Bonding in Orthodontics

Dr Farisha Mohammed

1. BONDING Dr. Farisha Mohammed 1

2. CONTENTS Introduction History and Evolution of Bonding Bonding Vs Banding Properties Mechanism of Bonding Steps in Bonding Cleaning Etching Applying Primer Types of Primer Adhesive – Cements & Composites 2

3. Curing Light Types of Bonding Bracket bonding -Other Non-Enamel surface Special Conditions Conclusion References 3

4. 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 Contemporary Orthodontic Appliance 5 th ed – William R. Proffit 4

5. Bonding is a term conventionally used to describe the attachment of the bracket using bonding resins to the enamel surfaces. Both physical and chemical forces play a role in the process; however, the mechanical interlocking of the low viscosity polymer bonding agent and the enamel surface is the principal mechanism of attachment between the enamel and resin-bonding systems. Textbook of Orthodontics – Samir E Bishara 5

6. HISTORY 6

7. 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 number of preliminary reports were published on different commercially available direct & indirect bonding system. 7

8. 8 A survey conducted by LEONARD GOERLICK in 1979 JCO revealed almost 93% of orthodontists started bonding brackets (at least in anteriors )instead of banding.

9. EVOLUTION OF BONDING “An appliance which cannot be made transparent or tooth- colored should at least be made smaller” 9

10. In the mid-1960 s, Dr George Newman , an orthodontist in Orange, New Jersey, and Professor Fujio Miura , chair of the Department of Orthodontics at Tokyo Medical and Dental University in Japan, pioneered the bonding of orthodontic brackets to enamel . 10 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

11. In the early 1970s, Miura developed a technique for bonding polycarbonate plastic brackets to phosphoric acid etched enamel using a restorative filling material developed by Masuhura et al The adhesive, Orthomite (Rocky Mountain Orthodontics, Denver, Colo ), consisted of methyl methacrylate and polymethyl methacrylate with tri-n- butylborane as the catalyst Miura found that the bond strength decreased with time as a result of exposure to oral fluids. 11 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

12. Newman continued his work with epoxy resins , while Retief et al from South Africa developed an adhesive to bond metal brackets , based on research conducted by Bowen on epoxy resins. Epoxy resins did not experience significant polymerization shrinkage when setting, had the same coefficient of thermal expansion as enamel, and were cross-linked to minimize water absorption. 12 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

13. Retief et al partnered with 3M Unitek (Monrovia, Calif ) to develop a mesh grid welded onto flattened stainless steel band material with a metal bracket welded to it The primary drawback -the weld spots on the mesh base prevented the adhesive from flowing between the mesh and the foil pad properly- resulting in reduced mechanical retention 13 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

14. 14 In the early 1970s , 3M Unitek's Concise and Adaptic from Johnson&Johnson ( NewBrunswick , NJ) were popular composite restorative filling materials, formulated from the research conducted previously by Bowen. Both systems used a 2-paste bisphenol A glycidyl methacrylate ( BisGMa ) resin with quartz as a filler and amineperoxide as the catalyst. These systems were cross-linked adhesives that experienced minimal polymerization shrinkage. The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

15. At this time, metal brackets were welded to a perforated base The only complaint with perforated base brackets was that the adhesive covering the base through the perforations was affected by the oral environment so that it often became stained and discolored during routine orthodontic treatment. 15 Fig 1. Perforated metal bracket base.

16. In 1974 , Dentsply /Caulk (Milford, Del) introduced the first single-paste ultraviolet (UV) light curable bracket adhesive, Nuva Tach ; this system used a UV unfilled bonding resin ( Nuva Seal) on the enamel and a single UV curable paste ( Nuva Tach ) . Polymerized with light-emitting energy in the 280-nm range The use of these UV light cured systems was cut short when it was discovered that they were harmful to exposed skin and eyes, sometimes even resulting in burned soft tissues . 16 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

17. In the early 1980s , McNamara and Howe introduced a version of the Herbst appliance , the acrylic splint design, that was made from 3-mm-thick splint Biocryl (Great Lakes Orthodontic Products, Tonawanda,NY ) Soon thereafter, the acrylic splint expander was developed as a mixed-dentition appliance for the treatment of maxillary constriction and Class III malocclusion. 17

18. Both appliances necessitated the bonding of splint Biocryl to the maxilla , a procedure that required a strong, thin paste that adhered well to plastic and resisted washout from under the appliance. Excel was developed in 1983 by Reliance Orthodontic Products(Itasca, Ill) specifically for bonding large acrylic appliances. Excel allowed appliances to be bonded and removed successfully without decalcification occurring during treatment. 18 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

19. 19 In 1979, Ormco (Orange, Calif ) developed and patented a technique to braze mesh to a metal foil pad , eliminating strength-reducing weld spots This design allowed the adhesive to penetrate between the mesh and the foil pad, thus increasing mechanical retention The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

20. In the early 1980s , visible light–cured restorative materials were introduced in all areas of dentistry The catalyst for these adhesives was camphorquinone , which cured in the visible light range ( 440-480 nm ) with a quartz-tungsten-halogen light , making them safe for exposed eyes and skin. 20 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

21. In 1985, Suh produced Enhance for Reliance Orthodontic Products , which made bonding to fluorosed and atypical surfaces possible with any chemical or light-curing system. Enhance was applied on the etched enamel before the unfilled resin. In addition, the monomer in Enhance (biphenyl dimethacrylate ) bonded chemically to composite and metal. Clinicians - the ability to bond to any metal surface without using a metal primer or to a composite restoration without using a plastic conditioner. 21 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

22. Crypsis , a color-change adhesive , was introduced in 1986 . This 2-paste dual-cure bracket adhesive was developed and marketed by Orec (Beaverton, Ore) The 2-paste material was yellow after it was mixed but it turned tooth color when it polymerized. This color characteristic allowed the operator to see the composite flash around the bracket base and remove it before it polymerized. 22

23. The color-change mechanism was a function of the light-cure catalyst. In 2004 , several single-paste light-cured , color changing adhesives entered the market from Reliance Orthodontic Products, 3M Unitek , and Ormco . 23 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

24. In 1995, Silverman et al developed a technique for bonding metal brackets to wet enamel with no acid etching using Fuji Ortho LC (GC America, Alsip, Ill), a dual-cure glass ionomer cement . This 2-part system comprises a powder ( fluoroaluminosilicate glass) and a liquid ( polyacrylic acid, water, hydroxyethyl methacrylate [HEMA], and camphorquinone -light activator). 24

25. In 1996, 3M Unitek introduced a metal bracket system with a light-cured adhesive preapplied to the base . The operator simply etched the enamel surface, applied an unfilled resin to the enamel, and placed the bracket. The prepasting by the bracket manufacturer eliminated the need for an assistant to place the composite on the bracket base. 25 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

26. In 1998 , several hydrophilic primers were introduced. Ortho Solo ( Ormco ), Assure (Reliance Orthodontic Products), and MIP (3MUnitek) were hydrophilic bonding resins that bonded well to wet or dry enamel,making the bonding procedure more forgiving. 26 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

27. Microetching (sandblasting) became the mechanical preparation of choice in the dental restorative field in the early 1990s . Aluminum oxide , the preferred abrasive powder for intraoral microetching , created fine surface roughness and significantly increased the mechanical retention to artificial surfaces 27

28. In 2000 , self-etching primers became effective in conditioning dentin and enamel. Self-etching primers such as Transbond Plus (3M Unitek ) and SEP (Reliance Orthodontic Products) now are part of the orthodontic armamentarium because of their lack of rinsing and drying steps , steps that are necessary with traditional phosphoric acid etching. 28 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

29. In 2003, Pro Seal (Reliance Orthodontic Products) was introduced into the marketplace as a light-cured, fluoride-releasing filled sealant that would remain intact on the exposed enamel for 2 to 3 years even under toothbrushing conditions 29 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

30. In 2005, LED Pro Seal (Reliance Orthodontic Products) was introduced to accommodate the clinician using the new, cordless light-emitting diode lights that emitted a photon between 440 and 480 nm. 30 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

31. In 2010, Select Defense ( ClassOne Orthodontics,Carlsbad , Calif ) was introduced as an enamel sealant hat contained selenium , an antimicrobial. 31 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

32. 32 The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63)

33. BONDING OVER BANDING 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. 33

34. 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. Brackets can be recycled further reducing the cost. 13.Invisible lingual brackets can be used when esthetic is important . 14. Attachments can be bonded to fixed bridgeworks. 34

35. MECHANISM OF BONDING Physical - based on secondary forces – Vander Waals forces, hydrogen bonds, dispersion forces( specially when surfaces are smooth and polished ) Chemical - based on primary forces – covalent, ionic, metallic bonds. Mechanical -based on penetration of one material into another at microscopic level (when surfaces are rough). 35

36. 36

37. BONDING PROCEDURE 37

38. PRE-TREATMENT Cleansing Improves wetting Acid etching Improves adhesion micromechanical retention. Pre-treatment is necessary as mouth is complicated by saliva ,acquired pellicle , different organic and inorganic components of enamel and dentin. 38

39. CLEANING 39

40. CLEANING Removal of salivary pellicle & contaminants Salivary pellicle - When a tooth is cleaned in situ, salivary proteins and glycoproteins with a strong affinity for enamel very quickly adsorb to the tooth surface and form a very thin layer called salivary pellicle. Material used – Pumice Improves wetting 40

41. CLEANSING WITH PUMICE Polishing brushes / Rubber Cup Low-speed <20,000 rpm – Micromotor Non-fluoride pastes for 10 sec Enamel – 5-14µm in depth 41

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43. Enamel conditioning 43

44. MOISTURE CONTROL Cotton Rolls Saliva ejector Cellulose Strip Absorbant Anti- sialogues Nola System 44

45. TYPES OF ETCHANTS Strong acids 37 % phosphoric acid for 15 seconds P rovides a strong bond Weak acids 2.5 % nitric acid 17% maleic acid for 30-60 seconds 45

46. Organic acid Maleic acid ,EDTA ,citric acid, tartaric acid. Inorganic acid phosphoric acid, nitric acid. Polymeric acid poly acrylic acid 46

47. 47 Morphology of Enamel Longitudinal section under microscope Enamel prisms (rods) – 5-12 million Diameter:4-5 µm Thickness : 1000 to 2000 µm (except as it tapers toward the cervical margin) [Diedrich,1981] Extend from DEJ to outer surface Wider – Prism head Narrower – Prism tail

48. 48 Enamel is made up of a series of closely packed hexagonal 'prisms' of hydroxyapatite .  The circular or hexagonal features on the surface of enamel shown here represent the ends of these hydroxyapatite crystals. ('keyhole' or ' fishscale ' appearance ).

49. PATTERNS OF ACID ETCHING 49

50. TYPE 1- INTRAPRISMATIC – REMOVAL OF PRISM CORES Type 1 – Most common. Preferential removal of enamel prism cores & periphery intact. 50 HONEY COMB

51. TYPE 2 – INTERPRISMATIC – REMOVAL OF PRISM PERIPHERIES Type 2 - Reverse of type 1. Periphery removed and cores intact. 51 COBBLE STONE

52. TYPE 3 – BOTH TYPE 1 & 2 Type 3 – Etching pattern less distinct. Both types 1 & 2 present. 52

53. 53 TYPE 4 Pitted enamel surfaces with unfinished puzzles, maps, or networks like Type 3 -

54. 54 TYPE 5 Flat, smooth surfaces Type 5 -

55. Examples of Conditioners 35 %-37% Phosphoric acid 10 % Phosphoric acid Maleic acid EDTA Citric acid + 3% ferric chloride 37% phosphoric acid is a good etchant and conditioner . A properly etched enamel surface gives a frosty white appearance on drying. 55

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57. 57 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 . Acording to William A. Brantley decreasing etching time between 30 and 10 seconds does not affect bond strength, whereas etching for 0 or 5seconds reduces bond strength ( less than 3 MPa ) significantly. Scanning electron microscopy shows that etching with 37% phosphoric acid for at least 30 seconds produces more optical etching patterns than etching for 15 seconds.

58. 58 Concentration of Acid ? Etching with 10% or 37% phosphoric acid produces the highest bond strengths ( 28 MPa ) to enamel. No differences in bond strengths are observed when enamel is etched with phosphoric acid ranging in concentration from 2% to 37%. One study reported that 2% phosphoric acid etchant was adequate for bonding, whereas another recommended 10 – 37% phosphoric acid. Wolfgang Carstensen (AJO 1995) . Compared three acid concentration ( 37%, 2% and 5%) was used for 30 seconds to bond the brackets. The results showed that 37% phosphoric acid had a higher bond strength. The amount of adhesive left on the teeth after debonding was smaller for 2% acid than 37% and 5%, and it was concluded that 2% phosphoric acid solution is appropriate for bonding of brackets and the reduced etching could be favorable in preventing enamel damage during the treatment and at the time of debonding .

59. 59 Wasundhara (AJO ) made an invitro study to detect the etch pattern and compare the shear bond strength by using 37% and 5% phosphoric acid and it was observed that there was no significant difference in shear bond strength, but 5% phosphoric acid produced a minimal enamel loss. What is preferred procedure for deciduous teeth? Acording to Zachrisson recommended procedure for conditioning deciduous teeth is to sand blast with 50 μm aluminum oxide for 3 seconds to remove some outermost aprismatic enamel and then etch for 30 seconds with Ultra-Etch 35% phosphoric acid gel.

60. 60 Is prolonged etching necessary when teeth are pretreated with fluoride? M. Brannstrom et al(1982 AJO) suggested that extra etching time is not necessary when teeth have been pretreated with fluoride. When in doubt, check that the enamel looks uniformly dull and frosty white after etch. If it does, surface retention is adequate for bonding. Will incorporation of fluorides in the etching solution will decrease the bond strength? Fluoridated phosphoric acid solutions and gels provide an etching effect similar to nonflouridated ones and give adequate bond strength in direct bonding procedures.

61. 61 F.Garcia et al (AJO 1991) compared the enamel morphology and shear bond strength of orthodontic bonded to enamel etched with fluoridated or a non fluoridated phosphoric acid gel . The result showed that overall morphologic etching effect was similar in both groups. J .B Thornton et al found that addition of fluoride to the phosphoric acid solution reduce the decalcification adjacent to bonded brackets.

62. 62 How much enamel is removed by etching and how deep are the histological alterations ? A routine etching removes 3 to 10 μm of surface enamel. Mark Daniel et al (AJO 1980) found that a 90 second etch with phosphoric acid resulted in mean loss of 6.9µm with no significant difference between liquid and gel. Deeper localized dissolutions will generally cause penetration to a depth of about 100µm or more. .

63. 63 Are they reversible? Is etching is harmful? Although laboratory studies indicate that the enamel alterations are largely reversible ( though not completely ) it can be stated that the overall effect of applying etchant to healthy enamel is not detrimental. This is augmented by the fact that normally enamel is 1000 to 2000 µm thick, abrasive wear of facial enamel is normal and proceeds at a rate of up to 2 µm per year on facial surface are self cleaning and not prone to caries.

64. 64 On application: Dab - do not rub etchant on the enamel ..it may fracture the exposed enamel. Do not allow etch to contact skin or gingiva .

65. RINSING After etching, the enamel surface should be throughly rinsed with a continuous stream of water spray for 5-10 sec so that acid is completely washed off. DRYING This should be followed by proper drying which will produce frosty, white appearance. Contamination of the etched and dried enamel surface by saliva, moisture or blood can prevent proper bonding. If any sort of contamination occurs, repeat the procedure. 65

66. 66

67. Contemporary Orthodontic Appliance 5 th ed – William R. Proffit 67

68. 68 GEL FORM Intended area is etched DISPENSING Phosphoric acid is produced in a liquid or gel form and neither form demonstrated any negative effects on bond strength. ( Brännström & Malmgren , 1982) LIQUID FORM More area beyond the bracket base is etched due to displacement of the acid by gravitational force. Unnecessary demineralized areas are produced in the enamel surface, which can cause plaque and bacterial retention areas. Gingival structures should be carefully protected during etching with liquid form ( Øgaard & Field, 2010).

69. Alternative to Acid Etching Crystal Growth Laser Air Abrasion / Sand Blasting 69

70. Also called as Crystal bonding. Polyacrylic acid containing sulfate ions applied. Reacts with the calcium in the enamel surface forming CaSO4 Dihydrate (Gypsum) –chemical bond with enamel. Crystal enucleation site for mechanical bond with adhesives. Needle-shaped crystals Crystal growth technique (Smith & Cartz , 1973) 70

71. 71 Advantages : Easier debonding, less adhesive left on tooth and less damage to enamel. Minimal effect on the outer, fluoride-containing enamel surface. No resin tags left behind in the enamel surface. Disadvantages : Bond strength 60-80% of strength obtained with acid etching. 64.4% bond failure compared to 3.4% of conventional. (Mac phee etal 1985).

72. AIR ABRASION/ SANDBLASTING/ MICROETCHING Micro-etcher uses high speed 50 µ Aluminium oxide particles which are propelled against the surface by air pressure. 72

73. Mechanism of action: Localized melting and ablation in effect etching it through micro-explosion of entrapped water in the enamel of hydroxyapatite crystals. LASER ETCHING Converts light energy to thermal energy Lasers can be used : Neodymium-yttrium-aluminum garnet ( Nd:YAG ) CO2 Er:YAG lasers. 73

74. THANK YOU 74

75. PART 2 BONDING 75

76. CONTENTS Introduction History and Evolution of Bonding Bonding Vs Banding Properties Mechanism of Bonding Steps in Bonding Cleaning Etching Applying Primer Types of Primer Adhesive – Cements & Composites 76

77. Curing Light Types of Bonding Bracket bonding -Other Non-Enamel surface Special Conditions Conclusion References 77

78. SEALING 78

79. SEALING 79 Sealer / Primer / Intermediate resin Low viscosity resin which is applied prior to bonding 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.

80. Use of sealant led to many divergent conclusions. They might be necessary to achieve proper bond strength Its necessary to improve resistance to micro leakage . After sealant coating moisture control may not be extremely important. It provides enamel cover in areas of adhesive voids . 80

81. 5. Sealant might permit easier bracket removal & protect against enamel tear outs during debonding . ( Zachrisson BU et al 1995 JCO) 6. 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. 81

82. APPLY RESIN TO PREPARED ENAMEL SURFACES. A Colour Atlas of Acid Etch Technique – J.J. Muray , T.G. Bennet 82

83. GENERATIONS OF BONDING AGENTS 83

84. Buonocore (1956) Resin containing glycerophosphoric acid dimethacrylate Bowen N- phenyl glycine & glycidyl methacrylate ( NPG-GMA ) Bonding- chelation of bonding agent to calcium of dentine DRAWBACK Poor dentine bonding Enamel bonding is good. Poor bond strength (1 to 3 MPa ). The first commercial system of this type – Cervident , SS White I - GENERATION 84

85. 85 II – GENERATION Late 1970’s Incorporated halophosphorous esters of unfilled resins bis – GMA : bisphenol – A glycidal methacrylate HEMA : hydroxyethyl methacrylate Bonding - through an ionic bond to calcium by chlorophosphate groups. Weak bond strength Scotch Bond (3M Dental ) Clearfil (Kuraray Co. Japan)

86. 86 Late 1980’s, principle- partially removed or modified smear layer The primer contains hydrophilic resin monomers which include 4–META : hydroxyethyl trimellitate anhydride OR BPDM : biphenyl dimethacrylate Hydrophilic group infiltrates smear layer Bonding : Smear layer softening – resin cures which forms hard surface. Unfilled resin adhesive is applied, attaching cured primer to the composite resin. Drawback – Bonding to smear layer Mirage bond Scotch bond Prisma Universal bond 2 and 3 III - GENERATION

87. IV - GENERATION 87 Total etch technique Complete removal of the smear layer is achieved 40% phosphoric acid for 15 to 20 seconds Bond Strength – 17-25 Mpa All bound -2 (BISCO) Scotch bond Multipurpose (3M) Optibond FL (Kerr)

88. V - GENERATION ONE –BOTTLE SYSTEM Primer and adhesives are combined into one solution Show high bond strength values both to the etched enamel and dentin due to adhesive lateral branches and hybrid layer formation. Total etching was done with 35 - 37% phosphoric acid for 15 to 20 secs . Bond Strength – 20-25 Mpa Single bond (3M), One step (BISCO), Prime and Bond ( Dentsply ) 88

89. VI - GENERATION Etchng was not required at least at the Dentinal interface - they contained dentin conditioning agent as one of their components Drawbacks: Multiple components Multiple steps 89

90. VII - GENERATION All in ONE I - Bond Etching Priming Bonding Late 1990’s & early 2000’s 90

91. All in one 91

92. Transbond™Plus Self Etching Prime Squeeze liquid from black reservoir towards the applicator Squeeze liquid from white reservoir into purple Churn and swirl 92

93. A self etching self adhering flowable composite technology eliminates the need for separate bonding application step with composites for direct restorative procedures. Stable nanofiller that will not settle out of dispersion. Highly functionlised SiO 2 Nano Particle - < 20nm Bond Strength – 30Mpa Curing time – 35 sec Vertise flow (Kerr), Single Bond, Optic Bond Solo Plus, Adper Single Bond 2 adhesive, Futurabond DC, Voco , Germany 3M 93 EIGHTH GENERATION

94. MOISTURE INSENSITIVE PRIMERS (MIP) Moisture – Resistant An aqueous solution of methacrylate functionalised polyalkenoic acid copolymer & hydroxyethyl – methacrylate Excess interfacial water ionizes carboxylic gps forming hydrogen bonded dimers , thus water is incorporated in bonding mechanism Application of primer on wet enamel surface . Useful in difficult moisture condition. eg.impacted teeth, partialy erupted teeth Transbond MIP (3M). 94

95. 95 In vitro study Compared the bond strength of bracket bonded with hydrophilic primer with conventional primer Concluded that the bond strength obtained with hydrophilic prime were significantly lower than conventional primer S.J.Little Wood et al ( BJO 2000 )

96. TYPES OF ADHESIVES Cements Composites 96

97. Matrix type Resin matrix Salt matrix Salt & resin matrix Polymerization Initiation Mechanism Chemical cure Light cure Dual cure CLASSIFICATION OF BONDING MATERIALS Thermocure Fluoride Content Filler Content Acrylic resins Diacrylate resins Glass ionomer cements Resin – ionomer hybrids Fluoride releasing systems Nonfluoride releasing systems Low or unfilled Highly filled 97

98. Composite resin Resin matrix monomer (BIS-GMA, UEDMA,TEGDMA) Initiator (Benzyl peroxide,Campharoquinone ) inhibitors (4 Methoxy phenol) pigments Inorganic filler glass quartz colloidal silica Coupling Agent OCH 2 CHCH 2 O-C-C=CH 2 CH 2 =C-C-O-CH 2 CH-CH 2 O -C- CH 3 CH 3 CH 3 CH 3 OH OH O O Bis -GMA CH 3 -C-C-O-CH 2 -CH 2 -CH 2 -Si-OH CH 2 O OH OH Bonds with filler Silane Bis -GMA Bonds with resin 3 D combination of atleast two chemically different materials with a distinct interface separating the components

99. Light activated resins UV light: Initiator- Benzoin ethyl ether Activator- UV light (wavelength of 365nm) Visible light : Initiator- Camphorquinone 0.25% wt Amine accelerator- Dimethyl-aminoethyl-methacrylate (DEAEMA 0.15%) Activator- visible light(420- 450nm) Chemically activated resins Initiator- Benzoyl peroxide Activator- Tertiary amine ( dihydroxy ethyl p toludine )

100. Two phase/ Mixed adhesives- (Concise 3m) One paste initiator & activator on the other Polymerization initiation by mixing of pastes Start of mix Start of gel Initial set Final set Working time Gel period Working time- brackets are placed and positioned Gel period- brackets must not be placed or positioned Final set- archwires may be placed Chemical cure adhesives

101. Clinical handling Time consuming Properties Increased exposure of components to air induces oxygen inhibition. Mixing introduces defects in the form of air entrapment and formation of voids.

102. Polymerization initiation Bonding agent on the etched enamel and bracket backing. One paste under light pressure Clinical handling Efficient application Limited time requirements. Activator sealant Adhesive paste Enamel and bracket sides of adhesive are more polymerized relative to middle zones. One phase / no mix [Rely - a – Bond( reliance),Unite (3M)]

103. Light cure sealant Light cure paste Light cure adhesives Polymerization initiation by exposure to light curing source Extended working time (command setting). Useful in situations where quick set is required- Eg.attachment on impacted canine after surgical uncovering with the risk for bleeding. Bond strength has been studied extensively and supports their use. (Theodore)

104. 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. Dual cure adhesives

105. Polymerization initiation Through exposure to heat Used for indirect orthodontic bonding and restorations. Properties Superior properties : increased polymerization rates. Use is limited as increased temperature is required to initiate polymerization and the necessity for adapting an indirect bonding set up. Thermocure

106. Setting Reaction: The hydrogen ions of the acid attack the glass particles in the presence of water releasing calcium, strontium, and aluminium ions. The metal ions combine with the carboxylic group of the polyacid to form the polyacid salts matrix and the glass surface is changed to a silica hydrogel . GLASS IONOMER CEMENTS Invented -1969 reported 1971 by WILSON AND KENT POWDER LIQUID P oly alkenoic acid (carboxyl containing acid) Flouroalumino silicate glass 106

107. GIC Advantages Disadvantages Fluoride release Hydrogel phases Moisture tolerance Bond strength less than that of composite. Hydrogel phase: responsible for the uptake and release of added environmental fluoride from topical gels, rinses & dentifrices. 107

108. 108 Use of GIC for direct bonding was described by White in 1986 . Many in-vitro studies have suggested that GIC gave a weaker bond strength with higher bond failure rates. Miguel (AJODO 1995) Bond strength of 2.5-10 Mpa . (Axel 1992)

109. GIC’S USED FOR BONDING TO CERAMIC BRACKETS CACCIAFESTA et al (1998) ( european journal of orthodontics) The lower bond strength of glass ionomer cements might be advantageous with ceramic brackets where high bond strengths have been associated with enamel damage. 109

110. GIC COMPOSITE RESIN MODIFIED GIC COMPOMER PMCR’S (POLY-ACID MODIFIED RESIN) 110

111. Polyacid + fluroalumino silicate Glass particles Monomer+photoinitiator +light Monomer+initiator + catalyst RMGIC’S A cid –base P olymerization (light –initiated) Polymerization (chemical initiator) COMPONENTS REACTION TYPE 111

112. ADVANTAGES: Polymerization proceeds faster than acid-base Reaction resulting in improvement of physical properties, especially resistance. RMGIC-tolerates moisture similar to GIC ’s. Improved physical properties & more stable hydrogel phases compared with GIC’s Polymerization of resin monomers hastens initial hardening of RMGIC,s without interfering with acid-base setting reactions (or) any other properties. Micromechanical interlock after polymerization 112

113. Resin Matrix composite- No water Filler - Ion leachable aluminosilicate glass No acid base reaction, but light activated polymerisation . Modified composites ( Compomers or poly acid modified composite resins) Study comparing GIC, RM GIC, Compomer , Light cure & chemical cure Resin adhesive ( MILLET 1999, ANGLE) No significant difference in debonding forces between RM GIC, Compomer & Resin Adhesives except GIC. The amount of adhesive left in the teeth with RM GIC was nil; half for GIC, & most of it for other adhesives.

114. Properties Bond strength comparable to conventional chemical cured systems. Efficient mode of bonding but further evidence is required for its efficacy. Adhesive Precoated Brackets APC PLUS [3M] Color change adhesive Uniform coating of adhesive on each bracket allowing for easier flash clean up. Moisture tolerant adhesive Release of a small amount of fluoride. Can select the bracket type.

115. CURING LIGHT 115

116. CURING LIGHTS Conventional curing lights High performance halogen lights ( optilux 501) Plasma Arc Lights (PAC) Lasers LED’s (Light emitting diode)

117. Conventional Curing lights : Use halogen bulbs filtered to produce blue light. Cure adhesives under bracket in 20-30 sec. High performance halogen curing lights: 80 watts tungsten/quartz/halogen bulb Cures under metal brackets in 8 seconds and under ceramic brackets in 5 seconds . Has boost mode to increase the output up to 1000 watts. hence allows metal brackets to be cured in 5 seconds L

118. 119 Plasma arc lights: Generates a lot of heat and large fan is required. Adhesive is cured in 5 seconds under metal brackets and 3 seconds under ceramic brackets Plasma arc carbon (PAC) lamps have a tungsten anode and cathode in a quartz tube filled with xenon gas. The gas becomes ionized and forms a plasma that consists of negatively and positively charged particles and generates an intense white light when an electrical current is passed . Plasma arc lights are contained in base units rather than in “guns” because of the high voltage used and heat generated. Light intensity- 900  mW /cm 2 ( Zacrisson & Büyükyılmaz,2005; Büyükyılmaz & Üşümez , 2003 )

119. Laser lights: Emits monochromatic coherent light source Generate lot of heat Cumbersome

120. Led’s(LIGHT EMITTING DIODES ) 1995 mills et al proposed solid state LEDs for polymerization. Solid state light emitting diode technology Use junctions of doped semiconductors to generate light. They directly emit light in the blue region. LED curing of 20 and 40 seconds yielded statistically similar results to curing of 40 seconds by conventional halogen light sources. ( Zacrisson & Büyükyılmaz,2005)

121. 122 Advantages : Have small size, are cordless. Quiet Generate minimal heat. Life time of > 10000 hrs Require no filters to produce blue light Lightweight, Portable and effective Take little power to operate. e.g.Ledmax-4

122. 123 • All new light sources cure resins faster than conventional halogen lights. • Fast halogen sources are more brand specific but generate low heat and are less expensive than plasma lights and LEDs. • Plasma arc lights offer the shortest curing times but are expensive and generate heat. Light-emitting diodes have small size, are cordless, are quiet, generate minimal heat, and perform favorably compared with conventional and fast halogen sources. Use protective eye glasses that have filtration effects.

123. TYPES OF BONDING 124

124. 125

125. DIRECT BONDING Easier, Faster Less expensive Drawbacks proper positioning is crucial. Has to be done rapidly and accurately . 126

126. PLACING BRACKET ON TOOTH A Colour Atlas of Acid Etch Technique – J.J. Muray , T.G. Bennet 127

127. PROBE USED TO CHECK THE BRACKET POSITION TO THE LONG AXIS OF TOOTH A Colour Atlas of Acid Etch Technique – J.J. Muray , T.G. Bennet 128

128. BRACKETS IN POSITION A Colour Atlas of Acid Etch Technique – J.J. Muray , T.G. Bennet 129

129. INDIRECT BONDING First described by Silverman & Cohen in 1972 . Placing brackets in a model Use template or tray to transfer Common agent – “No-mix” chemically activated materials More useful in Lingual Orthodontics Types Clear Tray PVS Transfer Tray Memosil Tray Single Unit Transfer Tray 130

130. CLEAR TRAY 131

131. 132 Clear Transfer Trays and Adhesives Clear vinyl trays made on a pressure-forming machine such as the Biostar from Great Lakes Orthodontics have largely replaced the original silicone tray materials. Advantage Provide a clear field of vision Can be easily sectioned to facilitate clinical delivery Makes possible the use of light cured materials with light cure adhesive.

132. 133

133. HIRO SYSTEM 134

134. MEMOSIL 135

135. WINDOW TRAY DAS’s Incisal and Occlusal Window Tray PVS – Heavy / Medium Body 136

136. SINGLE UNIT TRANSFER TRAY 137

137. 138 Advantages of indirect bonding Clinical Technical Time in motion combined with ergonomics and efficiencies

138. 139 Clinical Improved patient comfort No separators or band spcaes Better environment for placing ceramic brackets on mandibular teeth Placement of brackets in the posterior , with level slots and a passive archwire. Easier to build in overcorrections Better in/out control Improved vertical control

139. 140 Technical Enhanced TMJ health Improved periodontal health & better hygiene Increase post treatment stability Ergonomics & efficiencies Optimal use of time and better staff utilization Fewer appliance placement appointments and simplified and shortened debonding Healthier ergonomically

140. 141 Disadvantages Technique sensitive Improper seating of indirect tray may require complete redoing of the procedure. Amount of composite flash involves extra chair time to remove. Posterior attachments likely to fail Additional set of impressions required Excessive laboratory time is required for construction of the indirect setup Lab costs.

141. BONDING ON OTHER NON-ENAMEL SURFACE 142

142. 143

143. DORON HARARI et al (AJO) 2003 PORCELAIN - CERAMIC BRACKETS Preparing the porcelain surface Mechanical retention of adhesive to bracket bases 9.6% HF gels 2-4 minutes are used for etching porcelain surfaces 144

144. BONDING TO CERAMIC RESTORATIONS Fine diamond bur Sandblasting Micro-etching with alumino silicates 5%HCL Silica coating Surface conditioning methods 145

145. Buyukyilmaz T AND Zachrisson (1998) ANGLE ORTHODONTICS Bonding to gold- intra oral sandblasting is superior to roughening with diamond bur Tin plating improves bond strengths but only marginally . This procedure is not recommended by the FDA and hence not recommended for orthodontic purposes . BONDING TO GOLD 146

146. BONDING TO AMALGAM Intra-oral sandblasting for 2-4 seconds at a distance of 10mm . Use a META intermediate resin with a short curing time such as reliance metal primer. 147

147. BONDING TO VENEERS Kao and johston (1991)journal of prosthetic dentistry. Reported fracture incidence on debonding orthodontic brackets from porcelain veneers Lee –knight et al (1991)AJO IT may be worth using a ceramic reinforced resin bracket , such as ormco spirit or GAC Elan , on veneers as these brackets are extremely easy to debond . 148

148. SPECIAL CONDITIONS 149

149. ETCHING IN FLUORIDATED TEETH Fluoride ion Hydroxy –apatite crystal Resistant to acid-dissolution Caries prevention Hence fluoridated teeth requires longer etching time. 150

150. 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. DRAWBACKS OF BONDING 151

151. CONCLUSION Bonding of brackets has changed the practice of orthodontics and has become a routine clinical procedure in a remarkably short time. Modifications of technical devices, sealants and adhesives, attachments, and procedures are continuing.

152. In the past, the best clinical results were achieved by orthodontists who had the best wire bending skills. However, the best results in the future will be achieved by those orthodontists who are best at accurate bracket positioning. Most of the problems associated with bonding techniques have faded away.

153. REFERENCES Graber, Vanarsdal , Vig OP Kharbanda Contemporary Orthodontic Appliance 5 th ed – William R. Proffit Textbook of Orthodontics – Samir E Bishara A Colour Atlas of Acid Etch Technique – J.J. Muray , T.G. Bennet Textbook Of Operative Dentistry, Vimal Sikri Phillip’s Science Of Dental Materials The evolution of bonding in orthodontics ,Paul Gange - Am J Orthod Dentofacial Orthop 2015;147:S56-63) 154

154. Crystal growth on outer enamel surface - AJO-DO 1986; 89:183 - 193 , Maijer and Smith 155