Ortho wires /certified fixed orthodontic courses by Indian dental academy


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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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Ortho wires /certified fixed orthodontic courses by Indian dental academy

  1. 1. ORTHODONTIC WIRES INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. INTRODUCTION  Orthodontic wires, which generate the biomechanical forces communicated through brackets for tooth movement, are central to the practice of the profession.  Ideally arch wires are designed to move the teeth with light continuous force. It is important that these forces do not decrease rapidly. Also an ideal arch wire should have certain properties like esthetics, biohostability, formability, resilience etc. but the search of a arch wire which meets all this requirements and is perfect is still not over and the search continuous…..  For not abusing the material and for designing the appliance to its full potential the proper understanding of its physical and mechanical properties is required. The aim of this seminar is to provide this basic knowledge of orthodontic wire characteristics. www.indiandentalacademy.com
  4. 4.  Evans (BJO 1990) divided the phases of archwire development into five phases on the basis of (a) Method of force delivery, (b) Force/Deflection characteristics and (c) Material. PHASE I  Method of force delivery: Variation in archwire dimension  Force/Deflection characteristics: Linear force/deflection ratio  Material: Stainless steel, Gold EVOLUTION OF ORTHODONTIC WIRES (PHASES OFARCHWIRE DEVELOPMENT) www.indiandentalacademy.com
  5. 5. PHASE II  Method of force delivery: Variation in archwire material but same dimension  Force/Deflection characteristics: Linear force/deflection characteristics  Material: Beta Titanium, Nickel titanium, Stainless steel, Cobalt chromium PHASE III  Method of force delivery: Variation in archwire diameter  Force/Deflection characteristics: Non- linear force deflection characteristic due to stress induced structural change  Material: Superelastic Nickel Titaniumwww.indiandentalacademy.com
  6. 6. PHASE IV  Method of force delivery: Variation in structural composition of archwire material  Force/Deflection characteristics: Non-linear force/deflection characteristic dictated by thermally induced structural change  Material: Thermally activated Nickel titanium PHASE V  Method of force delivery: Variation in archwire composition/structure  Force/Deflection characteristics: Non-linear force/deflection characteristics dictated by different thermally induced structural changes in the sections of the archwire  Material: Graded, thermally activated nickel titanium www.indiandentalacademy.com
  7. 7. THE EARLY ARCHWIRES  The scarcity of adequate dental materials at the end of the nineteenth century launched E.H. Angle on his quest for new sources  Angle listed only a few materials as appropriate work. These included strips or wires of precious metal, wood, rubber, vulcanite, piano wire, and silk thread.  Before Angle began his search for new materials, orthodontists made attachments from noble metals and their alloys Gold (at least 75%, to avoid discoloration), platinum, iridium, and silver alloys were esthetically pleasing and corrosion resistant, but they lacked flexibility and tensile www.indiandentalacademy.com
  8. 8.  In 1887 Angle tried replacing noble metals with German silver, a brass. His contemporary, J.N. Farrar, condemned the use of the new alloy, showing that it discolored in the mouth, Farrar‟s opinion was shared by many  To obtain the desired properties, Angle acted, as stated in 1888, “by varying the proportion of Cu, Ni and Zn” around the average composition of the Neusilber brass (German silver, 65%Cu, 14%Ni,21%Zn), as well as by applying cold working operations at various degrees of plastic deformation.  Besides its “unsightliness” and obvious lack of reproducibility (variations in composition and processing), the mechanical and chemical properties of German silver were well below modern demands. However, because it could be readily soldered, this brass allowed Angle to design more complex appliances. www.indiandentalacademy.com
  9. 9.  The material that was to truly displace noble metals was stainless steel. As with German silver, it had its opponents. As late as 1934 Emil Herbst held that gold was stronger than stainless steel without exfoliation. If forced to choose, he even preferred German silver to stainless steel. Eventually, better manufacturing procedures and quality control made stainless steel the material of choice. www.indiandentalacademy.com
  10. 10. DESIRABLE PROPERTIES OF ORTHODONTIC WIRES:  The ideal properties for an orthodontic purpose according to Proffit5 are: 1. High strength. 2. Low stiffness. 3. High range. 4. High formability.  Kusy11 (1997) in a review of contemporary arch wires listed a few ideal characteristics desired in an archwire as follows: 1. Esthetics 2. Stiffness 3. Strength 4. Range 5. Springback 6. Formability 7. Resiliency (Resilience) 8. Coefficient of friction 9. Biohostability 10. Biocompatibility 11. Weldability www.indiandentalacademy.com
  11. 11. PROPERTIES OF ORTHODONTIC ARCH WIRES  Strength -Proportional limit -Yield strength -Ultimate tensile strength  Stiffness  Range  Resilience  Formability www.indiandentalacademy.com
  12. 12. There are three points on a force-deflection curve that represent strength. Studying materials using a graph is very helpful because "a picture is worth a thousand words." www.indiandentalacademy.com
  13. 13. Strength:  Strength is the measure of the force a material can withstand before the material permanently deforms. (is the maximal stress required to fracture a structure)Strength may be viewed in these three ways: 1. Proportional Limit: the point at which any permanent deformation first occurs. 2. Yield Strength: the point at which 0.1% deformation is measured. 3. Ultimate Tensile Strength: the maximum load that the wire can sustain.  strength is in units of force www.indiandentalacademy.com
  14. 14. Stiffness:  Stiffness is proportional to the slope of the linear portion of the graph of the force-deflection curve of a material. The linear portion ranges from zero to the proportional limit. The steeper the slope, the stiffer the material. (defined as the ratio of force to deflection of a member) www.indiandentalacademy.com
  15. 15. Range:  Range(flexibility) is the deflection the material will encounter before any permanent deformation occurs - from zero to the proportional limit. Beyond the proportional limit, the material will bend, but it will not return to its original shape. There is, however, a limit to the amount of bending beyond the proportional limit to which you can bend a material - the failure point is were it breaks (Range is defined as the distance the wire will bend elastically before deformation occurs, and is measured in millimeters)  range is in units of length www.indiandentalacademy.com
  16. 16. Internal stresses and external strains are characteristics of a material that can be calculated from the force-deflection curve. This relationship explains the similarity in the shapes of the force-deflection and stress- strain curves. The slope of the stress-strain curve is the elastic modulus (E) and is proportional to the stiffness. www.indiandentalacademy.com
  17. 17. Resilience  Resilience is the area under the curve out to the proportional limit.  Resilience represents the energy capacity of the material that is a combination of the strength and stiffness www.indiandentalacademy.com
  18. 18. Formability:  Formability is the amount of permanent deformation that a material can withstand before breaking. (It represents total amount of permanent bending a wire will tolerate before it breaks)  It is represented by the area under the curve between yield stress and tensile strength. www.indiandentalacademy.com
  19. 19. www.indiandentalacademy.com
  20. 20. Bauschinger Effect as described by A.J. Wilcock:  This phenomenon was discovered by Dr. Bauschinger in 1886 (Mugharabi 1987). He observed the relationship between permanent deformation and loss of yield strength and found that if the metal was permanently deformed in one direction then, it reduced its yield strength in the opposite direction. If a straight wire of wire is bent so that permanent deformation occurs and an attempt is made to increase the magnitude, bending in the same direction as had originally be done, the wire is more resistant to permanent deformation than if an attempt had been made to bend in the opposite direction. The wire is more resistant to permanent deformation because a certain residual stress remains in it, after placement of first bend. A flexibly member will not deform as easily if it is activated in the same direction as the original bends were made to form the configuration. If a bend is made in an orthodontic appliance the maximum elastic load is not the same in all direction: it is greatest in the direction identical to the original direction of bending or twisting. The phenomenon responsible for this difference is known as Bauschinger Effect.www.indiandentalacademy.com
  21. 21. Two noteworthy points about this effect are: 1. Plastic prestrain increases the elastic limit of deformation in the same direction as the prestrain. 2. Plastic prestrain decreases the elastic limit of deformation in the direction reverse to prestrain. If the magnitude of prestrain is increased, the elastic limit in the reverse direction can reduce to zero. Dr. Bauschinger said that plastic deformation in the absence of dislocation locking will not achieve as high a yield point. Furthermore if the material is subjected to reverse straining it will posses an even lower yield point in the reverse direction. This effect can be used to advantage after wire bending because of the residual stresses left in the material, improving its elastic properties in the direction to which the wire has been deformed. www.indiandentalacademy.com
  22. 22. MANUFCTURING OF ORTHODONTIC WIRES www.indiandentalacademy.com
  23. 23. Manufacture: AISI ,specially for orthodontic purposes Various steps – 1. Melting 2. Ingot Formation 3. Rolling 4. Drawing www.indiandentalacademy.com
  24. 24.  Melting : The selection and melting of the components of alloys influence the physical properties of metals.  Ingot formation : An ingot is produced by the pouring of molten alloy into a mold. It is one of the critical operations.  Rolling : It is the first mechanical step in the manufacture of a wire from the ingot. The ingot is rolled into a long bar by a series of rollers that gradually reduce it to a relatively small diameter.  Drawing : It is a more precise process by which the ingot is reduced to its final size. The wire is pulled through a small hole in a die. The size of the hole is slightly smaller than the starting diameter of the wire, in order to facilitate uniform squeezing of the wire from all sides by the walls of the die as it passes through, reducing the wire to the diameter of the die.www.indiandentalacademy.com
  25. 25. www.indiandentalacademy.com
  26. 26. PROCESS OF MANUFACTURE:  Spinner Straightening: It is the mechanical process of straightening resistant materials, usually in the cold drawn condition. The wire is pulled through rotating bronze rollers that torsionally twist it into straight condition  Pulse Straightening: It was founded by Mr. A.J. Wilcock. The wire is pulsed in special machines that permit high tensile wires to be straightened.  Stress Relief Of Stainless Steel One of the steps in manufacture or at the time of clinical application is “Stress Relieving” . It is a level of heat treatment at which internal stresses are relieved by minute slippages and readjustments in intergranular relations without the loss of hardening that accompanies the higher temperature process of annealing.  Work Hardening / Strain Hardening In a polycrystalline metal there is a build up of dislocations at the grain boundaries and occurs on intersecting slip planes. Later point defect increases and entire grain gets distorted leading to increased stress required to cause further slip, leading to stronger, harder and less ductile metal with less resistance to tarnish and corrosion. www.indiandentalacademy.com
  27. 27.  Cold Working It is the process of deforming a metal at room temperature.  Annealing It is the process in which the effects associated with cold working (for example: strain hardening, lowered ductility and distorted grains) can be reversed by simply heating the metal. Annealing generally comprises of 3 stages: Recovery Recrystallization Grain growth  Tempering: It is the process of reheating steel to intermediate temperature ranges (usually below 1000°F [525 °C] under carefully controlled conditions to permit a partial transformation into softer forms. This is done to remedy steel which when quenched in water results in very brittle martensite that is unsuitable for most mechanical applications. www.indiandentalacademy.com
  28. 28. Forms of Steel  At high temperatures (more than 1400 to 1500°F / 750 to 800°C) steel is a homogenous material with all of the carbon in solid solution in the iron. At this temperature, the iron carbide is completely decomposed. This form of steel is called "Austenite".  At low temperatures (less than 450°F / 225°C), an almost pure cementite, the hardest and most brittle form of iron- carbon combination called "Martensite" is formed.  Between these high and low extremes of temperature many intermediate phases are formed. These are various mixtures of ferrite and cementite, with crystal structures tending toward hardness in the low temperature ranges and toward softness and ductility at higher temperatures. www.indiandentalacademy.com
  29. 29. WIRE ALLOYS www.indiandentalacademy.com
  30. 30. GOLD ALLOYS  Their composition is very similar to the Type IV gold casting alloys. The typical composition of the alloy is as follows-  Gold – 15 – 65% (55-65% more typical)  Copper – 11 – 18%  Silver – 10 – 25%  Nickel – 5 – 10%www.indiandentalacademy.com
  31. 31.  The alloys contain quite a high amount about (20 – 25%) of palladium. Platinum is also present and in presence of palladium, it raises the melting point of the alloys, and makes it corrosion resistant.  Copper incorporates strength to the wire. They acquire additional strengthening through cold working, which is incorporated during the wire drawing process www.indiandentalacademy.com
  32. 32.  This combination of properties makes gold very formable and capable of delivering lower forces than stainless steel. These wires are easily joined by soldering and the joints are very corrosion resistant.  The gold wires are not used anymore in orthodontics mainly because of their low yield strength and increasing cost has made its use prohibitive. www.indiandentalacademy.com
  33. 33. HEAT TREATMENT OF GOLD WIRE  The changes that are produced in the strength and ductility of a wrought gold alloy by heat treatment are due to the alterations in the gold-copper compound present in the alloy.  In order to uniformly soften most wrought gold wire it is heated to 1300° F. for approximately 10 minutes and then quenched www.indiandentalacademy.com
  34. 34.  The wire is very soft and ductile and may be easily manipulated  If left standing at room temperature for several days, will become much harder. This phenomenon is known as “age-hardening” or “precipitation- hardening”. www.indiandentalacademy.com
  35. 35.  Other method: If, after quenching from 1300° F. The wire is reheated to approximately 840° F. and allowed to cool slowly from this temperature, the gold-copper compound tends to come out of solution.  By not using heat treatment procedures the orthodontist is not obtaining the maximum properties from this alloys. www.indiandentalacademy.com
  36. 36.  Besides precipitation hardening there are two other ways by which the strength of wrought gold wire may be increased. One of these methods is cold working. The other method is to vary the composition of the alloy constituents. www.indiandentalacademy.com
  37. 37. STAINLESS STEEL  Stainless Steel is defined as a alloy of iron that is resistant to corrosion. It was discovered accidentally in U.K. during second world was by a Sheffield metallurgist BREARLEY. It was patented in 1917.  Later chromium was added to it so that it gets a protective coating of chromium oxide on it, hence improving the corrosion resistantance. www.indiandentalacademy.com
  38. 38. Types of stainless steels  FERRITIC STAINLESS STEEL (AISI series 400) It has good corrosion resistance, is cheaply made. Disadvantage of this type of stainless steel is that it is not hard nor can it be hardened.  MARTENSITIC STAINLESS STEEL: (AISI series 400) Alloys in the 400 series contain little or no Nickel and are primarily alloys of Iron and Chromium. They can be heat treated much the same as carbon steel to form martensite at room temperature. The low resistance to fracture and high corrosion resistance of these alloys render them useful in the construction of orthodontic instruments. They are used in making surgical and cutting instruments. The disadvantage in such type of steel is its brittle nature.  AUSTENITIC STAINLESS STEELS (AISI series 302 & 304) They contain Iron, Chromium 18%, Nickel 8% and 0.15% Carbon. The Nickel content has a stabilizing effect on austenite only at high temperatures, but in the Chromium-Nickel steels, the austenite is stable even at room temperature. Hence these alloys are called "Austenitic stainless steel". Presence of Chromium in the alloy provides the austenite with the necessary strength and high resistance to corrosion. Types 302 and 304 are commonly used in orthodontic appliances. They contain about 18% chromium and 8% Nickel and hence constitute the 18-8 group of stainless steels. www.indiandentalacademy.com
  39. 39. The austenitic stainless steel, because of the presence of austenite, cannot be hardened by quenching or similar heat treatment. The only way to harden such steels is by "cold working". Under cold working, the austenitic stainless steels harden rapidly with the usual realignment of the crystalline structure. Work hardening also brings about some transformation of part of the austenite to martensite, which adds to the hardening effect. The advantages of austenitic stainless steel are: 1. Most corrosion resistant form. 2. Greater ductility. 3. Strengthening during cold working. 4. Ease of welding. 5. Readily overcome sensitization. 6. Less critical grain growth. 7. Ease of forming. www.indiandentalacademy.com
  40. 40. SENSITIZATION  The 18-8 stainless steels may lose its resistance to corrosion if it is heated between 400-9000 C due to precipitation of chromium carbide at the grain boundaries www.indiandentalacademy.com
  41. 41. Overcoming Sensitization  Reduce the carbon content  Cold working  STABILIZATION: Addition of Titanium www.indiandentalacademy.com
  42. 42. HEAT TREATMENT OF STAINLESS STEEL Done(400-500degree C) to  Eliminate some residual stress resulting from wire manufacturing and to  Prevent premature breakage of complex appliances during assemly. www.indiandentalacademy.com
  43. 43.  Kemler: 700-8000F for 5-15 minutes  Backofen and Gales: 750-8200F for 10 minutes  Funk: 8500F for 3 minutes www.indiandentalacademy.com
  44. 44. Properties:  The modulus of elasticity ranges from 23 X 106 to 24X106 psi. The wires have a very high yield strength of 50,000-280,000 psi.  This wire is strong, has excellent formability, adequate springback, offers low frictional resistance, can be soldered, has good corrosion resistance & moderate cost. www.indiandentalacademy.com
  45. 45.  By The 50‟s Rocky Mountain Orthodontics offered two tempers of cold worked stainless steels: Standard and extra hard grade  Today American Orthodontics advertises three grades of stainless steel wires: Standard, Gold Tone, Super Gold Tone www.indiandentalacademy.com
  46. 46. AUSTRALIAN ARCHWIRES  Developed by Mr. A. J. Wilcock & Dr. P. R. Begg  Acquaintance goes back to the war years at the University of Melbourne.  Dr. Begg demanded a wire that remained active in the mouth for long periods.  High Tensile wires were developed www.indiandentalacademy.com
  47. 47.  Difficulties faced with high tensile wires(1970s):  Impossible to straighten.  Work softening  Breakage of wire www.indiandentalacademy.com
  48. 48. OVERCOMING THE DIFFICULTIES  Old method - Spinner straightening: Yield stress decreases due to Bauschinger effect  New method - Pulse straightening(1980s) : No plastic deformation whatsoever. www.indiandentalacademy.com
  49. 49. Advantages of Pulse straightening  Permits the highest tensile wire to be straightened, previously not possible.  The material tensile yield stress is not suppressed in any way.  The wire has a much smoother appearance and hence less bracket friction. www.indiandentalacademy.com
  50. 50. Mr. Wilcock, Jr.’s recommendations to decrease breakage:  Use the flat beak  Round the edges of the pliers  Warm the wire www.indiandentalacademy.com
  51. 51. Grades of wire available The wires are marked in various sizes and grades ranging from 0.008” to 0.002” and regular to supreme grade. Regular with white label Regular plus with green label  Special grade with black label  Special plus with orange label  Extra special plus (ESP) with blue label  Premium with blue label  Premium plus  Supreme with blue label Regular grade is the least resilient and premium grade is the most resilient of all the wires www.indiandentalacademy.com
  52. 52. Properties  The ultimate tensile strength for pulse-straightened wires is 8-12% higher than stainless steel wires.  The load-deflection rate is higher  The pulse-straightened wires have a significantly higher working range and recovery patterns.  Frictional resistance of the pulse- straightened wires is lesser www.indiandentalacademy.com
  53. 53. Zero Stress Relaxation  This is the ability of a wire to deliver a constant light elastic force when subjected to an external force or forces of occlusion.  This indicates that the wire should have a very high and sharp yield point with low elongation.  This is probably in the region of „special plus‟ and above www.indiandentalacademy.com
  54. 54.  The stiffness of an archwire can be varied in three ways.  The first and traditional approach has been to vary the dimensions of the wire. Small changes in dimensions can result in large variations in stiffness.The difference between .016” and .014” diameter is approximately 40%.  The second approach to vary the elastic modulus E. That is, use various archwire materials such as Nitinol , Beta-Titanium, Gold alloys and stainless steel. BRAIDED WIRES www.indiandentalacademy.com
  55. 55.  A third approach, which is really an extension of the second, is to build up a strand of stainless steel wire, for example, a core wire of .0065” and six .0055” wrap, wires will produce an overall diameter approximately .0165 inches. The reason why the strand has a more flexible feel is due to the contact slip between adjacent wrap wires and the core wire of the stand.(COAXIAL WIRES)  When the strand is deflected the wrap wires, which are both under tension, and torsion will slip with respect to the core wire and each other. Providing there is only elastic deformation each wire should return to its original position. www.indiandentalacademy.com
  56. 56.  Kusy and Dilley noted that the stiffness of a triple stranded 0175” ( 3 X 008”) stainless steel arch wire was similar to that of 0.010” single stranded stainless steel arch wire. The multistranded archwire was also 25% stronger than the .010” stainless steel wire.  The .0175” triple stranded wire and .016” Nitinol demonstrated a similar stiffness. However nitinol tolerated 50% greater activation than the multistranded wire.  The triple stranded wire was also half as stiff as .016” beta-titanium.  Multistranded wire can be used as a substitute to the newer alloy wire considering the cost of nickel titanium wire. www.indiandentalacademy.com
  57. 57. COBALT-CHROMIUM-NICKEL ALLOY  Initially it was manufactured for watch springs by Elgin Watch Company, hence the name Elgiloy. CONTENTS  40% Cobalt  20% Chromium  15% Nickel  7% Molybdenum  2% Manganese  0.15% Carbon  0.4% Beryllium  15% Iron. www.indiandentalacademy.com
  58. 58. Types of Elgiloy Available in four tempers (levels of resilience)  Blue Elgiloy(soft) – can be bent easily with fingers and pliers.  Yellow Elgiloy(ductile) – Relatively ductile and more resilient than blue Elgiloy.  Green Elgiloy(semi-resilient) – More resilient than yellow Elgiloy  Red Elgiloy(resilient) -Most resilient of Elgiloy wires www.indiandentalacademy.com
  59. 59.  All four alloy tempers have the same composition. (last three tempers have mechanical properties similar to less expensive SS wires)  Differences in mechanical properties arise from variations in the wire processing.  As with SS alloys, the corrosion resistance of Elgiloy arises from a thin passivating chromium oxide layer on the wire surface.  Popular because the as-received wire can easily be manipulated into desired shapes and then heat treated to achieve considerable increases in strength and resilience. www.indiandentalacademy.com
  60. 60. HEAT TREATMENT  The ideal temperature for heat treatment is 900°F or 482°C for 7-12 min in a dental furnace.  This causes precipitation hardening of the alloy increasing the resistance of the wire to deformation. www.indiandentalacademy.com
  61. 61. Disadvantages  Greater degree of work hardening  High temperatures (above 1200°F) cause annealing Advantages  Greater resistance to fatigue and distortion  Longer function as a resilient spring  High moduli of elasticitywww.indiandentalacademy.com
  62. 62. Comparison with stainless steel  Values of modulus of elasticity (elastic force delivery) for the Elgiloy Blue and SS orthodontic wires are very similar  Force delivery and joining characteristics are similar.  Contain comparable amount of nickel to that found in the SS wires, which may present concerns about biocompatibility. www.indiandentalacademy.com
  63. 63. Clinical application  Elgiloy Blue wires is used for fabrication of the fixed lingual quad- helix appliance, which produces slow maxillary expansion for the treatment of maxillary constriction or crossbite in the primary and mixed dentitions. www.indiandentalacademy.com
  64. 64. ALPHA TITANIUM Pure titanium:  Below 885° C - hexagonal closed packed or alpha lattice is stable  At higher temperature the metal rearranges into body centered cubic or beta crystal.  HCP- possesses fewer slip planes www.indiandentalacademy.com
  65. 65.  Gets hardened by absorbing intraoral free hydrogen ions, which turn it into titanium hydride, at the oral temperature of 37°C and 100% humidity.  Any modifications if required should be done within six weeks (Mollenhauer) www.indiandentalacademy.com
  66. 66. BETA TITANIUM (TITANIUM MOLYBDENUM ALLOY OR T.M.A.)  Introduced by Dr. Burstone (1980) Composition 80% Titanium 11.5% Molybdenum 6% Zirconium 4.5% Tin www.indiandentalacademy.com
  67. 67. Advantages of TMA v/s Nitinol  Smoother  Can be welded  Good formability Advantages of TMA v/s S.S.  Gentler forces  More range  Higher springback  Drawback: High coefficient of friction www.indiandentalacademy.com
  68. 68. Low friction TMA:  Introduced by Ormco  Done by ion implantation beam mechanism TMA Colours:  Also developed by Ormco  Implantation of oxygen and nitrogen ions  Ensures colour fastness www.indiandentalacademy.com
  69. 69. Welding of TMA wire  POSITIONING - Set down of 80% - 25 - 60 % recommended Broad, flat electrodes One wire"set down" into the other. www.indiandentalacademy.com
  70. 70. Welding of TMA wire Below optimal - low strength, separation of wire Optimal welding - good ductility strength atleast 90% of unweld wire Higher than optimal - good strength, low ductility High voltage - Wire become brittle Complete burnout www.indiandentalacademy.com
  71. 71. Welding of TMA wire Round wires - Simple to weld. - Require lower voltages  SMALLER CONTACT AREA - Low voltage - Point contact - „T‟ joint  SINGLE PULSE - Short duration. TMA wire can be welded to TMA wire Not possible to weld TMA to SS www.indiandentalacademy.com
  72. 72. Welding of TMA wire Improper Welding Low voltage - The parts may delaminate High voltage - Wire become brittle Cracks Melting www.indiandentalacademy.com
  73. 73. NICKEL-TITANIUM ALLOYS  CONVENTIONAL - NITINOL  SUPERELASTIC  Pseudoelastic-Japanese NiTi  Thermo elastic-Cu NiTi. www.indiandentalacademy.com
  74. 74. NICKEL-TITANIUM ALLOYS 2 forms of NiTi alloys 1. Martensite – Face centered (close packed hexagonal). 2. Austenite – Body centered cubic/tetragonal lattice. www.indiandentalacademy.com
  75. 75. NICKEL-TITANIUM HYSTERESIS • The transformation at different temperatures. • The difference between cooling and heating. • The range for most binary alloys is 400 – 600 www.indiandentalacademy.com
  76. 76. NITINOL  Was invented in early 60‟s by William F. Buchler, a researcher metallurgist of the Naval Ordinance Laboratory in Silver Springs, Maryland  The name Nitinol is given for NI for nickel, TI for titanium and NOL for Naval Ordinance Laboratory.  It was initially developed for space programs but was first introduced into dentistry by Unitek cooperation in 1970‟s .  Clinical use of Nitinol wire started in May 1972 by G.F.ANDREASEN et al.www.indiandentalacademy.com
  77. 77. NITINOL NiTi wires have two remarkable properties which makes its use in dentistry: SHAPE MEMORY  The characteristic of being able to return to a previously manufactured shape when it is heated to a TTR.  Ability of the material to remember its original shape after being plastically deformed while in the martensitic form. Superelasticity: Superelasticity means the ability of the wire to exert the same force whether it is deflected a relatively small or a large distance. This can be produced by stress, not by temperature difference and is called stress induced martensitic transformation. www.indiandentalacademy.com
  78. 78. NITINOL In orthodontic applications 1. Requires fewer arch wire changes. 2. Requires less chair time. 3. Shortens the time required to accomplish the rotations and leveling 4. Produces less patient discomfort. www.indiandentalacademy.com
  79. 79. NITINOL PHYSICAL PROPERTIES Material property Nitinol Stainless steel Alloy Nickel, Titanium Iron, Chrome,Nickel Ultimate strength 230,000 to 250,000 p.s.i 280,000 to 300,000 p.s.i Modulus of elasticity 4.8 x106 p.s.i 28.5 x 106 p.s.i www.indiandentalacademy.com
  80. 80. NITINOL STORED ENERGY COMPARISONS Stored energy of Nitinol wire is significantly greater than an equivalent SS wire.this comparison was based upon the wires being bent 90 degrees www.indiandentalacademy.com
  81. 81. NITINOL CLINICAL APPLICATIONS Class I ,II,III malocclusions in both extraction and non extraction cases www.indiandentalacademy.com
  82. 82. NITINOL  Primary criterion – Amount of malalignment from the ideal arch form.  More the deflection – more the benefit. www.indiandentalacademy.com
  83. 83. NITINOL  Imp benefits - a rectangular wire is inserted early in the treatment.  Simultaneous rotation, leveling, tipping and torquing can be accomplished earlier with a resilient rectangular wire, Cross bite correction Uprighting impacted canines Opening the bite www.indiandentalacademy.com
  84. 84. NITINOL www.indiandentalacademy.com
  85. 85. NITINOL LIMITATIONS 1.Can`t be bent with sharp – cornered instruments. 2.It will readily break when bent over a sharp edge. 3.The bending of loops or omega bends are not recommended. ( especially closing loops ). 4.Can`t be soldered or welded to itself without annealing the wire.www.indiandentalacademy.com
  86. 86. 5. Bending of tie-back hooks entails a high risk of failure. 6. Cinch – backs. - Annealing - Dark blue color flame. - Cherry red flame – brittle. www.indiandentalacademy.com
  87. 87. Phase - Transformation  AUSTENITE PHASE  MARTENSITE PHASE  Martensite start(MS)  Martensite finish(MF)  Austenite start(AS)  Austenite finish(AF) www.indiandentalacademy.com
  88. 88. NICKEL-TITANIUM ALLOYS  SUPERELASTIC  Chinese NiTi  Pseudoelastic-Japanese NiTi  Thermo elastic-Cu NiTi. www.indiandentalacademy.com
  89. 89. CHINESE NITI WIRE  CHINESE NiTi wire - A new orthodontic wire - C. J. BURSTONE ( AJO JUNE 1985)  New NiTi by Dr.Tien Hua Cheng and associates at the General Research Institute for non Ferrous Metals, in Beijing, China.  Austenitic parent phase + Little work hardened  Chinese NiTi wire has much lower transitional temperature than NiTi wire.www.indiandentalacademy.com
  90. 90. CHINESE NITI WIRE 1. Applicable in situations where large deflections are required. 2. When tooth are badly malpositoned. 3. Niti wire deformation is not time dependent CLINICAL SIGNIFICANCE www.indiandentalacademy.com
  91. 91. JAPANESE NITI The super - elastic property of the Japanese NiTi alloy wire for use in orthodontics. - Fujio Miura et al ( AJODO July 1986 ) In 1978 Furukawa electric co.ltd of Japan produced a new type of alloy 1. High spring back. 2. Shape memory. 3. Super elasticity.www.indiandentalacademy.com
  92. 92. CLINICAL IMPLICATIONS  Alignment of badly malposed teeth  Distalize the molar  Expansion of arch  Gain/Close the space  Periodontally compromised pts www.indiandentalacademy.com
  93. 93. CLINICAL APPLICATIONS INITIAL TWO MONTHS LATER www.indiandentalacademy.com
  94. 94. CLINICAL APPLICATIONS www.indiandentalacademy.com
  95. 95. COPPER NiTi • Introduced by Rohit sachdeva • It has the advantage of generating more constant forces than any other super elastic nickel titanium alloys. • More resistant to deformation www.indiandentalacademy.com
  96. 96. QUATERNARY METAL – Nickel, Titanium, Copper, Chromium. Copper enhances thermal reactive properties and creates a consistent unloading force. www.indiandentalacademy.com
  98. 98. COPPER NiTi CLASSIFICATION  Type I Af – 150 c  Type II Af - 270 c-MOUTH BREATHERS  Type III Af - 350c-  Type IV Af - 400c-ONLY AFTER CONSUMING HOT FOOD AND BEVERAGES www.indiandentalacademy.com
  99. 99. COPPER NiTi ADVANTAGES OF COPPER NiTi ALLOYS OVER OTHER NiTi WIRES - Smaller loading force for the same degree of deformation. (20% less ) - Reduced hysteresis makes to exert consistent tooth movement and reduced trauma. www.indiandentalacademy.com
  100. 100. Clinical Applications  Provides 3 dimensional control  Effective in surgical orthodontic cases  Eliminates need to change arch wires frequently DISADVANTAGES  Bracket friction will be more when large wires are used ADVANTAGES www.indiandentalacademy.com
  101. 101. ESTHETIC ARCHWIRES  Composites: can be composed of ceramic fibers that are embedded in a linear or cross-linked polymeric matrix.  Developed by a process known as pultrusion www.indiandentalacademy.com
  102. 102. A prototype (reported by Kusy) shows the following characteristics:  Tooth coloured  Adequate strength  Variable stiffness  Resilience and springback comparable to Niti  Low friction (beta staging)  Enhanced biocompatibility (beta staging) (Formability, weldability are unknown) www.indiandentalacademy.com
  103. 103. OPTIFLEX Made of clear optical fibre; comprises of three layers: 1. A silicon dioxide core 2. A silicon resin middle layer 3. A stain resistant nylon outer layer Silicon Dioxide Core Nylon Outer Layer Silicon resin Middle Layer www.indiandentalacademy.com
  104. 104. Properties  The most esthetic orthodontic arch wire to date.  Completely stain resistant  Exerts light continuous forces  Very flexible www.indiandentalacademy.com
  105. 105. Precautions to be taken with Optiflex  Use elastomeric ligatures.  No Sharp bends  Avoid using instruments with sharp edges, like the scalers etc., to force the wire into the bracket slot.  Use the (501) mini distal end cutter (AEZ)  No rough diet  Do not “cinch Back” www.indiandentalacademy.com
  106. 106. Other esthetic archwires  E.T.E. coated Nickel Titanium: E.T.E. is an abbreviation for ELASTOMERIC POLY TETRA FLORETHYLENE EMULSION  Stainless steel or Nickel titanium arch wire bonded to a tooth coloured EPOXY coating www.indiandentalacademy.com
  107. 107. Cross-section 1970s: Only S.S.; varying the cross-sectional diameter) v/s Modulus (1980s: S.S., Niti, B-Ti; varying the elastic modulus) v/s Transition temperature (1990s: Cu Niti; Varying TTR/Af) www.indiandentalacademy.com
  108. 108. APPLYING ARCHWIRES www.indiandentalacademy.com
  109. 109. PROPERTY SS ELGILOY TMA NiTi Cost Low Low High High Force Delivery High High Intermediate Light Springback Low Low Intermediate High Formability Excellent Excellent Excellent Poor Ease of joining Must be reinforced with solder Must be reinforced with solder Weldable Cannot be soldered or welded Friction Lower Lower Higher Higher Biocompati bility Concern Concern Excellent Concernwww.indiandentalacademy.com
  110. 110. Wire alloy Composition (Wt%) Modulus of elasticity (Gpa) Yield strength (MPa) Springback Austenit ic SS 17-20%Cr ,8- 12%Ni 0.15%C(max) Rest-Fe 160- 180 1100- 1500 0.0060-0.0094 Ar 0.0065-0.0099 Ht Co-Cr- Ni (Elgiloy -Blue) 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 β- titanium (TMA) 77.8%Ti, 11.3%Mo, 6.6%Zr, 4.3%Sn 62-69 690-970 0.0094-0.011 NiTi 55%Ni, 45% Ti (Approx)-& may contain small amounts of Cu 34 210-410 0.0058-0.016 www.indiandentalacademy.com
  111. 111. IN SEARCH OF THE IDEAL ARCHWIRE..by Kusy www.indiandentalacademy.com
  112. 112. CONCLUSION  It can be seen that there is not a single arch wire that meets all the requirements of the orthodontist. We still have a long way to go, in terms of finding the „ideal‟ archwire. But, with such rapid progress being made in science and technology, I am sure that we will see significant improvements in arch wires in the near future.  Also, we must consider ourselves fortunate to have such a wide array of materials to choose from. Just imagine working with just a single type of Gold alloy wire, like they used to not so long ago. So we should appreciate this fact and try to make the most of what we have. www.indiandentalacademy.com
  113. 113. THANK YOU www.indiandentalacademy.com
  114. 114. LIST OF REFERENCES  Applied Dental Materials: John F. Mc Cabe 7th Edition 1990 Blackwell Scientific Publication. Pg. 69.  The Clinical handling of Dental Materials: Bernard G.N. Smith, Paul S. Wright, David Brown. WRIGHT Publications, 2nd Edition, 1994; Pg. 195-199.  Howe G.L. Greener E.H., Crimmins D.S.: Mechanical properties and stress relief of stainless steel orthodontic wire. AO 1968; 38: 244-249.  Andreasen G. Heilman H., Krell D.: Stiffness changes in thermodynamic NiTinol with increasing temperature AO 1985; 55:120-126.  Edie J.W.: Andreasen G.F., Zaytoun M.P.: Surface corrosion of Nitinol and stainless steel under clinical conditions AO 1981; 51:319-324.  Miura F, Mogi M. Yoshiaki O: Japanese NiTi alloy wire use of electric heat resistance treatment method EJO 198; 10; 187- 191.  Andreasen G.F., Murrow R.E. : Laboratory and clinical analyses of nitinol wire AJODO 1978; 73: 142-151.  Evans T.J.W, Durning P: Orthodontic Product update – Aligning archwires, the shape of things to come? – A fourth and fifth phase of force delivery. BJO 1996; 23:269-275.  Kusy R.P. : A review of contemporary archwires-Their properties and characteristics AO 1997; 67: 197-207. www.indiandentalacademy.com
  115. 115.  Wilcock A.J., Jr. : Applied materials engineering for orthodontic wires. Aust. Jor. Orthod. 1989; V:22-29.  Burstone C.J. Bai Q., Morton J.Y. : Chinese NiTi Wire – A new orthodontic alloy AJODO 1985; 87; 445-452.  Fillmore G.M., Tomlinson J.L.: Heat treatment of Cobalt chromium alloys of various tempers AO : 1979; 49: 126-130.  Kohl R.W. : Metallurgy in orthodontics. AO 1964; 34: 37-42.  Waters N.E.: Orthodontic product update-Super elastic Nickel-Titanium wires. BJO 1992; 19: 319-322.  Andreasen G.G., Hilleman T.B.: An evaluation of 55 Cobalt substituted NiTinol wire for the use in orthodontics. JADA 1971; 82: 1373-1375.  Beckoten W.A., Gales G.F.: Heat treated stainless steel for orthodontics. AJODO 1952; 38: 755-765.  Wilcock A..J., Jr: JCO Interview, JCO 1988; 22: 484- 489.  Burstone C.J., Goldberg A.J.: Beta Titanium. A new orthodontic alloy. AJODO 1980; 77; 121 –132.  Kapilla S., Sachdeva R: Mechanical properties and clinical applications of orthdontic wires. www.indiandentalacademy.com
  116. 116.  Miura F, Mogi M., Ohura Y and Humanaka H: The super- elastic property of Japanese NiTi alloy wire for use in orthodontics AJODO 1986; 90:1-10.  Proffit W.R., Fields H.W Jr.: Contemporary orthodontics – Mosby 3rd Edition 2000 Pg 326-334.  Thurow R.C.: Edgewise orthodontics. The C.V.Mosby Company 1982 4th Edition. Graber T.M., Vanarsdall R.L. Jr: Orthodontics – Current principles and Techniques. Mosby 1994 2nd Edition.  Philips R.W.: Skinner‟s Science of dental Materials Prism Books Pvt. Ltd. 1991 – 9th Edition.  Craig R.G. : Restorative dental materials. The C.V. Mosby Co. 1989 8th Edition.  Hudgine J.J.: The effect of long-term deflection on permanent deformation of Nickel titanium archwires AO 1990: 283-293.  Kusy R.P., Sterens L.E: Triple Stranded stainless steel wires 1987: 18-32.  Sachdeva R.C.L.: Orthdontics for the next millennium. ORMCO Publishing. www.indiandentalacademy.com
  117. 117. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com