DISINFECTION
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacade...
Hypersensitivity
Refers to the injurious consequences in the
sensitized host following contact with
specific antigens.
Inc...
 Ni – moderately cytotoxic
 Cr

– little

Grimsdotir & Hansten – saliva -connecting medium – discharge of ions &
metal c...
Alan & Smith – incidence rate of
hypersensitivity – 10%

Blane & Peltonon – estimated that 4.5 –
28.5 of popln – have sens...
 Factors affecting development of

sensitization

 Raitt and Brostoff –
 Mechanical irritation
 Skin laceration
 Incr...
Dietary intake




Ni - 200 – 300 micgms / day
Cr – 250 micgms / day
Drinking water – 20 micgms / l – Ni (Bencho )

Amo...
 Form

of release - Ni – soluble
Cr – insoluble
 Allergy more common in extra oral -- intra
oral appliances – 6 times

...
Lack of intra oral response due to
Salivary glycoproteins -- barrier
difference of permeability
Cellular hypersensitivity ...
 No

increase in blood level of Ni – 5
months of Ortho t/t - Bishara

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9
Hypersensitivity reactions to Dental
Alloys

Symptoms of allergic reactions – dental alloys
 Inflammed hyperplastic gingi...
Symptoms
 Contact dermatitis,
 Contact stomatitis,
 Loss of taste,
 Numbness, burning sensn,
 Angular chelitis
 Seve...
Immunologic mechanism
Ni – common cause – contact dermatitis
Delayed hypersensitivity reaction
Induction phase
Elucidation...
Different corrosion resistant
materials – used in
Hypersensitivity ptns
AISI 316 L steel – most corrosion resistant
AISI 3...
Conclusions
The daily amount of Cr & Ni released –
insignificant when compared with – daily
dietary intake of these metals...
 Patients with fully banded & bonded

appliances did not show a significant
increase in the Ni blood level during the 1 s...
 The release rates for full mouth

orthodontic appliances are less than 10%
of the reported average daily dietary
intake ...
DISINFECTION
PROCEDURES

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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 ...
Definitions
 Antisepsis

– used to indicate the
prevention of infection, usually by
inhibiting the growth of bacteria in ...
Spaulding system ( 1972 )





Critical

- penetrate/touch broken skin or
mucous membrane
- must be sterilized
Semicrit...
Heat
 Fast
 Reliable
 Inexpensive ( relatively )

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22
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- 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,...
Hot air oven

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

ww...
Pasteurization ( below 1000C )
Purpose – To reduce the bacterial population of a
liquid such as milk
Spores are not affect...
BOILING WATER (1000C)
Denaturation of proteins
Minimum exposure time – 30 minutes
Less reliable
Washing soda ( 2% conc.) m...
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...
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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40
ULTTRAVIOLET LIGHT
Wave length
Visible light is between 400 & 800nm
Ultraviolet light is between 100 & 400 nm

www.indiand...
Demerits;


It is not effective against bacterial spores



Does not penetrate liquids or solids



It may cause damage...
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
MICROSCOPIC BUBBLES
‘-COLD BOILING
Deme...
Physical agents of infection
control
Heat

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

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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


Presence of ...
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...
 Anionic detergents

– Soaps &fatty

 Nonionic detergents

– Tween 80

acids
Gross disruption of lipoprotein framework

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

pH - 8.0
Mechanical removal...
PHENOL ( Carbolic acid )
LISTER-1865
 Active against gram-positive bacteria
 Coagulating proteins esp. cell membrane
Dis...
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...
Agents that destroy or modify the
functional groups of proteins



Mercuric compounds – sulphydryl groups
Anionic deterg...
Heavy metals
‘An electron donating element whose atoms are
large, with complex electron arrangements’
Heavy metals are ver...
OXIDISING AGENTS
Halogens –
’
 Chlorine – gasseous form, organic & inorganic
compounds
chlorine is available in 3 other f...
Chlorine compounds
1.Ca(Ocl)2 - Chlorinated lime
2. NaOCl - DAKIN’s solution used to treat
‘ATHLETE’s foot

4. Chloramines...
Iodine
More reactive than chlorine
Tincture of iodine –2% iodine solution in
ethyl alcohol

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6...


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 m...
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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70
Formaldehyde
Gas at high temperatures & a solid at room
temperatures
37% solution – Formalin
In gaseous form - Sterilize s...
Ethylene oxide
 Toxic & Highly explosive
 Paper, leather, wood, metal, rubber &
plastics
 Gas autoclaves & chemiclave
...
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
DISINFECTION

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75
The overall process consists of








Holding ( presoaking )
Precleaning
Corrosion control, drying, lubrication
P...
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 handl...
Ultrasonic cleaning of instruments

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79


Corrosion control, drying, lubrication
Steam sterilization causes corrosion



Rust inhibitors – silver nitrite



Dr...


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



Pouche...
Resin cassettes

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82
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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85
Unsaturated chemical vapor sterilization
( chemiclave )
Heating a special chemical solution
Solution – 0.23% formaldehyde ...
CHEMICLAVE

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87
Temperature - 2700 F( 1320 C )
Pressure
- 25 psi ( 172 Kpa.)
Time
- 20 min
Positive feature – corrosion is reduced or
comp...
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 as...
Sterilization in Orthodontics

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97
Types of disinfections used in
dentistry
 1.

Surface disinfections: Environmental surfaces like cabinets,
chairs, units...
 3.

Immersion sterilization:
Agent has the capability of killing all
micro organisms and infective agents.

Time:- 6 t...
BIOLOGICAL CONTAMINANTS:(JCO ’88)


AGENT.
SURVIVALTIME

DISEASE
•

ESTIMATED
AT ROOMTEMPERATURE:



VIRUSES:HAV

Hepati...


BACTERIA:-



Mycobacterium
weeks
Tuberculosis



Staphylococcus Aurous

Skin, lung infections



Streptococcus
Pyog...
Trends in sterilization and disinfections
procedures in orthodontic clinics
(Robert G.Cash:Am.J.Orthod.1990)
 Greater use...
 Comparison of infection control practices

of orthodontists and general dentists:(- Mc Carthy, et al:
Am.J.Orthod ’97)
G...
Corrosion of instruments:(Masunaga JCO ’87)
 Solution corrosion
 Debris (interface corrosion)
 Heat
 Stress corrosion
...
Corrosion of instruments
 Prevention of corrosion during auto

claving:-Clean instruments thoroughly; rinse with
distille...
 Instruments not be laid on each other
 Detergents with chloride bases should not

be used (HCI formed).
 PH > 8.5disru...
Sterilization of
orthodontics instruments
and bands in cassettes:(Holt, Miller, et al
Am.J.Orthodo ’90)
 Contaminated
ins...
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108
Glass bead sterilization of orthodontic
bands:- (smith Am J Orthod ’86)
 15 Sec – Bacteria
 45 Sec – Spores

226 C
 5 s...
Types of sterilization on orthodontic Pliers:(Mazzocchi. et al JCO ’94)
 Auto Clave - 250F, 1atm, for 30min
 Chemiclave ...
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111
 Auto clave:-

Corrosion by water.
 Chemiclave:- decreased corrosion
 Lubrication of instrument hinges:Avoid oils.
 Ha...
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113
Conclusion
 Clinical& metallurgical modifications of

orthodontic pliers after 500 cycles of
sterlization are negligible
...
Comparison of 3 dry heat convection
sterilizers
 Cox sterilizer  Dentronix  Farber ware –


Results – all 3 units 100%...
Results

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Sterlization of heat sensitive
instruments

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117
ADA RECOMMENDATIONS FOR
STERILIZATION AND DISINFECTION OF
DENTAL INSTRUMETNS, MATERIALS AND
COMMONLY USED ITEMS:

Stainle...
•





3 way syringe:- Vapoclave, glutaraldehyde
Orthodontic pliers:-Autoclave, vapoclave
Reuse of materials like prefor...
•

Welder points:-Vapoclave

•

Welder to be scrubbed with pure spirit.

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120
DISINFECTANTS IN THE DENTAL LAB:IMPRESSIONS:-

Alginate:Sodium hypo chlorite
Chlorine dioxide
Phenols
Iodophors
Polysulphi...
Gypsum casts –
iodophor

sprayed or soaked

Resin dentures sodium hypochlorite

immersed

Wax records
iodophor
sodium hypo...
INFECTION CONTROL IN THE DENTAL
OFFICE
 Patients should be treated as if they are

infected with blood borne pathogens su...
 Before t/t

– thorough medical history
- place disposable coverings

During t/t - use protective wear
- minimize formati...
 After t/t

- clean instruments thoroughly
- sterilize instruments
- biological monitoring – once

weekly
- dispose conta...
Common causes of sterilization
failure
 Cycle time too short
 Temp. too low
 Failure to preheat sterilizer
 Faulty ste...
References







Orthodontic biomaterials from past to present –
Robert P Kusy , Angle – orthod may 2000
Future of or...
References








Effects of recycling on the mechanical properties and
surface topography of nickel titanium alloy ...









Biodegradation of orthodontic appliances – Part
1 Biodegradation of Ni & Cr in vitro. Barret ,
Bishara , Am ...





Force application and decay characterstics of
untreated and treated polyurethrane elastomeric
chains, Stevenson, R...
References


Trends in sterilization procedures and disinfection
procedures in orthodontic offices- Robert.G.cash.
– AJOD...
References






Text book of microbiology
-R.Ananthnarayan & C.K.J.Paniker
Infection control & office safety
- DCNA ...
www.indiandentalacademy.com
Leader in continuing dental education

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133
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Disinfection /certified fixed orthodontic courses by Indian dental academy

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Disinfection /certified fixed orthodontic courses by Indian dental academy

  1. 1. DISINFECTION INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
  2. 2. 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 2
  3. 3.  Ni – moderately cytotoxic  Cr – little Grimsdotir & Hansten – saliva -connecting medium – discharge of ions & metal compounds – combine with chemically corroded metal – attach to mucosa. www.indiandentalacademy.com 3
  4. 4. 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 www.indiandentalacademy.com 4
  5. 5.  Factors affecting development of sensitization  Raitt and Brostoff –  Mechanical irritation  Skin laceration  Increased environmental temperature  Increased intensity and duration of exposure  Genetic factors www.indiandentalacademy.com 5
  6. 6. 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 6
  7. 7.  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 7
  8. 8. Lack of intra oral response due to Salivary glycoproteins -- barrier difference of permeability Cellular hypersensitivity btn skin & mucosa difference in Langerhans distribution www.indiandentalacademy.com 8
  9. 9.  No increase in blood level of Ni – 5 months of Ortho t/t - Bishara www.indiandentalacademy.com 9
  10. 10. 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 10
  11. 11. Symptoms  Contact dermatitis,  Contact stomatitis,  Loss of taste,  Numbness, burning sensn,  Angular chelitis  Severe gingivitis,  Mild erythema with or without edema www.indiandentalacademy.com 11
  12. 12. Immunologic mechanism Ni – common cause – contact dermatitis Delayed hypersensitivity reaction Induction phase Elucidation phase Diagnosis – ptn history clinical findings patch testing www.indiandentalacademy.com 12
  13. 13. 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 13
  14. 14. 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 14
  15. 15.  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  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 15
  16. 16.  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. www.indiandentalacademy.com 16
  17. 17. DISINFECTION PROCEDURES www.indiandentalacademy.com 17
  18. 18. 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 18
  19. 19. 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 19
  20. 20. 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 20
  21. 21. 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 21
  22. 22. Heat  Fast  Reliable  Inexpensive ( relatively ) www.indiandentalacademy.com 22
  23. 23. 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 23
  24. 24. 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 24
  25. 25. Dry heat DIRECT FLAME Bunsen burner www.indiandentalacademy.com 25
  26. 26. Incineration- soiled dressings,beddings www.indiandentalacademy.com 26
  27. 27. 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 27
  28. 28. Hot air oven www.indiandentalacademy.com 28
  29. 29. Moist heat  Temperatures below 1000C/ pasteurization  Temperatures at 1000C/ boiling  Steam at atmospheric pressure www.indiandentalacademy.com 29
  30. 30. 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 30
  31. 31. BOILING WATER (1000C) Denaturation of proteins Minimum exposure time – 30 minutes Less reliable Washing soda ( 2% conc.) may be added www.indiandentalacademy.com 31
  32. 32. Fractional sterilization ( steam at atmospheric pressure )  Tyndallization ( John Tyndall )  Intermittent sterilization www.indiandentalacademy.com 32
  33. 33. 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 33
  34. 34. 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 34
  35. 35. 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 35
  36. 36. 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 36
  37. 37. Physical control by other methods www.indiandentalacademy.com 37
  38. 38. 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 38
  39. 39. 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 39
  40. 40. Membrane filter technique www.indiandentalacademy.com 40
  41. 41. ULTTRAVIOLET LIGHT Wave length Visible light is between 400 & 800nm Ultraviolet light is between 100 & 400 nm www.indiandentalacademy.com 41
  42. 42. Demerits;  It is not effective against bacterial spores  Does not penetrate liquids or solids  It may cause damage to human cells www.indiandentalacademy.com 42
  43. 43. 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 43
  44. 44.  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 44
  45. 45. ULTRASONIC VIBRATIONS High frequency sound waves beyond the range of the human ear MICROSCOPIC BUBBLES ‘-COLD BOILING Demerits  Not very effective  Liquid is required www.indiandentalacademy.com 45
  46. 46. 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 www.indiandentalacademy.com 46
  47. 47. Chemical control of microorganisms www.indiandentalacademy.com 47
  48. 48. 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 48
  49. 49. Factors  Concentration of the substance  Time  pH of the medium  Temperature  Nature of microorganism  Presence of extraneous material www.indiandentalacademy.com 49
  50. 50. Bacterial species Resistance Bacterial endospores Mycobacterium tuberculosis Small nonlipid viruses Fungi Medium sized lipid viruses Vegetative bacteria www.indiandentalacademy.com 50
  51. 51. 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 51
  52. 52. 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 52
  53. 53. 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 53
  54. 54. 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 54
  55. 55.  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 55
  56. 56.  Anionic detergents – Soaps &fatty  Nonionic detergents – Tween 80 acids Gross disruption of lipoprotein framework relatively non toxic  Amphoteric compounds – gram+‘ www.indiandentalacademy.com 56
  57. 57. 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 57
  58. 58. 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 58
  59. 59. 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 59
  60. 60. 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 60
  61. 61. Agents that denatures proteins Denaturation of polypeptide chain Unfolding of polypeptide chain Ex; Acids Alkalies Alcohols Acetone Organic solvents www.indiandentalacademy.com 61
  62. 62. Agents that destroy or modify the functional groups of proteins   Mercuric compounds – sulphydryl groups Anionic detergents - amino & imidazole groups Ex; heavy metalshalogens hydrogen peroxide www.indiandentalacademy.com 62
  63. 63. 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 www.indiandentalacademy.com 63
  64. 64. 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 64
  65. 65. 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 65
  66. 66. Iodine More reactive than chlorine Tincture of iodine –2% iodine solution in ethyl alcohol www.indiandentalacademy.com 66
  67. 67.  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 67
  68. 68. 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 68
  69. 69. 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 69
  70. 70. ALKYLATING AGENTS  Formaldehyde  Ethylene oxide  Gluteraldehyde www.indiandentalacademy.com 70
  71. 71. 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 71
  72. 72. Ethylene oxide  Toxic & Highly explosive  Paper, leather, wood, metal, rubber & plastics  Gas autoclaves & chemiclave  Catheters,artificial heart vaves www.indiandentalacademy.com 72
  73. 73. 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 73
  74. 74.    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 74
  75. 75. INSTRUMENT DISINFECTION www.indiandentalacademy.com 75
  76. 76. The overall process consists of        Holding ( presoaking ) Precleaning Corrosion control, drying, lubrication Packaging Sterilization Sterilization monitoring Handling processed instruments www.indiandentalacademy.com 76
  77. 77. HOLDING (PRESOAKING )  Holding solution– detergent/water/enzyme solution  To prevent drying  Perforated basket  Extended soaking www.indiandentalacademy.com 77
  78. 78. PRECLEANING    Ultrasonic cleaning - reduces direct handling - time saving Manual scrubbing - dangerous - long handled brush Instrument washers www.indiandentalacademy.com 78
  79. 79. Ultrasonic cleaning of instruments www.indiandentalacademy.com 79
  80. 80.  Corrosion control, drying, lubrication Steam sterilization causes corrosion  Rust inhibitors – silver nitrite  Drying remove excess water  Hinged instruments – lubrication www.indiandentalacademy.com 80
  81. 81.  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 81
  82. 82. Resin cassettes www.indiandentalacademy.com 82
  83. 83. Types of sterilization 1. Heat sterilization – moist heat - dry heat - unsaturated chemical vapor 2. Liquid chemical sterilization 3. Gas sterilization www.indiandentalacademy.com 83
  84. 84. 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 www.indiandentalacademy.com 84
  85. 85. Small office sterilizer www.indiandentalacademy.com 85
  86. 86. 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 86
  87. 87. CHEMICLAVE www.indiandentalacademy.com 87
  88. 88. 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 88
  89. 89. 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 89
  90. 90. 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 90
  91. 91. 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 91
  92. 92. 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 92
  93. 93. 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 93
  94. 94. Sterilization monitoring Sterilization failures – improper cleaning, packaging, use of sterilizer Helps to achieve high level of sterility  Biologic  Chemical  Physical www.indiandentalacademy.com 94
  95. 95.  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 95
  96. 96. Handling processed instruments    Drying Cooling Storage Shelf life – the period of time during which sterility is assumed to be maintained www.indiandentalacademy.com 96
  97. 97. Sterilization in Orthodontics www.indiandentalacademy.com 97
  98. 98. 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 98
  99. 99.  3. Immersion sterilization: Agent has the capability of killing all micro organisms and infective agents.  Time:- 6 to 10hrs.  4. Hand antimicrobial treatment:- www.indiandentalacademy.com 99
  100. 100. 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 100
  101. 101.  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 www.indiandentalacademy.com 101  Tuberculosis Days to Days
  102. 102. 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 102
  103. 103.  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 www.indiandentalacademy.com 103
  104. 104. Corrosion of instruments:(Masunaga JCO ’87)  Solution corrosion  Debris (interface corrosion)  Heat  Stress corrosion  Conc. Cell corrosion www.indiandentalacademy.com 104
  105. 105. 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 105
  106. 106.  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. www.indiandentalacademy.com 106
  107. 107. 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. www.indiandentalacademy.com 107
  108. 108. www.indiandentalacademy.com 108
  109. 109. 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 www.indiandentalacademy.com 109
  110. 110. 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 110
  111. 111. www.indiandentalacademy.com 111
  112. 112.  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 www.indiandentalacademy.com 112
  113. 113. www.indiandentalacademy.com 113
  114. 114. Conclusion  Clinical& metallurgical modifications of orthodontic pliers after 500 cycles of sterlization are negligible www.indiandentalacademy.com 114
  115. 115. Comparison of 3 dry heat convection sterilizers  Cox sterilizer  Dentronix  Farber ware –  Results – all 3 units 100% successful www.indiandentalacademy.com 115
  116. 116. Results www.indiandentalacademy.com 116
  117. 117. Sterlization of heat sensitive instruments www.indiandentalacademy.com 117
  118. 118. 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 118
  119. 119. •   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 www.indiandentalacademy.com 119
  120. 120. • Welder points:-Vapoclave • Welder to be scrubbed with pure spirit. www.indiandentalacademy.com 120
  121. 121. DISINFECTANTS IN THE DENTAL LAB:IMPRESSIONS:- Alginate:Sodium hypo chlorite Chlorine dioxide Phenols Iodophors Polysulphide:Sodium hypochlorite Chlorine dioxide Phenols www.indiandentalacademy.com Sprays Immersed 121
  122. 122. Gypsum casts – iodophor sprayed or soaked Resin dentures sodium hypochlorite immersed Wax records iodophor sodium hypochlorite immersed www.indiandentalacademy.com 122
  123. 123. 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 www.indiandentalacademy.com 123
  124. 124.  Before t/t – 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 124
  125. 125.  After t/t - clean instruments thoroughly - sterilize instruments - biological monitoring – once weekly - dispose contaminated waste – that cannot be sterilized or disinfected www.indiandentalacademy.com 125
  126. 126. 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. www.indiandentalacademy.com 126
  127. 127. 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 127
  128. 128. 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 128
  129. 129.      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 129
  130. 130.    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 130
  131. 131. 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 - - www.indiandentalacademy.com 131
  132. 132. 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 132
  133. 133. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com 133

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