Level,align & bite opening

LEVEL, ALIGN ANDLEVEL, ALIGN AND
BITE OPENINGBITE OPENING
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTS:CONTENTS:
 Physical Properties of WiresPhysical Properties of Wires
 Types of wires usedTypes of wires used
 Wire selectionWire selection
 Introduction and DefinitionIntroduction and Definition

 Leveling and Aligning in PEALeveling and Aligning in PEA

Alignment of symmetric CrowdingAlignment of symmetric Crowding

Alignment in Premolar Extraction SituationsAlignment in Premolar Extraction Situations

Alignment in Nonextraction SituationsAlignment in Nonextraction Situations

Alignment of Asymmetric CrowdingAlignment of Asymmetric Crowding

Anchorage control during leveling and aligningAnchorage control during leveling and aligning

Vertical control of incisors, canines and molarsVertical control of incisors, canines and molars

Special problems in aligningSpecial problems in aligning

Surgical Exposure of unerupted/impacted teeth:Surgical Exposure of unerupted/impacted teeth:

 Arch leveling and overbite controlArch leveling and overbite control

The Bite Plate EffectThe Bite Plate Effect

The Importance of Second MolarsThe Importance of Second Molars

Bypass ArchesBypass Arches

Relevelling proceduresRelevelling procedures
 Surgical treatmentSurgical treatment
 Segmental level/alignSegmental level/align

 Aligning in Begg mechanotherapyAligning in Begg mechanotherapy

Arch wires and their manufactureArch wires and their manufacture

Decline in the Use of Multilooped WiresDecline in the Use of Multilooped Wires

Alignment of the teeth without using multilooped wiresAlignment of the teeth without using multilooped wires
in the Refined Beggin the Refined Begg

Arch wire Strength Needed to Negate the Ill Effects ofArch wire Strength Needed to Negate the Ill Effects of
ElasticsElastics

Amount of canine distalization needed to createAmount of canine distalization needed to create
space for relieving the crowdingspace for relieving the crowding

Amount of Wire DeflectionAmount of Wire Deflection

Amount of rotational correction requiredAmount of rotational correction required

Anterior Open BiteAnterior Open Bite

Closing the Anterior SpacingClosing the Anterior Spacing

Molar Position CorrectionMolar Position Correction

 Levelling in begg mechanotherapyLevelling in begg mechanotherapy
 ConclusionConclusion
 BibliographyBibliography

INTRODUCTION AND
DEFINITION

The major stages of comprehensiveThe major stages of comprehensive
orthodontic treatment are ;orthodontic treatment are ;
 (1) alignment and leveling,(1) alignment and leveling,
 (2) correction of molar relationship and space(2) correction of molar relationship and space
closure, andclosure, and
 (3) finishing.(3) finishing.
Tooth leveling and aligning is normallyTooth leveling and aligning is normally
the first orthodontic objective during thethe first orthodontic objective during the
initial stage of treatment.initial stage of treatment.

GOALS OF THE FIRST STAGEGOALS OF THE FIRST STAGE
OF TREATMENT (LEVELLINGOF TREATMENT (LEVELLING
AND ALIGNING) :AND ALIGNING) :
 In almost all patients with malocclusion, at leastIn almost all patients with malocclusion, at least
some teeth are initially malaligned. The greatsome teeth are initially malaligned. The great
majority also have either excessive overbite,majority also have either excessive overbite,
resulting from some combination of anresulting from some combination of an
excessive curve of Spee in the lower arch andexcessive curve of Spee in the lower arch and
an absent or reverse curve of Spee in the upperan absent or reverse curve of Spee in the upper
arch, or (less frequently) anterior open bite witharch, or (less frequently) anterior open bite with
excessive curve of Spee in the upper arch andexcessive curve of Spee in the upper arch and
little or none in the lower arch.little or none in the lower arch.

 The goals of the first phase of treatment are toThe goals of the first phase of treatment are to
bring the teeth into alignment and correctbring the teeth into alignment and correct
vertical discrepancies by leveling out the arches.vertical discrepancies by leveling out the arches.
For proper alignment, it is necessary not only toFor proper alignment, it is necessary not only to
bring malposed teeth into the arch, but also tobring malposed teeth into the arch, but also to
specify and control the anteroposterior positionspecify and control the anteroposterior position
of incisors, the width of the arches posteriorly,of incisors, the width of the arches posteriorly,
and the form of the dental arches.and the form of the dental arches.

 The form of the dental arches obviously variesThe form of the dental arches obviously varies
between individuals.between individuals. Although the orthodontistAlthough the orthodontist
has some latitude in changing arch form, andhas some latitude in changing arch form, and
indeed must do so in at least one arch if theindeed must do so in at least one arch if the
upper and lower arch are not compatible initially.upper and lower arch are not compatible initially.
More stable results are achieved when theMore stable results are achieved when the
patient's original arch form is preserved duringpatient's original arch form is preserved during
orthodontic treatment.orthodontic treatment.

 The light resilient arch wires used in the firstThe light resilient arch wires used in the first
stage of treatment need not be shaped to thestage of treatment need not be shaped to the
patient's arch form as carefully as the heavierpatient's arch form as carefully as the heavier
arch wires used later in treatment, but from thearch wires used later in treatment, but from the
beginning, the arch wires should reflect eachbeginning, the arch wires should reflect each
individual's arch form.individual's arch form. If preformed arch wiresIf preformed arch wires
are used, from the beginning the appropriateare used, from the beginning the appropriate
large, medium or small arch form should belarge, medium or small arch form should be
selected.selected.

 Similarly, in leveling the arch, it is necessary toSimilarly, in leveling the arch, it is necessary to
determine and control whether the levelingdetermine and control whether the leveling
occurs by elongation of posterior teeth, intrusionoccurs by elongation of posterior teeth, intrusion
of incisors, or some specific combination of theof incisors, or some specific combination of the
two.two.

DefinitionDefinition
 It may be defined as ;It may be defined as ; The toothThe tooth
movements needed to achieve passivemovements needed to achieve passive
engagement of a steel rectangular wire ofengagement of a steel rectangular wire of
0.019 / 0.025 dimension and of suitable0.019 / 0.025 dimension and of suitable
arch form, into a correctly placedarch form, into a correctly placed
preadjusted 0.022 bracket system.preadjusted 0.022 bracket system.

Short Terms Versus Long TermShort Terms Versus Long Term
Objectives :Objectives :
 It is helpful to consider leveling and aligningIt is helpful to consider leveling and aligning
against background of short term and long termagainst background of short term and long term
objectives.objectives.

 The short term objectives, in the openingThe short term objectives, in the opening
months of treatment, will be to achieve propermonths of treatment, will be to achieve proper
leveling and aligning into passive rectangularleveling and aligning into passive rectangular
steel wires.steel wires.

 The long term objectives, to be reached by theThe long term objectives, to be reached by the
end of treatment, will be to achieve an idealend of treatment, will be to achieve an ideal
dentition, showing the six keys to normaldentition, showing the six keys to normal
occlusion, and with the dentition properlyocclusion, and with the dentition properly
positioned in the facial profile.positioned in the facial profile.

 During leveling and aligning, therefore, all toothDuring leveling and aligning, therefore, all tooth
movements should be carried out with the finalmovements should be carried out with the final
treatment goal in mind, and anchorage controltreatment goal in mind, and anchorage control
measures should be used to restrict unwantedmeasures should be used to restrict unwanted
tooth movements.tooth movements.

 Experience has repeatedly shown that attemptsExperience has repeatedly shown that attempts
to rush the short term objectives, by taking shortto rush the short term objectives, by taking short
cuts and using heavy forces, cause unwantedcuts and using heavy forces, cause unwanted
changes to take place. These makechanges to take place. These make
achievement of the long term objectives moreachievement of the long term objectives more
time consuming and difficult.time consuming and difficult.

 Today a variety of orthodontic wires areToday a variety of orthodontic wires are
available in the market in both size and materialavailable in the market in both size and material
for almost every application which itself isfor almost every application which itself is
creating problem in selectioncreating problem in selection

Physical Properties of a WirePhysical Properties of a Wire ::

 When an external force acts upon a solid body,When an external force acts upon a solid body,
a reaction force results within the body that isa reaction force results within the body that is
equal in magnitude but opposite in direction toequal in magnitude but opposite in direction to
the external force.the external force.
 The external force will be called the load on theThe external force will be called the load on the
body.body.
 The internal force divided by the area over whichThe internal force divided by the area over which
it acts within the body is the resultantit acts within the body is the resultant stressstress andand
deformation is called asdeformation is called as strainstrain (Change in(Change in
dimension) (Deflection / Unit length).dimension) (Deflection / Unit length).

 Strain may be either elastic (reversible), plasticStrain may be either elastic (reversible), plastic
(permanent) displacement of atoms inside the(permanent) displacement of atoms inside the
material or combination of bothmaterial or combination of both..

Types of Stresses and Strains :Types of Stresses and Strains :
 A material specimen can be subjected to threeA material specimen can be subjected to three
basic modes of force or load application.basic modes of force or load application.
 By means of their directions, stress can beBy means of their directions, stress can be
classified under three types.classified under three types.

Tensile Stress :Tensile Stress :
A tensile stress is carried byA tensile stress is carried by
a load that tends to stretch ora load that tends to stretch or
elongate a body. It is alwayselongate a body. It is always
accompanied by a tensileaccompanied by a tensile
strain.strain.

CompressiveCompressive
StressStress ::
If a body is placed under aIf a body is placed under a
load that tends to compress /load that tends to compress /
shorten it, the internalshorten it, the internal
resistance to such load isresistance to such load is
called compressive stress. Acalled compressive stress. A
compressive stress is alwayscompressive stress is always
accompanied by aaccompanied by a
compressive strain.compressive strain.

Shear StressShear Stress ::
Stress that tends to resistStress that tends to resist
the sliding displacement ofthe sliding displacement of
one side of specimen withone side of specimen with
respect the opposite side orrespect the opposite side or
twisting about specimentwisting about specimen
axis (termed torsion) isaxis (termed torsion) is
shear stress/strain.shear stress/strain.

STRESS:STRESS:
Quotient of applied force and original cross-Quotient of applied force and original cross-
sectional areasectional area..
STRAIN:STRAIN:
Quotient of change in length and the originalQuotient of change in length and the original
reference.reference.

Complex Stresses :Complex Stresses :
 It is extremely difficult to induce a stress of aIt is extremely difficult to induce a stress of a
single type in a body.single type in a body.

ELASTIC LIMIT :ELASTIC LIMIT :
(PROPORTIONAL LIMIT)(PROPORTIONAL LIMIT)
It is a point at which any permanent deformationIt is a point at which any permanent deformation
is first observed.is first observed. The elastic limit of a material isThe elastic limit of a material is
the greatest stress to which a material can bethe greatest stress to which a material can be
subjected, such that it will return to its originalsubjected, such that it will return to its original
dimensions when the forces are released.dimensions when the forces are released. (i.e.(i.e.
atoms will move into their regular positions).atoms will move into their regular positions).

 For relatively small loads, the stress is below theFor relatively small loads, the stress is below the
elastic limit of the material, and reversible elasticelastic limit of the material, and reversible elastic
strain occurs that disappears completely whenstrain occurs that disappears completely when
the specimen is unloaded. When the stressthe specimen is unloaded. When the stress
reaches a sufficiently high load , a ductilereaches a sufficiently high load , a ductile
material begins to undergo permanentmaterial begins to undergo permanent
deformation, whereas a brittle material willdeformation, whereas a brittle material will
fracture without any significant permanentfracture without any significant permanent
deformation.deformation.

Yield Strength :Yield Strength :
 The yield strength is the point at which aThe yield strength is the point at which a
deformation of 0.1% is measured. Unit used isdeformation of 0.1% is measured. Unit used is
pounds / inchpounds / inch22
..

Ultimate Tensile Strength:Ultimate Tensile Strength:
 It is maximal stress required to fracture aIt is maximal stress required to fracture a
structure. It is greatest force that the materialstructure. It is greatest force that the material
can be sustained.can be sustained.

Modulus of Elasticity Young'sModulus of Elasticity Young's
Modulus (Elastic Module):Modulus (Elastic Module):
 It is the ratio of the stress to the strain.It is the ratio of the stress to the strain. It's aIt's a
slope of stress /strain curve.slope of stress /strain curve. If a slope is moreIf a slope is more
horizontal it is springier and if it is vertical wire ishorizontal it is springier and if it is vertical wire is
stiffer.stiffer. A wire having low modulus of elasticityA wire having low modulus of elasticity
has increased flexibility and exerts low forcehas increased flexibility and exerts low force
over large deflection.over large deflection. Wire with high modulus ofWire with high modulus of
elasticity is difficult to bend.elasticity is difficult to bend.

Elastic modulus=b/cElastic modulus=b/c

Stiffness (Load Deflection rate):Stiffness (Load Deflection rate):
It is resistance to deformation.It is resistance to deformation. It isIt is
measure of force required to produce a specificmeasure of force required to produce a specific
deformation.deformation.

 1/springiness = Stiffness = force / distance.1/springiness = Stiffness = force / distance.
 This is proportional to the modulus of elasticity,This is proportional to the modulus of elasticity,
and cross section of a given arch wire.and cross section of a given arch wire.
 It represents the magnitude of force deliveredIt represents the magnitude of force delivered
by the arch wire at a given deflectionby the arch wire at a given deflection

Low stiffness or load deflectionLow stiffness or load deflection
rates provide,rates provide,
 Ability to apply lower forces.Ability to apply lower forces.
 More constant force over time as the applianceMore constant force over time as the appliance
experiences deactivationexperiences deactivation

Flexibility :Flexibility :
 It indicates how much a wire can be strainedIt indicates how much a wire can be strained
without undergoing plastic deformation.without undergoing plastic deformation.

Resiliency:Resiliency:
 Can be defined as the amount of energyCan be defined as the amount of energy
absorbed by a structure when it is stressed notabsorbed by a structure when it is stressed not
to exceed its proportional limit.to exceed its proportional limit. It is area underIt is area under
the Stress-Strain curve.the Stress-Strain curve. This area representsThis area represents
the stored energy.the stored energy.

Spring Back (Range of Action):Spring Back (Range of Action):
 Defined as the distance that the wire will bendDefined as the distance that the wire will bend
elastically before permanent deformation occurs.elastically before permanent deformation occurs.
 If a wire can be deflected over long distancesIf a wire can be deflected over long distances
without permanent deformation, it has a highwithout permanent deformation, it has a high
spring back value.spring back value.
 Higher spring back values provide the ability toHigher spring back values provide the ability to
apply large activation with a resultant increase inapply large activation with a resultant increase in
working time of the appliance. This in turnworking time of the appliance. This in turn
implies that fewer arch wire changes orimplies that fewer arch wire changes or
adjustments will be required.adjustments will be required.

Stress Relaxation :Stress Relaxation :
 Change in the stress over period of time isChange in the stress over period of time is
called stress relaxation. After a substance hascalled stress relaxation. After a substance has
been deformed, the displaced atoms may bebeen deformed, the displaced atoms may be
said to be "uncomfortable" and wish to return tosaid to be "uncomfortable" and wish to return to
heir normal positions. Given time, by diffusionheir normal positions. Given time, by diffusion
they will slowly move back to their equilibriumthey will slowly move back to their equilibrium
relationship.relationship.
 The result is a change in the shape or contourThe result is a change in the shape or contour
of the solid as a gross manifestation of theof the solid as a gross manifestation of the
arrangement in atomic / molecular positions.arrangement in atomic / molecular positions.
 Such a relief of stress is known as relaxation.Such a relief of stress is known as relaxation.

Zero Stress Relaxation :Zero Stress Relaxation :
 When the wire is held in deflected position for aWhen the wire is held in deflected position for a
longtime, if the stress does not reduce and wirelongtime, if the stress does not reduce and wire
still exerts a constant force, that wire is said tostill exerts a constant force, that wire is said to
have zero stress relaxation.have zero stress relaxation. Wires with zeroWires with zero
stress relaxation there is no need for frequentstress relaxation there is no need for frequent
reactivation.reactivation.

Formability :Formability :
 This is the ability to bend the wire into desiredThis is the ability to bend the wire into desired
configurations such as loops, coils and stopsconfigurations such as loops, coils and stops
without fracturing the wires.without fracturing the wires.
 It is a distance along the X-axis from yield pointIt is a distance along the X-axis from yield point
to failure point in stress strain curve.to failure point in stress strain curve.

Ductility:Ductility:
 Ability of a material to withstand permanentAbility of a material to withstand permanent
deformation under a tensile load withoutdeformation under a tensile load without
fracture. A metal that may be drawn readily intofracture. A metal that may be drawn readily into
a wire is said to be ductile.a wire is said to be ductile.
 It is important clinically because alloy must haveIt is important clinically because alloy must have
sufficient ductility so that it will not fracture undersufficient ductility so that it will not fracture under
accidental loading during fabrication of anaccidental loading during fabrication of an
appliance.appliance.
 Ductility decreases with increase in temperature.Ductility decreases with increase in temperature.
 Gold is most ductile. Silver is less ductile thanGold is most ductile. Silver is less ductile than
gold.gold.

Malleability:Malleability:
 The ability of a material to withstand permanentThe ability of a material to withstand permanent
deformation without rupture under compression,deformation without rupture under compression,
as in hammering or rolling into a sheet, isas in hammering or rolling into a sheet, is
termed malleability. Malleability increases withtermed malleability. Malleability increases with
increase in temperature. Gold is most malleableincrease in temperature. Gold is most malleable
metal.metal.

Hardness :Hardness :
 Resistance to indentation. Factors influencingResistance to indentation. Factors influencing
the hardness of a material are its Strength,the hardness of a material are its Strength,
Proportional limit, Ductility, Malleability,Proportional limit, Ductility, Malleability,
Resistance to abrasion.Resistance to abrasion.

Friction :Friction :
 It is proportional to the force of contact, and theIt is proportional to the force of contact, and the
nature of the surface at the bracket / wirenature of the surface at the bracket / wire
interface.interface.
 Excessive amounts of bracket wire friction mayExcessive amounts of bracket wire friction may
result in loss of anchorage or bindingresult in loss of anchorage or binding
accompanied by little or no tooth movement foraccompanied by little or no tooth movement for
a given force.a given force.

 An ideal wire material for orthodontic purposesAn ideal wire material for orthodontic purposes
should possess high strength, low stiffness, highshould possess high strength, low stiffness, high
range and high formability.range and high formability.

The Behavior of an Arch wireThe Behavior of an Arch wire
depends upon :depends upon :
 The diameter of the wireThe diameter of the wire
 The composition of the wireThe composition of the wire
 The length and configuration of the inter-bracketThe length and configuration of the inter-bracket
spanspan
 The width of the bracketsThe width of the brackets
 Friction between the wire and the bracketFriction between the wire and the bracket
channelchannel

The influence of wire diameter :The influence of wire diameter :
 The relationship between a force applied by aThe relationship between a force applied by a
wire (in elastic deformation) and its length,wire (in elastic deformation) and its length,
diameter, and amount of bending is expresseddiameter, and amount of bending is expressed
in the formula;in the formula;
DRDR44
FF αα ------------
LL33
 Where F is the force, D is the amount ofWhere F is the force, D is the amount of
deformation or bending expressed in millimeters,deformation or bending expressed in millimeters,
R is the radius and L is the length of the wire.R is the radius and L is the length of the wire.

 Small variations in the length and radius of aSmall variations in the length and radius of a
wire have a major effect upon its stiffness.wire have a major effect upon its stiffness.
Doubling the radius increases the stiffness by aDoubling the radius increases the stiffness by a
factor of 16, while doubling its length reducesfactor of 16, while doubling its length reduces
the stiffness by a factor of 8.the stiffness by a factor of 8.
 Range is inversely proportional to the diameter,Range is inversely proportional to the diameter,
so doubling the diameter halves the range, andso doubling the diameter halves the range, and
the wire can only be bent half as far beforethe wire can only be bent half as far before
attaining its elastic limit.attaining its elastic limit.

The influence of wireThe influence of wire
compositioncomposition

 Orthodontic wires which generate the bio-Orthodontic wires which generate the bio-
mechanical forces communicated throughmechanical forces communicated through
brackets for tooth movement, are central to thebrackets for tooth movement, are central to the
practice of the profession. In the rationalpractice of the profession. In the rational
selection of the wires for a treatment, theselection of the wires for a treatment, the
orthodontist should consider a variety of factors,orthodontist should consider a variety of factors,
including the amount of force delivery that isincluding the amount of force delivery that is
desired, the elastic (working) range or springdesired, the elastic (working) range or spring
back, formability or ease of manipulation and theback, formability or ease of manipulation and the
need for soldering and welding. In vivoneed for soldering and welding. In vivo
corrosion, with release of metal ions, andcorrosion, with release of metal ions, and
ensuing bio-compatibility concerns for theensuing bio-compatibility concerns for the
patients are also important factors.patients are also important factors.

ORTHODONTIC WIRESORTHODONTIC WIRES

Types of wires usedTypes of wires used ::
 Stainless steel - round, rectangular andStainless steel - round, rectangular and
multi strandedmulti stranded
 Nickel titanium alloysNickel titanium alloys
 Alfa titaniumAlfa titanium
 ββ titanium (TMA)titanium (TMA)
 Titanium - NiobiumTitanium - Niobium
 Cobalt – ChromiumCobalt – Chromium
 Composite plasticComposite plastic

GOLD ALLOY WIRESGOLD ALLOY WIRES
 Historically, gold alloy wires were first used inHistorically, gold alloy wires were first used in
orthodontic practice, although these noble metalorthodontic practice, although these noble metal
wires have minimal use currently because ofwires have minimal use currently because of
their much greater cost.their much greater cost.
 Composition similar to those of type IV goldComposition similar to those of type IV gold
casting alloys.casting alloys.
 Elastic delivery force much less than that ofElastic delivery force much less than that of
stainless steel wires.stainless steel wires.
 Substantial hardening and strengthening couldSubstantial hardening and strengthening could
be achieved by an appropriate heat treatmentbe achieved by an appropriate heat treatment

STAINLESS STEEL WIRESSTAINLESS STEEL WIRES
 By 1950’s stainless steel alloys were used forBy 1950’s stainless steel alloys were used for
most orthodontics wires.most orthodontics wires.
 Most widely used material.Most widely used material.
 Its elastic properties make it well suited for useIts elastic properties make it well suited for use
as an arch wire material,as an arch wire material,
 Has the advantage of availability in a wide rangeHas the advantage of availability in a wide range
of sizes and popular because of their favorableof sizes and popular because of their favorable
combination of low cost and excellentcombination of low cost and excellent
formability.formability.

 The stainless steel alloys used for orthodonticThe stainless steel alloys used for orthodontic
wires are of the “18-8” austenitic type, containingwires are of the “18-8” austenitic type, containing
18% chromium and 8% nickel18% chromium and 8% nickel
 The chromium forms a thin passivating oxideThe chromium forms a thin passivating oxide
layer that provides corrosion resistance bylayer that provides corrosion resistance by
blocking the diffusion of oxygen to underlyingblocking the diffusion of oxygen to underlying
bulky alloy.bulky alloy.
 Since nickel atoms are not strongly bonded, theSince nickel atoms are not strongly bonded, the
likelihood of in vivo slow nickel release fromlikelihood of in vivo slow nickel release from
alloy is increased, which may have implicationsalloy is increased, which may have implications
for bio-compatibility.for bio-compatibility.

 Heat treatment at temperatures between 400Heat treatment at temperatures between 400oo
cc
and 500and 50000
c is recommended to eliminate residualc is recommended to eliminate residual
stress resulting from manufacturing and tostress resulting from manufacturing and to
prevent premature breakage of complexprevent premature breakage of complex
appliances during assembly.appliances during assembly.
 From clinical viewpoint, the purpose of heatFrom clinical viewpoint, the purpose of heat
treating stainless steel orthodontic appliances istreating stainless steel orthodontic appliances is
to minimize breakage rather than to achieveto minimize breakage rather than to achieve
significance increase in resilience.significance increase in resilience.

 The solder joint is primarily formed by surfaceThe solder joint is primarily formed by surface
wetting and mechanical retention of solder at thewetting and mechanical retention of solder at the
work piece surfaces.work piece surfaces.
 In contrast, spot welding of SS causes meltingIn contrast, spot welding of SS causes melting
and solidification of the alloy, with localized lossand solidification of the alloy, with localized loss
of wrought microstructure and increasedof wrought microstructure and increased
stresses in the surrounding heat –affected zonestresses in the surrounding heat –affected zone
where the joint failure is most likely to occur.where the joint failure is most likely to occur.

CHROME-COBALT WIRESCHROME-COBALT WIRES
 A cobalt-chromium-nickel alloy (Elgiloy) wasA cobalt-chromium-nickel alloy (Elgiloy) was
developed during 1950’s by Elgiloy corporationdeveloped during 1950’s by Elgiloy corporation
(Elgin, IL, USA).(Elgin, IL, USA).
 Was originally used for watch springsWas originally used for watch springs
 Available in four tempers (levels of resilience)Available in four tempers (levels of resilience)
 Blue (soft), Yellow (ductile), Green (semi-ductile)Blue (soft), Yellow (ductile), Green (semi-ductile)
and Red (resilient).and Red (resilient).
 All four alloy tempers have same compositionAll four alloy tempers have same composition
and differences in mechanical properties ariseand differences in mechanical properties arise
from variations in wire processing.from variations in wire processing.

 As stainless steel alloy, the corrosion resistanceAs stainless steel alloy, the corrosion resistance
of Elgiloy arises from thin passivating chromiumof Elgiloy arises from thin passivating chromium
oxide layer on the wire surface.oxide layer on the wire surface.
 It can be formed into an arch wire in the 'soft'It can be formed into an arch wire in the 'soft'
state, and then used in that form to apply lightstate, and then used in that form to apply light
forces. Alternatively, it can be 'hardened' byforces. Alternatively, it can be 'hardened' by
heating to increase its stiffness. After heatheating to increase its stiffness. After heat
treatment, the softest Elgiloy becomestreatment, the softest Elgiloy becomes
equivalent to regular stainless steel, while harderequivalent to regular stainless steel, while harder
initial grades are equivalent to the super steels.initial grades are equivalent to the super steels.

 Because of its “soft feel” during manipulation,Because of its “soft feel” during manipulation,
orthodontists can mistakenly believe that as-orthodontists can mistakenly believe that as-
received Elgiloy Blue wires have substantiallyreceived Elgiloy Blue wires have substantially
lower elastic force delivery than stainless steellower elastic force delivery than stainless steel
wires. In reality, the values of modulus ofwires. In reality, the values of modulus of
elasticity for Elgiloy Blue and stainless steelelasticity for Elgiloy Blue and stainless steel
wires are very similar.wires are very similar.
 Other than major difference in composition, theOther than major difference in composition, the
SS and Elgiloy Blue alloys have similar forceSS and Elgiloy Blue alloys have similar force
delivery and joining characteristics.delivery and joining characteristics.
 Elgiloy Blue wires contain comparable amount ofElgiloy Blue wires contain comparable amount of
nickel that found in stainless steel wires, whichnickel that found in stainless steel wires, which
may present concerns about bio-compatibility.may present concerns about bio-compatibility.

BETA-TITANIUM (TMA-TITANIUMBETA-TITANIUM (TMA-TITANIUM
MOLYBDENUM ALLOY)MOLYBDENUM ALLOY)
 Marketed by Ormco Corporation (Glendora, CA,Marketed by Ormco Corporation (Glendora, CA,
USA).USA).
 Conceived for orthodontic use about twoConceived for orthodontic use about two
decades back bydecades back by BURSTONEBURSTONE andand GOLDBERG,GOLDBERG,
who recognized its potential for delivering lowerwho recognized its potential for delivering lower
bio-mechanical forces compared to SS andbio-mechanical forces compared to SS and
chrome-cobalt alloys.chrome-cobalt alloys.
 Elastic modulus ofElastic modulus of β-titanium is approximatelyβ-titanium is approximately
40% that of SS and Elgiloy Blue wires.40% that of SS and Elgiloy Blue wires.
 Significantly improved values of springback ,Significantly improved values of springback ,
which markedly increases their working rangewhich markedly increases their working range
for tooth movement.for tooth movement.

 Offers a highly desirable combination of strengthOffers a highly desirable combination of strength
and springiness (i.e. excellent resilience), as welland springiness (i.e. excellent resilience), as well
as reasonably good formability due to its bccas reasonably good formability due to its bcc
structure.structure.
 Appropriate in its larger sizes a finishing archAppropriate in its larger sizes a finishing arch
wire towards the end of treatment for finalwire towards the end of treatment for final
detailing of tooth position.detailing of tooth position.
 Well suited for sectional mechanics.Well suited for sectional mechanics.
 It is the only orthodontic wire alloy possessingIt is the only orthodontic wire alloy possessing
true weldability.true weldability.
 Most expensive of orthodontic wires.Most expensive of orthodontic wires.

 With increased interest in bio-compatibility ofWith increased interest in bio-compatibility of
orthodontic materials, another important featureorthodontic materials, another important feature
is their absence of nickel that is present in otheris their absence of nickel that is present in other
three major alloy types.three major alloy types.
 SEM studies revealed relatively rough surfaceSEM studies revealed relatively rough surface
that is attributed to adherence or cold welding bythat is attributed to adherence or cold welding by
the titanium to the dies or rollers during wirethe titanium to the dies or rollers during wire
processing which leads to friction, along withprocessing which leads to friction, along with
localized sites of cold welding or adherence bylocalized sites of cold welding or adherence by
the wire to the bracket slot.the wire to the bracket slot.
 Recently developed NRecently developed N++
ion implantationion implantation
technique which yields high concentration oftechnique which yields high concentration of
nitrogen within a few tens of nanometer from thenitrogen within a few tens of nanometer from the
wire surface has markedly improved the slidingwire surface has markedly improved the sliding
friction.friction.

TITANIUM-NIOBIUM WIRESTITANIUM-NIOBIUM WIRES
 Made from a nickel free titanium niobium alloy,Made from a nickel free titanium niobium alloy,
the wires are soft and easy to form, yet have thethe wires are soft and easy to form, yet have the
same working range as stainless steel.same working range as stainless steel.
 The stiffness of titanium niobium in bending isThe stiffness of titanium niobium in bending is
roughly half of that of stainless steel, whereas inroughly half of that of stainless steel, whereas in
torsion it is roughly one third.torsion it is roughly one third.
 The weldability of these wires was found to beThe weldability of these wires was found to be
good.good.

ALPHA-TITANIUM WIRESALPHA-TITANIUM WIRES
 Developed by A.J.Wilcock Jr. in 1988.Developed by A.J.Wilcock Jr. in 1988.
 It has closely packed hexagonal lattice.It has closely packed hexagonal lattice.
 Mainly used as finishing wire.Mainly used as finishing wire.
 This wire is formable and weldable.This wire is formable and weldable.

NICKEL-TITANIUM WIRESNICKEL-TITANIUM WIRES
 The pioneer for development of Niti wires forThe pioneer for development of Niti wires for
orthodontics was Andreasen, who publishedorthodontics was Andreasen, who published
articles advocating their use in early 1970’s.articles advocating their use in early 1970’s.
 The first Niti orthodontic wire alloy (Nitinol) wasThe first Niti orthodontic wire alloy (Nitinol) was
marketed by Unitek Corporation (now 3M Unitek,marketed by Unitek Corporation (now 3M Unitek,
Monrovia, CA, USA).Monrovia, CA, USA).
 The generic name ‘NITINOL” that is applicableThe generic name ‘NITINOL” that is applicable
to this group of Niti alloys originates fromto this group of Niti alloys originates from nickel,nickel,
titaniumtitanium andand Naval Ordnance LaboratoryNaval Ordnance Laboratory wherewhere
the alloy was developed by Buehler andthe alloy was developed by Buehler and
associates.associates.

 The new super elastic Niti wires, Chinese NitiThe new super elastic Niti wires, Chinese Niti
(marketed as Ni-Ti by Ormco) and Japanese Niti(marketed as Ni-Ti by Ormco) and Japanese Niti
(marketed as Sentalloy by GAC international,(marketed as Sentalloy by GAC international,
Islandia, NY, USA) were subsequentlyIslandia, NY, USA) were subsequently
introduced during the mid-1980’s.introduced during the mid-1980’s.
 The Niti wires contain approximately equiatomicThe Niti wires contain approximately equiatomic
proportions of nickel and titanium, and areproportions of nickel and titanium, and are
based on intermetalic compound Nitibased on intermetalic compound Niti
(sometimes written as TiNi)(sometimes written as TiNi)

 There are two major NiTi phases in nickel-There are two major NiTi phases in nickel-
titanium wires. Austenitic Niti has an ordered bcctitanium wires. Austenitic Niti has an ordered bcc
structure that occurs at high temperature andstructure that occurs at high temperature and
low stresses.low stresses.
 Martensitic NiTi has been reported to have aMartensitic NiTi has been reported to have a
distorted monoclinic, triclinic or hexagonaldistorted monoclinic, triclinic or hexagonal
structure and forms at low temperature and highstructure and forms at low temperature and high
stresses.stresses.
 The shape memory effect is associated withThe shape memory effect is associated with
reversible matrensite-austenite transformation,reversible matrensite-austenite transformation,
which occurs rapidly by crystallographic twinningwhich occurs rapidly by crystallographic twinning
at atomic levelat atomic level
 In some cases an intermediate R-phase havingIn some cases an intermediate R-phase having
a rhombohedral crystal structure may forma rhombohedral crystal structure may form
during this transformation process.during this transformation process.

 There are several important phaseThere are several important phase
transformation temperatures for the Niti alloys.transformation temperatures for the Niti alloys.
On cooling , the Ms (martensite-start) and MfOn cooling , the Ms (martensite-start) and Mf
(martensite-finish) at which transformation to(martensite-finish) at which transformation to
martensite begins and is completed,martensite begins and is completed,
respectively.respectively.
 Analogously, on heating, the As (austenite-start)Analogously, on heating, the As (austenite-start)
and Af (austenite-finish) at temperatures atand Af (austenite-finish) at temperatures at
which the transformation to austenite begins andwhich the transformation to austenite begins and
is completed, respectively.is completed, respectively.
 Similar transformation temperature of Rs and RfSimilar transformation temperature of Rs and Rf
may be defined for the R-phase.may be defined for the R-phase.

 The shape- memory wires alloys have AfThe shape- memory wires alloys have Af
temperatures that are below the temperature oftemperatures that are below the temperature of
oral environment, so that the wires haveoral environment, so that the wires have
essentially the completely austenitic structure inessentially the completely austenitic structure in
vivo.vivo.
 For the superelastic Niti alloy , completeFor the superelastic Niti alloy , complete
transformation to austenite occurs only slightlytransformation to austenite occurs only slightly
above the temperature of oral environment,above the temperature of oral environment,
since the Af temperature on heating is abovesince the Af temperature on heating is above
404000
c. Under in vivo conditions, this alloy isc. Under in vivo conditions, this alloy is
predominantly austenite with some R-phase.predominantly austenite with some R-phase.
 For the non-superelastic alloy Nitinol isFor the non-superelastic alloy Nitinol is
composed of martensite, austenite and perhapscomposed of martensite, austenite and perhaps
R-phase at the temperatures of oralR-phase at the temperatures of oral
environment.environment.

 In 1994 Ormco Corporation introduced a newIn 1994 Ormco Corporation introduced a new
orthodontic wire alloy, Copper Ni-Ti, which isorthodontic wire alloy, Copper Ni-Ti, which is
available in three temperature variants of 27available in three temperature variants of 2700
c,c,
353500
c and 40c and 4000
c corresponding to the austenite-c corresponding to the austenite-
finish temperatures for the completion offinish temperatures for the completion of
martensite-to-austenite transformation.martensite-to-austenite transformation.
 These variants would be useful for differentThese variants would be useful for different
types of orthodontic patients. For ex, the 27types of orthodontic patients. For ex, the 2700
cc
variant would be useful for mouth breathers; thevariant would be useful for mouth breathers; the
353500
c variant is is activated at normal bodyc variant is is activated at normal body
temperature; and the40temperature; and the4000
c variant would providec variant would provide
activation only after consuming hot food andactivation only after consuming hot food and
beverages.beverages.

 KusyKusy has suggested that the NiTi wireshas suggested that the NiTi wires
products can alternatively be classified intoproducts can alternatively be classified into
following three categories:following three categories:

Stabilized Martensitic Alloys (M-NiTi) :Stabilized Martensitic Alloys (M-NiTi) :
 Do not posses shape memory or superelasticity asDo not posses shape memory or superelasticity as
processing of the wire creates a stable martensiticprocessing of the wire creates a stable martensitic
structurestructure
 This alloy has a fixed composition , which isThis alloy has a fixed composition , which is
incapable of demonstrating changes in its crystalincapable of demonstrating changes in its crystal
structure.structure.
 Its elastic properties are the result of its inherentlyIts elastic properties are the result of its inherently
stable structure.stable structure.
 ex, Nitinolex, Nitinol..

Active Martensitic Alloy (ThermalActive Martensitic Alloy (Thermal
NiTi) :NiTi) :
 Have shape memory, oral environment raisesHave shape memory, oral environment raises
the temperature of deformed arch wire whichthe temperature of deformed arch wire which
demonstrates a change in crystal structure fromdemonstrates a change in crystal structure from
martensite to austenitemartensite to austenite
 This thermo elastic shape memory can beThis thermo elastic shape memory can be
observed by clinician if deformed arch wireobserved by clinician if deformed arch wire
segment is warmed in the hands,segment is warmed in the hands,
 ex, Sentalloy and Copper Ni-Ti.ex, Sentalloy and Copper Ni-Ti.

Active Austenitic Alloys (A-NiTi) :Active Austenitic Alloys (A-NiTi) :
 On application of stress, wire demonstrates aOn application of stress, wire demonstrates a
change in crystal structure from austenite tochange in crystal structure from austenite to
martensite.martensite.
 The reverse transformation from martensiteThe reverse transformation from martensite
back to austenite takes place during unloadingback to austenite takes place during unloading
(deactivation).(deactivation).
 Display superelastic behavior.Display superelastic behavior.

 Have relatively high surface roughness, resultingHave relatively high surface roughness, resulting
in high arch wire-bracket friction.in high arch wire-bracket friction.
 One manufacturer (GAC international) offers anOne manufacturer (GAC international) offers an
ion-implanted NiTi alloy, which is expected toion-implanted NiTi alloy, which is expected to
have reduced sliding friction.have reduced sliding friction.
 Concern among some orthodontists about bio-Concern among some orthodontists about bio-
compatibility problems associated with ofcompatibility problems associated with of
release of nickel ions in vivo.release of nickel ions in vivo.
 Clinical disadvantages of NiTi alloys are thatClinical disadvantages of NiTi alloys are that
bends can't readily be placed in the wires andbends can't readily be placed in the wires and
the wires can't be solderedthe wires can't be soldered

 Heat treatment of these wires is convenientlyHeat treatment of these wires is conveniently
performed by an electrical resistance technique,performed by an electrical resistance technique,
and a commercial apparatus (ArchMate, GACand a commercial apparatus (ArchMate, GAC
International) allows the orthodontics toInternational) allows the orthodontics to
prepare custom superelastic NiTi wires forprepare custom superelastic NiTi wires for
specific patients.specific patients.

Multi-stranded/co-axial stainlessMulti-stranded/co-axial stainless
steel wires:steel wires:
 Made by building up a strand of SS wires aroundMade by building up a strand of SS wires around
a core wire.a core wire.
 More flexible due to contact slips between wrapMore flexible due to contact slips between wrap
wires and core wires of strand.wires and core wires of strand.
 Are available in round, rectangular and squareAre available in round, rectangular and square
cross-section.cross-section.

Composite Plastics:Composite Plastics:
 Developed from materials used in aerospaceDeveloped from materials used in aerospace
technology.technology.
 Optiflex, marketed by Ormco, is a compositeOptiflex, marketed by Ormco, is a composite
structure formed by top-coating optical glassstructure formed by top-coating optical glass
fibres with a hot melt adhesive and a nylon skin.fibres with a hot melt adhesive and a nylon skin.
The result is a 0.017 wire with an 0.008 glassThe result is a 0.017 wire with an 0.008 glass
core. Advantage of this wire are light forces forcore. Advantage of this wire are light forces for
initial alignment and excellent esthetics.initial alignment and excellent esthetics.

The Length and Configuration of theThe Length and Configuration of the
Inter-Bracket Span :Inter-Bracket Span :
 Relatively large inter bracket spans allow aRelatively large inter bracket spans allow a
relatively large length of archwire to lie betweenrelatively large length of archwire to lie between
the brackets. The force delivered to the teeththe brackets. The force delivered to the teeth
will then be low compared with that seen with awill then be low compared with that seen with a
low inter bracket span, and the range of action oflow inter bracket span, and the range of action of
the archwire will be enhanced.the archwire will be enhanced.

 When wide brackets are used, the length of theWhen wide brackets are used, the length of the
inter bracket spans inevitably reduced.inter bracket spans inevitably reduced.
 Reduction in archwire stiffness or theReduction in archwire stiffness or the
incorporation of loops may need to beincorporation of loops may need to be
considered in order to increase the flexibility ofconsidered in order to increase the flexibility of
the archwirethe archwire..

The influence of bracket width :The influence of bracket width :
 The wider the bracket, the easier it will be toThe wider the bracket, the easier it will be to
generate the moments needed to control thegenerate the moments needed to control the
mesiodistal position of the roots.mesiodistal position of the roots. The widerThe wider
bracket reduces both the force needed tobracket reduces both the force needed to
generate the moment and the contact angle andgenerate the moment and the contact angle and
is thus advantageous for space closure byis thus advantageous for space closure by
sliding.sliding.

 However, the wider the bracket on a tooth, theHowever, the wider the bracket on a tooth, the
smaller the inter bracket spans betweensmaller the inter bracket spans between
adjacent teeth and therefore, the shorter theadjacent teeth and therefore, the shorter the
effective length of the archwire segmentseffective length of the archwire segments
between supports. This greatly decreases bothbetween supports. This greatly decreases both
the springiness of the archwire and its range ofthe springiness of the archwire and its range of
action.action.

The Influence of FrictionThe Influence of Friction

Surface Qualities of Wires :Surface Qualities of Wires :
 As the titanium content of an alloy increases, itsAs the titanium content of an alloy increases, its
surface reactivity increase, its surfacesurface reactivity increase, its surface
roughness increases, and the surface chemistryroughness increases, and the surface chemistry
is a major influence on frictional behavior.is a major influence on frictional behavior.

 The surface of NiTi is rougher than that ofThe surface of NiTi is rougher than that of
stainless steel. Butstainless steel. But ββ titanium is rougher thantitanium is rougher than
NiTi due to it's titanium content. (NiTi due to it's titanium content. (ββ Titanium hasTitanium has
80% when compared to NiTi which has only80% when compared to NiTi which has only
50% of titanium).50% of titanium).
 This problem could be handled by ionThis problem could be handled by ion
implantation onto the surface.implantation onto the surface.

Surface Qualities of Brackets :Surface Qualities of Brackets :
 Most modern orthodontic brackets are madeMost modern orthodontic brackets are made
from stainless steel, and if properly polished,from stainless steel, and if properly polished,
have relatively smooth surfaces comparable withhave relatively smooth surfaces comparable with
steel wires.steel wires.
 Titanium brackets may be rougher, and slidingTitanium brackets may be rougher, and sliding
with titanium brackets may be problematic.with titanium brackets may be problematic.

 The problems related to frictional resistanceThe problems related to frictional resistance
have limited the use of ceramic brackets.have limited the use of ceramic brackets.
 The ones made from polycrystalline ceramicsThe ones made from polycrystalline ceramics
have considerably rougher surfaces than steelhave considerably rougher surfaces than steel
brackets.brackets.

How to Select a Correct Wire forHow to Select a Correct Wire for
a Clinical Situation?a Clinical Situation?
 From the preceding sections, it is evident thatFrom the preceding sections, it is evident that
there is no ideal orthodontic wire alloy.there is no ideal orthodontic wire alloy.
 Given the recent proliferation of wire alloyGiven the recent proliferation of wire alloy
choices and sizes, the diverse treatmentchoices and sizes, the diverse treatment
philosophies, and the empirical nature ofphilosophies, and the empirical nature of
orthodontics, it is sometimes difficult to select aorthodontics, it is sometimes difficult to select a
suitable wire for a particular clinical situation.suitable wire for a particular clinical situation. AA
few questions should be answered.few questions should be answered.

 How much control is required ?How much control is required ?
 What are the load / deflection requirements?What are the load / deflection requirements?
 Elastic or Plastic Working Range ? Do we wishElastic or Plastic Working Range ? Do we wish
to place bends in the Wire ?to place bends in the Wire ?
 Wire Cost Vs Value ?Wire Cost Vs Value ?

 Burstone and Goldberg have provided severalBurstone and Goldberg have provided several
clinical examples where the use of beta-titaniumclinical examples where the use of beta-titanium
offers advantages to the orthodontists i,eoffers advantages to the orthodontists i,e
alignment of teeth during finishing , the rotationalignment of teeth during finishing , the rotation
and changing of axial orientation of teeth, theand changing of axial orientation of teeth, the
use of specialized springs or auxiliaries such asuse of specialized springs or auxiliaries such as
intrusive arches. The weldability of TMA is veryintrusive arches. The weldability of TMA is very
useful when assembly of a complex appliance isuseful when assembly of a complex appliance is
needed.needed.

 Andereasen and Morrow emphasized the benefitAndereasen and Morrow emphasized the benefit
of rectangular Nitinol arch wires for earlyof rectangular Nitinol arch wires for early
treatment stages, where simultaneous rotation,treatment stages, where simultaneous rotation,
leveling could be performed. They pointed outleveling could be performed. They pointed out
that in some cases treatment can begin with fullthat in some cases treatment can begin with full
sized rectangular wires that nearly fill the slot.sized rectangular wires that nearly fill the slot.
Clinical examples, such as crossbite correction,Clinical examples, such as crossbite correction,
uprighting of impacted canines and openinguprighting of impacted canines and opening
bites.bites.

 The superelastic and shape memory nickel-The superelastic and shape memory nickel-
titanium wires are particularly useful where largetitanium wires are particularly useful where large
deflections are necessary for badlydeflections are necessary for badly
malpositioned teeth. Orthodontic appliancesmalpositioned teeth. Orthodontic appliances
fabricated from these wires will generate thefabricated from these wires will generate the
most nearly constant forces during major stagesmost nearly constant forces during major stages
of tooth movement.of tooth movement.

 Burstone has pointed out that multistrandedBurstone has pointed out that multistranded
wires can be used advantageously in a variety ofwires can be used advantageously in a variety of
applications. These include initial torque control,applications. These include initial torque control,
a transition between round and rectangulara transition between round and rectangular
wires, and a finishing wires at the end treatment.wires, and a finishing wires at the end treatment.

Current Trend :Current Trend :
 In the past the usual method of regulating theIn the past the usual method of regulating the
magnitude of force from an orthodonticmagnitude of force from an orthodontic
appliance was primarily variation in the crossappliance was primarily variation in the cross
sectional dimensions of the wires used.sectional dimensions of the wires used.
Although configurations such as loops haveAlthough configurations such as loops have
been used to lower forces, small wires werebeen used to lower forces, small wires were
used for light forces and large wires for heavierused for light forces and large wires for heavier
ones. Hence traditional orthodontics may beones. Hence traditional orthodontics may be
described asdescribed as "variable cross section"variable cross section
orthodontics".orthodontics".

 Further development of materials in orthodonticsFurther development of materials in orthodontics
was influenced by the orthodontist's demands towas influenced by the orthodontist's demands to
have appliance systems that were relativelyhave appliance systems that were relatively
resistant to permanent deformation, thusresistant to permanent deformation, thus
providing a large range of activation. This blendproviding a large range of activation. This blend
of characteristics required the use of materialsof characteristics required the use of materials
that had high yield strength to elastic modulusthat had high yield strength to elastic modulus
ratio, as demonstrated by NiTi and TMA. Withratio, as demonstrated by NiTi and TMA. With
the introduction of these materials tothe introduction of these materials to
orthodontics, a new clinical strategy evolved,orthodontics, a new clinical strategy evolved,
namely thenamely the "variable modulus orthodontics"."variable modulus orthodontics".

 The generation of superelastic andThe generation of superelastic and
thermodynamic nickel-titanium wires like neo-thermodynamic nickel-titanium wires like neo-
sentalloy, Cu-NiTi, etc, represents another majorsentalloy, Cu-NiTi, etc, represents another major
advance from the previous concepts.advance from the previous concepts. By takingBy taking
advantage of the body temperature, and byadvantage of the body temperature, and by
setting the alloy's transformation temperature forsetting the alloy's transformation temperature for
the martensitic transformation, precise control ofthe martensitic transformation, precise control of
the memory phenomenon can be effected.the memory phenomenon can be effected. ThisThis
is calledis called "variable transformation temperature"variable transformation temperature
orthodontics".orthodontics".

WIRE SEQUENCEWIRE SEQUENCE
ACCORDING TO DIFFERENTACCORDING TO DIFFERENT
ORTHODONTIC CONCEPTS :ORTHODONTIC CONCEPTS :

LEVELLING ALIGNINGLEVELLING ALIGNING
IN PRE-ADJUSTEDIN PRE-ADJUSTED
APPLIANCEAPPLIANCE

ALIGNMENT :ALIGNMENT :
Principles in the Choice of AlignmentPrinciples in the Choice of Alignment
Arches :Arches :

 In nearly every patient with malaligned teeth, theIn nearly every patient with malaligned teeth, the
root apices are closer to the normal positionroot apices are closer to the normal position
than the crowns, because malalignment almostthan the crowns, because malalignment almost
always develops as the eruption paths of teethalways develops as the eruption paths of teeth
are deflected.are deflected.

 Putting it another way, a tooth bud occasionallyPutting it another way, a tooth bud occasionally
develops in the wrong place, (barring surgerydevelops in the wrong place, (barring surgery
that displaces all tissues in the area, asthat displaces all tissues in the area, as
sometimes happens in cleft palate repairs, or thesometimes happens in cleft palate repairs, or the
severe tipping from lip pressure that displacessevere tipping from lip pressure that displaces
maxillary central incisors in Class II, division 2maxillary central incisors in Class II, division 2
cases) but the root apices are likely to becases) but the root apices are likely to be
reasonably close to their correct positions evenreasonably close to their correct positions even
though the crowns have been displaced as thethough the crowns have been displaced as the
teeth erupted.teeth erupted.

 To bring teeth into alignment, a combination ofTo bring teeth into alignment, a combination of
labiolingual and mesiodistal tipping guided by anlabiolingual and mesiodistal tipping guided by an
arch wire is needed, but root movement usuallyarch wire is needed, but root movement usually
is not.is not.

Several important consequences forSeveral important consequences for
orthodontic mechanotherapy follow fromorthodontic mechanotherapy follow from
this :this :
 Initial arch wires for alignment should provideInitial arch wires for alignment should provide
light, continuous force of approximately 50light, continuous force of approximately 50
grams, to produce the most efficient tippinggrams, to produce the most efficient tipping
tooth movement. Heavy force, in contrast, is totooth movement. Heavy force, in contrast, is to
be avoided.be avoided.

 The arch wires should be able to move freelyThe arch wires should be able to move freely
within the brackets. This means that thewithin the brackets. This means that the
largest initial arch wire that should be usedlargest initial arch wire that should be used
with an 18-slot edgewise bracket is 16 mil,with an 18-slot edgewise bracket is 16 mil,
whereas 14 mil would be more satisfactory.whereas 14 mil would be more satisfactory.
With the 22 slot bracket, an 18 mil arch wireWith the 22 slot bracket, an 18 mil arch wire
would be close to ideal from a bracketwould be close to ideal from a bracket
clearance point view.clearance point view.

 Rectangular arch wires, particularly those withRectangular arch wires, particularly those with
a tight fit within the bracket slot so that thea tight fit within the bracket slot so that the
position of the root apex could be affected,position of the root apex could be affected,
normally should be avoided.normally should be avoided.
 The springier the alignment arch wire, theThe springier the alignment arch wire, the
more important it is that the crowding be atmore important it is that the crowding be at
least reasonably symmetric. If only one toothleast reasonably symmetric. If only one tooth
is crowded out of line a rigid wire is neededis crowded out of line a rigid wire is needed
that maintains arch form except wherethat maintains arch form except where
springiness is required, and an auxiliary wirespringiness is required, and an auxiliary wire
should be used to reach the malaligned tooth.should be used to reach the malaligned tooth.

Alignment of symmetric CrowdingAlignment of symmetric Crowding
Arch Wire Choices :Arch Wire Choices :
 The flat load deflection curve of superelastic NiTiThe flat load deflection curve of superelastic NiTi
makes ideal for initial alignment when themakes ideal for initial alignment when the
degree of crowding is similar on the two sides ofdegree of crowding is similar on the two sides of
the arch. The superelastic wire providesthe arch. The superelastic wire provides
remarkable range over which a tooth can beremarkable range over which a tooth can be
moved without generating excessive force.moved without generating excessive force.
Under most circumstances initial alignment canUnder most circumstances initial alignment can
be accomplished simply by tying 14 or 16 mil A-be accomplished simply by tying 14 or 16 mil A-
NiTi that delivers about 50 gm into the bracketsNiTi that delivers about 50 gm into the brackets
of all the teeth, being careful not to tie too tightly.of all the teeth, being careful not to tie too tightly.

 It is possible now to obtain superelastic wiresIt is possible now to obtain superelastic wires
that are almost totally passive when cold, butthat are almost totally passive when cold, but
deliver the desired force when at mouthdeliver the desired force when at mouth
temperature. Placing a chilled wire is muchtemperature. Placing a chilled wire is much
easier than placing a springy one, and this caneasier than placing a springy one, and this can
be significant advantage under somebe significant advantage under some
circumstances.circumstances.

 As one might expect, the extreme springiness ofAs one might expect, the extreme springiness of
superelastic wires is not a totally unmixedsuperelastic wires is not a totally unmixed
blessing.blessing. When these wires are tied into aWhen these wires are tied into a
malocclusion, they have a tendency to "travel"malocclusion, they have a tendency to "travel"
around the arch as the patient chews, especiallyaround the arch as the patient chews, especially
if function is mostly on one side.if function is mostly on one side. Then the wireThen the wire
sticks out the back of the molar tube on onesticks out the back of the molar tube on one
side, and may come out of the tube on the otherside, and may come out of the tube on the other
side.side.

Alignment in Premolar ExtractionAlignment in Premolar Extraction
SituationsSituations
 In patients with severe crowding of anteriorIn patients with severe crowding of anterior
teeth, it is necessary to retract the canines intoteeth, it is necessary to retract the canines into
premolar extraction sites to gain enough spacepremolar extraction sites to gain enough space
to align the incisors.to align the incisors. In extremely severeIn extremely severe
crowding, it is better to retract the caninescrowding, it is better to retract the canines
independently before placing attachments on theindependently before placing attachments on the
incisors.incisors. Sliding the canines produces moreSliding the canines produces more
stress on the posterior anchorage, so criticalstress on the posterior anchorage, so critical
anchorage is an indication for the retractionanchorage is an indication for the retraction
loops.loops.

 In more typical and less extreme crowding, it isIn more typical and less extreme crowding, it is
possible to simultaneously tip the caninespossible to simultaneously tip the canines
distally and align the incisors. The samedistally and align the incisors. The same
independent distal movement of the caninesindependent distal movement of the canines
now can be obtained with an A-NiTi arch wire,now can be obtained with an A-NiTi arch wire,
and A-NiTi coil springs from the first molars to tipand A-NiTi coil springs from the first molars to tip
the canines distally. When this is done, thethe canines distally. When this is done, the
spring should be chosen to deliver only 50 gm,spring should be chosen to deliver only 50 gm,
and an arch wire preformed by the manufacturerand an arch wire preformed by the manufacturer
to have an exaggerated reverse curve of speeto have an exaggerated reverse curve of spee
should be chosen, to limit forward tipping of theshould be chosen, to limit forward tipping of the
molars.molars.

Alignment in Non-extractionAlignment in Non-extraction
SituationsSituations ::
 Alignment in non extraction cases requiresAlignment in non extraction cases requires
increasing arch length, moving the incisorsincreasing arch length, moving the incisors
further from the molars. In this circumstance,further from the molars. In this circumstance,
just tying a superelastic wire into the bracketjust tying a superelastic wire into the bracket
slots is ineffective. Two objects cannot occupyslots is ineffective. Two objects cannot occupy
the same space at the same time, so alignmentthe same space at the same time, so alignment
cannot occur until space to allow it is created.cannot occur until space to allow it is created.

Alignment of AsymmetricAlignment of Asymmetric
CrowdingCrowding
 When all or nearly all the crowding is in oneWhen all or nearly all the crowding is in one
place, what is needed is an arch wire that is rigidplace, what is needed is an arch wire that is rigid
where the teeth are already aligned, and quitewhere the teeth are already aligned, and quite
springy where they are not.springy where they are not. Nothing in this worldNothing in this world
is an unmixed blessing, and the extremeis an unmixed blessing, and the extreme
springiness of a superelastic wire means that if itspringiness of a superelastic wire means that if it
is tie into an asymmetrically maligned arch, teethis tie into an asymmetrically maligned arch, teeth
distant to the site of malalignment will be moveddistant to the site of malalignment will be moved

 A impacted canine is the prime example ofA impacted canine is the prime example of
asymmetric malalignment.asymmetric malalignment. If a continuousIf a continuous
superelastic wire were tied to the impacted toothsuperelastic wire were tied to the impacted tooth
and to the lateral incisor and premolar adjacentand to the lateral incisor and premolar adjacent
to it, the incisor and premolar would be tippedto it, the incisor and premolar would be tipped
into the canine space the same amount that theinto the canine space the same amount that the
canine was pulled toward proper positioncanine was pulled toward proper position..

 If one lateral incisor is blocked out of the archIf one lateral incisor is blocked out of the arch
and must be brought into position, the sameand must be brought into position, the same
guideline applied.guideline applied.

 It is easy to add a small diameter superelasticIt is easy to add a small diameter superelastic
wire as an auxiliary spring, so that a stiff mainwire as an auxiliary spring, so that a stiff main
arch (16 or 18 steel) can be tied into all the teetharch (16 or 18 steel) can be tied into all the teeth
except the displaced one.except the displaced one. A segment ofA segment of
superelastic NiTi can be laid in the brackets onsuperelastic NiTi can be laid in the brackets on
top of the main arch wire, or tied below thetop of the main arch wire, or tied below the
brackets of the anchor teeth, and tied to thebrackets of the anchor teeth, and tied to the
bracket on the displaced tooth.bracket on the displaced tooth.

 With this arrangement, the correct light force toWith this arrangement, the correct light force to
bring the displaced tooth into alignment isbring the displaced tooth into alignment is
provided by the NiTi wire, and the reciprocalprovided by the NiTi wire, and the reciprocal
force is distributed over all the rest of the teeth.force is distributed over all the rest of the teeth.
The result is efficient movement of the displacedThe result is efficient movement of the displaced
tooth, with excellent preservation of arch form.tooth, with excellent preservation of arch form.
 Note that there are two advantages of theNote that there are two advantages of the
superelastic auxiliary wire; control of thesuperelastic auxiliary wire; control of the
tendency to distort arch form, and light forcetendency to distort arch form, and light force
against the tooth to be moved.against the tooth to be moved.

ANCHORAGE CONTROLANCHORAGE CONTROL
DURING LEVELLING ANDDURING LEVELLING AND
ALIGNINGALIGNING

LACEBACKS FOR A/PLACEBACKS FOR A/P
CANINE CONTROLCANINE CONTROL
 Lace backs are 0.010 or 0.009 ligature wiresLace backs are 0.010 or 0.009 ligature wires
which extend from the most distally bandedwhich extend from the most distally banded
molar to the canine bracket.molar to the canine bracket. They restrictThey restrict
canine crowns from tipping forward duringcanine crowns from tipping forward during
leveling and aligning.leveling and aligning.

 They are mainly used in premolar extractionThey are mainly used in premolar extraction
cases, but they may also be required in somecases, but they may also be required in some
non extraction cases where there is a localnon extraction cases where there is a local
threat to anchorage. For example, if the root ofthreat to anchorage. For example, if the root of
a canine is mesially placed, this will effectivelya canine is mesially placed, this will effectively
increase the tip in the canine bracket at the startincrease the tip in the canine bracket at the start
of treatment, and hence increase the anchorageof treatment, and hence increase the anchorage
needs of that tooth.needs of that tooth.

 Lace backs are passive devices, and should notLace backs are passive devices, and should not
be over tightened to an extent that tissuebe over tightened to an extent that tissue
blanching occurs. They are placed before theblanching occurs. They are placed before the
arch wire. At monthly adjustment visits, the lacearch wire. At monthly adjustment visits, the lace
backs are normally loose, and require 1-2 mm ofbacks are normally loose, and require 1-2 mm of
tightening.tightening.

 The initial purpose of lace backs was to preventThe initial purpose of lace backs was to prevent
canines from tipping forward, but it wascanines from tipping forward, but it was
observed that, where necessary, these ligatureobserved that, where necessary, these ligature
wires were an effective method of distalizing thewires were an effective method of distalizing the
canines without causing unwanted tippingcanines without causing unwanted tipping
 Lace backs are normally continued throughoutLace backs are normally continued throughout
the leveling and aligning arch wires sequence. .the leveling and aligning arch wires sequence. .

BENDBACKS FOR A/P INCISORBENDBACKS FOR A/P INCISOR
CONTROL :CONTROL :
 These are used as an important method ofThese are used as an important method of
anchorage support.anchorage support.
 If the arch wire is bent back immediately behindIf the arch wire is bent back immediately behind
the tube on the most distally banded molar, thisthe tube on the most distally banded molar, this
serves to minimize forward tipping of incisors.serves to minimize forward tipping of incisors.
 Like lace backs, bend backs are normallyLike lace backs, bend backs are normally
continued throughout the leveling and aligningcontinued throughout the leveling and aligning
which requires A/P control of incisors.which requires A/P control of incisors.

 In cases where it is necessary to increase archIn cases where it is necessary to increase arch
length during leveling and aligning and wherelength during leveling and aligning and where
A/P incisor control is not required, bend backsA/P incisor control is not required, bend backs
should be placed 1 or 2 mm distal to molarshould be placed 1 or 2 mm distal to molar
tubes.tubes.

A/P ANCHORAGE SUPPORT ANDA/P ANCHORAGE SUPPORT AND
CONTROL FOR UPPER MOLARSCONTROL FOR UPPER MOLARS
- THE USE OF HEADGEAR :- THE USE OF HEADGEAR :
 In certain cases, it may be necessary for theIn certain cases, it may be necessary for the
upper posterior segments to be limited in theirupper posterior segments to be limited in their
mesial movement, maintained in their positions,mesial movement, maintained in their positions,
or even distalized, to allow the anterioror even distalized, to allow the anterior
segments to be properly positioned in the face.segments to be properly positioned in the face.

Posterior anchorage control requirementsPosterior anchorage control requirements
are normally greater in the upper arch thanare normally greater in the upper arch than
in the lower arch owing to five main factors :in the lower arch owing to five main factors :
 The upper molars move mesially more easily thanThe upper molars move mesially more easily than
the lower molars.the lower molars.
 The upper anterior segment has larger teeth thanThe upper anterior segment has larger teeth than
the lower anterior segmentthe lower anterior segment
 The upper anterior brackets have more tip builtThe upper anterior brackets have more tip built
into them than the lower anterior brackets.into them than the lower anterior brackets.

 The upper incisors require more torque controlThe upper incisors require more torque control
and bodily movement than the lower incisors,and bodily movement than the lower incisors,
which only require distal tipping or uprighting.which only require distal tipping or uprighting.
 In many practices, a typical caseload has moreIn many practices, a typical caseload has more
Class II type of malocclusions than Class III typeClass II type of malocclusions than Class III type

A/P ANCHORAGE SUPPORT ANDA/P ANCHORAGE SUPPORT AND
CONTROL FOR UPPER MOLARSCONTROL FOR UPPER MOLARS
- THE PALATAL BAR :- THE PALATAL BAR :
 A second method of anchorage support in theA second method of anchorage support in the
upper posterior segment is the palatal bar.upper posterior segment is the palatal bar.
 Can also be used to rotate the molars which areCan also be used to rotate the molars which are
rotated and to intrude the molars.rotated and to intrude the molars.

A/P ANCHORAGE SUPPORTA/P ANCHORAGE SUPPORT
AND CONTROL FOR UPPERAND CONTROL FOR UPPER
MOLARS - THE NANCEMOLARS - THE NANCE
HOLDING ARCH :HOLDING ARCH :

A/P ANCHORAGE CONTROLA/P ANCHORAGE CONTROL
OF LOWER MOLARS - THEOF LOWER MOLARS - THE
LINGUAL ARCHLINGUAL ARCH
 Lingual arches should also be considered forLingual arches should also be considered for
maximum anchorage premolar extraction cases.maximum anchorage premolar extraction cases.
This will include many bimaxillary proclinationThis will include many bimaxillary proclination
cases and also cases with severe lower anteriorcases and also cases with severe lower anterior
crowding.crowding. In both these types of problem, it isIn both these types of problem, it is
necessary to consider using a lingual archnecessary to consider using a lingual arch
throughout the early stages of leveling andthroughout the early stages of leveling and
aligning.aligning.

 This will restrict the mesial movement of lowerThis will restrict the mesial movement of lower
molars, and in the bimaxillary proclination cases,molars, and in the bimaxillary proclination cases,
it will ensure that most of the premolar extractionit will ensure that most of the premolar extraction
space is available at the end of leveling andspace is available at the end of leveling and
aligning, to provide for retraction of the anterioraligning, to provide for retraction of the anterior
segment. In the severely crowded cases, thesegment. In the severely crowded cases, the
lingual arch will ensure that most of the premolarlingual arch will ensure that most of the premolar
extraction space is used to relieve anteriorextraction space is used to relieve anterior
crowding.crowding.

Vertical Control of the IncisorsVertical Control of the Incisors
 The effect of bracket tip is more extreme in theThe effect of bracket tip is more extreme in the
upper arch, and care is needed if the caninesupper arch, and care is needed if the canines
are distally tipped in the starting malocclusion.are distally tipped in the starting malocclusion.
In such cases, as the arch wire passes throughIn such cases, as the arch wire passes through
the canine bracket slot it will lay incisally to thethe canine bracket slot it will lay incisally to the
incisor bracket slots.incisor bracket slots. If the wire is fully engagedIf the wire is fully engaged
into the incisors, it will tend to cause extrusion ofinto the incisors, it will tend to cause extrusion of
these teeth, which is undesirable in most cases.these teeth, which is undesirable in most cases.

 This effect can be avoided either by notThis effect can be avoided either by not
bracketing the incisors at the start of treatment,bracketing the incisors at the start of treatment,
or by not tying the arch wire into the incisoror by not tying the arch wire into the incisor
bracket slots, but allowing it to lay incisally to thebracket slots, but allowing it to lay incisally to the
brackets until the canine roots have beenbrackets until the canine roots have been
uprighted and moved distally, under the controluprighted and moved distally, under the control
of the lace backs. The incisors can then beof the lace backs. The incisors can then be
engaged without causing unwanted extrusion.engaged without causing unwanted extrusion.

Vertical Control of Canines :Vertical Control of Canines :
 It is important to avoid early arch wireIt is important to avoid early arch wire
engagement of high labial canines, so thatengagement of high labial canines, so that
unwanted vertical movement of lateral incisorsunwanted vertical movement of lateral incisors
and premolars does not occur.and premolars does not occur.

Vertical Control of Molars in HighVertical Control of Molars in High
Angle Cases :Angle Cases :
When treating high angle cases, theWhen treating high angle cases, the
following methods of vertical molar controlfollowing methods of vertical molar control
should be considered :should be considered :
 Upper second molars are generally not initiallyUpper second molars are generally not initially
banded or bracketed, to minimize extrusion ofbanded or bracketed, to minimize extrusion of
these teeth. If they require banding, an archthese teeth. If they require banding, an arch
wire step can be placed behind the first molar towire step can be placed behind the first molar to
avoid extrusion.avoid extrusion.

 If the upper first molars require expansion, anIf the upper first molars require expansion, an
attempt is made to achieve bodily movementattempt is made to achieve bodily movement
rather than tipping, to avoid extrusion of therather than tipping, to avoid extrusion of the
palatal cusps. This is best accomplished with apalatal cusps. This is best accomplished with a
fixed expander.fixed expander.
 If palatal bars are used, they are designed to lieIf palatal bars are used, they are designed to lie
away from the palate by approximately 2 mm soaway from the palate by approximately 2 mm so
that the tongue can exert a vertical intrusivethat the tongue can exert a vertical intrusive
effect.effect.

 When headgears are used in high angel cases,When headgears are used in high angel cases,
either a combination pull or a high pull headgeareither a combination pull or a high pull headgear
is used. The cervical pull headgear is avoided.is used. The cervical pull headgear is avoided.
 In some cases, an upper or lower posteriorIn some cases, an upper or lower posterior
biteplate in the molar region is helpful tobiteplate in the molar region is helpful to
minimize extrusion of molars.minimize extrusion of molars.

SPECIAL PROBLEMS INSPECIAL PROBLEMS IN
ALIGNMENTALIGNMENT

Crossbite Correction :Crossbite Correction :
 For both posterior and anterior crossbite, it isFor both posterior and anterior crossbite, it is
obviously important to make the appropriateobviously important to make the appropriate
distinctions between skeletal and dentaldistinctions between skeletal and dental
problems, and to quantitative the severity of theproblems, and to quantitative the severity of the
problem.problem.

Individual Teeth Displaced intoIndividual Teeth Displaced into
Anterior CrossbiteAnterior Crossbite
 Anterior crossbite of one or two teeth almostAnterior crossbite of one or two teeth almost
always is an expression of severe crowding, andalways is an expression of severe crowding, and
is most likely to occur when maxillary lateralis most likely to occur when maxillary lateral
incisors that were somewhat lingually positionedincisors that were somewhat lingually positioned
to begin with, are forced even more lingually byto begin with, are forced even more lingually by
lack of space.lack of space. Correction of the crossbiteCorrection of the crossbite
requires first opening enough space for therequires first opening enough space for the
displaced teeth, then bringing them into properdisplaced teeth, then bringing them into proper
position in the archposition in the arch

 It may be necessary to use a bite plateIt may be necessary to use a bite plate
temporarily to separate the posterior teeth andtemporarily to separate the posterior teeth and
create the vertical space needed to allow thecreate the vertical space needed to allow the
teeth to move. The older the patient, the moreteeth to move. The older the patient, the more
likely it is that a bite plate will be needed. Duringlikely it is that a bite plate will be needed. During
rapid growth in early adolescence, often incisorsrapid growth in early adolescence, often incisors
that were locked in anterior crossbite can bethat were locked in anterior crossbite can be
corrected without a bite plate.corrected without a bite plate.

Transverse Maxillary Expansion byTransverse Maxillary Expansion by
Opening the Midpalatal Suture :Opening the Midpalatal Suture :
 It is relatively easy to widen the maxilla byIt is relatively easy to widen the maxilla by
opening the midpalatal suture before and duringopening the midpalatal suture before and during
adolescence, but this becomes progressivelyadolescence, but this becomes progressively
more difficult as patients become older.more difficult as patients become older.

 Patients who are candidates for opening the midPatients who are candidates for opening the mid
palatal suture may have such severe crowdingpalatal suture may have such severe crowding
that even with this arch expansion, premolarthat even with this arch expansion, premolar
extraction will be required. In these patients,extraction will be required. In these patients,
however, separation of the suture should be thehowever, separation of the suture should be the
first step in treatment, before either extraction orfirst step in treatment, before either extraction or
alignment. The first premolar teeth are useful asalignment. The first premolar teeth are useful as
anchorage for the lateral expansion and cananchorage for the lateral expansion and can
serve for that purpose even if they are to beserve for that purpose even if they are to be
extracted later, and the additional spaceextracted later, and the additional space
provided by the lateral expansion facilitatesprovided by the lateral expansion facilitates
alignment.alignment.

 Opening the midpalatal suture should be usedOpening the midpalatal suture should be used
primarily as a means of correcting a skeletalprimarily as a means of correcting a skeletal
crossbite, making a narrow maxilla normal, not acrossbite, making a narrow maxilla normal, not a
normal maxilla abnormally wide.normal maxilla abnormally wide.

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