Benefits of Titanium in Dentistry

Titanium and its alloys
www.indiandentalacademy.com

• The unparalleled tissue tolerance and biocompatibility
of titanium have made it the leading metal for dental
implants.
• Titanium and titanium-based alloys have the greatest
corrosion resistance of any of the known metals
• Although stainless steel is highly corrosion-resistant,
it has been found to be attacked by artificial saliva
which has dissolved nickel and chromium from the
alloy.
• Most alloys used in orthodontics contain potentially
toxic nickel, chromium, and cobalt.
Introduction

• Nickel has produced more reported allergic reactions
than all the other metals combined. Women are
believed to be especially susceptible, because of
sensitization from nickel leaching from irregularities
in the surface coatings of costume jewelry.
• According to Hamula et al in JCO 1996, the
problems of nickel sensitivity, corrosion, and
inadequate retention of SS brackets has been solved
with the introduction of new, pure titanium bracket
(Rematitan).
• Its one-piece construction requires no brazing layer,
and thus it is solder- and nickel-free.

• A computer-aided laser (CAL) cutting process
generates micro- and macro-undercuts, making it
possible to design an “ideal” adhesive pattern for each
tooth.
• Sernetz et al in 1997 evaluated the qualities and
advantages of titanium brackets.
• The biocompatibility of these brackets is maintained
by preserving the integrated base made of a single
piece of pure titanium.
• Lesser stiffness of titanium compared to stainless steel
allows torque to be fully expressed without deforming
the bracket wings.

• Titanium brackets are made from a pure, medical-
grade titanium that has advantages in miniaturization
over stainless steel because of its greater strength
(made possible by special cold-working processes)
and its lower elastic modulus.
• Single-piece construction allows the lowest possible
bracket height, since clinical in-and-out depths remain
the same.
• This makes the miniaturized appliance even less
conspicuous.
• A low bracket profile can be helpful in assessing lip
balance during treatment, especially in cases of lip
insufficiency and protrusion.

• Many patients prefer the appearance of the silver-gray
titanium brackets over shiny, reflective stainless steel.
• Titanium also has low thermal conductivity, and thus
alleviates the sensitivity to extreme temperature changes
often experienced by patients wearing metal appliances.
• It imparts none of the metallic taste of stainless steel
brackets.
• Such brackets may provide an alternative to SS brackets
for those communities who are concerned with nickel
toxicity, since their tribologic properties are quite
comparable to the currently accepted standard, SS.

Composition
• A commercially pure (cp) medical grade 4 Ti
(designation DIN 17851-German standards) is used as
the basis for the manufacture of titanium brackets.
• Composition is
Titanium - over 99%
Iron - < 0.30%
Oxygen - < 0.35%
Nitrogen - < 0.35%
Carbon - 0.05%
Hydrogen - 0.06%

Surface characteristics
• The surface texture of the Ti brackets is much rougher
than that of the SS brackets.
• According to Harzer et al in Angle 2001, the surface
structure and the color of titanium and steel brackets are
very different.
• The surface of the rolled wings of titanium brackets is
very rough, and the biocompatibility of titanium supports
plaque adherence.
• These are the reasons for significantly more plaque
accumulation and a more marked change of color with
titanium brackets.
• The slots of titanium brackets are not as rough as the
wings because the slots are milled and not rolled.www.indiandentalacademy.com

• According to energy dispersive x-ray microanalysis
(EDX), the titanium brackets appeared to be
comprised solely of Ti.
• Ti is found to exist mostly in the oxidized form, TiO2
.
• Titanium is prone to fretting and galling, despite its
excellent resistance to corrosion at physiological
temperatures and its high specific strength.
• Nonetheless it has proven biocompatibility in medical
and dental applications.

Titanium and sliding mechanics
• Some clinicians have found titanium brackets to be
superior to stainless steel brackets in sliding mechanics.
An oxidation treatment of the titanium bracket, in
addition to creating chemical and mechanical passivity,
hardens the bracket slot.
• The smooth, Teflon-like surface of titanium is due to a
thin layer of titanium oxide and prevents direct contact
between the metallic atoms on the surfaces of the wire
and the bracket, thus reducing interatomic adhesion and
friction.
• Early testing of friction between stainless steel wires and
titanium brackets has shown a nearly 30% reduction in
friction compared to stainless steel brackets

• Kusy and whitley in AJO 1998 found that in the dry
state, both the SS brackets and Ti brackets are
comparable for SS wires.
• Ti brackets compare favorably against the conventional
SS bracket for all couples evaluated with SS, Ni-Ti, and
beta -Ti archwires.The Ti bracket displays an adhesive
effect for all couples when tested in the wet versus the
dry state at 34°C in the pasive configuration.
• In the active configuration, kusy and Grady in AJO
2000 found that as the force or angulation between the
bracket and archwire increases, the passive oxide layer
on titanium (Ti) brackets does not break down
• The passive oxide layers on Ti brackets provide a good
medium for sliding mechanics.

• Against SS archwires, the static and kinetic coefficients
of friction of SS and Ti brackets are comparable in both
the passive and active configuration, regardless of testing
under dry or wet conditions.
• By using Ti brackets, biocompatible archwire–bracket
couples may be chosen that have more favorable sliding
characteristics than other biocompatible ceramic
brackets. Thus, Ti brackets are a suitable substitute for
SS brackets in sliding mechanics
• Titanium brackets present superior structural dimensional
stability as a result of favorable material properties when
compared to SS brackets.

• Kapur and sinha in AJO 1999 found that Titanium
brackets have different frictional characteristics when
compared with stainless steel brackets using similar
wires. Stainless steel brackets showed higher static and
kinetic frictional force values as the wire size increased.
However, for the titanium brackets the frictional force
decreased as the wire size increased.
• The desirable mechanical properties of titanium allow
early engagement of a full size wire during treatment, it
allows the bracket to elastically deform for three-
dimensional control of tooth movement with rectangular
wires.

Titanium and corrosion
• Toumelin-Chemla et al tested the corrosive properties
of fluoride-containing toothpastes on titanium in vitro
and found substantial corrosion processes in the
fluoridated acidic media.
• Reclaru and Meyer suggested that fluoride ions are the
only ions acting on the protective layer of titanium and
causing localized pitting and crevice corrosion.
• The aggressiveness of the environment at pH 3 is such
that it is no longer possible to maintain passivation
zones, and titanium will, therefore, undergo a continuous
degradation.

conclusion
• In essence, titanium brackets are a suitable alternative
to conventional metal brackets in many aspects. Their
biocompatibility, absence of nickel, good corrosion
resistance, superior dimensional stability, comparable
frictional characteristics and decreased
conspicuousness along with low thermal conductivity
make these brackets a suitable alternative to
conventional S.S brackets specially in nickel sensitive
patients.

Titanium implants
• Implants are an excellent alternative to
traditional orthodontic anchorage
methodologies, and they are a necessity
when dental elements lack quantity or
quality, when extraoral devices are
impractical, or when noncompliance
during treatment is likely.
• The growing demand for orthodontic
treatment methods that require minimal
compliance, particularly by adults, and
the importance placed on esthetic
considerations by all patients have led to
the expansion of implant technology.

Indications
• Implants have been used to extrude impacted teeth, to
retract anterior teeth, for space closure and to correct
dental position in preprosthetic orthodontic treatment.
In addition, they have been applied in the treatment of
Class III malocclusion, anterior open bite, and dental
alignment, and as an aid to the retention of teeth with
insufficient bone support.
• These osseointegrated implants are usually used as
anchorage to assist orthodontic tooth movement.
Many different orthodontic osseointegrated anchorage
systems (OOAS) have been developed.

• Implants can be used in the following conditions:
1. as a source of anchorage alone ( indirect anchorage)
a. orthopedic anchorage
1. for maxillary expansion
2. headgear like effects (singer et al in
angle 2000 used implants placed in the
zygomatic buttress of the maxilla to protract
it in class III pts with maxillary
retrognathism)
b. dental anchorage
1. space closure
2. intrusion of teeth
a. of anteriors
b. of posteriors
3. for distalization
2. in conjunction with prosthetic rehabilitation (directwww.indiandentalacademy.com

Implant designs
Modified implant designs meant specifically for
orthodontic usage are
1. Onplants
2. Mini implants
3. skeletal anchorage system
4. The micro implants
5. The Aarhus implants

Materials used
• The material must be nontoxic and biocompatible, have
favorable mechanical properties, and be able to resist
stress and strain with proven effectiveness in clinical and
experimental studies.
• The materials commonly used for implants can be divided
into 3 categories:
– Biotolerant - stainless steel, chromium-cobalt alloy.
– Bioinert - titanium, carbon and
– Bioactive - vetroceramic apatite hydroxide, ceramic oxidized
aluminum.

Advantages of titanium
• Commercially pure titanium is the
material most often used in implantology.
• It consists of 99.5% titanium, and the
remaining 0.5% is other elements, such
as carbon, oxygen, nitrogen, and
hydrogen.
• titanium is considered an excellent
material
• Osseointegration is defined as a direct
structural and functional connection
between ordered living bone and the
surface of a load carrying implant
• no allergic or immunological reactions
• Mechanical characteristics -very light
weight, excellent resistance to traction
and breaking. www.indiandentalacademy.com

Fixture size and shape
• Implanted fixtures must meet the demands of
primary stability and effectively withstand
forces
• The maximum load that can be applied to the
fixture is proportional to the quantity of
osseointegration, making it dependent on the
surface area of osseoimplant-tissue contact.
Because implants are usually cylindrical, the
parameters that contribute to the contact surface
are length, diameter, and shape.
• Traditional dimensions 3-4 mm in diameter,
6-10 mm in length
• The shape most used is cylindrical or
cylindrical-conical (flared), with a smooth or
threaded surface

Onplants
• Introduced by Block anf Hoffman
in 1995
• It is in the form of a circular disc 8-
10 mm in diameter with provision
for abutments
• Made of Cp titanium and the
undersurface of the disc is coated
with hydroxyapatite
• Placed by a process called tunneling
in the posterior region of the palate

Skeletal Anchorage System
• Reported by Umemori and Sugawara
et al in AJO 1999
• for correction of skeletal open bites
by controlling the height of the
posterior dentoalveolar region
• Titanium miniplates might be used
as a source of stationary anchorage
• L-shaped miniplate is used fixed by
bone screws with the long arm
exposed to the oral cavity
• can provide a significant amount of
intrusion of the molars
• advantages: no preparation is
necessary, stable rigid anchorage is
ensured, and tooth movement is
possible shortly after implantation.www.indiandentalacademy.com

Orthosystem implants
• Orthosystem developed for anchorage
reinforcement of posterior teeth- reported
by Wehrbein et al in AJO 1999
• pure titanium 1-piece device with an
endosseous implant body, a transmucosal
neck section, and an abutment
• implant body has a selftapping thread
with a sandblasted, large grit, acidetched
surface
• inserted in the midsagittal palate for
anchorage reinforcement of posterior
teeth provided a means for reducing
patient compliance, reducing treatment
time, minimal anchor loss

Mini implants:
• These were introduced by Ryuzo
Kanomi in 1997. the implant is a
modified surgical screw and is
placed interdentally under local
anaesthesia.
The Aarhus implant system:
• This was introduced by Birte
Melsen.
Micro implants:
• These are small diameter implants
that can be placed interdentally
either buccally or palatally.
For intrusion and retraction
Micro implants
Mini implants

Anatomical sites
• Sites normally used are -alveolar bone in an agenesic or
extraction site, the palate in the median or paramedian
area, the retroincisive and retromolar site, the anterior
nasal spine, and the chin symphysis.
• Fixtures in an extraoral site, eg, the zygomatic bone
• Shigeru et al in 2000 - endosseous implants in
experimental animal as anchors for long term mesio-
distal movement of teeth.
• When used for orthodontic anchorage alone, a 1-phase
surgical procedure is preferred.
• Block and hoffman on onplants suggest 10-12 weeks of
healing time. Costa and Melsen suggest 4 weeks of
healing time

Nickel –titanium wires
Introduction
• Nickel-titanium alloys - introduced to the orthodontic
speciality by Andreasen and Hillman in 1971.
• The first nickel-titanium alloy, nitinol- based on the
original research of Buehler.
• The name nitinol was derived from the elements that make
up these alloys— "ni" for nickel, "ti" for titanium, and
"nol" for Naval Ordinance Laboratory, its place of origin.
• available as NiTi, Nitinol, Orthonol, Sentinol and Titanal
• advantageous properties of nitinol are the good springback
and flexibility
• high springback of nitinol is useful in circumstances that
require large deflections but low forces

Properties required in an orthodontic wire:
• It should be possible for the wire to be deflected over
long distances without permanent deformation; hence, a
large springback. This assures better control over tooth
movement and minimizes intervals for adjustment
• Low stiffness and produce light forces
• wire should be highly formable and should be formed
into complicated configurations, such as loops, without
fracture.
• Springback, or maximum elastic deflection, is related to
the ratio of YS/E.
• ability and ease of joining is an important clinical
parameter.
• The corrosion resistance of such joints and the wires
themselves should be satisfactory

Basic definitions
• Springback - also referred to as maximum elastic
deflection, maximum flexibility, range of activation,
range of deflection, or working range. Springback is
related to the ratio of yield strength to the modulus of
elasticity of the material (YS/E). It is a measure of how
far wire can be deflected without permanent deformation
• Stiffness or load deflection rate. It is the force
magnitude delivered and is proportional to the modulus
of elasticity. Low stiffness provides
(1) ability to apply lower forces,
(2) a more constant force over time, and
(3) greater ease and accuracy.

• Formability - ability to bend a wire into desired
configurations
• Modulus of resilience- This represents the work
available to move teeth.
• Biocompatibility and environmental stability-
includes resistance to corrosion and tissue tolerance to
elements in the wire.
• Joinability- The ability to attach auxiliaries to
orthodontic wires by welding or soldering
• Friction- The preferred material for moving a tooth
relative to the wire would be one that produces the
least amount of friction at the bracket/wire interface.

Stainless steel
• Austenitic stainless steel wires are the wires most
commonly used.
• contains approximately 18 percent chromium, 8 percent
nickel, and less than 0.20 percent carbon.
• high modulus necessitates the use of smaller-diameter
wires for alignment.
• decreased wire size results in poorer fit in the bracket
and loss of control.
• stainless steel has excellent formability.
• can be soldered, but the technique is moderately
demanding.
• has good corrosion resistance.

Cobalt chromium wires
• Composition is 40 percent cobalt, 20 percent chromium,
15 percent nickel, 7 percent molybdenum, and 16
percent iron.
• Has excellent formability
• Spring characteristics are similar to those of stainless
steel
• Can be soldered, but technique is demanding.
• Corrosion resistance of the wire is excellent.

Composition and manufacture of niti wires
• Nitinol is approximately 52 percent nickel, 45 percent
titanium, and 3 percent cobalt
• Solid-state solution hardening and cold working are the
basic strengthening mechanisms employed
• With proper heat treatment, the alloy demonstrates
significant changes in mechanical properties and
crystallographic arrangement.
• Have a stabilised martensitic phase formed by cold
welding, were the shape memory effect has been
supressed.
• Surface characteristics of the nickel-titanium alloy wires
are a result of its complex manufacturing process

• Nickel and titanium are most commonly manufactured
into the nickel-titanium alloy by the process of
vacuum induction melting or vacuum arc melting.
• Segregation is often a problem because there is a
relatively wide disparity of melting points.
• Several remelts are often needed to improve
homogeneity of the nickel-titanium alloy.
• Powders are then made of the alloy. The process of
hot isostatical pressing is used by the manufacturer to
form the powders into wires.
• Voids occur in areas where the powders are not
completely pressed together. The wires obtain their
final shape by the process of drawing or rolling. The
process of drawing or rolling may leave scratch marks
on the surface.

Classification of Ni-Ti wires
Kusy has classified nickel titanium wires as
1. Martensite stabilised alloys- do not possess shape memory or
superelasticity; processing creates a stable martensite
structure. These are the nonsuperelastic wires such as Nitinol.
2. Martensite active alloys- employ the thermoelastic effect for
shape memory. Oral environment raises the temperature of the
deformed archwire in the martensitic structure so that it
transforms to the austeinitic form. These are the shape
memory alloys such as Neo-Sentalloy and Copper Ni-Ti
3. Austenitic active alloys undergoes a stress induced
martensitic transformation (SIM) when activated. These alloys
are the superelastic wires that do not possess thermoelastic
shape memory at the temperature of the oral environment such
as Nitinol SE

Phase transformations
Two major NiTi phases are:
1. Austenitic Niti - a ordered BCC structure occurs at
high temperatures / low stress.
2.Martensitic NiTi- distorted monoclinic, triclinic or
hexagonal structure and forms at low temperatures / high
stress.
• shape memory effect is associated with a reversible
martensite to austenite transformation, which occurs
rapidly by crystallographic twinning
• When these alloys are subjected to high temperatures,
detwinning occurs, and the alloy reverts to the original
shape or size - shape memory effect.

• Some cases an intermediate R-phase having a
rhombohedral crystal structure may form during the
transformation process
• Since transformation occurs as a result of specific
crystallographic relationship between the two phases
-the rearrangement of atoms in the cells has been named
the Bain distortion
• Martensitic transformations do not occur at a particular
temperature, but rather within a range known as the
temperature transition range(TTR).
• TTR refers to the temperature range for the start and
completion of the transformation for that particular
structure

• Start of martensitic formation is designated as Ms
(martensite start) and the end as Mf (martensite
finish).
• The temperature at which Mf begins to decline and the
austenite begins to form is designated as As (austenite
start) and the temperature at which the whole structure
is austenitic is termed as Af (austenite finish).
• For stress induced martensite (SIM) formation, an
additional Md (martensite deformation) temperature is
defined as the highest temperature at which it is
possible to have martensite.

Martensitic transformation

Shape memory effect
• Buehler and Cross- shape-memory phenomenon was
related to the inherent capability of a nickel-titanium
alloy to alter its atomic bonding as a function of
temperature
• At a high temperature range the crystal structure of these
alloys is noted to be in an austenitic phase, although at a
lower temperature the structure is in a martensitic phase.
• In the martensitic phase, these alloys are said to be
ductile and readily capable of undergoing plastic
deformation. However, when heated through the TTR,
they revert back to the austenitic phase and regain their
original shapes

• Hurst and Nanda in AJO 1990 -specific TTR depends on
the chemical composition of the alloy and its processing
history. The TTR can be changed by altering the
proportion of nickel to titanium or by substituting cobalt
for nickel in the alloy.
• Memory configuration of the alloy must be first set in the
material by holding it in the desired shape while
annealing it at 450° F to 500° F for 10 minutes
• Through deflection and repeated temperature cycles, the
wire in the austenitic phase is able to “memorize” a
preformed shape, including specific orthodontic
archforms.
• Once a certain shape is set, the alloy can then be
plastically deformed at temperatures below its TTR. On
heating through the TTR, the original shape of the alloy
is restored. www.indiandentalacademy.com

• To obtain maximum shape recovery, the amount of plastic
deformation at temperatures below the TTR should be
limited to 7% or 8% of the original linear length.
• When an external force is applied, the deformation of NiTi
alloy is induced with martensitic transformation.
• The martensitic transformation can be reversed by heating
the alloy to return to the austenite phase and it is gradually
transformed by reversing back into the energy stable
condition.
• This means that the alloy can return to the previous shape.
This phenomenon is called shape memory.

Superelasticity / Pseudoelasticity
• Superelasticity is determined by the typical
crystallographic characteristics of NiTi.
• In response to temperature variations, the crystal
structure undergoes deformations
• The alloys essentially undergo a reorganization to meet
the new environmental conditions - a property that has
earned them the designation of “smart materials.”
• The transformation from the austenitic to the martensitic
phase (thermoelastic martensitic transformation) is
reversible and is called as pseudoshearing.

• On activation, the wire undergoes a transformation from
austenitic to martensitic form due to stress
• it is necessary to manufacture a wire in the austenitic
phase for the superelastic behaviour to occur
• original Nitinol alloy and other nonsuperelastic Ni Ti
wires have principally a work-hardened martensitic
structure
• clinically useful consequence of superelastic behavior -
variations in heat treatment can result in differing stress
levels to initiate phase transformations in the same
nickel-titanium wires.
• Japanese NiTi alloy is available in three different
superelastic force ranges of light, medium, and heavy for
individual wire sizes.www.indiandentalacademy.com

• The unique force deflection curve for austenitic Ni-Ti wire is
that its unloading curve differs from the loading curve –i.e
reversibility has an energy loss associated with it
-HYSTERESIS.
• The different loading and unloading curves produce the
remarkable effect the the force delivered by the austenitic
NiTi wire can be changed during clinical use by merely
releasing the wire and retying it.
• Deflection generates a local martensitic transformation and
produces stress-induced martensite (SIM).
• The highest temperature at which the martensite can form is
referred to as Md, and in austenitic alloys Md is usually
located above Af, allowing the SIM to form in the stressed
areas even if the rest of the wire remains austenitic.
• SIM is unstable, and if the specimen is maintained at oral
temperature it undergoes reverse transformation to the
austenitic phase as soon as the stress is removed.

• In orthodontic clinical applications, SIM forms where the
wire is tied to brackets on malaligned teeth so that the
wire becomes noticeably pliable in the deflected areas,
with seemingly permanent deformation
• In those areas, the wire will be superelastic until, after
tooth movement, a self-controlled reduction of the
deflection will restore the stiffer austenitic phase.
• Formation of SIM partially compensates for the lack of a
thermally induced martensite and contributes to the
superelastic behavior of austenitic NiTi alloys. This
property, termed pseudoelasticity, can be considered a
localized stress-related superelastic phenomenon. Only in
cases of very severe crowding will an austenitic alloy
behave superelastically.

Recycling of NiTi wires:
• Nitinol wires corrode when exposed to a chloride
environment, and this effect is potentiated by contact
with stainless steel.
• Mayhew and Kusy have demonstrated no appreciable
loss in properties of nitinol wires after as many as three
cycles of various forms of heat sterilization or chemical
disinfection, the effects of the oral environment on the
wire properties are still inconclusive.
• Retreived NiTi wires are characterised by the formation
of a proteinaceous biofilm, the organic constituents of
which are mainly alcohol, amides and carbonate.
Delamination, pitting and crevice corrosion defects as
well as decreased grain size were found.

Friction and NiTi:
• Stannard in AJO 1986 -These wires are found to have
moderate friction which is greater than stainless steel
but lesser than beta titanium.
• Prososki AJO 1990- Elgiloy and NiTi wires were found
to have comparable friction and this was lesser than beta
titanium and stainless steel. Findings on resistance to
corrosion of nitinol wires have been inconsistent.
• Sarkar, and Foster have noted that corrosion does not
affect flexural properties of nitinol wires, some reports
indicate an increase in permanent deformation and a
decrease in elasticity caused by corrosion or the
cumulative effects of cold-working

Clinical usage
• Most advantageous properties of nitinol -good springback
and flexibility, which allow for large elastic deflections
• The high springback of nitinol is useful in circumstances
that require large deflections but low forces
• nitinol has greater springback and a larger recoverable
energy than stainless steel or beta-titanium wires
• This results in increased clinical efficiency of nitinol wires
since fewer arch wire changes or activations are required.
• for a given amount of activation, wires made of titanium
alloys produce more constant forces on teeth than stainless
steel wires. A distinct advantage of nitinol is realized when
a rectangular wire is inserted early in treatment. This
accomplishes simultaneous leveling, torquing, and
correction of rotations.

• Andreasen and Morrow - fewer arch wire changes,
less chairside time, reduction in time required to
accomplish rotations and leveling, and less patient
discomfort.
• The poor formability of these wires implies that they
are best suited for preadjusted systems.
• Any first-, second-, and third-order bends have to be
overprescribed to obtain the desired permanent bend.
• Nitinol fractures readily when bent over a sharp
edge.In addition, bending also adversely affects the
springback property of this wire.
• The bending of loops and stops in nitinol is therefore
not recommended.

• Since hooks cannot be bent or attached to nitinol,
crimpable hooks and stops are recommended for use.
• Cinch-backs distal to molar buccal tubes can be
obtained by resistance or flame-annealing the end of
the wire. This makes the wire dead soft and it can be
bent into the preferred configuration.
• A dark blue color indicates the desired annealing
temperature. Care should be taken not to overheat the
wire because this makes it brittle

Beta titanium wires
• Introduced BY BURSTONE AND GOLDBERG
• Commercial name – TMA (Titanium Molybdenum Alloy)
• Nitinol, has excellent springback characteristics and a
low stiffness. unfortunately, its has low formability
which limits its application in conditions where
considerable bending of an appliance is required.
• At temperatures above 1,625° F pure titanium rearranges
into a body-centered cubic (BCC) lattice, referred to as
the ''beta" phase.
• With the addition of such elements as molybdenum or
columbium, a titanium-based alloy can maintain its beta
structure even when cooled to room temperature. Such
alloys are referred to as beta-stabilized titaniums.

Composition
• It is composed of
Titanium – 77.8 %
Molybdenum – 11.3 %
Zirconium – 6.6 %
Tin – 4.3 %
• A clinical advantage of β - titanium is its excellent
formability which is due to the BCC structure of beta
stabilised titaniums
• The addition of molybdenum to the alloy composition
stabilises the high temperature BCC β - phase of
polymeric titanium at room temperature.
• Zirconium and zinc - contribute to increased strength and
hardness. www.indiandentalacademy.com

Properties of β - titanium
∀ β - titanium wires have improved springback which
markedly increases their working range
• Excellent formability
• High ductility - dislocation movement of the different
slip systems in the BCC crystal structure
• Wire has a relatively rough surface due to adherence or
cold welding
• Only wire that possesses the property of true weldability
• Absence of nickel makes it more biocompatible and
hence these wires can used in nickel sensitive patients.
• Excellent corrosion resistance and biocompatibility due
to the presence of a thin, adherent passivating surface
layer of titanium oxide.

Friction and β - titanium
• Kusy et al ( AJO 1990) and several other authors - Beta
titanium archwires produce highest friction owing to
substantial cold welding or mechanical abrasion.
• The surface of the titanium wire can become cold
welded to the S.S bracket, making sliding space closure
difficult
• Ion-implantation - alters the surface composition of a
wire. Implantation of nitrogen ions into the surface of
this wire causes surface hardening and can decrease
frictional force by as much as 70%.
• ion-implantation process tends to increase stress fatigue,
hardness, and wear regardless of the composition of the
material www.indiandentalacademy.com

• Reduction in friction is significant only when both the
wire and the opposing surface are ion implanted.
• Katherine Kula and proffit in AJO 1998 concluded that
there was no significant difference when ion implanted
TMA wire was compared to unimplanted TMA wire in
sliding mechanics clinically.
• Ion implantation takes place in vacuum and involves the
implantation of oxygen and nitrogen onto the TMA wires
• These ions penetrate the wire surface by reacting with the
tin in TMA to change the surface and immediate sub-
surface of the material
• This layer is very hard and creates considerable
compressive forces. These forces improve the fatigue
resistance and ductility while reducing the co-efficient of
friction roughly to that of steel.

Clinical application
• Due to its unique and balanced properties, beta titanium wire
can be used in a number of clinical applications.
• For a given cross section, it can be deflected approximately
twice as far as stainless steel wire without permanent
deformation
• This allows a greater range of action for either initial tooth
alignment or finishing arches.
• Beta titanium is ductile, which allows for placement of tie-
back loops or complicated bends.
• High formability of β-titanium allows the fabrication of
closing loops with or without helices.
• Allows direct welding of auxiliaries to an arch wire without
reinforcement by soldering.

• Beta titanium wires are the most expensive of all the
orthodontic wire alloys but the increased cost is offset
by its combined advantageous properties. Beta
titanium not only offers an improvement in the
properties of presently designed orthodontic
appliances with its increased springback, reduced
force magnitudes, good ductility, and weldability, but
its excellent balance of properties should permit the
design of future appliances which deliver superior
force systems with simplified configuration.

Important properties of orthodontic
wire alloys
Property Stainless
steel
Cobalt
chromium
β - titanium
TMA
Nickel -
titanium
1. Cost Low Low High High
2. Force delivery High High Intermediate Low
3. Springback Low Low Intermediate High
4.Formability Excellent Excellent Excellent Poor
5. Ease of
joining
Welded joints
must be
reinforced with
solder
Welded joints
must be reinforced
with solder
Only wire that
has true
weldability
Cannot be
soldered or
welded
6. Friction Low Low High High
7. Biocompatibility Some Some None some

Chinese Ni Ti wire
• Introduced by Dr. Tien Cheng and studied by Burstone,
Qin, and Morton
• The parent phase is austenite which yields mechanical
properties that differ significantly from nitinol wire.
• Has much lower transition temperature than nitinol wire.
Mechanical properties
• Springback has 1.4 times the springback of nitinol wire
and 4.6 times the springback of stainless steel wire.
• average stiffness of Chinese NiTi wire is 73% that of
stainless steel wire and 36% that of nitinol wire

• Change in stiffness among different activations is
related to a clinically interesting finding - the magnitude
of force increases if a wire is retied into a bracket
Clinical significance
• Chinese NiTi wire is applicable in situations where
large deflections are required
• used in conditions were teeth are badly malaligned and
in appliances designed to deliver constant forces.
• there is a force difference if the appliance is left in place
throughout the deactivation or if it is removed and
retied. If the force levels have dropped too low for a
given type of tooth movement, then the simple act of
untying and retying can increase the magnitude of the
force.

Japanese Ni-Ti wires
• 1978- Japanese NiTi alloy, possesses all three properties
- excellent springback, shape memory, and super-
elasticity
• The unique feature was that the stress value remained
fairly constant during deformation and rebound
• Japanese NiTi alloy wire, yields a significantly higher
value of elastic modulus than the Nitinol wire.
• Japanese NiTi alloy wire possesses superelastic
property.
• Tensile testing - When the wire is stretched upto 2%,
stress – strain curve is proportional. But when the strain
was increased upto 8%, there was no change in stress.
This phenemenon is called as superelasticity.

• Wire is manufactured by a different process than Nitinol,
and demonstrates the superelastic property
• Elastic deformation occurs with the strain range of 0% to
2% in the austenite phase. The martensitic
transformation begins at the 2% strain level and the
transformation continues up to the 8% to 10% strain
level.
• When the martensitic transformation is completed, the
whole specimen is transformed into the martensitic
phase. Later, the martensitic transformation occurs again
in the direction of the austenite phase.
• The Japanese NiTi alloy wire possesses the property in
which the load becomes almost even when the deflection
was decreased. This is termed "super-elastic property"

Clinical application
• Classic NiTi alloy wire used in clinical orthodontics is the
work-hardened type wire called Nitinol. The Japanese NiTi
alloy wire possesses excellent springback property, shape
memory, and super-elasticity.
• Nitinol wire provides a light force and a lesser amount of
permanent deformation in comparison with stainless steel
and Co-Cr-Ni wires. super-elastic property provides a light
continuous force so that an effective physiologic tooth
movement can be delivered.
• Super-elasticity is especially desirable because it delivers a
relatively constant force for a long period of time, which is
considered a physiologically desirable force for tooth
movement

Copper Ni – Ti wires
• In 1994 copper Ni –Ti wires were introduced by the
ormco corporation.
• It is available in three temperature variants: 270
C, 350
C and 400
C corresponding to the austenite finish
temperatures
• Shape memory behaviour is reported to occur for each
variant at temperatures exceeding the specified
temperature.
• The addition of copper to nickel titanium enhances the
thermal- reactive properties of the wire, thereby
enabling the clinician to provide optimal forces for
consistent tooth movement.

Composition
They are composed of
Nickel – 44%
Titanium – 51%
Copper – less than 5%
Chromium – 0.2 – 0.3%
• Kusy - wire contains nominally 5-6 wt% of copper and 0.2-
0.3 % of chromium.
• The 270
C variant contains 0.5% of chromium to compensate
for the effect of copper in raising the Af above that of the oral
environment.
• The addition of copper to Ni-Ti not only modifies the shape
memory , but also increases the stability of transformation
and also helped to control hysteresis width and improved
corrosion resistance. superelastic wires contain copper (5–6
per cent) to increase strength and reduce energy loss.www.indiandentalacademy.com

Differences between Copper Ni-Ti and traditional
nickel titanium alloys:
• Copper Ni-Ti is more resistant to permanent deformation
and exhibits better springback.
• Copper Ni-Ti demonstrates a smaller loading force for
the same degree of deformation, making it possible to
engage severely malposed teeth with less patient
discomfort and potential for root resorption.
• Copper Ni-Ti exhibits a more constant force/deformation
relationship, providing superior consistency from
archwire to archwire.
• As copper is an efficient conductor of heat, Copper Ni-
Ti demonstrates consistent transformation temperatures
that ensure consistency of force. This equates to
consistent effectiveness in moving teeth.www.indiandentalacademy.com

Phase transformation
• Differential scanning calorimetry curves demonstrate
that the 27°C coppet Ni-Ti wire contains a single peak
both on heating and cooling.
• This indicates a direct transformation from martensite to
austenite on heating and from austenite to martensite on
cooling without an intermediate R phase.
• The 35°C and 40°Copper Ni-Ti wire alloys exhibit two
overlapping peaks on heating, corresponding to
transformation from martensite to R-phase followed by
transformation from R-phase to austenite

Uses of copper Ni - Ti wires
• 27°C Copper Ni-Ti generates forces in the high range
of physiological force limits and produces constant
unloading forces that can result in rapid tooth
movement. Engagement force is lower than with other
superelastic wires. This variant would be useful in
mouth breathers.
• 35°C Copper Ni-Ti generates mid-range constant force
levels when the wire reaches mouth temperature. Early
ligation is easier with full-size archwires due to the
lower loading forces. When earlier engagement of full-
size wires and sustained unloading forces at body
temperature are desired, 35°C Copper Ni-Ti is the
ideal wire. This variant is activated at normal body
temperature. www.indiandentalacademy.com

• 40°C Copper Ni-Ti provides intermittent forces that are
activated when the mouth temperature exceeds 40°C. It is
useful as an initial wire and can be used to engage severely
malaligned teeth (such as high cuspids) without creating
damaging or painful levels of force or unwanted side
effects. It is also the wire of choice for patients scheduled
for long intervals between visits when control of tooth
movement is a concern. This variant would provide
activation only after consuming hot food and beverages.
Advantages of copper Ni – Ti wires:
1. a more constant force delivery on a larger field of
activation
2. a better resistance to permanent deformation
3. slower drop of the deactivation force (less hysteresis

Heat activated wires
• A Martensitic wire, Heat Activated Titanium wires exhibit
excellent shape memory and superelastic characteristics.
• It transforms to its Austenitic state at 35° C, delivering a very
gentle continuous force. Because it is soft and pliable at room
temperature, it can be easily engaged to even the most
severely misaligned teeth.
• Nitinol Heat-Activated is a thermally activated super-elastic
archwire. It is the easiest of Nitinol wires to engage, and it
delivers light continuous forces that effectively move teeth
with minimal discomfort to the patient.
• Can be cooled or chilled resulting in a softer, more pliable
wire for easy engagement
• Provides light continuous forces
• Force activation at 27° C

• Thermoelastic alloys exhibit a thermally induced
shape/memory effect whereby they undergo structural
changes when heated through a transitional temperature
range (TTR) (Kusy, 1997).
• At room temperature the alloy is soft and easily ligated
to badly displaced teeth. At mouth temperature the ratio
of austenite increases and along with it the stiffness of
the wire, so that it more readily attempts to regain the
original archform (Bishara et al., 1995).
• The extent of this effect depends upon the TTR, which
can be set specifically by modifying the composition of
the alloy or by appropriate heat treatment during
manufacture (Buehler and Cross).

Alpha titanium wires
The composition of α- titanium is
Titanium – 90 %
Aluminium – 6%
Vanadium – 4%
• The alloy is different in that its molecular structure
resembles a closely packed hexagonal lattice as against
the BCC lattice of beta titanium.
• The hexagonal lattice possesses fewer slip planes. Slip
planes are planes in a crystal that glide past one another
during deformation. The more the slip planes, the easier
it is to deform the material. BCC structure has two slip
planes while HCP lattice has only one slip plane. Thus
the near α- phase titanium alloy is less ductile than
TMA.

Timolium wires
• New entry into the arena of titanium – based alloys.
• alloy with titanium, aluminium and vanadium as its
components.
• This alloy has a smooth surface texture, less friction at
the archwire –bracket interface, and better strength than
existing titanium based alloys.
• Vinod Krishnan et al (Angle 2004) -tensile evaluation
of the weld joint was beta titanium > stainless steel >
timolium.
• Weld surface of timolium exhibited a smooth and
symmetrical flow of the alloy, less surface distortions,
and an intact weld surface. Timolium with proper flow
of weld flash uniformly on both sides, had better surface
properties on surface evaluation.

Titanium Niobium wires
• This alloy has low spring back (equivalent to stainless
steel) and is much less stiffer than TMA.
• It is useful when a highly formable wire with low forces
in small activations is required.
• Titanium Niobium is an innovative archwire designed for
precision, tooth-to-tooth finishing.
• At 80% of the stiffness of TMA, it is perfect for holding
bends, yet light enough not to override the arch-to-arch
relationship. It is recommended for use with finishing
elastics and even though it feels soft and pliable, it
possesses a resiliency after bending that is equal to
stainless steel.

Nitinol total control
• IN 1988 Miura demonstrated the use of electrical
resistance heat treatment to introduce permanent bends
in their NiTi wires. The technique requires special pliers
attached to an electric power supply. This helps in
imparting bends without affecting superelasticity.
• A new pseudo super elastic NiTi alloy Nitinol total
control accepts specific 1st
, 2nd and 3rd
order bends while
maintaining its desirable super elastic properties. NTC
combines super elasticity with light continuos forces
over a desired treatment range with bendability required
to account for variations in tooth morphology arch form
and bracket prescription.

Supercable
• Hanson combined the mechanical advantage of multistranded
cables with material properties of super elastic wires to create a
super elastic NiTi Coaxial wire. This wire called super cable
comprises of 7 individual strand woven together to maximize
flexibility and minimize force delivery.
1. Elimination of archwire bending.
2. More effective and efficient control of rotations, tipping and
levelling mechanics with an 0.018'' arch wire at the
beginning of the treatment.
3. Flexibility and ease of engagement regardless of crowding
4. A light continuous force delivery
5. Minimal patient discomfort and fewer visits due to longer
arch wire activation.

Benefits of Titanium in Dentistry

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