Early treatment of palatally erupting maxillary canines by extraction of the primary canines


Ericson, S.; Kurol, J.

European Journal of Orthodontics 10(4): 283-295

1988


The effect of extraction of the primary canine on palatally erupting ectopic maxillary canines was analysed. There were 46 consecutive ectopic canines, in 35 individuals, aged 10.0-13.0 years (man age 11.4 years) at the time of discovery of the ectopic eruption. All cases showed no or minor space loss. After extraction of the primary canine, the children were investigated clinically and radiographed at 6-month intervals for up to 18 months. In 36 of 46 canines (78%) the palatal eruption changed to normal; 23 already showed improved positions after 6 months and 13 after 12 months. No new cases normalized after 12 months. We suggest that extraction of the primary canine is the treatment of choice in young individuals to correct palatally ectopically erupting maxillary canines provided that normal space conditions are present and no incisor root resorptions are found.

EuropeanJournal
of
Orthodotuirs
10
(1988)
210-295
C
1988
European
Onhodontic
Society
Early
treatment
of
palatally
erupting
maxillary
canines
by
extraction
of
the
primary
canines
Sune
Ericson
and
Juni
Kurol
J6nkoping,
Sweden
SUMMARY
The
effect
of
extraction
of
the
primary
canine
on
palatally
erupting
ectopic
maxillary
canines
was
analysed.
There
were
46
consecutive
ectopic
canines,
in
35
individuals,
aged
10.0-
13.0
years
(mean
age
11.4
years)
at
the
time
of
discovery
of
the
ectopic
eruption.
All
cases
showed
no
or
minor
space
loss.
After
extraction
of
the
primary
canine,
the
children
were
investigated
clinically
and
radiographed
at
6-month
intervals
for
up
to
18
months.
In
36
of
the
46
canines
(78%)
the
palatal
eruption
changed
to
normal;
23
already
showed
improved
positions
after
6
months
and
13
after
12
months.
No
new
cases
normalized
after
12
months.
We
suggest
that
extraction
of
the
primary
canine
is
the
treatment
of
choice
in
young
individuals
to
correct
palatally
ectopically
erupting
maxillary
canines
provided
that
normal
space
conditions
are
present
and
no
incisor
root
resorptions
are
found.
Introduction
The
maxillary
permanent
canine
is
second
only
to
the
third
molar
in
frequency
of
impaction,
with
a
prevalence
of
approximately
2
per
cent
of
the
population
(Thilander
and
Jakobsson,
1968;
Ericson
and
Kurol,
1986a).
The
canine
is
found
palatal
to
the
dental
arch
in
about
85
percent
of
the
cases
and
buccal
only
in
about
15
percent
(Hitchin,
1956;
Rayne,
1969;
Ericson
and
Kurol,
1987a).
If
orthodontic
treatment
is
not
started,
there
is
always
a
risk
of
retention
and
also
of
resorp-
tion
of
the
roots
of
the
permanent
incisors.
Such
resorptions
have
recently
been
reported
to
occur
in
12
percent
of
cases
of
ectopic
eruption
of
the
maxillary
canines
in
the
age
range
10-13
years
(Ericson
and
Kurol,
1987a).
Resorptions
may
be
found
as
early
as
10
years
of
age
but
occur
most
often
in
the
age
groups
11
to
12
years
(Ericson
and
Kurol,
1987b).
The
most
common
treatment
procedure
in
children
and
adolescents
is
surgical
exposure
followed
by
orthodontic
appliance
treatment,
where,
as
a
rule,
the
primary
canines
are
left
in
place
until
the
orthodontist
has
moved
the
impacted
tooth
to
this
region
(Moyers,
1973;
Clark,
1971;
Bishara
et
al.,
1976;
Hunter,
1983a,
b;
Fleury
et
a/.,
1985).
Other
proposed
strategies
are
1.
acceptance,
i.e.
no
treat-
ment,
2.
extraction
of
the
malerupting
canine,
and
3.
surgical
repositioning
(Richardson
and
McKay,
1983).
Several
aetiological
factors
for
ectopic
canine
eruption
have
been
proposed,
and
include
her-
editary
factors,
lack
of
space,
persistence
of
primary
canines,
a
true
ectopic
path
of
eruption,
reduced
root
length
or
aplasia
of
lateral
incisors
(Richardson
and
McKay,
.1982;
Jacoby,
1983;
Becker
et
al.,
1984).
Delayed
exfoliation
of
the
primary
canine
was
believed
by
Lappin
(1951)
to
be
the
principal
aetiological
factor
and
he
presumed
that
it
would
be
possible
to
prevent
the
condition
from
occurring
in
a
great
many
cases,
by
extracting
the
primary
canine.
This
was
also
suggested
by
Miller
(1963)
and
Williams
(1981).
Berger,
in
1943,
stated
that
widening
of
the
arch
in
the
premolar
region
and
early
extraction
of
the
primary
canines
were
advisable
as
precautionary
measures
to
prevent
incisor
root
resorptions.
A
thorough
search
of
the
literature
has
shown
that
sporadic
case
reports
where
extraction
of
the
primary
canine
has
favourably
influenced
the
future
path
of
eruption
have
been
pre-
sented
over
the
last
50
years
(Buchner,
1936;
Kettle,
1957;
Lind,
1977;
Williams,
1981;
Leives-
ley,
1984).
In
some
of
the
presented
case
reports,
284
SUNE
ERICSON
ANDJORI
KUROL
however,
only
a
slight
displacement
of
the
canine
is
present
in
the
periapical
intra-oral
radio-
graphs,
for
example
with
the
crown
in
a
good
position
but
with
an
increased
mesial
angulation
(Kettle,
1957).
Other
authors
have
made
more
or
less
casual
remarks
that
extraction
of
the
primary
canine
may
offer
a
possibility
of
correct-
ing
impacted
canines
(Hotz,
1974;
Howard,
1978;
Silling
et
al.,
1979).
On
the
other
hand,
there
is
also
a
case
report
in
which
extraction
of
the
primary
canine
did
not
affect
the
eruption
of
the
permanent
canine
(Hotz,
1974).
No
systematic
longitudinal
study
to
evaluate
the
corrective
effect
of
primary
canine
extraction
on
the
palatally
deflected
path
of
eruption
of
maxillary
canines
has
been
carried
out,
however.
The
purpose
of
this
prospective
study
was
to
analyse
the
effect
of
extraction
of
the
primary
canine
on
palatally
erupting
maxillary
canines
in
young
individuals.
It
was
also
considered
of
interest
to
determine
when
such
a
corrective
effect
of
the
extraction
could
be
ascertained.
Subjects
and
methods
Forty-six
consecutive
ectopic
palatally
placed
maxillary
canines
were
studied.
The
children,
14
boys
and
21
girls,
were
between
10
and
13
years
Aber
rc
7
--
A
111111.
11111
4 1
,
r
a
Figure
1
Orthopantomogram
(A),
intra-oral
axial-vertex
radiograph
(B)
and
intra-oral
periapical
films
(C)
showing
the
left
maxillary
permanent
canine
in
a
true
palatal
ectopic
path
of
eruption
and
the
right
canine
with
a
lingual
tendency.
At
the
start
of
treatment,
the
primary
canines
are
present.
Normal
space
conditions.
Normalization
of
the
left
canine
6
months
after
extraction
of
the
primary
canine
(D).
ECTOPIC
MAXILLARY
CANINES
285
I
Table
1
Distribution
according
to
age
at
the
time
of
extraction
of
the
primary
canine.
Age
-
group
Number
of
teeth
Percent
10-10.9
17
37
11-11.9
13
28
12-12.9
16
35
Total
46
100
i
old
at
the
time
of
the
discovery
of
the
ectopic
I
s
position
(Tablel)
and
were
referred
for
treatment
i
1
'2
1
3141
5
from
the
Public
Dental
Service
after
the
intro-
duction
of
a
digital
palpation
screening
method
(Ericson
and
Kurol,
1986b).
Inability
to
locate
the
canine
in
the
normal
position
by
digital
palpation
prompted
a
supplementary
radio-
graphic
examination
of
the
canine,
where
its
position
was
carefully
determined
in
three
planes
(Ericson
and
Kurol,
1986a,
Fig.
1).
The
eruption
angles
and
positions
of
the
\
/
/
Sector
1
2
3
4
5
Number
13
11
20
2
0
lig!
/
1
/
2
/
I
/
3
A
-s
C
Sector
1
2
3
4
5
Number
8
18
17
3
0
rr
d
l
OL
tr
d
1
(degrees)
(mm)
Mean
22.o
14.
7
11.1
3.
2
Range
2-55
.
9.s
-20.3
Figure
2
Mesial
inclination
(alpha,
a)
to
the
midline
and
distance
(d1)
to
the
occlusal
line,
OL,
of
the
permanent
maxillary
canine
in
the
frontal
plane
(orthopantomogram)
at
the
start
of
treatment.
Figure
3
Distribution
of
the
46
maxillary
canines
according
to
the
medial
position
of
the
canine
crown
in
sectors
1-5
in
the
(A)
frontal
plane
and
(B)
transverse
plane
(derived
from
orthopantomogram
and
axial-vertex
views)
at
the
start
of
treatment.
permanent
maxillary
canines
were
determined
as
follows:
—In
the
frontal
view
(orthopantomogram)
(A)
the
angle
of
the
canine
(B)
the
distance
of
the
cusp
tip
to
the
occlusal
line
(Fig.
2)
and
the
medial
crown
position
in
sectors
1-5
(Fig.
3).
286
SUNE
ERICSON
AND
JORI
KUROL
Table
2
Effect
of
the
extraction
of
the
primary
canine
on
the
46
maxillary
canines
with
a
palatally
ectopic
path
of
eruption
in
35
individuals,
14
boys
and
21
girls,
aged
10-13
years.
Improved
position
Canine
Total
No
change
Worsening
after
after
position
number
after
after
(orthopantomogram)
of
canines
6
months
12
months
18
months
18
months
Sector
1,
2
24
19
3
2
Sector
3,
4
22
4
10
6
2
Total
46
23
13
8
2
In
the
transverse
plane
(vertex
projection)
the
position
of
the
crown
of
the
canine
relative
to
the
adjacent
lateral
incisor
and
dental
arch
was
determined
from
the
vertex
projection
and
the
conventional
intra-oral
projections.
The
position
of
the
canine
crown
relative
to
the
dental
arch
was
classified
as
completely
lingual,
lingual
tendency
and
correctly
pos-
itioned.
In
the
sagittal
plane
(lateral
head
film),
the
distances
to
the
occlusal
line.
Immediately
after
diagnosis
of
the
ectopic
palatal
path
of
eruption,
the
primary
canine
was
extracted.
The
permanent
canines
were
then
followed
clinically
and
radiographically
at
six-
month
intervals
up
to
18
months
for
the
radio-
graphic
procedure,
if
necessary,
and
clinically
to
full
eruption
or
to
the
end
of
necessary
orthodontic
appliance
treatment.
Thus,
if
a
clearly
noticeable
improvement
of
the
position
of
the
maxillary
permanent
canine
was
regis-
tered,
the
radiographic
follow-up
was
termi-
nated
at
the
6
or
12-month
control.
In
four
of
the
46
cases
(one
boy
and
three
girls),
the
lateral
incisors
already
showed
root
resorption
on
the
palatal
side
at
start.
Two
of
the
resorptions
were
superficial
and
two
were
extensive
and
reached
the
pulp.
In
the
latter
two
cases,
the
treatment
planning
for
orthodontic
treatment
of
their
malocclusion
included
extrac-
tion
of
maxillary
teeth
and
these
two
cases
were
therefore
included
in
this
study.
The
maximum
width
of
the
dental
follicle
of
the
canine
was
measured
on
the
intra-oral
periapical
radiographs.
All
cases
had
good
dental
arches
and
no
space
deficiency
was
registered
after
measuring
with
sliding
calipers.
There
had
been
no
early
extrac-
tion
of
primary
molars
in
the
maxilla.
Conventional
statistical
methods
were
used
for
calculation
of
means
and
standard
devi-
ations.
Student's
t-test
was
used
for
parametric
variables
and
the
chi-square
test
for
non-para-
metric
variables
for
the
analysis
of
differences
between
the
registrations
(Nie
et
al.,
1975).
Results
The
main
results
are
presented
in'
Table
2.
Altogether
36
(78%)
of
the
46
ectopic
canines
showed
normalization
of
the
path
of
eruption
and
later
clinically
correct
position
at
the
final
control.
For
ten
teeth
no
improvement
was
registered:
seven
showed
no
change
at
all,
one
only
slight
improvement
and
two
an
impaired
position
with
the
crown
moving
more
medially
during
the
observation
period.
Time
factor
Of
the
36
cases
with
normalization
and
clinically
correct
position
at
the
final
control,
23
canines
(64%)
already
showed
improved
positions
radio-
graphically
at
the
6-month
control,
Table
2.
Nine
of
these
had
already
normalized
at
this
time
(for
example,
Fig.
1).
After
12
months,
another
13
teeth
had
normalized
and
another
14
canines
had
improved
positions
and
showed
clinically
good
positions
at
the
18-month
con-
trol.
No
new
cases
of
improvement
occurred
between
the
12-month
and
18-month
obser-
vations.
Medial
position
(sectors
1-5,
Fig.
3)
Of
the
46
canines,
22
overlapped
the
adjacent
lateral
incisor
(in
the
orthopantomogram)
by
more
than
half
of
the
lateral
root,
and
14
(64%)
of
these
normalized
(Table
3).
Of
the
24
canines
which
overlapped
the
lateral
incisor
root
by
less
287
ECTOPIC
MAXILLARY
CANINES
Table
3
Distribution
of
the
medial
position
of
the
maxillary
permanet
canine
in
sectors
1-4
in
the
vertical
plane
as
shown
in
the
orthopantomogram.
No
teeth
were
in
sector
5.
At
the
start
of
treatment,
after
12
and
after
18
months.
Number
and
percent.
Medial
maxillary
canine
crown
position
in
sector
Registration
1
2
3,
4
Total
number
n(%)
n(%)
n(%)
At
start
(n
=
46)
13(28)
11(24)
22(46)
46
12
months
after
extraction
(n
=
37)
28•(61)
9(20)
9(20)
46•
18
months
after
extraction
(n
=
24)
36•(78)
2(4)
8(17)
46•
9
canines
had
normal
positions
at
the
6-month
radiographic
control
and
another
13
at
the
12-month
control.
Table
4
The
distribution
of
the
canine
crown
position
relative
to
the
midline
of
the
dental
arch
in
the
horizontal
plane
as
shown
in
the
axial-
vertex
radiogram.
At
the
start
of
treatment,
12
months
and
18
months
after
extraction
of
the
primary
canine.
Number
and
percent.
Position
relative
to
the
dental
arch
Registration
Palatal
Palatal
tendency
Central
or
buccal
tendency
Total
number
n(%)
n(%)
n(%)
At
start
(n
=
46)
27(59)
19(41)
46
12
months
after
extraction
(n
=
37)
9(20)
15(33)
22(48)•
46•
18
months
after
extraction
(n
=
24)
8(17)
2(4)
36(78)•
46•
9
canines
had
normal
positions
at
the
6-month
radiographic
control
and
another
13
at
the
12-month
control.
than
half
of
the
root
at
the
start
of
treatment,
22
(91%)
normalized
(Table
2,
Fig.
4).
The
change
in
medial
canine
crown
position
in
re-
lation
to
time
after
extraction
can
be
seen
from
Table
3,
where
eight
of
the
ten
teeth
with
no
final
normalization
belonged
to
sectors
3
and
4
and
one
to
sector
2
at
the
start.
The
positions
of
the
canines
in
the
vertex
projection
(Fig.
3)
showed
concordant
results
and
will
not
be
reported
in
detail.
Position
relative
to
the
dental
arch
The
distribution
of
the
canine
crown
position
relative
to
the
midline
of
the
dental
arch
is
shown
in
Table
4.
Of
the
27
canines
(59%)
in
a
lingual
position
at
the
start
of
treatment
(22
in
288
SUNE
ERICSON
AND
JURI
KUROL
could
be
seen
for
eight
of
the
canines
at
the
last
control
at
18
months.
All
the
rest
normalized
except
one,
which
remained
in
a
slight
lingual
position
(lingual
tendency).
This
means
complete
normalization
in
78%
of
all
cases.
91%
1
64%
Figure
4
Schematic
illustration
of
the
normalization
of
the
maxillary
permanent
canine
at
the
control
18
months
after
extraction
of
the
primary
canines.
The
figures
indicate
the
rate
of
success
for
the
perinanent
canine
positions
at
the
start
of
treatment,
mesial
and
distal
to
the
midline
of
the
lateral
incisor
in
the
orthopantomogram.
sectors
3
and
4,
and
5
in
sectors
1
and
2)
only
9
(20%)
remained
in
this
position
and
no
change
N
10
-
Mesial
inclination
The
distribution
of
the
mesial
inclination
of
the
maxillary
canines
at
the
start
of
treatment
is
shown
in
Figure
5.
The
inclination
is
approxi-
mately
normally
distributed.
The
change
after
extraction
of
the
primary
canines
at
the
6-month
and
12-month
controls
is
shown
in
Table
5.
The
dynamic
change
in
position
and
the
mean
difference
at
the
different
registrations
are
presented.
Note
the
large
standard
deviations
(Table
5).
Canine
vertical
distance
to
the
occlusal
plane
The
distance
from
the
canine
cusp
to
the
occlusal
plane
(Fig.
2)
at
the
different
registrations
is
shown
in
Table
6.
The
distance
at
the
start
of
treatment
ranged
from
9.5
to
20.3
mm.
At
that
time,
the
canines
were
on
average
positioned
about
15
mm
from
the
occlusal
line
in
the
orthopantomogram
and
Table
6
shows
the
change
during
the
observation
period
up
to
12
months.
The
distance
as
measured
on
the
lateral
head
film
showed
concordant
results
compared
to
Table
6.
5
-
I1
e—e
5
-9'
10*-14
.
15
*
-19
.
20-24
*
30
.-
3e
40
*
-44
*
45
.
-4e
50
.
-55
.
Mesial
inclination
to
the
midline
(orthopantomogram)
Figure
5
Distribution
of
the
mesial
inclination
(degrees)
of
the
46
maxillary
canines
to
the
midline
in
the
orthopantomogram
at
the
start
of
treatment.
Registration
mean
s.d.
a±s.d.
At
start
(n
=
46)
22.0
11.1
6-month
control
(n
=
46)
17.9
12.5
4.1±8.3
12-month
control
(n
=
37)
14.0
13.3
9.8+9.1
Level
of
significance
p
<
0.01
p
<
0.001
289
ECTOPIC
MAXILLARY
CANINES
Table
5
Mesial
inclination
(degrees)
of
the
canine
to
the
midline
in
the
orthopantomogram.
Mean
value
and
standard
deviation
at
the
different
registrations
and
mean
difference
and
level
of
significance.
Table
6
The
distance
(mm)
from
the
canine
cusp
to
the
occlusal
plane
in
the
orthopantomogram.
Mean'
value
and
standard
deviation
at
the
different
registrations
and
mean
difference
and
level
of
significance.
Registration
mean
s.d.
a±s.d.
At
start
(n
=
46)
14.7
3.2
6-month
control
(n=
46)
11.7
4.3
'
3.0
±
1.8
12-month
control
(n
=
37)
9.2
5.0
5.5
±
2.7
Level
of
significance
p
<
0.01
p
<
0.001
Table
7
Treatment
procedures
for
10
out
of
the
46
ectopic
maxillary
canines
where
no
improvement
of
position
was
registered
12
months
after
extraction
of
the
primary
canine.
Change
of
eruption
path
Treatment
Orthodontic
Position
in
the
impaired
surgical
fixed
appliance
'Extraction
orthopantomogram
No
change
position
exposure
treatment
of
lateral
2
6
2
1
8 8
2
8
2
9
8
2
Overlapping
less
than
half
of
the
lateral
(sectors
1,
2)
Overlapping
more
than
half
of
the
lateral
(sectors
3,
4)
Total
290
SUNE
ERICSON
AND
JURI
KUROL
No
normalisation
Ten
of
the
46
canines
showed
no
change
or
an
impaired
position.
The
clinical
treatment
is
shown
in
Table
7.
Nine
of
these
teeth
had
a
true
lingual
position
at
the
start
of
treatment
(Table
4)
and
in
eight
cases
the
cusp
was
positioned
more
medially
to
the
midline
of
the
lateral
incisor
in
the
orthopantomogram.
Surgical
exposure
and
orthodontic
fixed
appliance
treatment
was
carried
out
in
eight
cases
(Table
7).
After
ortho-
dontic
treatment,
all
canines
were
in
clinically
favourable
positions.
Resorptions
In
the
four
cases
with
resorptions
on
the
root
of
the
lateral
incisor,
diagnosed
at
the
start
of
treatment,
the
positions
were
normal
in
two
cases,
unchanged
in
one
and
one
canine
showed
an
impaired
position.
Three
canines
were
pos-
itioned
in
sector
3
and
one
in
sector
2
in
the
orthopantomogram
at
the
start
of
treatment.
Two
of
the
resorptions
were
severe
and
reached
the
pulp
at
the
start
of
treatment.
One
remained
unchanged
and
one
deteriorated
during
the
observation
period
and
these
two
cases
are
the
extraction
cases,
where
the
orthodontic
treat-
ment
plan
included
extraction
of
lateral
incisors
as
one
possibility
from
the
start.
No
new
cases
of
resorption
were
registered
during
the
obser-
vation
period.
Dental
follicle
The
maximal
width
of
the
dental
follicle
of
the
maxillary
canine,
measured
on
the
intra-oral
periapical
radiographs,
exceeded
3
mm
in
13
cases
and
varied
between
1
and
5
mm
for
the
46
canines.
There
was
no
association
in
those
cases
which
did
not
improve
related
to
the
size
of
the
follicle.
Discussion
The
effect
of
extraction
of
the
primary
canine
on
the
palatally
deflected
path
of
eruption
of
the
maxillary
canine,
is
analysed
in
this
report.
To
our
knowledge,
this
is
the
first
prospective
longitudinal
study
where
such
an
effect
on
pala-
tally
erupting
maxillary
canines
has
been
shown.
Orthodontic
textbooks
and
papers
on
treatment
of
ectopic
maxillary
canines
do
not
mention
this
treatment
approach,
but
there
are
sparse
case
reports
in
the
literature
(Buchner,
1936;
Kettle,
1957;
Lind,
1977;
Williams,
1981;
Leivesley,
1984).
Perhaps
extraction
of
the
primary
canine
has
been
considered
an
'oddity'
and
the
success
limited
to
cases
with
only
a
minor
deflection,
as
shown
by
Kettle
(1957).
This
study
clearly
shows
that
extraction
of
the
primary
canine
has
a
favourable
effect
on
palatally
malerupting
maxillary
canines.
Almost
80
per
cent
of
the
cases
were
corrected
due
to
the
early
extraction
of the
primary
canines.
Spontaneous
corrections
may
occur
but
from
4
$
1
A
..
A
tt
Figure
6
Ectopic
palatal
eruption
of
the
right
maxillary
canine
in
a
girl
aged
12
years
9
months
at
the
start
of
treatment.
The
mesial
inclination
and
palatal
position
where
the
canine
crown
almost
reaches
the
central
incisor
can
be
seen
in
the
orthopantomogram
(A)
and
axial
vertex
projection
(B).
The
radiographs
show
the
improvement
of
position
and
inclination
from
the
start
of
treatment
(C)
to
6
months
after
extraction
of
the
primary
canine
(D,
E).
ECTOPIC
MAXILLARY
CANINES
291
clinical
experience,
it
is
not
likely
that
ectopically
erupting
canines
will
be
spontaneously
corrected
to
such
an
extent,
especially
not
those
with
the
crown
in
advanced
medial
positions,
as
shown
in
Figures
2
and
4,
Table
2.
However,
a
few
of
the
canines
in
the
youngest
age
groups
with
a
moderate
dislocation
of
the
canine
might
have
corrected
spontaneously,
as
shown
by
us
earlier
(Ericson
and
Kurol,
1986a).
For
ethical
reasons,
we
have
not
been
able
to
design
a
study
with
a
traditional,
untreated
control
group
but
it
is
hardly
likely
that
22
of
24
canines
(92%)
in
sectors
1
and
2
and
14
of
22
(64%)
in
sectors
3
and
4
(in
the
orthopantomogram)
would
do
so.
The
results
will
be
discussed
with
this
assumption
and
reservation.
A
positive
change
in
the
path
of
eruption
could
be
observed
radiographically
in
50
per
cent
of
the
cases,
and
in
some
cases
(20%)
also
clinically,
at
the
6-month
registration
after
extraction
of
the
primary
canine
(Figs.
1
and
6).
At
the
12-month
control,
all
but
nine
had
normal
or
improved
positions.
If
such
a
change
in
eruption
is
not
detectable
at
that
time,
a
new
decision
must
be
made
and
some
canines
posing
a
risk
of
further
root
resorption
of
the
incisors,
may
have
to
be
surgically
exposed
and
treated
with
orthodontic
appliances,
while
in
most
other
cases
a
further
6
months
of
observation
may
be
allowed.
If
no
improvement
is
detectable
at
the
12-month
control,
we
suggest
alternative
treatment.
If
the
diagnosis
is
made
early
accord-
ing
to
defined
criteria
i.e.
clinical
palpation
and
if
necessary
radiographic
examination
(Ericson
and
Kurol,
1986a),
there
should
be
enough
time
to
carry
out
alternative
surgical
and/or
orthodontic
treatment.
This
study
has
clearly
demonstrated
the
favourable
effect
on
the
maxillary
canine
even
in
very
medial
positions
of
the
canine
crown
(Table
3,
Figs.
1
and
6)
and
up
to
a
mesial
inclination
of
the
canine
of
55
degrees
to
the
midline
in
the
orthopantomogram
(Table
6).
Note
that
canine
teeth
with
similar
positions
B
A
•••
a
C
Figure
7
Palatal
ectopic
eruption
of
both
maxillary
canines
in
a
boy
aged
12
years
11
months
at
the
start
of
treatment.
Mixed
dentition
period.
The
width
of
the
dental
follicle
exceeded
3
mm
fpr
both
canines.
In
the
orthopantomogram
(A)
the
mesial
inclination
to
the
midline
is
31
degrees
for
the
left
canine
and
27
degrees
for
the
right
canine.
In
the
axial-vertex
projection
(B)
the
cusp
tips
are
positioned
approximately
in
the
same
position
lingually
to
the
lateral
incisor
root.
Twelve
months
after
extraction
of
the
maxillary
primary
canines
the
orthopantomogram
(C)
and
axial-vertex
projection
(D)
show
an
improved
position
of
the
left
canine
and
a
slightly
impaired
position
of
the
right
maxillary
canine.
292
SUNE
ERICSON
AND
!URI
KUROL
7
A
qb
C
D
r.
liblirw•
Figure
8
Girl
aged
12
years
8
months
at
the
start
of
treatment.
The
right
maxillary
canine
is
erupting
palatally
and
the
orthopantomograms,
axial-vertex
radiographs
and
intra-oral
radiographs
show
the
development
from
the
start
(A,
C,
E)
to
12
months
after
extraction
of
the
primary
canine
(13,
D,
F).
and
angulations
may
react
differently
even
in
the
same
individual,
as
shown
in
Figure
7.
In
spite
of
a
difference
of
only
four
degrees
in
mesial
angulation
and
concordant
medial
and
lingual
positions,
the
left
maxillary
canine
nor-
malized
but
not
the
right.
Due
to
the
difficulty
in
predicting
a
favourable
change
of
the
path
of
eruption
in
the
individual
case,
we
recommend
radiological
and/or
clinical
supervision
at
six-
month
intervals
after
extraction
of
the
primary
canine
until
the
permanent
canine
erupts.
The
degree
of
palatal
position
at
the
start
of
treatment
relative
to
the
dental
arch
has
been
shown
to
influence
the
result
(Table
4).
Maxillary
canines
with
a
moderate
lingual
path
of
eruption
normalized
more
often
(90%)
than
canines
in
true
lingual
positions
(65%).
Again,
no
reliable
forecast
of
success
or
failure
can
be
made
in
the
individual
case,
although
the
prognosis
for
the
treatment
on
the
whole
is
very
good.
With
earlier
diagnosis
according
to
our
earlier
recommen-
dations
(Ericson
and
Kurol,
1986b),
it
may
be
possible
to
achieve
even
better
results
as
the
canine
is
then
higher
up
and
probably
has
a
less
deflected
path
of
eruption.
Note
that
one-third
of
the
patients
in
this
study
were
between
12
and
13-years-old
at
the
time
of
referral.
It
has
often
been
mentioned
that
a
palatal
path
of
eruption
may
be
seen
in
cases
where
the
primary
canine
is
unresorbed
(Dewel,
1949;
Hotz,
1974;
Salzmann,
1974).
However,
it
is
not
established
whether
this
is
a
consequence
or
the
primary
cause
of
the
ectopic
palatal
eruption.
In
this
study,
in
individuals
aged
10-13
years,
i.e.
during
a
normal
eruption
period,
21
(46%)
of
the
46
primary
canines
were
unresorbed
and
25
(54%)
showed
various
degrees
of
resorption.
In
order
to
be
successful
with
this
procedure
of
extracting
the
primary
canine,
we
must
follow
the
eruption
process
radiologically
by
means
of
correct
and
standardized
radiographs.
If
this
is
done,
it
will
be
possible
to
record
even
slight
or
moderate
changes,
as
studies
of
distortion
in
rotational
panoramic
radiography
and
cephalo-
graphy
have
demonstrated
great
tolerance
with
respect
to
angular
and
vertical
distortions
ECTOPIC
MAXILLARY
CANINES
293
OW.
A
B
,
4
4
AN
C
D
Figure
9
Girl
aged
11
years
at
the
start
of
treatment
(A,
C,
E)
and
12
months
later
(8,
D,
F);
an
impaired
position
of
the
left
maxillary
canine
is
evident
in
the
orthopantomogram,
axial-vertex
projection
and
intra-oral
radiograph.
(Tronje,
1982;
McDavid
et
al.,
1985;
Ahlqvist
et
al.,
1986).
Based
on
these
reports,
and
applying
a
relative
scale
for
the
mesio-distal
and
bucco-
lingual
determinations,
it
can
be
claimed
that
the
registrations
in
this
study
have
been
per-
formed
with
moderate
errors,
acceptable
for
practical
clinical
purposes
in
the
everyday
clini-
cal
situation.
Used
together,
we
consider
the
methods
describe
the
displaced
canine
and
the
changes
in
position
with
sufficient
accuracy
in
three
dimensions
and
are
suitable
for
this
clinical
purpose.
Guilford's
coefficient
of
reliability
(Guilford,
1965)
was
high
for
all
our
measure-
ments
(Ericson
and
Kurol,
1988).
In
view
of
the
positive
results
of
this
study
we
suggest
that
primary
canine
extraction
is
the
treatment
of
choice
in
the
age-group
10-13
years
when
the
permanent
maxillary
canine
has
a
palatal
ectopic
path
of
eruption.
Before
the
age
of
10,
spontaneous
correction
of
potentially
malplaced
canines
may
occur
(Ericson
and
Kurol,
1986b)
and
extraction
is
normally
not
indicated
unless
a
very
early
somatic
and
dental
development
is
found.
With
late
diagnosis
or
crowding
and
in
cases
of
resorption
or
very
horizontal
paths
of
eruption,
alternative
modes
of
treatment
should
be
considered,
as
our
experi-
ence
of
the
method
in
such
cases
is
too
small.
Surgical
exposure
with
subsequent
orthodontic
appliance
treatment
will
be
the
main
choice
in
those
cases.
Early
extraction
of
the
primary
canine
in
order
to
correct
the
malerupting
maxillary
permanent
canine
has
considerable
advantages
for
the
child,
both
economically
and
in
terms
of
the
discomfort
that
result
from
more
traditional
treatment
ap-
proaches.
In
fact,
periodontal
damage
to
the
ectopic
canine
after
surgical
exposure
and
ortho-
dontic
alignment
has
been
reported
compared
to
control
canines
(Wirth
et
al.,
1976
a,b;
Hans-
son
and
Linder-Aronson,
1972;
Boyd,
1982;
Kohavi
et
al.,
1984;
Oliver
and
Hardy,
1986).
Incisor
devitalization
and
some
loss
of
alveolar
bone
support
may
also
occur
(Proffit
and
Acker-
man,
4985).
The
characteristics
of
those
cases
with
no
change
or
an
impaired
position
have
to
be
further
analysed.
294
SUNE
ERICSON
AND
JURI
KUROL
Conclusions
and
recommendations
It
has
been
clearly
shown
that
extraction
of
primary
canines
in
the
upper
jaw
has
a
favour-
able
effect
on
palatally
erupting
maxillary
can-
ines
in
most
cases,
if
this
extraction
treatment
is
performed
in
time.
Early
diagnosis
of
malerup-
tion
is
important
for
success.
The
ectopic
pos-
ition
and
the
path
of
eruption
of
the
maxillary
canine
should
preferably
be
identified
before
the
age
of
11.
When
a
favourable
effect
of
treatment
occurs,
the
change
in
position
and
in
the
path
of
eruption
will
be
observed
at
the
latest
12
months
after
the
extraction
of
the
primary
canine.
If
no
improvement
can
be
found
at
that
time,
normal-
ization
is
not
to
be
expected
and
alternative
treatment
should
be
considered.
Due
to
the
great
individual
variation
in
the
position
of
the
maxillary
canines
at
the
start
of
treatment
and
to
some
extent
also
in
the
response
to
treatment,
it
is
not
possible
to
predict
success
or
failure
in
the
individual
case,
although
the
prognosis
for
the
treatment
on
the
whole
is
very
good.
Clinical
and/or
radiological
controls
at
six-month
inter-
vals
are
recommended.
In
view
of
the
positive
results,
we
suggest
that
primary
canine
extraction
is
the
treatment
of
choice
in
the
age-group
10-13
years
when
the
erupting
permanent
maxillary
canine
has
a
pala-
tal
ectopic
path
of
eruption.
With
later
diagnosis
or
crowding,
and
in
cases
of
resorption
of
the
incisor
roots
or
a
very
horizontal
path
of
eruption,
alternative
modes
of
treatment
should
be
considered.
Address
for
correspondence:
Dr
Kiri
Kurol
Department
of
Orthodontics
The
Institute
for
Postgraduate
Dental
Education
Jarnvagsgatan
9
S-552
55
JonkOping
Sweden
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