3. orthodontic appliances

8/7/2019 3. Orthodontic appliances

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Orthodontics 538Orthodontics 538

Monica Schneider, DDS, MSMonica Schneider, DDS, MS


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ClinicalComponentClinicalComponent

6 clinic points are required for completion of the clinic portion of the course6 clinic points are required for completion of the clinic portion of the course

-- Ortho Assist (2)Ortho Assist (2)

You must attend 2 postgraduateYou must attend 2 postgraduate orthoortho clinic sessions. Signclinic sessions. Sign--up is necessary; youup is necessary; you

will have to check in the postwill have to check in the post--gradgrad orthoortho clinic on the 3clinic on the 3rdrd floor at 8:50am for thefloor at 8:50am for the

morning session and 12:50pm for the afternoon session with Mrs. Amymorning session and 12:50pm for the afternoon session with Mrs. Amy RevtyRevty(Head orthodontic assistant) so she can assign you to one of the residents.(Head orthodontic assistant) so she can assign you to one of the residents.

We will take a maximum of 5 students on each clinic session.We will take a maximum of 5 students on each clinic session. Assist and get asAssist and get as

much as you can from the experience.much as you can from the experience. You will get 1 point for assist, so be sure toYou will get 1 point for assist, so be sure to

get swiped intoget swiped into AxiumAxium..

-- Consults (4)Consults (4)

Ortho instructors orOrtho instructors or postgradspostgrads will be available for consults each clinic period. Getwill be available for consults each clinic period. Get

as many consults as possible for anyas many consults as possible for any orthoortho question you might have relevant toquestion you might have relevant to

the patient, child or adult. Each consult =1 point. The consults are done in thethe patient, child or adult. Each consult =1 point. The consults are done in the

orthodontic clinic 3orthodontic clinic 3rdrd floor, if you have a patient for a consult talk to one of thefloor, if you have a patient for a consult talk to one of the

assistants so you can get a chair assigned.assistants so you can get a chair assigned.


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Ortho CompetencyOrtho Competency

-- Ortho CompetencyOrtho Competency

Students are required to perform a supervisedStudents are required to perform a supervised

orthodontic examination (following theorthodontic examination (following theorthodontic blue form which is in theorthodontic blue form which is in the

orthodontic clinic) to an instructor. This is aorthodontic clinic) to an instructor. This is a

good opportunity to learn one on one withgood opportunity to learn one on one with

your instructor. No points are given, this is ayour instructor. No points are given, this is a

requirement.requirement.


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Bonus PointsBonus Points

Orthodontic Clinical Credits:Orthodontic Clinical Credits: One of the requirements to passOne of the requirements to pass

this course is that the student must accumulate in the clinic atthis course is that the student must accumulate in the clinic at

least six orthodontic clinical credits by the end of theleast six orthodontic clinical credits by the end of the

academic year (orthodontic assists and consults)academic year (orthodontic assists and consults)

If the student has more than 6 orthodontic clinical credits, heIf the student has more than 6 orthodontic clinical credits, he

(she) may earn bonus point(s) as follows:(she) may earn bonus point(s) as follows:

77--8 orthodontic clinical credits:8 orthodontic clinical credits: 1 bonus point1 bonus point

9 or more orthodontic clinical credits9 or more orthodontic clinical credits 2 bonus points2 bonus points


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Typical steps in treatmentTypical steps in treatment

Level andLevel and derotatederotate the archesthe arches

Intrude upper and lower anterior teethIntrude upper and lower anterior teeth

Correct AP relationshipCorrect AP relationship Close spaces if neededClose spaces if needed

Finish and retentionFinish and retention


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Type of applianceType of appliance Standard edgewise vs.Standard edgewise vs. PreadjustedPreadjusted applianceappliance

Ligating wings

Bracket slot

Bracket base

Bracket slots have NO angulation or inclination Bracket slots have angulation or inclination

Left quadrant

upper

lower

Left quadrant


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Type of applianceType of appliance Standard edgewise vs.Standard edgewise vs. PreadjustedPreadjusted applianceappliance

Ligating wingsBracket slotBracket base

and mesh for

bonding

Bracket slots have NO angulation or inclination Bracket slots have angulation or inclination

Left quadrant

upper

lower

Left quadrant

Bracket base

and mesh for

bonding

Base of the slot

The standard brackets the height (profile) of the brackets is the same from the base of the bracket to the base of

the slot , in the preadjusted appliance the height varies to compensate different tooth thicknesses (i.e. comparethe diagrams for upper centrals and laterals in both prescriptions)


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The chart shows a wide variety of systems with the preadjusted appliance notice the variationin torque and angulation comparing different teeth and different prescriptions

Commonly

used systems


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Edgewise applianceEdgewise appliance

The edge wise appliance allows movement ofThe edge wise appliance allows movement of

teeth in three planes of space with a singleteeth in three planes of space with a single

archwirearchwire [[bcbc slot is rectangular]slot is rectangular]

Meaning of edgewiseMeaning of edgewise

Edgewise slot received a rectangular wireEdgewise slot received a rectangular wire

.022x.028 inserted into the bracket in the.022x.028 inserted into the bracket in the

narrowest positionnarrowest position

.022 slot measurement


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Slot sizesSlot sizes .022 slot.022 slot

oror

.018 slot.018 slot

In the past because gold wire was used the slot had to beIn the past because gold wire was used the slot had to be

largerlarger

Stainless steel wires were used later and were not as flexibleStainless steel wires were used later and were not as flexibleand the .018 slot became more common. A smaller size wireand the .018 slot became more common. A smaller size wire

was used to fill up the slot (easier to bend)was used to fill up the slot (easier to bend)

Today practitioners use:Today practitioners use:

.018.018 50%50% .022.022 50%50%

Slot size is less important todaySlot size is less important today

Memory wires and more flexible wires (Memory wires and more flexible wires (NiTiNiTi, TMA), TMA) -- makes them easiermakes them easier

to insert and bendto insert and bend

Can use bigger size wire but does not have to be a very stiff wireCan use bigger size wire but does not have to be a very stiff wire


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Design ofBracketsDesign ofBrackets

Shape of the BracketShape of the Bracket SingleSingle

One set ofOne set of ligatingligating wingswings

TwinTwin

Two sets ofTwo sets of ligatingligating wingswings


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Type ofBracketType ofBracket

Standard EdgewiseStandard Edgewise 0 torque0 torque

00 angulationangulation

PreadjustedPreadjusted Appliance (Appliance (StraightwireStraightwire))

Changes in torque andChanges in torque and angulationangulation

Brackets are marked on the distal gingival corner different

Colors for each quadrant (some companies have different color for each tooth)


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Larry AndrewsLarry Andrews

Graduated Ohio State 1958.Graduated Ohio State 1958.

19601960--64 collected 120 non64 collected 120 non--orthodonticorthodontic

normalsnormals..

Using this sample he formulated the SIXUsing this sample he formulated the SIX

KEYS TO OCCLUSION that theseKEYS TO OCCLUSION that these normalsnormals

supposedly contained.supposedly contained.

He later found that theseHe later found that these six keyssix keys werewere

often missing in ABO board cases.often missing in ABO board cases.


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Six Keys of OcclusionSix Keys of OcclusionDr. Lawrence F. AndrewsDr. Lawrence F. Andrews Molar relationshipMolar relationship

The distal marginal ridge ofThe distal marginal ridge ofthe maxillary first molarthe maxillary first molar

contacts thecontacts the mesialmesial marginalmarginal

ridge of theridge of the mandibularmandibular

second molar.second molar.

CrownCrown AngulationAngulation (Tip)(Tip)

Crown Inclination (Torque)Crown Inclination (Torque)

RotationsRotations

SpacesSpaces

Curve ofCurve of SpeeSpee


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Preadjusted Appliance (Straightwire)Preadjusted Appliance (Straightwire)

CrownCrown AngulationAngulation (Tip)(Tip) TheThe mesiodistalmesiodistal orientation of the clinical crown of the toothorientation of the clinical crown of the tooth

The gingival portion of the long axes of all crowns is more distal thanThe gingival portion of the long axes of all crowns is more distal than

thethe incisalincisal portionportion

mesialdistal


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Inclination (Torque)Inclination (Torque)

TheThe buccolingualbuccolingual

orientation of the clinicalorientation of the clinical

crown of the toothcrown of the tooth Centrals and lateralsCentrals and laterals

All crownsAll crowns labiallylabially

inclinedinclined

TheThe incisalincisal portion of theportion of the

maxillary incisors is labialmaxillary incisors is labialto the gingival portionto the gingival portion


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PreadjustedPreadjusted Appliance (Appliance (StraightwireStraightwire))

Inclination (Torque)Inclination (Torque) Upper canines throughUpper canines through

molarsmolars

All crownsAll crowns linguallylingually

inclinedinclined

The gingival portion isThe gingival portion is

more labial than themore labial than the

occlusalocclusal portion of theportion of the

crown.crown.


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Lower incisorsLower incisors

UprightUpright


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Lower canines throughLower canines through

molarsmolars

All crowns areAll crowns are linguallylinguallyinclinedinclined


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InIn-- OutOut

Takes into account the differing faciolingualTakes into account the differing faciolingual

thicknesses of the upper and lower teeththicknesses of the upper and lower teeth

Preadjusted bracket has increasedthickness in the premolar area

Standard bracket the same

Thickness in all brackets


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RotationRotation

Eliminates the necessity of putting bendsEliminates the necessity of putting bends mesialmesial to theto the

first molarsfirst molars

buildbuild--in offsetin offset

Off set bends need to be

placed to compensate the

rotation of molar and size ofsecond premolar

Off sets are build in the

brackets and tubes


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Other DesignsOther Designs SelfSelf ligatingligating bracketsbrackets

Smart Clip Bracket

Disengagement Instrument for smart clip

Insertion Instrument for smart clip

Damon 3 Bracket

Clip system

holds the

wire in the

slot

Doors hold the wire in the slot


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Other DesignsOther Designs

Lingual bracketsLingual brackets


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Bracket MaterialsBracket Materials

Stainless steelStainless steel

Plastic/acrylicPlastic/acrylic

GoldGold

CeramicCeramic

MonocrystallineMonocrystalline

sapphiresapphire


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InvisalignInvisalign Series of aligners usedSeries of aligners used

PolysiloxanePolysiloxane impressionimpression

Three dimensional imagingThree dimensional imaging

ScanningScanning

SterolitographySterolitography (models made(models made

and trays made from a seriesand trays made from a series

of models)of models)


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Archwire selectionArchwire selection

The pressure of the wire in the bracket slotThe pressure of the wire in the bracket slotgenerates the force that moves the teeth in allgenerates the force that moves the teeth in all

three dimensionsthree dimensions

Elastic behavior determined by stressElastic behavior determined by stress--strainstrain

responseresponse Internal stateInternal state

Basic Properties ofElastic MaterialsBasic Properties ofElastic Materials


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StressStress

Internal distribution of a loadInternal distribution of a load

Force applied to a mechanical structureForce applied to a mechanical structure

Equal and opposite to the applied load over unitEqual and opposite to the applied load over unit

areaarea

Stress =Stress = ForceForce

AreaArea


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Change in dimension of a material due to aChange in dimension of a material due to a

external force or loadexternal force or load

Measured by a change in lengthMeasured by a change in length

Strain = e/ LStrain = e/ L

e = change in lengthe = change in length

L = original lengthL = original length

StrainStrain


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Stress strain curveStress strain curve Measures the load and deformation and calculatesMeasures the load and deformation and calculates

the corresponding strain and stressthe corresponding strain and stress

ElasticElastic

RangeRange

PlasticPlastic

RangeRange

StrainStrain

StressStress E.L.E.L.ult.ult.


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Characteristics ofImportance inCharacteristics ofImportance in

Orthodontic wiresOrthodontic wires StiffnessStiffness

Resistance to deformationResistance to deformation

Opposite to springinessOpposite to springiness

StrengthStrength

Maximum possible loadMaximum possible load

Working rangeWorking range

How far the wire can beHow far the wire can be deflected without beingdeflected without being

deformeddeformed


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Orthodontic wiresOrthodontic wires

FormabilityFormability

Biocompatibility and environmentalBiocompatibility and environmental

stabilitystability

JoinabilityJoinability want to be able to solderwant to be able to solder

FrictionFriction


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Load deflection rateLoad deflection rate

External measurementsExternal measurements

Force produced by unit of activationForce produced by unit of activation

Is the force magnitude delivered by anIs the force magnitude delivered by an

appliance and is proportional to theappliance and is proportional to the

modulus of elasticity (E)modulus of elasticity (E)


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Mechanical properties of metalsMechanical properties of metals

Load deflection curveLoad deflection curve

ElasticElastic

RangeRange

PlasticPlastic

RangeRange

P maxP max

P ult.P ult.LoadLoad

DeflectionDeflection


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ProportionalLimitProportionalLimit

Maximum stress at which stress isMaximum stress at which stress is

proportional to strainproportional to strain

Elastic region : before proportional limitElastic region : before proportional limit

Plastic region : after proportional limitPlastic region : after proportional limit


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Yield pointYield point

Point at which deformation of 0.1% isPoint at which deformation of 0.1% is

measuredmeasured

There is a rapid increase in strain w/o aThere is a rapid increase in strain w/o acorresponding increase in stresscorresponding increase in stress

The stress at which a material begins toThe stress at which a material begins to

function in a plastic mannerfunction in a plastic manner


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StressStress--strain curvestrain curve

Load

Deflection

The curve measures load /mm of deflection the stiffer the wire the less deflection = steeper curve


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Resilience and ToughnessResilience and Toughness

ResilienceResilience::

MaximunMaximun amount of energy a material canamount of energy a material can

absorb without undergoing permanentabsorb without undergoing permanent

deformationdeformation

Toughness:Toughness:

Ability to absorb energy without fractureAbility to absorb energy without fracture


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Resilience and ToughnessResilience and Toughness


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Orthodontic wiresOrthodontic wires

StiffnessStiffness

Resistance to deformationResistance to deformation StrengthStrength

Maximum possible loadMaximum possible load

Working rangeWorking range How far the wire can be deformedHow far the wire can be deformed


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Wire cross sectionWire cross section


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Round wireRound wire

RangeRange

Range :Range :

ddDD 2d = 1/22d = 1/2


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StrengthStrength

Strength :Strength :

cubic functioncubic function

of theratioof theratio

ddDD 2d = 82d = 8


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StiffnessStiffness

Stiffness :Stiffness :

ddDD 2d = 162d = 16


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StrengthStrength ddDD

2d2d 88

SpringinessSpringiness dd DD 2d2d 1/161/16

RangeRange dd DD 2d2d 1/21/2


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Length of the WireLength of the Wire

Range is proportional to the square of theRange is proportional to the square of the

lengthlength

BeamB = 4 Beam ABeamB = 4 Beam A

AB


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Stiffness is inversely proportional to the cubeStiffness is inversely proportional to the cube

of the lengthof the length

Stiffness A = 1Stiffness A = 1

StiffnessB = 1/8StiffnessB = 1/8


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Strength is inversely proportional to theStrength is inversely proportional to the

lengthlength

Strength A = 4Strength A = 4

StrengthB = 2StrengthB = 2

BA


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StrengthStrength LLDD

2L2LDD

1/41/4

SpringinessSpringiness LL DD 11 2L2L DD 88

RangeRange LL DD 11 2L2L DD 44


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Optimal cross sectionOptimal cross section

Circular cross sectionCircular cross section

Multidirectional activationsMultidirectional activations Has to be properly orientedHas to be properly oriented

May rotate in the bracketMay rotate in the bracket


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Optimal cross sectionOptimal cross section

Flat cross sectionFlat cross section

Unidirectional activationsUnidirectional activations

Can deliver lower loadCan deliver lower load--deflection rates withoutdeflection rates without

permanent deformationpermanent deformation

Can be anchored into a tube or a bracketCan be anchored into a tube or a bracket


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Archwire MaterialArchwire Material

Stainless SteelStainless Steel

Entered dentistry in 1919Entered dentistry in 1919

Softened by annealingSoftened by annealing

Some bandsSome bands Ligature wiresLigature wires

Hardened by cold workingHardened by cold working

Super grades steels more brittleSuper grades steels more brittle

Regular grade can be bent without breakingRegular grade can be bent without breaking


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JoinabilityJoinability is possible (soldering)is possible (soldering)

Fused together by weldingFused together by welding

Corrosion resistanceCorrosion resistance Lower frictionLower friction


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Stainless SteelStainless Steel SizesSizes

Round (.014, .016, .018)Round (.014, .016, .018)

Square (.016 x .016)Square (.016 x .016)

Rectangular (.016 x .022, .017 x .025, .018 x .025, .021 xRectangular (.016 x .022, .017 x .025, .018 x .025, .021 x

.025).025)


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MultistrandedMultistranded wireswires

Specific number of thin wire sections coiled aroundSpecific number of thin wire sections coiled around

each othereach other

Round or rectangular cross sectionRound or rectangular cross section Stiffness of a triple stranded 0.0175 similar to a 0.010Stiffness of a triple stranded 0.0175 similar to a 0.010

stainless steel single strandedstainless steel single stranded

MultistrandedMultistranded 25% stronger than the 0.010 stainless25% stronger than the 0.010 stainless

steel wiresteel wire


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ArchwireArchwire MaterialMaterial

Cobalt chromium wiresCobalt chromium wires

ElgiloyElgiloy,, AzuraloyAzuraloy

Supplied in a softer stateSupplied in a softer state

Hardened by heat treatmentHardened by heat treatment After heat treatment becomes equivalent toAfter heat treatment becomes equivalent to

regular stainless steelregular stainless steel

Good formabilityGood formability

Larger frictional forcesLarger frictional forces


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Beta Titanium (TMA)Beta Titanium (TMA) Introduced in the early 1980sIntroduced in the early 1980s

Commercially available as TMACommercially available as TMA

Titanium molybdenum alloyTitanium molybdenum alloy Strength and springinessStrength and springiness

Simplify appliance designSimplify appliance design

Good formabilityGood formability

Attach hooks by weldingAttach hooks by welding

Higher levels of friction than Stainless steelHigher levels of friction than Stainless steel


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Archwire MaterialArchwire Material Nickel Titanium AlloyNickel Titanium Alloy

NitinolNitinol

SuperelasticSuperelastic NiTiNiTi NiNi--Ti, CuTi, Cu NiTiNiTi,, NitinolNitinol--SESE

Cannot be soldered or weldedCannot be soldered or welded

Cannot be easily formed or bentCannot be easily formed or bent

Forces are maintained over a large range of deflectionForces are maintained over a large range of deflection

Large deflection ,low force wires

with memory


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1

4

3

2

Characteristics of a ForceCharacteristics of a Force

Line of actionLine of action

SenseSense

MagnitudeMagnitude

Point ofPoint of

applicationapplication


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Center of RotationCenter of Rotation

DefinitionDefinition

The point about which aThe point about which a

bodybody rotatesrotates


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Center of RotationCenter of Rotation

TYPE OF MOVEMENTTYPE OF MOVEMENT CENTER OFCENTER OFROTATIONROTATION

TranslationTranslation InfinityInfinity

Uncontrolled tippingUncontrolled tipping Slightly apical to theSlightly apical to thecenter of resistancecenter of resistance

Controlled tippingControlled tipping ApexApex

Root movementRoot movement Incisal (occlusal)Incisal (occlusal)edgeedge


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MomentMoment

DefinitionDefinition Magnitude of the force multiplied by theMagnitude of the force multiplied by the

perpendicular distance of the line ofperpendicular distance of the line of

action of the force to the center ofaction of the force to the center of

resistanceresistance

20 mm20 mm

50 gm50 gm

M = F x dM = F x d


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CoupleCouple

Two forces of equal magnitudeTwo forces of equal magnitude

Parallel noncolinear lines of actionParallel noncolinear lines of action

Opposite sensesOpposite senses

20 mm20 mm

20 mm20 mm


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Determining the EquivalentDetermining the Equivalent

Force SystemForce System

Distance from the

bracket to Cr = 9.8 mm

Determine the force system at the bracket

Determine the equivalent force system at the Cres


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Wire SequenceWire Sequence

.022 slot.022 slot

1.1. .0175 respond.0175 respond MultistrandedMultistranded SS orSS or

2.2. .014.014 NiTiNiTi

3.3. .016.016 NiTiNiTi

4.4. .016 x .022.016 x .022 NiTiNiTi or TMAor TMA

5.5. .016 x .022 SS.016 x .022 SS

6.6. .017 x .025 SS.017 x .025 SS

7.7. .018 x .025 SS or higher.018 x .025 SS or higher


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Steps in TreatmentSteps in Treatment

Align and level the archesAlign and level the arches


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Align and level the archesAlign and level the arches


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Correct verticalCorrect vertical

relationshiprelationship

Intrude anterior teethIntrude anterior teeth

Intrusion archesIntrusion arches

Reverse curve wiresReverse curve wires


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Correct vertical relationshipCorrect vertical relationship

Intrude anterior teethIntrude anterior teeth

Sequence of wiresSequence of wires

Step up or down (making bends)Step up or down (making bends) Reverse curve wiresReverse curve wires

Intrusion archesIntrusion arches


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CorrectCorrect AnteroposteriorAnteroposterior relationshiprelationship

Class IIClass II

DistalizeDistalize the upper molarsthe upper molars

Moving lower teethMoving lower teeth anteriorlyanteriorly

Upper molar distalized

with pendulum

appliance

Note space opened

Molar

Class I

ii


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Correct Anteroposterior relationshipCorrect Anteroposterior relationship Class IIClass II

Distalize the upper molarsDistalize the upper molars

Moving lower teeth anteriorlyMoving lower teeth anteriorly

S iS i


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CorrectCorrect AnteroposteriorAnteroposterior relationshiprelationship Class IIClass II

ExtraoralExtraoral TractionTraction

External force to maxillary dentitionExternal force to maxillary dentition

Facebow

Insert in upper molar tubesAttach to strap

P i f i i f h FP i f i i f h F


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Point of origin of the ForcePoint of origin of the Force

Depends upon theDepends upon the

assembly usedassembly used

CervicalCervical neckneck

OccipitalOccipital Back of headBack of head

ParietalParietal Upper part ofUpper part of

the headthe head

Direction of the distalization force


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H d Cl ifi tiH d Cl ifi ti


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Headgear ClassificationHeadgear Classification

Cervical HeadgearCervical Headgear

High Pull HeadgearHigh Pull Headgear

Combination HeadgearCombination HeadgearStraight pullStraight pull

I t l El tiI t l El ti


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IntraoralElasticsIntraoralElastics

IntramaxillaryIntramaxillary Class IClass I

Same archSame arch

IntermaxillaryIntermaxillary Class II elasticsClass II elastics

Upper and lower archesUpper and lower arches

Use with heavyUse with heavy archwiresarchwires

Use as much as possibleUse as much as possible

Evaluate side effectsEvaluate side effects


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IntermaxillaryIntermaxillary Vertical ElasticsVertical Elastics

To get betterTo get better interdigitationinterdigitation

Close the bite if is a mild open biteClose the bite if is a mild open bite



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IntermaxillaryIntermaxillary

Cross elasticsCross elastics

Can be used to correct midline deviationsCan be used to correct midline deviations

C il S iC il S i


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CoilSpringsCoilSprings

Open coils (open space)Open coils (open space) Closed coils (close space or maintain space)Closed coils (close space or maintain space)

Openingspace for an impacted tooth

With an open coilHolding the space that was opened while

The tooth comes down to the arch

St i T t tSt i T t t


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Close spacesClose spaces

Closing loopsClosing loops

Elastomeric chainsElastomeric chains

To activate the loop is pulled apart and the wire is bent distal to the molar (cinched back) toprevent the wire from sliding forward and to maintain the force needed for space closure

Elastomeric ChainsElastomeric Chains


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Elastomeric ChainsElastomeric Chains



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Finish and retentionFinish and retention

Finishing wires usually heavy SS or TMAFinishing wires usually heavy SS or TMA

Choose retainerChoose retainer

Standard HawleyStandard Hawley

EssixEssix retainerretainer

3. orthodontic appliances

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