Preliminary Surface Analysis of Etched, Bleached, and Normal Bovine Enamel

Abstract

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H 2 O 2 for 60 min; (2) immersion in 37% H 3 PO 4 for 60 s; (3) immersion in 35% H 2 O 2 for 60 min, in distilled water for two min, and in 37% H 3 PO 4 for 60 s; (4) immersion in 37% H 3 PO 4 for 60 s, in distilled water for two min, and in 35% H 2 O 2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H 2 O 2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H 3 PO 4 , however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens.
These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H 2 O 2 -treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

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Journal of Dental Research
http://jdr.sagepub.com/content/69/9/1610
The online version of this article can be found at:
DOI: 10.1177/00220345900690091501
1990 69: 1610J DENT RES
N.D. Ruse, D.C. Smith, C.D. Torneck and K.C. Titley
Preliminary Surface Analysis of Etched, Bleached, and Normal Bovine Enamel
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Preliminary
Surface
Analysis
of
Etched,
Bleached,
and
Normal
Bovine
Enamel
N.D.
RUSE,
D.C.
SMITH,
C.D.
TORNECK1,
and
K.C.
TITLEY2
Center
for
Biomaterials,
1Department
of
Endodontics,
and
2Department
of
Pediatric
Dentistry,
Faculty
of
Dentistry,
University
of
Toronto,
124
Edward
Street,
Toronto,
Ontario,
Canada
M5G
1G6
X-ray
photoelectron
spectroscopic
(XPS)
and
secondary
ion-
mass
spectroscopic
(SIMS)
analyses
were
performed
on
un-
ground
un-pumiced,
unground
pumiced,
and
ground
labial
enamel
surfaces
of
young
bovine
incisors
exposed
to
four
dif-
ferent
treatments:
(1)
immersion
in
35%
H202
for
60
min;
(2)
immersion
in
37%
H3PO4
for
60
s;
(3)
immersion
in
35%
H202
for
60
min,
in
distilled
water
for
two
mmin
and
in
37%
H3PO4
for
60
s;
(4)
immersion
in
37%
H3PO4
for
60
s,
in
distilled
water
for
two
min,
and
in
35%
H202
for
60
min.
Untreated
unground
un-pumiced,
unground
pumiced,
and
ground
enamel
surfaces,
as
well
as
synthetic
hydroxyapatite
surfaces,
served
as
controls
for
intra-tooth
evaluations
of
the
effects
of
different
treatments.
The
analyses
indicated
that
exposure
to
35%
H202
alone,
besides
increasing
the
nitrogen
content,
produced
no
other
significant
change
in
the
elemental
composition
of
any
of
the
enamel
surfaces
investigated.
Exposure
to
37%
H3PO4,
however,
produced
a
marked
decrease
in
calcium
(Ca)
and
phosphorus
(P)
concentrations
and
an
increase
in
carbon
(C)
and
nitrogen
(N)
concentrations
in
unground
un-pumiced
specimens
only,
and
a
decrease
in
C
concentration
in
ground
specimens.
These
results
suggest
that
the
reported
decrease
in
the
adhesive
bond
strength
of
resin
to
35%
H202-treated
enamel
is
not
caused
by
a
change
in
the
elemental
composition
of
treated
enamel
surfaces.
They
also
suggest
that
an
organic-
rich
layer,
unaffected
by
acid-etching,
may
be
present
on
the
unground
u-n-pumiced
surface
of
young
bovine
incisors.
This
layer
can
be
removed
by
thorough
pumicing
or
by
grinding.
An
awareness
of
its
presence
is
important
when
young
bovine
teeth
are
used
in
a
model
system
for
evaluation
of
resin
adhesiveness.
J
Dent
Res
69(9):1610-1613,
September,
1990
Introduction.
Bleaching
of
enamel
with
a
35%
solution
of
hydrogen
peroxide
(H202)
has
been
recommended
as
a
clinical
procedure
for
cor-
rection
of
tooth
discolorations
or
preparation of
the
enamel
for
acid-etch
veneer
bonding
restorations
(Feinman
et
al.,
1987).
These
recommendations
have
been
made
without
a
compre-
hensive
understanding
of
the
effect
of
the
bleaching
procedure
on
the
structure
and
chemical
composition
of
the
enamel
sur-
face
and
of
its
influence
on
the
adhesive
bond
strength
of
the
applied
resin.
Shear
and
tensile
bond
strength
determinations
have
shown
that
resin
adhesiveness
to
enamel
is
dramatically
reduced
as
a
result
of
prolonged
treatment
of
the
enamel
with
concentrated
H202
(Titley
et
al.,
1988).
This
study
was
undertaken
to
determine
whether
the
re-
ported
loss
in
resin
adhesiveness
to
enamel
could
be
related
to
possible
changes
in
the
elemental
composition
of
the
enamel
surfaces
induced
by
the
H202
treatment.
Materials
and
methods.
Tooth
material.
-Incisors
were
obtained
from
young
cattle
at
a
local
abattoir.
Only
animals
having
more
than
four
erupted
permanent
incisors
that
exhibited
little
or
no
wear
were
in-
cluded.
The
teeth
were
transported
to
the
laboratory
in
cold
tap
water.
In
the
laboratory,
they
were
decoronated
on
a
band
saw,
and
the
coronal
pulp
was
removed
with
a
dental
explorer.
The
crowns
were
washed
and
stored
in
tap
water
in
a
tightly
sealed
container
at
40C
until
required,
a
period
not
exceeding
eight
weeks.
For
the
experiment,
the
crowns
of
seven
teeth
were
sec-
tioned
mesio-distally,
and
all
but
a
very
thin
layer
of
the
dentin
underlying
the
labial
enamel
was
ground
away
on
a
water-
irrigated
grinding
wheel
with
use
of
600-grit
silicon-carbide
(SiC)
paper.
Each
enamel
slab
was
then
further
cut
into
four
sections,
as
shown
in
Fig.
1,
with
a
diamond
separating
disc
under
running
water.
Sections
obtained
from
individual
teeth
were
identified
accordingly.
Enamel
preparation.
-The
enamel
sections
from
two
of
the
teeth
were
thoroughly
pumiced
for
two
min,
rinsed
for
two
min
in
distilled
water,
and
dried
with
clean,
dry,
compressed
air.
The
enamel
sections
from
two
of
the
teeth
were
only
rinsed
in
distilled
water
for
two
min
and
dried
with
clean,
dry,
com-
pressed
air.
The
labial
surfaces
of
the
enamel
sections
from
the
remain-
ing
three
teeth
were
ground
on
a
slowly
rotating
water-irrigated
grinding
wheel
with
use
of
600-grit
SiC
paper,
rinsed
in
dis-
tilled
water
for
two
min,
and
dried
with
clean,
dry,
compressed
air.
So
that
the
inherent
variation
between
tooth
enamel
com-
positions
would
be
overcome,
one
randomly
selected
enamel
section
from
each
tooth
was
used
as
control,
while
the
other
three
enamel
sections
from
the
same
tooth
were
randomly
se-
lected
and
treated
according
to
the
treatment
plan
in
Table
1.
In
this
way,
intra-
(rather
than
inter-)
tooth
comparisons
of
the
effects
of
different
treatments
were
made
possible.
After
treat-
ment,
each
enamel
section
was
rinsed
for
two
min
in
distilled
water,
dried
with
a
gentle
flow
of
compressed
air,
and
mounted
with
double-sided
adhesive
tape
on
the
bottom
of
a
covered
plastic
petri
dish
with
its
labial
surface
upward.
Specimens
were
dried
in
an
oven
at
370C
and
stored
in
a
vacuum
desic-
cator
over
phosphorus
pentoxide.
X-ray
photoelectron
spectroscopic
(XPS)
analysis
of
the
specimens
(obtained
from
teeth
1,
2,
3,
5,
and
6)
was
carried
out
by
use
of
a
Surface
Science
SSX-100
spectrometer
(Uni-
versity
of
Western
Ontario).
Monochromatic
Mg
Ka.
(1253.6
eV)
x-rays
were
used
under
the
following
operating
conditions:
spot
size
of
1000
Wrm,
flood
gun
level
of
1,
resolution
4,
and
a
vacuum
reading
of
10-6
-
10
-7
Pa
(10-
8
-
10-9
Torr).
Surface
elemental
compositions
were
calculated
from
peak
heights
with
use
of
the
instrumental
computer
programs.
Sec-
ondary
ion-mass
spectroscopic
(SIMS)
analysis
of
enamel
sec-
tions
(obtained
from
teeth
4
and
7)
was
performed
with
a
1610
Received
for
publication
February
2,
1989
Accepted
for
publication
March
30,
1990
This
investigation
was
supported
in
part
by
a
MRC
grant
and
the
Dean's
Fund
for
Research,
Faculty
of
Dentistry,
University
of
To-
ronto.
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SURFACE
ANALYSIS
OF
BOVINE
ENAMEL
Cameca
11f
instrument
(University
of
Western
Ontario).
A
sputtering
rate
of
approximately
1
ALm/100
s
was
used
for
depth
profile
analyses.
Results.
The
results
of
the
semi-quantitative
surface
elemental
com-
position
analyses
for
the
unground
enamel
samples
are
sum-
marized
in
Table
2,
while
Table
3
summarizes
the
results
obtained
for
the
ground
enamel
samples.
The
XPS
spectra
for
the
control
and
acid-etched
unground
un-pumiced
enamel
specimens
are
shown
in
Figs.
2
and
3.
Corresponding
spectra
for
ground
surfaces
are
shown
in
Figs.
4
and
5.
A
comparison
of
the
three
unground
control
specimens
(two
un-pumiced
and
one
pumiced)
and
of
the
two
ground
control
specimens
revealed,
as
expected,
significant
differences
in
their
surface
elemental
compositions
(Table
2 and
Table
3).
Exposure
of
the
unground
un-pumiced
enamel
surface
to
35%
H202
for
60
min
resulted
in
a
slight
but
insignificant
(considering
the
10-20%
relative
error
of
the
measurement)
increase
in
the
concentration
of
phosphorus
and
a
significant
increase
in
the
concentration
of
nitrogen
(Table
2,
tooth
1).
The
unground
pumiced
enamel
surface
and
the
ground
enamel
surfaces
showed
a
similar
significant
increase
in
surface
nitro-
gen
content
and
insignificant
changes
in
the
concentrations
of
the
other
elements
after
exposure
to
the
same
treatment
(Table
2,
tooth
3,
and
Table
3,
tooth
6,
respectively).
An
organic-rich,
demineralized
layer,
characterized
by
a
high
C
content
and
a
dramatic
drop
in
Ca
and
P,
was
detected
on
the
surfaces
of
the
unground
un-pumiced
enamel
specimens
after
treatment
with
either
37%
H3PO4
for
60
s
or
37%
H3PO4
for
60
s,
followed
by
35%
H202
for
60
min
(Table
2,
teeth
1
and
2).
On
the
other
hand,
when
applied
to
the
unground
pumiced
enamel
surface,
the
two
abovementioned
treatments
resulted
in
a
significant
decrease
in
C
and
a
significant
increase
in
0,
Ca,
and
P
(Table
2,
tooth
3).
Similar
effects
were
ob-
served
with
ground
enamel
surfaces
(Table
3,
teeth
5
and
6).
Treatment
of
ground
enamel
with
35%
H202
for
60
min
followed
by
treatment
with
37%
H3PO4
for
60
s
resulted
in
a
surface
elemental
composition
similar
to
the
one
obtained
by
treatment
with
37%
H3PO4
for
60
s
alone
(Table
3,
tooth
5).
The
SIMS
depth
profile
analysis
of
the
unground
un-pum-
iced
37%-H3PO4-treated
enamel
surface
confirmed
the
pres-
ence
of
an
organic-rich
demineralized
layer
that
extended
to
a
depth
of
12
am
(when
the
concentration
of
the
analyzed
ele-
ments
reached
a
plateau
similar
to
that
obtained
for
ground
enamel
samples)
and
which
exhibited
the
lowest
concentrations
of
Ca
and
P
in
the
first
2
,um
(Fig.
6).
SIMS
depth
profile
analyses
of
four
unground
pumiced
enamel
sections
(tooth
4)
and
four
ground
enamel
sections
(tooth
7)
showed
little
or
no
change
at
all
in
the
concentration
of
the
investigated
elements
in
the
upper 20-25
jLrm
of
surface
layer.
Comparative
data,
published
by
us
elsewhere
(Smith
et
al.,
1987),
were
also
obtained,
under
the
same
conditions,
for
ground
and
unground
surfaces
of
synthetic
hydroxyapatite
(Durapatite
-
Sterling-Winthrop
Laboratories,
NY)
and
provided
a
base-
line
for
the
present
spectra.
Discussion.
During
the
XPS
analysis
of
a
sample,
its
surface
is
exposed
to
monochromatic
x-rays,
which
results
in
the
emission,
by
surface
atoms,
of
photoelectrons
having
kinetic
energies
char-
acteristic
for
each
emitting
atom
and
its
respective
binding
state.
By
analysis
of
these
photoelectrons
according
to
their
kinetic
energy,
(semi)quantitative
and
structural
information
can
be
derived
regarding
the
analyzed
surface.
With
the
ex-
ception
of
hydrogen,
all
elements
are
identifiable
during
XPS
analysis,
the
detection
limit
of
the
technique
being
approxi-
mately
0.1%,
with
a
relative
standard
error
of
10%
for
stan-
dardized
quantitative
determinations
and
20-30%
for
standardless
semi-quantitative
ones.
During
SIMS
analysis,
irradiation
of
the
sample
surface
by
low-energy
ions
(helium,
oxygen,
argon,
etc.)
results
in
the
displacement
of
ions
characteristic
of
the
composition
of
the
outer
few
atomic
layers,
i.e.,
to
about
2
nm
depth.
Both
positive
and
negative
emitted
ions
can
be
collected
and
ana-
lyzed
according
to
their
respective
mass/charge
ratio.
This
process
leads
to
sputter
erosion
of
the
surface,
such
that
successive
spectral
scans
can
provide
depth-profiling
infor-
mation.
The
XPS
spectra
for
the
unground
un-pumiced
enamel
sur-
faces
(Fig.
2)
show
peaks
indicating
the
presence
of
C,
0,
Ca,
P.
N.
and
F.
There
was
a
difference
in
the
semi-quantitative
elemental
composition
of
the
two
surfaces,
with
the
second
sample
showing
a
higher
content
of
C
to
the
detriment
of
the
other
elements,
a
fact
that
may
be
due
to
either
different
levels
of
mineralization
or
to
the
presence
of
adventitious
organic
contamination
(Table
2,
teeth
1
and
2).
The
unground
pumiced
TABLE
1
TREATMENT
AND
ANALYSIS
PROTOCOL
FOR
THE
BOVINE
LABIAL
ENAMEL
SECTIONS
Tooth
No.
Surface*
HP**
E***
HP
+
E
E
+
HP
Analysis
Fig.
1-Diagram
of
sectioning
of
labial
surface
of
bovine
tooth
to
pro-
vide
sections
for
different
conditioning
treatments.
1
ug,
u-p
X
X
X
XPS
2
ug,
u-p
X
X
XPS
3
ug,
p
X
X
X
XPS
4
ug,
p
X
X
X
SIMS
5
g
X
X
X
XPS
6
g
X
X X
XPS
7
g
X
X
X
SIMS
*ug
=
unground;
u-p
=
un-pumiced;
g
=
ground;
p
=
pumiced.
**HP=35%
H1202,
one
h.
***E=37%
H3PO4,
60
s.
---
-
-
---
.
Vol.
69
No.
9
1611
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J
Dent
Res
September
1990
TABLE
2
ATOMIC
PERCENT
SURFACE
COMPOSITIONS
OF
UNGROUND
BOVINE
ENAMEL
Tooth
No.
Cleaning
Treatment
C
0
Ca
P
N
F
Ca/P
1
none
none
18.8
46.5
15.2
10.4
1.8
1.0
1.5
1
none
35%
H202,
1
h
20.0
47.9
14.4
12.4
4.1
-
1.2
1
none
37%
H3PO4,
60
s
66.5
18.5
0.7
0.5
14.4
-
1.3
1
none
37%
H3PO4,
60
s
65.1 18.6
0.4
0.5
15.5
-
0.9
+
35%
H202,
1
h
2
none
none
46.2
29.4
9.1
7.8
4.4
2.1
1.2
2
none
37%
H3PO4,
60
s
80.6
11.7
-
-
6.2
0.2
2
none
37%
H3PO4,
60
s
77.3
13.0
-
-
6.5
0.3
-
+
35%H202,
1
h
3
pumice
none
36.9
37.8
11.8
7.9
2.6
1.9
1.5
3
pumice
35%
H202,
1
h
28.3
44.3
14.0
11.6
4.0
0.5
1.2
3
pumice
37%
H3PO4,
60
s
11.6
52.2
20.0
15.2
-
0.8
1.3
3
pumice
37%
H3PO4,
60
s
13.5
50.5
18.6 15.9
1.0
0.3
1.2
+
35%
H202,
1
h
TABLE
3
ATOMIC
PERCENT
SURFACE
COMPOSITIONS
OF
GROUND
BOVINE
ENAMEL
Tooth
No.
Treatment
C
0
Ca
P
N
Ca/P
5
none
33.4
40.0
12.9
8.6
1.1
1.5
5
37%
H3PO4,
60
s
24.1
46.4
14.8
12.6
1.1
1.2
5
35%
H202,
1
h
25.7
44.8
15.8
12.0
0.6
1.3
+
37%
H3PO4,
60
s
5
37%
H3PO4,
60
s
26.3
44.3
14.9
11.8
1.3
1.3
+
35%
H202,
1
h
6
none
25.2
45.3
15.6 11.2
2.3
1.4
6
35%
H202,
1
h
23.1
46.0
13.7
11.6
5.3
1.2
6
37%
H3PO4,
60
s
15.9
50.6
18.4
14.2
-
1.3
6
37%
H3PO4,
60
s
14.7
50.4
18.7
15.8
1.0
1.2
+
35%
H202,
1
h
sample
showed
a
similar
elemental
composition
slightly
dif-
ferent
semi-quantitatively
(Table
2,
t6oth
3).
Treatment
of
the
unground
un-pumiced
sample
with
35%
H202
for
60
min
resulted
in
a
slight,
insignificant
increase
in
P
concentration
and
a
significant
increase
in
N
concentration
that
may
indicate
an
overall
increase
in
the
exposure
of
surface
organic
components
(Table
2,
tooth
1).
The
same
treatment,
when
applied
to
the
unground
pumiced
enamel
surface,
re-
sulted,
again,
in
a
significant
increase
in
N
concentration
ac-
companied
by
other
slight
and
insignificant
modifications
that
could,
however,
be
correlated
with
a
cleansing
effect,
i.e.,
removal
of
organic
contamination
and
exposure
of
more
min-
eral
hydroxyapatite
(Table
2,
tooth
3).
The
unground un-pumiced
enamel
surfaces
treated
with
37%
H3PO4
for
60
s
revealed
the
formation
of
an
organic-rich
layer
with
little
or
no
mineral
content
at
all
(Table
2,
teeth
1
and
2).
The
XPS
spectrum
(Fig.
3)
still
showed
small
concentra-
tions
of
F.
enhanced
levels
of
C
and
N.
and
a
small
peak
for
silicon
(Si).
The
latter
probably
arises
from
the
etching
agent
(Smith
and
Ruse,
1987).
There
were
small
(Table
1,
tooth
1)
or
no
peaks
at
all
(Table
1,
tooth
2)
present
for
Ca
and
P,
indicating
an
almost
complete
demineralization
of
the
surface.
The
absence
of
a
similar
change
in
Ca
and
P
in
the
ground
specimens
(Table
3,
teeth
5
and
6)
suggests
that
the
enamel
below
the
surface
is
more
densely
and
more
uniformly
min-
eralized
than
the
enamel
on
the
surface
(Peterson
et
al.,
1978).
The
additional
treatment
of
acid-etched
surfaces
with
35%
H202
for
60
min
did
not
produce
any
further
significant
mod-
ifications
in
the
surface
elemental
compositions.
The
organic-
rich
layer,
in
these
cases,
could
be
attributed
to
the
presence
50000
W
I'.
1000.
0
BindIng
Energy
(mV)
0.
Fig.
2-XPS
spectrum
of
unground
un-pumiced
untreated
bovine
labial
enamel
surface.
1000.
a
Binding
Energy
(eV)
0.0
Fig.
3-XPS
spectrum
of
unground
un-pumiced
bovine
labial
enamel
surface
treated
with
37%
H3PO4
for
60
s.
I
1612
RUSE
et
al.
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SURFACE
ANALYSIS
OF
BOVINE
ENAMEL
on
the
surface
of
unground
un-pumiced
enamel
of
an
organic-
rich
pellicle
and/or
an
organic-rich
coronal
cementum
(Glimcher
et
al.,
1964).
The
presence
of
an
organic-rich
"film"
was
evident
on
the
surface
of
the
enamel
sample
analyzed
by
SIMS.
During
SIMS
sputtering,
a
charring
effect
accompanied
by
the
exfoliation
of
the
organic-rich
pellicle
took
place
and
was
later
characterized
by
the
viewing
of
the
sample
under
a
light
mi-
croscope
(Fig.
7).
SIMS
depth-profile
analysis
of
the
unground
un-pumiced
acid-
etched
enamel
sample
(Fig.
6)
confirmed
the
presence
(on
the
surface)
of
an
organic-rich
layer
that
was
approximately
12
pAm
thick.
However,
the
depth
of
this
layer
and,
indeed,
its
very
presence
are
probably
dependent
on
both
the
degree
of
tooth
maturation
and
surface
cleaning
proceduress.
It
is
probable
that
it
may
be
reduced
in
teeth
that
are
aged
or
worn,
or
in
teeth
that
are
thoroughly
cleaned,
as
demonstrated
by
the
surface
compo-
sition
of
the
unground
pumiced
enamel
sample
(see
Table
2,
tooth
3).
If
the
organic-rich
layer
is
enamel
cuticle,
it
is
greater
in
depth
than
that
of
human
teeth
(Eisenmann,
1985).
One
aspect
of
the
organic-rich
layer
lies
in
the
significance
of
its
presence
in
studies
that
utilize
young
bovine
incisors
for
investigation
of
the
adhesive
properties
of
restorative
mate-
rials.
In
such
instances,
the
tooth
surface
should
be
ground
so
that
more
mature
and
uniformly
mineralized
enamel
may
be
exposed.
This
also
confirms
that
a
uniform
etching
of
the
labial
surface
of
both
human
and
bovine
teeth
is
more
likely
to
be
obtained
after
maturation
of
the
enamel
has
occurred
and/or
after
the
enamel
surface
has
been
mildly
abraded.
Since
in
our
previous
study
(Titley
et
al.,
1988)
we
ground
the
enamel
surfaces
of
the
bovine
teeth
used
to
evaluate
resin
adhesion
to
bleached
enamel,
it
appears
that
the
marked
re-
duction
in
the
bond
strength
caused
by
the
bleaching
was
not
related
to
a
peroxide-induced
change
in
the
elemental
com-
position
of
the
enamel
surface.
However,
the
absence
of
such
change
does
not
necessarily
imply
that
no
change
in
surface
chemistry
occurred,
and
further
investigation
into
this
possi-
bility
is
currently
being
undertaken.
REFERENCES
EISENMANN,
D.R.
(1985):
Enamel
Structure.
In:
Oral
Histology,
Development,
Struc-
ture
and
Function,
A.R.
Ten
Cate,
Ed.,
St.
Louis:
Mosby,
pp.
198-215.
FEINMAN,
R.A.;
GOLDSTEIN,
R.E.;
and
GARBER,
D.A.
(1987):
Bleaching
Teeth,
Chicago:
Quintessence
Pub.
Co.
GLIMCHER,
M.J.;
FRIBERG,
U.A.;
and
LEVINE,
P.T.
(1964):
The
Identification
and
Characterization
of
a
Calcified
Layer
of
Coronal
Cementum
in
Erupted
Bovine
Teeth,
J
Ultrastr
Res
10:76-88.
PETERSSON,
L.G.;
LODDING,
A.;
and
KOCH,
G.
(1978):
Elemental
Microanalysis
of
Enamel
and
Dentin
by
Secondary
Ion
Mass
Spectrometry
(SIMS),
Swed
Dent
J
2:41-
54.
SMITH,
D.C.;
MURRAY,
D.G.;
ZUCCOLIN,
J.D.;
and
RUSE,
N.D.
(1987):
Surface
Characteristics
of
Hydroxyapatite
and
Adhesive
Bonding.
1.
Surface
Characterization,
J
Adhesion
22:291-312.
SMITH,
D.C.
and
RUSE,
N.D.
(1987):
Adhesion
to
Dentin.
Characterization
of
the
Sub-
strate,
Trans
Soc
Biomater,
Abst.
No.
153.
TITLEY,
K.C.;
TORNECK,
C.D.;
SMITH,
D.C.;
and
ADIBFAR,
A.
(1988):
Adhesion
of
Composite
Resin
to
Bleached
and
Unbleached
Bovine
Enamel,
J
Dent
Res
67:1523-
1528.
(A
c
0
I-
c
z
z
0
5
10
15
20
DEPTH
(Pjm)
Fig.
6-SIMS
depth-profile
analysis
(for
relevant
elements)
of
the
un-
ground,
un-pumiced
bovine
labial
enamel
surface
treated
with
37%
H3PO4
for
60
s.
The
curves
are
separated
for
clarity.
One-thousand-second
sput-
tering
time
is
equivalent
to
approximately
10
,um
of
depth.
Increased
C
and
decreased
0,
P,
and
Ca
concentrations
are
evident
in
the
outer
12
pum.
tos0.
0
Binding
Energy
CeV)
0.11
Fig.
4-XPS
spectrum
of
600-grit
SiC
wet,
ground,
bovine
labial
enamel
surface.
1000.0
B
i
nd
I
rg
Energy
(V)
0.0
Fig.
5-XPS
spectrum
of
600-grit
SiC
wet,
ground,
bovine
labial
enamel
surface
treated
with
37%
H3PO4
for
60
s,
followed
by
35%
H202
for
60
min.
Fig.
7-Light
micrograph
of
the
unground
un-pumiced
bovine
labial
enamel
surface
treated
with
37%
H3PO4
for
60
s
after
SIMS
analysis.
The
charred,
exfoliating,
organic-rich
film
is
evident.
10E5-
legend
'-..~---
C
10E3t
d
10
1
.
...I
.,..I
2,.
1613
Vol.
69
No.
9
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