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1. INDIAN DENTAL ACADEMY
Leader in continuing dental education
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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.
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3. 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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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
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5. 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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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
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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
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8. 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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9. No
increase in blood level of Ni – 5
months of Ortho t/t - Bishara
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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
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11. Symptoms
Contact dermatitis,
Contact stomatitis,
Loss of taste,
Numbness, burning sensn,
Angular chelitis
Severe gingivitis,
Mild erythema with or without edema
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12. 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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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
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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
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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.
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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.
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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
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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
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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
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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
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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
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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
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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
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29. Moist heat
Temperatures below 1000C/ pasteurization
Temperatures at 1000C/ boiling
Steam at atmospheric pressure
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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
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31. BOILING WATER (1000C)
Denaturation of proteins
Minimum exposure time – 30 minutes
Less reliable
Washing soda ( 2% conc.) may be added
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32. Fractional sterilization ( steam at atmospheric
pressure )
Tyndallization
( John Tyndall )
Intermittent
sterilization
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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
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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
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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
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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
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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.
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42. 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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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
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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
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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
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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
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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
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49. Factors
Concentration of the substance
Time
pH of the medium
Temperature
Nature of microorganism
Presence of extraneous material
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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
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53. 1.
Agents that interfere with membrane
function
Structural derangement or disorganisation of
cell wall proteins and lipids
Surface active agents
Phenols
Alcohols
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54. Surface active agents
“Substances which alter
energy relationship at interfaces producing a
reduction of surface or interfacial tension”
Anionic
Cationic
Nonionic
Amphoteric
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61. Agents that denatures proteins
Denaturation of polypeptide chain
Unfolding of polypeptide chain
Ex;
Acids
Alkalies
Alcohols
Acetone
Organic solvents
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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
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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
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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
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66. Iodine
More reactive than chlorine
Tincture of iodine –2% iodine solution in
ethyl alcohol
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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
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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
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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
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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
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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 )
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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
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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
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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
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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
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cold start
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
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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
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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
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94. Sterilization monitoring
Sterilization failures – improper cleaning,
packaging, use of sterilizer
Helps to achieve high level of sterility
Biologic
Chemical
Physical
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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
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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
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99. 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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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
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Less than HBV
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
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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
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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.
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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.
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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.
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114. Conclusion
Clinical& metallurgical modifications of
orthodontic pliers after 500 cycles of
sterlization are negligible
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115. Comparison of 3 dry heat convection
sterilizers
Cox sterilizer Dentronix Farber ware –
Results – all 3 units 100% successful
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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.
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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
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122. Gypsum casts –
iodophor
sprayed or soaked
Resin dentures sodium hypochlorite
immersed
Wax records
iodophor
sodium hypochlorite
immersed
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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
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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
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125. After t/t
- clean instruments thoroughly
- sterilize instruments
- biological monitoring – once
weekly
- dispose contaminated waste –
that cannot be sterilized or disinfected
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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.
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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
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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
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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
.
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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.
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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 -
-
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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
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133. Thank you
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