STAINLESS STEEL AND IT’S
APPLICATION IN
ORTHODONTICS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indi...
SYNOPSIS
 Introduction.
 History of stainless steel.
 Composition and functions of each
ingredient.
 Types and grade o...
SYNOPSIS
 Structure on solidification and grain structure.
 Types of crystal lattice.
 Crystal imperfections.
 Physica...
SYNOPSIS
 General properties of stainless steel.
 Sensitisation.
 Stabilisation.
 Ductility and malleability.
 Solder...
SYNOPSIS
 Characteristics of Clinical relevance.
 Spring back.
 Modulus of resilience.
 Stiffness.
 Load deflection r...
SYNOPSIS
 Stress relaxation.
 Strength.
 Biohostability.
 Application in Orthodontic wires.
 Ideal requirements of Or...
SYNOPSIS
 Australian orthodontic arch wire.
 Unique characteristics.
 Manufacture, grading and color coding.
 Advantag...
INTRODUCTION
 Steel is an alloy of Iron and Carbon.
Carbon content should not exceed
0.2% max.
 When it contains 12 to 1...
HISTORY
 First developed by accident by Harry Brearley in
Sheffield, England.
 Stainless steel entered dentistry in 1919...
COMPOSITION
TYPES CHROMIUM NICKEL CARBON
FERRITIC 11.5-27% 0 0.2% MAX
AUSTENITIC 16-26% 7-22% 0.25%
MARTENSITIC 11.5-27% 0...
FUNCTIONS
 Chromium:
 Increases tarnish and corrosion resistance. A thin transparent,
tough, impervious oxide layer of C...
FUNCTIONS
 Silicon:
 Deoxidiser and scavenger.
 Titanium:
 Inhibits the precipitation of Chromium
carbide.
www.indiand...
GRADES OF STAINLESS
STEEL
 SOFT.
 HALF HARD OR SPRING HARD.
 HARD.
www.indiandentalacademy.com
METTALURGY
www.indiandentalacademy.com
Types of crystal lattice – (FCC)
Austenitic *
 Most corrosion resistant of all types of stainless steel.
 Formed between...
Types of crystal lattice – (BCC)
Ferritic
 Stable between room temperature and 912 C.
 Carbon has low solubility in this...
Types of crystal lattice – (BCT)
Martensitic.
 If austenite is cooled rapidly (Quenched) it will
undergo spontaneous diff...
Types of crystal lattice – (BCT)
Martensitic.
 Increased strength and hardness – used for
surgical and cutting instrument...
PHYSICAL PROPERTIES.
 stress:
 Force per unit area.
 Tensile, compressive or shear stress.
 Strain:
 Proportion of ch...
MECHANICAL PROPERTIES.
• Modulus of Elasticity: This is a measure of stiffness of the material. Gives the
flexibility of t...
GENERAL PROPERTIES
 SENSITISATION:
 When heated between 400 and 900 C 18-8
stainless steel loses it’s resistance to tarn...
GENERAL PROPERTIES
 Stabilization:
 Introduction of any element which
precipitates as carbide instead of
chromium.
 Tit...
GENERAL PROPERTIES
 Ductility:
 Ability of a material to be drawn into wires.
 Ability of a material to withstand perma...
SOLDERING
 It is a process of joining two metals by the use of a intermediate alloy
which has a lower melting point.
 So...
SOLDERING
 The flux is applied and the heavier gauge
is heated first.
 Flux should cover all the area and the
metal shou...
SOLDERING
 Flux:
 Aids in removing the oxide coating so as to increase the
flow.
 Dissolves any surface impurities.
 R...
Welding
 Joining of two or more metal pieces directly under
pressure without introduction of an intermediary or a
filler ...
Factors to be taken into account
during soldering and welding
 As the annealing temperature of stainless
steel falls with...
Cold Working
 The process of plastically deforming a
metal at a temperature below that at
which it recrystallises new gra...
Strain Hardening or Work
Hardening.
 If a metal is continuously stressed it becomes stiffer and harder.
 Hardening of a ...
Heat treatment
 General process using thermal energy
to change the characteristics of metallic
alloys as in tempering, pr...
Annealing
 The effect associated with cold working such
as strain hardening, low ductility and distorted
grains can be re...
Annealing
 Recovery:
 Cold work properties begin to disappear.
 Slight decrease in tensile strength and no change in du...
Hardening heat treatment
 There is no hardening heat treatment
for austenitic steel due to it’s stability.
 It can only ...
Characteristics of Clinical
relevance
 Spring back (maximum elastic deflection):
 The extent to which the range recovers...
Characteristics of Clinical
relevance
 Resilience:
 The capacity of a material to absorb
energy when the material is ela...
Characteristics of Clinical
relevance
 Stiffness:
 Amount of force required to produce a
specific amount of deformation....
Characteristics of Clinical
relevance
 Load deflection rate:
 For a given load the deflection observed within
the elasti...
Working range and flexibilty
 The distance a wire will bend elastically
before permanent deformation occurs.
 Measured i...
Formability
 The ability to bend wires into desired
configurations as loops, coils and stops
without fracturing the wire....
Stress relaxation
 When a wire has been deformed and
held in a fixed position the stress may
diminish with time even thou...
Biohostability
 The ease with which a material will
culture bacteria, spores or viruses.
www.indiandentalacademy.com
Ideal requirements of
Orthodontic arch wires
 Esthetic
 Good range
 Tough
 Poor biohost
 Good springback
 Low fricti...
Variation in diameter and
length of orthodontic wires
STIFFNESS STRENGTH RANGE
x MODULUS OF
ELASTICITY
X resiliency X elas...
Australian Orthodontic arch
wires
 Claude Arthur J Wilcock developed an orthodontic
arch wire for use in the Beg techniqu...
Australian Orthodontic arch
wires
 Manufacture:
 Spinner straightening and pulse
straightening.
 Spinner straightening:...
Australian Orthodontic arch
wires
 Types:
 Regular
 Regular plus
 Special
 Special plus
 Extra special plus
 Suprem...
www.indiandentalacademy.com
Thank you
For more details please visit
www.indiandentalacademy.com
Upcoming SlideShare
Loading in...5
×

Stainless steel and it’s application in orthodontics /certified fixed orthodontic courses by Indian dental academy

940

Published on


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
0091-9248678078

Published in: Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
940
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
1
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Stainless steel and it’s application in orthodontics /certified fixed orthodontic courses by Indian dental academy "

  1. 1. STAINLESS STEEL AND IT’S APPLICATION IN ORTHODONTICS. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. SYNOPSIS  Introduction.  History of stainless steel.  Composition and functions of each ingredient.  Types and grade of stainless steel.  Metallurgy.  Nature of metallic bonding. www.indiandentalacademy.com
  3. 3. SYNOPSIS  Structure on solidification and grain structure.  Types of crystal lattice.  Crystal imperfections.  Physical properties.  Tensile strength  Proportional limit and Hooke’s law.  Mechanical properties.  Elasticity and Elastic limit.  Modulus of elasticity .  Ductility and malleability.  Yeild strength and ultimate strength www.indiandentalacademy.com
  4. 4. SYNOPSIS  General properties of stainless steel.  Sensitisation.  Stabilisation.  Ductility and malleability.  Soldering and welding.  Strain hardening.  Cold working.  Heat treatment.  Annealing.  Hardening heat treatment www.indiandentalacademy.com
  5. 5. SYNOPSIS  Characteristics of Clinical relevance.  Spring back.  Modulus of resilience.  Stiffness.  Load deflection rate.  Working range and flexibility.  Formability. www.indiandentalacademy.com
  6. 6. SYNOPSIS  Stress relaxation.  Strength.  Biohostability.  Application in Orthodontic wires.  Ideal requirements of Orthodontic wires.  Wire characteristics and clinical relevance.  Variation in diameter and length it’s relation with strength stiffness and range. www.indiandentalacademy.com
  7. 7. SYNOPSIS  Australian orthodontic arch wire.  Unique characteristics.  Manufacture, grading and color coding.  Advantages of stainless steel.  Disadvantages of stainless steel.  Conclusion. www.indiandentalacademy.com
  8. 8. INTRODUCTION  Steel is an alloy of Iron and Carbon. Carbon content should not exceed 0.2% max.  When it contains 12 to 13% chromium it is called stainless steel.  Steel exists in three Ferritic, austenitic and martensitic forms. www.indiandentalacademy.com
  9. 9. HISTORY  First developed by accident by Harry Brearley in Sheffield, England.  Stainless steel entered dentistry in 1919, introduced at Krupp’s dental poly clinic in Germany by F. Haupt Meyer.  In 1930 Angle used it to make ligature wires.  By 1937 the value of stainless steel as an orthodontic wire had been confirmed.  Stainless steel today is used to make arch wires,ligature wires, band material, brackets and buccal tubes. www.indiandentalacademy.com
  10. 10. COMPOSITION TYPES CHROMIUM NICKEL CARBON FERRITIC 11.5-27% 0 0.2% MAX AUSTENITIC 16-26% 7-22% 0.25% MARTENSITIC 11.5-27% 0-2.5% 0.15-1.2% Minor quantities of Silicon, phosphurous, sulphur, Manganese, Tantalum. BALANCE COMPOSED OF IRON www.indiandentalacademy.com
  11. 11. FUNCTIONS  Chromium:  Increases tarnish and corrosion resistance. A thin transparent, tough, impervious oxide layer of Chromium oxide forms on the surface of the alloy when subjected to room air.- “passivating film effect”.  Increases hardness, tensile strength and proportional limit.  Nickel:  Increases strength.  Increases tarnish and corrosion resistance.  Cobalt:  Decreases hardness.  Manganese:  Scavenger for sulphur.  Increases hardness during quenching. www.indiandentalacademy.com
  12. 12. FUNCTIONS  Silicon:  Deoxidiser and scavenger.  Titanium:  Inhibits the precipitation of Chromium carbide. www.indiandentalacademy.com
  13. 13. GRADES OF STAINLESS STEEL  SOFT.  HALF HARD OR SPRING HARD.  HARD. www.indiandentalacademy.com
  14. 14. METTALURGY www.indiandentalacademy.com
  15. 15. Types of crystal lattice – (FCC) Austenitic *  Most corrosion resistant of all types of stainless steel.  Formed between 912 – 1394C  AISI 302,304 – 18% Chromium, 8% Nickel and 0.15%(302) 0r 0.08%(304) Carbon – 18-8 stainless steel.  Austenite is pefered to Ferritic because of greater ductility, ability to undergo more cold work without fracture. Increased strength during cold working, ease of welding, readily overcomes sensitisation, less critical grain growth and ease of forming.  When austenite is allowed to cool slowly to room temperature it forms Fe3C and ferrite. The iron carbide compound is called cementite and the solid solution of ferrite along with cementite is called pearlite. www.indiandentalacademy.com
  16. 16. Types of crystal lattice – (BCC) Ferritic  Stable between room temperature and 912 C.  Carbon has low solubility in this structure.  Interstices in BCC are very small.  ASI 400  Good corrosion resistance at low cost provided increased strength is not required.  Temperature change does not nduce phase change in solid state.  The alloy is not hardenable by heat treatment.  Not readily work hardenable.  Little application in Dentistry. www.indiandentalacademy.com
  17. 17. Types of crystal lattice – (BCT) Martensitic.  If austenite is cooled rapidly (Quenched) it will undergo spontaneous diffisionless transformation to a Body Centered Tetragonal.  The lattice is highly distorted, strained resulting in a hard strong brittle alloy.  Martensite decomposes into ferrite and carbide.  Decomposition is accelerated by appropriate heat treatment to reduce hardness but this is counter balanced by increased toughness – “Tempering”  AISI 400 www.indiandentalacademy.com
  18. 18. Types of crystal lattice – (BCT) Martensitic.  Increased strength and hardness – used for surgical and cutting instruments.  Yeild strength of 492 MPa (annealed). Hardened – 1898 MPa  Brinell’s hardness range- 230 – 600.  Elongation – less than 2%.  Reduced ductility.  Corrosion rsistance is the least. Reduced further with Hardening heat treatment. www.indiandentalacademy.com
  19. 19. PHYSICAL PROPERTIES.  stress:  Force per unit area.  Tensile, compressive or shear stress.  Strain:  Proportion of change in dimension to the applied stress.  Elastic strain: Original shape is regained.  Plastic strain: Original shape is not regained.  Elasticity:  Ability of the stressed material to return to it’s original form.  Elastic limit:  The greatest stress to which a material can be subjected so that it will return to it’s original dimension when the forces are released.  Hookes law:  Stress is proportional to strain within the proportional limit.  Proportional limit:  Greatest possible stress that can be induced in a material such that stress is directly proportional to strain. www.indiandentalacademy.com
  20. 20. MECHANICAL PROPERTIES. • Modulus of Elasticity: This is a measure of stiffness of the material. Gives the flexibility of the wire component. 179 GPa • Strength: Capacity of a material to resist a deforming load without exceeding the limits of plastic deformation. Strength is proportional to the resiliency of the material. • Yield strength: The stress at which increase in strain is disproportionate to stress. 1579 MPa 0.2% plastic deformation. •Ultimate strength: The strength at which the material fractures. 2117 MPa •Tensile strength – 200 MPa •Resilience: Total energy storage capacity. The amount of energy absorbed by a structure when it is stressed within it’s proportional limit. •Knoop hardness: 600 • Stiffness: Force/ distance. It is the measure of resistance to deformation.www.indiandentalacademy.com
  21. 21. GENERAL PROPERTIES  SENSITISATION:  When heated between 400 and 900 C 18-8 stainless steel loses it’s resistance to tarnish and corrosion.  Carbon atoms migrate to grain boundaries and combine with chromium to form chromium carbide where the energy is the highest.  If the stainless steel is severely cold worked the carbide precipitate along slip planes, as a result the areas deficient in chromium are less localized and carbides are more uniformly distributed. www.indiandentalacademy.com
  22. 22. GENERAL PROPERTIES  Stabilization:  Introduction of any element which precipitates as carbide instead of chromium.  Titanium approximately six times the carbon content. www.indiandentalacademy.com
  23. 23. GENERAL PROPERTIES  Ductility:  Ability of a material to be drawn into wires.  Ability of a material to withstand permanent deformation under tensile load without fracture.  Malleability:  Ability of a metal to withstand permanent deformation under compressive forces without fracturing. www.indiandentalacademy.com
  24. 24. SOLDERING  It is a process of joining two metals by the use of a intermediate alloy which has a lower melting point.  Soldering temperature – 620 – 665 C.  Ideally silver solders are used- alloy of silver, copper, zinc to which tin and indium are added to lower the fusion temperature and improve solderability.  Technical considerations:  Needle like non luminous gas air flame is used.  Thinner the diameter of the flame, less the metal surrounding the joint is annealed.  The work is held 3mm beyond the tip of the blue cone in the reducing zone of the flame.  Soldering should be observed in shadow against a black background so the temperature can be judged by the color of the work. The color should not exceed dull red.  If possible the parts should be tag welded to hold the parts together. www.indiandentalacademy.com
  25. 25. SOLDERING  The flux is applied and the heavier gauge is heated first.  Flux should cover all the area and the metal should be allowed to flow around the joint. The work should be immediately quenched in water.  Other methods of soldering:  Electric resistance heating.  Indirect heating using brass wire intermediary. www.indiandentalacademy.com
  26. 26. SOLDERING  Flux:  Aids in removing the oxide coating so as to increase the flow.  Dissolves any surface impurities.  Reduces the melting point of the solder.  Composition:  Borax glass – 55%  Boric acid – 35%  Silica – 10%  Potassium flouride is added to dissolve the passivating effect of Chromium.  Potassium flouride and Boric acid should be in 1:1 concentration www.indiandentalacademy.com
  27. 27. Welding  Joining of two or more metal pieces directly under pressure without introduction of an intermediary or a filler material.  Spot welding is used to join various components in orthodontics. A large current is allowed to pass through a limited area on the overlapping metals to be welded.  The resistance of the material to the flow of current produces intense localized heating and fusion of metals.  The welded area becomes susceptible to corrosion due Chromium carbide precipitation and loss of passivation.  The grain structure is not affected.  Increased weld area increases the strength. www.indiandentalacademy.com
  28. 28. Factors to be taken into account during soldering and welding  As the annealing temperature of stainless steel falls within the soldering and welding temperature ranges, these procedure can lead to loss of working range and elasticity of the metal.  Precautions:  By using low fusing solders.  Using low diameter needle like flame.  Reducing the number of welding procedures and duration. www.indiandentalacademy.com
  29. 29. Cold Working  The process of plastically deforming a metal at a temperature below that at which it recrystallises new grains, which is usually one-third to one half times is absolute melting point temperature.  The deformation of space lattices of stainless steel by mechanical manipulation at room temperature. www.indiandentalacademy.com
  30. 30. Strain Hardening or Work Hardening.  If a metal is continuously stressed it becomes stiffer and harder.  Hardening of a metal by cold working is called strain hardening of work hardening.  During strain hardening dislocations tend to build up at grain boundaries. The barrier effect of grain boundaries will cause further slip to occur at intersecting slip planes. Point defects increase resulting in a distorted grain structure.  Consequences:  Increased surface hardness.  Greater yield and ultimate strength.  Less ductility.  Proportional limit is increased.  Reduced resistance to corrosion.  No change in elastic modulus.  Majority of these properties id due to a phase change from FCC to BCC lattice structure. www.indiandentalacademy.com
  31. 31. Heat treatment  General process using thermal energy to change the characteristics of metallic alloys as in tempering, precipitation hardening or annealing. – Robert P Kusy 1997.  Annealing  Hardening www.indiandentalacademy.com
  32. 32. Annealing  The effect associated with cold working such as strain hardening, low ductility and distorted grains can be reversed by simply heating the metal.  The greater the amount of cold working the more rapidly the effects can be reserved by annealing.  Stages of annealing:  Recovery.  Recrystallisation.  Grain growth. www.indiandentalacademy.com
  33. 33. Annealing  Recovery:  Cold work properties begin to disappear.  Slight decrease in tensile strength and no change in ductility.  All the residual stress is relaxed.  Recrystallisation:  Old grains disappear totally and are replaced with strain free grains.  Occurs mostly in regions where defects have accumulated.  It attains it’s soft and ductile condition at the end of this stage.  Grain Growth  The Grain size and number of the recrystallised structure depends on the amount of prior cold working.  On repeated annealing larger grains consume smaller grains. At the end of annealing the number of grains decrease and size increases. www.indiandentalacademy.com
  34. 34. Hardening heat treatment  There is no hardening heat treatment for austenitic steel due to it’s stability.  It can only be hardened by cold working. www.indiandentalacademy.com
  35. 35. Characteristics of Clinical relevance  Spring back (maximum elastic deflection):  The extent to which the range recovers upon deactivation of an activated arch wire.  A measure of how far a wire can be deformed without causing permanent deformation or exceeding the limits of the material.  Higher the spring back, grater the working range and lesser are the requirements of frequent activations.  Stainless steel has a spring back lesser than Nickel-titanium or beta titanium. www.indiandentalacademy.com
  36. 36. Characteristics of Clinical relevance  Resilience:  The capacity of a material to absorb energy when the material is elastically deformed.  It is measured by the area under the stress strain curve. www.indiandentalacademy.com
  37. 37. Characteristics of Clinical relevance  Stiffness:  Amount of force required to produce a specific amount of deformation.  Stiffness d4 www.indiandentalacademy.com
  38. 38. Characteristics of Clinical relevance  Load deflection rate:  For a given load the deflection observed within the elastic limit.  The force magnitude delivered by an appliance and is proportional to the modulus of elasticity.  Low load deflection rate provides ability to apply low forces, a more constant force over time while deactivation, greater ease and accuracy in applying a given force. www.indiandentalacademy.com
  39. 39. Working range and flexibilty  The distance a wire will bend elastically before permanent deformation occurs.  Measured in millimeter or other length units.  Flexibility is the measure of the amount at which the wire can be strained without undergoing plastic deformation. www.indiandentalacademy.com
  40. 40. Formability  The ability to bend wires into desired configurations as loops, coils and stops without fracturing the wire. www.indiandentalacademy.com
  41. 41. Stress relaxation  When a wire has been deformed and held in a fixed position the stress may diminish with time even though the total strain may remain constant. www.indiandentalacademy.com
  42. 42. Biohostability  The ease with which a material will culture bacteria, spores or viruses. www.indiandentalacademy.com
  43. 43. Ideal requirements of Orthodontic arch wires  Esthetic  Good range  Tough  Poor biohost  Good springback  Low friction  Weldable  Springy  Formable  Biocompatible  Resilient  Strong www.indiandentalacademy.com
  44. 44. Variation in diameter and length of orthodontic wires STIFFNESS STRENGTH RANGE x MODULUS OF ELASTICITY X resiliency X elastic limit x 1/L3 X 1/length X L2 x d4 X d3 X 1/ d x1/ No of coils X no of coils X 1/coil dia3 X 1/ coil dia X coil dia 2 www.indiandentalacademy.com
  45. 45. Australian Orthodontic arch wires  Claude Arthur J Wilcock developed an orthodontic arch wire for use in the Beg technique.  Unique characteristics different from usual orthodontic arch wires.  They are ultra high tensile austenitic stainless steel arch wires.  The wires are highly resilient.  When arch wire bends are incorporated and pinned to the teeth the stress generated within the wire which generate a light force which is continuous in nature.  Wire is resistant to permanent deformation and maintains it’s activation for maximum control of anchorage. www.indiandentalacademy.com
  46. 46. Australian Orthodontic arch wires  Manufacture:  Spinner straightening and pulse straightening.  Spinner straightening: The wire is passed through bronze rollers.  Pulse straightening: The wire is pulsed in a special machine which permits high tensile wires to be straightened. www.indiandentalacademy.com
  47. 47. Australian Orthodontic arch wires  Types:  Regular  Regular plus  Special  Special plus  Extra special plus  Supreme  Premium plus www.indiandentalacademy.com
  48. 48. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com

×