Bonding (2)

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.
www.indiandentalacademy.com

HISTORYHISTORY
The introduction of Acid etch Bonding techniqueThe introduction of Acid etch Bonding technique
has led to dramatic changes in the practice ofhas led to dramatic changes in the practice of
orthodontics.orthodontics.
• 1950 – Newman used 40%-50% phosphoric acid1950 – Newman used 40%-50% phosphoric acid
and Epoxy type resin.and Epoxy type resin.
• 1955 – Buonocore demonstrated the increased1955 – Buonocore demonstrated the increased
adhesion produced by acid pretreatment, usingadhesion produced by acid pretreatment, using
85% phosphoric acid.85% phosphoric acid.
• 1965 – Retief described an epoxy resin system to1965 – Retief described an epoxy resin system to
withstand orthodontic forces.withstand orthodontic forces.

•1968 – Smith introduced zinc poly acrylate1968 – Smith introduced zinc poly acrylate
(carboxylate) for bonding.(carboxylate) for bonding.
•1970 – Miura et al described an acrylic resin1970 – Miura et al described an acrylic resin
(Orthomite), using a modified trialkyl borane(Orthomite), using a modified trialkyl borane
catalyst, that proved to be successful in bondingcatalyst, that proved to be successful in bonding
plastic brackets.plastic brackets.
•The most widely used resin, commonly referred toThe most widely used resin, commonly referred to
as Bowens resin or bis-GMA, was introduced toas Bowens resin or bis-GMA, was introduced to
improve bond strength and increase dimensionalimprove bond strength and increase dimensional
stability by cross linking.stability by cross linking.
cont…

• 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.
cont…

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.

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.

cont….cont….
• 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.

• 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.
cont….

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.www.indiandentalacademy.com

cont…cont…
..
• 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.

STEPS INVOLVEDSTEPS INVOLVED
• CLEANING.CLEANING.
• ENAMEL CONDITIONING.ENAMEL CONDITIONING.
• SEALING.SEALING.
• BONDING.BONDING.

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.

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.

Reisner et al foundReisner et al found more consistent resultsmore consistent results
when buccal tooth surfaces were lightlywhen buccal tooth surfaces were lightly
abraded with TC burabraded with TC bur (#1172) at slow speed(#1172) at slow speed
(25000rpm) than when surfaces were pumiced(25000rpm) than when surfaces were pumiced
for ten seconds before acid etching.for ten seconds before acid etching.

EFFECT OF PUMICE PROPHYLAXISEFFECT OF PUMICE PROPHYLAXIS
ON THE BOND STRENGTH OFON THE BOND STRENGTH OF
ORTHODONTIC BRACKETSORTHODONTIC BRACKETS
The purpose of the study was to determineThe purpose of the study was to determine
whether pumice prophylaxis, performedwhether pumice prophylaxis, performed
before acid etching, enhances the bondbefore acid etching, enhances the bond
strength and retention rate of orthodonticstrength and retention rate of orthodontic
brackets.brackets.
(1998 AJO-DO), Volume 1997 Jun. (599 - 605) Steven J. Lindauer,
DMD, MDSc, Henry Brown...

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.

FLUORIDE INCORPORATED PUMICEFLUORIDE INCORPORATED PUMICE
For the purpose of reducing carious lesions inFor the purpose of reducing carious lesions in
bonded teeth, studies were conducted afterbonded teeth, studies were conducted after
fluoride was incorporated in pumicefluoride was incorporated 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

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.

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 Beunocore (1955)Dr. Michael Beunocore (1955)
introduced acid etching – Usedintroduced acid etching – Used
85% Ortho phosphoric acid.85% Ortho phosphoric acid.

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

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

Enamel bonding system basically consists of anEnamel bonding system basically consists of an
unfilled liquid and acrylic monomer which wetsunfilled liquid and acrylic monomer which wets
the high energy surface and is drawn into thethe high energy surface and is drawn into the
micro porosities created by capillary action.micro porosities created 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.

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 differenceDifferent etching patterns may be due to difference
in chemical composition and crystallinein chemical composition and crystalline
orientation. Variations may be seen from site toorientation. Variations may be seen from site to
site or from tooth to tooth. On etching , Glisteningsite or from tooth to tooth. On etching , Glistening
enamel turns dull and appears “Frosty White”.enamel turns dull and appears “Frosty White”.

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

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

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.

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.

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. www.indiandentalacademy.com

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.

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)

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.

EFFECT OF ACID ETCHING DEPENDSEFFECT OF ACID ETCHING DEPENDS
ON SEVERAL PARAMETERS SUCHON SEVERAL PARAMETERS SUCH
AS: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. Etchant shouldThe way in which etching is activated. Etchant should
always be added in dabbing action. It should not bealways be added in dabbing action. It should not be
applied in rubbing action because rubbing may fractureapplied in rubbing action because rubbing may fracture
the thin enamel rods, thereby reducing the valley depths,the thin enamel rods, thereby reducing the valley depths,
irregularities and obliterating them with fractured enamelirregularities and obliterating them with fractured enamel
pieces.pieces.

• 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.
cont…

EFFECTS OF ACID ETCHING ONEFFECTS OF ACID ETCHING ON
THE ENAMEL SURFACE:THE ENAMEL SURFACE:
35 – 50% Phosphoric acid applied on tooth enamel35 – 50% Phosphoric acid applied on tooth enamel
for 60 sec will render the following effects andfor 60 sec will render the following effects and
changes:changes:
• It will etch the enamel substance with preferentialIt will etch the enamel substance with preferential
dissolution of inter prismatic enamel first,dissolution of inter prismatic enamel first,
followed by the tops of prisms themselves. Thefollowed by the tops of prisms themselves. The
least dissolvable are the sides of prisms.least dissolvable are the sides of prisms.
• Surface area is increased to 2000 times of itsSurface area is increased to 2000 times of its
original un etched surface.original un etched surface.
• It will create valleys and depressions . EnamelIt will create valleys and depressions . Enamel
surface will be irregular at an average depth of 25surface will be irregular at an average depth of 25
µm. (Valleys are places of inter prismatic enamel –µm. (Valleys are places of inter prismatic enamel –
top of prisms will have circumscribed depressionstop of prisms will have circumscribed depressions))

• 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.

• 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.

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 adhesiveprecipitates 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.

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.

B) Etching Time: (15 sec)B) Etching Time: (15 sec)
Glaspole and Ericcson (1986) Tested the effectsGlaspole and Ericcson (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.

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.

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.

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.

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.

• 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.

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.

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

LASERSLASERS
(JADA Feb 2004)(JADA Feb 2004)
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

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

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.

Comparison Of Acid Gel ToComparison Of Acid Gel To
Solution:Solution:
No significant difference in the surface irregularitiesNo significant difference in the surface irregularities
of etch pattern of a gel and a soln.of etch pattern of a gel and a soln.
Brannstrom et al 1982 –Brannstrom et al 1982 –
• No sig. diff. between etching effect of 50%No sig. diff. between etching effect of 50%
phosphoric acid gel and 37% solution.phosphoric acid gel and 37% solution.
• Gel gives better control than a soln. while etchingGel gives better control than a soln. while etching
several teeth at the same time or while etchingseveral teeth at the same time or while etching
partially eruptd teeth or difficult to access areas.partially eruptd teeth or difficult to access areas.

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.

Another School Of Thought: Incorporation of fluoride toAnother School Of Thought: Incorporation of fluoride to
etching solutions –etching solutions – Increases enamel resistance toIncreases enamel resistance to caries.caries.
Kajander et al – 2% and 4% acidified sodium fluoride solutionKajander et al – 2% and 4% acidified sodium fluoride solution
are effective in preventing decalcification of etched enamelare effective in preventing decalcification of etched enamel
surfaces.surfaces.
Bishara et al – The application of 2% or 4% sod. Fluoride doesBishara et al – The application of 2% or 4% sod. 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 soln. enhances caries prevention during orthoetchant soln. enhances caries prevention during ortho
treatment. But in case the patient has caries or hypoplasiatreatment. But in case the patient has caries or hypoplasia
the etching time and concentration should be increased.the etching time and concentration should be increased.

Removal Of Acid Residues AndRemoval Of Acid Residues And
Crystal Precipitates!Crystal Precipitates!
Subsequent to etching the enamel surface must beSubsequent to etching the enamel surface must be
entirely cleaned from acid residues and from anyentirely cleaned from acid residues and from any
loose deposits of calcium salts lowering theloose deposits of calcium salts lowering the
retentive micro porosities of etched enamel.retentive micro porosities of etched enamel.
Studies have shown that a minimum of 5 seconds ofStudies have shown that a minimum of 5 seconds of
continuous water spray is essential for the acidcontinuous water spray is essential for the acid
residues or crystal precipitates left after acidresidues or crystal precipitates left after acid
etching.etching.

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.

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

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

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.

• 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

PRASHANT PRATAP
III YR MDS
DEPARTMENT OF ORTHODONTICS
SAVEETHA DENTAL COLLEGE
(PART II)

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,surfaces of a substrate, can join them together,
resist separation and transmit load across theresist separation and transmit load across the
bond.”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

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 thesesystems. The basic difference between these
fluid bonding resins and the resin composites isfluid bonding resins and the resin composites is
the absence of filler particles in the former.the absence of filler particles in the former. TheThe
use of these unfilled resins is based upon theiruse of these unfilled resins is based upon their
lower viscosity and thus superior diffusion intolower viscosity and thus superior diffusion into
enamel rods, resulting in improved interfacialenamel rods, resulting in improved interfacial
adaptation.adaptation.

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.

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

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.

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.

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:
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.

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 - includes GI basedSmear layer removing agents - includes GI based
interaction -interaction - 2 step bonding agents.2 step bonding agents.
• Smear layer dissolving agents -Smear layer dissolving agents - 3 step bonding3 step bonding
agents.agents.

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.

• 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.

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 theApplication of a layer of unfilled resin or primer onto the
etched enamel surface prior to bonding is an added step inetched enamel surface prior to bonding is an added step in
bonding process which increases the clinical time requiredbonding process which increases the clinical time required
for fixed appliance placement.for fixed 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 aThe manufacturer also claims that it can be in applied to a
wet enamel surface and adequate etching and priming in awet enamel surface and adequate etching and priming in a
3 second period can be achieved.3 second period can be achieved.

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.

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.

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.

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..

Ideal requisitesIdeal requisites of bonding system:of bonding system:
As per Philips and RageAs per Philips and Rage
• 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.

• 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.
cont…..

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.

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:– camphoroquinone 0.2wt%Initiator:– camphoroquinone 0.2wt%
(photoinitiator)(photoinitiator)
Activator:– dimethylaminoethylActivator:– dimethylaminoethyl
methacrylate (amine).methacrylate (amine).

• Inhibitors-Inhibitors- Butylated hydroxytoluene 0.01wt%.Butylated hydroxytoluene 0.01wt%.
To minimize or prevent spontaneousTo minimize or prevent spontaneous
polymerization of monomers.polymerization of monomers.
• Optical modifiers-Optical modifiers- Titanium dioxide andTitanium dioxide and
Aluminium oxide (0.001 to 0.007wt%).Aluminium oxide (0.001 to 0.007wt%).

• 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.

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.

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.

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

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

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 (low intensity light). 20-60Exposure time – 80-240 seconds (low intensity light). 20-60
seconds (high intensity light)seconds (high intensity light)
• Elevated pulpal temperature with longer curingElevated pulpal temperature with longer curing
cycles.cycles.
• Bracket failure rate – 48%.Bracket failure rate – 48%.
(bracket – adhesive interface-(bracket – adhesive interface- Layman et al 2004).Layman et al 2004).

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.

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.

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
cont……..

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.

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).

Mechanism of Adhesion…Mechanism of Adhesion…
• Chelation of carboxyl groups of the polyChelation of carboxyl groups of the poly
acids with the calcium in the apatite of theacids with the calcium in the apatite of the
enamel and dentin.enamel and dentin.
• Bond to enamel is higher due to greaterBond to enamel is higher due to greater
inorganic content of enamel.inorganic 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.

4.CYANOACRYLATES4.CYANOACRYLATES
(JCO 2000,(JCO 2000,
Thomas W. Ortendahl, ULF Ortengren).Thomas W. Ortendahl, ULF Ortengren).
• 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.

cont…….cont…….
• 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.

5. FIBER – REINFORCED COMPOSITES5. FIBER – REINFORCED COMPOSITES
JCO 2000, VOL 34JCO 2000, VOL 34
Charles J BurstoneCharles J Burstone
Adren J KuhlbergAdren J Kuhlberg
• Is a partially polymerized fiber-matrix complexIs 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.

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.

ADVANTAGES:ADVANTAGES:
(by Cooper et al )(by Cooper et al )
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]. www.indiandentalacademy.com

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.
cont……

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…

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.

cont….cont….
• 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

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.

cont….cont….
• 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.

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

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.

POSITIONING:POSITIONING:
Position the brackets mesiodistally andPosition the brackets mesiodistally and
incisogingivally and angulate them using aincisogingivally and angulate them using a
placement scaler (RM 349).placement scaler (RM 349).
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.

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.

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.

cont….cont….
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.

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 .

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.

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 reliance metal primerApply a uniform coat of reliance metal primer
and wait for 30 seconds.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.

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 andprecious metals (Superbond C&B, Panavia Ex and
21) all have been reported to improve bonding to21) all have been reported to improve bonding to
gold in laboratory settings.gold in laboratory settings.
• Present clinical experiments include the use of newPresent clinical experiments include the use of new
one-component primer based on the VTD adhesiveone-component primer based on the VTD adhesive
monomer [triazine-dithiol] and 4 META adhesivemonomer [triazine-dithiol] and 4 META adhesive
resin.resin.

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.

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.

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.

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

cont….cont….
• 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.

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 de bonds the attachment with a largeand de bonds the attachment with a large
amount of the resin left on the tooth surface,amount of the resin left on the tooth surface,
which can be removed using a finishing bur orwhich can be removed using a finishing bur or
scaler.scaler.

cont….cont….
• 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 Orthopli Bracketdebonding pliers ( 095 Orthopli Bracket
Removing Plier ) at the enamel-composite orRemoving Plier ) at the enamel-composite or
the bracket-composite interface. The bracketthe bracket-composite interface. The bracket
is debonded, leaving minimal amounts ofis debonded, leaving minimal amounts of
resin on the tooth surface. A finishing bur orresin on the tooth surface. A finishing bur or
scaler can remove any remaining resinscaler can remove any remaining resin
residue on the debonded tooth.residue on the debonded tooth.

cont…cont…
• 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.

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.

• 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.

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.

• 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.
cont….

cont…cont…
• 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.

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.

INFLUENCE ON ENAMEL BY DIFFERENTINFLUENCE ON ENAMEL BY DIFFERENT
DEBONDING INSTRUMENTSDEBONDING INSTRUMENTS
((by Zachrisson & Artunby Zachrisson & Artun ))
• 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.

cont…cont…
• 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.

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.

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.

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 offbecause the operator expects that it will wear off
with time!with time!
• Adhesive wear depends on the size, type, and amount ofAdhesive wear depends on the size, type, and amount of
reinforcing fillers in the adhesive. Extremely thin films ofreinforcing fillers in the adhesive. Extremely thin films of
adhesive may not be of esthetic or other concern. It mayadhesive may not be of esthetic or other concern. It may
even be advantageous to seal surface irregularities such aseven be advantageous to seal surface irregularities such as
pits and grooves to protect against demineralization..pits and grooves to protect against demineralization..

• These are carious lesions of varying extent. TheThese are carious lesions of varying extent. The
incidence and severity of white spots after a fullincidence and severity of white spots after a full
term orthodontic treatment have been studied byterm orthodontic treatment have been studied by
several authorsseveral authors.. Gorelick et alGorelick et al found that 50% offound that 50% of
the patients experienced an increase in whitethe patients experienced an increase in white
spots.spots.
• The highest incidence was in the maxillaryThe highest incidence was in the maxillary
incisors.incisors.

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.

MECHANISM OF ACTION OFMECHANISM OF ACTION OF
FLOURIDEFLOURIDE
• Application of fluoride leads to the formation ofApplication of fluoride leads to the formation of
Fluorapatite CrystalsFluorapatite Crystals (instead of Hydroxy apatite(instead of Hydroxy apatite
crystals), which is more resistant to acid attack.crystals), which is more resistant to acid attack.
• Fluoride has aFluoride has a Toxic effectToxic effect on caries causingon caries causing
bacteria.bacteria.
• Also fluorideAlso fluoride prevents the attachmentprevents the attachment ofof
acidogenic bacteria to the susceptible toothacidogenic bacteria to the susceptible tooth
surfaces.surfaces.
• The cariostatic mechanism of Titanium TetraThe cariostatic mechanism of Titanium Tetra
fluoride is probably due to the retentive, Titaniumfluoride is probably due to the retentive, Titanium
rich, glaze-like coating formed on the enamel. Thisrich, glaze-like coating formed on the enamel. This
surface coating has been found to resist challengessurface coating has been found to resist challenges
even under extreme acidic and alkaline conditions.even under extreme acidic and alkaline conditions.

REBONDINGREBONDING
The loose bracket is removed from the archwire. AnyThe loose bracket is removed from the archwire. Any
adhesive remaining on the tooth surface isadhesive remaining on the tooth surface is
removed with a TC bur. The adhesive remainingremoved with a TC bur. The adhesive remaining
on the loose bracket is treated by sandblastingon the loose bracket is treated by sandblasting
until all visible bonding material is removed fromuntil all visible bonding material is removed from
the base. The tooth is then etched with ultra etchthe base. The tooth is then etched with ultra etch
35% phosphoric acid gel for 15 to 30 seconds. after35% phosphoric acid gel for 15 to 30 seconds. after
sealing, the bracket is re bonded. The neighboringsealing, the bracket is re bonded. The neighboring
brackets are re ligated first, and then the re bondedbrackets are re ligated first, and then the re bonded
bracket is ligated.bracket is ligated.

Bonding (2)

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

En vedette

En vedette (7)

Similaire à Bonding (2)

Similaire à Bonding (2) (20)

Plus de Indian dental academy

Plus de Indian dental academy (20)

Dernier

Dernier (20)

Bonding (2)