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1. ORTHODONTIC
WIRES
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

2. 




ORTHODONTICS
WIRES
Introduction
Terminologies
Classification of wires
Mechanical properties & clinical
application of wires
Ideal orthodontic alloy

3. 

Individual wires
-Gold wires
-Cobalt chromium wires (Elgiloy)
-Stainless steel wires
-Australian heat treated wires
-Nickel Titanium wires (NITI wires)
-Beta Titanium wires (TMA wires)
-Alpha Titanium wires
-Copper Niti wires
-Ceramic wires
Conclusion

4. Introduction
Those who are enamored of
practice without science are like a sailor who
goes into a ship without rudder or compass
& hence has no certainty where he is going.
Practice should always be based upon a
secured knowledge of theory.

5. Terminolgies
Mechanics:
As an area of study with in the physical sciences, is
concerned with the state of rest or motion of bodies,
subjected to forces.
 Force:
Force is defined as an act upon a body that changes or
tends to change the state of rest or the motion of that
body.
 Stress:
Displacing force measured across a given area, it is
known as stress (force per unit area, pound/sq. inch)
 Strain:
The change in dimension is called a strain change in
length / unit length.
Strain could be
1) Plastic
2) Elastic

6. 



Tensile stress:
A tensile stress is caused by a load that tends to stretch
or elongate a body. It is always accompanied by a
tensile strain.
Compressive stress:
If a body is placed under a load that tends to compress
or shorten it. the internal resistance to such a load in
called compressive stress. It is accompanied by a
compressive strain.
Shear stress:
A stress that tends to resist a twisting motion or a sliding
of one portion of a body over another, is called as shear
or shearing stress.
The elastic limit of a material is the greatest stress to
which a material can be subjected, such that it will return
to its original dimensions when the forces are released.

7. 
Proportional limit:
If the wire is loaded in tension in small increments until the
wire ruptures, without removal of the load each time and if
each stress is plotted on a vertical coordinate and the
corresponding strain is plotted on the horizontal coordinate
a curve is obtained.

Hook’s law:
The stress is directly proportional to the strain in elastic
deformation.

Yield strength:
The yield strength is the stress required to produce the
particular offset chosen (plastic strain).

8. 
Modulus of elasticity:
If any stress value is equal to or less than the
proportional limit is divided by its corresponding strain
value, a constant of proportionality will result, this
constant of proportionality is known as the modulus of
elasticity or Young’s modulus.

The maximal flexibility is defined as the strain that
occurs when the material is stressed to its proportional
limit.

9. Stress
Elastic Properties
Elastic Portion
Strain

10. Elastic Properties
Stress
Yield strength
0.1%
Proportional Limit
Elastic Limit
Strain

11. Stress
Elastic Properties
Ultimate Tensile
Strength
Fracture Point
Strain

12. Stress
Elastic Properties
Range
Springback
Strain

13. Stress
Elastic Properties
Resilience
Formability
Strain

14. Stress
Elastic Properties
Modulus of elasticity α Stiffness
Springiness α
1
Stiffness
Strain
.

15. Wire characteristics of clinical
relevance

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


Springback:
Stiffness:
Formability:
Resiliency:
Range:
Biocompatible & Environmentally stable.
Joinability:
Friction:

16. A rough idea can be obtained clinically as
well



Forming an arch wire with the thumb gives
an indication of the stiffness of the wire.
Flexing the wires between the fingers,
without deforming it, is a measure of
flexibility
Deflecting the ends of an archwire
between the thumb and finger gives a
measure of resiliency.

17. Effects of size & shape on
elastic properties

Effects of diameter or cross section
Strength --- d --- 2d=8
(2d/d)3
springiness --- d --- 2d=1/16 (d/2d)4
Range --- d --- 2d= ½
(d/2d)

18. Effects of length & attachment
Cantilever type
supported beam
If length is doubled
Strength: reduced by ½
Springiness: increased by 8
Increase by doubled.
Remains same.
Range: increased by 4 times Remains same.

19. Direction of loading

When a wire is bend so that it permanently
deforms & an increase in the bend is
desirable it should be done in the original
direction of bending & twisting. This is
term as the bauschinger effect.
Hence the operator should be sure of the
last bend made in the wire is in the same
direction as the bending produced during
its activation.

20. Fatigue & prevention of fatigue
failure
Cyclic loading at stress values well below those
determined in ultimate strength measurement
can produce about failure of a structure. This
type of failure is called fatigue.
Prevention:
1.prevent minute scratches.
2.Wire should not be marked or notched with file
during arch designing.
3.Smooth beaked pliers should be used.
4.Repeated bending at the same spot is to be
avoided.
5.Adjustment & bends to be avoided near high
stress areas & soldered joints.


21. Classification of wires

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According to material used
Gold archwires
Stainless steel archwires
Chrom-cobalt archwires
Nickel-Titanium archwires
 Martensitic
 Austenitic
 Superelastic
 Japanese NiTi
 Chinese NiTi
 Beta titanium – TMA
 Alpha NiTi
Copper NiTi
Ceramic coated/optiflex archwires

22. Classification according to cross
section



Rounded
Rounded
rectangular
Retangular

Co axial

Twisted

woven

23. Gold wires



 ADA specification
Precious metal alloy
was used before
no.7
1950’s due to its
Type I: High precious
stability.
metal containing
Wrought metal is
atleast 75% of Au &
used in modern
Pt
dentistry because
Type II: Low precious
gold in its pure state
metal containing
is very soft, malleable
atleast 65% of Au &
& ductile.
Pt
Not used today due to Composition: Au, Pt,
its low yield strength.
Pd, Ag, Cu, Ni, Zn

24. Cobalt chromium nickle alloy



First use as watch springs (Elgiloy) during
1950’s
Commercially available as Elgiloy, Rocky
mountain orthodontics, Azura &
Multiphase.
Composition: cobalt- 40%,chromium- 20%
nickle- 15%, molybdenum-7%,
manganese-2%, carbon- 0.5%,
beryllium-0.4%, iron-1.5%

25. Cobalt chromium nickle alloy

Heat treated before being supplied to the
user & are available in several degree of
hardness having colour coding
Soft:- Blue
Ductile:- Yellow
Semi resilient:- Green
Resilient:- Red
Heat treatment increases yield strength &
decreases ductility.

26. Cobalt chromium nickle alloy
Physical properties:
1. Tarnish & corrosion resistance is excellent.
2. Hardness, yield strength & tensile strength is
comparable to 18-8 stainless steel.
3. Ductility: greater in soft compared to 18-8.
lesser in hardened condition.
 Mechanical properties:
1. Greater resistance to fatigue & distortion.
2.Non heat treated wires have smaller spring back.
3.Have high modulus of elasticity so its deliver
forces more & faster movements occurs of
posterior teeth causing loss of anchorage.


27. Cobalt chromium nickel alloy
4.Have good formability & can be bent into many
configuration relatively easily.
5.Low fusing solder is recommended.
6.Frictional forces between brackets & wires is
comparable to stainless steel.

Recent Advances:
1. G & H wire company: can be heat treated in
bent areas & easily soldered without annealing.
having good ductility, strength, flexibility
resistance to fatigue & corrosion & have greater
spring back.

28. Stainless steel wires
Steels are iron based alloys that contain
less than 1.2% carbon.
 When 12 to 30 % chromium is added to
iron the alloy is called as stainless steel.
 Exist in 3 phases
1.Ferrite (Body centered cubic) structure.
This phase is stable upto 912° C
2.Austentic(Face centered cubic) structure.
This phase is stable between 912 ° to 1394
°C


29. Stainless steel wires
3.Martensite (Body centered tetragonal)
struture.
If the austenitic alloy is cooled very rapidly it
will undergo a spontaneous , diffusionless
transformation to a body centered
tetragonal structure called martensite. This
lattice is highly distorted & strained,
resulting in a very hard, strong, brittle alloy.

30. Stainless steel wires

Ferritic stainless steel:
- provides good corrosion resistance.
-low cost.
-has less strength.
-not hardenable by heat treatment.
-not readily work hardenable.
Hence, finds little application in dentistry.

31. Stainless steel wires

Martensitic stainless steel:
-high strength.
-can be heat treated.
- decrease corrosion resistance.
-decrease ductility.
Hence used for surgical & cutting
instrument.

32. Stainless steel wires

Austenitic stainless steel:
Most corrosion resistant of the stainless
steel.
composition: chromium -18%
nickel8%
carbon- 0.15%
AISI 302 is the basic type.
Type 304 has similar composition but
carbon content is limited to 0.08%,this is
the most commonly used type.

33. Stainless steel wires
Austenitic stainless steel is preferable to the
ferritic alloys because of:
-greater ductility & ability to undergo more cold
work without breaking.
-substantial strengthening during cold working.
-greater ease of welding.
- ability to fairly readily overcome sensitization
-comparative ease in forming.
-disadvantage is it annealing temperature
so low fusing silver solder should be used.


34. Australian heat treated arch wires


Outstanding properties or characteristics
of the Australian wire is its
-resiliency, springback after having
deflected.
Variation in the types of wires is made by
fluctuation in the rate at which the wire
passes the heat source.

35. Australian heat treated arch wires
Available in the following forms
forms
colour code
1Regular grade
White
2.Regular plus grade Green
3.Special grade
Black
4.Special plus
Orange
5.Extra special plus
Blue
6.Supreme
Blue


36. Australian heat treated arch wires



Regular grade: lowest grade & easiest to
bend. It is used for practice or forming
auxiliaries.
Regular plus grade: Relatively easy to
form ,more resilient than regular grade. Available
in sizes 0.014”, 0.016”, 0.018”, 0.020”
Special grade: Highly resilient yet can be
formed into intricate shapes with little danger of
breakage.0.016” is often used for starting arches
in many techniques. Available in sizes 0.014”,
0.016”, 0.018”, 0.020”

37. Australian heat treated arch wires




Special plus grade: used by experienced
operators. Hardness & resiliency of 0.016” size
are excellent for supporting anchorage.
Available in sizes 0.014”, 0.016”, 0.018”, 0.020”,
0.022”
Extra special plus grade: This grade is
unequaled in resilience. More difficult to bend &
subject to fracture. Wire breaks easily if not
bend properly, no margin for bending errors.
Available in size 0.016” only.

38. Australian heat treated arch wires


Supreme grade: Also called as premium
plus in Australia. Used only in treatment of
rotations, alignment & leveling.
Though supreme grade exceeds the yield
strength of extra special plus it is intended
for use in either short sections & where
sharp bends are not required.
Available in sizes 0.010”, 0.012” & 0.016”

39. Australian heat treated arch wires


Newer grades of Australian wires: During
last 2 decades, 3 more grades have been
introduced namely Premium, Premium
plus, & supreme ( P, P+ & S ) in an order
of increasing yield strength.
Properties: greater spring back, greater
resiliency, less formability, greater
resistance to permanent deformation,
more brittle than lower grades.
Premium:.008”,.009”,.010”,.011”,.012”,.014”,.016”
.018”,.020”

40. Australian heat treated arch wires
Premium plus: .
008”,.009”,.010”,.011”,.012”,.014”,.016”,.018”,
Supreme: .008”,.009”,.010”,.011”

41. Nickel Titanium Alloys



Nitinol was invented in the early 1960’s by
William F. Buehler, a research metallurgist
at the Naval ordinance.
Nitinol: Ni for Nickel and Ti for titanium
and nol for Naval ordnance laboratory.
Composition:
Nickel
– 54%
Titanium
– 44%
Cobalt
– 02%

42. Nickel Titanium Alloys
The wire has low stiffness in combination
with moderately high strength which leads
to large elastic deflection or working
range.
 The alloy has limited formability.
 Alloy can exist in various crystallographic
forms. At high temperature body centered
cubic lattice (BCC) referred to as the
austenitic phase..


43. Nickel Titanium Alloys
Appropriate cooling induces
transformation to a close packed
hexagonal martensitic lattice.
 This transition can also be induced by
stress.
 Austenitic NiTi is the high-temperature,
low stress form, and martensitic NiTi is
the low-temperature, high stress form.
 Transformation occurs by a twinning
process, which is reversible below the
elastic limit.


44. Nickel Titanium Alloys


This transition leads to two potential properties
shape memory, and super elasticity or
pseudoelasticity.
Shape memory:




Shape memory refers to the ability of the material to
‘remember’ its original shape after being plastically
deformed while in the martensitic form.
Hence wire is set into the desired shape and held
while undergoing a high temperature heat treatment
near 482 ° C.
Then cooled and formed into a second shape.
Subsequent heating through a lower transition
temperature i.e. near mouth temperature leads to
returning of the wire to its original shape.

45. Nickel Titanium Alloys

Inducing the austenitic to martensitic
transition by stress can produce
superelasticity a phenomenon – NiTi
wires. On a stress sufficient to induce the
phase transformation there is a significant
increase in strength referred to as
superelasticity which occurs due to a
volumetric change in crystal structure.

46. Nickel Titanium Alloys



At the completion of the phase transformation,
behavior reverts to conventional elastic and
plastic strain with increasing stress.
Unloading results in reverse transition and
recovery.
Therefore, NiTi alloy can be produced with either
austenitic or martenstic structure with varying
degrees of cold work and variations in transition
temperature.

47. Nickel Titanium Alloys



NiTi has low modulus value and larger
working range. Less formability and can
neither soldered nor welded.
Crimpable hooks and stops like cinchback
distal to molar buccal tube is recommended.
Cinchback is performed by flame annealing
which leads to making the wire dead soft and
it can be bent into the preferred configuration.
Dark blue colour indicates the desired
annealing temperature.

48. Nickel Titanium Alloys

Clinical application:






High springback, flexibility, low constant
forces ,shape memory and elasticity are the
important and advantageous properties for
clinical applications of NiTi.
Frictional forces are higher than stainless
steel and lower than those with beta-titanium.
Uses:
Crossbite correction
Uprightening impacted canines
Opening the bites

49. Beta-Titanium alloy
In 1960 a high temperature of titanium
alloy which above 1625 ° F rearranges
into a body centered cubic lattice ,referred
to as the beta phase, with the addition of
elements as molybdenum was developed.
 Composition:
Titanium- 79%
Molybdenum-11%
Zirconium-6%
Tin- 4%


50. Beta-Titanium alloy
Also called as TMA wires
 Mechanical properties
-low modulus of elasticity
- modulus of elasticity is twice that nitinol &
less than half that of stainless steel.
-greater spring back.
-good corrosion resistance.
- heat treatment is not recommended.
-as it is ductile hence loops & bends can
be given.


51. Alpha Titanium Arch Wire





It is the recent alloy in the family of
titanium alloy.
Composition:
Titanium
– 90%
Aluminum
– 6%
Vanadium
– 4%


Molecular structure is the alpha phase with a
closely packed hexagonal lattice.
It possesses fewer slip planes thereby this
wire is difficult to deform. Hence it is less
ductile than beta-titanium.

52. Alpha Titanium Arch Wire
 Clinical
significance:
Rectangular wires in the sizes of 0.022” x
0.018” (ribbon mode) or 0.020” x 0.020”
(square) are recommended by
Mollenhauer for the finishing stage.
Alpha titanium combination wire with an
anterior ribbon (0.022” x 0.018”) and
posterior round (0.018”) sections in
second stage of Begg treatment.

53. Copper-NiTi Arch wire



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
It was introduced by Rohit Sachdeva
and Suhio Mriyasaki in 1994 .
Composition:
wt %
Atomic wt %
Titanium
42.99
48.08
Nickel
49.87
45.39
Chromium
0.50
0.96
Copper
5.64
5.57

54. Copper-NiTi Arch wire




Properties:
Copper NiTi generates a more constant
force over long activation spans and very
small activations as compared to nickel
titanium alloys.
Copper NiTi more resistant to permanent
deformation compared to nickel titanium
alloys.
Exhibits better spring back characteristics.

55. 
The addition of copper combined with more
sophisticated manufacturing and thermal
processes make possible the fabrication of
four different copper NiTi archwires with
precise and consistent transformation
temperatures 150 ° C, 270 ° C, 380 ° C and
400 ° C. This enables the clinician to select
archwires on a case-specific basis.

56. Copper-NiTi Arch wire


Classification:
Depending on austenitic finish
temperatures they are classified into.
Type I Af
= 15 ° C
Type II Af
= 27 ° C
Type III Af
= 35 ° C
Type IV Af
= 40 ° C

57. Ceramic Arch Wires

Optiflex archwire:
Optiflex is a recent new orthodontic archwire
designed by Tallas . It combines unique
mechanical properties with a highly esthetic
appearance. It is made of clear optical fiber, it
comprises of three layers.
1.A silicon dioxide core that provides the force
for moving teeth.
2.A silicone resin middle layer that protects the
core from moisture and adds strength.
3. A strain resistant nylon outer layer that
prevents damage to the wire and further
increases its strength.

58. Ceramic Arch Wires
Properties:
 Shape: Round or Rectangular
 Has wide range of action
 Ability to apply light continuous forces
 Clinical application:
-Sharp bends to be avoided
-It is a highly resilient archwire that is
especially effective in the alignment of
crowded teeth.


59. Ceramic Arch Wires



Lee White Wire is tooth coloured, epoxycoated archwire that has superior wear
resistance and stability of six to eight
weeks.
A unique heat treatment bakes on the
epoxy coating and makes it possible to
offer a wide variety of sizes.
The preformed wires are designed in a
natural archform

60. Conclusion



Recent advances in the orthodontic wire
alloy has lead to a wide spectrum of wires
with varied properties.
Hence the orthodontist must make the
decision depending upon the clinical
situation as to which wire is optimum.
An adequate knowledge of the mechanical
properties and the clinical applications is a
must to aid in making the right decisions.

62. Effects of Length

64. Thank you
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