Fixed appliance anchorage

Anchorage inAnchorage in
OrthodonticsOrthodontics
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Anchorage in Fixed Appliances:Anchorage in Fixed Appliances:
 Edgewise Appliance:Edgewise Appliance:
Tweed Technique:Tweed Technique:
“ When teeth are tipped distally as they are in
anchorage preparation, osteoid tissue appears
to be laid down adjacent to the mesial surface
of the tooth being moved distally.”
- Kaare Reitan

 Anchorage Preparation:Anchorage Preparation:
First Degree:First Degree:
 ANB 0ANB 0º- 4º, facial esthetics are goodº- 4º, facial esthetics are good
 Mandibular terminal molars must be uprightedMandibular terminal molars must be uprighted
and maintained in a position to prevent theirand maintained in a position to prevent their
being elongatedbeing elongated
 Direction of intermaxillary elastic pull shouldDirection of intermaxillary elastic pull should
not exceed 90ºnot exceed 90º

 Anchorage Preparation:Anchorage Preparation:
Second Degree:Second Degree:
 ANB exceeds 4.5ANB exceeds 4.5
 Mandibular second molars should always beMandibular second molars should always be
bandedbanded
 Must be tipped distally so that their distalMust be tipped distally so that their distal
marginal ridges are at gum levelmarginal ridges are at gum level
 Direction of pull of intermaxillary elasticsDirection of pull of intermaxillary elastics
should always beshould always be > 90º> 90º

 Third Degree or Total Anchorage Preparation:Third Degree or Total Anchorage Preparation:
 ANB does not exceed 5ANB does not exceed 5ºº
 Jigs are necessary for total anchorage preparationJigs are necessary for total anchorage preparation
 All posterior teeth (second premolar to terminalAll posterior teeth (second premolar to terminal
molars) are tipped distallymolars) are tipped distally
 Distal marginal ridges of terminal molars are belowDistal marginal ridges of terminal molars are below
gum levelgum level
 In difficult cases, anchorage prepared in bothIn difficult cases, anchorage prepared in both
maxillary and mandibular archesmaxillary and mandibular arches

 Space Closure:Space Closure:
Class III elasticsClass III elastics
 Lower:Lower:
Head gear (upper molars)Head gear (upper molars)
Class II elasticsClass II elastics
 Upper:Upper:
Head gear (lower molars)Head gear (lower molars)

Tweed-Merrifield Technique:Tweed-Merrifield Technique:
 Allows mandibular anchorage to be preparedAllows mandibular anchorage to be prepared
quickly by tipping 2 teeth at a time to theirquickly by tipping 2 teeth at a time to their
anchorage prepared position by using 10 teethanchorage prepared position by using 10 teeth
as “anchorage units” to tip two teethas “anchorage units” to tip two teeth
 Hence referred to as theHence referred to as the Merrifield “10-2”Merrifield “10-2”
SystemSystem

 Separate canine retraction with high pull J-Separate canine retraction with high pull J-
hook headgears aided by power chainshook headgears aided by power chains

 Spaces closed withSpaces closed with
maxillary and mandibularmaxillary and mandibular
closing loop arch wiresclosing loop arch wires
 Vertical support toVertical support to
maxillary arch with J-hookmaxillary arch with J-hook
headgear; to mandibularheadgear; to mandibular
anterior teeth with anterioranterior teeth with anterior
vertical elasticsvertical elastics

 Sequential Mandibular AnchorageSequential Mandibular Anchorage
Preparation:Preparation:
 The archwire produces an active force on onlyThe archwire produces an active force on only
two teeth while remaining passive to the othertwo teeth while remaining passive to the other
teethteeth
 Remaining teeth act as stabilizing orRemaining teeth act as stabilizing or
anchorage unitsanchorage units
 Anchorage preparation supported by high pullAnchorage preparation supported by high pull
headgear worn distal to the mandibular centralheadgear worn distal to the mandibular central
incisorsincisors

 Initiated by tipping the second molar to a 15Initiated by tipping the second molar to a 15ºº
distal inclinationdistal inclination
 After space closure, arch is checked to ensureAfter space closure, arch is checked to ensure
a 15a 15º distal tip of second molars:º distal tip of second molars: ReadoutReadout
 A 10A 10º distal tip is placed mesial to first molarº distal tip is placed mesial to first molar
bracketsbrackets
 Compensating bend maintainsCompensating bend maintains 1515º of terminalº of terminal
molar tipmolar tip

 Final step: Place a 5ºFinal step: Place a 5º
distal tip 1mm mesialdistal tip 1mm mesial
to second premolarto second premolar
bracketsbrackets
 In the maxillary arch,In the maxillary arch,
an effective 5º distalan effective 5º distal
tip on the secondtip on the second
molar is placed in themolar is placed in the
arch wirearch wire

Anchorage Considerations in BeggAnchorage Considerations in Begg
and Tip-Edge Techniques:and Tip-Edge Techniques:
 Begg Technique:Begg Technique:
Very efficient in anchorage conservation in theVery efficient in anchorage conservation in the
sagittalsagittal direction.direction.
Stationary AnchorageStationary Anchorage
Anchorage Control in Stage I:Anchorage Control in Stage I:
Sagittal anchorage:Sagittal anchorage:
 Upper Molar Anchorage:Upper Molar Anchorage:
1.1. Upper Class I elastics not usedUpper Class I elastics not used

2. TPA , when using power arms and palatal2. TPA , when using power arms and palatal
elastics ( also consolidating the first andelastics ( also consolidating the first and
second molars)second molars)

 Lower Molar Anchorage:Lower Molar Anchorage:
1.1. Stiff lower wire ( 0.018” P or P+)Stiff lower wire ( 0.018” P or P+)
2.2. Light (yellow) or ultra light (‘Road Runner’)Light (yellow) or ultra light (‘Road Runner’)
elastics. Heavier elastics tax anchorage andelastics. Heavier elastics tax anchorage and
hinder bite openinghinder bite opening
3.3. Molar stops when Class II and lower Class IMolar stops when Class II and lower Class I
elastics are usedelastics are used
4.4. Lip bumper/lingual arch in critical anchorageLip bumper/lingual arch in critical anchorage
casescases

 Causes of anchorage loss in sagittal directionCauses of anchorage loss in sagittal direction
during Stage I:during Stage I:
1.1. Insufficient resistance from anchor bendsInsufficient resistance from anchor bends
2.2. Excessively heavy elastic pullExcessively heavy elastic pull
3.3. Increased resistance from anterior teeth:Increased resistance from anterior teeth:
- incisor and/ or canine roots touching labial- incisor and/ or canine roots touching labial
cortical platecortical plate
- abnormal tongue or lip function- abnormal tongue or lip function
4.4. High mandibular plane angleHigh mandibular plane angle

 Vertical Anchorage:Vertical Anchorage:
1.1. Extrusion of molars due to anchor bendsExtrusion of molars due to anchor bends
2.2. Vertical component of Class II elasticsVertical component of Class II elastics

 Vertical Anchorage:Vertical Anchorage:
 Usually adequate in low angle casesUsually adequate in low angle cases
 In high angle cases should be reinforced with:In high angle cases should be reinforced with:
1.1. T.P.A.T.P.A.
2.2. High pull headgearHigh pull headgear
3.3. Posterior bite blocksPosterior bite blocks
4.4. Engagement of arch wire in first and secondEngagement of arch wire in first and second
molarsmolars

 Transverse Anchorage:Transverse Anchorage:
Anchor bends and Class II elastics causeAnchor bends and Class II elastics cause
lingual rolling of molarslingual rolling of molars
To prevent:To prevent:
1.1. Sufficiently stiff arch wiresSufficiently stiff arch wires
2.2. Expansion of the arch wiresExpansion of the arch wires
3.3. T.P.A., expanded headgear face bow, lipT.P.A., expanded headgear face bow, lip
bumperbumper

 Anchorage Control in Stage II:Anchorage Control in Stage II:
 Heavy arch wires (0.018” P or P+ or 0.020” P)Heavy arch wires (0.018” P or P+ or 0.020” P)
to maintain corrections. Also resist distobuccalto maintain corrections. Also resist distobuccal
rotational tendencyrotational tendency
 Since anchor bends are reduced, a MAA forSince anchor bends are reduced, a MAA for
lingual root torquelingual root torque
 0.010” uprighting springs on canines0.010” uprighting springs on canines

 Anchorage Control in Stage II:Anchorage Control in Stage II:
 Braking mechanics for protraction ofBraking mechanics for protraction of
posteriors:posteriors:
1.1. Braking springs or angulated T pins onBraking springs or angulated T pins on
canines and lateral incisorscanines and lateral incisors
2.2. Torquing component on incisors-Torquing component on incisors-
combination wires or torquing auxiliariescombination wires or torquing auxiliaries

 Anchorage Control in Pre-Stage III:Anchorage Control in Pre-Stage III:
 Upper wire: Gable bend for holding the deepUpper wire: Gable bend for holding the deep
bite correction and uprighting distally tippedbite correction and uprighting distally tipped
molarsmolars
 Lower wire: gable and anchor bendsLower wire: gable and anchor bends
 Inversion of segments to avoid canineInversion of segments to avoid canine
extrusionextrusion
 Ends of arch wires are bent backEnds of arch wires are bent back

Causes of anchorage loss in Stage III:Causes of anchorage loss in Stage III:
Torquing auxiliaries and uprighting springsTorquing auxiliaries and uprighting springs
cause reciprocal reactions in all three planes ofcause reciprocal reactions in all three planes of
space:space:
Lingual root torquing auxiliary and distal rootLingual root torquing auxiliary and distal root
uprighting spring:uprighting spring:
labial crown movements, extrusion of anteriorslabial crown movements, extrusion of anteriors
and intrusion of posteriors, buccal crownand intrusion of posteriors, buccal crown
movement of posteriorsmovement of posteriors

 Reciprocal mesial crown moving forcesReciprocal mesial crown moving forces
resisted by cinching and use of Class II elasticsresisted by cinching and use of Class II elastics
 When mesial drag on the lower arch is great-When mesial drag on the lower arch is great-
reverse (labial) root torquing auxiliaryreverse (labial) root torquing auxiliary

Control of Anchorage in Stage III:Control of Anchorage in Stage III:
 Minimise need for root movements by:Minimise need for root movements by:
- careful diagnosis and planning of extractions- careful diagnosis and planning of extractions
- controlled tipping of incisors- controlled tipping of incisors
- use of brakes- use of brakes
 Use of heavy base wires ( 0.020” P)Use of heavy base wires ( 0.020” P)
 Lighter auxiliaries and uprighting springsLighter auxiliaries and uprighting springs
 Light Class II elasticsLight Class II elastics

Control of Anchorage in Stage III:Control of Anchorage in Stage III:
 Reinforcement of Anchorage:Reinforcement of Anchorage:
In treatment of severe malocclusions,In treatment of severe malocclusions,
anchorage needs to be reinforced in Stage IIIanchorage needs to be reinforced in Stage III
1.1. Sagittal: Reverse root torquing auxiliary,Sagittal: Reverse root torquing auxiliary,
headgear or T.P.A., lip bumperheadgear or T.P.A., lip bumper
2.2. Vertical: High pull head gear, T.P.A. orVertical: High pull head gear, T.P.A. or
posterior bite blocksposterior bite blocks

3. Transverse:3. Transverse:
1.1. 0.020” P base wires with adequate0.020” P base wires with adequate
contraction and toe-in built into the wirescontraction and toe-in built into the wires
2.2. TPA or heavy overlay wiresTPA or heavy overlay wires
3.3. Extended mouse trap or molar torquingExtended mouse trap or molar torquing
auxiliary for buccal root torqueauxiliary for buccal root torque

 Arch Wires in Stage III:Arch Wires in Stage III:
 Cuspid circles tightly touching the cuspidCuspid circles tightly touching the cuspid
bracketsbrackets
 Posterior segments kept gingival in relation toPosterior segments kept gingival in relation to
anterior segmentsanterior segments
 Contraction in the upper arch wire: 2mm for 2-Contraction in the upper arch wire: 2mm for 2-
spur auxiliary made in 0.012” wirespur auxiliary made in 0.012” wire
 Molar segments of upper given a mild toe-in.Molar segments of upper given a mild toe-in.
Lower wire segments are in lineLower wire segments are in line

 Arch Wires in Stage III:Arch Wires in Stage III:
 Gable bend in the upper and gable and anchorGable bend in the upper and gable and anchor
bends in the lower arch wirebends in the lower arch wire
 Wire ends are annealed and tightly cinchedWire ends are annealed and tightly cinched

Begg vs. Conventional Edgewise:Begg vs. Conventional Edgewise:
 Begg EdgewiseBegg Edgewise
1.1. Stationary anchorageStationary anchorage Near reciprocal anchorageNear reciprocal anchorage
2.2. Round wires Rectangular full size wiresRound wires Rectangular full size wires
+Light elastics +Heavy forces+Light elastics +Heavy forces
3.3. Decreased friction Increased frictionDecreased friction Increased friction

Anchorage Control Using the Pre-Anchorage Control Using the Pre-
Adjusted ApplianceAdjusted Appliance
 Anchorage requirements differ because ofAnchorage requirements differ because of
built-in adjustments which start expressingbuilt-in adjustments which start expressing
right from the beginningright from the beginning
 Initial wires being flexible, not sufficientInitial wires being flexible, not sufficient
resistance in the various planesresistance in the various planes

 Specific approaches used:Specific approaches used:
1.1. Ricketts:Ricketts:
 Utility arch:Utility arch:
 Buccal root torque of lowerBuccal root torque of lower
molarsmolars
 Tip backTip back
 Toe-in bendToe-in bend
 Nance buttonNance button
 Quad helixQuad helix
 Headgears: cervical,Headgears: cervical,
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2.2. Alexander:Alexander:
 6 degrees distal tip of lower first molar6 degrees distal tip of lower first molar
 ‘‘Retractors’ ( Dr. Fred Schudy):Retractors’ ( Dr. Fred Schudy):
Cervical, combination or high pull dependingCervical, combination or high pull depending
on growth patternon growth pattern
 5 degree labial root torque in lower anteriors5 degree labial root torque in lower anteriors
 Two stage upper anterior retractionTwo stage upper anterior retraction
 En mass lower anterior retractionEn mass lower anterior retraction

Roth:Roth:
 Frictionless space closureFrictionless space closure
with double keyhole loopswith double keyhole loops
 Asher facebow to retractAsher facebow to retract
anteriors in criticalanteriors in critical
anchorage casesanchorage cases
 Palatal arches involvingPalatal arches involving
second molarssecond molars

3.3. Burstone:Burstone:
Two-tooth concept and segmentalTwo-tooth concept and segmental
movementmovement
 Arch divided into 1 anterior and 2Arch divided into 1 anterior and 2
posterior segments, treated asposterior segments, treated as
separate unitsseparate units
 Frictionless mechanics using TMAFrictionless mechanics using TMA
springs; low load deflection ratesprings; low load deflection rate
 TPA/ lingual archTPA/ lingual arch
 Differential M/F ratios controls theDifferential M/F ratios controls the
anchorageanchorage

 Considerations in Loop Mechanics:Considerations in Loop Mechanics:
The performance of a loop is determined by:The performance of a loop is determined by:
1.1. Spring Properties: The amount of force itSpring Properties: The amount of force it
delivers and the way the force changes as teethdelivers and the way the force changes as teeth
move. Affected by wire size, wire material, legmove. Affected by wire size, wire material, leg
length, configuration and interbracket distancelength, configuration and interbracket distance
2.2. Root Paralleling Moments: Limits the amountRoot Paralleling Moments: Limits the amount
of wire that can be incorporated to make theof wire that can be incorporated to make the
loop springierloop springier

Considerations in Loop Mechanics:Considerations in Loop Mechanics:

 Location of the Loop:Location of the Loop:
Extent to which it serves as a symmetric orExtent to which it serves as a symmetric or
asymmetric V bendasymmetric V bend
 Additionally the loop must “fail safe” : toothAdditionally the loop must “fail safe” : tooth
movement should stop after a prescribedmovement should stop after a prescribed
range of movementrange of movement
 Different loop designs:Different loop designs:
1.1. Vertical loops:Vertical loops:

2.2. Delta loop:Delta loop:
 Made in 16x22 wireMade in 16x22 wire
 Activated by openingActivated by opening
3.3. Double Keyhole Loop:Double Keyhole Loop:
 Ronald RothRonald Roth
 Made in 0.019x 0.026 dimensionMade in 0.019x 0.026 dimension

4.4. T- loop:T- loop:
 BurstoneBurstone
 Made of 0.018/0.017 x 0.025Made of 0.018/0.017 x 0.025
TMA wireTMA wire
 Low load deflection rateLow load deflection rate
 Higher M/F ratios obtained byHigher M/F ratios obtained by
placing more wire lengthplacing more wire length
gingivallygingivally
 Activation is quite sensitive andActivation is quite sensitive and
needs to be activated at 6needs to be activated at 6
different placesdifferent places

5.5. Opus Closing Loop:Opus Closing Loop:
 Designed by SiatkowskiDesigned by Siatkowski
 Offers excellent control of forces and momentsOffers excellent control of forces and moments
 Made in 16x22 or 18x25 steel or 17x25 TMAMade in 16x22 or 18x25 steel or 17x25 TMA
wirewire

6.6. K-SIR LoopK-SIR Loop::
 .019x.025 TMA wire.019x.025 TMA wire
 Brings about simultaneous intrusion andBrings about simultaneous intrusion and
retraction of the anterior teethretraction of the anterior teeth
 Low load deflection rate and good rangeLow load deflection rate and good range

BENNETT AND MCLAUGHLIN:BENNETT AND MCLAUGHLIN:
Anchorage control:Anchorage control:
‘‘The maneuvers used to restrict undesirableThe maneuvers used to restrict undesirable
changes during the opening phase ofchanges during the opening phase of
treatment, so that leveling and aligning istreatment, so that leveling and aligning is
achieved without key features of theachieved without key features of the
malocclusion becoming worse.’malocclusion becoming worse.’

Horizontal Anchorage Control:Horizontal Anchorage Control:
 Control of Anterior Segments:Control of Anterior Segments:
 Tendency for the incisors and theTendency for the incisors and the
cuspids to tip forward whencuspids to tip forward when
archwires are first placedarchwires are first placed
 To prevent anterior teeth fromTo prevent anterior teeth from
tipping forward, elastic forcetipping forward, elastic force
appliedapplied
 Opened the bite in the premolarOpened the bite in the premolar
area and deepened the bitearea and deepened the bite
anteriorly-anteriorly- Roller Coaster EffectRoller Coaster Effect

 To minimize this effect:To minimize this effect:
A new system of forceA new system of force
developed by Bennett anddeveloped by Bennett and
McLaughlin:McLaughlin:
 Use ofUse of lacebackslacebacks: Initial tipping: Initial tipping
followed by a period of reboundfollowed by a period of rebound
due to levelling effect of the archdue to levelling effect of the arch
wirewire
 Bending the arch wire behind theBending the arch wire behind the
most distally banded posteriormost distally banded posterior
toothtooth

 Lacebacks and Bendbacks:Lacebacks and Bendbacks:

 Use ofUse of lacebackslacebacks::
 Study conducted byStudy conducted by
Robinson in 1989Robinson in 1989
 Little additional loss ofLittle additional loss of
anchorage in posterioranchorage in posterior
segments while asegments while a
substantial gain insubstantial gain in
anchorage in anterioranchorage in anterior
segmentssegments

 Control of Posterior Segments:Control of Posterior Segments:
Posterior anchorage requirements are greater inPosterior anchorage requirements are greater in
upper arch:upper arch:
 Upper anterior segment has larger teethUpper anterior segment has larger teeth
 Upper anterior brackets have greater amountUpper anterior brackets have greater amount
of tip built into themof tip built into them
 Upper incisors require greater torque controlUpper incisors require greater torque control
and bodily movementand bodily movement

 Upper molars move mesially more readilyUpper molars move mesially more readily
 More Class II type of malocclusionsMore Class II type of malocclusions
encounteredencountered
..˙. Extra-oral force to provide anchorage˙. Extra-oral force to provide anchorage
control in upper archcontrol in upper arch
- High angle cases: occipital headgearHigh angle cases: occipital headgear
- Low angle cases: cervical headgearLow angle cases: cervical headgear
- Supplemented with TPASupplemented with TPA

 Control of Posterior Segments:Control of Posterior Segments: Lower ArchLower Arch
 Lingual arch and lacebacks adequate forLingual arch and lacebacks adequate for
anchorage supportanchorage support
 Class III elastics once the 0.016 round wireClass III elastics once the 0.016 round wire
has been reachedhas been reached

Vertical Anchorage Control:Vertical Anchorage Control:
 Incisor Vertical Control:Incisor Vertical Control:
 Distally tipped canines cause extrusion of theDistally tipped canines cause extrusion of the
incisors- avoided by not bracketing the incisors orincisors- avoided by not bracketing the incisors or
not tying the arch wire into incisor bracketsnot tying the arch wire into incisor brackets

 Avoid early engagement of high labiallyAvoid early engagement of high labially
placed caninesplaced canines

 Molar Vertical Control:Molar Vertical Control:
 Upper second molarsUpper second molars
generally not initiallygenerally not initially
banded; step placed behindbanded; step placed behind
the first molarthe first molar
 Attempt to achieve bodilyAttempt to achieve bodily
movement during expansionmovement during expansion
 Palatal barsPalatal bars
 In high angle cases, high-In high angle cases, high-
pull or combination pullpull or combination pull
headgearheadgear
 Upper or lower posteriorUpper or lower posterior
bite platebite plate www.indiandentalacademy.comwww.indiandentalacademy.com

Lateral Anchorage Control:Lateral Anchorage Control:
 Intercanine Width:Intercanine Width: Should be maintainedShould be maintained
 Molar Crossbites:Molar Crossbites: Avoid correction by tippingAvoid correction by tipping
movementsmovements

 During space closure,During space closure,
heavy forces avoided byheavy forces avoided by
the use ofthe use of active tiebacksactive tiebacks
 Once completed,Once completed, passivepassive
tiebackstiebacks used to maintainused to maintain
the correctionthe correction

Inverse Anchorage Technique:Inverse Anchorage Technique:
 JosJoséé CarriCarrièère:re:
 Mandible is a preferred point of reference forMandible is a preferred point of reference for
diagnosis and treatment planning, whilediagnosis and treatment planning, while
maxilla is better suited to acceptingmaxilla is better suited to accepting
orthodontic correctionorthodontic correction
 Mandible is subjected to considerableMandible is subjected to considerable
movement and hence a variable referencemovement and hence a variable reference
point. Actively influenced by musclespoint. Actively influenced by muscles
surrounding itsurrounding it

 Maxilla bears a fixed anatomical relationshipMaxilla bears a fixed anatomical relationship
to the skull. Less influenced by vectors andto the skull. Less influenced by vectors and
forces generated by the surrounding musclesforces generated by the surrounding muscles
 Histological difference between maxilla andHistological difference between maxilla and
mandible ; maxilla has more plasticity ofmandible ; maxilla has more plasticity of
responseresponse
 Treatment starts from the distal segments andTreatment starts from the distal segments and
moves sectionally towards the mesial partmoves sectionally towards the mesial part
((distomesial sequencedistomesial sequence))

 Inverse Anchorage Equation:Inverse Anchorage Equation:
C - Dc/2 – R1 = 0C - Dc/2 – R1 = 0 where,where,
C= horizontal distance b/w the cusp tip of the upperC= horizontal distance b/w the cusp tip of the upper
canine and the end of the distal ridge of the lowercanine and the end of the distal ridge of the lower
caninecanine
Dc= arch length discrepancy of the mandibular arch,Dc= arch length discrepancy of the mandibular arch,
measured from distal of both lower caninesmeasured from distal of both lower canines
R1= amount in mm which the anterior limit of the lowerR1= amount in mm which the anterior limit of the lower
incisors should be moved in the cephalogram for theincisors should be moved in the cephalogram for the
correction of a casecorrection of a case

 On knowing both the variables, it is possible toOn knowing both the variables, it is possible to
deduce the distance to which the upper caninesdeduce the distance to which the upper canines
have to be distalisedhave to be distalised
 C= Dc/2 + R1C= Dc/2 + R1
 If CIf C >> Dc/2 + R1; amount of anchorageDc/2 + R1; amount of anchorage
prepared is greater than neededprepared is greater than needed
 If CIf C << Dc/2 + R1; a loss of anchorage hasDc/2 + R1; a loss of anchorage has
occuredoccured

 Through this equation, we are able to:Through this equation, we are able to:
1.1. Prescribe the amount of anchorage requiredPrescribe the amount of anchorage required
2.2. Control the condition of the anchorageControl the condition of the anchorage
3.3. Ideal resultsIdeal results

Stages:Stages:
 Maxillary stage:Maxillary stage:
Treatment started in the maxilla with posteriorTreatment started in the maxilla with posterior
leveling, canine retraction, anterior levelingleveling, canine retraction, anterior leveling
and anterior retractionand anterior retraction
 Mandibular stage:Mandibular stage:
same sequencesame sequence

IMPLANTS :IMPLANTS :
 Boucher: ‘Boucher: ‘Implants are alloplastic devicesImplants are alloplastic devices
which are surgically insertedwhich are surgically inserted intointo oror ontoonto jawjaw
bone.’bone.’
Why implants?Why implants?
Limitations of fixed orthodontic therapy:Limitations of fixed orthodontic therapy:
 Headgear complianceHeadgear compliance
 Reactive forces from dental anchorsReactive forces from dental anchors

 Anchorage Source:Anchorage Source:
 Orthopedic anchorage:Orthopedic anchorage:
- maxillary expansion- maxillary expansion
- headgear like effects- headgear like effects
 Dental anchorage:Dental anchorage:
- space closure- space closure
- intrusion ( anterior and posterior)- intrusion ( anterior and posterior)
- distalization- distalization

 Implant designs for orthodontic usage:Implant designs for orthodontic usage:
 OnplantOnplant
 Impacted titanium postImpacted titanium post
 Mini-implantMini-implant
 Micro-implantMicro-implant
 Skeletal anchorage systemSkeletal anchorage system

Implants for intrusion ofImplants for intrusion of
teeth:teeth:
 Creekmore ( 1983)Creekmore ( 1983)
 Vitallium bone screw

 Implants for spaceImplants for space
closure:closure:
Eugene Roberts: use ofEugene Roberts: use of
retromolar implants forretromolar implants for
anchorageanchorage
Size of implant: 3.8mmSize of implant: 3.8mm
width and 6.9mmwidth and 6.9mm
lengthlength

 Onplant: Block andOnplant: Block and
Hoffman (1995)Hoffman (1995)
Titanium disc- coatedTitanium disc- coated
with hydroxyapatite onwith hydroxyapatite on
one side and threadedone side and threaded
hole on the otherhole on the other
Inserted subperiosteallyInserted subperiosteally

 Impacted titanium posts:Impacted titanium posts:
Bousquet and Mauran (1996)Bousquet and Mauran (1996)
Post impacted between upperPost impacted between upper
right first molar and secondright first molar and second
premolar extraction space onpremolar extraction space on
labial surface of alveolarlabial surface of alveolar
processprocess

 Mini-implant:Mini-implant:
Ryuzo Kanomi ( 1997)Ryuzo Kanomi ( 1997)
Small titanium screwsSmall titanium screws
1.2mm diameter and1.2mm diameter and
6mm length6mm length
Initially used for incisorInitially used for incisor
intrusionintrusion

 Skeletal anchorage system (SAS):Skeletal anchorage system (SAS):
Sugawara and Umemori (1999)Sugawara and Umemori (1999)
Titanium miniplatesTitanium miniplates
Placement in key ridge for upper molar and ramus forPlacement in key ridge for upper molar and ramus for
lower molar intrusionlower molar intrusion
Uses:Uses:
- molar intrusionmolar intrusion
- Molar intrusion and distalisationMolar intrusion and distalisation
- Incisor intrusionIncisor intrusion
- Molar protractionMolar protraction

 Micro-implants:Micro-implants:
 For retracting the maxillaryFor retracting the maxillary
anteriors & uprighting theanteriors & uprighting the
mandibular molarsmandibular molars
 No side effects on the anteriorNo side effects on the anterior
teethteeth

Zygoma Ligatures: An AlternativeZygoma Ligatures: An Alternative
Form of Maxillary AnchorageForm of Maxillary Anchorage
Brite MelsonBrite Melson
Jens Kolsen PetersonJens Kolsen Peterson
Antonio CostaAntonio Costa
JCO/ MARCH 1998JCO/ MARCH 1998
 Indicated in patients without sufficient posteriorIndicated in patients without sufficient posterior
anchorage in whom other forms of anchorage haveanchorage in whom other forms of anchorage have
been ruled outbeen ruled out
 Best bone quality is found in the zygomatic arch andBest bone quality is found in the zygomatic arch and
infrazygomatic crest in a partially edentulous patientinfrazygomatic crest in a partially edentulous patient

 Surgical Technique:Surgical Technique:
 A horizontal bony canal drilled in the region ofA horizontal bony canal drilled in the region of
infrazygomatic crestinfrazygomatic crest
 A double twisted 0.012 wire is pulled throughA double twisted 0.012 wire is pulled through
this canalthis canal
 Wire covered by a thin polyethylene catheterWire covered by a thin polyethylene catheter
to protect the mucosato protect the mucosa

 Orthodontic Technique:Orthodontic Technique:
 A coil spring is extended from the zygomaA coil spring is extended from the zygoma
ligature to the point of force applicationligature to the point of force application
 Center of resistance determines point of forceCenter of resistance determines point of force
applicationapplication
 Prosthesis should be constructed immediatelyProsthesis should be constructed immediately
after removal of the applianceafter removal of the appliance
 Zygomatic wires are removed by pulling atZygomatic wires are removed by pulling at
one endone end

Rapid orthodontic tooth movement intoRapid orthodontic tooth movement into
newly distracted bone after mandibularnewly distracted bone after mandibular
distraction osteogenesis in a caninedistraction osteogenesis in a canine
modelmodel
Eric Jein-Wein LiouEric Jein-Wein Liou
Alvaro A. FigueroaAlvaro A. Figueroa
John W. PollyJohn W. Polly
AJO, April 2000AJO, April 2000

 ‘‘Distraction osteogenesis is a process ofDistraction osteogenesis is a process of
growing new bone by mechanically stretchinggrowing new bone by mechanically stretching
preexisting vascularised bone tissue.’preexisting vascularised bone tissue.’
 Purpose of the Study:Purpose of the Study:
To determine the feasibility, timing and rate ofTo determine the feasibility, timing and rate of
orthodontic tooth movement into the fibrousorthodontic tooth movement into the fibrous
bone recently formed through distractionbone recently formed through distraction
osteogenesis in the canine mandibleosteogenesis in the canine mandible

 Material and Methods:Material and Methods:
 Four mature beagle dogsFour mature beagle dogs
 A custom-made intraoralA custom-made intraoral
distraction device using andistraction device using an
orthodontic palatalorthodontic palatal
expanderexpander
 Surgical Procedure:Surgical Procedure:
 Mandibular body osteotomyMandibular body osteotomy
 Care taken to preserve 0.5Care taken to preserve 0.5
to 1.0mm thickness ofto 1.0mm thickness of
alveolar bonealveolar bone
 Distraction device fixedDistraction device fixed
with bone screwswith bone screws

 Distraction Procedures:Distraction Procedures:
 7 day latency period7 day latency period
 Distraction device activated 1mm each day forDistraction device activated 1mm each day for
14 days14 days
 Orthodontic Tooth Movement:Orthodontic Tooth Movement:
 Calibrated elastic threads with 50g ofCalibrated elastic threads with 50g of
orthodontic force applied to mandibular fourthorthodontic force applied to mandibular fourth
premolars for 5 weekspremolars for 5 weeks

 On one side, premolar moved simultaneouslyOn one side, premolar moved simultaneously
with the distraction procedure and on the otherwith the distraction procedure and on the other
after the completion of distractionafter the completion of distraction
 Distraction device and orthodontic appliancesDistraction device and orthodontic appliances
left in place for another 4 months before theleft in place for another 4 months before the
dogs were sacrificeddogs were sacrificed
 Results:Results:
 Tooth movement at the same time asTooth movement at the same time as
distraction- 6mm in 7 weeksdistraction- 6mm in 7 weeks

 Tooth movementTooth movement
immediately after cessationimmediately after cessation
of distraction- 6mm in 5of distraction- 6mm in 5
weeksweeks
 Fourth premolars movedFourth premolars moved
with distraction- horizontalwith distraction- horizontal
bone loss. No nativebone loss. No native
alveolar bone identifiedalveolar bone identified
 Radiographically, extrudedRadiographically, extruded
and tipped forwardand tipped forward
 Fourth premolars movedFourth premolars moved
after distraction- mild to noafter distraction- mild to no
alveolar bone lossalveolar bone loss
 Native alveolar boneNative alveolar bone
preservedpreserved

 Discussion:Discussion:
1.1. Osteogenesis in rapid tooth movement:Osteogenesis in rapid tooth movement:
 Average rate of tooth movement: 0.3 mm perAverage rate of tooth movement: 0.3 mm per
weekweek
 In the study, rate of tooth movement: 1.2 mmIn the study, rate of tooth movement: 1.2 mm
per weekper week
 The process of osteogenesis on the tensionThe process of osteogenesis on the tension
side; a form of distraction osteogenesisside; a form of distraction osteogenesis
 No infrabony defect on tension sideNo infrabony defect on tension side

2. Less bone resistance, faster tooth movement:2. Less bone resistance, faster tooth movement:
 Typical rate of tooth movement with 100g ofTypical rate of tooth movement with 100g of
tipping force: 1.5 mm in 5 weekstipping force: 1.5 mm in 5 weeks
 In this study, with 50g of tipping force: 6mmIn this study, with 50g of tipping force: 6mm
in 5 weeksin 5 weeks
 Teeth moved into fibrous immature boneTeeth moved into fibrous immature bone
tissuestissues

3. Timing to initiate rapid3. Timing to initiate rapid
orthodontic toothorthodontic tooth
movement:movement:
 Theoretically, during the firstTheoretically, during the first
few days after distractionfew days after distraction
 Transient burst of localizedTransient burst of localized
osteoclastic activity results inosteoclastic activity results in
resorption of alveolarresorption of alveolar
 Native alveolar bone adjacentNative alveolar bone adjacent
to fourth premolar movedto fourth premolar moved
simultaneously withsimultaneously with
distraction disappeareddistraction disappeared
completelycompletely

 Fourth premolars moved after distraction:Fourth premolars moved after distraction:
native crestal alveolar bone preserved andnative crestal alveolar bone preserved and
brought into the distraction spacebrought into the distraction space
4. Pulp Vitality:4. Pulp Vitality:
 Maintained in all teethMaintained in all teeth
Conclusion:Conclusion:
The best time to initiate tooth movement wasThe best time to initiate tooth movement was
immediately after the end of distractionimmediately after the end of distraction

Ongoing Innovations inOngoing Innovations in
Biomechanics and Materials for theBiomechanics and Materials for the
New MillenniumNew Millennium
Robert P. KusyRobert P. Kusy
Angle Orthodontist, 2000Angle Orthodontist, 2000

 Glossary of Terms:Glossary of Terms:
 FR: classical frictionFR: classical friction
 µ: coefficient of frictionµ: coefficient of friction
 N: normal or ligation forceN: normal or ligation force
 θ: second order angulation of an arch wireθ: second order angulation of an arch wire
relative to a bracketrelative to a bracket
 θθc: critical contact angle or second order angulation: critical contact angle or second order angulation
after which binding (BI) occursafter which binding (BI) occurs
 θθz: second order angulation after which binding(BI): second order angulation after which binding(BI)
ends and physical notching(NO) beginsends and physical notching(NO) begins

 Glossary of Terms:Glossary of Terms:
 BI: elastic binding causedBI: elastic binding caused
by exceedingby exceeding θθc but less thanbut less than
θθz
 NO: physical notchingNO: physical notching
caused by exceedingcaused by exceeding θθz
 Bracket Index: Width/SlotBracket Index: Width/Slot
 Clearance Index: 1-Clearance Index: 1-
Engagement IndexEngagement Index
 Engagement Index:Engagement Index:
Size/SlotSize/Slot

 Introduction:Introduction:
Biomechanics and materials complement oneBiomechanics and materials complement one
another; yet are presented as though they areanother; yet are presented as though they are
independent of each otherindependent of each other
 Biomechanics as a Science:Biomechanics as a Science:
For each arch-wire bracket combination aFor each arch-wire bracket combination a
critical contact angle (critical contact angle (θθc ) exists given by the) exists given by the
relationship:relationship:
θθc= 57.3( Clearance Index)
(Bracket Index)(Bracket Index)

θθc= 57.3( 1- Engagement Index)
(Bracket Index)(Bracket Index)
 Once binding occurs, it can assume two forms:Once binding occurs, it can assume two forms:
 Elastic DeformationElastic Deformation
 Plastic Deformation (Plastic Deformation (physical notchingphysical notching))
 Overall resistance to sliding:Overall resistance to sliding:
RS = FR+BI+NORS = FR+BI+NO
 FR occurs because of the ligation or normalFR occurs because of the ligation or normal
force (N)force (N)

 Elastic binding (BI)Elastic binding (BI)
occurs once the wireoccurs once the wire
contacts the diagonal tie-contacts the diagonal tie-
wings of a bracketwings of a bracket
 Physical notching: plasticPhysical notching: plastic
deformation occurs at thedeformation occurs at the
diagonal tie-wings or thediagonal tie-wings or the
opposing wire contactsopposing wire contacts
 For optimal slidingFor optimal sliding θ ≈ θθ ≈ θc
 Sliding at θ < θSliding at θ < θc results inresults in
increased treatment timeincreased treatment time
 Sliding at θSliding at θc < θ <θ< θ <θz ::
amount of binding andamount of binding and
the treatment timethe treatment time
increasesincreases www.indiandentalacademy.comwww.indiandentalacademy.com

Using Biomechanics to Innovate NewUsing Biomechanics to Innovate New
MaterialsMaterials
 To reduce FR, 2 options exist:To reduce FR, 2 options exist:
DecreaseDecrease µ or decrease Nµ or decrease N
 Reducing FR by decreasing µ for θ < θReducing FR by decreasing µ for θ < θc
Improving surface chemistryImproving surface chemistry
 Reducing FR by decreasing N for θ < θReducing FR by decreasing N for θ < θc
Two methods:Two methods:
1.1. Use of self ligating bracketsUse of self ligating brackets
2.2. Development of stress relaxed ligaturesDevelopment of stress relaxed ligatures

MaterialsMaterials
 Use of self ligatingUse of self ligating
brackets:brackets:
 Minimize NMinimize N
 When θ < θWhen θ < θc FR is lowFR is low
 BI behaves similar toBI behaves similar to
conventional bracketsconventional brackets
 Perhaps the overstatementPerhaps the overstatement
of their capabilitiesof their capabilities
promoted practitioners topromoted practitioners to
slide teeth whenslide teeth when
θ > θθ > θc

MaterialsMaterials
 Development of stress relaxed ligatures:Development of stress relaxed ligatures:
 Short term forces resisted by elastic, highShort term forces resisted by elastic, high
strength material; long term forcesstrength material; long term forces
accommodated by stress relaxation and anaccommodated by stress relaxation and an
accompanying decrease in Naccompanying decrease in N
 Formed from acrylic monomer n-butylFormed from acrylic monomer n-butyl
methacrylate and drawn polyethylene fibers bymethacrylate and drawn polyethylene fibers by
use of the photo-pultrusion processuse of the photo-pultrusion process

MaterialsMaterials
 StabilizingStabilizing θ at θ ≈ θθ at θ ≈ θc
 2 means are available:2 means are available:
1.1. Power armsPower arms
2.2. Composite arch wiresComposite arch wires
 Power armsPower arms
 A force that passes through the center ofA force that passes through the center of
resistance generates no momentresistance generates no moment
 Once a tooth moves, the point of forceOnce a tooth moves, the point of force
application shifts away from the center ofapplication shifts away from the center of
resistanceresistance www.indiandentalacademy.comwww.indiandentalacademy.com

MaterialsMaterials
 Use of composite arch wires:Use of composite arch wires:
 To slide teeth a clinician chooses fromTo slide teeth a clinician chooses from
among several archwire- bracketamong several archwire- bracket
combinationscombinations
 By integrating two classes of materials (aBy integrating two classes of materials (a
ceramic and a polymer), a compositeceramic and a polymer), a composite
archwire can be fabricated.archwire can be fabricated.
 Mechanical properties differ, overall cross-Mechanical properties differ, overall cross-
sectional area remains constantsectional area remains constant

Use of composite arch wires:Use of composite arch wires:
 Manufactured by the photo-pultrusion processManufactured by the photo-pultrusion process
using ceramic glass fiber yarns and acrylicusing ceramic glass fiber yarns and acrylic
monomersmonomers
 For 3 levels of fiber loading (49, 59 and 70%For 3 levels of fiber loading (49, 59 and 70%
v/v) the values ofv/v) the values of µ and θµ and θc remained constantremained constant
 This constancy should be advantageousThis constancy should be advantageous

MaterialsMaterials
 Reducing BI forReducing BI for θθc < θ< θ
<θ<θz ::
 IfIf θ exceeds θθ exceeds θc , some, some
binding occursbinding occurs
 In the past, practitionersIn the past, practitioners
chose archwire bracketchose archwire bracket
combinations thatcombinations that
represent a compromiserepresent a compromise
between binding andbetween binding and
controlcontrol www.indiandentalacademy.comwww.indiandentalacademy.com

Reducing BI forReducing BI for θθc < θ <θ< θ <θz ::
 With increasing stiffness, decreasingWith increasing stiffness, decreasing
interbracket distance, or both, bindinginterbracket distance, or both, binding
increasesincreases
 In recent work, binding has been reduced byIn recent work, binding has been reduced by
materials having high resiliencies and highmaterials having high resiliencies and high
yield strength- resistance to deformation andyield strength- resistance to deformation and
physical notchingphysical notching
 Use of composite wires made from ceramicUse of composite wires made from ceramic
glass fibers and a BIS-GMA-TEGMA matrixglass fibers and a BIS-GMA-TEGMA matrix

Photo-pultrusion:Photo-pultrusion:
 Fibers are drawn into a chamber: spread,Fibers are drawn into a chamber: spread,
tensioned and coated with monomertensioned and coated with monomer
 Reconstituted into a profile of specificReconstituted into a profile of specific
dimensions via a diedimensions via a die
 As photons of light polymerize the structureAs photons of light polymerize the structure
into a compositeinto a composite
 Any shrinkage voids are replenished by aAny shrinkage voids are replenished by a
gravity fed monomergravity fed monomer

Photo-pultrusion:Photo-pultrusion:
 If further shaping is required, composite isIf further shaping is required, composite is
only partially cured (only partially cured (α staged)α staged)
 Further processed using a second die and βFurther processed using a second die and β
staged into final formstaged into final form

Conclusions:Conclusions:
 Sliding mechanics should occur only at valuesSliding mechanics should occur only at values
of angulation (of angulation (θ)θ) that are in close proximity tothat are in close proximity to
the critical contact angle (the critical contact angle (θθc))
 Material innovations can reduce FR at θ < θMaterial innovations can reduce FR at θ < θc byby
reducing the coefficient of friction, the normalreducing the coefficient of friction, the normal
force of ligation or both, among which variousforce of ligation or both, among which various
surface treatments and stress relaxed ligaturessurface treatments and stress relaxed ligatures
are 2 meansare 2 means

Conclusions:Conclusions:
 Composite materials can stabilizeComposite materials can stabilize θ at θ ≈ θθ at θ ≈ θc byby
maintaining the same archwire bracketmaintaining the same archwire bracket
clearance while permitting the force deflectionclearance while permitting the force deflection
characteristics to varycharacteristics to vary
 Decreasing wire stiffness or increasingDecreasing wire stiffness or increasing
interbracket distance can reduce RS atinterbracket distance can reduce RS at θθc < θ< θ
<θ<θz, independent of the material used, independent of the material used

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