Root movement in orthodontics

ROOT MOVEMENTROOT MOVEMENT
IN ORTHODONTICSIN ORTHODONTICS
……
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CONTENTS
• Introduction
• Need for axial corrections
• Torque
• Diagnosis & Evaluation for root correction
• Biomechanical considerations
• Root movement in Removable Appliances
• Root movement in Beggs
• Root movement in PEARoot movement in PEA
• Root movement in segmental arch technique

• Root movement in Segmental SurgeryRoot movement in Segmental Surgery
• Cortical AnchorageCortical Anchorage
• ComplicationsComplications
• ConclusionConclusion
• BibliographyBibliography

INTRODUCTIONINTRODUCTION

 Control of theControl of the axial inclinationsaxial inclinations of teeth duringof teeth during
orthodontic therapy is critical for achieving excellentorthodontic therapy is critical for achieving excellent
results and ensuringresults and ensuring long term stabilitylong term stability afterafter
completion of treatment.completion of treatment.
 The careful evaluation of individual tooth axialThe careful evaluation of individual tooth axial
inclinations is often carried out as ainclinations is often carried out as a second stage ofsecond stage of
space closurespace closure in extraction therapy or beforein extraction therapy or before
completion of treatment in non-extraction therapy.completion of treatment in non-extraction therapy.

Need For AxialNeed For Axial
CorrectionsCorrections

 Good axial inclinations andGood axial inclinations and
adequateadequate root parallelismroot parallelism withwith
regular bone distributionregular bone distribution
between teeth helps to obtainbetween teeth helps to obtain
and maintain aand maintain a stablestable
treatment result.treatment result.

Raleigh WilliamRaleigh William
 The lower incisor roots, rather than theirThe lower incisor roots, rather than their
crowns, should becrowns, should be divergentdivergent. If the roots. If the roots
are leftare left convergentconvergent, the crowns tend to, the crowns tend to
bunch together and causebunch together and cause relapse.relapse.

STABLE UNSTABLE

 The evaluation ofThe evaluation of root axial inclinationsroot axial inclinations
is also critical in patients withis also critical in patients with congenitallycongenitally
missing teethmissing teeth when the goal is to replacewhen the goal is to replace
these teeth with eitherthese teeth with either implantsimplants oror
bridges.bridges.

CREATING SPACE FOR IMPLANTSCREATING SPACE FOR IMPLANTS

 Parallelism of theParallelism of the abutments rootsabutments roots as wells asas wells as
adequate bone distribution are important factors in theadequate bone distribution are important factors in the
prognosis and successful outcome of treatment.prognosis and successful outcome of treatment.
 Root correction, which may involve individual teeth orRoot correction, which may involve individual teeth or
groups of teeth is also instrumental ingroups of teeth is also instrumental in positioning teethpositioning teeth
over basal bone to achieve an ideal occlusalover basal bone to achieve an ideal occlusal
relationshiprelationship in the anterior and posterior portions of thein the anterior and posterior portions of the
dental arches.dental arches.

Providing good PeriodontalProviding good Periodontal
EnvironmentEnvironment
 Gingiva folded and bunched upGingiva folded and bunched up
 Plaque harboring pseudoPlaque harboring pseudo
pocketpocket

TORQUETORQUE

 In terms ofIn terms of Engineering principlesEngineering principles, it is defined as a, it is defined as a
force causing twistforce causing twist in a structure, the resulting twistin a structure, the resulting twist
of the mechanical part is calledof the mechanical part is called TorsionTorsion..
 In terms ofIn terms of orthodonticsorthodontics it is defined as theit is defined as the
buccolingualbuccolingual oror labiolinguallabiolingual root tipping in whichroot tipping in which
the movement of the crown is minimized andthe movement of the crown is minimized and
movement of the root apex is maximized.movement of the root apex is maximized.

 Torque can be effectively employed in removableTorque can be effectively employed in removable
appliance and in fixed appliances.appliance and in fixed appliances.
 Torquing mechanics are more effective and widelyTorquing mechanics are more effective and widely
used inused in fixed mechanotherapyfixed mechanotherapy than in removablethan in removable
appliances. In removable appliances springs areappliances. In removable appliances springs are
used for torquing the tooth.used for torquing the tooth.

Torque in the fixed appliance can beTorque in the fixed appliance can be
employed in different ways.employed in different ways.
• By giving aBy giving a twisttwist in the arch wire commonlyin the arch wire commonly
used in Edgewise technique.used in Edgewise technique.
• Torque exerted by theTorque exerted by the bracketbracket itself e.g., PEAitself e.g., PEA
• By the use ofBy the use of Torquing auxiliariesTorquing auxiliaries widely usedwidely used
in Begg technique and Edgewise technique.in Begg technique and Edgewise technique.

Diagnosis &Diagnosis &
Evaluation for RootEvaluation for Root
CorrectionCorrection

 Root correction may be considered theRoot correction may be considered the second phasesecond phase
of space closureof space closure and most often completion of spaceand most often completion of space
closure is recommended before evaluating for theclosure is recommended before evaluating for the
potential need to correctpotential need to correct root axial inclinationsroot axial inclinations..
 Clinical assessment of root positionsClinical assessment of root positions during spaceduring space
closure is often very useful and may be done byclosure is often very useful and may be done by
monitoring the inclinations of the canine and anteriormonitoring the inclinations of the canine and anterior
brackets.brackets.

 Lateral cephalometricLateral cephalometric head films,head films, IOPAIOPA taken attaken at
454500
andand PanoramicPanoramic radiographs are commonlyradiographs are commonly
used to assess the need for not correction.used to assess the need for not correction.
 Lateral head films primarily assist in evaluatingLateral head films primarily assist in evaluating
thethe axial inclinations of the anterioraxial inclinations of the anterior teethteeth byby
comparing a film taken before initiation ofcomparing a film taken before initiation of
treatment and one taken after completion oftreatment and one taken after completion of
space closure.space closure.

Checking Lateral Ceph for Torque
Requirement
Finish with upper incisors parallel to the facial Axis

 Radiographs taken at 45Radiographs taken at 4500
indicate the axialindicate the axial
inclinations of canines, premolars, and molarsinclinations of canines, premolars, and molars
and are helpful forand are helpful for assessing proper rootassessing proper root
parallelism, adequate bone distribution andparallelism, adequate bone distribution and
bone levels.bone levels.

 Despite the amount ofDespite the amount of deformationdeformation inherent ininherent in
panoramic radiographspanoramic radiographs routinely used to assessroutinely used to assess
the axial inclinations of the posterior teeth.the axial inclinations of the posterior teeth.
 This is primarily because panoramic radiographsThis is primarily because panoramic radiographs
are easily available and comparison with aare easily available and comparison with a
pretreatment panoramic radiograph is usuallypretreatment panoramic radiograph is usually
possible.possible.

PRE RX
POST RX

BIOMECHANICAL CONSIDERATIONS

Moment-to-Force ratioMoment-to-Force ratio
The ratio ofThe ratio of counter-balancingcounter-balancing momentmoment
produced toproduced to net forcenet force that is applied tothat is applied to
a tooth.a tooth.

UncontrolledUncontrolled
TippingTipping
MOMENT : FORCE

Controlled Tipping
MOMENT : FORCE

T R AN SL AT I O NT R AN SL AT I O N
MOMENT : FORCE

R O O T M O V E M E N TR O O T M O V E M E N T
MOMENT : FORCE

PEA & Begg
Moment arm of
couple
Moment arm of couple

ROOT MOVEMENT INROOT MOVEMENT IN
REMOVABLE APPLIANCESREMOVABLE APPLIANCES

 Apron springApron spring derive their main flexibility fromderive their main flexibility from
the twisting of the section and the length of thethe twisting of the section and the length of the
torque bars.torque bars.
 These torque springs areThese torque springs are flexibleflexible,, easy toeasy to
construct, easilyconstruct, easily positioned and adjusted.positioned and adjusted.

Apron springApron spring

• VERTICAL PLANEVERTICAL PLANE
• SAGITAL PLANESAGITAL PLANE
• TRANSEVERSE PLANETRANSEVERSE PLANE
ROOT MOVEMENT IN BEGGSROOT MOVEMENT IN BEGGS

VERTICAL PLANEVERTICAL PLANE

SAGITAL PLANESAGITAL PLANE
• LABIO-LINGUAL ROOT MOVEMENTLABIO-LINGUAL ROOT MOVEMENT
• TORQUINGTORQUING
• UPRIGHTINGUPRIGHTING

TORQUINGTORQUING AUXILLARIESAUXILLARIES
• Two spur & Four spur

Pre Wound Torquing AuxiliaryPre Wound Torquing Auxiliary
 Base arch wire .020” Special Plus
 Auxiliary .012”, 014”

KITCHTON AUXILIARYKITCHTON AUXILIARY
 .014” Special Plus
 Can be used with Beggs &
edgewise

 Auxiliary modified to apply labial rootAuxiliary modified to apply labial root
torque totorque to max lateralsmax laterals only.only.

Reciprocal lateral TorquingReciprocal lateral Torquing
AuxiliaryAuxiliary
 Situation where CentralSituation where Central
incisors require palatal rootincisors require palatal root
torque & Laterals requiretorque & Laterals require
labial root torque.labial root torque.

Lower Reverse Torquing AuxiliaryLower Reverse Torquing Auxiliary

MAA AuxiliaryMAA Auxiliary

Uprighting springsUprighting springs
 Mini – 0.5 mm diameterMini – 0.5 mm diameter
 Midi – 0.9 mm diameterMidi – 0.9 mm diameter
 Maxi – 1.5 mm diameterMaxi – 1.5 mm diameter

UprightingUprighting

Reciprocal uprightingReciprocal uprighting

Transverse planeTransverse plane
• Buccal root torque to molarsBuccal root torque to molars

Root Movement In PEARoot Movement In PEA
 Lawrence AndrewLawrence Andrew developed the straightdeveloped the straight
wire appliance which became widelywire appliance which became widely
available in the mid 1970s.available in the mid 1970s.
 Six keys to normal occlusion.Six keys to normal occlusion.

• Crown inclination:Crown inclination:
Is defined as an angle between a line perpendicularIs defined as an angle between a line perpendicular
to theto the occlusal planeocclusal plane and a line that is parallel andand a line that is parallel and
tangent to thetangent to the FACCFACC at its mid point (FApoint)at its mid point (FApoint)
crown inclination is determined from the mesial andcrown inclination is determined from the mesial and
distal perspectives.distal perspectives.

 InIn PEAPEA, torque or inclination of the tooth is, torque or inclination of the tooth is
expressed by the bracket itself this because of theexpressed by the bracket itself this because of the
bracket slot is cut at an angle.bracket slot is cut at an angle.
 The third key in the optimal occlusion isThe third key in the optimal occlusion is crowncrown
inclinationinclination, most maxillary incisors have positive, most maxillary incisors have positive
inclination where as mandibular incisors have ainclination where as mandibular incisors have a
slightly negative inclination.slightly negative inclination.

 The maxillary central incisors have a moreThe maxillary central incisors have a more
positive inclinationpositive inclination than laterals where asthan laterals where as
canines and premolars have acanines and premolars have a negativenegative
inclinationinclination. Maxillary first and second molars. Maxillary first and second molars
also have negative inclination.also have negative inclination.
 InclinationInclination of the mandibular teeth areof the mandibular teeth are
progressively more negative from the incisorsprogressively more negative from the incisors
to the molar.to the molar.

 Normally inNormally in PEAPEA if we engage a full sized archif we engage a full sized arch
wire into the slot it will automatically express thewire into the slot it will automatically express the
torque which is incorporated in the bracket.torque which is incorporated in the bracket.
 But in some situations it we need torque in theBut in some situations it we need torque in the
individual or more number of teeth we have toindividual or more number of teeth we have to
twist the arch wiretwist the arch wire to express the desired torqueto express the desired torque
(third order bend).(third order bend).

Torque in Face V/s Torque in
Base
Torque in FaceTorque in Face Torque in BaseTorque in Base

First Generation Of PEA
Andrews appliance
5/7 9/3 11/-7 2/-7 2/-7 5/-9 5/-9
2/-1 2/-1 5/-11 2/-17 2/-22 2/-26 2/-35
UPPER
LOWER
Tip/torque in degrees

Second Generation Of PEA
Roth appliance
5/12 9/8 13/-2 0/-7 0/-7 0/-14 0/-14
2/-1 2/-1 -1/-11 -1/-17 -1/-22 -1/-30 -1/-30
UPPER
LOWER

Third Generation Of PEA
MBT appliance
4/17 8/10 8/0 0/-7 0/-7 0/-14 0/-14
0/-6 0/-6 3/-6 2/-12 2/-17 0/-20 0/-10
UPPER
LOWER

EFFECT OF BUILT IN TIPEFFECT OF BUILT IN TIP

BUCCAL ROOT TORQUEBUCCAL ROOT TORQUE

TORQUE +10 TORQUE -10
Blocked in Lateral incisor

Root movement inRoot movement in
Segmental Arch TechniqueSegmental Arch Technique

Root movement is generally divided intoRoot movement is generally divided into
two categories;two categories;
• En masse root movement &En masse root movement &
• Individual root movement (as separateIndividual root movement (as separate
canine root movement or separate incisorcanine root movement or separate incisor
root movement).root movement).

 En masse root movementEn masse root movement is required when theis required when the
entire anterior segment must be moved as a unit,entire anterior segment must be moved as a unit,
commonly after en masse space retraction.commonly after en masse space retraction.
 If the anterior segment has been retractedIf the anterior segment has been retracted
through controlled tipping,through controlled tipping, all the roots areall the roots are
retracted as a unit.retracted as a unit.

 Separate canine root movementSeparate canine root movement may be necessarymay be necessary
following separate canine retraction.following separate canine retraction.
 When an anterior segment with flared incisors isWhen an anterior segment with flared incisors is
retracted by controlled tipping, the incisors mayretracted by controlled tipping, the incisors may
assume normal axial inclinations while the canineassume normal axial inclinations while the canine
develops adevelops a distal axial inclinationdistal axial inclination, hence only the, hence only the
canines need separate root correction.canines need separate root correction.

 En masseEn masse root movement, or root retractionroot movement, or root retraction
(rotation around a point on the crown of the(rotation around a point on the crown of the
tooth), forms a second phase of space closuretooth), forms a second phase of space closure
after tipping movement.after tipping movement.
 It is accomplished by using a mechanism thatIt is accomplished by using a mechanism that
places moments on the teeth with centers ofplaces moments on the teeth with centers of
rotation located at the level of the brackets.rotation located at the level of the brackets. TheThe
mechanism which delivers these moments ismechanism which delivers these moments is
known as a root spring.known as a root spring.

HORIZONTAL PLANEHORIZONTAL PLANE
ANTERIOR ROOT SPRINGANTERIOR ROOT SPRING

HELICAL SPRING FORHELICAL SPRING FOR
ENMASSE ROOT MOVEMENTENMASSE ROOT MOVEMENT

Cantilever for En Masse RootCantilever for En Masse Root
CorrectionCorrection

CANINE ROOT UPRIGHTINGCANINE ROOT UPRIGHTING

T-Looped spring in 17x25 SS to upright molarT-Looped spring in 17x25 SS to upright molar

VERTICAL PLANE
INTRUSION UTILITYINTRUSION UTILITY
ARCHESARCHES
INTRUSION & PROTRACTIONINTRUSION & PROTRACTION
UTILITY ARCHESUTILITY ARCHES

BURSTONE INTRUSIONBURSTONE INTRUSION
ARCHARCH
3 PIECE INTRUSION3 PIECE INTRUSION
ARCHARCH

ROOT MOVEMENT IN SEGMENTAL SURGERYROOT MOVEMENT IN SEGMENTAL SURGERY

CORTICALCORTICAL
ANCHORAGEANCHORAGE

 TheThe cortical bonecortical bone is characterized by being moreis characterized by being more
dense and laminated, with a very limited blooddense and laminated, with a very limited blood
supply.supply.
 TheThe blood supply in the boneblood supply in the bone is the key factor inis the key factor in
tooth movement, since it carries the cellulartooth movement, since it carries the cellular
elements that resorb away bone and also theelements that resorb away bone and also the
cellular elements that build up new bone.cellular elements that build up new bone.
 In cortical bone, where theIn cortical bone, where the blood supply isblood supply is
limitedlimited, the physiological process is delayed and, the physiological process is delayed and
tooth movement is slower,tooth movement is slower,

 Tooth movement can beTooth movement can be further delayedfurther delayed wherewhere
excess force against the cortical bone can pressexcess force against the cortical bone can press
out the blood supply and limit the physiology andout the blood supply and limit the physiology and
the tooth movement.the tooth movement.
 Bio-progressive TherapyBio-progressive Therapy applies this principle ofapplies this principle of
cortical bone anchorage in stabilizing the teethcortical bone anchorage in stabilizing the teeth
in those areas where it desires to limit theirin those areas where it desires to limit their
movement.movement.

 Lower molar anchorageLower molar anchorage is enhanced byis enhanced by
expanding the molar roots into the dense corticalexpanding the molar roots into the dense cortical
bone on their buccal surface.bone on their buccal surface.
 ExcessiveExcessive buccal root torquebuccal root torque andand expansionexpansion isis
placed in the archwires to locate the roots into theplaced in the archwires to locate the roots into the
cortical bone.cortical bone.

COMPLICATIONSCOMPLICATIONS
•ANCHOR LOSSANCHOR LOSS
•ROOT RESORPTIONROOT RESORPTION

ANCHOR LOSS

ROOT RESORPTIONROOT RESORPTION
• Fixed versus Removable:Fixed versus Removable: only one studyonly one study
compared root resorption resulting from fixedcompared root resorption resulting from fixed
and removable appliances, concluding that theand removable appliances, concluding that the
use of fixed appliances is more detrimental touse of fixed appliances is more detrimental to
the roots.the roots.
• KetchamKetcham claimed that normal function isclaimed that normal function is
disturbed by the splingting effect of orthodonticdisturbed by the splingting effect of orthodontic
fixed appliances over a long period that canfixed appliances over a long period that can
cause root resorption.cause root resorption.

• Stuteville on the other hand, suggested
that the juggling forces caused by
removable appliances are more harmful
to the roots.

It is often stated that the light wire Begg
technique causes less root resorption
than Edgewise, although maxillary
incisor root resorption during the Begg
third stage has been documented.
Begg versus Edgewise

Intermaxillary elastics:Intermaxillary elastics:
• Lee & LangeLee & Lange found significantly more rootfound significantly more root
resorption on the side where elastics wereresorption on the side where elastics were
used and suggested that jiggling forcesused and suggested that jiggling forces
due to elastics are responsible for rootdue to elastics are responsible for root
resorption.resorption.

Orthodontic Movement TypeOrthodontic Movement Type
 It seems that there isIt seems that there is no safeno safe toothtooth
movement.movement.
 IntrusionIntrusion is probably the mostis probably the most
detrimental to the roots involved, butdetrimental to the roots involved, but
tipping, torque, bodily movement, andtipping, torque, bodily movement, and
palatal expansion can also be implicated.palatal expansion can also be implicated.

Orthodontic ForceOrthodontic Force
 They concluded that higher stressThey concluded that higher stress
causes more root resorptioncauses more root resorption..
 According toAccording to SchwartzSchwartz Applied forceApplied force
exceeding the optimal level of 20 to 25exceeding the optimal level of 20 to 25
gm/Sq.cm causes periodontal ischemia,gm/Sq.cm causes periodontal ischemia,
which can lead to root resorption.which can lead to root resorption.

Continuous versus Intermittent Forces:Continuous versus Intermittent Forces:
 The pause in treatment with intermittent forcesThe pause in treatment with intermittent forces
allows the resorbed cementum to heal andallows the resorbed cementum to heal and
prevents further resorptionprevents further resorption..
Treatment Duration.Treatment Duration.
 Most studies report that the severity of rootMost studies report that the severity of root
resorption is directly related to treatmentresorption is directly related to treatment
duration.duration.

ConclusionConclusion
……

 Root correction is aRoot correction is a critical stepcritical step ofof
orthodontic treatment before finishing.orthodontic treatment before finishing.
 Proper root alignment and axialProper root alignment and axial
inclinations are key factors for theinclinations are key factors for the
attainment of aattainment of a functional, stable andfunctional, stable and
esthetically pleasing occlusion.esthetically pleasing occlusion.

• AdequateAdequate root parallelismroot parallelism and boneand bone
distribution will also be beneficial to longdistribution will also be beneficial to long
term periodontal health and are thereforeterm periodontal health and are therefore
important to ensure aimportant to ensure a good prognosisgood prognosis forfor
treatment.treatment.

BIBLIOGRAPHYBIBLIOGRAPHY
• The design construction and use of RemovableThe design construction and use of Removable
orthodontic Appliances By: Philip Adamsorthodontic Appliances By: Philip Adams
• Robert J. Nikolai Bio Engineering Analysis ofRobert J. Nikolai Bio Engineering Analysis of
orthodontic Mechanicsorthodontic Mechanics
• Orthodontic management of the Dentition with theOrthodontic management of the Dentition with the
pre adjustedpre adjusted
• Bennett & Richard P. Mclaughlin 2ndBennett & Richard P. Mclaughlin 2nd EditionEdition
• Edgewise Orthodontics By: Raymon C. ThurowEdgewise Orthodontics By: Raymon C. Thurow
• Contemporary Orthodontics By: William R. ProfitContemporary Orthodontics By: William R. Profit
• Roth RH Treatment mechanics for the straight wireRoth RH Treatment mechanics for the straight wire
Appliance ;Graber T.M & Vanarsadall R.RAppliance ;Graber T.M & Vanarsadall R.R

• The straight wire Appliance 17 years later J.C.O VolThe straight wire Appliance 17 years later J.C.O Vol
21; 1987; 632-64221; 1987; 632-642
• Andrews six keys to normal occlusal Am J OrhodAndrews six keys to normal occlusal Am J Orhod
1972; vol 62: 296 – 3091972; vol 62: 296 – 309
• Begg Orthodontic Theory & Technique By: P.R.Begg Orthodontic Theory & Technique By: P.R.
Begg & KeslingBegg & Kesling
• The Begg Appliance & Technique By: G.G.T.The Begg Appliance & Technique By: G.G.T.
FletcherFletcher
• Barry Mollen hauer Aust Orthodontic J 11 Oct 1990Barry Mollen hauer Aust Orthodontic J 11 Oct 1990
• T.P Orthodontics catalougeT.P Orthodontics catalouge

Root movement in orthodontics

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