STERILISATION &
DISINFECTION
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www....
Objective of sterilization
–Removal of microorganisms or destroy
them from materials or from areas since they
cause contam...
Definitions
Sterilization – The process by which an
article, surface, or medium is freed of all living
microorganisms eith...
Definitions
Antisepsis – used to indicate the prevention of
infection, usually by inhibiting the growth of
bacteria in wou...
Spaulding system ( 1972 )


Critical

- penetrate/touch broken skin or
mucous membrane
- must be sterilized
 Semicritica...
Heat
 Fast

 Reliable
 Inexpensive

( relatively )

THERMAL DEATH TIME
THERMAL DEATH POINT

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HEAT
Factors determining the time & temperature
for sterilization






Nature of heat – dry or moist
Presence of org...
PHYSICAL CONTROL WITH HEAT


SUNLIGHT – Ultraviolet rays
Typhoid bacilli exposed to sun on pieces of
cloth were killed in...
Dry heat
DIRECT FLAME
Bunsen burner

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Incineration

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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,...
Hot air oven

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Moist heat
below 1000C/ pasteurization
 Temperatures at 1000C/ boiling
 Steam at atmospheric pressure
 Temperatures

ww...
Pasteurization ( below 1000C )
Purpose – To reduce the bacterial population of a
liquid such as milk
Spores are not affect...
BOILING WATER (1000C)
Lower temperatures & less time of exposure are
required
Denaturation of proteins
Minimum exposure ti...
Fractional sterilization ( steam at atmospheric
pressure )


Tyndallization
( John Tyndall )



Intermittent
sterilizati...
Free flowing steam at 1000C for 30 minutes on
each of 3 successive days.
First day
- steam kills all organisms except
spor...
AUTOCLAVE
Moist heat In the form of pressurized steam
increase in the pressure of the gas
increase in the temperature
As t...
Used for glassware, metal ware, blankets,
intravenous solutions and a broad variety of
other objects
Pressure in autoclave...
Limitations
 Plastic ware melts in high heat
 sharp instruments become dull
 Oily substances cannot be treated
Prevacuu...


HOT OIL

1600C for 1 hour
Advantages – no rusting of instruments
minimal corrosion
 SILICON

www.indiandentalacademy.c...
Physical control by other
methods

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FILTRATION

( 1980s )

filter technology – Charles Chamberland
Julius petri
Filter – a mechanical device used to remove
mi...
Types of filters
 Candle filters 1.Unglazed ceramic filters
Ex; Chamberland filter
2.Diatomaceous earth filters
Ex; Berke...
Membrane filter technique

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ULTRASONIC LIGHT
Wave length
Visible light is between 400 & 800nm
Ultraviolet light is between 100 & 400 nm

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Mechanism of action
When microorganisms are subjected to UV light
linking of thymine molecules occurs
Demerits;


It is n...
Other types of radiation


Ionizing radiation
X-rays & gamma rays

Both have wavelengths shorter than the UV light
They f...


Microwave
- Wave length is longer than that of UV light
- Molecules are set into a high speed motion



Laser beam
Lig...
ULTRASONIC VIBRATIONS
High frequency sound waves beyond the range of the
human ear
„Cold boiling‟
They cause the formation...
www.indiandentalacademy.com
Preservation methods ( bacteriostatic )
Retard spoilage & prolong the shelflife of foods


Drying
 Salting - osmosis
 F...
Physical agents of infection
control
Heat

- Sunlight
- Drying
- Dry heat ( flaming, incineration & hot air )
- Moist heat...
Chemical control of
microorganisms

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Chemical control of
microorganisms
Puerperal fever ( childbed fever )
– a blood disease accompanied
by high fever and ofte...
General principles of chemical
control
Egyptians – resins & aromatics
Ancient people burned sulfur for deodorizing and
san...
Selection of antiseptics &
disinfectants
Prerequisites










It should have a wide spectrum of activity
Fast ...
Factors
 Concentration of the substance
 Time
 pH of the medium
 Temperature
 Nature of microorganism
 Surface to be...
Evaluation of antiseptics &
disinfectants
Phenol Coefficient ( PC )
- A measure of the effectiveness of an
antiseptic or d...
Bacterial species

Resistance

Bacterial endospores
Mycobacterium tuberculosis
Small nonlipid viruses
Fungi
Medium sized l...
3 Levels of disinfection
1. High

- sterilizing agents
ex; ethylene oxide gas
2. Intermediate - bactericidal agents
ex; fo...
Mechanisms of anti-microbial action
 Agents

that interfere with membrane
function
 Agents that denatures proteins
 Age...
1.

Agents that interfere with membrane
function
Structural derangement or disorganisation of
cell wall proteins and lipid...
Surface active agents
“Substances which alter
energy relationship at interfaces producing a
reduction of surface or interf...
Cationic detergents – quaternary ammonium
compounds
Ex; Acetyl trymethyl ammonium bromide &
Benzalkonium chloride
+vely ch...


Anionic detergents
– Soaps &fatty acids
Gross disruption of lipoprotein framework



Nonionic detergents – Tween 80
re...
Soap

– A chemical compound of fatty acids
combined with potassium or sodium hydroxide


pH - 8.0
 Mechanical removal of...
PHENOL ( Carbolic acid )
 Active against gram-positive bacteria
 Coagulating proteins esp. cell membrane
 Used in PC te...
PHENOL DERIVATIVES




- Greater germicidal activity &
lower toxicity
BISPHENOLS - 2 phenol molecules
ex; Hexachlorophen...
ALCOHOLS
Effective skin antiseptics
 Ethyl alcohol - Denatures proteins and
dissolves lipids
- Dehydrating agent
Readily ...
Agents that denatures proteins
Denaturation of polypeptide chain
Unfolding of polypeptide chain
Ex;

Acids
Alkalies
Alcoho...
ACIDS & ALKALIES
Free H+ and OH- ions

All organic acids – food preservatives
Ex; benzoic acid, propionic acid
Acids are v...
Agents that destroy or modify the
functional groups of proteins
Mercuric compounds – sulphydryl groups
 Anionic detergent...
Heavy metals
„An electron donating element whose atoms are
large, with complex electron arrangements‟

„Oligo-dynamic acti...
Mercury (Hgcl2)
- Skin diseases
- Toxic to the host
- antimicrobial activity is reduced in the
presence of organic matter
...
Silver  AgNO3

- antiseptic & disinfectant
- 1% AgNo3 solution is active against
Neisseria Gonorrhoeae infection
- to tre...
OXYDISING AGENTS
Halogens –
„A group of highly reactive elements whose
atoms have 7 electrons in the outer shell‟
 Chlori...
Chlorine compounds
1.Ca(Ocl)2 - Chlorinated lime
2. NaOCl - DAKIN‟s solution used to treat
„ATHLETE‟s foot
3. Clorax & Pur...
Iodine
More reactive than chlorine
Halogenating tyrosine portions of protein
molecules
Tincture of iodine –2% iodine solut...


Iodophors

„Iodine detergent complexes that release iodine
over a long period of time‟
Advantage – no staining of tissu...
Hydrogen peroxide ( H2O2 )


A simple chemical compound digested by
catalase to water and oxygen
 Mechanical removal of ...
DYES
 Tryphenylmethane dyes/Aniline dyes
EX; Brilliant green, Malachite green, Crystal violet &
Gention violet
Interferen...
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 s...







Ethylene oxide
Toxic & Highly explosive
Freon gas in cryoxide / CO2 gas in carboxide
Cold burns
Paper, leathe...
Gluteraldehyde






2 to 3.4% is effective
Activity will not reduce in the presence of organic
matter
It does not da...





Agents interfere with membrane function
- surface active agents
- phenols
- alcohols
Agents denatures proteins - a...
INSTRUMENT
PROCESSING

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The overall process consists of









Holding ( presoaking )
Precleaning
Corrosion control, drying, lubrication
...
HOLDING (PRESOAKING )
 Holding solution–
detergent/water/enzyme
solution
 To prevent drying
 Perforated basket
 Extend...
PRECLEANING


Ultrasonic cleaning - reduces direct handling
- time saving
 Manual scrubbing - dangerous
- long handled b...
Ultrasonic cleaning of instruments

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Corrosion control, drying, lubrication
 Steam sterilization causes corrosion


Rust inhibitors – silver nitrite



Dryi...
Packaging
 Prevents contamination after sterilization, during
storage or when being distributed to chair side


Pouches,...
Resin cassettes

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SRERILIZATION
Universal sterilization
“if it can be sterilized, sterilize it”
Sterility assurance
- the correct performanc...
Types of sterilization
1. Heat sterilization – moist heat
- dry heat
- unsaturated chemical vapor
2. Liquid chemical steri...
Steam sterilization
Heating water to generate steam in a
closed chamber producing a moist heat that
rapidly kills microorg...
Small office sterilizer

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Unsaturated chemical vapor sterilization
( chemiclave )
Heating a special chemical solution
Solution – 0.23% formaldehyde ...
CHEMICLAVE

www.indiandentalacademy.com
Temperature - 2700 F( 1320 C )
Pressure
- 25 psi ( 172 Kpa.)
Time
- 20 min

Positive feature – corrosion is reduced or
com...
Dry heat sterilization
Heating air with transfer of heat energy from air to
the instruments
Requires high temperatures
Tem...
Static air type dry heat sterilizer
Heat energy from static
air is transferred to the
instrument

Heat-up cycle begins 15 ...
Forced air type dry heat sterilizer
It circulates the heated air
through out the chamber
at a high velocity
Packaged items...
GAS STERILIZATION
Ethylene oxide
Adv; low temperatures ( below room temp. )
Disadv; time consuming
explosive if mixed with...
RECENT ADVANCES
 Low temperature sterilization involves
vaporized H2O2
 Bead sterilizers
Size of glass beads – 1.2 to 1....
Sterilization monitoring
Sterilization failures – improper cleaning,
packaging, use of sterilizer
Helps to achieve high le...


Biologic monitoring
- Bac. Stearothermophilus (steam/chemical vapor )
- Bac. Subtilis ( dry heat/ethylene oxide gas )

...
Handling processed instruments


Drying
 Cooling
 Storage
Shelf life – the period of time during which sterility
is ass...
References






Text book of microbiology
-R.Ananthnarayan & C.K.J.Paniker
Infection control & office safety
- DCNA ...
References


Robert.G.cash.- Trends in sterilization procedures and
disinfection procedures in orthodontic offices
– AJOD...
Thank you
For more details please visit
www.indiandentalacademy.com

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Sterilisation & disinfection /certified fixed orthodontic courses by Indian dental academy

  1. 1. STERILISATION & DISINFECTION INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Objective of sterilization –Removal of microorganisms or destroy them from materials or from areas since they cause contamination, infection and decay. In microbiology - to prevent contamination Surgery - to maintain asepsis Drug & food -for ensuring the safety www.indiandentalacademy.com
  3. 3. 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  Sanitization - This term is sometimes used as a synonym for disinfection, particularly used with reference to food processing & catering  www.indiandentalacademy.com
  4. 4. Definitions Antisepsis – used to indicate the prevention of infection, usually by inhibiting the growth of bacteria in wounds or tissues SEPS ( A Greek word ) – PUTRID   Bactericidal agents  Bacteriostatic agents  Cleaning  Degerming www.indiandentalacademy.com
  5. 5. 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
  6. 6. Heat  Fast  Reliable  Inexpensive ( relatively ) THERMAL DEATH TIME THERMAL DEATH POINT www.indiandentalacademy.com
  7. 7. 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
  8. 8. 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 www.indiandentalacademy.com
  9. 9. Dry heat DIRECT FLAME Bunsen burner www.indiandentalacademy.com
  10. 10. Incineration www.indiandentalacademy.com
  11. 11. 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
  12. 12. Hot air oven www.indiandentalacademy.com
  13. 13. Moist heat below 1000C/ pasteurization  Temperatures at 1000C/ boiling  Steam at atmospheric pressure  Temperatures www.indiandentalacademy.com
  14. 14. 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
  15. 15. BOILING WATER (1000C) Lower temperatures & less time of exposure are required Denaturation of proteins Minimum exposure time – 30 minutes Less reliable Washing soda ( 2% conc.) may be added www.indiandentalacademy.com
  16. 16. Fractional sterilization ( steam at atmospheric pressure )  Tyndallization ( John Tyndall )  Intermittent sterilization www.indiandentalacademy.com
  17. 17. 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 www.indiandentalacademy.com
  18. 18. 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
  19. 19. 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
  20. 20. 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
  21. 21.  HOT OIL 1600C for 1 hour Advantages – no rusting of instruments minimal corrosion  SILICON www.indiandentalacademy.com
  22. 22. Physical control by other methods www.indiandentalacademy.com
  23. 23. 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
  24. 24. Types of filters  Candle filters 1.Unglazed ceramic filters Ex; Chamberland filter 2.Diatomaceous earth filters Ex; Berkefeld filter  Asbestos filters  Sintered glass filters  Membrane filters www.indiandentalacademy.com
  25. 25. Membrane filter technique www.indiandentalacademy.com
  26. 26. ULTRASONIC LIGHT Wave length Visible light is between 400 & 800nm Ultraviolet light is between 100 & 400 nm www.indiandentalacademy.com
  27. 27. Mechanism of action When microorganisms are subjected to UV light linking of thymine molecules occurs Demerits;  It is not effective against bacterial spores  Does not penetrate liquids or solids  It may cause damage to human cells www.indiandentalacademy.com
  28. 28. Other types of radiation  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
  29. 29.  Microwave - Wave length is longer than that of UV light - Molecules are set into a high speed motion  Laser beam Light Amplification by Stimulated Emission of Radiation www.indiandentalacademy.com
  30. 30. ULTRASONIC VIBRATIONS High frequency sound waves beyond the range of the human ear „Cold boiling‟ They cause the formation of bubbles or cavities and the water appears to boil - cavitation Demerits  Not very effective  Liquid is required www.indiandentalacademy.com
  31. 31. www.indiandentalacademy.com
  32. 32. Preservation methods ( bacteriostatic ) Retard spoilage & prolong the shelflife of foods  Drying  Salting - osmosis  Freezing – lowering temperature www.indiandentalacademy.com
  33. 33. 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 Preservation methods - Drying - Salting - Freezing www.indiandentalacademy.com
  34. 34. Chemical control of microorganisms www.indiandentalacademy.com
  35. 35. Chemical control of microorganisms Puerperal fever ( childbed fever ) – a blood disease accompanied by high fever and often transmitted during child birth  Ignaz semmelweis - “savior of mothers” www.indiandentalacademy.com
  36. 36. General principles of chemical control Egyptians – resins & aromatics Ancient people burned sulfur for deodorizing and sanitary purposes Spices –preservatives as well as masks for foul odors Medicinal chemicals - 1800s U.S.Pharmacopia ( 1830 ) – tincture of iodine Copper sulphate – fungal infections Mercury – syphilis Joseph Lister (1860s) – principles of aseptic surgery( phenol ) www.indiandentalacademy.com
  37. 37. 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
  38. 38. Factors  Concentration of the substance  Time  pH of the medium  Temperature  Nature of microorganism  Surface to be treated  Presence of extraneous material www.indiandentalacademy.com
  39. 39. Evaluation of antiseptics & disinfectants Phenol Coefficient ( PC ) - A measure of the effectiveness of an antiseptic or disinfectant as compared to phenol sta. Aureus, sal. typhi Drawback – it does not consider factors like tissue toxicity, presence of organic matter  In-use test www.indiandentalacademy.com
  40. 40. Bacterial species Resistance Bacterial endospores Mycobacterium tuberculosis Small nonlipid viruses Fungi Medium sized lipid viruses Vegetative bacteria www.indiandentalacademy.com
  41. 41. 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
  42. 42. 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
  43. 43. 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
  44. 44. 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
  45. 45. 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 Incompatibility with anionic agents  www.indiandentalacademy.com
  46. 46.  Anionic detergents – Soaps &fatty acids Gross disruption of lipoprotein framework  Nonionic detergents – Tween 80 relatively non toxic  Amphoteric compounds – „TEGO‟ compounds www.indiandentalacademy.com
  47. 47. 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
  48. 48. PHENOL ( Carbolic acid )  Active against gram-positive bacteria  Coagulating proteins esp. cell membrane  Used in PC test Disadv;  Expensive  Pungent odour  Caustic to the skin www.indiandentalacademy.com
  49. 49. 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 www.indiandentalacademy.com
  50. 50. ALCOHOLS Effective skin antiseptics  Ethyl alcohol - Denatures proteins and dissolves lipids - Dehydrating agent Readily reacts with organic matter 50-80% solution  Isopropyl alcohol  Methylalcohol www.indiandentalacademy.com
  51. 51. Agents that denatures proteins Denaturation of polypeptide chain Unfolding of polypeptide chain Ex; Acids Alkalies Alcohols Acetone Organic solvents www.indiandentalacademy.com
  52. 52. ACIDS & ALKALIES Free H+ and OH- ions All organic acids – food preservatives Ex; benzoic acid, propionic acid Acids are valuable adjuncts to disinfection www.indiandentalacademy.com
  53. 53. Agents that destroy or modify the functional groups of proteins Mercuric compounds – sulphydryl groups  Anionic detergents - amino & imidazole groups  Ex; heavy metals halogens hydrogen peroxide www.indiandentalacademy.com
  54. 54. Heavy metals „An electron donating element whose atoms are large, with complex electron arrangements‟ „Oligo-dynamic action‟ Heavy metals are very reactive with proteins www.indiandentalacademy.com
  55. 55. Mercury (Hgcl2) - Skin diseases - Toxic to the host - antimicrobial activity is reduced in the presence of organic matter Copper - chlorophyll containing organisms - CuSO4 is a potent inhibitor of algae - BORDEAUX mixture www.indiandentalacademy.com
  56. 56. Silver  AgNO3 - antiseptic & disinfectant - 1% AgNo3 solution is active against Neisseria Gonorrhoeae infection - to treat suturing threads  Colloidal preparation  Not sporicidal www.indiandentalacademy.com
  57. 57. OXYDISING AGENTS Halogens – „A group of highly reactive elements whose atoms have 7 electrons in the outer shell‟  Chlorine – gasseous form, organic & inorganic compounds chlorine is available in 3 other forms 1. Hypochlorites 2. Organic chloramines 3. Inoganic chloramines www.indiandentalacademy.com
  58. 58. Chlorine compounds 1.Ca(Ocl)2 - Chlorinated lime 2. NaOCl - DAKIN‟s solution used to treat „ATHLETE‟s foot 3. Clorax & Purex bleach 4. Chloramines – Chloramine-T www.indiandentalacademy.com
  59. 59. Iodine More reactive than chlorine Halogenating tyrosine portions of protein molecules Tincture of iodine –2% iodine solution in ethyl alcohol www.indiandentalacademy.com
  60. 60.  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 - presurgical scrubbing Ioprep - local wound antiseptic www.indiandentalacademy.com
  61. 61. 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 www.indiandentalacademy.com
  62. 62. 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 www.indiandentalacademy.com
  63. 63. ALKYLATING AGENTS  Formaldehyde  Ethylene oxide  Gluteraldehyde www.indiandentalacademy.com
  64. 64. 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 Contact dermatitis www.indiandentalacademy.com
  65. 65.       Ethylene oxide Toxic & Highly explosive Freon gas in cryoxide / CO2 gas in carboxide Cold burns Paper, leather, wood, metal, rubber & plastics Gas autoclaves & chemiclave Beta propiolactone( BPL ) – Vaccines, sera, & surgical ligatures www.indiandentalacademy.com
  66. 66. 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
  67. 67.    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
  68. 68. INSTRUMENT PROCESSING www.indiandentalacademy.com
  69. 69. The overall process consists of        Holding ( presoaking ) Precleaning Corrosion control, drying, lubrication Packaging Sterilization Sterilization monitoring Handling processed instruments www.indiandentalacademy.com
  70. 70. HOLDING (PRESOAKING )  Holding solution– detergent/water/enzyme solution  To prevent drying  Perforated basket  Extended soaking www.indiandentalacademy.com
  71. 71. PRECLEANING  Ultrasonic cleaning - reduces direct handling - time saving  Manual scrubbing - dangerous - long handled brush  Instrument washers www.indiandentalacademy.com
  72. 72. Ultrasonic cleaning of instruments www.indiandentalacademy.com
  73. 73. Corrosion control, drying, lubrication  Steam sterilization causes corrosion  Rust inhibitors – silver nitrite  Drying remove excess water  Hinged instruments – lubrication www.indiandentalacademy.com
  74. 74. Packaging  Prevents contamination after sterilization, during storage or when being distributed to chair side  Pouches, bags, cassettes ( stainless steel, aluminum, and plastic/resin )  Closed containers www.indiandentalacademy.com
  75. 75. Resin cassettes www.indiandentalacademy.com
  76. 76. SRERILIZATION Universal sterilization “if it can be sterilized, sterilize it” Sterility assurance - the correct performance of the proper instrument processing steps and monitoring the sterilization with biologic & chemical indicators www.indiandentalacademy.com
  77. 77. Types of sterilization 1. Heat sterilization – moist heat - dry heat - unsaturated chemical vapor 2. Liquid chemical sterilization 3. Gas sterilization www.indiandentalacademy.com
  78. 78. 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 Flash sterilization cycle www.indiandentalacademy.com
  79. 79. Small office sterilizer www.indiandentalacademy.com
  80. 80. 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
  81. 81. CHEMICLAVE www.indiandentalacademy.com
  82. 82. 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
  83. 83. 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
  84. 84. 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 cold start www.indiandentalacademy.com
  85. 85. 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
  86. 86. 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
  87. 87. 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  Hot oil sterilization - mineral oil www.indiandentalacademy.com
  88. 88. Sterilization monitoring Sterilization failures – improper cleaning, packaging, use of sterilizer Helps to achieve high level of sterility  Biologic  Chemical  Physical www.indiandentalacademy.com
  89. 89.  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
  90. 90. Handling processed instruments  Drying  Cooling  Storage Shelf life – the period of time during which sterility is assumed to be maintained www.indiandentalacademy.com
  91. 91. 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 www.indiandentalacademy.com
  92. 92. References  Robert.G.cash.- Trends in sterilization procedures and disinfection procedures in orthodontic offices – AJODO ;1990.Vol.98  Gerald.E.Smith -Glass bead sterilization of orthodontic bands –AJODO; Sept 1986  W.F.Hohlt, C.H. Miller- Sterilization of orthodontic instruments in cassettes - AJODO; Nov 1990  G.M.Mccarthy A.H.Mamandras - Infection control in the orthodontic office in Canada - AJODO Sept.1997 www.indiandentalacademy.com
  93. 93. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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