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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Bond strength of orthodontic brackets /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • 1. A COMPARATIVE EVALUATION OF SHEAR BOND STRENGTH OF ORTHODONTIC BRACKETS BONDED TO PORCELAIN FUSED METAL CROWNS TREATED WITH DIFFERENT SURFACE CONDITIONING TECHNIQUES – AN INVITRO STUDY INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
  • 2. CONTENTS        INTRODUCTION AIMS AND OBJECTIVES REVIEW OF LITERATURE MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION www.indiandentalacademy.com 2
  • 3. INTRODUCTION  The introduction of acid etch bonding technique by Buonocore in 1955, brought the concept of bonding various resins to enamel with applications in all fields of dentistry, including orthodontics.  With the development of reliable and reproducible bonding techniques to enamel surfaces, cemented bands were replaced by bonded brackets on incisor, cuspid and bicuspid teeth.  Newman 1965 was the first person who used epoxy resin for bonding stainless steel brackets to enamel www.indiandentalacademy.com 3
  • 4.  By the late 1970s bonding of orthodontic brackets had become an accepted clinical technique in routine fixed appliance treatment.  With the increased number of adults seeking orthodontic treatment, clinicians often have to bond orthodontic brackets to teeth that have different types of restorations, including amalgam, gold, composite and porcelain.  Various methods have been tried to improve the bonding of orthodontic brackets to porcelain surfaces by pretreating porcelain surface by mechanical or chemical means, or by a combination of both. www.indiandentalacademy.com 4 www.indiandentalacademy.com 4
  • 5. AIMS AND OBJECTIVES     (1) To compare the effect of different surface conditioning methods on bond strength, when orthodontic brackets are bonded to porcelain fused metal surfaces. (2) To compare the bond strength of brackets bonded to porcelain-fused-to-metal surface with bonding on natural teeth as control. (3) To assess the type of bond failures using scanning electron microscope (4) To discuss a more reliable and least variable surface conditioning method for bonding brackets to porcelain fused metal surfaces. www.indiandentalacademy.com 5
  • 6. Review of Literature   Ozcan M, Vallittu PK et al., (2004) evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. The specimens were randomly assigned to one of the following treatment conditions of the ceramic surface: (1) orthophosphoric acid, primer, bonding agent, (2) hydrofluoric acid gel, primer, bonding agent, (3) tribochemical silica coating (silicon dioxide 30µm) silane, (4) airborne particle abrasion (aluminum trioxide 30µm) www.indiandentalacademy.com 6 silane,
  • 7. & (5) airborne particle abrasion (aluminum trioxide, 30µm) silane, bonding agent  Results showed that brackets treated with silica coating with silanization had significantly greater bond strength values (13.6 MPa,) than brackets treated with orthophosphoric acid (8.5 MPa). www.indiandentalacademy.com 7
  • 8. MATERIALS AND METHODS  The present study was conducted in the Department of Orthodontics and Dentofacial Orthopedics, Sibar Institute of Dental Sciences, Takkellapdu, Guntur and Department of Organic Coatings & Polymers, Indian Institute of Chemical Technology, Habsiguda, Secunderabad  Sixty human maxillary premolar teeth extracted for therapeutic purposes from patients seeking orthodontic treatment in the Department of Orthodontics and Dentofacial Orthopedics, Sibar institute of dental sciences were collected & stored in normal saline after treating them with hydrogen peroxide for one week. 8 www.indiandentalacademy.com
  • 9. Inclusion & Exclusion Criteria for Teeth Selection:  Teeth with no signs of caries  Teeth free of restorations  Teeth with no cracks on the crown as a result of the pressure of the extraction forceps.  Teeth with no cement remnants as a result of previous orthodontic treatment.  Teeth with fluorosis, hypoplasia or abnormalities of crown morphology, which may have affected bracket bonding, were excluded. www.indiandentalacademy.com 9
  • 10. TEETH MOUNTED IN ACRYLIC BLOCKS GLASS IONOMER CEMENT USED TO CEMENT PFM'S ON EXTRACTED 10 www.indiandentalacademy.com MAXILLARY PREMOLARS
  • 11.  Fifty Porcelain Fused Metal crowns were fabricated over the extracted maxillary premolar teeth after crown preparation for the study purpose,  and ten extracted natural maxillary premolar teeth were acid etched in conventional manner using 37% phosphoric acid for 30 seconds  Composite bonding was done which acted as controls to compare the bond strength with Porcelain Fused Metal crowns. www.indiandentalacademy.com 11
  • 12. MATERIALS USED FOR THE STUDY DENTSPLY QHL75 LITE USA VISIBLE LIGHT CURING UNIT AND OTHER BONDING MATERIALS USED IN THE STUDY www.indiandentalacademy.com 12
  • 13. Methods  Bonding procedure: The teeth collected were grouped into six groups of ten each (Group I to Group VI)  And Following six protocols were executed for surface preparation.  Group I: Orthodontic brackets were bonded to enamel surfaces on ten teeth in Group I which acted as control group, teeth were acid etched with 37% phosphoric acid gel for 30 seconds, thoroughly washed, and air dried using 3-in-1syringe, followed by application of primer & bonding agent (Transbond XT 3M, light cured composite www.indiandentalacademy.com 13 resin).
  • 14.  Group II: etched with 37% phosphoric acid gel for 30 seconds, teeth were thoroughly washed, and air dried using 3-in-1syringe, followed by application of primer & bonding agent.  Group III: etched with 9% Hydrofluoric acid for 90 seconds  Group IV: were air abraded using 30 µm aluminum oxide particles from 10 mm distance with 250 Kpa pressure for 23 seconds using sand blaster machine, & etched with 9% Hydrofluoric acid for 90 seconds,. www.indiandentalacademy.com 14
  • 15. FINE DIAMOND BUR 30 µm BRASSELER LEMGO GERMANY SAND BLASTING WITH 30 µm ALUMINUM OXIDE PARTICLES www.indiandentalacademy.com 15
  • 16.  Group V: were air abraded using 30 µm aluminum oxide particles from 10 mm distance with 250 Kpa pressure for 23 seconds using sand blaster machine, followed by two coats of silane coupling agent application and air dried.  Group VI: Orthodontic brackets were bonded on ten Porcelain Fused Metal crowns belonging to Group VI, which were roughened using Fine diamond bur 30 μm.  Subsequent to bonding, the samples were stored in distilled water at physiological temperature (37ºC) for 1 day, and thermocycled 500 times between 5°C and 55°C with a dwelling time of 30 seconds using a computerised thermocycling device (Nova Inc., Konya, Turkey) prior to www.indiandentalacademy.com 16 shear bond strength testing. 
  • 17. SILANE APPLICATION FINE DIAMOND BUR ROUGHENING www.indiandentalacademy.com 17
  • 18. BRACKET PLACEMENT LIGHT CURING AFTER BRACKET PLACEMENT www.indiandentalacademy.com 18
  • 19.  Shear Bond Strength Testing In order to maintain a consistent debonding force in a controlled direction, teeth were mounted on to an acrylic jig. Facial surface of the porcelain crown was kept exactly parallel to the debonding force or perpendicular to the floor.  SBS was recorded with a universal testing machine (Autograph Model AGS 10 ANG, Shimadzu, Japan).  A crosshead speed of 1mm/min was used. www.indiandentalacademy.com 19
  • 20.  Debonded surfaces were observed under a scanning electron microscope for the types of failures after the debonding procedure.  Following debonding, the surfaces under the debonded brackets were coated with gold and palladium solution to prepare the specimens for viewing under scanning electron microscope model Hitachi- S520, Japan; Oxford Link ISIS300 UK at 500x and 1500x magnifications. www.indiandentalacademy.com 20
  • 21. RESULTS  The data was normally distributed and the results were tabulated and statistically analyzed using the S.P.S.S. 10 statistical analysis package software.  Shear bond strength in Megapascals (Mpa) and Standard Deviation (±SD) for shear bond strength of brackets bonded to porcelain fused metal surfaces were represented individually by tables for easy observation. www.indiandentalacademy.com 21
  • 22.  maximum mean shear bond strength of a sample  belonged to group V which was sandblasting with silane application 12.34 ± 0.95 Mpa and minimum belonged to group II which was acid etching with 37% phosphoric acid gel for 30 seconds 5.51 ± 0.88 MPa.  9% Hydrofluoric acid (group III) showed the second highest shear bond strength mean values 11.48 ± 0.98 MPa.  group IV which was Sandblasting and 9% Hydrofluoric acid showed a bond strength of 7.96 ± 1.07 MPa www.indiandentalacademy.com 22
  • 23. and group VI which was Fine diamond bur roughening with silane application showed mean values of 9.28 ± 1.11 MPa and group I which was control group (37% phosphoric acid) showed shear bond strength mean values of 11.03 ± 1.63 MPa Table I: Summary statistics according to groups  Groups Minimum Maximum Range Mean Std.Dev. SE Median Group I 9.01 13.61 4.60 11.03 1.63 0.51 10.84 Group II 3.82 7.01 3.19 5.51 0.88 0.28 5.52 Group III 10.11 13.54 3.43 11.48 0.98 0.31 11.29 Group IV 6.22 9.49 3.27 7.96 1.07 0.34 8.10 Group V 10.98 13.93 2.95 12.34 0.95 0.30 12.08 Group VI 7.27 11.21 1.11 0.35 9.16 www.indiandentalacademy.com 3.94 9.28 23
  • 24. 7.96 9.28 11.03 10.00 5.51 8.00 6.00 Group III Group IV 1.11 1.07 Group II 0.95 0.98 2.00 0.88 4.00 1.63 Mean shear bond strength 12.00 11.48 14.00 12.34 Figure: Comparison of mean shear bond strength in six groups 0.00 Group I www.indiandentalacademy.com Mean Group V Std.Dev. Group VI 24
  • 25.  Parametric tests for comparison of six groups by one way ANOVA test and Pair wise comparison of six groups by Newman-Keuls multiple comparison post hoc procedure were done.  Both the tests showed significant difference between and within the groups in shear bond strength and P value also was highly significant, i.e. ***p<0.001. www.indiandentalacademy.com 25
  • 26. Scanning Electron microscope Results  The SEM photomicrographs of all the six different surface preparations revealed different surface morphologies.  For the porcelain-fused-metal crowns treated with 30 μm Al2O3 and Fine diamond bur 30 μm, loss of the glazed surface and mild roughening were seen.  Uniform peeling or an erosive appearance with shallow penetration and undercuts was observed when compared with chemical etching. Hydrofluoric acid etching demonstrated mild roughening of the surface and orthophosphoric acid etching produced minimal change and did not appear to alter the glazed 26 www.indiandentalacademy.com porcelain surfaces. 
  • 27. CONTROL GROUP ORTHOPHOSPHORIC ACID AT 500 X (GROUP I) CONTROL GROUP ORTHOPHOSPHORIC ACID AT 1500 X(GROUP I) www.indiandentalacademy.com ORTHO PHOSPHORIC ACID AT 550 X ORTHO PHOSPHORIC ACID AT 1500X(GROUP II) (GROUP II)
  • 28. HYDROFLUORIC ACID AT 500 X (GROUP III) HYDROFLUORIC ACID AT 1500 X (GROUP III) www.indiandentalacademy.com SAND BLAST + HF ACID AT 500 X SAND BLAST + HF ACID AT 1500 X 28 (GROUP IV) (GROUP IV)
  • 29. SAND BLSATING + SILANE AT 500 X (GROUP V) SAND BLSATING + SILANE AT 1500 X (GROUP V) FINE DIAMOND BUR ROUGHENING www.indiandentalacademy.com 29 FINE DIAMOND BUR ROUGHENING AT AT 1500 X(GROUP VI) 500 X(GROUP VI)
  • 30. Discussion  Even though the clinical relevance of in-vitro studies is considered to be limited, the mean shear bond strengths of metal brackets to ceramic surfaces in this study generally exceeded acceptable limits (except for 37% phosphoric acid) and therefore can be considered sufficient for clinical situations.  The clinical forces may dislodge the brackets in single traumatic incident (comparable to the universal debonding machine in vitro) or as a result of repeated stresses.  To overcome the above said limitations thermocycling is required to test the bond strength of brackets to ceramics, as it induces artificial aging and stresses at the level of various thermal expansion coefficients of metal, resin and ceramic www.indiandentalacademy.com 30 materials.
  • 31. Group I - 37% Phosphoric acid  Orthodontic brackets bonded to enamel surfaces on ten natural teeth gave clinically acceptable and significant bond strength of 11.03 ± 1.63 MPa. Group II - 37% Phosphoric acid  Porcelain surface preparation using 37 % Phosphoric acid gave significantly low SBS of 5.51 ± 0.88 MPa. These results were not in acceptable range for the orthodontic bonding. Group III - 37% Hydrofluoric acid  Preparation with Hydrofluoric acid (HFA) produced significantly high bond strength of 11.48 ± 0.98 MPa, www.indiandentalacademy.com 31 which was similar to the reports of previous studies.
  • 32.  Surface conditioning with HFA successfully increased the adhesion of the composite resin to the porcelain surfaces by producing physical or topographical changes in the porcelain surface.  This was an expected result as HFA facilitates micromechanical retention between porcelain and composite resin. When the two acids, HFA and Phosphoric acid were compared, higher bond values were obtained in the HF acid treated group.  - However, HFA should be used with great care as it is capable of causing severe trauma to soft tissues and tooth www.indiandentalacademy.com 32 substance (Hayakawa et al., 1992).
  • 33. Group IV – Sand blasting + Hydrofluoric acid  In the mechanical preparation we used sandblasting in combination with 9% hydrofluoric acid etching and bracket bonding with composite material.  Surface preparation with 30 µm Al2O3 particles produced a uniform peeling appearance of the porcelain with deeper penetration and more undercuts compared to roughening; which increased potential mechanical retention.  Hydrofluoric acid further acted by dissolving the crystalline and glassy phase of the ceramic(But this combination also seemed to cause irreversible alteration to the porcelain surface) www.indiandentalacademy.com 33
  • 34. Group V – Sand blasting + Silane  Gave the maximum SBS value in this study, which is 12.34 ± 0.95 MPa.  These results were comparable to the previous studies done by Kocadereli et al. and Schmage et al. In contrast, Zachrisson reported earlier to these studies that silane application to sandblasted porcelain did not provide clinically acceptable bond strengths and suggested abandoning this technique. www.indiandentalacademy.com 34
  • 35.  In a study carried out by Tamer Türk et al. stated that samples coated with silane, but not exposed to chemical or mechanical roughening, were considered as the control group but demonstrated bond failures during thermocycling.  Barbosa et al. (1995) reported the premature loss of brackets bonded to glazed ceramic surfaces coated with silane after 7 days of water immersion.  They explained that this premature loss was due to the high solubility of silane in water. www.indiandentalacademy.com 35
  • 36. Group VI – Fine Diamond Bur roughening + Silane - Gave an SBS of 9.28 ± 1.11 MPa.  Barbosa et al. (1995)In their study stated that roughening with coarse diamond burs resulted in higher SBS when compared with other groups, i.e. glazed and deglazed surfaces with sandpaper disks.  Silane presents a chemical link between the dental ceramic and the composite resin, and the organic portion of the molecule enhances the wettability of the ceramic surface, thereby displaying a closer micromechanical bond (Lu et al., 1992).  However, in order to obtain a viable bond between the orthodontic bracket and the ceramic surface, mechanical or chemical roughening is inevitable (Wood et al., 1986; Kao et al. , 1988 www.indiandentalacademy.com , 1995 ; Gillis and ; Barbosa et al. 36 Redlich,1998 ; Huang and Kao, 2001
  • 37. Shortcomings of the study  Although the results obtained in this study can be helpful for selection of the most effective method for bonding orthodontic brackets to PFM’s clinically, it is important to be updated with the continuous development of newer ceramic systems used these days.  This study was carried out only on feldspathic ceramics with porcelain fused metal surfaces, and didn’t consider all ceramic crowns, other ceramic types like Zirconia based ceramics, leucite or lithium disilicate, composite restoration surfaces. www.indiandentalacademy.com 37
  • 38.     Conclusion Sand blasting followed by application of Silane (group V) produced maximum bond strength comparable or even better than the control group followed by groups III and VI. 37% Ortho Phosphoric acid (group II) produced least SBS and hence not suitable for bonding Othodontic brackets in a clinical scenario. Even though groups III and VI produced clinically acceptable SBS values, because of their technique sensitivity and side effects, they have to be used with great care and caution. The best porcelain surface conditioning method recommended clinically for bonding Orthodontic brackets to porcelain fused metal crowns was sand blasting followed by the application of Silane coupling agent. 38 www.indiandentalacademy.com
  • 39. www.indiandentalacademy.com 39