mini screws

7/25/2019 Mini Screws

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MiniscrewsMiniscrewsas Orthodontic Anchorageas Orthodontic Anchorage

Sahar ShafiSahar Shafi02/13/0602/13/06


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AnchorageAnchorage

ExtraoralExtraoral

Head and Neck GearHead and Neck Gear

Patient nonPatient non--compliancecompliance

Patient discomfortPatient discomfort

Limited range of movementLimited range of movement


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IntraoralIntraoralAnchorageAnchorage

IntraarchIntraarch

--assumes more teeth offer greater anchorage than fewerassumes more teeth offer greater anchorage than fewerteeth and that tipping is easier than translationteeth and that tipping is easier than translation

InterarchInterarch

--move teeth in one direction inmove teeth in one direction in ieie. the upper jaw and in the. the upper jaw and in theopposite direction in the lower jawopposite direction in the lower jaw

ExtradentalExtradental--transfer of reactive forces to the interface between metallictransfer of reactive forces to the interface between metallic

anchorages and boneanchorages and bone


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IntraoralIntraoral ExtradentalExtradentalAnchorageAnchorage

Use alveolar bone for anchorageUse alveolar bone for anchorage

Minimizes or completely neutralizesMinimizes or completely neutralizesundesired reactive forces duringundesired reactive forces during

tooth movementstooth movements Especially indicated when lack qualityEspecially indicated when lack quality

or quantity of dental anchorage unitsor quantity of dental anchorage units

ieie.. periodontallyperiodontally involved teeth orinvolved teeth or

partialpartial edentualismedentualism


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IntraoralIntraoral ExtradentalExtradentalAnchorage SystemsAnchorage Systems

OsseointegratedOsseointegrated ImplantsImplants

--SxSx trauma upon insertion/removaltrauma upon insertion/removal

--Limited available sitesLimited available sites

--Wait time forWait time for osseointegrationosseointegration before loadingbefore loading

--High CostHigh CostOnplantsOnplants

--Same as above but considerably easier to removeSame as above but considerably easier to remove

ZygomaticZygomatic WiresWires--Limited available sites but immediate load possible for theLimited available sites but immediate load possible for thefirst time, leading to the discovery offirst time, leading to the discovery of miniscrewsminiscrews using theusing thesame principles.same principles.


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MiniscrewsMiniscrews Direct anchorageDirect anchorage Can be attached with elasticsCan be attached with elastics

oror NiTiNiTi superelasticsuperelastic coils tocoils to

fixed appliancesfixed appliances Reduced cost compared toReduced cost compared to

implantsimplants

Titanium or Stainless steelTitanium or Stainless steelminiscrewsminiscrews 66--12mm in length12mm in length

and 1.5and 1.5--2mm in diameter2mm in diameter

penetrating bone 5penetrating bone 5--8mm8mmdepending on locationdepending on location

Cap placed over top ofCap placed over top of

miniscrewminiscrew and secured withand secured with

light cured composite to avoidlight cured composite to avoid

contaminationcontamination


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Introductory KitIntroductory Kit

A screw driverA screw driver

Burs for drilling bony holeBurs for drilling bony hole

MiniscrewsMiniscrews 6,8,10, & 12mm in length6,8,10, & 12mm in length

and 1.5and 1.5--2mm in diameter2mm in diameter

2 different screw head designs2 different screw head designs


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Maxillary LocationsMaxillary Locations

Inferior surface of anterior nasal spineInferior surface of anterior nasal spine

--ProclinationProclination of incisorsof incisors

MidpalatalMidpalatal suturesuture

--DenseDense cristacrista nasalisnasalis bone for intrusion and retraction ofbone for intrusion and retraction offlared and overflared and over--erupted incisorserupted incisors

InfrazygomaticInfrazygomatic crestcrest--Retraction and intrusion of anterior teeth or intrusion ofRetraction and intrusion of anterior teeth or intrusion ofmolarsmolars


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MandibularMandibularLocationsLocations

RetromolarRetromolar positionposition

--MesalMesal movement of molars w/o retraction of anterior teethmovement of molars w/o retraction of anterior teeth

Edentulous areas of alveolar processEdentulous areas of alveolar process

--Move single tooth w/o interfering with remaining dentitionMove single tooth w/o interfering with remaining dentition

Laterally in molar/premolar regionLaterally in molar/premolar region

--Vertical and/or transverse movement of molars and premolarsVertical and/or transverse movement of molars and premolars

Anterior MandibleAnterior Mandible

--Intrusion andIntrusion and proclinationproclination of incisorsof incisors


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AdvantagesAdvantages

Ease of insertion and removalEase of insertion and removal

Orthodontist can performOrthodontist can perform-- no need for referralno need for referral

Immediate loadingImmediate loading-- shorteningshortening txtx timetime

Limited local irritation vs. otherLimited local irritation vs. other transmucosaltransmucosaltypes of anchoragetypes of anchorage

If present, localIf present, local applicatonapplicaton ofof chlorhexidinechlorhexidinecontrolled itcontrolled it

Small enough to be placed between roots ofSmall enough to be placed between roots ofadjacent teeth in alveolar bone withoutadjacent teeth in alveolar bone withoutmucoperiostealmucoperiosteal flapflap


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DisadvantagesDisadvantages

Local irritationLocal irritation

Risk of infection specific in relation toRisk of infection specific in relation to

different locations (associated withdifferent locations (associated withallall transmucosaltransmucosal anchorages)anchorages)

Perforation of maxillary sinus whenPerforation of maxillary sinus whenscrew placed inscrew placed in infrazygomaticinfrazygomatic crestcrest(no associated problems)(no associated problems)

Potential risk of contacting roots orPotential risk of contacting roots ornerves (leading tonerves (leading to complicatonscomplicatonsdepending on location)depending on location)


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Most Notable Complication:Most Notable Complication:

Loosening ofLoosening of MiniscrewsMiniscrewsIn the preliminary report in 1998 by CostaIn the preliminary report in 1998 by Costa

et al., 2 out of 16 clinical trialet al., 2 out of 16 clinical trial miniscrewsminiscrewswere lost beforewere lost before txtx was completedwas completed

In a 2004 study done byIn a 2004 study done by FortiniFortini et al., 3/19et al., 3/19miniscrewsminiscrews were lost due to incorrectwere lost due to incorrectpositioning of 1 in the maxilla and the usepositioning of 1 in the maxilla and the use

of 2 short (8mm)of 2 short (8mm) miniscrewsminiscrews in thein themandible, which were easily replaced withmandible, which were easily replaced with12mm screws without changing the12mm screws without changing the

locationlocation


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2004 Publication: Arturo et al2004 Publication: Arturo et al

SxSx ProcedureProcedure

10/19 inserted under LA via 2mm mucosal10/19 inserted under LA via 2mm mucosal

incisionincision

--periosteumperiosteum reflected from underlying bonereflected from underlying bone--drill hole w/ twist drill into bone under continuous irrigationdrill hole w/ twist drill into bone under continuous irrigation

--miniscrewminiscrew inserted manually w/ screwdriverinserted manually w/ screwdriver

2/19 inserted with mucosa punch2/19 inserted with mucosa punch--allows creation ofallows creation of transmucosaltransmucosal access to bone w/o flapaccess to bone w/o flap

--miniscrewminiscrew inserted manually w/ screwdriverinserted manually w/ screwdriver

7/19 inserted directly through mucosa w/o7/19 inserted directly through mucosa w/o

any flap dissectionany flap dissection--used slow speed twist drill to drill into bone under irrigationused slow speed twist drill to drill into bone under irrigation

--used slow speedused slow speed handpiecehandpiece for screwing the screws into bonefor screwing the screws into bone


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Mucosal IncisionMucosal Incision


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Mucosa PunchMucosa Punch

Creates directCreates direct transmucosaltransmucosal access toaccess to

bonebone


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Insertion Directly Through MucosaInsertion Directly Through Mucosa


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Side NotesSide Notes

In situations where flapIn situations where flapwas raised, waited 8was raised, waited 8--1010

days before loading screwsdays before loading screws

to allow soft tissue healingto allow soft tissue healing

andand maintainancemaintainance of goodof goodOHOH

Loading accomplished byLoading accomplished by

superelasticsuperelastic NiTiNiTi coilcoil

springs, power chains, orsprings, power chains, or

elastic modules attachedelastic modules attachedto head ofto head of miniscrewminiscrew

SS over titanium becauseSS over titanium becauseease of handlingease of handling


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Clinical ExamplesClinical Examples

Intrusion andIntrusion and RetrusionRetrusion of anterior teeth withof anterior teeth withsuperelasticsuperelastic NiTiNiTi coil springs and elastics,coil springs and elastics,

respectivelyrespectively

M ill Ri ht Fi t M l I t iM ill Ri ht Fi t M l I t i


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Maxillary Right First Molar IntrusionMaxillary Right First Molar Intrusion

PretreatmentPretreatment


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Maxillary Right First Molar Intrusion:Maxillary Right First Molar Intrusion:

LoadingLoading


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Maxillary Right First Molar Intrusion:Maxillary Right First Molar Intrusion:

PostTreatmentPostTreatment


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Extrusion of Impacted Maxillary Right CanineExtrusion of Impacted Maxillary Right Canine


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PremolarPremolar DistalizationDistalization


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Protraction of Lower Right 2Protraction of Lower Right 2ndnd and 3and 3rdrd MolarsMolars

PretreatmentPretreatment


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LoadingLoading


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PostPost--TreatmentTreatment


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DiscussionDiscussion

MiniscrewsMiniscrews proved efficient in maintaining theproved efficient in maintaining thetype oftype of extradentalextradental anchorage required in severalanchorage required in several

different clinical situationsdifferent clinical situations

Apart from slight local irritation, neitherApart from slight local irritation, neitherdiscomfort nor allergicdiscomfort nor allergic rxnsrxns were reported bywere reported by

patientspatients

AllAll miniscrewsminiscrews were well accepted and toleratedwere well accepted and tolerated

throughoutthroughout txtx

Loosening of 3/19 screws occurred that couldLoosening of 3/19 screws occurred that couldhave been avoided with appropriate planninghave been avoided with appropriate planning


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ReferencesReferences

Costa et al.Costa et al. MiniscrewsMiniscrews asas

orthodontic anchorage: A preliminaryorthodontic anchorage: A preliminaryreport. Int. J. Adult Orthodontics andreport. Int. J. Adult Orthodontics andOrthognathicOrthognathic SxSx. 1998;13(2):201. 1998;13(2):201--99

FortiniFortini et al. Clinical Application andet al. Clinical Application and

Efficacy ofEfficacy of MiniscrewsMiniscrews forfor ExtradentalExtradentalAnchorage. Orthodontics. 2004;Anchorage. Orthodontics. 2004;1(2).1(2).


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