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

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BONDING IN ORTHODONTICS– II
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

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CONTENTS
1. Evolution of bonding agents
2. Banding
3. Indirect bonding
4. Bonding to special surfaces
5. Bond strength
6. Debonding
7. Decalcification and
demineralization

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EVOLUTION OF BONDING MATERIALS
“An appliance which
cannot be made
transparent or tooth-
colored should at least be
made smaller.”

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Schange’s adjustable clamp band Angle’s retraction screw
1871 - W.E. MAGILL – Zinc oxycloride

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 Laborious, time-consuming, skill
 Partially erupted teeth
 Decalcification /discoloration
 Gingival irritation
 Unaesthetic
 Need of separators
 Closure of band spaces – “What you see is not
what you get”

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3 major developments that made bonding of
attachments to teeth possible –
1. BUONOCORE 1955 – improved retention of
methyl methacrylate to enamel – 85% phosphoric
acid for 30 seconds
2. BOWEN 1962 – bis Glycidyl methacrylate –
more stable and greater strength
3. NEWMAN 1965 – first to acid etch and bond
orthodontic brackets with epoxy resin

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Orthodontic attachments had to be cemented on
teeth instead of the intermediary bands-
 Methylmethacrylate monomer –MMA – first
material to be used
 Catalyst – Benzoyl peroxide –BPO
 Powder-liquid system
 In use in restorative dentistry
•Poor adhesion - Polymerization shrinkage
•Pulpal irritation

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BUONOCORE (1955) –
 Improved retention of methyl methacrylate to
enamel – 85% phosphoric acid for 30 seconds
 Not successful for orthodontic purposes –
• Occlusal force
• Wide range of oral thermal change
• Wet environment

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G. V. NEWMAN (1965)
 Bonded plastic brackets with epoxy resins
 Start of direct bonding procedure
 For short-term treatment with anterior brackets
 Did not replace ‘metal-band’ system

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First commercially available orthodontic adhesives
1. OIS Adhesive system – OIS company in 1969
2. Bracket Bond – GAC in 1970
 MMA -BPO-amine catalyst system
 Weak Adhesion
 Early 70s - all adhesives consisted of MMA - it
bonded chemically to plastic brackets – in vogue

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Fujio Miura and associates in 1971 –
 Introduced – ORTHOMITE
 MMA - Tri–N–Butyl Borane (catalyst)
 Increased adhesive strength
 Coupling agent – ‘silane’
methacryloxypropyltrimethoxysilane
 Increased adhesive penetration
•Chemically bonded to adhesive
•Affinity to enamel

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Merits of MMA adhesives:
1. Plastic brackets
2. Good storage stability
3. Increased working time – brush-on / dip-in
4. Elimination of sealant - good penetration into
enamel surface
5. Less damage during debonding

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Demerits of MMA adhesives:
1. Fluctuating proportion of powder-liquid
depending on operator
2. Poor mechanical interlocking to metal bracket
bases

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Metal brackets enter the scene
 Plastic – worry about enamel-adhesive
 Enamel-adhesive & adhesive-bracket
Adhesive-bracket -Mesh, perforated pad , foil mesh
Enamel-adhesive –
•Increased hardness of adhesive
•MMA BisGMA
•Filler material - TEGDMA

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Bisphenol Glycidyl Dimethacrylate (Bis-GMA)
 BOWEN 1962
• Greater strength
• Lower water absorption
• Less polymerization shrinkage
 2-paste system
 Strongest adhesives for metal brackets

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FILLERS:
 Reduce viscosity of resin
 Reduce polymerization shrinkage
 Quartz, silica glass particles
 3 - 20 microns - abrasion resistance
 0.2 – 0.3 microns - smooth surface - less plaque
retention
Adhesives with large particle fillers recommended
for extra bond strength, but careful removal of
excess is mandatory

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Di/triethyl glycol dimethacrylate (TEGDMA)

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 Merit and demerit of Bis-GMA – hardness
 Poor penetration due to increased viscosity –
dilute with MMA
 Plastic brackets could not be used – primer for
partially dissolving added
 Active life less than powder liquid system

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 In 1974 – ORTHOMITE II – 20% more
 HNPM –
hydroxynapthoxypropylmethacrylate
 Eliminated silane
 4 - META – methacryloxyethyl trimellitate
anhydride
 ORTHOMITE SUPER BOND

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4 - META
 Plastic & metal
 PRE-PRIMED brackets
 Base was primed with adhesive
 Bracket base covered with PMMA powder
 Base dipped in monomer and pressed onto
etched surface.
 Bond strength less than manual application

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Orthodontic adhesives are variations of-
 Adhesives
 Direct-restorative materials used in
restorative dentistry
Late 20th
century –direct restorative biomaterials
1. Resin-matrix – originated in U.S.
2. Salt-matrix – U.K.

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1. RESIN MATRIX:
Classification -
According to organic matrix components -
A. Acrylic resins – MMA Ex. ORTHOMITE, GENIE
B. Diacrylate resins- BisGMA Ex.CONCISE, PHASE II
According to polymerisation mechanism –
A. Chemically activated
B. Light-cured
C. Dual-cured
D. Thermocured

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A. CHEMICALLY ACTIVATED:
 Chemically-cured/ Auto-cured / Self-cured
 Used since beginning of bonding
 Most-widely used ortho adhesives
 Two-paste / one-paste
 Two-paste system:
 Initiator- Benzyl peroxide in monomer
 Activator- tertiary amine – dihydroxyethyl –p-
toluidine

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Ex. Concise (3M)
 Good bond strength
 Laborious
 Time-consuming
 Increased air-exposure- oxygen inhibition
 Defects – air entrapment, voids

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One-paste system:
 One adhesive component applied to bracket base
and other on tooth surface – catalyst gradient
 No-mixing
 Bracket positioned accurately - pressed firmly
into place
 Curing occurs – 30-60 secs
 Ex. Rely-a-bond, System 1+, Unite

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 Procedure simplified
 Fast
 Efficient
 Little long term information available on bond
strength
 Inhomogeneous polymerisation – sandwich
technique
 Enamel and bracket side more polymerized
 Liquid activators – toxic, allergic reactions

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B. LIGHT-CURED:
Visible-light cured
Camphoroquinone
Cure from incisal and gingival areas
 Increased working time
 Ideal for educational purpose
 DC same as Chemical-cure; same for metal
and ceramic brackets
 Photocuring time-consuming

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C. DUAL-CURED:
Intiation – exposure to light
Propagation – chemically cured
 Advantages of light and chemically cured
 Improved surface and bulk material properties
 Highest DC, bond strength
 Ideal for bonding molar tubes
 Most time-consuming
 Bulk defect due to mixing

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D. THERMO-CURED:
 Exposure to heat
 Superior properties
 Not for direct but only indirect bonding

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Adhesives acting in the presence of water –
1. MOISTURE-RESISTANT –
- can bond in presence of water
- saliva, gingival fluid – contaminants
- ex. Transbond MIP
2. MOISTURE-ACTIVE –
- need water for bonding
- enamel surface intentionally made wet
- Cyanoacrylate – no liquid, only paste
- ex. Smartbond

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CYANOACRYLATES:
 Ethyl-cyanoacrylate – Smartbond-orthodontic
bracket adhesive (1991)
 Other uses
•Automobiles,Circuit boards,Light aircraft
•Fracture fixation
•Skin sutures
•Cardiac surgery
•Guided tissue regeneration

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 Crabb and Wilson – 1971- compared with
polycarboxylate cement – poor
performance and bond strength,
unsuitable for clinical use
 Howells and Jones – 1994 – poor
performance on storage in saline for a
week
 Krishnan et al – 1994 –equal to Bis-GMA
when kept in 37o
C for 24 hours

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 THOMAS W. - JCO 2000 - Compared the shear
bond strength and debonding effects of Smart-
Bond & Rely-a-bond
•Smart-Bond’s strength was significantly
higher
•No danger of fracturing the enamel
•Polycarbonate bracket - work only if they
are pretreated with water

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Ideal characteristics of Bonding medium:
1. Non-toxic
2. Adequate working and setting time
3. Moderate viscosity
4. Ability to wet etched surface
5. Sufficient tensile and compressive strength -
retain bracket & ease of debonding
6. Resist decomposition in the oral environment
7. Antimicrobial

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Evaluation of antimicrobial properties of
orthodontic composite resin combined with
benzalkonium chloride
Othman et al,AJO Sep2002
 The antimicrobial agent benzalkonium chloride
added to a chemically cured composite resin
 Anti microbial benefits and bond strength of the
modified composite were evaluated.

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Results:
 No significant difference between the tensile
bond strength between modified composite and
the original product
 The incorporated BAC added to anti microbial
properties of original composite without
altering it’s mechanical properties

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2. SALT MATRIX:
CEMENTS IN ORTHODONTICS:
Desirable properties:
1. Adequate working and setting time
2. High tensile, compressive and shear stress
3. Resistant to dissolution
4. Clinically acceptable bond strength
5. Low Adhesive Remnant Index (ARI) on
debonding
6. Anticariogenic potential

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ZINC PHOSPHATE:
 Oldest of the luting cements
 Powder and liquid system
 Film thickness of 20 microns
 Efficient mixing characteristics
 Mechanical adhesion
 Pulpal irritant - highly acidic
 May cause decalcification of enamel resulting
in white spots

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ZINC SILICOPHOSPHATE:
 Addition of silicate glass
 Superior strength and fluoride releasing property
 Extremely acidic
 High solubility
 No longer used

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ZINC POLYCARBOXYLATE CEMENT:
 Introduced by Smith in 1968
 First cement system that developed a chemical
bond to the tooth structure.
 Early 70s –Durelon – poor bond strength
 Combined desirable properties of Zn-
phosphate & ZOE

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 Acid-base reaction
 Chemical bond to tooth
 Fluoride release
 Shorter setting time
 Viscous liquid – less efficient mixing
characteristics - PSEUDOELASTIC

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GLASS IONOMER CEMENTS:
 Developed and introduced in 1974 byWilson, Kent
and Smith.
 To combine strength and fluoride release of
silicophosphate and adhesive efficiency of
carboxylate
 Group of materials that use silicate glass powder
and an aqueous solution of Polyalkeonic acids

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Setting reaction:
 Surface of glass particles is attacked by acid
 Ca, Al, Na, Fl ions-leached into aqueous medium
 Next 24 hours a new phase forms in which
aluminium ions become bound within the cement
matrix leading to a more rigid set cement
 NaF uniformly dispersed in the set cement.
 Unreacted portion of glass particles sheathed by
silica gel.

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 Unreacted powder particles surrounded by a
silica gel in an amorphous matrix of hydrated
Ca++ and Al+++ polysalts.
 During initial reaction if mix contaminated by
additional water or ambient air - dissolution of
matrix - weak and more soluble cement
 Adhesion- chelation of carboxyl groups of
polyacids with Ca in apatite of enamel & dentin

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Biological properties :
 Chemical adhesion
 Bacteriostatic or bactericidal due to fluoride
release.
 Acid - less irritating to the surrounding tissues
 Enamel etching for luting bands not required
 Reduces demineralization
 Highest strength
 Least solubility
 Bonds to enamel and base metals

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Drawbacks:
 Moisture sensitivity
 Low early strength
 Polymerizable resin functional groups added
 Impart additional curing process
 Allow the bulk of the material to mature
through the acid-base reaction.
RESIN MODIFIED GLASS IONOMER CEMENT

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Nicholson (Quint Int 1977)
“Resin modified GIC’s are those materials that
are modified by the inclusion of resin, generally
to make them partly photocurable”
W.M. Tay (Dental update 95)
“These are hybrid materials that retain
significant acid base reaction as a part of their
overall curing process”

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Advantages of RMGIC’s over GIC’s:
1. Sufficiently long working time controlled in
command to a snap set by photocuring.
2. Improved setting characteristics.
3. Protect the acid base balance from problem of
water balance.
4. Rapid development of early strength.
5. Fluoride release greater.
6. Diametral strength high (20 Mpa compared to 6. 6
Mpa)

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Disadvantages of RMGIC’s over GIC’s:
1. Biocompatibility is controversial.
2. Setting shrinkage is higher leading to
increased microleakage and poor marginal
adaptation
 Brands
• Fuji Ortho LC
• Photacfil – ESPE
• Vitrebond – 3M

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In 1986 – White described a method of bonding
orthodontic brackets to the enamel surfaces of
teeth, with a glass ionomer cement.
 Poor strength
 Isolation of newly bonded teeth
 Light arch-wires immediately after bonding

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Bond strength and durability of glass ionomer
cements used as bonding agents - AJO July 1989
-Klockowski, Davis, Joynt, Wieczkowski, and
MacDo
 Compared GICs (Ketac-fil, Ketac-cem and
Chelon) with Rely-A-Bond (no-mix
autopolymerising) which served as a standard
in a clinical study.

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Results:
 Bond strength of GICs was significantly less
when compared to Rely-A-bond.
 Less reduction of bond strength of GICs on
recycling – lesser than Rely-A-bond on recycling
 Failures involved cohesion within cement or
adhesion involving the enamel - easily scraped
off from the enamel surface without causing
much damage.

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 Cook -1990 compared the in vivo bond
strength of a glass ionomer cement, Ketac
(ESPE Premier Denbol Products, Norristown,
Pa.), with a composite resin bonding agent –
12% failure rate
 Fajen et al- 1990 evaluated the bond strength
of three glass ionomer cements against a
composite resin in vitro

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 Fricker - 1994, worked with Fuji II LC glass
ionomer cement (GC Corp., Kyoto, Japan) –
•Same rate of success bonding brackets to
enamel surfaces as he did with composite
cements.
•Dentine conditioner was utilized for ten
seconds

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 Kusy - discussed the damage to teeth on
debonding after using composite bonding resins.
•“When is stronger better?”
•Use of glass ionomer cements for
orthodontic bonding procedures - do not
need etching or damage the enamel during
debonding.

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A new light-cured glass ionomer cement that bonds
brackets to teeth without etching in the presence of
saliva -AJO-DO SEP 1995
-Silverman, Cohen
 Used a new Resin modified GIC
 Fuji Ortho LC
 Light-cured, resin-reinforced glass ionomer
cement
 3 mechanisms of setting

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Advantages:
 Saves significant amount of chair time.
 Eliminates working in a dry field.
 Eliminates etching and priming enamel
surfaces.
 Fluoride release protects teeth against
decalcification.
 Repairs are quick and easy.
 Increased patient and operator comfort.

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Evaluation of fluoride release from an orthodontic
bonding system – AJO-DO Aug 1991
-Samir E. Bishara, Edward J. Swift, Jr., Daniel C.
N. Chan,
 Light-activated fluoride-releasing - FluorEver
OBA
 Tensile bond strength was significantly less – 1/3
– 1/2 of conventional (chan et al)

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 Fluoride ion release – 2.6ppm on day 1
0.42ppm on day 2
0.04ppm on day 43
 However , decrease in enamel
decalcification was observed.

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BANDING
“Feel the pinch”

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Advantagesof banding
 Stronger
 Protect against interproximal caries
 Easier to recement and deband
1. CUSTOM-MADE
• Indirect
• Direct
1. PRE-FORMED

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1. CUSTOM-MADE BANDS:
1. Band-pinching
2. Band-cementation
1. BAND-PINCHING:
 ‘Food-trap for cariogenic debris’
 Exacting proximity between tooth and band
 Poorly fitting band – ‘island in a sea of
cement’.
BANDING PROCEDURE

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BAND MATERIAL:
Precious metal
Chrome-cobalt alloy
Stainless steel
Size:
Thickness Width
Incisors 0.003 – 0.004” 0.125”
Premolars & Canines 0.004” 0.150”
Molars 0.005 – 0.006” 0.180 – 0.200”

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REQUIREMENTS:
1. Greatest strength and
durability with minimum of
bulk
2. Soft enough to permit close
adaptation
3. Strong enough to withstand
stresses
4. Polishable
5. Corrosion and tarnish resistant
6. Biocompatible www.indiandentalacademy.com

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2. BAND-CEMENTATION:
Do not depend on cement for retention
‘Drive fit’

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Universal scaler parallel to band margin and
not perpendicular

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2. PRE-FORMED BANDS:
Band selection:
 Casts
 Variations – anatomy, tapered crowns, extra
cusps, restorations
 One size larger than the one that seems to fit
the tooth – prevents wasteful distortion of
bands

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Band fitting:
 First - finger pressure - only on mesial and distal
sides
 Amalgam plugger / band pusher – 2/3rd
 Bite pressure through biting stick – facial and
lingual
 Final seating pressure –
•Maxillary – palatal side of tooth
•Mandibular – buccal side of tooth

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Checklist:
All cusps on banded teeth equally visible
Band margin –
•Just below marginal ridge
•Above the contact point
Buccal attachment accurately positioned
Open occlusal margins crimped towards tooth

www.indiandentalacademy.com 78
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Bonding in orthodontics /certified fixed orthodontic courses by Indian dental academy

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