Bonding in orthodontics 2 /certified fixed orthodontic courses by Indian dental academy

Bonding in OrthdonticsBonding in Orthdontics
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacademy.comwww.indiandentalacademy.com


HistoryHistory
 Advantages ,disavantagesAdvantages ,disavantages
 Factors affecting bondingFactors affecting bonding
 Bonding procedureBonding procedure
 Bonding agentsBonding agents

Based on the investigations of Silverstone,Based on the investigations of Silverstone,
acid solutions in concentrations of 20–acid solutions in concentrations of 20–
50% applied for 1–2 minutes was found to50% applied for 1–2 minutes was found to
produce the most retentive conditionsproduce the most retentive conditions
In 1968 Smith introducedIn 1968 Smith introduced
Znpolycarboxylate for bracket bonding.Znpolycarboxylate for bracket bonding.

Buonocore in 1955 introduced the conceptBuonocore in 1955 introduced the concept
of acid etching. Pretreatment with 85%of acid etching. Pretreatment with 85%
phosphoric acid increased adhesion.phosphoric acid increased adhesion.
In 1965 Newman applied direct bonding toIn 1965 Newman applied direct bonding to
orthodontics.orthodontics.

Miura et al described an acrylicMiura et al described an acrylic
resin(orthomite) using trialkylboraneresin(orthomite) using trialkylborane
catalyst for bonding plastic brackets andcatalyst for bonding plastic brackets and
for enhanced adhesion in presence offor enhanced adhesion in presence of
moisture.moisture.
Bowens resin or bisGMA(bisphenolABowens resin or bisGMA(bisphenolA
glycidyl dimethacrylate) –designed toglycidyl dimethacrylate) –designed to
improve bond strength and improveimprove bond strength and improve
dimensional stability by crosslinking.dimensional stability by crosslinking.

AAdvantages of Bondingdvantages of Bonding
 Esthetically superiorEsthetically superior
 Faster and simplerFaster and simpler
 Less discomfort for patientLess discomfort for patient
 More precise bracket placementMore precise bracket placement
 Improved gingival condition possibleImproved gingival condition possible
 Partially erupted teeth can be controlledPartially erupted teeth can be controlled
 Mesiodistal enamel reduction possibleMesiodistal enamel reduction possible
during treatmentduring treatment

Interprximal areas are accessible forInterprximal areas are accessible for
composite buildupscomposite buildups
Caries risk under loose bands isCaries risk under loose bands is
eliminatedeliminated
No band spaces to close at the end ofNo band spaces to close at the end of
tratmenttratment
 Brackets may be recycled furtherBrackets may be recycled further
reducing the costreducing the cost
Lingual brackets or invisible braces mayLingual brackets or invisible braces may
be used when esthetics is importantbe used when esthetics is important

Disadvantages of BondingDisadvantages of Bonding
 Bonded bracket has a weaker attachment than aBonded bracket has a weaker attachment than a
cemented bandcemented band
 Excess adhesive extending beyond the bracketExcess adhesive extending beyond the bracket
base can cause poor oral hygiene ,leading tobase can cause poor oral hygiene ,leading to
gingival inflammationgingival inflammation
 Protection against interproximal caries of wellProtection against interproximal caries of well
contoured cemented bands is absentcontoured cemented bands is absent
 Rebonding a loose bracket requires moreRebonding a loose bracket requires more
preparation timepreparation time
 Debonding is more time consuming thanDebonding is more time consuming than
debanding as removal of adhesive is moredebanding as removal of adhesive is more
difficult than removal of cementdifficult than removal of cement

Factors affecting BondingFactors affecting Bonding
Enamel solubilityEnamel solubility
Preeuptive factors: chemical orPreeuptive factors: chemical or
histological charecteristics of tooth .histological charecteristics of tooth .
Hypocalcification or hypoplasia of aHypocalcification or hypoplasia of a
permanent teethpermanent teeth
Excessive ingestion of flourideExcessive ingestion of flouride

Posteruptive factotrsPosteruptive factotrs
Topical flouridesTopical flourides
Presence of plaquePresence of plaque

Conditioning solutionConditioning solution
 Phosophoric acid -35 to 50%Phosophoric acid -35 to 50%
 Zinc oxide – acts as a buffer and partiallyZinc oxide – acts as a buffer and partially
neutralizes the acid.neutralizes the acid.
 gels are added to improve the viscosity. Increasedgels are added to improve the viscosity. Increased
concentration or viscosity does not ensure betterconcentration or viscosity does not ensure better
etching:etching:
 Gwinnet and Buonnocore suggested the use ofGwinnet and Buonnocore suggested the use of
lower concentration of phosphoric acid .lower concentration of phosphoric acid .

Application of 50% phosphoric acid forApplication of 50% phosphoric acid for
60sec results in formation of monocalcium60sec results in formation of monocalcium
phosphate monohydrate ppt that can bephosphate monohydrate ppt that can be
rinsed off.rinsed off.
Concentration below 27% lead to formationConcentration below 27% lead to formation
of dicalcium phosphate which cannot beof dicalcium phosphate which cannot be
rinsed offrinsed off

Operator induced complications:Operator induced complications:
water contamination via three way syringe.water contamination via three way syringe.
Care is taken not to rub the etched enamelCare is taken not to rub the etched enamel
with cotton or fingers to avoidwith cotton or fingers to avoid
contamination of surface by greasecontamination of surface by grease
particles $ perspiration.particles $ perspiration.

Factors influencing bonding to ideallyFactors influencing bonding to ideally
etched enameletched enamel
Salivary contamination :salivary proteinsSalivary contamination :salivary proteins
clog the porosities of etched enamelclog the porosities of etched enamel
Water contamination via three wayWater contamination via three way
syringe.syringe.
Care is taken not to rub the etched enamelCare is taken not to rub the etched enamel
with cotton or fingers to avoidwith cotton or fingers to avoid
contamination of surface by greasecontamination of surface by grease
particles $ perspiration.particles $ perspiration.

Uniform etching at the gingival margin is moreUniform etching at the gingival margin is more
difficult :difficult :
As sealent approaches marginalAs sealent approaches marginal
gingiva,seapage of crevicular fluid acts as agingiva,seapage of crevicular fluid acts as a
barrier to the flow of the fluid below the freebarrier to the flow of the fluid below the free
gingival margingingival margin
Sealant ledge formed at the gingival marginSealant ledge formed at the gingival margin

therefore etching area be restricted to thetherefore etching area be restricted to the
center of the clinical crowncenter of the clinical crown
to ensure safe marginal seal conditionedto ensure safe marginal seal conditioned
area should be larger than bracket & padarea should be larger than bracket & pad
area.area.

Bonding procedureBonding procedure
CleaningCleaning
Enamel conditioning and bondingEnamel conditioning and bonding
SealingSealing
bondingbonding

CleaningCleaning
- essential to remove plaque and- essential to remove plaque and
organic pellicleorganic pellicle
- requires rotary instruments – rubber- requires rotary instruments – rubber
cup or a polishing brushcup or a polishing brush
-care must be taken to avoid-care must be taken to avoid
traumatising gingival margintraumatising gingival margin

For increased patient control cleaningFor increased patient control cleaning
should be done before use of moistureshould be done before use of moisture
control devicescontrol devices
Pumice and water residue is eliminatedPumice and water residue is eliminated

Enamel conditioningEnamel conditioning
moisture controlmoisture control ::
-- cheek retractorscheek retractors
- saliva ejectors- saliva ejectors
- cotton or gauze rolls- cotton or gauze rolls
- antisialogogues :probathaline, atropine- antisialogogues :probathaline, atropine
- dri angles : ot restrict saliva flow from- dri angles : ot restrict saliva flow from
parotid glandparotid gland

Enamel pretreatmentEnamel pretreatment
Conditioning solution 35% to 50% isConditioning solution 35% to 50% is
applied lightly over the enamel with foamapplied lightly over the enamel with foam
pellet , or brush for 60 sec. Surface mustpellet , or brush for 60 sec. Surface must
be kept moist by repeated application.be kept moist by repeated application.
Etchant is rinsed off using abundant waterEtchant is rinsed off using abundant water
sprayspray
High speed evacuator used to removeHigh speed evacuator used to remove
etchant water sprayetchant water spray

 Teeth are thoroughly dried with air sourceTeeth are thoroughly dried with air source
to obtain dull frosty appearanceto obtain dull frosty appearance
 Some additional points :Some additional points :
- etching entire facial surface with solution is- etching entire facial surface with solution is
harmlessharmless
- gel gives better control for restricting the etched- gel gives better control for restricting the etched
area but requires more thorough rinsingarea but requires more thorough rinsing
afterwards.afterwards.
-According to Pus routine etching removes 3-10-According to Pus routine etching removes 3-10
micrometer of surface enamelmicrometer of surface enamel

According to Silverstone the etchingAccording to Silverstone the etching
patterns were related to five types:patterns were related to five types:
Type 1:Type 1: preferential dissolution of thepreferential dissolution of the
prism cores resulting in a “honeycomb”prism cores resulting in a “honeycomb”
appearance.appearance.
Type 2:Type 2: preferential dissolution of thepreferential dissolution of the
prism peripheries giving a “cobblestone”prism peripheries giving a “cobblestone”
appearance.appearance.

Type 3:Type 3: a mixture of type 1 and 2 patterns.a mixture of type 1 and 2 patterns.
Type 4:Type 4: pitted enamel surfaces as well aspitted enamel surfaces as well as
structures which look like unfinishedstructures which look like unfinished
puzzles, maps, or network.puzzles, maps, or network.
Type 5:Type 5: flat, smooth surfaces.flat, smooth surfaces.

40% solution40% solution
 Occlusal and central sites:Occlusal and central sites:
The type 2 etching patternThe type 2 etching pattern
with preferentialwith preferential
dissolution of the prismdissolution of the prism
peripheries predominatesperipheries predominates
resulting in aresulting in a
“cobblestone” appearance“cobblestone” appearance

 Cervical third :pittedCervical third :pitted
enamel surface ,typeenamel surface ,type
IV pattrenIV pattren

 Chow and Brown reported that phosphoric acidChow and Brown reported that phosphoric acid
concentrations greater than ~27% produceconcentrations greater than ~27% produce
monocalcium phosphate monohydrate as amonocalcium phosphate monohydrate as a
soluble product, while concentrations less thansoluble product, while concentrations less than
~27% form dicalcium phosphate dihydrate. The~27% form dicalcium phosphate dihydrate. The
former product is readily soluble and would beformer product is readily soluble and would be
completely washed away in the clinical situation,completely washed away in the clinical situation,
whereas the latter product is less soluble.whereas the latter product is less soluble.
 Total loss of superficial enamel, which isTotal loss of superficial enamel, which is
especially rich in fluoride, is probably smallerespecially rich in fluoride, is probably smaller
after etching with 2% or 5% phosphoric acidafter etching with 2% or 5% phosphoric acid
than with a 40% solution.than with a 40% solution.

Disadvantages of phosphoric acid:Disadvantages of phosphoric acid:
1.may contribute to decalcification1.may contribute to decalcification
2. development of white spots around the2. development of white spots around the
around bonded appliancearound bonded appliance
3.enamel fracture particularly when3.enamel fracture particularly when
debonding ceramic bracketsdebonding ceramic brackets

 Softer etching procedures effected mainlySofter etching procedures effected mainly
the type 1 pattern with preferentialthe type 1 pattern with preferential
dissolution of the prism cores. Type 2dissolution of the prism cores. Type 2
pattern represents an advanced stage ofpattern represents an advanced stage of
the etching process possibly caused by athe etching process possibly caused by a
breakdown of the fragile prism peripheries.breakdown of the fragile prism peripheries.

The sequence of etching patterns obtainedThe sequence of etching patterns obtained
with different acid concentrations gave thewith different acid concentrations gave the
impression that the type 2 pattern, i.e.impression that the type 2 pattern, i.e.
increased dissolution of the prismincreased dissolution of the prism
peripheries, occurred predominantly atperipheries, occurred predominantly at
higher acid concentrations (40% andhigher acid concentrations (40% and
20%).20%).

The etching patterns were generallyThe etching patterns were generally
similar in the occlusal and central part ofsimilar in the occlusal and central part of
the buccal surfaces and frequently differedthe buccal surfaces and frequently differed
from the cervical area. Galil and Wrightfrom the cervical area. Galil and Wright
reported that type 4 and 5 patternsreported that type 4 and 5 patterns
predominated in the cervical regions andpredominated in the cervical regions and
types 1, 2, and 3 in the occlusal andtypes 1, 2, and 3 in the occlusal and
central regions. .central regions. .

The aprismatic layer is of variableThe aprismatic layer is of variable
thickness . The crystallites within the layerthickness . The crystallites within the layer
are oriented with their axis almostare oriented with their axis almost
perpendicular to the enamel surface. It isperpendicular to the enamel surface. It is
present at the cervical third of eamelpresent at the cervical third of eamel

Arakawa reported that the resinArakawa reported that the resin
penetration was considerably worse in thepenetration was considerably worse in the
cervical region than in the central andcervical region than in the central and
occlusal regions.occlusal regions.

Alternative etchants as maleic acid:Alternative etchants as maleic acid:
1.produce clinically reliable bond strength1.produce clinically reliable bond strength
2. reduce depth of enamel dissolution2. reduce depth of enamel dissolution
disadvantage of acid etching:disadvantage of acid etching:
1.risk of contamination of moisture and1.risk of contamination of moisture and
saliva is increasedsaliva is increased
2.unpleasnt taste of acid2.unpleasnt taste of acid

Selfetching primers donot penetrate theSelfetching primers donot penetrate the
enamel surface to the same depth asenamel surface to the same depth as
phosphoric acid so conservative treatmentphosphoric acid so conservative treatment
possiblepossible
[JCO October2005][JCO October2005]

Brajen Unibond is a self etching , lightBrajen Unibond is a self etching , light
cured bonding systemcured bonding system
Etching pattern similar to that ofEtching pattern similar to that of
phosphoric acidphosphoric acid
Acid is neutralised by calciumAcid is neutralised by calcium
hydrxyapatite of enamel but specialhydrxyapatite of enamel but special
compounds are able to penetrate mineralcompounds are able to penetrate mineral
component of enamelcomponent of enamel

SEP provides a microretntive bondSEP provides a microretntive bond
strength of 22MPastrength of 22MPa
Adhesive is designed to release flourideAdhesive is designed to release flouride
Good resistance to discolorationGood resistance to discoloration
Combines acid etching and priming into aCombines acid etching and priming into a
single stepsingle step

SealingSealing
Dry the tooth completelyDry the tooth completely
Thin layer of sealant painted over theThin layer of sealant painted over the
etched surface with a small foam pellet.etched surface with a small foam pellet.
Excess sealant may cause bracket drift.Excess sealant may cause bracket drift.
Inetrmediate resin is essential for betterInetrmediate resin is essential for better
bond strength and pervent microleakage.bond strength and pervent microleakage.

BondingBonding
Transfer: reverse action tweezersTransfer: reverse action tweezers
Positioning :placement scaler such asPositioning :placement scaler such as
RM 349 used to position. This allowsRM 349 used to position. This allows
visualisation of the slot w.r.t. ncisal edgevisualisation of the slot w.r.t. ncisal edge
and long axisand long axis
FittingFitting
Removal of excess:scaler or cabide burRemoval of excess:scaler or cabide bur
used.used.

BondingBonding

Indirect bondingIndirect bonding
Advantage :Advantage :
-bracket can be more accurately positioned-bracket can be more accurately positioned
-chair side time is reduced-chair side time is reduced
ProcedureProcedure

Ideal properties of bonding agentIdeal properties of bonding agent
Be nontoxic systemically & to oral tissuesBe nontoxic systemically & to oral tissues
Adequte working & setting timeAdequte working & setting time
Have moderate viscosityHave moderate viscosity
Have sufficient tensile strength &Have sufficient tensile strength &
compressive strengthcompressive strength
Have ability to wet etched enamelHave ability to wet etched enamel
Should resist decomposition in oralShould resist decomposition in oral
enviornment.enviornment.

1955, Buonocore : 30-second application of1955, Buonocore : 30-second application of
85% orthophosphoric acid .85% orthophosphoric acid .
In 1962, Bowen :In 1962, Bowen :
-bisphenol A-glycidyl dimethacrylate (bis--bisphenol A-glycidyl dimethacrylate (bis-
GMA) resin.GMA) resin.
-bis-GMA : stronger and more stable than-bis-GMA : stronger and more stable than
the acrylic , especially when an inorganicthe acrylic , especially when an inorganic
filler material was added.filler material was added.
(Volume 1989 Jul (8 - 15): Bond strength comparison(Volume 1989 Jul (8 - 15): Bond strength comparison
- Milne, Andreasen, and Jakobsen- Milne, Andreasen, and Jakobsen))

1964, Newman :1964, Newman :
-bond orthodontic brackets to the teeth-bond orthodontic brackets to the teeth
-acid-etch technique and an epoxy-derived-acid-etch technique and an epoxy-derived
resin.resin.
In 1970, BuonocoreIn 1970, Buonocore
- combined the acid-etch technique with a- combined the acid-etch technique with a
bis-GMA resinbis-GMA resin
- sealing pits and fissures against caries.- sealing pits and fissures against caries.

Weisser (1973) and Silverman andWeisser (1973) and Silverman and
associates (1974) : application of directassociates (1974) : application of direct
bonded orthodontic bracketsbonded orthodontic brackets
 using the acid etch and bis-GMA resinusing the acid etch and bis-GMA resin
system.system.

Silverman, Cohen, used aSilverman, Cohen, used a
methylmethacrylate and ultraviolet-light-methylmethacrylate and ultraviolet-light-
activated unfilled bis-GMA resin.activated unfilled bis-GMA resin.
 used chairside as an intermediaryused chairside as an intermediary
adhesive between the patient's etchedadhesive between the patient's etched
enamel and the preset adhesive on theenamel and the preset adhesive on the
bracket base.bracket base.

Resins based composites are moreResins based composites are more
viscous than unfilled acrylic resins ,dilutionviscous than unfilled acrylic resins ,dilution
by monomers to decrease viscosityby monomers to decrease viscosity
&enhance wetting was done.&enhance wetting was done.
improved mechanical bonding byimproved mechanical bonding by
optimum formation if resin tagsoptimum formation if resin tags

Traditionally: Bis GMA +TEGDMA toTraditionally: Bis GMA +TEGDMA to
control viscositycontrol viscosity
 these are hydrophobic & worked well asthese are hydrophobic & worked well as
long as it was restricted to enamellong as it was restricted to enamel
For dentin bonding there should beFor dentin bonding there should be
hydrophillic group that bonds dentin & ahydrophillic group that bonds dentin & a
hydrophobic group that bonds the resin.hydrophobic group that bonds the resin.

Composite resinsComposite resins
Basic compositionBasic composition
Resin matrix: BISGMAResin matrix: BISGMA
Filler: quartz ,colloidal silicaFiller: quartz ,colloidal silica
Coupling agent :organosilanesCoupling agent :organosilanes
Inhibitor : hydroquinoneInhibitor : hydroquinone
Opacifiers: titanium oxide and aluminiumOpacifiers: titanium oxide and aluminium
oxideoxide

Ultraviolet light-cured introduced thirtyUltraviolet light-cured introduced thirty
years ago and quickly replaced thoseyears ago and quickly replaced those
products that were self-cured.products that were self-cured.
Disadvantage :Disadvantage :
- radiation hazards- radiation hazards
-limited depth of cure.-limited depth of cure.
 blue, visible light-cured composite resinblue, visible light-cured composite resin
replaced ultraviolet light light cure resins,replaced ultraviolet light light cure resins,
visible light has deepervisible light has deeper

Selfcure compositesSelfcure composites
Initiator : benzoyl peroxideInitiator : benzoyl peroxide
Activator: tertiary amineActivator: tertiary amine

DisadvantagesDisadvantages
 The polymerization :starts immediately on mixingThe polymerization :starts immediately on mixing
 air bubbles that arise during mixingair bubbles that arise during mixing
uneven consistencies in resinsuneven consistencies in resins
weakening of the bond strengthweakening of the bond strength
(1992 AJO-DO, Volume Apr (350 - 354): Bond strength between light-(1992 AJO-DO, Volume Apr (350 - 354): Bond strength between light-
and self-cured resin - Wang and Meng)and self-cured resin - Wang and Meng)

rapid polymerization occurs when therapid polymerization occurs when the
visible light spectrum producing avisible light spectrum producing a
"command set" of the resin."command set" of the resin.
 an unlimited working time is possible withan unlimited working time is possible with
the visible light-cured resin, allowing morethe visible light-cured resin, allowing more
accuracy and an unlimited number ofaccuracy and an unlimited number of
bracket placements with each mix.bracket placements with each mix.
((Volume 1989 Sep (214 - 220): In vitro evaluation ofVolume 1989 Sep (214 - 220): In vitro evaluation of
visible light-cured resin system used in bonding -visible light-cured resin system used in bonding -
Greenlaw, Way, and Galil)Greenlaw, Way, and Galil)www.indiandentalacademy.comwww.indiandentalacademy.com

Light cure resinsLight cure resins
single paste system The ketone,single paste system The ketone,
camphoroquinone, is sensitive to blue lightcamphoroquinone, is sensitive to blue light
at a 470 nm wavelength, which catalyzesat a 470 nm wavelength, which catalyzes
the polymerization reaction.the polymerization reaction.

Tensile bond strength of Transbond 60Tensile bond strength of Transbond 60
and 40 stronger than that of Transbond 20and 40 stronger than that of Transbond 20
Bond strength of light-cured resin ofBond strength of light-cured resin of
Transbond and self cure resin (except inTransbond and self cure resin (except in
instances of 20 seconds or less ofinstances of 20 seconds or less of
exposureexposure
((AJOAJO 1992 ,101 350 -354 Comparison of bond strength of light1992 ,101 350 -354 Comparison of bond strength of light
cure and selfcure -Wei Nan wangcure and selfcure -Wei Nan wang))

disadvantagesdisadvantages
diffuse penetration of the light for curingdiffuse penetration of the light for curing
the resinthe resin
incomplete polymerization beneath theincomplete polymerization beneath the
surfacesurface
limited depth of cure, ranging from 2.0 tolimited depth of cure, ranging from 2.0 to
3.0 mm3.0 mm
 doubling the exposure time increased thedoubling the exposure time increased the
cured depth by about a third (3.0 to 4.0cured depth by about a third (3.0 to 4.0
mm in depth).mm in depth).

Transbond 60 and 40 have the same bondTransbond 60 and 40 have the same bond
strength,strength,
adequate time exposure for clinical usageadequate time exposure for clinical usage
is 40 seconds to keep minimum operativeis 40 seconds to keep minimum operative
timetime

Glass ionomer cement :acid etchingGlass ionomer cement :acid etching
not requirednot required
Easier to remove from the enamelEasier to remove from the enamel
than composites.than composites.

Dentin poses greater obstacles thanDentin poses greater obstacles than
enamel :enamel :
- it is a living tissue- it is a living tissue
- it consists 20% volume of fluid- it consists 20% volume of fluid
- tubular fluid adversely affects adhesion- tubular fluid adversely affects adhesion

Glass ionomer cementGlass ionomer cement

Properties of glass-ionomer liners includes
effective bonding to dentin,
 release of fluoride,
 radio-opacity,
low thermal conductivity
(Shear bond strength of composite, glass
ionomer, and acidic primer adhesive systems
Samir E. Bishara AJO 1999 volume 115)

 this product has its own conditioner (20%
polyacrylic acid) that removes the smear
layer and prepares
Carboxyl group of polyacids react with
calcium of apatite of enamel and dentin
Takes 24 hrs for conventional GICs toTakes 24 hrs for conventional GICs to
achieve maximum strengthachieve maximum strength

The results indicated that the
resin/phosphoric acid adhesive system
(control group) provided the strongest
shear bond strength (10.4 ± 2.8 MPa).
The glass ionomer adhesive system
provided a significantly lower bond
strength ( 6.5 ± 1.9 MPa)

 Glass ionomer cement (GIC)
 bond chemically to enamel and dentine without
etching these surfaces, and
 release fluoride ions to the vicinity.
 not recommended for bonding orthodontic
brackets due to lower bond strength compared
to composite resin.
 To increase the bond strength, some resins,
such as hydroxydimethacrylate and BIS-GMA,
are added to GIC.
(Shear bond strength of resin reinforced GIC-
CHUN,HSI CHUNG AJO DO 1999VOLUME
115)

Resin modified glass ionomerResin modified glass ionomer
cementcement
COMPOSITIONCOMPOSITION
 Fuji Ortho LC powderFuji Ortho LC powder
- fluoroalumino-silicate glass- fluoroalumino-silicate glass
- polyacrylic acid, water, monomer, and an- polyacrylic acid, water, monomer, and an
activator. Theactivator. The
-2-hydroxyethyl-methacrylate .-2-hydroxyethyl-methacrylate .
-camphorquinone as a photoinitiator.-camphorquinone as a photoinitiator.
((AJODOAJODO 1995,108,231 to 236)1995,108,231 to 236)
Elliott Silverstone and MortonElliott Silverstone and Morton CohenCohen))

Setting reactionSetting reaction
-an acid-base reaction-an acid-base reaction
- The light irradiation activates free radical- The light irradiation activates free radical
polymerization of HEMA to form a polyHEMApolymerization of HEMA to form a polyHEMA
matrix that hardens the material.matrix that hardens the material.
-self-cure of the resin monomers.-self-cure of the resin monomers.
-light initiated reaction : early placement of arch-light initiated reaction : early placement of arch
wires,wires,
-the acid-base reaction occurs simultaneously and-the acid-base reaction occurs simultaneously and
continues for a period of time after the mass hascontinues for a period of time after the mass has
been cured by light irradiation.been cured by light irradiation.

 It polyHEMA and the polyacrylic metal salt form aIt polyHEMA and the polyacrylic metal salt form a
homogeneous matrix that surrounds the glass particles.homogeneous matrix that surrounds the glass particles.
ADVANTAGESADVANTAGES
 more comfortable appointments for both the patient andmore comfortable appointments for both the patient and
the operator.the operator.
 releases fluoridereleases fluoride
does not require etching of the enamel,does not require etching of the enamel,
 around brackets may well be reduced or eliminated.around brackets may well be reduced or eliminated.

saves valuable chair time with respect tosaves valuable chair time with respect to
composite resin bonding :composite resin bonding :
- keeping the field dry not required- keeping the field dry not required
- etching and priming steps eliminated- etching and priming steps eliminated

LandmarksLandmarks
Acid pretreatment with 85% phosphoric acid
Buonocore 1955
bisphenolA-Glycidyl dimethacrylate
Bis-GMA
Bowen 1962
Cyanoacrylates,polyesters,polyurethanes as ortho
adhesives
Newman 1965
Direct bonding with epoxy resin
G V Newman 1965
Zinc polyacrylate(carboxylate)
Mizrahi and smith.1968

1st
detailed posttreatment evaluation
Of direct bonding
Zachrisson 1977
U V light cure bonding
Silverman 1971
Acrylic resin using tri n borane as catalyst
Miura, masuhara 1971
Visible light cure bonding
1979

 The minimum bond strength required for clinical
success is related to the forces of occlusion and
not to the forces generated by an orthodontic
arch wire. The force generated by an orthodontic
arch wire ranges from 15 to 150 gm. Forces
produced during mastication are highly variable,
with a range up to 50 kg.(40- 120 N)
 Thickness of the bonding material between
the bracket base and tooth surface is 0.2 to 0.5
mm.

First generation bonding agentFirst generation bonding agent
 Experimental bonding systems based on epoxyExperimental bonding systems based on epoxy
resins and acrylic resinsresins and acrylic resins
 Uses silane coupling agents whichUses silane coupling agents which
-bond inorganic filler to the matrix of resin-bond inorganic filler to the matrix of resin
-are gamma-methacryloxyprorpyl trimethoxysilane-are gamma-methacryloxyprorpyl trimethoxysilane
- represented as M-X.- represented as M-X.
-First generation ignored the smear layer-First generation ignored the smear layer

 M is the unsaturated group capable ofM is the unsaturated group capable of
copolymerising with unfilled resin.copolymerising with unfilled resin.
 X is capable of chemically reacting with siliceousX is capable of chemically reacting with siliceous
substratesubstrate
 Disadvantage :Disadvantage :
1.high polymerisation shrinkage1.high polymerisation shrinkage
2.different coeffiient of thermal expansion from2.different coeffiient of thermal expansion from
enamelenamel
3. Bond strength is 2-3 MPa3. Bond strength is 2-3 MPa

First generation contained NPG-GMAFirst generation contained NPG-GMA
An example of NPG-GMA bonding agentAn example of NPG-GMA bonding agent
isis
S.S. White cervident .S.S. White cervident .

Second generation dental adhesiveSecond generation dental adhesive
Polymerisation byPolymerisation by ultraviolet lightultraviolet light
 polymerizable phosphates added to BiS-GMApolymerizable phosphates added to BiS-GMA
resins promote bonding to calcium called asresins promote bonding to calcium called as
phosphate bonding systemphosphate bonding system
 In 1978 clearfill bond system F (Kuraray Japan)In 1978 clearfill bond system F (Kuraray Japan)
was introduced- first product of secondwas introduced- first product of second
generation bonding system(sturdevant).Thisgeneration bonding system(sturdevant).This
contained HEMA and Phenyl Pcontained HEMA and Phenyl P

Significant chemical bonding betweenSignificant chemical bonding between
adhesive and tooth structure was lackingadhesive and tooth structure was lacking
Second generation contained NPG-GMASecond generation contained NPG-GMA
(N phenyl glycine glycidyl methacrylate)(N phenyl glycine glycidyl methacrylate)

Mechanism of action :polar interactionMechanism of action :polar interaction
between negatively charged phosphatebetween negatively charged phosphate
group in resin and positively chargedgroup in resin and positively charged
calcium ion in the tooth structurecalcium ion in the tooth structure
Disadvantage:Disadvantage:
-radiation hazard-radiation hazard
- low bond strength- low bond strength
-resins devoid of hydrophillic component-resins devoid of hydrophillic component
- limited depth of penetration.- limited depth of penetration.

Third generation dental adhesivesThird generation dental adhesives
Filled or composite resins addedFilled or composite resins added
Based on use of an acid group to react withBased on use of an acid group to react with
Ca ions & a methacrylate group toCa ions & a methacrylate group to
copolymerise with resin.copolymerise with resin.
 these used a conditoning step on dentinthese used a conditoning step on dentin
Conditioning agents interact with superficialConditioning agents interact with superficial
dentindentin

 Bowen in 1982 developed aBowen in 1982 developed a multistepmultistep
adhesive systemadhesive system called as an oxalate bondingcalled as an oxalate bonding
system.system.
 Used dentin conditioner of 2.5% nitric acidUsed dentin conditioner of 2.5% nitric acid
in combination with ferric oxalate.in combination with ferric oxalate.
 Bond strength -10.2 to 18.5 MpaBond strength -10.2 to 18.5 Mpa
 Bowen later replaced ferric oxalate withBowen later replaced ferric oxalate with
aluminium oxalate.Bond strength increased toaluminium oxalate.Bond strength increased to
12.5 +/_ 3.2 Mpa12.5 +/_ 3.2 Mpa

Third generation bonding proceduresThird generation bonding procedures
involved following steps:involved following steps:
1 Application of dentin conditioner (type of1 Application of dentin conditioner (type of
acid to alter or remove smear layer)acid to alter or remove smear layer)
2.Application of primer2.Application of primer
3.application of adhesive, resin3.application of adhesive, resin
Advantage :improved thermal expansionAdvantage :improved thermal expansion
qualitiesqualities
Removing the flash once it sets is difficultRemoving the flash once it sets is difficult

Develops full strength with in few minutesDevelops full strength with in few minutes
Sets rapidlySets rapidly

Fourth generationFourth generation
NO MIX TECHNIQUENO MIX TECHNIQUE
Excess resin not polymeriseExcess resin not polymerise

It was recognised that phosphoric acidIt was recognised that phosphoric acid
could be used to etch both enamel &could be used to etch both enamel &
dentin. Previous generations relied ondentin. Previous generations relied on
separate etching regimens for enamel &separate etching regimens for enamel &
dentin. Thereforedentin. Therefore total etch techniquetotal etch technique
was used. This led to decreasedwas used. This led to decreased
complexitycomplexity

Fifth generationFifth generation
 Used visible light to activate polymerisationUsed visible light to activate polymerisation
Micromechanical retention is obtained byMicromechanical retention is obtained by
 Penetratoin into partiallly open dentinal tubulesPenetratoin into partiallly open dentinal tubules
 Formation of a layer in which hydrophillicFormation of a layer in which hydrophillic
monomer penetrate and polymerise to form anmonomer penetrate and polymerise to form an
intrepenetrating network with the demineralisedintrepenetrating network with the demineralised
collagen fibril network.This leads to good bondcollagen fibril network.This leads to good bond
strengthstrength

DisadvantageDisadvantage
difficult to get enough visible light todifficult to get enough visible light to
bonding material below the base of thebonding material below the base of the
bracket to obtain good polymerisation.bracket to obtain good polymerisation.

journal namejournal name

Sixth generation bonding agentSixth generation bonding agent
 Self etching primer: etches and primes toothSelf etching primer: etches and primes tooth
simultaneuoslysimultaneuosly
 Composition: phosphoric acid and methacrylate groupsComposition: phosphoric acid and methacrylate groups
 Advantage :Advantage :
-reduce number of procedural steps during bonding-reduce number of procedural steps during bonding
-Decrease chair side time-Decrease chair side time
Product will allow bonding in areas that are difficult toProduct will allow bonding in areas that are difficult to
isolate.isolate.
Bark Mier : Resin penetrated through enamel surface andBark Mier : Resin penetrated through enamel surface and
adequate conditioning was achievedadequate conditioning was achieved

The bonding method involves a pumice
prophylaxis, followed by application of the
self Etching adhesive for three seconds, a
quick blast of air to thin the material, and
direct attachment of the bracket to the tooth
with a light-cured composite resin.

 Acidic part of the primer dissolves the smear
layer and incorporates it into the mixture. Acidic
primer solutions also demineralize the dentin
and encapsulate the collagen fibers and
hydroxyapatite crystals.
 This simultaneous conditioning and priming
allows penetration of the monomer into the
dentin. The adhesive resin component will then
diffuse into the primed dentin, which produces a
“hybrid layer.
(Sameer E. bishara)

Samir E. Bishara.Samir E. Bishara. Shear bond strength of
composite, glass ionomer, and acidic
primer adhesive systems Am. J . Orthod
Dentofacial orthop;1999 :115:24-8

Combine the conditioning (Phenyl P) and
priming (HEMA and dimethacrylate)
agents into a single acidic primer solution
that can be used on enamel and dentin.
Seventy freshly extracted human molars

Group I : polyacrylic acid and GICGroup I : polyacrylic acid and GIC
Group II:composite resin adhesive + 37%
acid
 Group III:same composite resin +acidic
primer

 Results :
1. Resin/phosphoric acid adhesive system
(control group): shear bond strength ( 10.4
± 2.8 MPa)
2.GIC adhesivesystem: bond strength
( 6.5 ± 1.9 MPa)
3.acidic primer + orthodontic adhesive:
( 2.8 ± 1.9Mpa

Samir E.Bishara.Samir E.Bishara. Effect of an acidic primer
on shear bond strength of orthodontic
brackets: Am J Orthod Dentofacial Orthop
1998;114:243-71998;114:243-7

Group1: 37%phosphoric acid +Group1: 37%phosphoric acid +
system1+adhesive (activator liquid +system1+adhesive (activator liquid +
adhesive paste placed on bracket)adhesive paste placed on bracket)
Group2: 10%maleic acidGroup2: 10%maleic acid
+system1+adhesive+system1+adhesive
Group3:acidic primer + lightly filledGroup3:acidic primer + lightly filled
resins(BisGMA)resins(BisGMA)
Group4:acidic primer +highly filled resinsGroup4:acidic primer +highly filled resins

RESULTS
 acidic primers bonded to orthodontic brackets to
the enamel surface can provide clinically
acceptable shear bond forces ( 10.4 +/- 4.4
MPa) when used with a highly (77%) filled
adhesive.
 These debonding forces were comparable to
those obtained when the enamel was
conditioned with either phosphoric ( 11.8 +/- 4.1
MPa) or maleic ( 10.9 +/- 4.4MPa) acids. With
the use of a lightly (10%) filled adhesive (Clearfil
Liner Bond 2), the shear bond strength was
significantly lower (5.9+/- 5.6 MPa).

Seventh Generation bonding agentSeventh Generation bonding agent
MIP is hydrophilic because it contains 2-
hydroxyethyl methacrylate, polyalkenoate
copolymers with carboxylate groups, and
ethanol.
(Ram Kumar Gandhi .Shear bond strength(Ram Kumar Gandhi .Shear bond strength
of stainless steel brackets with moistureof stainless steel brackets with moisture
insensitive brackets; AJODO 2001:insensitive brackets; AJODO 2001:
119:251-5)119:251-5)

Concise with its conventional primer had
the highest shear bond strength under dry
etched enamel surface(14.86 MPa)
 Enamel wet with either water or saliva,
there was a dramatic and highly significant
drop in the bond strength for both the
conventional primer and the MIP.

MIP in combination with Transbond XT
produced acceptable bond strengths in
the presence of a thin film of water or
saliva (9.69 MPa and 8.90 MPa)

MIP used with Concise under dry etched
enamel surface conditions, the MIP might
diffuse into the resin,causing sufficient
bond strength without light activation.
In contrast, in a wet field, the primer
becomes diluted and also no visible light
to cure it

 MIP : hydrophilic nature. It is designed to be
visible-light cured.
 MIP is used with Transbond XT: it can be cured
by the visible light that penetrates the resin.
Thus, MIP was found to be effective when used
with Transbond XT on enamel surfaces
contaminated with either water or saliva.
 Concise is chemically activated: no mechanism
for the hardening of MIP because there is no
application of visible light.

Hobson RS, Ledvinka J .The effect ofHobson RS, Ledvinka J .The effect of
moisture and blood contamination onmoisture and blood contamination on
bond strength of new orthodontic material.bond strength of new orthodontic material.
Am.J.Orthod DentofacialAm.J.Orthod Dentofacial
orthop2002;122:267-73orthop2002;122:267-73

Transbond XT with MIP, (Moisture
Insensitive Primer,3M/Unitek Dental
Products) and Assure (Reliance
Orthodontics, Itasca, Ill), a light-cured bis-
GMA-type resin.
144 freshly extracted bovine teeth

Results:Results:
highest mean bond strength in groups 1highest mean bond strength in groups 1
and 4and 4
lowest mean bond strength in groups 2&3lowest mean bond strength in groups 2&3

 Noncontaminated enamel surfaces had the
highest bond strengths for both the hydrophilic
and hydrophobic materials.
 When using a hydrophobic primer, if the etched
surface is contaminated with saliva before
primer application, it may be necessary to re-
etch before proceeding with the bonding
procedure. If the contamination occurs after the
primer had been placed and cured simple drying
and reapplication of primer is necessary to
obtain adequate bond strength

CCeramic bracketseramic brackets

 The esthetic requirements of orthodontic
treatment - tooth-colored attachments.
 Esthetic brackets - based on
polycarbonates and metal-reinforced
plastics had been introduced for direct
bonding, but they were found clinically
inefficient because of their high
debonding rates ,lack of strength to
resist distortion and breakage,wire slot
wear ,discoloration
 The ceramic bracket is made of
polycrystalline aluminum oxide (Al203)
with a specially prepared bonding
surface

Bonding ceramic brackets:Bonding ceramic brackets:
The ceramic bracket is made of
polycrystalline aluminum oxide (Al203) with a
specially prepared bonding surface
2 mechanisms;2 mechanisms;
Mechanical retention via indentations andMechanical retention via indentations and
or undercuts in the bracket base.or undercuts in the bracket base.
Chemical bonding using an adhesiveChemical bonding using an adhesive
intermediate.intermediate. www.indiandentalacademy.comwww.indiandentalacademy.com

Chemically bndedChemically bnded
• More recent development.
• Glass is added to the aluminium oxide bracket
base and treated with silane coupling agent. The
silane bonds with glass and has a free end of its
molecules that will react with any of acrylic
bonding materials
• The same mechanism as that used for porcelain
crowns and restorations
• Produces exceptonal bond strength….But

Can possibly exceed brittle fracture
resistance.
Stresses of debonding shift from bracket –
adhesive interface to enamel- adhesive
interface inducing enamel cracks
If bracket to adhesive bond is too strong
then failure can occur within the enamel
within the adhesive or within the ceramic

Bonding materials for ceramics:
No-mix or one step bonding materials
contraindicated:
 They have higher concentrations of
amine polymerization accelerator. (Tends
to discolour more.)

The newer light cured restorative
materials-adhesives of choice.
Excellent colour stability
Adequate time for bracket placement.
 An unfilled acrylic cement gave the
highest values of bond strength for both
the plastic and the ceramic brackets.
A highly filled diacrylate cement gave the
highest values of bond strength for the
metal brackets. www.indiandentalacademy.comwww.indiandentalacademy.com

Ceramic brackets are large , very hardCeramic brackets are large , very hard
and do not bend on pressure , extracarefuland do not bend on pressure , extracareful
debonding is necessary not to introducedebonding is necessary not to introduce
enamel cracksenamel cracks
All adhesive outside the bracket isAll adhesive outside the bracket is
removed with a bur before bracket isremoved with a bur before bracket is
gently lifted off the toothgently lifted off the tooth
Also surface of ceramic brackets isAlso surface of ceramic brackets is
rougher .thus sttracts more plaquerougher .thus sttracts more plaque

Metal bracketsMetal brackets
Rely on mechanical retention for bondingRely on mechanical retention for bonding
Perforated bases provide less bondPerforated bases provide less bond
strength and are less hygienic than meshstrength and are less hygienic than mesh
backed bases as more plaquebacked bases as more plaque
accumalates on adhesive resin flowingaccumalates on adhesive resin flowing
through holesthrough holes
Meshbacked bases should be small andMeshbacked bases should be small and
follow gingival contourfollow gingival contourwww.indiandentalacademy.comwww.indiandentalacademy.com

Corrosion of metal brackets due to poorCorrosion of metal brackets due to poor
bondingbonding
through crevice causes black and greenthrough crevice causes black and green
stainsstains

Conditioning agents used include:Conditioning agents used include:
1.1. Hydroxymethylmetacrylaye(HEMA)Hydroxymethylmetacrylaye(HEMA)
2.2. solution of maleic acidsolution of maleic acid
3.3. 2% aqueous nitricacid2% aqueous nitricacid
- another system consisted of- another system consisted of
 aqueous EDTA : as a conditioneraqueous EDTA : as a conditioner
 bonding agent: 2% gluteraldehydebonding agent: 2% gluteraldehyde
 it reacts with collagen rather the nitric oxideit reacts with collagen rather the nitric oxide

thank youthank you
For more details please visitFor more details please visit

Bonding in orthodontics 2 /certified fixed orthodontic courses by Indian dental academy

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Destaque

Destaque (13)

Semelhante a Bonding in orthodontics 2 /certified fixed orthodontic courses by Indian dental academy

Semelhante a Bonding in orthodontics 2 /certified fixed orthodontic courses by Indian dental academy (20)

Mais de Indian dental academy

Mais de Indian dental academy (20)

Último

Último (20)

Bonding in orthodontics 2 /certified fixed orthodontic courses by Indian dental academy