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

Bonding in orthodontics
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


•Introduction
•Bonding over banding
•Basic bonding procedure
•Materials used in bonding
•Bonding to crowns&restorations
•Bonding various brackets
•Indirect bonding
•Lingual bonding
•Rebonding
•Debonding
•Factors affecting bond strength
•Conclusion


Introduction
In 1995 BUNOCORE introduced acid etching technique.He
demonstrated increased adhesion produced by acid pretreatment
of enamel.This led to dramatic changes in practice of orthodontics
. 1965-with the advent of epoxy resin bonding NEWMAN began to apply
these findings to direct bonding of orthodontic attachments
In early 1970s considerable no, of preliminary reports were
published on different commercially available direct &indirect
bonding system.
A survey conducted by LEONARD GOERLICK in 1979 JCO revealed
almost 93% of orthodontists started bonding brackets (at least in
anteriors )instead of banding.


BONDING OVER BANDING
Advantages
1. Esthetically superior.
2. Faster & Simpler.
3. Less discomfort for the patient
4. Arch length is not increased by band material.
5. Allows more precise bracket placement even in tooth with aberrant
shape.
6. Improved gingival health.
7. Better access for cleaning .
8. Mesiodistal enamel reduction possible during treatment.
9. Interproximal areas are accessible for composite buildup.
10.Caries risk under loose bands is eliminated.Interproximal caries
can be deducted & treated.
11. No band spaces to close at end of treatment.
12.No large supply of bands are needed.

13. Brackets can be recycled further reducing the cost.
14. Invisible lingual brackets can be used when esthetic is important.
15. Attachments can be bonded to fixed bridgeworks.


Disadvantages
1. Bonded brackets have weaker attachments than cemented band.
2. If excess adhesive extends beyond bracket base increases risk of
plaque accumulation
3. Protection against interproximal caries of well contoured
cemented brackets is absent.
4. Bonding generally not indicated when lingual auxillaries or
headgear required.
5. Rebonding loose brackets require more preparation than
rebanding loose bands.
6. Debonding- more time consuming due to more difficult removal
of adhesives.
7. Evidence based decalcification& white spot lesion occurs more
following bonding than banding.


BASIC BONDING PROCEDURE
1. CLEANING
2. ENAMEL CONDITIONING.
3. SEALING
4. BONDING


CLEANING
•
•

Thorough cleaning of teeth to remove plaque &organic
pellicle that normally forms on teeth is mandatory.
Materials used are water slurry of pumice or prophylaxis
paste with rotary instruments like rubber cup or small
polishing brush.


ENAMEL CONDITIONING
1. MOISTURE CONTROL
2. ENAMEL PRETREATMENT
MOISTURE CONTROL
Completely dry working field is absolutely necessary .
Devices like
•Lip expanders &cheek retractors
•Saliva ejectors
•Tongue guards with bite blocks
•Salivary duct obstructers
•Cotton or gauze rolls
•Antisialogogues can be used.

ANTISIALOGOGUES
They help to decrease salivary release from glands & ducts unlike
other devices that control released saliva.
Ex:
• Atropine sulphate- In JCO-1981 Sidney brant Showed this is a safe
drug with complication & can be used as an sublingual injection
Dose-0.4 mg
• Banthine tablets –In JCO 1981 Richard .N. Carterreported that 50 mg per
100 lb in a sugar free drink 15 min before bonding is adequate.


ENAMEL PREATREATMENT
PROCEDURE:
After drying the tooth apply a conditioning solution or gel ( usually
37% to 50% phosphoric acid ) lightly over enamel surface with a
pellet or brush for 15-60 sec.
Enchant Is rinsed off with abundant water spray for about 15 sec.
If salivary contamination occurs rinse with water spray & re etch
for another 30 sec .
Dry the tooth thoroughly to obtain dull frosty white appearance.
If not re etch
Etching is also done by 10% polyacrylic acid
10% maleic acid or

HISTOLOGY:

Lehman & Davidson AJO 1981
When enamel is etched with phosphoric acid of high %age like 50%
it forms monocalcium phosphate monohydrate on the surface which
is highly soluble in water & can be completely washed away leaving
a roughness of larger surface area.


There are 4 types of enamel appearance after various pre
treatment
Type 1
Honey comb appearance with loss
of enamel prism centers.

Type -2
Cobblestone appearance
with prism edges lost.

Type -3
Pitted enamel with map
like appearance.

Type -4

Granulation of enamel
with numerous holes


Enamel after 15% phosphoric acid etching
15 secs,

30 secs,

60 secs,


Enamel after 37 % phosphoric acid etching
30 secs,

15 secs,

60 secs,


Enamel after 37 %
phosphoric acid etching

Enamel after 10 %
polyacrylic acid etching


Air abrasion:
Its a older technique of enamel pretreatment introduced as early as
1940 by Dr. Robert black..It uses abrading with 50 um or 90 um
particles of aluminium oxide for 3 sec at 10mm distance..AJO-DO 1997
Marc .E. Olsen et al reported that air abrasion significantly decreases
bond strength & on debonding leaves no adhesive on enamel surface.
So it is not recommended.
37% H3PO4 acid

90 um AlO2 air abrasion


In AJO-DO 1980 Nordenwall
Reported that 15 sec etching is adequate for young
permanent teeth ,whereas 60 sec are needed for permanent
teeth. Same author in 1981 that there is no significant
differences appear between etching solution or gel. But gel
provides better control for restricting the etched area but
requires more thorough rinsing afterward.

In AJO-DO 1986 Chris .D.Johnson's et al

Recommended 60 sec etching of buccal surface of molars to
produce optimal etch pattern .
Its best to avoid etching over acquired as well as developmental
demineralizations. If its impossible a short etching time ,
.
application of sealant & the use of direct bonding with extra
attention to not having areas of adhesive deficiency are important
The presence of voids can lead to metal corrosion & indelible
staining of underlying developmental white spots.

Tooth with exposed dentin should be coated with Ca(OH)2 paste
before etching.
Though Zachrisson reports fluoride content of tooth has no
effect on etching time R. Lehman& Davidson in AJO-DO 1981 reported
that fluoride is important in decreasing enamel solubility.
Fluoridated enamel has highly acid resistant layer of 2-4 um
thickness which may sometimes resist even 3 min etch. So
avoiding fluoride application shortly prior to bonding is
recommended.
.But In AJO-DO Garcia Godey et al reported that addition of 0.5%
NaF2 to 60% phosphoric acid gel produced significantly higher
bond strength than 30% phosphoric acid without fluoride.


AMOUNT OF ENAMEL IOST DURING ETCHING:

Zachrisson- Routine etching with 37% phosphoric acid removes 310 um of surface enamel.

Gwinnett et al -50% Phosphoric acid removes 5 – 25 um of
enamel.

Fitzpatrick & way and by Silverstone reported that 30% phosphoric
acid for 90 sec removes enamel with a mean of 9.9 um

Leebrown & Way –37% phosphoric acid in 90 secs removes a mean
of 3 u ( 0.2 +11.2 um)


Crystal growth theory:
Jon Arton in AJO-DO 1984 reported crystal growth conditioning
after use of polyacrylic acid with residual sulphate provided
retention areas in enamel similar to phosphoric acid etching with
less risk enamel damage at debonding.
Phosphoric acid etched
Crystal growth on
enamel surface
enamel surface


NEW CONCEPTS OF ETCHING:
Laser etching:
This new concept was proposed in 1993.Angle by J.A.Von Fraunhofer.
He showed at 3 watts for 12 sec laser etching produced acceptable
bond strength though significantly less than conventional acid
etching. He used Nd/ YAG as laser source.

Serder Usumuz et al in AJO-DO 2002 used ErCr ; YSGG as the
hydrokinetic laser system for acid etching & came to the same
conclusion.
But major disadvantage as reported by Fraunhofer is that high
laser produces heat in sufficient magnitude to cause at least
localized pulpal infection & possible irreversible damage to pulpal
tissue immediately opposite the site of laser irradiation.

SEM picture of enamel after
37% phosphoric acid etching.

SEM picture of enamel after
laser etching of 2 W output.


SEALING
After etching a thin layer of sealant may be painted over entire
enamel surface . Its best applied with a small foam pellet or brush
&it should be thin & even.
Use of sealant led to many divergent conclusions.
1. They might be necessary to achieve proper bond strength .
2. Its necessary to improve resistance to micro leakage.
3. After sealant coating moisture control may not be extremly
important.
4. It provides enamel cover in areas of adhesive voids.
5. Gwinnet& Ceen found light polymerized sealant protect
enamel adjacent to brackets from dissolutions &
subsurface lesions

6. Sealant might permit easier bracket removal & protect
against enamel tear outs during debonding.
7. Study by Leonardo Foresti et al Angle 1994 showed sealant
actually increases no, & length of resin tags. Also more fluid
resin coupled with previously applied sealant penetrates deeper
into enamel & forms longer tags.


BONDING
1. TRANSFER.

Bracket gripped with a pair of cotton pliers . Slight excess of
adhesive is applied to bracket base .To mix adhesive the per tooth
mixing is the best mtd , because it provides sufficient working
time & can obtain optimal bond strength.The operator can work
in a relaxed manner .Now the bracket is placed on tooth close to
its correct position.
2. POSITIONING.

Placement scaler preferably with parallel edges is used to
position the bracket both vertically & horizontally in correct
position.

Use of bracket positioning gauge:


Using precision instrument:


3.FITTING

Using the scaler with one point contact with the bracket , its
pushed firmly towards the tooth surface. This tight fit ensures
good bond strength & reduces sliding of bracket.Remove the
scaler & do not disturb the bracket.( totally undisturbed setting is
essential for achieving adequate bond strength).
4.REMOVAL OF EXCESS

A slight bit of excess adhesive is essential to minimize
possibility of voids.so using sufficient adhesive & buttering it
into entire mesh backing of bracket is very helpful.But this leads
to excess adhesive flush.
Its better to remove excess adhesive with scaler before the
adhesive sets without disturbing bracket position .We can also
use oval(No 7006 No 2) or tapered (No 1172) tungsten carbide
(TC) bur.

Removing excess adhesive is a must because
•To minimize gingival irritation by preventing plaque
accumulation around the periphery of bracket base.
•To reduce periodontal damage.
•To prevent possibility of decalcifications.
•It avoids bridging when tooth are crowded
•Improves esthetics.
•Facilitate debonding.


MATERIALS USED IN BONDING
Glass ionomer cements (GIC)
IT was introduced in 1972 by Wilson & Kent as a new translucent
cement for dentistry. It’s a hybrid of silicate & polycarbonate
cement. :
First generation
Used as luting agent & direct restorative material with unique
properties for bonding chemically to enamel , dentin,& stainless
steel.IT also releases fluoride that prevents caries formation. But
it has high susceptibility to water while setting leading to weaker
bond.
Second generation
Water hardening cements with same acids in freeze – dried form
or an alternative powdered co-polymer of acrylic & maleic acid.

ADHESIVES
Basically 2 types.
1. Acrylic resins:
• These are self curing resins
• Composed of methylmethacrylate monomer & ultra fine
powder
• They produce linear polymer so has less bond strength
2. Diacrylic resins:
• These are acrylic modified epoxy resin (bis –GMA or
Bowen's resin)
•They polymerize by forming cross linking
•So increase strength
•Decrease water absorption
•Decrease polymerization shrinkage

Can also be classified as
1. Unfilled resins:
• Has minute filler particles of uniform size ( 0.2 & 0.3
millimicron)
• Yield smoother surface
• Retains less plaque
• More prone to abrasion
2.Filled resins:
• Has coarse filler particles of quartz
or silica of variable size.
• Increase abrasion resistance.
• Increase plaque accumulation.

No mix adhesives
• Here one paste is applied to bracket base & a primer is applied
to etched enamel. When both come in contact under slight
pressure its cured chemically.
• Simplicity.
• Unpolymerized monomer might retain causing toxicity &
allergy.
Visible light cured adhesive
• These adhesives are cured when exposed to light.They contain
CAMPHOROQUINONE as photo initiator which is absorbed at
the wave length of 470 nm & thus gets activated.
•Light cured composite resins used with metal brackets are usually
dual cured having both light initiators & chemical catalyst.

Light sources used are :
• Halogen is the conventional light source used.
• Argon laser curing
• Xenon or plasma arc lamp from 1998
• Light emitting diode (LED) introduced by mills et al
Depth of curing usually depends on
• Composition of resin
• Light source
• Exposure time


Halogen
• Light is generated using two hot filaments.
• It uses about 400 mW / cm 2 power.
• It has a broad wave length of 400 – 520 nm .This results in
decreased intensity of light .

In EJO 2004 Nendl & droshl et al reported halogen light
achieved highest bond strength with 40 sec curing time .

Tarle et al EJO 2002 found halogen light achieved highest conversion
rate of about 60+ 55 in 20 sec & 73.5+ 1.4% in 40 sec


Argon laser
• Its introduced in late 1980s to increase output light energy
to 800 mW / cm2
• It has narrow wave length of 470 nm which corresponds
to the peak area of absorption of camphoroquinone.
• It produces 60% conversion in 5-10 sec.
Advantages
• Superior to conventional light cure regarding bond strength. As
supported by Nazir Lalahl et al ANGLE 2000.They also found it causes
less than half the frequency of enamel # during debonding.
• It saves chair time.
Disadvantages
• Requires shielding appliance over teeth which are not
bonded.
• Cost.

Plasma arc or xenon arc lamp
• Introduced in 1990s .
• Light source is xenon gas that is ionized by 2 electrodes.
• The large white light is filtered to width of 450-500 nm.
• Power density can reach more than 2000 mW/cm2 which is
about 5 times more intense than halogen.

Xenon produced 53.8+ 2.7 in 1 & 2 sec & 69.7+5.5 in 3 sec.
It uses 1370 mw/ cm2. IT saves chair side time as supported
by Vittoriocacciofesta et al AJO-DO 2004 Aug
.


Light emitting diode ( LED )
• Introduced since 2000.
• It uses doped semi conducters to generate light instead of
hot filaments.
LED produces 54.9+ 3% in 20 sec
& 65.4+ 2.4 in 40 sec
• It has the wavelength of 468 nm.
Advantages
•
•
•
•
•

Has high lifetime of 10000 with little degradation.
Requires little power to operate.
Requires no filter to produce blue light.
It is resistant to shock & vibration.

TYPES OF BRACKETS
METAL BRACKETS
Usually made of SS , Gold coated or Titanium based .
Advantages
•Higher strength.
•Small & less noticeable bases helps avoiding gingival irritation.
Disadvantages
•Less esthetics
•Increased corrosion susceptibility as reported by
Tsui Hsein Huang et al in EJO 2004 Feb SS brackets has increased
amount of ions released & this increases with time over 48 week
period. ( Nickel being the most predominant metal released causing
Ni skin allergy)

PLASTIC BRACKETS
.Its introduced in 1969 by Newman as an esthetic
alternative.They are made of polycarbonate.
Advantages
•Esthetically superior.
Disadvantages
•Less strength to resist distortion & breakage
•Wire slot wear leads to loss of tooth control
•Low bond strength (3-6 Mpa )
•Water intake & Discolorations
•Need for compatible bonding resins

CERAMIC BRACKETS
They are machined from monocrystalline or polycrystalline
aluminium oxide .
They bond to enamel by
•Mechanical retention
•Chemically by means of silane coupling agents
Advantages
•Its rigid
•Esthetic
•Achieves higher bond strength especially chemically
curing brackets when used with composite resins.

Disadvantages
•Increased bond strength also causes increased debonding
stress causing bond failure to occur at enamel/adhesive
interface in EJO 1998
•Mechanically retentive base has higher bond strength when
cured with RMGIC
•Failure occurred at enamel/adhesive interface-60%and at
bracket / adhesive interface –40%
•Increase frictional resistance between wire & brackets
causes difficult force & anchorage control by Bishara AJO-DO

2000
•Less durable & brittle
•Harder than steel causing opposing enamel wear.Bowens&
Rodrigal et al reported mean linear tensile strength of enamel
is 14.5 MPa & enamel #occurs as low as 13.5 MPa

But ceramic brackets gain bond strength of 16-22MPa
•Because of rougher & porous surface it attracts more
plaque
GOLD COATED BRACKETS
Recently introduced
Advantages
1.
2.
3.
4.

Esthetic improved over metal brackets
Neater & Hygienic
Good patient acceptance
No significant side effects in form of corrosion or other
adverse effects has been observed yet


NEWER MATERIALS IN BONDING
Hybrid or Resin modified GIC ( RMGIC )
Its recently introduced.It has composite resin component that
gives increased strength.& with the added advantage if fluoride
releasing property.
But as per Fricker RMGIC is not recommended in case of
occlusal interference due to its decreased strength & brittleness.

EJO 2004 April according to S.B. Oliveria et al there is no significant
bond strength difference occurred when compared to composite
resin when used with light and medium arched wires. So RMGIC
is a viable alternative when used with light & medium arch wires.

In Aug 2004 AJO-DO by Andrew Summerset al concluded that
regarding bond strength highest is achieved by conventional
chemically cured composite followed by RMGIC & least by GIC

SHEIF ETCHING PRIMERS ( SEP)
Bonding usually contains 4 steps.
1.
2.
3.
4.

Cleaning..
Conditioning..
Primer application.
Adhesive application prior to bracket placement.

Use of self etching primers combines the conditioning &
priming into single step.
Composition:
It contains methacrylated phosphoric acid ester formed when
phosphoric acid& methacrylate groups are combined into a
molecule that etches & primes simultaneously.

Advantages
1. Decreases chair time
2 . Decreases technique sensitivity.
3. Bishara in AJO-DO 2001 reported that there are more adhesive
remaining on tooth surface after debonding when self etching
primer is used than with conventional etching
Disadvantages
1. It has significantly less bond strength when compared
conventional etching & priming 2 step procedure. Supported by

Aljibouri et al EJO 2003
2. Bishara in AJO-DO 2002 also concluded that SEP produces less bond
strength with are without saliva contamination.

His study showed that
SEP
Without saliva contamination
–6
Mpa Contamination before primer
– 4.8 Mpa
Contamination after primer
– 4.8
Mpa Contamination before & after primer – 1.7 MPa

Rielco yamada et al in ANGLE 2002 reported that composite resin
with SEP has less bond strength than when used with
conventional 2 step etching . But its comparable with that of
RMGIC after polyacrylic acid

RamKumar Gandhi et al in AJO-DO 2001 reported SEP produce more
bond strength with used light activated composite than with
chemically cured resin.

IN ANGLE 2002 SEP produces less enamel dissolutions than
phosphoric acid or polyacrylic acid . This might have led to
decrease in bond strength.

IN AJO-DO 2003 Ryan .W. Arnold et al showed no significant diff, in
bond strength occurred between SEP & conventional etching..


MOISTURE INSENSITIVE PRIMERS (MIP)
These are hydrophilic methacrylate monomer which acts even
in the presence of moisture contaminated enamel.
Bond strength is less than conventional phosphoric acid
etchant.


MOISTURE RESISTANT ADHESIVES
They act even in the presence of moisture. The main reactive
component is a methacrylate functionalised poly alkenoic acid
copolymer originally used as dentin bonding system.
Mechanism:
Excess interfacial water ionizes carboxylic group forming
hydrogen bonded dimers A reversible breaking & reforming of
calcium –poly alkenoic acid complexes with enamel providing
some stress relaxation capacity. Thus a dynamic equilibrium
occurs at the interface incorporating water in the process &
thereby minimizes the detrimental plasticizing effect of water.


MOISTURE ACTIVE ADHESIVES
These products requires rather than tolerate moisture for proper
polymerization A recent product based on cynoacrylate
formulation has demonstrated superior properties.
Mechanism:
First step- the iso cynate groups react with water forming an
unstable carbamic acid component which rapidly decomposes to
CO2 & corresponding amine.
Second step- Amine reacts with residual iso cynate groups
cross linking the adhesive through substituted urea groups.


Advantages
•Particularly useful in conditions where moisture control is
difficult like in Lingual bonding or while bonding surgically
exposed impacted tooth,.
Disadvantages
• Presence of excess water produce only the first step resulting in
formation of deleteriously brittle polymer films.
•CO2 released has only limited diffusion through the adhesive
films as polymerization proceeds & become entrapped forming
gap or voids with detrimental effects on interfacial strength


ADHESIVE PRECATED BRACKETS( APC)
To save chairside time there are brackets with precoated
adhesive.The adhesive differ in their composition by %age of
various ingredients incorporated

Bishara in ANGLE 2002 conducted a study where he found no
significant difference occur in shear bond strength with
precoated and uncoated brackets .APC brackets provide
clinically acceptable bond strength within first 30 min
uncoated brackets – 5.7+2.4MPa
APC brackets
- 5.1+1.7MPa


BONDING TO CROWNS & RESTORATIONS
AMALGAM RESTORATIONS & CROWNS
Methods used are
1. Modifying metal surface
2. Use of intermediate resin
3. New adhesive resins that bond chemically to non-precious as
well as precious metals
Recommended procedure
By Zachrisson in ANGLE 98 & AJO-DO 2000
1. Intra oral sandblasting amalgam alloy with 50 micron
aluminium oxide for 3 sec as supported by Sperder In AJO-DO

1999

2. If small restorations, then condition the surrounding enamel
with 37% phosphoric acid for 30 sec
3. If large restoration or in crowns create a window & restore it
with composite resin & continue the same process
4. Apply reliance or any metal primer that has 4-META & wait
for 30 sec
5. Bond with concise resin.


BONDING TO PORCELIN
Many in vitro studies has been conducted by Zachrisson &
many others which gave controversial results in clinical
practice.
Procedure
1. Surface is to be roughened with sandpaper discs
2. 8-9.6%HF acid gel applied for 2 min( HF is not effective
when bonding to high alumina porcelins & glass
ceramics)
3. Silane coupling agent is optional.In vitro studies shows
increased bond strength with silane addition.But clinically
silane produce insignificant support to bond strength
4. Use concise resin for bonding

AJO-DO 1998 Zachrisson showed HF produce extensive in
depth penetrating pattern .But diamond roughening &
microetching produce only surface peeling.
AJO –DO 2004 Mutlu Ozean et al superior bond strength is
obtained when ceramic surface is pretreated with silica
coating & silanization giving about 13.6 MPa particularly
with polycarbonate brackets. Bond failure site is at bracket /
adhesive interface.


BONDING TO GOLD
In vitro studies showed sandblasting & special primers with
4-META containing resin bonding provides good adhesion.
Tin plating improved bond strength only marginally
But clinically is still difficult to achieve good bond strength
when bonding to gold

Gloria Nollie et al in ANGLE 1997 reported that Type –1V gold
treated with adlloy has increased bond strength & gives twice
as strong as those found in microetched gold.


INDIRECT BONDING
It was first introduced by Silverman& Cohen in 1974.They
used methylmethacrylate adhesive to attach to plastic
brackets to model cast in laboratory.An unfilled bis-GMA
resin was used as an adhesive between etched enamel &
previously placed adhesive.
Advantages
1. More accurate bracket positioning

AJO-DO 1999 by Bonchankoo et al concluded that indirect
technique has better bracket placement in vertical
position,but no significant difference occurred in
angulation or mesiodistal position.

2. Decreased chairtime

AJO-DO 1982 by Michael Aquirre et al showed that avg,
time needed for direct technique – 42.18 mins & for
indirect technique – 53.73 mins with only 23.91 mins
representing actual clinical time
3. Increased patient control
4. Its superior in lingual bonding where visualization is
difficult


Disadvantages
1. Technique sensitive
2. Increased lab time
3. Risk of adhesive leakage to gingival embrasure could
lead to difficult oral hygiene management.ANGLE 2004 by

Polatkaramen et al.
4. Removing adhesive is difficult to achieve & time
consuming
5. Achieving consistent & predictable adhesion is difficult.
6. Accidental removal of brackets with tray is not unusual.
7. Adequate bond strength shortly after sealant application
is mandatory.(To withstand force during tray removal )
8. Failure rates are slightly higher – Zachrisson &
Brobakken

9. Less disturbance during adhesive polymerization is
difficult to achieve
10. Closer fitting of bracket base is better achieved by one
point contact of scaler in direct bonding than when transfer
tray should be held in place by finger pressure in indirect
bonding.

BOTTOM LINE – WHEN CORRECT TECHNIQUE IS USED WITH
EXPERIENCE FAILURE RATES WITH DIRECT & INDIRECT TECHNIQUE
ARE WITHIN CLINICALLY ACCEPTEBLE RANGE


Clinical procedure
Many techniques are available which differ by
•The way brackets are attached temporarily to models
•Type of transfer tray
•Adhesive or sealant employed
Indirect bonding using silicone transfer tray :
Procedure:
• Patients stone model is marked
for long axis & vertical height
•Water soluble adhesive is placed
on bracket base or model &
bracket is positioned accurately

•Mixed silicone putty material
is pressed onto the cemented
brackets & tray is formed with
sufficient thickness for strength
•
•After silicone sets model &
tray are immersed in hot water
to separate brackets from
model.Remaining adhesive is
removed under water
•Patient s teeth are prepared as
per direct technique.
•Adhesive applied to bracket
bases

•Tray seated on patient s arch & held firmly with steady pressure
for 3 mins
•After 10 mins tray is cut & removed
•Any excess adhesive is removed


Indirect bonding with double sealant technique :
• Here adhesive is placed on bracket base to fix temporarily to
models.Excess removed.
• After 10 mins a placement tray is vacuum formed & placed
with models in water until thoroughly saturated.
• Trays are separated & trimmed so its gingival edge is within
2 mm of brackets
• The bracket bases are lightly abraded with a stone point.
• Patient s teeth are prepared
• Brackets are painted with catalyst sealant resin& enamel
surfaces are painted with universal sealant resin.
• Tray is inserted , seated & held for 3 mins
• Tray is peeled off from lingual to buccal
• Excess Flash removed

The above technique is called Thomas technique& introduced
in1979.Many criticism arrived stating that curing of sealant
might be incomplete.
So later arrived a modified Thomas technique which uses a
sealant that is mixed just before placing transfer tray on to the
tooth that ensures complete mixing of the 2 components of
the sealant..
.In ANGLE 1993 Jing-Yi- Shiac et al reported that Thomas
technique creates an interface between the old (aged)
composite& sealant which is not present in other
techniques.This might create marginal voids which when not
covered by sealant might result in 50% reduction in bond
strength.

JCO 1996 M.Moskowitz et al using Light vinyl polysiloxone
impression material


JCO Michael Read & Pearson using Memosil CD


LINGUAL BONDING
This is a recently invented technique introduced for
patients particularly adults who are highly esthetic consious
Fujita of Japan was a pioneer in lingual bonding
Advantages
• Esthetic
• Enamel demineralization is better controlled & of less
consequence
• Precise detailing of tooth position can be made without
the distractions of wires & brackets.
• Lip posture seen correctly instead of being artificially
determined in front of incisors

Disadvantages
•Technique sensitive
•Time consuming
•Awkward working position
•More precision necessary for adjustment of arch wires
•Decreased interbracket distances
•Good active ligation us difficult

•Ariane hohoff et al in AJO-DO 2003 concluded that lingual
orthodontics induces significant speech performance impairment
& oral discomfort.Smaller the appliance lesser the impairment &
so customized brackets are recommended.

REBONDING
More time consuming & uncomfortable for orthodontists is
loose brackets during treatment.
Clinical procedure
The loose bracket is removed from arch wire.Ligatures of 2
neighboring brackets are cut & arch wire is placed on top of
these brackets.
. The adhesive remaining on tooth surface is removed
Adhesive on bracket is removed with bur or slightly
roughened .Do not burnish mesh backing
Tooth is etched for 60 secs sealed & bracket rebonded.
Total time should not exceed 3 mins

Effect on enamel by various rebonding procedure

Unetched & etched enamel

Re etched enamel with
adhesive remnant


After scaling as a
rebonding procedure

After scaling and re
etching as a rebonding
procedure

After scaling ,prophylaxis
& re etching

After finishing bur & re
etching


After green stone & re etching

After green rubber wheel &
re etching


RECYCLING
Main goal of recycling process is to remove the adhesive from
bracket base without damaging or weakening the delicate foil
mesh or distorting the dimensions of bracket slot.
Some methods used are:
•Applying heat about 450 c to burn off the resin followed by
electro polishing ( to remove tarnish & oxide)
•Solvent stripping followed by high frequency vibrations
with only flash electro polishing
•Recycling with sandblasting
•Recycling with microetching

Advantages
• Cost effective

•EJO 2004 by Victoria Cacciafesta et al reported after 12 month in
vivo trial that there is no significant difference in bond failure
rate occurred between recycled& new SS brackets.
•In ANGLE 1995 Peter .G.Gaffey et al reported electro thermal
recycling resulted in bond strength greater than 9 MPa
which is clinically acceptable


Disadvantages
1. It results in decreased bond strength.
Supported by Chan Hsi Chung et al in AJO-DO 2002. They also
concluded that sandblasting debonded brackets gave acceptable
bond strength .Silane does not improve & HF acid actually
decreases bond strength.

In AJO-DO 1998 by James.K.Grubouski et al reported significant
decrease in bond strength occurred when microetching is used

Bishara also concluded shear bond strength considerably
decreases with repeated bonding


2. Decreases corrosion resistance

EJO 2004 Feb. by TsuiHsein Huang et al reported that recycled SS
brackets release more ions than new ones.


DEBONDING

Aim:
To remove the attachments & all adhesive resin from the
tooth & to restore the surface as closely as possible to its
pretreatment condition without inducing iatrogenic damage
Procedure:
1. Bracket removal ( SS )
First method with pliers:
Squeezing the bracket wings mesiodistally using tips of
weingart pliers& bracket removed with applying peel force.
Advantages
•Gentler technique
•Useful on brittle, mobile or endodontically
treated tooth

Disadvantages
•Bracket deformed & so can not be reused
•Break likely to occur at adhesive / bracket interface
leaving more adhesive remnant- By Bishara AJO –DO 1999
Second method with band remover.
Still ligated in place brackets are gripped with anterior band
removed & lifted off outwardly at 45 degree angle.
Bracket removal - ceramic brackets:

Bishara et al in 1994 ANGLE proposed that Modified diametrial
compression using debonding pliers requires the application of
30 % less force to enamel than when using shear force to
remove ceramic brackets .

Brackets using mechanical retention can be safely removed
with a peripheral force applied to gingival tie wings using an
ETM 346 RT or similar plier.
But brackets using chemical retention requires a wrench
type instrument & using a torquing force.
Thermal debracketing is another method which contains
application of controlled heat to resin that bonds the
brackets.
• Powder – liquid material has significantly lower debonding
temperature of about 45 degree C
• No mix paste requires 60-170 degree C

2. Removal of residual adhesive
Accomplished by
1. Scraping with super sharp band or bond removing pliers
or with a scaler – produces significant scratch marks


2. Using TC bur at 30,000 rpm with contraangle hand piece


3. Brain.W. Thomas et al in ANGLE 1996 proposed a new
technique to remove residual resin using laser aided
degradation .When resin is lased with Nd :YAG laser
energy at 100 Hz showed 75 % decrease in compressive
strength of the resin.
Enamel surface at 1200x
magnification without
being lased.

Enamel surface at 1200x
magnification after 3 sec
lasing


INFLUENCE ON ENAMEL
By proposing ESI ( Enamel Surface Index ) with scores 0 to
4 Under SEM Zachrisson & Artun compared influence on
enamel by different debonding instruments.

• Hand scaler produces
highest roughness( By Double

Rix et al in AJO-DO 2001 )


Score 4 – diamond instruments
Score - 3
By medium sand paper disk

By green rubber wheel


Score 2- Fine sand paper disk
Score 1-Oval plain cut & or Spiral fluted TC bur.
Final pumicing treatment found to be beneficial
Although it did not remove any deep scratches.


Amount of enamel loss during Debonding :
Depends on
• Types of instruments used
• Type of primer & resin used
• Bond failure interface.
For prophylaxis-With bristle brush – 10 millimicron enamel is lost
With rubber cup – 5 millimicron enamel is removed.
Resins - Unfilled – 5 to 8 millimicron lost with hand instruments
Total loss of enamel is 20 to 40 millimicron .
Filled – 10 millimicron with low speed TC bur.
20millimicron with high speed bur & green
rubber wheel.
Total of 10 to 25 millimicron with rotary instrument

Additional deep reaching enamel tearouts down to a depth
of 100 millimicron & localized enamel loss of 150 to 160
millimicron have also been reported.

EJO 2004 Elliets et al proposed diamond bur is better than bladed
bur in view of debonded enamel surface.

ANGLE 2004 by Rangasamy Rajagopal showed that MIP & SEP
under moisture contamination produce bond failure at bracket /
adhesive interface which results in les enamel damage .
But conventional etchant under moisture contamination
resulted in bond failure at enamel/ adhesive interface leading to
more enamel damage.

Enamel tearouts.
It is likely to occur with resins having small filler particles.
Might be due to greater penetration depth with small particles.
Upon debonding small fillers would reinforce the adhesive tags. &
bond failure occurs at bracket adhesive interface.
Enamel cracks.
They occur as split lines in enamel.A shap sound sometimes
heard upon removal of bonded brackets could be reflected in the
creation of enamel cracks.
• Vertical cracks are more common .
• Few horizontal & oblique cracks are observed.
• More noticeable cracks are in upper central incisors & canines0

BOND STRENGTH
Definition : It’s the force obtained at bond failure divided by
superficial surface area
FACTORS AFFECTING BOND STRENGTH :
1.Improper procedure:
•Pumicing has no effect on composite resin but decreases
bond strength significantly with the use of RMGIC
2. Moisture control:
•Presence of water or saliva or blood contamination
significantly decreases bond strength. Possible
mechanism is presence of high mucous protein content &
enzymes in saliva would likely result in increased
degradation of reactions in the adhesive & this affect
bond strength

ANGLE 1999 by Talconi et al reported water contamination
decreases bond strength to etched & unetched enamel using
RMGIC for short aging times . For unetched enamel saliva
was less deleterious than water regarding bond strength .

AJO-DO by Ross & Hobson reported that though moisture &blood
contamination decreases bond strength Transbond MIP is a
suitable adhesive for bonding conditions of poor moisture
control.
•Bond strength at dry condition: 15.69 MPa
After contamination
: 12.89 Mpa
After blood contamination
: 11.6 MPa


EJO 2000 for RMGIC etched surfaces Contaminated with
saliva actually increases bond strength & plasma still increase s
it.But it is not significant .So RMGIC has acceptable bond
strength regardless of enamel surface.

ANGLE 2004 Somsak Kayo et al showed saliva contamination of
SEP did not cause any significant decrease in bond strength

AJO –DO 2004 Aug by Vittorio Cacciafesta et al showed blood
contamination decreases bond strength with conventional
as well as moisture insensitive primer & produces
clinically inadequate bond strength .
Even time of moisture contamination affects bond strength
differently.If it occurred before primer application bond
strength decreases considerably than when when it occurs
after primer application.

3. Types of primer used
•Conventional etching & priming 2 step procedure highest
bond strength . Its followed by SEP. MIP gives the least bond
strength.
• Bishara in ANGLE 2002 concluded that fluoride releasing SEP
has significantly lower shear bond strength than conventional
2 step procedure.


4. Types of adhesives used
• Composite resin gives highest bond strength . Its followed
by RMGIC . 1st & 2nd generation GIC gives least bond
strength.
• Cook in 1990 reported up to 12 % failure rate observed
with GICs when used in upper anteriors which has least
occlusal interference
5. Time of curing:
• AJO-DO 1999 By Akra Kumori et al : Delayed exposure decrease
bond strength. Its affects LCC more than RMGIC
• AJO-DO 2000 By Bishara et al :Increasing curing time for
additional 5 – 10 sec increases bond strength of RMGIC

6.Location of brackets:
• Bracket failure is more common in lower arch than in
upper arch
• Posteriors are more susceptible than anteriors
• Premolars has highest prevalence for bond failure.
• Upper incisors are least affected.
• Bond failures are more in crowded teeth with complex
design than spaced teeth with simpler design.
7. Types of brackets used:
• Ceramic brackets yield highest bond strength .
• Metal brackets has comparable bond strength.
• Plastic brackets yield lowest bond strength.


8. Types of brackets bases:

AJO-DO 2004 by Wang et al :
TOMY bracket base with
circular concave discs
showed highest bond strength

Bracket base with horizontal
retention grooves concave
moderate bond strength


Conventional bracket base with larger mesh spacing
produce better bond strength


Bishara In ANGLE 2004 June:
Single mesh bracket base
gives 5.2 + 3.9 MPa bond
strength.

Double mesh bracket base
gives 5.8 + 2.8 MPa bond
strength.

The difference is not significant.

Oliver Sorrel et al in AJO-DO 2002:
Reported laser structured bracket base provides 2 times higher
bond strength than simple foil mesh. Also bond failure likely
to occur at enamel / Adhesive interface but with acceptable
enamel damage.

Major & smith et al in AJO-DO 1981:
• Weld spots could decrease retentive areas.
• Weld spurs could decrease bond strength with foil mesh bases
• Weld spurs at edges should be avoided to increase resin mesh
seal
• Best resin penetration is obtained with a fine mesh of woven
type.

Matasha in Orthodontic materials :
He suggested to increase bracket performance use of proper
primer would help to wet the surface of the base & invite the
adhesive to pass through mesh .It also decreases air trapping.
9.Recycled brackets:
Recycled brackets has decreased bond strength.
10.Other products application
• Todd kimura et al in AJO –DO 2004reported application
of fluoride varnish did not affect bond strength
significantly when etched either with conventional or
SEP.

• Ching Liang Meng in AJO – DO 1998 reported APF
application after itching to prevent enamel demineralization
decreases bond strength.
11. Miscellaneous
• Bishara in ANGLE 2000 : Removing excess adhesive after 5 sec
of light curing to initially secure the brackets decreases bond
strength significantly.

• Newman in Angle 2001 reported that micro etching bracket base
and use of adhesion promotors to enamel like Pyromellitic
glycerol dimethacrylate increase bond strength


EFFECTS OF BONDING ON TEETH
& PERIODONTIUM
White spot lesions (WSL )
They are early carious lesions first seen as white spots
in caries susceptible region usually around bracket margin
especially in gingival 3rd of teeth.
Treatment with fixed appliance makes conventional oral
hygiene for plaque removal more difficult & thus
increases cariogenic challenge on surfaces that normally
show low prevalence for caries.


ANGLE 2000
WSL – In non treated patients: 3% to 82%
In treated patients
: 8.5% to 44% in anteriors.
7.7 % to 81% in posteriors.
Zachrisson – enamel etching removes outer surface
which is better in absorbing fluorides.Also it exposes
more susceptible subsurface to oral environment.

AJO 1998 by Bronwen et al reported RMGIC adhesives
minimize enamel demineralization.

EJO 1997 by Agneta Marasson et al reported WSL are less
when GIC is used than with diacrylate.


Effect on Periodontium;
Excess adhesive especially in gingival 3rd of tooth causes
inflammation of periodontium & remains throughout
treatment.

AJO-DO 1999 by Alex .T.H. Hang et al reported that
polymerization of bonding resins is compromised at
atmospheric oxygen, giving rise to a layer of low molecular
wt, chemical species known as oxygen inhibited layer
which was found to be cytotoxic to human fibroblast.


AJO-DO 1999 by Kent.L, Knoernschild et al demonstrated
P.gingivalis, E.coli lipopolysaccharides exhibit a high
affinity for orthodontic brackets especially SS when
compared with ceramic , plastic or gold brackets.This
increases inflammation of tissues adjacent to brackets.


Simplicity of bonding can
be misleading . Success in
bonding requires
understanding of and
adherence to accepted
orthodontic and preventive
dentistry principles.


Thank you
For more details please visit


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

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