Bonding in orthodontics

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Presented By:
Dr. Anil Kumar Godara
Mar 14, 2019

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CONTENTS:CONTENTS:
 INTRODUCTIONS
 HISTORY OF BONDING
 ADVANTAGES OF BONDING
 DISADVANTAGES OF BONDING
 BASIC BONDING PROCEDURE 1)CLEANING
2)ENAMEL CONDITIONING
3)SEALING
4)BONDING
 DIRECT BONDING
 INDIRECT BONDING
 DEBONDING
 REBONDING
 RECYCLING
 FACTORS AFFECTING THE BOND STRENGH
 CONCLUSION
 REFERENCES

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WHAT IS BONDING???WHAT IS BONDING???
A term conventionally used to describe theA term conventionally used to describe the
attachment of the bracket using bondingattachment of the bracket using bonding
resins to the enamel surfaces.resins to the enamel surfaces.
BASIS OF BONDING
Mechanical inter locking of an adhesive to
irregularities in the enamel surface of the tooth
and to mechanical locks formed in the base of the
orthodontic attachment.

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HISTORYHISTORY
• Buonocore (1955)Buonocore (1955)
He introduced acid etching technique. He demonstrated
increased adhesion produced by acid pretreatment of
enamel. This led to dramatic changes in practice of
orthodontics . He improved retention of methyl
methacrylate to enamel – 85% phosphoric acid for 30
seconds
Not successful for orthodontic purposes –
•High polymerization shrinkage.
•High coefficient of thermal expansion
•Couldn’t withstand high occlusal forces

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Bisphenol Glycidyl DimethacrylateBisphenol Glycidyl Dimethacrylate
(Bis-GMA)(Bis-GMA)
• BOWEN 1962BOWEN 1962
• Greater strengthGreater strength
• Lower water absorptionLower water absorption
• Less polymerization shrinkageLess polymerization shrinkage
• 2-paste system2-paste system
• Strongest adhesives for metal bracketsStrongest adhesives for metal brackets
Bowen (1962)Bowen (1962)

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Demerit of Bis-GMA –Demerit of Bis-GMA –
• HardnessHardness
• Poor penetration due to increased viscosity – dilutePoor penetration due to increased viscosity – dilute
with MMAwith MMA
• Plastic brackets could not be used – primer forPlastic brackets could not be used – primer for
partially dissolving addedpartially dissolving added
• Active life less than powder liquid systemActive life less than powder liquid system

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Newman (1965)Newman (1965)
• With the advent of epoxy resin bonding , began to apply
these findings to direct bonding of orthodontic
attachments.
• First to bond orthodontic brackets with epoxy resinsFirst to bond orthodontic brackets with epoxy resins..
• Start of direct bonding procedure.Start of direct bonding procedure.
• For short-term treatment with anterior brackets.For short-term treatment with anterior brackets.
• Did not replace ‘metal-band’ system.Did not replace ‘metal-band’ system.

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Described an epoxy resin system to withstandDescribed an epoxy resin system to withstand
orthodontic forces.orthodontic forces.
Smith in 1968Smith in 1968
introduced zinc polyacrylate cement and bracketintroduced zinc polyacrylate cement and bracket
bonding with this cement.bonding with this cement.
Retief In 1965Retief In 1965

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Fujio MiuraFujio Miura and associatesin 1971 –and associatesin 1971 –
• Introduced –Introduced – ORTHOMITEORTHOMITE
• MMA - Tri–N–Butyl Borane (catalyst)MMA - Tri–N–Butyl Borane (catalyst)
• Increased adhesive strengthIncreased adhesive strength
• Coupling agent – ‘silane’Coupling agent – ‘silane’
metha-cryloxy-propyl-trimethoxy-silanemetha-cryloxy-propyl-trimethoxy-silane
• Increased adhesive penetrationIncreased adhesive penetration
• Chemically bonded to adhesiveChemically bonded to adhesive
• Affinity to enamelAffinity to enamel

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Merits of MMA adhesives:Merits of MMA adhesives:
1.1. Plastic bracketsPlastic brackets
2.2. Good storage stabilityGood storage stability
3.3. Increased working time – brush-on / dip-inIncreased working time – brush-on / dip-in
4.4. Elimination of sealant - good penetration into enamelElimination of sealant - good penetration into enamel
surfacesurface
5.5. Less damage during debondingLess damage during debonding
Demerits of MMA adhesives:Demerits of MMA adhesives:
1.1. Fluctuating proportion of powder-liquid depending onFluctuating proportion of powder-liquid depending on
operatoroperator
2.2. Poor mechanical interlocking to metal bracket basesPoor mechanical interlocking to metal bracket bases

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In early 1970s considerable no, of preliminary
reports were published on different
commercially available direct &indirect
bonding system.
A survey conducted by LEONARD
GOERLICK in 1979 JCO revealed almost
93% of orthodontists started bonding
brackets (at least in anteriors )instead of
banding.

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• In 1974In 1974
• HNPM – hydroxynapthoxypropylmethacrylateHNPM – hydroxynapthoxypropylmethacrylate
• Eliminated silaneEliminated silane
ORTHOMITE II
4 - META4 - META
• methacryloxyethyl trimellitate anhydridemethacryloxyethyl trimellitate anhydride
• Plastic & metalPlastic & metal
• PRE-PRIMED bracketsPRE-PRIMED brackets
• Base was primed with adhesiveBase was primed with adhesive
• Bracket base covered with PMMA powderBracket base covered with PMMA powder
• Base dipped in monomer and pressed onto etched surface.Base dipped in monomer and pressed onto etched surface.
• Bond strength less than manual applicationBond strength less than manual application

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• In the early 1970s, a considerable number of
different materials and procedures were introduced.
The clinical implications of Acid etching and
bonding had come to stay in Orthodontics and has
been verified by clinicians world wide. Today most
orthodontists directly or indirectly bond attachments
to the teeth.
• In 1991, a commercially available ethyl-
cyanoacrylate material was tested as an orthodontic
bracket adhesive and found to have significantly
higher tensile strength than a conventional
composite.

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BRACKET BONDINGBRACKET BONDING
The simplicity of bonding can be misleading. TheThe simplicity of bonding can be misleading. The
technique can undoubtedly be misused, not onlytechnique can undoubtedly be misused, not only
by an inexperienced clinician but also by moreby an inexperienced clinician but also by more
experienced orthodontists who do not performexperienced orthodontists who do not perform
procedures with care.procedures with care.
Success in bonding requires understanding of andSuccess in bonding requires understanding of and
adherence to accepted orthodontic and preventiveadherence to accepted orthodontic and preventive
dentistry principles.dentistry principles.

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ADVANTAGES OF BONDINGADVANTAGES OF BONDING
• Esthetically superior.Esthetically superior.
• Faster and simpler.Faster and simpler.
• Less discomfort for the patient.Less discomfort for the patient.
• Arch length not increased by band material.Arch length not increased by band material.

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• More precise bracket placement.More precise bracket placement.
• More hygienic.More hygienic.
• Partially erupted/ fractured tooth can bePartially erupted/ fractured tooth can be
controlled.controlled.
• Proximal reduction is possible during treatment.Proximal reduction is possible during treatment.
• Attachments can be bonded to artificial toothAttachments can be bonded to artificial tooth
surfaces like amalgam, porcelain, gold etc.surfaces like amalgam, porcelain, gold etc.

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• Inter proximal areas are accessible for proximalInter proximal areas are accessible for proximal
build up.build up.
• Interproximal caries can be detected and treated.Interproximal caries can be detected and treated.
• No band spaces present to close after treatment.No band spaces present to close after treatment.
• Brackets may be recycled, further reducing cost.Brackets may be recycled, further reducing cost.
• Lingual brackets can be used when the patientLingual brackets can be used when the patient
rejects visible orthodontic appliances.rejects visible orthodontic appliances.

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DISADVANTAGES OF BONDINGDISADVANTAGES OF BONDING
• Bonded bracket has a weaker attachment than aBonded bracket has a weaker attachment than a
cemented band.cemented band.
• Some bonding adhesives are not sufficientlySome bonding adhesives are not sufficiently
strong.strong.
• Excess adhesive, if extends beyond the bracketExcess adhesive, if extends beyond the bracket
base, becomes areas of plaque accumulation.base, becomes areas of plaque accumulation.
• Protection against inter proximal caries providedProtection against inter proximal caries provided
by well-contoured cemented bands is absent.by well-contoured cemented bands is absent.

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• Bonding is more complicated when lingualBonding is more complicated when lingual
auxiliaries are required or if headgears areauxiliaries are required or if headgears are
attached.attached.
• Re-bonding requires more preparation than re-Re-bonding requires more preparation than re-
cementing a loose band.cementing a loose band.
• Debonding is more time-consuming thanDebonding is more time-consuming than
debanding.debanding.

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STEPS INVOLVED IN BONDINGSTEPS INVOLVED IN BONDING
PROCEDUREPROCEDURE
• CLEANING.CLEANING.
• ENAMEL CONDITIONING.ENAMEL CONDITIONING.
• SEALING.SEALING.
• BONDING.BONDING.

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PREPARATORY PROCEDURESPREPARATORY PROCEDURES
Rubber cup or polishing
brush + thin slurry of
medium grain pumice
power + water on a slow
speed hand piece.
….to remove any debris, plaque or
pellicle on the tooth surface.

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CONVENTIONAL PUMICECONVENTIONAL PUMICE
POLISHING vs ABRADING WITH TCPOLISHING vs ABRADING WITH TC
BURBUR
Cleaning of the teeth with pumice will remove plaqueCleaning of the teeth with pumice will remove plaque
and the organic pellicle that normally covers alland the organic pellicle that normally covers all
teeth. This requires rotary instruments, either ateeth. This requires rotary instruments, either a
rubber cup or a polishing brush.rubber cup or a polishing brush.
Recently, the need for conventional pumice polishingRecently, the need for conventional pumice polishing
before acid etching has been questioned.before acid etching has been questioned.

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Reisner et al foundReisner et al found moremore
consistent resultsconsistent results when buccalwhen buccal
tooth surfaces were lightlytooth surfaces were lightly
abraded with TC burabraded with TC bur (#1172) at(#1172) at
slow speed (25000rpm) thanslow speed (25000rpm) than
when surfaces were pumicedwhen surfaces were pumiced
for ten seconds before acidfor ten seconds before acid
etching.etching.

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The purpose of the study was to determine whetherThe purpose of the study was to determine whether
pumice prophylaxis, performed before acid etching,pumice prophylaxis, performed before acid etching,
enhances the bond strength and retention rate ofenhances the bond strength and retention rate of
orthodontic brackets.orthodontic brackets.

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The results of this study did not provide any clear support for
pumice prophylaxis as a prerequisite for achieving adequate
enamel etching during orthodontic bonding procedures.
In vitro bond strengths were similar in pumiced and
nonpumiced samples as were the etching patterns observed under
SEM.
Pumiced surfaces showed scratches under SEM, whereas
nonpumiced surfaces showed retained plaque and debris in some
areas after etching.
Clinically, bracket failure rates were similar whether or not a
pumice prophylaxis was performed as part of the bonding
procedure.

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FLUORIDE INCORPORATED PUMICEFLUORIDE INCORPORATED PUMICE
For the purpose of reducing carious lesions in bondedFor the purpose of reducing carious lesions in bonded
teeth, studies were conducted after fluoride wasteeth, studies were conducted after fluoride was
incorporated in pumiceincorporated in pumice
But it was proved that fluoride incorporated did notBut it was proved that fluoride incorporated did not
bring about any considerable reduction in thebring about any considerable reduction in the
incidence of caries in bonded teethincidence of caries in bonded teeth

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It can be defined as the act or process of selectiveIt can be defined as the act or process of selective
dissolution.dissolution.
In Dentistry –In Dentistry – The selective dissolution of the toothThe selective dissolution of the tooth
enamel, metal or porcelain through the use of acidenamel, metal or porcelain through the use of acid
or other agents to create a retentive surface.or other agents to create a retentive surface.
Achieving a bond between enamel and resin basedAchieving a bond between enamel and resin based
restoratives involves discrete etching of the enamelrestoratives involves discrete etching of the enamel
in order to provide selective dissolutions within order to provide selective dissolutions with
resultant micro porosity.resultant micro porosity.

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Enamel BondingEnamel Bonding
Adhesion to enamel is achieved through acid etchingAdhesion to enamel is achieved through acid etching
of the highly mineralized tissue.of the highly mineralized tissue.
In 1955,In 1955, BuonocoreBuonocore proposed thatproposed that
acids can be used to alter theacids can be used to alter the
surface of enamel to render itsurface of enamel to render it
”more receptive to bonding”. He”more receptive to bonding”. He
was the first to describe acid etchwas the first to describe acid etch
technique for enamel bonding.technique for enamel bonding.
Dr. Michael Buonocore (1955)Dr. Michael Buonocore (1955)
introduced acid etching – Usedintroduced acid etching – Used
85% phosphoric acid.85% phosphoric acid.

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MOISTURE CONTROL &MOISTURE CONTROL &
ISOLATIONISOLATION
After the rinse, salivary control and maintenance of
a dry working field is essential

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• Lip expandersLip expanders
• Saliva ejectorsSaliva ejectors
• Tongue guards with biteTongue guards with bite
blocksblocks
• Salivary duct obstructors :Salivary duct obstructors :
Dri-AnglesDri-Angles →→ to restrictto restrict
flow of saliva from parotidflow of saliva from parotid
duct.duct.
• Cotton or gauze rollsCotton or gauze rolls
• AntisialagoguesAntisialagogues
– tabletstablets
– injectable solutionsinjectable solutions
• Banthine, Pro-Banthine,Banthine, Pro-Banthine,
atropine sulfate, etc.,atropine sulfate, etc.,

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Enamel bonding system basically consists of an unfilledEnamel bonding system basically consists of an unfilled
liquid and acrylic monomer which wets the high energyliquid and acrylic monomer which wets the high energy
surface and is drawn into the micro porosities createdsurface and is drawn into the micro porosities created
by capillary action.by capillary action.
Enamel Etching:Enamel Etching:
Goals of enamel etching are:Goals of enamel etching are:
• To clean the enamel.To clean the enamel.
• Remove enamel smear layer.Remove enamel smear layer.
• To increase microscopic roughness by removal ofTo increase microscopic roughness by removal of
prismatic and inter prismatic mineral crystals.prismatic and inter prismatic mineral crystals.
• To increase surface free energy of enamel.To increase surface free energy of enamel.

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Etching increases the surface energy of enamel fromEtching increases the surface energy of enamel from
28 dynes/cm to 72 dynes / cm. It removes about 1028 dynes/cm to 72 dynes / cm. It removes about 10
µm of enamel surface and creates a micro porousµm of enamel surface and creates a micro porous
layer from 5 to 50 µm deep.layer from 5 to 50 µm deep.
Patterns Of Etching:Patterns Of Etching:
(Gwinnett & Silverstone, 1975)(Gwinnett & Silverstone, 1975)
Different etching patterns may be due to difference inDifferent etching patterns may be due to difference in
chemical composition and crystalline orientation.chemical composition and crystalline orientation.
Variations may be seen from site to site or fromVariations may be seen from site to site or from
tooth to tooth. On etching , Glistening enamel turnstooth to tooth. On etching , Glistening enamel turns
dull and appears “Frosty White”.dull and appears “Frosty White”.

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VARIOUS PATTERNS OF ETCHED ENAMEL
TYPE 1
Prism core removed
preferentially leaving the
peripheries intact .
Most common Type.
(HONEYCOMB APPEARANCE)

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TYPE 2
Peripheries are
preferentially removed
leaving the core intact
(COBBLESTONE APPEARANCE)

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TYPE 3
Indiscriminate Erosion:
In this type surface loss occurs
without exposing the
underlying enamel prisms.
More commonly observed in
the cervical regions of teeth
where enamel prisms do not
extend to the surface.
TYPE 4
Junction between
Type 1 and Type 2.

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RESIN TAGSRESIN TAGS
They are resinous extensions into microThey are resinous extensions into micro
porosities of enamel. Enamel bonding dependsporosities of enamel. Enamel bonding depends
on resin tags becoming interlocked with surfaceon resin tags becoming interlocked with surface
irregularities created by etching. Resin tags areirregularities created by etching. Resin tags are
formed circularly between enamel prisms andformed circularly between enamel prisms and
peripheries.peripheries.

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Resin
Resin
tags
Enamel
protrusions
Intact enamel
Original concept of micromechanical retention

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Resin
Resin
tags
Intact enamel
Acid dissolved
enamel protrusions
Acid resistant resin
infiltrated enamel
Revised concept of the bonding mechanism between
acid etched enamel and orthodontic resin adhesives
Interfacial resin
enamel interdiffusion
zone

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They are of two types:They are of two types:
MACRO TAGSMACRO TAGS – Which are formed at the– Which are formed at the
periphery. They are 2-5 nm in length.periphery. They are 2-5 nm in length.
MICRO TAGSMICRO TAGS – Which are formed at the cores of– Which are formed at the cores of
enamel prism.enamel prism.

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Fine network of thousands of smaller tags isFine network of thousands of smaller tags is
usually found across the end of each rod,usually found across the end of each rod,
where individual hydroxyapatite crystalswhere individual hydroxyapatite crystals
have been dissolved leaving crypts outlinedhave been dissolved leaving crypts outlined
by organic material. These finer tags areby organic material. These finer tags are
called micro tags.called micro tags.
MICRO AND MACRO TAGS ARE THEMICRO AND MACRO TAGS ARE THE
BASIS OF MICRO-MECHANICALBASIS OF MICRO-MECHANICAL
BONDING.BONDING.

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Micro tags are probably more important because ofMicro tags are probably more important because of
their larger number and greater surface content.their larger number and greater surface content.
Resin enamel bond strength depends on crossResin enamel bond strength depends on cross
sectional area of the resin tags and has no relationsectional area of the resin tags and has no relation
with the length of the resin tags ( Retief et al 1986)with the length of the resin tags ( Retief et al 1986)

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Penetration Depth Of Resin TagsPenetration Depth Of Resin Tags
A decisive factor in the mechanical retentionA decisive factor in the mechanical retention
phenomenon is the extensive interlockingphenomenon is the extensive interlocking
between the adhesive and the enamel.between the adhesive and the enamel.
A routine etching removes 3 to 10 µm ofA routine etching removes 3 to 10 µm of
surface enamel. Another 25 µm revealssurface enamel. Another 25 µm reveals
subtle histological alterations creating thesubtle histological alterations creating the
necessary mechanical interlocks deeper.necessary mechanical interlocks deeper.

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EFFECT OF ACID ETCHING DEPENDS ONEFFECT OF ACID ETCHING DEPENDS ON
SEVERAL PARAMETERS SUCH AS:SEVERAL PARAMETERS SUCH AS:
• The kind of acid used.The kind of acid used.
• The acid concentration.The acid concentration.
• The etching time.The etching time.
• The form of etchants ( Gel form preferred )The form of etchants ( Gel form preferred )
• The rinsing time.The rinsing time.
• The way in which etching is activated. EtchantThe way in which etching is activated. Etchant
should always be added in dabbing action. It shouldshould always be added in dabbing action. It should
not be applied in rubbing action because rubbingnot be applied in rubbing action because rubbing
may fracture the thin enamel rods, thereby reducingmay fracture the thin enamel rods, thereby reducing
the valley depths, irregularities and obliterating themthe valley depths, irregularities and obliterating them
with fractured enamel pieces.with fractured enamel pieces.

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• Whether enamel is instrumented before etching.Whether enamel is instrumented before etching.
• Chemical composition of enamelChemical composition of enamel
• Whether enamel is of primary or permanent teeth.Whether enamel is of primary or permanent teeth.
Since primary teeth with prismless enamel requiresSince primary teeth with prismless enamel requires
longer etching time.longer etching time.
• Whether enamel is fluoridated, demineralized orWhether enamel is fluoridated, demineralized or
stained.stained.

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EFFECTS OF ACID ETCHING ON THE ENAMELEFFECTS OF ACID ETCHING ON THE ENAMEL
SURFACE:SURFACE:
35 – 50% Phosphoric acid applied on tooth enamel for 6035 – 50% Phosphoric acid applied on tooth enamel for 60
sec will render the following effects and changes:sec will render the following effects and changes:
• It will etch the enamel substance with preferentialIt will etch the enamel substance with preferential
dissolution of inter prismatic enamel first, followed bydissolution of inter prismatic enamel first, followed by
the tops of prisms themselves. The least dissolvable arethe tops of prisms themselves. The least dissolvable are
the sides of prisms.the sides of prisms.
• Surface area is increased to 2000 times of its original unSurface area is increased to 2000 times of its original un
etched surface.etched surface.
• It will create valleys and depressions . Enamel surfaceIt will create valleys and depressions . Enamel surface
will be irregular at an average depth of 25 µm. (Valleyswill be irregular at an average depth of 25 µm. (Valleys
are places of inter prismatic enamel – top of prisms willare places of inter prismatic enamel – top of prisms will
have circumscribed depressionshave circumscribed depressions))

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• Acid etching will expose proteinaceous organicAcid etching will expose proteinaceous organic
matrix substance of enamel, which can add to thematrix substance of enamel, which can add to the
resin retention if it becomes adequately embeddedresin retention if it becomes adequately embedded
within the resin material.within the resin material.
• Mechanical cleansing and acid etching of enamelMechanical cleansing and acid etching of enamel
will assure removal of substrate, enamel cuticle,will assure removal of substrate, enamel cuticle,
salivary deposits, plaque components and anysalivary deposits, plaque components and any
possible adhesives to enamel surface , thuspossible adhesives to enamel surface , thus
exposing a cleaner, lesser contaminated and moreexposing a cleaner, lesser contaminated and more
wettable enamel.wettable enamel.
• Increases the surface energy.Increases the surface energy.

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• Treatment with phosphoric acid will add to enamelTreatment with phosphoric acid will add to enamel
surface a highly polarized phosphate group whichsurface a highly polarized phosphate group which
will increase the adhesive ability to the enamelwill increase the adhesive ability to the enamel
surface.surface.
• It has been suggested that by phosphoric acidIt has been suggested that by phosphoric acid
treatment a newly precipitated phase of calciumtreatment a newly precipitated phase of calcium
oxalate and organic tungstate complexes could beoxalate and organic tungstate complexes could be
created in isolated surface areas which can adherecreated in isolated surface areas which can adhere
to enamel and to resinous substances.to enamel and to resinous substances.

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Etching Procedure:Etching Procedure:
A)A) Concentrate Of Acid (30 -40% Phosphoric acid)Concentrate Of Acid (30 -40% Phosphoric acid)
Generally the acid etchant used is phosphoricGenerally the acid etchant used is phosphoric
acid of 30 to 40% concentrate. Calciumacid of 30 to 40% concentrate. Calcium
dissolution and etching depth increases untildissolution and etching depth increases until
concentration reaches 40%.concentration reaches 40%.
Gwinnett and Buonocore suggested the use of lowGwinnett and Buonocore suggested the use of low
acid concentrations to prevent the formation ofacid concentrations to prevent the formation of
precipitates that could interfere with adhesive.precipitates that could interfere with adhesive.
Application of 50% phosphoric acid for 60 sec resultsApplication of 50% phosphoric acid for 60 sec results
in the formation of ain the formation of a Mono Calcium phosphateMono Calcium phosphate
MonohydrateMonohydrate precipitate that can be rinsed off.precipitate that can be rinsed off.

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However, concentrations below 27% may create a DiHowever, concentrations below 27% may create a Di
Calcium Phosphate Monohydrate precipitate thatCalcium Phosphate Monohydrate precipitate that
cannot be easily removed and, consequently maycannot be easily removed and, consequently may
interfere with adhesion.interfere with adhesion.
Another study done by Legler- Reteif and Bradley inAnother study done by Legler- Reteif and Bradley in
1990, measured the depth of etch of enamel1990, measured the depth of etch of enamel
exposed to different concentrations of phosphoricexposed to different concentrations of phosphoric
acid and found that :-acid and found that :-
28.5 +/- 0.1nm When etched with28.5 +/- 0.1nm When etched with
37%phosphoric acid37%phosphoric acid
4.0 +/- 0.7nm When etched with4.0 +/- 0.7nm When etched with
5% Phosphoric acid.5% Phosphoric acid.

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B) Etching Time: (15 sec)B) Etching Time: (15 sec)
Glaspole and Ericson (1986) Tested the effectsGlaspole and Ericson (1986) Tested the effects
of different etching times and found that 15 sec ofof different etching times and found that 15 sec of
etching is reliable as like 60 sec.etching is reliable as like 60 sec.
Other invitro studies have demonstrated similar bondOther invitro studies have demonstrated similar bond
strengths and microleakage for etching times of 15strengths and microleakage for etching times of 15
and 60 sec ( Bastos et al 1988, Crim, Shay 1987, Giland 60 sec ( Bastos et al 1988, Crim, Shay 1987, Gil
Patrick, Ross 1991)Patrick, Ross 1991)
Advantages of shorter etching time is that it yieldsAdvantages of shorter etching time is that it yields
acceptable bond strengths while conservingacceptable bond strengths while conserving
enamel and saving time.enamel and saving time.

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C) Rinsing Time : (15 Sec)C) Rinsing Time : (15 Sec)
Bates 1982 showed that rinsing for 5 sec with water afterBates 1982 showed that rinsing for 5 sec with water after
etching with 37% phosphoric acid did not remove theetching with 37% phosphoric acid did not remove the
reaction products completely and thus resulted in low bondreaction products completely and thus resulted in low bond
strength of composites.strength of composites.
So rinsing time of atleast 15 sec is required to removeSo rinsing time of atleast 15 sec is required to remove
dissolved calcium phosphate which otherwise might impairdissolved calcium phosphate which otherwise might impair
infiltration of monomers into the etched enamel porosities.infiltration of monomers into the etched enamel porosities.
In vitro bond strengths of resin composites to phosphoric acidIn vitro bond strengths of resin composites to phosphoric acid
(or) acid etched enamel usually exceeds 20 MPa which is(or) acid etched enamel usually exceeds 20 MPa which is
sufficient for adequate retention and prevent microleakagesufficient for adequate retention and prevent microleakage
around enamel margins of Bonded teeth.around enamel margins of Bonded teeth.

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D) Form:D) Form:
Acid etchants may be available in liquid or gelAcid etchants may be available in liquid or gel
form. Gel etchants are preferred because of theform. Gel etchants are preferred because of the
ease and control of placement. Gels are often madeease and control of placement. Gels are often made
by adding colloidal silica or polymer beads to theby adding colloidal silica or polymer beads to the
acid. These additives change the pH of acid.acid. These additives change the pH of acid.
Phosphoric acid made into a gel with silica has aPhosphoric acid made into a gel with silica has a
higher pH than phosphoric acid thickened withhigher pH than phosphoric acid thickened with
polymer.polymer.
However etching pattern with gel and liquid remainsHowever etching pattern with gel and liquid remains
the same.the same.

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CLINICAL POINTSCLINICAL POINTS
• The etched enamel should have white frostedThe etched enamel should have white frosted
appearance, indicative of proper etching treatment.appearance, indicative of proper etching treatment.
• During application of etchant, it is important to beDuring application of etchant, it is important to be
aware of the risk of air bubbles that may beaware of the risk of air bubbles that may be
introduced at the interface. If these voids remain,introduced at the interface. If these voids remain,
these regions will not be etched.these regions will not be etched.
• If contamination occurs after etching, theIf contamination occurs after etching, the
contaminant should be removed and the enamelcontaminant should be removed and the enamel
should be etched again for 10 sec.should be etched again for 10 sec.

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ALTERNATIVES TO ENAMELALTERNATIVES TO ENAMEL
ETCHANTSETCHANTS
Other alternative etchants to phosphoric acid are:Other alternative etchants to phosphoric acid are:
• EDTAEDTA (Ethylene diamine Tetra acetic acid)–(Ethylene diamine Tetra acetic acid)–
Has low bond strength since it does not etchHas low bond strength since it does not etch
preferentially.preferentially.
• PYRUVIC ACIDPYRUVIC ACID – 10% pyruvic acid buffered– 10% pyruvic acid buffered
with Glycine to a pH of about 2.2, promotes highwith Glycine to a pH of about 2.2, promotes high
bond strength to enamel, but has been found tobond strength to enamel, but has been found to
be impractical because of its instability.be impractical because of its instability.

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• SULPHURIC ACIDSULPHURIC ACID –– 2% sulphuric acid2% sulphuric acid
used for 30 sec has shown to be as effectiveused for 30 sec has shown to be as effective
as phosphoric acid, whereas higheras phosphoric acid, whereas higher
concentration produces crystal deposits thatconcentration produces crystal deposits that
interfere in bonding and cannot be washedinterfere in bonding and cannot be washed
away easily.away easily.
With the introduction of total – etch systemWith the introduction of total – etch system
( Fusayama, 1979) in which enamel and( Fusayama, 1979) in which enamel and
dentin are etched simultaneously, weakerdentin are etched simultaneously, weaker
acids are applied to enamel.acids are applied to enamel.

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OTHER INORGANIC ACIDSOTHER INORGANIC ACIDS
Such asSuch as 2.5% Nitric Acid2.5% Nitric Acid and organic acids such asand organic acids such as 10%10%
Maleic acidMaleic acid andand 10% Citric acid10% Citric acid can also be used.can also be used.
However these weaker acids provide lower bond strengthsHowever these weaker acids provide lower bond strengths
when compared to 30 to 40% phosphoric acid.when compared to 30 to 40% phosphoric acid.
Alexander Gardner, 2001 –Alexander Gardner, 2001 –
• Compared 50% phosphoric acid and 2.5% Nitric acid andCompared 50% phosphoric acid and 2.5% Nitric acid and
found that bond strength and type of micro porositiesfound that bond strength and type of micro porosities
produced by nitric acid are much inferior to that ofproduced by nitric acid are much inferior to that of
phosphoricphosphoric acid.acid.

59
ALTERNATIVE METHOD PROPOSEDALTERNATIVE METHOD PROPOSED
BY R MAIJER AND D.C.SMITH:BY R MAIJER AND D.C.SMITH:
They have proposed a new method of bonding that involves crystalThey have proposed a new method of bonding that involves crystal
growth of enamel surface. This system consists of treating agrowth of enamel surface. This system consists of treating a
clean tooth surface with a 50% solution of Polyacrylic acidclean tooth surface with a 50% solution of Polyacrylic acid
containing Sulphate ions liberating Potassium Sulphate.containing Sulphate ions liberating Potassium Sulphate.
Calcium ions will react with these sulphate ions formingCalcium ions will react with these sulphate ions forming
calcium sulphate di hydrate in 1-2 minutes. As these crystals arecalcium sulphate di hydrate in 1-2 minutes. As these crystals are
nucleated with the tooth, they grow outwardly in a spheruliticnucleated with the tooth, they grow outwardly in a spherulitic
habit with irregular surfaces. They are similar to an etchedhabit with irregular surfaces. They are similar to an etched
enamel without loss of tooth structure. It was suggested thatenamel without loss of tooth structure. It was suggested that
these crystals trapped resin to retain it mechanically.these crystals trapped resin to retain it mechanically.
Subsequent works showed that these crystals interfered withSubsequent works showed that these crystals interfered with
bondingbonding

60
LASERSLASERS
Laser etching is a process of continuous vaporizationLaser etching is a process of continuous vaporization
and micro explosions due to vaporization of waterand micro explosions due to vaporization of water
trapped within hydroxyapatite material.trapped within hydroxyapatite material.
Amount of surface roughening is dependent on typeAmount of surface roughening is dependent on type
of wavelength of Laser used.of wavelength of Laser used.
Carbon Dioxide and Nd:YAG has proved to be theCarbon Dioxide and Nd:YAG has proved to be the
most effective lasers for etchingmost effective lasers for etching

61
However studies have shown that changes in surfaceHowever studies have shown that changes in surface
morphology and bond strength after laser etching are quitemorphology and bond strength after laser etching are quite
similar to acid etching.similar to acid etching.
It has disadvantages such as formation of cracks and thermalIt has disadvantages such as formation of cracks and thermal
damage.damage.
Lasers used are:Lasers used are:
Erbium, Chromium:Erbium, Chromium:
Yttrium –Selenium-Yttrium –Selenium-
Gallium- GarnetGallium- Garnet
Wave length – 2.78µmWave length – 2.78µm

62
THE AREA OF ETCHING:THE AREA OF ETCHING:
Entire Facial Surface / Small Area outside BracketEntire Facial Surface / Small Area outside Bracket
Pad??Pad??
Although it may seem logical to etch an areaAlthough it may seem logical to etch an area
slightly larger than the pad but in case ofslightly larger than the pad but in case of
fluoride application to be done after etching ;fluoride application to be done after etching ;
then there is no harm in etching the entirethen there is no harm in etching the entire
facial surface.facial surface.

63
Comparison Of Acid Gel ToComparison Of Acid Gel To
Solution:Solution:
No significant difference in the surface irregularities ofNo significant difference in the surface irregularities of
etch pattern of a gel and a solution.etch pattern of a gel and a solution.
Brannstrom et al 1982 –Brannstrom et al 1982 –
• No sig. diff. between etching effect of phosphoricNo sig. diff. between etching effect of phosphoric
acid gel and solution.acid gel and solution.
• Gel gives better control than a solution. whileGel gives better control than a solution. while
etching several teeth at the same time or whileetching several teeth at the same time or while
etching partially erupted teeth or difficult to accessetching partially erupted teeth or difficult to access
areas.areas.

64
Fluoride Pretreatment And AcidFluoride Pretreatment And Acid
Etching:Etching:
Brannstrom – Teeth pre treated with fluoride did not showBrannstrom – Teeth pre treated with fluoride did not show
any difference in the etch pattern when compared to theany difference in the etch pattern when compared to the
normal teeth.normal teeth.
Extra time is not necessary when teeth have been pre treatedExtra time is not necessary when teeth have been pre treated
with fluoride.with fluoride.
Examination of inner bracket surfaces of teeth treated withExamination of inner bracket surfaces of teeth treated with
fluoride have shown more irregularities than normal teethfluoride have shown more irregularities than normal teeth
which indicateswhich indicates better micro retention in these teethbetter micro retention in these teeth..
Hence Brannstrom strongly recommends fluoride preHence Brannstrom strongly recommends fluoride pre
treatment of teeth to be bonded.treatment of teeth to be bonded.

65
Another School Of Thought: Incorporation of fluoride to etchingAnother School Of Thought: Incorporation of fluoride to etching
solutions –solutions – Increases enamel resistance toIncreases enamel resistance to caries.caries.
Kajander et al – 2% and 4% acidified sodium fluoride solution areKajander et al – 2% and 4% acidified sodium fluoride solution are
effective in preventing decalcification of etched enamel surfaces.effective in preventing decalcification of etched enamel surfaces.
Bishara et al – The application of 2% or 4% sodium Fluoride doesBishara et al – The application of 2% or 4% sodium Fluoride does
not affect the bond strength of the adhesive to the enamel.not affect the bond strength of the adhesive to the enamel.
Thus the application of either 2% or 4% sodium fluoride in theThus the application of either 2% or 4% sodium fluoride in the
etchant solution enhances caries prevention during orthodonticetchant solution enhances caries prevention during orthodontic
treatment. But in case the patient has caries or hypoplasia thetreatment. But in case the patient has caries or hypoplasia the
etching time and concentration should be increased.etching time and concentration should be increased.

66
Removal Of Acid Residues AndRemoval Of Acid Residues And
Crystal Precipitates!Crystal Precipitates!
Subsequent to etching the enamelSubsequent to etching the enamel
surface must be entirely cleanedsurface must be entirely cleaned
from acid residues and from anyfrom acid residues and from any
loose deposits of calcium saltsloose deposits of calcium salts
lowering the retentive microlowering the retentive micro
porosities of etched enamel.porosities of etched enamel.
Studies have shown that a minimumStudies have shown that a minimum
of 5 seconds of continuous waterof 5 seconds of continuous water
spray is essential for the acidspray is essential for the acid
residues or crystal precipitates leftresidues or crystal precipitates left
after acid etching.after acid etching.

67
ADVANTAGES/DISADVANTAGES OFADVANTAGES/DISADVANTAGES OF
ACID ETCHING!!ACID ETCHING!!
Advantages:Advantages:
1.1. EconomicalEconomical
2.2. Achieves high bondAchieves high bond
strength- 16 to 22 MPa.strength- 16 to 22 MPa.
3.3. Can be combined withCan be combined with
Fluoride application.Fluoride application.
4.4. No complicatedNo complicated
instrument required &instrument required &
operator friendly.operator friendly.
Disadvantages:Disadvantages:
1.1. Invariably 10 – 20 µm ofInvariably 10 – 20 µm of
enamel loss.enamel loss.
2.2. Porosities left uncovered byPorosities left uncovered by
resins prone to staining andresins prone to staining and
deposition of corrosiondeposition of corrosion
products.products.
3.3. Increased chances of enamelIncreased chances of enamel
damage on debonding.damage on debonding.
4.4. The loss of acquired fluorideThe loss of acquired fluoride
residue in the 10 µm.residue in the 10 µm.

68
Use Of Air Abrasives As EnamelUse Of Air Abrasives As Enamel
Conditioners:Conditioners:
Tooth Surface Preparations With AirTooth Surface Preparations With Air
Abrasives:Abrasives:
The enamel surfaces are Sand blasted with 50The enamel surfaces are Sand blasted with 50
µm/ 90 µm Aluminium Oxide powder withµm/ 90 µm Aluminium Oxide powder with
a micro etcher.a micro etcher.
Sand blaster pressure is set at 90psi for 4 secSand blaster pressure is set at 90psi for 4 sec
at right angles from a distance of 5mm.at right angles from a distance of 5mm.
The abraded surfaces are subsequentlyThe abraded surfaces are subsequently
cleaned ultrasonically in distilled water forcleaned ultrasonically in distilled water for
ten minutes and dried with oil free air.ten minutes and dried with oil free air.
The area exposed to air abrasion can beThe area exposed to air abrasion can be
controlled with the use of rubberdam and acontrolled with the use of rubberdam and a
window in the lead foil.window in the lead foil.

69
SELF ETCHING CONDITIONERSSELF ETCHING CONDITIONERS
Increasing the length of resin tags need not increase the enamel-Increasing the length of resin tags need not increase the enamel-
resin bond strengthresin bond strength
A recent development is the self etching conditioner primerA recent development is the self etching conditioner primer
combination, exemplified by Clearfil Liner Bond 2 (Kuraray),combination, exemplified by Clearfil Liner Bond 2 (Kuraray),
which when applied for 30 seconds, the primer seems to etchwhich when applied for 30 seconds, the primer seems to etch
through dentinal smear layers about 1µm, creating excellentthrough dentinal smear layers about 1µm, creating excellent
bond strength.bond strength.
The use of self etching primers savesThe use of self etching primers saves time clinically, because theytime clinically, because they
do not require separate acid etching and water rinsing steps butdo not require separate acid etching and water rinsing steps but
are simply dried with air.are simply dried with air.

70
LONG TERM EFFECT-LONG TERM EFFECT-
DEMINERALIZATION!!!DEMINERALIZATION!!!
Despite the advances in orthodontic materials andDespite the advances in orthodontic materials and
techniques in recent years, the development oftechniques in recent years, the development of
decay around brackets during orthodonticdecay around brackets during orthodontic
treatment continues to be a problem.treatment continues to be a problem.
Preventing these lesions during treatment is anPreventing these lesions during treatment is an
important concern for the orthodontist, becauseimportant concern for the orthodontist, because
the lesions are unesthetic, unhealthy andthe lesions are unesthetic, unhealthy and
potentially irreversible.potentially irreversible.

71
• Nearly 50% of orthodontic patients exhibitsNearly 50% of orthodontic patients exhibits
clinically visibleclinically visible “WHITE SPOT LESIONS”“WHITE SPOT LESIONS” thatthat
lasts approximately two years. These lesions arelasts approximately two years. These lesions are
due to the demineralization of enamel by organicdue to the demineralization of enamel by organic
acids produced by cariogenic bacteria.acids produced by cariogenic bacteria.
Normal enamelWhite spot lesion

73
SEALINGSEALING
((APPLICATION OF BONDING AGENT)APPLICATION OF BONDING AGENT)
Adhesive/ bonding agent:Adhesive/ bonding agent:
““is a material which when applied to theis a material which when applied to the
surfaces of a substrate, can join them together, resistsurfaces of a substrate, can join them together, resist
separation and transmit load across the bond.”separation and transmit load across the bond.”
Since the composite resins are more viscous they doSince the composite resins are more viscous they do
not flow easily into the micro porosities of etchednot flow easily into the micro porosities of etched
enamel. Thus, to enhance the wettability of etchedenamel. Thus, to enhance the wettability of etched
enamel, enamel bonding agents were developedenamel, enamel bonding agents were developed

74
Unfilled resins have been traditionally used asUnfilled resins have been traditionally used as
bonding agents in resin composite bondingbonding agents in resin composite bonding
systems. The basic difference between these fluidsystems. The basic difference between these fluid
bonding resins and the resin composites is thebonding resins and the resin composites is the
absence of filler particles in the former.absence of filler particles in the former. The use ofThe use of
these unfilled resins is based upon their lowerthese unfilled resins is based upon their lower
viscosity and thus superior diffusion into enamelviscosity and thus superior diffusion into enamel
rods, resulting in improved interfacial adaptation.rods, resulting in improved interfacial adaptation.

75
Enamel bonding agents are made by combining
different methacrylates → BIS-GMA (bisphenol a –
glycidyl methacrylate) and TEGDMA (triethylene
glycol dimethacrylate). Sealant is best applied with a
foam pellet or brush with a single gingivoincisal
stroke on each tooth. Coating should be thin.

76
EXCESS SEALANTEXCESS SEALANT CANCAN
LEAD TO:LEAD TO:
• Bracket driftBracket drift
• Unnatural enamel topographyUnnatural enamel topography
when polymerized.when polymerized.
Use of sealant in orthodontic bondingUse of sealant in orthodontic bonding
is uncertain. Some investigatorsis uncertain. Some investigators
conclude that it is necessary toconclude that it is necessary to
achieve bond strength and toachieve bond strength and to
improve resistance to micro leakageimprove resistance to micro leakage
or for bothor for both!!!!

77
SEALANTS CAN BE:SEALANTS CAN BE:
• Chemically cured (auto- polymerized).Chemically cured (auto- polymerized).
• Light - polymerized.Light - polymerized.
Sealants permit a relaxation of moisture controlSealants permit a relaxation of moisture control
because this is no longer extremely important afterbecause this is no longer extremely important after
resin coating.resin coating.
Sealants provide enamel cover, in areas of adhesiveSealants provide enamel cover, in areas of adhesive
voids.voids.

78
CLASSIFICATION OF BONDING AGENTSCLASSIFICATION OF BONDING AGENTS
1.Based on their release into dental market as1.Based on their release into dental market as
generationsgenerations
2.Based on number of clinical application steps and2.Based on number of clinical application steps and
their interaction with the smear layer.their interaction with the smear layer.
3.Classification introduced at Symposium in3.Classification introduced at Symposium in
Philadelphia in 2000.Philadelphia in 2000.

79
A. BASED ON THEIR RELEASE INTOA. BASED ON THEIR RELEASE INTO
DENTALMARKET AS GENERATIONS.DENTALMARKET AS GENERATIONS.
Typically distinguished as first generation to seventhTypically distinguished as first generation to seventh
generationgeneration
Following are few typical examples:Following are few typical examples:
1st1st generation -generation - Cervident (ss white), Cosmic bondCervident (ss white), Cosmic bond
2nd2nd generationgeneration – Clearfil bond F– Clearfil bond F
3rd3rd generationgeneration - Syntac, Tenure- Syntac, Tenure
4th4th generation -generation - All bond 2, Clearfil linerAll bond 2, Clearfil liner
5th5th generationgeneration – Prime & Bond NT, P&B 2.1– Prime & Bond NT, P&B 2.1
6th6th generationgeneration - Prompt-L-Pop, Xeno- Prompt-L-Pop, Xeno
7th7th generationgeneration - I Bond, G Bond, Xeno IV- I Bond, G Bond, Xeno IV
This classification has no scientific validity since the 1st andThis classification has no scientific validity since the 1st and
2nd generation are not available and more over the new2nd generation are not available and more over the new
generations did not perform better than the last.generations did not perform better than the last.

81
B. BASED ON NUMBER OF CLINICALB. BASED ON NUMBER OF CLINICAL
APPLICATION STEPSAPPLICATION STEPS
• Smear layer modifying agents -Smear layer modifying agents - 1 step bonding1 step bonding
agents.agents.
• Smear layer removing agents -Smear layer removing agents - 2 step bonding2 step bonding
agents.agents.
• Smear layer dissolving agents -Smear layer dissolving agents - 3 step bonding3 step bonding
agents.agents.

82
C. CLASSIFICATION INTRODUCED ATC. CLASSIFICATION INTRODUCED AT
SYMPOSIUM IN PHILADELPHIA IN 2000.SYMPOSIUM IN PHILADELPHIA IN 2000.
Based the number of different working steps and theBased the number of different working steps and the
treatment of smear layer into Type1 to type 4.treatment of smear layer into Type1 to type 4.
• TypeType 11 and Typeand Type 22 - smear layer removing with- smear layer removing with
phosphoric acid etchingphosphoric acid etching
• TypeType 33 and Typeand Type 44 - smear layer dissolving types.- smear layer dissolving types.

83
• Type 1Type 1 adhesives - 3 step application - Etching,adhesives - 3 step application - Etching,
Priming and Bonding.Priming and Bonding.
• Type 2Type 2 adhesives - 2 step application - Etching &adhesives - 2 step application - Etching &
Priming and Bonding in one stepPriming and Bonding in one step
• Type 3Type 3 adhesives--2 step self - etching adhesives—adhesives--2 step self - etching adhesives—
self conditioning primer demineralizes enamelself conditioning primer demineralizes enamel
and dentin and is covered with a separate bondingand dentin and is covered with a separate bonding
layer.layer.
• Type 4Type 4 adhesives- self-etching 2 componentadhesives- self-etching 2 component
mixing products –all in one products.mixing products –all in one products.

84
SELF-ETCHING PRIMERSSELF-ETCHING PRIMERS
(JO 2003 , SEPTEMBER – VOL. 30)(JO 2003 , SEPTEMBER – VOL. 30)
C.J. Larmour & D.R. StirrupsC.J. Larmour & D.R. Stirrups
Application of a layer of unfilled resin or primer onto the etchedApplication of a layer of unfilled resin or primer onto the etched
enamel surface prior to bonding is an added step in bondingenamel surface prior to bonding is an added step in bonding
process which increases the clinical time required for fixedprocess which increases the clinical time required for fixed
appliance placement.appliance placement.
Recently, to overcome this problem, a combined etch primerRecently, to overcome this problem, a combined etch primer
system (transbond-plus) has been introduced.system (transbond-plus) has been introduced.
• It comprises methacrylate phosphoric acid esters.It comprises methacrylate phosphoric acid esters.
• The manufacturer also claims that it can be in applied to a wetThe manufacturer also claims that it can be in applied to a wet
enamel surface and adequate etching and priming in a 3 secondenamel surface and adequate etching and priming in a 3 second
period can be achieved.period can be achieved.

85
ADVANTAGES….ADVANTAGES….
1. Isolation becomes less of a problem1. Isolation becomes less of a problem
2. Enamel preparation becomes less technique2. Enamel preparation becomes less technique
sensitive.sensitive.
3. Self-etch primer achieves adequate bond
strengths when applied to dry enamel surfaces
4. Also the ARI Index showed lower scores with
self etch primer.
This indicated that less time will be required
at the end of treatment removing retained resin
from enamel surfaces.

86
FLUORIDE-CONTAINING SEALANTS ??FLUORIDE-CONTAINING SEALANTS ??
Fluoride containing sealants have been introducedFluoride containing sealants have been introduced
and tried to mainly reduce the Demineralization ofand tried to mainly reduce the Demineralization of
the enamel around the bracket base.the enamel around the bracket base.
Ceen and Gwinnett found that these sealants protectCeen and Gwinnett found that these sealants protect
enamel adjacent to brackets from dissolution andenamel adjacent to brackets from dissolution and
subsurface lesions.subsurface lesions.
Further studies are needed on the clinical merits ofFurther studies are needed on the clinical merits of
these sealants.these sealants.

88
ENAMEL-ADHESIVE RESINENAMEL-ADHESIVE RESIN
INTERFACE…INTERFACE…
It has been documented that the micro mechanicalIt has been documented that the micro mechanical
retention of resin composites to acid-etchedretention of resin composites to acid-etched
enamel may not be due only to formation of resinenamel may not be due only to formation of resin
tags but also to the formation of an interfacial resintags but also to the formation of an interfacial resin
enamel inter diffusion zone within the lateral sitesenamel inter diffusion zone within the lateral sites
of the remaining enamel protuberances.of the remaining enamel protuberances.

89
CLASSIFICATIONCLASSIFICATION
Based upon the polymerization initiationBased upon the polymerization initiation
mechanism, orthodontic adhesives may bemechanism, orthodontic adhesives may be
classified into the following groups:classified into the following groups:
1.Chemically activated1.Chemically activated
Two paste.Two paste.
One paste.One paste.
2.2. Light cured.Light cured.
3. Dual cured3. Dual cured (chemically activated and light cured).(chemically activated and light cured).
4. Thermo cured4. Thermo cured..

90
Ideal requisitesIdeal requisites of bonding system:of bonding system:
• Provide high bond strength to enamel that shouldProvide high bond strength to enamel that should
be present immediately after placement and bebe present immediately after placement and be
permanent.permanent.
• Should have good biocompatibility to dental tissueShould have good biocompatibility to dental tissue
including the pulp.including the pulp.
• Minimize micro leakage at margins of adhesion.Minimize micro leakage at margins of adhesion.

91
• Prevent recurrent caries and marginal staining.Prevent recurrent caries and marginal staining.
• Posses a good shelf life.Posses a good shelf life.
• Be easy to use and minimally technique sensitive.Be easy to use and minimally technique sensitive.
• Compatible with wide range of resins.Compatible with wide range of resins.
• Should not be toxic or sensitizing to the operatorShould not be toxic or sensitizing to the operator
and patient.and patient.

92
COMPOSITIONCOMPOSITION
• Resin matrixResin matrix –– Bis-gma / UrethaneBis-gma / Urethane
dimethacrylate (UDMA) / TEGDMAdimethacrylate (UDMA) / TEGDMA
• FillersFillers –– Quartz, colloidal silica or heavy metalQuartz, colloidal silica or heavy metal
glasses (for radiopacity of fillers, eg. barium,glasses (for radiopacity of fillers, eg. barium,
strontium, zirconium).strontium, zirconium).
• Coupling agentsCoupling agents –– Organosilanes. provide bondOrganosilanes. provide bond
between resin matrix and the fillers. e.g.between resin matrix and the fillers. e.g. γγ--
methacryloxypropyl Tri methoxy silane.methacryloxypropyl Tri methoxy silane.

93
Activator-Initiator systemActivator-Initiator system
(i) Chemically activated resins:(i) Chemically activated resins:
Initiator :– benzoyl peroxideInitiator :– benzoyl peroxide
Activator : n-n-dimethyl-p-toluidine.Activator : n-n-dimethyl-p-toluidine.
(tertiary amine).(tertiary amine).
(ii) Light activated resins:-(ii) Light activated resins:-
Initiator:– camphoroquinoneInitiator:– camphoroquinone
(photoinitiator)(photoinitiator)
Activator:– dimethylaminoethylActivator:– dimethylaminoethyl
methacrylate (amine).methacrylate (amine).

94
• Inhibitors-Inhibitors- Butylated hydroxytoluene. ToButylated hydroxytoluene. To
minimize or prevent spontaneous polymerizationminimize or prevent spontaneous polymerization
of monomers.of monomers.
• Optical modifiers-Optical modifiers- Titanium dioxide andTitanium dioxide and
Aluminium oxide.Aluminium oxide.

95
• Resins containing large coarse quartz or silicaResins containing large coarse quartz or silica
glass particles of various size ( 3 to 20glass particles of various size ( 3 to 20µµm) will bem) will be
abrasion resistant.abrasion resistant.
• Resins containing minute filler particles of uniformResins containing minute filler particles of uniform
size (0.2 to 0.30size (0.2 to 0.30µµm) have a smoother surface thatm) have a smoother surface that
retains less plaque and is more prone to abrasion.retains less plaque and is more prone to abrasion.
• Adhesives with large particle fillers areAdhesives with large particle fillers are
recommended for extra bond strength, but carefulrecommended for extra bond strength, but careful
removal of the excess is mandatory because suchremoval of the excess is mandatory because such
adhesives accumulate plaque more easily than doadhesives accumulate plaque more easily than do
others.others.

96
POLYMERIZATION MECHANISMSPOLYMERIZATION MECHANISMS
1.1. Chemically activated resin:Chemically activated resin:
2 - paste system:-2 - paste system:-
BASE PASTEBASE PASTE
CATALYST PASTECATALYST PASTE
When 2 pastes are spatulated the amine reacts with theWhen 2 pastes are spatulated the amine reacts with the
benzoyl peroxide to form the free radicals, which start thebenzoyl peroxide to form the free radicals, which start the
polymerization.polymerization.
DisadvantagesDisadvantages ::
Air may get incorporated during mixing, reducing theAir may get incorporated during mixing, reducing the
properties.properties.
Working time is limited.Working time is limited.

97
2.2. Light activated resins:Light activated resins:
The first light-activated system using ultravioletThe first light-activated system using ultraviolet
(UV) light was developed as an alternative to(UV) light was developed as an alternative to
self-curing resins. Polymerization time wasself-curing resins. Polymerization time was
rapid.rapid.
DisadvantagesDisadvantages
• Harmful effects of UV rays.Harmful effects of UV rays.
• Bulky unit, difficult to handle.Bulky unit, difficult to handle.

98
VISIBLE LIGHT CURING (VLC)VISIBLE LIGHT CURING (VLC)
Introduced in 1980.Introduced in 1980.
ADVANTAGESADVANTAGES
• Command settingCommand setting
• Extended working timeExtended working time
• Void free.Void free.
DISADVANTAGESDISADVANTAGES
• Light source requiredLight source required
• Affected by operating lightAffected by operating light
• Cures only where sufficient intensity of light isCures only where sufficient intensity of light is
received.received.
• Shrinkage towards light sourceShrinkage towards light source

99
Various light devices………Various light devices………
• Halogen LCU.Halogen LCU.
• High energy laser curing system.High energy laser curing system.
• Plasma arc curing unit (micro-xenon LCU).Plasma arc curing unit (micro-xenon LCU).
• LED curing units (light emitting diodes).LED curing units (light emitting diodes).

100
HALOGEN LCUHALOGEN LCU
• Light source – Tungsten halogen bulb.Light source – Tungsten halogen bulb.
• Wavelength – 400-500nm (blue light).Wavelength – 400-500nm (blue light).
• Thickness of composite cured – 2mm.Thickness of composite cured – 2mm.
• Exposure time – 80-240 seconds (lowExposure time – 80-240 seconds (low
intensity light). 20-60 seconds (highintensity light). 20-60 seconds (high
intensity light)intensity light)
• Elevated pulpal temperature with longerElevated pulpal temperature with longer
curing cycles.curing cycles.
• Bracket failure rate – 48%.Bracket failure rate – 48%.

101
LASER CURING SYSTEMLASER CURING SYSTEM
• Argon lasers introduced in the late 1980s and earlyArgon lasers introduced in the late 1980s and early
1990s are capable of curing in only 10 seconds for1990s are capable of curing in only 10 seconds for
filled resins and 5 seconds for unfilled resins, at afilled resins and 5 seconds for unfilled resins, at a
wavelength of 488nm.wavelength of 488nm.
• Produce greater degree of polymerization than isProduce greater degree of polymerization than is
possible with VLC units.possible with VLC units.

102
PLASMA ARC/MICRO-XENON LCUPLASMA ARC/MICRO-XENON LCU
Permits a high-intensity polymerization of light-Permits a high-intensity polymerization of light-
curing adhesives. Light intensity is 1650curing adhesives. Light intensity is 1650
mw/cm2 which is about 3 times greater thanmw/cm2 which is about 3 times greater than
that of a conventional units.that of a conventional units.
• Wave length – 470nm.Wave length – 470nm.
• A high energy, high pressure ionized gas in theA high energy, high pressure ionized gas in the
presence of an electrical current is used to create apresence of an electrical current is used to create a
light source strong enough to increase the curinglight source strong enough to increase the curing
rate of light-cured adhesives.rate of light-cured adhesives.

103
ADVANTAGESADVANTAGES
• 2 seconds per tooth.2 seconds per tooth.
• immediate bond strength is high and archwiresimmediate bond strength is high and archwires
can be inserted and ligated immediately.can be inserted and ligated immediately.
• High costHigh cost
• Protective eye glasses are necessaryProtective eye glasses are necessary

Light emitting diode curing unitsLight emitting diode curing units
MILLSMILLS –1995–1995
• Instead of hot filament – Halogen bulb.Instead of hot filament – Halogen bulb.
• LED – junction of doped semi conductors.LED – junction of doped semi conductors.
ADVANTAGES:ADVANTAGES:
• Lifetime -10, 000 hrsLifetime -10, 000 hrs
• Requires no filtersRequires no filters
• Resist shock and vibrationResist shock and vibration
• Little power to operateLittle power to operate
• Newer – GALLIUM NITRIDE ( LED )Newer – GALLIUM NITRIDE ( LED )
104

Mills et al ( BJO 1997Mills et al ( BJO 1997 ))
Compared light source containing LED to Halogen units.Compared light source containing LED to Halogen units.
Concluded – LED curing units cured composites toConcluded – LED curing units cured composites to
significantly greater depths when tested at 40 & 60 sec.significantly greater depths when tested at 40 & 60 sec.
• DISADVANTAGESDISADVANTAGES
 Their technology is new to orthodontics, and theTheir technology is new to orthodontics, and the
concept still is evolving.concept still is evolving.
 Their curing time is slower than plasma arc curingTheir curing time is slower than plasma arc curing
lights and some enhanced halogen lights.lights and some enhanced halogen lights. 105

 Their batteries must be recharged.Their batteries must be recharged.
 They cost more than do conventional halogenThey cost more than do conventional halogen
lights.lights.
 They offer a relatively low intensity.They offer a relatively low intensity.
106

107
OTHER ALTERNATIVES TO SELF-OTHER ALTERNATIVES TO SELF-
CURING PASTE- PASTE SYSTEMSCURING PASTE- PASTE SYSTEMS
1.1. NO – MIX ADHESIVES:NO – MIX ADHESIVES:
One adhesive component is applied to theOne adhesive component is applied to the
bracket base while another is applied to thebracket base while another is applied to the
dried etched tooth.dried etched tooth.
After it is precisely positioned, the bracket isAfter it is precisely positioned, the bracket is
pressed firmly into place and curing occurspressed firmly into place and curing occurs
usually within 30 to 60 seconds.usually within 30 to 60 seconds.
Liquid activators of this system are definitelyLiquid activators of this system are definitely
toxic, allergic reactions have been reported intoxic, allergic reactions have been reported in
patients, dental assistants and doctors.patients, dental assistants and doctors.

108
2.2. GLASS IONOMER CEMENTSGLASS IONOMER CEMENTS::
((Introduced in 1972)Introduced in 1972)
Bond chemically to enamel and dentin, as well asBond chemically to enamel and dentin, as well as
to stainless steel, being able to release fluorideto stainless steel, being able to release fluoride
ions for caries protection.ions for caries protection.
Have unreliable and inferior adhesive propertiesHave unreliable and inferior adhesive properties
compared to composite resins.compared to composite resins.
COMPOSITION:COMPOSITION:
• Powder – acid-soluble calcium fluoroaluminosilicatePowder – acid-soluble calcium fluoroaluminosilicate
glass.glass.
• Liquid – polyacrylic acid in the form of copolymer,Liquid – polyacrylic acid in the form of copolymer,
Iticonic acid, maleic acid and tricarboxylic acid +Iticonic acid, maleic acid and tricarboxylic acid +
tartaric acid (improves handling characteristics andtartaric acid (improves handling characteristics and
increases the working time)+water (reaction mediumincreases the working time)+water (reaction medium
initially and for hydration of matrix later).initially and for hydration of matrix later).

109
Mechanism of Adhesion…Mechanism of Adhesion…
• Chelation of carboxyl groups of the poly acids with theChelation of carboxyl groups of the poly acids with the
calcium in the apatite of the enamel and dentin.calcium in the apatite of the enamel and dentin.
• Bond to enamel is higher due to greater inorganicBond to enamel is higher due to greater inorganic
content of enamel.content of enamel.
3.COMPOMER3.COMPOMER
• Light-cured glass ionomer.Light-cured glass ionomer.
• Combination of both addition polymerization andCombination of both addition polymerization and
acid-base reactivity, yielding a so called hybridacid-base reactivity, yielding a so called hybrid
material.material.

110
4.CYANOACRYLATES4.CYANOACRYLATES
• In 1991, a commercially available ethyl-In 1991, a commercially available ethyl-
cyanoacrylate material was tested as ancyanoacrylate material was tested as an
orthodontic bracket adhesive and found to haveorthodontic bracket adhesive and found to have
significantly higher tensile strength than asignificantly higher tensile strength than a
conventional composite.conventional composite.
• After 50, 100 and 150 days in a saline solution, theAfter 50, 100 and 150 days in a saline solution, the
cyanoacrylate showed no decline in tensilecyanoacrylate showed no decline in tensile
strength.strength.
• Because polymerization starts only in the presenceBecause polymerization starts only in the presence
of moisture and pressure, the clinical procedureof moisture and pressure, the clinical procedure
differs from that of conventional adhesives.differs from that of conventional adhesives.

111
• Surfaces to be bonded should be as close togetherSurfaces to be bonded should be as close together
as possible as the material cannot fill spaces oras possible as the material cannot fill spaces or
gaps, that is why a bracket base with deep mesh orgaps, that is why a bracket base with deep mesh or
under cuts will have lower bond strength.under cuts will have lower bond strength.
• No reports of allergy or biocompatibility problems.No reports of allergy or biocompatibility problems.
• Clinical experience indicates that cyanoacrylateClinical experience indicates that cyanoacrylate
does not work well on polycarbonate brackets withdoes not work well on polycarbonate brackets with
enlarged retention surfaces.enlarged retention surfaces.

112
5. FIBER – REINFORCED COMPOSITES5. FIBER – REINFORCED COMPOSITES
• It is a partially polymerized fiber-matrix complexIt is a partially polymerized fiber-matrix complex
that is later fully polymerized in a clinical setting.that is later fully polymerized in a clinical setting.
PROCEDUREPROCEDURE
• The tooth is prepared for bonding with polishingThe tooth is prepared for bonding with polishing
and etching.and etching.
• The FRC is placed in position and contoured toThe FRC is placed in position and contoured to
the tooth, then light – cured.the tooth, then light – cured.
• A low-viscosity adhesive can be added to form aA low-viscosity adhesive can be added to form a
protective layer over the bar.protective layer over the bar.

113
APC (adhesive pre-coated) BRACKETSAPC (adhesive pre-coated) BRACKETS
• Brackets preloaded with light-cured paste isBrackets preloaded with light-cured paste is
applied to the teeth and pressed firmly in place inapplied to the teeth and pressed firmly in place in
their approximate location.their approximate location.
• After adjusting the brackets and removing excessAfter adjusting the brackets and removing excess
adhesive, the operator tacks the bracket in placeadhesive, the operator tacks the bracket in place
with a 5 second exposure to the curing light.with a 5 second exposure to the curing light.

114
Consistent quality and quantity of adhesive.Consistent quality and quantity of adhesive.
Reduced wastage of material during bonding.Reduced wastage of material during bonding.
Easier clean-up following bonding.Easier clean-up following bonding.
Improved asepsis.Improved asepsis.
DISADVANTAGES:DISADVANTAGES:
Significantly lower shear bond strength than theSignificantly lower shear bond strength than the
uncoated brackets.uncoated brackets.
[[Possible explanation by bishara et al is thatPossible explanation by bishara et al is that
increased viscosity of the adhesive used on the apcincreased viscosity of the adhesive used on the apc
brackets, when combined with the mesh retentionbrackets, when combined with the mesh retention
mechanism incorporated in the metal bracket base,mechanism incorporated in the metal bracket base,
seems to significantly lower the shear bondseems to significantly lower the shear bond
strength].strength].

115
Bearn et alBearn et al reported no significant differencesreported no significant differences
in bond strength.in bond strength.
Wang & MengWang & Meng reported higher bond strengthsreported higher bond strengths
when light-curing was increased from 20 to 40when light-curing was increased from 20 to 40
secondsseconds
There fore it appears that the duration of lightThere fore it appears that the duration of light
exposure represents a clinical factor, whichexposure represents a clinical factor, which
can significantly affect the bond strength ofcan significantly affect the bond strength of
APC brackets.APC brackets.

116
MOISTURE ACTIVE ADHESIVESMOISTURE ACTIVE ADHESIVES
These require presence of moisture forThese require presence of moisture for
polymerization. Available as pastes and needs nopolymerization. Available as pastes and needs no
bonding agent..bonding agent..
EG :- Smart Bond.EG :- Smart Bond.
Manufacturer emphasizes that contamination withManufacturer emphasizes that contamination with
saliva must be avoided, because this will disturbsaliva must be avoided, because this will disturb
the setting process. But the wet environment in thethe setting process. But the wet environment in the
oral cavity is mostly due to salivary flow ratheroral cavity is mostly due to salivary flow rather
than to the presence of moisture. This may be anthan to the presence of moisture. This may be an
important area for future investigations…important area for future investigations…

117
ORTHODONTIC BONDINGORTHODONTIC BONDING
TECHNIQUESTECHNIQUES
• DIRECT BONDINGDIRECT BONDING
• INDIRECT BONDINGINDIRECT BONDING
Direct bonding:Direct bonding:
Refers to the direct attachment of orthodonticRefers to the direct attachment of orthodontic
appliances to etched teeth using chemically andappliances to etched teeth using chemically and
light-cured adhesives.light-cured adhesives.

118
• Easier.Easier.
• Faster.Faster.
• Less expensive.Less expensive.
• Chair side time is increasedChair side time is increased
• Placement of bracket is not as accurate asPlacement of bracket is not as accurate as
indirect bondingindirect bonding

119
Indirect bonding:Indirect bonding:
Introduced in 1972. Brackets are first positionedIntroduced in 1972. Brackets are first positioned
on study casts with a water-soluble adhesive andon study casts with a water-soluble adhesive and
then transferred to the mouth with a customthen transferred to the mouth with a custom
tray.tray.
Accuracy of placement of attachments.Accuracy of placement of attachments.
Reduced chair side time.Reduced chair side time.
Patient comfort.Patient comfort.
Easier cleanup during the bonding andEasier cleanup during the bonding and
debonding procedures.debonding procedures.
Easier debonding of brackets.Easier debonding of brackets.

120
• Laboratory time required setting brackets andLaboratory time required setting brackets and
making the transfer tray in addition to the chairmaking the transfer tray in addition to the chair
side time.side time.
• Technique sensitive.Technique sensitive.
• Failure requires additional time to rebond.Failure requires additional time to rebond.

121
DIRECT BRACKET BONDINGDIRECT BRACKET BONDING
PROCEDUREPROCEDURE
STEPS INVOLVED ARE:STEPS INVOLVED ARE:
– Transfer,Transfer,
– Positioning,Positioning,
– Fitting ,Fitting ,
– Removal of excess.Removal of excess.

122
TRANSFER:TRANSFER:
Grip the bracket with a pair of cotton pliers or aGrip the bracket with a pair of cotton pliers or a
reverse action tweezer.reverse action tweezer.
Apply the adhesive to the back of the bondingApply the adhesive to the back of the bonding
base.base.
Place the bracket immediately on the toothPlace the bracket immediately on the tooth
close to its correct position.close to its correct position.

123
POSITIONING:POSITIONING:
Position the brackets mesiodistally andPosition the brackets mesiodistally and
incisogingivally and angulate them using aincisogingivally and angulate them using a
placement scaler.placement scaler.
This scaler allows visualization of the bracket slotThis scaler allows visualization of the bracket slot
relative to the incisal edge and long axis of therelative to the incisal edge and long axis of the
teeth.teeth.
A mouth mirror will aid in horizontal positioning,A mouth mirror will aid in horizontal positioning,
particularly on rotated premolars.particularly on rotated premolars.
Measuring devices or height guides on the bracketMeasuring devices or height guides on the bracket
themselves enhance vertical positioning.themselves enhance vertical positioning.

Use of bracket positioning gauge:Use of bracket positioning gauge:
124

• Place bracket on the tooth,Place bracket on the tooth,
ensuring that the colored dot onensuring that the colored dot on
the bracket is positioned disto-the bracket is positioned disto-
gingivally.gingivally.
• Upper incisors: centered mesio-Upper incisors: centered mesio-
distally, over mid developmentdistally, over mid development
ridge,4mm from incisal edge, slotridge,4mm from incisal edge, slot
parallel to incisal and occlusalparallel to incisal and occlusal
plane.plane.
• Canine: centered over midCanine: centered over mid
development ridge, but this willdevelopment ridge, but this will
be slightly mesial to the midpointbe slightly mesial to the midpoint
of the tooth,4.5mm from cusp tip,of the tooth,4.5mm from cusp tip,
slot is parallel plane to theslot is parallel plane to the
occlusal.occlusal.
126
4.5
3.5

127
The bracket placement gauge is used
differently in different areas of the mouth.
In the Incisor regions, the gauge is placed
at 90° to the labial surface.
In the Canine and Premolar , the
gauge is placed parallel with the occlusal
surface.
In the Molar, the gauge is placed parallel
with individual molar.
Horizontal errors: Placing brackets too
mesially or distally of the vertical long axis
of the crown results in improper rotation.
Vertical errors: lead to intrusion and
extrusion
Brackets placed too incisally or gingivally .
Rotation: Excess resin material if used lead
to incomplete seating of the bracket.

128
FITTING:FITTING:
The scaler is turned, and with one point contact withThe scaler is turned, and with one point contact with
the bracket, it is pushed firmly toward the tooththe bracket, it is pushed firmly toward the tooth
surface.surface.
TIGHT FIT RESULTS INTIGHT FIT RESULTS IN::
– Good bond strengthGood bond strength
– Little material to remove on debondingLittle material to remove on debonding
– Reduced slide when excess material extrudesReduced slide when excess material extrudes
peripherally.peripherally.

129
REMOVAL OF EXCESS ADHESIVEREMOVAL OF EXCESS ADHESIVE
Remove excess adhesive [especially along theRemove excess adhesive [especially along the
gingival margin] with the scaler before thegingival margin] with the scaler before the
adhesive has set or with burs after setting (toadhesive has set or with burs after setting (to
avoid disturbing the bracket position).avoid disturbing the bracket position).
Excess removal prevents or minimizes gingivalExcess removal prevents or minimizes gingival
irritation and plaque buildup around theirritation and plaque buildup around the
periphery of the bonding base.periphery of the bonding base.
Reduces periodontal damage and the possibility ofReduces periodontal damage and the possibility of
decalcification.decalcification.

130
Improves esthetics – by providing a neater andImproves esthetics – by providing a neater and
cleaner appearance and also by eliminatingcleaner appearance and also by eliminating
exposed adhesive which might becomeexposed adhesive which might become
discolored in the oral environment.discolored in the oral environment.
Clinically significant gingival hyperplasia andClinically significant gingival hyperplasia and
inflammation rapidly occur when excessinflammation rapidly occur when excess
adhesive comes close to the gingival and is notadhesive comes close to the gingival and is not
properly removed.properly removed.

131
BONDING TO ARTIFICIAL TOOTHBONDING TO ARTIFICIAL TOOTH
SURFACESSURFACES
1. CROWNS AND RESTORATIONS:1. CROWNS AND RESTORATIONS:
Microetcher uses 50 µm white or 90
µm tan aluminium oxide particles at
approximately 7 kg/cm2 pressure for
bonding to different artificial
surfaces. It acts by preparing micro
retentive surfaces in metals .

132
2.2. PORCELAIN:PORCELAIN:
• In 1986,In 1986, Wood etWood et al showed that roughening theal showed that roughening the
porcelain surface, adding a porcelain primer, andporcelain surface, adding a porcelain primer, and
using a highly filled adhesive resin when bondingusing a highly filled adhesive resin when bonding
to glazed porcelain added progressively to bondto glazed porcelain added progressively to bond
strengths.strengths.
• Porcelain etchantPorcelain etchant→→9.6%hydrofluoric (HF) acid in9.6%hydrofluoric (HF) acid in
gel from.gel from.
• Application timeApplication time →→ 2 to 4 minutes. the etchant2 to 4 minutes. the etchant
creates micro porosities on the porcelain surfacecreates micro porosities on the porcelain surface
that achieves a mechanical interlock with thethat achieves a mechanical interlock with the
composite resin.composite resin.
• Sandblasting and silane (scotch prime) producedSandblasting and silane (scotch prime) produced
equally strong bonds.equally strong bonds.

134
3. AMALGAM :3. AMALGAM :
• Sandblast the amalgam filling with 50Sandblast the amalgam filling with 50 µµmm
aluminium oxide for 3 seconds.aluminium oxide for 3 seconds.
• Apply a uniform coat of 4-META PrimersApply a uniform coat of 4-META Primers
(reliance metal primer) and wait for 30 seconds.(reliance metal primer) and wait for 30 seconds.
• Apply sealant and bond with composite resin.Apply sealant and bond with composite resin.
Make sure the bonded attachment is not inMake sure the bonded attachment is not in
occlusion with antagonists.occlusion with antagonists.
• Amalgam surfaces can easily be re polished withAmalgam surfaces can easily be re polished with
rubber cups and points after debonding.rubber cups and points after debonding.

Improved techniques for bonding toImproved techniques for bonding to amalgamamalgam
restorations may involve-restorations may involve-
• (1) Modification of the metal surface(1) Modification of the metal surface
(sandblasting, diamond bur roughening)(sandblasting, diamond bur roughening)
• (2) The use of intermediate resins that improve(2) The use of intermediate resins that improve
bond strengths (e.g., All-Bond 2)bond strengths (e.g., All-Bond 2)
• (3) Newer adhesive resins that bond chemically to(3) Newer adhesive resins that bond chemically to
non-precious and precious metals. (e.g., 4-non-precious and precious metals. (e.g., 4-
methacryloxyethyl trimellitate anhydrid [4-META]methacryloxyethyl trimellitate anhydrid [4-META]
resins.resins.
135

137
4. GOLD :4. GOLD :
• Sandblasting, electrolytic tin-plating or plating withSandblasting, electrolytic tin-plating or plating with
gallium-tin solution (alloy).gallium-tin solution (alloy).
• The use of several different types of intermediateThe use of several different types of intermediate
primers, and new adhesives that bond chemically toprimers, and new adhesives that bond chemically to
precious metals (Superbond C&B, Panavia Ex and 21) allprecious metals (Superbond C&B, Panavia Ex and 21) all
have been reported to improve bonding to gold inhave been reported to improve bonding to gold in
laboratory settings.laboratory settings.
• Present clinical experiments include the use of new one-Present clinical experiments include the use of new one-
component primer based on the VTD adhesive monomercomponent primer based on the VTD adhesive monomer
[vinylbenzyl-n-propyl amino triazine-dithiol] and 4[vinylbenzyl-n-propyl amino triazine-dithiol] and 4
META adhesive resin.META adhesive resin.

138
5. COMPOSITE RESTORATIVES5. COMPOSITE RESTORATIVES
• The bond strength obtained with the addition ofThe bond strength obtained with the addition of
new composite to mature composite isnew composite to mature composite is
substantially less than the cohesive strength of thesubstantially less than the cohesive strength of the
material.material.
• However, brackets bonded to fresh, roughenedHowever, brackets bonded to fresh, roughened
surface of old composite restorations appear to besurface of old composite restorations appear to be
clinically successful in most instances. It isclinically successful in most instances. It is
probably advantageous to use an intermediateprobably advantageous to use an intermediate
primer as well.primer as well.

• Bonding brackets to fluorosed teeth remains aBonding brackets to fluorosed teeth remains a
notable clinical challenge because of frequentnotable clinical challenge because of frequent
bracket failure at the compromised enamel interface.bracket failure at the compromised enamel interface.
• Features:Features:
– Increased porosity or hypomineralization ofIncreased porosity or hypomineralization of
subsurface enamel.subsurface enamel.
– Irregular prism patterns, cracks and fissuresIrregular prism patterns, cracks and fissures
139
BONDING TO FLOUROSED TEETHBONDING TO FLOUROSED TEETH

• These abnormalities result in marked decrease inThese abnormalities result in marked decrease in
microhardness which adversely affects themicrohardness which adversely affects the
mechanical locking of an adhesive to the enamelmechanical locking of an adhesive to the enamel
surface.surface.
• Enamel with a high fluoride content is moreEnamel with a high fluoride content is more
resistant to etching and results in fewerresistant to etching and results in fewer
irregularities.irregularities.
• It has been suggested that this may result in aIt has been suggested that this may result in a
weaker resin bond and, consequently, poorweaker resin bond and, consequently, poor
retention of orthodontic brackets.retention of orthodontic brackets.
• Use ofUse of adhesion promoteradhesion promoter to severely fluorosedto severely fluorosed
teeth, will negate the need for microabrasion.teeth, will negate the need for microabrasion.
140

141
DEBONDINGDEBONDING
OBJECTIVE:OBJECTIVE:
• To remove the attachment and all the adhesiveTo remove the attachment and all the adhesive
resin from the toothresin from the tooth
• Restore the surface as closely as possible to itsRestore the surface as closely as possible to its
pretreatment condition with-out inducingpretreatment condition with-out inducing
iatrogenic damage.iatrogenic damage.
CLINICAL PROCEDURESCLINICAL PROCEDURES
• Bracket removal.Bracket removal.
• Removal of residual adhesive.Removal of residual adhesive.

142
1. CERAMIC BRACKETS:1. CERAMIC BRACKETS:
• The first method employs pistol grip debondingThe first method employs pistol grip debonding
Plier that is positioned over the brackets with itsPlier that is positioned over the brackets with its
jaws aligned horizontally over the bracket in anjaws aligned horizontally over the bracket in an
occlusogingival direction over the tie wings.occlusogingival direction over the tie wings.
Debonding of the bracket occurs when the handlesDebonding of the bracket occurs when the handles
are squeezed, the jaws contact the tie wings, andare squeezed, the jaws contact the tie wings, and
the bracket is pulled away from the tooth surface.the bracket is pulled away from the tooth surface.
Bracket failure often occurs.Bracket failure often occurs.

143
• The second method uses a delaminating technique,The second method uses a delaminating technique,
Delamination occurs when a sharp edged instrument isDelamination occurs when a sharp edged instrument is
placed at the enamel- adhesive interface. Forceplaced at the enamel- adhesive interface. Force
application (usually with a 346 Plier) produces aapplication (usually with a 346 Plier) produces a
peeling or wedge effect to debond the bracket.peeling or wedge effect to debond the bracket.
• The third method employs a special tool that producesThe third method employs a special tool that produces
a torsional or wrenching force at the base of thea torsional or wrenching force at the base of the
bracket.bracket.
The delaminating method appears to be the leastThe delaminating method appears to be the least
expensive and safest of the 3 methods of mechanicalexpensive and safest of the 3 methods of mechanical
debonding.debonding.

144
• A new ceramic bracket introduced in theA new ceramic bracket introduced in the
market allows easier debonding via a Verticalmarket allows easier debonding via a Vertical
scribe line placed in the base of the appliance.scribe line placed in the base of the appliance.
Weingart Pliers are used to apply forces in aWeingart Pliers are used to apply forces in a
mesiodistal grip of the bracket ears, allowingmesiodistal grip of the bracket ears, allowing
the bracket to fold on the vertical line.the bracket to fold on the vertical line.

145
2. METAL BRACKETS2. METAL BRACKETS
• The first method employsThe first method employs utilityutility plierspliers like thelike the
Wiengart or Howe pliers to squeeze the mesialWiengart or Howe pliers to squeeze the mesial
and distal wings of the brackets. This techniqueand distal wings of the brackets. This technique
exerts a pinch-and-peel effect on the bracketsexerts a pinch-and-peel effect on the brackets
and debonds the attachment with a large amountand debonds the attachment with a large amount
of the resin left on the tooth surface, which canof the resin left on the tooth surface, which can
be removed using a finishing bur or scaler.be removed using a finishing bur or scaler.

146
• The second method employs a shearing forceThe second method employs a shearing force
delivered by thedelivered by the sharp-edged bladessharp-edged blades of theof the
debonding pliers ( 095 S Orthopli Bracketdebonding pliers ( 095 S Orthopli Bracket
Removing Plier ) at the enamel-composite or theRemoving Plier ) at the enamel-composite or the
bracket-composite interface. The bracket isbracket-composite interface. The bracket is
debonded, leaving minimal amounts of resin on thedebonded, leaving minimal amounts of resin on the
tooth surface. A finishing bur or scaler can removetooth surface. A finishing bur or scaler can remove
any remaining resin residue on the debondedany remaining resin residue on the debonded
tooth.tooth.

147
• The third method uses specially designed pliersThe third method uses specially designed pliers
that exertthat exert tensile-typetensile-type forceforce that lifts the bracketthat lifts the bracket
off the enamel surface by engaging a wing of theoff the enamel surface by engaging a wing of the
bracket and braces the beak against the tooth.bracket and braces the beak against the tooth.
This technique leaves almost all the resin on theThis technique leaves almost all the resin on the
tooth surface with minimal bracket distortion.tooth surface with minimal bracket distortion.
The remaining resin can be cleaned using aThe remaining resin can be cleaned using a
finishing bur or scaler.finishing bur or scaler.

148
ALTERNATIVE METHODS OFALTERNATIVE METHODS OF
DEBONDINGDEBONDING
• An ultrasonic scaler or an electrothermal deAn ultrasonic scaler or an electrothermal de
bonderbonder. The tip of the electrothermal de bonder. The tip of the electrothermal de bonder
engages the slot running occlusogingivally in theengages the slot running occlusogingivally in the
bracket and with a mild torsional force, detachesbracket and with a mild torsional force, detaches
the bracket from the tooth surface.the bracket from the tooth surface.

149
• Thermal debondingThermal debonding and the use ofand the use of laserslasers havehave
the potential to be less traumatic and less riskythe potential to be less traumatic and less risky
for enamel damage, but these techniques arefor enamel damage, but these techniques are
still at an introductory stage.still at an introductory stage.
• Also the use of lasers will be very expensive.Also the use of lasers will be very expensive.

150
REMOVAL OF RESIDUAL ADHESIVEREMOVAL OF RESIDUAL ADHESIVE
ACCOMPLISHED BYACCOMPLISHED BY
(1) Scraping with a very sharp band or bond-(1) Scraping with a very sharp band or bond-
removing pliers or with a scaler .removing pliers or with a scaler .
(2) Using a suitable bur and contra-angle.(2) Using a suitable bur and contra-angle.

151
• Clinical experience and laboratory studiesClinical experience and laboratory studies
indicate that approximatelyindicate that approximately 30,000 rpm30,000 rpm isis
optimal for rapid adhesive removal withoutoptimal for rapid adhesive removal without
enamel damage. Light painting movementsenamel damage. Light painting movements
of the bur should be used so as not to scratchof the bur should be used so as not to scratch
the enamel. Water-cooling should not bethe enamel. Water-cooling should not be
employed when the last remnants areemployed when the last remnants are
removed because water lessens the contrastremoved because water lessens the contrast
with enamel.with enamel.

152
• Higher speeds than 30,000 rpm using fine flutedHigher speeds than 30,000 rpm using fine fluted
TC burs may be useful for bulk removal but are notTC burs may be useful for bulk removal but are not
indicated closer to the enamel because of the riskindicated closer to the enamel because of the risk
of marring the surface.of marring the surface.
• When all adhesive has been removed, the toothWhen all adhesive has been removed, the tooth
surface may be polished with pumice (or asurface may be polished with pumice (or a
commercial prophylaxis paste) in a routinecommercial prophylaxis paste) in a routine
manner.manner.

153
AMOUNT OF ENAMEL LOST INAMOUNT OF ENAMEL LOST IN
DEBONDINGDEBONDING
• Initial prophylaxis with bristle brush - 10Initial prophylaxis with bristle brush - 10µµm ofm of
enamelenamel
• About 5About 5µµm may be lost when a rubber cup is used.m may be lost when a rubber cup is used.
• Cleanup of unfilled resins with hand instruments- 5Cleanup of unfilled resins with hand instruments- 5
to 8to 8 µµm of enamel.m of enamel.
• Removal of filled resin with rotary instruments-10Removal of filled resin with rotary instruments-10
to 25to 25 µµm.m.
• Pus and WayPus and Way found a high-speed bur and greenfound a high-speed bur and green
rubber wheel removes around 20rubber wheel removes around 20 µµm, and a low-m, and a low-
speed TC bur removes around 10speed TC bur removes around 10 µµm of enamel.m of enamel.

154
INFLUENCE ON ENAMEL BY DIFFERENTINFLUENCE ON ENAMEL BY DIFFERENT
DEBONDING INSTRUMENTSDEBONDING INSTRUMENTS
• Diamond instruments were unacceptable, evenDiamond instruments were unacceptable, even
fine diamond burs produced coarse scratches andfine diamond burs produced coarse scratches and
gave a deeply marred appearance.gave a deeply marred appearance.
• Medium sandpaper disks and a green rubberMedium sandpaper disks and a green rubber
wheel produced similar scratches that could not bewheel produced similar scratches that could not be
polished awaypolished away
• Fine sandpaper disks produced several markedFine sandpaper disks produced several marked
and some even deeper scratches.and some even deeper scratches.

155
• Plain cut and spiral fluted TC burs operated atPlain cut and spiral fluted TC burs operated at
about 25,000 rpm were the only instruments thatabout 25,000 rpm were the only instruments that
provided the satisfactory surface appearance.provided the satisfactory surface appearance.
• None of the instruments tested left the toothNone of the instruments tested left the tooth
surface with its perikymata intact.surface with its perikymata intact.

156
ENAMEL TEAROUTSENAMEL TEAROUTS
• They may be related to the type of filler particles inThey may be related to the type of filler particles in
the adhesive resin used for bonding and to thethe adhesive resin used for bonding and to the
location of bond breakage. The macro fillers createlocation of bond breakage. The macro fillers create
a more natural break point in the enamel-adhesivea more natural break point in the enamel-adhesive
interface than at bracket-adhesive.interface than at bracket-adhesive.
• Ceramic brackets using chemical retention appearCeramic brackets using chemical retention appear
to cause enamel damage more often than thoseto cause enamel damage more often than those
using mechanical retention. This damage occursusing mechanical retention. This damage occurs
probably because the location of the bondprobably because the location of the bond
breakage is at the enamel-adhesive rather than atbreakage is at the enamel-adhesive rather than at
the adhesive-bracket interface.the adhesive-bracket interface.

157
CLINICAL IMPLICATION OFCLINICAL IMPLICATION OF
ENAMEL TEAROUT……….ENAMEL TEAROUT……….
Use brackets that have mechanical retention andUse brackets that have mechanical retention and
debonding instruments and techniques thatdebonding instruments and techniques that
primarily leave all or the majority of compositeprimarily leave all or the majority of composite
on the tooth.on the tooth.
Avoid scraping away adhesive remnants withAvoid scraping away adhesive remnants with
hand instruments.hand instruments.

158
ADHESIVE REMNANT WEARADHESIVE REMNANT WEAR
• Frequently, adhesive has been found on the toothFrequently, adhesive has been found on the tooth
surface, even after attempts to remove it withsurface, even after attempts to remove it with
mechanical instruments.mechanical instruments.
• In some instances adhesive may left on purposeIn some instances adhesive may left on purpose
because the operator expects that it will wear off withbecause the operator expects that it will wear off with
time!time!
• Adhesive wear depends on the size, type, and amountAdhesive wear depends on the size, type, and amount
of reinforcing fillers in the adhesive. Extremely thinof reinforcing fillers in the adhesive. Extremely thin
films of adhesive may not be of esthetic or otherfilms of adhesive may not be of esthetic or other
concern. It may even be advantageous to seal surfaceconcern. It may even be advantageous to seal surface
irregularities such as pits and grooves to protectirregularities such as pits and grooves to protect
against demineralization..against demineralization..

159
REVERSAL OFREVERSAL OF
DECALCIFICATIONDECALCIFICATION
FLUORIDE ADMINISTRATION:FLUORIDE ADMINISTRATION:
Daily rinsing with diluteDaily rinsing with dilute (0.05%) sodium fluoride(0.05%) sodium fluoride
solution throughout the periods of treatment andsolution throughout the periods of treatment and
retention, plus regular use of a fluoride dentifrice,retention, plus regular use of a fluoride dentifrice,
painting a fluoride varnish or new effective anticariouspainting a fluoride varnish or new effective anticarious
agents such as titanium tetra fluorideagents such as titanium tetra fluoride (TiF4)(TiF4) overover
caries- susceptible sites at each visit.caries- susceptible sites at each visit.

Bonding in orthodontics

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