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Sterilization and disinfection in dentistry

sterilization and disinfection in dentistry
through knowledge about the techniques with help prevent cross-infection and nosocomial infections

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Sterilization and disinfection in dentistry

  1. 1. Presented by Dr. Aishwarya Hajare 1st year post graduate student 1
  3. 3. Introduction  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. 3
  4. 4.  STERILIZATION Sterilization (or sterilisation) is a term referring to any process that eliminates or kills all forms of life and other biological agents including transmissible agents (such as fungi, bacteria, viruses, prions, spore forms, unicellular eukaryotic organisms such as Plasmodium, etc.) present in a specified region, such as a surface, a volume of fluid, medication, or in a compound such as biological culture media. ( WHO Glossary )  STERILE: Free from all living microorganisms; usually described as a probability (e.g., the probability of a surviving microorganism being 1 in 1 million).(CDC guidelines 2008) 4
  5. 5.  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).(CDC guidelines 2008)  Disinfection is a process of removing or killing most, but not all, viable organisms. MIMS-PLAYFAIR,5th 5
  6. 6.  ANTISEPSIS is the prevention of infection, usually by inhibiting the growth of bacteria in wounds or tissues  BACTERICIDAL AGENTS: Those which are able to kill bacteria.  BACTERIOSTATIC AGENTS: Only prevents the multiplication of bacteria which may however remain alive.  DECONTAMINATION: The process of rendering an article or area free of danger from contaminants, including microbial, chemical, radioactive and other hazards. 6
  7. 7. History of sterilization  Hippocrates of Cos (460-377 BC), was the first to separate medicine from philosophy and disproved the idea that disease was punishment for sin. He also advocated irrigation of wounds with wine or boiled water, foreshadowing asepsis.  Ignaz Semmelweis, an Hungarian obstetrician, advocated in 1847 the value of handwashing and fingernail scrubbing. 7
  8. 8.  In 1862, French chemist and microbiologist Louis Pasteur publishes his findings on how germs cause disease, which he later uses to develop the pasteurization process.  Joseph Lister, an English physician, reduced the mortality rate of his patients in 1867 by using a carbolic solution spray as he operated, he then used it in the wound.  Charles Chamberland, Louis Pasteur’s pupil and collaborator, developed the first pressure steam sterilizer, or autoclave in 1876. 8
  9. 9.  The research of Robert Koch and his associates in 1881 on the disinfecting properties of steam and hot air mark the beginning of the science of disinfection and sterilization. They devised the first non pressure flowing steam sterilizer.  Aesculap created the first rigid instrument container, originally made of stainless steel, in Germany. In the early 1900’s, responding to the needs of the military hospitals and aid stations, Aesculap manufactured chrome-plated containers for safe transport of sterile instruments.. 9
  11. 11.  Sunlight:- Active germicidal effect due to the combined effect of U.V and heat rays. e.g.:- river, tanks & lakes.  Drying:- 4/5ths of weight of bacterial cell consist of water and hence drying has a deleterious effect on many bacteria.  Heat :- most reliable and commonly applied way of sterilization Dry heat 11  Flaming:- Inoculating loops or wires, the tip of forceps & needles and spatulas are held in a bunsen flame till they become red hot in order to be sterilized.  Incineration :- Rapidly destroying materials such as soiled dressings, bedding, animal carcasses, pathological materials etc. PHYSICALAGENTS
  12. 12. 12 DRY HEAT Principle- - Protein denaturation. - Oxidative damage. - Toxic effects of elevated levels of electrolytes.
  13. 13. HOT AIR OVEN:-  It’s the most widely used mode of sterilization  Temp.- 160°C ( 320° F ) for 1-2 hr.  Uses :- - Glasswares like glass syringes, petridishes, flasks, pipettes & test tubes. - Surgical instruments like scalpels, scissors, forceps etc.. - Chemicals such as liquid paraffin, fats, greases, Sulphonamide, dusting powder etc. 13
  14. 14.  Precautions:- 1) Not to be overloaded. 2) Must be fitted with fans for even distribution of hot air. 3) Materials to be sterilized should be perfectly dry. 4) Rubber materials (except silicone rubber) will not withstand the temperature. 5) Allowed to cool for 2 hrs before opening the doors. 14 Advantage: Economical. Does not rust metals Easily monitored . Used for anhydrous oils & powder. Disadvantage : Hot air is bad conductor of heat hence it has less penetrating power
  15. 15. • pasteurisation of milk. • Inspissation. • Vaccine bath. • Low temperature steam formaldehyde. TEMPERATURE BELOW 100O C • Boiling • Tyndallisation • Steam sterilizer at 1000 C TEMPERATURE AT 100O C • Autoclave TEMPERATURE ABOVE 100O MOIST HEAT 15
  16. 16.  AUTOCLAVING Boiling water alone is INSUFFICIENT to kill spores and viruses water boils when its vapour pressure equals to that of surrounding atmosphere Hence, when pressure increases inside closed vessel Temperature at which water boils increases saturated steam has penetrative power When steam comes in contact with a cooler surface it condenses to water and gives up latent heat to that surface. The large reduction in volume of steam sucks in more steam to the site and the process continues till the temperature of article is raised to that of steam. 16
  17. 17. 17 AUTOCLAVE  Three major factors for effective autoclave: 1. Pressure: 15psi. 2. Temperature: 121oC 3. Time: 15 mins.  Higher temperature and pressure require shorter time for sterilisation. Pressure (psi) • 15 • 20 • 20 Temperature (°C) • 121 • 126 • 134 Time (mins) • 15 • 10 • 3
  18. 18. Types of autoclave DOWNWARD DISPLACEMENT  Also known as Gravity displacement unit.  This is because of the method of air removal in the sterilization chamber. POSITIVE PRESSURE DISPLACEMENT  It’s an improvement over downward displacement autoclave.  Steam is created in a second, separate chamber and held until the proper amount to displace all of the air in the sterilization chamber is accumulated.  The steam is then released into the sterilization chamber in a pressurized blast, forcing the air out through the drain hole and starting the sterilization process 18
  19. 19. NEGATIVE PRESSURE DISPLACEMENT  one of the most accurate types of unit available  Once the sterilization chamber door is closed, a vacuum pump removes the air.  Steam is created in a second, separate chamber.  Once the air has been completely removed from the sterilization chamber, the steam is then released into the sterilization chamber in a pressurized blast much like that of a positive pressure displacement unit.  The negative pressure displacement unit is able to achieve a high "Sterility Assurance Level" (SAL), but the system can be quite large and costly. 19
  20. 20. TRIPLE VACUUM AUTOCLAVE  A triple vacuum autoclave is set up/function in a similar fashion to a negative pressure displacement.  This is repeated three times, hence the name "triple vacuum" autoclave. This type of autoclave is suitable for all types of instruments and is very versatile 20
  21. 21. Classification of a autoclave Classification Suitable for Processing Used by N Type (Downward Displacement) Unwrapped solid instruments for immediate use. S Type (Vacuum) Items specified by the autoclave manufacturer. N.B. Eschmann units suitable for naked and single wrapped solid and hollow items. Medical Surgeries Podiatrist Tattooist Body Pierces B Type (Vacuum) Unwrapped & wrapped solid and hollow instruments. Porous loads, e.g drapes & gowns. Dentists Plastic surgeons Day surgeries 21
  22. 22. 1. Ensure complete air removal for temperature to reach 121°C. 2. Ensure loose packing in the chamber. 3. Tightly sealed materials may become dangerously pressurized causing injury when removed. 22 Considerations during autoclaving USES: Disposable syringes, Non disposable syringes, Glassware, Metal instruments, surgical dressing, Surgical instruments, Laboratory equipment, Culture media, Pharmaceutical products.
  23. 23. 23 Advantage:- Economical. Good penetration. Short cycle time. Easily monitored No special chemicals or exhaust required. Disadvantage:- Moisture retention Causes corrosion Carbon steel gets damaged Dulling of unprotected cutting edges. Destruction of heat sensitive materials.
  24. 24. Filtration helps to remove bacteria from heat labile such as sera and solutions of sugars or antibiotics used for preparation of culture media. 24 Candle Filter Sintered Glass Filters Membrane Filters Asbestos Filter
  25. 25. RADIATION 1) Non-ionising radiation:  Uses longer wavelength and lower energy. And hence lose the ability to penetrate substances, and can only be used for sterilizing surfaces  Eg. infrared radiation is used for rapid mass sterilization of prepacked items eg. Syringes, catheters.  UV radiation is used for disinfecting enclosed areas like operation theaters, laboratories. 2) Ionising radiation:  Uses short wavelength, high-intensity radiation with high penetrative power to destroy microorganisms.  This radiation can come in the form of gamma or X-rays that react with DNA resulting in a damaged cell.  Since there is no appreciable increase in the temperature, it is also known as COLD STERILIZATION.  Used for sterilizing plastics, swabs, metal foils etc. 25
  26. 26. Gamma radiation  The Nature of Gamma Radiation -A form of pure energy that is generally characterized by its deep penetration and low dose rates, Gamma Radiation effectively kills microorganisms throughout.  Benefits of Gamma Radiation include: 1. precise dosing 2. rapid processing 3. uniform dose distribution 4. system flexibility 5. dosimetric release–the immediate availability of product after processing.  Penetrating Sterilization: Even with High-Density Products Gamma Radiation is a penetrating sterilant.  Substantial Decrease in Organism Survival: Gamma Radiation kills microorganisms by attacking the DNA molecule. 26
  27. 27. ULTRASONIC and SONIC CLEANING  More effective than manual cleaning.  Removes dried serum, whole blood, plaque, zinc phosphate and polycarboxylate cements from instruments, metal surfaces and dentures.  Minimizes handling of contaminated instruments.  During cleaning, totally submerge instruments in the ultrasonic solution for 2 to 20 minutes .  Ultrasonic solution should be changed atleast once a day. 27
  28. 28. Flash sterilization  “Flash” steam sterilization was originally defined by Underwood and Perkins as sterilization of an unwrapped object at 1320C for 3 minutes at 27-28 lbs. of pressure in a gravity displacement sterilizer.  Currently, the time required for flash sterilization depends on the type of sterilizer and the type of item (i.e., porous vs non-porous items).  Uses: - Flash sterilization is considered acceptable for processing cleaned patient-care items that cannot be packaged, sterilized, and stored before use. - It also is used when there is insufficient time to sterilize an item by the preferred package method. 28
  29. 29. BIOLOGICAL CONTROLS FOR DIFFERENT STERILIZATION METHODS METHOD OF STERILIZATION BIOLOGICAL CONTROL Hot Air Oven Bacillus subtilis subsp. Niger Clostridium tetani Autoclave Bacillus stearothermophilus Filtration Serratia marcescens, Pseudomonas diminuta Ionizing Radiation Bacillus pumilis 29
  30. 30. CHEMICAL AGENTS LIQUIDS GASES • Alcohols • Aldehydes • Phenols • Halogens • Heavy Metals • Surface Active Agents • Dyes • Formaldehyde • Ethylene Oxide • Plasma 30
  31. 31.  Protein coagulation  Disruption of the cell membrane  Removal of the free sulphydryl groups  Substrate competition 31
  32. 32. CLASSIFICATION OF INSTRUMENTS Critical instruments Semi-critical Instruments Non-critical Instruments 32 Penetrate the soft tissue  Contact the bone  Enter into or contact the blood stream They should be thoroughly cleaned and heat sterilized if they are to be reused. Eg: Surgical instruments, Scalers, Scissors Surgical dental burs Scalpel blades Forceps Bone grafts  Contact the mucous membrane but will not penetrate the soft tissue Eg : Mouth mirror, impression trays, handpieces, probe, tweezers  Come into contact with intact skin Eg : X-Ray tubes, Light handles, Counter tops
  33. 33. 33
  34. 34. ALCOHOL Mechanism of Action : Denaturation of Proteins  Isopropyl alcohol  70% ethyl alcohol  Ethyl alcohol is active against the fungal spores and used to treat cabinets and incubator  Suitable for skin preparation before venepuncture Disadvantage : . Inflammable . Mucous membrane irritant. . Promotes rusting. 34 Used as a skin disinfectant
  35. 35. 35 A)Formaldehyde (formalin) In aqueous solution it acts as a bactericidal and sporicidal Active against Gram -ve bacteria, spores, viruses (HB, HIV) & fungi Aqueous soultion: Formalin(37% solution) - 10% formalin + 0.5% Na tetraborate used to clean metal instrument e.g. Endoscope, dialysis equipment. Gaseous form: Fumigation of wards/corridors/ICU’s DISADVANTAGE: Have pungent odour & irritating effect on skin & mucous membrane. ALDEHYDES
  36. 36.  High level disinfectant  Especially active against tubercle bacilli,f ungi and viruses  Less toxic than formaldehyde  Can be safely used to treat corrugated rubber anaesthetic tubes, face masks, metal instruments.  Exposure time: > 10hrs. 36 B.GLUTARALDEHYDE / CIDEX ( 2% alkaline NaHCO3)
  37. 37. PHENOLS: Acts by cell membrane damage thus releasing cell contents and causing lysis  Eg. Cresol ( LYSOL) ,chlorhexidine ( SAVLON),chloroxylenol (DETTOL)  Phenol is commonly found in mouthwashes, scrub soaps and surface disinfectants  Low efficiency disinfectant  Used for decontamination of the hospital environment, including laboratory surfaces, and noncritical medical items. 37
  38. 38. HALOGENS : A) Chlorine compounds:  Bleaching powder or hypochlorite solution mostly used disinfectant for HIV infected material.  in concentration of 0.05 or 0.5% used for surface material and instruments disinfection  Should be prepared daily because of instability of sodium hypochlorite solution  Active against bacteria, spores, fungi and viruses (HB, HIV) 38
  39. 39. B) IODOPHORS & IODINE  Active against bacteria, spores & some viruses & fungi  Suitable for skin preparation, mouthwash & as a surgical scrub (7.5% Povidone+iodine= Betadine) 39
  40. 40. SALTS  Salts of heavy metals have toxic effect on bacteria.  The salts of copper , silver and mercury are used as disinfectant. SURFACE ACTIVE AGENTS  substances which alter energy relationships at interfaces,producing a reduction of surface tension, are known as surface active agents. E.g. quaternary compounds 40
  41. 41. ETHYLENE OXIDE • Highly inflammable and in concentration more than 3% highly explosive and hence not used for fumigation of rooms • Mix with carbon dioxide or nitrogen to eliminate its explosive tendency • Effective against all types of micro-organism including viruses and spores. 41
  42. 42. RECOMMENDED CONCENTRATIONS DISINFECTANT CONCENTRATI ON Ethyl Alcohol 70% Gluteraldehyde 2% Lysol 2.5% Savlon 2% Dettol 4% Bleaching powder (Calcium hypochlorite) 14 gm in 1 L water Sodium hypocholorite 1%, 0.1% Betadine (Iodophore) 2% 42
  44. 44. The four accepted methods of sterilization in dental offices are:  Steam pressure sterilization (autoclave)  Chemical vapor pressure sterilization(chemiclave)  Dry heat sterilization(dryclave)  Ethylene oxide(ETOX) sterilization 44
  45. 45.  It is performed in a steam autoclave. For light load of instruments the time required at 121o C is 15 minutes at 15lbs of pressure. It works on principle as that of pressure cooker. Advantages: rapid and effective. Disadvantages: items sensitive Tends to rust carbon steel instruments and burs. Sterilization of burs in autoclaves. burs can be protected by keeping them submerged in small amounts of 2% sodium nitrite solution. Steam pressure sterilization(autoclave) 45
  46. 46.  Performed in a chemiclave. Operate at 131oC and 20lbs of pressure. they are similar to steam sterilizer and have cycle of 30minutes. • carbon steel and other corrosion sensitive instruments and pliers are sterilized without rust or corrosion. • items sensitive. 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. Chemical vapor pressure sterilization 46
  47. 47. Advantages 1. Carbon steel and other corrosion-sensitive instruments are said to be sterilized without rust. 2. Relatively quick turnaround time for instruments. 3. Load comes out dry. 4. Sterilization is verifiable. Disadvantages 1. Items sensitive to the elevated temperature will be damaged. Vapor odor is offensive, requires aeration. 2. Heavy cloth wrappings of surgical instruments may not be penetrated to provide sterilization. 47
  48. 48.  Conventional dry heat ovens  Short cycle, high temperature dry heat oven. They have heated chambers that allow air to circulate by gravity flow. A rapid high temperature processing that uses forced draft oven(air circulates with a fan or blower) Operate at approximately 188oC-191oC Dry heat sterilization 48
  49. 49. Advantages 1.Reasonable price 2. carbon steel instruments and burs do not rust or corrode or lose temper or cutting edges. 3. Rapid cycles possible at high temperatures Disadvantages 1.rubber and plastic materials might damage. 2. heavy load of instruments defeats sterilization. 3. Improper calibration may damage instruments 49
  50. 50. Etox sterilization is the best method for sterilizing complex instruments and delicate materials. Advantages  Operates effectively at low temperatures  Gas is extremely penetrative  Can be used for sensitive equipment like handpieces.  Sterilization is verifiable Disadvantages  Potentially mutagenic and carcinogenic.  Requires aeration chamber ,cycle time lasts hours  Usually only hospital based. Ethylene oxide sterilization 50
  51. 51. OPERATORY ASEPSIS  In the dental operatory, operatory surfaces that are repeatedly touched or soiled are best protected with disposable covers(barriers)that can be discarded after each treatment.  For dental unit trays, paper, plastic film or surgical pack wraps (paper or towels) should cover the entire tray.  Clear plastic 15-gallon waste container bags fit many chair backs , control units , and x-ray equipment.  Plastic restaurant silverware bags it suction handles and air water syringe handles. 51
  52. 52.  Gigasept which contains succindialdehyde and dimethoxytetrahydrofuran are used for disinfection of plastic and rubber materials eg: dental chair 52
  53. 53. Asepsis of surgery theaters  Fumigation is done by two methods: 1. Electric boiler method- 500 ml of formaldehyde (40%) added to distilled water in electric boiler. When the water heats fumes are generated. 2. Potassium permanganate – heat is induced by oxider action of potassium permanganate. 500ml of formaldehyde is added to potassium permanganate which reacts and generates fumes. 53
  54. 54. DENTAL RADIOGRAPHY CDC(MMWR),dec19,2003vol.52 • Contamination of working area occurs from saliva. • X-ray tube head, exposure selector and timer button are likely to get contaminated by saliva. • Precaution to be taken up : 1. Put on gloves. 2. Place the film packets and film holders in special tray. 3. Contaminated films(exposed films) to be placed in separate tray. 54
  55. 55. 4. Film holding device to be rinsed in running water to remove saliva. 5. Metallic part to be autoclaved. 6. Plastic attachments to be kept in chlorhexidine solution. 7. Wipe the x-ray tube head, exposure selector, timer button and film packets with detergents. 8. Tube can be wrapped in disposable plastics. 9. Film packets to be discarded in yellow bags. 55
  56. 56. BIOPSY SPECIMEN CDC(MMWR),dec19,2003vol.52 • Biopsy collection & transportation can also be a source of infection. • It should be kept in sturdy containers with secure lid. • Avoid contaminating the external surface of the container. • Swab used for collecting micro-organisms should be transferred slowly and carefully to the swab container. 56
  57. 57. • BIO-FILMS : CDC(MMWR),dec19,2003vol.52 • Tubes connecting hand-pieces, air/water syringe & ultrasonic scaler unit are harbor of wide range of micro-organisms. • They colonize and replicate on the inner surface of tubings. • They serve as reservoir for micro-organisms. 57
  58. 58. Following measures should be taken to prevent this : A) Anti-retraction valves : (one way flow check valve). To prevent transfer or aspiration of potentially infected material in the tubings. B) Bacterial filter : Filters to be fitted in water lines of hand-pieces & water syringes. C) Chemical Disinfectants : Tubings are flushed with disinfectants like sodium hypochlorite. D) Aspirators : Cleaned and flushed after every patient for 20 – 30 secs. To be flushed with disinfectant at the end of the day. 58
  59. 59.  Impression trays are sterilized as follows metallic - autoclave plastic – ethylene oxide  Disinfection of alginate impressions – Methods - Spraying - Immersion Iodophors, sodium hypochlorite (1:10 concentration ) , phenols, formaldehyde, glutaraldehyde. 59
  60. 60. DENTAL CASTS CDC(MMWR),dec19,2003vol.52  Spraying until wet or Immersing in a 1:10 dilution of sodium hypochlorite or an iodophor then rinse  Casts to be disinfected should be fully set (i.e. stored for at least 24 hours) 60  ADA recommends use of  Chlorine compounds  Iodophors  Combination of synthetic phenols  Glutaraldehyde.
  61. 61. • Sterilize instruments like articulators, wax knives, spatula, shade guide, acrylic bur etc. • Custom impression trays, base plates, occlusal rim and all other prosthesis must be disinfected, after construction & before use in patient. • Articulators, casts, base plates to be disinfected by 1:10 chlorine solution following each session or before returning to laboratory. • Dentures washed & soaked in sodium hypochlorite for 5 mins before delivery. 61
  62. 62. ROTARY INSTRUMENTS - BURS  Diamond and carbide burs: After use they are placed in 0.2% gluteraldehyde and sodium phenate (Eg. Sporicidin) for at least 10 minutes, cleaned with a bur brush or in an ultrasonic bath. Sterilize in an autoclave or dry heat  Steel burs: May get damaged by autoclaving. Can be sterilized by using a chemical vapor sterilizer or glass bead sterilizer at 2300C for 20-30 seconds. 62
  63. 63. ENDODONTIC INSTRUMENTS CDC(MMWR),dec19,2003vol.52 • Glass Bead or salt sterilizer is the best option, but they do not sterilize the handle. • Sterilization achieved in 10 seconds • Dry heat is used, with instruments in closed metal or perforated metal boxes. • Sterilization achieved at 218oC for 15 seconds • Gutta percha points are pre-sterilized. • Contaminated points are sterilized by 5.25% sodium hypochlorite.(1 min immersion). • Then rinse with hydrogen peroxide & dry it. 63
  64. 64. • Silver cones sterilized by passing slowly over the flame for 3-4 times. • Can also be sterilized in hot salt sterilizer. • Files to be handled with tweezer. • Glass slab is sterilized by swabbing the surface with tincture of thiomersal, followed by swabbing with alcohol. • Cement spatula is sterilized by flamming 3 or 4 times over bunsen flame. 64
  66. 66. IMPLANTS  Pre sterilized with Gamma radiation  In case the implants needs to be re-sterilized conventional sterilization techniques are not satisfactory  Steam sterilization should not be used as it results in contamination of surfaces with organic substances  Dry heat sterilization also leaves organic and inorganic surface residue  Radio frequency glow discharge technique (RFGDT) or Plasma cleaning is used.  In this, material to be cleaned is bombarded by high energetic ions formed in gas plasma in a vacuum chamber.  Removes both organic and inorganic contaminants. 66
  67. 67. Sterilization in periodontal clinic  All diagnostic instruments are sterilized by washing in korsolex and sterilized.  Periodontal instruments SHARP e.g. knives, scissors, Files Tissue holding forceps BLUNT Mouth mirrors, tweezers, artery forceps, suture holding forceps Periosteal elevator 67
  68. 68.  Sharp instruments are ideally sterilized by : conventional hot air oven by not sterilized:  Boiling  Autoclave  2% glutaraldehyde  Blunt instruments are sterilized by  Autoclave 68
  69. 69. Sutures  Sutures are pre sterilized by gamma radiation  Sutures are re- sterilized by two recommed methods are 1. Soak for a full 10 minutes completely immersed in povidone iodine 10% solution, then rinse in sterile saline/water. 2. Ethylene Oxide – gas sterilisation.  Sterilising/disinfecting by other methods (autoclaving, boiling, alcohol-soaking) are not recommended. Glutaraldehyde has been taken off the market since May 2002. It was never intended to be a suture soaking solution due to its high toxicity and the inability to ensure that all the solution is rinsed off before use 69
  70. 70. ULTRASONIC SCALERS CDC(MMWR),dec19,2003vol.52  Soak inserts in a container containing 70% isopropyl alcohol for removal of organic debris.  Rinse cleaned inserts thoroughly in warm water to remove all chemicals. As a final rinse, replace the insert into the scaler handpiece and operate the scaler for 10 seconds at the maximum water flow setting to flush out any retained chemicals  Dry inserts completely with air syringe  Package in proper wrap, bags, pouches, trays, or cassettes. Add spore tests and chemical indicators.  Ethylene Oxide is the preferred method of choice  Dry heat and chemical vapor methods of sterilization are considered ineffective methods with risk of damage to materials as per American Dental association Supplement to J.A.D.A. 8/92. 70
  71. 71. Effect of sterilization on instruments Sterilization Type of instrument Stainless steel Carbon steel Saturated steam at 250°F Amorphous substance formed near cutting edge; no dulling. Dulling and oxidation of cutting surfaces Formalin-alcohol vapor at 270°F Cracking of wire edge; no dulling. Some oxidation of surfaces; no dulling. Dry heat at 320°F Chipping of wire edge; no dulling. No visual change. Dry heat at 340°F Chipping of wire edge; no dulling. No visual change Effects of Sterilization on Periodontal Instruments Roger B. Parkes,* and Robert A. Kolstadf Accepted for publication 31 August 1981 71
  72. 72. Recent advances in sterilization and disinfection  Various new methods of sterilization are under investigation and development.  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  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. 72
  73. 73. Plasma Sterilization  Plasma is basically ionized gas. When you apply an electric field to a gas, it gets ionized into electrons and ions.  Plasma is usually comprised of UV photons, ions, electrons and neutrals.  A plasma is a quasi-neutral collection capable of collective behavior  Their combined photolytic, chemical and electric action efficiently kills most micro-organisms.
  74. 74. Ozone  Ozone sterilization is the newest low-temperature sterilization method recently introduced in the US and is suitable for many heat sensitive and moisture sensitive or moisture stable medical devices  Ozone sterilization is compatible with stainless steel instruments.  Ozone Parameters • The cycle time is approximately 4.5 hours, at a temperature of 850F – 940F. 74
  75. 75. Newer Disinfectants  Persistent antimicrobial-drug coating that can be applied to inanimate and animate objects containing silver (Surfacine)  A high-level disinfectant with reduced exposure time (ortho- phthalaldehyde)  An antimicrobial drug that can be applied to animate and inanimate objects (superoxidized water)
  77. 77. BASIC CONCEPT OF INFECTION CONTROL  Prevent spread of infection from the Clinician to the patient  Prevent the spread of infection from the Patient to the Clinician  Prevent the spread of infection from one patient to another 77 Patient Operator Other personnel67
  78. 78.  For routine dental examination procedures, hand washing is achieved by using either a plain or antimicrobial soap and water.  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.  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. 78
  79. 79. 79
  80. 80. 80
  81. 81. 81
  82. 82.  Hegde et al in their study stated that the bar soap under the "in use" condition is a reservoir of microorganisms and washing hands with such a soap may lead to spread of infection. (Microbial contamination of "in use" bar soaps in dental clinics. Indian J Dent Res 2006;17:70-3) 82 67
  83. 83. Methods of hand drying 83
  85. 85. Masks  Types: 1. Surgical masks (required to have fluid-resistant properties). 1. Procedure/isolation masks  Made up from a melt blown placed between non-woven fabric Layers of a Mask 1. an outer layer 2. a microfiber middle layer - filter large wearer-generated particles 3. a soft, absorbent inner layer - absorbs moisture.  Available in 2 sizes: regular and petite. 85
  86. 86. N95 PARTICULATE RESPIRATOR  National Institute for Occupational Safety and Health (NIOSH) introduced a rating system which identifies the abilities of respirators to remove the most difficult particles to filter, referred to as the most penetrating particle size (MPPS), which is 0.3µm in size.  The “N” means “Not resistant to oil”.  N95: captures at least 95% of particles at MPPS.  N99: captures 99% of particles at MPPS.  N100: captures 99.97% of particles at MPPS. 86
  87. 87. When should I wear an N95 respirator? N95 particulate respirator 87
  88. 88. Eye wear  CAUSES OF EYE DAMAGE: 1. Aerosols and spatter may transmit infection 2. Sharp debris projected from mouth while using air turbine handpiece, ultrasonic scaler may cause eye injury. 3. Injuries to eyes of patients caused by sharp instruments especially in supine position 88
  89. 89. Over garments Gown type Situation and Rationale Cotton/linen, reusable or disposable, long- sleeved isolation gowns Use if contamination of uniform or clothing is likely or anticipated Fluid resistant isolation gown or plastic apron over isolation gown Use if contamination of uniform or clothing from significant volumes of blood or body fluids is likely or anticipated (fluids may wick through non-fluid resistant reusable or disposable isolation gowns) Fluid impervious gowns e.g., Gortex® Use if extended contact or large volume exposure (e.g., large volume blood loss during resuscitation of MVA victim or surgical assist)89
  90. 90. Footwear  Most hospitals have their own policies regarding footwear.  Footwear with open heels and/or holes across the top can increase the risk of harm to the person wearing them due to more direct exposure to blood/body fluids or of sharps being dropped for examples. 90
  91. 91. OCCUPATIONALLY ACQUIRED INFECTIONS  HIV : 0.3%  Hepatitis C : 1.8%  Hepatitis B (HBeAg +ve) : 30%  Occupational exposures that may result in HIV, HBV, or HCV transmission include needlestick and other sharps injuries; direct inoculation of virus into cutaneous scratches, skin lesions, abrasions, or burns; and inoculation of virus onto mucosal surfaces of the eyes, nose, or mouth through accidental splashes  All health care professionals should be immunized against Hepatitis A, Hepatitis B, Varicella, MMR, DPT, Rubeola, Meningitis, Polio, Influenza, Tetanus, Diptheria, Rubella. 91 67
  92. 92. Post exposure prophylaxis-HIV  Wound care:  Clean wounds with soap and water  Flush mucous membrane with water.  No evidence of benefit for: – application of antiseptics or disinfectants – squeezing puncture sites  Chemoprophylaxis  Initiating occupational 4 week regimen of PEP (zidovudine+ lamivudine+nevirapine)as soon as possible, ideally within 2 hours of exposure.  HIV- antibody testing should be performed for atleast 6 months post exposure 9267
  93. 93. HIV Infection Control (OSHA regulations) • Measures at the time of Surgery : • Proper hand washing. • Surgical attire for operation theater. • Cover the operation table with waterproof & disposable sheet. • Patient to be posted at the end of the operation list. • Staff with laceration or abrasion on their hands are excluded from the theatre. 93
  94. 94. • Number of staff member to be kept minimum. • Separate members outside the operation theater for fetching the drugs, equipments etc. • Disposable foot covers, caps, mask, plastic gowns and protective eye wear. • Wearing of double gloves. • Face mask or cap, if contaminated with splatter of blood, should be replaced immediately. • Scissors & diathermy should be used instead of blade or scalpels. 94
  95. 95. • Sharp instruments not to be handed directly, but to be delivered via kidney tray. • Patient allowed to recover in operation theater instead of recovery room and directly transferred to ward. • In case of spillage of blood or body fluid, it should be moped up using gloves and old linen/paper towel or news paper. • Sent for incineration in plastic bag. • Area to be covered with 1% sodium Hypochlorite. • Floor is wiped with soap and water followed by 1% sodium hypochlorite. 95
  96. 96. • Gloves removed at last after removing mask, cap and gowns. • All sharp instruments kept in puncture proof plastic container. • Proper labeling done & sent for incineration. • Needles to be capped before shredding. • Non sharp waste kept in large plastic bag, labeled and sent for incineration. • Reusable instruments autoclaved. • Then washed with soap and water. • Re-autoclaved. 96
  97. 97. • Non-autoclavable instruments immersed in 2% glutaraldehyde solution for 1 hour. • Then cleaned with warm water and detergents. • Again soaked in glutaraldehyde for 3 hours. • Suction bottle should contain 30 ml of 2% glutaraldehyde or 60 ml of 1% sodium hypochlorite. • It is carefully emptied out, rinsed and autoclaved after surgery. • Ventilator tubes rinsed in running tap water and immersed in 2% glutaraldehyde for 2 hours. 97
  98. 98. • Laboratory specimen placed in 10 % formalin jar, with tight leak proof cork. • It is kept in a bag and tightly closed and sealed, before transportation to laboratory. • Operating table, floor and walls to be thoroughly cleaned with 1% sodium hypochlorite. • Equipments or surfaces that cannot be easily disinfected are covered with aluminium foil or disposable plastic covers during surgery. 98
  99. 99. • Measures for Health Care workers (OSHA regulations) A proper staff education and training. Vaccination of all employees. • Universal precautions to be observed. • Proper hand washing. • Careful handling of sharp objects & instruments. • Proper sterilization, disinfection or disposal of instruments after use. • Use of gloves, mask, gowns etc. 99
  100. 100. PRINCIPLES AND PROCEDURES FOR HANDLING AND CLEANING INSTRUMENTS AFTER TREATMENT  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.  Used instruments are commonly placed in an anti microbial solution as this softens and loosens debris.  Next, move the instruments or basket of instruments into an ultrasonic cleaning device, rinse them, and then carefully inspect the instruments for debris.  instruments likely to rust , dip into a rust inhibitor solution. Drain & dry instruments with absorbent towel. 100
  101. 101. 101
  102. 102. INSTRUMENT PROCESSING ADA guidelines for sterilization 102
  103. 103. Effect of sterilization on instruments Sterilization Type of instrument Stainless steel Carbon steel Saturated steam at 250°F Amorphous substance formed near cutting edge; no dulling. Dulling and oxidation of cutting surfaces Formalin-alcohol vapor at 270°F Cracking of wire edge; no dulling. Some oxidation of surfaces; no dulling. Dry heat at 320°F Chipping of wire edge; no dulling. No visual change. Dry heat at 340°F Chipping of wire edge; no dulling. No visual change Effects of Sterilization on Periodontal Instruments Roger B. Parkes,* and Robert A. Kolstadf Accepted for publication 31 August 1981 103
  104. 104. • Divided into two categories : A) Bio-hazardous materials. B) Non-bio-hazardous materials. A) Bio-hazardous materials consist of waste materials : – 1. Soaked with blood or other body secretions. – 2. Capable of causing infectious disease. – 3. Having a poisonous effect. – 4. Human tissue removed during surgery. – 5. Teeth and associated tissues. – 6. Gloves. 104 Waste management
  105. 105. • B) Non-bio-hazardous materials consist of waste materials : – 1. Matrix bands. – 2. Masks, caps, gloves, patient’s napkin’s. – 3. Impression materials. – 4. X- ray packets & surface covers. 105
  106. 106. Waste Management  Categories of bio-medical waste in india Options Waste category Category 1 Human anatomical waste(tissues ,organs,body parts) Category 2 Animal waste Category 3 Microbiology and biotechnology waste Category 4 Waste sharps (needles,syringe,sca lpels…) Category 5 Discarded medicine and cytotoxic drugs 10667
  107. 107. Waste Management Category 6 Solid waste(items contaminated with blood and fluid including cotton dressing….) Category 7 Solid waste (waste generated from disposable items ) Category 8 Liquid waste(waste generated from laboratory and washing cleaning …) Category 9 Incineration ash Category 10 Chemicals used in production of biological, chemical used in disinfection 10767
  108. 108. COLOUR CODES COLOUR TYPE OF CONTAINER WASTE CATEGORY TREATMENT OPTIONS YELLOW PLASTIC BAGS Human and animal wastes, Microbial and Biological wastes and soiled Wastes, eg. human tissues, body parts, organs, lab cultures, specimens, items contaminated with blood Incineration, deep burial RED DISINFECTED CONTAINER/PLAS TIC BAGS Microbiological and Biological wastes, Soiled wastes, Solid waste, eg. Disposable items like catheters, IV Autoclave, microwave, chemical burial 108
  109. 109. COLOUR CODE TYPE OF CONTAINER WASTE CATEGORY TREATMENT OPTIONS BLUE/WHITE TRANSPARENT PLASTIC BAG,PUNCTURE PROOF CONTAINER Waste sharps and solid waste, eg. .Sharps, needles , scalpels, disposable items like catheter, IV set etc Autoclave/ Microwave / Chemical Treatment Destructio n BLACK PLASTIC BAG Discarded medicines, incinerated ashes, chemicals used for disinfection etc. DISPOSAL IN SECURED LAND FILLS 109
  110. 110. CONCLUSION  A steady increase in the serious transmissible diseases over the last few decades have created a 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.  The dental health care provider has to follow high standards of infection control for the safety of the patients and the dental health care workers 11067
  111. 111. References  Texbook of microbiology by Prof. CP Baveja.(3rd edition)  Operative dentistry chp- infection control by Studervant.(4th edition)  Essentials of preventive and community dentistry Soben peter (3rd edition)  Textbook of clinical periodontology, Newman, Takei, Carranza, 11th edition.  WHO glossary  Article on Sterilization of Suture material by Ingrid Cox dated 2004 17(50) from Community Eye Health Journal.  Article on effects of sterilisation on periodontal instruments by Roger B. Parkes and Robert A. Kolstadf Accepted for publication 31 August 1981 Journ Periodont  Article on recent advances in sterilization by William A.Rutala and David Weber( Emerging Inectious Diseases 111
  112. 112.  Sterilization and disinfection of dental instruments by ADA  Disinfection & sterilization of dental instruments TB MED 266, 1995  CDC, guidelines for disinfection & sterilization in health care facilities 2008.  Infection prevention and control, college of respiratory therapists Ontario, june 2011  New CDC guidelines for selected infection control procedures, chris miller.  CDC guidelines for infection control in dental health care settings, Dec19, 2003/vol.52.  Sterilization of ultrasonic inserts 112

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sterilization and disinfection in dentistry through knowledge about the techniques with help prevent cross-infection and nosocomial infections


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