Basic seminar 3 sterilization and disinfection

Sterilization, disinfection and clinical dentistry go hand in hand, here is brief explanation of all the old and latest sterilization and disinfection methods in dentistry. It covers everything.

1. GOOD MORNING

2. STERILIZATION AND DISINFECTION

3. CONTENTS STERILIZATION : INTRODUCTION HISTORY DEFINITIONS AND TERMINOLOGIES PRINCIPLES AND GOALS OF STERILIZATION 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 3

4. AGENTS USED IN STERILIZATION STERILIZATION MONITORING METHODS USED FOR STERILIZATION NEWER METHODS IN STERILIZATION 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 4

5. DISINFECTION : AGENTS USED FOR DISINFECTION IDEAL REQUIREMENTS LEVELS OF DISINFECTION GENERAL RULES FOR SURFACE DISINFECTION NEWER PARADIGMS IN DISINFECTION 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 5

6. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 6 STERILIZATION

7. INTRODUCTION Microorganisms are ubiquitous since they cause contamination, infection and decay, it becomes necessary to remove or destroy them from materials or from areas. This is the object of sterilization. The method employed depends on the purpose for which it is carried out, the material which has to be sterilized and the nature of microorganisms that are to be removed or destroyed. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 7

8. HISTORY 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 8

9. Joseph Lister (1867) introduced antiseptic techniques in surgery. He d emonstrated that boiling instruments, washing hands and spraying phenol in air around the patient before surgery, reduces the incidence of post-operative infections. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 9

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11. DEFINITIONS AND TERMINOLOGIES STERILIZATION – The process by which an article, surface, or medium is freed of all living microorganisms either in vegetative or spore state . ( Ananthanarayan ) DISINFECTION – The destruction or removal of all pathogenic organisms, or organisms capable of giving rise to infection. ( Ananthanarayan ) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 11

12. DISINFECTANT – An agent that kills most pathogens but not necessarily endospores on inanimate objects. Eg : Alcohols, Aldehydes, etc. Efficacy can be classified as – High, Intermediate or Low . STERILANT - Some disinfectant will kill spores when prolonged exposure time (3-12 hrs ) and called chemical sterilant . SEPSIS - Presence of infection , infectious agent or infectious material 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 12

13. ASEPSIS - Methods which prevent contamination of wounds and other sites by ensuring that only sterile objects and fluids come in contact with them and that the risk of air borne contamination is minimized. ANTISEPTICS - Chemical agents applied to living tissues to reduce the number of micro-organisms present by inhibiting their activity or by destruction. Thus all antiseptics could be used as disinfectants but all disinfectants cannot be used as antiseptics because of toxicity. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 13

14. BIOCIDE : A substance that kills all living organisms including spores , both pathogenic and non pathogenic. BIOSTAT : An agent that prevents the growth of microorganisms but does not necessarily kill them. The removal or neutralization of biostat may allow for the regrowth of microorganisms . BACTERICIDAL AGENT : or germicides are those which are able to kill bacteria. BACTERIOSTATIC AGENT : are those which only prevent the multiplication of bacteria ; which however, may remain alive. Eg - soaps, detergents. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 14

15. DECONTAMINATION – It refers to process of rendering an article or area free of danger from contaminants, including microbial, chemical, radioactive and other hazards. CLEANING – The process which removes visible contamination, but does not necessarily destroy microorganisms. SANITIZATION - This term is sometimes used as a synonym for disinfection, particularly used with reference to food processing & catering. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 15

16. GOALS AND PRINCIPLES OF STERILIZATION GOALS Removal of microorganisms or destroy them from materials or from areas since they cause contamination, infection and decay. MICROBIOLOGY - To prevent contamination SURGERY - To maintain asepsis DRUG & FOOD - For ensuring the safety 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 16

17. PRINCIPLES All used instruments must be thoroughly cleaned. Agent must be in contact with every surface of each instrument to be sterilised. All sterilising equipments must be regularly serviced. Manufacturer’s instructions should be strictly followed. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 17

18. Sterilizaton can be divided into four stages: Pre-sterilization cleaning Packaging The Sterilization Process Aseptic storage 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 18

19. INSTRUMENT PROCESSING 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 19

20. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 20 Presterilization cleaning : It is achieved by either by Cleaning using a washer disinfector (most preferred method) Manual combined with ultrasonic cleaning Manual cleaning (the least preferred) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 20

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22. Disinfector cycle includes 5 steps: Flush Wash Rinse Thermal disinfection Drying 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 22

23. STERILIZATION MONITORING Sterilization procedures should be monitored through a combination of M echanical , Chemical and Biological techniques 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 23

24. It should be designed to evaluate the sterilizing conditions and the procedure's effectiveness. Because spores used in BIs (biological indicators) are more resistant and present in greater numbers than are the common microbial contaminants found on patient care equipment, an inactivated BI indicates that other potential pathogens in the load have also been killed. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 24 A biological indicator is the only type of monitor that provides direct evidence that sterilization process conditions are sufficient to kill spores. It uses microbes that are highly resistant to the type of sterilization process you are monitoring

25. COLOUR CHANGE STERILIZATION INDICATORS Color indicators are also included on the outside and inside of equipment sterilized in paper packages. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 25 The white stripes on the tape change to black when the appropriate conditions (temperature) have been met. Expiration dates should be printed on all equipment packs.

26. Bacillus stearothermophillus spores : Steam or chemical vapor sterilization monitoring . Bacillus subtilis spores : For dry heat or ethylene oxide gas sterilization monitoring . These spore strips are filter paper strips impregnated with spores and sealed in an envelope through which the sterilizing agent penetrates . There are no B.I. available to test chemical sterilants and disinfectants. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 26

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28. CLASSIFICATION OF AGENTS PHYSICAL AGENTS B. CHEMICAL AGENTS 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 28

29. PHYSICAL AGENTS 1 . Sunlight 2 . Drying 3 . Heat a. Dry heat -Flaming -Hot air oven 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 29

30. b. Moist heat -Temperature below 100 C (Pasteurization) - Temperature at 100 C (Boiling) -Steam at atmospheric pressure i.e. at 100 C. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 30

31. 4. Filtration -Candle filters -Asbestos filters -Sintered glass filters -Membrane filters 5 . Radiation -Nonionizing radiation -Ionizing radiation 6 . Ultrasonic and sonic vibration 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 31

32. SUNLIGHT Sunlight possesses appreciable bactericidal activity and plays an important role in the spontaneous sterilization that occurs under natural conditions . The action is primarily due to its content of Ultraviolet Rays . Semple and Grieg showed that, in India, typhoid bacilli exposed to the sun on pieces of white drill cloth were killed in 2 hours, whereas controls kept in the dark were still alive after 6 days. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 32

33. This is one of the natural methods of sterilization in cases of tanks, rivers and lakes . ADVANTAGES : Direct sunlight as in tropical countryside where it is not filtered by ozone layer and impurities in the atmosphere, has an active germicidal effect due to the combined effect of ultraviolet and heat rays. DISADVANTAGES : Many microorganisms still remain viable as active sunlight is not efficient in destroying them. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 33

34. DRYING Moisture is essential for bacterial growth. Drying therefore has a deleterious effect on most bacteria. Although, viruses and spores are unaffected by drying. Therefore , it is a very unreliable method . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 34

35. HEAT 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 35 Nature of heat Temperature & time Type of material No of micro-organisms Characteristics of organism

36. DRY HEAT Time : Temperature of exposure. FO value FO value at a particular temperature other than 121 o C is the time in minutes required to provide the lethality equivalent to that provided at 121 o C . THERMAL DEATH TIME (TDT)  is a concept used to determine how long it takes to kill a specific bacteria at a specific temperature. 5/5/2017 Basic Seminar 3 - Dr. Barkha . S. Tiwari 36

37. THERMAL DEATH POINT (TDP) The temperature at which all organisms of a culture will be killed by heat either instantaneously or within an arbitrary brief finite period. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 37 FLAMING INCINERATION HOT AIR OVEN INFRARED

38. It is used to sterilize : Bacterial inoculating loops Dental broaches Burs Scalpels, needles and cover slips 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 38

39. FLAMING A simple & effective method Tip of the instruments are held in a Bunsen flame till they become red-hot. These materials may be dipped in a disinfectant before flaming. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 39

40. INCINERATION This is an excellent method for safely destroying materials such as contaminated cloth, animal carcasses and pathologic materials. Its a high temperature dry oxidation process, that reduces organic and combustible waste to inorganic incombustible matter and results in a very significant reduction of waste-volume and weight. The process is usually selected to treat wastes that cannot be recycled, reused or disposed off in a land fill site. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 40

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42. Waste types not to be incinerated are : Pressurized gas containers Large amounts of reactive chemical wastes Silver salts and photographic or radiographic wastes Halogenated plastics such as PVC Waste with high mercury or cadmium content such as broken thermometers, used batteries and lead-lined wooden panels Sealed ampules or ampules containing heavy metals. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 42

43. TYPES OF INCINERATORS Double-chamber pyrolytic incinerators which may be especially designed to burn infectious health-care waste . Single-chamber furnaces with static grate , which should be used only if pyrolytic incinerators are not affordable. Rotary kilns operating at high temperatures , capable of causing decomposition of genotoxic substances and heat-resistant chemicals. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 43

44. HOT AIR OVEN This is the most widely used method of sterilization by dry heat. Heat does not penetrate materials easily and thus, long periods of exposure to high temperatures are necessary. Conventional dry heat ovens have heated chambers that allow air to circulate by gentle flow (gravity convention ). 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 44

45. MECHANISM OF ACTION Coagulation and oxidation of proteins. The oven is usually heated by electricity, with heating elements in the wall of the chamber. Since hot air is a bad conductor of heat its penetrating power is low. It must be fitted with a fan to ensure even distribution of air and elimination of air pockets. The material should be arranged so as to allow free circulation of air in between the objects 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 45

46. PARAMATERES : Standard exposure for 1 hour at 170 o C. TYPES : DRY HEAT OVEN TYPE OF STERILISER ( STATIC) ( 60-120 minutes at 320 F) 5/5/2017 Basic Seminar 3 - Dr. Barkha . S. Tiwari 46 The heating coils in the bottom or sides of the unit cause hot air to rise inside the chamber through natural convection

47. RAPID HEAT TRANSFER (FORCED AIR) / SHORT CYCLE HIGH TEMEPRATURE DRY HEAT OVEN 6 minutes for unwrapped instruments 12 minutes for wrapped instruments. 8 minutes for handpiece and medical kits 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 47 180 -190 o C Heated air is circulated throughout the chamber at a high velocity, permitting more rapid transfer of energy from the air to the instruments, thereby reducing the time needed for sterilization.

48. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 48 Time and temperature – recommended by Medical Research Council TEMPERATURE ( o C) HOLDING TIME (minutes) 160-169 45-50 170-179 18-20 180-189 7.5-10 190-199 1.5-3

49. INDICATIONS Glass wares (petri dishes, pipettes, flasks) Forceps Scissors Scalpels Glass syringes Swabs Pharmaceutical products e.g. Liquid (paraffin ) Test tubes and flasks should be wrapped in a paper Oils, greases, petroleum jelly 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 49

50. ADVANTAGES Effective and safe sterilization of metal instruments and mirrors It does not affect many moisture sensitive compounds. No corrosion of carbon steel instruments and burs Cost-effective DISADVANTAGES Long cycles Poor penetration Uneven heating Damage to heat sensitive items (Plastics, Rubber) Heavy loads of instruments , crowding of packs and heavy wrapping easily defeat sterilization. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 50

51. GLASS BEAD STERILIZER This method involves heat transfer device. The media used are glass beads of 1mm in diameter and a metal cup. The method employs submersion of endodontic instruments and burs into the beads. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 51

52. The beads heat up and transfer it to the metal surface in contact. Working temperature - 210º - 230ºC for 10-30 seconds Working time – 15 seconds. Pre heating time ranged from – 15 – 20 minutes . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 52

53. Disadvantage: Only working end of the file is immersed, leaving the handles still contaminated . Not suitable for hollow instruments . Larger beads – Not effective in transferring heat to endodontic instruments as large air spaces between the beads reduce efficiency of the sterilizer 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 53

54. HOT SALT STERILIZATION Similar to glass bead sterilizer More safer than glass bead sterilizer. Pre heating required . Higher temperature than glass bead sterilizer as granules are smaller so air space between granules is reduced and conductivity of heat by salt is higher. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 54

55. Larger instruments should be immersed in for 20 seconds. To sterilize instrument- immerse at least ¼ the inch below the salt’s surface and in the peripheral area of sterilizer Commercial table salt- 1 % Sodium silicoaluminate , Magnesium carbonate / Sodium carbonate used. It pours more readily and will not become fused under heat. **Pure sodium chloride- not used as high heat may cause fusion of granules. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 55

56. Salt containing dextrose not to be used as it may coalesce the granules of salt at high heat. Salt carried to the root canal – easily irrigated. Salt to be changed weekly or more often- depending on the degree of humidity. Temperature : 425 o F (218 o C) and 475 o F (246 o C). Thermometer inserted in the salt to monitor temperature. Broaches, files and reamers - 5 seconds. Absorbent points and cotton pellets - 10 seconds. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 56

57. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 57 MOIST HEAT STERILIZATION

58. STEAM IS A VERY EFFECTIVE STERILIZING AGENT SINCE IT: Liberates latent heat when it condenses to form water, potential microbial ( cidal ) activity. Contracts in volume during condensation, thus reinforcing penetration. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 58

59. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 59 Temp below 100  PASTEURISATION : 63ºC, 30 minutes (Holder method ) : 72 ºC, 15 seconds (Flash method) VACCINE BATHS : 60 ºC, 1 hour Temp at 100  BOILING STEAM AT ATMOSPHERIC PRESSURE 10-30 min Koch & Arnold’s steamer 2% NaHCO3 Tyndallisation (100 o C for 20 minutes)

60. PASTEURIZATION Developed by Louis Pasteur to prevent the spoilage of beverages. Used to reduce microbes responsible for spoilage of beer, milk, wine, juices, etc. Classic Method of Pasteurization: Milk was exposed to 65 o C for 30 minutes. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 60

61. THERE ARE 3 METHODS HOLDER METHOD It involves heating up to 62.9 C for 30 min . Although thermophilic bacteria thrive at this temperature; they are of little consequence because they cannot grow at body temperature. FLASH PASTEURIZATION This method uses a temperature of 71.6 C for 15 seconds followed by cooling to 13 C . High Temperature Short Time (Flash Modification Pasteurization (HTST): Used today . Milk is exposed to 72 o C for 15 seconds. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 61

62. Ultra High Temperature Pasteurization (UHT): Milk is treated at 140 o C for 3 seconds and then cooled very quickly in a vacuum chamber. Advantage: Milk can be stored at room temperature for several months. ULTRA- PASTEURIZATION This method uses a temperature of 82 C for 3 seconds. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 62

63. INSPISSATION Vaccines of nonsporing bacteria are heat inactivated in special vaccine baths at 60 for 1 hour. Serum or body fluids containing coaguable proteins can be sterilised by heating at 56 for 1 hour for several successive days. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 63

64. BOILING Heat at 100 o C or more at sea level kills vegetative forms of bacterial pathogens, almost all viruses, and fungi and their spores within 10 minutes or less. Denaturation of proteins. Endospores and some viruses are not destroyed this quickly. However brief boiling will kill most pathogens. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 64

65. Material should be immersed in water and boiled for 10-30 minutes but the lid of the sterilizer should not be opened. Hepatitis virus: can survive up to 30 minutes of boiling. Endospores: can survive up to 20 hours or more of boiling. Reliable sterilization with moist heat requires temperatures above that of boiling water. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 65

66. TYNDALLIZATION Also known as compressed or saturated steam. This is an inexpensive method using a Koch or Arnold steamer. Principle steam under pressure is hotter. higher the pressure the higher the temperature 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 66

67. Liquids were sterilized by this method at 100 C for 30 minutes on each of 3 successive days . Also called Fractional sterilization , because a fraction was accomplished on each day. Also called Tyndallization after its developer John Tyndall, and Intermittent sterilization because it has a stop and start operation. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 67

68. MECHNISM OF ACTION During the first day’s exposure, steam kills virtually all organisms except bacterial spores and it stimulates spores to germinate vegetative cells. During overnight incubation the cells multiply and are killed on second day. Again the material is cooled and a few remaining spores germinate only to be killed on the 3rd day. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 68 ***This method also fails because certain spores ( eg ; some anaerobes ) fail to germinate. A suitable medium for germination such as broth is required”.

69. AUTOCLAVE Moist heat in the form of pressurized steam is regarded as the most dependable method for destruction of all forms of bacterial life including spores. This method is incorporated into a device called the Autoclave . Autoclave means ‘self locking’. Over a hundred years ago, French & German microbiologists developed the autoclave. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 69

70. TYPES OF AUTOCLAVES Type N : Sterilization is achieved by passive displacement with steam. They are non- vaccum and used for non-wrapped solid instruments. Type B : They are vaccum sterilizers designed to reprocess load types such as hollow, air-retentive and packaged loads. Type S : They are specially designed to reprocess specific load types. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 70

71. PRINCIPLE Water boils when its vapour pressure equals that of the surrounding atmosphere. Hence pressure inside a closed vessel increases , thus the temperature at which water boils also increases. Saturated steam has a high penetration power. When steam comes in contact with a cooler surface, it condenses to water and gives up its latent heat to that surface. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 71

72. The large reduction in volume sucks in more steam to the area and the process continues till the temperature of the surface is raised to that of the steam. Condensed water ensure moist conditions for killing the microbes present. “LATENT HEAT EFFECT” 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 72

73. MECHANISM OF ACTION Moist heat denatures & coagulates the protein of a microbe. Higher efficiency of penetration & faster microbicidal action than dry heat. (Moist heat penetrates material much more rapidly than dry heat because water molecules conduct heat better than air). 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 73

74. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 74 2 Basic Types Horizontal / Downward displacement steriliser Vertical / Vacuum steam steriliser Small bench top autoclave at 136 C at 32 pounds for 5 minutes Porous load autoclave at 121 C , at 20 pounds pressure for 30 minutes.

75. PARAMETER Standard conditions are 121 C at 15 psi of pressure for at least 15 minutes. Or 132 C for 3 - 7 minutes at 30 psi for unwrapped instruments , add 5 mins for moderately packed. Instruments should be packaged in muslin cloth, paper, nylon, aluminium foil, steam permeable plastic. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 75

76. STERILISATION MONITORING Biologic indicators; spores of Bacillus Stearothermophillus ( thermophilic organism) with a growth of 55 - 60 C. Its spores require exposure of 12 minutes at 121 C to be sterilised. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 76

77. Recommended Cycles Settings for general wrapped items: Temp . - 121 degree C , Pressure - 20 PSI Time -- 30 min Setting Settings for bottled solutions: Always vent bottles to avoid bursting ! Temp. - 121 degree C, Pressure - 20 PSI Time -- 30 min Setting 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 77 Temperature Holding time 121 C 15min 126 C 10 min 134 C 3min

78. Setting for "Flashing" an unwrapped instrument: Temp. – 132 degree C, Pressure - 30 PSI Time -- 4-7 Min Setting Flash sterilization :- Sterilization cycles – operate at high temp – shorter time 3-10 min at 131 C 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 78

79. WRAPPING OF INSTRUMENTS 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 79

80. AUTOCLAVED INSTRUMENTS 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 80 USES Dressings Instruments Laboratory ware Media Pharmaceutical products Rubber items

81. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 81 DISADVANTAGES Causes rust & corrosion of non-stainless steel instruments , carbide burs. Damage to plastic & rubber. Dulls unprotected cutting edges. Items may be wet after cycle. Deposits with use of hard water . ADVANTAGES Time efficient. Good penetration of fabric and paper wrapping. Effective against spores. Sterilizes water based liquids (irrigating solution) in standard cycles .

82. PRE-VACCUM AUTOCLAVE A new form of autoclave called the Prevacuum autoclave has been developed, which draws air out of the chamber at the beginning of the cycle . The major advantage of this is minimal exposure . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 82 Temperature – 132 C to 134 C Pressure – 28 to 30 lb /in 2 Time – 4 minutes

83. GRAVITY DISPLACEMENT AUTOCLAVES Small, automatic bench-top autoclaves. They work on the principle of downward displacement of air as a consequence of steam entering at the top of the chamber. They are not recommended now 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 83

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85. FILTRATION Removal of microbes by passage of a liquid or gas through a screen like material with small pores. Used to sterilize heat sensitive materials like vaccines, enzymes, antibiotics, and some culture media. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 85

86. Types: Candle filters : Purification of water for industrial & drinking purposes a ) Unglazed porcelain ( Chamberland & Doulton filters) b) Diatomaceous earth ( Berkefeld & Mandler filters . ) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 86

87. Membrane filter ( 0.22 µm pore diameter) - widely used in water purification and analysis, sterilisation and sterility testing a)Cellulose acetate/cellulose nitrate/polycarbonate . HEPA filters : - High Efficiency Particulate Air filters. a ) Remove 99.97% of 0.3µm particles Used in operating rooms and burn units To remove bacteria from air. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 87

88. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 88 RADIATION Radiation Non- ionising Infrared Ultraviolet Ionising X-rays Gamma rays Cosmic rays

89. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 89 Non – Ionising Radiation INFRA RED ULTRAVIOLET Wavelength > Light Disinfecting enclosed Absorbed as heat areas like entryways , Rapid mass sterilization OT , labs of prepacked items (syringes , catheter) 89

90. Ionising radiation X rays Gamma rays Beta rays short wavelength  high penetrating power electrons from atoms stripped highly reactive radicals (-OH&H+) formed DNA breakage of the organisms 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 90 D E A T H

91. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 91 But ionizing radiation is not harmful in a particular case. The case is related to how long you are exposed. USES Plastics Syringes Swabs Catheters Surgical catgut Bone tissue graft .

92. ULTRASONIC VIBRATIONS Microorganisms in the fluid are disintegrated by the external pressures . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 92 The current trend is to use ultrasonic as a cleaning agent to follow the process by sterilization in an autoclave.

93. When propagated in fluids ultrasonic vibrations cause formation of microscopic bubbles or cavities and the water appears to boil. Some observers call this COLD BOILING . The cavities rapidly collapse & send out shock waves. The formation and implosion of the cavities is known as CAVITATION . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 93

94. FREEZING Freezing can both kill and preserve depending on various factors. Repeated freezing and thawing are much more destructive to bacteria than prolonged storage at freezing temperature. If bacteria are rapidly subjected to temperature below –35 C, ice crystals that form within the cell produce a lethal effect during defreezing . Two freezing cycles have been proved to be more lethal. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 94

95. Ice crystal disruption: ( i) Freezing kills by ice crystal disruption of cells and molecules. ( ii) Freezing slowly is generally more harmful than rapid (or flash ) freezing. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 95 LYPOPHILIZATION (FREEZE-DRYING ) A process used for preserving biological material, by removing water from the sample, that involves first freezing the sample and then drying it under vacuum, at a very low temperature.

96. NEWER METHODS IN STERILIZATION CHEMICLAVE This system depends on heat, water and chemical combination for it’s efficacy. The temperature and pressure required is greater than that for autoclave. It is known as a Chemiclave / Harvey Sterilizer. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 96

97. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 97 Instead of distilled water a solution of 78.28% alcohol, 0.23%formaldehyde, ketone, acetone and water is used to produce the sterilizing vapor. Temperature : 131 C at 20 pounds pressure for 20 to 40 minutes.

98. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 98 Advantages Short cycle. No rusting or corrosion. Dry instruments at the end of the cycle. Automatic preset cycle timing. Disadvantages Heat sensitive instruments. Chemical odors (fumes ). Liquids cant be sterilized. Special solution required.

99. 2. Sterilization by Cold Atmospheric Plasma Plasma is the fourth state of matter, discovered by the British physicist Sir William Crookes in the year 1879. It is a collection of stripped particles. Once the electrons are stripped from atoms and molecules, those particles change state and become plasma. Plasmas are naturally energetic because stripping electrons uses constant energy . Other well-known plasmas include lightning, neon signs, and fluorescent lights. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 99

100. Cold Atmospheric Plasma (CAP) is known as non-thermal because it has electrons at a hotter temperature than the heavy particles that are at room temperature. Gases that can be used to produce CAP are Helium, Argon, Nitrogen, Heliox (a mix of helium and oxygen), and air . The mechanism of plasma sterilization is related to the abundance of plasma components, like reactive oxygen species, ions and electrons, and UV and electromagnetic fields. Also , plasma can affect not only the contacted point but also the area around it. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 100

101. Yang Hong Li et al. stated that plasma sterilization, with the advantage of low temperature, fastness, thoroughness, safety, overcomes the deficiency of the traditional sterilization technology, and may become a novel method for killing microbe. To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated by Su-Jin Sung et al. It was proved that the atmospheric pressure nonthermal air plasma device was effective in killing both Escherichia coli and Bacillus subtilis . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 101

102. STERILIZATION Liquid sterilization process ( Endoclens ) New plasma sterilizer ( Sterrad 50) Rapid readout ethylene oxide biological indicator ETOX (Attest) LASER 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 102

103. TO BE CONTINUED.. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 103

104. GOOD AFTERNOON

105. A Fomite is any nonliving object or substance capable of carrying infectious organisms such as germs or parasites and hence transferring them from one individual to another. For eg . Skin cells, hair, bedding, clothing, stethoscopes, neckties, IV drip tubes, catheters etc. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 105

106. Bunsen Burner 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 106 Types of Flames Roaring blue flame (700 o C) Blue flame (500 o C) Safety flame (300 C) The flame has an Outer oxidizing zone Middle reducing zone Inner unburned gases

107. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 107 DISINFECTION

108. CHEMICAL AGENTS - Alcohols a. Ethyl alcohol b. Isopropyl alcohol c. Methyl alcohol d. Trichlorobutanol -Aldehydes a. Formaldehyde b . Gluteraldehyde 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 108

109. Dyes a . Aniline dyes b . Acridine dyes Halogens - Phenols - Surface active agents - Metallic salts Gases a . Ethylene oxide b . Formaldehyde c . Beta propionolactone 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 109

110. IDEAL REQUIREMENTS 1. Broad and wide spectrum of activity 2. Fast acting (even in presence of organic matter) 3. Non toxic 4. Surface compatibility 5. Easy to use 6. Odourless 7. Economical 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 110

111. 8. Be stable 9 . High penetrating power 10. Should not cause local irritation and sensitivity 11. High solubility 12. Effective : acid and alkali 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 111

112. Factors that determine potency of disinfectants: Concentration of substance Time of action pH of medium Temperature Nature of organisms Presence of extraneous material 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 112

113. MECHANISM OF ACTION Act in various ways – Protein coagulation Disruption of cell membrane Removal of sulphydryl groups Substrate competition 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 113 A compound resembling the essential substrate of the enzyme diverts or misleads the enzymes necessary for the metabolism of the cell and causes cell death

114. TYPES OF DISINFECTION USED IN DENTISTRY (Recommended by ADA & CDC ) Surface disinfection : Used for treatment of surfaces like cabinets, tables , chairs , lights etc. Immersion disinfection : Immersion of plastics and instruments in liquid disinfectant Time required : 5-30 minutes . Immersion sterilization : Prolonged contact with disinfectant Time required (6-10 hours). Disinfectant has the capacity to kill all micro organisms and infective agents. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 114

115. High level disinfectants – These disinfectants inactivate resistant bacterial spores, Gram-positive and Gram-negative bacteria, M.tuberculosis . E.g . Ethylene Oxide Gas, Immersion Gluteraldehyde Solutions 2. Intermediate level disinfectants – These disinfectants do not inactivate spores during routine use but they destroy other forms of microbes, vegetative bacteria, most viruses, fungi, M.tuberculosis . E.g.Formaldehyde , Chlorine Compounds, Iodophors , Alcohols, Phenolic Compounds. 5/5/2017 Basic Seminar 3 - Dr. Barkha . S. Tiwari 115 LEVELS OF DISINFECTION

116. 3. Low level disinfectants – Provide the narrowest antimicrobial range , most bacteria and fungi but not M. tuberculosis . E.g. Quaternary Ammonium Compounds, simple phenols and detergents. Such compounds are suitable for cleaning environmental surfaces. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 116

117. SPAULDING (1872) classified dental instruments as: CRITICAL : They penetrate the skin or mucosa including bone. E.g - Needles, scalers , burs, scalpels, surgical instruments, dental explorers, endodontic files. SEMI-CRITICAL : These items contact, but do not penetrate intact skin or mucous membrane. E.g - Amalgam condensers, hand pieces , mirrors, cheek retractors, impression trays 5/5/2017 Basic Seminar 3 - Dr. Barkha . S. Tiwari 117

118. NON-CRITICAL : These items (also known as clinical contact surfaces) come in contact with intact skin but not mucous membranes. E.g - Chair surfaces, radiographic equipment, blood pressure cuffs, facebows , pulse oximeters , examination and curing lights, computers 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 118 A. Critical : Sterilize B. Semi-critical : Sterilize, High level disinfection C. Non-critical : I ntermediate level disinfectant.

119. ALCOHOLS ETHYL ALCOHOL / PROPYL ALCOHOL (70%) : Mixed with water and used for skin antisepsis prior to cannulation , injection and hand-scrubbing. "Some water must be present for alcohols to disinfect because they act by coagulating (permanently denaturing) proteins, and water is needed for the coagulation reactions. Also the mixture penetrates more deeply than pure alcohol into most materials to be disinfected" 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 119

120. 2. ISOPROPYL ALCOHOL It is preferred to ethyl alcohol as it is a better fat solvent, more bactericidal and less volatile. It denatures proteins & lipids, and leads to cell membrane disintegration. It is used to disinfect the skin prior to cutaneous injections. It is active against gram positive, gram negative, & acid fast organisms at a concentration of 50-70% ‘ Isopropyl alcohol’ or ‘rubbing alcohol’ has high bactericidal activity in concentration as high as 99%. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 120

121. DISADVANTAGES : Relatively inefficient in the presence of blood and saliva . Lacks sporicidal activity. Causes corrosion of metals 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 121

122. Effective against fungal spores and is used for treating cabinets and incubators. Chambers are wiped with liberal amounts of methanol. However methyl alcohol is toxic and inflammable. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 122 3.METHYL ALCOHOL

123. Sterillium : Effective, Rub-in hand disinfectant Composition: 2-propanol- 45gms 1-propanol-30gms ethyl-hexadecyl-dimethylammonium-ethylsulphate-0.2gms Directions for use : 1. Hygienic Hand Disinfection : Rub sterillium well over clean, dry hands and nail grooves for 30 secs . 2. Surgical Hand Disinfection : Rub sterillium well over clean, dry hands, grooves and upto elbows for 3 mins . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 123

124. ALDEHYDES GLUTERALDEHYDE 2 % CIDEX solution is effective . It destroys vegetative cells within 10 to 30 minutes and spores in 10 hours. It is recommended for use on surgical instruments where residual blood may be present . It does not damage delicate objects, and therefore it can be used to sterilize optical equipment such as the optic fiber endoscopes. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 124

125. It is an agent of choice for disinfecting metal containing dental instruments & used as a sterilizing agent. Kills by denaturation of proteins. Gluteraldehyde will disinfect in 10 minutes and will sterilize after 6- 10 hours immersion at room temperature. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 125

126. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 126 ADVANTAGES High biocidal activity. Tuberculocidal , sporicidal . Used only as immersion sterilization/disinfectant. Active in organic debris. Doesn’t degrade rubber & plastic items .

127. DISADVANTAGES It can damage many metal items. E.g . nickel coated impression trays & carbon steel burs will often discolor and corrode, respectively when immersed in gluteraldehyde solution for prolonged periods. It can cause hypersensitivity on repeated exposure so instruments immersed in gluteraldehyde should be thoroughly rinsed in sterile water prior to use. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 127

128. USES OF GLUTERALDEHYDE Surgical instruments where residual blood may be present. Scopes (optic fibre endoscopes, cytoscopes , bronchoscopes, etc.) Treat corrugated rubber tubes, anaesthetic tubes, face masks, plastic endotracheal tubes, metal instruments, polythene tubing. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 128

129. FORMALDEHYDE (a Component of Chemiclave ) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 129 Formaldehyde Bacteria Spores Viruses Anatomic specimens 10% formalin + 0.5% sodium tetraborate Disadvantages Vapour

130. It is gas at high temperature & solid at room temperature. In aqueous solutions, it is bactericidal, sporicidal and virucidal . To make a solution of 10% Formalin, 9parts of water are added to 1part of 40% (aqueous) Formaldehyde. Formalin is utilized for inactivating virus in vaccines & producing toxoids from toxins. In the gaseous form, formaldehyde is expelled into a closed chamber where it is used as a sterilant for surgical equipment, hospital gowns and medical instruments. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 130

131. However penetration is poor and the surface must be exposed to the gas for up to 12hours for effective sterilization. (Fumigation) Formaldehyde leaves a residue and instruments must be rinsed before use. Can cause hypersensitivity reactions. Formalin residues can be neutralized by using ammonia . ( 250 ml ammonia per litre of formalin ) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 131

132. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 132 USES OF FORMALDEHYDE Against bacteria, viruses, spores Anatomic specimen preservation 10% Formalin + 0.5% sodium tetraborate – sterilised clean instruments. Heat sensitive catheters Fumigating sick rooms, laboratories. Disinfecting- clothing, bedding, furniture (under controlled conditions) in hospitals.

133. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 133 Korsolex disinfectant: Composition – Gluteraldehyde : 15.2g Formaldehyde: 19.7g Direction for use : Using gloves, dilute 5parts of Korsolex Rapid to 95 parts of clean tap water to get 5% solution. Dip pre-rinsed instruments in prepared Korsolex Rapid solution

134. ANILINE DYES Brilliant green, malachite green & crystal violet . They are more active against gram positive organisms . Gentian violet is used for the T/t of trench mouth and Candida Albicans infection. Interference with cell wall appears to be the mode of activity ( BACTERIOSTATIC in high dilution). 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 134

135. ACRIDINE DYES Acriflavine , Proflavine , Euflavine , Aminacrine . These dyes are used as antiseptics for staphylococcal infections in wounds. They act by combining directly with DNA, thereby stopping RNA synthesis. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 135

136. These dyes are more active against gram positive organisms than against gram negative but are not as selective as the aniline dyes. Acridine dyes are often referred to as “ flavines ” because of their yellow colour . They are active even in the presence of serum or pus unlike aniline dyes. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 136

137. OXIDANTS An oxidizing agent is a substance that has the ability to oxidize other substances (cause them to lose electrons) Halogens Hydrogen peroxide Potassium permanganate 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 137

138. HALOGENS Highly reactive elements. Two halogens Chlorine & Iodine are commonly used for disinfection. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 138

139. 1. CHLORINE Available as -- gas -- organic compound ( organochloride , chlorocarbon ) -- inorganic compounds (hydrogen chloride) Most commonly used as HYPOCHLORITES The disinfectant action results from it’s ability to liberate free chlorine. In aqueous solutions the liberated Cl ions reacts with water to form hypochlorous acid. Concentration – 0.05 - 0.5% , contact time - 10 minutes. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 139

140. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 140 Used in water supplies and swimming baths. Chlorox & Purex bleach used for household sanitation & in the disinfection of food utensils. Chlorinated lime is used as bleaching agent in textile industry. CHLORAMINES : such as chloramines - T are organic compounds that contain chlorine and amino groups. These compounds release free chlorine more slowly than hypochlorite solutions and are more stable. They are used for general wound antisepsis and root canal therapy.

141. 2. SODIUM HYPOCHLORITE Active component of household bleach . Household bleach (5% hypochlorite) diluted 1: 10 to 1:100 in water used as antimicrobial and also to disinfect plastics. Kills vegetative bacteria, viruses and few bacterial spores. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 141

142. In dentistry- it is used as an intracanal medicament. (first suggested by Grossman in 1941) Mechanism of action Chlorine in aqueous solution exists in two forms-hypochlorite ( OCl - ) and hypochlorous acid ( HOCl ) It is responsible for breakdown of proteins into amino groups. 3. Hypochlorite dissolves necrotic tissue because of its high alkaline nature 4. To increase the efficacy, 1% sodium bicarbonate is added . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 142

143. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 143 5.25% Hypochlorite - irrigation of root canal .

144. Precautions to be taken while using Sodium Hypochlorite Solution. If NaOCl gets extruded to periapical tissues, it causes excruciating pain, periapical bleeding and swelling. Medications like antibiotics and analgesics should be prescribed accordingly. Also during irrigation, the needle with very small diameter to be used and never locked in the canal. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 144

145. DAKIN’s solution 0.5% sodium hypochlorite solution was used by H. D. Dakin extensively for wounds during the I & II World War In Europe. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 145

146. Advantages It causes tissue dissolution It has antibacterial and bleaching action It causes lubrication of canals Economical Easily available 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 146

147. Disadvantages Because of its high surface tension, its ability to wet dentin is less. Irritant to tissue periapically If comes in contact, it may cause gingival inflammation Bleach the clothes if split Bad odour and taste Vapours can irritate the eyes 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 147

148. IODINE Iodine is more reactive and more germicidal. Iodine acts on the tyrosine portions of protein molecules. Tincture of iodine 2% iodine solution in ethyl alcohol used as an antiseptic for application over skin and mucous membrane. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 148

149. IODOPHORS When iodine is complexed with certain organic material the compound is called IODOPHOR - retains germicidal action of iodine & reduces caustic & staining effects. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 149 Povidine -iodine 5% & 0.9 % NaCl is used for irrigation (Betadine).

150. HYDROGEN PEROXIDE It is used to rinse wounds, scrapes and abrasions. The area foams & effervescence as catalase in the tissue breaks down hydrogen peroxide to oxygen & water. The furious bubbling removes microorganisms mechanically. Anaerobic bacteria are sensitive to H 2 O 2 because sudden release of oxygen gas inhibits their growth. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 150

151. New forms of H 2 O 2 are more stable than traditional forms and do not decompose spontaneously. Inanimate material such as soft contact lenses, utensils, and heat sensitive plastics can be disinfected within 30 minutes . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 151

152. In dentistry: 3% of hydrogen peroxide is used as an irrigant The rapid release of nascent oxygen [O] in contact with organic tissue effervescence dislodges the necrotic tissue and dentinal debris. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 152

153. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 153 PHENOLS

154. CARBOLIC ACID AND OTHERS Following its introduction as a surgical antiseptic by Lister in 1865, phenol was widely used as a disinfectant . Since most phenolic disinfectants have a low solubility in water , they are formulated with emulsifying agents, such as soaps, which also increase their antimicrobial action. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 154

155. ACTION: They act as cytoplasmic poisons by penetrating and disrupting cell wall , thereby leading to denaturation of intracellular proteins. Phenol is active against gram positive bacteria. Bactericidal at 1% and fungicidal at 1.3%. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 155

156. HEXACHLOROPHENE : Uses : Skin disinfectant Presurgical disinfection for patients/surgeons. CHLOROXYLENOL Non corrosive, non irritant Used as antiseptic, poor activity against many bacteria DETTOL - 4.8 % chlorxylenol + 9 % terpinol + 13% alcohol 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 156

157. CRESOL 3-10 times more active than carbolic acid 50% soapy emulsion, LYSOL CLEARSOL & STERLICOL Widely used in hospitals and labs 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 157

158. SURFACE ACTIVE AGENTS Classified as cationic, anionic, nonionic and amphoteric compounds . ANIONIC SURFACE ACTIVE AGENTS These are active at acid ph. These agents cause gross disruption of the lipoprotein framework of the cell membrane and also have mechanical cleansing action. , e.g . Soaps and fatty acids 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 158

159. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 159 DISADVANTAGES Inability to penetrate organic debris . Incompatible with Ca, Mg, and iron of hard water. E.g. Benzalkonium Chloride.

160. NON-IONIC SURFACE ACTIVE AGENTS These agents are relatively nontoxic and few promote bacterial growth. E.g . Tween 80 ( Polysorbate ) facilitates the diffused growth of mycobacterium tuberculosis and provides a source of Oleic acid which is stimulatory to the organism. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 160

161. CATIONIC SURFACE ACTIVE AGENTS Quarternary ammonium compounds – Acetyl trimethyl ammonium bromide. C ETAVLON SAVLON – 3.0% cetrimide + 0.3% CHX AMPHOTERIC SURFACE ACTIVE AGENTS Also known as surfactants ( eg . Dodecylbenzenesulfonate ) ‘ Tego ’ compounds – no longer used now. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 161

162. METALLIC SALTS- BISGUINIDES (CHLORHEXIDINE, HIBITANE) Non toxic skin antiseptic. Most effective against gram positive organisms Fairly effective against gram negative organisms. Aqueous solution used in treatment of wounds. 4% SOLUTION– SURGICAL SCRUB 0.4%- solution in detergent. 0.2 % - anti-plaque agent. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 162

163. 2% - denture disinfectant. 0.12% - root canal irrigant . Available as dihydrochloride , diacetate , gluconate . Wide range of activity against gram positive or gram negative organisms. Low activity against spores/viruses . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 163

164. CHLORHEXIDINE GLUCONATE It exhibits both antiplaque & antibacterial properties. Bacteriostatic at low concentration & bactericidal at high concentration 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 164

165. Mechanism of action:- 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 165 The Dicationic CHX molecule , attaches to the pellicle by one cation , and to the bacteria attempting to colonize the tooth surface with the other. This is called the ‘Pin-Cushion Effect ’ . At low concentration this results in increased permeability with leakage of intracellular components including potassium . At high concentration chlorhexidine causes precipitation on bacterial cytoplasam & cell death . Once adsorbed; shows a persistant bacteriostatic action lasting in excess of 12 hours – ‘ Substantivity ’

166. GASES 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 166 Formaldehyde gas Betapropionolactone BPL Ethylene oxide

167. Formaldehyde gas 150 grams of KMnO 4 + 280 ml Formalin Fumigation of operation rooms. When formaldehyde gas is used, doors must be sealed and left unexposed for 48 hours. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 167

168. Betapropionolactone (BPL) Condensation product of ketone and formaldehyde. More efficient for fumigation than formaldehyde. Rapid biocidal action but carcinogenic potential . 0.2% BPL is used for sterilisation of biological products. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 168

169. Ethylene oxide Colorless liquid Boiling point of 10.7 C Highly penetrating gas with a sweet ethereal smell Highly inflammable, highly explosive When mixed with 10% CO 2 or nitrogen , explosion is limited. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 169

170. MECHANISM OF ACTION Alkylating the hydroxyl, carboxyl, amino and sufhydryl groups in protein molecules. Reacts with RNA & DNA. Requires a special chamber and proper ventilating facilities because it is toxic and carcinogenic. Humidification of the load is necessary before sterilization because the biocidal activity increases in the presence of moisture. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 170

171. The chamber then must be flushed with inert gas for 8-12 hours to ensure that all traces of ethylene oxide are removed otherwise, the chemical will cause “cold burns” on contact with skin. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 171

172. Testing the disinfectant Determination of phenol coefficient : The disinfectant to be tested is compared with phenol on a standard microbe . 1. Rideal walker test- Phenol is considered as standard, and corresponding rating system is called “phenol coefficient ” This is a figure expressing the disinfecting power of any disinfectant. It is the ratio of the dilution of the disinfectant that kills a microorganism to the dilution of phenol that kills the organism in the same time under identical conditions. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 172

173. Disinfectants that are more effective have coefficient >1 and less effective have coefficient <1. Chick martin test- Method of testing the invitro efficiency of the bactericidal agent by a standard culture of Salmonella Typhi . Disinfectant acts in presence of organic matter (yeast suspension ) and is tested for a fixed period of time against various concentration of phenol solution. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 173

174. INSTRUMENT DIVISION 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 174

175. BRACKETS , BAND MATERIALS Standard steam Autoclave Chemical vapor Ethylene oxide Dry heat sterilizing cycles. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 175

176. DISINFECTION OF ELASTOMERIC LIGATURES 2 % gluteraldehyde 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 176 ORTHODONTIC MARKING PENCILS -Wiping with a sterile gauze -Soaking pencil tips in disinfectant

177. DENTAL HAND-PIECES Surface contamination control Sterilisation 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 177

178. Most common is autoclaving. Chemical vapor pressure sterilization can also be used. Etox gas- most gentle method Etox processing takes several hours /overnight. Dry heat sterilization – generally not recommended. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 178 NSK High Speed Handpiece Sterilization recommended – autoclave

179. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 179

180. Remove the bur and dismantle the handpiece if possible, to allow for more effective treatment. Treat all parts together. Remove organic matter with a small brush. For lubrication- Spray ‘ PANA – SPRAY ’ for 1-2 seconds into the drive tube before autoclaving . For Average use- lubrication at the end of each day’s work Above average use - lubricate twice a day(one at lunch time, and one at the end of the day’s work) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 180

181. The following disinfectants are effective against AIDS-related virus: 70 % ethanol for one hour . 2 % freshly prepared glutaraldehyde , or 1 % available iodine solution for 30 minutes. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 181

182. IMPRESSIONS The ADA recommends that all impressions must be rinsed to remove saliva; blood and debris followed by disinfection before cast and die stone are sent to a dental laboratory. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 182 The laboratory disinfects appliance and then transports it in a heat-sealed bag to the dentist

183. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 183 Item Recommended method Alternative method Impressions Alginate Rinse, get rid of excess water, spray with 0.1% sodium hypochlorite, put in closed container for 10 seconds. Iodophors can also be used. Zinc oxide eugenol paste Rinse, get rid of excess water, spray with 0.1% sodium hypochlorite, put in closed container for 10 secs . Iodophors can also be used. Polysulphide rubber base Rinse, immerse in 2% gluteraldehyde for 10 minutes, rinse Iodophors , sodium hypo chlorite can also be used Polyether Chlorine compounds Silicon rubber Gluteraldehyde, iodophors, chlorine compounds. Impression compound Rinse under running tap water and immerse in Iodophors or chlorine compounds

184. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 184 Recommendations For Disinfecting Impression Materials Impression Materials Disinfectants Gluteraldehyde Iodophors Sodium hypochlorite Alginate No Yes Yes Polysulfide Yes Yes Yes Silicones Yes Yes Yes Polyethers No Yes Yes Reversible hydrocolloid No Yes Yes ZnOE PASTE Yes Yes

185. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 185 Sterilization of conservative instruments Instruments 1 st choice 2 nd choice 3 rd choice Metal instr. Moist heat Dry heat chemical Surgical burs Moist heat Dry heat chemical Handpieces Moist heat chemical - Airotor Moist heat chemical - Cautery tip Gas chemical - M.mirror Moist heat chemical Dry heat 3-way syr. Moist heat chemical Dry heat

186. RUBBER DAM Once the rubber dam is applied, the teeth and the dam should be thoroughly swabbed with a large pellet of cotton soaked in a quick evaporating, non staining antiseptic i.e. 2% Glutaraldehyde . Ray : Has recommended 2% Benzalkonium chloride in 5% of isopropyl alcohol . Moller : Prefer swabbing with hydrogen peroxide followed by tincture of iodine . 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 186

187. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 187 Rubber Dam Part Sterilization method Rubber dam clamps Autoclaving or dry heat sterilization Plastic Frame Metal Frame Gluteraldehyde Autoclaving Rubber dam punch Autoclaving or dry heat Rubber dam sheet Disposable

188. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 188 Instruments Sterilizer used Method of sterilization Dapen Dish Merthiolate 70% alcohol Swabbed with merthiolate followed by alcohol Reamers, files broaches, spreaders Hot salt sterilizer Immersing it in hot salt sterilizer for 5 sec Gutta Percha cones 5.2% sodium hypochlorite Kept sterile in screw capped vials containing alcohol until sterilization. Immersing it in sodium hypochlorite for 1 min then rinse the cone with hydrogen peroxide and dry it between 2 layers of sterile gauze Silver cones Glass bead sterilizer Immersing it in 55 sec Paper points Hot salt sterilizer Immersing for 10 sec by placing its butt head first Glass slabs Cement spatula Iodine and alcohol Swabbing the surface with iodine and double swabbing with alcohol . Tips of cotton pliers 90% alcohol, flaming Tips of cotton pliers are dipped in alcohol and then subjected to flaming

189. COMPOSITE FILLING INSTRUMENTS All composite instrument can be heat sterilized by the acceptable methods, not exceeding 350 o C/177 o F . Steam autoclave Chemical vapor Dry heat Ethylene oxide 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 189

190. DENTAL BURS IN AUTOCLAVE By submerging burs in 2% Sodium nitrite solution . Burs kept in small metal/glass beaker with perforated lid ( eg . Metal Salt Shaker) 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 190

191. ENDODONTIC FILES For surface disinfection during canal debridement- Banker’s Sponge soaked in 70% Isopropyl alcohol/proprietary quaternary ammonium solutions. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 191

192. The protocol comprises 10 vigorous strokes in a scouring sponge soaked in 0.2 % Chlorhexidine solution . They can also be sterilized in autoclave and with sodium hypochlorite. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 192 Ni-Ti ENDODONTIC INSTRUMENTS

193. CONCLUSION It is our most important duty to preserve and maintain the health of our patients and ourselves due to alarmingly high risk of getting infected by dangerous diseases like hepatitis-B, TB, herpes, HIV etc. As it is always said that PREVENTION IS BETTER THAN CURE , sterilization and disinfection should be practiced regularly to prevent others and ourselves from getting infected. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 193

194. REFERENCES Ananthanarayan R, and C. K. Jayaram Paniker . Textbook Of Microbiology. Bombay: Orient Longman, 1981. Samaranayake LP. Essential Microbiology For Dentistry. Edinburgh: Churchill Livingstone/Elsevier, 2006. Peter Soben . Essentials Of Preventive And Community Dentistry. New Delhi: Arya ( Medi ) Publishing House, 2003. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 194

195. A textbook of Preventive and Social Medicine. Park 23 rd edition. Chandra, Gopi Krishna V, Grossman LI. Grossman's Endodontic Practice. New Delhi: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2010 . A textbook of Endodontics , Nisha Garg , 2 nd Edition Practical Infection Control in Dentistry, James A.Cottone , 2 nd Edition. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 195

196. 5/5/2017 Basic Seminar 3 - Dr. Barkha. S. Tiwari 196