stainless steel is very important material in dentistry and orthodontics.In present ppt this alloy orthodontic wires discussed in detail .

2. Orthodontic Wires
Stainless Steel
AND

3. Stainless Steel
 Ferrous alloy with a minimum of 10.5% chromium content.
 High resistance to oxidation , corrosion and staining.
 Fire and heat resistance.
 Low maintenance.
 Relative inexpense ( eco – friendly )

4.  Aesthetic appearance.
 100% recyclable.
Environmentally friendly.
Hygienic qualities ( Hospitals , Kitchens , … ).
Ease of fabrication.
Stainless Steel

5. Chrysler Building

8. Stainless Steel
There are :
five different metallurgical structures
( or classes ) of stainless steel ,
each has different characteristic and has
been created for different application.

9. Austenitic Stainless steel
Most widely used category of stainless steel.
 Low carbon ( 0.08% max. ).
 High ductility and toughness.
 Cannot be hardened by heat treatment.
 Non magnetic.
 Excellent corrosion resistance.
 15 – 30 % chromium.
 6 – 20 % nickle.
 Sometimes called 18 – 8.

10. Ferritic Stainless Steel
 Carbon levels are low.
 Non – hardenable by heat treatment.
 Magnetic.

11. Martensitic Stainless Steel
 Hardenable Stainless steel.
 High carbon level ( 0.15 to 1.2 % ).
 Heat treated to high hardness levels.
 Needle like microstructure.

12. Duplex Stainless Steel
 Low carbon ( below 0.03 % ).
Combination of both Austenitic and
Ferritic structures.
 Magnetic.

13. Precipitation Hardening Steels
 Low carbon ( 0.09 max. ) .
 Ease of fabrication.

14. Stainless steel :
Softened by Annealing
Hardened by cold working

15. Dead Wire
Fully or partially annealed
stainless steel wires
are soft and highly formable.

16. Heat Treatment
Above room temperature
Below solidus temperature

17. Heat Treatment:
Harden a metal
Soften a metal
Change its grain size , or corrosion resistance.

19. Grain boundaries

20. Slip

21. Fatigue Failure

22. INTER GRAIN CRACK

23. ORTHODONTIC WIRES:
• Stainless steel
• Cobalt Chromium
• Beta Titanium
• Nickel Titanium
• Glass Optiflex
• Fiber reinforced composite

24. FACTORS TO BE
CONSIDERED WHEN
SELECTING THE WIRE:
• Amount of force delivery that is desired
• Formability
• Soldering or welding capability
• Biocompatibility
• Corrosion resistance
• Cost of the wire

26. STAINLESS STEEL WIRES:
• High stiffness
• Easily adjusted
• Low friction
• Can be welded or soldered
• Cheap

27. STAINLESS STEEL
• Has good Cost, formability, and welding capability.
• 18-8 SS (18% Cr,8% Ni)
• Sometimes has some biocompatibility problem.
• Cold-working of these wires cause increase of yield strength from
275 to 1100 Mpa.
• Heat treatment on 400-500 C is recommended to remove the
internal stress of the wire to prevent the premature breakage.
• Heat treatment also increase the elastic limit & the hardness.
• On spot welding cause melting of wire on the joint which may cause
breakage of wire.

28. COBALT CHROMIUM –NICKEL WIRE
• Commercial name is Elgiloy Blue
• There is 4 colors of these wires: Blue-yellow-Green-Red
• Corrosion resistance is due to Cr layer of these wire.
• It’s a very formable wire then after heat treatment become harder.
• Heat treatment increase stiffness & load deflection rate & yield
strength
• Its Modulus of Elasticity is more than of SS wire.
• It’s a very good wire for making Quad-helix appliance

29. NITI WIRE
• Niti is a biocompatible wire
• There is Tio2 surface film layer to prevent corrosion
• Disadvantage : high cost, not weldable & solderable
• Niti wire has a very rough surface so it create high friction

31. NITI WIRE
• It is biocompatible
• It has 2 phase: Austenitic Niti & Martensitic Niti
• Austenitic Niti: Has an ordered BCC that occurred at higher
temperature
• Martensitic Niti: it has 3 form structure; Monoclinic, Triclinic,
Hexagonal
• Its shape memory property will occur when there is phase changes
from Austenitic to Martensitic phase

32. NITI WIRE
• TTR( Transforming Temperature Range): temperature that occurs at
the beginning and finishing of transformation phase.

33. B-TITANIUM WIRE (TMA)
• It is Titanium -Molybdenum alloy.
• Its Elastic Modulus is 40% of SS wire
• It’s a good wire for making auxiliary spring wires
• It has very good formability
• It has a high welding capability
• It’s the most expensive of all orthodontic wires

34. B-TITANIUM WIRE (TMA)
• It has a good proper intermediate force delivery
• It is a good wire for making axillary springs
• Not contain Nickel( no allergic reaction)
• Excellent corrosion resistance & good biocompatibility
• It has rough surface so increase the friction on sliding
mechanics
• With ion-implantation can decrease the frictional resistance

35. STIFFNESS
S.S.
Stress
Strain
NiTi
Cr.co
TMA

36. CLINICAL CONSIDERATION
• There is NO ideal wire for all stages of treatment.
• Stainless Steel and Blue elgiloy wires have very polished surfaces that
create less friction.
• SS and elgiloy has Nickel content so it might create some form of
allergy.
• TMA is a expensive wire.
• TMA has very good formability.