Recent research findings in orthodontic bonding /certified fixed orthodontic courses by Indian dental academy


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Recent research findings in orthodontic bonding /certified fixed orthodontic courses by Indian dental academy

  1. 1. Recent Research findings in Orthodontic Bonding Materials INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Direct bonding of orthodontic attachments to teeth with the use of epoxy resins was introduced in 1950s and the use of BIS GMA in the mid 1960s. Acid-etching technique in the 1950s to bond dental restorations to tooth structure was the breakthrough point in the history of orthodontic bonding. The basis for the adhesion of brackets to enamel has been enamel etching with phosphoric acid, as first proposed by Buonocore in 1955.
  3. 3. In the past few years, there has been a major research drive to increase bond strength between dental materials and dental hard tissues, although most of the adhesive systems have provided clinically acceptable bond strengths. Achieving a low bond failure rate should be a high priority objective – replacing loose brackets is time consuming, costly.
  4. 4. Continuous search is on for higher bond strengths, better adhesives and materials that will bond in presence of saliva. There is a need to improve the bonding procedure to maintain clinically useful bond strengths while minimizing the amount of enamel loss and to simplify the technique reducing the number of steps
  5. 5. In the past decade, one has witnessed unprecedented progress in bonding to enamel with various materials techniques and auxiliaries involving glass ionomer bonding, self-etching primers, and new, powerful light-curing sources, along with self-ligating brackets and a different treatment concept, the Invisalign technique.
  6. 6. This distinctive pattern of progress can be attributed to the fact that the specialty’s armamentarium largely depends on the advancement of technology in various materials science fields and in other dental specialties for the development and application of new materials. For example, the emergence of nanotechnology and its growing application in industry has influenced the manufacture of composite resin by introducing nanofilled composites
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  8. 8. Enamel preparation: acid etching, Crystal growth, laser, or air abrasion? Duration of etching – Studies and clinical experience indicate that 15-30 sec is probably adequate for etching most young permanent teeth.( Brannstrom 1978,1982, Newmann 1982, Wang 1991) There is no evidence that indicates any significant increase in bond strength between 15 and 90 sec of permanent tooth etching. (Barkmeier et al 1987, Osorio et al 1999)
  9. 9. 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. Type of etchant – Etching with 10% or 37% phosphoric acid produces the highest bond strengths (28Mpa) – Brantley & Eliades 2001. Gardner & Hobson (2001) documented that enamel etching with orthophosphoric acid provides similar bond strength with much lower acid concentrations than the original 37%.
  10. 10. Wang and colleagues ( Angle 1994) evaluated several phosphoric acid concentrations from 2% to 80% and found that best bond strength was achieved with 30%40% concentrations. Among the other techniques and materials tried, the most prominent was the Crystal growth system. This method, originally developed by Maijer and Smith at the University of Toronto, attempted to reduce the depth penetration of treatment into enamel. (Maijer & Smith, AJO1982)
  11. 11. It involves use of polyacrylic acid solution containing sulfate ions, which causes growth of calcium sulfate dihydrate crystals on the enamel surface. These crystals in turn retain the adhesive. Bond strength was found to be 60-80% less than with conventional acid etching. (Artun & Bergland AJO 1984, Farquhar AJO 1986 , Read EJO 1986)
  12. 12. Use of 10% maleic acid for etching resulted in a lower bond strength.( Powers & Kim, Semin Orthod 1997) Another technique – micro etching with small intraoral sandblasters. Takes about 3 seconds. They use 50µm white or 90µm tan Aluminium oxide powder connected to a compressed air source in the operatory. Operates at about 7kg/cm2 optimum pressure. If patient is allergic to Aluminium oxide – Silicon carbide can be used.
  13. 13. Composite to metal adhesion can be improved by atleast 300% with intraoral sandblasting. Highly effective in bonding to gold and other metals, as well as porcelain. Other clinical applications – Removal of composite from loose brackets before rebonding. Increasing the retentiveness of stainless steel bands.
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  17. 17. Sandblasting without acid etching produces lower bond strength than conventional acid etching and consistently results in bond failures at enamel adhesive interface.( Olsen M, Bishara SE AJO 1997, Reisner AJO 1997). Reisner (1997) also reported that sandblasting followed by acid etching produces bond strengths comparable to or higher than acid etched enamel.
  18. 18. D.N Kapoor, V.P. Sharma, Pradeep Tandon, Kamlesh Pandey: Comparative evaluation of Tannic acid, Citric acid and phosphoric acid as etching agents for direct bonding (JIOS 2002) Concluded that: 1) Application of 37% phosphoric acid for 15 seconds produced comparable etching topography when 50% tannic acid was applied for 90 seconds. 2) Assessment of penetration depth revealed that 37% phosphoric acid dissolves more enamel than tannic acid or citric acid
  19. 19. 3) 1 min application of 50% citric acid did not result in attainment of adequate bond strength. 4) 50% Tannic acid when applied on enamel for 90 sec provided the tensile bond strength closer to 37% phosphoric acid. So 50% Tannic acid could be an alternative to phosphoric acid for etching as it dissolves lesser amount of enamel and at the same time provides similar tensile bond strength.
  20. 20. Laser etching – Application of laser energy to an enamel surface causes localized melting and ablation. Removal of enamel (etching) results primarily from the micro-explosion of entrapped water in the enamel. In addition, there may be some melting of hydroxyapatite crystals.
  21. 21. Laser etching of enamel by Nd: YAG laser typically produces lower bond strengths than does acid etching. ( MacDonald et al JDR 1994) Carbon dioxide laser etching of enamel have shown that bond strengths of 10 MPa can be obtained reliably. (Ma T & Flint W AJO 1997).
  22. 22. Self etch adhesive systems New bonding systems were developed to combine conditioning and priming agents into a single acidic primer for simultaneous use on enamel, eliminating steps of separate etching, rinsing, and drying. The use of a self-etching primer (SEP) would have the advantage of a faster and simplified application technique, allowing adequate etching and priming of enamel in only one step.
  23. 23. In addition to saving time, fewer steps in the bonding process might translate into fewer procedural errors, minimizing technique sensitivity. Ex- First Step (Reliance Orthodontics, IL) Transbond Plus ( 3M Unitek, CA), Ideal 1 ( GAC Orthodontic products, NY) Prompt L-Pop (3M ESPE, Seefeld, Germany)
  24. 24. The Active ingredient of the self-etching primers (SEPs) is a methacrylated phosphoric acid ester that dissolves calcium from hydroxyapatite. Rather than being rinsed away , the removed calcium forms a complex and is incorporated into a network when the primer polymerizes. Etching and monomer penetration to the exposed enamel rods are simultaneous, and the depth of etch and primer penetration are identical.
  25. 25. Acidic primer solutions also demineralize the dentin and encapsulate the collagen fibers and hydroxyapatite crystals. This simultaneous conditioning and priming allows penetration of the monomer into the dentin. The adhesive resin component will then diffuse into the primed dentin, which produces a “hybrid layer.”
  26. 26. The etching process is stopped by 3 mechanisms: 1.The acid groups attached to the monomer are neutralized by forming a complex with calcium from hydroxyapatite. 2.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. 3. As the primer is light cured and the primer monomers are polymerized, transport of acid groups to the interface is stopped.
  27. 27. 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
  28. 28. 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.
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  32. 32. Bishara et al (AJODO 2001) evaluated the effectiveness of using Prompt L-pop (ESPE, Seefeld, Germany) to bond orthodontic brackets with composite resin. According to the results, this SEP provided significantly lower (but clinically acceptable) shear bond strength (mean, 7.1 ± 4.4 MPa) when compared with a conventional etch/priming technique before bonding brackets with Transbond XT adhesive paste (3M Unitek, Monrovia, Calif).
  33. 33. Arnold et al (AJODO 2002) compared the shear bond strengths of metal brackets bonded with Transbond Self Etch Primer and conventional acid etch technique. They found no significant difference in the bond strength obtained with the two techniques.
  34. 34. Cal-Neto and Miguel (Angle Orthod 2006) did a Scanning Electron Microscopy evaluation of the bonding mechanism of Transbond Self-Etching Primer on enamel. Compared with phosphoric acid, Transbond Plus SEP produced a uniform and more conservative etch pattern, with regular adhesive penetration and a less aggressive enamel demineralization. The resin tags were shorter than those observed in control group.
  35. 35. Enamel etching patterns with phosphoric acid and Transbond SEP
  36. 36. A new product Adper Prompt L-pop (3M ESPE, St Paul, Minn), was introduced to improve enamel and dentin bond strengths. Adper Prompt contains different percentages of the same components as the original Prompt Lpop. The manufacturer claims that maximizing bond strength has been achieved, in part, by optimizing the relative amounts of nonacid functional methacrylates with acidic methacrylated phosphoric esters.
  37. 37. Adper Prompt also introduces better activation control and other chemical modifications enhancing a uniform adhesive film, improving the quality of hybridization between the adhesive and the enamel surface.
  38. 38. Cal-Neto et al (Angle Orthod 2006) found no difference in bond strength whether a conventional etching and primer or Adper Prompt L-pop was used. (16.24 and 13.56 Mpa respectively) The amount of adhesive on the enamel after debonding was significantly less when using Adper Prompt than when using phosphoric acid. Their results indicated that Adper Prompt is potentially adequate for orthodontic bonding needs.
  39. 39. However in study by Zafer C Cehrell (AJODO 2005) where 4 self etch primer system { Prompt L Pop, Clearfil SE Bond, FL Bond, One Up Bond } , a non rinse conditioner and acetone based adhesive system ( Prime & Bond NT ) and conventional adhesive Transbond XT were assessed for shear bond strength. Shear bond strength of all 5 experimental groups were all significantly lower than that of Transbond XT, but not different from one another. ( Range of 1.72 ± 0.13 to 1.77 ± 0.14 MPa). Transbond XT – 10.5 ± 0.86 MPa.
  40. 40. Difference from other studies – a) Bonding done on intact enamel instead of ground enamel surfaces. b) Lack of thermal agitation which effects bond strength. C) Biodegradation of the adhesive & composite as a result of immersion in water or exposure to oral fluids leading to decreased bond strength values over time. In present study specimens were stored in water for 6 weeks and the water was changed every week.
  41. 41. K.House & A.J. Ireland ( J.O. 2006) assessed the in vivo bond failure of the single component self etching primer system Ideal 1 ( GAC Orthodontic Products) & compared it with the conventional acid etching using a 37% phosphoric acid. Total of 339 teeth were bonded with Ideal 1 and failure recorded at 1,6 & 12 months.
  42. 42. The study found that enamel pretreatment with Ideal self etching primer system results in an unacceptably high bond failure rate ( 72.4% at 12 months) compared to conventional acid etching (14.8% at 12 months).
  43. 43. Self-etching Primers: Is Prophylactic Pumicing Necessary? A Randomized Clinical Trial Antonia M. Burgessa; Martin Sherriffb; Anthony J. Ireland ( Angle 2006) The purpose of this clinical trial was to determine whether pumice prophylaxis is required before the use of a self-etching primer (SEP). Data on bond failure were collected at 6 and 12 months after appliance placement. Very high bond failure rates of 55.5% for the nopumice group and 33.2% for the pumice group, were recorded.
  44. 44. This randomized, cross-mouth clinical trial suggests that the omission of pumice prophylaxis before orthodontic bonding with a SEP has a significant effect, leading to an increased bond failure rate. However, with the First Step SEP used in this clinical trial, the observed clinical bond failure rates were still unacceptably high at 33.2%, such that this material cannot be recommended for clinical use.
  45. 45. Moisture insensitive primers Ex – Transbond MIP ( 3M Unitek, CA) , Assure ( Reliance Orthodontics, IL), Ortho Solo Universal Bond Enhancer (Ormco/”A” Company, CA). The main reactive component of this product is a methacrylate-functionalized polyalkenoic acid copolymer originally used in dentin bonding systems. Excess interfacial water ionizes the carboxylic acid groups forming hydrogen bonded dimers.
  46. 46. In addition, a reversible breaking and reforming of calcium polyalkenoic acid complexes with enamel is established, providing some stress relaxation capacity. Thus, a dynamic equilibrium occurs at the interface, incorporating water in the the bonding mechanism. This minimizes the detrimental plasticizing effect of water that occurs with moisture contamination of conventional bonding agents.
  47. 47. Schaneveldt and Foley (AJODO 2002) evaluated the effectiveness of 2 moisture-insensitive primers, Transbond MIP (3M Unitek, Monrovia, Calif) and Assure (Reliance Orthodontic Products, Itasca, Ill) and compared them with a control hydrophobic primer, Transbond XT (3M Unitek). Both bonding systems provided adequate bond strengths whether saliva contamination occured before or after the application of the hydrophilic primers. Therefore, additional mechanical preparation and reetching of the enamel surface after saliva contamination would not be required
  48. 48. The hydrophilic resin sealants or primers polymerize in the presence of a slight amount of water, but they will not compensate routinely for saliva contamination. When bonding to enamel, one must place the resin sealant or resin primer onto the prepared enamel before the pellicle (biofilm) from the saliva, This is crucial for a successful bond.
  49. 49. Ashima Valiathan, Ashil A.M. Kerala Dental Journal 2006 (In press) studied the efficacy of Transbond Moisture insensitive primer in vitro, in the dry state and in the presence of saliva and compared it with conventional Transbond XT. It was found that in the presence of salivary contamination, brackets bonded using Transbond MIP gave significantly higher bond strength (14.53 Mpa) as compared to brackets bonded with conventional primer (9.36 Mpa)
  50. 50. Moisture active adhesives In contrast to MIP’s, these require rather than tolerate the presence of moisture for proper polymerization. These materials are available as pastes and possess a completely different composition and polymerization mode, requiring no bonding agent. A recent product based on a cyanoacrylate formulation (Smart-bond, Gestenco Intl AB, Sweden) has demonstrated superior properties, excellent in vitro performance and easy clinical application without the need for etching and liquid resin coating.
  51. 51. Setting reaction: 1. Isocyanate group + Water carbamic acid component Unstable CO2 + Amine 2. Amine + residual isocyanate groups Crosslinking of adhesive through substituted urea groups.
  52. 52. Bishara et al (AJODO 2003) reported that Smartbond cyanoacrylate adhesive has adequate bond strength 24 hours after initial bonding, but its strength decreases by 80% after thermocycling between 5°C and 55°C
  53. 53. Srivastava A; Gorantla S; Valiathan A. (TIBAO 2002) compared the bond strength of two indigenously developed cyanoacrylates (N-Butyl cyanoacrylate and Isoamyl-2-cyanoacrylate) with a conventional self-cured composite (Right On). The results showed that although the initial bond strength of N-Butyl cyanoacrylate was higher than the control composite, it deteriorated when stored in physiologic saline for 48 hours.
  54. 54. Isoamyl-2-cyanoacrylate had significantly lower bond strength when compared to the other samples in all the three groups under study. This study showed the need for further work to be done with cyanoacrylates to decrease their bio-degradability, so that they can be clinically useful in orthodontics.
  55. 55. James Sunny P, Valiathan A (TIBAO 2003) performed an in vitro study to compare shear bond strengths of brackets bonded with Smart Bond and with a conventional composite (RightOn) respectively. Measurements were performed at 1 hour (dry), 24 hrs and 48 hrs (in artificial saliva). Composite showed higher bond strength than cyanoacrylate at all time intervals. Smartbond achieved a maximum bond strength of 5.07 Mpa at 24 hours, which declined at 48 hours. The authors concluded that Smartbond might not be a better option for bonding compared to conventional composite.
  56. 56. Resin modified glass ionomer cements Ex - Fuji Ortho LC ( GC America, IL). Research has however demonstrated poor bond strength with GICs, about 2.4 to 5.5 MPa, by using either phosphoric or polyacrylic acid. GICs also have a greater bracket detachment rate than composite resin systems. with the addition of a small amount of light-activated resin, many of the poor early physical and mechanical properties of GIC could be improved.
  57. 57. These improvements were incorporated in the material known as resin-modified glass ionomer (RMGIC) cement. Wide variations of bond strengths of RMGIs to enamel have been reported in the orthodontic literature— from 5.4 to 18.9 MPa.
  58. 58. A study comparing the bond strength between an RMGI and a composite resin reported bracket failure rates of 5% for RMGI and 8.3% for composite. (Fricker, AJODO 1998). In a Randomized controlled clinical trial by Gorton & Featherstone ( AJODO 2003) the quatitative microhardness tests of teeth bonded with Fuji Ortho LC showed significantly less mineral loss compared with teeth bonded with light cured composite resin ( Transbond XT).
  59. 59. Pretreatment with polyacrylic acid facilitates a chemical bond between the Glass ionomer and the enamel and thus should be performed before bonding with Glass ionomer. RMGIC are also material of choice when bonding in situations of extreme wetness like in second molar region.
  60. 60. Sarin Koyal and Valiathan A ( JPFA 2003) compared the bond failure rates of Fuji Ortho LC and Transbond XT clinically using a split mouth technique, over a period of 6 months. The study revealed that Transbond XT and Fuji Ortho LC had a comparable bond failure rate . There were no significant differences in the plaque and gingival index in the two groups. They concluded that Fuji Ortho LC is a suitable alternative for orthodontic bonding.
  61. 61. Poly acid modified resins (Compomers) Polyacid-modified composite resins, also known as compomers, were developed to bring the features of caries inhibition and carboxyl chelation to resins. Compomers are single-component systems consisting of aluminosilicate glass in the presence of carboxyl modified resin monomers and light-activated conventional resin monomers. After light-activation of the compomer, it is postulated that water sorbs into the compomer, allowing a delayed acid-base reaction that may release fluoride and other remineralizing ions from the aluminosilicate glass.
  62. 62. Compomer bonding studies have failed to confirm the chelation of carboxyl groups to enamel or dentin. The fluoride release from compomers is lower than that from GICs but higher than that from resins. Fluoride recharging and caries inhibition of compomers have been reported. Their early setting strengths are superior to those of the RMGICs but inferior to those of the resin adhesives. Example: Dyract AP.
  63. 63. Giomers A new category of fluoride-containing esthetic restorative material has recently been introduced to the dental profession. The giomer uses prereacted glass ionomer technology to form a stable glass ionomer phase in the material. This differs from compomers in which the fluoroaluminosilicate glass particles do not react until water is taken up into the restoration.
  64. 64. Both giomers and compomers require a resin bonding system after acid etching. Manufacturers of giomers claim fluoride release, biocompatibility, and smooth surface finish.
  65. 65. Chitnis et al (AJODO March 2006) compared the shear bond strength of orthodontic brackets bonded to tooth enamel with 4 adhesives: a commercially available giomer material, a polyacid modified composite resin, a resin-modified glass ionomer and a standard resin-based composite adhesive. The conventional Resin cement and the RMGI cement provided significantly higher orthodontic bond strengths than the Poly Acid modified composite resin and the giomer materials when attaching metal brackets to tooth enamel. The authors concluded that current RMGI orthodontic cements might provide acceptable bond strengths.
  66. 66. Ormocer Ormocer is an acronym for organically modified ceramic technology. Ormocer materials contain inorganic-organic copolymers in addition to the inorganic silanated filler particles. It is synthesized through a solution and gelation processes (sol-gel process) from multifunctional urethane and thioether(meth)acrylate alkoxysilanes. Ormocers are described as 3-dimensionally cross-linked copolymers.
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  69. 69. Ajlouni, Bishara et al (Angle Orthod 2004) compared the shear bond strength (SBS) of an Ormocer (Admira)with Transbond XT (3M Unitek, Monrovia, Calif). The mean SBS for Admira was 5.1 MPa and that for Transbond XT was 4.6 MPa. It was concluded that the new material, Ormocer, which is an organically modified ceramic restorative material can potentially have orthodontic applications if available in a more flowable paste.
  70. 70. Advantages of Ormocer : 1. No residual monomer content 2. Coefficient of thermal expansion similar to natural tooth strucure 3. Significantly lower wear rate 4. Protection against caries
  71. 71. Recent innovations also include the development of light activated color change adhesives which help identify excess adhesive for removal during the bonding procedure. A new fluorescing adhesive paste ( Pad Lock, Reliance Orthodontics, IL) discloses not only the flash produced at bracket placement, but the adhesive remnants left after debonding & cleanup.
  72. 72. Pro-Seal (Reliance Orthodontics, IL) is a fluoride filled , light cured sealent with a propietary catalyst that sets the resin without an oxygen inhibited layer. Its complete polymerization prevents oral fluid absorption & reduces toothbrush abrasion. It can inhibit long term decalcification ,even in patients with poor oral hygiene.
  73. 73. Manal M. Soliman Samir E. Bishara ( Angle 2006) measured the rate and amount of fluoride ions released from the sealant over a period of 17 weeks and determined whether the fluoridereleasing sealant has a recharging ability when fluoride ions are reintroduced into the environment. Disc-shaped specimens were prepared from two types of sealants: (1) 10 discs were made using a fluoride-releasing sealant (Pro-Seal) and (2) 10 discs were made of a nonfluoride adhesive primer (control).
  74. 74. The results indicated that the fluoride-containing sealant released fluoride ions into the solution in sustained but significantly decreasing rates from a at the end of the 17th week. Furthermore, the Pro Seal discs had the ability to be recharged with fluoride ions introduced from a foaming solution of acidulated phosphate fluoride.
  75. 75. Newer self-adhesive cements have the potential to further simplify the bonding process, that is, by reducing the process of bonding orthodontic brackets to a one-step procedure. RelyX Unicem (3M ESPE, Seefeld, Germany), a self-adhesive universal cement, has proven to have many desirable properties, which have made it the adhesive material of choice in many dental procedures
  76. 76. Bishara et al (2006, Angle Orthod) did a study on whether a self-adhesive universal cement, RelyX Unicem (3M ESPE, Seefeld, Germany), can be used successfully to bond orthodontic brackets to enamel. Materials and Methods: Forty human molars were cleaned, mounted, and randomly divided into two groups: 20 orthodontic brackets were bonded to teeth using RelyX Unicem, and 20 brackets were bonded using the Transbond XT (3M Unitex, Monrovia, Calif) adhesive system.
  77. 77. Results: The mean bond strength of the brackets bonded using the RelyX Unicem was 3.7± 6 2.1 MPa and was significantly lower than the brackets bonded with the Transbond system ( 5.97 ± 4.2 MPa). Conclusions: The Shear bond strength of the self-adhesive universal cement needs to be increased for it to be successfully used for bonding orthodontic brackets.
  78. 78. Bioactive adhesive systems with antibacterial effects or intensive remineralizing ability are considered beneficial and capable of superior clinical performance as a direct strategy to eliminate the cause of caries. Clearfil Protect Bond ( Kuraray, Osaka, Japan) is a new fluoride releasing antibacterial bonding agent , combines the physical advantages of dental adhesive technology and antibacterial effect.
  79. 79. Clearfil Protect Bond contains 12methacryloyloxydodecyl-pyridinium bromide (MDPB) which is an antibacterial monomer. It copolymerizes with other monomers after curing and is covalently bonded to the polymer network. Does not leach from surface but acts as a contact inhibitor against the bacteria that attach to the surface.
  80. 80. Arhun N et al ( AJODO 2006) compared Clearfil Protect bond with Adper Prompt L Pop and Transbond Plus SEP to assess the bond strength. Adper Prompt L Pop – 9.6 ± 4.00 MPa Clearfil Protect bond – 13.8 ± 4.32MPa Transbond Plus SEP – 6.3 ± 2.86MPa
  81. 81. Similarly incorporation of 2.5% Cetylpyridinium chloride (antiplaque agent) in adhesives have been found to impart antimicrobial activity without altering diametral tensile strength. ( Tahani A. Al-Musallam et al AJODO 2006).
  82. 82. Effect of bleaching The recent popularity of tooth whitening or bleaching has had a significant impact on the practice of dentistry . In 1989, the first at-home “night-guard” bleaching system using carbamide peroxide was introduced by Haywood and Heymann. Since then, bleaching has became more accessible to dentists, patients, and the population at large, with bleaching materials and paraphernalia available in overthe-counter kits and special and regular toothpastes. Athome bleaching products, with a few exceptions, contain carbamide peroxide in varying concentrations, from 5% to 30%.
  83. 83. Bishara et al ( AJODO 2005) determined the effect of enamel bleaching on the shear bond strength of orthodontic brackets bonded with a composite adhesive. In the at-home bleaching group (n = 30), Opalescence bleaching agent (Ultradent, South Jordan, Utah), which contains 10% carbamide peroxide, was brushed onto the teeth daily for 14 days and left for 6 hours each day. Teeth in the in-office group (n = 30) were treated with Zoom! (Discus Dental, Culver City, Calif), which contains 25% hydrogen peroxide gel and then exposed to a light source for 20 minutes; these teeth were treated twice.
  84. 84. After bleaching, the specimens were randomly divided into equal subgroups and stored in artificial saliva at 37°C for 7 or 14 days before bonding. Shear bond strength testing was performed on all teeth.. Results: The mean shear bond strength for the control group was 5.6 ± 1.8 MPa. Means for the at-home groups were 5.2 ± 3.6 MPa and 7.2 ± 3.2 MPa for the 7- and 14day waiting periods, respectively. Means for the in-office groups were 5.1 ± 5.3 MPa and 6.6 ± 2.6 MPa for the 7and 14-day waiting periods, respectively. Conclusions: The results showed that in-office and athome bleaching did not affect the shear bond strength of orthodontic brackets to enamel.
  85. 85. Bulut et al ( EJO 2006) in their study concluded that brackets bonded immediately after bleaching revealed significantly lower tensile bond strengths. However antioxidant treatment immediately after bleaching was effective in reversing the tensile bond strength of brackets.
  86. 86. Bishara et al ( Angle 2005) did a study to determine whether the use of an iodine compound for disinfecting the waterlines in dental units has an effect on the shear bond strength of orthodontic brackets bonded to enamel. Forty molar teeth were divided randomly into two groups— group 1 control: twenty teeth were etched for 15 seconds with 35% phosphoric acid, washed with a distilled water spray for 10 seconds, stored in distilled water for 5 minutes, dried to a chalky white appearance, and the sealant applied to the etched surface;
  87. 87. group 2 experimental: twenty teeth were etched for 15 seconds with 35% phosphoric acid and washed for 10 seconds with water containing iodine. The teeth were stored for five minutes in the iodinated water, dried to a chalky white appearance, and the sealant applied to the etched surface as in the control group.
  88. 88. All teeth were debonded within 30 minutes from the initial time of bonding. Results indicated that there were no significant differences in the shear bond strengths of the teeth that were washed and immersed in the iodine solution and the control group in which distilled water was used. The mean shear bond strengths for the two groups were 6.5 ± 3.5 MPa and 4.7 ± 3.1 MPa respectively.
  89. 89. Dental flowable Composite Among the composite resins that could be used in orthodontics as bonding agents today, flowable composite merits great attention because of its clinical handling characteristics. Flowable composites show two desirable clinical handling characteristics that have not existed for composites until very recently: (1) nonstickiness, so that materials could be packed or condensed, and (2) fluid injectability.
  90. 90. Flowable composites were created by retaining the same small particle sizes of traditional hybrid composites but by reducing the filler content and allowing the increased resin to reduce the viscosity of the mixture. Ex - Denfil Flow (Vericom Laboratories Ltd, Anyang, Korea), Dyract Flow (DeTrey Dentsply, Konstanz, Germany) .
  91. 91. Simona Tecco et al ( Angle Orthod 2005) reported that the bond strength of Denfil Flow (34.8 MPa) showed no significant difference with the other control groups and was clinically acceptable. Denfil Flow and Dyract Flow tended to display cohesive failure within the adhesive. Denfil Flow can be used without liquid resin to reduce the bonding procedure time while maintaining acceptable bond strength
  92. 92. Light Curing Units In light-initiated bonding resins the curing process begins when a photoinitiator is activated. Most commonly camphoroquinone as the absorber, with the absorption maximum in the blue region of the visible light spectrum (480nm) . Until recently, the most common method of delivering blue light has been halogen-based light-curing units (e.g., Ortholux XT, 3M/Unitek) The halogen lights can cure orthodontic composite resins in 20 seconds and light-cured resin-modified glass ionomers in 40 seconds per bracket. This prolonged curing time is inconvenient for the clinician and the patient.
  93. 93. So Fast halogens (e.g., Optilux 501 or Demetron , California) have higher-output lamps or even using turbo tips that focus the light and concentrate it into a smaller area can reduce the curing time to half of the time needed with conventional halogen lights.
  94. 94. Light emitting diode (LED), argon laser, and plasma arc light-curing units have become commercially available in recent years. Although plasma and argon laser substantially decrease the time required to reach comparable bond strength with conventional halogen, these lamps are costly, but the expense can be partially cancelled by their longer lives.
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  96. 96. Argon Laser: They produce a highly concentrated beam of light that is collimated. One interesting potential of the argon laser is its ability to protect the lased enamel surface against decalcification. Recent studies have shown that argon laser irradiation significantly reduces enamel demineralization around orthodontic brackets. (Noel 2003, Anderson 2002) .
  97. 97. Argon laser is an excellent light source producing a peak wavelength of 488nm. Offers rapid curing, improved physical properties like hardness, tensile strength, shear bond strength, degree of polymerization. Ex- AccuCure 3000 argon laser (Laser Med, Utah)
  98. 98. Although the curing times could be reduced to 5 seconds for unfilled and 10 seconds, their use in orthodontics is not extensive, because of their high cost and poor portability.
  99. 99. Plasma arc light: This light was introduced in mid 1990s The lamp has a tungsten anode and a cathode in a quartz tube filled with xenon gas. When an electric current is passed through xenon, the gas becomes ionized and forms plasma made up of negatively and positively charged particles and generates an intense white light. This white light is filtered to blue wavelengths, with a narrow spectrum between 430 - 490nm.
  100. 100. The conventional halogen lamps emit light with an energy level of 300mW, the plasma arc lamp has a much higher peak energy level of 900 mW. The advantage of the high-intensity light is that the amount of light energy needed for polymerization of the composite resin can be delivered in a much shorter time.
  101. 101. About 3 to 5 seconds for metal brackets ( Sfondrini ME, Cacciafesta AJODO 2004) , less than 3 seconds for ceramic brackets (Klocke et al AJODO 2003) This yields similar bond failure rates as for brackets cured with a conventional halogen light for 20 sec.
  102. 102. Light Emitting Diodes: In 1995 Mills et al proposed solid-state LED technology for polymerization of light-initiated resins to overcome the shortcomings of conventional halogen lights. LED curing of 20 and 40 seconds yielded statistically similar results to curing of 40 seconds by conventional halogen light sources. New-generation LEDs with higher-intensity diodes may shorten the curing times further e.g., the new Ortholux LED by 3M/Unitek has recommended curing times of 10 sec for metal and 5 sec for ceramic brackets.
  103. 103. LED use junctions of doped semiconductors to generate the light. Wavelength of light emitted is about 470nm. Ex- Bluephase LED ( Ivoclar Vivadent Inc, NY), Ortholux LED ( 3M/Unitek ,CA), L.E. Demetron (Ormco/”A” company, CA), Tu Tu ( American Orthodontics, WI)
  104. 104. Compared to LED halogen units work at approximately 1% efficiency and are only 10% efficient in converting electrical current into light. LEDs have longer life spans of more than 10,000 hrs compared to 50 hrs for a halogen bulb. More consistent light output than Quartz halogen lights.
  105. 105. Advantages: Light-emitting diodes are small in size, are cordless, are quiet, generate minimal heat, and perform favorably compared with conventional and fast halogen sources.
  106. 106. Side effect – Harmful effect on retina. Blue light can form intracellular reactive oxygen species, thereby affecting cell functions. Wataha et al ( Dent Mater 2004) hypothesized that, if the biologic effects of blue light are redox mediated, antioxidants might be used to reduce the undesirable effects on tissues during clinical use,
  107. 107. Bikram S Thind & David R Stirrups ( EJO 2006) compared tungsten quartz halogen, plasma arc and LED light sources for polymerization of an orthodontic adhesive and concluded that polymerization as effective as conventional bulb light sources was obtained with short exposure times recommended for plasma arc or LED. Similar results have been got for Argon laser (Bryan S, Angle Orthod 2006) where it is concluded that exposure time beyond 5 sec and power setting beyond 150mW has no cumulative effect on the shear bond strength of stainless steel orthodontic brackets.
  108. 108. For effect of distance of light tip source on bond strength ,Kimberly Gronberg ( Angle 2006) found no effect in bond strength with the varying distance of light tip from 1-10mm for source to specimen distance for LED curing unit. Hinoura et al (1993) had earlier confirmed the same for lasers when distance increased to 1.5mm.
  109. 109. Bonding to Non conventional surfaces – Adhesion Boosters Bonding is more complicated in adult patients than in adolescents. Many adults have crownand-bridge restorations made of porcelain or precious metals, in addition to amalgam restorations of molars. Effective bonding of orthodontic brackets, buccal tubes, and retainer wires to artificial surfaces is now feasible, thanks to the introduction of a wide variety of new techniques and materials
  110. 110. Sandblaster Tin plating – Improves bonding to noble metals. Most commonly, the tin is electrolytically deposited with a unit such as the MicroTin ( 3M Unitek) or Kura Ace Mini (Morita USA Inc). An alternative method is to rub on a solution of gallium and tin (Adlloy) with a pure tin bar (Nippon-Bashi Tokuriki, Japan). Metal Surface is first sanblasted with 50µm aluminium oxide. Some organic tin compounds may be toxic
  111. 111. Adhesives that Bond Chemically to Metal – Two different types of adhesives, 4-META resins and 10-MDP bisGMA resins, have recently been developed to improve adhesion to metals. Super-Bond C&B ( Sun Medical Co. Ltd, Kyoto Japan) also marketed as C&B Metabond is activated by combining 4 META (4-methacryloxyethyl trimellitate anhydrid) and tributylborane monomers and then adding the polymer powder to the activated liquid .
  112. 112. The polarity of the 4-META molecule is believed to be the key to its bonding mechanism. The molecule orients toward the oxygen or hydroxyl groups in the metal layer and forms a hydrogen bond. Bond strengths of Super-Bond C&B to sandblasted and tin-plated gold and to sandblasted chromium-cobalt alloys are reportedly more than 30 MPa, exceeding those of conventional composites to acid-etched enamel.
  113. 113. A clinical drawback of Super-Bond C&B is its curing time of 10 minutes or more. Panavia EX ( J. Morita USA Inc, CA) a filled bisGMA resin, differs from other such adhesives in that the monomer contains a phosphate ester group (10-MDP, or 10-methacryloyloxydecyl dihydrogen phosphate). The bonding mechanism is not entirely understood, but it apparently involves both mechanical and chemical retention. MDP bonds chemically to oxides of nickel, chromium, and cobalt and to oxides of tin formed by tin plating.
  114. 114. Because Panavia requires an anaerobic environment for complete setting, the bond margins should be covered with a gel such as Oxyguard after removal of excess adhesive. In vitro studies show shear and tensile bond strengths in excess of 30 MPa when bonding to abrasive-sprayed base-metal alloys or tin-plated noble alloys (Imbery 1993, Omura 1984)
  115. 115. Intermediate Resins to Enhance Bond Strengths The most popular and complete intermediate resins available today are All-Bond 2 (Bisco Dental Products, IL) and Scotchbond MP (MultiPurpose) from 3M Unitek. All-Bond 2, a third-generation dentin bonding agent, contains a 10% phosphoric acid gel for dentin conditioning. One drop each of Primer A (NTG-GMA) and Primer B (BPDM) are mixed and applied to the enamel and dentin until the acetone solution evaporates
  116. 116. Deciduous teeth and fluorosced or hypocalcified enamel surfaces produce inconsistent results when conditioned in the conventional manner. New hydrophilic universal resins like Assure Universal bonding resin, Enhance Adhesion Booster ( Reliance Ortho) , Orthosolo Universal Bond Enhancer (Ormco, Calif) have been successful in achieving acceptable bond strengths with these atypical enamel surfaces.
  117. 117. After etching, multiple coats of the resin is applied and the last coat is lightly dried. Attachments can then be bonded with any chemical or light cured system.
  118. 118. Sumant Goel, Vishwanath Patil (JCO 2005) assessed Enhance LC, compared it with Light Bond (3M unitek) in vivo. Total 150 brackets ( 64 Begg, 86 MBT) were bonded. At 90 days monitoring period out of 150 brackets 13 brackets had bond failure : 2 in Enhance L.C. group and 11 in Light Bond only group. They concluded that application of Enhance LC appeared to reduce bond failure rate when compared to Light Bond alone. Also the adhesion booster did not increase the amount of adhesive remaining on enamel.
  119. 119. Bonding to amalgam Sandblasting the surface of restoration followed by use of adhesives containing 4 META, 10 MDP/Bis GMA and intermediate resins improves bonding to dental amalgam. Amalgambond (Super-Bond D liner) { Chamleon dental products, Inc, Kansas City, KS} is a 4-META resin that bonds to amalgam, as do Super-Bond C&B and C&B Metabond. Another 10-MDP monomer, besides Panavia EX, is Clearfil Porcelain Bond (J. Morita USA Inc, CA).
  120. 120. All-Bond 2 and Amalgambond can be used during initial placement, but Scotchbond MP should be used only on hardened, sandblasted amalgam.
  121. 121. Effects of surface treatment on orthodontic bonding to amalgam. Skilton JW, Tyas MJ, Woods MG. ( Aust Orthod J 2006) AIM: This study aimed to compare the shear bond strengths of metal brackets bonded to amalgam surfaces. METHODS: One hundred and fifty amalgam samples were fabricated and either polished, roughened with a diamond bur or sandblasted with 50 µm aluminium oxide. Following thermocycling the shear bond strengths were tested and compared with control samples bonded to etched enamel.
  122. 122. RESULTS: Concise resin composite, Metal Primer/Concise resin composite and All-Bond II/Concise resin composite bonded to sandblasted amalgam gave the highest mean shear strengths and were statistically similar to the etched enamel/Concise resin composite controls. CONCLUSION: One would expect sandblasted amalgam surfaces to be associated with higher shear bond strengths than diamond bur roughened or polished amalgam surfaces
  123. 123. Bonding to Gold Sandblasting, Electrolytic tin plating, or with gallium tin solution (Adloy), Superbond C & B, Panavia Ex and Panavia 21 have been reported to improve bonding to gold in laboratory settings.
  124. 124. Bonding to porcelain Conventional acid etching – ineffective in the preparation of porcelain surface. Approaches suggested to improve bond strength – mechanical, chemical or combination. Mechanical : Purpose is to remove the glaze and roughen the surface to provide sufficient mechanical retention for the adhesive. Can be achieved by microetching , coarse diamond stone, sandpaper disks.
  125. 125. Chemical : 1) HF acid – 9.6% HF acid in gel form applied for 2 min. 2) For areas of ceramic surface where isolation is difficult, a 1.23% APF gel can be used for ten min. Bond strength is not adequate. (Barbosa et al AJODO 1995) 3) Use of Silane coupling agent like Ormco porcelain primer, Porc Etch, Reliance Porcelain Conditioner, Scotchprime (3M).
  126. 126. ‫ץ‬methacryloxy-propyltrimethoxy silane is a coupling agent that provides reactive sites for inorganic and organic components. Hydrolysable group ( Silanol group) reacts with inorganic dental porcelain forming a siloxane (SiO-Si) bond. The methacrylate group (organofunctional group) reacts with resin forming covalent bonds with the polymer matrix of resin composite.
  127. 127. Silane are also known as adhesion promoters & function by adsorbing and altering the surface of porcelain. For optimal bonding of orthodontic brackets to porcelain surfaces, we recommend the following procedure: 1. Deglaze the porcelain surface by sandblasting with 50-micron aluminum oxide for two to four seconds. 2. Etch the porcelain with 9.6% HF acid gel for two minutes. 3. Apply two or three coats of a silane porcelain primer. 4. Bond the brackets with a highly filled bisGMA resin.
  128. 128. Raed Ajlouni, Samir E. Bishara ( Angle 2005) evaluated the effect of porcelain surface conditioning on bonding Orthodontic brackets. They concluded that most reliable procedure for orthodontic brackets to porcelain surfaces is through either microetching + HF acid or with the use of a silane coupler.
  129. 129. CONCLUSION The rapid pace of advancements in the field has altered the commercial life of materials; it is common for materials, introduced just a few years ago, to become obsolete, a possible derivative of the lack of strenuous quality control, and research and design deficiencies. Therefore, the clinician faces a handicap in the race with technology and the requirement to obtain familiarity with new materials and techniques, some of which might not have advantages over their predecessors.
  130. 130. This important implication brings a new challenge to graduate orthodontic education curricula: to build a solid background in materials science, facilitating informed decisions on novel materials and techniques, as opposed to selecting those based solely on advertisement brochures. Thus, evidence-based approaches must extend to orthodontic materials, with emphasis on the mechanical, physical, and biological properties, and the potential alterations induced by intraoral aging and their implications in mechanotherapy.
  131. 131. Projected short-term future developments in adhesives ( Eliades T AJODO 2006) ● Glass ionomer and compomer bonding will become more frequent. ● Two-phase chemically cured systems will be gradually abandoned. ● Fluoride-releasing adhesives with long-term release capacity, rather than the current nonstandardized adhesives, will be introduced.
  132. 132. ●Adhesives with antimicrobial properties or microbial repellent actions might be adopted. ● Antimicrobial varnishes might be introduced as the standard means of prophylaxis.
  133. 133. References Ashima Valiathan, Ashil A.M. Efficacy of moisture insensitive primer- An in vitro study. Kerala Dental Journal 2006 (In press) Amit Srivastava, Suresh Gorantla and Ashima Valiathan. In Vitro evaluation of indigenously developed cyanoacrylates as bonding agents in comparison to a conventional bonding agent Trends Biomater. Artif. Organs 2002: 16:25-27. James Sunny and Ashima Valiathan “A comparative In vitro study with newer generation Ethyl Cyanoacrylate (Smartbond) and a Composite-bonding agent” Trends Biomater.Artif.Organs. 2003;16(2):83-89
  134. 134. Koyal Sarin and Ashima Valiathan. Comparison of bond failure of Fuji Ortho LC Transbond XT – A clinical study. Journal of Pierre Fauchard Academy 2003; 17:17-25. A.Sivakumar, Ashima Valiathan : Ormocers in Orthodontics. Trends Biomat Artif Organs 2006,20;44. Ajlouni R, Bishara S, Soliman M Oonsombat C, Laffoon J ,John Warren The Use of Ormocer as an Alternative Material for Bonding Orthodontic Brackets. Angle Orthod 2004;75:106–108
  135. 135. Cal Neto J, Felipe Carvalhob; Rhita Cristina C. Almeida Miguel J. Evaluation of a New Self-etching Primer on Bracket Bond Strength In Vitro. Angle Orthodontist, Vol 76, No 3, 2006 Ortendahl T, Ortengren U. A New Orthodontic Bonding Adhesive. JCO 2000; 34(1): 50-54. Bishara S, Ajlouni R, Laffoon J. Effect of thermocycling on the shear bond strength of a cyanoacrylate orthodontic adhesive. Am J Orthod Dentofacial Orthop 2003; 123:21-4
  136. 136. Bishara SE, Von Wald L, Laffoon JF, Warren JJ . Effect of a self-etch primer/adhesive on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop. 2001;119:621–624 Arnold RW, Combe EC, Warford JH Jr. Bonding of stainless steel brackets to enamel with a new self-etching primer. Am J Orthod Dentofacial Orthop. 2002;122 (3):274–276. V.K Prashanth & Valiathan Ashima: In Vitro Evaluation of Cyanoacrylate (super glue) As a bonding agent in orthodontics.Trends Biomater.Artif.Organs 1998;12(1):19-25
  137. 137. D.N Kapoor,V.P Sharma, Pradeep Tandon, Kamlesh Pandey: Comparative evaluation of Tannic acid, Citric acid and phosphoric acid as etching agent for direct bonding. JIOS 2002 Vol35 , 2 page 54-62. Arhun N, Arman A, Sesen C, Karabulut E, Korkmaz Y, Gokalp S: Shear bond strength of orthodontic brackets with 3 self-etch adhesives.Am J Orthod Dentofacial Orthop. 2006 Apr;129(4):547-50. Vicente A, Bravo LA, Romero M, Ortiz AJ, Canteras M . Effects of 3 adhesion promoters on the shear bond strength of orthodontic brackets: an in-vitro study. Am J Orthod Dentofacial Orthop. 2006 Mar;129(3):390-5
  138. 138. William A Brantley, Theodore Eliades: Orthodontic Adhesive Resins - Orthodontic Materials . Thieme Stuttgart. NewYork 2001 page 201-20, 105-122, 253-271. Graber, Vanarsdall: Orthodontic current principles techniques, 4th edition,2005. St. Loius , Mosby. page 579-605. Sumant Goel, Vishwanath Patil : Effect of adhesion booster on bond failure. JCO 2005 39(6);360-362.
  139. 139. Simona Tecco; Tonino Traini; Sergio Caputi; Felice Festa; Valentina de Luca; Michele D'Attiliof : A New OneStep Dental Flowable Composite for Orthodontic Use: An In Vitro Bond Strength Study. Angle Orthodontist: Vol. 75, No. 4, pp. 672–677. Theodore Eliades : Orthodontic materials research and applications: Part 1. Current status and projected future developments in bonding and adhesives. AJODO 2006,130;445-451. Paul Gange : Bonding in today’s Orthodontic Practice. JCO 2006; 361-367.
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  141. 141. K House , A.J. Ireland, M. Sheriff : An investigation into use of single component self etching primer adhesive system for orthodontic bonding : a randomized controlled clinical trial. J.O. 2006 33;38-44. Raed Ajlouni, Samir E Bishara, Manal Soliman : The effect of porcelain surface conditioning on bonding orthodontic brackets. Angle Orthod 2005,75; 858-864. Bryan S.Elvebak, Barbara H Miller, Peter Buschang : Orthodontic bonding with varying curing time and light power using an Argon laser. Angle orthod 2006,76,(5); 837-844.
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  143. 143. Samir E. Bishara; Manal Soliman; Raed Ajlouni; John Laffoon; John J. Warrene: Waterline Disinfectant Effect on the Shear Bond Strength of Orthodontic Brackets. Angle Orthod 2005;75:1032–1035 Chitnis D, Dunn W, Gonzalez C. Comparison of in-vitro bond strengths between resin-modified glass ionomer, polyacid-modified composite resin, and giomer adhesive systems. Am J Orthod Dentofacial Orthop 2006;129: 11-16 Simona Tecco, Tonino Traini, Felice Festa, Michele D Attilio : A new one step dental flowable composite for orthodontic use : An in vitro bond strength study. Angle Orthod 2005;75;672-677.
  144. 144. Thank you For more details please visit