Dental Disinfection Procedures

Elastomeric and newer materialsElastomeric and newer materials
Recycling of materialsRecycling of materials
Biodegradation of materialsBiodegradation of materials
Hypersensitivity reactionsHypersensitivity reactions
Disinfection proceduresDisinfection procedures
www.indiandentalacademy.comwww.indiandentalacademy.com

DISINFECTION PROCEDURESDISINFECTION PROCEDURES
Objective of sterilizationObjective of sterilization
––Removal of microorganisms orRemoval of microorganisms or
destroy them from materials or from areasdestroy them from materials or from areas
since they cause contamination, infectionsince they cause contamination, infection
and decay.and decay.
In microbiology - to prevent contaminationIn microbiology - to prevent contamination
Surgery - to maintain asepsisSurgery - to maintain asepsis
Drug & food -for ensuring the safetyDrug & food -for ensuring the safety

 SterilizationSterilization – T– The process by which anhe process by which an
article, surface, or medium is freed of allarticle, surface, or medium is freed of all
living microorganisms either in theliving microorganisms either in the
vegetative or spore statevegetative or spore state
 DisinfectionDisinfection – The destruction or removal– The destruction or removal
of all pathogenic organisms, or organismsof all pathogenic organisms, or organisms
capable of giving rise to infectioncapable of giving rise to infection

 AntisepsisAntisepsis – used to indicate the– used to indicate the
prevention of infection, usually byprevention of infection, usually by
inhibiting the growth of bacteria in woundsinhibiting the growth of bacteria in wounds
or tissuesor tissues
SEPS ( A Greek word ) – PUTRIDSEPS ( A Greek word ) – PUTRID
 Bactericidal agentsBactericidal agents
 Bacteriostatic agentsBacteriostatic agents

ElastomericsElastomerics
 Elastomer is a material that afterElastomer is a material that after
substantial deformation rapidlysubstantial deformation rapidly
returns to its original dimensions.returns to its original dimensions.
 Natural rubber- ancient Incan &Natural rubber- ancient Incan &
Mayan civilization- 1Mayan civilization- 1stst
knownknown
elastomerelastomer
 Charles goodyear- 1839-Charles goodyear- 1839-
vulcanizationvulcanization

 Natural rubber latex elastics- Baker, Case,Natural rubber latex elastics- Baker, Case,
Angle- early advocatesAngle- early advocates
 Polymer rubbers – developed fromPolymer rubbers – developed from
petrochemicals – 1920petrochemicals – 1920

StructureStructure
 Primary + secondary bonds- weakPrimary + secondary bonds- weak
molecular attractionmolecular attraction
 At rest – folded linear moleculeAt rest – folded linear molecule
 On extension – unfold- expense ofOn extension – unfold- expense of
secondary bondssecondary bonds

 If primary bonds are broken- permanentIf primary bonds are broken- permanent
deformationdeformation
 Synthetic polymers – sensitive to freeSynthetic polymers – sensitive to free
radical generating systemsradical generating systems
ozoneozone
uv lightuv light
 Decrease in flexibility & tensile strengthDecrease in flexibility & tensile strength
 Addition of antioxidants & anti ozonatesAddition of antioxidants & anti ozonates

 Introduced to dental profession – 1960’sIntroduced to dental profession – 1960’s
 Generate light continuous forcesGenerate light continuous forces
 Uses – canine retractionUses – canine retraction
diastema closurediastema closure
rotational correctionrotational correction
space closurespace closure
 Adv-Adv- inexpensiveinexpensive
relatively hygienicrelatively hygienic
easily appliedeasily applied
ptn co operationptn co operation

Disadv –Disadv – absorb water & salivaabsorb water & saliva
stain permanentlystain permanently
permanent deformationpermanent deformation
rapid loss of forcerapid loss of force
temperature sensitivetemperature sensitive

Force degradation and force delivery ofForce degradation and force delivery of
elastomeric chainselastomeric chains
 Inability to deliver a continuous force levelInability to deliver a continuous force level
 Bishara & Anderson-1970- comparedBishara & Anderson-1970- compared
latex & unitek alastik moduleslatex & unitek alastik modules
 After 24 hrsAfter 24 hrs
alastiks 74 % force decayalastiks 74 % force decay
latex elastics 42 % losslatex elastics 42 % loss

Force DecayForce Decay

 After 1After 1stst
day- force decay relatively stableday- force decay relatively stable
 Hershey & Reynolds- 1975 – comparedHershey & Reynolds- 1975 – compared
chains – framework- simulating toothchains – framework- simulating tooth
movementmovement
 ConclusionConclusion
11stst
day- 50% force lossday- 50% force loss
4 wks – 40% original force remains4 wks – 40% original force remains
more consistent force- by stampingmore consistent force- by stamping
manufacture – than injection moldedmanufacture – than injection molded

 Wong1976Wong1976 – compared two commercial– compared two commercial
chainschains
 Chains distracted & maintained at 17 mm inChains distracted & maintained at 17 mm in
water at 37 Cwater at 37 C
 Result – 1Result – 1stst
3 hrs – greatest amount of force lost3 hrs – greatest amount of force lost
 Kovach et alKovach et al – evaluated initial force values– evaluated initial force values
of unitek alastiksof unitek alastiks
stretched to 30 % of their original length atstretched to 30 % of their original length at
rates of .2 , 2 & 20” / minrates of .2 , 2 & 20” / min

 Conclusion –Conclusion –
rapidly extended chains – greater initialrapidly extended chains – greater initial
force levelsforce levels
At 1 wk the chain stretched at slow rate-At 1 wk the chain stretched at slow rate-
exhibited less force decayexhibited less force decay
Recommended slow stretchingRecommended slow stretching

 Ash & Nikolai-1978Ash & Nikolai-1978 – compared force– compared force
decay of chains – stored in air , water anddecay of chains – stored in air , water and
vivovivo
 In vivo environment – significantly moreIn vivo environment – significantly more
force decay after 30 mins than those keptforce decay after 30 mins than those kept
in airin air
 After 3 wks – chains in vivo – greater forceAfter 3 wks – chains in vivo – greater force
loss than those stored in waterloss than those stored in water
 Both maintained force levels of moreBoth maintained force levels of more
than 160 gmsthan 160 gms

 Due to effects of mastication oral hygiene ,Due to effects of mastication oral hygiene ,
salivary enzymes & temp variationssalivary enzymes & temp variations
 Genova et alGenova et al – 1985– 1985 – investigated force– investigated force
degradation of chains - artificial salivadegradation of chains - artificial saliva
chains subjected to tooth movement retained 9-chains subjected to tooth movement retained 9-
13 % less force than held at constant length13 % less force than held at constant length
short filament chains – higher initial force levelsshort filament chains – higher initial force levels
& retain higher % of remaining force& retain higher % of remaining force

 Rock et alRock et al – tested 13 commercially– tested 13 commercially
available elasticsavailable elastics
 Regardless of the no. of loops , the forceRegardless of the no. of loops , the force
values at 100% extension were constantvalues at 100% extension were constant
 Short filament chains – higher initial forceShort filament chains – higher initial force
level at 100 % extension-403 to 625gmslevel at 100 % extension-403 to 625gms
 Recommended 50 – 75 % extension-Recommended 50 – 75 % extension-
desired force of 300 gmsdesired force of 300 gms

 Killiany et al – 1986Killiany et al – 1986 – force delivery and– force delivery and
decay characteristics of RMO – ENERGYdecay characteristics of RMO – ENERGY
chain – compared with short loop chainchain – compared with short loop chain
from American orthodonticsfrom American orthodontics
 After 4 wks – simulated oral environment –After 4 wks – simulated oral environment –
ENERGY chain – retained 66 % of initialENERGY chain – retained 66 % of initial
forceforce
short loop chain retained 33 % of originalshort loop chain retained 33 % of original
forceforce

 Kuster etal 1986-Kuster etal 1986- compared chains of 2compared chains of 2
companies stored in air & in vivocompanies stored in air & in vivo
 At 100% extension force levelsAt 100% extension force levels
315gm315gm
279gm279gm
 Initial extension of 50 -75% not supportedInitial extension of 50 -75% not supported

 Storie & FraunhoferStorie & Fraunhofer – compared gray– compared gray
chain & fluoride releasing chain fromchain & fluoride releasing chain from
ortho archortho arch
 conclusionconclusion
fluoride releasing chain – higher initialfluoride releasing chain – higher initial
force level at 100 % extensionforce level at 100 % extension
gray chain – retain 38 % of its initial forcegray chain – retain 38 % of its initial force
fluoride releasing chain – 14 % of initialfluoride releasing chain – 14 % of initial
force after 1 wk in 37 C distilled waterforce after 1 wk in 37 C distilled water

 Baty & Fraunhofer- compared 3Baty & Fraunhofer- compared 3
colour of elastomeric chains with stdcolour of elastomeric chains with std
gray chainsgray chains

Colouring had little effect on initial forceColouring had little effect on initial force
delivery of chainsdelivery of chains

Pre- stretching effectsPre- stretching effects
 Purpose – to improve the large initial forcePurpose – to improve the large initial force
degradation & the constancy of forcedegradation & the constancy of force
deliverydelivery
 WongWong – 1976 – pre stretching the elastic– 1976 – pre stretching the elastic
chains 1/3 of their original length –chains 1/3 of their original length –
improve the strengthimprove the strength
 Brooks & HersheyBrooks & Hershey – combination of pre– combination of pre
- stretching and heat app n – reduced the- stretching and heat app n – reduced the
amount of force degradation by 50 % at 1amount of force degradation by 50 % at 1
hr and 31 % at 4 wkshr and 31 % at 4 wks

 Heat appln alone – increased rate of forceHeat appln alone – increased rate of force
decaydecay
 Storie et alStorie et al – pre stretched gray and– pre stretched gray and
fluoride releasing chains – 50 % for 5 secsfluoride releasing chains – 50 % for 5 secs
Immersed in 3 fluid environmentsImmersed in 3 fluid environments
 Reported no clinical benefitReported no clinical benefit

Environmental effectsEnvironmental effects
 Ferriter – 1990Ferriter – 1990 – effect of ph extremes of– effect of ph extremes of
plaque (4.95) & saliva (7.26)plaque (4.95) & saliva (7.26)
 Chains – basic soln – exhibited more forceChains – basic soln – exhibited more force
decaydecay
 Jefferies et alJefferies et al – simulated disinfection 30– simulated disinfection 30
mins & sterilization (10 hrs & 1 wk ) usingmins & sterilization (10 hrs & 1 wk ) using
gluteraldehyde solngluteraldehyde soln
 Use of gluteraldehyde – no deleteriousUse of gluteraldehyde – no deleterious
effect on propertieseffect on properties

 Coffelt et al – subjected chains toCoffelt et al – subjected chains to
31 % APF31 % APF
4 % SNF4 % SNF
0.4 % Kcl soln0.4 % Kcl soln
 Concluded 31% APF had some effect onConcluded 31% APF had some effect on
the force delivery & decay ratethe force delivery & decay rate

summarysummary
 E chains lose 50- 70 % of their initial forceE chains lose 50- 70 % of their initial force
during the first day and at 3 wks retain only 30during the first day and at 3 wks retain only 30
-40 % of the original force-40 % of the original force
 Force guage should be used to determine theForce guage should be used to determine the
desired initial forcedesired initial force
 Longer filament chains deliver a lower initialLonger filament chains deliver a lower initial
force at the same extension than the closed loopforce at the same extension than the closed loop
chainchain
 Pre stretching of these chains – means ofPre stretching of these chains – means of
reducing the rapid force decay rate & a constantreducing the rapid force decay rate & a constant
forceforce

summarysummary
 Environmental factors – associated withEnvironmental factors – associated with
deformation & force degradationdeformation & force degradation
 The synthetic elastomeric chains –The synthetic elastomeric chains –
protected from direct lightprotected from direct light
 E chains – convenient , inexpensiveE chains – convenient , inexpensive
method – continuous force system over amethod – continuous force system over a
3-4 wk period3-4 wk period

White spot lesionWhite spot lesion
 Enamel de mineralizationEnamel de mineralization
 PreventionPrevention
1.1. Effective plaque controlEffective plaque control
2.2. Fluoride releaseFluoride release
a. fluoride varnishesa. fluoride varnishes
b. fluoride containing compositesb. fluoride containing composites
c. fluoride releasing GICc. fluoride releasing GIC
d. fluoride relesing elastomersd. fluoride relesing elastomers

 Enamel sealants – minimal benefit (BanksEnamel sealants – minimal benefit (Banks
& Richmond)& Richmond)
 Fluoride releasing composites – ineffectiveFluoride releasing composites – ineffective
in preventing enamel damage ( Mitchel ,in preventing enamel damage ( Mitchel ,
Turner – 1993 )Turner – 1993 )
 GIC – provides greater fluoride releaseGIC – provides greater fluoride release
 Inadequate bond strengthInadequate bond strength
 Featherstone – 1985 – long duration lowFeatherstone – 1985 – long duration low
dose fluoride release – reducesdose fluoride release – reduces
demineralizationdemineralization

 Fluoride releasing elastomeric modules –Fluoride releasing elastomeric modules –
provide such conditionsprovide such conditions
 Joseph & Gobler – 1993Joseph & Gobler – 1993 – study on the– study on the
rate and amount of SNF release from arate and amount of SNF release from a
fluoride impregnated elastic power chainfluoride impregnated elastic power chain
 MaterialMaterial
5 experimental groups & 1 control group5 experimental groups & 1 control group
12 unit length of F power chain (CFRD)12 unit length of F power chain (CFRD)
studiedstudied
37 C in a incubator & 100 rpm agitation37 C in a incubator & 100 rpm agitation

fluoride releasefluoride release
initially high – veryinitially high – very
low levels – after 1 wklow levels – after 1 wk
Minimum continuousMinimum continuous
level of 0.25 mg oflevel of 0.25 mg of
fluoride – necessaryfluoride – necessary
for remineralizationfor remineralization
Bactericidal effect atBactericidal effect at
low levels of fluoridelow levels of fluoride

 Protection only temporaryProtection only temporary
 Max benefit – elastics to be replaced atMax benefit – elastics to be replaced at
wkly intervalswkly intervals
 Regular topical appln of fluoride stillRegular topical appln of fluoride still
necessarynecessary

 William wiltshireWilliam wiltshire – 1996 – measured– 1996 – measured
release of fluoride from fluoride releasingrelease of fluoride from fluoride releasing
elastomeric modules ( fluor-I ties) in vitroelastomeric modules ( fluor-I ties) in vitro
 ResultsResults
initial burst of fluoride during the 1initial burst of fluoride during the 1stst
and 2and 2ndnd
day foll by a logarithmic decreaseday foll by a logarithmic decrease
 35 % - total fluoride at day 135 % - total fluoride at day 1
 63 % - 163 % - 1stst
wkwk
 83 % - 183 % - 1stst
monthmonth
 88 % - 288 % - 2ndnd
monthmonth
 At 6 months – 0.19 +/- 0.03 micro gmsAt 6 months – 0.19 +/- 0.03 micro gms

 For optimal clinical benefit – replaceFor optimal clinical benefit – replace
fluoride releasing ligature monthlyfluoride releasing ligature monthly
 Banks , Chadwik, AsherBanks , Chadwik, Asher
prospective controlled clinical trialprospective controlled clinical trial
To evaluate the effectiveness of SNFTo evaluate the effectiveness of SNF
releasing modules & chainreleasing modules & chain
MaterialsMaterials
49 ptns, 782 teeth- exptl group49 ptns, 782 teeth- exptl group
45 ptns, 740 teeth – control group, non45 ptns, 740 teeth – control group, non
fluoride releasing elastomericsfluoride releasing elastomerics

 After bonding excess composite removedAfter bonding excess composite removed
 Etching confinedEtching confined
 Standardized dietary & hygieneStandardized dietary & hygiene
instructionsinstructions
 Ptns scored by EDI ( EnamelPtns scored by EDI ( Enamel
Decalcification Index) – Banks &Decalcification Index) – Banks &
Richmond – 1994Richmond – 1994

EDIEDI


The use of fluoride releasing elastomericThe use of fluoride releasing elastomeric
modules – reduced enamel decalcification permodules – reduced enamel decalcification per
tooth by 49 %tooth by 49 %

Enamel decalcificationEnamel decalcification
control group – 26 % of teeth & 73 % ptnscontrol group – 26 % of teeth & 73 % ptns
exptl group – 16 % of teeth & 63 % ptnsexptl group – 16 % of teeth & 63 % ptns

Occlusal zones showed no differenceOcclusal zones showed no difference

Fluoride releasing elastomerics – effective inFluoride releasing elastomerics – effective in
reducing enamel decalcificationreducing enamel decalcification

Fibre reinforced compositeFibre reinforced composite
 Poly( ethylene tere phthalate glycol) &Poly( ethylene tere phthalate glycol) &
poly (1,4 cyclohexylene dimethylene terepoly (1,4 cyclohexylene dimethylene tere
phthalate glycol) reinforced withphthalate glycol) reinforced with
continuous glass fibrescontinuous glass fibres
 FRC contained -43-45 vol% fiberFRC contained -43-45 vol% fiber
 Flexural strength -565 MPaFlexural strength -565 MPa
 RequisitesRequisites
proper wetting of glass fibresproper wetting of glass fibres
proper orientation of glass fibresproper orientation of glass fibres

pultrusionpultrusion
 Fibre bundles – pulled through an extruderFibre bundles – pulled through an extruder
simultaneously with the extrusion of thesimultaneously with the extrusion of the
polymer.polymer.
 Fibre bundles impregnated by the polymerFibre bundles impregnated by the polymer
 Exiting dies determine cross sectionExiting dies determine cross section
shape and sizeshape and size

Electro micrographElectro micrograph

Fibre reinforced compositeFibre reinforced composite
 Burstone & GuntherBurstone & Gunther
20012001
 Enhanced mech.Enhanced mech.
propertiesproperties
 A metal attachmentA metal attachment
pad- FRC strip –pad- FRC strip –
exhibited superiorexhibited superior
bonding strengthbonding strength

 Highest failure – withHighest failure – with
loadings parallel toloadings parallel to
the tooth surfacethe tooth surface
 Less shear strengthLess shear strength

Charles Burstone& KuhlbergCharles Burstone& Kuhlberg
 Pre impregnated material – PREGPre impregnated material – PREG
partially polymerised fibre matrix complexpartially polymerised fibre matrix complex
ApplicationsApplications
1.1. Bonded cuspid to cuspid retainersBonded cuspid to cuspid retainers
2.2. BridgesBridges
active applicationsactive applications
- adjuncts for active tooth movements- adjuncts for active tooth movements

 Matrix – light cured thermoset BisgmaMatrix – light cured thermoset Bisgma
 Splint it – long fibre reinforced compositeSplint it – long fibre reinforced composite
 S glass fiber- bar more estheticS glass fiber- bar more esthetic
 Two stages of polymerizationTwo stages of polymerization
 Initial polymerization- matrix flexibleInitial polymerization- matrix flexible

PropertiesProperties
 ME – 70 % > highly filled compositeME – 70 % > highly filled composite
 YS – 6 times >YS – 6 times >
 Resiliency – 24 times >Resiliency – 24 times >

 Clinical useClinical use
- 3 configurations- 3 configurations
roperope
wide stripwide strip
woven patternwoven pattern

 TechniqueTechnique

FRC rope cut to lengthFRC rope cut to length

Transparent foil removedTransparent foil removed

Tooth prepared for bondingTooth prepared for bonding

FRC placed & contoured to toothFRC placed & contoured to tooth

Attachments are directly bonded to FRCAttachments are directly bonded to FRC

Low viscosity adhesive – protective layerLow viscosity adhesive – protective layer

Indirect or direct bondingIndirect or direct bonding

Active applicationActive application
FRC full arch

AttachmentsAttachments

IntermaxillaryIntermaxillary
elasticselastics

Vertical elastics- open biteVertical elastics- open bite

Extrusion of maxillary incisorExtrusion of maxillary incisor
segmentsegment

Space closureSpace closure

Molar uprightingMolar uprighting

Uprighting posterior segment withUprighting posterior segment with
tip back springtip back spring

Anterior lingual root torquing springAnterior lingual root torquing spring
combination with stainless steelcombination with stainless steel
arch wirearch wire

Maxillary incisor intrusionMaxillary incisor intrusion
TMA intrusion archTMA intrusion arch

Mandibular incisor intrusion archMandibular incisor intrusion arch

Replacement connectorsReplacement connectors

Maxillary lingual bonded FRCMaxillary lingual bonded FRC
retainerretainer

Connecting FRC frameworkConnecting FRC framework

summarysummary
 Long fibre reinforced materials have theLong fibre reinforced materials have the
potential to replace metals in clinicalpotential to replace metals in clinical
orthodonticsorthodontics
 Biocompatibility not a concernBiocompatibility not a concern
 FRC materials are superior to polymersFRC materials are superior to polymers
 Increased rigidity and strengthIncreased rigidity and strength
 Highly formable – fabricated in complexHighly formable – fabricated in complex
shapesshapes

 Layers can be added to change the shapeLayers can be added to change the shape
- improve rigidity- improve rigidity
 Precise contour to the teethPrecise contour to the teeth
 Potential to alter some of the currentPotential to alter some of the current
methods of active treatmentmethods of active treatment
 Esthetic alternative to lingual orthodonticsEsthetic alternative to lingual orthodontics

 Ptns who need only partial orPtns who need only partial or
compromised treatment are goodcompromised treatment are good
candidates for FRC appliancescandidates for FRC appliances
 Mixed dentition casesMixed dentition cases
 FRC bars- alternative to bandsFRC bars- alternative to bands

 DisadvantageDisadvantage
weakest in shearweakest in shear
Shear loads to be minimized as much asShear loads to be minimized as much as
possiblepossible
Requires good bonding conditionsRequires good bonding conditions
eg – bridges and retainerseg – bridges and retainers

BiodegradationBiodegradation
 Orthodontic materials – Universally austentic SSOrthodontic materials – Universally austentic SS
- 18% chromium- 18% chromium
- 8% nickel- 8% nickel
NiTi – 1970sNiTi – 1970s
Oral environment – ionic propertiesOral environment – ionic properties
thermal propertiesthermal properties
microbiologicmicrobiologic
enzymaticenzymatic
Ideal for biodegradationIdeal for biodegradation

 Human exposure to NiHuman exposure to Ni
- dietdiet
- atmosphere- atmosphere
- jewelry- jewelry
- water- water
- clothing- clothing
- fasteners- fasteners

 Dietary intakeDietary intake
- Ni – 200 -300 microgms / day- Ni – 200 -300 microgms / day
- Cr – 280 microgms / day- Cr – 280 microgms / day
- Ti – 300 – 2000 microgms/day- Ti – 300 – 2000 microgms/day
Water – 20 microgms / l – NiWater – 20 microgms / l – Ni
- 0.43 microgms/l- Cr- 0.43 microgms/l- Cr

 Iatrogenic exposureIatrogenic exposure
Joint prosthesisJoint prosthesis
Dental implantsDental implants
Orthopedic platesOrthopedic plates
Surgical clipsSurgical clips
Pace maker leadsPace maker leads
Prosthetic heart valvesProsthetic heart valves
orthodontic appliancesorthodontic appliances
Ni release – dental alloy – 4.2Ni release – dental alloy – 4.2
microgms/cm/daymicrogms/cm/daywww.indiandentalacademy.comwww.indiandentalacademy.com

36micgms/day – Cr36micgms/day – Cr
Full mouth ortho appliances –Full mouth ortho appliances –
40micgms/day – Ni40micgms/day – Ni
Heat treated-SS arch wire-Heat treated-SS arch wire-
0.26micgms/cm/day0.26micgms/cm/day

Bishara , Barret – 1993Bishara , Barret – 1993 ::
Purpose – Compare in vitro corrosion rate for stdPurpose – Compare in vitro corrosion rate for std
orthodontic appliancesorthodontic appliances
Appliance immersed – prepared artificial salivaAppliance immersed – prepared artificial saliva
at 37cat 37c
MaterialsMaterials
10 sets of bands and brackets10 sets of bands and brackets
Both SS & NiTi archwiresBoth SS & NiTi archwires

-Type 305 – SS – bands-Type 305 – SS – bands AISIAISI
-Type 316 – SS – brackets and tubes-Type 316 – SS – brackets and tubes AISIAISI
-Bands not covered from inner surface-Bands not covered from inner surface
-17- 25 wires-17- 25 wires
-5 sets – rectangular SS wires-5 sets – rectangular SS wires
-5 sets – Ni Ti – Unitek-5 sets – Ni Ti – Unitek
Polyethylene tubes – 100 mlPolyethylene tubes – 100 ml
Artificial saliva – pH – 6.75Artificial saliva – pH – 6.75

 Analyzed –Analyzed –
1,7,14,21,28 days1,7,14,21,28 days
 Results –Results –
 Ni – peak level – dayNi – peak level – day
77thth
 Park and ShearerPark and Shearer
similar findingssimilar findings

 Cr – peak level 14Cr – peak level 14thth
dayday

ConclusionConclusion
 Orthodontic appliances -reasonable amts of Ni &Orthodontic appliances -reasonable amts of Ni &
Cr when placed in a artificial saliva mediumCr when placed in a artificial saliva medium
 Ni release reaches max after 1 week thenNi release reaches max after 1 week then
diminishesdiminishes
 Cr release increases during the first 2 weeksCr release increases during the first 2 weeks
and levels off during subsequent 2 weeksand levels off during subsequent 2 weeks
 Release rates of Ni & Cr from SS or NiTi wire –Release rates of Ni & Cr from SS or NiTi wire –
not significantly different.not significantly different.

ConclusionConclusion
 For both archwire types the release rateFor both archwire types the release rate
for Ni averaged 37 times greater than thatfor Ni averaged 37 times greater than that
for Cr.for Cr.
 The release rates for full mouthThe release rates for full mouth
orthodontic appliances are less than 10%orthodontic appliances are less than 10%
of the reported average daily dietaryof the reported average daily dietary
intake for Ni & .25% of those reported forintake for Ni & .25% of those reported for
Cr.Cr.

 Changes in the blood level of nickelChanges in the blood level of nickel
Bishara,BarretBishara,Barret
Purpose: to determine whether orthodonticPurpose: to determine whether orthodontic
patients accumulate measurablepatients accumulate measurable
concentrations of Ni in blood.concentrations of Ni in blood.
Materials:Materials:
31 subjects – 18 females & 13 males.31 subjects – 18 females & 13 males.
Blood samples collectedBlood samples collected
1 – before placement of orthodontic1 – before placement of orthodontic
applianceappliance
2 – 2 months after placement2 – 2 months after placement
3 – 4-5 months after placement3 – 4-5 months after placement

Blood analyzed – atomic absorption spectroBlood analyzed – atomic absorption spectro
photometryphotometry
Nickel and Chromium carcinogenicityNickel and Chromium carcinogenicity
Ni – risk inversely proportional to solubility inNi – risk inversely proportional to solubility in
aqueous mediaaqueous media
Cr – hexavalent oxidation stateCr – hexavalent oxidation state
Normal Ni & Cr conc in bloodNormal Ni & Cr conc in blood
Ni – 2.4 +/- 0.5 ng/ml & 30 +/- 19 ng/mlNi – 2.4 +/- 0.5 ng/ml & 30 +/- 19 ng/ml
Cr – 0.371 ng/mlCr – 0.371 ng/ml

 Hexavalant Cr – readily absorbedHexavalant Cr – readily absorbed
 Elimination – urine.Elimination – urine.
ResultsResults ––
 Ni levels in bloodNi levels in blood
 All blood levels below normalAll blood levels below normal
 17.2% of blood samples – above detection limit17.2% of blood samples – above detection limit
of .4 ppbof .4 ppb
 never exceeded 1.3ppbnever exceeded 1.3ppb

 16 patients no detectable Ni levels16 patients no detectable Ni levels
 5 patients reduction in blood level5 patients reduction in blood level
Higher values –Higher values –
 Contamination from venipunctureContamination from venipuncture
needleneedle
 DietDiet

SUMMARYSUMMARY
 Patients with fully banded & bondedPatients with fully banded & bonded
appliances did not show a significantappliances did not show a significant
increase in the Ni blood level during the 1increase in the Ni blood level during the 1stst
4-5 mnts of orthodontic therapy4-5 mnts of orthodontic therapy
 Orthodontic therapy using appliancesOrthodontic therapy using appliances
made of alloys containing Ni-Ti did notmade of alloys containing Ni-Ti did not
result in significant increase in the bloodresult in significant increase in the blood
levels of Ni.levels of Ni.

Grimsdottir 1992Grimsdottir 1992
 Facebows,archwires,brackets& molarFacebows,archwires,brackets& molar
bands analyzedbands analyzed
 Most appliances – variable amount –AgMost appliances – variable amount –Ag
soldersolder
 14days in 0.9Nacl14days in 0.9Nacl
 Facebows – highest amount of NI &CrFacebows – highest amount of NI &Cr
 Archwires- leastArchwires- least

Park & ShearerPark & Shearer
 Ni &Cr release-simulated ortho applianceNi &Cr release-simulated ortho appliance
 incubated in 0.05%Naclincubated in 0.05%Nacl
 Ni-40micgms/dayNi-40micgms/day
 Cr-36 micgms/dayCr-36 micgms/day
 below the daily dietary intakebelow the daily dietary intake
 may sensitize patientsmay sensitize patients

Metal release from simulated fixedMetal release from simulated fixed
orthodontic appliances – AJO 2001orthodontic appliances – AJO 2001
Hwang etalHwang etal
MethodMethod
Simulated fixed orthodontic appliancesSimulated fixed orthodontic appliances
---soaked in 50 ml of artificial saliva---soaked in 50 ml of artificial saliva
pH – 6.75 +/- .15 at 37 CpH – 6.75 +/- .15 at 37 C
Time period – 3 monthsTime period – 3 months
4 groups ( 16 – 22)4 groups ( 16 – 22)
2 SS wires2 SS wires
2 Ni-Ti arch wires2 Ni-Ti arch wires

Composition of artificial salivaComposition of artificial saliva

320 polyethylene tubes – 50 ml artificial320 polyethylene tubes – 50 ml artificial
salivasaliva
MethodMethod
Metal release – plasma mass spectrometryMetal release – plasma mass spectrometry
Analyzed onAnalyzed on
11stst
, 3, 3rdrd
days, 1days, 1stst
22ndnd
33rdrd
44thth
88thth
&12&12thth
weeksweeks

ResultsResults
Cr release – noCr release – no
increase after 4increase after 4
weeks –weeks –
gp Agp A
-- 2 weeks in gp B-- 2 weeks in gp B
-- 3 weeks in gp C-- 3 weeks in gp C
-- 8 weeks in gp D-- 8 weeks in gp D

Ni release – no increaseNi release – no increase
after 2 weeks – gp Aafter 2 weeks – gp A
-- 3 days in gp B-- 3 days in gp B
-- 7 days in gp C-- 7 days in gp C
-- 3 weeks in gp D-- 3 weeks in gp D

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

CONCLUSIONCONCLUSION
The daily amount of Cr & Ni released –The daily amount of Cr & Ni released –
insignificant when compared with – dailyinsignificant when compared with – daily
dietary intake of these metalsdietary intake of these metals
Such a small amount of release mightSuch a small amount of release might
produce sensitivity when the orthodonticproduce sensitivity when the orthodontic
appliance are in place for 2-3 yearsappliance are in place for 2-3 years
For an allergic reaction in the oral mucosaFor an allergic reaction in the oral mucosa
an antigen must be 5 – 12 times greateran antigen must be 5 – 12 times greater
than that needed for a skin allergythan that needed for a skin allergy

Leaching of Ni Cr and Be ions fromLeaching of Ni Cr and Be ions from
base metal alloy in an artificial oralbase metal alloy in an artificial oral
environmentenvironment --Yong--Yong
Tai, Ralf D Long, J PROSTTai, Ralf D Long, J PROST DENT 1992DENT 1992
MethodMethod
Artificial oral environment – 3D force movementArtificial oral environment – 3D force movement
cycles of masticationcycles of mastication
12 pairs of crowns articulated12 pairs of crowns articulated
Metal vs metalMetal vs metal
Metal vs enamelMetal vs enamel
Metal vs procelainMetal vs procelain
Metal vs metal without chewing as a controlMetal vs metal without chewing as a control

1 year simulated – period of mastication1 year simulated – period of mastication
ResultsResults
In vitro analysis in artificial environment –In vitro analysis in artificial environment –
release of Ni & Be from base metal alloyrelease of Ni & Be from base metal alloy
Dissolution & Occlusal wear are both factorsDissolution & Occlusal wear are both factors
in the release of Ni & Be metalsin the release of Ni & Be metals
Occlusal wear increases the concs 2-3Occlusal wear increases the concs 2-3
times more – than with dissolution alone.times more – than with dissolution alone.

HypersensitivityHypersensitivity
Refers to the injurious consequences in theRefers to the injurious consequences in the
sensitized host following contact withsensitized host following contact with
specific antigens.specific antigens.
Incidence of Ni sensitivityIncidence of Ni sensitivity
Greg, Dulap, Moffa – allergic response to NiGreg, Dulap, Moffa – allergic response to Ni
containing dental alloys.containing dental alloys.

 Ni toxicity – moderately cytotoxicNi toxicity – moderately cytotoxic
 Cr toxicity – littleCr toxicity – little
Grimsdotir & HanstenGrimsdotir & Hansten – saliva --– saliva --
connecting medium – discharge of ions &connecting medium – discharge of ions &
metal compounds – combine withmetal compounds – combine with
chemically corroded metal – attach tochemically corroded metal – attach to
mucosa.mucosa.

Alan & SmithAlan & Smith – incidence rate of– incidence rate of
hypersensitivity – 10%hypersensitivity – 10%
Blane & PeltononBlane & Peltonon – estimated that 4.5 –– estimated that 4.5 –
28.5 of popln – have sensitivity to Ni28.5 of popln – have sensitivity to Ni
Higher prevalence in femalesHigher prevalence in females
 Janson & ParkJanson & Park – hypersensitivity in– hypersensitivity in
females – related to environmentalfemales – related to environmental
exposure – contact with detergentsexposure – contact with detergents
jewellery & other metallic objectsjewellery & other metallic objects

 Factors affecting development ofFactors affecting development of
sensitizationsensitization
 Raitt and BrostoffRaitt and Brostoff ––
 Mechanical irritationMechanical irritation
 Skin lacerationSkin laceration
 Increased environmental temperatureIncreased environmental temperature
 Increased intensity and duration ofIncreased intensity and duration of
exposureexposure
 Genetic factorsGenetic factors

Dietary intakeDietary intake
 Ni - 200 – 300 micgms / dayNi - 200 – 300 micgms / day
 Cr – 250 micgms / dayCr – 250 micgms / day
 Drinking water – 20 micgms / l – Ni (Bencho )Drinking water – 20 micgms / l – Ni (Bencho )
 Amount of Ni releaseAmount of Ni release
 Grims DottarGrims Dottar – largest amount of Ni – released– largest amount of Ni – released
from facebow – silver solderfrom facebow – silver solder
Brackets -- .3-.9 micgms/dayBrackets -- .3-.9 micgms/day
SS archwire -- .26 micgms/cm.sq/daySS archwire -- .26 micgms/cm.sq/day

 Form of release - Ni – solubleForm of release - Ni – soluble
 Cr – insolubleCr – insoluble
 Allergy more common in extra oral -- intraAllergy more common in extra oral -- intra
oral appliances – 6 timesoral appliances – 6 times
5-12 times higher conc needed – oral5-12 times higher conc needed – oral
mucosamucosa

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

 No increase in blood level of Ni – 5No increase in blood level of Ni – 5
months of Ortho t/t - Bisharamonths of Ortho t/t - Bishara

Hypersensitivity reactionsHypersensitivity reactions
 Dental AlloysDental Alloys
 Symptoms of allergic reactions – dental alloysSymptoms of allergic reactions – dental alloys
 Inflammed hyperplastic gingival tissueInflammed hyperplastic gingival tissue
 Alveolar bone loss -- crownsAlveolar bone loss -- crowns
 Edema of throat, palate, gumsEdema of throat, palate, gums
 Osteomyelitis – SS bone fixation wiresOsteomyelitis – SS bone fixation wires
 Orthodontic appliances – face bows & neckOrthodontic appliances – face bows & neck
straps, Ni-Ti arch wiresstraps, Ni-Ti arch wires
 ,,

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

Immunologic mechanismImmunologic mechanism
Ni – common cause – contact dermatitisNi – common cause – contact dermatitis
Delayed hypersensitivity reactionDelayed hypersensitivity reaction
Induction phaseInduction phase
Elucidation phaseElucidation phase
Diagnosis –Diagnosis –
ptn historyptn history
clinical findingsclinical findings
patch testingpatch testing

Different corrosion resistantDifferent corrosion resistant
materials – used inmaterials – used in
Hypersensitivity ptnsHypersensitivity ptns
AISI 316 L steel – most corrosion resistantAISI 316 L steel – most corrosion resistant
AISI 304 L steelAISI 304 L steel
PIA 17 – 4PIA 17 – 4
Bio force ion guard wire – 3 micron nitrogenBio force ion guard wire – 3 micron nitrogen
coatingcoating
Pyramid manufacturers – steel -- hypoPyramid manufacturers – steel -- hypo
allergicallergic

ConclusionsConclusions
The daily amount of Cr & Ni released –The daily amount of Cr & Ni released –
insignificant when compared with – dailyinsignificant when compared with – daily
dietary intake of these metalsdietary intake of these metals
Such a small amount of release mightSuch a small amount of release might
produce sensitivity when the orthodonticproduce sensitivity when the orthodontic
appliance are in place for 2-3 yearsappliance are in place for 2-3 years
For an allergic reaction in the oral mucosaFor an allergic reaction in the oral mucosa
an antigen must be 5 – 12 times greateran antigen must be 5 – 12 times greater
than that needed for a skin allergythan that needed for a skin allergy

 Patients with fully banded & bondedPatients with fully banded & bonded
appliances did not show a significantappliances did not show a significant
increase in the Ni blood level during the 1increase in the Ni blood level during the 1stst
4-5 mnts of orthodontic therapy4-5 mnts of orthodontic therapy
 Orthodontic therapy using appliancesOrthodontic therapy using appliances
made of alloys containing Ni-Ti did notmade of alloys containing Ni-Ti did not
result in significant increase in the bloodresult in significant increase in the blood
levels of Ni.levels of Ni.

 The release rates for full mouthThe release rates for full mouth
orthodontic appliances are less than 10%orthodontic appliances are less than 10%
of the reported average daily dietaryof the reported average daily dietary
intake for Ni & .25% of those reported forintake for Ni & .25% of those reported for
Cr.Cr.

Orthodontic appliancesOrthodontic appliances
Strong biologic sensitizersStrong biologic sensitizers

..
Janson & PrystouskyJanson & Prystousky -- age range 10-20-- age range 10-20
yearsyears

Raitt and BrostoffRaitt and Brostoff – several factors for– several factors for
the development of sensitizationthe development of sensitization
 Mechanical irritationMechanical irritation
 Skin lacerationSkin laceration
 Increased environmental temperatureIncreased environmental temperature
 Increased intensity and duration ofIncreased intensity and duration of
exposureexposure
 Genetic factorsGenetic factors

Kawahara & YamakawaKawahara & Yamakawa – Ni –– Ni –
moderately cytotoxic & Cr – little toxicity.moderately cytotoxic & Cr – little toxicity.
Grandjsan et alGrandjsan et al – avg dietary intake– avg dietary intake
Ni – 200 -300 micgms./dayNi – 200 -300 micgms./day
Cr – 250 micgms/dayCr – 250 micgms/day

Benco –Benco – Ni concs – drinking water belowNi concs – drinking water below
20 micgm/ltr.20 micgm/ltr.
-- below the normal dietary intake-not-- below the normal dietary intake-not
clinically significantclinically significant

Majjer & SmithMajjer & Smith – Ni released – soluble– Ni released – soluble
compoundcompound
Cr – insoluble formCr – insoluble form
Greg & TemovariGreg & Temovari – reaction – use of– reaction – use of
facebow – Ni-Ti arch wiresfacebow – Ni-Ti arch wires
Moffa et alMoffa et al – allergic response to Ni– allergic response to Ni
containing dental alloyscontaining dental alloys
Dulap et al –Dulap et al – allergic reaction – insertion ofallergic reaction – insertion of
Ni-Ti wire in sensitive patientNi-Ti wire in sensitive patient

Jacobson & HenstenJacobson & Hensten ––

Park & ShearerPark & Shearer -- Ni from orthodontic-- Ni from orthodontic
bands – sensitized ptns. – causebands – sensitized ptns. – cause
hypersensitivity reactions in ptns with priorhypersensitivity reactions in ptns with prior
h/o hs.h/o hs.
James et alJames et al – no relationship betwn a +ve– no relationship betwn a +ve
recn to Ni & a clinical response to Nirecn to Ni & a clinical response to Ni
containing dental alloycontaining dental alloy
Stearh Jear et alStearh Jear et al – no risk involved for Ni– no risk involved for Ni
sensitive ptnssensitive ptns

Bishara, BarreteBishara, Barrete – no increase in blood– no increase in blood
level of Ni – 5 months of orthodonticlevel of Ni – 5 months of orthodontic
treatment.treatment.
Magnuson & NeilsonMagnuson & Neilson – higher level of– higher level of
Ni conc – needed to elicit – intra oralNi conc – needed to elicit – intra oral
responseresponse

FischerFischer – sensitivity test – not to be used– sensitivity test – not to be used
indiscriminatelyindiscriminately
Vijayabasava, Surendra ShettyVijayabasava, Surendra Shetty ––
decrease in pH – increase in Nidecrease in pH – increase in Ni
Highest – pH 5.8Highest – pH 5.8
Ni release – less than 5-10% daily dietaryNi release – less than 5-10% daily dietary
intakeintake
Ross Levy et alRoss Levy et al – orthodontic appliance –– orthodontic appliance –
induce sensitivity – little or no effect on theinduce sensitivity – little or no effect on the
gingiva of the ptn.gingiva of the ptn.

RecyclingRecycling
““ Involves repeated exposure of theInvolves repeated exposure of the
appliance for several wks to mechanicalappliance for several wks to mechanical
stresses or elements of the oralstresses or elements of the oral
environment as well as sterilization b/wenvironment as well as sterilization b/w
uses.uses.
May result in corrosion and biodegradationMay result in corrosion and biodegradation
of the wireof the wire
Alteration in propertiesAlteration in properties

RecyclingRecycling
 Niti – desirable mechanical propNiti – desirable mechanical prop

Relatively high costRelatively high cost

Buckthal et al – 52% orthodontists recycle NiBuckthal et al – 52% orthodontists recycle Ni
ti wiresti wires

80% cold methods – disinfection80% cold methods – disinfection

Cold & heat sterilization – don’t affectCold & heat sterilization – don’t affect
mechanical propertiesmechanical properties

Harris et al – simulated oral environmentHarris et al – simulated oral environment
0.016 Nitinol wires0.016 Nitinol wires

 Concluded – significant decrease in YS –Concluded – significant decrease in YS –
4 month period4 month period

Effects of clinical recycling onEffects of clinical recycling on
mechanical properties of Niti alloy wiresmechanical properties of Niti alloy wires
-sunil kapila-1991-sunil kapila-1991
 Materials and methodsMaterials and methods
60 wires – Nitinol & Niti wires60 wires – Nitinol & Niti wires
3 point bending test – mechanical3 point bending test – mechanical
propertiesproperties
SEM – surface characteristicsSEM – surface characteristics

 WiresWires
To – as received conditionTo – as received condition
T1 – 8 wks of clinical exposure ( 1T1 – 8 wks of clinical exposure ( 1
cycle)cycle)
T2 – 2 cyclesT2 – 2 cycles
Cold recycled after one clinical cycle-Cold recycled after one clinical cycle-
isopropyl alcoholisopropyl alcohol
ResultsResults
Nitinol wires subjected to 1 or 2 recyclesNitinol wires subjected to 1 or 2 recycles
demonstrated statistically significantdemonstrated statistically significant
differences during loading then control Todifferences during loading then control To

 SEM of both Nitinol and Niti wiresSEM of both Nitinol and Niti wires
demonstrated increased pitting of wiresdemonstrated increased pitting of wires
after clinical exposureafter clinical exposure
 Some smoothening of Nitinol wires wereSome smoothening of Nitinol wires were
also observed in localised regions of thealso observed in localised regions of the
wirewire

Surface characteristicsSurface characteristics

Recycling of orthodontic bracketsRecycling of orthodontic brackets

British surveyBritish survey – 47.5 % of clinicians– 47.5 % of clinicians
recycle metal bracketsrecycle metal brackets

recycled brackets – acceleratesrecycled brackets – accelerates
corrosion processcorrosion process

wheeler and Ackermannwheeler and Ackermann – reduction– reduction
in mesh diameter – recycling – noin mesh diameter – recycling – no
significant change in bond strengthsignificant change in bond strength

 Mascia and chenMascia and chen – decrease in shear– decrease in shear
bond strengthbond strength
 Hixon et al –Hixon et al – studied change in bracketstudied change in bracket
slot tolerance after recycling of bracketsslot tolerance after recycling of brackets
 concluded – no statistically significantconcluded – no statistically significant
change in the tolerance through twochange in the tolerance through two
successive recyclessuccessive recycles
 ChapmanChapman – bracket slot - increase in– bracket slot - increase in
width – proportionate to no. of times it iswidth – proportionate to no. of times it is
recycledrecycled

comparison of iron release fromcomparison of iron release from
new and recycled orthodonticnew and recycled orthodontic
brackets-Huang & Yen- AJO2001brackets-Huang & Yen- AJO2001
 purposepurpose – compare release of ions– compare release of ions
Ni, Mn , FeNi, Mn , Fe

materials and methodsmaterials and methods – 12 wk– 12 wk
periodperiod

recycle brackets – coated withrecycle brackets – coated with
adhesive and heat treatedadhesive and heat treated

atomic absorption – detection of ionsatomic absorption – detection of ions

 surface characteristics – energy dispersivesurface characteristics – energy dispersive
radiographic analysisradiographic analysis
 ResultsResults – recycled brackets released– recycled brackets released
more ions than new bracketsmore ions than new brackets
 Both new and recycled brackets canBoth new and recycled brackets can
degrade in solnsdegrade in solns
 Greater amounts of Ni, Mn and Fe ionsGreater amounts of Ni, Mn and Fe ions
were released in the artificial saliva solnwere released in the artificial saliva soln
than in other buffer solnsthan in other buffer solns

 The brackets release greater amounts ofThe brackets release greater amounts of
ions in a ph 4 buffer than in ph 7 or 10ions in a ph 4 buffer than in ph 7 or 10
bufferbuffer
 As the immersion time increased so didAs the immersion time increased so did
the ion releasethe ion release
 After 12 wk immersion the total amount ofAfter 12 wk immersion the total amount of
ion release was less than the cumulativeion release was less than the cumulative
daily intake-daily intake-

Effect of recycling on theEffect of recycling on the
mechanical properties and surfacemechanical properties and surface
topography of Niti alloy wirestopography of Niti alloy wires
Sung ho lee & Chang – AJO 2001Sung ho lee & Chang – AJO 2001
Parameters –Parameters –
mechanical propertiesmechanical properties
surface topographysurface topography
frictional forcesfrictional forces

 MaterialsMaterials
3 types of Niti wires – 60 wires3 types of Niti wires – 60 wires
16. 22 rectangular wires16. 22 rectangular wires
1.1. As received condition – To - controlAs received condition – To - control
groupgroup
2.2. Treated in artificial saliva for 4 wks – T1Treated in artificial saliva for 4 wks – T1
3.3. Treated in artificial saliva & autoclaved –Treated in artificial saliva & autoclaved –
T2T2
Method – maintained in a incubator at 37 CMethod – maintained in a incubator at 37 C

 ResultsResults – Niti wires demonstrated no– Niti wires demonstrated no
statistically significant differences in maxstatistically significant differences in max
tensile strength , ME and bending fatiguetensile strength , ME and bending fatigue
 Niti and Optimalloy demonstratedNiti and Optimalloy demonstrated
increased pitting and corrosion onincreased pitting and corrosion on
recycling , Sent alloy did notrecycling , Sent alloy did not
 Recycled NIti and OptimalloyRecycled NIti and Optimalloy
demonstrated greater surface roughness ,demonstrated greater surface roughness ,
Sent alloy did not .Sent alloy did not .

 Recycled Niti and OptimalloyRecycled Niti and Optimalloy
demonstrated significantly greater maxdemonstrated significantly greater max
frictional co.eff s than did the controlfrictional co.eff s than did the control
group.group.
 Sent alloy showed no difference.Sent alloy showed no difference.
 Surface roughness and frictional co.eff ofSurface roughness and frictional co.eff of
recycled Niti and Optimalloy were notrecycled Niti and Optimalloy were not
more than those of Sent alloy controlmore than those of Sent alloy control
groupgroup

changes in bracket slot tolerencechanges in bracket slot tolerence
following recycling of direct bondfollowing recycling of direct bond
metallic orthodontic appliancesmetallic orthodontic appliances
-Mark Hixson-Mark Hixson
Materials and methods –Materials and methods –
Stainless steel – direct bond brackets – 3Stainless steel – direct bond brackets – 3
different companiesdifferent companies
Evaluated for changes in ability to beEvaluated for changes in ability to be
torqued by rectangular arch wire aftertorqued by rectangular arch wire after
being recycledbeing recycled
75 0.022 * 0.028 brackets75 0.022 * 0.028 brackets

 Torque meter assemblyTorque meter assembly

conclusionconclusion – recycling of brackets– recycling of brackets
results in no significant change in theresults in no significant change in the
tolerance through two successive recyclestolerance through two successive recycles
 The max increase in tolerance after 2The max increase in tolerance after 2
recycles was approximately 3 degreesrecycles was approximately 3 degrees

Effect of recycling on shear bondEffect of recycling on shear bond
strength – D N Kapoor, Pradeepstrength – D N Kapoor, Pradeep
Tandon – JIOS sep 03Tandon – JIOS sep 03
 Purpose – compare the reconditioningPurpose – compare the reconditioning
methods like flaming ,sand blasting andmethods like flaming ,sand blasting and
solvent disolutionsolvent disolution
 Bond strength – universal instron testingBond strength – universal instron testing
machinemachine

ResultsResults
 New brackets bonded to freshly extractedNew brackets bonded to freshly extracted
teeth produce higher shear bond strengthteeth produce higher shear bond strength
when compared to re-bonded bracketswhen compared to re-bonded brackets
bonded to freshly extracted teeth and/orbonded to freshly extracted teeth and/or
reconditioned enamel surfacereconditioned enamel surface
 Flaming and sand blasting method for reFlaming and sand blasting method for re
conditioning of brackets demonstratesconditioning of brackets demonstrates
highest shear bond strengthhighest shear bond strength

ResultsResults
 Rebonded brackets after re conditioningRebonded brackets after re conditioning
by solvent disolution method exhibit moreby solvent disolution method exhibit more
than optimum shear bond strength andthan optimum shear bond strength and
can be an effective chemical method forcan be an effective chemical method for
reconditioningreconditioning
 Lowest value of shear bond strength wasLowest value of shear bond strength was
seen when the bracket - reconditioned byseen when the bracket - reconditioned by
flaming was bonded to reconditionedflaming was bonded to reconditioned
enamel surfaceenamel surface

resultsresults
 Significant alteration In the enamel surfaceSignificant alteration In the enamel surface
was not observed due to repeatedwas not observed due to repeated
bonding - SEMbonding - SEM

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