Serial extraction is an interceptive orthodontic procedure used to correct potential irregularities by extracting certain primary and permanent teeth in a planned sequence. This allows the remaining teeth to erupt into a better position. It was first described in 1929 and involves extracting teeth to guide others into normal occlusion. It is based on reducing tooth material if there is excess compared to arch length. By removing some teeth, others are guided into the extraction spaces by natural forces. It is indicated for class I malocclusions with arch length deficiencies and is carried out over 2-3 years by extracting teeth in stages to close extraction spaces gradually. Fixed appliances are usually needed after serial extractions to correct tooth angles and refine the bite.

1. Lama Al-Mashhrawi

2. SERIAL EXTRACTION
Serial extractionisaninterceptive orthodonticprocedure usuallyinitiatedinthe earlymixeddentition
whenone can recognize ananticipate potential irregularitiesinthe dentofacial complexandiscorrected
by a procedure thatincludesthe plannedextractionof certaindeciduousteethandlaterspecific
permanentteethinanorderlysequenceandpredeterminedpatterntoguide the eruptingpermanent
teethintoa more favourable position.
History
Kjellgrenin1929 usedthe termserial extractiontodescribe aprocedure where some deciduousteeth
followedbypermanentteethwere extractedtoguide the restof the teethintonormal occlusion.Nance
duringthe 1940's popularisedthistechniqueinthe UnitedStatesof Americaandtermedit'planned&
progressive extraction'.Hotzin1970 calledsucha procedure 'active supervisionof teethbyextraction
Rationale
Serial extractionisbasedontwobasicprinciples
a. Arch length - toothmaterial discrepancy:
Wheneverthere isanexcessof toothmaterial ascomparedtothe arch length,itisadvisable toreduce
the tooth material inordertoachieve stable results.Thisprinciple isutilizedinserial extraction
procedureswhere toothmaterial is reducedbyselective extractionof teethsothatthe restof the teeth
can be guidedtonormal occlusion.
b. Physiologictoothmovement:Humandentitionshowsaphysiologictendencytomove
towardsan extractionspace.Thusbyselective removal of some teeth the restof the teeth
whichare inthe processof eruptionare guidedbythe natural forcesintothe extraction
spaces.
Indications
Serial extractionisindicatedinthe followingcases:
1. ClassI malocclusionshowingharmonybetweenskeletal andmuscular system.
2. Arch lengthdeficiencyascomparedtothe tooth material isthe mostimportantindicationforserial
extraction.Archlengthdeficiencyisindicatedbythe presence of one ormore of the followingfeatures:
a. Absence of physiologicspacing
b. Unilateral orbilateral premature lossof deciduouscanineswithmidline shift
c. Malpositionedorimpactedlateralincisorsthateruptpalatallyoutof the arch
d. Markedlyirregularorcrowdedupperandloweranteriors
e. Localizedgingival recessioninthe loweranteriorregionisacharacteristicfeature of
arch lengthdeficiency
f. Ectopic eruptionof teeth
g. Mesial migrationof buccal segment
h. Abnormal eruptionpattern&sequence
i. Loweranteriorflaring

3. j. Ankylosisof one ormore teeth
3. Where growthis not enoughto overcome the discrepancybetweentoothmaterial andbasal bone
4. Patientswithstraightprofile andpleasingappearance
Contra-indicationsofserial extraction
Serial extractionsare contra-indicatedinanumberof conditionsthatinclude:
1. ClassII & IIImalocclusionwithskeletal abnormalities
2. Spaceddentition
3. Anodontia/oligodontia
4. Openbite and deepbite
5. Midline diastema
6. ClassI malocclusionswithminimal space deficiency
7. Uneruptedmalformedteethe.g.dilaceration
8. Extensive cariesorheavilyfilledfirstpermanentmolars
9. Mild disproportionbetweenarchlengthandtoothmaterial thatcan be treatedbyproximal stripping
Advantages of serial extraction
Serial extractioncarriedoutduringthe mixeddentitionandearlypermanentdentitionperiodshasa
numberof advantages:
a. Treatmentismore physiologicasit involvesguidance of teethintonormal positionsmakinguse of the
physiologicforces.
b. Psychological traumaassociatedwithmalocclusioncanbe avoidedbytreatmentof the malocclusion
at an earlyage.
c. It eliminatesorreducesthe durationof multibandedfixedtreatment.
d. Betteroral hygiene ispossible therebyreducingthe riskof caries.
e.Healthof investingtissuesispreserved.
f.Lesserretentionperiodis indicatedatthe completionof treatment.
g. More stable resultsobtainedasthe toothmaterial andarch lengthare in harmony.
Disadvantages of serial extraction
a. Serial extractionrequiresclinical judgement.There isnosingleapproachthatcan be universally
appliedtoall patients.Eachpatienthasto be assessedanda suitable extractiontimetableplanned.
b. Treatmenttime isprolongedasthe treatmentiscarriedoutinstagesspreadover2-3 years.

4. c. It requiresthe patienttovisitthe dentist often.Thuspatientco-operationisneeded.
d. Asextractionspacesare createdthat close gradually,the patienthasatendencyof developingtongue
thrust.
e.Extractionof the buccal teethcan resultindeepeningof the bite.
f.If the proceduresare not carriedoutproperlythere isa riskof arch lengthreducingbymesial
migrationof the buccal segment.Thusapoorlyexecutedserial extractionprogramme canbe worse
than none at all.
g. Ditchingor space can existbetweenthe canine andsecondpremolar
h. The axial inclinationof teethatthe terminationof the serial extractionproceduremayrequire
correction.Thisnecessitatesshorttermfixedappliancetherapy.
Diagnostic procedure
The diagnosticexercisepriortotreatmentshouldinvolve comprehensiveassessmentof the dental,
skeletal andsofttissues.A toothmaterial - arch lengthdiscrepancymustideallyexist.Accordingtomost
authors,an arch lengthdeficiencyof notlessthan5 - 7 mm shouldexisttoundertake thisprocedure.
Study model analysisshouldbe carriedoutto determinethe archlengthdiscrepancy:Carey'sanalysisin
the lowerarch and arch perimeteranalysisinthe upperarchshouldbe carriedout.Mixeddentition
analysishelpsindeterminingthe space requiredforthe eruptingbuccal teeth.The eruptionstatusof
the dentitionisevaluatedfromanO.P.G.
The skeletal tissue assessmentshouldinvolvecomprehensive cephalometricexaminationtostudythe
underlyingskeletal relation.Serial extractionproducesthe best resultsinaClassIskeletal pattern.
Presence of aClassII or a ClassIIIskeletal patternare contraindicationsforserial extraction
procedure
The soft tissue assessmentbyclinical examinationandcephalogramshelpinthe diagnosis.Serial
extractionisgenerallyundertakeninpatientsexhibitingharmonioussofttissue pattern.
A numberof methodsorsequencesof extractionhave beendescribed.Three of the popularmethods
are:
1. Dewel'smethod
2. Tweed'smethod
3. Nance method
Dewel'smethod:Dewel hasproposeda3stepserial extractionprocedure.Inthe firststepthe
deciduouscaninesare extractedtocreate space forthe alignmentof the incisors.
Thisstepis carriedout at 8-9 years of age.A year later,the deciduousfirstmolarsare extracted sothat
the eruptionof firstpremolarsisaccelerated.Thisisfollowedbythe extractionof the eruptingfirst
premolarstopermitthe permanentcaninestoeruptintheirplace.

5. In some casesa modifiedDewel'stechnique isfollowedwhereinthe firstpremolarsare enucleatedat
the time of extractionof the firstdeciduousmolars.Thisisfrequentlynecessaryinthe mandibulararch
where the caninesofteneruptbeforethe firstpremolars.
Tweed'smethod:Thismethodinvolvesthe extractionof the deciduousfirstmolarsaround8yearsof
age.This isfollowedbythe extractionof the firstpremolarsandthe deciduouscaninessimultaneously.
Nance method:Thisis similartothe Tweed'stechniqueandinvolvesthe extractionof the deciduous
firstmolarsfollowedbythe extractionof the firstpremolarsandthe deciduouscanines.
Post serial extraction fixedtherapy
Most cases of serial extractionneedfixedappliance therapyforthe correctionof axial inclinationand
detailingof the occlusion.