Long term stability of treatment outcome after fixed orthodontic treatment with or without premolar extraction

Abstract

Purpose
To evaluate and compare the long term stability of treatment outcome in patients treated with fixed orthodontic treatment with and without premolar extractions.

Material and methods
Fifty five debonded patients (35 females and 20 males) with complete pre-treatment (T0) and post-treatment (T1) records with at least 3 years of post-retention (T2) were included in the study. These patients were divided into two groups; Extraction group comprising of 30 patients who had undergone 4 premolar extractions and non-extraction group had 25 patients. Long term stability of post-treatment occlusion was assessed with Little’s irregularity index, intercanine width and ABO model grading system.

Results
The incisor irregularity score increased in both extraction and non-extraction groups from post-treatment (T1) to post-retention (T2) and the mean changes were statistically significant. The results of Mann–Whitney test for Little’s irregularity index and intercanine width showed no statistically significant differences between the extraction and the non-extraction groups at T1 to T2. The overall mean changes in the ABO variables showed no statistically significant differences (P > 0.05) from post-treatment (T1) to post-retention phase (T2) in extraction and non-extraction groups except interproximal contacts, which showed a statistically significant difference.

Conclusion
There was significant relapse in the alignment of maxillary and mandibular anterior teeth with a change in Little’s irregularity score, intercanine width and ABO scores from post-treatment to post-retention. The comparison of relapse in extraction and non-extraction groups did not show significant differences from T1 to T2. Therefore, similar relapse may be expected irrespective of treatment plan.

Full text

Original
article
Long
term
stability
of
treatment
outcome
after
fixed
orthodontic
treatment
with
or
without
premolar
extraction
Nameksh
Raj
Bhupali *,
Satinder
Pal
Singh,
Sanjeev
Verma,
Vinay
Kumar,
Raj
Kumar
Verma
Unit
of
Orthodontics
&
Dentofacial
Orthopaedics,
OHSC,
PGIMER
Chandigarh,
India
a
b
s
t
r
a
c
t
Purpose:
To
evaluate
and
compare
the
long
term
stability
of
treatment
outcome
in
patients
treated
with
fixed
orthodontic
treatment
with
and
without
premolar
extractions.
Material
and
methods:
Fifty
five
debonded
patients
(35
females
and
20
males)
with
complete
pre-treatment
(T0)
and
post-treatment
(T1)
records
with
at
least
3
years
of
post-retention
(T2)
were
included
in
the
study.
These
patients
were
divided
into
two
groups;
Extraction
group
comprising
of
30
patients
who
had
undergone
4
premolar
extractions
and
non-extraction
group
had
25
patients.
Long
term
stability
of
post-
treatment
occlusion
was
assessed
with
Little’s
irregularity
index,
intercanine
width
and
ABO
model
grading
system.
Results:
The
incisor
irregularity
score
increased
in
both
extraction
and
non-extraction
groups
from
post-treatment
(T1)
to
post-retention
(T2)
and
the
mean
changes
were
statistically
significant.
The
results
of
Mann–Whitney
test
for
Little’s
irregularity
index
and
intercanine
width
showed
no
statistically
significant
differences
between
the
extraction
and
the
non-
extraction
groups
at
T1
to
T2.
The
overall
mean
changes
in
the
ABO
variables
showed
no
statistically
significant
differences
(P>0.05)
from
post-treatment
(T1)
to
post-retention
phase
(T2)
in
extraction
and
non-extraction
groups
except
interproximal
contacts,
which
showed
a
statistically
significant
difference.
Conclusion:
There
was
significant
relapse
in
the
alignment
of
maxillary
and
mandibular
anterior
teeth
with
a
change
in
Little’s
irregularity
score,
intercanine
width
and
ABO
scores
from
post-treatment
to
post-retention.
The
comparison
of
relapse
in
extraction
and
non-
extraction
groups
did
not
show
significant
differences
from
T1
to
T2.
Therefore,
similar
relapse
may
be
expected
irrespective
of
treatment
plan.
©
2019
Published
by
Elsevier
Ltd
and
The
Japanese
Orthodontic
Society.
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
8
August
2018
Received
in
revised
form
1
November
2018
Accepted
9
December
2018
Available
online
7
January
2019
Keywords:
Extraction
and
non-extraction
Stability
Little’s
irregularity
index
Arch
width
ABO-MGS
*
Corresponding
author
at:
Unit
of
Orthodontics
&
Dentofacial
Orthopaedics,
OHSC,
PGIMER
Chandigarh,
160012
India.
E-mail
addresses:
namekshrb@gmail.com
(N.R.
Bhupali),
drspsingh_chd@yahoo.com
(S.P.
Singh),
drsanjuverma@yahoo.com
(S.
Verma),
sonidrvinay16@gmail.com
(V.
Kumar),
drrajverma876@gmail.com
(R.K.
Verma).
https://doi.org/10.1016/j.odw.2018.12.001
1344-0241/©
2019
Published
by
Elsevier
Ltd
and
The
Japanese
Orthodontic
Society.
o
r
t
h
o
d
o
n
t
i
c
w
a
v
e
s
7
8
(
2
0
1
9
)
2
6
–
3
2
Available
online
at
www.sciencedirect.com
ScienceDirect
jo
u
rn
al
h
om
ep
age:
w
ww
.elsevier
.co
m
/loc
ate/o
d
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1.
Introduction
The
most
desired
goal
of
orthodontic
treatment
is
the
long-term
stability
of
treatment
outcome.
The
comprehensive
orthodontics
comprises
of
two
main
therapeutic
approaches
for
management
of
dentoalveolar
malocclusion:
extraction
and
non-extraction.
There
is
still
controversy
regarding
the
orthodontic
stability
between
extraction
and
non-extraction
treatment
decision.
This
becomes
more
important
in
borderline
cases
[1].
Erdinc
et
al.
[2]
evaluated
relapse
of
anterior
crowding
with
a
post-retention
period
of
4
years
and
11
months
and
found
no
statistically
significantdifferences inlong term stabilityamong the extraction
and
non-extraction
groups.
A
study
by
Janson
et
al.
[3]
reported
the
similar
results
with
nodifference in
post-retention
stability in
extraction
and
non-extraction
treatment.
Myser
et
al.
[4]
found
significantly
greater
malalignment
in
patients’
with
extractions
than
those
treated
without
extractions
at
the
post-retention
phase.
Therefore,
from
the
aforementioned
literature,
different
results
may
be
expected
in
the
relapse
patterns
of
patients
treated
with
or
without
extractions.
Several
indices
have
been
used
to
evaluate
the
treatment
outcome
in
orthodontics.
Little’s
irregularity
index
[5]
is
the
most
commonly
used
index
to
compare
relapse
in
anterior
teeth.
The
intercanine
width
is
the
most
commonly
used
transverse
dimensions
to
assess
the
post
treatment
stability
[8,14].
American
Board
of
Orthodontics
in
1998
developed
a
more
objective
system
to
assess
the
final
outcome
of
the
comprehensive
orthodontic
treatment
[6].
The
long
term
post
treatment
stability
of
cases
treated
by
fixed
orthodontics
is
variable
and
unpredictable
in
both
extraction
and
non-extractioncases. Therefore, the purposeof this retrospective
study
was
to
assess
and
compare
the
long
term
stability
of
occlusion
after
comprehensive
orthodontic
treatment
with
and
without
extractions.
2.
Methods
The
appropriate
ethical
approval
of
the
present
study
was
obtained
from
ethical
committee
of
institution
(NK/1786/MDS/
13589-90)
(Post
graduate
institute
of
medical
education
and
research).
The
sample
consisted
of
patients
treated
with
comprehensive
orthodontic
treatment
with
extraction
or
non-
extraction.
All
the
patients
included
in
the
study
had
Angle’s
Class
I
Dewey’s
Type
1
malocclusion
and
had
completed
retention
period
of
three
years
post-treatment.
The
patients
had
skeletal
Class
I
bases
with
moderate
crowding
(5–7mm).
After
the
case
discussion
in
the
department,
they
were
assigned
to
the
extraction
and
non-extraction
treatment
groups
on
the
basis
of
facial
profile
and
soft
tissue
cephalo-
metric
parameters.
The
retention
protocol
for
all
the
cases
involved
modified
Begg’s
retainer
in
the
maxillary
arch
and
lingual
bonded
retainer
in
the
mandibular
arch.
The
patients
included
were
examined
for
no
abnormal
habits
like
tongue
thrusting,
thumb
sucking.
The
patients
with
incomplete
pre-
treatment
and
post-treatment
records,
missing
or
impacted
teeth,
having
congenital
craniofacial
anomalies
such
as
cleft
lip
and
palate
and
syndromic
condition,
previous
history
of
orthodontic
treatment/orthognathic
surgery
and
debonded
before
the
finishing
stage,
were
excluded.
A
total
of
126
debonded
patients
met
the
inclusion
criterion
and
an
attempt
was
made
to
recall
them
telephonically
for
post
retention
records.
The
final
sample
of
the
study
comprised
of
55
patients
(35
females
and
20
males).
All
the
patients
were
wearing
retainer
in
the
maxillary
arch
and
had
bonded
retainer
in
the
mandibular
arch
at
the
time
record
taking.
The
impressions
for
these
patients
were
made
with
alginate
and
post-retention
study
models
were
prepared.
The
patients
were
then
divided
into
two
groups;
Extraction
group
comprised
of
30
patients
who
had
undergone
4
premolars
extraction
and
Non-Extraction
group
had
25
patients.
All
the
patients
were
treated
with
0.018in.
slot
size
preadjusted
fixed
orthodontic
appliances.
2.1.
Study
model
measurements
Little’s
irregularity
index,
intercanine
width
and
American
Board
of
Orthodontics
model
grading
system
(ABO-MGS)
were
used
to
compare
the
study
models
at
three
different
time
periods
i.e.
pre-treatment
(T0),
post-treatment
(T1)
and
post-
retention
(T2).
The
alignment
of
the
maxillary
and
mandibular
arches
were
assessed
with
Little’s
irregularity
index
[5]
as
measure-
ment
(in
millimetres)
of
the
linear
displacements
of
anatomic
contact
points
of
adjacent
teeth
of
both
maxillary
and
mandibular
anterior
teeth
with
the
help
of
digital
vernier
calliper
(573-621,
Mitutoyo,
Japan)
from
the
mesial
contact
point
of
the
left
canine
to
the
mesial
contact
point
of
the
right
canine.
The
sum
of
these
five
displacements
represented
the
relative
degree
of
anterior
irregularity.
Intercanine
width
was
measured
as
the
distance
between
cusp
tips
of
contralateral
canines.
The
following
7
parameters
were
assessed
as
American
Board
of
Orthodontics
Model
Grading
System
using
the
ABO
measuring
gauge:
alignment,
marginal
ridges,
buccolingual
inclination,
occlusal
relationships,
occlusal
contacts,
overjet
and
interproximal
contacts
[7].
2.2.
Intra
examiner
reliability
The
measurements
were
made
by
a
single
examiner
trained
in
use
of
Little’s
irregularity
index,
intercanine
width
and
ABO
model
grading
system.
The
intra-examiner
reliability
was
determined
for
little’s
irregularity
index,
intercanine
width
and
ABO
grading
system.
The
measurements
of
10
patients
were
repeated
after
3
weeks
by
the
same
examiner.
Intra-
observer
reliability
was
calculated
by
paired
t-test.
2.3.
Statistical
analysis
The
continuous
data
was
presented
as
MeanS.D.
Normality
of
quantitative
data
was
checked
by
measures
of
Kolmogorov
Smirnov
tests
of
normality.
For
time
related
variables
of
skewed
data
Wilcoxon
Signed
rank
test
was
applied.
Paired
t-
test
was
used
to
assess
the
changes
in
normally
distributed
data
from
pre-treatment
to
post-retention.
The
changes
from
post-treatment
to
post-retention
in
extraction
and
non-
extraction
groups
were
compared
using
Mann–Whitney
U-
test.
Pearson
correlation
coefficient
or
Spearman
correlation
coefficient
was
used
to
determine
the
correlation
among
o
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2
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3
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27

different
parameters
used
for
post-retention
stability
and
relapse
in
extraction
and
non-extraction
groups.
All
the
statistical
tests
were
two
sided.
The
P
value
of<0.05
was
considered
as
level
of
statistical
significance.
3.
Results
The
results
of
the
intra-examiner
reliability
did
not
show
statistically
significant
difference
in
the
measurements
made
for
Little’s
irregularity
index,
intercanine
width
and
ABO
model
grading
system,
respectively
(P>0.05).
The
important
characteristics
of
the
sample
under
investigation
are
pre-
sented
in
Table
1.
The
average
age
of
the
total
sample
was
15.28
years
and
average
post
retention
period
was
51.45
months.
The
average
age
of
the
patients
in
the
extraction
group
was
16.67
years
and
14
years
in
the
non-extraction
group.
The
post
retention
period
was
49.90
months
and
54
months
for
the
extraction
group
and
the
non-extraction
groups,
respectively.
Though
the
number
of
females
enrolled
in
the
study
were
more
than
male
patients,
the
male
to
female
ratio
showed
non-significant
differences.
The
Table
2
presents
the
comparison
of
mean
changes
in
the
incisor
irregularity
of
the
maxillary
and
mandibular
arch
at
T0–T1
and
T1–T2
between
the
extraction
and
the
non-
extraction
groups.
The
overall
mean
change
in
the
Incisor
irregularity
of
the
total
sample
in
the
maxillary
and
mandibu-
lar
arch
showed
decrease
from
T0-T1,
while
a
slight
increase
was
noted
from
T1
to
T2
and
these
changes
are
statistically
highly
significant
(P<0.01).
The
extraction
and
non-extraction
groups
showed
similar
Incisor
irregularity
changes
in
the
maxillary
and
mandibular
arch.
The
results
of
Mann–Whitney
test
showed
no
statistically
significant
difference
(P>0.05)
between
maxillary
and
mandibular
arch
or
the
extraction
and
non-extraction
groups.
The
comparison
of
mean
differences
in
the
intercanine
width
between
the
extraction
and
the
non-extraction
groups
as
shown
in
Table
3.
In
overall
sample,
the
increase
in
intercanine
width
in
maxillary
and
mandibular
arch
from
T0
to
T1
showed
a
statistically
highly
significant
difference
(P<0.01),
while
from
T1
to
T2
the
decrease
was
statistical
non-significant
(P>0.05).
There
was
statistically
highly
significant
(P<0.01)
increase
in
maxillary
intercanine
width
from
T0
to
T1
in
extraction
and
non-extraction
group
shown
in
Table
3.
The
decrease
in
intercanine
width
in
maxilla
from
T1
to
T2
in
extraction
group
was
statistically
non-significant
(P>0.05)
and
in
the
non-
extraction
group,
was
statistically
significant.
The
increase
in
the
intercanine
width
in
the
mandibular
arch
from
T0
to
T1
and
decrease
from
T1
to
T2
was
statistically
significant
(P<0.05)
in
the
extractiongroup.
The
mean
increase
in
intercanine
width
in
non-extraction
group
from
T0toT1
showeda
statistically
highly
significant
value
(P<0.01)
while,
the
decrease
from
T1
to
T2
were
statistically
non-significant
(P>0.05).
The
comparison
of
mean
differences
in
the
intercanine
width
between
the
extraction
and
the
non-extraction
groups
by
Mann–Whitney
test
showed
no
statistically
significant
differences
(P>0.05).
Table
1
–
Gender
wise
distribution,
mean
age
and
post-retention
period
of
extraction
and
non-extraction
patients.
Treatment
plan
Sample
size
Males
Females
Post-retention
period
(in
months)
Mean
ageSD
(in
years)
Overall
mean
age
(in
years)
P
value
Male
(n= 20)
Female
(n= 35)
Extraction
30
10
20
49.9011.40
16.673.17
16.004.48
16.244.02
0.67
(NS)
Non-extraction
25
10
15
54.0007.61
14.003.00
13.452.91
13.702.89
0.65
(NS)
Total
55
20
35
51.4510.25
15.343.09
14.723.70
15.283.81
0.63
(NS)
NS= Non-significant.
Table
2
–
Comparison
of
the
mean
change
in
the
incisor
irregularity
of
maxillary
and
mandibular
arches
at
pre-treatment
(T0),
post-treatment
(T1)
and
post-retention
phase
(T2)
in
extraction
and
non-extraction
groups.
Incisor
irregularity
Treatment
plan
T0
T1
T2
(T0–T1)
(T1–T2)
Extraction
versus
non-
extraction
(T0–T1)
(T1–T2)
Mean
change
P
value
Mean
change
P
value
P
value
P
value
Maxillary
Extraction
(n= 30)
3.641.17
1.270.52
1.580.50
2.361.14
0.000
***
0.300.53
0.002
**
0.544
(NS)
0.339
(NS)
Non-extraction
(n=25)
3.601.35
1.050.22
1.500.61
2.551.32
0.000
***
0.450.60
0.004
**
Total
(n= 55)
3.621.23
1.190.44
1.550.54
2.431.20
0.000
***
0.360.56
0.000
***
Mandibular
Extraction
(n= 30)
3.301.31
1.240.44
1.550.51
2.061.30
0.000
***
0.300.53
0.002
**
0.100
(NS)
0.403
(NS)
Non-extraction
(n=25)
2.650.81
1.250.44
1.450.51
1.400.88
0.000
***
0.200.41
0.042
*
Total
(n= 55)
3.061.18
1.250.43
1.510.50
1.811.19
0.000
***
0.260.49
0.000
**
*
P= 0.05.
**
P= 0.01.
***
P= 0.001.
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The
descriptive
and
comparative
statistics
of
the
variables
assessed
by
the
ABO
model
grading
system
are
shown
in
Tables
4
and
5.
The
mean
changes
in
the
total
sample
for
the
alignment,
marginal
ridges,
buccolingual
inclination,
occlusal
relationship,
occlusal
contacts,
overjet
were
statistically
non-
significant
(P>0.05)
while
change
in
interproximal
contacts
was
statistically
highly
significant
(P<0.01).
In
the
extraction
group,
the
mean
change
in
the
alignment
from
post-treatment
(T1)
to
post-retention
(T2)
showed
a
statistically
significant
difference
(P<0.05),
while
change
in
all
other
variables
and
total
score
was
statistically
non-significant
(P>0.05).
In
the
non-extraction
group,
mean
change
in
alignment,
marginal
ridges
buccolingual
inclination,
occlusal
relationship,
occlusal
contacts,
overjet
and
total
score
showed
no
statistically
significant
changes
(P>0.05)
while
the
change
in
interproxi-
mal
contacts
was
statistically
highly
significant
(P<0.01).
4.
Discussion
It
has
been
observed
clinically
that
the
problem
of
relapse
is
common
in
both
extraction
and
non-extraction
cases.
The
stability
of
results
and
amount
of
relapse
in
extraction
and
non-extraction
cases
are
still
debatable
[2].
The
little’s
irregularity
index
and
intercanine
width
had
been
commonly
used
in
various
studies
to
compare
the
stability
of
post
retention
results
in
extraction
and
non-extraction
treatment
and
hence
these
parameters
were
used
in
this
study
so
that
results
could
be
compared
[2,3,8,9].
The
ABO
system,
one
of
the
most
detailed
and
objective
indices
in
use
in
the
present
times
was
used
to
evaluate
the
patients’
final
occlusion
and
compare
the
post-treatment
stability
and
relapse
in
extraction
versus
non-extraction
treatment
therapy
[6,7].
The
assessment
of
post-treatment
to
post-retention
changes
on
the
study
models
by
various
analysis
show
definite
occlusal
changes.
The
overall
mean
change
in
the
irregularity
score
in
both
extraction
and
a
non-extraction
group
from
T1
to
T2
showed
statistically
significant
relapse.
The
mean
change
in
the
maxillaryirregularityscorefromT1toT2 in extractiongroup
was
lower
than
the
non-extraction
group.
A
study
by
Kahl-
Nieke
et
al.
[10]
and
Myser
et
al.
[4]
found
more
incisor
irregularity
in
the
cases
treated
with
extraction
treatment
plan,
while
Uhde
et
al.
[11]
and
Paquette
et
al.
[1]
found
greater
amounts
of
relapse
in
the
non-extraction
patients.
Freitas
et
al.
[12],
Francisconi
et
al.
[13]
and
Canuto
et
al.
[14]
reported
a
significant
relapse
in
the
maxillary
anterior
segment
at
the
post-retention
period
in
the
cases
treated
by
non-extraction
treatment
plan.
The
mandibular
incisor
irregularity
increased
from
T1
to
T2
in
the
extraction
and
non-extraction
groups
showing
the
relapse
in
both
the
groups.
But,
the
increase
was
smaller
than
the
study
conducted
by
Artun
et
al.
[15]
This
study
also
showed
mandibular
incisor
irregularity
at
T1–T2
in
the
extraction
group
was
slightly
higher
(value)
than
the
non-
extraction
group
as
seen
in
the
studies
done
by
Francisconi
et
al.
[13]
and
Zafarmand
et
al.
[16],
suggesting
of
slightly
more
relapse
in
the
extraction
cases.
The
comparison
of
incisor
irregularityshowedthat
a
comparableamount of relapse occurs
in
the
anterior
alignment
from
the
post-treatment
to
post-
retention
phase
in
the
extraction
and
non-extraction
similar
to
the
observations
of
the
various
previous
studies
[13,15,17–19].
Table 3 –Comparison of the mean change in the intercanine width (in mm) of maxillary and mandibular arches at pre-treatment (T0), post-treatment (T1) and post-retention
phase (T2) in extraction and non-extraction groups.
Intercanine width (in mm) Treatment plan T0 T1 T2 (T0–T1) (T1–T2) Mann–Whitney Test
(T0–T1) (T1–T2)
Mean change P value Mean change P value P value P value
Maxillary Extraction (n= 30) 34.494.36 35.89 2.65 35.96 2.64 1.40 4.71 0.102 (NS) 0.441.23 0.838 (NS) 0.080 (NS) 0.097 (NS)
Non-extraction (n= 25) 32.892.12 35.50 1.81 34.59 2.46 2.62 1.87 0.000
***
0.981.95 0.037
*
Total (n= 55) 33.893.74 35.75 2.36 35.45 2.63 1.85 3.92 0.001
**
0.391.59 0.075 (NS)
Mandibular Extraction (n= 30) 26.242.34 27.67 1.38 27.30 1.60 1.44 2.29 0.001
**
0.380.82 0.014
*
0.869 (NS) 0.653 (NS)
Non-extraction (n= 25) 26.101.62 27.44 2.10 27.14 2.27 1.34 1.84 0.005
**
0.322.32 0.54 (NS)
Total (n= 55) 26.182.08 27.58 1.67 27.24 1.86 1.40 2.11 0.000
***
0.351.55 0.105 (NS)
*
P=0.05.
**
P=0.01.
***
P=0.001.
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29

In
the
extraction
group,
the
maxillary
and
mandibular
intercanine
width
increased
from
pre-treatment
(T0)
to
post-
treatment
(T1)
in
accordance
to
the
past
studies
[1,2,8,10,11,14,15,20–24].
However,
the
increase
was
statisti-
cally
non-significant
in
the
maxillary
arch
(P>0.05)
and
statistically
significant
(P<0.05)
in
the
mandibular
arch
which
is
in
accordance
with
the
studies
of
Paquette
et
al.
[1],
Erdinc
et
al.
[2]
and
de
Almeida
et
al.
[8].
The
mandibular
intercanine
width
decreased
from
T1
to
T2
suggestive
of
relapse
but
decrease
was
not
to
pretreatment
value.
McReynolds
and
Little
[20],
Paquette
et
al.
[1],
Kahl-nieke
et
al.
[10]
and
Erdinc
et
al.
[2]
also
reported
the
same
findings
whereas
Uhde
et
al.
[11]
reported
a
decrease
in
the
mandibular
intercanine
width
more
than
the
pre-treatment
value.
In
the
non-extraction
group
there
was
an
increase
in
intercanine
width
from
T0
to
T1
in
maxillary
and
mandibular
arches.
The
decrease
in
intercanine
width
from
T1
to
T2
in
the
maxillary
arch
was
statistically
significant
(P<0.05)
showing
relapse
after
the
treatment;
while
in
mandibular
arch
change
was
statistically
non-significant
difference
(P>0.05)
sugges-
tive
of
stable
mandibular
arch
at
the
post-retention
stage.
The
studies
by
Motamedi
et
al.
[23],
Erdinc
et
al.
[2]
and
Freitas
et
al.
[12]
showed
a
statistically
significant
decrease
in
intercanine
width
at
the
post-retention
stage.
The
intergroup
comparison
between
extraction
and
non-extraction
showed
no
significant
differences
(P>0.05)
in
relapse
in
the
maxilla
and
mandible
from
T1
to
T2.
The
present
study
supported
the
findings
of
various
other
studies
[2,18,21,22,25]
that
also
reported
no
significant
differences
in
relapse
between
the
extraction
and
non-extraction
treatment
plan.
The
ABO
measurements
for
variables
of
alignment
and
marginal
ridges
scored
the
highest
in
the
extraction
and
non-
extraction
group
respectively
at
post-treatment
(T1).
Cook
et
al.
[26]
also
reported
the
highest
score
in
the
marginal
ridge
discrepancy
in
the
University
treated
patients,
while
higher
score
for
occlusal
contacts
in
the
patients
treated
at
the
private
clinic.
Wes
Fleming
et
al.
[27]
reported
the
alignment
variable
as
highest
contributing
factor
in
the
ABO
score
in
the
non-
extraction
group.
The
present
study
showed
alignment
variable
scored
maximum
in
the
extraction
group
that
may
be
because
their
study
did
not
compare
the
extraction
and
non-extraction
subjects.
Occlusal
contacts
scored
the
highest
points
in
the
study
by
Farhadian
et
al.
[28]
in
both
the
extraction
and
non-extraction
group
and
they
were
the
second
highest
contributing
variable
of
the
ABO
score
in
the
study
by
Wes
Fleming
et
al.
[27]
which
is
in
contradiction
to
the
present
study.
The
assessment
by
ABO
suggested
relapse
tendency
for
alignment
in
extraction
group
but
it
was
non-significant
in
the
non-extraction
group
due
to
difference
in
the
severity
of
pretreatment
crowding.
Marginal
ridges
variable
improved
in
extraction
due
to
settling
not
evident
in
non-extraction
group.
The
buccolingual
inclination,
occlusal
relationship
and
overjet
except
the
variable
of
interproximal
contacts
showed
non-
significant
relapse
in
both
the
groups.
The
total
ABO
scores
in
both
the
groups
were
non-significant
(P>0.05).
These
findings
indicated
that
occlusion
remained
stable
over
a
period
of
two
years
after
the
post-treatment
and
there
was
no
difference
between
the
extraction
and
non-extraction
treatment
plan.
The
findings
are
in
agreement
with
the
study
of
Anthopoulou
Table 4 –Descriptive statistics of the ABO variables and total ABO scores at post-treatment (T1) and post-retention (T2) interval based on treatment plan.
ABO variable treatment
plan
Alignment Marginal ridges Buccolingual
inclination
Occlusal relationship Occlusal contacts Overjet Interproximal
contacts
Total score
T1 T2 T1 T2 T1 T2 T1 T2 T1 T2 T1 T2 T1 T2 T1 T2
Extraction (n=30) 5.27 3.06 6.182.82 5.27 2.52 5.06 2.26 2.39 2.15 2.85 1.56 4.73 3.56 4.09 3.19 1.00 1.58 0.88 1.95 5.183.97 5.644.32 1.941.92 1.64 1.58 25.79 9.13 26.33 7.78
Non- extraction (n=25) 5.753.13 6.10 2.45 6.20 2.40 5.70 2.77 2.65 1.81 2.95 1.32 4.45 4.54 4.954.50 1.151.87 1.001.34 4.10 3.18 4.85 3.56 1.70 1.84 0.20 0.52 26.00 10.54 25.75 10.54
Total (n= 55) 5.453.07 6.15 2.66 5.62 2.49 5.30 2.46 2.49 2.02 2.89 1.46 4.62 3.91 4.42 3.71 1.06 1.68 0.921.73 4.773.71 5.344.03 1.85 1.87 1.09 1.46 25.87 9.59 26.11 8.84
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et
al.
[29]
and
Akinci
Cansunar
and
Uysal
[30]
who
also
reported
that
an
acceptable
occlusion
could
be
achieved
at
the
post-
treatment
in
the
patients
treated
with
either
of
the
treatment
philosophy
i.e.
extraction
or
non-extraction
whereas
Farha-
dian
et
al.
[28]
found
that
the
patients
who
had
undergone
extraction
of
four
premolars
had
more
acceptable
final
occlusion.
5.
Conclusions
There
was
significant
relapse
in
crowding
of
maxillary
and
mandibular
anterior
teeth
in
both
extraction
and
non-
extraction
groups.
The
intercanine
width
of
maxillary
arch
decreased
in
the
non-extraction
cases
and
in
the
mandibular
arch
in
extraction
cases
post-retention.
Intercanine
width
of
maxillary
arch
in
extraction
cases
and
of
mandibular
arch
in
non-extraction
cases
was
found
to
be
stable
even
after
two
years
of
post-retention
period.
The
alignment
variable
of
ABO
model
grading
system
deteriorated
significantly
(0.912.48)
from
post-treatment
to
post-retention
in
the
extraction
group.
The
findings
of
the
study
indicated
that
post
treatment
tooth
positions
remained
stable
over
a
period
of
two
years
and
there
was
no
difference
between
the
extraction
and
non-extraction
treatment
plan.
Orthodontists
can
achieve
the
similar
long
term
stability
with
both
the
treatment
modalities.
Authors’
contributions
NRB
contributed
to
the
data
analysis
and
interpretation,
drafting
of
the
article,
and
critical
revision
of
the
article.
SPS
contributed
to
the
conception
and
design
of
the
work
and
critical
revision
of
the
article.
SV
contributed
to
the
design
and
drafting
of
the
article
and
critical
revision
of
the
article.
VK
and
RKV
contributed
to
interpretation
of
data
and
critical
revision
of
the
article.
All
authors
gave
the
final
approval
of
the
version
to
be
published.
Funding
No
funding
Ethics
approval
This
project
was
approved
by
the
ethical
committee
of
the
Post
Graduate
Institute
of
Medical
education
and
Research,
Chandigarh.
(NK/1786/MDS/13589-90)
Conflict
of
interest
The
authors
have
no
conflict
of
interest
to
disclose.
R
E
F
E
R
E
N
C
E
S
[1]
Paquette
DE,
Beattie
JR,
Johnston
Jr.
LE.
A
long-term
comparison
of
nonextraction
and
premolar
extraction
edgewise
therapy
in
borderline
Class
II
patients.
Am
J
Orthod
Dentofacial
Orthop
1992;102:1–14.
[2]
Erdinc
AE,
Nanda
RS,
Işıksal
E.
Relapse
of
anterior
crowding
in
patients
treated
with
extraction
and
nonextraction
of
premolars.
Am
J
Orthod
Dentofacial
Orthop
2006;129:775–84.
[3]
Janson
G,
Busato
MCA,
Henriques
JFC,
de
Freitas
MR,
de
Freitas
LMA.
Alignment
stability
in
Class
II
malocclusion
treated
with
2-
and
4-premolar
extraction
protocols.
Am
J
Orthod
Dentofacial
Orthop
2006;130:189–95.
[4]
Myser
SA,
Campbell
PM,
Boley
J,
Buschang
PH.
Long-term
stability:
postretention
changes
of
the
mandibular
anterior
teeth.
Am
J
Orthod
Dentofacial
Orthop
2013;144:420–9.
[5]
Little
RM.
The
irregularity
index:
a
quantitative
score
of
mandibular
anterior
alignment.
Am
J
Orthod
1975;68:554–63.
[6]
Casko
JS,
Vaden
JL,
Kokich
VG,
Damone
J,
James
RD,
Cangialosi
TJ,
et
al.
Objective
grading
system
for
dental
casts
and
panoramic
radiographs.
Am
J
Orthod
Dentofacial
Orthop
1998;114:589–99.
Table
5
–
Comparative
statistics
of
the
mean
changes
of
the
ABO
variables
and
total
ABO
scores
at
post-treatment
(T1)
and
post-retention
(T2)
interval
in
extraction
and
non-
extraction
groups.
Extraction
Non-extraction
Total
Extraction
versus
non
extraction
T1–T2
T1–T2
T1–T2
Mean
change
P
value
Mean
change
P
value
Mean
change
P
value
P
value
Alignment
0.912.48
0.037
*
0.352.89
0.633
(NS)
0.702.63
0.055
0.059
(NS)
Marginal
ridges
0.212.01
0.386
(NS)
0.501.73
0.221
(NS)
0.321.90
0.135
(NS)
0.224
(NS)
Buccolingual
inclination
0.462.48
0.078
(NS)
0.300.98
0.193
(NS)
0.401.23
0.060
0.063
(NS)
Occlusal
relationship
0.643.50
0.365
(NS)
0.502.09
0.270
(NS)
0.213.07
0.860
(NS)
0.625
(NS)
Occlusal
contacts
0.121.77
0.273
(NS)
0.151.61
0.935
(NS)
0.991.71
0.324
(NS)
0.608
(NS)
Overjet
0.463.40
0.510
(NS)
0.752.69
0.210
(NS)
0.573.12
0.228
(NS)
0.608
(NS)
Interproximal
contacts
0.302.17
0.392
(NS)
1.501.93
0.004
*
0.762.15
0.011
*
0.013
*
Total
score
0.557.83
0.543
(NS)
0.255.63
0.810
(NS)
0.801
(NS)
*
P=0.05.
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[7]
The
American
Board
of
Orthodontics
grading
system
for
dental
casts
and
panoramic
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