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Materials used in Orthodontics _ Dr. Nabil Al-Zubair


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Materials used in Orthodontics _ Dr. Nabil Al-Zubair

  1. 1. Materials used in Orthodontics Dr. Nabil Al-Zubair
  2. 2. THE BEGINNINGS Teeth were regarded by the ANCIENTS as: (Very Precious) to the extent that: ‘‘. . . special Penalties [were exacted] for knocking out the teeth of an individual, either freeman or slave.’’ ‫القدماء‬ ‫العقوبات‬
  3. 3. Greece were: burying their dead with appliances that were used to maintain space and prevent collapse of the dentition during life As early as 400 BC, Hippocrates : referenced in his writings the correction of tooth irregularities ‫دفن‬‫موتاهم‬
  4. 4. In a Roman tomb in Egypt, finds: a number of teeth bound with a gold wire at the time of Christ, Aurelius Cornelius Celsus first records: the treatment of teeth by finger pressure ‫في‬‫رومانية‬ ‫مقبرة‬
  5. 5. - inherent malocclusions and the use of corrective forces are recognized, - the first orthodontic material is documented—a gold ligature wire - the virtue of maintaining space is appreciated, and Thus,
  6. 6. -‫نجح‬‫تقويم‬ ‫وفى‬ ‫الفكين‬ ‫تشوهات‬ ‫عالج‬ ‫في‬ ‫الزهراوى‬ ‫ابتكرها‬ ‫جراحية‬ ‫آالت‬ ‫باستخدام‬ ‫األسنان‬‫خصيصا‬ -‫الزهراوى‬‫الذهبية‬ ‫األسنان‬ ‫جسور‬ ‫استخدم‬ ‫من‬ ‫أول‬ ‫والفضية‬‫ضغط‬ ‫وأدوات‬‫األسنان‬ -‫كما‬ ‫لقلعها‬ ‫الكالليب‬ ‫وأستعمل‬ ‫األسنان‬ ‫بطب‬ ‫أهتم‬‫أستعمل‬ ‫منها‬ ‫الزائد‬ ‫لنشر‬ ‫المبارد‬ ‫القاسم‬ ‫أبو‬‫الزهراوي‬403‫هـ‬/1013‫م‬
  7. 7. In 1887, Edward Angle used: - Nickelsilver alloys in his orthodontic accessories. - Subsequently he replaced them with copper, nickel and silver- free zinc alloys. - Eventually, gold alloys became his favorite choice
  8. 8. CLASSIFICATION OF ORTHODONTIC MATERIALS I Classification according to the structure of orthodontic materials II Classification according to usage
  9. 9. I Classification according to the STRUCTURE of orthodontic materials Wire alloys Orthodontic band Orthodontic brackets Ceramic brackets Filler particles in cements Polycarbonates for brackets Adhesive resins for bonding Polyurethane elastomers for tooth movement Ceramic materials Polymeric materialsMetallic materials
  10. 10. II Classification according to usage_1 - Gold alloys - Stainless steel - Co-Cr-Ni (elgiloy) - B-titanium - Nickel –titanium - Stainless steel - Titanium - Plastics - Polycarbonates and ceramics Wire Brackets Conventional ligatures fluoride releasing elastomerics Elastomeric ligature and chains Ii- Non-metallic with Optiflex i- Metallic wires
  11. 11. i- Metallic wires
  12. 12. OPTIFLEX ARCHWIRE  Optiflex is a non metallic orthodontic arch wire  It was designed by DR. TALASS  In the year 1992 and manufactured by Ormco. Ii- Non-metallic with Optiflex  It has got unique mechanical properties with a highly aesthetic appearance  Made of clear optical fiber
  13. 13. OPTIFLEX ARCHWIRE  It comprises of 3 layers. A) A silicon dioxide core that provides the FORCE for moving tooth. B) A silicon resin middle layer that PROTECTS the core form moisture and adds strength. C) A strain resistant nylon outer layer that PREVENTS damage to the wire and further increases strength
  14. 14. OPTIFLEX ARCHWIRE 1) It the most aesthetic orthodontic archwire 2) It is completely stain resistant, and will not stain or loose its clear look even after several weeks in mouth 3) Its effective in moving teeth using light continuous force
  15. 15. OPTIFLEX ARCHWIRE 4) it is Very flexible , 5) has an extremely wide range of actions, 6) when indicated it can be tied with electrometric ligatures to severely malaligned teeth without fear of fracturing the arch wire. 7) Due to superior properties optiflex can be used with any bracket system
  16. 16. II Classification according to usage_2 - Chemically cured / - Light cured - Thermo-cured Orthodontic adhesive composite resin - Zinc phosphate - Zinc polycarbocxylate - Glass ionomers - Alginate impression martial - Brass - Lock pins - Mini-implant MiscellaneousCements
  17. 17. Ideal requirements of these cements are • Adequate working and setting time • High strength • Resistance to dissolution • Clinically acceptable bond strength • Anti carcinogenic property Zinc phosphate cement Zinc polycarboxylate cement Glass ionomer The cements that are widely used for cementation orthodontics bands are: Cements used in Orthodontics Orthodontic application of cements are limited to luting of bands and appliances
  18. 18. - Alginate is the most extensively used impression material today - Irreversible hydrocolloids: used for recording minimum detail; e.g. study models ALGINATE
  19. 19. 1. Easy to manipulate 2. Relatively inexpensive 3. Comfortable for the patient 4. They are hydrophilic 5. Have pleasant taste 6. Long shelf-life 1. tear easily 2. Models should be poured immediately 3. They have limited detail reproduction 4. Can retard gypsum setting DISADVANTAGESADVANTAGES ALGINATE
  20. 20. Removable vs. Fixed Two Types of Orthodontic Appliances:
  21. 21. • Bands • Brackets • Wires • Accessory appliances Fixed appliances
  22. 22. • 24K plating gold bracket Brackets • Metal bracket
  23. 23. • Clear Bracket Brackets
  24. 24. Brackets Plastic brackets • Staining and discoloration • Poor dimensional stability • Larger friction
  25. 25. Ceramic brackets Brackets – Durable, resist staining – Can be custom-molded – Dimensionally stable Advantages over plastic brackets ‫متين‬
  26. 26. Ceramic brackets Brackets – Bulkier than metal bracket – Fractures of brackets – Friction is bigger than that in metal bracket – Wear on teeth contacting a bracket – Enamel damage on debonding Disadvantages over metal brackets
  27. 27. • Metal-reinforced ceramic bracket Brackets
  28. 28. Self ligating bracket Brackets
  29. 29. The negative space between the buccal surface of the maxillary first premolar and the inner point at which the lips join when the patient smiles. Buccal Corridor Width ‫عرض‬‫الشدقى‬ ‫الممر‬
  30. 30. • Lingual brackets Invisible orthodontics? • Invisalign
  31. 31. • Lingual bracketsInvisible orthodontics?
  32. 32. Step 1: Visit your orthodontist or dentist Step 2: Invisalign® makes your aligners Step 3: You receive your aligners in a few weeks. Step 4: You wear your aligners. Step 5: You've finished treatment! Invisalign
  33. 33. Invisalign
  34. 34.  Mild-moderate crowding with IPR or expansion  Posterior dental expansion  Close mild-moderate spacing Clear aligner therapy (CAT) applicability CAT performs well:  Absolute intrusion (1 or 2 teeth only)  Lower incisor extraction for severe crowding  Tip molar distally
  35. 35. 0.1-0.5 mm in thickness
  36. 36. •Dental expansion for blocked-out teeth •Extrusion of incisors* •High canines •Severe rotations (particularly of round teeth) •Leveling by relative intrusion •Molar uprighting (any teeth with large undercuts) •Translation of molars* •Closure of premolar extraction spaces* CAT does not perform well: Clear aligner therapy (CAT) applicability
  37. 37. • patients treated with Invisalign RELAPSED more than those treated with conventional fixed appliances. Invisalign vs. braces
  38. 38. • Type: – NiTi wire (Nickel-Titanium wire) – TMA wires (Titanium- Molybdenum-Alloy) – Stainless steel wire Wires • Shape – Round wire – Rectangular wire
  39. 39. Properties of arch wires – related to force levels, rigidity, formability, etc.
  40. 40. • Maintains force over a range of tooth movement General Characteristics of Orthodontic Forces • Optimal: light, continuous – Ideal Material • Maintains elasticity
  41. 41. 1.Cantilever Beam:- is one whose: - one end is fixed and the - other end carries a point or concentrated load. 2. Simply Supported Beam:- is one which: - carries two reaction forces at its two ends & - a point load at its mid-point. Types of Beams
  42. 42. Physical Properties of Orthodontic Wires
  43. 43. ‫عند‬،، ‫إنفعال‬ ‫عنه‬ ‫ينتج‬ ‫إجهاد‬ ‫تحت‬ ‫تقع‬ ‫المرنة‬ ‫المواد‬ ‫على‬ ‫معينة‬ ‫بقوى‬ ‫التأثير‬ ‫هذا‬‫الشكل‬ ‫فى‬ ‫تغير‬ ‫إلى‬ ‫اإلنفعال‬ ‫هذا‬ ‫يؤدي‬ ‫قد‬ ‫وكذلك‬ ‫بالنقصان‬ ‫أو‬ ‫وحجمها‬ ‫طولها‬ ‫فى‬ ‫بالزيادة‬ ‫إما‬ ‫يكون‬ ‫اإلنفعال‬. ‫اإلنفعال‬ ‫تعريف‬: ‫هو‬‫المؤثرة‬ ‫للقوة‬ ‫المادة‬ ‫إستجابة‬ ‫أو‬ ‫الطول‬ ‫فى‬ ً‫ا‬‫تغير‬ ‫يكون‬ ‫فقد‬ ‫عليها‬ ‫الشكل‬ ‫أو‬ ‫الحجم‬. ‫اإلنفعال‬ ‫أن‬ ‫القول‬ ‫يمكن‬ ‫آخر‬ ‫بمعنى‬ ‫إلى‬ ‫بالنسبة‬ ‫الطول‬ ‫فى‬ ‫التغير‬ ‫هو‬ ‫الحجم‬ ‫فى‬ ‫التغير‬ ‫أو‬ ‫األصلى‬ ‫الطول‬ ‫األصلى‬ ‫للحجم‬ ‫بالنسبة‬. ‫اإلجهاد‬‫واإلنفعال‬Stress and Strain: ‫اإلجهاد‬ ‫تعريف‬: ‫هو‬‫المؤثرة‬ ‫القوة‬ ‫وحدة‬ ‫على‬ ‫عموديا‬ ‫المساحة‬ σ = F/A Stress Strain Stress Strain
  44. 44. – Defined by stress-strain response to external load Materials & Production of Orthodontic Force • Strain= internal distortion produced by the load - deflection/unit length • Stress= internal distribution of the load - force/unit area • Elastic behavior
  45. 45. Yield strength Ultimate tensile strength Plastic Region Stress Strain Failure point Elastic Region
  46. 46. • Measure deflection = strain - examples: • Bending • Twisting • Change in length Orthodontic Model: Beam Metal Spanning • Force applied to a beam = stress
  47. 47. – Stiffness – Range, springback – Strength - Resilience, formability Beam Properties in Orthodontics • Defined in force deflection or stress-strain diagrams • Useful properties:
  48. 48. 3. Ultimate tensile (yield) strength 1. Proportional limit 2. Yield strength • Maximum load wire can sustain Bending Properties of an Orthodontic Wire • Point at which permanent deformation is first observed • Similar to “elastic limit” • Point at which 0.1% deformation occurs Defined by 3 points Stress Strain Proportional limit Yield strength Ultimate tensile strength 0.1%
  49. 49. – Young’s modulus Stiffness of an Orthodontic Wire Modulus of elasticity (E) – Slope of load deflection curve – Stiffness α E – Springiness α 1/E Resistance of a body to elastic deformation caused by an applied force - Describes the stiffness or springiness of a wire ‫المرونة‬ ‫معامل‬ ‫الجسم‬ ‫مقاومة‬‫الناجم‬ ‫للتشوه‬‫المستخدمة‬ ‫القوة‬ ‫عن‬
  50. 50. Low stiffness leads to: - an ability to apply lower forces - a more constant force to be delivered over time and - greater ease and accuracy in applying a given force. STIFFNESS or LOAD DEFLECTION RATE more Horizontal, and vice versa As the springiness (elasticity) of a wire increases, The slope of the stress -strain curve becomes
  51. 51. Spring back is also referred to as maximum elastic deflection or working range Decreasing the number of arch wire changes Higher springback values provide: The ability to apply large activations with a resultant increase in working time of the appliance SPRINGBACK thus
  52. 52. • Related to elastic portion of force deflection curve (slope) Stiffness versus Springiness Springiness= 1/stiffness• Reciprocal relationship – More horizontal= greater springiness – More vertical= stiffer
  53. 53. • Range Distance wire will bend elastically before permanent deformation Range versus Springback • Springback – Found after wire deflected beyond its yield point – Clinically useful • Wires often deflected past yield point ‫النطاق‬ ‫المسافة‬‫شكله‬ ‫فيها‬ ‫الى‬ ‫ويعود‬ ‫السلك‬ ‫ثني‬ ‫يتم‬ ‫التي‬ ‫قبل‬ ‫السابق‬‫دائم‬ ‫تشوه‬ ‫حدوث‬
  54. 54. • Strength = stiffness x range Relationship of Strength, Stiffness & Range
  55. 55. • Resilience – Area under stress-strain curve to proportional limit – Represents Energy Storage Capacity Resilience, Formability High formability provides: the ability to bend a wire into desired configurations such as loops, coils .etc. without fracturing the wire • Formability – The amount of permanent deformation a wire can withstand before breaking
  56. 56. • Deflection properties: – High strength – Low stiffness (usually) – High range – High formability Ideal Orthodontic Wire Material • Strength = stiffness x range • Other properties: – Weldable, solderable – Reasonable cost • No one wire meets all criteria!
  57. 57. Wire Materials
  58. 58. – Before 1950’s: gold alloys, corrosion resistant Wire Materials – 1970’s applied to orthodontics – Demonstrates exceptional springiness • Two special properties: Shape Memory, Superelasticity – Improved strength, springiness – Corrosion resistant: chromium • Typical: 18% chromium, 8% nickel Nickel-titanium (NiTi) alloys Precious metal alloys Stainless steel, cobalt-chromium (elgiloy®) alloys
  59. 59. Stainless steel alloy:
  60. 60. • In the past: • the arch wire & springs were constructed from GOLD or platinized gold, • But because these materials are very expensive; therefore the stainless steel alloy is used as an alternative alloy in orthodontic appliance. • Alloys: are mixtures of two or more metallic elements.
  61. 61. First and foremost alloys used in orthodontics in forms of wires, bands and brackets History – The advent of stainless steel - Stainless steel was introduced into orthodontic practice in 1929, when Renfert, a North American company, began selling wires made from these alloys, which were produced by a German company named Krupp Stainless Steel Alloys
  62. 62. Properties of Stainless Steel  Passivation  Sensitization  Stabilization • Composition: Stainless steel alloy Fe 71% Ni 8% Cr 18% C <0.2% Resist Tarnish and corrosion The loss of chromium from the alloy that occurs with heat Stabilized against the formation of chromium carbide Stainless Steel Wires Rectangular Round gauges from 0.15mm – 1 mm
  63. 63. Properties of Stainless Steel Passivation known as a passavating film They Resist Tarnish and corrosion because of: - The presence of chromium: If the oxide layer is disturbed by mechanical or chemical actions the wire can corrode Chromium + Oxygen = chromic oxide forms on the surface of the wire and prevents corrosion A thin, transparent layer
  64. 64. (-) The nicks and rough places left on a wire after it is bent with pliers may produce localized electric couples that allow corrosion - Acetic and lactic acids do not attack the passavating film - can be used in the cleaning of Hawley retainers containing stainless steel wires (-) If bits of carbon steel are incorporated into the surface of a stainless steel wire that comes into contact with carbon steel pliers, cutters, or burs, starts the process of corrosion (-) Chlorine cleansers attack 18 - 8 steels and cause corrosion
  65. 65. The loss of chromium from the alloy that occurs with heat is known as sensitization Sensitization Cr + C Chromium carbide 400 - 900 ° C Reduction in corrosion resistance Chromium carbide most rapidly forms at 650 ° C and begins to decompose above that temperature Loss of passivating effect Weakening of the metal
  66. 66. Stabilization Stainless steel can be stabilized against the formation of chromium carbide by adding an element such as titanium that precipitates as carbide in preference to chromium. Very few of the stainless steel wires used by orthodontists are stabilized.
  67. 67. 40% Co 20% Cr 15% Ni 15.8% Fe 7% Mo 2% Mn 0.15% C 0.04% Be Composition COBALT – CHROMIUM – NICKLE (or) ELGILOY Cobalt – chromium – nickel orthodontic wire (elgiloy) was developed during 1950’s by elgiloy corporation
  68. 68. - Elgiloy is available in four different temper (levels of resistance) & color coded : - Blue (soft) - Yellow (ductible) - Green (semi-resilient) - Red (resilient) Properties - Elgiloy has excellent Resistance to Tarnish and corrosion similar to stainless steel because of passivating effect - It can be subjected to soldering and welding procedure
  69. 69. However, because of their - high values of modulus of elasticity, wires manufactured from these alloys have - the highest force delivery, along with lower elastic ranges and springback. The stainless and Elgiloy blue wires are: - the least expensive, and have excellent formability and good joining characteristics
  70. 70. • Introduced 1980’s – Demonstrate superelasticity • Large reversible strains – Over wide range of deflection, force nearly constant – Very desirable characteristic Austenitic NiTi (A-NiTi)
  71. 71. • Good choice: – Initial stages of Tx – Leveling and aligning (good stiffness, range) • Poor choice: – Finishing (poor formability) Uses of Ni-Ti Arch wires
  72. 72. Wire alloy Composition Modulus of Elasticity Yield Strength (MPa) Springback Austenitic Stainless Steel 7-12% Cr 8-12% Ni 0.15% C Balance Fe 160-180 1100-1500 0.006-0.0094 (AR) 0.0065- 0.0099 (HT) Cobalt - Chromium - Nickel, 40% Co, 20% Cr, 15% Ni, 15.8% Fe, 7% Mo, 2% Mn, 0.15% C, 0.04% Be 160-190 830-1000 0.0045-0.0065 (AR) 0.0054- 0.0074 (HT) Beta - Titanium 77.8% Ti, 11.3% Mo, 6.6% Zr, 4.3% Sn 62-69 690-970 0.0094-0.011 Nickel - Titanium 55% Ni, 45% Ti 34 210-410 0.0058-0.016 Physical Properties of Orthodontic Wires
  73. 73. • Wire properties – Significantly affected by wire (beam) cross section and length Elastic Properties: Effects of Size and Shape • Magnitude of change varies with wire material
  74. 74. • Strength – Changes to third power • Ratio between larger to smaller beam • E.g., double diameter: deliver 8x strength • Springiness – Changes to fourth power • Ratio between smaller to larger beam • E.g., double diameter: wire 1/16 as springy Effects of Diameter: Cantilever Strength d 2d = 8 (2d/d)³ Springiness d 2d = 1/16 (d/2d)⁴ Rang d 2d 1/2 (d/2d)
  75. 75. • Strength = stiffness x range • Strength = 1/(1/16)x 0.5 Springiness= 1/stiffness 1/16= 1/stiffness Stiffness = 1/(1/16) • Strength = 16 x 0.5 = 8 Distance wire will bend elastically before permanent deformation Effects of Diameter: Cantilever
  76. 76. • Range – E.g., double diameter: half the range Effects of Diameter: Cantilever
  77. 77. • Strength – Decreases proportionately – E.g., double length: half the strength • Springiness – Increase by cube of ratio – E.g., double length: 8x the springiness Effects of Length: Cantilever Strength 1/2 1/4 1 2 Springiness 1 8 1 1/4 Rang 1 4 1 1/2 • Range – Increases by square of ratio – E.g., double length: 4x the range
  78. 78. – Light wire: • Low strength, low force, high range • Example: removable appliance – Finger spring – High strength needed to avoid deformation – Force can be reduced by increasing wire length • Add helix Spring Design • Requires appropriate balance: – Heavy wire: • High strength, high force, low range
  79. 79. The most important allergies in relation to orthodontics treatment are those associated with exposure to: - Latex - Nickel containing alloys - Acrylic - Impression materials Hypersensitivity reaction: either - Type I (immediate)- present as localized urticaria or anaphylaxis - Type IV (delayed) – results in localized allergic contact dermatitis (those related to nickle) Allergy to Orthodontic Materials
  80. 80. - Staff should be aware of emergency protocol for dealing with anaphylactic reaction Management of latex allergy - The use of elastomeric ties could be avoided with the use of self-ligating brackets - The use of latex products should be avoided
  81. 81. Management of latex allergy - Inter-maxillary elastics replaced with latex-free elastics - Space closure should be undertaken with nickel-titanium coils
  82. 82. Nickel Allergy - Typically, Type IV hypersensitivity reactions present on the skin as contact dermatitis; - however, intra-oral manifestation are less common - there appears to be a higher threshold nickel concentration intra-orally to induce a reaction - Nickel-titanium archwires, stainless steel products - (archwires, brackets, headgears) – all containing nickel - Affecting over 10% of females
  83. 83. Management of Nickel Allergy - Brackets- Ceramic, gold, titanium or polycarbonate - Use of fiber-reinforced composite wires - Use of clear plastic aligners Use of nickel free products:
  84. 84. Dr. NabiL Al-Zubair Congratulations Graduation