Sterilization and disinfection in dental clinics /certified fixed orthodontic courses by Indian dental academy


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Sterilization and disinfection in dental clinics /certified fixed orthodontic courses by Indian dental academy

  1. 1. tion lisa teri S and tion fec isin D ntal n de i n i c s DENTAL cli INDIAN ACADEMY Leader in continuing dental education
  3. 3. TERMINOLOGIES Sterilization - Process of destruction or removal of all viable microorganisms from an object or from a particular environment . - Total inactivation of all forms of microbial life in terms of the organism’s ability to reproduce .
  4. 4. Disinfection - Refers to the use of physical process or chemical agent (disinfectants) that promotes killing, inhibition, or removal of pathogenic microorganisms (usually on inanimate objects) but not bacterial endospore.
  5. 5. Sepsis – growth of microorganisms or the presence of microbial toxins in the blood and other tissues. Asepsis - refers to any practice that prevents the entry of infectious agents into sterile tissues and thus prevents infection.
  6. 6. Antisepsis – aseptic technique practiced in health care, ranges from sterile methods that uses chemical agents (antiseptics) which are applied directly to exposed body surfaces, wounds, and surgical incision to destroy or inhibit vegetative pathogens.
  7. 7. - is an agent used to reduce the viability of a microbial population below a threshold level that causes infection. - Disinfectants are used on inanimate objects. Disinfectant Antiseptic - chemical agents that opposes sepsis or putrefaction either by killing microorganisms or by preventing their growth. - Term commonly used for agents that are applied topically to living tissues.
  8. 8. HISTORY Zaccharias Jansen in 1590 and Robert Hooke iin 1660 opened the world of microbes to mankind by their inventions of microscopes. AntonVan Leeuwenhoek-.””’”animolecules;”1667 through his handcrafted microscope-observed tooth scrapings. in 1667 through microscope his handcrafted
  9. 9. “ The Golden Age of MICROBIOLOGY” Louis Pasteur (France) Robert Koch (Germany) Igniz Semmelweiss (Vienna), Oliver Wendell Holmes (USA), Lord Joseph Lister (England) Louis Pasteur (France).
  10. 10. Willoby Miller (USA) who came to be known as the “Father of oral Microbiology”” in mid-concept of prevention of disease through “Infection Control Procedures”
  11. 11. INFECTION “Defined as an invasion and multiplication of micro organisms in body tissues. Transmission: Source Mode of Transmission Susceptible Host
  12. 12. CROSS INFECTION Defined as the transmission of infectious agents between patient and the staff within a “clinical environment”. Causes P Patients suffering from the infectious illness. ing finf Patients in prodromal phase of infection . Carriers of infectious organism.
  13. 13. INFECTION VERSUS CROSSINFECTION Pathways  Patient to dental team  Patient to patient  Dental team to patient  Dental office to community
  14. 14. CHAIN OF INFECTION All links must be connected for infection to take place Pathogen Susceptible Host Source Entry Mode
  15. 15. Goal of Infection control “Eliminate or reduce the number of microbes shared between people”
  16. 16. Infection Control In Dental Office Dental office designing and maintenance.  Patient screening  Personal protection Immunization ii. Hand hygiene, washing and care iii. pre procedural mouth wash  Personal protective equipment i. Gloves ii. face mask i.
  17. 17. Dental Office Designing And Maintenance. 1. Cabinetry 2. Floor covering 3. Work surfaces 4. Ventilation
  18. 18. Patient screening Patient medical history. Identify patients at high risk to harbor potentially infectious organisms and those who may have increased susceptibility to infections.
  19. 19. Personal protection Immunization  Hand washing . Antiseptic mouth rinses for the patient
  20. 20. 1 5 9 2 4 3 6 10 7 11 8 12
  21. 21.
  22. 22. Personal protective equipment (PPE) PPE is designed to protect the skin and the mucous membranes of the eyes, nose, and mouth of dental health-care personnel (DHCP) from exposure to infectious or potentially infectious materials.
  23. 23. Gloves Types of gloves; i. Sterile surgical gloves ii. Over gloves ( Avoids cross-contamination)
  24. 24. iii. Examination gloves Powder-free (preferable)  Latex – inexpensive but could be allergic  Polyurethane – strong and nonallergic  Nitrile – strong and non-allergic  Vinyl – non-allergic
  25. 25. iv. Utility gloves.   Nitrile gloves Puncture and cut resistant to handle contaminated sharps Neoprene gloves Handle hot objects and to avoid burns/scalds (while removing sterile instrument packs from sterilizer)
  26. 26. Recommendations for Gloving Remove gloves that are torn, cut or punctured Do not wash, disinfect or sterilize gloves for reuse
  27. 27.  Face Mask
  28. 28.  Protective eye wear
  29. 29. Proper clinical attire Wear gowns, lab coats, or uniforms that cover skin and personal clothing likely to become soiled with blood, saliva, or infectious material.
  30. 30. DYNAMICS OF STERILIZATION & DISINFECTION Microorganisms are not killed instantly when exposed to a lethal agent . The kinetics of death of a microbial population is exponential. The rate of disinfection varies with the concentration of the disinfectant.
  31. 31. Factors affecting disinfectant potency 1. Number of microorganisms 2. Nature of microorganism 3. Temperature ,pH 4. Time
  32. 32. 5. Mode of action of the agents 6.Concentration of the agent 7. Presence of exogenous materials
  33. 33. CLASSIFICATION OF INSTRUMENT STERILIZATION Proposed by SPAULDING in 1972 according to the use and degree of contamination patient care items and equipments are classified as:  Critical  Semi Critical  Non Critical
  34. 34. METHODS OF MICROBIAL CONTROL Physical Agents Chemical Agents Chemotherapeutic Agents
  35. 35. • Heat • Freezing • Radiation • Filtration • Ultrasonic and SonicVibration
  36. 36. HEAT - Most reliable and universally applied method of sterilization - 2 kinds of heat : 1. Dry 2. Moist
  37. 37. Thermal Death Time - Refers to minimum time required to kill all microbes at a specified temperature in a specified environment . Thermal Death Point - Lowest temperature required to kill all microbes when time is held constant.
  38. 38. DRY HEAT Sterilization that requires higher temperature and longer period of heating . Denotes air with a low moisture content that has been heated by flame or electric heating coil. Temperature ranges from 160°C – several thousand degrees.
  39. 39. Mechanism of action : Denaturation of proteins Oxidative damage Its use is limited primarily to sterilization of glass wares and materials as oils, jellies, and powders that are impervious to steam.
  40. 40. Forms: 1. Direct flaming Loops or wires, glass slides ,cover slips, the tips of the instruments are held in a Bunsen flame till they become red-hot. These materials may be dipped in a disinfectant before flaming.
  41. 41. 2. Incineration / cremation This is an excellent method for safely destroying materials such as contaminated cloth, animal carcasses and pathologic material, Plastics such as PVC. Globally used for the disposal of hospital waste.
  42. 42. 3. Hot air oven This is the most widely used method of sterilization by dry heat. A holding period of 160oC ( 320oF) for 1 hr is used to sterilize glassware, swabs, liquid paraffin, dusting powder, fats and grease. It is suitable for dry powders and water free oily substances.
  43. 43. Glassware should be perfectly dry before being placed in the oven. The British pharmacopoeia  recommends a holding period of 1hr at 1500C for oils, glycerol, and dusting powder. 
  44. 44. ADVANTAGES Effective and safe sterilization of metal instruments and mirrors. No corrosion of Carbon steel instruments and burs. Does not rust or corrode.
  45. 45. DISADVANTAGES Long cycles Poor penetration Uneven heating Cannot sterilize liquids Is generally unsuitable for handpieces
  46. 46. 4.Glass Bead And Hot Salt Steriliser  The glass bead sterilizer uses a metal cup with glass beads of 1 mm diameter in it. The hot salt container uses ordinary table salt.
  47. 47. The temperature range for both varies from 425o F to 475o F . Both are used to sterilise endodontic instruments.
  48. 48. MOIST HEAT kills bacteria faster than dry heat. Temperature ranges from 60-135°C. Mechanism of actionDenaturation and coagulation of proteins Loss of functional integrity of membranemolecules microorganism Time required for sterilization Most mesophilic nonsporeformers 60°C for 30min S. Aureus & S. faecalis 60°C for 60min Vegetative form of all bacteria, fungi & yeast 80°C for 5-10min Heat resistant sporeformers 120°C for 4min 100°C for 5.5min is required
  49. 49. Can be performed by 3 methods 1.Temperature below 1000c 2.Temperature at 1000c 3.Temperature above 1000c
  50. 50. Temperatures below 1000C PASTEURIZATION Its purpose is to reduce the bacterial population of a liquid such as milk and destroy organisms that may cause spoilage. Spores are not affected by this method .  Destroys Mycobacterium tuberculosis.
  51. 51. There are 3 methods Holder method Heats up to 62.90C for 30 min….. although thermophilic bacteria thrive at this temperature; they are of little significance because they cannot grow at body temperature.
  52. 52. Flash pasteurization This method uses a temperature of 71.60 C for 15 sec. followed by cooling to 130C. Ultra pasteurization This method uses a temperature of 820 C for 3 sec.
  53. 53. ADVANTAGES Rapid, economic , no elaborate equipment, good penetration and harmless to wide range of dental materials.
  54. 54. DISADVANTAGES  Dulls the cutting edges.  Causes corrosion.  Possible deposits from use of hard water
  55. 55. Steam at atmospheric pressure 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 higher the temperature.
  56. 56. Liquids are sterilized by this method at 1000C for 30min on each of 3 successive days. Also called Fractional sterilization, because a fraction is accomplished on each day. Also called Tyndallization after its developer John Tyndall, and Intermittent sterilization because it has a stop and start operation.
  57. 57. Steam Under Pressure 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.
  58. 58. The basic principle is that when the pressure of a gas increases, the temperature increases .
  59. 59. It is important to note that sterilizing agent is moist heat but not the pressure. Pressure 15 lbs/sq. inch Temperature 121.50C
  60. 60. Recommended Cycles Settings for general wrapped items:  Temp. - 121 degree C Pressure - 20 PSI  Time -- 30 min Setting Settings for bottled solutions:  Temp. - 121 degree C , Pressure - 20 PSI
  61. 61. Setting for "Flashing" an unwrapped instrument:  Temp. – 132 degree C Pressure - 30 PSI  Time - 4-7 Min Setting This method can be used for a broad variety of items such as instruments, clothing, glassware,
  62. 62. DISADVANTAGES Plastic ware melts in high heat. Sharp instruments become dull and corrode. Use of heavy water may leave deposits.
  63. 63. GAS STERILIZATION Ethylene oxide: The use of ETO is recognized by the American Dental association (ADA) and Centers for Disease control and prevention (CDC) as an acceptable method of sterilization.  i) Those that can be damaged by heat and/ or moisture.  ii) Those that can be cleaned and dried thoroughly.
  64. 64. This chemical is effective as a virucidal agent, is sporicidal, does not damage materials, and can evaporate without residues.
  65. 65. CHARACTERISTICS Temperature : room temperature (250C/750F) Cycle time : 10-16 hours (depending on material) Acceptable materials : paper, plastic bags Advantages : -High capacity for penetration. -Does not damage heat-labile material. -Evaporates without leaving a toxic residue.
  66. 66. Disadvantages: -Slow, requires long cycle time. -Uses toxic/hazardous chemical. -Items must be cleaned and dried thoroughly before exposure. -Causes tissue irritation if not well aerated..
  67. 67. FREEZING Primarily used in the preservation of bacterial cultures. In freezing, the formation of ice crystals outside the cell causes the withdrawal of water from the cell interior, resulting in an increased intracellular electrolyte concentration and denaturation of proteins. The cell membrane is damaged, and a leakage of intracellular organic compounds ensues.
  68. 68. Lyophilization ( 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 very low temperature.
  69. 69. RADIATION - Defined as energy emitted from atomic activities and dispensed at high velocity through matter or space. -2 types Ionizing radiation: Radiation that have sufficient energy to remove an electron completely from an atom and produce an electrical charge (ionization). Nonionizing radiation: Energy absorbed by the molecule cannot remove an electron completely, the excitation produced often leads to photochemical
  70. 70. Ionizing radiation - Electromagnetic rays: X-ray, alpha, beta & gamma rays - Can penetrate a solid barrier, bombard a cell, enter it, and dislodge electrons from molecules. - Breaks DNA, creates massive mutations. - Sterilizes catgut , nylon sutures, plastic, syringe,
  71. 71. Non-ionizing radiation - Ex. Ultraviolet light - Effectiveness of UV light as a lethal and mutagenic agent is closely related to its wavelength (240280nm); optimum at about 260nm which corresponds with the absorption maximum of DNA.
  72. 72. Lethal effect on bacteria is attributed to absorption. kills the organism. Primarily used to control airborne infections, where it is used for the disinfection of enclosed areas such as nurseries, hospital wards.
  73. 73. FILTRATION -An effective method to remove microbes from air and liquids. - Separates microorganism from contaminated solution. - Used to prepare liquids that cannot withstand heat (heat-labile), including serum and other blood products, vaccines, drugs, IV fluids, enzymes and culture media.
  74. 74. - TYPES 1. Seitz – asbestos – cellulose 2. Sintered glass – glass filaments 3. Chamberland – unglazed porcelain 4. Berkefeld – diatomaceous earth 5. Membrane filter – cellulose ester -High efficiency particulate air (HEPA) filters provide a flow of sterile air to hospitals.
  75. 75. ULTRASONIC VIBRATIONS 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.
  76. 76. The cavities rapidly collapse & send out shock waves. The formation and implosion of the cavities is known as cavitation. Microorganisms in the fluid are quickly disintegrated by the external pressures. The current trend is to use ultrasonic as a cleaning agent to follow the process by sterilization in an autoclave.
  77. 77.
  78. 78.  Destroys structural integrity of cell membrane (protein & lipids). Net effect is the release of small metabolites from the cell that interferes with the active transport and energy metabolism.
  79. 79.  Agents:  Surface active agents Cationic – most effective • Anionic • Non-ionic – not effective • Amphoteric  Phenolic compound  Alcohol •
  80. 80. I. Surface active agents - Substances that alter the energy relationship at interfaces producing a reduction of surface or interfacial tension. - They disrupt the integrity of cell membrane that results in the loss of molecules from the cytoplasm and affects the proton motive force which provides energy for solute transport.
  81. 81. Cationic Agents Quarternary ammonium compound - Bactericidal for a wide range of organisms, gram (+) species are more susceptible - Ex. Benzalkonium chloride ( Zephiran ) Used primarily in hand or face washes  Acts on phospholipids,changes cell permeability. Benzalkonium application many include disinfecting instruments and preserving drugs in low concentration form.
  82. 82. Anionic Agents - Soaps and fatty acid dissociate to yield negatively charged ions (active at acid Ph). - Causes gross disruption of the lipoprotein framework of the cell wall. - Displays rapid bactericidal action (within 30secs) . - Effective against gram (+) organisms.
  83. 83.  Diguanides - Acts at a concentration of (1 – 4) %. - Antimicrobial activity against vegetative bacteria, yeasts, and enveloped viruses . - Disrupts cytoplasmic membrane. - It may be used together with surface active agents.
  84. 84. Chlorhexidine which is more effective at pH 7 – 8 Used as a safe antiseptic to prevent body infection , in oral rinses for treating sore gums, mouth ulcers and preventing plaque on teeth. Chlorhexidine digluconate (GynePro feminine wash) 
  85. 85. II Phenolic compound - At low concentration, causes leakage of cell contents and irreversible inactivation of membranebound oxidases and dehydrogenases. - Parent compound : Carbolic acid ( phenol ) Excellent for disinfecting faeces, blood, pus, sputum & other proteinaceous material.
  86. 86. - Primarily used for testing new bactericidal agent - Cresols - Xylenols  Phenolics are effective against bacteria, fungi and viruses.
  87. 87. Phenol derivatives: • Cresols - Simplest of the alkyl phenols - Ortho-, meta-, paracresols – are applicably more active than phenol - Cresols are used to dissolve other chemicals, as disinfectants and deodorizers, and to make specific chemicals that kill Insect pests - Sold under the trade names: Lysol and Creolin •
  88. 88. • Xylenols - Dimethylphenols - Important class of phenolics with great industrial importance. - Used as pesticides and in the manufacture of antioxidants.
  89. 89. Kills 99.9% of germ s in 30 sec onds Hospital disinfectant deodorant is highly effective against TB, MRSA, and HIV-1 • Tuberculocidal, virucidal, fungicidal, bactericidal •
  90. 90. • Diphenyl compound Exhibits unique antibacterial property. - Hexachlorophene Topical anti-infective, anti-bacterial agent, often used in soaps, toothpaste and antiperspirant . - • Used as a preservative in cosmetic products. • PHisoHex, widely used as a very effective antibacterial skin cleanser in the treatment of acne.
  91. 91. III. Alcohol - Disorganizes lipid structure by penetrating intothe hydrocarbon region, denatures proteins. -Concentration between 50%-90% . -Optimal activity at 70% - 75% .
  92. 92. - Effective against vegetative bacteria, fungi and viruses . - Sporicidal activity - Disinfects work surfaces and, as antiseptics on skin.
  93. 93. Ethanol / Ethyl alcohol - Used as skin disinfectant. - Uses: Sterilizes skin before cutaneous injections. Disinfects thermometers. - Most effective at 50-70% -Effective against gram (+) , gram (-) bacteria.
  94. 94. Isopropyl alcohol - Most effective at 50-70% - Recommended as replacement for the sterilization of thermometers -Necrosis may result from absorption of vapours through the lungs during alcohol sponge bath.
  95. 95. 1.Acid & alkalies – Benzoic acid Lactic acid Acetic acid Propionic acid 2. Alcohol 3. Acetone
  96. 96. Agents: 1. Heavy metals 2. Oxidizing agents 3. Dyes 4. Alkylating agents
  97. 97. Heavy Metals • Mercurials • Mercuric chloride – very toxic disinfectant, not used today. • Metaphen, Merthiolate, Mercuchrome . • Silver compounds • Soluble silver salts or as colloidal preparations. • Silver nitrate – highly bactericdal for gonococci. • Silver sulfadiazine – topical cream for burn patients.
  98. 98. Oxidizing agent • Halogens (1) Iodine - As I2 at pH value below 6 where maximal bactericidal action takes place. - Destroys many microorganisms and viruses within 3-5 minutes. - Strong smell and can stain skin and clothings. - Skin irritant .
  99. 99. Betadine Solution - - - Iodophores Enhances stability Povidone –iodine -Available in "Swab Aid" pads, Swab Sticks and as a Surgical Scrub. - It is a fast-acting, broad-spectrum antiseptic . - Indicated for degerming skin, wounds and mucous membranes. - widely use in hospitals, sanitation and water purification.
  100. 100. (2) chlorine - Hypochlorite, inorganic ,inorganic chloramines. - The active moiety of hypochlorites and chlorine is hypochlorous acid. - Water disinfectant - Hypochlorites - most useful of the chlorine compound
  101. 101.  Widely used for sanitizing dairy products and food processing .  Employed as sanitizers in most households, hospitals, and public buildings  Marketed as: Chlorox, Zonrox, Purex
  102. 102. • Hydrogen peroxide - It is a weak acid. - Used in the cleansing of wounds. - It has strong oxidizing properties and is therefore a powerful bleaching agent that is mostly used for bleaching paper.
  103. 103. Dyes • Triphenyl methane dyes • Crystal violet, Malachite green, Brilliant green • Highly selective for gram (+) organisms • Used in the laboratory in the formulation of selective culture media • Acidine dyes • Often referred as Flavines . • Exerts a bactericidal and bacteriostatic effect. proflavine, acriflavine • used in wound antisepsis
  104. 104. Alkylating agent - Glutaraldehydes and formaldehydes . - Active against bacteria and their spores, viruses, fungi and protozoa. -These effects are mediated predominantly via amine, sulfurhydryl and carboxyl groups on microbial surface proteins.
  105. 105. Formaldehyde:- • Aqueous solution containing 37% formaldehyde (Formalin) • Paraformaldehyde a poymer (contain 9199% formaldehde) - Formalin - used for preserving fresh tissues - when used in high concentration, it destroys all organisms, including spores.
  106. 106. - Used to inactivate virus in the preparation of vaccines. - As a gas – used to decontaminate rooms, buildings, fabrics, and instruments..
  107. 107. Glutaraldehyde - used as “cold sterilant” for surgical instruments - 10x more effective than formaldehyde as a bactericidal and sporocidal agent and less toxic. Ethylene oxide - Employed in gaseous sterilization, especially on materials that would be damaged by heat (polyethylene tubings, drugs). - Active against all types of bacteria, including spores & TB bacilli.
  108. 108. Sterilization monitoring – Biological – Chemical – Physical /mechanical
  109. 109. Drying, cooling, storage and recycling of sterilized instruments
  110. 110. Causes of sterilization failure Improper loading of sterilization chamber Improper packing Improper timing improper temperature Improper cleaning of items to be sterilized.
  111. 111. DISINFECTING IMPRESSIONS Methods:1.Spraying 2.Dipping 3.Immersing Iodophors, sodium hypochlorite (1:10 concentration), chlorine dioxide, phenols, and other approved products are all acceptable.
  112. 112. IN ORTHODONTICS Orthodontic wires: Disinfected with Iodophor (10 minutes) Wiped with alcohol gauge ,dried Placed into paper storage envelopes
  113. 113. Wires can be sterilized by: AUTOCLAVE: 274 degrees-10 minutes. COLD STERILIZATION: Sporocidin solution,6.75 hrs DRY HEAT: 375 degrees-1o minutes Wires used are Nitinol,TMA,0.016 ss wire.
  114. 114. Pliers: Alcohol Cold sterilization Autoclave:250 degrees F, 1 atm-30 mins. Chemiclave:276 degrees F,1.36 atm,30 mins  Dryclave: 340 degrees F-I hour
  115. 115. Handpieces: Alcohol  Cold sterilization  Autoclave  Dryclave 
  116. 116. Molar bands: Cleaned by enzyme disinfectant(15 mins) Rinsed in running water(1 min) Sterilized by Autoclave(3 mins)
  117. 117. Orthodontic cutters:  Wrapped in polyethylene paper pouches  Autoclave  Chemiclave
  118. 118. Elastomeric ligatures: Banicide (0.5 % Glutaraldehyde)-10 mins Lysol Autoclave Dry heat
  119. 119. CONCLUSION As the saying goes-"Cleanliness is next to godliness." All general practitioners and specialists alike should be educated about aseptic techniques and their benefits so that the dental environment is less hazardous one to work in.
  120. 120. “PREVENTION IS BETTER THAN CURE”- a proverb well suited to sterilisation. DEADLY WORLD OF MICROBIAL PATHOGENS  Utilisation of proper sterilization, disinfectants and aseptic procedures helps us achieve the safety our profession demands .
  121. 121. REFERENCES Text Book Of Microbiology Ananthanarayan,6th edition Art And Science Of Operative Dentistry Sturdevant CDC. Guidelines for infection control in dental health-care settings – 2003. MMWR 2003; 52(No. RR-17):1–66. Available at
  122. 122. Centers for Disease Control and Prevention. Recommended infection control practices for dentistry 1993, MMWR 42 (RR-8):1-13. GlenA.Smith,Glenn R.Carey.Effect of clinical use and sterilization on selected arch wires.Am J Orthod Dentofac Orthop 102:153-159,1992. Robert G.Cash.Trends in Sterilization and Disinfection procedures.Am J Orthod Dentofac Orthop 98:292-299,1990.
  123. 123. Gilliam M.Antonios H. Mamandras.Infection control in Orthodontic office in Canada 112:275-281,1997. M.R.Fulford.Decontamination of tried in Orthodontic molar bands.Eur J Orthod25:621622,2003.
  124. 124. THANK YOU