Serial extraction in Class I
malocclusion
Dr Maher Fouda
Faculty of Dentistry
Mansoura
Egypt

DEFINITION OF SERIAL EXTRACTION
Serial extraction is defined as the planned and sequential
extraction of certain deciduous teeth followed by removal of
specific permanent teeth in order to encourage the spontane-ous
correction of irregularities.

HISTORICAL DEVELOPMENT
Throughout the history of orthodontics, it has been
recognized that the removal of one or more irregular teeth
would improve the appearance of the remainder.1 Bunon,
in his Essay on Diseases of the Teeth, published in 1743,
made the first reference to the removal of deciduous teeth
to achieve a better alignment of the permanent teeth.
Crowding of 3-4 mm. Lower Occlusal (masked).

The names that stand out particularly for the mod-
ern development of the serial extraction concept
are Kjellgren of Sweden, Hotz of Switzerland, Heath
of Australia, and Nance, Lloyd, Dewel and Mayne of
the United States.
Pretreatment intraoral photographs showing previous
extractions of the deciduous canines.

The word serial extraction was coined by Kjellgren (1929).
Nance presented clinics on his technique of ‘progressive
extraction’ a number of times in the 1940s and has been
called the ‘father’ of serial extraction philosophy in the
United States. Hotz renamed the technique as ‘guidance
of eruption’.
The deciduous first molars have been extracted.

Pioneers of Serial Extraction Philosophy • The concept of
serial extraction was introduced by Robert Bunon (1743).
The word serial extraction was coined by Kjellgren (1929).
Nance is called the ‘Father of serial extraction’ because he
popularized the technique. • Hotz renamed the technique
as ‘Guidance of eruption’.
Clinical significance
Extraction of maxillary and mandibular permanent premolars and extraction of
deciduous maxillary second molars and eruption of permanent maxillary second
premolars.
The mandibular anterior segment is well aligned.

RATIONALE OF SERIAL EXTRACTION
1. Growth of jaws: It is in Class I cases that serial ex-traction finds its
most successful application. If there is a Class I malocclusion with
generalized crowding in a normally growing child, the clinician would be
most unwise to resort to expansion of the maxillary and mandibular
arches with fixed or removable appliances. The normal growth of dental,
skeletal and soft tissue influences the result of serial extraction.
Class I cases

2. Dentitional adjustment in the anterior segment
during first transitional period: The fact that the
permanent incisors are larger than the deciduous
counterparts is quite obvious, even to the patient.

Direct measurement of this incisor liability, as it is termed by
Mayne, is possible and recommended. The deciduous–
permanent tooth size differential averages 6–7 mm, even when
there is no crowding. Any appreciable incisor liability, which
would not get adjusted despite the contributions by the
adjustment mechanisms listed in Box 31.1 strongly point to a
program of guided extraction in the mixed dentition period.

3. Dentitional adjustment in the posterior segment
during second transitional period: The combined widths
of the mandibular deciduous canine, first molar and
second molar averages to 1.7 mm, that is, more than the
combined widths of the three permanent successors.

As Nance indicated, there is less width differential in the
maxillary arch (average width difference 1 mm). This
‘leeway space’ exists on both sides, so it would average 3.4
mm in the mandibular arch and about 2 mm in the maxillary
arch.

Can it be used for incisor crowding? This leeway space is
required to correct the flush terminal plane relationship
which is a normal, transient developmental phenomenon
and is seen in a large percentage of cases
Moyers has reported that at
least 50% of normal developing
dentitions have a flush terminal
plane relationship that corrects
itself only with the loss of the
deciduous molars at the end of
the mixed dentition period with
the utilization of the leeway
space. This Class II tendency
may be accentuated with a
distal step, if there is a
morphogenetic Class II pattern
or an excessively deep overbite
and resultant functional
retrusion.

When the permanent teeth replaces primary teeth,
there is mesial shift of the mandibular first molar
utilizing the leeway space and mesiobuccal cusp of
the maxillary first molar locks into the mesiobuccal
groove of the mandibular first permanent molar.

The ‘leeway space’, then, is usually a reserved bit
of arch length to allow for the adjustment of
maxillary and mandibular dental arches during
the critical tooth exchange period.

When this space is used, holding back the permanent
mandibular molars to gain anterior arch length, it may
very well have a Class II tendency and result in full
Class II division 1 malocclusion. When the settling in the
cusps and grooves is prevented, it may create
premature contacts that intensify bruxism and
functional problems.

4. Dental crowding is the result of inadequate arch size.
Serial extraction aims to correct this discrepancy by
reducing the tooth material.

Why not intercept the developing malocclusion in the
early mixed dentition by relieving crowding to provide a
chance for nature to adapt with adequate space,
instead of waiting for all permanent dentition to emerge
into a full-blown malocclusion?
36 has grown after mucosal release. Without treatment, it remains slightly lingual
and rotated. Note isolated enamel hyperplasia in 75.

The answer is conditionally corroborative. But,
before commencing on this ‘robbing Peter to pay
Paul’ technique, the orthodontists must question
themselves .
Which road shall it be? After a diagnostic study
of an incipient malocclusion, a conditional
affirmative or negative decision is made. But this
tentative opinion is subject to constant
assessment during the program of guided
extraction. A ‘yes’ decision for guided extraction
means that at least a dozen decisions will have
to be made over a period of 2–4 years of
orthodontic preappliance guidance. Unless the
dentist is prepared to travel the road and make
the numerous decisions, based on periodic
diagnostic criteria, he or she should not
undertake the ‘trip’ in the first place.

5. Physiological tooth movement or drifting occurs
at the time and site of extraction. Teeth move both
mesially and drift distally. This principle is being utilized
in serial extraction for self-correction.

(MAYNE )
1. Intercanine arch growth: 3–4 mm
2. Interdental (developmental) spacing: 2–3
mm
3. More anterior position of permanent
incisors as they erupt: 1–2 mm
Compensatory mechanism of incisor liability

C L INI C A L S I GNI F I C ANC E
Benefits of Serial Extraction
• Serial extraction guides or encourages eruption of
permanent teeth in a favorable position.
• Reduces malposition of individual teeth.
• Avoids loss of labial alveolar bone.
• Reduces treatment time when active orthodontic
treatment is required.

FACTORS TO BE CONSIDERED
The relationship of the mesiodistal diameter of deciduous
dentition and permanent dentition is the most important factor to
be considered. The other factors are:
• Direction of growth indicated in normal Class I skeletal base
• Shape of dental arch
• Size of the teeth
• Relationship of the crowns to the alveolar crest and to the
adjacent teeth.

INVESTIGATIONS
Clinical Examination
When an orthodontist sees a child of 5 or 6 years of age with all the
deciduous teeth present in a slightly crowded state or with no spaces
between them, it can be predicted with a fair degree of certainty that
there will not be enough space in the jaws to accommodate all the
permanent teeth in their proper alignment.
Upper and lower occlusal views
of primary dentition. (a) The
upper dentition with space. (b)
The lower dentition with
space. (c) The upper dentition
without space. (d) The lower
dentition without space.

As Dewel, Mayne and others have pointed out, after
the eruption of the first permanent molars at 6 years
of age, there is probably no increase in the distance
from the mesial
aspect of the first molar on one side around the arch
to the mesial aspect of the first molar on the opposite
side.

If there is any change, it may be an actual
reduction of the molar-to-molar arch length, as the
‘leeway space’ is lost through the mesial migration
of the first permanent molars during the tooth
exchange process and correction of the flush
terminal plane relationship .

Diagnostic Discipline
The complete diagnostic records of study models,
periapical radiographs, panoramic radiographs and
cephalometric radiographs should be made and
studied. A calliper or fine line divider is used to
measure the combined widths of the teeth present in
each segment
A Boley gauge, or a pair of fine line dividers,
should be used to measure existing arch length
from plaster study casts. These recorded
measurements should be compared with those
taken of unerupted teeth, from long cone
technique intraoral radiographs, to determine
incisor liability and posterior segment leeway
space.

The circumferential measurement is recorded in study cast
from the mesial aspect of the first molar on one side to the
mesial aspect of the first molar on the other side .
Molar-to-molar arch length may be measured by adapting soft brass separating wire
around the arch from the mesial side of one first molar to the other, as illustrated. Wire
is then straightened out and measured with a millimetric rule.

INDICATIONS OR CLUES FOR SERIAL
EXTRACTION
The following is a list of possible clinical clues for serial
extraction, occurring singly or in combination:
1. Premature loss
2. Arch length deficiency and tooth size discrepancies
3. Lingual eruption of lateral incisors
4. Unilateral deciduous canine loss and shift to the same
side
and b) Bolton discrepancy
(oversized maxillary incisors
Unilateral deciduous canine
loss
Lingual eruption of lateral incisors

5. Canines erupting mesially over lateral incisors
6. Mesial drift of buccal segments
7. Abnormal eruption direction and eruption sequence
8. Flaring
9. Ectopic eruption
Complete space loss in
the upper arch after
early extraction of
carious upper first
primary molars
Canines erupting
mesially over
lateral incisors
Flaring
Ectopic eruption

10. Abnormal resorption
Intraoral periapical
radiographs are excellent
sources of serial
extraction clues. (A and B)
Maxillary lateral incisors
are blocked out of arch,
with an abnormal
resorption pattern. (C)
Lateral incisors are
probably erupting
lingually with arch length
deficiency. (D–F)
Abnormal resorption
patterns of deciduous
teeth serve as a harbinger
of future guided extraction
procedures.

11. Ankylosis
(A) intraoral photo. Infraocclusion of the maxillary left second primary molar being covered by the surrounding
tissues. (B)
Panoramic radiograph. Submerged maxillary left second primary molar with underlying permanent successors.

12. Labial stripping, or gingival recession, usually of a lower
incisor.

13. Rotated and tipped permanent molars in either arch are usually
a sign of mesial drift of the buccal teeth, and the first molars in
particular

CONTRAINDICATIONS OF SERIAL
EXTRACTION
Serial extraction is contraindicated in the following conditions:
1. Class I malocclusion with minimal arch size tooth size discrepancy
5. Partial anodontia or missing teeth

2. Class II division 2

4. Class III

Skeletal class III

6. Presence of midline diastema
7. Presence of deep overbite
8. Presence of open bite
9. When there is collapsed arch
10. In cleft lip and palate cases
midline diastema
deep overbite
open bite
cleft lip and palate

DEWEL’S TECHNIQUE OF SERIAL
EXTRACTION (CD4 TECHNIQUE)
This is usually done in three stages namely : (i) early
extraction of deciduous canine, (ii) extraction of
The three stages of serial
extraction. (A) Extraction
of primary canines to
provide space for incisor
alignment; (B) Extraction
of primary first molars
when 1⁄2–2⁄3 of first
premolar root is formed;
(C) Extraction of first
premolars for permanent
canine eruption.
deciduous first molars, and (iii) extraction of first premolar.
Each stage accomplishes a specific purpose.

Removal of Deciduous Canines
1. With deciduous canine exfoliation or removal, the
immediate purpose is to permit the eruption and
optimal alignment of the lateral incisors.
2. Improvement in the position of the central incisors
may reasonably be expected.
deciduous canine exfoliation deciduous canine removal

3. Prevention of the eruption of the maxillary lateral incisors in
lingual crossbite or the mandibular incisors in lingual malposition
is a primary consideration. But this improvement is gained at the
expense of space for the permanent canines.

4. Vitally important is the fact that correct lateral incisor
position prevents the mesial migration of the canines
into severe malpositions that will require concerted
mechanotherapy later.

5. In the maxillary arch, the first premolars erupt
uniformly ahead of the canines. In the mandibular arch,
it is statistically less predictable.
the first premolars

Sometimes, the orthodontist will try to maintain the mandibular
deciduous canines somewhat longer hoping to retard
the eruption of the permanent canines, while the first
premolars take advantage of the edentulous area created by
premature removal of the mandibular first deciduous molars.

It is desired by most orthodontists embarking on a serial
extraction procedure that the first premolars will erupt as
soon as possible and ahead of the canines so the premolars
may be removed, if necessary. This frequently does not
happen (Fig. 31.7).
In the upper laminographic view, the sequence is most desirable, with all four premolars erupting ahead
of canines. In the bottom view, maxillary first premolars are clearly ahead of canines, mandibular canines
are ahead of first premolars leading to lack of space for premolars.

As the experienced clinician knows, there is little evidence
that the eruption sequence can be changed, anyway. The too
early removal of mandibular deciduous first molars may very
well delay the eruption of the first premolars, as a dense layer
of bone fills in over them after the deciduous tooth removal.
Panoramic radiograph of a
20-year-old male with the
Hyper IgE condition. The
figure shows deviations in
the normal
eruption pattern as
premolars and two canines
have fully formed
roots but have not erupted.

It is important to expedite(speed) the normal eruption of the
maxillary lateral incisors. Belated eruption and lingual
malposition of these teeth permit the maxillary canines to
migrate mesially and labially into the space that nature has
reserved for the lateral incisors.

These ‘high cuspids’, as the orthodontist often calls them, make
lingual crossbite of the maxillary lateral incisors more certain,
make orthodontic therapy more difficult and practically ensure
that the first premolars will ultimately have to be removed.
Remember, not all properly managed serial extraction cases
inevitably require permanent tooth sacrifice.

Timing of Extraction
Generally speaking, these teeth are removed between 8
and 9 years of age in patients with an average
developmental pattern.

Removal of the First Deciduous Molars
Purpose of Extraction
1. By this procedure, the orthodontist hopes to accelerate the
eruption of the first premolar teeth ahead of the canines, if at
all possible.
2. This is particularly ‘touch and go’ in the mandibular arch
where the normal sequence so often is for the canine to erupt
ahead of the first premolar. The maneuver is seldom
successful in the lower arch as has been indicated already.

3. In Class I malocclusions especially, the first premolar may be
partially impacted between the permanent canine and the still
present second deciduous molar. Hence, the dentist may vary
the first procedure of removing all four deciduous canines, as
outlined above, and remove the first deciduous molars in the
lower arch to tip the eruption scales in the direction of the first
premolar.

4. There are times when the orthodontist, while removing
first deciduous molars, must consider the
possibility of enucleating the unerupted first premolars (usually
in the lower arch) to achieve the optimal benefits of the serial
extraction procedure. This is a most hazardous step and
obviously requires keen diagnostic acumen. Yet in the properly
chosen case, the autonomous adjustment and marked
improvement in alignment following this step can be most
gratifying to both the patient and the orthodontist .

Laminographic views of severe Class I malocclusion with multiple serial extraction clues (ectopic
eruption, drift, premature loss, shift to one side, flaring, etc.). Deciduous teeth have been removed in
the middle left picture, and four first premolars are now out in the bottom left view, enucleated
because of the ‘logjam’ seen in the middle left view. In the three right-hand views, eruption is
proceeding, with significant autonomous improvement. The partially impacted lower second molar in
the middle right view was surgically uprighted . The lower right view shows complete adjustment.

Laminographic views of severe Class I malocclusion with multiple serial extraction clues (ectopic
eruption, drift, premature loss, shift to one side, flaring, etc.). Deciduous teeth have been removed in
the middle left picture, and four first premolars are now out in the bottom left view, enucleated
because of the ‘logjam’ seen in the middle left view. In the three right-hand views, eruption is
proceeding, with significant autonomous improvement. The partially impacted lower second molar in
the middle right view was surgically uprighted . The lower right view shows complete adjustment.

Laminographic views of severe Class I malocclusion with multiple serial extraction clues (ectopic
eruption, drift, premature loss, shift to one side, flaring, etc.). Deciduous teeth have been removed in
the middle left picture, and four first premolars are now out in the bottom left view, enucleated
because of the ‘logjam’ seen in the middle left view. In the three right-hand views, eruption is
proceeding, with significant autonomous improvement. The partially impacted lower second molar in
the middle right view was surgically uprighted . The lower right view shows complete adjustment.

5. Where the canines have erupted prior to the first premolars
in the mandibular arch, the convex mesial coronal portion of
the second deciduous molar may interfere with first premolar
eruption. In such cases, it is necessary to remove the second
deciduous molars. No firm rule can be developed here, and
each case is judged on its merits with proper diagnostic
criteria.
Upper and lower eruption sequence

Timing of Extraction
Generally speaking, the first deciduous molars are removed
approximately 12 months after the deciduous canines. Thus,
first deciduous molar removal would be between 9 and 10
years of age in the average developmental pattern.
It would vary from child to child and might sometimes be
done earlier in the mandible than in the maxilla, to enhance
the early eruption of the first premolars.

Timing is really not so critical for the removal of the first
deciduous molars. There are those who might prefer to
remove the remaining deciduous canines and first
deciduous molars at the same time, somewhere between
81⁄2 and 10 years of age.

Removal of the Erupting First Premolars
Word of Caution
Before this is done, all diagnostic criteria must again be evaluated. The
status of the developing third molars must be determined. It can be a
serious mistake to remove four first premolars, only to find that the third
molars are congenitally missing and there would have been enough space
without premolar removal.
Extraction of maxillary and mandibular permanent premolars and extraction of
deciduous maxillary second molars and eruption of permanent maxillary second premolars.
The mandibular anterior segment is well aligned.

Purpose of Extraction
1. If the diagnostic study confirms the inherent arch length deficiency, the
purpose of this step is to permit the canine to drop distally into the space created
by the extraction. If the procedure has been carried out correctly and the timing
has been right, it is a most rewarding experience after the removal of the first
premolars to observe the bulging canine eminences move distally on their own
into the premolar extraction sites .
A series of laminographic views, showing autonomous adjustment
possible with properly guided serial extraction procedures. Note
significant uprighting of canines as they move back into space created in
the first premolar area.

2. As indicated previously, sometimes it becomes necessary to
remove the mandibular second deciduous molars to permit the
first premolars to erupt. This is a more conservative step and is
usually preferable to enucleation. But it increases the chances
for need of a holding arch to prevent undue loss of space and
excessive mesial drift of the first permanent molar .
Nance holding arch, with orthodontic bands on first permanent molars. As drawing shows, first premolars have been
removed, permitting canine teeth to drop distally into the spaces created. The holding arch prevents mesial migration of
molars in severe discrepancy cases.

Timing of Extraction
Generally speaking, if the decision has definitely been made that it is
necessary to remove the first premolar teeth, the sooner this is done
the better the self-adjustment. It serves no purpose to wait for full
eruption of the premolar teeth.
The deciduous first molars
have been extracted.
Extraction of maxillary and mandibular permanent premolars and extraction of
deciduous maxillary second molars and eruption of permanent maxillary second
premolars.
The mandibular anterior segment is well aligned.

TWEED’S TECHNIQUE OF SERIAL EXTRACTIONAccording to
Tweed, when discrepancy exists between arch length and tooth
material, serial extraction is initiated around 71⁄2 –81⁄2 years of
age
Tweed’s method of serial
extraction. (A) Severe
space deficiency with
incisor crowding; (B)
Extraction of primary first
molar to encourage early
eruption of first premolar;
(C and D) Extraction of
primary canine and first
premolar for permanent
canine eruption.

• At approximately 8 years, all deciduous first molars are
extracted to hasten the eruption of first premolars.
• Extraction of first premolars and deciduous canines is done
simultaneously 4–6 months prior to eruption of permanent
canines, when premolars are about the level of alveolar bone
crest.

• When the permanent canines erupt they migrate posteriorly into
good position.
• Any irregularities in mandibular incisors also get corrected
spontaneously by the normal muscular forces.
• The residual space is closed by drifting and tipping of the
posterior teeth unless full appliance therapy is implemented.

Nance method is similar to Tweed’s method. The deciduous
first molars are extracted before 6–12 months before its
normal exfoliation time, followed by first premolars and
deciduous canines.
Nance Method of Serial Extraction

DISADVANTAGES/PROBLEMS IN SERIAL
EXTRACTION
1. The timing of tooth removal may be important. It is not always
possible to see the patient when we want to or to remove specific
teeth at the optimal time for the greatest improvement.
2. The serial extraction patient comes in with better adjustment in
the maxillary than in the mandibular arch.

3. Almost always, there is the ‘ditch’ between the permanent canine
and the second premolar in the mandibular arch. The roots of the
maxillary canine and maxillary second premolar parallel themselves
fairly well with autonomous adjustment, whereas this is almost never
true in the mandibular arch. The long axes of the teeth converge in
the maxilla.ry arch
Axial inclinations of maxillary teeth (top) converge
apically while they diverge apically in the mandibular
arch (bottom). This permits self-paralleling of
maxillary canines and second premolars, but
interferes with root parallelism in the mandibular arch,
creating what the orthodontist calls ‘the ditch’. Thus,
appliances are almost always required to upright
mandibular teeth, regardless of the high level of self-
improvement in other malocclusion details.

The compensating curve and the occlusal surfaces of the
mandibular arch form a concave arc, so the long axes in the
mandibular buccal segments diverge. Thus, there is
automatic paralleling of the roots with the removal of the first
premolar in the maxillary arch.

On the contrary, the removal of the mandibular first premolar
allows the tipping together of the crowns, accentuating the ‘V’
or ‘ditch’. Seldom does the distance between the apex of the
mandibular canine and the apex of the mandibular second
premolar decrease on its own. It is necessary for the
orthodontist to resort to stringent appliance guidance to close
the space and upright the teeth .
the most ideal condition for successful serial extraction is a
Class I malocclusion with severe hereditary crowding, minimal overjet and
overbite, normal basal jaw relationships, and an orthognathic facial pattern or a
slight maxillomandibular dentoalveolar protrusion.

4. The ‘bite’ tends to close at least temporarily during the extraction
supervision period in most instances, particularly in cases with a
Class II tendency.
5. Sometimes there is a further reduction in arch length during the
period of guidance. The lower incisors, while aligning themselves,
may also become more upright (lingually inclined), which increases
the overbite tendency.

6. Occasionally, the removal of premolars does not stimulate the
distal migration of canines. Figure 31.13 shows a case in which
one maxillary canine remained impacted in a horizontal position.
In such instances, the change in treatment plan requires
uncovering the canine surgically, placing some sort of guiding
appliance and literally pulling the tooth down into normal
position.
Canine on upper left is impacted, despite serial extraction procedures. Stringent and protracted
mechanotherapy was required to achieve results shown in bottom view.

7. Treatment need to be continued with fixed appliance
mechanotherapy as this is not a definitive treatment.
8. Need for patient cooperation and prolonged follow-up.
9. Not suitable for skeletal cases.

Beforehand, it should be said that there is no single procedure
for serial extraction. A provisional diagnostic decision is the
best choice. Serial extraction is a long-term guidance program
and, therefore, it becomes necessary to re-evaluate and
modify provisional decisions many times.
Serial extraction without orthodontic treatment
only partial correction occurs after extractions
in other patients.

Reference