Nickel titanium in orthodontics

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Nickel titanium in orthodontics

  1. 1. Nickel Titanium in OrthodonticsNickel Titanium in Orthodontics INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
  2. 2. Ni Ti alloy was discovered in early 1960sNi Ti alloy was discovered in early 1960s byby William F. BuehlerWilliam F. Buehler, a research, a research metallurgist at the Naval Ordnancemetallurgist at the Naval Ordnance Laboratory in Silver springs, Maryland.Laboratory in Silver springs, Maryland. key discovery occurred inkey discovery occurred in 1962,1962, when awhen a binary alloy composed of equi-atomicbinary alloy composed of equi-atomic nickel and titanium was found to exhibit anickel and titanium was found to exhibit a shape recovery effect when heated aftershape recovery effect when heated after being mechanically deformed.being mechanically deformed. www.indiandentalacademy.comwww.indiandentalacademy.com
  3. 3. Although other reversible phase changeAlthough other reversible phase change materials were known at the time, the Ni-Timaterials were known at the time, the Ni-Ti alloys showed a large recoverable strain valuealloys showed a large recoverable strain value when compared to other binary, ternary orwhen compared to other binary, ternary or quaternary shape memory alloy systems.quaternary shape memory alloy systems. Rumour has it that William Buehler, who wasRumour has it that William Buehler, who was working with high nickel-bearing alloys for gasworking with high nickel-bearing alloys for gas turbine components, left a small ingot of Ni-Titurbine components, left a small ingot of Ni-Ti alloy made in a vacuum melt furnace on a deskalloy made in a vacuum melt furnace on a desk in direct sunlight.in direct sunlight. www.indiandentalacademy.comwww.indiandentalacademy.com
  4. 4. When Buehler and his colleagues came backWhen Buehler and his colleagues came back from lunch, they noticed the ingot’s shape hadfrom lunch, they noticed the ingot’s shape had changedchanged The physical performance of the Ni-Ti alloyThe physical performance of the Ni-Ti alloy made it a landmark discovery, and the range ofmade it a landmark discovery, and the range of commercially viable applications that have beencommercially viable applications that have been found for the materials is proof of the importancefound for the materials is proof of the importance of the nickel-titanium shape memory alloys.of the nickel-titanium shape memory alloys. Buehler’s preliminary results led to developmentBuehler’s preliminary results led to development of the first Ni Ti orthodontic alloy 55% nickel andof the first Ni Ti orthodontic alloy 55% nickel and 45% titanium by pioneers such as45% titanium by pioneers such as AndreasenAndreasen and his colleagues in 1972.and his colleagues in 1972. www.indiandentalacademy.comwww.indiandentalacademy.com
  5. 5. TheThe Unitek CorporationUnitek Corporation licensed thelicensed the patent [1974] and offered a stabilizedpatent [1974] and offered a stabilized martensitic alloy (M-NiTi) that does notmartensitic alloy (M-NiTi) that does not exhibit any shape memory effect (SME)exhibit any shape memory effect (SME) under the name, Nitinol.under the name, Nitinol. Nitinol – Ni Ti Naval ordnance laboratory.Nitinol – Ni Ti Naval ordnance laboratory. It is a stabilized form of the alloy in whichIt is a stabilized form of the alloy in which work hardening has abolished the phasework hardening has abolished the phase transformationtransformation www.indiandentalacademy.comwww.indiandentalacademy.com
  6. 6. This alloy hasThis alloy has low elastic moduluslow elastic modulus andand highhigh rangerange The nickel-titanium wires contain approximatelyThe nickel-titanium wires contain approximately equiatomic proportionsequiatomic proportions of nickel and titanium,of nickel and titanium, and are based upon the intermetallic com-poundand are based upon the intermetallic com-pound NiTi (sometimes written as TiNi).NiTi (sometimes written as TiNi). Examination of the binary phase diagramExamination of the binary phase diagram reveals that some deviation from stoichiometryreveals that some deviation from stoichiometry is possible for NiTi.is possible for NiTi. www.indiandentalacademy.comwww.indiandentalacademy.com
  7. 7. www.indiandentalacademy.comwww.indiandentalacademy.com
  8. 8. BASIC CONCEPTS ABOUT NICKELBASIC CONCEPTS ABOUT NICKEL TITANIUM ALLOYSTITANIUM ALLOYS 11. ACTIVE :- A term that is used to describe an alloy that is capable of undergoing its anticipated phase transformation. 2. PASSIVE :- An alloy that is incapable of undergoing its anticipated phase transformation because extensive plastic deformation has suppressed the transition. www.indiandentalacademy.comwww.indiandentalacademy.com
  9. 9. AUSTENITEAUSTENITE :-:- High temperature phase of Nickel titaniumHigh temperature phase of Nickel titanium alloys isalloys is called Austenite . Like many ferrous alloys this austenitecalled Austenite . Like many ferrous alloys this austenite can transform to Martensite. It has gotcan transform to Martensite. It has got Body centeredBody centered cubic (BCC) structurecubic (BCC) structure. It is t. It is the stronger, higherhe stronger, higher temperature phase present in NiTi.temperature phase present in NiTi. MARTENSITIC TRASFORMATIONMARTENSITIC TRASFORMATION :-:- Process of phase transformation which isProcess of phase transformation which is DIFFUSIONLESS, occuring from within and without anyDIFFUSIONLESS, occuring from within and without any chemical change which results in transformation ofchemical change which results in transformation of Austenite (parent phase) to Martensite following rapidAustenite (parent phase) to Martensite following rapid cooling. It has gotcooling. It has got distorted monoclinic, triclinic or HCPdistorted monoclinic, triclinic or HCP structurestructure MMore deformable,ore deformable, lower temperature phaselower temperature phase present in NiTi.present in NiTi. www.indiandentalacademy.comwww.indiandentalacademy.com
  10. 10. TWINNING :- In certain metals that crystallize in Hexagonal closed pack (HCP) structure, deformation occurs by twinning. It refers to a movement that divides the lattice into two symmetric parts; these parts are no longer in the same plane but rather at a certain angle. e.g., :- NiTi alloys are characterized by multiple rather than single twining throughout the metal www.indiandentalacademy.comwww.indiandentalacademy.com
  11. 11. The resulting structure is caused by aThe resulting structure is caused by a reversible Bain transformationreversible Bain transformation [a[a rearrangement of atoms in the newrearrangement of atoms in the new phase], which is responsible for thephase], which is responsible for the alloy’s “alloy’s “Shape MemoryShape Memory” and” and SuperelasticitySuperelasticity, properties that derive, properties that derive from the twinning-detwinningfrom the twinning-detwinning mechanism.mechanism. www.indiandentalacademy.comwww.indiandentalacademy.com
  12. 12. When these alloys areWhen these alloys are subjected to highersubjected to higher temperature.temperature. ⇓⇓ DETWINNINGDETWINNING OCCURSOCCURS ⇓⇓ Alloy reverts to its originalAlloy reverts to its original shape.shape. (SHAPE(SHAPE MEMORY EFFECT).MEMORY EFFECT). www.indiandentalacademy.comwww.indiandentalacademy.com
  13. 13. Phase transformation terminologiesPhase transformation terminologies Shape MemoryShape Memory: The ability of certain alloys to: The ability of certain alloys to return to a predetermined shape upon heatingreturn to a predetermined shape upon heating via a phase transformation.via a phase transformation. Af TemperatureAf Temperature: The temperature at which a: The temperature at which a shape memory alloy ( SMA ) finishesshape memory alloy ( SMA ) finishes transforming to austenite upon heating.transforming to austenite upon heating. Ap TemperatureAp Temperature: The temperature at which the: The temperature at which the SMA is about 50% transformed to AusteniteSMA is about 50% transformed to Austenite upon heating.upon heating. www.indiandentalacademy.comwww.indiandentalacademy.com
  14. 14. As TemperatureAs Temperature: The temperature at which: The temperature at which the SMA starts transforming to Austenitethe SMA starts transforming to Austenite upon heating.upon heating. Mf TemperatureMf Temperature: The temperature at which: The temperature at which a SMA finishes transforming to Martensitea SMA finishes transforming to Martensite upon cooling.upon cooling. Mp TemperatureMp Temperature:: The temperature, at whichThe temperature, at which a SMA is about 50% transformed toa SMA is about 50% transformed to Martensite upon cooling.Martensite upon cooling. www.indiandentalacademy.comwww.indiandentalacademy.com
  15. 15. Ms TemperatureMs Temperature: The temperature at which: The temperature at which a SMA starts transforming to Martensitea SMA starts transforming to Martensite upon cooling.upon cooling. HysteresisHysteresis: The: The temperature differencetemperature difference between a phase transformation uponbetween a phase transformation upon heating and cooling. In NiTi alloys, it isheating and cooling. In NiTi alloys, it is generally measured as the differencegenerally measured as the difference between Ap and Mp.between Ap and Mp. www.indiandentalacademy.comwww.indiandentalacademy.com
  16. 16. www.indiandentalacademy.comwww.indiandentalacademy.com
  17. 17. Af tempratureAf temprature : Most important marker.: Most important marker. To exploit super elasticity to its fullestTo exploit super elasticity to its fullest potential, the working temperature ofpotential, the working temperature of orthodontic appliances should be greaterorthodontic appliances should be greater than Af temperature.than Af temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  18. 18. Phase TransformationPhase Transformation: The change from: The change from one alloy phase to another with a changeone alloy phase to another with a change in temperature, pressure, stress,in temperature, pressure, stress, chemistry, and/or time.chemistry, and/or time. R-phaseR-phase: A phase intermediate between: A phase intermediate between Martensite and Austenite that can form inMartensite and Austenite that can form in NiTi alloys under certain conditions.NiTi alloys under certain conditions. www.indiandentalacademy.comwww.indiandentalacademy.com
  19. 19. Thermoelastic Martensitic TransformationThermoelastic Martensitic Transformation: A: A diffusionless, thermally reversible phasediffusionless, thermally reversible phase transformation characterized by a crystaltransformation characterized by a crystal lattice distortion.lattice distortion. www.indiandentalacademy.comwww.indiandentalacademy.com
  20. 20. SuperelasticitySuperelasticity:: The springy, “rubber like”The springy, “rubber like” behaviour present in NiTi shape Memorybehaviour present in NiTi shape Memory AlloysAlloys at temperatures above the Afat temperatures above the Af temperature. The superelasticity arisestemperature. The superelasticity arises from the formation and reversal of stressfrom the formation and reversal of stress induced martensite.induced martensite. MMdd:: It is the highest temperature at whichIt is the highest temperature at which martensite formation can be induced bymartensite formation can be induced by stress.stress. www.indiandentalacademy.comwww.indiandentalacademy.com
  21. 21. Typical Loading And Unloading BehaviorTypical Loading And Unloading Behavior Of Superelastic NiTi.Of Superelastic NiTi. Part of the unusual nature of aPart of the unusual nature of a superelastic material like A-NITI is that itssuperelastic material like A-NITI is that its unloading curve differs from its loadingunloading curve differs from its loading curve (i.e.,the reversibility has an energycurve (i.e.,the reversibility has an energy loss associated with it [hysteresis]).loss associated with it [hysteresis]). www.indiandentalacademy.comwww.indiandentalacademy.com
  22. 22. Stress strain diagram of alloy with superelastic behaviour www.indiandentalacademy.comwww.indiandentalacademy.com
  23. 23. This means theThis means the force that it delivers isforce that it delivers is not the same as thenot the same as the force applied toforce applied to activate it.activate it. www.indiandentalacademy.comwww.indiandentalacademy.com
  24. 24. www.indiandentalacademy.comwww.indiandentalacademy.com
  25. 25. The different loadingThe different loading and unloading curvesand unloading curves produce the evenproduce the even more remarkablemore remarkable effect that the forceeffect that the force delivered by an A-delivered by an A- NITI wire can beNITI wire can be changed duringchanged during clinical use merely byclinical use merely by releasing and retyingreleasing and retying it .it . Activation (to 80 degrees) and reactivation (to 40 degrees) curves for A-NiTi wire. www.indiandentalacademy.comwww.indiandentalacademy.com
  26. 26. Superelastic compounds generallySuperelastic compounds generally present a high stiffness in the initialpresent a high stiffness in the initial segment of the slope of the stress-strainsegment of the slope of the stress-strain graph when the deflection of the wire isgraph when the deflection of the wire is still minimum.still minimum. The initial activation force required forThe initial activation force required for autenitic NiTi can be 3 times greater thanautenitic NiTi can be 3 times greater than the force required to deflect a classic workthe force required to deflect a classic work hardened martensitic wire (nitinol).hardened martensitic wire (nitinol). www.indiandentalacademy.comwww.indiandentalacademy.com
  27. 27. www.indiandentalacademy.comwww.indiandentalacademy.com
  28. 28. Stainless steel Nickel Titanium www.indiandentalacademy.comwww.indiandentalacademy.com
  29. 29. INFLUENCE OF TREATMENT :-INFLUENCE OF TREATMENT :- Memory effects lasts only as long as twinning -Memory effects lasts only as long as twinning - detwinning phenomenon can take place.detwinning phenomenon can take place. When atoms slide against each other with a fullWhen atoms slide against each other with a full lattice unit – Irreversible transformationlattice unit – Irreversible transformation (permanent set) takes place.(permanent set) takes place. Consequently cold worked wires do not transformConsequently cold worked wires do not transform b’ coz of their high elasticityb’ coz of their high elasticity www.indiandentalacademy.comwww.indiandentalacademy.com
  30. 30. HysteresisHysteresis There is a difference in the transformationThere is a difference in the transformation temperatures upon heating from martensite totemperatures upon heating from martensite to austenite and cooling from austenite toaustenite and cooling from austenite to martensite, resulting in a delay or “lag” in themartensite, resulting in a delay or “lag” in the transformation.transformation. This difference known as the transformationThis difference known as the transformation temperaturetemperature hysteresis,hysteresis, is generally defined asis generally defined as the difference between the temperatures atthe difference between the temperatures at which the material is 50% transformed towhich the material is 50% transformed to austenite upon heating and 50% transformed toaustenite upon heating and 50% transformed to martensite upon cooling.martensite upon cooling. www.indiandentalacademy.comwww.indiandentalacademy.com
  31. 31. For NiTi Alloys, the difference between MpFor NiTi Alloys, the difference between Mp and Ap is 25-50and Ap is 25-50°°C.C. Thus Nitinol transformations exhibitThus Nitinol transformations exhibit thermal hysteresis,thermal hysteresis, MsMs ≠≠ Af and MfAf and Mf ≠≠ As.As. www.indiandentalacademy.comwww.indiandentalacademy.com
  32. 32. www.indiandentalacademy.comwww.indiandentalacademy.com
  33. 33. In addition to the hysteresis, the overall span of theIn addition to the hysteresis, the overall span of the transformation may be important. Typical values for thetransformation may be important. Typical values for the overall transformation temperature span are about 40-overall transformation temperature span are about 40- 7070°°C.C. Both the hysteresis and the overall transformationBoth the hysteresis and the overall transformation temperature span are slightly different for different NiTitemperature span are slightly different for different NiTi alloys. Further, alloying can greatly affect thealloys. Further, alloying can greatly affect the transformation hysteresis.transformation hysteresis. Copper additionsCopper additions have shownhave shown toto reduce the hysteresisreduce the hysteresis to about 10 to 15to about 10 to 15°°C andC and Niobium additions can expand the hysteresis overNiobium additions can expand the hysteresis over 100100°°C. ( Santaro AJO 2001)C. ( Santaro AJO 2001) www.indiandentalacademy.comwww.indiandentalacademy.com
  34. 34. Austenite and Martensite have differentAustenite and Martensite have different crystal structure and mechanicalcrystal structure and mechanical properties the most notable mechanicalproperties the most notable mechanical properties of Nitinol wires i.eproperties of Nitinol wires i.e superelasticity and shape memory aresuperelasticity and shape memory are result of reversible nature of Martensiticresult of reversible nature of Martensitic transformationtransformation www.indiandentalacademy.comwww.indiandentalacademy.com
  35. 35. Martensitic transformations do not occur at aMartensitic transformations do not occur at a precise temperature but rather within a rangeprecise temperature but rather within a range known asknown as temperature transition range(TTR)temperature transition range(TTR).. Range for most binary NiTi alloysRange for most binary NiTi alloys →→ 4040°° - 60- 60°° C.C. Transformation from Austenite to Martensite canTransformation from Austenite to Martensite can occur by.occur by. →→ Lowering the temperature.Lowering the temperature. →→ Applying stressApplying stress (Stress induced Martensite)(Stress induced Martensite) SIM.SIM. www.indiandentalacademy.comwww.indiandentalacademy.com
  36. 36. Specific TTR is a function of :-Specific TTR is a function of :- →→ Composition of the alloy.Composition of the alloy. →→ Processing history.Processing history. TTRS can be obtained from below roomTTRS can be obtained from below room temperature upto 275temperature upto 275°°F or higher.F or higher. e.g . Considering body temperature as referencee.g . Considering body temperature as reference -- TTR above that temperature – Alloy isTTR above that temperature – Alloy is Austentic (Rigid).Austentic (Rigid). TTR below that temperature – Alloys is MartensiticTTR below that temperature – Alloys is Martensitic (Superelastic)(Superelastic) www.indiandentalacademy.comwww.indiandentalacademy.com
  37. 37. EFFECTS OF ADDITIONS AND IMPURITIES ONEFFECTS OF ADDITIONS AND IMPURITIES ON TTR :-TTR :- Adding a third metal can lower the TTRAdding a third metal can lower the TTR →→ to as low as - 330to as low as - 330°° F ( - 200F ( - 200°° C).C). →→ Narrow the difference b/w cooling and heatingNarrow the difference b/w cooling and heating (Narrow Hysteresis).(Narrow Hysteresis). For thermally activated purposes mostFor thermally activated purposes most common third metals are Cu and Cocommon third metals are Cu and Co because.because. →→ Reduce the hysteresisReduce the hysteresis →→ Bring TTR close to body temperature.Bring TTR close to body temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  38. 38. Dissolved interstitial elements (small atomsDissolved interstitial elements (small atoms such as O, N and C) disrupt the matricessuch as O, N and C) disrupt the matrices which affects alloy shape memory andwhich affects alloy shape memory and super elasticity.super elasticity. Thermally respondent wires – designed soThermally respondent wires – designed so that composition , Annealing and coldthat composition , Annealing and cold working match Ms to temperature ofworking match Ms to temperature of human bodyhuman body www.indiandentalacademy.comwww.indiandentalacademy.com
  39. 39. Shape Memory is aShape Memory is a Combination ofCombination of Thermoelasticity andThermoelasticity and PseudoelasticityPseudoelasticity www.indiandentalacademy.comwww.indiandentalacademy.com
  40. 40. CLASSIFICATION OF NITI COMPOUNDSCLASSIFICATION OF NITI COMPOUNDS:: II.. Based on Transformation TemperatureBased on Transformation Temperature Ranges ( Waters,1992)Ranges ( Waters,1992) Group 1Group 1: Alloys with TTRs between room: Alloys with TTRs between room temperature and body temperature [Activetemperature and body temperature [Active Martensite].Martensite]. Group 2:Group 2: Alloys with TTR below roomAlloys with TTR below room temperature [Austenite active]temperature [Austenite active] GroupGroup 3: Alloys with TTR close to body3: Alloys with TTR close to body temperature, “which by virtue of the shapetemperature, “which by virtue of the shape memory effect spring back to their original shapememory effect spring back to their original shape when activated by body heat”.when activated by body heat”. www.indiandentalacademy.comwww.indiandentalacademy.com
  41. 41. Kusy ( 1991)Kusy ( 1991) classified NiTi into :classified NiTi into : Martensitic-stabilized alloysMartensitic-stabilized alloys - do not- do not possess shape memory or superpossess shape memory or super elasticity, because the processing of theelasticity, because the processing of the wire creates a stable martensitic structure.wire creates a stable martensitic structure. These are the non superelastic wire alloysThese are the non superelastic wire alloys such as originally developed Nitinol.such as originally developed Nitinol. www.indiandentalacademy.comwww.indiandentalacademy.com
  42. 42. Martensitic-active alloysMartensitic-active alloys - employ the- employ the thermoelastic effect to achieve shape memory;thermoelastic effect to achieve shape memory; the oral environment raises the temperature ofthe oral environment raises the temperature of the deformed arch wire with the martensiticthe deformed arch wire with the martensitic structure so that it transforms back to thestructure so that it transforms back to the austenitic structure and returns to the startingaustenitic structure and returns to the starting shape.shape. The clinician can observe this thermoelasticThe clinician can observe this thermoelastic shape memory if a deformed archwire segmentshape memory if a deformed archwire segment is warmed in the hands. These are the shape-is warmed in the hands. These are the shape- memory wire alloys such asmemory wire alloys such as Neo Sentalloy andNeo Sentalloy and Copper Ni-Ti.Copper Ni-Ti. www.indiandentalacademy.comwww.indiandentalacademy.com
  43. 43. Austenitic-active alloysAustenitic-active alloys - undergo a stress-- undergo a stress- induced martensitic (SIM) transformation wheninduced martensitic (SIM) transformation when activated. These alloys display superelasticactivated. These alloys display superelastic behavior , which is the mechanical analogue ofbehavior , which is the mechanical analogue of the thermoelastic shape-memory effect (SME).the thermoelastic shape-memory effect (SME). An austenitic-active alloy does not exhibitAn austenitic-active alloy does not exhibit thermoelastic behavior when a deformed wirethermoelastic behavior when a deformed wire segment is warmed in the hands. These alloyssegment is warmed in the hands. These alloys are the superelastic wires that do not possessare the superelastic wires that do not possess thermoelastic shape memory at the temperaturethermoelastic shape memory at the temperature of the oral environment, such asof the oral environment, such as Nitinol SE.Nitinol SE. www.indiandentalacademy.comwww.indiandentalacademy.com
  44. 44. Nickel Titanium WiresNickel Titanium Wires CONVENTIONAL NITINOLCONVENTIONAL NITINOL -- Original alloyOriginal alloy -- 55% Nickel55% Nickel,, 45% Titanium45% Titanium ratio ofratio of elements.elements. To modify mechanical properties andTo modify mechanical properties and transition temp. 1.6% Cobalt was added totransition temp. 1.6% Cobalt was added to itit www.indiandentalacademy.comwww.indiandentalacademy.com
  45. 45. CRYSTAL STRUCTURE:CRYSTAL STRUCTURE: --            Stabilized Martensitic formStabilized Martensitic form.. --        No application of phase transition effects.No application of phase transition effects. The family of Stabilized Martensitic alloysThe family of Stabilized Martensitic alloys now commercially available are referred tonow commercially available are referred to asas M – NiTiM – NiTi.. www.indiandentalacademy.comwww.indiandentalacademy.com
  46. 46. PROPERTIESPROPERTIES 1.1. Springback and FlexibilitySpringback and Flexibility Most advantageous properties of Nitinol areMost advantageous properties of Nitinol are Good Springback and Flexibility.Good Springback and Flexibility. Low force per unit of deactivation – that is lowLow force per unit of deactivation – that is low stiffness.stiffness. Nitinol wires have greater springback and largerNitinol wires have greater springback and larger recoverable energy than Stainless Steel orrecoverable energy than Stainless Steel or ββ-Ti-Ti when activated to same extent. High spring backwhen activated to same extent. High spring back is useful in circumstances that require largeis useful in circumstances that require large deflections but low forces.deflections but low forces. Delivers 1/5Delivers 1/5thth – 1/6– 1/6thth force per unit of deactivationforce per unit of deactivation www.indiandentalacademy.comwww.indiandentalacademy.com
  47. 47. 2.2. Spring Rate / Load Deflection RateSpring Rate / Load Deflection Rate:: Load deflection rate of Stainless Steel is twiceLoad deflection rate of Stainless Steel is twice that of Nitinol.that of Nitinol. Clinically this means that for any givenClinically this means that for any given malocclusion nitinol wire will produce a lower,malocclusion nitinol wire will produce a lower, more constant and continuous force on teethmore constant and continuous force on teeth than would a stainless steel wire of equivalentthan would a stainless steel wire of equivalent sizesize www.indiandentalacademy.comwww.indiandentalacademy.com
  48. 48. 3.3. Formability :Formability : Nitinol has poor formability.Nitinol has poor formability. Therefore best suited for preadjusted systems.Therefore best suited for preadjusted systems. -Bending also adversely effects springback-Bending also adversely effects springback property of this wire.property of this wire. -Bending of loops and stops in nitinol is not-Bending of loops and stops in nitinol is not recommended.recommended. - Any 1- Any 1stst , 2, 2ndnd and 3and 3rdrd order bends have to be overorder bends have to be over prescribed to obtain desired permanent bend.prescribed to obtain desired permanent bend. www.indiandentalacademy.comwww.indiandentalacademy.com
  49. 49. Cinch backs distal to molar tubes can be obtainedCinch backs distal to molar tubes can be obtained by flame annealing the end of wire. This makesby flame annealing the end of wire. This makes the wire dead soft and it can be bent into thethe wire dead soft and it can be bent into the preferred configuration.preferred configuration. A dark blue color indicates the desired annealingA dark blue color indicates the desired annealing temperature. Care should be taken not totemperature. Care should be taken not to overheat the wire because this makes it brittle.overheat the wire because this makes it brittle. www.indiandentalacademy.comwww.indiandentalacademy.com
  50. 50. 4.4. Shape MemoryShape Memory:: Andreasen and MorrowAndreasen and Morrow described the “shapedescribed the “shape memory” phenomenon as capability of wire tomemory” phenomenon as capability of wire to return to a previously manufactured shape whenreturn to a previously manufactured shape when it is heated through TTR.it is heated through TTR. Ironically the first 50 : 50 composition of Ni andIronically the first 50 : 50 composition of Ni and Ti was shape memory alloy (SMA) inTi was shape memory alloy (SMA) in composition only.composition only. Nitinol alloy isNitinol alloy is passivepassive.. SME had been suppressed by cold working theSME had been suppressed by cold working the wire during drawing to more than 8 – 10%.wire during drawing to more than 8 – 10%. www.indiandentalacademy.comwww.indiandentalacademy.com
  51. 51. 5.5. Joinability:Joinability: Not joinableNot joinable Since hooks cannot be bent or attached to Nitinol,Since hooks cannot be bent or attached to Nitinol, crimpable hooks and stops are recommended for use.crimpable hooks and stops are recommended for use. 6.6. FrictionFriction:: Garner, Allai and Moore (1986)Garner, Allai and Moore (1986) andand Kapila et al (1990):Kapila et al (1990): Noted that bracket wire frictional forces with nitinol wiresNoted that bracket wire frictional forces with nitinol wires are higher than those with SS wires and lower thanare higher than those with SS wires and lower than those withthose with ββ-Ti, in 0.018 inch slot.-Ti, in 0.018 inch slot. In 0.022 inch slot – NiTi andIn 0.022 inch slot – NiTi and ββ-Ti wires demonstrated-Ti wires demonstrated similar levels of friction.similar levels of friction. Although NiTi has greater surface roughness Beta –Ti hasAlthough NiTi has greater surface roughness Beta –Ti has greater frictional resistancegreater frictional resistance www.indiandentalacademy.comwww.indiandentalacademy.com
  52. 52. CLINICAL APPLICATIONS:CLINICAL APPLICATIONS: Levelling and Aligning:Levelling and Aligning: Nitinol wire is much more difficult to deform duringNitinol wire is much more difficult to deform during handling and seating into bracket slots is easier thanhandling and seating into bracket slots is easier than Stainless Steel arch wires.Stainless Steel arch wires. - Reduces loops formerly needed to level dentition.Reduces loops formerly needed to level dentition. - Can be used for longer periods of time without changing.- Can be used for longer periods of time without changing. -- www.indiandentalacademy.comwww.indiandentalacademy.com
  53. 53. Torque can be controlled early in treatment becauseTorque can be controlled early in treatment because successive arch wires fit with precision and case.successive arch wires fit with precision and case. The deactivation force released by superelastic NiTi forThe deactivation force released by superelastic NiTi for torque control is definitely lower than that released by antorque control is definitely lower than that released by an equivalent rectangular stainless steel wire, but theequivalent rectangular stainless steel wire, but the property is due more to the intrinsic elastic properties ofproperty is due more to the intrinsic elastic properties of NiTi compounds than to the presence of a phaseNiTi compounds than to the presence of a phase transformation.transformation. - Rectangular Nitinol inserted early in R- Rectangular Nitinol inserted early in Rxx – accomplishes– accomplishes simultaneous leveling, torquing and correction ofsimultaneous leveling, torquing and correction of rotations.rotations. -- www.indiandentalacademy.comwww.indiandentalacademy.com
  54. 54. Bite opening usingBite opening using RCS. (Reverse CurveRCS. (Reverse Curve of Spee)of Spee) www.indiandentalacademy.comwww.indiandentalacademy.com
  55. 55. ADVANTAGES :ADVANTAGES : - Fewer arch wire changes.- Fewer arch wire changes. - Less chair side time.- Less chair side time. - Less patient discomfort.- Less patient discomfort. Reduction in time to accomplish rotations.Reduction in time to accomplish rotations. www.indiandentalacademy.comwww.indiandentalacademy.com
  56. 56. LIMITATIONS:LIMITATIONS: - Poor formability.- Poor formability. - Poor joinability.- Poor joinability. - By its very nature nitinol is not a stiff wire- By its very nature nitinol is not a stiff wire which means that it can easily be deflected. Lowwhich means that it can easily be deflected. Low stiffness of nitinol provides inadequate stabilitystiffness of nitinol provides inadequate stability at completion of treatment. Such stability is oftenat completion of treatment. Such stability is often best maintained by using stiffer Stainless Steelbest maintained by using stiffer Stainless Steel wires tailored to the desired finished occlusion.wires tailored to the desired finished occlusion. - Tendency for dentoalveolar expansion.- Tendency for dentoalveolar expansion. - Expensive.- Expensive. www.indiandentalacademy.comwww.indiandentalacademy.com
  57. 57. Conventional Nitinol is available asConventional Nitinol is available as -- Nitinol classicNitinol classic -- UnitekUnitek corporationcorporation.. -- TitanalTitanal -- Lancer pacificLancer pacific.. -- OrthonolOrthonol -- Rocky mountainRocky mountain orthodontics.orthodontics. www.indiandentalacademy.comwww.indiandentalacademy.com
  58. 58. PSEUDOELASTIC NITINOLPSEUDOELASTIC NITINOL:: In the late 1980s, new Nickel titanium wires withIn the late 1980s, new Nickel titanium wires with anan Active Austenitic grain structureActive Austenitic grain structure appeared.appeared. These wires exhibited the remarkable propertyThese wires exhibited the remarkable property of NiTi alloys – SUPERELASTICITY.of NiTi alloys – SUPERELASTICITY. SUPERELASTICITY:SUPERELASTICITY: Manifested by very largeManifested by very large reversible strains and a non elastic stress strainreversible strains and a non elastic stress strain or force deflection curve.or force deflection curve. www.indiandentalacademy.comwww.indiandentalacademy.com
  59. 59. This group is also referred to asThis group is also referred to as A-NiTiA-NiTi.. This group includes :This group includes : --            Chinese NiTi.Chinese NiTi. --            Japanese NiTi (Sentinol)Japanese NiTi (Sentinol) --            2727°°C superelasticC superelastic Cu-NiTiCu-NiTi.. In Austenitic active alloy both MartensiteIn Austenitic active alloy both Martensite and Austenitic phases play an importantand Austenitic phases play an important role during its mechanical deformationrole during its mechanical deformation www.indiandentalacademy.comwww.indiandentalacademy.com
  60. 60. MECHANISM OF SUPERELASTICITY:MECHANISM OF SUPERELASTICITY: Stress Induced Martensitic Transformation : (SIM)Stress Induced Martensitic Transformation : (SIM) Unique force deflection curve for A-NiTi occurs becauseUnique force deflection curve for A-NiTi occurs because of phase transition in grain structure from Austenite toof phase transition in grain structure from Austenite to Martensite, in response not to temperature change butMartensite, in response not to temperature change but applied force.applied force. This transformation is mechanical analogue of thermallyThis transformation is mechanical analogue of thermally induced shape memory effect. ,the Austenitic alloyinduced shape memory effect. ,the Austenitic alloy undergoes a transition in internal structure in response toundergoes a transition in internal structure in response to stress without requiring a significant temperaturestress without requiring a significant temperature change.change. www.indiandentalacademy.comwww.indiandentalacademy.com
  61. 61. It is possible for these materials as their TTR isIt is possible for these materials as their TTR is close to room temperature.close to room temperature. MMdd of A-NiTi group is above mouth temperatureof A-NiTi group is above mouth temperature allowing formation of SIM at oral temperature.allowing formation of SIM at oral temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  62. 62. AAff (Austenitic finish) of these alloys is below mouth(Austenitic finish) of these alloys is below mouth temperature.temperature.                                                                 ⇓⇓ ••           Formation ofFormation of SIMSIM is reversible when stress isis reversible when stress is reduced.reduced. ••           These alloys cannot be easily cooled downThese alloys cannot be easily cooled down below their Ms.below their Ms.                                                                 ⇓⇓ Do not display clinically useful shape memoryDo not display clinically useful shape memory www.indiandentalacademy.comwww.indiandentalacademy.com
  63. 63. To exploit superelasticity to its fullest potentialTo exploit superelasticity to its fullest potential the working temperature of orthodonticthe working temperature of orthodontic appliances should be greater than the Aappliances should be greater than the Aff temperature.temperature. ••        It is the differential between AIt is the differential between Aff temperature andtemperature and mouth temperature that determines the forcemouth temperature that determines the force generated by NiTi alloys.generated by NiTi alloys. AAff can be controlled over wide range by affectingcan be controlled over wide range by affecting composition, thermomechanical treatment andcomposition, thermomechanical treatment and manufacturing process of alloymanufacturing process of alloy www.indiandentalacademy.comwww.indiandentalacademy.com
  64. 64. A superelastic material will not be superelastic atA superelastic material will not be superelastic at all temperatures, but will exhibit goodall temperatures, but will exhibit good superelastic properties in a temperature windowsuperelastic properties in a temperature window extending from the Active Af temperature upto aextending from the Active Af temperature upto a temperature which is about 50temperature which is about 50°°C above activeC above active Af.Af. A material with an Active Af of about 15A material with an Active Af of about 15°°C willC will exhibit good superelasticity upto about 65exhibit good superelasticity upto about 65°°CC which means that the material will exhibit goodwhich means that the material will exhibit good superelasticity at both room temperature andsuperelasticity at both room temperature and body temperaturebody temperature www.indiandentalacademy.comwww.indiandentalacademy.com
  65. 65. CHINESE NI TICHINESE NI TI Developed byDeveloped by Dr. Tien Hua ChengDr. Tien Hua Cheng and associatesand associates for orthodontic applications at the Generalfor orthodontic applications at the General Research Institute for Non ferrous metals inResearch Institute for Non ferrous metals in Beijing, China. Reported byBeijing, China. Reported by BurstoneBurstone in 1985in 1985.. Spring Back :Spring Back : At 80At 80°° of activation.of activation. Chinese NiTi wire has :Chinese NiTi wire has : --            1.4 times the springback of Nitinol wire.1.4 times the springback of Nitinol wire. --            4.6 times the springback of SS wire.4.6 times the springback of SS wire. www.indiandentalacademy.comwww.indiandentalacademy.com
  66. 66. Stiffness of Chinese NiTi is 36% that of NitinolStiffness of Chinese NiTi is 36% that of Nitinol wire.wire.    TTemperature dependent effects are clinicallyemperature dependent effects are clinically insignificant.insignificant. Chinese  NiTi  deformation  is  not  particularly  time Chinese  NiTi  deformation  is  not  particularly  time  dependent  unlike  nitinol  wire,  will  not  continue  to dependent  unlike  nitinol  wire,  will  not  continue  to  deform  a  significant  amount  in  mouth  between deform  a  significant  amount  in  mouth  between  adjustments.adjustments. The initial activation force required for austeniticThe initial activation force required for austenitic NiTi can be 3 times greater than the forceNiTi can be 3 times greater than the force required to deflect a classic work hardenedrequired to deflect a classic work hardened martensitic wire (Nitinol).martensitic wire (Nitinol). www.indiandentalacademy.comwww.indiandentalacademy.com
  67. 67. JAPANESE NITIJAPANESE NITI In 1978In 1978 : Furukawa Electric Co. Ltd. of Japan: Furukawa Electric Co. Ltd. of Japan produced a new type of Japanese NiTi alloy.produced a new type of Japanese NiTi alloy. In 1986In 1986 :: Miura et alMiura et al reported on Japanese NiTireported on Japanese NiTi Superelasticity is produced by stress, not bySuperelasticity is produced by stress, not by temperature change and is calledtemperature change and is called stress inducedstress induced Martensitic transformation (SIM)Martensitic transformation (SIM).. Provides light continuous force for physiologicProvides light continuous force for physiologic tooth movementtooth movement www.indiandentalacademy.comwww.indiandentalacademy.com
  68. 68. Japanese NiTi is marketed as Sentalloy. The relationship between the temperature andThe relationship between the temperature and time of the heat treatment of the Japanese NiTitime of the heat treatment of the Japanese NiTi alloy wire was studied to optimize the super-alloy wire was studied to optimize the super- elastic properties of the alloy.elastic properties of the alloy. When the heat application was raised to 500° C,When the heat application was raised to 500° C, the force level indicating the super-elasticthe force level indicating the super-elastic property could be reduced.property could be reduced. www.indiandentalacademy.comwww.indiandentalacademy.com
  69. 69. Other Super Elastic NiTi wiresOther Super Elastic NiTi wires 3M Unitek: Nitinol Super Elastic3M Unitek: Nitinol Super Elastic American Orthodontics: TitaniumAmerican Orthodontics: Titanium Memory Wire:Memory Wire: Available in two forceAvailable in two force levels :levels : Force IForce I – low force,– low force,Force IIForce II – high– high force.force. Ortho Organizers: NitaniumOrtho Organizers: Nitanium Masel Orthodontics: ElastinolMasel Orthodontics: Elastinol www.indiandentalacademy.comwww.indiandentalacademy.com
  70. 70. ADVANTAGES:ADVANTAGES:   Constant force over wide range of deflection.Constant force over wide range of deflection. Low stiffness.Low stiffness. High springback.High springback. More effective in initial tooth alignment.More effective in initial tooth alignment. Less patient discomfort.Less patient discomfort. www.indiandentalacademy.comwww.indiandentalacademy.com
  71. 71. LIMITATIONS OF SUPERELASTIC NiTi:LIMITATIONS OF SUPERELASTIC NiTi:     Cannot be soldered or welded.Cannot be soldered or welded. Poor formability.Poor formability. Tendency for dentoalveolar expansion.Tendency for dentoalveolar expansion. ““Travels” around the arch.Travels” around the arch. Expensive.Expensive. www.indiandentalacademy.comwww.indiandentalacademy.com
  72. 72. Thermoelastic nitinolThermoelastic nitinol Thermal analog of pseudoelasticity in whichThermal analog of pseudoelasticity in which martensitic phase transformation occursmartensitic phase transformation occurs from Austenite as temperature isfrom Austenite as temperature is decreased.decreased. This phase transformation can beThis phase transformation can be reversed by increasing the temperature toreversed by increasing the temperature to its original value.its original value. www.indiandentalacademy.comwww.indiandentalacademy.com
  73. 73. CHARACTERISTICS OF AN IDEALCHARACTERISTICS OF AN IDEAL THERMODYNAMIC NITINOL WIRE:THERMODYNAMIC NITINOL WIRE: 1. Dead soft at room temperature so that it can1. Dead soft at room temperature so that it can be tied easily.be tied easily. 2. Instantaneously activated by heat of mouth.2. Instantaneously activated by heat of mouth. 3. Able to apply clinically acceptable orthodontic3. Able to apply clinically acceptable orthodontic forces.forces.      www.indiandentalacademy.comwww.indiandentalacademy.com
  74. 74. 4.4.     Once fully activated would not be affectedOnce fully activated would not be affected further by increased heat in the mouth.further by increased heat in the mouth. 5.5.         A fairly narrow TTR i.e., it should beA fairly narrow TTR i.e., it should be completely active at mouth temperature yetcompletely active at mouth temperature yet completely passive at lower temperature.completely passive at lower temperature. This property would allow the clinician sufficientThis property would allow the clinician sufficient time to tie archwire into the bracket slots beforetime to tie archwire into the bracket slots before heat of mouth activates the wire.heat of mouth activates the wire. www.indiandentalacademy.comwww.indiandentalacademy.com
  75. 75. Thermoelastic NitinolThermoelastic Nitinol – formable at ice water temperatures.– formable at ice water temperatures. ⇓⇓ Ice water is belowIce water is below MsMs of thermoelastic wiresof thermoelastic wires ⇓⇓ Martensite while engagingMartensite while engaging When warmed aboveWhen warmed above AAff by mouth temp.by mouth temp. ⇓⇓ Transformation is reversed to from AusteniteTransformation is reversed to from Austenite ⇓⇓ Wire returns to its original shape thus displaying shapeWire returns to its original shape thus displaying shape memory.memory. www.indiandentalacademy.comwww.indiandentalacademy.com
  76. 76. COPPER NiTiCOPPER NiTi Invented byInvented by Dr. Rohit Sachdeva & Suchio MiyazakiDr. Rohit Sachdeva & Suchio Miyazaki .. COMPOSITION :COMPOSITION : Quaternary alloy containing.Quaternary alloy containing. * Nickel* Nickel * Copper (5 – 6%)* Copper (5 – 6%) • TitaniumTitanium * Chromium (0.2 – 0.5%)* Chromium (0.2 – 0.5%) CopperCopper:: --            Increases strengthIncreases strength --            Reduces hysteresisReduces hysteresis --        these benefits occur at expense of increasing TTRthese benefits occur at expense of increasing TTR above that of oral cavity.above that of oral cavity. www.indiandentalacademy.comwww.indiandentalacademy.com
  77. 77. ChromiumChromium :: to compensate for the aboveto compensate for the above mentioned unwanted effect 0.5%mentioned unwanted effect 0.5% chromium is added to return TTR close tochromium is added to return TTR close to oral temperatureoral temperature www.indiandentalacademy.comwww.indiandentalacademy.com
  78. 78. TYPES OF CU-NITITYPES OF CU-NITI:: 1.1. Type IType I AfAf 1515°°C.C. 2.2. Type IIType II AfAf 2727°°CC 3.3. Type IIIType III AfAf 3535°°CC 4.4. Type IV AfType IV Af 4040°°CC www.indiandentalacademy.comwww.indiandentalacademy.com
  79. 79. www.indiandentalacademy.comwww.indiandentalacademy.com
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  82. 82. Chill SprayChill Spray Facilitates adjustments orFacilitates adjustments or fitting of Ni Ti orthodonticfitting of Ni Ti orthodontic archwires,archwires, springs,appliances, etc.springs,appliances, etc. Ideal for Niti MemoryIdeal for Niti Memory Expanders and RotatorsExpanders and Rotators such as the Tandemsuch as the Tandem Loop Arndt MemoryLoop Arndt Memory Expander and ArndtExpander and Arndt Memory Rotator.Memory Rotator. Chills to -620Chills to -620ºº F/-520F/-520 ººC.... puts Niti into its softC.... puts Niti into its soft martensitic statemartensitic state www.indiandentalacademy.comwww.indiandentalacademy.com
  83. 83. Active Martensite Thermodynamic WireActive Martensite Thermodynamic Wire:: Included in the active martensitic group are wiresIncluded in the active martensitic group are wires with an Af set at a temperature at or above 37with an Af set at a temperature at or above 37°°CC [CuNiTi 37[CuNiTi 37°°C and CuNiTi 40C and CuNiTi 40°°C], which is almostC], which is almost complete, transformed into martensite duringcomplete, transformed into martensite during clinical application.clinical application. Martensitic alloy has a greater working rangeMartensitic alloy has a greater working range than austenite, and it may therefore provethan austenite, and it may therefore prove advantageous during the process of alignmentadvantageous during the process of alignment and leveling.and leveling. www.indiandentalacademy.comwww.indiandentalacademy.com
  84. 84. The ability to vary transition temperatures inThe ability to vary transition temperatures in martensitic wires of identical dimensions, allowsmartensitic wires of identical dimensions, allows the clinician to apply appropriate levels ofthe clinician to apply appropriate levels of physiological force during alignment, whilstphysiological force during alignment, whilst maintaining archwire size.maintaining archwire size. This wire combines greater heat sensitivity, highThis wire combines greater heat sensitivity, high shape memory, and extremely low, constantshape memory, and extremely low, constant forces to provide a full-size wire that can beforces to provide a full-size wire that can be inserted early in treatmentinserted early in treatment www.indiandentalacademy.comwww.indiandentalacademy.com
  85. 85. ADVANTAGES OF Cu-NiTi OVER OTHER NiTiADVANTAGES OF Cu-NiTi OVER OTHER NiTi AlloysAlloys:: 1.1.        Cu – NiTi generates more constant force overCu – NiTi generates more constant force over long activation spans.long activation spans. 2. More resistant to permanent deformation.2. More resistant to permanent deformation. 3.3.    Exhibits better springback properties.Exhibits better springback properties. 4. Exhibits smaller drop in unloading forces4. Exhibits smaller drop in unloading forces (reduced hysteresis).(reduced hysteresis). Provides precise TTRs at 4 different levels –Provides precise TTRs at 4 different levels – Enables Clinician to select archwires on a caseEnables Clinician to select archwires on a case specificspecific www.indiandentalacademy.comwww.indiandentalacademy.com
  86. 86. Bioforce SentalloyBioforce Sentalloy –– A Graded Thermodynamic WireA Graded Thermodynamic Wire The heatThe heat treatment of selected sections of the archwire bytreatment of selected sections of the archwire by means of different electric current delivered bymeans of different electric current delivered by electric pliers modified the values of theelectric pliers modified the values of the deactivation forces by varying the amount ofdeactivation forces by varying the amount of austenite present in the alloy.austenite present in the alloy. After heating the anterior segment for 60After heating the anterior segment for 60 minutes, the linear plateau of the deactivationminutes, the linear plateau of the deactivation force dropped to 80 g in a 3-point bending test atforce dropped to 80 g in a 3-point bending test at room temperature.room temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  87. 87. Similar manufacturing procedures have beenSimilar manufacturing procedures have been perfected to produce wires such as Bioforceperfected to produce wires such as Bioforce Sentalloy (GAC) that are able to deliver selectiveSentalloy (GAC) that are able to deliver selective forces according to the needs of the individualforces according to the needs of the individual dental arch segmentsdental arch segments BioForce (GAC) offers 80 grams of force forBioForce (GAC) offers 80 grams of force for anteriors and up to 320 grams for molarsanteriors and up to 320 grams for molars www.indiandentalacademy.comwww.indiandentalacademy.com
  88. 88. NITROGEN COATED ARCHWIRES:NITROGEN COATED ARCHWIRES: Implanting Nitrogen on surface of NiTi alloys byImplanting Nitrogen on surface of NiTi alloys by Ion implantation process –Ion implantation process – NITRIDINGNITRIDING.. Advantages:Advantages: --        Make Titanium more esthetically pleasing givingMake Titanium more esthetically pleasing giving it gold like aspect.it gold like aspect. --            Hardens surface.Hardens surface. --            Reduces friction.Reduces friction. --            Reduces Nickel release into mouth.Reduces Nickel release into mouth. e.g :e.g : Bioforce IonguardBioforce Ionguard - 3- 3µµm Nitrogen coating.m Nitrogen coating. www.indiandentalacademy.comwww.indiandentalacademy.com
  89. 89. TheThe IONGUARDIONGUARD process actually alters the wire’sprocess actually alters the wire’s surface to provide a dramaticallysurface to provide a dramatically reducedreduced coefficient of friction for sliding mechanicscoefficient of friction for sliding mechanics thatthat are better than the same size stainless steel wireare better than the same size stainless steel wire and half the friction of competitive NiTi wire.and half the friction of competitive NiTi wire. It also seals the occlusal surface of the wire toIt also seals the occlusal surface of the wire to eliminate breakage and reduce nickel leaching.eliminate breakage and reduce nickel leaching. While the IONGUARD process alters the surfaceWhile the IONGUARD process alters the surface of the wire, none of the wire’s unique propertiesof the wire, none of the wire’s unique properties is changed.is changed. www.indiandentalacademy.comwww.indiandentalacademy.com
  90. 90. Nitinol Total Control .A newNitinol Total Control .A new Orthodontic alloy.Orthodontic alloy. TODD A. THAYER, KARL FOX,ERIC MEYER ( JCO1999) developed a new pseudo-superelastic nickel titanium,alloy, Nitinol Total Control, Accepts specific 1st-, 2nd-, and 3rd-order bends while maintaining its desirable superelastic properties. www.indiandentalacademy.comwww.indiandentalacademy.com
  91. 91. Combines the ability of superelastic nickel titanium to deliver light, continuous forces over a desired treatment range with the bend ability required to account for variations in tooth morphology, archform, and bracket prescriptions. Frictional and bending tests verify that the force levels produced by them are within accepted ranges for optimal tooth movement. Furthermore,wire properties are not temperaturedependent. www.indiandentalacademy.comwww.indiandentalacademy.com
  92. 92. Because of relatively low stiffness, it should not be used for space closure. It can avoid the need to change archwires, , int he following situations: Repositioning due to improper bracket placement • Repositioning brackets to maintain torque control • www.indiandentalacademy.comwww.indiandentalacademy.com
  93. 93. Placement of extrusion, intrusion, or utilityarches •Functional finishing with detailing bends thataddress variations in tooth morphology and interarch occlusal relationships • Filling the bracket slot with controlled, lightforce (torque without shearing the bracket) Reduces archwire inventory without compromising treatment mechanics. Lower forces are generally associated with less patient discomfort. In addition, by reducing the number of archwire changes required, allows the clinician to treat more patients effectively and efficiently. www.indiandentalacademy.comwww.indiandentalacademy.com
  94. 94. www.indiandentalacademy.comwww.indiandentalacademy.com
  95. 95. NiTi wire bending pliers.NiTi wire bending pliers. In 1988, Miura, Mogi, and Ohura demonstrated the use of electrical-resistance heat treatment to introduce permanent bends in their nickel titanium wires. The technique requires special pliers attached to an electric power supply. Although the authors claimed that the superelastic force of the wire was not affected by the treatment, heating the wire does alter the crystalline structure of the nickel titanium lattice. www.indiandentalacademy.comwww.indiandentalacademy.com
  96. 96. MaselMasel offers two “V”offers two “V” Notch Stop pliers thatNotch Stop pliers that place precise “V” bendsplace precise “V” bends in NiTi wire.in NiTi wire. The newly designedThe newly designed Extraoral “V” Notch StopExtraoral “V” Notch Stop Plier #649 forms aPlier #649 forms a precise 1-mm “V” stopprecise 1-mm “V” stop that prevents wire fromthat prevents wire from disengaging from thedisengaging from the buccal tube. Bends roundbuccal tube. Bends round wire from 0.012 to 0.020wire from 0.012 to 0.020 inches, and rectangularinches, and rectangular wire up to 0.017 x 0.022wire up to 0.017 x 0.022 inches.inches. www.indiandentalacademy.comwww.indiandentalacademy.com
  97. 97. The Intraoral “V” Notch Stop Plier makesThe Intraoral “V” Notch Stop Plier makes “V” stops right in the mouth with one“V” stops right in the mouth with one squeeze. It bends round wire up to 0.016squeeze. It bends round wire up to 0.016 inches and rectangular wire up to 0.016 xinches and rectangular wire up to 0.016 x 0.022 inches.0.022 inches. www.indiandentalacademy.comwww.indiandentalacademy.com
  98. 98. HU-FRIEDY’S Hammerhead NiTi Tie BackHU-FRIEDY’S Hammerhead NiTi Tie Back PlierPlier Reduce a multi-stepReduce a multi-step process down to one,process down to one, simple squeeze —simple squeeze — nono heat requiredheat required Bends NiTi wireBends NiTi wire intraorally with no heatintraorally with no heat treatingtreating Designed to tie back NiTiDesigned to tie back NiTi distal to the buccal tube,distal to the buccal tube, gabel bends, omegagabel bends, omega loopsloops www.indiandentalacademy.comwww.indiandentalacademy.com
  99. 99. Bendistal PliersBendistal Pliers Allow orthodontists to NiTi wires intraorally usingAllow orthodontists to NiTi wires intraorally using a V-bend technique that corrects manya V-bend technique that corrects many challenging orthodontic problems with single-challenging orthodontic problems with single- squeeze adjustments.squeeze adjustments. The pliers’ tiny tips fit between brackets to allowThe pliers’ tiny tips fit between brackets to allow placement of intraoral activating bends on tiedplacement of intraoral activating bends on tied archwires without breaking the wire or thearchwires without breaking the wire or the brackets.brackets. www.indiandentalacademy.comwww.indiandentalacademy.com
  100. 100. The pliers areThe pliers are available in a set ofavailable in a set of two, featuring a longtwo, featuring a long and thin design toand thin design to reach behind thereach behind the molar tube for easiermolar tube for easier cinch-back purposescinch-back purposes and wire activations inand wire activations in the four mouththe four mouth quadrants.quadrants. www.indiandentalacademy.comwww.indiandentalacademy.com
  101. 101. www.indiandentalacademy.comwww.indiandentalacademy.com
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  104. 104. Recycling & Sterilization of Nickel TitaniumRecycling & Sterilization of Nickel Titanium ArchwiresArchwires Recycling of nitinol wires is often practicedRecycling of nitinol wires is often practiced because of their favorable physicalbecause of their favorable physical properties and the high cost of the wire.properties and the high cost of the wire. The ability to recycle these archwire reliesThe ability to recycle these archwire relies on effective sterilization of the wire prior toon effective sterilization of the wire prior to re-use without resulting in deterioration ofre-use without resulting in deterioration of clinical properties.clinical properties. www.indiandentalacademy.comwww.indiandentalacademy.com
  105. 105. For effective sterilization, steam autoclavingFor effective sterilization, steam autoclaving (ideally at(ideally at 134ºC, 32 psi for 3 minutes134ºC, 32 psi for 3 minutes) is) is the method recommended.the method recommended. For instruments unable to withstandFor instruments unable to withstand autoclaving, an effective cold disinfectionautoclaving, an effective cold disinfection solution such as 2% glutaraldehyde is ansolution such as 2% glutaraldehyde is an alternative.alternative. www.indiandentalacademy.comwww.indiandentalacademy.com
  106. 106. Mayhew and Kusy (1988)Mayhew and Kusy (1988) andand Buckthal andBuckthal and Kusy(1986)Kusy(1986) have demonstrated no appreciablehave demonstrated no appreciable loss in properties of nitinol wires after as manyloss in properties of nitinol wires after as many as three cycles of various forms of heatas three cycles of various forms of heat sterilization or chemical disinfection .sterilization or chemical disinfection . In a recent in vitro investigation on the effects ofIn a recent in vitro investigation on the effects of a simulated oral environment on 0.016” nickela simulated oral environment on 0.016” nickel titanium wires,titanium wires, Harris et al(1988)Harris et al(1988) noted anoted a significant decrease in yield strength of thesesignificant decrease in yield strength of these wires over a period of four months.wires over a period of four months. www.indiandentalacademy.comwww.indiandentalacademy.com
  107. 107. The testing procedure involved a staticThe testing procedure involved a static environment in which thermal changesenvironment in which thermal changes were not taken into account and in whichwere not taken into account and in which the dynamic changes in forces, such asthe dynamic changes in forces, such as those of mastication and occlusion, werethose of mastication and occlusion, were nonexistent.nonexistent. www.indiandentalacademy.comwww.indiandentalacademy.com
  108. 108. Burstone et al (1985)Burstone et al (1985) andand Miura et alMiura et al (1986)(1986) noted that temperatures greaternoted that temperatures greater than 60ºC increased the susceptibility ofthan 60ºC increased the susceptibility of these austenitic nickel titanium wires tothese austenitic nickel titanium wires to plastic deformation and decreased theirplastic deformation and decreased their springback.springback. www.indiandentalacademy.comwww.indiandentalacademy.com
  109. 109. Corrosion SusceptibilityCorrosion Susceptibility Corrosion in wire alloys becomes a factorCorrosion in wire alloys becomes a factor in the quality of the wire performance inin the quality of the wire performance in Orthodontics.Orthodontics. Corrosion phenomena are increased byCorrosion phenomena are increased by internal stresses in the metal appliances,internal stresses in the metal appliances, by the inhomogeneous structure of theby the inhomogeneous structure of the alloy, and by different metals coming intoalloy, and by different metals coming into contact.contact. www.indiandentalacademy.comwww.indiandentalacademy.com
  110. 110. When the in vivo and in vitro corrosionWhen the in vivo and in vitro corrosion behaviour of stainless steel, Elgiloy, nitinolbehaviour of stainless steel, Elgiloy, nitinol and TMA wires were compared,and TMA wires were compared, It was found that the stainless steel,It was found that the stainless steel, Elgiloy and TMA exhibited no appreciableElgiloy and TMA exhibited no appreciable corrosion damage, but the pitting due tocorrosion damage, but the pitting due to corrosion was observed on the surface ofcorrosion was observed on the surface of nitinol.(nitinol.( Clinard , JDR 1981Clinard , JDR 1981)) www.indiandentalacademy.comwww.indiandentalacademy.com
  111. 111. A study byA study by Kim and Johnson(1999)Kim and Johnson(1999) determined ifdetermined if there is a significant difference in the corrosivethere is a significant difference in the corrosive potential of stainless steel, nickel titanium,potential of stainless steel, nickel titanium, nitride-coated nickel titanium, epoxy-coatednitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium orthodontic wires.nickel titanium, and titanium orthodontic wires. SEM photographs revealed that some nickelSEM photographs revealed that some nickel titanium and stainless steel wires weretitanium and stainless steel wires were susceptible to pitting and localized corrosion.susceptible to pitting and localized corrosion. The nitrides coating did not affect the corrosionThe nitrides coating did not affect the corrosion of the alloy, but epoxy coating decreasedof the alloy, but epoxy coating decreased corrosion. Titanium wires and epoxy-coatedcorrosion. Titanium wires and epoxy-coated nickel titanium wires exhibited the least corrosivenickel titanium wires exhibited the least corrosive potential.potential. www.indiandentalacademy.comwww.indiandentalacademy.com
  112. 112. Study byStudy by Eliades et al (2000)Eliades et al (2000) evaluating theevaluating the structure and morphological condition ofstructure and morphological condition of retrieved NiTi orthodontic arch wires reportedretrieved NiTi orthodontic arch wires reported that intra-oral exposure of NiTi wires alters thethat intra-oral exposure of NiTi wires alters the topography and structure of the alloy surfacetopography and structure of the alloy surface through surface attack in the form of pitting orthrough surface attack in the form of pitting or crevice corrosion or formation of integuments.crevice corrosion or formation of integuments. NiTi wires were coated by intra-orally formedNiTi wires were coated by intra-orally formed proteinaceous integuments that masked theproteinaceous integuments that masked the alloy surface topography to an extent dependentalloy surface topography to an extent dependent on the individual patient’s oral environmentalon the individual patient’s oral environmental conditions and the intra-oral exposure period.conditions and the intra-oral exposure period. www.indiandentalacademy.comwww.indiandentalacademy.com
  113. 113. Clinical PerformanceClinical Performance Evans et al (1998)Evans et al (1998) clinically evaluated threeclinically evaluated three commonly used orthodontic tooth aligning archcommonly used orthodontic tooth aligning arch wires:wires: 0.016 x 0.022 inch active martensitic0.016 x 0.022 inch active martensitic medium force nickel titanium,medium force nickel titanium, 0.016 x 0.022 inch0.016 x 0.022 inch graded force active martensitic nickel titaniumgraded force active martensitic nickel titanium,, andand 0.015 inch multistrand stainless steel0.015 inch multistrand stainless steel. It was. It was a prospective randomized clinical triala prospective randomized clinical trial Heat activated nickel titanium arch wires failed toHeat activated nickel titanium arch wires failed to demonstrate a better performance than thedemonstrate a better performance than the cheaper multistrand stainless steel wires in thischeaper multistrand stainless steel wires in this randomized clinical trial.randomized clinical trial. www.indiandentalacademy.comwww.indiandentalacademy.com
  114. 114. The failure to demonstrate in vivo superiority atThe failure to demonstrate in vivo superiority at the clinical level may be due to the confoundingthe clinical level may be due to the confounding effects of large variations in individual metaboliceffects of large variations in individual metabolic response.response. Alternatively, it may be that in routine clinicalAlternatively, it may be that in routine clinical practice NiTi-type wires are not sufficientlypractice NiTi-type wires are not sufficiently deformed to allow their full superelasticdeformed to allow their full superelastic properties to come in to play during initialproperties to come in to play during initial alignment.alignment. www.indiandentalacademy.comwww.indiandentalacademy.com
  115. 115. According to data, under conditions of minimumAccording to data, under conditions of minimum crowding there is no special reason to use acrowding there is no special reason to use a superelastic alloy wire rather than an establishedsuperelastic alloy wire rather than an established multistranded stainless steel wire, because themultistranded stainless steel wire, because the range of force delivered by the multistrandedrange of force delivered by the multistranded stainless steel is considered acceptable.stainless steel is considered acceptable. Superelastic NiTi may represent the electiveSuperelastic NiTi may represent the elective choice when moderate crowding is present andchoice when moderate crowding is present and when arch form and torque control are requiredwhen arch form and torque control are required in the initial stages of treatment because anin the initial stages of treatment because an equivalent rectangular multistranded stainlessequivalent rectangular multistranded stainless steel wire presents rather higher stiffness and issteel wire presents rather higher stiffness and is subject to permanent deformationsubject to permanent deformation.. www.indiandentalacademy.comwww.indiandentalacademy.com
  116. 116. NiTi Coil SpringsNiTi Coil Springs Compression & tension springs made of Ni TiCompression & tension springs made of Ni Ti have been recommended-have been recommended- a) Minimum of permanent deformation.a) Minimum of permanent deformation. b) More constant force during unloading.b) More constant force during unloading. Closed coil springs – used for space closure.Closed coil springs – used for space closure. Open coil springs- Mainly for opening space toOpen coil springs- Mainly for opening space to unravel the teeth for distalization of molars.unravel the teeth for distalization of molars. www.indiandentalacademy.comwww.indiandentalacademy.com
  117. 117. The superelastic coil springs were designed andThe superelastic coil springs were designed and manufactured to produce a specific forcemanufactured to produce a specific force throughout the working range of the spring.throughout the working range of the spring. Like the adjustable force springs, ourLike the adjustable force springs, our superelastic coil springs will not take asuperelastic coil springs will not take a permanent set. They return to their originalpermanent set. They return to their original length after normal deflection.length after normal deflection. www.indiandentalacademy.comwww.indiandentalacademy.com
  118. 118. Coil Springs With EyeletsCoil Springs With Eyelets Adjustable force andAdjustable force and superelastic closedsuperelastic closed coil springs arecoil springs are available with eyelets.available with eyelets. These stainless steelThese stainless steel eyelets attach to eacheyelets attach to each end of adjustableend of adjustable force or superelasticforce or superelastic closing (closed coil)closing (closed coil) springs.springs. This allows to easilyThis allows to easily engage a bracket hook,engage a bracket hook, sliding hook, buccalsliding hook, buccal tube hook and/or postedtube hook and/or posted arch wire hooksarch wire hooks www.indiandentalacademy.comwww.indiandentalacademy.com
  119. 119. Place one eyelet overPlace one eyelet over the distal hook andthe distal hook and gripping the leadinggripping the leading edge of the frontedge of the front eyelet with pliers, pulleyelet with pliers, pull gently forward togently forward to engage your anteriorengage your anterior hook.hook. www.indiandentalacademy.comwww.indiandentalacademy.com
  120. 120. A study was designed byA study was designed by Heinz et al ( AJO 1999)Heinz et al ( AJO 1999) to determine whether relatively constant forcesto determine whether relatively constant forces can be delivered and whether the forcecan be delivered and whether the force magnitudes approach the manufacturer’smagnitudes approach the manufacturer’s targeted force values.targeted force values. Heavy, medium, and light springs were activatedHeavy, medium, and light springs were activated 15 mm at temperatures that ranged from 15°C to15 mm at temperatures that ranged from 15°C to 60°C. The forces were measured during60°C. The forces were measured during deactivation with a specially constructed forcedeactivation with a specially constructed force transducer temperature chamber.transducer temperature chamber. www.indiandentalacademy.comwww.indiandentalacademy.com
  121. 121. Relatively constant forces can be achieved with anRelatively constant forces can be achieved with an over-activation procedure that allows relaxationover-activation procedure that allows relaxation to the desired activation.to the desired activation. The light springs delivered forces that were nearThe light springs delivered forces that were near the targeted force; no difference was foundthe targeted force; no difference was found between the heavy and medium springs in thebetween the heavy and medium springs in the constant force range.constant force range. The force magnitudes varied markedly dependingThe force magnitudes varied markedly depending on mouth temperature.on mouth temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  122. 122. Angolkar, RS Nanda (AJO1992)Angolkar, RS Nanda (AJO1992) designed a indesigned a in vitro study to determine the force degradation ofvitro study to determine the force degradation of closed coil springs made of stainless steel (SS),closed coil springs made of stainless steel (SS), cobalt-chromium-nickel (Co-Cr-Ni) and nickel-cobalt-chromium-nickel (Co-Cr-Ni) and nickel- titanium (Niti) alloys, when they were extendedtitanium (Niti) alloys, when they were extended to generate an initial force value in the range ofto generate an initial force value in the range of 150 to 160 gm.150 to 160 gm. The specimens were divided into two groups.The specimens were divided into two groups. Group IGroup I included SS, Co-Cr-Ni, and two nickel-included SS, Co-Cr-Ni, and two nickel- titanium spring types (Niti 1 and Niti 2), 0.010 ´titanium spring types (Niti 1 and Niti 2), 0.010 ´ 0.030 inch with an initial length of 12 mm.0.030 inch with an initial length of 12 mm. www.indiandentalacademy.comwww.indiandentalacademy.com
  123. 123. Group llGroup ll was comprised of SS, Co-Cr-Ni, and Ni Ti 3was comprised of SS, Co-Cr-Ni, and Ni Ti 3 0.010 ´ 0.036-inch springs, with an initial length of 6 mm.0.010 ´ 0.036-inch springs, with an initial length of 6 mm. A universal testing machine was used to measure force.A universal testing machine was used to measure force. Initial force was recorded, and then the springs wereInitial force was recorded, and then the springs were extended to the respective distances at 4 hours, 24extended to the respective distances at 4 hours, 24 hours, 3 days, 7 days, 14 days, 21 days, and 28 dayshours, 3 days, 7 days, 14 days, 21 days, and 28 days resulting in a total of eight time periods.resulting in a total of eight time periods. Between the time intervals, all springs were extended toBetween the time intervals, all springs were extended to the same initial extension on specially designed racksthe same initial extension on specially designed racks and stored in a salivary substitute at 37° C.and stored in a salivary substitute at 37° C. www.indiandentalacademy.comwww.indiandentalacademy.com
  124. 124. All springs showed a force loss over time. Of theAll springs showed a force loss over time. Of the total, the major force loss for most springs wastotal, the major force loss for most springs was found to occur in the first 24 hours.found to occur in the first 24 hours. The SS and Co-Cr-Ni springs showed relativelyThe SS and Co-Cr-Ni springs showed relatively higher force decay in group I (0.010 ´ 0.030higher force decay in group I (0.010 ´ 0.030 inch) compared with Niti 1 and Niti 2.inch) compared with Niti 1 and Niti 2. The Niti 3 springs of group II (0.010 ´ 0.036 inch)The Niti 3 springs of group II (0.010 ´ 0.036 inch) showed higher force degradation than the SSshowed higher force degradation than the SS and Co-Cr-Ni springs of this group.and Co-Cr-Ni springs of this group. www.indiandentalacademy.comwww.indiandentalacademy.com
  125. 125. The least force decay was found in the NitiThe least force decay was found in the Niti 1 springs. In general, the total force loss1 springs. In general, the total force loss after 28 days was in the range of 8% toafter 28 days was in the range of 8% to 20% for all springs tested.20% for all springs tested. This was considered to be relatively lessThis was considered to be relatively less compared with force loss shown by latexcompared with force loss shown by latex elastics and synthetic elastic modules aselastics and synthetic elastic modules as reported in the literature.reported in the literature. www.indiandentalacademy.comwww.indiandentalacademy.com
  126. 126. Jebby Jacob, K.Sadashiva Shetty (JIOS 2002)Jebby Jacob, K.Sadashiva Shetty (JIOS 2002) conducted a study to evaluate the force characteristics ofconducted a study to evaluate the force characteristics of NiTi open & closed coil springs of different length,NiTi open & closed coil springs of different length, diameter, lumen size to determine the effect of staticdiameter, lumen size to determine the effect of static simulated oral environment on spring properties .simulated oral environment on spring properties . Results showed-Results showed- Increase in size of lumenIncrease in size of lumen : decreased force.: decreased force. Increasing wire diameterIncreasing wire diameter : increases force.: increases force. Increasing open coil spring lengthIncreasing open coil spring length : range of: range of superelaticity increased significantly.superelaticity increased significantly. www.indiandentalacademy.comwww.indiandentalacademy.com
  127. 127. Closed coil springs with shorter length &Closed coil springs with shorter length & smaller diameter showed good supersmaller diameter showed good super elastic range.elastic range. Spring properties showed very minorSpring properties showed very minor changes over a period of 4 weeks in staticchanges over a period of 4 weeks in static stimulated oral enviornment.stimulated oral enviornment. www.indiandentalacademy.comwww.indiandentalacademy.com
  128. 128. Nattrass (EJO1998)Nattrass (EJO1998) conducted a study on 9mmconducted a study on 9mm closed coil spring & found that increase inclosed coil spring & found that increase in temprature increased the force level.temprature increased the force level. In same study elastomeric chains were alsoIn same study elastomeric chains were also tested & it was found that they were effectedtested & it was found that they were effected both by temprature & oral environment.both by temprature & oral environment. Increase in temprature & exposure to soft drinkIncrease in temprature & exposure to soft drink & turmeric solution lead to a more force loss in& turmeric solution lead to a more force loss in elastomeric chains.elastomeric chains. www.indiandentalacademy.comwww.indiandentalacademy.com
  129. 129. Han et al (Angle 1993)Han et al (Angle 1993) conducted a studyconducted a study of Ni Ti closed coil springs, Stainless steelof Ni Ti closed coil springs, Stainless steel springs,& polyurethane elastics in asprings,& polyurethane elastics in a simulated oral environment for 4 weeks.simulated oral environment for 4 weeks. Results showed degradation of physicalResults showed degradation of physical properties of stainless steel springs &properties of stainless steel springs & elastics, but Ni Ti remained relativelyelastics, but Ni Ti remained relatively stable.stable. www.indiandentalacademy.comwww.indiandentalacademy.com
  130. 130. In a in vivo study byIn a in vivo study by Sonis AL ( JCO 1994)Sonis AL ( JCO 1994) Ni Ti closed coil springs produced nearlyNi Ti closed coil springs produced nearly twice as rapid a rate of tooth movement astwice as rapid a rate of tooth movement as conventional elastic at same force level.conventional elastic at same force level. Miura et al ( 1988)Miura et al ( 1988) compared mechanicalcompared mechanical properties of Japanese Ni Ti & stainlessproperties of Japanese Ni Ti & stainless steel coil springs in both closed & opensteel coil springs in both closed & open types.types. www.indiandentalacademy.comwww.indiandentalacademy.com
  131. 131. Japanese Ni Ti coil springs exhibitedJapanese Ni Ti coil springs exhibited superior spring back, super elasticsuperior spring back, super elastic properties.properties. Most important characteristic of Ni Ti coilMost important characteristic of Ni Ti coil spring was the ability to exert a very longspring was the ability to exert a very long range of constant ,light & continuousrange of constant ,light & continuous force.force. www.indiandentalacademy.comwww.indiandentalacademy.com
  132. 132. Ni Ti Palatal expanderNi Ti Palatal expander Conventional rapid palatal expanders are uncomfortable,Conventional rapid palatal expanders are uncomfortable, require patient cooperation, and rely on labor-intensiverequire patient cooperation, and rely on labor-intensive laboratory production.laboratory production. They are inefficient because of the intermittent nature ofThey are inefficient because of the intermittent nature of their force application. Also, they are often soldered totheir force application. Also, they are often soldered to maxillary first molars with pre-existing mesiolingualmaxillary first molars with pre-existing mesiolingual rotations that the devices are unable to correct.rotations that the devices are unable to correct. These rotations can distort the appliances into ineffectiveThese rotations can distort the appliances into ineffective shapes, and until the rotations are corrected, much ofshapes, and until the rotations are corrected, much of the potential expansion time can be wasted.the potential expansion time can be wasted. www.indiandentalacademy.comwww.indiandentalacademy.com
  133. 133. To overcome the limitations of conventionalTo overcome the limitations of conventional expansion appliances,expansion appliances, William Arndt ( JCOWilliam Arndt ( JCO 1993)1993) developed a tandem-loop, nickel titanium,developed a tandem-loop, nickel titanium, temperature-activated palatal expander with thetemperature-activated palatal expander with the ability to produce light, continuous pressure onability to produce light, continuous pressure on the midpalatal suture while simultaneouslythe midpalatal suture while simultaneously uprighting, rotating, and distalizing the maxillaryuprighting, rotating, and distalizing the maxillary first molars.first molars. The action of the appliance is a consequence ofThe action of the appliance is a consequence of nickel titanium's shape memory and transitionnickel titanium's shape memory and transition temperature effects. Nickel titanium can betemperature effects. Nickel titanium can be processed into a set shape to which it constantlyprocessed into a set shape to which it constantly tends to return after deformationtends to return after deformation www.indiandentalacademy.comwww.indiandentalacademy.com
  134. 134. www.indiandentalacademy.comwww.indiandentalacademy.com
  135. 135. In addition, it can be alloyed to produce a metalIn addition, it can be alloyed to produce a metal with a specific transition temperature.with a specific transition temperature. At temperatures below the transitionAt temperatures below the transition temperature, the interatomic forces weaken,temperature, the interatomic forces weaken, making the metal much more flexible.making the metal much more flexible. Above the transition temperature, theAbove the transition temperature, the interatomic forces bind the atoms tighter and theinteratomic forces bind the atoms tighter and the metal stiffens.metal stiffens. www.indiandentalacademy.comwww.indiandentalacademy.com
  136. 136. The nickel titanium expander has aThe nickel titanium expander has a transitiontransition temperature of 94°Ftemperature of 94°F. When it is chilled before. When it is chilled before insertion, it becomes flexible and can easily beinsertion, it becomes flexible and can easily be bent to facilitate placement .bent to facilitate placement . As the mouth begins to warm the appliance, theAs the mouth begins to warm the appliance, the metal stiffens, the shape memory is restored,metal stiffens, the shape memory is restored, and the expander begins to exert a light,and the expander begins to exert a light, continuous force on the teeth and the midpalatalcontinuous force on the teeth and the midpalatal suture .suture . www.indiandentalacademy.comwww.indiandentalacademy.com
  137. 137. Nickel titanium expanders come in eight differentNickel titanium expanders come in eight different intermolar widths, ranging fromintermolar widths, ranging from 26mm to 47mm26mm to 47mm,, that generate forces ofthat generate forces of 180-300g180-300g.. The 26-32mm sizes have softer wires thatThe 26-32mm sizes have softer wires that produce lower force levels for younger patients.produce lower force levels for younger patients. The clinician determines the appropriate size byThe clinician determines the appropriate size by measuring the amount of expansion needed,measuring the amount of expansion needed, then adding 3mm for overcorrection.then adding 3mm for overcorrection. www.indiandentalacademy.comwww.indiandentalacademy.com
  138. 138. Freeze-gel packs, provided in the expander kits,Freeze-gel packs, provided in the expander kits, can be placed around the expander assemblycan be placed around the expander assembly while the band cement is being prepared. Thiswhile the band cement is being prepared. This will cool the appliance enough to allow easywill cool the appliance enough to allow easy insertion into the lingual sheaths.insertion into the lingual sheaths. The expander should be handled by the molarThe expander should be handled by the molar attachments during placement to avoid warmingattachments during placement to avoid warming the nickel titanium.the nickel titanium. www.indiandentalacademy.comwww.indiandentalacademy.com
  139. 139. When the appliance begins to stiffen in theWhen the appliance begins to stiffen in the mouth, it may cause some discomfort at first.mouth, it may cause some discomfort at first. The patient can alleviate this by sipping a coldThe patient can alleviate this by sipping a cold liquid, which will temporarily make the nickelliquid, which will temporarily make the nickel titanium slightly more flexible. Many of mytitanium slightly more flexible. Many of my patients have delighted in showing this effect topatients have delighted in showing this effect to their friends.their friends. www.indiandentalacademy.comwww.indiandentalacademy.com
  140. 140. Maurice Corbett (JCO 1997) Described a modification called the Nickel palatal expander 2, that delivers a uniform, slow continuous force for maxillary expansion, molar distalization and rotation. Puneet Batra,Ritu Duggal, Hari Prakash (JIOS 2003): studied the efficacy of nitinol expander in cleft and non cleft patients and they concluded that it would be effective in both type of patients requiring transverse expansion of the maxilla. www.indiandentalacademy.comwww.indiandentalacademy.com
  141. 141. Donohue V, Marshman, WinchesterL EJO 2004 compared maxillary expansion using either a quadhelix appliance or a nickel titanium expander in 28 patients. There was no significant difference in the efficacy or rate of expansion between the two appliances. The quad helix however appeared to exert a more controlled rate of expansion. www.indiandentalacademy.comwww.indiandentalacademy.com
  142. 142. Molar distalizationMolar distalization Superelastic NiTi wire:Superelastic NiTi wire: Locatelli et alLocatelli et al ((19921992) used a 100) used a 100 gm NeoSentalloy wire (superelastic Nickel-titanium wire)gm NeoSentalloy wire (superelastic Nickel-titanium wire) with shape memory for molar distalization .with shape memory for molar distalization . Crimp stops just distal to first premolar bracket areCrimp stops just distal to first premolar bracket are placed 5 – 7 mm distal to anterior opening of molar tubeplaced 5 – 7 mm distal to anterior opening of molar tube and hooks between lateral incisors and canines.and hooks between lateral incisors and canines. Excess wire is deflected gingivally into buccal fold. AsExcess wire is deflected gingivally into buccal fold. As wire returns to original shape, it exerts 100 gm distalwire returns to original shape, it exerts 100 gm distal force against molars.force against molars. www.indiandentalacademy.comwww.indiandentalacademy.com
  143. 143. www.indiandentalacademy.comwww.indiandentalacademy.com
  144. 144. Super elastic nickel titanium wires haveSuper elastic nickel titanium wires have been found as effective as other means inbeen found as effective as other means in producing distal movement of theproducing distal movement of the maxillary first molars.maxillary first molars. When the distalization is carried out beforeWhen the distalization is carried out before the second molars have erupted, it canthe second molars have erupted, it can reliably produce 1-2mm of space.reliably produce 1-2mm of space. www.indiandentalacademy.comwww.indiandentalacademy.com
  145. 145. The concept of using coil springs for distalizationThe concept of using coil springs for distalization was introduced bywas introduced by Miura (1988)Miura (1988) who used 100who used 100 gms superelastic coils.gms superelastic coils. Gianelly ( AJO1991)Gianelly ( AJO1991) used Japanese NiTi coilused Japanese NiTi coil springs exerting 100 gms of force to movesprings exerting 100 gms of force to move maxillary molars distally.maxillary molars distally. www.indiandentalacademy.comwww.indiandentalacademy.com
  146. 146. Movement achieved is 1-1.5 mm perMovement achieved is 1-1.5 mm per month.month. NiTi molar distalizing springs are also aNiTi molar distalizing springs are also a part of appliances like Jones jig, Distal jetpart of appliances like Jones jig, Distal jet etc.etc. www.indiandentalacademy.comwww.indiandentalacademy.com
  147. 147. Erverdi et al ( BJO 1997)Erverdi et al ( BJO 1997) compared Ni Ticompared Ni Ti coil springs & repelling magnets as 2coil springs & repelling magnets as 2 methods of intra oral molar distalizers for amethods of intra oral molar distalizers for a period of 3 months.period of 3 months. Although upper molar distalization wasAlthough upper molar distalization was achieved with ease in both techniques, Niachieved with ease in both techniques, Ni Ti coil springs were found to be moreTi coil springs were found to be more effective in terms of movement achieved.effective in terms of movement achieved. www.indiandentalacademy.comwww.indiandentalacademy.com
  148. 148. Neet Separating SpringsNeet Separating Springs The Neet Separating Springs are manufacturedThe Neet Separating Springs are manufactured from Nickel Titanium. These innovativefrom Nickel Titanium. These innovative separators provide light continous forces that willseparators provide light continous forces that will separate stubborn molars while maintainingseparate stubborn molars while maintaining patient comfort.patient comfort. Inserting the separator into any contact is easyInserting the separator into any contact is easy and will provide generous space for banding.and will provide generous space for banding. The clinician no longer has to struggle trying toThe clinician no longer has to struggle trying to "saw" through the contact with an elastomeric"saw" through the contact with an elastomeric separator.separator. www.indiandentalacademy.comwww.indiandentalacademy.com
  149. 149. www.indiandentalacademy.comwww.indiandentalacademy.com
  150. 150. Nickel allergyNickel allergy Nickel is the most common metal to causeNickel is the most common metal to cause contact dermatitis in orthodontics.contact dermatitis in orthodontics. Nickel-titanium alloys may have nickel content inNickel-titanium alloys may have nickel content in excess of 50 per cent and can thus potentiallyexcess of 50 per cent and can thus potentially release enough nickel in the oral environment torelease enough nickel in the oral environment to elicit manifestations of an allergic reaction.elicit manifestations of an allergic reaction. Nickel elicits contact dermatitis, which is a TypeNickel elicits contact dermatitis, which is a Type IV delayed hypersensitivity immune response.IV delayed hypersensitivity immune response. www.indiandentalacademy.comwww.indiandentalacademy.com
  151. 151. It has been shown that the level of nickelIt has been shown that the level of nickel in saliva and serum increases significantlyin saliva and serum increases significantly after the insertion of fixed orthodonticafter the insertion of fixed orthodontic appliances.appliances. ( Agaoglu,2001).( Agaoglu,2001). It has been suggested that a thresholdIt has been suggested that a threshold concentration of approximately 30 ppm ofconcentration of approximately 30 ppm of nickel may be sufficient to elicit a cytotoxicnickel may be sufficient to elicit a cytotoxic response.response. (Bour ,1994).(Bour ,1994). www.indiandentalacademy.comwww.indiandentalacademy.com
  152. 152. Barrett et al ( AJO,1993)Barrett et al ( AJO,1993) reported that thereported that the release rate for nickel from stainless steelrelease rate for nickel from stainless steel or nickel titanium wires are notor nickel titanium wires are not significantly differentsignificantly different Possible risks associated with nickelPossible risks associated with nickel toxicity : Risk of nephrotoxicity,toxicity : Risk of nephrotoxicity, Carcinogenicity, risk of immune changesCarcinogenicity, risk of immune changes & alveolar bone loss.& alveolar bone loss. www.indiandentalacademy.comwww.indiandentalacademy.com
  153. 153. : Flexile nickel-titanium wires release increased: Flexile nickel-titanium wires release increased amounts of nickel and are thought to inductamounts of nickel and are thought to induct nickel sensitivity; there may be up to 20 per centnickel sensitivity; there may be up to 20 per cent conversion rate.conversion rate. (Jia ,1999)(Jia ,1999) These high nickelThese high nickel content wires should be avoided in nickelcontent wires should be avoided in nickel sensitive patients.sensitive patients. Alternatives include twistflex stainless steel,Alternatives include twistflex stainless steel, fibre-reinforced composite archwires. Wiresfibre-reinforced composite archwires. Wires such as TMA, pure titanium, and gold-platedsuch as TMA, pure titanium, and gold-plated wires may also be used without risk.wires may also be used without risk. www.indiandentalacademy.comwww.indiandentalacademy.com
  154. 154. Altered nickel-titanium archwires also existAltered nickel-titanium archwires also exist and include plastic/resin-coated nickel-and include plastic/resin-coated nickel- titanium archwires.titanium archwires. www.indiandentalacademy.comwww.indiandentalacademy.com
  155. 155. Ion-implanted nickel-titanium archwires haveIon-implanted nickel-titanium archwires have their surface bombarded with nitrogen ions,their surface bombarded with nitrogen ions, which forms an amorphous surface layer,which forms an amorphous surface layer, conferring corrosion resistance and displacingconferring corrosion resistance and displacing nickel atoms.nickel atoms. Manufacturers claim that these altered nickel-Manufacturers claim that these altered nickel- titanium archwires exhibit less corrosion thantitanium archwires exhibit less corrosion than stainless steel or non-coated nickel-titaniumstainless steel or non-coated nickel-titanium wires, which results in a reduction of the releasewires, which results in a reduction of the release of nickel and decrease the risk of an allergicof nickel and decrease the risk of an allergic response.response. www.indiandentalacademy.comwww.indiandentalacademy.com
  156. 156. Diagnosis of nickel allergyDiagnosis of nickel allergy It is important to make a correct diagnosis ofIt is important to make a correct diagnosis of nickel allergy, symptoms of which may occurnickel allergy, symptoms of which may occur either within or remote to the oral environment.either within or remote to the oral environment. The following patient history would suggest aThe following patient history would suggest a diagnosis of nickel allergy:diagnosis of nickel allergy: previous allergic response after wearing earringsprevious allergic response after wearing earrings or a metal watchstrap;or a metal watchstrap; www.indiandentalacademy.comwww.indiandentalacademy.com
  157. 157. appearance of allergy symptoms shortlyappearance of allergy symptoms shortly after the initial insertion of orthodonticafter the initial insertion of orthodontic components containing nickel;components containing nickel; confined extra-oral rash adjacent toconfined extra-oral rash adjacent to headgear studs.headgear studs. www.indiandentalacademy.comwww.indiandentalacademy.com
  158. 158. Intra oral agingIntra oral aging For brackets & archwires, issue of interest is theFor brackets & archwires, issue of interest is the in vivo alteration of material due to the expectedin vivo alteration of material due to the expected long period of performance, with possible effectslong period of performance, with possible effects on mechanical properties.on mechanical properties. Main focus of the alterations induced onMain focus of the alterations induced on orthodontic wires is on Ni Ti archwires becauseorthodontic wires is on Ni Ti archwires because stainless steel & Co-Cr-Ni archwires are usuallystainless steel & Co-Cr-Ni archwires are usually replaced in an escalating stepwise process asreplaced in an escalating stepwise process as treatment progresses.treatment progresses. www.indiandentalacademy.comwww.indiandentalacademy.com

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