Dental Hypersensitivity Causes and Prevention

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

1

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.

2

 Ni – moderately cytotoxic
 Cr

– little

Grimsdotir & Hansten – saliva -connecting medium – discharge of ions &
metal compounds – combine with
chemically corroded metal – attach to
mucosa.


3

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


4

 Factors affecting development of

sensitization

 Raitt and Brostoff –
 Mechanical irritation
 Skin laceration
 Increased environmental temperature
 Increased intensity and duration of

exposure
 Genetic factors


5

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

6

 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

7

Lack of intra oral response due to
Salivary glycoproteins -- barrier
difference of permeability
Cellular hypersensitivity btn skin & mucosa
difference in Langerhans distribution


8

 No

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


9

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

10

Symptoms
 Contact dermatitis,
 Contact stomatitis,
 Loss of taste,
 Numbness, burning sensn,
 Angular chelitis
 Severe gingivitis,
 Mild erythema with or without edema

11

Immunologic mechanism
Ni – common cause – contact dermatitis
Delayed hypersensitivity reaction
Induction phase
Elucidation phase
Diagnosis –
ptn history
clinical findings
patch testing


12

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

13

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

14

 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.

15

 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.


16

DISINFECTION
PROCEDURES


17

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

18

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

19

Definitions
 Antisepsis

– used to indicate the
prevention of infection, usually by
inhibiting the growth of bacteria in wounds
or tissues

 Bactericidal agents
 Bacteriostatic agents

20

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

21

Heat
 Fast
 Reliable
 Inexpensive ( relatively )


22

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

23

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


24

Dry heat
DIRECT FLAME
Bunsen burner


25

Incineration- soiled dressings,beddings


26

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

27

Hot air oven


28

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


29

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

30

BOILING WATER (1000C)
Denaturation of proteins
Minimum exposure time – 30 minutes
Less reliable
Washing soda ( 2% conc.) may be added


31

Fractional sterilization ( steam at atmospheric
pressure )


Tyndallization
( John Tyndall )



Intermittent
sterilization

32

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


33

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

34

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

35

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

36

Physical control by other
methods


37

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.

38

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

39

Membrane filter technique


40

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


41

Demerits;


It is not effective against bacterial spores



Does not penetrate liquids or solids



It may cause damage to human cells


42

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

43



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


44

ULTRASONIC VIBRATIONS
High frequency sound waves beyond the range of the
human ear
MICROSCOPIC BUBBLES
‘-COLD BOILING
Demerits
 Not very effective
 Liquid is required


45

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


46

Chemical control of
microorganisms


47

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

48

Factors
 Concentration of the substance
 Time
 pH of the medium
 Temperature
 Nature of microorganism


Presence of extraneous material

49

Bacterial species

Resistance

Bacterial endospores
Mycobacterium tuberculosis
Small nonlipid viruses
Fungi
Medium sized lipid viruses
Vegetative bacteria

50

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

51

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

52

1.

Agents that interfere with membrane
function
Structural derangement or disorganisation of
cell wall proteins and lipids





Surface active agents
Phenols
Alcohols

53

Surface active agents
“Substances which alter
energy relationship at interfaces producing a
reduction of surface or interfacial tension”





Anionic
Cationic
Nonionic
Amphoteric

54

 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

55

 Anionic detergents

– Soaps &fatty

 Nonionic detergents

– Tween 80

acids
Gross disruption of lipoprotein framework

relatively non toxic
 Amphoteric compounds

– gram+‘


56

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

57

PHENOL ( Carbolic acid )
LISTER-1865
 Active against gram-positive bacteria
 Coagulating proteins esp. cell membrane
Disadv;
 Expensive
 Pungent odour
 Caustic to the skin

58

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


59

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

60

Agents that denatures proteins
Denaturation of polypeptide chain
Unfolding of polypeptide chain
Ex;

Acids
Alkalies
Alcohols
Acetone
Organic solvents

61

Agents that destroy or modify the
functional groups of proteins



Mercuric compounds – sulphydryl groups
Anionic detergents - amino & imidazole groups

Ex;

heavy metalshalogens
hydrogen peroxide


62

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


63

OXIDISING AGENTS
Halogens –
’
 Chlorine – gasseous form, organic & inorganic
compounds
chlorine is available in 3 other forms
1. Hypochlorites
2. Organic chloramines
3. Inoganic chloramines

64

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

65

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


66



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

67

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





68

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


69

ALKYLATING AGENTS
 Formaldehyde
 Ethylene oxide
 Gluteraldehyde


70

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

71

Ethylene oxide
 Toxic & Highly explosive
 Paper, leather, wood, metal, rubber &
plastics
 Gas autoclaves & chemiclave
 Catheters,artificial heart vaves


72

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

73






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 )

74

INSTRUMENT
DISINFECTION


75

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

Holding ( presoaking )
Precleaning
Corrosion control, drying, lubrication
Packaging
Sterilization
Sterilization monitoring
Handling processed instruments

76

HOLDING (PRESOAKING )
 Holding solution–
detergent/water/enzyme
solution
 To prevent drying
 Perforated basket
 Extended soaking

77

PRECLEANING






Ultrasonic cleaning - reduces direct handling
- time saving
Manual scrubbing - dangerous
- long handled brush
Instrument washers


78

Ultrasonic cleaning of instruments


79



Corrosion control, drying, lubrication
Steam sterilization causes corrosion



Rust inhibitors – silver nitrite



Drying remove excess water



Hinged instruments – lubrication

80



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

81

Resin cassettes


82

Types of sterilization
1. Heat sterilization – moist heat
- dry heat
- unsaturated chemical vapor
2. Liquid chemical sterilization
3. Gas sterilization


83

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


84

Small office sterilizer


85

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

86

CHEMICLAVE


87

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

88

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

89

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

90

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

91

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

92

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

93

Sterilization monitoring
Sterilization failures – improper cleaning,
packaging, use of sterilizer
Helps to achieve high level of sterility
 Biologic
 Chemical
 Physical

94



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

95

Handling processed instruments




Drying
Cooling
Storage

Shelf life – the period of time during which sterility
is assumed to be maintained

96

Sterilization in Orthodontics


97

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

98

 3.

Immersion sterilization:
Agent has the capability of killing all
micro organisms and infective agents.

Time:- 6 to 10hrs.
 4. Hand antimicrobial treatment:-


99

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

Less than HBV

100



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


101



Tuberculosis

Days to

Days

Trends in sterilization and disinfections
procedures in orthodontic clinics
(Robert G.Cash:Am.J.Orthod.1990)
 Greater use of ;-

Gloves
Masks and gowns
Protective eye wear.
 Increased use of diff. Types of heat

sterilization.
 Increase in disinfections of alginate
impression

102

 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


103

Corrosion of instruments:(Masunaga JCO ’87)
 Solution corrosion
 Debris (interface corrosion)
 Heat
 Stress corrosion
 Conc. Cell corrosion


104

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.

105

 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.


106

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.


107


108

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


109

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

110


111

 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


112


113

Conclusion
 Clinical& metallurgical modifications of

orthodontic pliers after 500 cycles of
sterlization are negligible


114

Comparison of 3 dry heat convection
sterilizers
 Cox sterilizer  Dentronix  Farber ware –


Results – all 3 units 100% successful


115

Results


116

Sterlization of heat sensitive
instruments


117

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.

118

•





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


119

•

Welder points:-Vapoclave

•

Welder to be scrubbed with pure spirit.


120

DISINFECTANTS IN THE DENTAL LAB:IMPRESSIONS:-

Alginate:Sodium hypo chlorite
Chlorine dioxide
Phenols
Iodophors
Polysulphide:Sodium hypochlorite
Chlorine dioxide
Phenols

Sprays

Immersed
121

Gypsum casts –
iodophor

sprayed or soaked

Resin dentures sodium hypochlorite

immersed

Wax records
iodophor
sodium hypochlorite

immersed


122

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


123

 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

124

 After t/t

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

weekly
- dispose contaminated waste –
that cannot be sterilized or disinfected

125

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.


126

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

127

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

128










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
.

129






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.

130

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 -

-


131

References
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
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

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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Dental Hypersensitivity Causes and Prevention

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