73893775 Orthodontic Wires

ORTHODONTIC WIRESORTHODONTIC WIRES

BY JITHIN JACOBBY JITHIN JACOB

www.dentistpro.org to find more

INDEXINDEX INTRODUCTIONINTRODUCTION EVOLUTION OF ORTHODONTIC WIRESEVOLUTION OF ORTHODONTIC WIRES PROPERTIES OF ORTHODONTIC WIRESPROPERTIES OF ORTHODONTIC WIRES MANUFACTURING OF ORTHODONTIC WIRESMANUFACTURING OF ORTHODONTIC WIRES WIRE ALLOYSWIRE ALLOYS GOLD ALLOYSGOLD ALLOYS STAINLESS STEEL WIRESSTAINLESS STEEL WIRES AUSTRALIAN ARCH WIRESAUSTRALIAN ARCH WIRES BRAIDED WIRESBRAIDED WIRES Co-Cr NICKEL WIRESCo-Cr NICKEL WIRES TITANIUMTITANIUM ALPHA TITANIUM WIRESALPHA TITANIUM WIRES BETA TITANUM WIRES(TMA)BETA TITANUM WIRES(TMA) NICKEL TITANIUM ALOYNICKEL TITANIUM ALOY NITINOLNITINOL CHINESE NITICHINESE NITI JAPANESE NITIJAPANESE NITI Cu NITICu NITI ESTHETIC WIRESESTHETIC WIRES CONCLUSIONCONCLUSION BIBLOGRAPHYBIBLOGRAPHY


INTRODUCTIONINTRODUCTION Orthodontic wires, which generate the biomechanical forces Orthodontic wires, which generate the biomechanical forces

communicated through brackets for tooth movement, are communicated through brackets for tooth movement, are central to the practice of the profession.central to the practice of the profession.

Ideally arch wires are designed to move the teeth with light Ideally arch wires are designed to move the teeth with light continuous force. It is important that these forces do not continuous force. It is important that these forces do not decrease rapidly. Also an ideal arch wire should have decrease rapidly. Also an ideal arch wire should have certain properties like esthetics, biohostability, formability, certain properties like esthetics, biohostability, formability, resilience etc. but the search of a arch wire which meets all resilience etc. but the search of a arch wire which meets all this requirements and is perfect is still not over and the this requirements and is perfect is still not over and the search continuous…..search continuous…..

For not abusing the material and for designing the For not abusing the material and for designing the appliance to its full potential the proper understanding of its appliance to its full potential the proper understanding of its physical and mechanical properties is required. The aim of physical and mechanical properties is required. The aim of this seminar is to provide this basic knowledge of this seminar is to provide this basic knowledge of orthodontic wire characteristics.orthodontic wire characteristics.

Evans (BJO 1990)Evans (BJO 1990) divided the phases of divided the phases of archwire development into five phases on the archwire development into five phases on the basis of (a) Method of force delivery, (b) basis of (a) Method of force delivery, (b) Force/Deflection characteristics and (c) Material.Force/Deflection characteristics and (c) Material.

PHASE IPHASE I Method of force delivery: Method of force delivery: Variation in Variation in

archwire dimensionarchwire dimension Force/Deflection characteristicsForce/Deflection characteristics: Linear : Linear

force/deflection ratioforce/deflection ratio MaterialMaterial: Stainless steel, Gold: Stainless steel, Gold

EVOLUTION OF ORTHODONTIC WIRES(PHASES OF ARCHWIRE DEVELOPMENT)

PHASE IIPHASE II Method of force deliveryMethod of force delivery: Variation in archwire : Variation in archwire

material but same dimensionmaterial but same dimension Force/Deflection characteristicsForce/Deflection characteristics: Linear : Linear

force/deflection characteristicsforce/deflection characteristics MaterialMaterial: Beta Titanium, Nickel titanium, : Beta Titanium, Nickel titanium,

Stainless steel, Cobalt chromiumStainless steel, Cobalt chromium

PHASE IIIPHASE III Method of force deliveryMethod of force delivery: Variation in archwire : Variation in archwire

diameterdiameter Force/Deflection characteristicsForce/Deflection characteristics: Non-linear : Non-linear

force deflection characteristic due to stress force deflection characteristic due to stress induced structural changeinduced structural change

MaterialMaterial: Superelastic Nickel Titanium: Superelastic Nickel Titanium

PHASE IVPHASE IV Method of force deliveryMethod of force delivery: Variation in structural : Variation in structural

composition of archwire materialcomposition of archwire material Force/Deflection characteristicsForce/Deflection characteristics: Non-linear : Non-linear

force/deflection characteristic dictated by thermally force/deflection characteristic dictated by thermally induced structural change induced structural change

Material: Material: Thermally activated Nickel titaniumThermally activated Nickel titanium

PHASE VPHASE V Method of force deliveryMethod of force delivery: Variation in archwire : Variation in archwire

composition/structurecomposition/structure Force/Deflection characteristics: Force/Deflection characteristics: Non-linear Non-linear

force/deflectionforce/deflection characteristics dictated by different characteristics dictated by different thermally induced structural changes in the sections of thermally induced structural changes in the sections of the archwirethe archwire

MaterialMaterial: Graded, thermally activated nickel titanium: Graded, thermally activated nickel titanium

THE EARLY ARCHWIRESTHE EARLY ARCHWIRES The scarcity of adequate dental materials at the end The scarcity of adequate dental materials at the end

of the nineteenth century launched E.H. Angle on his of the nineteenth century launched E.H. Angle on his quest for new sourcesquest for new sources

Angle listed only a few materials as appropriate work. Angle listed only a few materials as appropriate work. These included strips or wires of precious metal, These included strips or wires of precious metal, wood, rubber, vulcanite, piano wire, and silk thread.wood, rubber, vulcanite, piano wire, and silk thread.

Before Angle began his search for new materials, Before Angle began his search for new materials, orthodontists made attachments from noble metals orthodontists made attachments from noble metals and their alloys Gold (at least 75%, to avoid and their alloys Gold (at least 75%, to avoid discoloration), platinum, iridium, and silver alloys discoloration), platinum, iridium, and silver alloys were esthetically pleasing and corrosion resistant, were esthetically pleasing and corrosion resistant, but they lacked flexibility and tensile strengthbut they lacked flexibility and tensile strength

In 1887 Angle tried replacing noble metals with German silver, In 1887 Angle tried replacing noble metals with German silver, a brass. His contemporary, J.N. Farrar, condemned the use of a brass. His contemporary, J.N. Farrar, condemned the use of the new alloy, showing that it discolored in the mouth, Farrar’s the new alloy, showing that it discolored in the mouth, Farrar’s opinion was shared by manyopinion was shared by many

To obtain the desired properties, Angle acted, as stated in To obtain the desired properties, Angle acted, as stated in 1888, “by varying the proportion of Cu, Ni and Zn” around the 1888, “by varying the proportion of Cu, Ni and Zn” around the average composition of the Neusilber brass (German silver, average composition of the Neusilber brass (German silver, 65%Cu, 14%Ni,21%Zn), as well as by applying cold working 65%Cu, 14%Ni,21%Zn), as well as by applying cold working operations at various degrees of plastic deformation.operations at various degrees of plastic deformation.

Besides its “unsightliness” and obvious lack of reproducibility Besides its “unsightliness” and obvious lack of reproducibility (variations in composition and processing), the mechanical and (variations in composition and processing), the mechanical and chemical properties of German silver were well below modern chemical properties of German silver were well below modern demands. However, because it could be readily soldered, this demands. However, because it could be readily soldered, this brass allowed Angle to design more complex appliances.brass allowed Angle to design more complex appliances.

The material that was to truly displace noble The material that was to truly displace noble metals was stainless steel. As with German metals was stainless steel. As with German silver, it had its opponents. As late as 1934 silver, it had its opponents. As late as 1934 Emil Herbst held that gold was stronger than Emil Herbst held that gold was stronger than stainless steel without exfoliation. Ifstainless steel without exfoliation. If forced to forced to choose, he even preferred German silver to choose, he even preferred German silver to stainless steel. Eventually, better stainless steel. Eventually, better manufacturing procedures and quality control manufacturing procedures and quality control made stainless steel the material of choice.made stainless steel the material of choice.

DESIRABLE PROPERTIES OF DESIRABLE PROPERTIES OF ORTHODONTIC WIRES:ORTHODONTIC WIRES:

The ideal properties for an orthodontic purpose according to Proffit5 are:The ideal properties for an orthodontic purpose according to Proffit5 are:

1.1. High strength.High strength.2.2. Low stiffness.Low stiffness.3.3. High range.High range.4.4. High formability.High formability.

Kusy11Kusy11 (1997) in a review of contemporary arch wires listed a few ideal (1997) in a review of contemporary arch wires listed a few ideal characteristics desired in an archwire as follows:characteristics desired in an archwire as follows:

1. Esthetics1. Esthetics 2. Stiffness2. Stiffness 3. Strength3. Strength 4. Range4. Range 5. Springback5. Springback 6. Formability6. Formability 7. Resiliency (Resilience)7. Resiliency (Resilience) 8. Coefficient of friction8. Coefficient of friction 9. Biohostability9. Biohostability 10. Biocompatibility10. Biocompatibility 11. Weldability11. Weldability

PROPERTIES PROPERTIES OFOF

ORTHODONTIC ARCH WIRES ORTHODONTIC ARCH WIRES

StrengthStrength -Proportional limit-Proportional limit -Yield strength-Yield strength -Ultimate tensile strength-Ultimate tensile strength StiffnessStiffness RangeRange ResilienceResilience FormabilityFormability


There are three points on a force-deflection curve that There are three points on a force-deflection curve that represent strength. Studying materials using a graph is represent strength. Studying materials using a graph is

very helpful because very helpful because

"a picture is worth a thousand words.""a picture is worth a thousand words."

Strength:Strength: Strength is the measure of the force a material can Strength is the measure of the force a material can

withstand before the material permanently deforms. (withstand before the material permanently deforms. (is the is the maximal stress required to fracture a structuremaximal stress required to fracture a structure)Strength may be )Strength may be viewed in these three ways: viewed in these three ways:

1.1. Proportional Limit: the point at which any permanent Proportional Limit: the point at which any permanent deformation first occurs.deformation first occurs.

2.2. Yield Strength: the point at which 0.1% deformation is Yield Strength: the point at which 0.1% deformation is measured. measured.

3.3. Ultimate Tensile Strength: the maximum load that the Ultimate Tensile Strength: the maximum load that the wire can sustain. wire can sustain.

strength is in units of forcestrength is in units of force

Stiffness:Stiffness:

Stiffness is proportional to the slope Stiffness is proportional to the slope of the linear portion of the graph of of the linear portion of the graph of the force-deflection curve of a the force-deflection curve of a material. The linear portion ranges material. The linear portion ranges from zero to the proportional limit. from zero to the proportional limit. The steeper the slope, the stiffer the The steeper the slope, the stiffer the material. (defined as the ratio of material. (defined as the ratio of force to deflection of a member)force to deflection of a member)

Range:Range:

Range(flexibility) is the deflection the material Range(flexibility) is the deflection the material will encounter before any permanent deformation will encounter before any permanent deformation occurs - from zero to the proportional limit. occurs - from zero to the proportional limit. Beyond the proportional limit, the material will Beyond the proportional limit, the material will bend, but it will not return to its original shape. bend, but it will not return to its original shape. There is, however, a limit to the amount of There is, however, a limit to the amount of bending beyond the proportional limit to which bending beyond the proportional limit to which you can bend a material - the failure point is were you can bend a material - the failure point is were it breaks (it breaks (Range is defined as the distance the wire will bend Range is defined as the distance the wire will bend

elastically before deformation occurs, and is measured in millimeterselastically before deformation occurs, and is measured in millimeters)) range is in units of length range is in units of length

Internal stresses and external strains are characteristics of a material Internal stresses and external strains are characteristics of a material that can be calculated from the force-deflection curve. This that can be calculated from the force-deflection curve. This

relationship explains the similarity in the shapes of the force-deflection relationship explains the similarity in the shapes of the force-deflection and stress-strain curves. The slope of the stress-strain curve is the and stress-strain curves. The slope of the stress-strain curve is the

elastic elastic

modulus (E) and is proportional to the stiffness.modulus (E) and is proportional to the stiffness.

ResilienceResilience

Resilience is the area under the Resilience is the area under the curve out to the proportional limit. curve out to the proportional limit.

Resilience represents the energy Resilience represents the energy capacity of the material that is a capacity of the material that is a combination of the strength and combination of the strength and stiffness stiffness

Formability:Formability:

Formability is the amount of permanent Formability is the amount of permanent deformation that a material can withstand deformation that a material can withstand before breaking.before breaking.

(It represents total amount of permanent (It represents total amount of permanent bending a wire will tolerate before it bending a wire will tolerate before it breaks)breaks)

It is represented by the area under the It is represented by the area under the curve between yield stress and tensile curve between yield stress and tensile strength.strength.

Bauschinger Effect as described by A.J. Bauschinger Effect as described by A.J. WilcockWilcock::

This phenomenon was discovered by This phenomenon was discovered by Dr. Bauschinger in Dr. Bauschinger in 1886 (Mugharabi 1987)1886 (Mugharabi 1987). He observed the relationship . He observed the relationship between permanent deformation and loss of yield strength between permanent deformation and loss of yield strength and found that if the metal was permanently deformed in and found that if the metal was permanently deformed in one direction then, it reduced its yield strength in the one direction then, it reduced its yield strength in the opposite direction. If a straight wire of wire is bent so that opposite direction. If a straight wire of wire is bent so that permanent deformation occurs and an attempt is made to permanent deformation occurs and an attempt is made to increase the magnitude, bending in the same direction as increase the magnitude, bending in the same direction as had originally be done, the wire is more resistant to had originally be done, the wire is more resistant to permanent deformation than if an attempt had been made permanent deformation than if an attempt had been made to bend in the opposite direction. The wire is more resistant to bend in the opposite direction. The wire is more resistant to permanent deformation because a certain residual stress to permanent deformation because a certain residual stress remains in it, after placement of first bend. A flexibly remains in it, after placement of first bend. A flexibly member will not deform as easily if it is activated in the member will not deform as easily if it is activated in the same direction as the original bends were made to form the same direction as the original bends were made to form the configuration. If a bend is made in an orthodontic appliance configuration. If a bend is made in an orthodontic appliance the maximum elastic load is not the same in all direction: it the maximum elastic load is not the same in all direction: it is greatest in the direction identical to the original direction is greatest in the direction identical to the original direction of bending or twisting. The phenomenon responsible for of bending or twisting. The phenomenon responsible for this difference is known as Bauschinger Effect.this difference is known as Bauschinger Effect.

Two noteworthy points about this effect are:Two noteworthy points about this effect are:

1.1. Plastic prestrain increases the elastic limit of deformation in Plastic prestrain increases the elastic limit of deformation in the same direction as the prestrain.the same direction as the prestrain.

2.2. Plastic prestrain decreases the elastic limit of Plastic prestrain decreases the elastic limit of deformation in the direction reverse to prestrain. If the deformation in the direction reverse to prestrain. If the magnitude of prestrain is increased, the elastic limit in the magnitude of prestrain is increased, the elastic limit in the reverse direction can reduce to zero.reverse direction can reduce to zero.

Dr. Bauschinger said that plastic deformation in the absence Dr. Bauschinger said that plastic deformation in the absence of dislocation locking will not achieve as high a yield point. of dislocation locking will not achieve as high a yield point. Furthermore if the material is subjected to reverse straining Furthermore if the material is subjected to reverse straining it will posses an even lower yield point in the reverse it will posses an even lower yield point in the reverse direction.direction.

This effect can be used to advantage after wire bending This effect can be used to advantage after wire bending because of the residual stresses left in the material, because of the residual stresses left in the material, improving its elastic properties in the direction to which the improving its elastic properties in the direction to which the wire has been deformed.wire has been deformed.

MANUFCTURING OF ORTHODONTIC MANUFCTURING OF ORTHODONTIC

WIRESWIRES

Manufacture:Manufacture: AISI , AISI ,specially for orthodontic specially for orthodontic

purposespurposes

Various steps – Various steps –

1.1. MeltingMelting

2.2. Ingot FormationIngot Formation

3.3. RollingRolling

4.4. DrawingDrawing

MeltingMelting : The selection and melting of the components of : The selection and melting of the components of alloys influence the physical properties of metals. alloys influence the physical properties of metals.

Ingot formationIngot formation : An ingot is produced by the pouring of : An ingot is produced by the pouring of molten alloy into a mold. It is one of the critical operations. molten alloy into a mold. It is one of the critical operations.

RollingRolling : It is the first mechanical step in the manufacture of a : It is the first mechanical step in the manufacture of a wire from the ingot. The ingot is rolled into a long bar by a wire from the ingot. The ingot is rolled into a long bar by a series of rollers that gradually reduce it to a relatively small series of rollers that gradually reduce it to a relatively small diameter. diameter.

DrawingDrawing : It is a more precise process by which the ingot is : It is a more precise process by which the ingot is reduced to its final size. The wire is pulled through a small hole reduced to its final size. The wire is pulled through a small hole in a die. The size of the hole is slightly smaller than the in a die. The size of the hole is slightly smaller than the starting diameter of the wire, in order to facilitate uniform starting diameter of the wire, in order to facilitate uniform squeezing of the wire from all sides by the walls of the die as it squeezing of the wire from all sides by the walls of the die as it passes through, reducing the wire to the diameter of the die. passes through, reducing the wire to the diameter of the die.

PROCESS OF MANUFACTURE:PROCESS OF MANUFACTURE: Spinner Straightening:Spinner Straightening: It is the mechanical process of straightening resistant materials, usually It is the mechanical process of straightening resistant materials, usually

in the cold drawn condition. The wire is pulled through rotating bronze in the cold drawn condition. The wire is pulled through rotating bronze rollers that torsionally twist it into straight condition rollers that torsionally twist it into straight condition

Pulse Straightening:Pulse Straightening: It was founded by Mr. A.J. Wilcock. The wire is pulsed in special machines It was founded by Mr. A.J. Wilcock. The wire is pulsed in special machines

that permit high tensile wires to be straightened. that permit high tensile wires to be straightened.

Stress Relief Of Stainless SteelStress Relief Of Stainless Steel One of the steps in manufacture or at the time of clinical application is One of the steps in manufacture or at the time of clinical application is

“Stress Relieving” . It is a level of heat treatment at which internal “Stress Relieving” . It is a level of heat treatment at which internal stresses are relieved by minute slippages and readjustments in stresses are relieved by minute slippages and readjustments in intergranular relations without the loss of hardening that accompanies the intergranular relations without the loss of hardening that accompanies the higher temperature process of annealing.higher temperature process of annealing.

Work Hardening / Strain HardeningWork Hardening / Strain Hardening In a polycrystalline metal there is a build up of dislocations at the grain In a polycrystalline metal there is a build up of dislocations at the grain

boundaries and occurs on intersecting slip planes. Later point defect boundaries and occurs on intersecting slip planes. Later point defect increases and entire grain gets distorted leading to increased stress increases and entire grain gets distorted leading to increased stress required to cause further slip, leading to stronger, harder and less ductile required to cause further slip, leading to stronger, harder and less ductile metal with less resistance to tarnish and corrosion.metal with less resistance to tarnish and corrosion.

Cold WorkingCold Working It is the process of deforming a metal at room temperature.It is the process of deforming a metal at room temperature.

AnnealingAnnealing

It is the process in which the effects associated with cold It is the process in which the effects associated with cold working (for example: strain hardening, lowered ductility and working (for example: strain hardening, lowered ductility and distorted grains) can be reversed by simply heating the metal.distorted grains) can be reversed by simply heating the metal.

Annealing generally comprises of Annealing generally comprises of 3 stages3 stages:: RecoveryRecovery RecrystallizationRecrystallization Grain growthGrain growth TemperingTempering:: It is the process of reheating steel to intermediate temperature It is the process of reheating steel to intermediate temperature

ranges (usually below 1000°F [525 °C] under carefully controlled ranges (usually below 1000°F [525 °C] under carefully controlled conditions to permit a partial transformation into softer forms. conditions to permit a partial transformation into softer forms. This is done to remedy steel which when quenched in water This is done to remedy steel which when quenched in water results in very brittle martensite that is unsuitable for most results in very brittle martensite that is unsuitable for most mechanical applications.mechanical applications.

Forms of SteelForms of Steel At high temperatures (more than 1400 to 1500°F / 750 to At high temperatures (more than 1400 to 1500°F / 750 to

800°C) steel is a homogenous material with all of the 800°C) steel is a homogenous material with all of the carbon in solid solution in the iron. At this temperature, the carbon in solid solution in the iron. At this temperature, the iron carbide is completely decomposed. This form of steel is iron carbide is completely decomposed. This form of steel is called "Austenite".called "Austenite".

At low temperatures (less than 450°F / 225°C), an almost At low temperatures (less than 450°F / 225°C), an almost pure cementite, the hardest and most brittle form of iron- pure cementite, the hardest and most brittle form of iron- carbon combination called "Martensite" is formed. carbon combination called "Martensite" is formed.

Between these high and low extremes of temperature Between these high and low extremes of temperature many intermediate phases are formed. These are various many intermediate phases are formed. These are various mixtures of ferrite and cementite, with crystal structures mixtures of ferrite and cementite, with crystal structures tending toward hardness in the low temperature ranges tending toward hardness in the low temperature ranges and toward softness and ductility at higher temperatures.and toward softness and ductility at higher temperatures.

WIRE ALLOYSWIRE ALLOYS

GOLD ALLOYSGOLD ALLOYS

Their composition is very similar to the Their composition is very similar to the Type IV gold casting alloys. The Type IV gold casting alloys. The typical composition of the alloy is as typical composition of the alloy is as follows-follows-

Gold – 15 – 65% (55-65% more typical)Gold – 15 – 65% (55-65% more typical) Copper – 11 – 18%Copper – 11 – 18% Silver – 10 – 25%Silver – 10 – 25% Nickel – 5 – 10%Nickel – 5 – 10%

The alloys contain quite a high amount The alloys contain quite a high amount about (20 – 25%) of palladium. Platinum is about (20 – 25%) of palladium. Platinum is also present and in presence of palladium, it also present and in presence of palladium, it raises the melting point of the alloys, and raises the melting point of the alloys, and makes it corrosion resistant.makes it corrosion resistant.

Copper incorporates strength to the wire. Copper incorporates strength to the wire. They acquire additional strengthening They acquire additional strengthening through cold working, which is incorporated through cold working, which is incorporated during the wire drawing processduring the wire drawing process

This combination of properties makes gold This combination of properties makes gold very formable and capable of delivering very formable and capable of delivering lower forces than stainless steel. These lower forces than stainless steel. These wires are easily joined by soldering and the wires are easily joined by soldering and the joints are very corrosion resistant.joints are very corrosion resistant.

The gold wires are not used anymore in The gold wires are not used anymore in orthodontics mainly because of their low orthodontics mainly because of their low yield strength and increasing cost has made yield strength and increasing cost has made its use prohibitive.its use prohibitive.

HEAT TREATMENT OF GOLD WIREHEAT TREATMENT OF GOLD WIRE

The changes that are produced in the The changes that are produced in the strength and ductility of a wrought gold strength and ductility of a wrought gold alloy by heat treatment are due to the alloy by heat treatment are due to the alterations in the gold-copper compound alterations in the gold-copper compound present in the alloy.present in the alloy.

In order to uniformly soften most wrought In order to uniformly soften most wrought gold wire it is heated to 1300° F. for gold wire it is heated to 1300° F. for approximately 10 minutes and then approximately 10 minutes and then quenchedquenched

The wire is very soft and ductile and The wire is very soft and ductile and may be easily manipulatedmay be easily manipulated

If left standing at room temperature for If left standing at room temperature for several days, will become much harder. several days, will become much harder. This phenomenon is known as “age-This phenomenon is known as “age-hardening” or “precipitation-hardening” or “precipitation-hardening”. hardening”.

Other method: If, after quenching from Other method: If, after quenching from 1300° F. The wire is reheated to 1300° F. The wire is reheated to approximately 840° F. and allowed to approximately 840° F. and allowed to cool slowly from this temperature, the cool slowly from this temperature, the gold-copper compound tends to come gold-copper compound tends to come out of solution. out of solution.

By not using heat treatment procedures By not using heat treatment procedures the orthodontist is not obtaining the the orthodontist is not obtaining the maximum properties from this alloys.maximum properties from this alloys.

Besides precipitation hardening Besides precipitation hardening there are two other ways by which there are two other ways by which the strength of wrought gold wire the strength of wrought gold wire may be increased. One of these may be increased. One of these methods is cold working. The methods is cold working. The other method is to vary the other method is to vary the composition of the alloy composition of the alloy constituents.constituents.

STAINLESS STEELSTAINLESS STEEL Stainless Steel is defined as a alloy of iron Stainless Steel is defined as a alloy of iron

that is resistant to corrosion. It was that is resistant to corrosion. It was discovered accidentally in U.K. during discovered accidentally in U.K. during second world was by a Sheffield second world was by a Sheffield metallurgist metallurgist BREARLEYBREARLEY. It was patented . It was patented in 1917.in 1917.

Later chromium was added to it so that it Later chromium was added to it so that it gets a protective coating of chromium gets a protective coating of chromium oxide on it, hence improving the corrosion oxide on it, hence improving the corrosion resistantance.resistantance.

Types of stainless steelsTypes of stainless steels FERRITIC STAINLESS STEELFERRITIC STAINLESS STEEL ( (AISI series 400) It has good corrosion AISI series 400) It has good corrosion

resistance, is cheaply made. Disadvantage of this type of stainless resistance, is cheaply made. Disadvantage of this type of stainless steel is that it is not hard nor can it be hardened.steel is that it is not hard nor can it be hardened.

MARTENSITIC STAINLESS STEEL: (AISI series 400)MARTENSITIC STAINLESS STEEL: (AISI series 400) Alloys in the 400 Alloys in the 400 series contain little or no Nickel and are primarily alloys of Iron and series contain little or no Nickel and are primarily alloys of Iron and Chromium. They can be heat treated much the same as carbon steel to Chromium. They can be heat treated much the same as carbon steel to form martensite at room temperature. The low resistance to fracture form martensite at room temperature. The low resistance to fracture and high corrosion resistance of these alloys render them useful in the and high corrosion resistance of these alloys render them useful in the construction of orthodontic instruments. They are used in making construction of orthodontic instruments. They are used in making surgical and cutting instruments. The disadvantage in such type of surgical and cutting instruments. The disadvantage in such type of steel is its brittle nature.steel is its brittle nature.

AUSTENITIC STAINLESS STEELS (AISI series 302 & 304) They contain AUSTENITIC STAINLESS STEELS (AISI series 302 & 304) They contain Iron, Chromium 18%, Nickel 8% and 0.15% Carbon. The Nickel content Iron, Chromium 18%, Nickel 8% and 0.15% Carbon. The Nickel content has a stabilizing effect on austenite only at high temperatures, but in has a stabilizing effect on austenite only at high temperatures, but in the Chromium-Nickel steels, the austenite is stable even at room the Chromium-Nickel steels, the austenite is stable even at room temperature. Hence these alloys are called "Austenitic stainless steel". temperature. Hence these alloys are called "Austenitic stainless steel". Presence of Chromium in the alloy provides the austenite with the Presence of Chromium in the alloy provides the austenite with the necessary strength and high resistance to corrosion. Types 302 and necessary strength and high resistance to corrosion. Types 302 and 304 are commonly used in orthodontic appliances. They contain about 304 are commonly used in orthodontic appliances. They contain about 18% chromium and 8% Nickel and hence constitute the 18-8 group of 18% chromium and 8% Nickel and hence constitute the 18-8 group of stainless steels.stainless steels.

The austenitic stainless steel, because of the presence of The austenitic stainless steel, because of the presence of austenite, cannot be hardened by quenching or similar austenite, cannot be hardened by quenching or similar heat treatment. The only way to harden such steels is by heat treatment. The only way to harden such steels is by "cold working". Under cold working, the austenitic stainless "cold working". Under cold working, the austenitic stainless steels harden rapidly with the usual realignment of the steels harden rapidly with the usual realignment of the crystalline structure. Work hardening also brings about crystalline structure. Work hardening also brings about some transformation of part of the austenite to martensite, some transformation of part of the austenite to martensite, which adds to the hardening effect.which adds to the hardening effect.

The advantages of austenitic stainless steel areThe advantages of austenitic stainless steel are::1.1. Most corrosion resistant form.Most corrosion resistant form.2.2. Greater ductility.Greater ductility.3.3. Strengthening during cold working.Strengthening during cold working.4.4. Ease of welding.Ease of welding.5.5. Readily overcome sensitization.Readily overcome sensitization.6.6. Less critical grain growth.Less critical grain growth.7.7. Ease of forming.Ease of forming.

SENSITIZATIONSENSITIZATION

The 18-8 stainless steels may lose its The 18-8 stainless steels may lose its resistance to corrosion if it is heated resistance to corrosion if it is heated between 400-900between 400-9000 0 C due to C due to precipitation of chromium carbide at precipitation of chromium carbide at the grain boundaries the grain boundaries

Overcoming SensitizationOvercoming Sensitization

Reduce the carbon contentReduce the carbon content Cold workingCold working STABILIZATION: Addition of TitaniumSTABILIZATION: Addition of Titanium

HEAT TREATMENT OF STAINLESS HEAT TREATMENT OF STAINLESS STEELSTEEL

Done(400-500degree C) to Done(400-500degree C) to Eliminate some residual stress Eliminate some residual stress

resulting from wire manufacturing resulting from wire manufacturing and toand to

Prevent premature breakage of Prevent premature breakage of complex appliances during assemly.complex appliances during assemly.

Kemler: 700-800Kemler: 700-80000F for 5-15 F for 5-15 minutesminutes

Backofen and Gales: 750-820Backofen and Gales: 750-82000F for F for 10 minutes10 minutes

Funk: 850Funk: 85000F for 3 minutesF for 3 minutes

Properties:Properties: The modulus of elasticity ranges from 23 The modulus of elasticity ranges from 23

X 10X 1066 to 24X10 to 24X1066 psi. The wires have a very psi. The wires have a very high yield strength of 50,000-280,000 psi. high yield strength of 50,000-280,000 psi.

This wire is strong, has excellent This wire is strong, has excellent formability, adequate springback, offers formability, adequate springback, offers low frictional resistance, can be soldered, low frictional resistance, can be soldered, has good corrosion resistance & moderate has good corrosion resistance & moderate cost. cost.

By The 50’s Rocky Mountain By The 50’s Rocky Mountain Orthodontics offered two tempers Orthodontics offered two tempers of cold worked stainless steels: of cold worked stainless steels: Standard and extra hard gradeStandard and extra hard grade

Today American Orthodontics Today American Orthodontics advertises three grades of advertises three grades of stainless steel wires: stainless steel wires:

Standard, Standard, Gold Tone,Gold Tone, Super Gold ToneSuper Gold Tone

AUSTRALIAN ARCHWIRESAUSTRALIAN ARCHWIRES

Developed by Mr. A. J. Wilcock & Dr. Developed by Mr. A. J. Wilcock & Dr. P. R. BeggP. R. Begg

Acquaintance goes back to the war Acquaintance goes back to the war years at the University of Melbourne.years at the University of Melbourne.

Dr. Begg demanded a wire that Dr. Begg demanded a wire that remained active in the mouth for remained active in the mouth for long periods. long periods.

High Tensile wires were developedHigh Tensile wires were developed

Difficulties faced with high Difficulties faced with high tensile wires(1970s):tensile wires(1970s):

Impossible to straighten. Impossible to straighten.

Work softeningWork softening

Breakage of wireBreakage of wire


OVERCOMING THE DIFFICULTIESOVERCOMING THE DIFFICULTIES

Old method - Spinner Old method - Spinner straightening: Yield stress straightening: Yield stress decreases due to Bauschinger decreases due to Bauschinger effecteffect

New method - Pulse New method - Pulse straightening(1980s) : No plastic straightening(1980s) : No plastic deformation whatsoever.deformation whatsoever.

Advantages of Pulse Advantages of Pulse straighteningstraightening

Permits the highest tensile wire to Permits the highest tensile wire to be straightened, previously not be straightened, previously not possible. possible.

The material tensile yield stress is The material tensile yield stress is not suppressed in any way.not suppressed in any way.

The wire has a much smoother The wire has a much smoother appearance and hence less bracket appearance and hence less bracket friction.friction.

Mr. Wilcock, Jr.’s recommendations to Mr. Wilcock, Jr.’s recommendations to decrease breakage:decrease breakage:

Use the flat beakUse the flat beak Round the edges of the pliersRound the edges of the pliers

Warm the wireWarm the wire

Grades of wire availableGrades of wire available

The wires are marked in various sizes and grades ranging The wires are marked in various sizes and grades ranging from 0.008” to 0.002” and regular to supreme grade. from 0.008” to 0.002” and regular to supreme grade.

Regular with white labelRegular with white labelRegular plus with green label Regular plus with green label Special grade with black label Special grade with black label Special plus with orange label Special plus with orange label Extra special plus (ESP) with blue labelExtra special plus (ESP) with blue labelPremium with blue label Premium with blue label Premium plus Premium plus Supreme with blue labelSupreme with blue label

Regular grade is the least resilient and premium grade is Regular grade is the least resilient and premium grade is the most resilient of all the wiresthe most resilient of all the wires

PropertiesProperties The ultimate tensile strength for The ultimate tensile strength for

pulse-straightened wires is 8-12% pulse-straightened wires is 8-12%

higher than stainless steel wires.higher than stainless steel wires. The load-deflection rate is higherThe load-deflection rate is higher The pulse-straightened wires have a The pulse-straightened wires have a

significantly higher working range significantly higher working range

and recovery patterns.and recovery patterns. Frictional resistance of the pulse-Frictional resistance of the pulse-

straightened wires is lesserstraightened wires is lesser

Zero Stress Relaxation Zero Stress Relaxation

This is the ability of a wire to deliver This is the ability of a wire to deliver a constant light elastic force when a constant light elastic force when subjected to an external force or subjected to an external force or forces of occlusion.forces of occlusion.

This indicates that the wire should This indicates that the wire should have a very high and sharp yield have a very high and sharp yield point with low elongation.point with low elongation.

This is probably in the region of This is probably in the region of ‘special plus’ and above ‘special plus’ and above

The stiffness of an archwire can be The stiffness of an archwire can be varied in three ways.varied in three ways.

The first and traditional approach has The first and traditional approach has been to vary the dimensions of the wire. been to vary the dimensions of the wire. Small changes in dimensions can result Small changes in dimensions can result in large variations in stiffness.The in large variations in stiffness.The difference between .016” and .014” difference between .016” and .014” diameter is approximately 40%.diameter is approximately 40%.

The second approach to vary the elastic The second approach to vary the elastic modulus E. That is, use various archwire modulus E. That is, use various archwire materials such as Nitinol , Beta-materials such as Nitinol , Beta-Titanium, Gold alloys and stainless Titanium, Gold alloys and stainless steel.steel.

BRAIDED WIRESBRAIDED WIRES

A third approach, which is really an extension A third approach, which is really an extension of the second, is to build up a strand of of the second, is to build up a strand of stainless steel wire, for example, a core wire of stainless steel wire, for example, a core wire of .0065” and six .0055” wrap, wires will produce .0065” and six .0055” wrap, wires will produce an overall diameter approximately .0165 an overall diameter approximately .0165 inches. The reason why the strand has a more inches. The reason why the strand has a more flexible feel is due to the contact slip between flexible feel is due to the contact slip between adjacent wrap wires and the core wire of the adjacent wrap wires and the core wire of the stand.(COAXIAL WIRES)stand.(COAXIAL WIRES)

When the strand is deflected the wrap wires, When the strand is deflected the wrap wires, which are both under tension, and torsion will which are both under tension, and torsion will slip with respect to the core wire and each slip with respect to the core wire and each other. Providing there is only elastic other. Providing there is only elastic deformation each wire should return to its deformation each wire should return to its original position. original position.

Kusy and Dilley noted that the stiffness of a triple Kusy and Dilley noted that the stiffness of a triple stranded 0175” ( 3 X 008”) stainless steel arch wire stranded 0175” ( 3 X 008”) stainless steel arch wire was similar to that of 0.010” single stranded was similar to that of 0.010” single stranded stainless steel arch wire. The multistranded stainless steel arch wire. The multistranded archwire was also 25% stronger than the .010” archwire was also 25% stronger than the .010” stainless steel wire. stainless steel wire.

The .0175” triple stranded wire and .016” Nitinol The .0175” triple stranded wire and .016” Nitinol demonstrated a similar stiffness. However nitinol demonstrated a similar stiffness. However nitinol tolerated 50% greater activation than the tolerated 50% greater activation than the multistranded wire. multistranded wire.

The triple stranded wire was also half as stiff The triple stranded wire was also half as stiff as .016” beta-titanium.as .016” beta-titanium.

Multistranded wire can be used as a substitute to Multistranded wire can be used as a substitute to the newer alloy wire considering the cost of nickel the newer alloy wire considering the cost of nickel titanium wire.titanium wire.

COBALT-CHROMIUM-NICKEL COBALT-CHROMIUM-NICKEL ALLOYALLOY

Initially it was manufactured for watch springs Initially it was manufactured for watch springs by Elgin Watch Company, hence the name by Elgin Watch Company, hence the name ElgiloyElgiloy..

CONTENTSCONTENTS 40% Cobalt40% Cobalt 20% Chromium20% Chromium 15% Nickel15% Nickel 7% Molybdenum 7% Molybdenum 2% Manganese2% Manganese 0.15% Carbon0.15% Carbon 0.4% Beryllium0.4% Beryllium 15% Iron.15% Iron.

Types of ElgiloyTypes of ElgiloyAvailable in four tempers (levels of resilience)Available in four tempers (levels of resilience)

Blue Elgiloy(soft)Blue Elgiloy(soft) – can be bent easily – can be bent easily with fingers and pliers. with fingers and pliers.

Yellow Elgiloy(ductile)Yellow Elgiloy(ductile) – Relatively – Relatively ductile and more resilient than blue ductile and more resilient than blue Elgiloy. Elgiloy.

Green Elgiloy(semi-resilient)Green Elgiloy(semi-resilient) – More – More resilient than yellow Elgiloyresilient than yellow Elgiloy

Red Elgiloy(resilient)Red Elgiloy(resilient) -Most resilient -Most resilient of Elgiloy wiresof Elgiloy wires

All four alloy tempers have the same composition. All four alloy tempers have the same composition. (last three tempers have mechanical properties (last three tempers have mechanical properties similar to less expensive SS wires)similar to less expensive SS wires)

Differences in mechanical properties arise from Differences in mechanical properties arise from variations in the wire processing.variations in the wire processing.

As with SS alloys, the corrosion resistance of As with SS alloys, the corrosion resistance of Elgiloy arises from a thin passivating chromium Elgiloy arises from a thin passivating chromium oxide layer on the wire surface.oxide layer on the wire surface.

Popular because the as-received wire can easily Popular because the as-received wire can easily be manipulated into desired shapes and then be manipulated into desired shapes and then heat treated to achieve considerable increases in heat treated to achieve considerable increases in strength and resilience.strength and resilience.

HEAT TREATMENTHEAT TREATMENT

The ideal temperature for heat The ideal temperature for heat treatment is 900°F or 482°C for 7-12 treatment is 900°F or 482°C for 7-12 min in a dental furnace. min in a dental furnace.

This causes precipitation hardening This causes precipitation hardening of the alloy increasing the resistance of the alloy increasing the resistance of the wire to deformation.of the wire to deformation.

DisadvantagesDisadvantages Greater degree of work hardening Greater degree of work hardening High temperatures (above 1200°F) High temperatures (above 1200°F)

cause annealingcause annealing

AdvantagesAdvantages Greater resistance to fatigue and Greater resistance to fatigue and

distortiondistortion Longer function as a resilient springLonger function as a resilient spring High moduli of elasticityHigh moduli of elasticity

Comparison with stainless steelComparison with stainless steel

Values of modulus of elasticity (elastic Values of modulus of elasticity (elastic force delivery) for the Elgiloy Blue and SS force delivery) for the Elgiloy Blue and SS orthodontic wires are very similarorthodontic wires are very similar

Force delivery and joining characteristics Force delivery and joining characteristics are similar.are similar.

Contain comparable amount of nickel to Contain comparable amount of nickel to that found in the SS wires, which may that found in the SS wires, which may present concerns about biocompatibility.present concerns about biocompatibility.

Clinical applicationClinical application

Elgiloy Blue wires is used for Elgiloy Blue wires is used for fabrication of the fixed lingual quad-fabrication of the fixed lingual quad-helix appliance, which produces slow helix appliance, which produces slow maxillary expansion for the maxillary expansion for the treatment of maxillary constriction or treatment of maxillary constriction or crossbite in the primary and mixed crossbite in the primary and mixed dentitions.dentitions.

ALPHA TITANIUMALPHA TITANIUM

Pure titanium: Pure titanium: Below 885° C - hexagonal closed Below 885° C - hexagonal closed

packed or alpha lattice is stablepacked or alpha lattice is stable At higher temperature the metal At higher temperature the metal

rearranges into body centered cubic rearranges into body centered cubic or beta crystal.or beta crystal.

HCP- possesses fewer slip planes HCP- possesses fewer slip planes

Gets hardened by absorbing Gets hardened by absorbing intraoral free hydrogen ions, which intraoral free hydrogen ions, which turn it into titanium hydride, at the turn it into titanium hydride, at the oral temperature of 37°C and oral temperature of 37°C and 100% humidity. 100% humidity.

Any modifications if required Any modifications if required should be done within six weeks should be done within six weeks (Mollenhauer)(Mollenhauer)

BETA TITANIUM BETA TITANIUM (TITANIUM MOLYBDENUM ALLOY OR T.M.A.)(TITANIUM MOLYBDENUM ALLOY OR T.M.A.)

Introduced by Dr. Burstone (1980)Introduced by Dr. Burstone (1980)

CompositionComposition80% Titanium80% Titanium

11.5% Molybdenum11.5% Molybdenum

6% Zirconium6% Zirconium

4.5% Tin4.5% Tin

Advantages of TMA v/s NitinolAdvantages of TMA v/s Nitinol SmootherSmoother Can be weldedCan be welded Good formabilityGood formability

Advantages of TMA v/s S.S.Advantages of TMA v/s S.S. Gentler forcesGentler forces More rangeMore range Higher springbackHigher springback

Drawback: Drawback: High coefficient of frictionHigh coefficient of friction

Low friction TMALow friction TMA:: Introduced by OrmcoIntroduced by Ormco Done by ion implantation beam Done by ion implantation beam

mechanismmechanism

TMA TMA CCoolloouurrss:: Also developed by OrmcoAlso developed by Ormco Implantation of oxygen and nitrogen Implantation of oxygen and nitrogen

ions ions Ensures colour fastnessEnsures colour fastness

Welding of TMA wireWelding of TMA wire

POSITIONINGPOSITIONING- - Set down of 80%Set down of 80%

- 25 - 60 % recommended- 25 - 60 % recommended

Broad, flat electrodes One wire"set down" into the other.

Welding of TMA wireWelding of TMA wireBelow optimal - low strength, separation of Below optimal - low strength, separation of

wirewire

Optimal welding - good ductility strength Optimal welding - good ductility strength

atleast 90% of unweld wireatleast 90% of unweld wire

Higher than optimal - good strength, low ductilityHigher than optimal - good strength, low ductility

High voltage - Wire become brittleHigh voltage - Wire become brittle

Complete burnoutComplete burnout


Round wires - Simple to weld. Round wires - Simple to weld. - Require lower voltages- Require lower voltages

SMALLER CONTACT AREASMALLER CONTACT AREA- Low voltage- Low voltage- Point contact- Point contact- ‘‘T’ jointT’ joint

SINGLE PULSESINGLE PULSE- Short duration.- Short duration.

TMA wire can be welded to TMA wireTMA wire can be welded to TMA wire Not possible to weld TMA to SSNot possible to weld TMA to SS


Improper WeldingImproper Welding

Low voltage Low voltage - The parts may - The parts may

delaminatedelaminate

High voltage High voltage - Wire become brittle- Wire become brittle

CracksCracks

MeltingMelting

NICKEL-TITANIUM ALLOYSNICKEL-TITANIUM ALLOYS

CONVENTIONAL - NITINOLCONVENTIONAL - NITINOL

SUPERELASTICSUPERELASTIC

Pseudoelastic-Japanese NiTiPseudoelastic-Japanese NiTi

Thermo elastic-Cu NiTi.Thermo elastic-Cu NiTi.


2 forms of NiTi alloys2 forms of NiTi alloys

1. Martensite – Face centered (close 1. Martensite – Face centered (close

packed hexagonal).packed hexagonal).

2. Austenite – Body centered 2. Austenite – Body centered

cubic/tetragonal lattice.cubic/tetragonal lattice.

NICKEL-TITANIUMNICKEL-TITANIUM

HYSTERESISHYSTERESIS

• The transformation at different temperatures.The transformation at different temperatures.

• The difference between cooling and heating. The difference between cooling and heating.

• The range for most binary alloys is 40The range for most binary alloys is 400 0 – 60– 6000

NITINOLNITINOL Was invented in early 60’s by Was invented in early 60’s by William F. BuchlerWilliam F. Buchler, ,

a researcher metallurgist of the a researcher metallurgist of the Naval Ordinance Naval Ordinance LaboratoryLaboratory in Silver Springs, Maryland in Silver Springs, Maryland

The name Nitinol is given for NI for nickel, TI for The name Nitinol is given for NI for nickel, TI for titanium and NOL for Naval Ordinance Laboratory. titanium and NOL for Naval Ordinance Laboratory.

It was initially developed for space programs but It was initially developed for space programs but was first introduced into dentistry by Unitek was first introduced into dentistry by Unitek cooperation in 1970’s .cooperation in 1970’s .

Clinical use of Nitinol wire started in May 1972 by Clinical use of Nitinol wire started in May 1972 by

G.F.ANDREASEN et al.G.F.ANDREASEN et al.

NITINOLNITINOL

NiTi wires have two remarkable properties which makes its NiTi wires have two remarkable properties which makes its use in dentistry:use in dentistry:

SHAPE MEMORYSHAPE MEMORY The characteristic of being able to return to a previously The characteristic of being able to return to a previously

manufactured shape when it is heated to a TTR.manufactured shape when it is heated to a TTR. Ability of the material to remember its original shape after being Ability of the material to remember its original shape after being

plastically deformed while in the martensitic form. plastically deformed while in the martensitic form.

Superelasticity:Superelasticity:

Superelasticity means the ability of the wire to exert the same Superelasticity means the ability of the wire to exert the same force whether it is deflected a relatively small or a large force whether it is deflected a relatively small or a large distance. This can be produced by stress, not by temperature distance. This can be produced by stress, not by temperature difference and is called stress induced martensitic difference and is called stress induced martensitic transformation. transformation.

NITINOLNITINOL

In orthodontic applicationsIn orthodontic applications

1. Requires fewer arch wire changes.1. Requires fewer arch wire changes.

2. Requires less chair time.2. Requires less chair time.

3. Shortens the time required to accomplish the3. Shortens the time required to accomplish the

rotations and levelingrotations and leveling

4. Produces less patient discomfort.4. Produces less patient discomfort.

NITINOLNITINOL

PHYSICALPHYSICAL PROPERTIESPROPERTIES

Material Material propertyproperty

NitinolNitinol Stainless Stainless steelsteel

AlloyAlloy Nickel, TitaniumNickel, Titanium Iron, Iron, Chrome,NickelChrome,Nickel

Ultimate strengthUltimate strength 230,000 to 230,000 to 250,000 p.s.i250,000 p.s.i

280,000 to 280,000 to 300,000 p.s.i300,000 p.s.i

Modulus of Modulus of elasticity elasticity

4.8 x104.8 x106 6 p.s.ip.s.i 28.5 x 1028.5 x 1066 p.s.i p.s.i

NITINOLNITINOL

STORED ENERGY COMPARISONSSTORED ENERGY COMPARISONS

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

NITINOLNITINOL

CLINICAL APPLICATIONSCLINICAL APPLICATIONSClass I ,II,III malocclusions in both extraction Class I ,II,III malocclusions in both extraction

and non extraction cases and non extraction cases

NITINOLNITINOL Primary criterion – Amount of malalignment Primary criterion – Amount of malalignment

from the ideal arch form. from the ideal arch form. More the deflection – more the benefit. More the deflection – more the benefit.

NITINOLNITINOL

Imp benefits - a rectangular wire is inserted Imp benefits - a rectangular wire is inserted

early in the treatment. early in the treatment. Simultaneous rotation, leveling, tipping and Simultaneous rotation, leveling, tipping and

torquing can be accomplished earlier with a torquing can be accomplished earlier with a

resilient rectangular wire, resilient rectangular wire,

Cross bite correctionCross bite correction

Uprighting impacted caninesUprighting impacted canines

Opening the biteOpening the bite

NITINOLNITINOL

NITINOLNITINOL LIMITATIONSLIMITATIONS

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

instruments.instruments.

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

edge.edge.

3.The bending of loops or omega bends are not 3.The bending of loops or omega bends are not

recommended. ( especially closing loops ). recommended. ( especially closing loops ).

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

annealing the wire.annealing the wire.

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

of failure.of failure.

6. Cinch – backs.6. Cinch – backs.

- Annealing - Dark blue color flame.Annealing - Dark blue color flame.

- Cherry red flame – brittle.Cherry red flame – brittle.

Phase - TransformationPhase - Transformation

AUSTENITE PHASEAUSTENITE PHASE

MARTENSITE PHASEMARTENSITE PHASE

Martensite start(MS)Martensite start(MS)

Martensite finish(MF)Martensite finish(MF)

Austenite start(AS)Austenite start(AS)

Austenite finish(AF)Austenite finish(AF)


SUPERELASTICSUPERELASTIC

Chinese NiTi Chinese NiTi

Pseudoelastic-Japanese NiTiPseudoelastic-Japanese NiTi

Thermo elastic-Cu NiTi.Thermo elastic-Cu NiTi.

CHINESE NITI WIRECHINESE NITI WIRE CHINESE NiTi wire - A new orthodontic wire CHINESE NiTi wire - A new orthodontic wire

- C. J. BURSTONE ( AJO - C. J. BURSTONE ( AJO

JUNE 1985) JUNE 1985)

New NiTi by Dr.Tien Hua Cheng and New NiTi by Dr.Tien Hua Cheng and

associates at the General Research Institute associates at the General Research Institute

for non Ferrous Metals, in Beijing, China. for non Ferrous Metals, in Beijing, China.

Austenitic parent phase + Little work Austenitic parent phase + Little work

hardenedhardened

Chinese NiTi wire has much Chinese NiTi wire has much lower transitionallower transitional

temperaturetemperature than NiTi wire.than NiTi wire.

CHINESE NITI WIRECHINESE NITI WIRE

1. Applicable in situations where 1. Applicable in situations where large large

deflectionsdeflections are required. are required.

2. When tooth are 2. When tooth are badly malpositoned.badly malpositoned.

3. Niti wire deformation is 3. Niti wire deformation is not time dependentnot time dependent

CLINICAL SIGNIFICANCE

JAPANESE NITIJAPANESE NITI

The super - elastic property of the Japanese NiTi alloy The super - elastic property of the Japanese NiTi alloy

wire for use in orthodontics.wire for use in orthodontics.

- Fujio Miura et al ( AJODO July 1986 ) - Fujio Miura et al ( AJODO July 1986 )

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

new type of alloynew type of alloy

1. High spring back.1. High spring back.

2. Shape memory.2. Shape memory.

3. Super elasticity.3. Super elasticity.

CLINICAL IMPLICATIONSCLINICAL IMPLICATIONS

Alignment of badly malposed Alignment of badly malposed

teethteeth Distalize the molarDistalize the molar Expansion of archExpansion of arch Gain/Close the spaceGain/Close the space Periodontally compromised ptsPeriodontally compromised pts


CLINICAL APPLICATIONS CLINICAL APPLICATIONS

INITIALINITIAL

TWO MONTHS LATERTWO MONTHS LATER

CLINICAL APPLICATIONS CLINICAL APPLICATIONS

COPPER NiTiCOPPER NiTi

• Introduced by Rohit sachdevaIntroduced by Rohit sachdeva

• It has the advantage of generating more It has the advantage of generating more

constant forces than any other super constant forces than any other super

elastic nickel titanium alloys.elastic nickel titanium alloys.

• More resistant to deformationMore resistant to deformation

QUATERNARY METALQUATERNARY METAL – –

Nickel, Titanium, Copper, Chromium.Nickel, Titanium, Copper, Chromium.

Copper enhances thermal reactive Copper enhances thermal reactive

properties and creates a consistent properties and creates a consistent

unloading force. unloading force.


VARIABLE TRANSFORMATION VARIABLE TRANSFORMATION

TEMPERATURE ORTHODONTICS TEMPERATURE ORTHODONTICS

- -

ROHIT C. L. SACHDEVA.ROHIT C. L. SACHDEVA.


CLASSIFICATIONCLASSIFICATION

Type I Af – 15Type I Af – 1500 c c

Type II Af - 27Type II Af - 2700 c-MOUTH BREATHERS c-MOUTH BREATHERS

Type III Af - 35Type III Af - 3500c-c-

Type IV Af - 40Type IV Af - 4000c-ONLY AFTER c-ONLY AFTER CONSUMING HOT FOOD AND BEVERAGESCONSUMING HOT FOOD AND BEVERAGES


ADVANTAGES OF COPPER NiTi ALLOYS ADVANTAGES OF COPPER NiTi ALLOYS

OVER OTHER NiTi WIRESOVER OTHER NiTi WIRES

- Smaller loading force for the same degree of Smaller loading force for the same degree of

deformation. (20% less )deformation. (20% less )

- Reduced hysteresis makes to exert - Reduced hysteresis makes to exert

consistent tooth movement and reduced consistent tooth movement and reduced

trauma.trauma.

Clinical ApplicationsClinical Applications

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

frequentlyfrequently

DISADVANTAGESDISADVANTAGES Bracket friction will be more when large wires Bracket friction will be more when large wires

are used are used

ADVANTAGES

ESTHETIC ARCHWIRESESTHETIC ARCHWIRES

Composites: can be composed of Composites: can be composed of ceramic fibers that are embedded ceramic fibers that are embedded in a linear or cross-linked in a linear or cross-linked polymeric matrix. polymeric matrix.

Developed by a process known as Developed by a process known as pultrusionpultrusion

A prototype (reported by Kusy) shows the following A prototype (reported by Kusy) shows the following characteristics:characteristics:

Tooth colouredTooth coloured Adequate strengthAdequate strength Variable stiffnessVariable stiffness Resilience and springback comparable to NitiResilience and springback comparable to Niti

Low friction (beta staging)Low friction (beta staging) Enhanced biocompatibility (beta staging)Enhanced biocompatibility (beta staging)

(Formability, weldability are unknown)(Formability, weldability are unknown)

OPTIFLEXOPTIFLEX

Made of clear optical fibre; comprises of three Made of clear optical fibre; comprises of three layers:layers:

1. A silicon dioxide core 1. A silicon dioxide core

2. A silicon resin middle layer2. A silicon resin middle layer

3. A stain resistant nylon outer layer3. A stain resistant nylon outer layer

Silicon Dioxide Core Nylon Outer Layer

Silicon resin Middle Layer

PropertiesProperties

The most esthetic orthodontic arch The most esthetic orthodontic arch wire to date.wire to date.

Completely stain resistantCompletely stain resistant Exerts light continuous forcesExerts light continuous forces Very flexibleVery flexible

Precautions to be taken with Precautions to be taken with OptiflexOptiflex

Use elastomeric ligatures. Use elastomeric ligatures. No Sharp bendsNo Sharp bends Avoid using instruments with sharp edges, Avoid using instruments with sharp edges,

like the scalers etc., to force the wire into like the scalers etc., to force the wire into the bracket slot. the bracket slot.

Use the (501) mini distal end cutter (AEZ)Use the (501) mini distal end cutter (AEZ) No rough diet No rough diet Do not “cinch Back”Do not “cinch Back”

Other esthetic archwiresOther esthetic archwires

E.T.E. coated Nickel Titanium: E.T.E. E.T.E. coated Nickel Titanium: E.T.E. is an abbreviation for ELASTOMERIC is an abbreviation for ELASTOMERIC POLY TETRA FLORETHYLENE POLY TETRA FLORETHYLENE EMULSIONEMULSION

Stainless steel or Nickel titanium Stainless steel or Nickel titanium arch wire bonded to a tooth coloured arch wire bonded to a tooth coloured EPOXY coatingEPOXY coating

Cross-section Cross-section 1970s: Only S.S.; 1970s: Only S.S.;

varying the cross-sectional diameter)varying the cross-sectional diameter)

v/s v/s ModulusModulus

(1980s: S.S., Niti, B-Ti; varying the elastic (1980s: S.S., Niti, B-Ti; varying the elastic modulus)modulus)

v/s v/s Transition temperature Transition temperature (1990s: Cu Niti; Varying TTR/Af)(1990s: Cu Niti; Varying TTR/Af)

APPLYING ARCHWIRESAPPLYING ARCHWIRES

PROPERTYPROPERTY SSSS ELGILOYELGILOY TMATMA NiTiNiTi

CostCost LowLow LowLow HighHigh HighHigh

Force Force DeliveryDelivery

HighHigh HighHigh IntermediateIntermediate LightLight

SpringbackSpringback LowLow LowLow IntermediateIntermediate HighHigh

Formability Formability ExcellentExcellent ExcellentExcellent ExcellentExcellent Poor Poor

Ease of Ease of joiningjoining

Must be Must be reinforced reinforced with solderwith solder

Must be Must be reinforced reinforced with with soldersolder

Weldable Weldable Cannot be Cannot be soldered or soldered or weldedwelded

FrictionFriction Lower Lower Lower Lower Higher Higher Higher Higher

BiocompatiBiocompatibility bility

Concern Concern Concern Concern ExcellentExcellent Concern Concern

Wire Wire alloyalloy

Composition (Wt%)Composition (Wt%) Modulus Modulus of of elasticity elasticity (Gpa)(Gpa)

Yield Yield strength strength (MPa)(MPa)

SpringbackSpringback

AustenitAustenitic ic

SSSS

17-20%Cr ,8-17-20%Cr ,8-12%Ni12%Ni

0.15%C(max) Rest-0.15%C(max) Rest-FeFe

160-160-180180

1100-1100-15001500

0.0060-0.0094 0.0060-0.0094 ArAr

0.0065-0.0099 0.0065-0.0099 HtHt

Co-Cr-Co-Cr-Ni Ni (Elgiloy (Elgiloy -Blue)-Blue)

40%Co, 20%Cr40%Co, 20%Cr

15%-Ni, 15.8%Fe, 15%-Ni, 15.8%Fe, 7%Mo, 2%Mn 7%Mo, 2%Mn 0.15%C, 0.04%Be0.15%C, 0.04%Be

160-160-190190

830-830-10001000

0.0045-0.0065 0.0045-0.0065 ArAr

0.0054-0.0074 0.0054-0.0074 HtHt

ββ--titanium titanium (TMA)(TMA)

77.8%Ti, 11.3%Mo, 77.8%Ti, 11.3%Mo, 6.6%Zr, 4.3%Sn6.6%Zr, 4.3%Sn 62-6962-69 690-970690-970 0.0094-0.0110.0094-0.011

NiTiNiTi 55%Ni, 45% Ti 55%Ni, 45% Ti (Approx)-& may (Approx)-& may contain small contain small amounts of Cuamounts of Cu

3434 210-410210-410 0.0058-0.0160.0058-0.016

IN SEARCH OF THE IDEAL IN SEARCH OF THE IDEAL ARCHWIRE..by KusyARCHWIRE..by Kusy

CONCLUSIONCONCLUSION It can be seen that there is not a single arch wire It can be seen that there is not a single arch wire

that meets all the requirements of the that meets all the requirements of the orthodontist. We still have a long way to go, in orthodontist. We still have a long way to go, in terms of finding the ‘ideal’ archwire. But, with terms of finding the ‘ideal’ archwire. But, with such rapid progress being made in science and such rapid progress being made in science and technology, I am sure that we will see significant technology, I am sure that we will see significant improvements in arch wires in the near future.improvements in arch wires in the near future.

Also, we must consider ourselves fortunate to Also, we must consider ourselves fortunate to have such a wide array of materials to choose have such a wide array of materials to choose from. Just imagine working with just a single type from. Just imagine working with just a single type of Gold alloy wire, like they used to not so long of Gold alloy wire, like they used to not so long ago. So we should appreciate this fact and try to ago. So we should appreciate this fact and try to make the most of what we have.make the most of what we have.

THANK YOUTHANK YOU


LIST OF REFERENCESLIST OF REFERENCES Applied Dental Materials: John F. Mc Cabe 7th Edition 1990 Applied Dental Materials: John F. Mc Cabe 7th Edition 1990

Blackwell Scientific Publication. Pg. 69.Blackwell Scientific Publication. Pg. 69. The Clinical handling of Dental Materials: Bernard G.N. Smith, The Clinical handling of Dental Materials: Bernard G.N. Smith,

Paul S. Wright, David Brown. WRIGHT Publications, 2nd Paul S. Wright, David Brown. WRIGHT Publications, 2nd Edition, 1994; Pg. 195-199.Edition, 1994; Pg. 195-199.

Howe G.L. Greener E.H., Crimmins D.S.: Mechanical properties Howe G.L. Greener E.H., Crimmins D.S.: Mechanical properties and stress relief of stainless steel orthodontic wire. AO 1968; and stress relief of stainless steel orthodontic wire. AO 1968; 38: 244-249.38: 244-249.

Andreasen G. Heilman H., Krell D.: Stiffness changes in Andreasen G. Heilman H., Krell D.: Stiffness changes in thermodynamic NiTinol with increasing temperature AO 1985; thermodynamic NiTinol with increasing temperature AO 1985; 55:120-126.55:120-126.

Edie J.W.: Andreasen G.F., Zaytoun M.P.: Surface corrosion of Edie J.W.: Andreasen G.F., Zaytoun M.P.: Surface corrosion of Nitinol and stainless steel under clinical conditions AO 1981; Nitinol and stainless steel under clinical conditions AO 1981; 51:319-324.51:319-324.

Miura F, Mogi M. Yoshiaki O: Japanese NiTi alloy wire use of Miura F, Mogi M. Yoshiaki O: Japanese NiTi alloy wire use of electric heat resistance treatment method EJO 198; 10; 187-electric heat resistance treatment method EJO 198; 10; 187-191.191.

Andreasen G.F., Murrow R.E. : Laboratory and clinical analyses Andreasen G.F., Murrow R.E. : Laboratory and clinical analyses of nitinol wire AJODO 1978; 73: 142-151.of nitinol wire AJODO 1978; 73: 142-151.

Evans T.J.W, Durning P: Orthodontic Product update – Aligning Evans T.J.W, Durning P: Orthodontic Product update – Aligning archwires, the shape of things to come? – A fourth and fifth archwires, the shape of things to come? – A fourth and fifth phase of force delivery. BJO 1996; 23:269-275.phase of force delivery. BJO 1996; 23:269-275.

Kusy R.P. : A review of contemporary archwires-Their Kusy R.P. : A review of contemporary archwires-Their properties and characteristics AO 1997; 67: 197-207.properties and characteristics AO 1997; 67: 197-207.

Wilcock A.J., Jr. : Applied materials engineering for Wilcock A.J., Jr. : Applied materials engineering for orthodontic wires. Aust. Jor. Orthod. 1989; V:22-29.orthodontic wires. Aust. Jor. Orthod. 1989; V:22-29.

Burstone C.J. Bai Q., Morton J.Y. : Chinese NiTi Wire – A Burstone C.J. Bai Q., Morton J.Y. : Chinese NiTi Wire – A new orthodontic alloy AJODO 1985; 87; 445-452.new orthodontic alloy AJODO 1985; 87; 445-452.

Fillmore G.M., Tomlinson J.L.: Heat treatment of Cobalt Fillmore G.M., Tomlinson J.L.: Heat treatment of Cobalt chromium alloys of various tempers AO : 1979; 49: 126-chromium alloys of various tempers AO : 1979; 49: 126-130.130.

Kohl R.W. : Metallurgy in orthodontics. AO 1964; 34: 37-Kohl R.W. : Metallurgy in orthodontics. AO 1964; 34: 37-42.42.

Waters N.E.: Orthodontic product update-Super elastic Waters N.E.: Orthodontic product update-Super elastic Nickel-Titanium wires. BJO 1992; 19: 319-322.Nickel-Titanium wires. BJO 1992; 19: 319-322.

Andreasen G.G., Hilleman T.B.: An evaluation of 55 Andreasen G.G., Hilleman T.B.: An evaluation of 55 Cobalt substituted NiTinol wire for the use in Cobalt substituted NiTinol wire for the use in orthodontics. JADA 1971; 82: 1373-1375.orthodontics. JADA 1971; 82: 1373-1375.

Beckoten W.A., Gales G.F.: Heat treated stainless steel Beckoten W.A., Gales G.F.: Heat treated stainless steel for orthodontics. AJODO 1952; 38: 755-765.for orthodontics. AJODO 1952; 38: 755-765.

Wilcock A..J., Jr: JCO Interview, JCO 1988; 22: 484-489.Wilcock A..J., Jr: JCO Interview, JCO 1988; 22: 484-489. Burstone C.J., Goldberg A.J.: Beta Titanium. A new Burstone C.J., Goldberg A.J.: Beta Titanium. A new

orthodontic alloy. AJODO 1980; 77; 121 –132.orthodontic alloy. AJODO 1980; 77; 121 –132. Kapilla S., Sachdeva R: Mechanical properties and Kapilla S., Sachdeva R: Mechanical properties and

clinical applications of orthdontic wires.clinical applications of orthdontic wires.

Miura F, Mogi M., Ohura Y and Humanaka H: The super-Miura F, Mogi M., Ohura Y and Humanaka H: The super-elastic property of Japanese NiTi alloy wire for use in elastic property of Japanese NiTi alloy wire for use in orthodontics AJODO 1986; 90:1-10.orthodontics AJODO 1986; 90:1-10.

Proffit W.R., Fields H.W Jr.: Contemporary orthodontics – Proffit W.R., Fields H.W Jr.: Contemporary orthodontics – Mosby 3rd Edition 2000 Pg 326-334.Mosby 3rd Edition 2000 Pg 326-334.

Thurow R.C.: Edgewise orthodontics. The C.V.Mosby Thurow R.C.: Edgewise orthodontics. The C.V.Mosby Company 1982 4th Edition. Graber T.M., Vanarsdall R.L. Company 1982 4th Edition. Graber T.M., Vanarsdall R.L. Jr: Orthodontics – Current principles and Techniques. Jr: Orthodontics – Current principles and Techniques. Mosby 1994 2nd Edition.Mosby 1994 2nd Edition.

Philips R.W.: Skinner’s Science of dental Materials Prism Philips R.W.: Skinner’s Science of dental Materials Prism Books Pvt. Ltd. 1991 – 9th Edition.Books Pvt. Ltd. 1991 – 9th Edition.

Craig R.G. : Restorative dental materials. The C.V. Craig R.G. : Restorative dental materials. The C.V. Mosby Co. 1989 8th Edition.Mosby Co. 1989 8th Edition.

Hudgine J.J.: The effect of long-term deflection on Hudgine J.J.: The effect of long-term deflection on permanent deformation of Nickel titanium archwires AO permanent deformation of Nickel titanium archwires AO 1990: 283-293.1990: 283-293.

Kusy R.P., Sterens L.E: Triple Stranded stainless steel Kusy R.P., Sterens L.E: Triple Stranded stainless steel wires 1987: 18-32.wires 1987: 18-32.

Sachdeva R.C.L.: Orthdontics for the next millennium. Sachdeva R.C.L.: Orthdontics for the next millennium. ORMCO Publishing.ORMCO Publishing.


Date post:	13-Apr-2015
Category:	Documents
Upload:	ndasifko
View:	661 times
Download:	29 times

73893775 Orthodontic Wires

Documents