extraction in orthodontics

EXTRACTION IN ORTHODONTICSEXTRACTION IN ORTHODONTICS
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EXTRACTION S IN ORTHODONTICSEXTRACTION S IN ORTHODONTICS
INTRODUCTIONINTRODUCTION
EXTRACTION PROCEDURESEXTRACTION PROCEDURES
– BALANCING EXTRACTIONBALANCING EXTRACTION
– COMPENSATING EXTRACTIONCOMPENSATING EXTRACTION
– PHASED EXTRACTIONPHASED EXTRACTION
– ENFORCED EXTRACTIONENFORCED EXTRACTION
– WILKINSON EXTRACTIONWILKINSON EXTRACTION
– THERAPEUTIC EXTRACTIONTHERAPEUTIC EXTRACTION
– SERIAL EXTRACTIONSERIAL EXTRACTION
DEWEL’S METHODDEWEL’S METHOD
TWEED’S METHODTWEED’S METHOD
NANCE’S METHODNANCE’S METHOD
CRITERIA FOR EXTRACTIONCRITERIA FOR EXTRACTION
INCISOR EXTRACTIONINCISOR EXTRACTION
CANINE EXTRACTIONCANINE EXTRACTION
MOLAR EXTRACTIONMOLAR EXTRACTION
CAMOUFLAGECAMOUFLAGE
EXTRACTION FOR SURGICAL ORTHODONTICSEXTRACTION FOR SURGICAL ORTHODONTICS
SUMMARY AND CONCLUSIONSUMMARY AND CONCLUSION
BIBLIOGRAPHYBIBLIOGRAPHY

INRTODUCTIONINRTODUCTION
The philosophy of extraction related to the orthodontic treatment is not new.The philosophy of extraction related to the orthodontic treatment is not new.
Establishment of normal functional occlusion in balancing with supportingEstablishment of normal functional occlusion in balancing with supporting
structures occasionally requires the reduction of one or more teeth.structures occasionally requires the reduction of one or more teeth.
Most extractions are performed as part of a general plan of orthodontic treatment.Most extractions are performed as part of a general plan of orthodontic treatment.
TheThe nature of malocclusionnature of malocclusion and theand the age of the patientage of the patient is an important factor inis an important factor in
deciding whether the extraction is needed or not needed.deciding whether the extraction is needed or not needed.
To extract or not has always been a controversial in orthodonticsTo extract or not has always been a controversial in orthodontics
In orthodontics there areIn orthodontics there are two major reasonstwo major reasons for extraction needfor extraction need
1. To provide space to align the teeth in presence of severe crowding1. To provide space to align the teeth in presence of severe crowding
2. To allow teeth to be retracted so protrusion can be reduced or skeletal2. To allow teeth to be retracted so protrusion can be reduced or skeletal
Class II or class III problems can be camouflaged (anterior-posterior relationship)Class II or class III problems can be camouflaged (anterior-posterior relationship)
In orthodontics extractions include serial extraction as an interceptive procedureIn orthodontics extractions include serial extraction as an interceptive procedure
and therapeutic extraction as a space gaining procedure.and therapeutic extraction as a space gaining procedure.

HISTORICAL BACKGROUNDHISTORICAL BACKGROUND
The question of tooth removal has been a controversial subject since theThe question of tooth removal has been a controversial subject since the EdwardEdward
AngleAngle (Non-extraction) and his student(Non-extraction) and his student Calvin. S. CaseCalvin. S. Case (Extraction) debate in early(Extraction) debate in early
1905.1905.
The role of extractions in orthodontics was recognized byThe role of extractions in orthodontics was recognized by John HunterJohn Hunter in 1771 inin 1771 in
his natural history of the teeth.his natural history of the teeth.
SpoonerSpooner in 1839 advised the extraction of 4 premolars or 1st molars whenin 1839 advised the extraction of 4 premolars or 1st molars when
defective.defective.
FarrarFarrar in 1888 considered judicious extractions an essential requisite “in 1888 considered judicious extractions an essential requisite “For theFor the
prevention & correction of irregularities”.prevention & correction of irregularities”. He recognized that indiscriminateHe recognized that indiscriminate
extraction mayextraction may “create a new difficulty while removing the original one”.“create a new difficulty while removing the original one”.

PiercePierce,, writing in the Dental Cosmos in 1859, advocated extraction in tooth crowdingwriting in the Dental Cosmos in 1859, advocated extraction in tooth crowding
as a means for simplifying orthodontic procedure.as a means for simplifying orthodontic procedure.
AngleAngle also advocated extraction to avoid “collapse” & to improve facial appearancealso advocated extraction to avoid “collapse” & to improve facial appearance
Considerations for extractions according to Angle in class I malocclusion were
 Where jaws are small either due to the arrested development whereby there is an
increase in the angles of inclination i.e. the procumbency of incisors.
 Where extraction is necessary from the requirements of the facial lines for the
developments of the arches such as to afford room for malposed teeth.
 He advocated the choice of extraction of 1st or 2nd PM usually but some 1st molars if
affected by caries & few lateral incisors.

Angle in class II div1Angle in class II div1 and its subdivision he advised extraction of one PMand its subdivision he advised extraction of one PM
preferably 1st frompreferably 1st from each half to establish harmony in size of the arches & improveeach half to establish harmony in size of the arches & improve
occlusion.occlusion.
Although he was against extraction of 1st molars, canines, lateral incisors, heAlthough he was against extraction of 1st molars, canines, lateral incisors, he
advocated 1st PM extraction in class III malocclusions except when there is lingualadvocated 1st PM extraction in class III malocclusions except when there is lingual
inclination of incisor & canine teeth.inclination of incisor & canine teeth.
At the1911 meetingAt the1911 meeting Calvin. S. CaseCalvin. S. Case presented an article “presented an article “The question ofThe question of
extraction in orthodontia”extraction in orthodontia” which was followed by discussions bywhich was followed by discussions by Mathew. H .Cryer,Mathew. H .Cryer,
Martin Dewey, H. Clay Ferris, J. P. Buckley, G. F. Bowman and Thomas P.Martin Dewey, H. Clay Ferris, J. P. Buckley, G. F. Bowman and Thomas P.
Hinnman. (Case’s-Rational school and Angle’s-New school)Hinnman. (Case’s-Rational school and Angle’s-New school)

According toAccording to Calvin. S. Case’sCalvin. S. Case’s observations in 1921, he stated that aligningobservations in 1921, he stated that aligning
malposed teeth without extraction might markedly affect stability.malposed teeth without extraction might markedly affect stability.
MargolisMargolis in 1943 stated that the most effective extraction strategy to relievein 1943 stated that the most effective extraction strategy to relieve
crowding is to extract PM’s closest to the site of crowding.crowding is to extract PM’s closest to the site of crowding.
In 1945,In 1945, TweedTweed found that, a group of patient he treated without extraction showedfound that, a group of patient he treated without extraction showed
a great tendency towards dental collapse and he was unhappy with the faces hea great tendency towards dental collapse and he was unhappy with the faces he
was producing. Later the idea of treating the patient with extractions formed thewas producing. Later the idea of treating the patient with extractions formed the
basis of his further work.basis of his further work.
By early 1960’s more than half of the orthodontic patients had extractions of someBy early 1960’s more than half of the orthodontic patients had extractions of some
teeth, usually but not always the 1teeth, usually but not always the 1stst
PM’s.PM’s.

Types of extractionsTypes of extractions
– Balancing extractionBalancing extraction
– Compensating extractionCompensating extraction
– Phased extractionPhased extraction
– Enforced extractionEnforced extraction
– Wilkinson extractionWilkinson extraction
– Therapeutic extractionTherapeutic extraction
– Serial extractionSerial extraction

Wilkinson extraction:Wilkinson extraction:
Wilkinson advocated extraction of all 1st permanent molars between the ageWilkinson advocated extraction of all 1st permanent molars between the age
of 8 1/2 - 9 1/2 years. This was on the fact that these teeth are moreof 8 1/2 - 9 1/2 years. This was on the fact that these teeth are more
susceptible to caries. And othersusceptible to caries. And other benefitsbenefits of extracting these teeth at an earlyof extracting these teeth at an early
age are:-age are:-
Extraction provide space for eruption of the 3rd molars therebyExtraction provide space for eruption of the 3rd molars thereby
impaction be avoidedimpaction be avoided
In general crowding in the arch is minimized. Thus other teeth are atIn general crowding in the arch is minimized. Thus other teeth are at
lower risk caries.lower risk caries.
Drawback:Drawback:--
The 2nd PM and 2nd Molars rotate and tip mesially into theThe 2nd PM and 2nd Molars rotate and tip mesially into the
extraction spaceextraction space
Removal of these teeth will deprive the anchorage needRemoval of these teeth will deprive the anchorage need
It offers limited space to relieve crowdingIt offers limited space to relieve crowding

Serial ExtractionSerial Extraction
Interceptive orthodonticsInterceptive orthodontics

Early mixed dentitionEarly mixed dentition

Recognize & anticipate potential irregularitiesRecognize & anticipate potential irregularities

Corrected by planned extraction (guidance of eruption)Corrected by planned extraction (guidance of eruption)

Certain deciduous & permanent teethCertain deciduous & permanent teeth

Pre-determined patternPre-determined pattern

Guiding erupting teethGuiding erupting teeth

Favorable positionFavorable position

Serial extraction was described for first time bySerial extraction was described for first time by BunonBunon (1743) about 250 yrs ago(1743) about 250 yrs ago
in his book “Essay on diseases of the teeth”.in his book “Essay on diseases of the teeth”.
Joseph FoxJoseph Fox (1814) mentions in his text publication that “In cases of discrepancy,(1814) mentions in his text publication that “In cases of discrepancy,
the removal of the temporary cuspids is absolutely necessary & unless operatedthe removal of the temporary cuspids is absolutely necessary & unless operated
upon timely, the irregularity is difficult remedied”.upon timely, the irregularity is difficult remedied”.
Similar views were expressed bySimilar views were expressed by LecluseLecluse (1754).(1754). BourdetBourdet (1757),(1757), HunterHunter (1771),(1771),
DewelDewel (1817),(1817), RobinsonRobinson (1846),(1846), Chapin HarrisChapin Harris (1855) & others(1855) & others
The word serial extraction was termed byThe word serial extraction was termed by KjellgrenKjellgren (1929) & he defined it as a(1929) & he defined it as a
treatment procedure in the mixed dentition for thetreatment procedure in the mixed dentition for the prevention of malocclusionprevention of malocclusion & to& to
facilitate the alignmentfacilitate the alignment of the permanent teeth.of the permanent teeth.
This procedure was popularized byThis procedure was popularized by NanceNance in 1940.in 1940.
In 1970In 1970 HotzHotz referred the procedure as guidance of eruptionreferred the procedure as guidance of eruption

Clinical symptoms of an authentic serial extraction includeClinical symptoms of an authentic serial extraction include
 Markedly irregular anterior teethMarkedly irregular anterior teeth
 Premature loss of one or more of the deciduous caninesPremature loss of one or more of the deciduous canines
 Various median line deviationVarious median line deviation
 Impacted or displaced lateral incisorsImpacted or displaced lateral incisors
 Gross reduction in arch length andGross reduction in arch length and
 Frequently gingival recession and alveolar destruction along the labial surface ofFrequently gingival recession and alveolar destruction along the labial surface of
one or both lower central incisorsone or both lower central incisors

InIn moderate borderlinemoderate borderline malocclusion in the mixed dentition that arouses themalocclusion in the mixed dentition that arouses the
greatest apprehension on the part of orthodontist considering a serial extractiongreatest apprehension on the part of orthodontist considering a serial extraction
diagnosis.diagnosis.
It can be described as neither a true extraction case nor non-extraction category.It can be described as neither a true extraction case nor non-extraction category.
Experiences occasionally dictates that a decision be made b/w moderate spacingExperiences occasionally dictates that a decision be made b/w moderate spacing
with extraction or slight crowding without extraction, with the balance in favor of thewith extraction or slight crowding without extraction, with the balance in favor of the
latter.latter.
Each borderline case has to be decided on theEach borderline case has to be decided on the character of malocclusioncharacter of malocclusion and whatand what
ultimately will be in theultimately will be in the best interest of each individual patient.best interest of each individual patient.

Prerequisites in serial extraction:Prerequisites in serial extraction:
 Diagnostic prerequisites in serial extractionDiagnostic prerequisites in serial extraction
 Conventional and alternative serial extraction sequenceConventional and alternative serial extraction sequence::
 Borderline characteristicsBorderline characteristics
 Esthetics, cephalometrics and skeletal considerationsEsthetics, cephalometrics and skeletal considerations
 Orthodontic treatment requirementsOrthodontic treatment requirements

1.1. Diagnostic prerequisites in serial extractionDiagnostic prerequisites in serial extraction::
 A preciseA precise arch-length analysisarch-length analysis is an essential part of diagnosis.is an essential part of diagnosis.
 Lower incisor positionLower incisor position
 Arch length calculations, are more conclusive in the lower arch than inArch length calculations, are more conclusive in the lower arch than in
the upper arch for the simple reason that it is more difficult to recoverthe upper arch for the simple reason that it is more difficult to recover
lost space in the lower arch than in the upper arch. This means that iflost space in the lower arch than in the upper arch. This means that if
the irregularity can be corrected without extraction in the lower arch,the irregularity can be corrected without extraction in the lower arch,
then it ordinarily can be corrected without extraction in the upper arch.then it ordinarily can be corrected without extraction in the upper arch.

2.2. Conventional and alternative serial extraction sequenceConventional and alternative serial extraction sequence::
In theIn the authenticauthentic arch reduction, preliminary interception and correction by serialarch reduction, preliminary interception and correction by serial
extraction are accomplished inextraction are accomplished in three separate stagesthree separate stages for three purposes:for three purposes:
 CC  provides space for incisors correctionprovides space for incisors correction
 DD  permits early eruptions of 1permits early eruptions of 1stst
PMPM
 11stst
PMPM  permits eruptions of permanent canine into favorable positionpermits eruptions of permanent canine into favorable position
The time interval b/w extraction varies fromThe time interval b/w extraction varies from 6-15 months6-15 months
The objective is to permit a measure of self –correction by reconcilingThe objective is to permit a measure of self –correction by reconciling
differences b/w total tooth material and potential supporting bonedifferences b/w total tooth material and potential supporting bone
In both conventional and alternative serial extraction methods, activeIn both conventional and alternative serial extraction methods, active
orthodontic treatment ordinarily is delayed in class I malocclusion until theorthodontic treatment ordinarily is delayed in class I malocclusion until the
eruption of permanent canineseruption of permanent canines

AnAn alternative in serial extractionalternative in serial extraction is in reversing the removal of two deciduous teeth.is in reversing the removal of two deciduous teeth.
((In borderline cases the 1st deciduous molars are removed before deciduousIn borderline cases the 1st deciduous molars are removed before deciduous
canines )canines )
– indicated in borderline casesindicated in borderline cases
– both deciduous canines must be presentboth deciduous canines must be present
– arch length loss should be moderatearch length loss should be moderate
– none of the incisors should be severely malposed or impactednone of the incisors should be severely malposed or impacted
– 22ndnd
deciduous molars should be sturdy enough to remain in position for several yearsdeciduous molars should be sturdy enough to remain in position for several years
– there should be no gingival recession along the labial surface of lower incisorsthere should be no gingival recession along the labial surface of lower incisors
– deciduous canines are given priority in conventional extraction sequence because ofdeciduous canines are given priority in conventional extraction sequence because of
greater deficiency in arch length and because of undesirable migration of incisors into lostgreater deficiency in arch length and because of undesirable migration of incisors into lost
canine spacecanine space
for this reasons orthodontist must differentiate b/w authentic serial extraction andfor this reasons orthodontist must differentiate b/w authentic serial extraction and
borderline irregularity before he embarks on any protocol of extractionsborderline irregularity before he embarks on any protocol of extractions

3.3. Borderline characteristicsBorderline characteristics
– have good facial patternshave good facial patterns
– moderate loss of arch lengthmoderate loss of arch length
– good muscular environmentgood muscular environment
– satisfactory direction of skeletal growthsatisfactory direction of skeletal growth
In these cases current controversy lies and until it is resolved , no irrevocableIn these cases current controversy lies and until it is resolved , no irrevocable
action should be taken.action should be taken.
The proper course is to secure all possible diagnostic records and then to placeThe proper course is to secure all possible diagnostic records and then to place
the patient under observation to determine whether his individual growth trend willthe patient under observation to determine whether his individual growth trend will
make it possible for him to retain all of the teeth.make it possible for him to retain all of the teeth.
IfIf growth is goodgrowth is good, patient can be placed under full treatment without extraction, patient can be placed under full treatment without extraction
IfIf growth is questionablegrowth is questionable, further development will not be seriously jeopardized by, further development will not be seriously jeopardized by
extraction of 1st deciduous molars.extraction of 1st deciduous molars.
IfIf growth unexpectedly takes a favorable turngrowth unexpectedly takes a favorable turn, comphrensive treatment with a full, comphrensive treatment with a full
complement of teeth can still be undertaken.complement of teeth can still be undertaken.
IfIf still growth is inadequatestill growth is inadequate ,there is ample of time to proceed with the rest of the,there is ample of time to proceed with the rest of the
serial extraction program involving removal of deciduous canines and 1st PMserial extraction program involving removal of deciduous canines and 1st PM

4. Esthetics, cephalometrics and skeletal considerations4. Esthetics, cephalometrics and skeletal considerations
i.i. Esthetics is not a problem in early stagesEsthetics is not a problem in early stages
– InIn class I casesclass I cases, facial contours are still acceptable and the alignment of teeth usually, facial contours are still acceptable and the alignment of teeth usually
shows no marked irregularity until the eruption of the permanent canines.shows no marked irregularity until the eruption of the permanent canines.
– InIn bimaxillary protrusions with poor skeletal patternsbimaxillary protrusions with poor skeletal patterns, disturbed facial musculature are, disturbed facial musculature are
concern with facial esthetics as they are with occlusal relations.concern with facial esthetics as they are with occlusal relations.
– InIn class II casesclass II cases usually involve skeletal problems that require concurrent orthodonticusually involve skeletal problems that require concurrent orthodontic
treatment and serial extraction (accessory to or) alone will not bring about anytreatment and serial extraction (accessory to or) alone will not bring about any
improvement in the supporting structures or in the 1st molar occlusion.improvement in the supporting structures or in the 1st molar occlusion.
ii.ii. CephalometricallyCephalometrically, the typical, the typical
– class I, serial extraction presents a facial pattern that can best be described as flat orclass I, serial extraction presents a facial pattern that can best be described as flat or
straight.straight.
– InIn bimaxillary protrusionbimaxillary protrusion, the entire mass seems to occupy a wide area in the lower half of, the entire mass seems to occupy a wide area in the lower half of
the face.the face.

InIn protrusive casesprotrusive cases, the incisors show a distinct anterior displacement when related to, the incisors show a distinct anterior displacement when related to
the facial plane , as represented by N-Pog line. The incisors not only labiallythe facial plane , as represented by N-Pog line. The incisors not only labially
displaced but they also have an increased labial inclination.displaced but they also have an increased labial inclination.
In authentic serial extraction casesIn authentic serial extraction cases, it is apparent cephalometrically that the incisors, it is apparent cephalometrically that the incisors
cannot be moved labially without displacing them beyond the limits of supportingcannot be moved labially without displacing them beyond the limits of supporting
bone. Nor is it possible to gain the width of a PM by distal movement of the molars;bone. Nor is it possible to gain the width of a PM by distal movement of the molars;
on their eruption, the second molars will require all the space that further posterioron their eruption, the second molars will require all the space that further posterior
development will provide, thus in conservative treatment procedure in the authenticdevelopment will provide, thus in conservative treatment procedure in the authentic
serial extraction cases is to remove selected premolars the areas of greatestserial extraction cases is to remove selected premolars the areas of greatest
concentration and to repositioning the remaining teeth in a normal alignment over theconcentration and to repositioning the remaining teeth in a normal alignment over the
available basal bone.available basal bone.

iii. as the serial extraction procedure that requires great caution and restraintiii. as the serial extraction procedure that requires great caution and restraint
because it involvesbecause it involves prediction of growthprediction of growth..
5.Orthodontic treatment requirements5.Orthodontic treatment requirements
One of theOne of the misconceptions of serial extractionmisconceptions of serial extraction is that the procedure, in itself,is that the procedure, in itself,
will ensure a satisfactory esthetic and functional correction. But to thewill ensure a satisfactory esthetic and functional correction. But to the
contrary, the fully corrective serial extraction cases is most unusual, insteadcontrary, the fully corrective serial extraction cases is most unusual, instead
majority of cases require comprehensive orthodontic treatment to close themajority of cases require comprehensive orthodontic treatment to close the
spaces, open the bite, upright the teeth on either side of the extraction sitesspaces, open the bite, upright the teeth on either side of the extraction sites
and realign rotated and malposed incisors and canines.and realign rotated and malposed incisors and canines.

Indications:Indications:
– Depends on M-D crown width (CDE & 345)Depends on M-D crown width (CDE & 345)
– Crowding of the incisor teeth, premature loss of one or some deciduous caninesCrowding of the incisor teeth, premature loss of one or some deciduous canines
& midline deviations.& midline deviations.
– GrowthGrowth should be watched to determine whether there will eventually beshould be watched to determine whether there will eventually be
sufficient room for all of the teeth in the arch without resorting to any extractions.sufficient room for all of the teeth in the arch without resorting to any extractions.
– TheThe relative positionrelative position 3 & 4 should be ascertained before extractions are3 & 4 should be ascertained before extractions are
undertakenundertaken
– Abnormal primary canineAbnormal primary canine root resorptionroot resorption

– When radiographic examination shows thatWhen radiographic examination shows that canines might erupt before the 1stcanines might erupt before the 1st
PM,PM, Dewel advises extraction of the 1st deciduous molars before extracting theDewel advises extraction of the 1st deciduous molars before extracting the
deciduous canines to prevent the canines from erupting before the 1st PM. If thedeciduous canines to prevent the canines from erupting before the 1st PM. If the
canines are permitted to erupt 1st , there maybe impaction of 1st PM. However,canines are permitted to erupt 1st , there maybe impaction of 1st PM. However,
early 1st deciduous molar extraction is not always followed by early 1st PMearly 1st deciduous molar extraction is not always followed by early 1st PM
extraction.extraction.
– The permanent canines may showThe permanent canines may show lingual / labial eruptionlingual / labial eruption to the deciduousto the deciduous
canines.canines.
– Class I withClass I with anterior crowdinganterior crowding (space discrepancy of 10 mm).(space discrepancy of 10 mm).

Contraindication:Contraindication:
– Class I malocclusion with mild to moderate crowding & space deficiencyClass I malocclusion with mild to moderate crowding & space deficiency
– Class III and class II div 2 malocclusionClass III and class II div 2 malocclusion
– When oligodontia or other deficiencies of teeth are present.When oligodontia or other deficiencies of teeth are present.
– In midline diastema and deep bite casesIn midline diastema and deep bite cases
– Where fixed appliance cannot be used to avoid arch collapse.Where fixed appliance cannot be used to avoid arch collapse.
– Cleft lip and palate casesCleft lip and palate cases
– Where extensive caries of permanent first molars requires their removal.Where extensive caries of permanent first molars requires their removal.
NOTENOTE
– They must be class I molar relation on both sidesThey must be class I molar relation on both sides
– Facial skeletal relation must be balanced anterio - posteriorly, verticallyFacial skeletal relation must be balanced anterio - posteriorly, vertically
– Discrepancy should be at least 5mm in all the quadrantsDiscrepancy should be at least 5mm in all the quadrants
– Dental midline should be coincidingDental midline should be coinciding
– Their must be neither open nor closed bite.Their must be neither open nor closed bite.

Timing of extraction:Timing of extraction:
– It is not possible to predict the exact time of tooth emergence from the root lengthIt is not possible to predict the exact time of tooth emergence from the root length
of the teeth or from skeletal age.of the teeth or from skeletal age.
– Deciduous 1st molarsDeciduous 1st molars should not be extractedshould not be extracted before one halfbefore one half of the succeedingof the succeeding
PM root is attained.PM root is attained.
– Deciduous caninesDeciduous canines shouldshould not benot be extracted before the permanent canine hasextracted before the permanent canine has
attainedattained one half ofone half of its root length, excepting when the oncoming 1st PM is aboutits root length, excepting when the oncoming 1st PM is about
to emerge ahead of the canine.to emerge ahead of the canine.
– A relatively rapid elongation of the roots of the PM & canines occurs soon afterA relatively rapid elongation of the roots of the PM & canines occurs soon after
the tooth comes through the alveolar mucosa into the mouth.the tooth comes through the alveolar mucosa into the mouth.
– By taking into the consideration theBy taking into the consideration the amount of root formationamount of root formation of the canines &of the canines &
PM’s, thePM’s, the unresorbed portionunresorbed portion of the deciduous lateral incisors themselves, someof the deciduous lateral incisors themselves, some
idea will be obtainedidea will be obtained  amount of tooth development that is still required untilamount of tooth development that is still required until
about one half to 3 quarters of the permanent tooth roots will be developedabout one half to 3 quarters of the permanent tooth roots will be developed

Various methods of serial extractions:Various methods of serial extractions:
Dewel methodDewel method (CD4)(CD4)
Tweed’s methodTweed’s method (D4C)(D4C)
Nance methodNance method (D4C)(D4C)

– Dewel method: (CD4)Dewel method: (CD4)
– He describes inHe describes in 3 stages3 stages
– Early extraction of deciduous canines to provide space for the incisors toEarly extraction of deciduous canines to provide space for the incisors to
assume correct position/alignmentassume correct position/alignment
– Extraction of 1st deciduous molars to permit early eruption of the 1st PMExtraction of 1st deciduous molars to permit early eruption of the 1st PM
– Extraction of 1st PM to allow canines to erupt in that place of formerly occupiedExtraction of 1st PM to allow canines to erupt in that place of formerly occupied
by 1st PMby 1st PM
– The intervals b/w these stages and the sequence of eruption vary withThe intervals b/w these stages and the sequence of eruption vary with
individual patient from 6 months to 1 year. Teeth should not be extractedindividual patient from 6 months to 1 year. Teeth should not be extracted
without observing the patient at intervals of 2-3 months to ascertain whetherwithout observing the patient at intervals of 2-3 months to ascertain whether
favorable growth will manifest itself.favorable growth will manifest itself.

– Tweed’s Method (D4C)Tweed’s Method (D4C)
According to Tweed, when diagnosis shows that aAccording to Tweed, when diagnosis shows that a discrepancy exists b/w toothdiscrepancy exists b/w tooth
and basal bone & that the patient is b/w the age of 7 1/2 --8 1/2 years, serialand basal bone & that the patient is b/w the age of 7 1/2 --8 1/2 years, serial
extraction is performed as followsextraction is performed as follows
At the age of 8 years, all four deciduous 1stmolars are extracted.At the age of 8 years, all four deciduous 1stmolars are extracted.
If the mandibular permanent incisors are not blocked out or severely crowed, theIf the mandibular permanent incisors are not blocked out or severely crowed, the
deciduous canines are maintained in position so that eruption of the permanentdeciduous canines are maintained in position so that eruption of the permanent
canines will not be hastenedcanines will not be hastened
When the 1st PM teeth erupt or about the level of the crest of the alveolar mucosaWhen the 1st PM teeth erupt or about the level of the crest of the alveolar mucosa
they are extracted and the deciduous canines are also extracted at this time.they are extracted and the deciduous canines are also extracted at this time.

If the 1st PM are extracted 4-6 months prior to eruption of the permanent canines,If the 1st PM are extracted 4-6 months prior to eruption of the permanent canines,
the permanent canines usually will shift posteriorly and erupt in the space left bythe permanent canines usually will shift posteriorly and erupt in the space left by
extracted 1st PM. The irregularities of the mandibular incisors are not severe, showextracted 1st PM. The irregularities of the mandibular incisors are not severe, show
self correction.self correction.
The 2nd deciduous molars should me maintained in the arch to prevent mesializingThe 2nd deciduous molars should me maintained in the arch to prevent mesializing
and inclining of 1st permanent molars.and inclining of 1st permanent molars.

– Nance’s Method: (D4C)Nance’s Method: (D4C)
It is similar to the Tweeds method and involves the extraction of the deciduous 1stIt is similar to the Tweeds method and involves the extraction of the deciduous 1st
molars followed by 1st PM and deciduous caninesmolars followed by 1st PM and deciduous canines
When determining whether sufficient space will be available to accommodate theWhen determining whether sufficient space will be available to accommodate the
permanent teeth in normal alignment from permanent 1st molar, on one side topermanent teeth in normal alignment from permanent 1st molar, on one side to
permanent 1st molar on the other side, Nance gave consideration to the amount ofpermanent 1st molar on the other side, Nance gave consideration to the amount of
Leeway Space, the severity and amount of tooth crowding, labial tipping of theLeeway Space, the severity and amount of tooth crowding, labial tipping of the
permanent incisors in the mandibular arch and the occlusal relationship of thepermanent incisors in the mandibular arch and the occlusal relationship of the
permanent 1st molars.permanent 1st molars.
Measurements by Nance showed that the difference of leeway space may varyMeasurements by Nance showed that the difference of leeway space may vary
from 0-4 mm b/w the deciduous and permanent teeth.from 0-4 mm b/w the deciduous and permanent teeth.

He established a method to determine the relative M-D widths of the deciduous andHe established a method to determine the relative M-D widths of the deciduous and
permanent teeth in mixed dentition by measuring the M-D widths of the deciduouspermanent teeth in mixed dentition by measuring the M-D widths of the deciduous
molars & the deciduous canine to that of the PM’s & permanent canines. Themolars & the deciduous canine to that of the PM’s & permanent canines. The
difference b/w the deciduous and permanent teeth give the Leeway space on onedifference b/w the deciduous and permanent teeth give the Leeway space on one
sideside
He also obtained the following measurements from the mandibular cast in the mixedHe also obtained the following measurements from the mandibular cast in the mixed
dentition by measuring the outside or perimeter of the arch from M-B surface to M-Bdentition by measuring the outside or perimeter of the arch from M-B surface to M-B
surface of the permanent 1st molars by using 0.010 inch ligature wire.surface of the permanent 1st molars by using 0.010 inch ligature wire.
Using dividers, he also obtained the measurement from the M-L surface of theUsing dividers, he also obtained the measurement from the M-L surface of the
permanent 1st molar to the apex of the interdental papillae b/w the mandibularpermanent 1st molar to the apex of the interdental papillae b/w the mandibular
incisors. This is the inside measurement.incisors. This is the inside measurement.

Criteria for ExtractionCriteria for Extraction
A.A.
– Arch length to tooth material discrepancyArch length to tooth material discrepancy
– Type of alveolar processType of alveolar process
– gonial anglegonial angle
– Axial inclinationAxial inclination
– Correction of sagittal inter-arch relationshipCorrection of sagittal inter-arch relationship
– Abnormal size and form of teethAbnormal size and form of teeth
– Skeletal jaw malrelationsSkeletal jaw malrelations
– Need for facial profile alterationNeed for facial profile alteration
B.B. Dental VariablesDental Variables::
– Dental discrepancyDental discrepancy
– Curve of SpeeCurve of Spee
– Bolton discrepancyBolton discrepancy
– Peck & Peck indexPeck & Peck index
– Irregularity indexIrregularity index
C.C. Cephalometric VariablesCephalometric Variables
– Relation of the horizontal planesRelation of the horizontal planes
– Frankfort mandibular plane angleFrankfort mandibular plane angle
– SN-Mandibular plane angleSN-Mandibular plane angle
– Proportion of PFH to AFHProportion of PFH to AFH
– IMPAIMPA
– FMIAFMIA
– Distance b/w lower incisor to A Pog lineDistance b/w lower incisor to A Pog line
D.D. Facial variablesFacial variables
– Distance b/w the E-line to Lower lipDistance b/w the E-line to Lower lip
– Distance b/w the B-line to Lower lipDistance b/w the B-line to Lower lip
– N-L angleN-L angle
– Upper lip morphologyUpper lip morphology
– Dental midline deviationDental midline deviation
E.E. Growth statusGrowth status

Arch length to tooth material discrepancyArch length to tooth material discrepancy ::
– Ideally the arch length & tooth material should be in harmony with each otherIdeally the arch length & tooth material should be in harmony with each other
– The size of the dentition & arch length are usually genetically determined. The presence ofThe size of the dentition & arch length are usually genetically determined. The presence of
the tooth material in excess of the arch length can result in crowding of the teeth orthe tooth material in excess of the arch length can result in crowding of the teeth or
proclination of anterior segment. Hence the reduction of tooth material is achieved byproclination of anterior segment. Hence the reduction of tooth material is achieved by
extraction of one or more teeth.extraction of one or more teeth.
Type of alveolar process:Type of alveolar process:
– Extraction is done when the alveolar process is narrow & offer little support to the bone.Extraction is done when the alveolar process is narrow & offer little support to the bone.

TheThe axial inclinationaxial inclination of the mandibular incisors & their effect on the FIMA (Frankfortof the mandibular incisors & their effect on the FIMA (Frankfort
mandibular incisor angle)mandibular incisor angle)
The axial positioning of dental units, both in normal and in malocclusion isThe axial positioning of dental units, both in normal and in malocclusion is
purposeful, just as in arch form and tooth alignment. It is dictated by force balance,purposeful, just as in arch form and tooth alignment. It is dictated by force balance,
both functional and environmental.both functional and environmental.
Hence no longer move the teeth into position wherein these balanced forces areHence no longer move the teeth into position wherein these balanced forces are
violated. Where it is decided that the position of the root apices does not favourviolated. Where it is decided that the position of the root apices does not favour
prolonged mechano-therapy with the preservation of all the teeth, reduction in theprolonged mechano-therapy with the preservation of all the teeth, reduction in the
number of teeth may assist in obtaining a stable result in the minimum time.number of teeth may assist in obtaining a stable result in the minimum time.

Correction of interarch relationship (sagittal)Correction of interarch relationship (sagittal)
– Abnormal sagittal relationship such as Class II or class III malocclusion mayAbnormal sagittal relationship such as Class II or class III malocclusion may
require extraction of teeth to achieve normal sagittal interarch relation. In suchrequire extraction of teeth to achieve normal sagittal interarch relation. In such
cases extraction helps in establishing normal incisor & molar relationship.cases extraction helps in establishing normal incisor & molar relationship.
Angle class I:Angle class I:
– In this case A-P relationship of arches is in correct relation so it is unwise toIn this case A-P relationship of arches is in correct relation so it is unwise to
discourage forward development of the alveolar bone in one jaw more than in thediscourage forward development of the alveolar bone in one jaw more than in the
other. Extraction to be performed are those completely displaced from the arch,other. Extraction to be performed are those completely displaced from the arch,
are usually better to be symmetrical, the same tooth being removed from all theare usually better to be symmetrical, the same tooth being removed from all the
quadrants.quadrants.

Angle class II:Angle class II:
– In this case the upper arch is relatively forward than the lower arch, in suchIn this case the upper arch is relatively forward than the lower arch, in such
conditions the upper arch has to be controlled for further development.conditions the upper arch has to be controlled for further development.
– In such a case with severe crowding & the lower incisor root apices are in correctIn such a case with severe crowding & the lower incisor root apices are in correct
relationship to one other, extraction of premolars tooth from either side of therelationship to one other, extraction of premolars tooth from either side of the
upper arch, this will cause a relative impairment of the forward development ofupper arch, this will cause a relative impairment of the forward development of
the upper arch and allowing anterior teeth to be moved back with the fixedthe upper arch and allowing anterior teeth to be moved back with the fixed
appliances, there by improving the U/L incisor relationship.appliances, there by improving the U/L incisor relationship.
– Usually the 1st PM is the choiceUsually the 1st PM is the choice
– Normally extraction from lower arch is avoided unless it is indicated byNormally extraction from lower arch is avoided unless it is indicated by
orthodontic treatment.orthodontic treatment.

Angle class III:Angle class III:
– When treatment of class III case is complete , the upper incisors are ahead ofWhen treatment of class III case is complete , the upper incisors are ahead of
lower incisor and prevention of upper incisor relapse to its original position as inlower incisor and prevention of upper incisor relapse to its original position as in
before treatment of class III is by positive overbite. Extraction in upper arch isbefore treatment of class III is by positive overbite. Extraction in upper arch is
avoided because of the forward development of the arch, if extractions areavoided because of the forward development of the arch, if extractions are
inevitable consideration should be given to reduce the no. of teeth in lower archinevitable consideration should be given to reduce the no. of teeth in lower arch
in order to compensate.in order to compensate.
– If extraction from the lower arch is considered necessary in class III case, theyIf extraction from the lower arch is considered necessary in class III case, they
should be performed as early as possible in order that the maximum interferenceshould be performed as early as possible in order that the maximum interference
with the forward development of the arch is obtained and if extraction is delayedwith the forward development of the arch is obtained and if extraction is delayed
until a late age it is difficult to obtain any change in the form of dental arch.until a late age it is difficult to obtain any change in the form of dental arch.

Abnormal size and form of teeth:Abnormal size and form of teeth:
– Anomalies such asAnomalies such as macrodontia, severely hypoplastic teeth, dilacerations andmacrodontia, severely hypoplastic teeth, dilacerations and
abnormal crown morphologyabnormal crown morphology may need extraction in order to achievemay need extraction in order to achieve
satisfactory occlusion.satisfactory occlusion.
– Unless an acceptable shape can be restored by means of a crowns or byUnless an acceptable shape can be restored by means of a crowns or by
stoning away an offending cusp, it may be necessary to extract the tooth.stoning away an offending cusp, it may be necessary to extract the tooth.
– Skeletal jaw malrelations:Skeletal jaw malrelations:
– Severe skeletal malrelations of the jaws may not be satisfactorily treated usingSevere skeletal malrelations of the jaws may not be satisfactorily treated using
only orthodontic appliances alone. Surgical resective procedures along withonly orthodontic appliances alone. Surgical resective procedures along with
extraction may be required in such cases for their corrections.extraction may be required in such cases for their corrections.

B.B. Dental Variables:Dental Variables:
Dental discrepancyDental discrepancy
– Crowding of 4-8mm can be treated with or without extractionCrowding of 4-8mm can be treated with or without extraction
– Discrepancy of more than 8mm indicates extraction becauseDiscrepancy of more than 8mm indicates extraction because
conservative procedures of stripping is inadequateconservative procedures of stripping is inadequate
Bolton discrepancyBolton discrepancy
– An interarch tooth size discrepancy may be as good reason forAn interarch tooth size discrepancy may be as good reason for
extraction as an intra –arch discrepancyextraction as an intra –arch discrepancy
– More than 4mm is consider severe and indicates extraction to adjustMore than 4mm is consider severe and indicates extraction to adjust
the inter arch relationshipsthe inter arch relationships
– Less than 4mm –strippingLess than 4mm –stripping

Curve of SpeeCurve of Spee
– 3-5 mm (1.5-3mm per side)3-5 mm (1.5-3mm per side)
is consider mildis consider mild
– Greater than 6mm isGreater than 6mm is
considered severe andconsidered severe and
borderline patient with aborderline patient with a
deep curve of Spee is likelydeep curve of Spee is likely
to require extractionto require extraction

Peck & Peck indexPeck & Peck index
– Peck & Peck, finding that crowded lower incisors were much wider M-D than B-L,Peck & Peck, finding that crowded lower incisors were much wider M-D than B-L,
proposed anproposed an index for assessing the shape deviations of the mandibular incisorsindex for assessing the shape deviations of the mandibular incisors
– To calculate the index, the greatest M-D crown dimension is divided by theTo calculate the index, the greatest M-D crown dimension is divided by the
greatest B-L crown dimension of lower incisors (located near gingival margin) andgreatest B-L crown dimension of lower incisors (located near gingival margin) and
results are multiplied by 100results are multiplied by 100
– Index b/w 88-95Index b/w 88-95  good anatomical shapegood anatomical shape
– Index greater than 95Index greater than 95  M-D width of the tooth is much greater than the B-LM-D width of the tooth is much greater than the B-L
widthwidth
– Stripping improve the shape of these teeth and gain space in the mandibular archStripping improve the shape of these teeth and gain space in the mandibular arch
– Borderline cases with narrow lower incisors (< 88) stripping does not help muchBorderline cases with narrow lower incisors (< 88) stripping does not help much
so consideration for extraction is needed.so consideration for extraction is needed.

Irregularity index:Irregularity index:
– Proposed byProposed by LittleLittle to evaluate mandibular incisor alignmentto evaluate mandibular incisor alignment
– Adding the linear distance b/w theAdding the linear distance b/w the 5 adjacent anatomical contact points5 adjacent anatomical contact points of lowerof lower
anterior teeth. Thus the score will be 0 if the patient has perfectly aligned incisorsanterior teeth. Thus the score will be 0 if the patient has perfectly aligned incisors
and canines.and canines.
– Index of 3.5-6.5mmIndex of 3.5-6.5mm  mild irregularitymild irregularity
– Greater than 6.5mmGreater than 6.5mm  severe irregularity and greater need for extractionsevere irregularity and greater need for extraction

C.C. Cephalometric VariablesCephalometric Variables
The 1st four factors evaluate the vertical facial proportion and other three focus on theThe 1st four factors evaluate the vertical facial proportion and other three focus on the
lower incisors, since proclination of these is one of the main reasons for extractionlower incisors, since proclination of these is one of the main reasons for extraction
1.1. Relationship of horizontal planeRelationship of horizontal plane::
– According toAccording to SassouniSassouni,, the horizontalthe horizontal
plane relationship of the supra-orbital,plane relationship of the supra-orbital,
palatal, occlusal, mandibular planespalatal, occlusal, mandibular planes
reflects the vertical proportionality of thereflects the vertical proportionality of the
CF skeletalCF skeletal
– Highly divergent planesHighly divergent planes  skeletal openskeletal open
bitebite  indicates in favor of extractionindicates in favor of extraction
– Parallel planesParallel planes  skeletal deep biteskeletal deep bite 
does not favor extractiondoes not favor extraction

2.2. SN-MPSN-MP
– According toAccording to SchudySchudy the normal values are 30 -34the normal values are 30 -3400
– SN-MP angle, which is closely related to the FMA, provides another appraisal ofSN-MP angle, which is closely related to the FMA, provides another appraisal of
the vertical balance of the face.the vertical balance of the face.

3.3. FMAFMA
– Patient with skeletal deep bite havePatient with skeletal deep bite have
FMA angle less than 20FMA angle less than 2000
nonnon
extractionextraction
– Patients have FMA angle morePatients have FMA angle more
than 30than 3000
 favor for extractionfavor for extraction

4.4. Proportion of PFH to AFHProportion of PFH to AFH
– Ratio was proposed byRatio was proposed by Jarabak and FizzelJarabak and Fizzel to evaluate the vertical equilibrium of the CFto evaluate the vertical equilibrium of the CF
skeletonskeleton
– Normal ratio 62-65%Normal ratio 62-65%
– Less than 61%Less than 61%  skeletal open biteskeletal open bite  favor extractionfavor extraction
– More than 65%More than 65% skeletal deep biteskeletal deep bite  non extractionnon extraction
5.5. IMPAIMPA
– Proposed byProposed by MargolisMargolis to evaluate the inclination of lower incisor to MPto evaluate the inclination of lower incisor to MP
– According toAccording to TweedTweed, IMPA can vary b/w 85-95, IMPA can vary b/w 85-9500
, but its value is highly influenced by the, but its value is highly influenced by the
mandibular plane inclination and the patient’s ethnicity.mandibular plane inclination and the patient’s ethnicity.
– Due to functional and esthetic impairment, an IMPA greater than 96Due to functional and esthetic impairment, an IMPA greater than 9600
is considered foris considered for
extraction.extraction.

6.6. FMIAFMIA
Angle formed by intersection of FH plane & long axis of the lower incisor 60-70Angle formed by intersection of FH plane & long axis of the lower incisor 60-7000
Angle less than 60Angle less than 6000
proclination of lower incisorsproclination of lower incisors  favor extractionfavor extraction
Angle more than 70Angle more than 7000
 retroclination of lower incisorsretroclination of lower incisors  non extractionnon extraction
7. Distance b/w lower incisor7. Distance b/w lower incisor to A- Pog lineto A- Pog line
Proclination of lower incisor can also be assessed by measuring the distance fromProclination of lower incisor can also be assessed by measuring the distance from
the incisal edge to the most prominent mandibular incisor to the line connecting pointthe incisal edge to the most prominent mandibular incisor to the line connecting point
A to Pog.A to Pog.
Negative valueNegative value  lower incisors are behind A-Pog linelower incisors are behind A-Pog line
Values b/w –2 to +3mmValues b/w –2 to +3mm  a good sagittal position of the lower incisors.a good sagittal position of the lower incisors.

D. Facial VariablesD. Facial Variables
– The facial esthetic of borderline patients can be adversely affected byThe facial esthetic of borderline patients can be adversely affected by
orthodontics if only dental and skeletal standards are used in treatment planningorthodontics if only dental and skeletal standards are used in treatment planning
1.1. Distance b/w E-line & lower lipDistance b/w E-line & lower lip
– E-lineE-line tip of the nose to Pogtip of the nose to Pog II
– Lower lip (labrale inferius) is about 2mm behind this line (but because of age &Lower lip (labrale inferius) is about 2mm behind this line (but because of age &
sex difference, a standard deviation of 3mm was admitted by Ricketts)sex difference, a standard deviation of 3mm was admitted by Ricketts)
– Values b/wValues b/w –5 & +1mm–5 & +1mm are considered normal, while greater than + 1mmare considered normal, while greater than + 1mm
indicates lip prominenceindicates lip prominence
– Since esthetically pleasing face can be disrupted by lip protrusion extraction isSince esthetically pleasing face can be disrupted by lip protrusion extraction is
usually required.usually required.

2.2. Distance b/w B-line & lower lipDistance b/w B-line & lower lip
– According toAccording to BurstoneBurstone, the lower lip should be, the lower lip should be 2.52.5 ±±1.5mm1.5mm anterior to the B-lineanterior to the B-line
(columella meets U lip (subnasale) and Pog(columella meets U lip (subnasale) and Pog II
))
– Extraction is indicated if the lower lip is more than 4mm ahead of this lineExtraction is indicated if the lower lip is more than 4mm ahead of this line
3.3. N-L angleN-L angle
– Columella and U lip tangentColumella and U lip tangent
– According toAccording to Drobocky and SmithDrobocky and Smith extraction of 4 PM’s increases the angle by anextraction of 4 PM’s increases the angle by an
average of 5.2average of 5.200
, therefore extraction should be avoided in cases with obtuse, therefore extraction should be avoided in cases with obtuse
angleangle

4.4. Upper lip morphologyUpper lip morphology
– The upper lip thickness should beThe upper lip thickness should be measured in 2 different waysmeasured in 2 different ways
– 3mm below the pt. A and from the vermillion border to the labial surface of3mm below the pt. A and from the vermillion border to the labial surface of
maxillary CImaxillary CI
– NormallyNormally  these 2 measurements should approximately be the samethese 2 measurements should approximately be the same
– If the vermillion border is thinner than the U lip near pt. AIf the vermillion border is thinner than the U lip near pt. A lips are strainedlips are strained
– If the U lip is thinner than the vermilion borderIf the U lip is thinner than the vermilion border  lips are flaccidlips are flaccid
– In borderline patients with strained lips, the incisors can be retracted withoutIn borderline patients with strained lips, the incisors can be retracted without
altering the soft-tissue profile, because the lip needs to reach normal form andaltering the soft-tissue profile, because the lip needs to reach normal form and
thickness before retractionthickness before retraction  in such case extraction is neededin such case extraction is needed
– On other hand, the lips would immediately follow tooth movement in borderlineOn other hand, the lips would immediately follow tooth movement in borderline
patients with normal lips.patients with normal lips.
– According toAccording to Arnett and BergmanArnett and Bergman,, orthodontists should avoid extraction inorthodontists should avoid extraction in
patients with flaccid lips due to the lack of labial support and the potential forpatients with flaccid lips due to the lack of labial support and the potential for
esthetic problemsesthetic problems

55. Dental midline deviation. Dental midline deviation
– Dental midline deviation due to skeletal problems should be managed surgically,Dental midline deviation due to skeletal problems should be managed surgically,
but patients with a normal relationship of the facial midpoints can be treatedbut patients with a normal relationship of the facial midpoints can be treated
orthodontically, therefore severe dental midlines treated orthodontically supportsorthodontically, therefore severe dental midlines treated orthodontically supports
extractionextraction
6.6. Growth StatusGrowth Status
– Growth of soft and hard tissue has a significant influence on facial results ofGrowth of soft and hard tissue has a significant influence on facial results of
orthodontic treatmentorthodontic treatment
– Extraction must be considered cautiously in patients with considerable remainingExtraction must be considered cautiously in patients with considerable remaining
growth potential (pre-pubertal and pubertal patient)growth potential (pre-pubertal and pubertal patient)
– On the other hand, because further growth is unlikely to alter the facial profile ofOn the other hand, because further growth is unlikely to alter the facial profile of
adult patients, the decision of extraction isadult patients, the decision of extraction is safer in post-pubertal patientssafer in post-pubertal patients

Upper incisor extractionUpper incisor extraction::
– These teeth areThese teeth are rarely extracted for the relief of crowdingrarely extracted for the relief of crowding, unless their, unless their
condition indicating that they are damaged severely beyond repair. Incondition indicating that they are damaged severely beyond repair. In
such cases the lateral incisors maybe aligned and shaped to centralsuch cases the lateral incisors maybe aligned and shaped to central
incisors in favorable situations.incisors in favorable situations.
– SevereSevere malposition of the teethmalposition of the teeth, particularly when its apex is positioned, particularly when its apex is positioned
palatallypalatally
– Malformed tooth (Cone form)Malformed tooth (Cone form)
– When lateral incisors are severely fractured in young children, it may beWhen lateral incisors are severely fractured in young children, it may be
necessary to extract thenecessary to extract the broken incisorbroken incisor and move the adjacent canine toand move the adjacent canine to
occupy the space.occupy the space.
– When the roots are unfavorablyWhen the roots are unfavorably dilacerated, ankyloseddilacerated, ankylosed, this makes, this makes
orthodontic tooth movement less efficient.orthodontic tooth movement less efficient.
– Unfavorably impacted toothUnfavorably impacted tooth

DrawbackDrawback
– Occlusion with incisor tooth extraction show a tendency to cusp-cusp relation onOcclusion with incisor tooth extraction show a tendency to cusp-cusp relation on
one side of the dental arches with what is known asone side of the dental arches with what is known as Slippage.Slippage. There maybe aThere maybe a
tendency for the space to open when the basal arch is large & in addition there istendency for the space to open when the basal arch is large & in addition there is
a tendency to increased maxillary incisor overjet & occasionally also to deepa tendency to increased maxillary incisor overjet & occasionally also to deep
overbite.overbite.
– When a maxillary lateral incisor tooth is missing, the decision to permit the spaceWhen a maxillary lateral incisor tooth is missing, the decision to permit the space
to remain open or to close it depends on theto remain open or to close it depends on the general arrangement of the teeth,general arrangement of the teeth,
the size of the basal arch, the facial outline, the thickness & tonicity of the softthe size of the basal arch, the facial outline, the thickness & tonicity of the soft
tissue covering face.tissue covering face. When the incisor teeth are in lingual inclination and theWhen the incisor teeth are in lingual inclination and the
basal arch is of ample proportion, extraction is usually followed by spacebasal arch is of ample proportion, extraction is usually followed by space
opening.opening.

Lower incisor extractionLower incisor extraction::
– According toAccording to Joondeph & Riedel, TurersonJoondeph & Riedel, Turerson and others -1980 one or two lowerand others -1980 one or two lower
incisors will be extracted as part of orthodontic treatment.incisors will be extracted as part of orthodontic treatment.
– For eg: patient with an open bite,For eg: patient with an open bite, Class III tendency or a periodontal problemClass III tendency or a periodontal problem
involving excessive gingival recession on the most protruded incisorinvolving excessive gingival recession on the most protruded incisor
– Space left by extraction should not be allowed to close by itself because of toothSpace left by extraction should not be allowed to close by itself because of tooth
shifting can not be predicted, so active space closure by means of orthodonticshifting can not be predicted, so active space closure by means of orthodontic
appliance is required.appliance is required.
– Anomalies in the number of anterior teethAnomalies in the number of anterior teeth
– Tooth size anomaliesTooth size anomalies
– Ectopic eruption of incisorsEctopic eruption of incisors
– Moderate class III malocclusionModerate class III malocclusion

1.Anomalies in the number of anterior teeth1.Anomalies in the number of anterior teeth
– TheThe supernumerarysupernumerary lower incisor require its extraction in order to achieve good occlusallower incisor require its extraction in order to achieve good occlusal
alignmentalignment
– A common case involving theA common case involving the absence of upper lateral incisorabsence of upper lateral incisor tooth, which may betooth, which may be
replaced with prosthesis or alternatively the space can be closed by orthodontically.replaced with prosthesis or alternatively the space can be closed by orthodontically.
– The extraction of a lower incisor would be indicated in order to co-ordinate the occlusion ofThe extraction of a lower incisor would be indicated in order to co-ordinate the occlusion of
the incisors.the incisors.
2.Tooth size anomalies2.Tooth size anomalies
– Discrepancy in M-D sizeDiscrepancy in M-D size of the six anterior teeth may be corrected by extracting a lowerof the six anterior teeth may be corrected by extracting a lower
incisor.incisor.
– The disproportion as reflected byThe disproportion as reflected by Bolton’s index 1958Bolton’s index 1958 is established by the relativeis established by the relative
macrodontia of the lower incisors or macrodontia of upper laterals.macrodontia of the lower incisors or macrodontia of upper laterals.
– TheThe fracture or morphological defectfracture or morphological defect of a mandibular incisor indicates its extraction inof a mandibular incisor indicates its extraction in
cases of crowding.cases of crowding. www.indiandentalacademy.comwww.indiandentalacademy.com

3.Ectopic eruption of incisors3.Ectopic eruption of incisors
– TranspositionTransposition of anterior teeth, particularly of theof anterior teeth, particularly of the caninescanines, or the severe malpositioning of a, or the severe malpositioning of a
lower incisor, indicates extraction to protect the long term survival of the dentition.lower incisor, indicates extraction to protect the long term survival of the dentition.

4.Moderate class III malocclusion4.Moderate class III malocclusion
– Anterior cross bite or an E-E relation of the incisors with a tendency towardsAnterior cross bite or an E-E relation of the incisors with a tendency towards
anterior open bite is another reason for extraction of lower incisor teeth.anterior open bite is another reason for extraction of lower incisor teeth.
– The occlusion improves on shortening the length of the mandibular arch, whichThe occlusion improves on shortening the length of the mandibular arch, which
retract the position of the lower incisors.retract the position of the lower incisors.
5. One way to prevent relapse it is wise to extract an incisor which is5. One way to prevent relapse it is wise to extract an incisor which is
malpositioned severely and moreover limits the unnecessarily movement ofmalpositioned severely and moreover limits the unnecessarily movement of
the tooth, correction thus becomes more circumscribed to a specificthe tooth, correction thus becomes more circumscribed to a specific
dentition zone. Thedentition zone. The loss of gingivalloss of gingival tissue or the disappearance of thetissue or the disappearance of the
external alveolar laminaexternal alveolar lamina constitutes an additional indication for extraction ofconstitutes an additional indication for extraction of
affected incisorsaffected incisors

Limitation for incisor extractionLimitation for incisor extraction
– AnAn accentuated over jetaccentuated over jet is a contra indication to the removal of a single loweris a contra indication to the removal of a single lower
incisor in presence of a positive over jet thereby closure of lower space willincisor in presence of a positive over jet thereby closure of lower space will
increase the overjet.increase the overjet.
– On removing an incisor, the canine displaces mesially and theOn removing an incisor, the canine displaces mesially and the canine functionalcanine functional
protectionprotection (Guidance) is lost.(Guidance) is lost.
– In certain cases particularly among adults theIn certain cases particularly among adults the space either fails to close or elsespace either fails to close or else
opens upopens up with ease, visible diastema thus results in an area of considerablewith ease, visible diastema thus results in an area of considerable
aesthetic and periodontal importance.aesthetic and periodontal importance.

Canine extractionCanine extraction::
– As a general rule, canine extractions are avoided.As a general rule, canine extractions are avoided.
Extraction of these teeth causesExtraction of these teeth causes
– flattening of faceflattening of face
– altered facial balancealtered facial balance
– change in facial expressionchange in facial expression
– the contact produced b/w the lateral and 1st PM are rarely satisfactorythe contact produced b/w the lateral and 1st PM are rarely satisfactory..
– It is only extracted when it isIt is only extracted when it is severely malposedseverely malposed andand impactedimpacted
– Impaction of canines is twice as common in females (1.17%) as in males (0.51%)Impaction of canines is twice as common in females (1.17%) as in males (0.51%)
– Mandibular impaction ---0.35%Mandibular impaction ---0.35%
– Palatal impaction: Labial impactionsPalatal impaction: Labial impactions ==== 2:1 or 3:1 Fournier et al 1982.2:1 or 3:1 Fournier et al 1982.
– Extraction of labially erupting and crowded canine is contraindicatedExtraction of labially erupting and crowded canine is contraindicated
– In case of extraction might temporarily improve the esthetics but may complicate andIn case of extraction might temporarily improve the esthetics but may complicate and
comprise the orthodontic treatment results, including the ability to provide the patient withcomprise the orthodontic treatment results, including the ability to provide the patient with
functional occlusion.functional occlusion.

IndicationsIndications::
– If it is ankylosed and cannot be transplantedIf it is ankylosed and cannot be transplanted
– If it is undergoing external or internal root resorptionIf it is undergoing external or internal root resorption
– If the root is severely dilaceratedIf the root is severely dilacerated
– In cases where canine is impacted between centralIn cases where canine is impacted between central
and lateral incisor roots and orthodontic correctionand lateral incisor roots and orthodontic correction
affects the neighbouring tooth structures.affects the neighbouring tooth structures.
– If the occlusion is acceptable with the 1st PM inIf the occlusion is acceptable with the 1st PM in
position of canine and with a functional occlusion withposition of canine and with a functional occlusion with
well aligned teeth or transposition of canine.well aligned teeth or transposition of canine.
– If any pathology involving the toothIf any pathology involving the tooth

1st Premolar extraction1st Premolar extraction::
– The 1st PM are the most commonly extracted teeth as part of orthodonticThe 1st PM are the most commonly extracted teeth as part of orthodontic
treatment. They are the teeth usually extracted when it is necessary to obtaintreatment. They are the teeth usually extracted when it is necessary to obtain
stable results in malocclusion with dental arch, basal arch discrepanciesstable results in malocclusion with dental arch, basal arch discrepancies. The. The
choice dependschoice depends on theon the
– Age of the patientAge of the patient
– Presence & severity of cariesPresence & severity of caries
– Presence of extensive fillingPresence of extensive filling
– Agenesis of other teeth in the dental archAgenesis of other teeth in the dental arch

TheThe reasonsreasons ffor their extraction are:or their extraction are:
– That they leave behind the posterior segment that offer adequate anchorage forThat they leave behind the posterior segment that offer adequate anchorage for
the retraction of the anterior segmentthe retraction of the anterior segment
– TheThe contactcontact that results b/w the canine & 2nd PM is satisfactorythat results b/w the canine & 2nd PM is satisfactory
– Extraction sites can usually be closed without much difficultyExtraction sites can usually be closed without much difficulty
– Their location in the arch is much that the space gained by their extraction can beTheir location in the arch is much that the space gained by their extraction can be
utilized for correction both in the anterior as well as the posterior regionutilized for correction both in the anterior as well as the posterior region
– Eruptive sequence permits proper eruption of canines if removed in time to avoidEruptive sequence permits proper eruption of canines if removed in time to avoid
crowding or impaction.crowding or impaction.

– To relieve moderate to severe anterior crowding of the upper or lower archTo relieve moderate to severe anterior crowding of the upper or lower arch
– For correction of moderate to severe anterior proclination as in a class IIFor correction of moderate to severe anterior proclination as in a class II
div 1 malocclusion or class I bimaxillary protrusion.div 1 malocclusion or class I bimaxillary protrusion.

Contraindications:Contraindications:
– Delayed treatment with a fixedDelayed treatment with a fixed
appliance can cause alveolar processappliance can cause alveolar process
resorption at the extraction site whichresorption at the extraction site which
may delay tooth movement & theremay delay tooth movement & there
may be permanent constriction ofmay be permanent constriction of
alveolar process at the extraction sitealveolar process at the extraction site

Treatment mechanics during bicuspidTreatment mechanics during bicuspid
extraction treatmentextraction treatment
– Initial cuspid angulationsInitial cuspid angulations
– Cuspid retraction during levelingCuspid retraction during leveling
and aligningand aligning
– Torque control during space closureTorque control during space closure
– Overbite control during OJOverbite control during OJ
reductionreduction

Vertical changes following extractionVertical changes following extraction::
– According toAccording to Witzig, Spahl & TulleyWitzig, Spahl & Tulley extraction of PM’s permits the posterior teeth to moveextraction of PM’s permits the posterior teeth to move
forward resulting in a decrease in the vertical dimension of occlusion. The mandible is thenforward resulting in a decrease in the vertical dimension of occlusion. The mandible is then
allowed to over close & the muscles of mastication become foreshortened. As aallowed to over close & the muscles of mastication become foreshortened. As a result TMJresult TMJ
problems are likely to occurproblems are likely to occur. Although this theory is popular particularly among general. Although this theory is popular particularly among general
practitioners, no controlled study has published results supporting this hypothesis.practitioners, no controlled study has published results supporting this hypothesis.
– Another theory that has been proposed according toAnother theory that has been proposed according to Witzig, Spahl & FarrarWitzig, Spahl & Farrar that 1st PMthat 1st PM
extractionsextractions lead to over retraction of the anteriorlead to over retraction of the anterior. This over retraction of anterior teeth is. This over retraction of anterior teeth is
thought to displace the mandible & the condyles posteriorly. Posterior condylarthought to displace the mandible & the condyles posteriorly. Posterior condylar
displacement has long been associated with TMJ disorders. As with the previousdisplacement has long been associated with TMJ disorders. As with the previous
hypothesis, this theory has not been substantiated by research.hypothesis, this theory has not been substantiated by research.

– However,However, Staggers (Staggers (1994)1994) in his study of age group 9-28 yrs & 9-16 yrsin his study of age group 9-28 yrs & 9-16 yrs
b/w extraction & non extraction groups show no significant differences inb/w extraction & non extraction groups show no significant differences in
vertical changes. On average the change in all cephalometricsvertical changes. On average the change in all cephalometrics
measurements from before treatment to after treatment reflected anmeasurements from before treatment to after treatment reflected an
increase in the vertical dimension.increase in the vertical dimension.

22ndnd
PM ExtractionPM Extraction
Discussed in orthodontics literature in theDiscussed in orthodontics literature in the
1940s and 1950s1940s and 1950s
Nance, Dewel, Carey were the earliestNance, Dewel, Carey were the earliest
one to discussone to discuss
22ndnd
PM extractions were favored by post Angle extraction proponents, such as P R Begg andPM extractions were favored by post Angle extraction proponents, such as P R Begg and
Charles TweedCharles Tweed
To this day 1To this day 1stst
PM remain the conventional extraction choice for most orthodontists in managingPM remain the conventional extraction choice for most orthodontists in managing
cases with substantial anterior crowding or protrusioncases with substantial anterior crowding or protrusion
However for dental reasons or for treatment mechanics reasons, 2However for dental reasons or for treatment mechanics reasons, 2ndnd
PM extraction may be indicatedPM extraction may be indicated
in some cases.in some cases.

22ndnd
Premolar extraction:Premolar extraction:
– These teeth should be extracted when they areThese teeth should be extracted when they are excluded completely from the arch,excluded completely from the arch,
which can be noticed in cases of early loss of 2nd deciduous molars & premolarswhich can be noticed in cases of early loss of 2nd deciduous molars & premolars
usually erupt lingually.usually erupt lingually.
– Mild incisor crowdingMild incisor crowding which is to be treated with fixed appliance,2which is to be treated with fixed appliance,2ndnd
PM can be a bestPM can be a best
choice for extractionchoice for extraction as space closure can be completed by controlled forwardas space closure can be completed by controlled forward
movementmovement of the lower molars without the danger of unwanted retraction of theof the lower molars without the danger of unwanted retraction of the
labial segment which can occur in such cases where 1st PM have been extracted.labial segment which can occur in such cases where 1st PM have been extracted.
The presence of the 1st PM anterior to the extraction site alters the anchorageThe presence of the 1st PM anterior to the extraction site alters the anchorage
balance in a way that favors closure from behind.balance in a way that favors closure from behind.
– Other situation like when the 2Other situation like when the 2ndnd
PM isPM is unfavorably impactedunfavorably impacted it is preferred to beit is preferred to be
extracted.extracted.
– InIn open bite casesopen bite cases, where extractions are to be undertaken, it is preferable to extract, where extractions are to be undertaken, it is preferable to extract
the 2the 2ndnd
PM’s as their extractionPM’s as their extraction encourages deepening of the biteencourages deepening of the bite..
– Common factors likeCommon factors like grossly decayed or deep fillinggrossly decayed or deep filling it is advised to be extracted.it is advised to be extracted.

Reasons for extraction of 2Reasons for extraction of 2ndnd
PMPM
Dental reasonsDental reasons
– Caries or restorationsCaries or restorations
– Malformed or abnormally smallMalformed or abnormally small
teethteeth
– One or more missing 2One or more missing 2ndnd
PMPM
– Local crowding, displacement,Local crowding, displacement,
or impactionor impaction
Horizontal anchorageHorizontal anchorage
– Borderline extraction casesBorderline extraction cases
– Class II and class III casesClass II and class III cases
Vertical anchorageVertical anchorage
Tooth contactsTooth contacts
Tooth size factorsTooth size factors
Bracket tip considerationBracket tip consideration

Second PM extraction –vertical anchorageSecond PM extraction –vertical anchorage
No reduction in vertical height in both PM extractionNo reduction in vertical height in both PM extraction
MP angle showed minimal changesMP angle showed minimal changes
Molars move mesially in 1Molars move mesially in 1stst
PM extraction cases, there wasPM extraction cases, there was
compensatory eruption of posterior teethcompensatory eruption of posterior teeth
This maintained MP angle and vertical dimensionThis maintained MP angle and vertical dimension
Most studies on average to high angle cases, indicate slight verticalMost studies on average to high angle cases, indicate slight vertical
dimension increase as part of treatmentdimension increase as part of treatment
Tendency for the bite to close in extraction cases is due to the spaceTendency for the bite to close in extraction cases is due to the space
that is provided for eruption, up righting, and retraction of incisors,that is provided for eruption, up righting, and retraction of incisors,
which in turn leads to bite closurewhich in turn leads to bite closure
This gives the clinical impression that the vertical dimension has beenThis gives the clinical impression that the vertical dimension has been
reducedreducedwww.indiandentalacademy.comwww.indiandentalacademy.com

Tooth contactsTooth contacts
– The contact point with the 1The contact point with the 1stst
M is similar after extraction of 1 orM is similar after extraction of 1 or
22ndnd
PMPM
– In lower arch , however the 2In lower arch , however the 2ndnd
PM is frequently larger in size andPM is frequently larger in size and
has a larger occlusal table than the 1has a larger occlusal table than the 1stst
PMPM
– The lower 1The lower 1stst
PM is often quite tapered and has a poorlyPM is often quite tapered and has a poorly
developed lingual cusp in comparison to the 2developed lingual cusp in comparison to the 2ndnd
PM and the distalPM and the distal
surface of the lower 2surface of the lower 2ndnd
PM is flattened and provides a betterPM is flattened and provides a better
contact point with the 1contact point with the 1stst
molar than the more convex and pointedmolar than the more convex and pointed
shape of the distal surface of the 1shape of the distal surface of the 1stst
PMPM
– For these reasons, the 1For these reasons, the 1stst
PM extraction in the lower arch, isPM extraction in the lower arch, is
preferred over 2preferred over 2ndnd
PM extraction, unless other factors indicatePM extraction, unless other factors indicate
themthem

DrawbackDrawback
– When there is more than 2-3 mm of residual space at the 2When there is more than 2-3 mm of residual space at the 2ndnd
PM site, spontaneous spacePM site, spontaneous space
closure following its extraction is usually rather unsatisfactory, with mesial tipping of the 1stclosure following its extraction is usually rather unsatisfactory, with mesial tipping of the 1st
permanent molar & disruption of the occlusionpermanent molar & disruption of the occlusion
– Spontaneous alignment of the lower incisors is much less satisfactory than where 1st PMSpontaneous alignment of the lower incisors is much less satisfactory than where 1st PM
have been removed.have been removed.

1st Molar extraction1st Molar extraction::
– These teeth are seldom teeth of choice for extraction for orthodontic purposeThese teeth are seldom teeth of choice for extraction for orthodontic purpose
because even when they are removed at the optimal time, thebecause even when they are removed at the optimal time, the contactcontact
relationshiprelationship b/w the 2b/w the 2ndnd
PM & the 2PM & the 2ndnd
Molar is rarely ideal and poor.Molar is rarely ideal and poor.
– AvoidedAvoided for the following reason:for the following reason:
Does not give adequate space for anterior segmentDoes not give adequate space for anterior segment
Results in deepening of biteResults in deepening of bite
22ndnd
PM & M will tip into the extraction spacePM & M will tip into the extraction space
mastication will be affectedmastication will be affected

– Minimal space requirement for correction of mild anterior crowding orMinimal space requirement for correction of mild anterior crowding or
mild proclinationmild proclination
– Grossly decayed molar or huge (Large) filled teethGrossly decayed molar or huge (Large) filled teeth
– Open bite cases can benefit from extraction of 1st molar as there is aOpen bite cases can benefit from extraction of 1st molar as there is a
tendency for the bite to deepening after extraction of 1st molarstendency for the bite to deepening after extraction of 1st molars
– When space required for alignment of anterior teeth, in such cases theWhen space required for alignment of anterior teeth, in such cases the
space available by removal of 1st molar will usually be needed forspace available by removal of 1st molar will usually be needed for
alignment of the anterior teeth. Therefore it is necessary to wait for 2alignment of the anterior teeth. Therefore it is necessary to wait for 2ndnd
molar eruption before extracting the 1st molars, so that space closuremolar eruption before extracting the 1st molars, so that space closure
by the forward movement of the 2by the forward movement of the 2ndnd
molars can be prevented.molars can be prevented.

HoustonHouston has advocated either the extraction before or after the eruption of the 2ndhas advocated either the extraction before or after the eruption of the 2nd
molars as routine measure with benefit to the dental archesmolars as routine measure with benefit to the dental arches
extraction before eruption of the 2nd molarsextraction before eruption of the 2nd molars::
In this case the 2nd molars are likely to move forward as it erupts, particularly in aIn this case the 2nd molars are likely to move forward as it erupts, particularly in a
crowded dentition, tendency to take up the position of the extracted 1st molar.crowded dentition, tendency to take up the position of the extracted 1st molar.
extraction after eruption of 2nd molarsextraction after eruption of 2nd molars
In this case the 2nd molar will tend to tilt or rotate forward into the 1st molar space,In this case the 2nd molar will tend to tilt or rotate forward into the 1st molar space,
but can readily be held back if necessary by mechanical therapybut can readily be held back if necessary by mechanical therapy

Wilkinson’s extractionWilkinson’s extraction::
– In this type all the 1st four molars are removed at the age of 8.5-9.5 yearsIn this type all the 1st four molars are removed at the age of 8.5-9.5 years
– This is done as it is the first permanent teeth to erupt into the oral cavity at the age of 6This is done as it is the first permanent teeth to erupt into the oral cavity at the age of 6
years and highly susceptible to decay (pits and fissure)years and highly susceptible to decay (pits and fissure)
– Extraction of 1st molars provides additional space for the eruption of the 3rd molars andExtraction of 1st molars provides additional space for the eruption of the 3rd molars and
thereby impaction of 3rd molars can be avoidedthereby impaction of 3rd molars can be avoided
– In general crowding of the arch is minimizedIn general crowding of the arch is minimized
Drawback:Drawback:
– Extraction of 1st molars offers limited space to relieve crowdingExtraction of 1st molars offers limited space to relieve crowding
– 2nd PM & 2nd Molars rotate and tilt into the extraction space2nd PM & 2nd Molars rotate and tilt into the extraction space
– It deprives the orthodontists of adequate anchorage support for any fixed orthodonticIt deprives the orthodontists of adequate anchorage support for any fixed orthodontic
applianceappliance
– A controlled follow-up of 100 cases byA controlled follow-up of 100 cases by Hallett & BurkeHallett & Burke in 1961 where the 1st molars hadin 1961 where the 1st molars had
been extracted showed less than 10% to have an acceptable occlusion.been extracted showed less than 10% to have an acceptable occlusion.
– Subsequent eruption of 2nd molars usually restores the original bite condition in deep biteSubsequent eruption of 2nd molars usually restores the original bite condition in deep bite
case due to removal of 1st molars.case due to removal of 1st molars.

2nd Molar Extraction:2nd Molar Extraction:
As the direction of growth and development of the alveolar process & the teeth isAs the direction of growth and development of the alveolar process & the teeth is
occlusally, outwards and forward, the teeth are moving forward during the periodsocclusally, outwards and forward, the teeth are moving forward during the periods
of active growth. As a result of extraction of 2nd molar may only provide space forof active growth. As a result of extraction of 2nd molar may only provide space for
3rd molar3rd molar

IndicationsIndications::
From review of literatureFrom review of literature the following reasons were proposed as major advantagesthe following reasons were proposed as major advantages
and favorable results of 2nd molar removal:and favorable results of 2nd molar removal:
– Facilitation of treatment using removable applianceFacilitation of treatment using removable appliance
– Reduction in the amount and duration of appliance therapyReduction in the amount and duration of appliance therapy
– Disimpaction of 3rd molarsDisimpaction of 3rd molars
– Faster eruption of 3rd molarsFaster eruption of 3rd molars
– Prevention of ‘dished-in’ appearance of the face at the end of the facial growthPrevention of ‘dished-in’ appearance of the face at the end of the facial growth
– Prevention of late incisor imbricationsPrevention of late incisor imbrications
– Facilitations of 1st molar distal movementFacilitations of 1st molar distal movement
– Distal movement of the dentition only as needed to correct the over jetDistal movement of the dentition only as needed to correct the over jet
– Fewer ‘residual’ spaces at the end of orthodontic treatmentFewer ‘residual’ spaces at the end of orthodontic treatment
– Less likelihood of relapseLess likelihood of relapse
– Good functional occlusionGood functional occlusion
– Good mandibular arch formGood mandibular arch form
– Reduction of incisal overbiteReduction of incisal overbite
– To relieve impaction of 2To relieve impaction of 2ndnd
PMPMwww.indiandentalacademy.comwww.indiandentalacademy.com

According toAccording to Chipman-2nd molarsChipman-2nd molars are removed whenare removed when
– Severely carious, ectopically erupted or severely rotatedSeverely carious, ectopically erupted or severely rotated
– Mild-moderate arch length deficiencies exist with good facial profilesMild-moderate arch length deficiencies exist with good facial profiles
– There is crowding in the tuberosity area with the need to facilitate 1st molar distalThere is crowding in the tuberosity area with the need to facilitate 1st molar distal
movement.movement.
AccordingAccording WilsonWilson,, PM extractions in Class I crowded cases without the use of fixedPM extractions in Class I crowded cases without the use of fixed
appliance therapy will result in tipping of teeth, poor contact points, increase inappliance therapy will result in tipping of teeth, poor contact points, increase in
overbite and functional interference. On theoverbite and functional interference. On the other handother hand, according to him extraction, according to him extraction
of 2nd molars wouldof 2nd molars would avoid these complicationsavoid these complications with either spontaneous correction ofwith either spontaneous correction of
the malocclusion or with the use of a simple appliance for short period of time. Thusthe malocclusion or with the use of a simple appliance for short period of time. Thus
the main benefit is avoidance of fully banded fixed appliance in class I casesthe main benefit is avoidance of fully banded fixed appliance in class I cases

AccordingAccording LehmanLehman
– Skeletal class I malocclusion with arch length discrepancy in the distal part of theSkeletal class I malocclusion with arch length discrepancy in the distal part of the
arch or with mild anterior crowdingarch or with mild anterior crowding
– In class II skeletal cases with only mild crowding of the mandibular archIn class II skeletal cases with only mild crowding of the mandibular arch
– He believes that PM extraction necessitates comprehensive, fixed applianceHe believes that PM extraction necessitates comprehensive, fixed appliance
treatment and that cases treated with 2nd molar extraction can be treated withtreatment and that cases treated with 2nd molar extraction can be treated with
head gear or lip bumper for relatively short period.head gear or lip bumper for relatively short period.
– Precondition for extractionPrecondition for extraction areare ::
All 3rd molars should be present and of normal size & shapeAll 3rd molars should be present and of normal size & shape
There should not be any congenitally missing teethThere should not be any congenitally missing teeth
Favorable inclination of 3rd molars should be present with a 15-30Favorable inclination of 3rd molars should be present with a 15-30 00
angle toangle to
the long axis of the 1st molar.the long axis of the 1st molar.

According toAccording to KokichKokich timing of extraction of 2nd molar istiming of extraction of 2nd molar is
– The 3rd molar crown should be formed completely but extraction carried outThe 3rd molar crown should be formed completely but extraction carried out
before root begins to developbefore root begins to develop
– The axial inclination of the bud should not be more than 30 degrees to occlusalThe axial inclination of the bud should not be more than 30 degrees to occlusal
planeplane
– 3rd molar should be close to the proximity to the 2nd molar roots to ensure3rd molar should be close to the proximity to the 2nd molar roots to ensure
adequate mesial drift of the 3rd molar as it eruptsadequate mesial drift of the 3rd molar as it erupts

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