BONDING IN ORTHODONTICS

1. BONDING IN ORTHODONTICS
Dr Jupitha Grace Podimon
PG Orthodontics
1

2. CONTENTS
• Introduction
• History
• Materials and Devices Used in Orthodontic
Bonding
• Brackets
• Ceramic Brackets
• Metal Brackets
• Adhesives
• Composite Resins
• Glass Ionomer Cements
• Light Sources
• Light-Emitting Diodes
• Bonding to Enamel
• Cleaning
• Enamel Conditioning
• Sealing and Priming
• Indirect Bonding
• Bonding to Artificial Tooth Surfaces
• Bonding to Porcelain
• Bonding to Amalgam
• Bonding to Gold
• Bonding to Composite Restoratives
• Bond Failures
• Rebonding
• Conclusion
2

3. INTRODUCTION
• “Bonding is mechanical locking of an adhesive to irregularities in the enamel
surface of the tooth and to mechanical locks formed in the base of orthodontic
attachment.”
• Successful bonding depends on three components
•Tooth surface & its preparation
•Design of attachment base
•Bonding Material
3

4. 4
HISTORY

5. YEARS AUTHORS IMPORTANT EVENTS
1955 Buonocore Introduced etching tooth surfaces with phosphoric acid—85%
phosphoric acid for 30 s
1962 Bowen Bowen’s Resin—bisphenol A-glycidyl dimethacrylate
1965 Newman Epoxy resin bonding orthodontic resins—diglycidyl ether of bisphenol-A
with a polyamide curing agent
1968 Smith Bracket bonding with zinc polyacrylate cement
1971 Miura et al Acrylic resin (orthomite)
1972,
1976
Silverman and
Cohen
Pioneers of indirect bonding technique
1973
1974
1977
2005
2010
Retief
Silverstone
Gorelick
Zachrisson and
Büyükyılmaz
Øgaard and Fjeld
Üs¸umez and
Erverdi
Etching modifications:
50%phosphoric acid
concentration
30%–50% phosphoric acid
concentration
35%–38% orthophosphoric acid
5

6. YEARS AUTHORS IMPORTANT EVENTS
1977 Zachrisson First detailed published large sample data on posttreatment
evaluation of direct bonding
1979 Takao Fusayama Total etch technique
1979 Maijer and Smith Crystal growth technique
1982 Nobuo Nakabayashi Resin reinforced hybrid layer
1992 J. Kanca et al. Moist bonding technique
1993
1997
2007
Hermsen and Vrijhoef
Olsen and Bishara
Bas -Kalkan and Orhan
10% Maleic acid, polyacrylic acid as etchants
1999 Sondhi A Sondhi Rapid-Set Indirect Bonding Adhesive 6

7. Bonding of orthodontic attachment offers
many advantages when compared to
conventional banding
• It is esthetically superior.
• It is faster and simple.
• There is less discomfort for the patient
• Arch length is not increased by band material by the
presence of band material on proximal surfaces of
teeth
• It allows more precise bracket placement.
• Bonds are more hygienic than bands. 7

8. • Partially erupted teeth can be controlled.
• Mesiodistal enamel reduction ( proximal reduction) is possible during treatment.
• Attachments may be bonded to artificial tooth surfaces (eg., amalgam, porcelain,
gold) and to fixed bridge work.
• Interproximal areas are accessible for composite buildups.
• Caries risk under loose bands is eliminated.
• No band spaces are present to close at the end of treatment.
• Brackets may be recycled, further reducing the cost.
• Lingual brackets, invisible braces, can be used when patient rejects visible
orthodontic appliance.
8

9. Disadvantages
– Weaker attachment
– Better access for cleaning doesn’t guarantee better oral hygiene and improved
gingival condition
– Protection against interproximal caries of well contoured bands is absent
– Bonding generally not indicated on teeth where lingual auxiliaries are required
or where headgears are attached
– Rebonding requires more preparation
– Debonding is more time consuming.
9

10. • MATERIALS AND DEVICES USED IN ORTHODONTIC BONDING
10

11. Brackets
• The two most common types of orthodontic attachments are -
stainless steel and ceramic brackets
11

12. Ceramic Brackets
 Are machined from monocrystalline or
polycrystalline aluminum oxide.
 Combine the aesthetics of plastic and the
reliability of metal brackets.
 Ceramic brackets bond to enamel by :
(1) mechanical retention via indentations
and undercuts in the base
(2) chemical bonding by means of a
silanecoupling agent.
12

13. • With mechanical retention, the stress of debonding is
generally at the adhesive–bracket interface
• The chemical bonding may produce excessive bond
strengths, with the stress at debonding shifted toward the
enamel–adhesive interface
• Chemically cured and light-cured adhesives are useful for
ceramic brackets
13

14. Metal Brackets
• Mechanical retention , mesh structure - most common
• Bracket-based designs –
standard mesh base
supermesh base
integral base
microetched base
laser-structured base
14

15. • Mesh pad is the system most commonly used for retention.
• A new type of laser-structured base retention was found to
produce double the bond strength produced by foil mesh
without compromising debonding characteristics
15

16. 16

17. Base of the bracket
Bracket has to bond either chemically /mechanically
• Mechanical interlocking
• Base attachments – Mesh base designs
Non-mesh design
17

18. Base attachments
MESH TYPE BASES
- Foil mesh base
- Mini mesh base
- Micro mesh base
- Laminated mesh base
- Dyna bond base
- Ormesh wide central
- Supermesh MB base
18
NON-MESH TYPE BASES
-Micro-loc base
-Dyna lock integral base
- Micro etch base
-Peripheral perforated base
- Laser structured base

19. 19
MESH TYPE BASES
Foil mesh base
DYNA bond mesh BASE
Ormesh base
Super mesh base

20. 20
LASER STRUCTURED BASE
DYNA-LOCK INTEGRAL BASE
MICRO-LOC BASES MICRO ETCH BASE
Non Mesh type of bases

21. METHODS OF ATTACHING MESH TO
BRACKET
SPOT WELDING
Originally, the strands within the mesh backing were welded to each
other and to the back of the bracket
BRAZING
• Instead of welding the mesh strands, they are united by a special
process called brazing that does not flatten the wires
21

22. LASER STRUCTURED BASE
 David Hamula (1996) introduced titanium
brackets whose retentive base pads were
done by a computer-aided laser (CAL)
cutting process
 The smooth surface
of bracket base is treated by a sufficiently
powerful Nd: YAG laser, melting and
evaporating the metal and burning
hole-shaped retentions 22

23. Adhesives Composite Resins
• Originated in Bowen’s classic work on the development of
the monomer 2,2-bis-4(2-hydroxy-3
methacryloyloxypropoxy) phenylpropane.
• The essential chemistry of the synthesis of this substance is
the reaction of glycidyl methacrylate with bisphenol A to
create a molecule informally known as bisphenol A–
glycidyl methacrylate (bisGMA).
23

24. • BisGMA is the basis of most of the contemporary composite
resin systems clinically used today.
• Polymerization of composite resins can be initiated
chemically or by light exposure
24

25. Matrix type
Resin
matrix
Salt
matrix
Salt & resin
matrix
Polymerization Initiation
Mechanism
Chemical
cure
Light
cure
Dual
cure
Thermo-cured
Fluoride
Content
Filler
Content
Acrylic
resins
Diacrylate
resins
GIC Resin – ionomer
hybrids
Fluoride
releasing
Non-fluoride
releasing
unfilled filled
CLASSIFICATION OF BONDING MATERIALS
25

26. • Acrylic resins-
– Based on self curing acrylics
– Derivatives of ethylene and contain a vinyl group in
their structural formula. Those used in dentistry are
esters of
• Acrylic acid CH2+CHCOOH
• Methacrylic acid CH2=C(CH3)COOH
– Form linear polymers only

27. Composition
Supplied as powder and liquid
• Powder-
– Polymethylmethacrylate as beads or grindings
– Benzoyl peroxide- initiator ( 0.3- 3%)
– Colour pigments
• liquid-
– Methylmethacrylate monomer
– Ethylene dimethacrylate – crosslinking agent (5%)
– Hydroquinone (0.06%) inhibitor
– Tertiary amine- N-N dimethyl-p-toludine (2%) - activator

28. • Diacrylate resins
– based on acrylic modified epoxy resin, Bowen’s
resin or bisGMA
– Polymerized by cross linking into a three
dimensional network.
– The crosslinking contributes to greater strength,
lower water absorption, less polymerization
shrinkage.

29. COMPOSITE RESIN
Based on size of filler particles-
• Conventional 8-12 um
• Small particle 1-5 um
• Microfilled 0.04-0.4 um
• Hybrid 0.6-1.0 um
29

30. • Based on matrix composition
• Bis-GMA
• UDMA urethane dimethacrylate
• Bis-EMA ethoxylated bisphenol A glycol dimethacrylate
• TEGDMA triethylene glycol dimethacrylate
• Other resin
30

31. COMPOSITION
• RESIN MATRIX
• FILLER PARTICLES
• COUPLING AGENT
• THEY ALSO CONTAIN:
• Hydroquinone
• UV absorber
• Opacifier
• Colour pigment
31

32. Resin matrix
• BIS-GMA resin is the base for composite.
Diluents are added to increase flow and handling characteristics or
provide cross linking for improved strength.
• DILUENTS:- MMA methylmethacrylate BIS-DMA bisphenol dimethacrylate
UDMA urethane dimethacrylate
• CROSS LINK DILUENTS
TEGDMA triethylene glycol dimethacrylate
EGDMA ethylene glycol dimethacrylate
32

33. FILLERS
•Silica particles
•Quartz
•Glass ( Ba, Zr)
• If the composite is made up of the resin matrix AND fillers, it
is called Filled Resin
33

34. Coupling Agent
• Chemical bond
– filler particle - resin matrix
• transfers stresses
• Organosilane (bifunctional molecule)
– siloxane end bonds to hydroxyl groups on filler
– methacrylate end polymerizes with resin
34

35. Inhibitors
• Prevents spontaneous
polymer formation
– heat
– light
• Extends shelf life
• Butylated Hydroxytoluene
35

36. Pigments and UV Absorbers
• Pigments
– metal oxides
• provide shading and opacity
• titanium and aluminum oxides
• UV absorbers
– prevent discoloration
– acts like a “sunscreen”
• Benzophenone
36

37. Visible-Light Activation
• Camphorquinone – most common photoinitiator
• absorbs blue light – 400 - 500 nm range
• Initiator reacts with amine activator
• Forms free radicals
• Initiates addition polymerization
37

38. Polymerization
• Initiation
– production of reactive free radicals
- typically with light for restorative materials
• Propagation
– hundreds of monomer units
– polymer network
– 50 – 60% degree of conversion
• Termination
38

39. • ‘Degree of conversion' applied to resin composites, refers to
the conversion of monomeric carbon-carbon double bonds into polymeric
carbon-carbon single bonds.
• Increasing the conversion results in higher surface hardness, flexural
strength, flexural modulus, fracture toughness, and diametral tensile
strength
39

40. 40

41. • the higher the value of C-factor, the greater is the
polymerization shrinkage. Therefore, three-dimensional tooth
preparations (Class I) have the highest (most unfavorable)
41

42. Glass Ionomer Cements
• Introduced in 1972, primarily as luting agents and as a direct restorative material, with
unique properties for chemically bonding to enamel, dentin, and stainless steel and
being able to release fluoride ions for caries protection.
• Modified to produce dual-cure or hybrid cements
• Glass ionomer and light-cured glass ionomer cements are the material of choice for
cementing bands
• They are stronger than zinc phosphate and polycarboxylate cements, with improved
adhesion to enamel and metal and less demineralization at the end of treatment.
42

43. • Glass ionomer cement is a tooth coloured material, introduced
by Wilson & Kent in 1972.
• Material was based on reaction between silicate glass powder &
polyacrylic acid.
• They bond chemically to tooth structure & release fluoride for
relatively long period.
43

44. CLASSIFICATION
• Type I For luting For restoration
• Type II Restorative esthetic
• Type III liner & bases
• Type IV Pit and Fissure sealant
• Type V Luting for Orthodontic purpose
• Type VI For core build up
• Type VII High fluoride releasing command set
• Type VIII ART
• Type IX Pediatric purpose
44

45. COMPOSITION
• Powder
• Acid soluble calcium fluroalumino
silicate glass
• Silica – 41.9%
• Alumina – 28.6%
• Aluminum fluoride – 1.6%
• Calcium fluoride – 15.7%
• Sodium fluoride – 9.3%
• Aluminum phosphate – 3.8%
• Fluoride portion act as ceramic
flux.
• Strontium, Barium or zinc oxide
provide radio opacity
• Liquid
1.Polyacrylic acid in the form co-polymer
with itaconic acid & maliec acid
2.Tartaric acid: improves handling
characteristic & increase working
time.
3.Water : Medium of reaction & hydrates
the reaction products
45

46. SETTING REACTION
• When the powder & liquid are mixed, Surface of
glass particles are attacked by acid. Then Ca, Al,
sodium, & fluoride ions are leached into
aqueous medium.
• Calcium poly salts are formed first, then
followed by aluminum poly salts which cross link
with poly anion chain.
• Set cement consist of unreacted powder particle
surrounded by silica gel in amorphous matrix of
hydrated calcium & aluminum poly salts.
46

47. • Calcium poly salts are responsible for initial set.
• Aluminum poly salts form the dominant phase.
• Water plays an important role in structure of cement
47

48. Continuum of resin ionomer hybrids
Resin composites
Compomer Resin modified GIC
Conventional GIC
Matrix- resin
Setting mechanism:
Light cured
Chemical cured
Matrix- polysalts
Setting mechanism:
Acid- base reaction
VLC- GIC
Light Activated Water Based Cements
Resin ionomer hybrids

49. • Resin modified GIC ( RM-GIC)
– Setting occurs both by acid base reaction and
by free radical addition polymerization (light
and/or chemical activated).
• Powder:
– glass composition used for conventional GIC or
a Strontium Aluminoflurosilicate glass.
• Liquid:
– Replacement of water by a water – HEMA 2-
Hydroxylethyl methacrylate
– mixture along with photo initiators and
chemical initiators for free radical
polymerization.

50. • Advantages
– Release more fluoride than compomers and
GIC
– More esthetic than GIC
– Bond with tooth structure without use of bonding
agents
– Strength is double to that of GIC.

51. • Modified composites (Compomers or poly acid
modified composite resins)
– Single-component systems consisting of aluminosilicate
glass in the presence of carboxyl modified resin
monomers and light-activated conventional resin
monomers.
• Advantages
– Excellent esthetics
– Low solubility
– High bond strength
– High fracture toughness.
• Disadvantages
– Require bonding agent to bond with tooth structure
– Bonding surface must be dry
– Less fluoride release than GICs.

52. Chemically Activated orthodontic Adhesive systems
• Chemically activated orthodontic adhesives employ benzoyl peroxide
as an initiator, which is activated by a tertiary aromatic amine such as
dimethyl – p- toludine or dihydroxyethyl – p toludine.
• Initiation occurs from mixing of the paste and liquid components and
free radicals are formed by a multi step process.
TWO - PHASE ( TWO PASTE) Adhesive Systems
ONE - PHASE (NO - MIX) Adhesive systems
52

53. TWO - PHASE ( TWO PASTE) Adhesive Systems
• Were the first to be tried by orthodontist in the early days of bonding.
• Application involves mixing the paste and liquid components.
Disadvantages
• Time consuming
• Increased exposure to air induces oxygen inhibition.
• Mixing introduces defects in the form of air entrapment and formation
of voids.
• Concise (3M).
53

54. • Application of liquid component on enamel and bracket base.
• No mixing required.
• Here homogenous polymerization pattern occur due to sandwich
technique involved in diffusion of liquid component into paste during
application.
• Enamel and bracket sides of adhesive are more polymerized relative
to middle zone
ONE - PHASE (NO - MIX) Adhesive systems
54

55. • Efficient application, limited time requirements.
• Succeeded two – phase systems
• Not recommended in applications where the adhesive thickness is
increased, as in molar tubes.
• System 1(Ormco)
• Rely - a – Bond( reliance)
• Unite (3M)
55

56. Light cure adhesives
• Extent of
polymerization
depends on
– exposure time
– Photoinitiator
concentration
– Light intensity emitted
by the curing unit
– Filler volume.
Light cure sealant
Light cure paste

57. With light curing from the edges of the bracket, the directions
of the free radical gradient and polymerization shrinkage are modified
from those of chemical cure no mix material.
Also the rapid setting reaction greatly reduces the time
available for atmospheric oxygen to diffuse into the bulk resin and
deactivate the free radicals produced by the photoinitiator.
Therefore, superior mechanical properties and better
peripheral bracket sealing are obtained with light cure composites
compared to chemical cure.

58. Advantages
– Extended working time
– Desirable when long W.T is needed- difficult premolar bracket
positions need to be checked with a mouth mirror before bracket
placement is considered optimal
– Useful in situations where quick set is required- rebonding one
loose bracket or when placing an attachment on impacted canine
after surgical uncovering with the risk for bleeding.

59. Dual cure adhesives
• Polymerization initiation
– Initiation is achieved through exposure to light
– Reaction proceeds following a chemically cured pattern.
• Clinical handling
– Combines advantages of both light & chemical cure resins
– Prolonged clinical application process as both mixing and photocuring
are required
– Mixing may induce air incorporation leading to porosity in the set
material.
• Ideal candidates for bonding molar tubes.

60. Thermocure
• Polymerization initiation
– Through exposure to heat
• Used for indirect orthodontic bonding and restorations.
• Properties
– It is claimed that they present substantially increased polymerization rates
and so superior properties
– Use is limited as increased temperature is required to initiate
polymerization and the necessity for adapting an indirect bonding set up.

61. Adhesive precoated brackets
• Clinical handling
– Direct application of primer onto the adhesive
covered base and bonding
• Properties
– Bond strength comparable to conventional chemical
cured systems
• Efficient mode of bonding but further evidence is
required for its efficacy

62. • GENERATIONS OF BONDING AGENTS
62

63. • A typical bonding system consists of :
1. Etchant:
• It conditions or prepares the enamel for bonding.
2. Primers:
• Primers serve as wetting agents to improve the penetration of the monomers into the micro-porosities.
Penetration is aided by solvents.
• These are hydrophilic monomers (HEMA) carried in a solvent such as acetone, ethanol- water or water.
3. Bonding agent:
• An unfilled or lightly filled resin , similar in composition to the resin in composites except that
hydrophilic molecules have been added.
• The basic difference between these fluid bonding resins and the resin composites is the absence of
filler particles in the former.
63

64. FIRST GENERATION
• Used during late 1960’s.
• Did not recommend etching dentin
• N-phenyl-glycine-glycidyl methacrylate (NPG – GMA )
• Bonding occurred due to the interaction of this bi-functional resin with the
calcium ions of hydroxyapatite.
• Bond strength- 2 Mpa
• Example:
• Cervident(S S White burs,Lakewood)
64

65. SECOND GENERATION
• Late 1970’s.
• Halo-phosphoric esters of unfilled resin (Bis-GMA & HEMA hydroxy ethyl
methacrylate )
• Bonded to dentine through an ionic bond to calcium by chlorophosphate
groups.
• Weak bond strength, but significant improvement over first generation.
• Bond strength- 5 Mpa.
65

66. • EXAMPLES:
• Clearfil Bond System(Kuraray,Japan)
• Scotchbond(3M ESPE)
• Bondlite(Kerr Corporation.CA)
• Prisma Universal Bond(Dentsply)
66

67. THIRD GENERATION
• Introduced in late 1980’s.
• Introduced acid etching of dentin.
• Primer- 6% pentaphosphate, 30% HEMA, 64% Ethanol
• Unfilled resin adhesive
• The primer contains hydrophilic resin monomers which include hydroxyethyl trimellitate
anhydride, or 4–META, and biphenyl dimethacrylate or BPDM.
• The primers contain a hydrophilic group that infiltrates smear layer, modifying it and
promoting adhesion to dentin.
• Drawback – Bonding to smear layer - covered dentine was not very successful.
• Bond strength- 12- 15 Mpa 67

68. EXAMPLES:
• Clearfil New Bond(Kuraray)
• Scotchbond 2(3M ESPE)
68

69. FOURTH GENERATION
• Early 1990
• use of the total etch technique is one of the main characteristics of fourth
generation bonding system, here complete removal of the smear layer is
achieved.
• The Total etch technique permits the etching of enamel and dentine
simultaneously using 40% phosphoric acid for 15 to 20 seconds. The
surface must be left moist to avoid collagen collapse.
• Concept of Wet bonding
• Follows conventional etch-rinse-prime–bond approach
• “Multiple bottle bonding agents” 69

70. 70

71. BRAND NAMES-
• All Bond 2 & All Bond 3
• Optibond FL(Kerr Corporation)
• Adper Scotchbond Multi-purpose(3M ESPE)
71

72. FIFTH GENERATION
• Mid 1990’s
• Also known as “One bottle adhesives” or “Single bottle bonding
agents”
• ONE BOTTLE SYSTEMS combined the primer and adhesives into one
solution to be applied after etching.
• Total etching was done with 35 - 37% phosphoric acid for 15 to 20
secs.
• Bond strength – 25 Mpa 72

73. 73

74. • BRAND NAMES:
• Prime & Bond NT(Dentsply)
• Adper single bond2
• ExciTE(Ivoclar,Vivadent)
• One coat Bond
• XP Bond
74

75. SIXTH GENERATION
• Late 1990’s & early 2000’s
• Recently several bonding system were developed and these systems are
characterised by the possibility to achieve the proper bond to enamel and
dentine using only one solution. These should really be one - step
bonding.
• Self etching primers
• Two bottle 2 step system: Eg: clearfil SE bond, Optibond, Nano bond
• 2 bottle 1 step system: Eg: Xeno III, Tenure unibond
75

76. 76

77. • BRAND NAMES:
• Clearfil SE Bond(Kuraray,Japan)
• AdheSE(Ivoclar-Vivadent)
• Optibond Solo Plus Self-etch(Kerr Corp)
77

78. SEVENTH GENERATION
• All in one self etch.
• Self etching adhesives with no mixing
• One step self etch system
• The trend in the latest generation of dental bonding systems is to reduce the
number of components and clinical placement steps.
• The introduction of i Bond, a single – bottle adhesive system, is the latest to new
generation materials and combines etchant, adhesive and primer to one
component.
• Lowest initial and long term bond strength.
78

79. 79

80. Examples are:
• iBond(Heraeus kulzer)
• G bond(GC)
• XenoIV(Dentsply)
• Clearfil S3(Curare)
• XenoV+
80

81. EIGHTH GENERATION
• In 2010, voco America introduced voco futurabond DC as 8th
generation which contains nanosized fillers.
• The addition of nano fillers with an average particle size of
12nm increases the penetration of resin monomer and hybrid
layer thickness which in turn improves mechanical properties
of bonding system.
• Better bond strength, shelf life.
81

82. • voco futurabond DC
82

83. DECADE BONDING AGENT FEATURES
1960s
1970s
FIRST GENERATION
SECOND GENERATION
• DENTIN ETCHING WAS CONTRAINDICATED
• ADHESION WAS TO SMEAR LAYER
• WEAK BOND STRENGTH
1980s THIRD GENERATION • ETCHING ENAMEL & DENTIN
• PRIMING-A SECOND STEP WAS DONE
• BETTER BOND STRENGTH
EARLY
1990s
FOURTH GENERATION • TOTAL ETCH CONCEPT WAS INTRODUCED
• WET BONDING & HYBRID LAYER CONCEPTS INTRODUCED
• MULTIPLE TECHNIQUE SENSITIVE CLINICAL STEPS
MID
1990s
FIFTH GENERATION • PRIMER & ADHESIVE COMBINED IN ONE BOTTLE
• HIGHER BOND STRENGTHS
LATE
1990s
SIXTH GENERATION • INTRODUCTION OF SELF-ETCHING PRIMERS
• POST OPERATIVE SENSITIVITY WAS REDUCED
• LOWER BOND STRENGTHS
EARLY
2000s
SEVENTH GENERATION • ALL IN ONE/ONE STEP BOND CONCEPT INTRODUCED
• BOND STRENGTH LOWER THAN 4TH & 5TH GENERATIONS
83

84. No-mix adhesives
Set when one paste under light pressure is brought together with
a primer fluid on the etched enamel and bracket backing or when
another paste on the tooth is to be bonded.
84

85. Light-polymerized adhesives
 freedom to choose when to initiate the adhesive curing cycle after bracket
placement.
 Light-curing resin composites - introduced 1970s.
 In light-cure adhesives, the curing process begins when a photoinitiator is
activated.
 Most dental photoinitiator systems use camphoroquinone as the diketone
absorber, with the absorption maximum in the blue region of the visible light
spectrum at a wavelength of 470 nanometers (nm) 85

86. Primers
• Much confusion and uncertainty surround the use of sealants and
primers in orthodontic bonding.
• Recent findings demonstrate that bonding with or without a primer
(unfilled resin) before bracket placement is equally clinically successful as
far as bracket failure rate is concerned.
86

87. Why, then, should a sealant be of any value in bracket bonding?
 If nothing else, a sealant permits a relaxation of moisture control
because controlling moisture is no longer critical after resin coating.
 Sealants also provide cover for enamel in areas of adhesive voids,
which is probably especially valuable with indirect bonding.
 The caries protection of sealant around the bracket base is more
uncertain, and further studies are needed on the clinical merits of fluoride-
containing sealants.
87

88. Moisture-Insensitive Primers ( MIP)
 To reduce the bond failure rates under moisture
contamination, hydrophilic primers that can bond in wet
fields have been introduced as a potential solution.
 For optimal results, the moisture-insensitive
primers should be used with their respective adhesive
resins.
88

89.  The hydrophilic resin sealants or primers polymerize in the
presence of a slight amount of water, but they will not overcome
routine saliva contamination.
 When bonding to enamel, the resin sealant or resin primer
must be placed onto the prepared enamel before the pellicle (biofilm)
formation from the saliva, which is not particularly difficult but is
crucial to a successful enamel bond.
89

90. MIP EXAMPLE
• Transbond MIP, 3M Unitek,Monrovia, CA; Assure or Assure
Plus, Reliance Orthodontic Products, Itasca, IL)
90

91. Self-Etching Primers
The unique characteristic of these bonding systems is
that they combine the conditioning and priming agents into a
single acidic primer solution for simultaneous use on both enamel
and dentin; therefore separate acid etching of the enamel and
subsequent rinsing with water and air spray is not required .
91

92. The active ingredient of the SEPs is a methacrylate phosphoric acid ester that
dissolves calcium from hydroxyapatite.
Mechanism:
• The phosphate group of methacrylated phosphoric acid ester dissolves calcium
and removes from hydroxyapatite.
• The released calcium then forms a complex and is incorporated into network when
the primer polymerizes.
• Etching and monomer penetration to exposed enamel rods are simultaneous and
depth of etch and primer penetration are identical.
92

93. Three mechanisms act to stop the etching process
 First, the acid groups attached to the monomer are neutralized by
forming a complex with calcium from hydroxyapatite.
 Second, as the solvent is driven from the primer during the
airburst step, the viscosity rises, slowing the transport of acid groups to the enamel
interface.
 Finally, as the primer is light cured and the primer monomers are
polymerized, transport of the acid groups to the interface is stopped.
93

94. • The minimal etch obtained with SEPs indicate that majority of the bond may
be more of a chemical bond with the calcium in the enamel than the
mechanical bond achieved with a conventional phosphoric acid etch.

95. • Instead of well known honey comb structure with microtag and
macrotag formation one finds an irregular but smooth hybrid layer,
3 to 4 microns thick and irregular tag formation with no apparent
indentations of enamel prisms or core material.

96. Clinical use of Self etching Primers:
1.Dry the tooth surface.
2. Apply Self etching primer.
It consists of three compartments.
a) contains methacrylated phosphoric acid
esters, photosensitizers, and stabilizers.
b) water and soluble fluoride.
c) Applicator microbrush

97. Squeezing and folding the first
compartment over to the second
activates the system.
The mixed component then is ejected
to the third to wet the applicator
tip.
3) Bond the bracket with composite
and cure with light.

100. 100

101. Light Sources
101

102. Halogen lights-
Conventional
• Most common source of blue light since 1970’s has been quartz tungsten halogen
(QTH).
• halogen bulbs produce light when electric energy heats a small tungsten filament to
high temperatures.
• Can cure orthodontic composite resin- 20 sec
• Light cured resin modified GI – 40 sec

103. • Use camphorquinone as absorber with absorption maximum in the
blue region of the visible light spectrum at a wavelength of 470 nm.
• Disadvantages
– Light power output is less than 1% of the consumed electric power
– limited life time of 100 hrs because of degradation of components of
the bulb by the high heat generated
– Prolonged curing time inconvenient for clinician and patient.

104. • Polymerization is initiated when a critical
concentration of free radicals is formed. This
requires particular no. of photons to be absorbed
by the initiatior system.
• Fast halogens- higher intensity output
accomplished by higher output lamps or using
turbo tips that focus light and concentrate it into
a smaller area.

105. • Never turn off a halogen unit if the fan is still running. This
will help to extend the life of the unit.
• The light guide must also be kept free of resin build up on
the end. Either use a sleeve cover to protect the light guide
or use some acetone to remove any residue that has
formed.
105

106. Argon lasers
• Late 1980’s argon lasers promised to reduce curing time
dramatically. Excited ions in an argon filled chamber
produce a light that is focused and passed through the
hand piece.
• They produce a highly concentrated beam of light
centered around the 480nm wavelength.
• Light is collimated which results in more consistent
power density over distance.

107. • Advantages
– Protects enamel surface against decalcification
– reduces enamel demineralization around orthodontic brackets
– Curing time - 5 sec for unfilled resins
- 10 sec for filled.
• Disadvantages
– High cost
– Poor portability
– Narrow output which sometimes did not cure all the resins.

108. Plasma arc lights
• Mid 1990’s the xenon plasma arc lamp was introduced for high intensity
curing of composite resins in restorative dentistry.
• Plasma arc curing was introduced with a 3 second cure
• Lamp has tungsten anode and cathode in a quartz tube filled with xenon gas.

109. • White light is filtered to blue wavelengths with a narrow spectrum
between 430 and 490 nm.
• The plasma arc lights are contained in base units rather than in guns
because of high voltage and heat generated.
• Whereas conventional halogen bulbs emit light with energy level of 300
mW, plasma arc lamp has a much higher peak energy level of 900mW.

110. • Advantages
– polymerization can be done in shorter time
– Use for 5- 10 sec is safe regarding pulp temperature.
• Disadvantages
– They require filters
– Generate heat
– Expensive.
• It is suggested that two 3 sec cycles of curing is more beneficial than 1 cycle of 6 sec; moving
the light after 3 sec of exposure not only minimizes any pulpal temperature effects , but it
also provides a better distribution of light energy under bracket base.

111. • 1995 Mills et al proposed solid state LEDs for polymerization.
• Use junctions of doped semiconductors to generate light.
• They directly emit light in the blue region.
Light emitting diodes

112. Advantages
– Have small size, are cordless
– quiet
– generate minimal heat
– Life time of > 10000 hrs
– Undergo little degradation of output over this time
– Require no filters to produce blue light
– Resist shock and vibration
– Take little power to operate.

113. • For success in bonding with light activated resins,
bracket should be exposed to the curing light
immediately after placement.
• Keep the time interval between placement and curing
to a minimum.
113

114. 114

115. CURING
• Polymerization contraction - irrelevant to the orthodontic setting
where the bracket or the orthodontic attachment is actually free
floating.
• Therefore preseting the light-curing unit to the maximum available
setting or to the boost mode is advisable.
115

116. • Recent studies demonstrate no significant differences between the
Shear Bond Strength values of brackets with curing distances of 0 to 4
mm.
• The light is best initiated after being placed at the correct position and
angulation as close to the bracket base as possible .
116

117. • Divergent photon release will be avoided and curing efficiency
increased if the light guide is brought into contact with the bracket
after an initial cure of 1 to 2 seconds.
• Locating the guide tip before starting the light gun is crucial; with
recent light sources, as little as even 2 or 3 seconds spent to position
the guide tip correctly after shooting may well correspond to almost
40% of the total suggested curing time.
117

118. • Many manufacturers advise curing metal brackets from mesial and distal,
direct bond molar tubes from mesial and distal or occlusal, and ceramic
brackets through the bracket.
• Most current light sources can cure adhesives in approximately 10 or 5
seconds per metallic and ceramic brackets, respectively.
• A new plasma-emulating LED (VALO Ortho, Ultradent Products, Inc.,
South Jordon, UT) was demonstrated to cure resin under brackets in as
few as 3 seconds
118

119. • One clinical concern with this light source is the high heat reported by
the patients at the gingiva, which is well tolerated when the patients are
informed in advance.
• laboratory studies, under simulated blood circulation, the temperature
increase in the pulp chamber was 1.74° C, which is significantly lower
than those resulting from longer exposures at lower power settings.
• However, not every resin is compatible with every light source, and each
combination should be individually assessed to achieve optimal results.
119

120. BONDING
120

121. Bonding to Enamel
121

122. • The steps of direct or indirect bracket bonding on facial or
lingual surfaces of teeth are as follows:
• CLEANING
• ENAMEL CONDITIONING
• SEALING
• BONDING
122

123. 1. CLEANING
• Cleaning of the teeth with pumice removes plaque and the organic
pellicle that normally covers all teeth. One must exercise care to avoid
traumatizing the gingival margin and initiating bleeding on teeth that are
not fully erupted.
• Improves the effectiveness of etching
• Bond strength appears to be unaffected if pumice used or not.
• Creation of surface irregularities microporosities and increasing the
surface area. 123

125. 125

126. 126

127. 2. ENAMEL CONDITIONING

128. MOISTURE CONTROL
• After the rinse, salivary control and maintenance of a completely dry
working field is absolutely essential.
• Lip expanders and / or cheek retractors
• Saliva ejectors
• Tongue guard with bite blocks
• Salivary duct obstructors
• Gadgets that combine several of these (saliva ejector, tongue holder,
and bite block).
• Cotton or guaze rolls
• Antisialagogues. 128

129. DRI ANGLES
• A unique replacement and a decided improvement on the cotton roll in the parotid area, designed by
John W Owen.
• The Dri-Angle covers the parotid or Stensen's duct and effectively restricts the flow of saliva.
• The Dri-Angle provides the required Dri-Field for: Composites, Bonding, Cementing.
• A thin, absorbent, cellulose triangle
• The Dri-Angle comes in two types: plain and silver coated.
• Use the silver coated Dri-Angle for superior saliva control. Silver coating on one side acts as a
complete moisture barrier for heavy salivators.

131. PLACEMENT
• The Dri-Angle has been contoured to fit the inside of the cheek.
• Choose the small or large size for the particular patient.
• Place the convex side against the cheek with the apex of the Dri-Angle as far back as possible.
• The apex should almost touch the retro-molar pad area.

132. LIP EXPANDERS AND CHEEK RETRACTORS

133. Tongue guards with bite blocks Saliva ejectors

134. Enamel pretreatment
Conventional Acid Etching.
134

135. TYPES OF ETCHANTS
Strong acids
• 37% phosphoric acid for 15 seconds
Provides a strong bond
Weak acids
• 2.5% nitric acid
• 17% maleic acid for 30-60 seconds
135

136. Organic acid
Maleic acid ,EDTA ,citric acid, tartaric acid.
Inorganic acid
phosphoric acid, nitric acid.
Polymeric acid
poly acrylic acid
136

137. ENAMEL PRETREATMENT
CONVENTIONAL ACID ETCHING
• After the operative field has been isolated, the teeth to be bonded are dried.
• The conditioning solution or gel (usually 37% phosphoric acid ) is then lightly
applied over the enamel surface with a foam pellet or brush for 15 to 60 sec.
• If tooth is etched for more than 90 sec – an insoluble calcium phosphate salt
crystals forms on the enamel that is impervious to rinsing, resulting in reduced
bond strength.
137

138. • To avoid damaging delicate enamel rods, care must be taken not to rub the liquid
onto the teeth.
• At the end of the etching period the etchant is rinsed off the teeth with abundant
water spray.
• Salivary contamination of the etched surface must not be allowed. ( If it occurs
rinse with water spray or re - etch for a few seconds; the patient must not rinse.)
138

139. • Next, teeth are thoroughly dried with moisture and oil- free air
source to obtain the dull frosty appearance.
• Teeth that do not appear dull and frosty white should be re- etched.
• The effect of acid etching is to remove a small amount of the softer
interprismatic enamel and open up pores between the enamel
prisms, so the adhesive can penetrate into enamel surface.
139

140. • <27% - Calcium salts are less dissolved - ETCH pattern with poorer
definition.
• >40% - Formation of dicalcium phosphate dihydrate - cannot be easily
removed by rinsing
140

141. Iatrogenic effects of etching
• Fracture and cracking of enamel upon
debonding
• Increased surface porosity - possible staining
• Loss of acquired fluoride in outer 10m of
enamel surface
• Loss of enamel during etching
• Resin tags retained in enamel - causing
discoloration of resin.
141

142. • Rougher surface if over - etched
• A rougher surface with enamel cracks if
debonding is carried out improperly, resulting in
increased plaque retention
• Leakage at the bracket interface leading to
bracket corrosion and staining
• Softer enamel surface with lower fluoride
content, more predisposed to decalcification.
142

143. Morphology
• The circular or hexagonal features on the
surface of enamel shown here represent the
ends of these hydroxyapatite crystals.
('keyhole' or 'fishscale' appearance ).
• Enamel prisms extend from DEJ to outer
surface at varying angles
• Enamel prisms (rods) – 5-12 million
• Diameter:4-5 μm
• Thickness : 1000 to 2000 μm (except as it
tapers toward the cervical margin)
143

144. Longitudinal section
• 2 types of bands
• Wider prisms
• Narrower Interprismatic
substance
144

145. • Key hole pattern
• Head – incisal region
• Tail – cervical region
145

146. 146
Prisms contain
hydroxyapatite crystals
Run parallel to long axis
of prism and become
perpendicular as they
approach tail

147. ETCHING PATTERNS
• According to Silverstone et al there are
5 types of etching patterns:
TYPE 1: central etch type.
• Here the prism centers have been
removed preferentially.
147

148. TYPE 2 : Cobble stone appearance
• the loss of prism peripheries demonstrates the head and
tail arrangement of the prisms
148

149. TYPE 3 : Less structured etch type
• which is a mixture of Type 1 and Type 2 configurations.
149

150. • TYPE 4 : pitted enamel surfaces as well as structures that look
like unfinished puzzles, maps, or networks.
150

151. TYPE 5 : flat smooth surface
• they lack micro-irregularities for penetration and retention of
resins.
151

152. • Should the etch cover the entire facial enamel or only a small portion
outside the bracket pad?
Clinical experience indicates that etching the entire facial enamel with
solution is harmless at least when a fluoride mouth rinse is used regularly.
• Are gels preferable to solution ?
Brannstrom et al (1982) They found one minute etching with an acid
gel had the same effect as etching with an acid liquid for the same time.
Gels provide better control for restricting the etched area but may require
more thorough rinsing afterward.
152

153. • What is the optimal etching time?
• No differences in bond strength are detected between 15 second
and 60 second etching with 37% phosphoric acid; however, shorter
etching times cause less enamel damage on debonding.
• Applied with a foam pellet, brush etc. for approximately 15 -30 s
• etching period for permanent teeth is 30s and deciduous teeth is 60-
90s
153

154. WHY 37% PHOSPHORIC ACID?
• Etching with 37% phosphoric acid produces the highest bond
strength ( 28Mpa) to enamel.
• The use of 10% maleic acid results in a lower bond strength (18
Mpa )
• Concentration greater than 50% results in formation of mono-
calcium phosphate monohydrate on etched surface that inhibits
further dissolution.
154

155. DO WE HAVE TO ETCH FLUORIDATED ENAMEL MORE THAN THE
NORMAL ENAMEL ?
• Highly fluoridated or fluorotic enamel does not require more
concentrated acid solutions or longer etching times.
155

156. • Is etching permissible on teeth with internal white spots?
• Caution should be exercised when etching over acquired and
developmental demineralizations. It is best to avoid it. If this is
impossible, a short etching time, the application of sealant, and the
use of direct bonding with extra attention to not having areas of
adhesive deficiency are important.
• The presence of voids, together with poor hygiene, can lead to metal
corrosion and staining of underlying developmental white spots.
156

157. How much enamel is removed by etching and how deep are the histological
alterations? Are they reversible? Is etching is harmful?
• A routine etching removes from 3 to 10 microns of surface enamel.
• Another 25 microns reveal subtle histologic alterations, creating the necessary
mechanical interlocks .
• Deeper localized dissolutions generally cause penetration to a depth of approximately
100 microns or more.
• Although laboratory studies indicate that the enamel alterations are largely (although
not completely) reversible,the overall effect of applying an etchant to healthy enamel is
not detrimental.
• This point is augmented by the fact that normal enamel is from 1000 to 2000 microns
thick,except where it tapers toward the cervical margin.
• Abrasive wear of facial enamel is normal and proceeds at a rate of up to 2 microns per
year, and facial surfaces are self-cleaning and not prone to caries. 157

158. • Can recently bleached teeth be safely bonded?
• Bleaching with 35% hydrogen peroxide significantly reduces bracket
adhesion when bonded 24 hours after bleaching.
• However, no significant adverse effect of bleaching seems to occur after 7
days.
• Therefore postponing the bonding procedure approximately 1 to 4 weeks
for recently bleached teeth may be a good practice.
158

159. WHY IS RINSING AND DRYING DONE AFTER ETCHING ENAMEL?
• It’s a misconception that rinsing is performed to remove acid from teeth.
• Acid removal is secondary for rinsing.
• Primary reason is to remove calcium monophosphate, calcium sulphate
byproducts , and phosphoric acid byproducts.
• Never take a wet cotton roll and attempt to wipe the acid off the tooth. This will
fracture enamel rods and will weaken bond strength.
• 10- 15 s per tooth – liquid etch
• 20s per tooth – gel etch.
159

160. What are other alternatives to etching with phosphoric
acid (e.g., polyacrylic acid, maleic acid, SEPs)?
• The use of polyacrylic acid with residual sulfate is reported to provide
retention areas in enamel similar to those after phosphoric acid
etching with less risk of enamel damage at debonding.
• However, other researchers have found much weaker bonds.
• Research shows that 10% maleic acid, which is believed to decrease
mineral loss alone, may produce similar bond strengths to 37%
phosphoric acid.
• However, the use of these milder acids has never been popularized.
160

161. WHAT ARE THE DIFFERENT WAYS TO PREPARE THE ENAMEL ?
• ACID ETCHING.
• CRYSTAL GROWTH.
• AIR ABRASION/ SAND BLASTING / MICRO ETCHING.
• LASER ETCHING.
161

162. CRYSTAL GROWTH
• Alternate to acid etching.
• Retention by growth of crystals on enamel surface
• This system consists of a polyacrylic acid
treatment liquid containing a sulfate component
that reacts with the calcium in the enamel surface
to form a dense growth of small, needle-shaped
crystals. These crystals grow in so-called
spherulitic habit .
• The crystal build up on the enamel serves as an
additional retentive mechanism for the resin that
bonds the orthodontic attachment to the teeth.
162

163. • In this procedure the bond does not rely on extensive
penetration into the enamel. Micromechanical interlocking is
created at the enamel surface.
• These crystals in turn retain the adhesive.
• Bond strength obtained is 60-80% of that obtained from acid
etching.
Advantages-
• easier debonding
• less residual adhesive left on tooth
• less damage to enamel
163

164. • No resin tags left behind in the enamel surface
• Possibility in the future of incorporating fluoride in the crystal
interface to provide an anticariogenic action.
164

165. 165
Phosphoric acid etched
enamel surface
Crystal growth on
enamel surface

166. MICRO ETCHING /AIR ABRASION/ SAND BLASTING
• 1940, by Robert Black
• 50 µ or 90 µ Aluminium oxide particles are propelled against
surface to be prepared at a pressure of about 7kgs/cm2 for 3 sec
at 10 mm distance.
• Sandblasting without acid etching produces lower bond strengths
than acid etching and consistently results in bond failures at the
enamel–adhesive interface.
166

167. 167

168. • Sandblasting enamel does not appear to damage the surface. However,
more in vivo tests are needed.
• The greatest debonding force was achieved by sandblasting before acid
etching.
• Sandblasting before etching can be a substitute for polishing with pumice.
168

169. Uses
• Removing old composite resin and improving retentive surface of loose brackets
before rebonding
• Along with acid etching in situation of rebonding brackets
• To increase retentive area inside molar bands
• Creating micro-mechanical retention for bonded retainers
• Bonding deciduous teeth.
169

170. LASER ETCHING
• Localized ablation of enamel by micro
explosion of trapped water inside enamel.
• Some melting of the hydroxyapatite crystals.
• Neodymium- yttrium- aluminium garnet
( Nd: YAG) laser.
• Increase of pulplal temperature.
• Produces lower bond strengths than acid
etching. 170

171. SEALING
• After the teeth are completely dry and frosty white, a thin
layer of bonding agent (sealant, primer) may be painted over
the etched enamel surface.
• The coating may be thinned by a gentle air burst for 1 to 2
seconds
• Bracket placement should be immediately started after all of
the etched surfaces are coated.
• Separate curing of the bonding agent is not necessary when
light cured products are used.
• Reapplication of the sealed layer is not required when saliva
contamination occurs, but the area should be air dried before
bracket placement.
171

172. • Importance
– A sealant basically permits relaxation of moisture
control because this is no longer critical after resin
coating
– Also provide enamel cover in areas of adhesive
voids, which is especially valuable with indirect
bonding
– Light polymerized sealants protect enamel
adjacent to brackets from dissolution and
subsurface lesions.

173. • Shorten the exposure time to air prior to complete
curing
• Brushes with long and thick bristles may result in
• Increased amount of material being placed on enamel
surface
• Increased inclusion of air
• The coating should be thin as excess sealant may
induce
• Bracket drift
• Unnatural enamel topography when polymerized.
173

174. BONDING
• Immediately after all teeth to be bonded have been painted
with sealant, the operator should proceed with the actual
bonding of the attachments.
• The recommended bracket bonding procedure consist of
the following steps
• 1.TRANSFER
• 2.POSITIONING
• 3.FITTING
• 4.REMOVAL OF EXCESS
174

175. TRANSFER
• The bracket is gripped with reverse action tweezer (bracket
holding forceps) and the mixed adhesive is applied to the
back of the bonding base.
• The bracket is immediately placed on the tooth close to its
correct position.
175

176. BONDING
• Transfer

177. POSITIONING
• The mandibular molar and premolar bracket wings must be kept out of occlusion, or
the brackets may easily come loose.
• Therefore before positioning the brackets, the operator should do the following:
1. The patient is asked to bite with his or her teeth together; the operator should then
evaluate the tooth area available for bonding.
2. The mandibular posterior brackets are bonded out-of-occlusion, which may necessitate
adjusting bends in the archwires.
• Later, the clinician uses a placement scaler to position the brackets mesiodistally and
incisogingivally and to angulate them accurately, relative to the long axis of the teeth.
• Proper vertical positioning may be enhanced by different measuring devices or height
guides.
177

178. • A mouth mirror will aid in horizontal positioning,
particularly on rotated premolars.
• Because of human limitations in the direct placement of
brackets on both anterior and posterior teeth, using
archwire bends or bracket repositioning to compensate for
the inherent inaccuracies in bracket positions is still
necessary.
178

179. • Positioning

180. BONDING TO PREMOLARS.
• The most difficult technical problem for bonding to maxillary first and
second premolars is to obtain accurate bracket placement.
• The visibility for direct bonding is facilitated if these teeth are bonded
without a lip expander, one side at a time.
• For newly erupted mandibular premolars, gingivally offset brackets are
recommended.
• The gingival third of these teeth may have a high incidence of aprismatic
enamel and an enamel rod direction that is less retentive.
180

181. 181

182. BONDING TO MOLARS.
• With the difficulty of banding in young patients, particularly second
molars, bonding these and other molars is advantageous.
• With special technique and care, the routine bonding of first, second,
and third molars can be accomplished with high success rates.
• For optimal bond strength, it appears preferable to establish
adequate moisture control and bond molar attachments with
conventional bisphenol A diglycidyl dimethacrylate (bis-GMA)
composite resins.
182

183. 3. FITTING
• Next, the clinician turns the scaler and with one-point contact with
the bracket, pushes firmly toward the tooth surface.
• Totally undisturbed setting is essential for achieving adequate bond
strength.
183

184. • Fitting
Tight fit will result in
– Good bond strength
– Little material to remove on
debonding
– Optimal adhesive penetration
into bracket backing
– Reduced slide when excess
material extrudes peripherally.

185. 4. REMOVAL OF EXCESS
• A slight bit of excess adhesive is essential to
minimize the possibility of voids and to be
certain that the adhesive will be buttered
into the bracket backing when the bracket is
being fitted.
• The excess is particularly helpful on teeth
with abnormal morphology.
• Excess adhesive will not be worn away by
toothbrushing and other mechanical forces; it
must be removed (especially along the
gingival margin) with the scaler before the
adhesive has set or with burs after setting.
185

186. – Prevents or minimizes gingival irritation, plaque build up
around the periphery of bonding base
– It also reduces periodontal damage and possibility of
decalcification
– Improves esthetics not only by providing a neater and
cleaner appearance but also by eliminating exposed
adhesive that might become discolored in the oral
environment.
186

187. • Always add slight excess of adhesive to the backing of attachment and then position
it on the tooth surface.
• Remove the scaler after bracket is in correct position.
• Totally undisturbed setting is essential for achieving adequate bond strength
• When placing brackets always match bracket height with opposite side.
• Mandibular arch is always at greater risk of moisture contamination and should be
bonded prior to maxillary arch.
187

188. Bracket placement in MBT technique
• Horizontal accuracy

189. • Axial accuracy

190. • Vertical accuracy

191. BONDING IN WET FIELD
• Despite moisture control steps and measures available, orthodontist often faces
problem of bonding in an environment with increased risk of contamination.
• This happens during bonding of partially erupted premolars because of
proximity of adhesive to cervical portion of crown and presence of crevicular
fluid.
• 2nd molar bonding
• Situation of blood contamination as in impacted canines.
• To over come this 2 formulations were developed;
-Moisture Resistant Adhesive,
-Moisture Active Adhesive.
191

192. MOISTURE RESISTANT ADHESIVES
• They are available in a primer formulation and are based on hydrophilic
attraction of its constituents.
• The main reactive component is : Meth-acrylate poly alkanoic acid copolymer
originally used in dentin bonding system.
• Mechanism:
- Excess inter-facial water ionises carboxylic groups forming hydrogen bonded
dimers.
- With this a dynamic equilibrium occurs at the interface, incorporating water in
the bonding mechanism that minimizes detrimental plasticity effect of water that
occurs with moisture contamination of conventional bonding agent.
192

193. • The sealant is applied, after 10 sec it should be lightly dried
with air for 5 sec, then light cured for 10 sec.
• For best results these primers should be used with their
respective adhesive resins.
193

194. MOISTURE ACTIVE ADHESIVES
• It requires moisture rather than tolerate the presence of moisture
for proper polymerization.
• Available as pastes, require no bonding agents.
• Contains cyano-acrylate.
• Setting reaction involves 2 steps-
- Iso-cyanate groups reacts with water, forming unstable carbamic
acid component, which rapidly decomposes to CO2 and
corresponding amine.
- The amine reacts with residual iso-cyanate groups, cross-linking
the adhesive through substituted urea groups.
194

195. ADVANTAGES
• Biocompatible,
• Allergy-tested,
• Moisture activated,
• No bad taste or smell for the patient,
• No discoloration throughout treatment,
• Bonds on plastic, metal and ceramic attachments.
195

196. DISADVANTAGES
• First step occurs only in presence of excess water.
• CO2 release during prolonged setting reaction, may become entrapped,
forming gaps or voids with detrimental effects on interfacial strength.
• The wet environment in oral cavity is mostly due to salivary flow rather than
the presence of water. Contamination with saliva adversely affects the
setting reaction and can affect the structure and performance of material.
• Surfaces to be bonded should be as close together as possible. It can’t fill
spaces or gaps, so bracket base with deep mesh or undercuts will have lower
bond strength
196

197. INDIRECT BONDING
197

198. • In Indirect bonding, brackets are attached to the teeth on the patients models,
transferred to the mouth with some sort of tray on to which the brackets become
incorporated, and then bonded simultaneously with a bisGMA resin.
• Most current indirect bonding techniques are based on a modification introduced by
Thomas, which attaches the brackets with composite resin to form a custom base.
• A transfer tray of silicone putty or thermoplastic material is used, and the custom
bracket bases are then bonded to the teeth with a chemically cured sealant.
198

199. Indirect Bonding with Composite Custom Bracket Base
The following procedure may be useful :
1. Take an impression, and pour a stone (not plaster) model.
2. Select brackets for each tooth.
3. Isolate the stone model with a separating medium.
4. Attach the brackets to the teeth on the model with lightcured or thermally
cured composite resin, or use adhesive precoated brackets.
5. Check all measurements and alignments. Reposition if needed.
6. Make a transfer tray for the brackets. The material can be putty silicone,
thermoplastics, or similar.
199

200. 7. After removing the transfer trays, gently sandblast the
adhesive bases with a microetching unit, taking care
not to abrade the resin base.
8. Apply acetone to the bases to dissolve the remaining
separating medium.
9. Prepare the patient’s teeth for a direct application.
10. Apply Sondhi Rapid-Set (3M Unitek, Monrovia, CA)
resin A to the tooth surfaces and resin B to the
bracket bases.
200

201. 11. Seat the tray on the prepared arch,
and apply equal pressure to the
occlusal, labial, and buccal surfaces
with the fingers. Hold for a minimum
of 30 seconds, and allow for 2
minutes or more of curing time
before removing the tray.
12. Remove excess flash of resin from
the gingival and contact areas of the
teeth with a scaler or contra-angle
handpiece and tungsten carbide bur. 201

202. An indirect bonding system must satisfy the following criteria to be
successful
• Positions brackets accurately on all teeth.
• Ensures adequate bracket adherence by avoiding moisture
contamination
• Reduces patient discomfort and duration of the bonding procedure.
• Reduces laboratory expense and doctor chair time.
• Ensures sufficient integrity of transfer trays to hold brackets securely
in place while the adhesive polymerizes.
• Reduces stress for the clinical staff.
202

203. DISADVANTAGES
• Technique sensitive
• Chairside procedure is more crucial, at least for inexperienced clinicians
• Removal of excess adhesive can be more difficult and more time consuming with some
techniques
• The risk for adhesive deficiencies under the brackets is greater
• The risk for adhesive leakage to interproximal gingival areas can disturb oral hygiene
procedures; and the failure rates with some methods seem to be slightly higher.
203

204. Bonding to Artificial Tooth Surfaces
204

205. 1. BONDING TO PORCELAIN.
Bonding to feldspar porcelain: (10%- 20% aliuminium oxide)
• 2 different techniques:
- Hydrofluoric acid (9.6% for 2 mins) gel treatment,
- Sand blasting and silane
(Eg: Scotch prime)
205

206. • The ideal bond should be sufficiently strong enough to endure a
course of orthodontic treatment, yet be sufficiently weak to
permit restoration of the porcelain surfaces following bracket
removal.
• HF acid creates a series of surface pits by preferential dissolution
of the glass phase from ceramic matrix
• Silane bonding acts as a chemical link between the inorganic
ceramic surface and organic resin adhesive agent.
206

207. SILANATION
• Provides ultra-fine mechanical retention by sandblasting, as well as a
chemico-physical bonding between the composite resin and the
ceramic or metal alloy by using a silane coupling agent. ( γ-meth-
acryloxy-propyl-trimethoxy-silane )
• The silica of the dental ceramic is chemically united with the acrylic
group of the composite resin through silanation.
• The highest bond strength values were obtained with sandblasting
and silicatization with silane or hydrofluoric acid without silane.
207

208. • This silane contains silanol groups that can bond with silanols
on the ceramic surface, forming a siloxane (Si-O-Si) bond.
• Additionally, this silane contains methacrylate groups that can
form covalent bonds with the polymer matrix of the resin
composite.
208

209. 209

210. When hydrofluoric acid gel is used close to the gingival margin, particularly in the mandible, one must use a
light-cured block out resin such as Kool-Dam to protect the soft tissues from the acid.
210

211. 2. BONDING TO AMALGAM.
Improved techniques for bonding to amalgam restorations may involve
(1) modification of the metal surface (sandblasting, diamond bur
roughening)
(2) the use of intermediate resins that improve bond strengths (e.g., All-
Bond 2 [Bisco, Schaumburg, IL], Enhance, and Metal Primer [Reliance
Orthodontics]), and
(3) new adhesive resins that bond chemically to nonprecious and precious
metals (e.g., 4-methacryloxyethyl trimellitate anhydrid [4-META] resins
and 10-MDP bis-GMA resins).
211

212. Small Amalgam Filling with
Surrounding Sound Enamel
1. Sandblast the amalgam alloy
with 50 microns of aluminum
oxide for 3 seconds
2. Condition surrounding enamel
with 37% phosphoric acid for
15 seconds.
3. Apply sealant and bond with
composite resin.
212

213. Large Amalgam Restoration or
Amalgam Only
1. Sandblast the amalgam filling
with 50 microns of aluminum
oxide for 3 seconds.
2. Apply a uniform coat of
Reliance Metal Primer and wait
for 30 seconds (or use another
comparable primer according to
manufacturer’s instruction).
3. Apply sealant and bond with
composite resin. 213

214. 3. GOLD SURFACE
• Intraoral Sandblasting
• Electrolytic tin plating
• Plating with gallium-tin solution
• Use of different intermediate
primers and adhesives that bond
chemically to precious metals
(Panavia).
214

215. 4.BONDING TO COMPOSITE RESTORATIVES
• The bond strength obtained with the addition of new
composite to mature composite is substantially less than
the cohesive strength of the material.
• However, brackets bonded to a fresh, roughened surface of
old composite restorations appear to be clinically successful
in most instances.
• Use of an intermediate primer is probably advantageous
as well.
215

216. BOND FAILURES
216

217. • Divided into two categories depending upon site of failures
• 1. Adhesive – enamel bond failures
• 2. Adhesive – bracket bond failures
Possible causes of Adhesive – enamel Bond failures
1. Contamination of etched enamel by saliva, moisture or oil from
water line.
2. Insufficient rinsing of etchant from tooth before bonding.
3. Inadequate drying of enamel surface precludes penetration of
resin.
4. Over – etching demineralizes enamel, reduces depth of resin
tags penetration, and removes excessive amounts of enamel.
5. Faulty bonding materials, materials with expired date.
217

218. Possible Causes of Adhesive – bracket bond failures
• Excessive force exerted on bracket from occlusion or excessive from
appliance.
• Movement of bracket during initial setting of adhesive.
• Contaminated bracket mesh (oil from hands, glove powder or
rebonded bracket).
• Adhesive not buttered into base firmly.
• Inadequate cure of light cured resin composite. 218

219. Adhesive remnant index
• The amount of adhesive remaining on the tooth surface after debonding is
measured by adhesive remnant index (ARI) given by Artun and Bergland.
• It is developed as a scoring system:
• • Score 0—no adhesive left on the tooth surface
• • Score 1—less than half of adhesive left on the tooth surface
• • Score 2—greater thanhalf of adhesive left on the tooth surface
• • Score 3—all adhesive left on tooth surface with a bracket mesh
impression
219

220. REBONDING
220

221. 221

222. RE-CYCLING
• Goal is to remove adhesive from bracket completely without damaging or
weakening the delicate bracket backing or distorting the dimensions of the
bracket slot.
Methods:
• Done by heat treatment (upto 450°c) and electro-polishing. (Heat to burn
off the resin and electro-polishing to remove oxide layer build up)
• Sandblasting
• Micro etching
222

223. CONCLUSION
Successful bonding in orthodontics requires careful
attention to three components of the system: the tooth surface
and its preparation, the design of the attachment base, and the
bonding material itself.
The future of bonding is promising. Product
development in terms of adhesives, brackets, and technical
details is continually occurring at a rapid rate. It is necessary for
the orthodontist to update and stay oriented.
223

224. BANDING
224

225. INTRODUCTION
• The chief parts of modern fixed appliances are tooth bands and arch wires
• Tooth bands are made up of metals and cemented to the teeth and provides place
for attachment of other auxiliaries like brackets, buccal tubes, lingual buttons
etc.
• These auxiliaries can be either welded or soldered to the bands. The tooth moving
forces derived from the arch wires are transmitted to the teeth through the
bracket
225

226. MAGILL was the first to use plain band cemented to the teeth.
• Steel replaced the gold as common orthodontic material, pinched bands are
welded rather than soldered.
• Preformed steel bands came into widespread use during the 1960s and are
now available in anatomically correct shapes for all the teeth.
226

227. INDICATIONS FOR BANDING
• Teeth that will receive heavy intermittent forces against
the attachments. E.g.: upper I molars
• Teeth that will need both labial and lingual attachments
• Teeth with short clinical crowns
• Tooth surfaces that are incompatible with successful
bonding
227

228. REQUISITES
• Must fit the contours of the tooth as closely as possible, there by enhancing the attachment to the teeth
• Should not extend sub-gingivally any more than is necessary for adequate retention on the teeth
• Resistant to deformation under stresses in the mouth
• Made up of an alloy that is resistant to tarnish in the mouth
• Material should have enough springiness that it can be forced over the height of contours of the teeth and
spring back slightly into undercut areas
228

229. TECHNIQUE
•materials required
•separation
•selection of material
•fabrication
•adaptation or fitting of bands
•cementation
229

230. MATERIALS REQUIRED
BAND
THICKNESS(inches)
BAND
WIDTH(inches)
INCISORS 0.003- 0.004 0.125
PRE-MOLAR 0.004 0.150
MOLAR 0.005 - 0.006 0.180- 0.200
230
• How pliers
• Double beak anterior forming pliers
• Posterior band forming pliers
• Band cutting pliers

231. SEPARATION
•In order to break tight interdental contacts
•Should be left for a week before banding
procedure
•Various types of separators include:
i.Brass wire separators (0.5/0.6mm dia)
ii.Ring separators(stretched elastic rings)
iii.Dumbbell separators(stretched ring regains
length and brings about separation)
iv.Kesling’sspring separator(coil and 2 arms)
v.Nitispring separators
231

232. WHY ADEQUATE SEPARATION IS NECESSARY?
Average periodontal ligament space-0.25 mm, placement of a 0.16-mm
orthodontic band without proper separation will risk contact with alveolar bone,
producing hyalinization areas and evoking the pain response hindering patients
from performing routine oral functions.
232

233. Fabrication of band
•Band material-adequate length-2 ends brought together-mesial and
distal embrasures
•Free ends held with How plier-buccal surface adapted with amalgam
plugger.
•Band material pinched with How & pinched through Peak pliers
•Spot welding at lingual joint
•Required inserts spot welded directly over the lingual joint
•Lingual extensions cut and polished.
•Appropriate attachments are soldered or spot welded onto
233

234. 234

235. 235

236. FABRICATING AND FITTING BANDS
• Upper molar band is designed to be placed initially by hand pressure
on the mesial and distal surfaces bringing the band down close to
the height of the marginal ridges.
Then it is driven to place by pressure on the mesiobuccal and
distolingual corners.
Final seating is with heavy biting force on the distolingual surface.
236

237. • Lower molar bands are designed to be seated initially with
hand pressure on the proximal surface and then heavy
biting force along the buccal but not the lingual margins.
237

238. • Upper premolar bands are usually seated
with alternate pressure on the buccal and
lingual surfaces.
• Lower premolar bands are designed for
heavy pressure on the buccal surface only.
238

239. CEMENTATION
• The most commonly used cements are zinc phosphate and glass ionomer
• A thick cement mix is loaded into the band in such a way that all the interior
surfaces are totally covered with cement, so that there is no bare metal.
• Now the upper aspect of the band is covered with gloved finger and the band is
pushed from above further apically using digital pressure.
• Patient is instructed to bite firmly but gently over the band.
239

240. THANKYOU
240