Elastomeric and newer materials
Recycling of materials
Biodegradation of materials
Hypersensitivity reactions
Disinfection...
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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DISINFECTION PROCEDURES
Objective of sterilization
–Removal of microorganisms or
destroy them from materials or from areas...
 Sterilization

– The process by which an

article, surface, or medium is freed of all
living microorganisms either in th...
 Antisepsis

– used to indicate the
prevention of infection, usually by
inhibiting the growth of bacteria in wounds
or ti...
Elastomerics
 Elastomer

is a material that after
substantial deformation rapidly
returns to its original dimensions.
 N...
Elastomerics
 Natural rubber latex elastics- Baker, Case,

Angle- early advocates
 Polymer rubbers – developed from
petr...
Structure
 Primary + secondary bonds- weak

molecular attraction
 At rest – folded linear molecule
 On extension – unfo...
Elastomerics
 If primary bonds are broken- permanent

deformation
 Synthetic polymers – sensitive to free
radical genera...
Elastomerics


Introduced to dental profession – 1960’s



Generate light continuous forces
Uses – canine retraction
dia...
Elastomerics
 Disadv –

absorb water & saliva
stain permanently
permanent deformation
rapid loss of force
temperature sen...
Elastomerics

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Elastomerics

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Elastomerics

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Elastomerics
Force degradation and force delivery of
elastomeric chains
 Inability to deliver a continuous force level
 ...
Force Decay

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Elastomerics
 After 1st

day- force decay relatively stable
 Hershey & Reynolds- 1975 – compared
chains – framework- sim...
Elastomerics
 Wong1976 – compared two commercial
chains
 Chains distracted & maintained at 17 mm in
water at 37 C
 Resu...
 Conclusion –

rapidly extended chains – greater initial
force levels
At 1 wk the chain stretched at slow rateexhibited l...
 Ash & Nikolai-1978 – compared force

decay of chains – stored in air , water and
vivo
 In vivo environment – significan...


Due to effects of mastication oral hygiene ,
salivary enzymes & temp variations

 Genova et al – 1985 – investigated f...
 Rock et al – tested 13 commercially

available elastics
 Regardless of the no. of loops , the force
values at 100% exte...
 Killiany et al – 1986 – force delivery and

decay characteristics of RMO – ENERGY
chain – compared with short loop chain...
 Kuster etal 1986- compared chains of 2

companies stored in air & in vivo
 At 100% extension force levels

315gm
279gm
...
 Storie & Fraunhofer – compared gray

chain & fluoride releasing chain from
ortho arch
 conclusion
fluoride releasing ch...
 Baty & Fraunhofer- compared 3

colour of elastomeric chains with std
gray chains
 Conclusion


Colouring had little ef...
Pre- stretching effects
 Purpose – to improve the large initial force

degradation & the constancy of force
delivery
 Wo...
 Heat appln alone – increased rate of force

decay
 Storie et al – pre stretched gray and

fluoride releasing chains – 5...
Environmental effects
 Ferriter – 1990 – effect of ph extremes of

plaque (4.95) & saliva (7.26)
 Chains – basic soln – ...
 Coffelt et al – subjected chains to

31 % APF
4 % SNF
0.4 % Kcl soln
 Concluded 31% APF had some effect on
the force de...
summary







E chains lose 50- 70 % of their initial force
during the first day and at 3 wks retain only 30
-40 % of...
summary
 Environmental factors – associated with

deformation & force degradation
 The synthetic elastomeric chains –
pr...
White spot lesion
Enamel de mineralization
 Prevention
1. Effective plaque control
2. Fluoride release
a. fluoride varnis...
 Enamel sealants – minimal benefit (Banks

& Richmond)
 Fluoride releasing composites – ineffective
in preventing enamel...
 Fluoride releasing elastomeric modules –

provide such conditions
 Joseph & Gobler – 1993 – study on the

rate and amou...
Conclusion
fluoride release
initially high – very
low levels – after 1 wk
Minimum continuous
level of 0.25 mg of
fluoride ...
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 Protection

only temporary
 Max benefit – elastics to be replaced at
wkly intervals
 Regular topical appln of fluoride...
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 William wiltshire – 1996 – measured

release of fluoride from fluoride releasing
elastomeric modules ( fluor-I ties) in ...
 For optimal clinical benefit – replace

fluoride releasing ligature monthly
 Banks , Chadwik, Asher

prospective contro...
 After bonding excess composite removed
 Etching confined
 Standardized dietary & hygiene

instructions
 Ptns scored b...
EDI

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 Conclusion







The use of fluoride releasing elastomeric
modules – reduced enamel decalcification per
tooth by 49...
Fibre reinforced composite
 Poly( ethylene tere phthalate glycol) &

poly (1,4 cyclohexylene dimethylene tere
phthalate g...
pultrusion
 Fibre bundles – pulled through an extruder

simultaneously with the extrusion of the
polymer.
 Fibre bundles...
Electro micrograph

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Fibre reinforced composite




Burstone & Gunther
2001
Enhanced mech.
properties
A metal attachment
pad- FRC strip –
ex...
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



Highest failure – with
loadings parallel to
the tooth surface
Less shear strength

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Charles Burstone& Kuhlberg
 Pre impregnated material – PREG

partially polymerised fibre matrix complex

Applications
1. ...
 Matrix – light cured thermoset Bisgma
 Splint it – long fibre reinforced composite
 S glass fiber-

bar more esthetic
...
Properties
 ME – 70 % > highly filled composite
 YS – 6 times >
 Resiliency – 24 times >

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...


Clinical use
- 3 configurations
rope
wide strip
woven pattern

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 Technique









FRC rope cut to length
Transparent foil removed
Tooth prepared for bonding
FRC placed & contou...
Active application
FRC full arch

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Attachments

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Intermaxillary
elastics

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Vertical elastics- open bite

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Extrusion of maxillary incisor
segment

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Space closure

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Space closure

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Molar uprighting

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Uprighting posterior segment with
tip back spring

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Anterior lingual root torquing spring
combination with stainless steel
arch wire

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Maxillary incisor intrusion
TMA intrusion arch

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Mandibular incisor intrusion arch

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Replacement connectors

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Maxillary lingual bonded FRC
retainer

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Connecting FRC framework

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summary
 Long fibre reinforced materials have the

potential to replace metals in clinical
orthodontics
 Biocompatibilit...
 Layers can be added to change the shape

- improve rigidity
 Precise contour to the teeth
 Potential to alter some of ...
 Ptns who need only partial or

compromised treatment are good
candidates for FRC appliances
 Mixed dentition cases
 FR...
 Disadvantage

weakest in shear
Shear loads to be minimized as much as
possible
Requires good bonding conditions
eg – bri...
Biodegradation
Orthodontic materials – Universally austentic SS
- 18% chromium
- 8% nickel
NiTi – 1970s
Oral environment –...
 Human exposure to Ni

- diet
- atmosphere
- jewelry
- water
- clothing
- fasteners
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 Dietary intake

- Ni – 200 -300 microgms / day
- Cr – 280 microgms / day
- Ti – 300 – 2000 microgms/day
Water – 20 micro...
 Iatrogenic exposure

Joint prosthesis
Dental implants
Orthopedic plates
Surgical clips
Pace maker leads
Prosthetic heart...
 36micgms/day – Cr
 Full mouth ortho appliances –

40micgms/day – Ni
 Heat treated-SS arch wire-

0.26micgms/cm/day
www...
 Bishara , Barret – 1993 :
Purpose – Compare in vitro corrosion rate for std
orthodontic appliances
Appliance immersed – ...
-Type 305 – SS – bands AISI
-Type 316 – SS – brackets and tubes AISI
-Bands not covered from inner surface
-17- 25 wires
-...


Analyzed –
1,7,14,21,28 days

 Results –



Ni – peak level – day
7th
Park and Shearer
similar findings

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

Cr – peak level 14th
day

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Conclusion





Orthodontic appliances -reasonable amts of Ni &
Cr when placed in a artificial saliva medium
Ni releas...
Conclusion
 For both archwire types the release rate

for Ni averaged 37 times greater than that
for Cr.
 The release ra...
 Changes in the blood level of nickel

Bishara,Barret
Purpose: to determine whether orthodontic
patients accumulate measu...
Blood analyzed – atomic absorption spectro
photometry

Nickel and Chromium carcinogenicity
Ni – risk inversely proportiona...



Hexavalant Cr – readily absorbed
Elimination – urine.

Results –


Ni levels in blood



All blood levels below nor...
 16 patients no detectable Ni levels
 5 patients reduction in blood level

Higher values –

Contamination from venipunc...
SUMMARY
 Patients with fully banded & bonded

appliances did not show a significant
increase in the Ni blood level during...
Grimsdottir 1992
 Facebows,archwires,brackets& molar

bands analyzed
 Most appliances – variable amount –Ag
solder
 14d...
Park & Shearer
 Ni &Cr release-simulated ortho appliance
 incubated in 0.05%Nacl
 Ni-40micgms/day
 Cr-36 micgms/day
 ...
Metal release from simulated fixed
orthodontic appliances – AJO 2001
Hwang etal

Method
Simulated fixed orthodontic applia...
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Composition of artificial saliva

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320 polyethylene tubes – 50 ml artificial
saliva

Method
Metal release – plasma mass spectrometry
Analyzed on
1st, 3rd day...
Results
Cr release – no
increase after 4
weeks –
gp A
-- 2 weeks in gp B
-- 3 weeks in gp C
-- 8 weeks in gp D

www.indian...
Ni release – no increase
after 2 weeks – gp A
-- 3 days in gp B
-- 7 days in gp C
-- 3 weeks in gp D

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Iron Release – no
increase after 2
weeks – gp A
-- 3 days in gp B
-- 1 day in gp C & gp D

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10...
CONCLUSION
The daily amount of Cr & Ni released –
insignificant when compared with – daily
dietary intake of these metals
...
Leaching of Ni Cr and Be ions from
base metal alloy in an artificial oral
environment
--Yong
Tai, Ralf D Long, J PROST DEN...
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1 year simulated – period of mastication
Results
In vitro analysis in artificial environment –
release of Ni & Be from bas...
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Hypersensitivity
Refers to the injurious consequences in the
sensitized host following contact with
specific antigens.
Inc...
 Ni toxicity – moderately cytotoxic
 Cr toxicity – little

Grimsdotir & Hansten – saliva -connecting medium – discharge ...
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 )
Am...
 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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Hypersensitivity reactions










Dental Alloys
Symptoms of allergic reactions – dental alloys
Inflammed hyperp...
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 ...
Orthodontic appliances
Strong biologic sensitizers

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.

Janson & Prystousky -- age range 10-20
years

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 Raitt and Brostoff – several factors for
the development of sensitization
 Mechanical irritation
 Skin laceration
 In...
Kawahara & Yamakawa – Ni –
moderately cytotoxic & Cr – little toxicity.

Grandjsan et al – avg dietary intake
Ni – 200 -30...
Benco – Ni concs – drinking water below
20 micgm/ltr.
-- below the normal dietary intake-not
clinically significant

www.i...
Majjer & Smith – Ni released – soluble
compound
Cr – insoluble form

Greg & Temovari – reaction – use of
facebow – Ni-Ti a...
Jacobson & Hensten –

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Park & Shearer -- Ni from orthodontic
bands – sensitized ptns. – cause
hypersensitivity reactions in ptns with prior
h/o h...
Bishara, Barrete – no increase in blood
level of Ni – 5 months of orthodontic
treatment.

Magnuson & Neilson – higher leve...
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Fischer – sensitivity test – not to be used
indiscriminately

Vijayabasava, Surendra Shetty –

decrease in pH – increase i...
Recycling
“ Involves repeated exposure of the
appliance for several wks to mechanical
stresses or elements of the oral
env...
Recycling
 Niti – desirable mechanical prop








Relatively high cost
Buckthal et al – 52% orthodontists recycle ...
 Concluded – significant decrease in YS –

4 month period

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Effects of clinical recycling on
mechanical properties of Niti alloy wires
-sunil kapila-1991
 Materials and methods

60 ...
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 Wires

To – as received condition
T1 – 8 wks of clinical exposure ( 1
cycle)
T2 – 2 cycles
Cold recycled after one clini...
 SEM of both Nitinol and Niti wires

demonstrated increased pitting of wires
after clinical exposure

 Some smoothening ...
Surface characteristics

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Recycling of orthodontic brackets

British survey – 47.5 % of clinicians
recycle metal brackets




recycled brackets –...
 Mascia and chen – decrease in shear

bond strength
 Hixon et al – studied change in bracket

slot tolerance after recyc...
comparison of iron release from
new and recycled orthodontic
brackets-Huang & Yen- AJO2001


purpose – compare release of...
 surface characteristics – energy dispersive

radiographic analysis
 Results – recycled brackets released

more ions tha...
 The brackets release greater amounts of

ions in a ph 4 buffer than in ph 7 or 10
buffer
 As the immersion time increas...
Effect of recycling on the
mechanical properties and surface
topography of Niti alloy wires
Sung ho lee & Chang – AJO 2001...
Materials
3 types of Niti wires – 60 wires
16. 22 rectangular wires
1. As received condition – To - control
group
2. Treat...
 Results – Niti wires demonstrated no

statistically significant differences in max
tensile strength , ME and bending fat...
 Recycled Niti and Optimalloy

demonstrated significantly greater max
frictional co.eff s than did the control
group.

 ...
changes in bracket slot tolerence
following recycling of direct bond
metallic orthodontic appliances
-Mark Hixson
Material...
 Torque meter assembly

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 conclusion – recycling of brackets
results in no significant change in the
tolerance through two successive recycles
 T...
Effect of recycling on shear bond
strength – D N Kapoor, Pradeep
Tandon – JIOS sep 03
 Purpose – compare the reconditioni...
Results
 New brackets bonded to freshly extracted

teeth produce higher shear bond strength
when compared to re-bonded br...
Results
 Rebonded brackets after re conditioning

by solvent disolution method exhibit more
than optimum shear bond stren...
results
 Significant alteration In the enamel surface

was not observed due to repeated
bonding - SEM

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Thank you
www.indiandentalacademy.com
Leader in continuing dental education

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Elastomeric & new materials, recycling and biodegradation of materials /certified fixed orthodontic courses by Indian dental academy

  1. 1. Elastomeric and newer materials Recycling of materials Biodegradation of materials Hypersensitivity reactions Disinfection procedures www.indiandentalacademy.com 1
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 2
  3. 3. DISINFECTION PROCEDURES 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 3
  4. 4.  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 4
  5. 5.  Antisepsis – used to indicate the prevention of infection, usually by inhibiting the growth of bacteria in wounds or tissues SEPS ( A Greek word ) – PUTRID  Bactericidal agents  Bacteriostatic agents www.indiandentalacademy.com 5
  6. 6. Elastomerics  Elastomer is a material that after substantial deformation rapidly returns to its original dimensions.  Natural rubber- ancient Incan & Mayan civilization- 1st known elastomer  Charles goodyear- 1839vulcanization www.indiandentalacademy.com 6
  7. 7. Elastomerics  Natural rubber latex elastics- Baker, Case, Angle- early advocates  Polymer rubbers – developed from petrochemicals – 1920 www.indiandentalacademy.com 7
  8. 8. Structure  Primary + secondary bonds- weak molecular attraction  At rest – folded linear molecule  On extension – unfold- expense of secondary bonds www.indiandentalacademy.com 8
  9. 9. Elastomerics  If primary bonds are broken- permanent deformation  Synthetic polymers – sensitive to free radical generating systems ozone uv light  Decrease in flexibility & tensile strength  Addition of antioxidants & anti ozonates www.indiandentalacademy.com 9
  10. 10. Elastomerics  Introduced to dental profession – 1960’s  Generate light continuous forces Uses – canine retraction diastema closure rotational correction space closure Advinexpensive relatively hygienic easily applied ptn co operation   www.indiandentalacademy.com 10
  11. 11. Elastomerics  Disadv – absorb water & saliva stain permanently permanent deformation rapid loss of force temperature sensitive www.indiandentalacademy.com 11
  12. 12. Elastomerics www.indiandentalacademy.com 12
  13. 13. Elastomerics www.indiandentalacademy.com 13
  14. 14. www.indiandentalacademy.com 14
  15. 15. Elastomerics www.indiandentalacademy.com 15
  16. 16. Elastomerics Force degradation and force delivery of elastomeric chains  Inability to deliver a continuous force level  Bishara & Anderson-1970- compared latex & unitek alastik modules  After 24 hrs alastiks 74 % force decay latex elastics 42 % loss www.indiandentalacademy.com 16
  17. 17. Force Decay www.indiandentalacademy.com 17
  18. 18. Elastomerics  After 1st day- force decay relatively stable  Hershey & Reynolds- 1975 – compared chains – framework- simulating tooth movement  Conclusion 1st day- 50% force loss 4 wks – 40% original force remains more consistent force- by stamping manufacture – than injection molded www.indiandentalacademy.com 18
  19. 19. Elastomerics  Wong1976 – compared two commercial chains  Chains distracted & maintained at 17 mm in water at 37 C  Result – 1st 3 hrs – greatest amount of force lost  Kovach et al – evaluated initial force values of unitek alastiks stretched to 30 % of their original length at rates of .2 , 2 & 20” / min www.indiandentalacademy.com 19
  20. 20.  Conclusion – rapidly extended chains – greater initial force levels At 1 wk the chain stretched at slow rateexhibited less force decay Recommended slow stretching www.indiandentalacademy.com 20
  21. 21.  Ash & Nikolai-1978 – compared force decay of chains – stored in air , water and vivo  In vivo environment – significantly more force decay after 30 mins than those kept in air  After 3 wks – chains in vivo – greater force loss than those stored in water  Both maintained force levels of more than 160 gms www.indiandentalacademy.com 21
  22. 22.  Due to effects of mastication oral hygiene , salivary enzymes & temp variations  Genova et al – 1985 – investigated force degradation of chains - artificial saliva  Conclusion chains subjected to tooth movement retained 913 % less force than held at constant length short filament chains – higher initial force levels & retain higher % of remaining force www.indiandentalacademy.com 22
  23. 23.  Rock et al – tested 13 commercially available elastics  Regardless of the no. of loops , the force values at 100% extension were constant  Short filament chains – higher initial force level at 100 % extension-403 to 625gms  Recommended 50 – 75 % extensiondesired force of 300 gms www.indiandentalacademy.com 23
  24. 24.  Killiany et al – 1986 – force delivery and decay characteristics of RMO – ENERGY chain – compared with short loop chain from American orthodontics  After 4 wks – simulated oral environment – ENERGY chain – retained 66 % of initial force short loop chain retained 33 % of original force www.indiandentalacademy.com 24
  25. 25.  Kuster etal 1986- compared chains of 2 companies stored in air & in vivo  At 100% extension force levels 315gm 279gm  Initial extension of 50 -75% not supported www.indiandentalacademy.com 25
  26. 26.  Storie & Fraunhofer – compared gray chain & fluoride releasing chain from ortho arch  conclusion fluoride releasing chain – higher initial force level at 100 % extension gray chain – retain 38 % of its initial force fluoride releasing chain – 14 % of initial force after 1 wk in 37 C distilled water www.indiandentalacademy.com 26
  27. 27.  Baty & Fraunhofer- compared 3 colour of elastomeric chains with std gray chains  Conclusion  Colouring had little effect on initial force delivery of chains www.indiandentalacademy.com 27
  28. 28. Pre- stretching effects  Purpose – to improve the large initial force degradation & the constancy of force delivery  Wong – 1976 – pre stretching the elastic chains 1/3 of their original length – improve the strength  Brooks & Hershey – combination of pre - stretching and heat app n – reduced the amount of force degradation by 50 % at 1 hr and 31 % at 4 wks www.indiandentalacademy.com 28
  29. 29.  Heat appln alone – increased rate of force decay  Storie et al – pre stretched gray and fluoride releasing chains – 50 % for 5 secs Immersed in 3 fluid environments  Reported no clinical benefit www.indiandentalacademy.com 29
  30. 30. Environmental effects  Ferriter – 1990 – effect of ph extremes of plaque (4.95) & saliva (7.26)  Chains – basic soln – exhibited more force decay  Jefferies et al – simulated disinfection 30 mins & sterilization (10 hrs & 1 wk ) using gluteraldehyde soln  Use of gluteraldehyde – no deleterious effect on properties www.indiandentalacademy.com 30
  31. 31.  Coffelt et al – subjected chains to 31 % APF 4 % SNF 0.4 % Kcl soln  Concluded 31% APF had some effect on the force delivery & decay rate www.indiandentalacademy.com 31
  32. 32. summary     E chains lose 50- 70 % of their initial force during the first day and at 3 wks retain only 30 -40 % of the original force Force guage should be used to determine the desired initial force Longer filament chains deliver a lower initial force at the same extension than the closed loop chain Pre stretching of these chains – means of reducing the rapid force decay rate & a constant force www.indiandentalacademy.com 32
  33. 33. summary  Environmental factors – associated with deformation & force degradation  The synthetic elastomeric chains – protected from direct light  E chains – convenient , inexpensive method – continuous force system over a 3-4 wk period www.indiandentalacademy.com 33
  34. 34. White spot lesion Enamel de mineralization  Prevention 1. Effective plaque control 2. Fluoride release a. fluoride varnishes b. fluoride containing composites c. fluoride releasing GIC d. fluoride relesing elastomers  www.indiandentalacademy.com 34
  35. 35.  Enamel sealants – minimal benefit (Banks & Richmond)  Fluoride releasing composites – ineffective in preventing enamel damage ( Mitchel , Turner – 1993 )  GIC – provides greater fluoride release  Inadequate bond strength  Featherstone – 1985 – long duration low dose fluoride release – reduces demineralization www.indiandentalacademy.com 35
  36. 36.  Fluoride releasing elastomeric modules – provide such conditions  Joseph & Gobler – 1993 – study on the rate and amount of SNF release from a fluoride impregnated elastic power chain  Material 5 experimental groups & 1 control group 12 unit length of F power chain (CFRD) studied 37 C in a incubator & 100 rpm agitation www.indiandentalacademy.com 36
  37. 37. Conclusion fluoride release initially high – very low levels – after 1 wk Minimum continuous level of 0.25 mg of fluoride – necessary for remineralization Bactericidal effect at low levels of fluoride  www.indiandentalacademy.com 37
  38. 38. www.indiandentalacademy.com 38
  39. 39.  Protection only temporary  Max benefit – elastics to be replaced at wkly intervals  Regular topical appln of fluoride still necessary www.indiandentalacademy.com 39
  40. 40. www.indiandentalacademy.com 40
  41. 41.  William wiltshire – 1996 – measured release of fluoride from fluoride releasing elastomeric modules ( fluor-I ties) in vitro  Results initial burst of fluoride during the 1 st and 2nd day foll by a logarithmic decrease  35 % - total fluoride at day 1  63 % - 1st wk  83 % - 1st month  88 % - 2nd month  At 6 months – 0.19 +/- 0.03 micro gms www.indiandentalacademy.com 41
  42. 42.  For optimal clinical benefit – replace fluoride releasing ligature monthly  Banks , Chadwik, Asher prospective controlled clinical trial To evaluate the effectiveness of SNF releasing modules & chain Materials 49 ptns, 782 teeth- exptl group 45 ptns, 740 teeth – control group, non fluoride releasing elastomerics www.indiandentalacademy.com 42
  43. 43.  After bonding excess composite removed  Etching confined  Standardized dietary & hygiene instructions  Ptns scored by EDI ( Enamel Decalcification Index) – Banks & Richmond – 1994 www.indiandentalacademy.com 43
  44. 44. EDI www.indiandentalacademy.com 44
  45. 45.  Conclusion     The use of fluoride releasing elastomeric modules – reduced enamel decalcification per tooth by 49 % Enamel decalcification control group – 26 % of teeth & 73 % ptns exptl group – 16 % of teeth & 63 % ptns Occlusal zones showed no difference Fluoride releasing elastomerics – effective in reducing enamel decalcification www.indiandentalacademy.com 45
  46. 46. Fibre reinforced composite  Poly( ethylene tere phthalate glycol) & poly (1,4 cyclohexylene dimethylene tere phthalate glycol) reinforced with continuous glass fibres  FRC contained -43-45 vol% fiber  Flexural strength -565 MPa  Requisites proper wetting of glass fibres proper orientation of glass fibres www.indiandentalacademy.com 46
  47. 47. pultrusion  Fibre bundles – pulled through an extruder simultaneously with the extrusion of the polymer.  Fibre bundles impregnated by the polymer  Exiting dies determine cross section shape and size www.indiandentalacademy.com 47
  48. 48. Electro micrograph www.indiandentalacademy.com 48
  49. 49. Fibre reinforced composite    Burstone & Gunther 2001 Enhanced mech. properties A metal attachment pad- FRC strip – exhibited superior bonding strength www.indiandentalacademy.com 49
  50. 50. www.indiandentalacademy.com 50
  51. 51.   Highest failure – with loadings parallel to the tooth surface Less shear strength www.indiandentalacademy.com 51
  52. 52. Charles Burstone& Kuhlberg  Pre impregnated material – PREG partially polymerised fibre matrix complex Applications 1. Bonded cuspid to cuspid retainers 2. Bridges active applications - adjuncts for active tooth movements www.indiandentalacademy.com 52
  53. 53.  Matrix – light cured thermoset Bisgma  Splint it – long fibre reinforced composite  S glass fiber- bar more esthetic  Two stages of polymerization  Initial polymerization- matrix flexible www.indiandentalacademy.com 53
  54. 54. Properties  ME – 70 % > highly filled composite  YS – 6 times >  Resiliency – 24 times > www.indiandentalacademy.com 54
  55. 55.  Clinical use - 3 configurations rope wide strip woven pattern www.indiandentalacademy.com 55
  56. 56.  Technique        FRC rope cut to length Transparent foil removed Tooth prepared for bonding FRC placed & contoured to tooth Attachments are directly bonded to FRC Low viscosity adhesive – protective layer Indirect or direct bonding www.indiandentalacademy.com 56
  57. 57. Active application FRC full arch www.indiandentalacademy.com 57
  58. 58. www.indiandentalacademy.com 58
  59. 59. Attachments www.indiandentalacademy.com 59
  60. 60. Intermaxillary elastics www.indiandentalacademy.com 60
  61. 61. Vertical elastics- open bite www.indiandentalacademy.com 61
  62. 62. Extrusion of maxillary incisor segment www.indiandentalacademy.com 62
  63. 63. Space closure www.indiandentalacademy.com 63
  64. 64. Space closure www.indiandentalacademy.com 64
  65. 65. Molar uprighting www.indiandentalacademy.com 65
  66. 66. Uprighting posterior segment with tip back spring www.indiandentalacademy.com 66
  67. 67. Anterior lingual root torquing spring combination with stainless steel arch wire www.indiandentalacademy.com 67
  68. 68. Maxillary incisor intrusion TMA intrusion arch www.indiandentalacademy.com 68
  69. 69. Mandibular incisor intrusion arch www.indiandentalacademy.com 69
  70. 70. www.indiandentalacademy.com 70
  71. 71. Replacement connectors www.indiandentalacademy.com 71
  72. 72. Maxillary lingual bonded FRC retainer www.indiandentalacademy.com 72
  73. 73. Connecting FRC framework www.indiandentalacademy.com 73
  74. 74. summary  Long fibre reinforced materials have the potential to replace metals in clinical orthodontics  Biocompatibility not a concern  FRC materials are superior to polymers  Increased rigidity and strength  Highly formable – fabricated in complex shapes www.indiandentalacademy.com 74
  75. 75.  Layers can be added to change the shape - improve rigidity  Precise contour to the teeth  Potential to alter some of the current methods of active treatment  Esthetic alternative to lingual orthodontics www.indiandentalacademy.com 75
  76. 76.  Ptns who need only partial or compromised treatment are good candidates for FRC appliances  Mixed dentition cases  FRC bars- alternative to bands www.indiandentalacademy.com 76
  77. 77.  Disadvantage weakest in shear Shear loads to be minimized as much as possible Requires good bonding conditions eg – bridges and retainers www.indiandentalacademy.com 77
  78. 78. Biodegradation Orthodontic materials – Universally austentic SS - 18% chromium - 8% nickel NiTi – 1970s Oral environment – ionic properties thermal properties microbiologic enzymatic Ideal for biodegradation  www.indiandentalacademy.com 78
  79. 79.  Human exposure to Ni - diet - atmosphere - jewelry - water - clothing - fasteners www.indiandentalacademy.com 79
  80. 80.  Dietary intake - Ni – 200 -300 microgms / day - Cr – 280 microgms / day - Ti – 300 – 2000 microgms/day Water – 20 microgms / l – Ni - 0.43 microgms/l- Cr www.indiandentalacademy.com 80
  81. 81.  Iatrogenic exposure Joint prosthesis Dental implants Orthopedic plates Surgical clips Pace maker leads Prosthetic heart valves orthodontic appliances Ni release – dental alloy – 4.2 www.indiandentalacademy.com microgms/cm/day 81
  82. 82.  36micgms/day – Cr  Full mouth ortho appliances – 40micgms/day – Ni  Heat treated-SS arch wire- 0.26micgms/cm/day www.indiandentalacademy.com 82
  83. 83.  Bishara , Barret – 1993 : Purpose – Compare in vitro corrosion rate for std orthodontic appliances Appliance immersed – prepared artificial saliva at 37c Materials 10 sets of bands and brackets Both SS & NiTi archwires www.indiandentalacademy.com 83
  84. 84. -Type 305 – SS – bands AISI -Type 316 – SS – brackets and tubes AISI -Bands not covered from inner surface -17- 25 wires -5 sets – rectangular SS wires -5 sets – Ni Ti – Unitek Polyethylene tubes – 100 ml Artificial saliva – pH – 6.75 www.indiandentalacademy.com 84
  85. 85.  Analyzed – 1,7,14,21,28 days  Results –   Ni – peak level – day 7th Park and Shearer similar findings www.indiandentalacademy.com 85
  86. 86.  Cr – peak level 14th day www.indiandentalacademy.com 86
  87. 87. Conclusion     Orthodontic appliances -reasonable amts of Ni & Cr when placed in a artificial saliva medium Ni release reaches max after 1 week then diminishes Cr release increases during the first 2 weeks and levels off during subsequent 2 weeks Release rates of Ni & Cr from SS or NiTi wire – not significantly different. www.indiandentalacademy.com 87
  88. 88. Conclusion  For both archwire types the release rate for Ni averaged 37 times greater than that for Cr.  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 88
  89. 89.  Changes in the blood level of nickel Bishara,Barret Purpose: to determine whether orthodontic patients accumulate measurable concentrations of Ni in blood. Materials: 31 subjects – 18 females & 13 males. Blood samples collected 1 – before placement of orthodontic appliance 2 – 2 months after placement 3 – 4-5 months after placement www.indiandentalacademy.com 89
  90. 90. Blood analyzed – atomic absorption spectro photometry Nickel and Chromium carcinogenicity Ni – risk inversely proportional to solubility in aqueous media Cr – hexavalent oxidation state Normal Ni & Cr conc in blood Ni – 2.4 +/- 0.5 ng/ml & 30 +/- 19 ng/ml Cr – 0.371 ng/ml www.indiandentalacademy.com 90
  91. 91.   Hexavalant Cr – readily absorbed Elimination – urine. Results –  Ni levels in blood  All blood levels below normal  17.2% of blood samples – above detection limit of .4 ppb  never exceeded 1.3ppb www.indiandentalacademy.com 91
  92. 92.  16 patients no detectable Ni levels  5 patients reduction in blood level Higher values –  Contamination from venipuncture needle  Diet www.indiandentalacademy.com 92
  93. 93. SUMMARY  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 93
  94. 94. Grimsdottir 1992  Facebows,archwires,brackets& molar bands analyzed  Most appliances – variable amount –Ag solder  14days in 0.9Nacl  Facebows – highest amount of NI &Cr  Archwires- least www.indiandentalacademy.com 94
  95. 95. Park & Shearer  Ni &Cr release-simulated ortho appliance  incubated in 0.05%Nacl  Ni-40micgms/day  Cr-36 micgms/day  below the daily dietary intake  may sensitize patients www.indiandentalacademy.com 95
  96. 96. Metal release from simulated fixed orthodontic appliances – AJO 2001 Hwang etal Method Simulated fixed orthodontic appliances ---soaked in 50 ml of artificial saliva pH – 6.75 +/- .15 at 37 C Time period – 3 months 4 groups ( 16 – 22) 2 SS wires 2 Ni-Ti arch wires www.indiandentalacademy.com 96
  97. 97. www.indiandentalacademy.com 97
  98. 98. Composition of artificial saliva www.indiandentalacademy.com 98
  99. 99. 320 polyethylene tubes – 50 ml artificial saliva Method Metal release – plasma mass spectrometry Analyzed on 1st, 3rd days, 1st 2nd 3rd 4th 8th &12th weeks www.indiandentalacademy.com 99
  100. 100. Results Cr release – no increase after 4 weeks – gp A -- 2 weeks in gp B -- 3 weeks in gp C -- 8 weeks in gp D www.indiandentalacademy.com 100
  101. 101. Ni release – no increase after 2 weeks – gp A -- 3 days in gp B -- 7 days in gp C -- 3 weeks in gp D www.indiandentalacademy.com 101
  102. 102. Iron Release – no increase after 2 weeks – gp A -- 3 days in gp B -- 1 day in gp C & gp D www.indiandentalacademy.com 102
  103. 103. CONCLUSION 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 103
  104. 104. Leaching of Ni Cr and Be ions from base metal alloy in an artificial oral environment --Yong Tai, Ralf D Long, J PROST DENT 1992 Method Artificial oral environment – 3D force movement cycles of mastication 12 pairs of crowns articulated Metal vs metal Metal vs enamel Metal vs procelain Metal vs metal without chewing as a control www.indiandentalacademy.com 104
  105. 105. www.indiandentalacademy.com 105
  106. 106. 1 year simulated – period of mastication Results In vitro analysis in artificial environment – release of Ni & Be from base metal alloy Dissolution & Occlusal wear are both factors in the release of Ni & Be metals Occlusal wear increases the concs 2-3 times more – than with dissolution alone. www.indiandentalacademy.com 106
  107. 107. www.indiandentalacademy.com 107
  108. 108. 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 108
  109. 109.  Ni toxicity – moderately cytotoxic  Cr toxicity – little Grimsdotir & Hansten – saliva -connecting medium – discharge of ions & metal compounds – combine with chemically corroded metal – attach to mucosa. www.indiandentalacademy.com 109
  110. 110. 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 110
  111. 111.  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 111
  112. 112. 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 112
  113. 113.  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 113
  114. 114. 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 114
  115. 115.  No increase in blood level of Ni – 5 months of Ortho t/t - Bishara www.indiandentalacademy.com 115
  116. 116. Hypersensitivity reactions         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 116
  117. 117. Symptoms  Contact dermatitis,  Contact stomatitis,  Loss of taste,  Numbness, burning sensn,  Angular chelitis  Severe gingivitis,  Mild erythema with or without edema www.indiandentalacademy.com 117
  118. 118. Immunologic mechanism Ni – common cause – contact dermatitis Delayed hypersensitivity reaction Induction phase Elucidation phase Diagnosis – ptn history clinical findings patch testing www.indiandentalacademy.com 118
  119. 119. 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 119
  120. 120. 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 120
  121. 121.  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 121
  122. 122.  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 122
  123. 123. Orthodontic appliances Strong biologic sensitizers www.indiandentalacademy.com 123
  124. 124. . Janson & Prystousky -- age range 10-20 years www.indiandentalacademy.com 124
  125. 125.  Raitt and Brostoff – several factors for the development of sensitization  Mechanical irritation  Skin laceration  Increased environmental temperature  Increased intensity and duration of exposure  Genetic factors www.indiandentalacademy.com 125
  126. 126. Kawahara & Yamakawa – Ni – moderately cytotoxic & Cr – little toxicity. Grandjsan et al – avg dietary intake Ni – 200 -300 micgms./day Cr – 250 micgms/day www.indiandentalacademy.com 126
  127. 127. Benco – Ni concs – drinking water below 20 micgm/ltr. -- below the normal dietary intake-not clinically significant www.indiandentalacademy.com 127
  128. 128. Majjer & Smith – Ni released – soluble compound Cr – insoluble form Greg & Temovari – reaction – use of facebow – Ni-Ti arch wires Moffa et al – allergic response to Ni containing dental alloys Dulap et al – allergic reaction – insertion of Ni-Ti wire in sensitive patient www.indiandentalacademy.com 128
  129. 129. Jacobson & Hensten – www.indiandentalacademy.com 129
  130. 130. Park & Shearer -- Ni from orthodontic bands – sensitized ptns. – cause hypersensitivity reactions in ptns with prior h/o hs. James et al – no relationship betwn a +ve recn to Ni & a clinical response to Ni containing dental alloy Stearh Jear et al – no risk involved for Ni sensitive ptns www.indiandentalacademy.com 130
  131. 131. Bishara, Barrete – no increase in blood level of Ni – 5 months of orthodontic treatment. Magnuson & Neilson – higher level of Ni conc – needed to elicit – intra oral response www.indiandentalacademy.com 131
  132. 132. www.indiandentalacademy.com 132
  133. 133. Fischer – sensitivity test – not to be used indiscriminately Vijayabasava, Surendra Shetty – decrease in pH – increase in Ni Highest – pH 5.8 Ni release – less than 5-10% daily dietary intake Ross Levy et al – orthodontic appliance – induce sensitivity – little or no effect on the gingiva of the ptn. www.indiandentalacademy.com 133
  134. 134. Recycling “ Involves repeated exposure of the appliance for several wks to mechanical stresses or elements of the oral environment as well as sterilization b/w uses. May result in corrosion and biodegradation of the wire Alteration in properties www.indiandentalacademy.com 134
  135. 135. Recycling  Niti – desirable mechanical prop      Relatively high cost Buckthal et al – 52% orthodontists recycle Ni ti wires 80% cold methods – disinfection Cold & heat sterilization – don’t affect mechanical properties Harris et al – simulated oral environment 0.016 Nitinol wires www.indiandentalacademy.com 135
  136. 136.  Concluded – significant decrease in YS – 4 month period www.indiandentalacademy.com 136
  137. 137. Effects of clinical recycling on mechanical properties of Niti alloy wires -sunil kapila-1991  Materials and methods 60 wires – Nitinol & Niti wires 3 point bending test – mechanical properties SEM – surface characteristics www.indiandentalacademy.com 137
  138. 138. www.indiandentalacademy.com 138
  139. 139.  Wires To – as received condition T1 – 8 wks of clinical exposure ( 1 cycle) T2 – 2 cycles Cold recycled after one clinical cycleisopropyl alcohol Results Nitinol wires subjected to 1 or 2 recycles demonstrated statistically significant differences during loading then control To www.indiandentalacademy.com 139
  140. 140.  SEM of both Nitinol and Niti wires demonstrated increased pitting of wires after clinical exposure  Some smoothening of Nitinol wires were also observed in localised regions of the wire www.indiandentalacademy.com 140
  141. 141. Surface characteristics www.indiandentalacademy.com 141
  142. 142. Recycling of orthodontic brackets  British survey – 47.5 % of clinicians recycle metal brackets   recycled brackets – accelerates corrosion process wheeler and Ackermann – reduction in mesh diameter – recycling – no significant change in bond strength www.indiandentalacademy.com 142
  143. 143.  Mascia and chen – decrease in shear bond strength  Hixon et al – studied change in bracket slot tolerance after recycling of brackets  concluded – no statistically significant change in the tolerance through two successive recycles  Chapman – bracket slot - increase in width – proportionate to no. of times it is recycled www.indiandentalacademy.com 143
  144. 144. comparison of iron release from new and recycled orthodontic brackets-Huang & Yen- AJO2001  purpose – compare release of ions Ni, Mn , Fe    materials and methods – 12 wk period recycle brackets – coated with adhesive and heat treated atomic absorption – detection of ions www.indiandentalacademy.com 144
  145. 145.  surface characteristics – energy dispersive radiographic analysis  Results – recycled brackets released more ions than new brackets  Both new and recycled brackets can degrade in solns  Greater amounts of Ni, Mn and Fe ions were released in the artificial saliva soln than in other buffer solns www.indiandentalacademy.com 145
  146. 146.  The brackets release greater amounts of ions in a ph 4 buffer than in ph 7 or 10 buffer  As the immersion time increased so did the ion release  After 12 wk immersion the total amount of ion release was less than the cumulative daily intake- www.indiandentalacademy.com 146
  147. 147. Effect of recycling on the mechanical properties and surface topography of Niti alloy wires Sung ho lee & Chang – AJO 2001 Parameters – mechanical properties surface topography frictional forces www.indiandentalacademy.com 147
  148. 148. Materials 3 types of Niti wires – 60 wires 16. 22 rectangular wires 1. As received condition – To - control group 2. Treated in artificial saliva for 4 wks – T1 3. Treated in artificial saliva & autoclaved – T2 Method – maintained in a incubator at 37 C  www.indiandentalacademy.com 148
  149. 149.  Results – Niti wires demonstrated no statistically significant differences in max tensile strength , ME and bending fatigue  Niti and Optimalloy demonstrated increased pitting and corrosion on recycling , Sent alloy did not  Recycled NIti and Optimalloy demonstrated greater surface roughness , Sent alloy did not . www.indiandentalacademy.com 149
  150. 150.  Recycled Niti and Optimalloy demonstrated significantly greater max frictional co.eff s than did the control group.  Sent alloy showed no difference.  Surface roughness and frictional co.eff of recycled Niti and Optimalloy were not more than those of Sent alloy control group www.indiandentalacademy.com 150
  151. 151. changes in bracket slot tolerence following recycling of direct bond metallic orthodontic appliances -Mark Hixson Materials and methods – Stainless steel – direct bond brackets – 3 different companies Evaluated for changes in ability to be torqued by rectangular arch wire after being recycled 75 0.022 * 0.028 brackets www.indiandentalacademy.com 151
  152. 152.  Torque meter assembly www.indiandentalacademy.com 152
  153. 153.  conclusion – recycling of brackets results in no significant change in the tolerance through two successive recycles  The max increase in tolerance after 2 recycles was approximately 3 degrees www.indiandentalacademy.com 153
  154. 154. Effect of recycling on shear bond strength – D N Kapoor, Pradeep Tandon – JIOS sep 03  Purpose – compare the reconditioning methods like flaming ,sand blasting and solvent disolution  Bond strength – universal instron testing machine www.indiandentalacademy.com 154
  155. 155. Results  New brackets bonded to freshly extracted teeth produce higher shear bond strength when compared to re-bonded brackets bonded to freshly extracted teeth and/or reconditioned enamel surface  Flaming and sand blasting method for re conditioning of brackets demonstrates highest shear bond strength www.indiandentalacademy.com 155
  156. 156. Results  Rebonded brackets after re conditioning by solvent disolution method exhibit more than optimum shear bond strength and can be an effective chemical method for reconditioning  Lowest value of shear bond strength was seen when the bracket - reconditioned by flaming was bonded to reconditioned enamel surface www.indiandentalacademy.com 156
  157. 157. results  Significant alteration In the enamel surface was not observed due to repeated bonding - SEM www.indiandentalacademy.com 157
  158. 158. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com 158

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