 1995;40(3):197-200 10. Google images
Editor's Notes
- #3: LLLL
- #4: MICROORGNS PRESENT EVERY WHERE PATHOLOGICAL ORGAS RESPONSIBLE FOR CONTAMINATION infection decay Aim to remove or destroy them from materials or surfaces
- #14: hot air bad conductor of heat Inner poor conductor, outer metallic layer, heated with electricity, heating elements in the wall, fan to ensure air distribution