Bonding & debonding2

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CONTENTSCONTENTS
 IntroductionIntroduction
 HistoryHistory
 Bonding AdhesivesBonding Adhesives
 Bracket BondingBracket Bonding
- Direct bonding- Direct bonding
- Indirect bonding- Indirect bonding
 Bonding to crowns and restorationsBonding to crowns and restorations
 Bond failuresBond failures
 RebondingRebonding
 RecyclingRecycling
 DebondingDebonding
 ConclusionConclusion

INTRODUCTIONINTRODUCTION
Orthodontics is a dynamically growing science. It is constantlyOrthodontics is a dynamically growing science. It is constantly
undergoing development and is evolving through the discovery ofundergoing development and is evolving through the discovery of
newer techniques and materials and improvements over the oldernewer techniques and materials and improvements over the older
ones.ones.
Bonding of brackets, eliminating the need for bands was a dreamBonding of brackets, eliminating the need for bands was a dream
for many years before becoming a routine clinical procedure in thefor many years before becoming a routine clinical procedure in the
1980’s.1980’s.
One of the most important events inOne of the most important events in
orthodontics appliance was the introduction of direct Bonding. This wasorthodontics appliance was the introduction of direct Bonding. This was
the direct result of the pioneering work bythe direct result of the pioneering work by BuonocoreBuonocore in the 1950’sin the 1950’s
and since steady stream of materials has been developed for theand since steady stream of materials has been developed for the
purpose.purpose.

 Buonocore (1955):Buonocore (1955): Demonstrated the increased adhesion ofDemonstrated the increased adhesion of
attachments to tooth surface by conditioning the enamel surfaceattachments to tooth surface by conditioning the enamel surface
withwith 85% phosphoric acid for 30 seconds85% phosphoric acid for 30 seconds..
 Sadler (1958):Sadler (1958): Attempts to cement orthodontic attachments directlyAttempts to cement orthodontic attachments directly
to enamel without etching have been recorded. Sadler tested nineto enamel without etching have been recorded. Sadler tested nine
materials (four dental cements, one rubber base cement, two metalmaterials (four dental cements, one rubber base cement, two metal
adhesives and two general purpose adhesives) but these were alladhesives and two general purpose adhesives) but these were all
unsuccessfulunsuccessful..
 Bowen (1962)Bowen (1962) developed a new resin system,developed a new resin system, Bisphenol-A-GlycidyBisphenol-A-Glycidyll
dimethacrylatedimethacrylate commonly known as BIS-GMA and is often referredcommonly known as BIS-GMA and is often referred
to as “Bowen’s Resin”.to as “Bowen’s Resin”.

 Newman (1965)Newman (1965) was the first to bond orthodontic attachments towas the first to bond orthodontic attachments to
teeth by means of an epoxy resinteeth by means of an epoxy resin. He used a mixture consisting of. He used a mixture consisting of
equal parts of low molecular weight epoxy liquid and a highequal parts of low molecular weight epoxy liquid and a high
molecular weight solid epoxy with a polyamide curing agent.molecular weight solid epoxy with a polyamide curing agent.
 Cueto (1966)Cueto (1966), his experiment was done to see if it was feasible to, his experiment was done to see if it was feasible to
attach a bracket directly to tooth enamel without the use ofattach a bracket directly to tooth enamel without the use of
orthodontic bands. The adhesive consisted of a liquid monomer,orthodontic bands. The adhesive consisted of a liquid monomer,
methyl-2-cyanoacrylate, and a silicate filler.methyl-2-cyanoacrylate, and a silicate filler.
 Mitchel (1967)Mitchel (1967) had failures with an epoxy resin but described ahad failures with an epoxy resin but described a
successful, although limited, clinical trial using black copper cementsuccessful, although limited, clinical trial using black copper cement
and gold direct attachments.and gold direct attachments.

 Buonocore et al (1968)Buonocore et al (1968) showed that enhanced bonding to acidshowed that enhanced bonding to acid
conditioned surfaces were due to the presence ofconditioned surfaces were due to the presence of “prism like”“prism like” tagstags
and also observed poor bonding with unconditioned enameland also observed poor bonding with unconditioned enamel
surfaces.surfaces.
 Smith (1968)Smith (1968) introducedintroduced Zinc polyacrylateZinc polyacrylate and bracket bonding withand bracket bonding with
cement was reported.cement was reported.
 Miura et al (1971)Miura et al (1971) experimented with a new catalyst (a modifiedexperimented with a new catalyst (a modified
trialkyl borane) and introducedtrialkyl borane) and introduced orthomiteorthomite. This proved to be. This proved to be
particularly successful for bonding plastic brackets and forparticularly successful for bonding plastic brackets and for
enhanced adhesion in the presence of moisture.enhanced adhesion in the presence of moisture.

 Retief (1973)Retief (1973) described the importance of preconditioning withdescribed the importance of preconditioning with 50%50%
phosphoric acidphosphoric acid..
 Reynolds (1975)Reynolds (1975) reported that a maximum tensile bond strength ofreported that a maximum tensile bond strength of
5.9 to 7.9 Mpa5.9 to 7.9 Mpa would be a adequate to resist treatment forces butwould be a adequate to resist treatment forces but
added that, in vitro tensile strength levels ofadded that, in vitro tensile strength levels of 4.9 Mpa4.9 Mpa have provedhave proved
clinically acceptable.clinically acceptable.
 Keizer et al (1976)Keizer et al (1976) evaluated direct bonding adhesives forevaluated direct bonding adhesives for
orthodontic metal brackets. Their study showed large standardorthodontic metal brackets. Their study showed large standard
deviation of bond strength giving rise to speculation on reliability.deviation of bond strength giving rise to speculation on reliability.

 Zachrisson (1978)Zachrisson (1978) stated that the objective of bonding was to getstated that the objective of bonding was to get
as good as mechanical as possible between enamel and adhesiveas good as mechanical as possible between enamel and adhesive
and evenly distributed etching pattern with marked surfaceand evenly distributed etching pattern with marked surface
roughness, but little actual loss of enamel is most desirable toroughness, but little actual loss of enamel is most desirable to
achieve mechanical interlock.achieve mechanical interlock.
 Tavas et al (1979)Tavas et al (1979) introduced the concept ofintroduced the concept of light activatedlight activated
compositescomposites. They demonstrated that the bond strength of brackets. They demonstrated that the bond strength of brackets
bonded with this was comparable with two chemically curedbonded with this was comparable with two chemically cured
adhesivesadhesives..
Although important improvements in bonding haveAlthough important improvements in bonding have
been made in the last 30 years, the requirements of an idealbeen made in the last 30 years, the requirements of an ideal
bonding system are quite similar to those indicated by Buonocore.bonding system are quite similar to those indicated by Buonocore.
Apparently, the future has a sound background in the past.Apparently, the future has a sound background in the past.

DEVELOPMENT OF BONDING AGENTSDEVELOPMENT OF BONDING AGENTS

FIRST GENERATIONFIRST GENERATION
BUONOCOREBUONOCORE (1956)(1956) – Demondtsrated the use of a– Demondtsrated the use of a Glycerophosphoric acidGlycerophosphoric acid
dimethacrylatedimethacrylate – containing resin, would bond to acid etching dentine.– containing resin, would bond to acid etching dentine.
BOWENBOWEN (1965)(1965), tried, tried NN –– phenylglycine and glycidyl methacrylatephenylglycine and glycidyl methacrylate ..
Bonding occured due toBonding occured due to the interaction of this bifunctional resin with the calciumthe interaction of this bifunctional resin with the calcium
ions of hydroxyapatiteions of hydroxyapatite..
Drawback –Drawback – Poor bond strengthPoor bond strength (1 to 3 MPa ).(1 to 3 MPa ).
The first commercial system of this type –The first commercial system of this type – Cervident, SS WhiteCervident, SS White

SECOND GENERATIONSECOND GENERATION
 In the late 1970’s the second generation system were introduced.In the late 1970’s the second generation system were introduced.
 IncorporatedIncorporated halophosphorous estershalophosphorous esters of unfilled resins such asof unfilled resins such as
bisphenol – A glycidal methacrelate or bis – GMAbisphenol – A glycidal methacrelate or bis – GMA, or, or hydroxyethylhydroxyethyl
methacrylate, or HEMA.methacrylate, or HEMA.
 Bonded to dentine through anBonded to dentine through an ionic bondionic bond to calcium byto calcium by
chlorophosphate groups.chlorophosphate groups.
 Weak bond strengthWeak bond strength, but significant improvement over first, but significant improvement over first
generation.generation.
 Scotch BondScotch Bond (3M Dental ),(3M Dental ), ClearfilClearfil (Kuraray Co. Japan)(Kuraray Co. Japan)

THIRD GENERATIONTHIRD GENERATION
 The primer contains hydrophilic resin monomers which includeThe primer contains hydrophilic resin monomers which include hydroxyethylhydroxyethyl
trimellitate anhydride, or 4–META,trimellitate anhydride, or 4–META, andand biphenyl dimethacrylate or BPDM.biphenyl dimethacrylate or BPDM.
 The primers contain a hydrophilic group that infiltrates smear layer,The primers contain a hydrophilic group that infiltrates smear layer,
modifying it and promoting adhesion to dentin.modifying it and promoting adhesion to dentin.
 The phosphate primer modifies the smear layer by softening and cures,The phosphate primer modifies the smear layer by softening and cures,
forming a hard surface. Following, the unfilled resin adhesive is applied,forming a hard surface. Following, the unfilled resin adhesive is applied,
attaching cured primer to the composite resin.attaching cured primer to the composite resin.
 Drawback – Bonding to smear layer - covered dentine was not veryDrawback – Bonding to smear layer - covered dentine was not very
successful.successful.
 Mirage bondMirage bond,, Scotch bond 2Scotch bond 2,, Prisma Universal bond 2 and 3Prisma Universal bond 2 and 3..

FOURTH GENERATIONFOURTH GENERATION
 The use of the total etch technique is one of the main characteristicsThe use of the total etch technique is one of the main characteristics
of fourth generation bonding system,of fourth generation bonding system, here complete removal of thehere complete removal of the
smear layer is achieved.smear layer is achieved.
 The Total etch technique permits the etching of enamel and dentineThe Total etch technique permits the etching of enamel and dentine
simultaneously usingsimultaneously using 40% phosphoric acid for 15 to 20 seconds40% phosphoric acid for 15 to 20 seconds..
The surface must be left moist to avoid collagen collapse.The surface must be left moist to avoid collagen collapse.
 The application of hydrophilic primer solution can infiltrate collagenThe application of hydrophilic primer solution can infiltrate collagen
network forming the hybrid layer. According tonetwork forming the hybrid layer. According to Nakabayashi (1982)Nakabayashi (1982)
the hybrid layer is defined as “the hybrid layer is defined as “the structure formed in dental hardthe structure formed in dental hard
tissues by demineralization of the surface and subsurface, followedtissues by demineralization of the surface and subsurface, followed
by infiltration of monomer and subsequent polymerizationby infiltration of monomer and subsequent polymerization..
 All bound -2 (BISCO),All bound -2 (BISCO), Scotch bond Multipurpose (3M).Scotch bond Multipurpose (3M).

FIFTH GENERATIONFIFTH GENERATION
 Consist of two different types of adhesive materials the so calledConsist of two different types of adhesive materials the so called
““one bottleone bottle” systems and the” systems and the self etching primerself etching primer bonding system.bonding system.
 ONE BOTTLE SYSTEMSONE BOTTLE SYSTEMS combined the primer and adhesives intocombined the primer and adhesives into
one solution to be applied after etching. Total etching was done withone solution to be applied after etching. Total etching was done with
35 - 37% phosphoric acid for 15 to 20 secs.35 - 37% phosphoric acid for 15 to 20 secs.
 SELF ETCHING PRIMERSELF ETCHING PRIMER was developed bywas developed by WatanabeWatanabe andand
NakabayashiNakabayashi. It is a aqueous solution of. It is a aqueous solution of 20% phenyl – P in 30%20% phenyl – P in 30%
HEMA.HEMA.
 Adv – The combination of etching and priming steps reduce theAdv – The combination of etching and priming steps reduce the
working time.working time.
 Single bond (3M),Single bond (3M), One step (BISCO)One step (BISCO)

SIXTH GENERATIONSIXTH GENERATION
 Recently several bonding system were developed and theseRecently several bonding system were developed and these
systems are characterised by the possibility to achieve the propersystems are characterised by the possibility to achieve the proper
bond to enamel and dentine using only one solution. These shouldbond to enamel and dentine using only one solution. These should
really bereally be one - step bondingone - step bonding..
 Unfortunately, the first evaluations of these new system showed aUnfortunately, the first evaluations of these new system showed a
sufficient bond to a conditioned dentin while the bond with enamelsufficient bond to a conditioned dentin while the bond with enamel
was less effective.was less effective.
 This may be due to systems are composed of an acidic solutionThis may be due to systems are composed of an acidic solution
cannot be kept in place, must be refreshed continuously and have acannot be kept in place, must be refreshed continuously and have a
pK that is not enough to properly etch enamel.pK that is not enough to properly etch enamel.
 Prompt - L - Pop (ESPE, GermanyPrompt - L - Pop (ESPE, Germany).).

SEVENTH GENERATIONSEVENTH GENERATION
 The trend in the latest generation of dental bonding systemsThe trend in the latest generation of dental bonding systems ii
reduce the number of components and clinical placement steps.reduce the number of components and clinical placement steps.
The introduction ofThe introduction of i Bondi Bond, a single – bottle adhesive system, is the, a single – bottle adhesive system, is the
latest to new generation materials and combines etchant, adhesivelatest to new generation materials and combines etchant, adhesive
and desensitizer one component.and desensitizer one component.

CLASSIFICATION OF ORTHODONTICCLASSIFICATION OF ORTHODONTIC
ADHESIVE SYSTEMSADHESIVE SYSTEMS
 Based upon the polymerization initiation mechanism:Based upon the polymerization initiation mechanism:
 -- CHEMICALLY ACTIVATEDCHEMICALLY ACTIVATED
 - LIGHT CURED- LIGHT CURED
 - DUAL CURED- DUAL CURED
 - THERMOCURED- THERMOCURED

Chemically Activated orthodonticChemically Activated orthodontic
Adhesive systemsAdhesive systems
 Chemically activated orthodontic adhesives employChemically activated orthodontic adhesives employ benzoylbenzoyl
peroxide as an initiatorperoxide as an initiator, which is activated by a tereitiary aromatic, which is activated by a tereitiary aromatic
amine such asamine such as dimethyl – p- toludine or dihydroxyethyl – p toludinedimethyl – p- toludine or dihydroxyethyl – p toludine..
 Initiation occurs from mixing of the paste and liquid componentsInitiation occurs from mixing of the paste and liquid components
and free radicals are formed by a multi step process.and free radicals are formed by a multi step process.
TWO - PHASE (TWO - PHASE ( TWO PASTETWO PASTE) Adhesive Systems) Adhesive Systems
ONE - PHASE (ONE - PHASE (NO - MIXNO - MIX) Adhesive systems) Adhesive systems

TWO - PHASE (TWO - PHASE ( TWO PASTETWO PASTE) Adhesive Systems) Adhesive Systems
 Were the first to be tried by orthodontist in the early days ofWere the first to be tried by orthodontist in the early days of
bonding.bonding.
 Application involves mixing the paste and liquid components.Application involves mixing the paste and liquid components.
DisadvantagesDisadvantages
 Time consumingTime consuming
 Increased exposure to air induces oxygen inhibition.Increased exposure to air induces oxygen inhibition.
 Mixing introduces defects in the form of air entrapment andMixing introduces defects in the form of air entrapment and
formation of voids.formation of voids.
 Concise (3M).Concise (3M).

 Application of liquid component on enamel and bracket baseApplication of liquid component on enamel and bracket base
 No mixing required..No mixing required..
 Here homogenous polymerization pattern occur due to sandwichHere homogenous polymerization pattern occur due to sandwich
technique involved in diffusion of liquid component into paste duringtechnique involved in diffusion of liquid component into paste during
application.application.
 Enamel and bracket sides of adhesive are more polymerizedEnamel and bracket sides of adhesive are more polymerized
relative to middle zones.relative to middle zones.
 Efficient application, limited time requirements.Efficient application, limited time requirements.
 Succeeded two – phase systemsSucceeded two – phase systems
 Not recommended in applications where the adhesive thickness isNot recommended in applications where the adhesive thickness is
increased, as in molar tubes.increased, as in molar tubes.
 System 1(Ormco)System 1(Ormco)
 Rely - a – Bond( reliance)Rely - a – Bond( reliance)
 Unite (3M)Unite (3M)
ONE - PHASE (ONE - PHASE (NO - MIXNO - MIX) Adhesive systems) Adhesive systems

Visible Light curedVisible Light cured
 Polymerization initiation by exposure to light curing sourcePolymerization initiation by exposure to light curing source
 Permits increased working time for optimal bracket placement.Permits increased working time for optimal bracket placement.
 Photoactivation from the incisal and cervical edges is suggested.Photoactivation from the incisal and cervical edges is suggested.
 Degree of cure of stainless steel brackets bonded with light – curedDegree of cure of stainless steel brackets bonded with light – cured
adhesives is comparable to degree of cure of adhesive bonded to transparentadhesives is comparable to degree of cure of adhesive bonded to transparent
aesthetic brackets.aesthetic brackets.
 Bond strength has been studied extensively and supports their use.Bond strength has been studied extensively and supports their use.
 Available since the 1980s.Available since the 1980s.
 Good alternatives to two phase systems.Good alternatives to two phase systems.
 Significantly more time demanding than one phase systems.Significantly more time demanding than one phase systems.
 Most manufactures have marketed LC adhesives.Most manufactures have marketed LC adhesives.www.indiandentalacademy.comwww.indiandentalacademy.com

Dual – CuredDual – Cured
 Initiation is achieved by exposure to lightInitiation is achieved by exposure to light.. Reaction proceedsReaction proceeds
following a chemically – cured pattern.following a chemically – cured pattern.
 Combines disadvantages of handling of both light – cured andCombines disadvantages of handling of both light – cured and
chemically cured materials.chemically cured materials.
 The most time consuming applications.The most time consuming applications.
 Increased degree of cure and bond strength, but questionableIncreased degree of cure and bond strength, but questionable
clinical significance for their differences with light – cured materials.clinical significance for their differences with light – cured materials.
 Ideal candidates - bonding molar tubes.Ideal candidates - bonding molar tubes.

Self etching primerSelf etching primer
 An acidic primer combines the etchant with the primer in oneAn acidic primer combines the etchant with the primer in one
application, Contains bothapplication, Contains both acidacid (Phenyl – p)(Phenyl – p) and theand the primerprimer ( HEMA( HEMA
and dimethacrylate)and dimethacrylate)..
 Clearfil liner bond V (Kuraray)Clearfil liner bond V (Kuraray)
 Mega bond (Kuraray)Mega bond (Kuraray)
 Prompt – L – Pop ( 3M UniteK )Prompt – L – Pop ( 3M UniteK )
 First step (Reliance)First step (Reliance)
 Transbond Plus ( Unitek 3m )Transbond Plus ( Unitek 3m )
 Ideal 1 (GAC )Ideal 1 (GAC )
 One up Bond F ( Tokuyama)One up Bond F ( Tokuyama)

Bond strengthBond strength
 Adequate and acceptable bond strength.Adequate and acceptable bond strength.
 No statistical difference with conventional compositeNo statistical difference with conventional composite
resin adhesive system.resin adhesive system.
 Varies from 8 – 20 MPa.Varies from 8 – 20 MPa.
 A delay in bonding after SEP application furtherA delay in bonding after SEP application further
increases the bond strength.increases the bond strength.

 Enamel loss (Hosein et al AJO 2004)Enamel loss (Hosein et al AJO 2004)
 After pumicing and conventional etching, the enamel loss wasAfter pumicing and conventional etching, the enamel loss was 2.762.76µµmm
ranged fromranged from 1.11 – 4.571.11 – 4.57µµmm..
 With the SEPs, the median enamel loss was significantly lower, atWith the SEPs, the median enamel loss was significantly lower, at 0.270.27µµ
mm the range wasthe range was 0.03 to 0.740.03 to 0.74µµmm..
 Scanning microscopy revealed that self – etching primer producedScanning microscopy revealed that self – etching primer produced lessless
dissolutiondissolution of enamel surface compared with phosphoric acid.of enamel surface compared with phosphoric acid.

 Polished EnamelPolished Enamel
 Phosphoric etched enamelPhosphoric etched enamel
surface;surface; More dissolution &More dissolution &
finely roughened enamelfinely roughened enamel
surface.surface.
 Self etching primed surface;Self etching primed surface;
Less dissolution & enamelLess dissolution & enamel
surface almost flat & presencesurface almost flat & presence
of minute holesof minute holes

 Enamel loss at debonding time;Enamel loss at debonding time;
 At debonding time, more adhesive remains on the enamel surfaceAt debonding time, more adhesive remains on the enamel surface
after the use of conventional acid etching technique than after the useafter the use of conventional acid etching technique than after the use
of self etching primer.of self etching primer.
 Enamel cleaning with tungsten carbide bur, debonding pliers, or theEnamel cleaning with tungsten carbide bur, debonding pliers, or the
ultrasonic scaler, more enamel was removed in conventional acid –ultrasonic scaler, more enamel was removed in conventional acid –
etching group than in self etching primer group.etching group than in self etching primer group.

 Effect of contaminationEffect of contamination
 Saliva has no effect on bond strength of SEP.Saliva has no effect on bond strength of SEP.
 SEPs have maximum bond strength under dry and wet condition.SEPs have maximum bond strength under dry and wet condition.
 Conventional primer didn’t offer clinically adequate bond strength inConventional primer didn’t offer clinically adequate bond strength in
cases of moisture contamination.cases of moisture contamination.
 Both MIP and SEP primer showed adequate bond strength superiorBoth MIP and SEP primer showed adequate bond strength superior
to that of conventional primer in case of moisture contamination.to that of conventional primer in case of moisture contamination.

 Study on self etching primer and two – stage etch prime systemStudy on self etching primer and two – stage etch prime system
( Aljoubouri)( Aljoubouri)
Bonding timeBonding time – by self etching was significantly shorter than that for 2-– by self etching was significantly shorter than that for 2-
stage bonding system (mean differencestage bonding system (mean difference 24.924.9).).
Bond failureBond failure - was similar for each bonding system ( SEP waswas similar for each bonding system ( SEP was 0.8%0.8%
and 2 stageand 2 stage 1.1%1.1% ))

 DisadvantagesDisadvantages
 The solution must be refreshed continuously because its liquidThe solution must be refreshed continuously because its liquid
formulation cannot be controlled.formulation cannot be controlled.
 Residual smear layer may remain inbetween adhesive material andResidual smear layer may remain inbetween adhesive material and
dentine.dentine.
 Leakage test reveals that, the seal achieved at the enamel marginsLeakage test reveals that, the seal achieved at the enamel margins
with one – bottle systems is superior to that resulting from selfwith one – bottle systems is superior to that resulting from self
etching primer.etching primer.

Moisture insensitive primers (MIP)Moisture insensitive primers (MIP)
 MOISTURE - ACTIVEMOISTURE - ACTIVE
 MOISTURE – RESISTANTMOISTURE – RESISTANT
MOISTURE - ACTIVEMOISTURE - ACTIVE
 An aqueous solution of methacrylate functionalised polyalkenoicAn aqueous solution of methacrylate functionalised polyalkenoic
acid copolymer & hydroxyethyl – methacrylate.acid copolymer & hydroxyethyl – methacrylate.
 Generally available as a primer formulation.Generally available as a primer formulation.
 Requires the presence ofRequires the presence of waterwater for initiating the setting reactionfor initiating the setting reaction
and will therefore fail in dry environment.and will therefore fail in dry environment.
 Cynoacrylates (smart bond).Cynoacrylates (smart bond).

 Moisture – ResistantMoisture – Resistant
 Primer compatible with the use of adhesives.Primer compatible with the use of adhesives.
 Application of primer on wet enamel surface.Application of primer on wet enamel surface.
 Transbond MIP (3M).Transbond MIP (3M).
THERMOCUREDTHERMOCURED
Initiation occurs throughInitiation occurs through exposure to heat.exposure to heat.
Not intended for direct bonding.Not intended for direct bonding.
Polymerization initiator system restricts their use to indirect bonding.Polymerization initiator system restricts their use to indirect bonding.
Superior properties.Superior properties.

 The bonding of orthodontic attachments to the etched enamelThe bonding of orthodontic attachments to the etched enamel
surface of teeth is a well-established clinical procedure. There aresurface of teeth is a well-established clinical procedure. There are
at present two techniques for the placement of orthodonticat present two techniques for the placement of orthodontic
attachments.attachments.
 The first is called theThe first is called the direct techniquedirect technique in which the brackets arein which the brackets are
placed directly on the enamel surface by the operator, as wasplaced directly on the enamel surface by the operator, as was
initially described byinitially described by NewmanNewman.. The second method of bracketThe second method of bracket
placement is theplacement is the indirect techniqueindirect technique, which was first described by, which was first described by
Silverman et alSilverman et al..
 In an investigation, that examined the preference of 2000 operatorsIn an investigation, that examined the preference of 2000 operators
for either the direct or the indirect technique of bonding,for either the direct or the indirect technique of bonding, Gore lickGore lick
found that the ratio of direct to indirect as the preferred method wasfound that the ratio of direct to indirect as the preferred method was
13:113:1 ..
 In a clinical trial in which direct and indirect methods wereIn a clinical trial in which direct and indirect methods were
compared, failure rates ofcompared, failure rates of 2% for the direct method2% for the direct method andand 13% for the13% for the
indirect methodindirect method were reported.were reported.

 Apart from this difference in failure rates, the indirect techniqueApart from this difference in failure rates, the indirect technique
was inferior because of the increased time required for bracketwas inferior because of the increased time required for bracket
placement. In addition, there was excess adhesive around theplacement. In addition, there was excess adhesive around the
bracket bases, which was both difficult and time consuming tobracket bases, which was both difficult and time consuming to
remove.remove.
 BondingBonding of orthodontic attachment offers manyof orthodontic attachment offers many advantagesadvantages whenwhen
compared to conventional banding:compared to conventional banding:
 It is esthetically superior.It is esthetically superior.
 It is faster and simple.It is faster and simple.
 There is less discomfort for the patientThere is less discomfort for the patient
 Arch length is not increased by band materialArch length is not increased by band material..
 It allows more precise bracket placement.It allows more precise bracket placement.
 Bonds are more hygienic than bands.Bonds are more hygienic than bands.

 Partially erupted teeth can be controlled.Partially erupted teeth can be controlled.
 Mesiodistal enamel reduction ( proximal reduction) is possible duringMesiodistal enamel reduction ( proximal reduction) is possible during
treatment.treatment.
 Attachments may be bonded to artificial tooth surfaces (eg., amalgam,Attachments may be bonded to artificial tooth surfaces (eg., amalgam,
porcelain, gold) and to fixed bridge work.porcelain, gold) and to fixed bridge work.
 Interproximal areas are accessible for composite buildups.Interproximal areas are accessible for composite buildups.
 Caries risk under loose bands is eliminated.Caries risk under loose bands is eliminated.
 No band spaces are present to close at the end of treatment.No band spaces are present to close at the end of treatment.
 Brackets may be recycled, further reducing the cost.Brackets may be recycled, further reducing the cost.
 Lingual brackets, invisible braces, can be used when patient rejectsLingual brackets, invisible braces, can be used when patient rejects
visible orthodontic appliance.visible orthodontic appliance.

 Disadvantages of Bonding:Disadvantages of Bonding:
 A bonded bracket has a weaker attachment than a cementedA bonded bracket has a weaker attachment than a cemented
band.band.
 Some bonding adhesives are not sufficiently strong.Some bonding adhesives are not sufficiently strong.
 Better access for cleaning does not necessarily guarantee betterBetter access for cleaning does not necessarily guarantee better
oral hygiene and improved gingival condition, especially if excessoral hygiene and improved gingival condition, especially if excess
adhesive extend beyond the bracket baseadhesive extend beyond the bracket base..
 The protection against the inter proximal caries of well contouredThe protection against the inter proximal caries of well contoured
cemented band is absentcemented band is absent..

 Bonding is more complicated when lingual auxiliaries are requiredBonding is more complicated when lingual auxiliaries are required
or where headgears are attached.or where headgears are attached.
 Rebonding a loose bracket requires more preparation thanRebonding a loose bracket requires more preparation than
rebanding a loose band.rebanding a loose band.
 Rebonding is more time consuming than debanding, sinceRebonding is more time consuming than debanding, since
removal of adhesive is more difficult than removal of cement.removal of adhesive is more difficult than removal of cement.

 The steps involved areThe steps involved are
 CLEANINGCLEANING
 ENAMEL CONDITIONINGENAMEL CONDITIONING
 SEALINGSEALING
 BONDINGBONDING

CLEANINGCLEANING
 Cleaning of the teeth with pumice will remove plaque and the organicCleaning of the teeth with pumice will remove plaque and the organic
pellicle.pellicle.
 This requires rotary instruments, either a rubber cup or a polishing brush. AThis requires rotary instruments, either a rubber cup or a polishing brush. A
bristle brush cleans more effectively but care must be taken to avoidbristle brush cleans more effectively but care must be taken to avoid
traumatizing the gingival margin and initiating bleeding.traumatizing the gingival margin and initiating bleeding.
 Studies have shown enamel loss due to prophylaxisStudies have shown enamel loss due to prophylaxis.. Mark Daniel pusMark Daniel pus
et al ( AJO 1980)et al ( AJO 1980) showed that 10.7µm of enamel loss during initialshowed that 10.7µm of enamel loss during initial
prophylaxis with bristle brush was greater than the 5.0µm lost whenprophylaxis with bristle brush was greater than the 5.0µm lost when
a rubber cup as used and the difference was statistically significant.a rubber cup as used and the difference was statistically significant.
 Pumice or a prophylactic paste is often used to clean the enamel surface.Pumice or a prophylactic paste is often used to clean the enamel surface.
Either does not affect bond strengthEither does not affect bond strength..

ENAMEL CONDITIONINGENAMEL CONDITIONING
 MOISTURE CONTROLMOISTURE CONTROL::
 After the rinse, salivary control and maintenance of aAfter the rinse, salivary control and maintenance of a
completely dry working field is absolutely essential.completely dry working field is absolutely essential.
 Lip expanders and / or cheek retractorsLip expanders and / or cheek retractors
 Saliva ejectorsSaliva ejectors
 Tongue guard with bite blocksTongue guard with bite blocks
 Salivary duct obstructorsSalivary duct obstructors
 Gadgets that combine several of these (saliva ejector,Gadgets that combine several of these (saliva ejector,
tongue holder, and bite block).tongue holder, and bite block).
 Cotton or guaze rollsCotton or guaze rolls
 Antisialagogues.Antisialagogues. (Banthine)(Banthine)

ENAMEL PRETREATMENTENAMEL PRETREATMENT
 After the operative field has been isolated, the teeth to be bonded areAfter the operative field has been isolated, the teeth to be bonded are
dried.dried.
 The conditioning solution or gel (The conditioning solution or gel (usually 37% phosphoric acidusually 37% phosphoric acid ) is) is
then lightly applied over the enamel surface with a foam pellet orthen lightly applied over the enamel surface with a foam pellet or
brush for 15 to 60 sec.brush for 15 to 60 sec.
 When etching solutions are used, the surface must be kept moist byWhen etching solutions are used, the surface must be kept moist by
repeated applications. To avoid damaging delicate enamel rods, carerepeated applications. To avoid damaging delicate enamel rods, care
must be taken not to rub the liquid onto the teethmust be taken not to rub the liquid onto the teeth..
 At the end of the etching period the etchant is rinsed off the teeth withAt the end of the etching period the etchant is rinsed off the teeth with
abundant water spray.abundant water spray.
 Salivary contamination of the etched surface must not be allowed. ( IfSalivary contamination of the etched surface must not be allowed. ( If
it occurs rinse with water spray or re - etch for a few seconds; theit occurs rinse with water spray or re - etch for a few seconds; the
patient must not rinse.)patient must not rinse.) www.indiandentalacademy.comwww.indiandentalacademy.com

 Next, teeth are thoroughly dried with moisture and oil- free air sourceNext, teeth are thoroughly dried with moisture and oil- free air source
to obtain the dull frosty appearance.to obtain the dull frosty appearance.
 Teeth that do not appear dull andTeeth that do not appear dull and frosty white should befrosty white should be re- etched.re- etched.
 The effect of acid etching is to remove a small amount of the softerThe effect of acid etching is to remove a small amount of the softer
interprismatic enamel and open up pores between the enamelinterprismatic enamel and open up pores between the enamel
prisms, so the adhesive can penetrate into enamel surface.prisms, so the adhesive can penetrate into enamel surface.

 Should the etch cover the entire facial enamel or only a smallShould the etch cover the entire facial enamel or only a small
portion outside the bracket pad?portion outside the bracket pad?
Clinical experience indicates that etching the entire facialClinical experience indicates that etching the entire facial
enamel with solution is harmless at least when a fluoride mouth rinseenamel with solution is harmless at least when a fluoride mouth rinse
is used regularly.is used regularly.
 Are gels preferable to solution ?Are gels preferable to solution ?
Brannstrom et al (1982)Brannstrom et al (1982) They found one minute etching withThey found one minute etching with
an acid gel had the same effect as etching with an acid liquid for thean acid gel had the same effect as etching with an acid liquid for the
same time. Gels provide better control for restricting the etched areasame time. Gels provide better control for restricting the etched area
but may require more thorough rinsing afterward.but may require more thorough rinsing afterward.

 What is the optimal etching time?What is the optimal etching time?
 No differences in bond strength are detected between 15No differences in bond strength are detected between 15
second and 60 second etching with 37% phosphoric acid; however,second and 60 second etching with 37% phosphoric acid; however,
shorter etching times cause less enamel damage on debonding.shorter etching times cause less enamel damage on debonding.
 Acording to William A. BrantleyAcording to William A. Brantley decreasing etching time between 30decreasing etching time between 30
and 10 seconds does not affect bond strength, whereas etching for 0and 10 seconds does not affect bond strength, whereas etching for 0
or 5seconds reduces bond strength ( less than 3 MPa ) significantly.or 5seconds reduces bond strength ( less than 3 MPa ) significantly.
 Scanning electron microscopy shows that etching with 37%Scanning electron microscopy shows that etching with 37%
phosphoric acid for at least 30 seconds produces more opticalphosphoric acid for at least 30 seconds produces more optical
etching patterns than etching for 15 seconds.etching patterns than etching for 15 seconds.

 Wei Nan Wang et al (1991)Wei Nan Wang et al (1991) study on tensile strengths of anstudy on tensile strengths of an
orthodontic resin cement were compared for 15, 30, 60, 90,120orthodontic resin cement were compared for 15, 30, 60, 90,120
seconds etching times, with 37% phosphoric acid solution on theseconds etching times, with 37% phosphoric acid solution on the
enamel surface of young permanent teeth .enamel surface of young permanent teeth .
 The results of tensile bond strength for 15, 30,60,90The results of tensile bond strength for 15, 30,60,90
seconds etching times were not statistically different . Resultsseconds etching times were not statistically different . Results
showed that to achieve good retention, to decrease enamel loss, andshowed that to achieve good retention, to decrease enamel loss, and
to reduce moisture contamination in the clinic as well as to saveto reduce moisture contamination in the clinic as well as to save
chair side time a 15-seconds etching time was suggested.chair side time a 15-seconds etching time was suggested.

 Is etching time is different for young and old teeth?Is etching time is different for young and old teeth?
 K J. Nordenvall et al (AJO 1980)K J. Nordenvall et al (AJO 1980) did a comparison between thedid a comparison between the
effects of 15 and 60 seconds of etching with a 37 percent phosphoriceffects of 15 and 60 seconds of etching with a 37 percent phosphoric
acid solution on enamel surfaces of deciduous and young and oldacid solution on enamel surfaces of deciduous and young and old
permanent teeth.permanent teeth.
 For deciduous teethFor deciduous teeth, no difference was found in effect between the, no difference was found in effect between the
etching periods.etching periods.
 For young permanent teethFor young permanent teeth, 15 seconds of etching created more, 15 seconds of etching created more
retentive conditions than 60 seconds.retentive conditions than 60 seconds.
 For old permanent teethFor old permanent teeth, the reverse was found. The most retentive, the reverse was found. The most retentive
conditions were found for the deciduous teeth, regardless of etchingconditions were found for the deciduous teeth, regardless of etching
time.time.

 Concentration of AcidConcentration of Acid ??
 Etching with 10% or 37% phosphoric acid produces the highest bondEtching with 10% or 37% phosphoric acid produces the highest bond
strengths (28 MPa ) to enamel. No differences in bond strengths arestrengths (28 MPa ) to enamel. No differences in bond strengths are
observed when enamel is etched with phosphoric acid ranging inobserved when enamel is etched with phosphoric acid ranging in
concentration from 2% to 37%. One study reported that 2%concentration from 2% to 37%. One study reported that 2%
phosphoric acid etchant was adequate for bonding, whereas anotherphosphoric acid etchant was adequate for bonding, whereas another
recommended 10 – 30% phosphoric acid.recommended 10 – 30% phosphoric acid.
 Wolfgang Carstensen (AJO 1995)Wolfgang Carstensen (AJO 1995).. Compared three acidCompared three acid
concentration (37%, 2% and 5%) was used for 30 seconds to bondconcentration (37%, 2% and 5%) was used for 30 seconds to bond
the brackets. The results showed that 37% phosphoric acid had athe brackets. The results showed that 37% phosphoric acid had a
higher bond strength.higher bond strength.
The amount of adhesive left on the teeth after debondingThe amount of adhesive left on the teeth after debonding
was smaller for 2% acid than 37% and 5%, and it was concluded thatwas smaller for 2% acid than 37% and 5%, and it was concluded that
2% phosphoric acid solution is appropriate for bonding of brackets2% phosphoric acid solution is appropriate for bonding of brackets
and the reduced etching could be favorable in preventing enameland the reduced etching could be favorable in preventing enamel
damage during the treatment and at the time of debonding.damage during the treatment and at the time of debonding.

 Wasundhara(AJO)Wasundhara(AJO) made an invitro study to detect the etch patternmade an invitro study to detect the etch pattern
and compare the shear bond strength by using 37% and 5%and compare the shear bond strength by using 37% and 5%
phosphoric acid and it was observed that there was no significantphosphoric acid and it was observed that there was no significant
difference in shear bond strength, but 5% phosphoric acid produceddifference in shear bond strength, but 5% phosphoric acid produced
a minimal enamel loss.a minimal enamel loss.
 What is preferred procedure for deciduous teeth?What is preferred procedure for deciduous teeth?
 Acording toAcording to ZachrissonZachrisson recommended procedure for conditioningrecommended procedure for conditioning
deciduous teeth is to sand blast with 50 μm aluminum oxide for 3deciduous teeth is to sand blast with 50 μm aluminum oxide for 3
seconds to remove some outermost aprismatic enamel and thenseconds to remove some outermost aprismatic enamel and then
etch for 30 seconds with Ultra-Etch 35% phosphoric acid gel.etch for 30 seconds with Ultra-Etch 35% phosphoric acid gel.

 Is prolonged etching necessary when teeth are pretreated withIs prolonged etching necessary when teeth are pretreated with
fluoride?fluoride?
M. Brannstrom et al(1982 AJO)M. Brannstrom et al(1982 AJO) suggested that extra etchingsuggested that extra etching
time is not necessary when teeth have been pretreated with fluoride.time is not necessary when teeth have been pretreated with fluoride.
When in doubt, check that the enamel looks uniformly dull and frostyWhen in doubt, check that the enamel looks uniformly dull and frosty
white after etch. If it does, surface retention is adequate for bonding.white after etch. If it does, surface retention is adequate for bonding.
Will incorporation of fluorides in the etching solution will decrease theWill incorporation of fluorides in the etching solution will decrease the
bond strength?bond strength?
Fluoridated phosphoric acid solutions and gels provide anFluoridated phosphoric acid solutions and gels provide an
etching effect similar to nonflouridated ones and give adequate bondetching effect similar to nonflouridated ones and give adequate bond
strength in direct bonding procedures.strength in direct bonding procedures.

 F.Garcia etal (AJO 1991)F.Garcia etal (AJO 1991) compared the enamel morphology andcompared the enamel morphology and
shear bond strength of orthodontic bonded to enamel etched withshear bond strength of orthodontic bonded to enamel etched with
fluoridated or a non fluoridated phosphoric acid gel. The resultfluoridated or a non fluoridated phosphoric acid gel. The result
showed that overall morphologic etching effect was similar in bothshowed that overall morphologic etching effect was similar in both
groups.groups.
 J .B Thornton etalJ .B Thornton etal found thatfound that addition of fluoride to the phosphoricaddition of fluoride to the phosphoric
acid solution reduce the decalcification adjacent to bonded brackets.acid solution reduce the decalcification adjacent to bonded brackets.

 Is etching permissible on teeth with internal white spots?Is etching permissible on teeth with internal white spots?
 Caution should be exercised when etching over acquired andCaution should be exercised when etching over acquired and
developmental demineralizations. It is best to avoid it. If this isdevelopmental demineralizations. It is best to avoid it. If this is
impossible, a short etching time, the application of sealent, and theimpossible, a short etching time, the application of sealent, and the
use of direct bonding with extra attention to not having areas ofuse of direct bonding with extra attention to not having areas of
adhesive deficiency are important.adhesive deficiency are important.
 The presence of voids, together with poor hygiene, can lead toThe presence of voids, together with poor hygiene, can lead to
metal corrosion and staining of underlying developmental whitemetal corrosion and staining of underlying developmental white
spots.spots.

 How much enamel is removed by etching and how deep are theHow much enamel is removed by etching and how deep are the
histological alterations?histological alterations?
Are they reversible? Is etching is harmful?Are they reversible? Is etching is harmful?
A routine etching removes 3 to 10 μm of surfaceA routine etching removes 3 to 10 μm of surface
enamel.enamel.
Mark Daniel et al (AJO 1980)Mark Daniel et al (AJO 1980) found that a 90 second etchfound that a 90 second etch
with phosphoric acid resulted in mean loss of 6.9µm with nowith phosphoric acid resulted in mean loss of 6.9µm with no
significant difference between liquid and gel.significant difference between liquid and gel.
Deeper localized dissolutions will generally causeDeeper localized dissolutions will generally cause
penetration to a depth of about 100µm or more.penetration to a depth of about 100µm or more.
..

 Although laboratory studies indicate that the enamel alterations areAlthough laboratory studies indicate that the enamel alterations are
largely reversible ( though not completely ) it can be stated that thelargely reversible ( though not completely ) it can be stated that the
overall effect of applying etchant to healthy enamel is notoverall effect of applying etchant to healthy enamel is not
detrimental.detrimental.
 This is augmented by the fact that normally enamel is 1000This is augmented by the fact that normally enamel is 1000
to 2000 µm thick, abrasive wear of facial enamel is normal andto 2000 µm thick, abrasive wear of facial enamel is normal and
proceeds at a rate of up to 2 µm per year on facial surface are selfproceeds at a rate of up to 2 µm per year on facial surface are self
cleaning and not prone to caries.cleaning and not prone to caries.

Possible iatrogenic effects of acid etching ofPossible iatrogenic effects of acid etching of
enamelenamel
 Fracture and cracking of enamel upon debondingFracture and cracking of enamel upon debonding
 Increased surface porosity – possible staining.Increased surface porosity – possible staining.
 Loss of acquired fluoride in outer 10Loss of acquired fluoride in outer 10µµm of enamelm of enamel
surface.surface.
 Loss of enamel during etching.Loss of enamel during etching.
 Resin tags retained in enamel – possibleResin tags retained in enamel – possible
discoloration of resin.discoloration of resin.
 Rougher surface if over-etched.Rougher surface if over-etched.

Should other means than acid etching beShould other means than acid etching be
preferred?preferred?
 AIR ABRASIONAIR ABRASION
 Air Abrasion, also referred to asAir Abrasion, also referred to as micro-etchingmicro-etching, is a technique in, is a technique in
which particles ofwhich particles of aluminum oxidealuminum oxide are propelled against theare propelled against the
surface of enamel by high air pressure, causing abrasion of thesurface of enamel by high air pressure, causing abrasion of the
surface.surface.
 Some manufactures of commercial units have suggested that airSome manufactures of commercial units have suggested that air
abrasion could eliminate acid etching; however, bond strengths toabrasion could eliminate acid etching; however, bond strengths to
air-abraded enamel are only aboutair-abraded enamel are only about 50%50% of those to acid-etchedof those to acid-etched
enamel.enamel.
 Air abrasion of metal brackets or bands is an effective techniqueAir abrasion of metal brackets or bands is an effective technique
for improving bond strength.for improving bond strength.
 It could be an alternative to pumicing the teeth before etching.It could be an alternative to pumicing the teeth before etching.www.indiandentalacademy.comwww.indiandentalacademy.com

 Karenet al (AJO 1997Karenet al (AJO 1997)) compared the use of acompared the use of a
sandblasting and current techniques. Four methods ofsandblasting and current techniques. Four methods of
enamel preparation before orthodontic bonding that areenamel preparation before orthodontic bonding that are
currently in use were investigated.currently in use were investigated.
 Group A – Only sand blastingGroup A – Only sand blasting
 Group B – Sand blasted and etchedGroup B – Sand blasted and etched
 Group C – Surfaces buffed with bur and acid etchedGroup C – Surfaces buffed with bur and acid etched
 Group D – pumiced and etched.Group D – pumiced and etched.
 Result showed no statistical difference in surfaceResult showed no statistical difference in surface
roughness and no difference in bond strength.roughness and no difference in bond strength.

CRYSTAL-GROWING SOLUTIONSCRYSTAL-GROWING SOLUTIONS
 Crystal bonding involves application to enamel of aCrystal bonding involves application to enamel of a poly (acrylic acid)poly (acrylic acid)
solutionsolution containing sulfate ions, which causes growth of calcium sulfatecontaining sulfate ions, which causes growth of calcium sulfate
dihydrate crystals on the enamel surface. These crystals in turn retain thedihydrate crystals on the enamel surface. These crystals in turn retain the
adhesive.adhesive.
 Potential advantages of crystal bonding include easier debonding, lessPotential advantages of crystal bonding include easier debonding, less
residual adhesive left on the tooth and less damage to enamel.residual adhesive left on the tooth and less damage to enamel.
 Since crystal bonding produces bond strengths ofSince crystal bonding produces bond strengths of 60 – 80%60 – 80% of the bondof the bond
strength obtained with acid etching, it is not yet considered a practicalstrength obtained with acid etching, it is not yet considered a practical
technique.technique.
 Maijer R, Smith Dc ( J Biomed Mater 1979):Maijer R, Smith Dc ( J Biomed Mater 1979): Found that crystal growingFound that crystal growing
solutions provided retention similar to those after etching with phosphoricsolutions provided retention similar to those after etching with phosphoric
acid with less risk of enamel damage at debonding.acid with less risk of enamel damage at debonding.

LASER ETCHINGLASER ETCHING
 The application of laser energy to an enamel surface causes localized meltingThe application of laser energy to an enamel surface causes localized melting
and ablation.and ablation.
 MECHANISMMECHANISM
- Removal of enamel (etching) results primarily from the micro-explosion- Removal of enamel (etching) results primarily from the micro-explosion
of entrapped water in the enamel.of entrapped water in the enamel.
- In addition, there may be some melting of the hydroxyapatite crystals.- In addition, there may be some melting of the hydroxyapatite crystals.
Laser etching of enamel by aLaser etching of enamel by a neodymium-yttrium-aluminumneodymium-yttrium-aluminum garnetgarnet
(Nd:YAG) laser typically produced lower bond strengths than does acid(Nd:YAG) laser typically produced lower bond strengths than does acid
etching.etching.
Satisfactory in vitro bond strengths were obtained in one study only when theSatisfactory in vitro bond strengths were obtained in one study only when the
Nd: YAG laser was used for 12 seconds at maximum power (3 W).Nd: YAG laser was used for 12 seconds at maximum power (3 W).
Studies ofStudies of CO2 laser (pulsed mode)CO2 laser (pulsed mode) etching of enamel have shown thatetching of enamel have shown that
bond strengths of 10 Mpa can be obtained reliably.bond strengths of 10 Mpa can be obtained reliably.
The thermal effects of laser etching on the enamel substructure requireThe thermal effects of laser etching on the enamel substructure require
further research.further research. www.indiandentalacademy.comwww.indiandentalacademy.com

BLEACHINGBLEACHING
 Teeth recently bleached have been observed to have significantlyTeeth recently bleached have been observed to have significantly
lower bond strengths to resin composites. The bleach produceslower bond strengths to resin composites. The bleach produces
oxygen, which inhibits free radical polymerization of resin composites.oxygen, which inhibits free radical polymerization of resin composites.
 Research has shown that orthodontic brackets can be placed afterResearch has shown that orthodontic brackets can be placed after
use ofuse of carbamide peroxidecarbamide peroxide bleaching with no adverse effect on bondbleaching with no adverse effect on bond
strength.strength.

SEALINGSEALING
 After the teeth are completely dry and frosty white, a thin layer ofAfter the teeth are completely dry and frosty white, a thin layer of
sealant may be painted over the entire etched enamel surface.sealant may be painted over the entire etched enamel surface.
 Sealent is best applied with a small foam pellet or brush with aSealent is best applied with a small foam pellet or brush with a
single gingivoincisal stroke on each tooth.single gingivoincisal stroke on each tooth.
 The sealant coating should be thin and even, because excessThe sealant coating should be thin and even, because excess
sealant may induce bracket drift and unnatural enamel topographysealant may induce bracket drift and unnatural enamel topography
when polymerized.when polymerized.
 Bracket placement should be started immediately after all etchedBracket placement should be started immediately after all etched
surfaces are coated with sealant.surfaces are coated with sealant.

 Research has been devoted in the acid etch procedure. The findingsResearch has been devoted in the acid etch procedure. The findings
are divergent.are divergent.
 Some investigators conclude that an intermediate resin isSome investigators conclude that an intermediate resin is
necessary to achieve proper bond strength.necessary to achieve proper bond strength.
 Some indicate that it is necessary to improve resistance toSome indicate that it is necessary to improve resistance to
micro leakage.micro leakage.
 Others feel it is necessary for both reasons.Others feel it is necessary for both reasons.
 Still others do not think that the intermediate resin is necessary atStill others do not think that the intermediate resin is necessary at
all.all.

 Wang and Tang (AJO 1991)Wang and Tang (AJO 1991) studiedstudied bond strengths with andbond strengths with and
without sealants in orthodontic bonding.without sealants in orthodontic bonding.
The results indicated no statistical differencesThe results indicated no statistical differences
between the tensile bond strengths of the two evaluated groups .between the tensile bond strengths of the two evaluated groups .
This study therefore indicated that, use of the sealant in theThis study therefore indicated that, use of the sealant in the
two – paste orthodontic bonding system for enhanced strengthtwo – paste orthodontic bonding system for enhanced strength
is unnecessary . However, the use of a sealant offer extrais unnecessary . However, the use of a sealant offer extra
protection to the enamel during debonding procedures.protection to the enamel during debonding procedures.

 BONDINGBONDING
 Immediately after all teeth to be bonded have been painted withImmediately after all teeth to be bonded have been painted with
sealant, the operator should proceed with the actual bonding of thesealant, the operator should proceed with the actual bonding of the
attachments.attachments.
 The recommended bracket bonding procedure consist of the followingThe recommended bracket bonding procedure consist of the following
stepssteps
 1.TRANSFER1.TRANSFER
 2.POSITIONING2.POSITIONING
 3.FITTING3.FITTING
 4.REMOVAL OF EXCESS4.REMOVAL OF EXCESS

 TRANSFER:TRANSFER:
 The bracket is gripped with a pair of cotton pliers or a reverse action plierThe bracket is gripped with a pair of cotton pliers or a reverse action plier
(bracket holding forceps) and the mixed adhesive is applied to the back of the(bracket holding forceps) and the mixed adhesive is applied to the back of the
bonding base.bonding base.
 The bracket is immediately placed on the tooth close to its correct position.The bracket is immediately placed on the tooth close to its correct position.
 POSITIONING:POSITIONING:
 A placement scaler, such as the RM 349 or one with parallel edges is used toA placement scaler, such as the RM 349 or one with parallel edges is used to
position the brackets mesiodistally and incisogingivilly and angulate themposition the brackets mesiodistally and incisogingivilly and angulate them
accurately.accurately.
 The placement scaler with parallel edges allows visualization of the bracketThe placement scaler with parallel edges allows visualization of the bracket
slot relative to the incisal edge and long axis of the teeth, with the scalerslot relative to the incisal edge and long axis of the teeth, with the scaler
seated in slot.seated in slot.
 Proper vertical positioning may enhanced by different measuring devices orProper vertical positioning may enhanced by different measuring devices or
height guides on the brackets themselves. A mouth mirror will aid inheight guides on the brackets themselves. A mouth mirror will aid in
horizontal positioning, particularly on rotated premolars.horizontal positioning, particularly on rotated premolars.

 FITTINGFITTING
 The scaler is turned and with one – point contact with the bracket it isThe scaler is turned and with one – point contact with the bracket it is
pushed firmly toward the tooth surface. The tight fit will result in good bondpushed firmly toward the tooth surface. The tight fit will result in good bond
strength, little material to remove on debonding and reduced slide whenstrength, little material to remove on debonding and reduced slide when
excess material extrudes peripherally.excess material extrudes peripherally.
 It is important that the scaler be removed once the bracket is in correctIt is important that the scaler be removed once the bracket is in correct
position and no attempts should be made to hold the bracket in place withposition and no attempts should be made to hold the bracket in place with
instrument. Even slight movement may disturb the setting of the adhesive.instrument. Even slight movement may disturb the setting of the adhesive.
 REMOVAL OF EXCESSREMOVAL OF EXCESS
A slight bit of excess adhesive is essential to minimize the possibilityA slight bit of excess adhesive is essential to minimize the possibility
of voids.of voids.
 Excess must be removed with the scaler before the adhesive has set or itExcess must be removed with the scaler before the adhesive has set or it
must be removed with bur after setting.must be removed with bur after setting.
 To avoid disturbing the bracket position during setting, remove the excessTo avoid disturbing the bracket position during setting, remove the excess
after the adhesive has set, for this purpose careful use of tapered tungstenafter the adhesive has set, for this purpose careful use of tapered tungsten
carbide bur.carbide bur.

Orthodontic light curing sourcesOrthodontic light curing sources
 Halogen light curing unitsHalogen light curing units
 Plasma Arc curing unitsPlasma Arc curing units
 LED (light emitting diodes) curing unitsLED (light emitting diodes) curing units

Halogen light curing unitsHalogen light curing units
 DrawbacksDrawbacks
 Halogen bulbs have a limitedHalogen bulbs have a limited
effective lifetime of approximatelyeffective lifetime of approximately
40 – 100 hrs.40 – 100 hrs.
 High temperatures cause a gradualHigh temperatures cause a gradual
degradation of the halogen bulb,degradation of the halogen bulb,
reflector and filter, reducing thereflector and filter, reducing the
intensity of the light output & thusintensity of the light output & thus
the units effectiveness is reduced.the units effectiveness is reduced.
 Clinical implicationClinical implication
 With an aging light – curing unit,With an aging light – curing unit,
adhesives will be less well curedadhesives will be less well cured
and risk of bond failure.and risk of bond failure.
 Replace the filter & halogen bulb onReplace the filter & halogen bulb on
a regular basis.a regular basis.

Plasma Arc curing unitsPlasma Arc curing units
AdavantagesAdavantages
 Overall time reduction – 2 minOverall time reduction – 2 min
for whole arch.for whole arch.
 Immediate bond strengthImmediate bond strength
appears to be very high.appears to be very high.
 No enamel damage onNo enamel damage on
debonding.debonding.
 Rebonding bracket- easy.Rebonding bracket- easy.
DisadvantagesDisadvantages
 Light emitted from plasma arcLight emitted from plasma arc
device is so powerful that bothdevice is so powerful that both
the operator & assistant shouldthe operator & assistant should
wear protective glasses.wear protective glasses.
 Additional cost of curing light.Additional cost of curing light.

LED (Light emitting diodes)LED (Light emitting diodes)
 Are semiconducting materials thatAre semiconducting materials that
transform current into light of atransform current into light of a
specific wavelength.specific wavelength.
 First suggested byFirst suggested by
Mills (Br. Dent J 1995)Mills (Br. Dent J 1995)
First report byFirst report by
Fujibayashi et al (Dent. JapFujibayashi et al (Dent. Jap
1998)1998)

ADVANTAGESADVANTAGES
 Much smaller & lighter than conventional bulbs.Much smaller & lighter than conventional bulbs.
 Offer high shock resistance, as there is no filament to be damaged andOffer high shock resistance, as there is no filament to be damaged and
their relatively low power consumption makes them suitable fortheir relatively low power consumption makes them suitable for
portable use in cordless devices.portable use in cordless devices.
 LEDs have lifetimes of more thanLEDs have lifetimes of more than 10,000 hours10,000 hours and experienceand experience
little degradation of light output over this time –little degradation of light output over this time – a distincta distinct
advantage over halogen bulbs.advantage over halogen bulbs.
 Require no filters to produce blue light. The spectral output of theseRequire no filters to produce blue light. The spectral output of these
LEDs falls mainly within the absorption spectrum of theLEDs falls mainly within the absorption spectrum of the
camphoroquinone photoinitiatior of most dental composites.camphoroquinone photoinitiatior of most dental composites.
 Depth of cure – significantly greater than halogen lightDepth of cure – significantly greater than halogen light

 Lay Man et al 2004Lay Man et al 2004
Bracket failure rateBracket failure rate
 Halogen light –Halogen light – 4.8%4.8%
 LED unit –LED unit – 1.9%1.9%
 More the number of LEDs significantly higher shear bond strength.More the number of LEDs significantly higher shear bond strength.
 Generally Shear bond strength greater than 8 MPa, even with 10Generally Shear bond strength greater than 8 MPa, even with 10
second cure.second cure.
 Effects on PulpEffects on Pulp
 Halogen lights were found to produce a greater pulpal temp rise –Halogen lights were found to produce a greater pulpal temp rise –
with longer curing cycles increasing iatrogenic pulpal damage risk.with longer curing cycles increasing iatrogenic pulpal damage risk.
 LEDs, lesser pulpal wall heating & had shorter cooling times – mayLEDs, lesser pulpal wall heating & had shorter cooling times – may
be related to their narrow energy spectrum.be related to their narrow energy spectrum.

In Indirect bonding, brackets are attached to the teeth on the patients models,In Indirect bonding, brackets are attached to the teeth on the patients models,
transferred to the mouth with some sort of tray on to which the bracketstransferred to the mouth with some sort of tray on to which the brackets
become incorporated, and then bonded simultaneously.become incorporated, and then bonded simultaneously.
 Several techniques for indirect bonding are available. Most are based on theSeveral techniques for indirect bonding are available. Most are based on the
procedures described byprocedures described by Silverman and Cohen ( JCO 1976)Silverman and Cohen ( JCO 1976)..
 H. Stuart ( Jco 2003 )H. Stuart ( Jco 2003 ) suggested most indirect bonding techniques aresuggested most indirect bonding techniques are
successful in accurately placing brackets but can be expensive, complexsuccessful in accurately placing brackets but can be expensive, complex
and time – consuming. So he introduced a simplified method that hasand time – consuming. So he introduced a simplified method that has
reduced lab cost and chair time.reduced lab cost and chair time.

 Mark the long axis of eachMark the long axis of each
tooth to be bonded with atooth to be bonded with a
sharp pencil, beginning at thesharp pencil, beginning at the
midpoint of the incisal crownmidpoint of the incisal crown
and extending to the gingivaland extending to the gingival
margin.margin.
 Paint the casts with a liquid foilPaint the casts with a liquid foil
separating medium.separating medium. www.indiandentalacademy.comwww.indiandentalacademy.com

 Paint a thin layer of unfilled light –Paint a thin layer of unfilled light –
cured resin on each bracket padcured resin on each bracket pad
followed by a thin layer of microfilledfollowed by a thin layer of microfilled
resin paste. Place each bracket in itsresin paste. Place each bracket in its
correct position and press thecorrect position and press the
bracket firmly against the toothbracket firmly against the tooth
surface and remove any excess.surface and remove any excess.
 The adhesive is cured.The adhesive is cured.

Inject polyvinyl siloxaneInject polyvinyl siloxane
impression material over theimpression material over the
brackets, occlusal andbrackets, occlusal and
lingual tooth surfaces.lingual tooth surfaces.
Sculpt the material to aSculpt the material to a
smooth contour with finger.smooth contour with finger.
 The transfer tray trimmedThe transfer tray trimmed
with scissor after removalwith scissor after removal
from the cast.from the cast.

Etch and prepare the entire dentition asEtch and prepare the entire dentition as
usual. Dry and apply a layer ofusual. Dry and apply a layer of
Orthosolo.Orthosolo.
 Wipe the composite pad surfacesWipe the composite pad surfaces
in the transfer tray with absolutein the transfer tray with absolute
alcohol to ensure that noalcohol to ensure that no
separating medium remain. A thinseparating medium remain. A thin
layer of Orthosolo is then applied.,layer of Orthosolo is then applied.,
 Followed by a very thin layer ofFollowed by a very thin layer of
Enlight LV (microfilled resin) isEnlight LV (microfilled resin) is
applied. The Orthosolo brushapplied. The Orthosolo brush
should be reused to spread theshould be reused to spread the
adhesive paste thinly over theadhesive paste thinly over the
entire surface of each bracket padentire surface of each bracket pad
and thus prevent voids duringand thus prevent voids during
seating or polymerization.seating or polymerization.

 Seat the indirect transferr traySeat the indirect transferr tray
firmly over the prepared teeth..firmly over the prepared teeth..
Bracket bonded with 10 –Bracket bonded with 10 –
second exposure fromsecond exposure from
occlusal.occlusal.
 The transfer tray removedThe transfer tray removed
immediately after each sectionimmediately after each section
is bonded.is bonded.
 Remove any excess flash ifRemove any excess flash if
there.there.

 According toAccording to Hickham and Rossouw (Jco 1993)Hickham and Rossouw (Jco 1993)
An indirect bonding system must satisfy the followingAn indirect bonding system must satisfy the following
criteria to be successful:criteria to be successful:
 Positions brackets accurately on all teeth.Positions brackets accurately on all teeth.
 Ensures adequate bracket adherence by avoidingEnsures adequate bracket adherence by avoiding
moisture contaminationmoisture contamination

 Reduces patient discomfort and duration of the bondingReduces patient discomfort and duration of the bonding
procedure.procedure.
 Reduces laboratory expense and doctor chair time.Reduces laboratory expense and doctor chair time.
 Ensures sufficient integrity of transfer trays to holdEnsures sufficient integrity of transfer trays to hold
brackets securely in place while the adhesivebrackets securely in place while the adhesive
polymerizes.polymerizes.
 Reduces stress for the clinical staff.Reduces stress for the clinical staff.

 The scope of orthodontics has expanded over the past two decades toThe scope of orthodontics has expanded over the past two decades to
include more adult patients, and it is expected that many of theseinclude more adult patients, and it is expected that many of these
people will have restorations placed on their teeth. Although bandingpeople will have restorations placed on their teeth. Although banding
is always an alternative for the teeth that have restorations, bonding isis always an alternative for the teeth that have restorations, bonding is
desirable in aesthetic areas.desirable in aesthetic areas.
 BONDING TO CERAMICSBONDING TO CERAMICS
 Acid etchingAcid etching with phosphoric acid iswith phosphoric acid is ineffectiveineffective..
 Alternative surface preparation techniques have been found toAlternative surface preparation techniques have been found to
satisfactory results which includes;satisfactory results which includes;
- Mechanical roughening with stones and diamonds- Mechanical roughening with stones and diamonds
- Sandblasting- Sandblasting
- Chemical roughening with hydrofluoric acid- Chemical roughening with hydrofluoric acid
- Combination of sand blasting and chemical roughening with- Combination of sand blasting and chemical roughening with
hydrofluoric acid and chemical coupling with the use of silaneshydrofluoric acid and chemical coupling with the use of silanes..www.indiandentalacademy.comwww.indiandentalacademy.com

 Roughening the porcelain surface with diamonds or stonesRoughening the porcelain surface with diamonds or stones (never(never
with carbide burs) increases the bond strength, but does not providewith carbide burs) increases the bond strength, but does not provide
sufficient retention for the whole period of the orthodontic treatment.sufficient retention for the whole period of the orthodontic treatment.
 Micro-etching of the ceramic surfaceMicro-etching of the ceramic surface. Small intraoral sandblaster. Small intraoral sandblaster
with a contrangle nozzle have been used. They usewith a contrangle nozzle have been used. They use 5050 µµmm oror
coarser aluminum oxide (A12O3)coarser aluminum oxide (A12O3) powder connected to apowder connected to a
compressed – air source in the operatory. An alternative powdercompressed – air source in the operatory. An alternative powder
that could be used in cases where patients have an allergic reactionthat could be used in cases where patients have an allergic reaction
to aluminum oxide isto aluminum oxide is silicon carbidesilicon carbide..
 Application ofApplication of silanesilane to the ceramic surface has been used toto the ceramic surface has been used to
promote the adhesion of resin composites. For example,promote the adhesion of resin composites. For example, y-y-
methacryloxy-propyltrimethoxysilanemethacryloxy-propyltrimethoxysilane is a coupling agent thatis a coupling agent that
provides reactive sites for inorganic and organic components.provides reactive sites for inorganic and organic components.

This silane contains silanol groups that can bond with silanols on theThis silane contains silanol groups that can bond with silanols on the
ceramic surface, forming a siloxane (Si-O-Si) bond. Additionally, thisceramic surface, forming a siloxane (Si-O-Si) bond. Additionally, this
silane contains methacrylate groups that can form covalent bondssilane contains methacrylate groups that can form covalent bonds
with the polymer matrix of the resin composite.with the polymer matrix of the resin composite.
 Etching of the ceramic surface with hydrofluoric acid (HF)Etching of the ceramic surface with hydrofluoric acid (HF) waswas
introduced in the early 1980s for bonding porcelain laminateintroduced in the early 1980s for bonding porcelain laminate
veneers.. A commonly used hydrofluoric acid product has aveneers.. A commonly used hydrofluoric acid product has a
concentration ofconcentration of 9.6% in gel form9.6% in gel form and is placed on the ceramic forand is placed on the ceramic for
two to four minutes. Other available commercial products usetwo to four minutes. Other available commercial products use 4%4%
acidulated phosphate fluoride containing 1.43% hydrofluoric acidacidulated phosphate fluoride containing 1.43% hydrofluoric acid inin
gel form for two minutes. Acid etching of ceramic surface isgel form for two minutes. Acid etching of ceramic surface is
recommended when maximum bond strength is required.recommended when maximum bond strength is required.

 The protocol for optimal bonding to ceramic surfaces is asThe protocol for optimal bonding to ceramic surfaces is as
follows:follows:
 (1)(1) The glaze is first removed by sandblasting, using 50The glaze is first removed by sandblasting, using 50 µµm Al2O3 form Al2O3 for
two to four seconds.two to four seconds.
 (2)(2) The ceramic surface is then etched for two minutes, using 9.6%The ceramic surface is then etched for two minutes, using 9.6%
hydrofluoric acid in gel form.hydrofluoric acid in gel form.
 (3)(3) Subsequently, two to three coatings of a silane coupling agent areSubsequently, two to three coatings of a silane coupling agent are
applied to the etched surface, followed by drying.applied to the etched surface, followed by drying.
 (4)(4) Two layers of unfilled resin are then applied to form a thin coating.Two layers of unfilled resin are then applied to form a thin coating.
 (5)(5) Finally, the bracket is bonded to the prepared ceramic surface,Finally, the bracket is bonded to the prepared ceramic surface,
using a highly filled Bis-GMA resin .using a highly filled Bis-GMA resin .

 BONDING TO CASTING ALLOYSBONDING TO CASTING ALLOYS
Proper surface preparation and special adhesives areProper surface preparation and special adhesives are
required for acceptable bonding to casting alloys. Althoughrequired for acceptable bonding to casting alloys. Although
roughening the alloy surface with a stone increases the bondroughening the alloy surface with a stone increases the bond
strength to brackets, intraoral sandblasters provide better results.strength to brackets, intraoral sandblasters provide better results.
In recent years, adhesives that chemically bond to metalIn recent years, adhesives that chemically bond to metal
surfaces have been developed. The commercial productssurfaces have been developed. The commercial products Super-Super-
Bond C&BBond C&B (Sun Medical, Kyoto, Japan) and(Sun Medical, Kyoto, Japan) and C&B MetabondC&B Metabond
(Parkell, Farmingdale, NY, USA) combine(Parkell, Farmingdale, NY, USA) combine 4-META4-META (4-(4-
methacryloxyethyltrimethyl anhydride) withmethacryloxyethyltrimethyl anhydride) with tributylborane monomertributylborane monomer
andand a polymer powder.a polymer powder.

It is believed that 4-META forms aIt is believed that 4-META forms a hydrogen bond with hydroxylhydrogen bond with hydroxyl
groupsgroups found on the prepared surface of the metal.found on the prepared surface of the metal.
In vitro studies have shown that brackets bonded to sandblastedIn vitro studies have shown that brackets bonded to sandblasted
gold alloys using these 4-META adhesives attain the bond strengthgold alloys using these 4-META adhesives attain the bond strength
values to acid-etched enamel. It has been found that thesevalues to acid-etched enamel. It has been found that these
adhesives bond better to base metal alloys than to gold alloys.adhesives bond better to base metal alloys than to gold alloys.
.Panavia EX.Panavia EX andand PanaviaPanavia 2121(J. Morita USA, Tustin, CA, USA).(J. Morita USA, Tustin, CA, USA).
BONDING TO AMALGAMBONDING TO AMALGAM
Sandblasting the surface of the amalgam restoration, followed bySandblasting the surface of the amalgam restoration, followed by
use of the adhesives,use of the adhesives, 4-=META4-=META,, 10MDP10MDP(10-methacryloyloxydecyl(10-methacryloyloxydecyl
dihydrogenphosphate)dihydrogenphosphate) // Bis-GMABis-GMA, and, and intermediate resinsintermediate resins,,
improves bonding to dental amalgam. However, the bond strengthimproves bonding to dental amalgam. However, the bond strength
achieved is at best about half that for resin composite to etchedachieved is at best about half that for resin composite to etched
enamel.enamel.

 Sandblasting the dental amalgam surface produces significantlySandblasting the dental amalgam surface produces significantly
better bonding than that achieved with a polished dental amalgambetter bonding than that achieved with a polished dental amalgam
surface.surface.
 However, when compared to roughening with a diamond bur,However, when compared to roughening with a diamond bur,
sandblasting of dental amalgam surfaces did not produce bettersandblasting of dental amalgam surfaces did not produce better
bonding.bonding.
 BONDING TO RESIN COMPOSITESBONDING TO RESIN COMPOSITES
 As the resin composite restoration ages in the mouth, lessAs the resin composite restoration ages in the mouth, less
unreacted methacrylate groupsunreacted methacrylate groups remain on the surface for cross-remain on the surface for cross-
linking with the bonding resin. Additionally, the exposed fillerlinking with the bonding resin. Additionally, the exposed filler
particles are freed (“plucked out”) from the silane-coupling agent. Toparticles are freed (“plucked out”) from the silane-coupling agent. To
achieve acceptable bonding to these restoration surfaces, theachieve acceptable bonding to these restoration surfaces, the
uppermost resin composite layer has to be removed with a diamonduppermost resin composite layer has to be removed with a diamond
or carbide bur.or carbide bur.

 Then the surface is acid-etched withThen the surface is acid-etched with 37% phosphoric acid37% phosphoric acid.. SilanationSilanation
follows before application of an unfilled resin and bonding. Thefollows before application of an unfilled resin and bonding. The
reported bond strengths to resin laminates are aboutreported bond strengths to resin laminates are about 60-85%60-85% of theof the
bond strengths to etched enamel, and this level of bond strength hasbond strengths to etched enamel, and this level of bond strength has
been judged adequate to provide clinically acceptable retention.been judged adequate to provide clinically acceptable retention.
 BONDING TO ACRYLIC RESINSBONDING TO ACRYLIC RESINS
 If Polymethyl methacrylate (PMMA) has been used, the surfaceIf Polymethyl methacrylate (PMMA) has been used, the surface
of the provisional restoration has to be firstof the provisional restoration has to be first wetted with methylwetted with methyl
methacrylatemethacrylate for three minutesfor three minutes. The brackets can then be bonded. The brackets can then be bonded
using a bonding agent (e.g., unfilled resin) and resin composite.using a bonding agent (e.g., unfilled resin) and resin composite.
Alternatively, the bracket can be attached using PMMA with theAlternatively, the bracket can be attached using PMMA with the
brush-bead technique, or it can be embedded in the PMMAbrush-bead technique, or it can be embedded in the PMMA
provisional restoration.provisional restoration.

 Divided into two categories depending upon site of failuresDivided into two categories depending upon site of failures
 1.1. Adhesive – enamel bond failuresAdhesive – enamel bond failures
 2. Adhesive – bracket bond failures2. Adhesive – bracket bond failures
Possible causes of Adhesive – enamel Bond failuresPossible causes of Adhesive – enamel Bond failures
1. Contamination of etched enamel by saliva, moisture or oil from1. Contamination of etched enamel by saliva, moisture or oil from
water line.water line.
2. Insufficient rinsing of etchant from tooth before bonding.2. Insufficient rinsing of etchant from tooth before bonding.
3. Inadequate drying of enamel surface precludes penetration of3. Inadequate drying of enamel surface precludes penetration of
resin.resin.
4. Over – etching demineralizes enamel, reduces depth of resin4. Over – etching demineralizes enamel, reduces depth of resin
tags penetration, and removes excessive amounts of enamel.tags penetration, and removes excessive amounts of enamel.
5. Faulty bonding materials, materials with expired date.5. Faulty bonding materials, materials with expired date.

Possible Causes of Adhesive – bracket bond failuresPossible Causes of Adhesive – bracket bond failures
 Excessive force exerted on bracket from occlusion or excessiveExcessive force exerted on bracket from occlusion or excessive
from appliance.from appliance.
 Movement of bracket during initial setting of adhesive.Movement of bracket during initial setting of adhesive.
 Contaminated bracket mesh (oil from hands, glove powder orContaminated bracket mesh (oil from hands, glove powder or
rebonded bracket).rebonded bracket).
 Adhesive not buttered into base firmly.Adhesive not buttered into base firmly.
 Activator not placed on bracket in paste primer system.Activator not placed on bracket in paste primer system.
 Inadequate cure of light cured resin composite.Inadequate cure of light cured resin composite.

Avoid bond failures….Avoid bond failures….
 Increases treatment timeIncreases treatment time
 Additional cost in materialsAdditional cost in materials
 Unexpected additional visits by patients.Unexpected additional visits by patients.

 Bonded brackets that become loose during treatment consumeBonded brackets that become loose during treatment consume
much chair time, are poor publicity for the office, and are amuch chair time, are poor publicity for the office, and are a
nuisance to the orthodontist..nuisance to the orthodontist..
 The best way to avoid loose brackets is to adhere strictly to theThe best way to avoid loose brackets is to adhere strictly to the
rules for good bonding technique.rules for good bonding technique.
 The loose bracket is removed from the archwire. Any adhesiveThe loose bracket is removed from the archwire. Any adhesive
remaining on the tooth surface is removed with TC bur. Theremaining on the tooth surface is removed with TC bur. The
adhesive remaining on the loose bracket is treated byadhesive remaining on the loose bracket is treated by
sandblasting.sandblasting.

 Until all visible material is removed from the base. The tooth isUntil all visible material is removed from the base. The tooth is
then etched with Ultraetch 35% phosphoric acid gel for 15 to 30then etched with Ultraetch 35% phosphoric acid gel for 15 to 30
seconds. On inspection, the enamel surface may not be uniformlyseconds. On inspection, the enamel surface may not be uniformly
frosty because areas are likely still retaining resin. The phosphoricfrosty because areas are likely still retaining resin. The phosphoric
acid will re-etch any exposed enamel and remove the pellicle onacid will re-etch any exposed enamel and remove the pellicle on
any exposed resin.any exposed resin.
 Sonis AL (AJO 1996)Sonis AL (AJO 1996) found out that the bond strength offound out that the bond strength of
sandblasted rebonded brackets is comparable to the success ratesandblasted rebonded brackets is comparable to the success rate
of new brackets.of new brackets.

RECYCLINGRECYCLING
 Several methods of recycling debonded attachments for repeatSeveral methods of recycling debonded attachments for repeat
use, either by commercial companies or by duplicated procedureuse, either by commercial companies or by duplicated procedure
in the office, are available.in the office, are available.
 The main goal of the recycling process is to remove the adhesiveThe main goal of the recycling process is to remove the adhesive
from the bracket completely without damaging or weakening thefrom the bracket completely without damaging or weakening the
delicate bracket backing or distorting the dimensions of the bracketdelicate bracket backing or distorting the dimensions of the bracket
slot.slot.
 Commercial processes employ heatCommercial processes employ heat ( about 450º C ),( about 450º C ), to burn offto burn off
resin, followed by eloctropolishing to remove the oxide buildupresin, followed by eloctropolishing to remove the oxide buildup
(e.g. Esmadent)(e.g. Esmadent) or they use solvent stripping combined with highor they use solvent stripping combined with high
frequency vibrations and only flash electropolishing (e.g.,frequency vibrations and only flash electropolishing (e.g., Ortho –Ortho –
Cycle).Cycle).
 The electropolishing is needed for removal of any tarnish or oxideThe electropolishing is needed for removal of any tarnish or oxide
formed during the elimination of the adhesive from the cloggedformed during the elimination of the adhesive from the clogged
pad.pad.

 Buchman ( AJO 1980)Buchman ( AJO 1980)
The methods of 3 recycling companies (Esmadent, OrhoThe methods of 3 recycling companies (Esmadent, Orho
cycle & Ortho Bonding ) and the flame method are examined for theircycle & Ortho Bonding ) and the flame method are examined for their
effects on bracket base torque, slot width & mechanical properties.effects on bracket base torque, slot width & mechanical properties.
Changes in slot width & base torque angle showed no statisticallyChanges in slot width & base torque angle showed no statistically
differencedifference..
- Recycling of used ceramic brackets- Recycling of used ceramic brackets by heating or resilanatingby heating or resilanating
appears to produce an acceptable bond strength.appears to produce an acceptable bond strength.

Recycling of ceramic bracketsRecycling of ceramic brackets
 Kenneth and Djeng (Jco 1990),Kenneth and Djeng (Jco 1990),
composite resin remaining on the bracket base is removedcomposite resin remaining on the bracket base is removed
by holding the bracket with a pair of tweezers and heating it in a miniby holding the bracket with a pair of tweezers and heating it in a mini
torch until it turns cherry red .torch until it turns cherry red .
On cooling, the residual composite resin will turn chalky whiteOn cooling, the residual composite resin will turn chalky white
and flaky. It can easily be removed by gently tapping the bracket onand flaky. It can easily be removed by gently tapping the bracket on
a table top or by lightly scraping the base with a wax knife thisa table top or by lightly scraping the base with a wax knife this
produces a clean surface.produces a clean surface.
 The bracket is allowed to cool for 5 minutes until it reaches roomThe bracket is allowed to cool for 5 minutes until it reaches room
temperatures.temperatures.
 It is dried with compressed air to remove any possible residue. It isIt is dried with compressed air to remove any possible residue. It is
rinsed in 100% isopropyl alcohol at pure acetone and allowed to airrinsed in 100% isopropyl alcohol at pure acetone and allowed to air
dry.dry.

Apply phosphoric acid etchant with a cotton pellet and leave itApply phosphoric acid etchant with a cotton pellet and leave it
on the base for 60 to 90 seconds. Do not rinse of the acid because iton the base for 60 to 90 seconds. Do not rinse of the acid because it
is used to hydrolyze the hydrogen atom and hydroxyl groups in theis used to hydrolyze the hydrogen atom and hydroxyl groups in the
silica surface. Apply the primer over the acid and leave it on thesilica surface. Apply the primer over the acid and leave it on the
surface for one minute before rinsing and drying thoroughly.surface for one minute before rinsing and drying thoroughly.
After 10 minutes of air drying the primed brackets can beAfter 10 minutes of air drying the primed brackets can be
bonded to the etched enamel surface with a chemically “or” lightbonded to the etched enamel surface with a chemically “or” light
cured composite resin.cured composite resin.

 The objectives of debonding are to remove the attachment and allThe objectives of debonding are to remove the attachment and all
the adhesive resin from the tooth and restore the surface as closelythe adhesive resin from the tooth and restore the surface as closely
as possible to its pretreatment condition without inducing iatrogenicas possible to its pretreatment condition without inducing iatrogenic
damage.damage.
 To obtain these objectives, a correct technique is of fundamentalTo obtain these objectives, a correct technique is of fundamental
importance.importance.
 Debonding may be unnecessarily time consuming and damaging toDebonding may be unnecessarily time consuming and damaging to
the enamel if performed with improper technique or in a carelessthe enamel if performed with improper technique or in a careless
mannermanner..

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