Preventive treatment of ectopically erupting maxillary permanent canines by extraction of deciduous canines and first molars: A randomized clinical trial


Alessandri Bonetti, G.; Zanarini, M.; Incerti Parenti, S.; Marini, I.; Gatto, M.Rosaria.

American Journal of Orthodontics and Dentofacial Orthopedics 139(3): 316-323

2011


In this research project, we aimed to compare the effectiveness of single (1 deciduous canine) and double (deciduous canine and first molar) extractions in subjects with retained maxillary permanent canines positioned palatally or centrally in the alveolar crest, at risk for root resorption of adjacent permanent teeth. Subjects at risk for canine impaction or resorptive situations were randomly assigned to 1 of 2 treatment modalities: single extraction (17 patients, 28 canines) or double extraction (20 patients, 37 canines). Thirty-one patients with 53 canines judged to be not at risk constituted the untreated control group. Panoramic radiographs were taken at the initial observation and after 18 months on average. Between-group statistical comparisons were carried out on the changes in canine inclination and sector location (measured on panoramic radiographs) and on the percentages of successful permanent canine eruptions. The double-extraction group showed significant improvements in the success rate and the intrabony position of the permanent canine, in terms of uprighting the canine's long axis with a crown movement in a distal direction. Concomitant deciduous canine and first molar extractions proved to be more effective as a preventive approach to promote eruption of retained maxillary permanent canines positioned palatally or centrally.

I
ORIGINAL
ARTICLE
C
E
A
1P
-
riP
Preventive
treatment
of
ectopically
erupting
maxillary
permanent
canines
by
extraction
of
deciduous
canines
and
first
molars:
A
randomized
clinical
trial
Giulio
Alessandri
Bonetti,
d
Matteo
Zanarini,
b
Serena
Incerti
Parenti,"
Ida
Marini,"
and
Maria
Rosaria
Gatto
d
Bologna,
Italy
Introduction:
In
this
research
project,
we
aimed
to
compare
the
effectiveness
of
single
(1
deciduous
canine)
and
double
(deciduous
canine
and
first
molar)
extractions
in
subjects
with
retained
maxillary
permanent
canines
positioned
palatally
or
centrally
in
the
alveolar
crest,
at
risk
for
root
resorption
of
adjacent
permanent
teeth.
Methods:
Subjects
at
risk
for
canine
impaction
or
resorptive
situations
were
randomly
assigned
to
1
of
2
treat-
ment
modalities:
single
extraction
(17
patients,
28
canines)
or
double
extraction
(20
patients,
37
canines).
Thirty-one
patients
with
53
canines
judged
to
be
not
at
risk
constituted
the
untreated
control
group.
Panoramic
radiographs
were
taken
at
the
initial
observation
and
after
18
months
on
average.
Between-group
statistical
comparisons
were
carried
out
on
the
changes
in
canine
inclination
and
sector
location
(measured
on
panoramic
radiographs)
and
on
the
percentages
of
successful
permanent
canine
eruptions.
Results:
The
double-extraction
group
showed
significant
improvements
in
the
success
rate
and
the
intrabony
position
of
the
permanent
canine,
in
terms
of
uprighting
the
canine's
long
axis
with
a
crown
movement
in
a
distal
direction.
Conclusions:
Concomitant
deciduous
canine
and
first
molar
extractions
proved
to
be
more
effective
as
a
preventive
approach
to
promote
eruption
of
retained
maxillary
permanent
canines
positioned
palatally
or
centrally.
(Am
J
Orthod
Dentofacial
Orthop
2011;139:316-23)
M
axillaiy
canine
impaction
is
often
encountered
in
orthodontic
clinical
practice";
the
frequency
ranges
from
1.7%
in
the
general
population
2
to
4.3%
in
the
population
of
subjects
referred
to
oral
surgery
or
orthodontics
departments.
4
Ectopically
or
nonerupting
canines
can
lead
to
resorp-
tion
of
the
roots
of
the
adjacent
permanent
teeth.
5-8
For
this
reason,
great
emphasis
should
be
given
to
the
early
detection
of
ectopic
eruption
and
potential
resorptive
situations,
when
preventive
measures
could
reduce
the
From
the
Department
of
Oral
Science,
Alma
Mater
Studiorum
University
of
Bologna,
Bologna,
Italy.
'Assistant
professor,
Department
of
Orthodontics.
b
Visiting
professor,
Department
of
Orthodontics.
`Resident,
Department
of
Orthodontics.
d
Assistant
professor
of
Medical
Statistics.
The
authors
report
no
commercial,
proprietary,
or
financial
interest
in
the
products
or
companies
described
in
this
article.
Reprint
requests
to:
Giulio
Alessandri
Bonetti,
Department
of
Orthodontics,
Alma
Mater
Studiorum,
University
of
Bologna,
Via
San
Vitale
59,
40125
Bologna,
Italy;
e-mail,
.
Submitted,
January
2009;
revised
and
accepted,
March
2009.
0889-5406/$36.00
Copyright
©
2011
by
the
American
Association
of
Orthodontists.
d
oi:10.1016/j.ajod
0.2009.03.051
316
severity
of
the
impaction
and,
if
possible,
encourage
the
eruption
of
the
canine,
thus
avoiding
possible
detrimental
effects.
5
'
7
'
8-13
For
early
diagnosis
of
ectopically
erupting
maxillary
canines,
both
clinical
(digital
palpation
screening
method)
and
radiographic
(eruption
angle
and
position
measured
on
panoramic
radiograph)
examinations
should
be
used.
1,3,5,6,9,10,14-17
Extraction
of
the
corresponding
deciduous
canines
has
been
recommended
as
a
preventive
treatment
to
promote
the
eruption
of
malposed
canines.
1,7,9,11-14
Previous
studies
found
that
between
50%
and
78%
of
palatally
displaced
maxillary
canines
reverted
to
a
normal
eruption
path
after
this
procedure!'"
1
'
12
The
additional
use
of
headgear
to
maintain
space
in
the
maxillary
dental
arch
resulted
in
an
increase
in
terms
of
successful
eruption
of
up
to
80%
of
the
canines,"
or
87.5%
of
the
subjects
treated,
12
with
a
significant
improvement
in
the
intraosseous
canine
position.
The
purpose
of
this
study
was
to
evaluate
the
effec-
tiveness
of
concomitant
extraction
of
the
deciduous
canine
and
first
molar
as
a
preventive
procedure
for
corresponding
retained
maxillary
permanent
canines
Randomized
(n=40)
1
Allocation
ECG
(deciduous
canines
extraction
alone)
Allocated
to
intervention
(n=20)
Received
allocated
intervention
ECMG
(deciduous
canines
and
first
molars
concomitant
extraction)
Allocated
to
intervention
(n=20)
Received
allocated
intervention
(n=20)
Did
not
receive
allocated
intervention
(n=0)
(n=20)
Did
not
receive
allocated
intervention
(n=0)
Lost
to
follow-up
(n=2)
Reasons=
moved
Follow-Up
Lost
to
follow-up
(n)
Analyzed
(n=17)
Excluded
from
analysis
(n=1)
Reasons:
poor
quality
panoramic
radiograph
at
final
observation
Analyzed
(n=20)
Excluded
from
analysis
(n=0)
Analysis
Alessandri
Bonetti
et
al
317
Fig
1.
CONSORT
flow
chart
of
participants
of
the
ECG
and
the
ECMG
through
each
stage
of
the
trial
(n,
number
of
patients).
positioned
palatally
or
centrally
in
the
alveolar
crest,
compared
with
extraction
of
only
the
deciduous
canine.
The
outcome
of
this
preventive
measure
was
evaluated
in
terms
of
improvement
of
the
intraosseous
position
of
the
displaced
canine
and
successful
eruption.
MATERIAL
AND
METHODS
in
this
randomized
clinical
trial,
we
analyzed
patient
records
collected
from
the
Department
of
Orthodontics,
University
of
Bologna,
in
Italy.
Inclusion
criteria
were
nonorthodontic
patients,
white
ancestry,
age
between
8
and
13
years,
maxillary
deciduous
canines
and
first
molars
in
the
dental
arch,
and
good-quality
panoramic
radiographs.
Exclusion
cri-
teria
were
previous
orthodontic
treatment,
premature
loss
of
the
maxillary
deciduous
canines
and
first
molars,
labially
retained
maxillary
permanent
canines,
aplasia
or
severe
hypoplasia
of
the
crown
of
the
maxillary
perma-
nent
lateral
incisors,
craniofacial
syndromes,
odonto-
mas,
cysts,
cleft
lip
or
palate
(or
both),
evidence
of
traumatic
injuries
to
the
permanent
incisors
or
to
the
face,
and
multiple
or
advanced
caries.
Seventy-one
sub-
jects,
with
123
canines,
fulfilled
all
criteria
and
were
included
in
this
study,
after
informed
consent
was
obtained
from
them
or
their
parents
or
guardians.
All
the
patients
were
examined
identically,
both
clinically
and
radiographically.
Because
we
considered
it
unethical
not
to
treat
patients
at
risk
for
ectopically
erupting
canines
or
poten-
tially
resorptive
situations,
canines
were
diagnosed
to
be
at
risk
by
at
least
1
of
the
following
clinical
and
radio-
graphic
criteria,
which
are
widely
accepted
in
the
interna-
tional
literature
and
among
practitioners.
1,3,5,6,9,10,14-17
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics
March
2011
Vol
139
Issue
3
318
Alessandri
Bonetti
et
al
Table
I.
Sample
distribution
by
sex
arid
age
ECG
ECMG
CG
Total
17
io
Male
9
9
16
34
8
Mean
age
(3)
9.8
10.2
9.0
The
clinical
criteria
were
absence
of
palpation
of
the
canine
bulge,
canine
bulge
palpable
palatally,
and
no
abnormal
inclination
or
rotation
of
the
adjacent
lateral
incisor
crown.
The
radiographic
criteria
were
inclination
of
the
canine
to
a
vertical
line
passing
through
the
midline
exceeding
25°
and
overlapping
of
the
canine
crown
with
the
root
of
the
permanent
lateral
incisor.
Among
the
71
subjects
(123
canines),
31
patients
(53
canines)
were
judged
to
be
at
no
risk.
They
had
no
treatment
and
constituted
the
control
group
(CG).
The
remaining
40
patients
(70
canines),
diagnosed
as
at
risk,
were
randomly
assigned
to
1
of
2
groups:
ECG
(20
patients,
33
canines),
having
extraction
of
only
the
deciduous
canine
corresponding
to
the
ectopically
erupting
maxillary
permanent
canine;
and
ECMG
(20
patients,
37
canines),
having
concomitant
extraction
of
the
deciduous
canine
and
first
molar
corresponding
to
the
ectopically
erupting
maxillary
permanent
canine.
Randomization
was
carried
out
by
using
a
block
design
and
computer-generated
random
numbers.
The
allocations
were
concealed
in
consecutively
numbered,
sealed
envelopes.
Three
patients
(5
canines)
in
the
ECG
did
not
complete
the
clinical
trial:
2
were
lost
to
follow-up
because
they
moved,
and
1
was
not
analyzed
because
of
a
poor-
quality
panoramic
radiograph
at
follow-up.
Consequently,
the
final
ECG
consisted
of
17
patients
and
28
canines.
A
CONSORT
flow
chart
of
participants
in
the
ECG
and
the
ECMG
through
each
stage
of
the
trial
is
shown
in
Figure
1.
Patient
distribution
by
sex
and
age
is
shown
in
Table
I.
Panoramic
radiographs
were
taken
at
initial
observa-
tion
(TO)
and
after
an
average
period
of
18
months
(T1)—
a
duration
that
has
already
proven
to
be
appropriate.
7
'
12
No
subject
in
either
treated
group
received
any
additional
orthodontic
or
surgical
therapy
beyond
the
extraction
of
the
deciduous
canine
(ECG)
or
the
concomitant
extraction
of
the
deciduous
canine
and
first
molar
(ECMG)
between
TO
and
T1.
For
all
patients,
the
panoramic
radiographs
were
taken
with
the
same
radiologic
apparatus
at
both
TO
and
T1,
under
standardized
conditions.
Since
different
studies
have
already
confirmed
the
reliability
of
angular
measurements
in
panoramic
radiographs,
each
panoramic
radiograph
was
digitized
with
a
scanner
(Expression
1680
Pro,
Epson,
Cinisello
40111Pubt
1-
Fig
2.
Inclination
of
the
maxillary
permanent
canine
(angle
cc)
is
measured
by
the
internal
angle
formed
by
the
major
axis
of
the
canine
and
the
midline,
according
to
the
method
of
Ericson
and
Kurol.
7
Balsamo,
Milano,
Italy),
and
the
angular
values
were
calculated
with
measurement
software
(LightningPlant
1.0.0,
ElleSoft,
Chieti,
Italy).
18-21
Two
radiographic
parameters
were
analyzed
to
assess
the
canine
eruption
pattern:
(1)
the
mesial
inclination
of
the
crown
to
the
midline,
according
to
Ericson
and
Kurol
7
(angle
a,
Fig
2);
and
(2)
the
medial
crown
position
in
sectors
1-5,
according
to
Ericson
and
Kurol
7
(s1-s5,
Fig
3).
Radio-
graphic
measurements
were
made
at
both
TO
and
T1
by
the
same
operator
(S.I.P.),
who
underwent
an
intraexa-
miner
reliability
check.
Additionally,
the
development
of
the
permanent
canine
(measuring
the
length
of
the
root)
was
evaluated
at
TO
according
to
2
stages,
accord-
ing
to
the
method
of
Ericson
and
Kurol
8
:
(1)
the
root
was
longer
that
the
canine
crown,
and
(2)
the
root
was
shorter
that
the
canine
crown
(Table
II).
The
between-group
statistical
comparison
was
carried
out
on
the
TO-T1
changes
in
the
radiographic
measure-
ments.
The
successful
outcome
was
defined,
according
to
Leonardi
et
al,"
as
the
complete
eruption
of
the
permanent
canine
into
the
dental
arch
within
48
months
from
the
initial
observation,
thus
permitting
bracket
positioning
for
final
arch
alignment
when
needed.
Statistical
analysis
On
the
basis
of
the
results
obtained
in
a
pilot
sam-
pling
of
canines,
a
normal
distribution
of
the
main
March
2011
Vol
139
Issue
3
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics
5
Alessandri
Bonetti
et
al
319
Fig
3.
Sector
of
mesiodistal
crown
position
of
the
maxil-
lary
permanent
canine
(s1-s5)
was
located
in
accordance
with
the
sector
designation
used
by
Ericson
and
Kurol.
7
variable—the
absolute
difference
of
the
a-angle
of
the
canine—was
hypothesized;
similarly,
a
standard
devia-
tion
of
13°
was
estimated.
A
minimum
of
26
canines
was
required
for
each
group,
when
the
true
value
of
the
absolute
difference
of
the
a-angle
between
the
ECG
and
the
ECMG
was
10°,
at
an
a-level
of
0.05
and
with
a
power
of
80%.
The
Kolmogorov-Smirnov
test
with
the
Lilliefors
level
of
significance
was
carried
out
to
verify
the
normality
of
the
distribution
of
the
a-angle
of
the
canines
in
each
group.
In
addition,
skewness
and
kurtosis
coefficients
SE)
and
cumulative
normal
plots
were
used
to
con-
firm
the
Gaussian
form
of
distribution
of
the
a-angles.
A
generalized
linear
model
was
applied
to
verify
the
significance
of
the
differences
of
the
a-angles.
The
values
of
the
a-angles
among
the
3
groups
at
TO
were
always
significantly
different.
Consequently,
to
control
for
the
influence
of
the
severity
of
canine
displacement
on
the
final
results,
the
inclination
at
TO
was
used
as
the
covariate;
also,
the
stage
of
root
development
of
the
permanent
canines
was
controlled
for.
The
chi-
square
test
was
used
to
highlight
an
association
of
a
group
with
variations
of
sector.
The
t
test
for
indepen-
dent
samples
was
used
for
comparison
between
each
pair
of
groups.
The
Fisher
exact
test
was
carried
out
to
compare
the
percentages
of
favorable
outcomes
be-
tween
the
ECG
and
the
ECMG.
An
a-level
of
0.05
was
set
and
adjusted
by
the
Bonferroni
correction
at
0.016
for
multiple
comparisons.
Table
II.
Canine
distribution
by
root
development
ECG
ECMG
CG
Canines
(n)
28
37
53
Stage
1
17
20
15
Stage
2
11
17
38
To
evaluate
the
method
error,
an
intraobserver
reli-
ability
check
was
carried
out
for
both
angular
values
and
sectors.
Fifteen
randomly
selected
panoramic
radio-
graphs
(15
subjects;
30
canines)
were
measured
by
the
same
operator
(S.1.P.)
twice,
on
2
days,
with
15
days
separating
the
measurement
sessions.
The
intraclass
correlation
coefficient
(ICC)
22
was
0.968
(95%
Cl,
0.934-0.985;
P
=
0.0001)
for
angulation
of
the
canines,
thus
confirming
high
intraobserver
reliability
for
the
method
used.
The
ICC
was
1.00
for
the
sector
designa-
tion,
indicating
no
differences
between
measurement
sessions.
To
evaluate
whether
clinical
experience
affects
the
accuracy
of
the
measurements,
20
randomly
selected
panoramic
radiographs
(20
subjects;
20
right
and
20
left
canines)
were
independently
measured
by
5
orthodon-
tists.
TheICC
values
were
0.955
for
the
angular
measure-
ments
and
1.000
for
the
sector
designation
for
both
right
and
left
canines.
These
coefficients
show
high
in-
terobserver
reliability
of
the
measurement
method,
which
has
proved
not
to
be
influenced
by
clinical
experience.
RESULTS
The
TO-T1
changes
in
the
radiographic
measure-
ments
relative
to
the
canines'
intraosseous
position
on
the
panoramic
radiographs
are
shown
in
Table
III.
The
variable
a-angle
exhibited
statistically
significant
changes
between
TO
and
T1
in
the
ECMG
when
com-
pared
with
both
the
ECG
(P
=
0.0001)
and
the
CG
(P
=
0.0001).
The
variable
sectors
(s1-s5)
showed
a
statistically
significant
change
between
TO
and
T1
in
the
ECMG
when
compared
with
both
the
ECG
(P
=
0.0009)
and
the
CG
(P
=
0.003).
Neither
the
a-angle
nor
the
sectors
(s1-s5)
showed
significant
differences
in
TO-T1
changes
in
the
ECG
compared
with
the
CG.
Positive
values
(+1,
+2)
relative
to
the
TO-T1
changes
in
the
sectors—ie,
significant
improvement
in
the
mesio-
distal
canine
crown
position—prevailed
in
the
ECMG.
In
the
ECMG,
51%
of
the
canines
(19
of
37)
showed
improvement
by
1
sector,
and
13%
of
the
canines
(5
of
37)
had
improvement
by
2
sectors.
In
the
ECG,
32%
of
the
canines
(9
of
28)
exhibited
improvement
by
1
sector,
but
no
canines
improved
by
2
sectors.
No
significant
influence
of
the
stage
of
root
develop-
ment
of
the
permanent
canines
was
seen.
A
statistically
significant
difference
(P
=
0.036)
was
observed
in
the
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics
March
2011
Vol
139
Issue
3
Clinical
case
#1
(ECMG)
BEFORE
41,.. Vat
1
1
A
AFTER
320
Alessandri
Bonetti
et
al
Table
III.
Comparison
of
the
changes
between
TO
(initial
observation)
and
T1
(18
months
after
TO)
for
canine
incli-
nation
(a-angle)
and
sector
location
(s1-s5)
on
the
panoramic
radiographs
ECMG
(37
canines)
Mean
Interval
Min
Max
Mean
Interval
Min
Max
a-angle
(°)
5.7
40.9
-16.9
24.0
16.4
32.98
2.6
30.38
s1-s5
0.0
1.0
0.0
1.0
1.0
3.0
-1.0
2.0
CG
(53
canines)
Significance
Mean
Interval
Min
Max
ECG-ECMG
ECMG-CG
ECG-CG
0.60
62.8
-27.6
35.2
P
=
0.0001
P
=
0.0001
NS
0.0
3.0
-2.0
1.0
P
=
0.0009
P
=
0.003
NS
ECG
(28
canines)
Min,
Minimum;
Max,
maximum;
NS,
not
significant.
percentages
of
favorable
clinical
outcomes
between
the
ECG
(78.6%)
and
the
ECMG
(97.3%).
DISCUSSION
During
its
normal
eruption
pathway,
the
maxillary
permanent
canine
moves
down
between
the
distal
aspect
of
the
permanent
lateral
incisor
and
the
mesial
aspect
of
the
first
premolar
in
close
contact
with
these
neighboring
teeth
and
the
apex
of
the
deciduous
canine."
Canine
inclination
to
the
midline
increases
mesially
until
the
maximum
angle
is
reached
at
approx-
imately
9
years
of
age;
then
it
straightens
again
with
horizontal
movement
of
the
cusp
in
a
distal
direction.
23-
25
When
the
tooth
shows
an
excessive
mesial
inclination
to
the
midline
or
overlaps
with
the
root
of
the
adjacent
incisors
based
on
clinical
and
radiographic
criteria,
it
is
suspected
to
follow
an
incorrect
eruption
pathway.
Therefore,
preventive
approaches
to
reestablish
the
physiologic
eruption
process
might
be
considered,
thus
decreasing
the
risk
of
canine
impaction
or
adjacent
root
resorption
of
permanent
teeth.
Deciduous
tooth
removal
has
been
shown
to
be
successful
in
inducing
eruption
and,
in
some
cases,
even
uprighting
succedaneous
teeth.
14,26-28
Similarly,
several
authors
have
proposed
the
extraction
of
deciduous
canines
to
return
ectopically
erupting
canines
to
a
normal
eruption
pathway,
if
the
persistence
of
the
deciduous
tooth
would
represent
a
mechanical
obstacle
for
the
emergence
of
the
permanent
tooth.
7,9,11,12,14,23
However,
the
exact
mechanism
behind
this
phenomenon
has
not
yet
been
scientifically
explained.
11
'
12
In
this
study,
we
suggest
combining
preventive
deciduous
canine
extraction
with
deciduous
first
molar
extraction
(Fig
4,
5,
and
6)
to
maximize
the
advantages
of
these
2
procedures.
In
addition
to
the
positive
effects
derived
from
deciduous
canine
extraction,
it
may
be
that
the
removal
of
the
deciduous
first
molar
accelerates
eruption
and
promotes
uprighting
of
the
first
premolar,
thus
stimulating
the
correct
eruption
of
the
permanent
canine
by
providing
more
space
for
the
physiologic
uprighting
movement
of
the
tooth
crown
in
a
distal
direction
into
alveolar
bone.
2
'
14
Fig
4.
Patient
in
the
ECMG
who
underwent
bilateral
con-
comitant
extraction
of
the
maxillary
deciduous
canines
and
first
molars
(before
and
after
extractions).
In
this
research
project,
we
aimed
to
compare
the
effectiveness
of
these
2
treatment
modalities
in
subjects
with
retained
maxillary
permanent
canines
positioned
palatally
or
centrally
in
the
alveolar
crest,
at
risk
for
root
resorption
of
adjacent
permanent
teeth.
To
this
end,
patients
were
randomized
between
the
ECG
and
the
ECMG.
Previous
studies
demonstrated
that
incisor
March
2011
Vol
139
Issue
3
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics
Clinical
case
#2
(ECMG)
BEFORE
AFTER
Clinical
case
#3
(ECMG)
BEFORE
AFTER
Alessandri
Bonetti
et
al
321
Fig
5.
Patient
in
the
ECMG
who
underwent
bilateral
con-
comitant
extraction
of
the
maxillary
deciduous
canines
and
first
molars
(before
and
after
extractions).
root
resorption
occurs
in
almost
50%
of
patients
with
ectopically
positioned
maxillary
canines,
29
'
and
that
the
risk
of
such
a
serious
complication
might
be
decreased
by
early
intervention,
aiming
to
eliminate
canine
crown
superimposition
over
the
adjacent
incisor
root
as
early
as
possible.
6
'
7
For
these
reasons,
we
considered
it
unethical
to
design
a
study
with
a
randomized,
untreated
control
group.
Therefore,
only
patients
with
no
risk
for
ectopically
erupting
canines
or
potential
resorptive
situations
constituted
the
untreated,
nonrandomized
CG.
Because
of
the
limitations
of
a
nonrandomized
CG,
it
was
used
for
comparison
to
test
only
the
effects
in
terms
of
permanent
canine
intraosseous
positional
changes
of
both
the
extraction
of
1
deciduous
canine
and
the
concomitant
extraction
of
the
deciduous
canine
and
first
molar.
Since
the
severity
of
canine
displacement
at
Fig
6.
Patient
in
the
ECMG
who
underwent
concomitant
extraction
of
the
maxillary
deciduous
canines
and
first
molars
on
the
left
side
(before
and
after
extractions).
TO
could
be
assumed
to
be
different
among
the
treated
and
untreated
subjects,
radiographic
variables
at
TO
were
used
as
the
covariate
to
prevent
any
possible
influence
of
this
difference
on
the
final
results,
and
the
CG
was
not
used
to
compare
the
percentages
of
spontaneous
canine
eruption,
which
is
the
ultimate
criterion
for
a
successful
outcome.
The
greatest
mean
value
for
a-angle
change
(16.4)
and
improvement
in
sector
(+1)
between
TO
and
T1
was
found
in
the
ECMG
compared
with
both
the
ECG
and
the
CG.
In
the
ECMG,
19
of
the
37
canines
improved
by
1
sector,
and
5
canines
improved
by
2
sectors.
On
the
other
hand,
9
of
the
28
canines
in
the
ECG
improved
by
1
sector,
but
none
improved
by
2
sectors.
No
statistically
significant
difference
was
shown
in
terms
of
both
a-an-
gle
and
sector
changes
between
the
ECG
and
the
CG.
On
the
contrary,
the
ECMG
proved
to
be
superior
to
the
CG:
American
Journal
of
Orthodontics
and
Dentofacial
Orthopedics
March
2011
Vol
139
Issue
3
322
Alessandri
Bonetti
et
al
a
significant
difference
was
found
in
the
TO-T1
changes
among
all
examined
variables.
Clinical
and
radiographic
follow-ups
are
indicated
12
to
18
months
(or
even
more,
depending
on
the
patient's
age
at
the
initial
observation)
after
removal
of
deciduous
teeth
to
follow
permanent
canine
eruption
tendency
over
time.
The
possibility
of
space
loss
after
tooth
extrac-
tions
is
unlikely
to
be
of
enough
clinical
significance
to
warrant
the
use
of
a
space
maintainer.
Orthodontic
treatment
might
be
needed
later
to
create
space
for
the
canine
or
to
correct
its
position
in
the
dental
arch,
once
the
clinician
has
taken
into
proper
account
canine
inclination,
mesiodistal
position,
and
their
potential
ef-
fect
on
incisor
root
resorption.
31
Radiographic
evidence
of
a
decrease
in
canine
inclination
to
the
midline
and
a
more
distal
canine
crown
position,
meaning
greater
parallelism
between
the
roots
of
those
elements,
enables
clinicians
to
start
the
orthodontic
treatment
by
moving
permanent
incisors
with
no
risk
of
iatrogenic
root
resorption.
A
further
advantage
of
the
concomitant
extraction
of
the
deciduous
canine
and
first
molar
is
that
the
first
premolars
erupt
early
into
the
dental
arch,
thus
allowing
fixed
orthodontic
therapy
to
begin,
if
necessary,
at
an
earlier
stage.
This
study
showed
uneventful
canine
eruption,
the
ultimate
criterion
for
a
successful
outcome,
in
97.3%
of
the
subjects
(36
of
37
canines)
in
the
ECMG
compared
with
78.6%
of
subjects
(22
of
28
canines)
in
the
ECG,
attesting
to
greater
effectiveness
of
concomitant
extrac-
tion
of
the
deciduous
canine
and
first
molar
in
terms
of
canine
impaction
prevention.
It
is
reasonable
to
assume
that
concomitant
extraction
of
the
deciduous
canine
and
first
molar
is
no
more
techni-
cally
difficult,
biologically
expensive,
or
traumatic,
com-
pared
with
extraction
of
only
the
deciduous
canine.
The
procedure
requires
anesthetizing
the
2
adjacent
areas,
and
the
2
extractions
can
be
done
in
the
same
appoint-
ment.
Above
all,
this
protocol
could
be
intended
as
a
real
prevention
procedure
for
patients
with
ectopically
erupt-
ing
permanent
canines
at
risk
of
adjacent
tooth
root
re-
sorption,
since
it
is
not
an
early
orthodontic
treatment,
because
the
patient
is
not
asked
to
wear
an
orthodontic
appliance.
Therefore,
successful
outcome
does
not
depend
on
patient
cooperation.
Deciduous
tooth
extractions
would
decrease
the
incidence
of
maxillary
permanent
canine
impaction,
thus
beneficially
reducing
the
need
for
active
orthodontic
treatment
in
a
patient
who
might
otherwise
have
an
acceptable
occlusion.
The
early
detec-
tion
and
prevention
of
maxillary
canine
impaction
is
of
fundamental
importance
to
the
orthodontist
to
avoid
a
more
complicated,
time-consuming,
and
biologically
ex-
pensive
procedure,
including
surgical
uncovering
followed
by
orthodontic
repositioning
of
the
unerupted
tooth.
CONCLUSIONS
Based
on
the
results
of
this
randomized
clinical
trial,
it
seems
appropriate
to
recommend
concomitant
early
extraction
of
the
deciduous
canine
and
first
molar
as
a
preventive
measure
in
patients
with
retained
maxillary
permanent
canines
positioned
palatally
or
centrally
in
the
alveolar
crest,
at
risk
for
root
resorption
of
adjacent
permanent
teeth.
The
following
conclusions
can
be
drawn
from
this
study.
1.
Favorable
and
greater
changes
of
the
intrabony
position
of
the
maxillary
permanent
canine
(in
terms
of
uprighting
the
long
axis
of
the
canine
and
distal
movement
of
the
canine
crown)
attesting
to
a
greater
chance
of
spontaneous
tooth
eruption
into
the
dental
arch
were
observed
with
concomi-
tant
extraction
of
deciduous
canines
and
first
mo-
lars,
than
with
extraction
of
only
deciduous
canines.
2.
This
procedure
proved
to
be
effective
at
increasing
the
rate
of
normal
eruption
of
ectopic
canines,
compared
with
deciduous
canine
extraction
alone.
3.
Concomitant
canine
and
first
molar
extractions
seem
to
be
a
reasonable
attempt
to
obtain
greater
parallelism
between
the
roots
of
the
permanent
ca-
nine
and
the
adjacent
lateral
incisor,
thus
improving
the
local
condition
for
the
displaced
canine
to
erupt
uneventfully.
4.
This
treatment
modality
allows
successive
fixed
or-
thodontic
therapy
to
start,
if
necessary,
earlier
and
with
no
risk
of
incisor
root
resorption.
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