DISINFECTION INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
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Hypersensitivity Refers to the injurious consequences in the sensitized host following contact with specific antigens. Incidence of Ni sensitivity Greg, Dulap, Moffa – allergic response to Ni containing dental alloys. www.indiandentalacademy.com
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Ni – moderately cytotoxic Cr
– little
Grimsdotir & Hansten – saliva -connecting medium – discharge of ions & metal compounds – combine with chemically corroded metal – attach to mucosa.
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Alan & Smith – incidence rate of hypersensitivity – 10%
Blane & Peltonon – estimated that 4.5 – 28.5 of popln – have sensitivity to Ni Higher prevalence in females Janson & Park – hypersensitivity in
females – related to environmental exposure – contact with detergents jewellery & other metallic objects
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Factors affecting development of
sensitization
Raitt and Brostoff – Mechanical irritation Skin laceration Increased environmental temperature Increased intensity and duration of
exposure Genetic factors
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Dietary intake
Ni - 200 – 300 micgms / day Cr – 250 micgms / day Drinking water – 20 micgms / l – Ni (Bencho )
Amount of Ni release Grims Dottar – largest amount of Ni – released
from facebow – silver solder Brackets -- .3-.9 micgms/day SS archwire -- .26 micgms/cm.sq/day www.indiandentalacademy.com
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Form
of release - Ni – soluble Cr – insoluble Allergy more common in extra oral -- intra oral appliances – 6 times
5-12 times higher conc needed – oral mucosa www.indiandentalacademy.com
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Lack of intra oral response due to Salivary glycoproteins -- barrier difference of permeability Cellular hypersensitivity btn skin & mucosa difference in Langerhans distribution
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No
increase in blood level of Ni – 5 months of Ortho t/t - Bishara
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Hypersensitivity reactions to Dental Alloys
Symptoms of allergic reactions – dental alloys Inflammed hyperplastic gingival tissue Alveolar bone loss -- crowns Edema of throat, palate, gums Osteomyelitis – SS bone fixation wires Orthodontic appliances – face bows & neck straps, Ni-Ti arch wires www.indiandentalacademy.com
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Symptoms Contact dermatitis, Contact stomatitis, Loss of taste, Numbness, burning sensn, Angular chelitis Severe gingivitis, Mild erythema with or without edema www.indiandentalacademy.com
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Immunologic mechanism Ni – common cause – contact dermatitis Delayed hypersensitivity reaction Induction phase Elucidation phase Diagnosis – ptn history clinical findings patch testing
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Different corrosion resistant materials – used in Hypersensitivity ptns AISI 316 L steel – most corrosion resistant AISI 304 L steel PIA 17 – 4 Bio force ion guard wire – 3 micron nitrogen coating Pyramid manufacturers – steel -- hypo allergic www.indiandentalacademy.com
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Conclusions The daily amount of Cr & Ni released – insignificant when compared with – daily dietary intake of these metals Such a small amount of release might produce sensitivity when the orthodontic appliance are in place for 2-3 years For an allergic reaction in the oral mucosa an antigen must be 5 – 12 times greater than that needed for a skin allergy www.indiandentalacademy.com
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ďƒ˜ Patients with fully banded & bonded
appliances did not show a significant increase in the Ni blood level during the 1 st 4-5 mnts of orthodontic therapy ďƒ˜ Orthodontic therapy using appliances made of alloys containing Ni-Ti did not result in significant increase in the blood levels of Ni. www.indiandentalacademy.com
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ďƒ˜ The release rates for full mouth
orthodontic appliances are less than 10% of the reported average daily dietary intake for Ni & .25% of those reported for Cr.
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DISINFECTION PROCEDURES
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Objective of sterilization –Removal of microorganisms or destroy them from materials or from areas since they cause contamination, infection and decay. In microbiology Surgery Drug & food
- to prevent contamination - to maintain asepsis -for ensuring the safety www.indiandentalacademy.com
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Definitions Sterilization
– The process by which
an article, surface, or medium is freed of all living microorganisms either in the vegetative or spore state Disinfection – The destruction or removal of all pathogenic organisms, or organisms capable of giving rise to infection www.indiandentalacademy.com
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Definitions Antisepsis
– used to indicate the prevention of infection, usually by inhibiting the growth of bacteria in wounds or tissues
Bactericidal agents Bacteriostatic agents www.indiandentalacademy.com
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Spaulding system ( 1972 )
Critical
- penetrate/touch broken skin or mucous membrane - must be sterilized Semicritical -touch intact mucous membrane - sterilize, high level disinfection Noncritical - surfaces do not touch mucous membrane - disinfection www.indiandentalacademy.com
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Heat Fast Reliable Inexpensive ( relatively )
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HEAT Factors determining the time & temperature for sterilization
Nature of heat – dry or moist Presence of organic matter Number of microorganisms present Characteristics of the organism Type of material from which the organisms have to be eradicated www.indiandentalacademy.com
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PHYSICAL CONTROL WITH HEAT
SUNLIGHT – Ultraviolet rays Typhoid bacilli exposed to sun on pieces of cloth were killed in 2 hours, where the controls kept in dark were alive after 6 days
DRYING - 4/5th of the bacterial cell is made-up of water
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Dry heat DIRECT FLAME Bunsen burner
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Incineration- soiled dressings,beddings
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HOT AIR OVEN Radiating dry heat 1600 C ( 3200 F) & 2 Hours useful for sterilizing dry powders, water free oily substances, many types of glass ware such as pipettes, flasks, and syringes. Advantage – non corrosive method www.indiandentalacademy.com
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Hot air oven
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Moist heat Temperatures below 1000C/ pasteurization Temperatures at 1000C/ boiling Steam at atmospheric pressure
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Pasteurization ( below 1000C ) Purpose – To reduce the bacterial population of a liquid such as milk Spores are not affected by pasteurization Holding method 62.90C for 30 minutes ( Mycobacterium tuberculosis & Coxiella burnetti ) Flash pasteurization – 71.60C for 15sec Ultra pasteurization – 820C for 3sec www.indiandentalacademy.com
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BOILING WATER (1000C) Denaturation of proteins Minimum exposure time – 30 minutes Less reliable Washing soda ( 2% conc.) may be added
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Fractional sterilization ( steam at atmospheric pressure ) ďƒ˜
Tyndallization ( John Tyndall )
ďƒ˜
Intermittent sterilization www.indiandentalacademy.com
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Free flowing steam at 1000C for 30 minutes on each of 3 successive days. First day - steam kills all organisms except spores, and it stimulates spores to germinate vegetative cells Second day
–vegetative cells are killed
Third day – kills the remaining cells
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AUTOCLAVE Moist heat In the form of pressurized steam increase in the pressure of the gas increase in the temperature As the water molecules in steam becomes more energized, their penetration increases www.indiandentalacademy.com
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Used for glassware, metal ware, blankets, intravenous solutions and a broad variety of other objects Pressure in autoclave - 15pds/sq. inch Temperature – 121.50C Time – 3 to 30 min www.indiandentalacademy.com
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Limitations Plastic ware melts in high heat sharp instruments become dull Oily substances cannot be treated Prevacuum autoclave Temperature - 1320C to 1340C Pressure – 28 to 30 lb/1n2 Time – 4minutes Advantage – minimal exposure time for sterilization www.indiandentalacademy.com
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Physical control by other methods
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FILTRATION
( 1980s )
filter technology – Charles Chamberland Julius petri Filter – a mechanical device used to remove microorganisms from a solution Ex; IV solutions,bacteriological media, toxoids, pharmaceuticals etc. www.indiandentalacademy.com
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Types of filters Candle filters 1.Unglazed ceramic filters Ex; Chamberland filter 2.Diatomaceous earth filters Ex; Berkefeld filter Asbestos filters-disposable Sintered glass filters Membrane filters www.indiandentalacademy.com
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Membrane filter technique
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ULTTRAVIOLET LIGHT Wave length Visible light is between 400 & 800nm Ultraviolet light is between 100 & 400 nm
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Demerits;
It is not effective against bacterial spores
Does not penetrate liquids or solids
It may cause damage to human cells
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Other types of radiation ďƒ˜
Ionizing radiation X-rays & gamma rays
Both have wavelengths shorter than the UV light They force electrons out of their shells, thereby creating ions www.indiandentalacademy.com
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ďƒ˜
Microwave - Wave length is longer than that of UV light - Molecules are set into a high speed motion
ďƒ˜
Laser beam Light Amplification by Stimulated Emission of Radiation
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ULTRASONIC VIBRATIONS High frequency sound waves beyond the range of the human ear MICROSCOPIC BUBBLES ‘-COLD BOILING Demerits Not very effective Liquid is required
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Physical agents of infection control Heat
- Sunlight - Drying - Dry heat ( flaming, incineration & hot air ) - Moist heat ( pasteurization, boiling, steam under normal pressure, steam under pressure ) Methods other than heat - Filtration - Radiation - Ultrasonic & sonic vibrations
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Chemical control of microorganisms
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Selection of antiseptics & disinfectants Prerequisites
It should have a wide spectrum of activity Fast acting Active in the presence of organic matter Nontoxic to animals or humans ( antiseptic ) Soluble in water It should not separate on standing Should have high penetrating power Surface compatibility Relatively inexpensive www.indiandentalacademy.com
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Factors Concentration of the substance Time pH of the medium Temperature Nature of microorganism
Presence of extraneous material www.indiandentalacademy.com
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Bacterial species
Resistance
Bacterial endospores Mycobacterium tuberculosis Small nonlipid viruses Fungi Medium sized lipid viruses Vegetative bacteria www.indiandentalacademy.com
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3 Levels of disinfection 1. High
- sterilizing agents ex; ethylene oxide gas 2. Intermediate - bactericidal agents ex; formaldehyde, alcohols 3. Low - narrowest anti-microbial activity ex; soaps, detergents www.indiandentalacademy.com
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Mechanisms of anti-microbial action Agents that interfere with membrane
function Agents that denatures proteins Agents that destroy or modify the functional groups of proteins www.indiandentalacademy.com
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1.
Agents that interfere with membrane function Structural derangement or disorganisation of cell wall proteins and lipids
Surface active agents Phenols Alcohols www.indiandentalacademy.com
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Surface active agents “Substances which alter energy relationship at interfaces producing a reduction of surface or interfacial tension”
Anionic Cationic Nonionic Amphoteric www.indiandentalacademy.com
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ďƒ˜ Cationic detergents
– quaternary ammonium compounds Ex; Acetyl trymethyl ammonium bromide & Benzalkonium chloride +vely charged hydrophylic portion reacts with membrane phospholipids Disadvantages ; Inability to penetrate organic debris www.indiandentalacademy.com
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Anionic detergents
– Soaps &fatty
Nonionic detergents
– Tween 80
acids Gross disruption of lipoprotein framework
relatively non toxic Amphoteric compounds
– gram+‘
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Soap – A chemical compound of fatty acids combined with potassium or sodium hydroxide
pH - 8.0 Mechanical removal of organisms Wetting agents Reduce surface tension www.indiandentalacademy.com
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PHENOL ( Carbolic acid ) LISTER-1865 Active against gram-positive bacteria Coagulating proteins esp. cell membrane Disadv; Expensive Pungent odour Caustic to the skin www.indiandentalacademy.com
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PHENOL DERIVATIVES
- Greater germicidal activity & lower toxicity BISPHENOLS - 2 phenol molecules ex; Hexachlorophene, Chlorhexidine FDA ( 1976 ) approved as a surgical scrub, hand wash, superficial skin wound cleanser Hexylresorcinol – mouthwash, topical antiseptic & in throat lozenges CRESOLS
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ALCOHOLS Effective skin antiseptics Ethyl alcohol - Denatures proteins and dissolves lipids - Dehydrating agent Readily reacts with organic matter 50-80% solution Isopropyl alcohol-high bactericidal activity Methylalcohol www.indiandentalacademy.com
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Agents that denatures proteins Denaturation of polypeptide chain Unfolding of polypeptide chain Ex;
Acids Alkalies Alcohols Acetone Organic solvents www.indiandentalacademy.com
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Agents that destroy or modify the functional groups of proteins
Mercuric compounds – sulphydryl groups Anionic detergents - amino & imidazole groups
Ex;
heavy metalshalogens hydrogen peroxide
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Heavy metals ‘An electron donating element whose atoms are large, with complex electron arrangements’ Heavy metals are very reactive with proteins Soluble salts of Hg,Ag & Cu
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OXIDISING AGENTS Halogens – ’ Chlorine – gasseous form, organic & inorganic compounds chlorine is available in 3 other forms 1. Hypochlorites 2. Organic chloramines 3. Inoganic chloramines www.indiandentalacademy.com
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Chlorine compounds 1.Ca(Ocl)2 - Chlorinated lime 2. NaOCl - DAKIN’s solution used to treat ‘ATHLETE’s foot
4. Chloramines – Chloramine-T- wound antisepsis www.indiandentalacademy.com
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Iodine More reactive than chlorine Tincture of iodine –2% iodine solution in ethyl alcohol
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Iodophors
‘Iodine detergent complexes that release iodine over a long period of time’ Advantage – no staining of tissues or fabrics Ex; wescodyne - preoperative skin preparation Betadine - local wound dressing Ioprep - presurgical scrubbing www.indiandentalacademy.com
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Hydrogen peroxide ( H2O2 )
A simple chemical compound digested by catalase to water and oxygen Mechanical removal of microorganisms New forms – super D H2O2
Heat sensitive plastics
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DYES Tryphenylmethane dyes/Aniline dyes EX; Brilliant green, Malachite green, Crystal violet & Gention violet Interference with cell wall synthesis Gram +ve organisms Acrydine dyes – Flavines Ex; Acriflavine, Proflavine Combines with DNA, thereby halting RNA synthesis Both gram +ve and –ve organisms
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ALKYLATING AGENTS Formaldehyde Ethylene oxide Gluteraldehyde
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Formaldehyde Gas at high temperatures & a solid at room temperatures 37% solution – Formalin In gaseous form - Sterilize surgical equipment & medical instruments 20% solution in 70% alcohol for 18hrs – to sterilize instruments www.indiandentalacademy.com
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Ethylene oxide Toxic & Highly explosive Paper, leather, wood, metal, rubber & plastics Gas autoclaves & chemiclave Catheters,artificial heart vaves
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Gluteraldehyde
2 to 3.4% is effective Activity will not reduce in the presence of organic matter It does not damage delicate objects Irritating fumes Discoloration & corrosion of instruments www.indiandentalacademy.com
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Agents interfere with membrane function - surface active agents - phenols - alcohols Agents denatures proteins - acids & alkalies Agents destroy or modify the functional groups of proteins - heavy metals - oxidizing agents ( halogens, H2O2 ) - dyes - alkylating agents ( formaldehyde, ethylene oxide, gluteraldehyde ) www.indiandentalacademy.com
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INSTRUMENT DISINFECTION
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The overall process consists of
Holding ( presoaking ) Precleaning Corrosion control, drying, lubrication Packaging Sterilization Sterilization monitoring Handling processed instruments www.indiandentalacademy.com
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HOLDING (PRESOAKING ) Holding solution– detergent/water/enzyme solution To prevent drying Perforated basket Extended soaking www.indiandentalacademy.com
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PRECLEANING
Ultrasonic cleaning - reduces direct handling - time saving Manual scrubbing - dangerous - long handled brush Instrument washers
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Ultrasonic cleaning of instruments
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Corrosion control, drying, lubrication Steam sterilization causes corrosion
Rust inhibitors – silver nitrite
Drying remove excess water
Hinged instruments – lubrication www.indiandentalacademy.com
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ďƒ˜
Packaging Prevents contamination after sterilization, during storage or when being distributed to chair side
ďƒ˜
Pouches, bags, cassettes ( stainless steel, aluminum, and plastic/resin )
ďƒ˜
Closed containers www.indiandentalacademy.com
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Resin cassettes
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Types of sterilization 1. Heat sterilization – moist heat - dry heat - unsaturated chemical vapor 2. Liquid chemical sterilization 3. Gas sterilization
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Steam sterilization Heating water to generate steam in a closed chamber producing a moist heat that rapidly kills microorganisms 4 cycles – 1. Heat-up cycle 2. Sterilizing cycle 3. Depressurization cycle 4. Drying cycle
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Small office sterilizer
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Unsaturated chemical vapor sterilization ( chemiclave ) Heating a special chemical solution Solution – 0.23% formaldehyde & 72.38% ethanol plus acetone, ketone, water & other alcohols 4 cycles 1. Heat-up/vaporization cycle 2. Sterilization cycle 3. Depressurization cycle 4. Optional purge cycle www.indiandentalacademy.com
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CHEMICLAVE
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Temperature - 2700 F( 1320 C ) Pressure - 25 psi ( 172 Kpa.) Time - 20 min Positive feature – corrosion is reduced or completely eliminated Negative feature – irritating fumes www.indiandentalacademy.com
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Dry heat sterilization Heating air with transfer of heat energy from air to the instruments Requires high temperatures Temperature – 3200F to 3750F ( 1600C to 1900C) Adv; No corrosion No irritating fumes www.indiandentalacademy.com
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Static air type dry heat sterilizer Heat energy from static air is transferred to the instrument
Heat-up cycle begins 15 to 30min from a www.indiandentalacademy.com cold start
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Forced air type dry heat sterilizer It circulates the heated air through out the chamber at a high velocity Packaged items -12min Unpackaged items - 6min www.indiandentalacademy.com
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GAS STERILIZATION Ethylene oxide Adv; low temperatures ( below room temp. ) Disadv; time consuming explosive if mixed with air toxicity LIQUID CHEMICAL STERILIZATION 2 to 3.4% gluteraldehyde www.indiandentalacademy.com
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RECENT ADVANCES Low temperature sterilization involves vaporized H2O2 Bead sterilizers Size of glass beads – 1.2 to 1.5mm Temperature - 4240 to 4500F Time - 3 to 5sec Disadv ; uneven temperatures www.indiandentalacademy.com
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Sterilization monitoring Sterilization failures – improper cleaning, packaging, use of sterilizer Helps to achieve high level of sterility Biologic Chemical Physical www.indiandentalacademy.com
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Biologic monitoring - Bac. Stearothermophilus (steam/chemical vapor ) - Bac. Subtilis ( dry heat/ethylene oxide gas )
Chemical monitoring - rapid change indicator ex; autoclave tape, special markings on the bags - slow change or integrated indicator
Physical monitoring –temperature, pressure, exposure time www.indiandentalacademy.com
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Handling processed instruments
Drying Cooling Storage
Shelf life – the period of time during which sterility is assumed to be maintained www.indiandentalacademy.com
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Sterilization in Orthodontics
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Types of disinfections used in dentistry 1.
Surface disinfections: Environmental surfaces like cabinets, chairs, units, lights, X-rays. Spraying or wiping the solution on the surface. 2. Immersion disinfections:Immersion of instruments and plastics and other smaller items in a liquid disinfectant. Time:- 5 to 30min www.indiandentalacademy.com
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3.
Immersion sterilization: Agent has the capability of killing all micro organisms and infective agents. Time:- 6 to 10hrs. 4. Hand antimicrobial treatment:-
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BIOLOGICAL CONTAMINANTS:(JCO ’88)
AGENT. SURVIVALTIME
DISEASE •
ESTIMATED AT ROOMTEMPERATURE:
VIRUSES:HAV
Hepatitis A
Months
HBV
Hepatitis B
Weeks
Respiratory
Pneumonias,
Hours
Viruses
Common cold
Herpes simplex 1,2
Skin, oral, eye, genital infections
Seconds or minutes.
Mumps virus
Parotities
Hours
HIV
AIDS www.indiandentalacademy.com
Less than HBV
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BACTERIA:-
Mycobacterium weeks Tuberculosis
Staphylococcus Aurous
Skin, lung infections
Streptococcus Pyogens
“Streptococcal Throat”, Hours to days scarlet fever
Mycoplasma Phenmoniae
Lung infection
Seconds or minutes
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Tuberculosis
Days to
Days
Trends in sterilization and disinfections procedures in orthodontic clinics (Robert G.Cash:Am.J.Orthod.1990) Greater use of ;-
Gloves Masks and gowns Protective eye wear. Increased use of diff. Types of heat
sterilization. Increase in disinfections of alginate impression www.indiandentalacademy.com
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ďƒ˜ Comparison of infection control practices
of orthodontists and general dentists:(- Mc Carthy, et al: Am.J.Orthod ’97) Greater compliance with sterilization recommendations,including protective barriers among general dentists than orthodontists
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Corrosion of instruments:(Masunaga JCO ’87) Solution corrosion Debris (interface corrosion) Heat Stress corrosion Conc. Cell corrosion
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Corrosion of instruments Prevention of corrosion during auto
claving:-Clean instruments thoroughly; rinse with distilled water. -Ultrasonic cleaner to remove debris. -Autoclave steam should be deionized -PH < 6.4 – pitting, corrosion Chrome plate instruments: Separate autoclaving. www.indiandentalacademy.com
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Instruments not be laid on each other Detergents with chloride bases should not
be used (HCI formed). PH > 8.5disrupts chromium oxide layer detergents containing amines:- purple or black stains.
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Sterilization of orthodontics instruments and bands in cassettes:(Holt, Miller, et al Am.J.Orthodo ’90) Contaminated instruments and bands sterilized in cassettes.
Steam autoclave Chemical vapour sterilization Dry heat sterilization.
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Glass bead sterilization of orthodontic bands:- (smith Am J Orthod ’86) 15 Sec – Bacteria 45 Sec – Spores
226 C 5 sec. Tap water, 10 sec. Soap scrub, 30min:alcohol immersion – ineffective disadvantages: Temp. variation Instrument size
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Types of sterilization on orthodontic Pliers:(Mazzocchi. et al JCO ’94) Auto Clave - 250F, 1atm, for 30min Chemiclave - 270F, 1.36atm, 20min Dry heat unit - 340F, 1hr. 500 cycles Dry heat sterilizer :-
No. of instruments - less. Longer cycle with wrapped instruments www.indiandentalacademy.com
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Auto clave:-
Corrosion by water. Chemiclave:- decreased corrosion Lubrication of instrument hinges:Avoid oils. Hardness after 500 cycles:Autoclave>chemiclave>dry heat Tarnish:- worst with chemiclave
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Conclusion ď&#x192;&#x2DC; Clinical& metallurgical modifications of
orthodontic pliers after 500 cycles of sterlization are negligible
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Comparison of 3 dry heat convection sterilizers Cox sterilizer Dentronix Farber ware –
Results – all 3 units 100% successful
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Results
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Sterlization of heat sensitive instruments
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ADA RECOMMENDATIONS FOR STERILIZATION AND DISINFECTION OF DENTAL INSTRUMETNS, MATERIALS AND COMMONLY USED ITEMS:
Stainless steel hand instruments.
-Autoclave. Stainless steel impression trays, -Autoclave, vapoclave, glutaraldehyde Plastic impression trays:-Vapoclave, glutaraldelyde Suction tips -Glutaraldehyde -Preferably disposable. www.indiandentalacademy.com
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•
3 way syringe:- Vapoclave, glutaraldehyde Orthodontic pliers:-Autoclave, vapoclave Reuse of materials like preformed bands, NiTi wires:-Vapoclave, glutaraldehyde
Advised not to reuse • Accessories like E-chain, Lig--rings, ligature wires, springs, etc:
Vapoclave
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â&#x20AC;˘
Welder points:-Vapoclave
â&#x20AC;˘
Welder to be scrubbed with pure spirit.
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DISINFECTANTS IN THE DENTAL LAB:IMPRESSIONS:-
Alginate:Sodium hypo chlorite Chlorine dioxide Phenols Iodophors Polysulphide:Sodium hypochlorite Chlorine dioxide Phenols www.indiandentalacademy.com
Sprays
Immersed121
Gypsum casts â&#x20AC;&#x201C; iodophor
sprayed or soaked
Resin dentures sodium hypochlorite
immersed
Wax records iodophor sodium hypochlorite
immersed
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INFECTION CONTROL IN THE DENTAL OFFICE Patients should be treated as if they are
infected with blood borne pathogens such as HBV or HIV health care workers – immunized
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ď&#x192;&#x2DC; Before t/t
â&#x20AC;&#x201C; thorough medical history - place disposable coverings
During t/t - use protective wear - minimize formation of droplets and aerosols - high vacuum evacuation - protect hands www.indiandentalacademy.com
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After t/t
- clean instruments thoroughly - sterilize instruments - biological monitoring – once
weekly - dispose contaminated waste – that cannot be sterilized or disinfected www.indiandentalacademy.com
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Common causes of sterilization failure Cycle time too short Temp. too low Failure to preheat sterilizer Faulty sterilizer Interruption of cycle Overloading of chamber Improper precleaning , packaging , or
sterilization procedures.
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References
Orthodontic biomaterials from past to present – Robert P Kusy , Angle – orthod may 2000 Future of orthodontic materials – The long term view – Robert P Kusy , Am j orthod 1998 ; 113 : 91-95 Changes in bracket slot tolerence following recycling of direct bond metallic orthodontic appliances – Mark . E Hixon Comparison of ion release from new and recycled orthodontic brackets – Tsui-Huang , Am J Orthod – 2001 ; 120:68-75 www.indiandentalacademy.com
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References
Effects of recycling on the mechanical properties and surface topography of nickel titanium alloy wires – Sung Ho Lee , Am J Orthod 2001;120:654-663 Effects of clinical recycling on mechanical properties of Niti alloy wires – Sunil Kapila, Scott Anderson , Am J Orthod 1991;100:428-435 Nickel hypersensitivity in the orthodontic patient – Justin Bass , Am J Orthod 1993;103:280-85 Tissue reactions to othodontic adhesives – William Davidson Effects of sterilzation on the mechanical properties and surface topography of Niti arch wires – Am J Orthod ; 1998:93:232-36 www.indiandentalacademy.com
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Biodegradation of orthodontic appliances – Part 1 Biodegradation of Ni & Cr in vitro. Barret , Bishara , Am J Orthod 1993; 103: 8 -14 Biodegradation of orthodontic appliances.Part 2 Changes in blood level of Ni. Barret , Bishara , Am J Orthod 1993; 103:115-9. In vitro release of Ni & Cr from simulated orthodontic appliances. HY Park Am J Orthod Metal release from simulated fixed orthodontic appliances. Chung Hwang. Am J Orthod , 2001;120:383-91 . www.indiandentalacademy.com
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Force application and decay characterstics of untreated and treated polyurethrane elastomeric chains, Stevenson, Robert Kusy, Angle orthod 1994; 64:455-456 Fibre reinforced composites in dentistry. Charles Burstone. JCO May 2000 The effects of 2% alkaline glutaraldehyde solution on the elastic properties of elastomeric chain. Angle Orthod, May 1990. www.indiandentalacademy.com
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References
Trends in sterilization procedures and disinfection procedures in orthodontic offices- Robert.G.cash. – AJODO ;1990.Vol.98
Glass bead sterilization of orthodontic bands AJODO; Sept 1986 -Gerald.E.Smith -
Sterilization of orthodontic instruments in cassettes AJODO; Nov 1990- W.F.Hohlt, C.H. Miller-
-
Infection control in the orthodontic office in Canada AJODO Sept.1997- G.M.Mccarthy A.H.Mamandras -
-
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References
Text book of microbiology -R.Ananthnarayan & C.K.J.Paniker Infection control & office safety - DCNA ( 1991 April ) Infection control - C.H.Miller Fundamentals of microbiology - Edward Alcamo Microbiology - W.K.Joklik & H.P.Willett
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www.indiandentalacademy.com Leader in continuing dental education
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