ortho wires part iii

(Continued)

Dr.Kishor Bagalkot

Manufacture: AISI ,specially for orthodontic purposes

Various steps –

1. Melting

2. Ingot Formation

3. Rolling

4. Drawing

MANUFACTURE

• Melting• Various metals of the alloy are melted

• Proportion influences the properties

• Ingot formation• Molten alloy into mold.

• Non uniform chunk of metal

• Porosities and slag.

• Grains seen in the ingot – control of mechanical properties

Steps

• Porosities due to dissolved gases (produced / trapped)

• Vacuum voids due to shrinking of late cooling interior.

• Important to control microstructure at this stage – basis

of its phy properties and mechanical performance

Ingot formation

Rolling –

• First mechanical process.

• Ingot reduced to thinner bars

• Finally form a wire

• Different wires from the same batch, differ in

properties

Steps

• Retain their property even after rolling

• Shape & arrangement altered

• Grains get elongated, defects get rearranged

• Work hardening – structure locked up.

• Wires start to crack if rolling continued

• Annealing is done- mobile

• Cooling – structure resembles original ingot, uniform

Rolling

Drawing

• More precise

• Ingot final size.

• Wire pulled through small hole in a die

• Progressively smaller diameter-uniform squeezing.

• Same pressure all around, instead of from 2 opposite

sides.

Steps

• Series of dies

• Annealing at regular intervals.

• Exact number of drafts and annealing cycles

depends on the alloy (gold <carbon steel<stainless

steel)

Drawing

Various alloys :

Gold

Stainless steel

Co-cr

Late 70-80’s Nitinol and TMA

Variable cross section approach.

Demand for the appliance system.

• Load deflection rate.

• Resistant to permanent deformation.

• Large range of action.

Variable modulus concept.

Variable transformation temperature orthodontics

Orthodontic Wires.

Titanium

Nickel-titanium alloy(NiTi)

• Nitinol

• Chinese NiTi

• Japanese NiTi

• Copper NiTi

Other Newer materials.

TITANIUM

Titanium was discovered by GREGOR.

(England 1790)

Biomedical material in US military industry.

BOTHE et al implanted titanium in lab Animals.

(1940)

A light weight metal.

Atomic weight – 47.9.

Non magnetic.

TITANIUM

• Corrosion resistant

• Biocompatibility

• High strength

• Ductility

TITANIUM

At room temp, Ti - difficult to deform. Alpha phase – Hexagonal unit cells

TITANIUM

At temp, > 16200F or 8820C - stable & easier to process.

Beta phase – Body centered cubic cells

TITANIUM

Beta phase – Body centered cubic cells

• Beta II or Ormco’s TMA

- Ti - 11.5 Mo - 6 Zr - 4 Sn

• Titanium Niobium

- Ti - 13 Nb - 13 Zr

Alloys with both phases

• Ti - 5 Al - 2.5Fe

• Ti - 6 Al - 4V

TITANIUM

SUPERIOR CORROSION RESISTANCE

• Tio2 - Ti affinity - friction.

Titanium is not esthetic

• Laser aided depositions

• Implantation of nitrogen

• IONGUARD

BETA - TITANIUM

Beta titanium was introduced by Dr. CHARLES

BURSTONE and JON GOLDBERG in the university of

CONNECTICUT ( Early 1980s )

Composition

Titanium - 73.5%

Molybdenum - 11.5%

Zirconium - 6%

Tin - 4.5 %

BETA – TITANIUM(AJO Feb. 1980; Burstone and Goldberg)

- Titanium based alloy + molybdenum or columbium.

Beta stabilized titaniums

Yield strength - 1,70,000 p.s.i

Modulus of elasticity - 9,400.000 p.s.i (2 NiTi, ½ St St)

YS/E - 1.8 X 10-2 (St St - 1.1 x 10-2)

BETA - TITANIUM

TEST FOR SPRING BACK TINIUS OLSEN STIFFNESS TESTER

¼ wire - 60º - 0.017’’/0.025’’

A. Straight wires

B. Wires with 35º bend

C. Wires which are overbent to 90º and then

bent back to 35º

Comparison of spring back

MODE

STAINLESS STEEL

BETA TITANIUM

PERCENT INCREASE

A 16.0 32.8 105%

B 16.5

31.3 90%

C 17.5 37.3 113%

BETA - TITANIUM

ADVANTAGES:

• Low stiffness

• Good formability

• High spring back

• Weldable

• Ductile

• Corrosion resistance

BETA-TITANIUM

DISADVANTAGES

• High coefficient of friction.

• Esthetics.

BETA - TITANIUM

Clinical Applications

Ideal edgewise arches

- Deflected twice than SS

- Range of action Initial tooth alignment or

Finishing arches

- Forces - 0.4 of SS

Eg : 0.018 x 0.025 TMA = 0.014 x 0.020 SS

- more gentle delivery of forces.

BETA - TITANIUM



- Full bracket engagement - 3rd order control.

- Ductility - Tie back loops or complicated bends.

BETA - TITANIUM



- Ductility - Tie back loops or complicated bends.

- 0.018 x .025 in .022.

BETA - TITANIUM

LOOPS

‘T’ Vertical

Helical

‘L’ loop

BETA TITANIUM

OPUS LOOP-0.017’’/0.025’’

BETA TITANIUM

Pendulum appliance – 0.032’’

BETA - TITANIUM

ROTATION INTRUSION

BETA-TITANIUM

K-SIR ARCH WIRE.0.019’’/0.025’’

BETA - TITANIUM

Canine root spring without helices

Closing loops

BETA - TITANIUM Direct welding of auxiliaries Helical finger spring.

BETA - TITANIUM

Welding of TMA wire (JCO 1987; Burstone)

What way different from St St

BETA - TITANIUM

Welding of TMA wire (JCO 1987; Burstone)

5 basic principles:

1. Proper positioning

2. Minimum voltage

3. Small contact area

4. Single short pulse

5. Pressure

ROCKY MOUNTAIN DIAL-A-WELD 506A

1. POSITIONING

• Set down of 80%

• 25 - 60 %

After welding, one wire has "set down" into the other.

Broad, flat electrodes

2. VOLTAGE Low Voltage - The parts may delaminate. Round wires - Simple to weld.

- Require lower voltages. High Voltage - Wire becomes brittle,

- Cracks

- Melting Overheating - 100% set down - Cracks

3. SMALLER CONTACT AREA

- Low voltage

- Higher localized heats

- Point contact

- ‘T’ joint

4. SINGLE PULSE

- Only one pulse

- Short duration.

5. PRESSURE

Improper Welding

Low voltage - The parts may delaminate

High voltage - Wire become brittle

Cracks

Melting

CLINICAL APPLICATIONS

PASSIVE APPLICATIONS:

- Stops

- Tie back hooks


ACTIVE APPLICATIONS

- Without loss of spring back


To gain space in the

anterior segment

CLINICAL IMPLICATIONS

ROTATIONAL

CORRECTION


TO INCLUDE SECOND MOLARS

Composite continuous arch with

posterior segment of .021"

x .025" TMA and anterior

segment of .016" round TMA to

facilitate alignment.

Composite continuous arch wire:

ALPHA TITANIUM (AJO March 1989; A.J.Wilcock)

Dr.Begg and Prof. Greenwood (1954)

0.018 Titanium wire

- Too soft

- Alpha stabilized by the addition of O2

ALPHA TITANIUM

TITANIUM - 90%

ALUMINIUM - 6%

VANADIUM - 4%

Close packed hexagonal lattice

ALPHA stabilizing elements–Aluminum, Gallium,

Germanium, Carbon, Oxygen and Nitrogen

‘NEAR ALPHA ALLOY’

- WILCOCK company

ALPHA – BETA PHASE

ALPHA TITANIUM

PROPERTIES: Heat treated to improve strength.

Satisfactory creep properties - Finishing & braking arches.

Wire becomes hard in the oral environment due to hydrogen absorption.

TITANIUM HYDRIDE Less ductile – one slip plane

Nickel free

Clinical Applications:

BEGG-II STAGE

• Combination wire

• 0.022x0.018-ant

• 0.018-post

• BRAKING MECH

Clinical Implications:

• BEGG-Finishing stage

• Rectangular wires

• 0.022’’x0.018-ribbon

• 0.020’’x0.020’’-square

TITANIUM-NIOBIUM

A new finishing wire alloy M. Dalstra et al

Nickel free Titanium alloy

(SYBRON DENTAL SPECIALITIES CALIFORNIA)

Ti - 74%

Nb - 13%

Zr - 13%

TITANIUM-NIOBIUM PROPERTIES

• Easy to bend, formability is less than TMA

• When lower forces are used than TMA

• Stiffness - ¼ of St St,

- ¾ of TMA

TITANIUM-NIOBIUM

PROPERTIES

• Load deflection rate is lower than TMA

• Yield strength is lower than St St

TITANIUM-NIOBIUM ADVANTAGES:

• Used when lower forces than TMA.

• No leaching of nickel

CLINICAL APPLICATIONS:

• Finishing wire with multiple bends

• Fixed retainers ( Biocompatible )

TIMOLIUM WIRES

- Research lab, TP orthodontics.

- New and improved titanium alloy.

Composition:

Ti - 82%

Mo - 15%

Nb - 3%

- Breakage resistance.

- Compressive strength.

TIMOLIUM WIRES

- Yield strength.

- Optimum delivered force.

- Friction

- Formability

BETA –III WIRES

Introduced by RAVINDRA NANDA• Bendable

• High force

• Low deflection rate

• Co-efficient of friction is more

• Nickel free titanium wire with memory

• Ideal for multilooping, cantilever, utility arches

- Finishing stages where tip & torque corrections done during initial stages.

A comparative study of metallurgical and working properties of two

new titanium based alloy wires (TiMolium and Beta III ) with the

earlier introduced titanium wires ( TMA ), and also alpha titanium

wires. - Jiku

Abraham

TiMolium - T.P.Orthodontics

Beta III - Ortho organizers

TMA - Ormco corp.

Alpha Titanium - A.J. WILLCOCK

Straight rectangular wires

GROUP I

- 4 wires in 16”x 22” dimension

GROUP II


GROUP III


Properties studied are

1. Yield, tensile strength & elastic modulus

2. Maximum load via 3-point bending test

3. Frictional resistance

4. Welding characteristics

5. Stress relaxation

6. Working range / spring back

7. Surface topography

8. Micro hardness

9. Elemental analysis

INSTRON MODEL NO.1193

Expr.setup for yield strength & ultimate tensile strength

Manufacturers claim that:

• Timolium is superior to TMA wires in the following:

1. Friction and surface smoothness.

2. Compressive strength.

3. Yield strength & breakage resistance.

• Beta III is bendable, high force low deflection, nickel free

arch wire with memory.

Results of the study showed that The coefficient of friction, surface smoothness, yield strength

& ultimate tensile strength of TiMolium was superior to that

of TMA.

However TMA has low load deflection rate and

high spring back than TiMolium .

Yield strength of Beta III was lower than TMA and TiMolium

Formability is good but resiliency is low.

CLINICAL APPLICATIONS OF THIS STUDY

1. Correction of crowding or alignment of teeth -

TMA > Beta III

2. Intrusion -

TMA shows a better stress relaxation

TMA > TiMolium .

3. Space closure

• Sliding mechanics -

TiMolium shows lowest values of coefficient of

friction in both static as well as kinetic friction.

TiMolium > Alpha titanium

• Frictionless mechanics –

Formability - Beta III > TMA > TiMolium

Resilience - TiMolium > TMA > Beta III

WELDABILITY

TiMolium > Beta III

FINISHING STAGES

Incomplete tip, torque correction.

Beta III > TMA > TiMolium.

NICKEL-TITANIUM ALLOYS

CONVENTIONAL - NITINOL

SUPERELASTIC

• Pseudoelastic-Japanese NiTi

• Thermo elastic-Cu NiTi.


2 forms of NiTi alloys

1. Martensite – Face centered (close packed

hexagonal).

2. Austenite – Body centered cubic/tetragonal

lattice.


Steel : temp. – FCC st - Austenite - C at the center of unit cell.

temp. – BCC st. – Ferritic – Fe at the center of unit cell.

rapid temp. – BCT st.– Martensite – C trapped in the unit cell.

Martensite – hard, strong, brittle.

NiTi : temp. –FCC st - Austenite

temp. - BCC st - Martensite

Martensite – Soft.

NICKEL-TITANIUM

TRANSITION TEMPERATURE RANGE

Martensitic transformation – Range.

TTR > body temp - Austenitic - Rigid.

TTR< body temp - Martensitic - Elastic.

Austenite wires - 2% of the strain range.

Martensitic wires - 8%.

NICKEL-TITANIUM

HYSTERESIS

• The transformation at different temperatures.

• The difference between cooling and heating.

• The range for most binary alloys is 400 – 600

PROPERTY AUSTENITE MARTENSITE

YIELD STRENGTH 560 MPa 100 MPa

ELASTIC MODULUS 75 GPa 28 GPa

NICKEL-TITANIUM

NICKEL-TITANIUM Martensitic transformation of

NiTi

FIDUCIARY LINE

Phase Transformation

MARTENSITIC TRANSFORMATION

ADDDITIONS and IMPURITIES

• + n of 3rd metal - TTR -200ºC

- Narrow the hysteresis.

- More accurate response.

• Thermally activated alloys contain third metal (Cu,Co)

• Small amounts of Al, Zr, Cr, or Fe will improve the

strength of the martensitic form

NITINOL

Laboratory and clinical Analysis Of Nitinol Wire

- G F. Andreasen, R E. Morrow ( AJO Feb 1978 )

Introduction of stainless steel wire appliances.

(1930- 1940) Nitinol ( Early 1960s) - William.F.Buehler, a research

metallurgist at the Naval Ordnance Lab in Silver Springs, Maryland

(Now called the Naval Surface Weapons Center ).

NITINOL

Ni - Nickel

Ti - Titanium

Nol - Naval ordnance laboratory

Clinical use of Nitinol wire started in May 1972

by G.F.ANDREASEN et al.

- Marketed as Nitinol by Unitek corp.

- Developed for the space programme.

- Useful because of its exceptional springiness.

Shape memory and

Super elasticity

NITINOL

NITINOL

SHAPE MEMORY WIRE

The characteristic of being able to return to a previously

manufactured shape when it is heated to a TTR.

Ability of the material to remember its original shape after being plastically deformed while in the martensitic form.

ELASTIC ORTHODONTIC WIRE

An outstanding elasticity which is useful for

orthodontic applications compared with st st.

NITINOL

In orthodontic applications

1. Requires fewer arch wire changes.

2. Requires less chair time.

3. Shortens the time required to accomplish the

rotations and leveling

4. Produces less patient discomfort.

NITINOL

PHYSICAL PROPERTIES

Material property Nitinol Stainless steel

Alloy Nickel, Titanium Iron, Chrome,Nickel

Ultimate strength 230,000 to 250,000 p.s.i 280,000 to 300,000 p.s.i

Modulus of elasticity 4.8 x106 p.s.i 28.5 x 106 p.s.i

NITINOL

BEND TEST

Acc to ADA Specification no.32 on orthodontic wires. TOST

NITINOL

NITINOL

TORSION TEST

A comparison between nitinol and stainless steel wires.

0 90 180 270 360 450 540 630 720

Torque Angle

NITINOL

STORED ENERGY COMPARISONS

Stored energy of Nitinol wire is significantly greater than an equivalent SS wire.this comparison was based upon the wires being bent 90 degrees

NITINOL

SPRING RATE

• Max F – both wires – full recovery without any permanent set.

NITINOL


Class I ,II,III malocclusions in both extraction and non

extraction cases

NITINOL Primary criterion – Amount of malalignment from the

ideal arch form.

More the deflection – more the benefit.

NITINOL

Imp benefits - a rectangular wire is inserted early in the

treatment.

Simultaneous rotation, leveling, tipping and torquing

can be accomplished earlier with a resilient rectangular

wire,

Cross bite correction

Uprighting impacted canines

Opening the bite

NITINOL

Torquing auxiliary in uprighting impacted canine.

NITINOL

Sectional arch wire

NITINOL

LIMITATIONS 1.Can`t be bent with sharp – cornered instruments.

2.It will readily break when bent over a sharp edge.

3.The bending of loops or omega bends are not

recommended. ( especially closing loops ).

4.Can`t be soldered or welded to itself without annealing

the wire.

NITINOL

5. Bending of tie-back hooks entails a high risk of

failure.

6. Cinch – backs.

- Annealing - Dark blue color flame.

- Cherry red flame – brittle.

(Continued)

Dr.Kishor Bagalkot

1970 – Nitinol – Martensitic.

Late 1980s – Austenitic – Superelasticity.

Phase - Transformation

AUSTENITE PHASE

MARTENSITE PHASE

• Martensite start(MS)

• Martensite finish(MF)

• Austenite start(AS)

• Austenite finish(AF)

Hysteresis A-B

(Ela

stic

D o

f A p

hase

. )(Transfn to M)

(Transfn completed.)

(E D of M structure)

(P D)

Hysteresis A-B

If stress released before reaching permanent deformation.

Elastic unloading of M

(Reverse transformation)(A Structure restored.)

(Elastic unloading of A)

Hysteresis A-B Elastic unloading of M

(Reverse transformation)(A Structure restored.)

(Elastic unloading of A)(Ela

stic

D o

f A p

hase

)(Transfn to M)

(Transfn completed.)

(E D of M structure)

(P D)

-Unloading curve differs from

the loading curve.

-The reversibility has an

energy loss.

-The force delivered - not the same as the force applied.

-Remarkable effect.

Hysteresis


CONVENTIONAL - NITINOL

SUPERELASTIC

• Chinese NiTi

• Pseudoelastic-Japanese NiTi

• Thermo elastic-Cu NiTi.


A certain shape is set at elevated temperatures (above the

TTR).When the alloy is cooled below the TTR, it can be

plastically deformed but when it is heated again the original

shape is restored.

Ex: An orthodontic arch form.

By lowering the temperature the alloy is transformed into

martensite and becomes pliable and easily deformed.

THERMOELASTICITY

SHAPE MEMORY

-High modulus alloy st st.

ELASTICITY AND SUPERELASTICITY:

-Effective strain Range cor to optm force zone.

-Force rapidly s as the teeth move.

Low EM. Alloy:

- Effective Strain Range – Larger.

- Nitinol, Braided wires.

SUPERELASTIC NITI

Eff. Strain Range cor to opt F zone

during Deactivation – more.

Small strain ranges

cor to other zones.

To remove small strain ranges -

Super position - over bending

Force guided activation -

overactivation

AJO 2001 - Olivier Nicolay – Pseudoelasticity and

thermoelasticity of nickel titanium alloys

Austenitic & Martensitic

Smart materials

- Reorganization of molecules

without change in the atomic compn to

meet the environmental

condn

Pseudoelasticity

-For most NiTi

- A phase (prevalent) + small (M) + intermediate R phase.

-On stress appln deflection - Stress Induced Martensite

Stress Induced Martensite (SIM)

-Unstable – On removal of stress.

-Partially compensates for the lack of thermally induced Martensite

-Contributes to the superelastic behavior of A – NiTi.

-This localized stressed related superelastic phenomenon

CHINESE NITI WIRE

CHINESE NiTi wire - A new orthodontic wire

- C. J. BURSTONE ( AJO JUNE

1985)

New NiTi by Dr.Tien Hua Cheng and associates at

the General Research Institute for non Ferrous

Metals, in Beijing, China.

CHINESE NITI WIRE

Austenitic parent phase + Little work hardened

Chinese NiTi wire has much lower transitional

temperature than NiTi wire.

CHINESE NITI WIRE

CANTILEVER APPARATUS

0.016 SS, Nitinol and A-NiTi

were submitted to a flexural test

STIFFNESS

SPRINGBACK

MAXIMUM MOMENT

Angular deflection measured by

protractor.

Bending moment Vs.Deflection

Arch Wire - Same force

- “Unique and Extremely desirable”.

CHINESE NITI WIRE

SPRING BACK

For 80º activation

SS - 16º

Nitinol - 52º

Chinese NiTi - 73º

CHINESE NITI WIRE

STIFFNESS

Activation and reactivation curves.

Unloading curves change at different

activation.

CHINESE NITI WIRE

THE MAXIMUM MOMENT

WIRE MOMENT SPRING BACK % RECOVERY

SS 3,067 16 20

NITINOL 2,112 52 65

NITI 1,233 73 91

CHINESE NITI WIRE

TEMPERATURE DEPENDENT CHANGES

temp. - stiffness

- reduced spring back

CHINESE NITI WIRE

TIME DEPENDANT CHANGESThe wires remained tied between 3 brackets for periods of 1 minute,1 hour and 72 hours.

Increased range of action –

large deflection.

Deformation - 4.4 st.st.

- 1.6 nitinol

CHINESE NITI WIRE

1. Applicable in situations where large deflections are

required.

2. When tooth are badly malpositoned.

3. Niti wire deformation is not time dependent

CLINICAL SIGNIFICANCE

JAPANESE NITI

The super - elastic property of the Japanese NiTi alloy wire

for use in orthodontics.

- Fujio Miura et al ( AJODO July 1986 )

In 1978 Furukawa electric co.ltd of Japan produced a new

type of alloy

1. High spring back.

2. Shape memory.

3. Super elasticity.

JAPANESE NITI

1. Examination of mechanical property of the wire.

1. Tensile test

2. Bending test

TESTS

JAPANESE NITI

Co-Cr-Ni, Nitinol ,

Ss and Japanese NiTi.

0.016 wire

Superelasticity.

1. Tensile test

JAPANESE NITI

JAPANESE NITI

Bending test

Different 0.016 wires


Alignment of badly malposed teeth

Distalize the molar

Expansion of arch

Gain/Close the space

Periodontally compromised pts


INITIAL

TWO MONTHS LATER

CLINICAL APPLICATION

The concept of NiTi coil springs was suggested in 1975.

1. Open coil springs.

2. Closed coil springs.

NITI COIL SPRINGS


Tensile and comp properties studied

- Japanese NiTi coil springs

- Desirable spring back and superelastic properties than st.st.

- Diameter of wire - SE

- Decreased lumen of the coil – increased SE

- Increased TTR – decreased SE

FACTORS THAT AFFECT THE MECHANICAL PROPERTIES OF SPRINGS.

AJO 1988, Fujio Miura


Closed coil spring

After 5 months


Open coil spring

After 3 months


Partially Impacted

second molar

Modified lingual arch &

NiTi coil spring.

Closed coil spring

After 3 months


MOLAR DISTALIZATION WITH SUPER ELASTIC NiTi

WIRE. - R.LOCATLLI et al ( JCO 1992 MAY ) .

After 4 months


NICKEL TITANIUM DOUBLE

LOOP SYSTEM- GIANCOTTI ( JCO APRIL 1998 )

After second molar erupts

80g Neosentalloy arch wire

2 sectional arch wires

NICKEL TITANIUM PALATAL EXPANDER

Tandem loop, nickel titanium , temperature activated palatal

expander.

- Light continuous pressure on the mid palatal suture .

( Simultaneous uprighting , rotating , and distalising the

maxillary first molars )


W.V.ARNDT ( JCO 1993


Disadvantages of conventional expansion.

-Intermittent force

-Inability to correct rotations.

-Arndt and Rickets – Uni/bilateral MLgl rotations

of molars.


A consequence of nickel titanium’ s shape memory and transition temperature effects.

The nickel titanium expander has a transition temperature of 940 F.

Below TTR – Metal is flexible

Above TTR – Metal stiffen

THE ACTION OF THE APPLIANCE

BELOW 200 C AT TTR

Passiveappliance

Initial activation

After expansion

8 intermolar widths 26-47mm

180-300gms

Amount of expansion + 3mm over correction.

Freeze gel packs in the expander kit.

AJO 2001, Christopher Ciambotti -- Comparison

Both – D Alv expn

Crossbite correction.

Tipping of molars.

More reliable widening

Comparison:

1. Palatal width change - RPE group is 28 %

- In NiTi group 16 %.

2. Buccal tipping of the alveolar process - RPE group – 5.080.

- NiTi group – 6.610

3. Molar rotation - RPE group 1.580

- NiTi group 26.610

4. Radiographic evidence shows that mid palatal

suture separation is less obvious in the NiTi group

than RPE group.

5. No correlation between age and amount of dento-

alveolar expansion.

6. RPE appliance widened the palate more reliably,

NiTi appliance tipped the molars buccally.


INDIVIDUALISED PRESURGICAL ARCH FORMS

- Fujio MIURA et al JCO Sept. 1990.

Clinical Application

Arch wires that have

MEMORIZED

various tooth

movement.


Before surgery After surgery


Provides 3 dimensional control Effective in surgical orthodontic cases Eliminates need to change arch wires frequently

DISADVANTAGES Bracket friction will be more when large wires are used

ADVANTAGES

Superelasticity –Llight constant force levels

Shape memory – Easy arch wire placement

REFRIGERENT SPRAY – ENDO ICE


BIOEFFICIENT THERAPY

ANTHONY.D.VIAZIS ( JCO Sept 1995 )


3-micron nitrogen coating that is produced by ion

bombardment of the wire surface.

Reduce

1.Friction

2. Breakage

3.Release of nickel into the mouth .

BIOFORCE IONGUARD WIRES

COPPER NiTi

VARIABLE TRANSFORMATION TEMPERATURE

ORTHODONTICS

- ROHIT C. L. SACHDEVA.

“Variable cross sectional orthodontics”.

“Variable modulus concept”

- BURSTONE

COPPER NiTi

• Introduced by Rohit sachdeva

• It has the advantage of generating more constant

forces than any other super elastic nickel titanium

alloys.

• More resistant to deformation.

• Smaller mechanical hysteresis

COPPER NiTi

QUATERNARY METAL – Nickel, Titanium, Copper,

Chromium.

Copper enhances thermal reactive properties and creates a

consistent unloading force.

CLASSIFICATION

Type I Af – 150 c

Type II Af - 270 c

Type III Af - 350c

Type IV Af - 400c

COPPER NiTi

1. Smaller loading force for the same degree of deformation. (20%

less )

2. Reduced hysteresis makes to exert consistent tooth movement and

reduced trauma.

ADVANTAGES OF COPPER NiTi ALLOYS OVER

OTHER NiTi WIRES

DIRECT ELECTIC RESISTANCE HEAT TREATMENT METHOD (DERHT)

ARCHMATE

DIRECT ELECTIC RESISTANCE HEAT TREATMENT METHOD (DERHT)

COMPOSITE WIRES

The future of orthodontic materials ROBERT.P.KUSY (AJODO Jan 1998)

• Metals

• Polymers

• Ceramics

Advantages are realised

Disadvantages are minimised

METAL-CERAMIC

METAL- POLYMER

CERAMIC- COMPOSITE

POLYMERS

METALS

CERAMICS

SEMICONDUCTORS

COMPOSITE WIRES

In orthodontics

Composite prototypes of arch wires, ligatures,

Brackets - S-2 glass fibers ( ceramic )

- Acrylic resins ( polymer )

Esthetically pleasing because they tend to transmit the

colour of host teeth Strong & Springy.

COMPOSITE WIRES

The process of manufacturing components of

continuous lengths & a constant cross sectional shape

Eg; Arch wires

Bundles of continuous fibers are impregnated with a

polymeric resin pulled through a sizing die

Then passed through a curing die that imparts a

precise shape ( Electro magnetic radiation )

PULTRUSION

Comparison of unidirectional fiber reinforced polymeric composites to NITI alloys in bending

COMPOSITE WIRES

Patients with allergic reactions with nickel

Esthetic than previous wires

Better strength & springiness

DISADVANTAGES

Shape can not be changed

ADVANTAGES

COMPOSITE WIRESOPTIFLEX WIRES

A composite ceramic fiber-plastic-nylon ( ORMCO )

Dr.TALASS

COMPOSITE WIRES

A. Silicon dioxide core - ForceB. Silicon resin middle

layer - Protection from moistureC. Nylon layer - Prevents from damage

Structure – Clear optical fiber made of 3 Layers

COMPOSITE WIRES

The wire can be ROUND or RECTANGULAR

• Wide range of action

• Light continuous force

• Sharp bend must be avoided

• Highly resilient - Effective in the alignment of

crowded teeth

References :•Proffit W R; Contemporary Orthodontics,Ed.2,Mosby YearBook Inc.,St.Louis,U.S.A.,1993.

•Graber T M & Vanarsdall R L;Orthodontics,Current Principles & Techniques,Ed.3,Mosby Inc,St.Louis,U.S.A.2000.

•Ralph W P;Skinner’s science of dental materials;Ed.9,

W B Saunders Company,1992

•Robert P.Kusy;A review of contemporary arch wires;Their properties and characteristics’ Angle Orthod,1997;67(3);197-208

References :

Charles J Burstone&AJ Goldberg;Beta Titanium;A new orthodontic alloy;AMJ Orthod 1980;77:121-132.

Wilcock AJ;Applied materials engineering for orthodontic wires; Aust Orthod J,1989;11(1);22-29

Andreasen GF& Marrow RE;Laboratory &clinical analysis of nitinol wire;AMJ Orthod 1978;73;142-151

Charles J Burstone,Qin&Morton;Chinese Niti wire;A new orthodontic alloy;AMJ Orthod 1985;87;445-451

Fujio Miura,Mogi,Ohura&Hamanaka;The super-elastic property of the Japanese NiTi alloy wire for use in orthodontics;AMJ Orthod Dentofac Orthop,1986;90;1-10

References:

Rohit sachdeva;Orthodontics for the next

millenium;chapter-Biomechanical consideration in the

selection of NiTi alloys in orthodontics and variable

transformation temperature orthodontics with copper-

NiTi,1997;Ormco,227-247

A comparative study of metallurgical & working properties

of two new Titanium based alloy wires(TiMolium &Beta

III)with the earlier introduced titanium wires(TMA),and

also Alpha Titanium wires

-Dr. Jiku Abraham

Clinical Insights on Copper NiTi

Charles R.Sager – A.Clinical Comment

- 35º - 17 x 25 or 19 x 25 – Initial A/w.

- Dead soft in hand, Resilient M. temp.

- Easy to place crimpable hooks

- For elastics or

- For ant. H.G.

Clinical Insights on Copper NiTi

Charles R.Sager – A.Clinical Comment

- Ethyl chloride sprayed on cotton applicator.

- Bend back / Cinch back – flame the wire.

- Rect . A/W – Very early in treatment

Allen Polland – Australia.

- 35º - 16 x 22 – for minimum crowding, non extraction.

- Triplex spray – for engaging the wire.

- No pain.

- H.G. – C1 pull H.G. for correction of class II molar relation

- Rectangular wire – to limit the lingual collapse of lower

anterior.

- Disadvantage – no transverse and vertical control.

Randall C. Moles

Patient + doctor – time = Copper NiTi

- Temp – at which the wire will deliver its optimum

force level.

- 35º copper NiTi - initial phase 19 x 25.

(Continued)

Dr.Kishor Bagalkot

- Amount of force delivered by the wires to the D Alv

st. in the deactivation phase.

- Light forces - More physiologic.

- Literature about the delivery of forces - Large

variations.

Pseudoelasticity and thermoelasticity of NiTi

alloys: A clinically oriented review – Margherita

Santoro, Olivier F Nicolay. (AJO 2001)

-Variations in forces delivered

- Non uniform methods of measuring i.e, N, cN, Pa.

-Alloy compn, CS, No of strands in the wire.

-In the early expts, uniaxial tensile tests for comparing

mechanical properties.

- Stretch of > 8% to see the SE properties.

- Using cantilever configuration.

- Bending moments in gm/mm.

- Deflection in degrees.

- ADA approved method – Sp No. 32.

Flexural Tests:

- May simulate SE behavior even for non SE alloy.

For reliable and valuable data, expts that simulate as

closely as possible IOl setting.

-3 bracket bending tests.

- Useful results for clinical needs.

- Unilateral bending tests.

3 Bracket Bending Test

3 Point Bending Test

-Thermostats and insulated chambers.

-Alt approach – expts at room temp.

-Wires with TTR at oral temp. – partially M.

Tests at room temp. – as SE wires & low forces.

Temperature Settings:

-An ideal arch wire – differential forces to the arch

segments.

-70gms – 80gms in the incisor area

-Gradually increase towards post. Segments upto 300gms

How heavy are the deactivation forces

- Small diameter multistranded st.st.

- SE wires

- Forces < 100gm

Force delivery characteristics of some of the commercially available NiTi alloys*

Force delivery characteristics of some of the

commercially available NiTi alloys

0.016 x 0.022

600

500

400

300

200

100

NiTiNitinol SE Nitinol Classic 27ºC Cu Niti 35º C Cu Niti 40ºC Cu Niti Sentalloy(H) Neo Sentalloy

300 gms

215 gms

137 gms80 gms

87 gms

313 gms

293 gms

143 gms

Two primary considerations.

1. An appropriate stress related TTR cor. to the

oral temp.

2. A physiologic force to the teeth and pdm.

How to choose a NiTi wire?

- At least 2mm of deflection.

- Severe dental crowding.

- Not in very mild crowding.

- Pdly compromised patient.

How to choose a NiTi wire?

- The stress value Fairly constant

- Heat Rx with Nitrate Salt Bath – dramatic changes in these properties.

- It might be possible to bend the wire in to the other configurations and still be able to control the amount of force.

Japanese NiTiWire use of DE RHT method - Fujio

Minra Masakuni Mogi & Yoshiaki Ohura –EJO 1988

- Subject of basic research – Tokyo university – 1978.

- Spring back

- Shape memory

- SE

Controlling the amount of force with SE

Material – 5 difnt diameters of Jap NiTi alloy wire

014,016,018,020 & 022.

Wires – Other wires

St.St., Co-Cr Ni, Work hardened NiTi

2 Parts Bending the A/W

- Electric power supply – a transformer, timer, meter, foot switch.

- A pair of electric pliers.

- An electric arch holder.

Heating equipment ARCHMATE

- A 6cm straight wire – curved

- Current – Wire – Memorized the new shape.

- A longer Rx time – less current

- The small wire – less current

Methods findings – Bending the A/W

Graph – Reln betn length of time & Amperage of Current

when wire bent for 90°

- Jap NiTi – bent with DERHT rebounded to original 90° indicating pt deformn of 0° degree.

- i.e. On heat Rx – No change in spring back properly

- St. St. & Co-Cr Ni – Rebound 50°

- Work hardened NiTi - 75°

Testing the Mechl properties of wires

-A cantilever straightening test.

- Wires – Rebent - 90° to 0°

3.5Amps – Arch holder – Ant. Segment – 45 mins

3.5 Amp – Pm segment + Ant segment 15mins.

i.e. A-A1 – 60 mins. Ends / Molars segments – Not heat

treated.

Controlling the Amount of force

- Only desired secn of wire – heat treated.

2. Bending

- Pliers and finger cold hardening process

- Difficult for NiTi wire,

- Special pliers – loose spring back property

- DERHT does not diminish mech1 property

Discussion –

1. DERHT Method

- Utilizes electric resistance of wire to generate

016” utility wire with electric pliers

Pseudoelasticity and Thermoelasticity of NiTi

alloys: A Clinically Oriented Review – Margherita

Santoro, Olivier F Nicolay. (AJO 2001)

- Data available in the literature - TTR S of alloys.

- Thermomechl behavior – Correln betn TTR and Oral temp.

- Buehler – 1960

- NiTi orthodontic alloy – Andreasen

- Claims

- Difnt parameters and Exptl settings to analyze difnt

compns and properties.

- Improvements

Thermoelasticity and Shape memory effect:

An ideal NiTi – Stable at mouth.

- Formable at room temp.

Most Recent Techno – Advances – SE NiTi s

SE NiTi

A - Phase

M - Phase

‘R’ - Phase

Mechl Properties and composition of NiTi alloys

- Molecular arrangement - modified

- No change in atomic compn

- Transformn Diffusionless

- Smart Material

Temp variations Crystal St. Deformns


- Crystal st of alloy confirmed by

- Radiographic diffracn

- Difntial scanning calorimetry

- Each NiTi alloy specific TTR


Resistivity of SE NiTi to Temp

-Both A and M difnt amount of resistance to passage of

electric currents.


- At higher temp > Af wire remains in Austenitic

phase.

- Shape memory - Wire in A – Phase able to memorize a

PREFORMED shape.


- Low temp. M.; Temp A

Every time Temp > Af Arch form.

Technically One way shape Memory Effect.

Eg – CuNiTi 40º

At room temp. M or mixed phase sharp bends.

Wire Hot water Temp > Af i e 40ºc Original arch form.

- Temp M pliable and easily deformed.

- When Completely austenitic Above Af Stress strain

curve follows Regular pattern of other alloys such as St.St. ie

Lack of plateau.

A - NiTi More Elastic than other Alloys.

Not SE (In absence of Stress)

- Af.< Oral Temp, wire primarily A – IOly and Fully M – EOly

Objectives of Research New Alloy like CuNiTi.

TTR cor to oral Temp and Reach Af above Oral

Temp.

In phase transition, both A and M – NiTi will be stiffer

than SE wire

-NiTi absorbs Deflecn stresses.

ME low more stiffer.

- When only moderate deflection in required A NiTi

deliver biologically acceptable force.

- Low forces of NiTi Hypothetical

- Need to be compared with force delivery of other alloys

through proper expts.

- The performance of any NiTi – Composition and

Manufacturing procedures.

A + (Small M) + R Phase Grain St.

To activate SE properties quantities of M

On Stress appn Deflection (SIM) formed

Local M. Transformation Even rest of wire remains A

Pseudoelasticity

These areas wire will be SE till the tooth moves.

– When Af below oral temp.; A phase intra orally

This property Pseudoelasticity.

A localized stress related SE phenomenon

- SIM formation possible only. Af slightly lower than oral

temp.

- If Af considerably lower than oral temp – more Austenitic

and Too much energy required for maintaining (SIM).

- SIM Compensates for TIM and contributes to SE properties.

Only in cases of very severe crowding

An A – NiTi behaves SE lically.

-Pseudo and thermoelasticsity not always present

-Advertisement Confusing/misleading

-Attempt to simplify the clinical choice

Review of Available Alloys

NiTi : Generally classified - SE

- Non SE

SE Pseudoelastic Chinese NiTi

Japanese NiTi

Thermoelastic - Copper NiTi



- Heat treatment and pressure variations

- Modifications of atomic compn eg. CuNiTi

Tech Advancements - TTR at sp temp. 27º,35º,40º C

1. TTR betn room and body temp - M active alloys

2. TTR below oral temp – A active alloys

3. TTR close to body temp – on insertion, shape memory


Water’s review – 1992 – three groups based on their TTRs


Phase I Au & St.St.

Phase II Stabilized eg. Work hardened Nitinol

Phase III SE – A, Active Austinitic, TTR < oral temp,

predominantly A at room temp.

Phase IV Thermodynamic.

Phase V Graded thermodynamic

Recently Evans and Durning – 5 groups

Review of Available Alloys:

- TTR close or cor to oral temp.- working range at room temp - On temp both SIM & TIM Austinite

-Wires Af above 37ºC i.e. CuNiTi 40ºC

-Austinite forms only when the temp above 40ºC

- Hot rinses to force

- Cold rinses to discomfort

Phase V Graded thermodynamic

Phase IV Thermodynamic - Active Martensitic

- TTR close or slightly below oral temp. to allow SIM

formn

TTRs of available alloys

- Several expts – to verify TTR values

2. Complexity of Manufacturing procedures.

- Wires of lllr compn difnt TTRs

- Expt1 findings Not comparable

- Some manufactures don’t provide accurate

informns of TTR

Variations in TTRs

1. IO1 temp wide fluctuations – Appx – 35º - 37º expt1

settings.


-Most alloys TTR betn 17º & 32ºC

-Practically unable to exhibit – SE behavior during clinical

applicns

-CuNiTi s 27 & 35º Af active Austenite

- CuNiTi 40ºC Truly SE at oral temp.

Yoneyama, Doi and Hanamaka – used differential scanning

claorimetory


-Formn of SIM Shift of TTR towards higher temp.

-On stress apln maintains Martensitic phase.

Higher energy to reconvert SIM A

Clinically stress related TTR/Stress related Af

-Actual temp at which thermoactive wires activated.

-Necessity of studying TTR in +nce of stress.

Stress related TTRs

Coluzzi et al :

When No Deflecn NeoSentalloy – Af - 28ºC

On Loading Af - ed proportionally to 34ºC

Leone’s unloaded 20ºC

on loading 35ºC

- Deflecn device loading of 2

- At 5ºC all alloys M 2.38mm of PDn

- At 37ºC all alloys A 0.08mm of PDn

Mullins, Bagby & Norman – N.Sentalloy – F100, 200, 300

& bioforce sentalloy

– Compared thermodynamic properties of active arch Nitinol

Heat activated Nitinol and Neosentalloy.

Expt setup Variation of cantiliver bend test in temp

controlled environments.

Bishara et al

-30º and 40º bends in straight wire segments

-Samples Immersed in H2O

-100% Recovery of original shape.

-All alloys TTR an average betn 21-28ºC

All Samples TTR below oral temp.

Santoro & Beshers.

Neosentalloy

27º Se CuNi & Thermoactive 35 & 40º CuNiTi

Active Arch Nitinol.

-Thermoactive NiTi alloys also studied under stress.

Neosentalloy Stress related Af - 28ºC

27º SeE CuNiTi Stress related Af - 32ºC

Both Mainly Austenitic Ioly even +nce of Delfect.

35º CuNiTi – Stress related Af 39ºC

40º CuNiTi

Expt1 Setting Crowded lower incisors.

In summary – 2 fundamental properties to select a NiTi wire.

1. A proper stress related TIR cor to or slightly below oral temp.

2. A Low deactivation force to the dentoalv. St.

• Light forces - bone hyaline

• Limit undermined resorption

• More physiologic tooth movt.

• A review of literature large variations in study designs

Part II Deactivation forces:

• Amount of force delivered by wires to dentoalv. St. in

Deactivation force.

• Forces may be given in cN, N, or expressed as strengths in parcals

• In clinical practice, forces in gms/ounces.

• Parameter commonly used force delivery – Stiffness values i.e. force required to obtain a deflecn in the wire below the yield point.

• Does not give useful informn about amount of force to D.Alv. st.

Part II Deactivation forces:

• Methods used to measure force not uniform.

• Alloy compn

• CS

• No of strands of wire used in the expt

Specific expts to obtain direct clinical data

Force delivery influenced by

Wire attached at one end & stretched.

A stretch of more than 8% to see SE expression

Forces - not usually observed in clinical aplns

Generally produce values of ME which are

significantly lower than those obtained by deflecn

tests.

In early expts, - uniaxial tensile tests – most acceptable

for comparing mechl properties of difnt alloys.

• Forces evaluated on bending moments

• Expressed in gms/mms.

• Delfecn – measured in degrees.

Flexural tests using cantilever configurn

• Cantilever tests -ADA approved

• ADA Sp No. 32

• A single direcn deformn by unilat1 bending.

• May simulate SE behavior (even if alloys is not SE)

• Wire slides unrestrained over the supp device

• Fricn the loading force SE behavior

• Non restrained - No considn of fricn by ligations.

Does not reproduce the clinical constraint.

To obtain reliable & valuable data.

• Free end principle

• Consistent method of ligation of wire

• IB distance

• Type of Bracket used

• Length of wire specimen.

Expts simulate IO clinical setting.

- Used in recent lab expts on A-NiTi

- Common finding – High stiffness if wire is deflected less than 2mm.

- Because of lack of formn of SIM

ANiTi presents 0.28 Stiffness for small deflecns

Nitinol presents 0.20 – stiffness for small deflecns

3 Bracket B.Test – Partially restrained model

Threshold of 2mm – minimum activation of SE – A NiTi

Stress strain curves for St.St. Nitinol & NiTi -

- Consistent +nce of Martensite – Lowering deactivn force.

- Martensite – Low stiffness phase – ME 2000000psi

- Austenite – higher stiffness phase – ME – 8000000psi

- The relative concn of two phases - Resultant stiffness &

amount force delivered.

On Stress:

A – SIM – Pseudoelasticity

• Initial activn force – 3 times more than Nitinol.

• Once SIM forms – Hzl plateau appears.

• Alloy absorbs any additional load and releases it.

• Linear region cor to deactn plateau lower than the activn

phase.

• SE compounds – high stiffness initially when deflecn minm.

Nakano et al – 16 x 22 Nitinol SE – 3pt BT at 37

Segner & Ibe, Oltjen – 16 x 22 Nitinol SE – 3 brackets BT at 35

Other authors – Nitinol SE – 79.6 9/mm at room temp.

Dift. Expt1 settings – Results

Nitinol SE, Nitinol classic

• Control of temp – Thermostats & Insulated chambers.

• Numerous expts – done at room temp.

• Wires – TTR at O1 temp – partially Martensitic

• When Tests conducted at room temp – performs as SE

• At oral temp- M A.

• Highest temp at which SIM can form – Md.

• In active A-NiTi – Md > Af

Temperature settings

- In active Martensitic wire – TTR at oral temp so that amount of M – constantly available.

- Tonners & Waters – Plateau with of temp.

- Sentalloy light 0.016 – 20 cN at 35C – 62 cN at 50C

- Sentalloy heavy .016 - .77 cN at 35C, 108 cN at 50C

- Ormco NiTi – 102 cN at 35 - 112 cN at 50C

- Af – located slightly below oral temp.

Temperature settings

Authors confirmed• temp - SIM

• SE wires at least 2mm of deflecn.

• How heavy are the deactn forces.

• Depends on Ratio betn Magnitude of force & affected Root Bone surface.

• An ideal A/W – differential forces.

• Forces < 100gm – by small multistranded st.st.

Stress strain values –

• Manufacturing process• Difnt expt1 settings.

Variability of E properties -

16x22 sentalloy medium – 3BBT – 695 gm/mm if – for clinical appln

- To maintain 100gm force - .016 round wire. - 73gm in 3 PBT

Eg. 1. Sentalloy

16x22 sentalloy medium – 3 PBT 193gm /mm

- 3 PBT at 37C – 143gm/mm force

- 3 BBT – 36gm

2. For Neosentalloy –

16 x 22 wire type F240

- Light forces – range of or below 100 gm/mm 3 BBT at oral temp. 37° C.

27 ° SE CuNiTi – 137 gm/mm

Small diameter round wire.

Cu NiTi – 16 x 22 35° & 45° C

Multibraided strand NiTi wire – 17 x 25 – 12.4gm/mm.

Classic Multi stranded St.St. – 17 x 25 - 170.7 gm/mm.

0175 – st.st in 6 strand – 43.1 gm/mm.

Lab tests – st. st 4 to 5 times more stiffer than SE NiTi.

Multi stranded St St Vs. Nickel Titanium

Oltjen et al – 3 BBT at room temp.

A NiTi 17x25 – 2mm deflecn – 18gm/mm.

- Multi stranded st.st, Nitinol & Chinese NiTi – compared to

test degree of pt deformation.

- > 50% of Braided st. st – pth deformed.

- 3 PBT – 4mm deflecn - at 2mm - Braided wire – moderate

plastic deformn.

- Exceptional spring back and

- R to pt deformn – over a longer period.

Advantage of SE wire

- Range of force by multist st.st. – Acceptable.

SE. NiTi – Elective choice

1. Moderate crowding

2. Arch form & torque control require in initial stages.

Acc to data – minm crowding – A multistr. St.St. wire.

- i.e. Less force + Torque control required.

lar Cu NiTi 40°C

In cases of severe crowding & Pdl compromised pts

- Miura – immersed several SE NiTi wires – in Nitrate

Salt bath at difnt temps.

- Bending Test for testing mechl properties.

Jap NiTi - 500° C for 20 mins

Force – 300 – 50 gm

i.e. A higher temp Rx – Complete loss of SE properties.

Graded Thermodynamic NiTi

- Heat Rx of selected secns of A/W by means of difnt currents, delivered by electric pliers.

- Modified values of deactivn forces by varying the amount of Austenite in the alloy.

- After heating ant segment 60 mins – force – 80gms

- lllr procedures – Bioforce wires – selective force.

- Evans & Durning – Classified – Phase V or Graded Thermodynamic NiTi.

A few years later,

- DERHT – Direct Electric Resistance Heat Treatment.

Filleul & Jordan

- Used differential scanning calorimetry.

- Teq – that measures Euthalpy of phase transition .

Torsional Behavior

- Rect NiTi wires – Early Torque control during the aligning.

At 22°C, 39° & 44°C

N.S.F100 - 22°C – SE plateau – 910gm/mm Torque

At higher temp – No plateau – wires – Austenite

Filleul & Jordan

- 17 x 25 - Neo sentalloys F100,

35° Cu NiTi

40° Cu NiTi

19 x 25 st.st – 30° degree twist – 3000gm/mm

Deactivn of SE NiTi – Definitely Lower than St.St.

Temp - Torquing forces of NiTi.

CuNiTi - 35° & 40° - Equivalent torsional behavior

21.7°C – SE plateau – 560gm/mm torque

39° C – SE plateau – 1190gm/mm torque

44° C – SE plateau – 1400 gm/mm torque.

- Temp - force by 85%

- Force variations – Transient

For All Cu NiTis & Neo Sentalloys –

- 20° constant twist - 37°C – 1000gm/mm

Meling & Odegaard

- Temp - Torsional force

- Rate of tooth movt – light cont forces – double.

- Histologically – Normal oblasts, oclasts in Plig of rats when SE NiTi.

- When work hardened alloy – hyalinizn - no of cells.

Clinical Trials:

- Randomized clinical trials

- Faster tooth movt.

- Less pt discomfort

Acc to Expt1 data obtained on rats.

By Warita Et al

Jones & Richmond –

Triple strand .015 St.St. = 0.014 sentalloy

West et al :

- 015 multist st.st. Vs. 014 A-NiTi

- 6 weeks clinical trial

- SE wires showed better performance only in lower incisors

OBrien et al

- No difference in rate of tooth movt. betn. Austenite & work hardened alloy

Reitan & Storey – Definite Reln betn amount of force &

pain.

Jones & Chan – recorded pain & discomfort

- 014 Heavy sentalloy

- 015 multistranded st.st.

Minm discomfort – by pt.

1. More pain after A/W insertion than that of Xn

2. No difference betn A/W

3. No difference degree of crowding

4. Significant coreln betn age and level of pain

- Pain reported by pt –

1. An appropriate stress – related TTR cor to oral temp.

2. A physiologic force.

Considerations for choosing NiTi

1. Type of loading

- lllr to oral condn/clinical appln. - 3

BBT – most consistent device.

2. Amount of loading

- At least 2mm deflect – SIM formation

- Below 2mm – higher force – more A

- Severe dental crowding

- Deflecn – Localized SIM

Expts to study NiTi

- No need of SE wire

- A small diameter work hardened alloy or

- Multistranded round st.st. wire

In pdly compromised pts – force level > 100gm

- controlled force levels

Mild Crowding

ortho wires part iii

Health & Medicine