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The E
ffect of Airborne-particle A
brasion on the Surface C
haracteristics of M
onolithic Zirconia and the S
hear Bond S
trength
치 학 사학 문
The Effect of Airborne-particle Abrasion on the
Surface Characteristics of Monolithic Zirconia
and the Shear Bond Strength
다양한 샌드블라스 조건
지 코니아 물 레진 시 트
결합강도에 미치는 과에 한 연
2013 2월
울 학 학원
치 과학과 치과보철학전공
문 지
2
0
1
3
문
지
치 학 사학 문
The Effect of Airborne-particle Abrasion on the
Surface Characteristics of Monolithic Zirconia
and the Shear Bond Strength
다양한 샌드블라스 조건
지 코니아 물 레진 시 트
결합강도에 미치는 과에 한 연
2013 2월
울 학 학원
치 과학과 치과보철학 공
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해야 합니다.
문제 : The effect of airborne-particle abrasion on the surface characteristics of monolithic zirconia and the shear bond strength
학 : □ 사 ■ 사
학 과 : 치 과학과 (치과보철학전공)
학 : 2010-31187
연 락 처 :
저 : 문 지 ( )
제 : 2012 11 월 23
울 학 귀하
The Effect of Airborne-particle Abrasion on the
Surface Characteristics of Monolithic Zirconia and
the Shear Bond Strength
2013
Ji-Eun Moon, DDS, MSD
Department of Prosthodontics, Graduate School, Seoul National University
(Directed by Prof., Sung-Hun Kim, DDS, PhD)
2
CONTENTS
ABSTRACT --------------------------------------------------------------- 3
1. INTRODUCTION ------------------------------------------------------- 5
2. MATERIAL and METHODS
2. 1. Evaluation of microstructural changes of airborne-particle
abraded monolithic zirconia ceramic ------------------------------- 9
2. 2. Shear bond strength of resin cement ------------------------------- 16
3. RESULTS
3. 1. Microstructural changes -------------------------------------------- 19
3. 2. Shear bond strength ------------------------------------------------- 39
4. DISCUSSION ------------------------------------------------------------- 48
5. CONCLUSIONS --------------------------------------------------------- 56
REFERENCES ----------------------------------------------------------- 57
APPENDIX
KOREAN ABSTRACT
3
ABSTRACT
Purpose. This study was designed to evaluate the effects of several airborne-
particle abrasion protocols on the surface characteristics of monolithic
zirconia and to examine the effect of protocol choice on the shear bond
strength of resin cement.
Material and Methods. Two forms of monolithic zirconia specimens, 375
bar-shaped (45 × 4 × 3 mm) and 500 disc-shaped (Ø 9 × 1 mm), were
divided into 25 groups. All specimens were abraded with one of three
different sizes of alumina particles (25, 50 or 125 μm), two different
pressures (2 or 4 bar), two distinct application times (10 or 20s) and two
distinct incidence angles (45 or 90°). The bar-shaped specimens were used
for a 3-point bending test and determination of flexural strengths; Weibull
parameters were calculated for these specimens. The transformed
monoclinic phase (XM) was examined with X-ray diffractometry and Raman
spectrometry. Surface characteristics were investigated with SEM, confocal
laser scanning microscopy and AFM. The disc-shaped specimens were used
to determine the shear bond strength of resin cement (Panavia F2.0) before
and after thermocycling (5000 cycles). The fractured surfaces were
examined with SEM. All data were analyzed using 4-way ANOVA and a
multiple comparisons Scheffé test (α = .05).
4
Results. Specimens abraded with the 25 μm particles showed significantly
increased flexural strength compared to the control group; however,
differences between specimens abraded with 50 and 125 μm were
insignificant. The particle size and abrasion pressure and time significantly
affected the flexural strength, while the incidence angle was insignificant.
The XM and surface roughness were proportional to the size, pressure, time
and incidence angle. The Raman spectrum analysis showed a higher
proportion of the monoclinic phase as the depth of the specimen was closer
to the abraded surface. Under SEM and AFM observation, the larger particle
groups showed a more substantial roughening effect. In bonding with resin
cement, the highest shear bond strength after thermocycling was obtained by
the abrasion with 50 μm particles at 4 bar for 20s, regardless of incidence
angle.
Conclusion. Airborne-particle abrasion causes modification of the specimen
flaw distribution, transformation of the crystal structure, and an increase in
the shear bond strength of resin cement. Based on this study, the
recommended protocol for airborne-particle abrasion is a 50 μm particle
surface at 4 bar for 20s using an angle of either 45° or 90°.
Keyword: Monolithic Y-TZP; Airborne-particle abrasion; Phase transformation; Flexural strength; Shear bond strength Student number: 2010 – 31187
5
1. INTRODUCTION
In response of the high demand for highly esthetic, metal-free and
biocompatible restoration materials with high flexural strength, various
types of all-ceramic systems have been developed in the last few decades. In
a systematic review, all-ceramic crowns showed comparable survival rates
to metal-ceramic crowns when used in the anterior and or premolar regions,
but had a significantly higher fracture rate when used in the posterior region
[1]. Substantial effort has been put forth in the development of more reliable
all-ceramic systems. In the early 1990s, yttria-stabilized tetragonal zirconia
polycrystal (Y-TZP) was introduced to dentistry as a core material for all-
ceramic restorations. It is fabricated through the computer-aided
design/computer-aided manufacturing (CAD/CAM) technique. Compared to
other all-ceramic systems, results with Y-TZP have been encouraging, as it
has shown high resistance to fracture [2, 3].
Although damage to a zirconia framework has been reported only rarely,
chipping or fracturing of the ceramic veneer has been proposed as the most
frequent reason for failure of zirconia-based restorations [4-6]. Chip-off
fractures occur at a rate between 0% and 69% after 36 to 60 months of
follow-up [4-6]. Therefore, in order to increase the success rate of
restoration and overcome the chipping problem, zirconia restoration without
6
veneering ceramic, called a monolithic zirconia restoration system, was
introduced. Currently, monolithic zirconia restorations are constructed by
CAD/CAM and then only polished or characterized using a glaze layer.
Many studies of monolithic zirconia restorations have shown improved
clinical and laboratory results [7-9]. Their strong bond strength is
indispensable for the long-term durability of restorations. Manufacturers
also claim that zirconia ceramic restorations can be successfully cemented
with either conventional or adhesive cements. Nevertheless, some zirconia
fixed partial dentures (FPDs) show reduced retention with abutments. A
strong, durable resin bond to dental ceramics is established by the formation
of chemical bonds and micromechanical interlocking, and achieving reliable
and stable bond to zirconia remains a challenge [10, 11]. As zirconia has a
polycrystalline structure and limited vitreous phase, neither hydrofluoric
acid etching nor silanization can achieve durable zirconia-resin bonding [10,
12]. Thus, various surface treatments have been introduced to establish
durable adhesion between zirconia and dental resin cement.
For chemical bonding, many studies have shown that functional monomers
containing 4-Methacryloyloxyethyl Trimellitate Anhydride (4-META) and
10-Methacryloyloxydecyl Dihydrogen Phosphate (MDP) act as coupling
agents [11, 13, 14]. Moreover, recent studies showed that zirconia primers
and chemically adhesive resin cement have reliable bond strength. [14, 15].
7
For mechanical interlocking, airborne-particle abrasion has been used to
clean the surface, removes impurities, increases surface roughness, and
modify the surface energy and wettability. In addition, airborne-particle
abrasion provides the mechanical impingement of particles on the surface
[16-18], which results in a roughened surface and allows the resin cement to
flow into these micro-retentions and create a stronger micromechanical
interlock [19]. Airborne-particle abrasion with alumina has been identified
as a key factor in achieving a durable bond for zirconia-based ceramics [20-
24]. Different sizes of abrasive alumina particles (25, 50, 115, 125, 150 μm)
have been used, without evidence of the superiority of one over another [10,
11, 13, 25]. However, recent in vitro studies report that airborne-particle
abrasion may have a deleterious effect on the zirconia surface due to the
creation of microcracks, which might reduce the flexural strength [26, 27].
Moreover, the tetragonal phase of Y-TZP is converted to the monoclinic
phase with volume expansion (4 – 5%) under the high stresses caused by
airborne-particle abrasion, and this unique transformation can produce
different types of damage that affect the structural integrity and material
reliability [28]. Specifically, this process may result in an increase in the
crack propagation resistance of Y-TZP for a certain period of time,
functioning as a toughening mechanism [18, 29]. Conversely, since the
presence of the monoclinic structure is unstable and stressful, there is a
higher tendency for the zirconia ceramic in this phase to be fragile. Thus, it
8
may result in an increase in the fracture tendency over the longer term [26,
30, 31]. The counteracting effects of abrasion on the flexural strength of Y-
TZP are controversial in terms of effective power and duration of abrasion,
and the role of surface flaws acting as the stress concentrators relative to the
stress-induced surface compressive layer [26, 32-35].
Although several surface treatments have been recently described [10, 19,
36-40], the selection of the most appropriate airborne-particle abrasion
protocol on for Y-TZP remains controversial. Moreover, no literature
describing the t→m transformation of Y-TZP under various airborne-particle
abrasion could be found. Thus, it is necessary to determine the optimum
protocol for airborne-particle abrasion for monolithic zirconia restoration, in
order to consistently achieve a more favorable clinical outcome.
The purpose of this study was to evaluate several airborne-particle abrasion
protocols and determine how they affect monolithic zirconia in terms of
flexural strength, surface characteristics, and reliability. The shear bond
strength between the abraded monolithic zirconia and resin cement was also
evaluated. The null hypothesis to be tested was that there was no difference
in flexural strength, surface characteristics or shear bond strength of resin
cement before and after thermocycling among groups treated with various
airborne-particle abrasion protocols.
9
2. MATERIAL and METHODS
2. 1. Evaluation of microstructural changes of airborne-particle
abraded monolithic zirconia ceramic
2. 1. 1. Preparation of the specimens
Three-hundreds seventy-five specimens (45 × 4 × 3 mm) of densely sintered
high-purity monolithic zirconia ceramic (Zmatch, Dentaim, Seoul, Korea) –
which consisted of 94 - 95% ZrO2 and HfO2, 5 ± 0.2% Y2O3 and ≤ 0.25%
Al2O3 – were fabricated. The samples, denoted “as-received”, were wet
ground in sequence, first with 300 grit diamond grinding disc and
sequentially with 6, 3 and 1 μm diamond slurry. The grinding and polishing
were performed in order to minimize surface defects on the specimens
before testing.
2. 1. 2. Surface treatment by modifying alumina air abrasion conditions
Bar-shaped specimens were randomly divided into 25 groups (n = 15), and
for each group a different surface treatment was applied to the top surface of
the specimens (Group B to Y). Group A was the control with surface
remaining in the ‘as-received’ state. For alumina particle abrasion,
specimens were mounted in a sample holder at a distance of 10 mm from tip
of the sandblaster unit (AX-B3, AxianMedical Co., Tianjin, China),
equipped with a nozzle of 5 mm in diameter. Specimens were abraded with
10
Fig. 1. Schematic diagram (a) and total specimens (b) of bar-shaped monolithic zirconia specimen for 3-point bending test recommended ISO 6872:2008.
(a)
(b)
11
25, 50 or 125 μm alumina particles (Cobra, Renfert GmbH, Hilzingen,
Germany) at an air pressure of 2 or 4 bar for 10 or 20 seconds. Incidence
angle of particle delivery was maintained at 45 or 90° [41]. Airborne-paricle
abrasion protocols for each group were shown in Table 1.
2. 1. 3. X-ray diffractometry and Raman spectroscopy analysis
Before and after the airborne-particle abrasion, randomly selected
specimens of all groups were examined to analyze the crystalline phases by
X-ray diffractometry (D8 DISCOVER, Bruker, Karlsruhe, Germany). X-ray
diffraction data was collected with 2θ diffractometer using the Cu-Kα
radiation. Diffractogram was obtained from 20° to 40°, at a scan speed of
5°/min and a step size of 0.02° covering the location of the highest peaks of
t and m phases. Refinement of the data was carried out using a graphing
software (Origin 5.0 Professional, Originlab, Northampton, MA, USA). The
monoclinic peak intensity ratio (XM) on the specimen’s surface was
calculated according to the method of Garvie and Nicholson (Eq. 1) [42].
XM = ( ) ( )
( ) ( ) ( ) (Eq. 1)
Im and It represent the integrated intensity (area under the peaks) of the
monoclinic and tetragonal peaks, respectively.
Raman spectra were collected with a triple monochromator spectrometer
12
Table 1. Experimental groups with the various airborne-particle abrasion conditions
Group Size of
particle (μm) Pressure (bar) Time (s) Angle (°)
A (Control) No treatment
B
25
2
10 45
C 10 90
D 20 45
E 20 90
F
4
10 45
G 10 90
H 20 45
I 20 90
J
50
2
10 45
K 10 90
L 20 45
M 20 90
N
4
10 45
O 10 90
P 20 45
Q 20 90
R
125
2
10 45
S 10 90
T 20 45
U 20 90
V
4
10 45
W 10 90
X 20 45
Y 20 90
13
(MonoRa 750i, Dongwoo optron, Kwangju, Korea). The Ar laser (488 nm
wavelength) beam was focused using an optical microscope with ×100 long-
focal objective. Sample exploration and record spectra were performed in
steps of -1 μm [43].
2. 1. 4. Scanning electron microscopy, confocal laser scanning microscopy
and Atomic force microscopy analysis
Randomly selected specimens from all groups were gold-coated with a
sputter coater (SC7620 Mini Sputter Coater, Polaron, Schwalbach, Germany)
and the fractured surfaces were examined using the scanning electron
microscope (FE-SEM, S-4700, HITACHI, Tokyo, Japan) at ×500 and ×5000
magnification. Typical cases were used for illustration.
Confocal laser scanning microscopy (LSM 5 Pascal, Carl Zeiss Microscopy,
Göttingen, Germany) was performed to evaluate surface roughness (Sa) of
the experimental groups. A 543 nm HeNe laser (1 mW) was used as a light
source, and the specimens were examined at ×200 magnification. The
measuring area was 450 × 450 μm, and the height of the z-stack was 30 μm
in 1 μm intervals.
Atomic force microscope (SPA-400, Seiko instruments, Chiba, Japan),
operated in contact mode with 10 μm tip height, no rotation of cone angle
14
and 125 μm cantilever length, was used to obtain a quantitative and
qualitative data. This obtained a 3-dimensional image of the microstructural
surface located in the center of the samples. Images with 256 × 256 pixels
were acquired with a scan size of 20 × 20 μm and a scan rate of 0.65 Hz.
2. 1. 5. Flexural strength test
After the different surface treatments were done, 3-point bending test was
performed at a cross-head speed of 1 mm/min in a universal testing machine
(Model 3345, Instron, Canton, MA, USA) according to the ISO 6872:2008
(Fig. 2). Maximum load to failure was recorded, and the flexural strength
(sf ) was calculated in MPa (Eq. 2).
s =
(Eq. 2)
P is the fracture load (N), l is the span size (30 mm), w is the specimen
width (4 mm) and b is the thickness of the specimen (3 mm).
2. 1. 6. Statistical analysis
Statistical analyses were performed using 4-way ANOVA and Scheffé
multiple comparisons. The 4 factors used for the analyses were particle size,
pressure, time and incidence angle. The overall significance level was set to
α = .05, statistical software (SPSS 20.0; SPSS Inc., Chicago, IL, USA) was
used for calculations.
15
In addition, the strength distributions of quasi-brittle materials like ceramics
are more properly described by Weibull statistics rather than mean strength
values determined based on a Gaussian strength distribution [44]. The
Weibull modulus m was used to assess the variability of strength, where the
smaller m the lower the reliability of strength. The basic form of the Weibull
distribution is shown as follows (Eq. 3) [45, 46].
= 1 − exp − σ
σ
(Eq. 3)
Pf is the probability of failure, σ is the stress applied during testing, and σ0 is
the Weibull characteristic strength which is calculated at 63.21% failure
probability. m is then calculated from the straight line of a slope obtained by
plotting (Eq. 4).
=
σ
σ (Eq. 4)
16
2. 2. Shear bond strength of resin cement
2. 2. 1. Preparation of the specimens
Five-hundreds disc-shaped specimens (ø 9 × 1 mm) were fabricated (Fig. 2a
and 2b) and then sintered in the relevant equipment and equally divided into
25 groups (n = 20). Airborne-particle abrasion protocols were the same as
described in section 2. 1. 2.
2. 2. 2. Bonding procedure
All specimens were ultrasonically cleaned in distilled water for 5 minutes
[47], and were embedded in polytetrafluoroethylene (PTFE) molds (10 mm
in inner diameter, 20 mm in outer diameter, and 11 mm in height) using
polymethyl methacrylate (Vertex-Dental, Dentimex, Zeist, Netherlands),
constructing abraded surface of the disc that remained uncovered for the
resin cement. Commercially available dual-cured resin cement (Panavia F
2.0, Lot no. A paste-00535A and B-paste 00101A, Kuraray Medical Co. Ltd.,
Osaka, Japan) was chosen. A PTFE ring with an opening (3 mm in inner
diameter and 3 mm in depth) was then positioned on the abraded surface of
the specimen. The resin cement was mixed and packed into the PTFE ring
incrementally using hand instrument by the same operator (Fig. 2c) and then
left to polymerize completely for 30 minutes at 23 ± 1 °C after 20 seconds
LED light curing (Elipar™ S10, 3M ESPE, St.Paul, MN, USA). After the
setting, the half of each group (n = 10) was subjected to thermocycling
17
Fig. 2. Schematic diagrams (a) and total specimens (b) of disc-shaped monolithic zirconia specimen. PTFE mold embedded zirconia disc and adhered resin cement (c).
(a)
(b)
(c)
18
for 5000 cycles between 5 and 55 °C. The dwelling time at each temperature
was 30 seconds, and the transfer time from one bath to another was 2
seconds [35]. The remained subgroups (n = 10) were tested after 24 hours
without thermocycling.
2. 2. 3. Shear bond strength test
The specimen was mounted in the jig of a universal testing machine (Model
3345, Instron, Canton, MA, USA) and the shear stress was applied at a
constant crosshead speed of 1 mm/min until fracture between zirconia and
resin cement occurred. Maximum load to failure was recorded, and shear
bond strength was calculated in MPa before and after thermocycling [35].
2. 2. 4. Scanning electron microscopy
Fracture surface of selected specimens was gold coated with a sputter coater
and was examined using SEM (FE-SEM, S-4700, HITACHI, Tokyo, Japan)
at ×30 and ×500 magnification.
2. 2. 5. Statistical analysis
The shear bond strengths were tested with 4–way ANOVA for the
interpretation of the surface treatment differences before and after
thermocycling. The overall significance level was set to α = .05, and a
statistical software (SPSS 20.0, SPSS Inc., Chicago, IL, USA) was used for
calculations.
19
3. RESULTS
3. 1. Microstructural changes of specimens
The flexural strengths of specimens were presented in Fig. 3(a) – 3(g). The
mean strength, characteristic strength (σ0) and Weibull modulus (m) for
experimental groups were listed in Table 2(a) – 2(c). In this study, the mean
flexural strength ranged from 1179 ± 74.1 MPa to 2695 ± 283.1 MPa, the
characteristic strength ranged from 1212 MPa to 2827 MPa, and Weibull
modulus ranged from 7 to 20. The specimens tested in the control group
showed the mean flexural strength for 1454 ± 93.6 MPa, σ0 for 1496MPa
and m for 18. When specimens were abraded with 25 μm alumina particles,
there was significant increase in the flexural strength compared to the
control group. However, with 50 and 125 μm alumina particle, there was no
significant difference. Higher pressure and longer abrasion time increased
the flexural strength with 25 μm particle size; abrasion under 4 bar and 20
seconds significantly increased the strength compared to 2 bar and 10
seconds. However, these tendencies became unclear with other particle sizes.
Weibull moduli were decreased in experimental groups except for Group B
and C.
Table 3 summarized the overall 4-way ANOVA on the flexural strength of
3-point bending test. The 3 main factors (alumina particle size, pressure and
20
Fig. 3(a). The plot of flexural strength against failure probability (%) for Group A specimens “as-received”.
3-point bending fracture strength
Fai
lure
pro
bab
ilit
y (
%)
21
Fig. 3(b). The plot of flexural strength against failure probability (%) for Group B – E specimens with 25 μm alumina particles at 2 bar, variable 10 or 20 s from an angle of 45 or 90°.
Fig. 3(c). The plot of flexural strength against failure probability (%) for Group F – I with 25 μm alumina particles at 4 bar, variable 10 or 20 s from an angle of 45 or 90°.
3-point bending fracture strength
3-point bending fracture strength
Fai
lure
pro
bab
ilit
y (
%)
Fai
lure
pro
bab
ilit
y (
%)
22
Fig. 3(d). The plot of flexural strength against failure probability (%) for Group J – M with 50 μm alumina particles at 2 bar, variable 10 or 20 s from an angle of 45 or 90°.
Fig. 3(e). The plot of flexural strength against failure probability (%) for Group N – Q with 50 μm alumina particles at 4 bar, variable 10 or 20 s from an angle of 45 or 90°.
3-point bending fracture strength
3-point bending fracture strength
Fai
lure
pro
bab
ilit
y (
%)
Fai
lure
pro
bab
ilit
y (
%)
23
Fig. 3(f). The plot of flexural strength against failure probability (%) for Group R – U with 125 μm alumina particles at 2 bar, variable 10 or 20 s from an angle of 45 or 90°.
Fig. 3(g). The plot of flexural strength against failure probability (%) for Group V – Y with 125 μm alumina particles at 4 bar, variable 10 or 20 s from an angle of 45 or 90°.
3-point bending fracture strength
3-point bending fracture strength
Fai
lure
pro
bab
ilit
y (
%)
Fai
lure
pro
bab
ilit
y (
%)
24
Table 2(a). The influence of 25 μm alumina particle size, air stream delivery pressure, application time and incidence angle of particle delivery on the flexural strengths, characteristic strengths, Weibull modulus, monoclinic phase contents and surface roughness
Control Experimental
Size (μm)
As-received
25
Pressure (bar)
2 4
Time (s) 10 20 10 20
Angle (°) 45 90 45 90 45 90 45 90
Group A B C D E F G H I
Mean strength
(MPa)
1454 (93.6)
1245 (72.6)
1179 (74.1)
1498 (207.4)
1597 (165.2)
1725 (218.6)
2047 (274.6)
2695 (283.1)
2554 (215.2)
σ0 (MPa) 1496 1279 1212 1597 1668 1823 2176 2827 2656
m 18 20 18 8 11 9 8 11 14
XM 0 16 22 25 32 26 31 31 32
Sa (μm) 0.07
(0.002) 0.34
(0.007) 0.34
(0.030) 0.33
(0.015) 0.39
(0.022) 0.49
(0.020) 0.54
(0.013) 0.58
(0.031) 0.64
(0.013)
� σ0 = Characteristic strength; m = Weibull modulus; XM = Monoclinic phase contents; Sa = Surface roughness
25
Table 2(b). The influence of 50 μm alumina particle size, air stream delivery pressure, application time and incidence angle of particle delivery on the flexural strengths, characteristic strengths, Weibull modulus, monoclinic phase contents and surface roughness of groups
� σ0 = Characteristic strength; m = Weibull modulus; XM = Monoclinic phase contents; Sa = Surface roughness
Experimental
Size (μm) 50
Pressure (bar)
2 4
Time (s) 10 20 10 20
Angle (°) 45 90 45 90 45 90 45 90
Group J K L M N O P Q
Mean strength
(MPa)
1697 (179.0)
1682 (165.5)
1580 (173.8)
1679 (234.6)
1568 (209.8)
1320 (191.1)
1356 (219.9)
1346 (177.1)
σ0 (MPa) 1778 1758 1660 1794 1671 1413 1457 1426
m 11 12 10 8 8 8 7 9
XM 27 37 34 36 29 34 34 37
Sa (μm) 0.44
(0.032) 0.49
(0.007) 0.50
(0.016) 0.62
(0.018) 0.55
(0.017) 0.58
(0.029) 0.61
(0.010) 0.67
(0.037)
26
Table 2(c). The influence of 125 μm alumina particle size, air stream delivery pressure, application time and incidence angle of particle delivery on the flexural strengths, characteristic strengths, Weibull modulus, monoclinic phase contents and surface roughness
� σ0 = Characteristic strength; m = Weibull modulus; XM = Monoclinic phase contents; Sa = Surface roughness
Experimental
Size ( μm ) 125
Pressure (bar)
2 4
Time (s) 10 20 10 20
Angle (°) 45 90 45 90 45 90 45 90
Group R S T U V W X Y
Mean strength
(MPa)
1330 (137.9)
1351 (115.9)
1410 (138.8)
1541 (119.8)
1412 (150.5)
1426 (152.1)
1618 (179.0)
1525 (226.3)
σ0 (MPa) 1393 1404 1478 1596 1483 1494 1734 1628
m 11 13 12 15 11 12 11 7
XM 30 33 33 38 35 36 38 40
Sa (μm) 0.44
(0.013) 0.45
(0.019) 0.57
(0.006) 0.58
(0.020) 0.74
(0.013) 0.89
(0.016) 0.84
(0.040) 0.91
(0.055)
27
time) significantly affected the flexural strength, however incidence angle
did not. Interactions were significant except for size × incidence angle,
pressure × incidence angle, and time × incidence angle. The highest strength
were obtained in groups abraded with 25 μm, 4 bar, 20 seconds and 45°
(Group H, σ0 = 2827 MPa).
Fig. 4 presented the Raman spectra obtained in Group U at several depths.
Tetragonal phase was observed with intense peaks at 147, 265 and 320 cm-1.
Conversely, the monoclinic intense peaks at 181 and 190 cm-1 were
observed in the spectra of the most external area. These peaks disappeared
near the 10 μm depth.
The relative monoclinic phases (XM) of each group were summarized in
Table 2 and Fig. 5. XM increased with larger particle size, higher pressure,
longer time and larger incidence angle except for Group K, ranged from 0%
(control group) and 16% (Group B) to 40% (Group Y). The X-ray
diffraction spectra of control group and experimental Group Y, the latter
having the highest monoclinic contents among the experimental groups,
were shown in Fig. 6(a) – 6(b). The XM values were 0% and 40%,
respectively. Group A spectrum only has one t peak at 30.2°, while m peaks
were shown at both sides of reduced and broadened t peak in Group Y
spectrum. These results confirmed that the observed asymmetry in the
28
Table 3. Summary of 4-way ANOVA for flexural strength conducted at each level of interacting factor
Source Sum of
Square df
Mean
Square F P
Size 8702236.7 2 4351118.4 131.6 .000
Pressure 4848104.8 1 4848104.8 146.6 .000
Time 3724864.3 1 3724864.3 112.6 .000
Angle 11211.3 1 11211.3 .3 .561
Size × Pressure 20677986.9 2 10338993.5 312.7 .000
Size × Time 5909509.0 2 2954754.5 89.4 .000
Size × Angle 108795.1 2 54397.6 1.6 .194
Pressure × Time 353001.5 1 353001.5 10.7 .001
Pressure × Angle 126075.5 1 126075.5 3.8 .052
Time × Angle 3900.6 1 3900.6 .1 .731
Size × Pressure × Time 904131.4 2 452065.7 13.7 .000
Size × Pressure × Angle 257834.3 2 128917.2 3.9 .021
Size × Time × Angle 457854.7 2 228927.4 6.9 .001
Pressure × Time × Angle 348755.6 1 348755.6 10.5 .001
Size × Pressure × Time × Angle 588903.8 2 294451.9 8.9 .000
Error 11573738.0 350 33067.8
Total 1012104439.0 375
29
Fig. 4. Raman spectra obtained in Group U at several depths. The monoclinic doublets at 181 – 190 cm-1 were evident in the spectra of the most external area, but closer to surface.
30
Fig. 5. Monoclinic contents of each group after airborne-particle abrasion.
Group
Mo
nocl
inic
phas
e co
nte
nts
(%
)
31
spectrum of Group Y was due to the concentrated stress in the region of
abraded surface. Fig. 6(c) showed the spectra of Group B, J and R
specimens, which presented the effect of alumina particle size. The XM
values were 16%, 27% and 30%, respectively. A decrease and broadness in
the intensity of t peak was observed when the size of alumina particles
increased from 25 to 125 μm, thus meaning the increase of the XM values.
Fig. 6(d) showed the spectra of Group M, N, O and Q. Group M and Q
showed the effect of pressure, Group N and O showed the effect of
incidence angle, and Group O and Q showed the effect of time. Pressure,
time and incidence angle had increasing effects on t→m transformation. The
XM values of Group M, N, O and Q were 36%, 29%, 34% and 37%,
respectively.
The surface roughness values (Sa) measured by confocal laser scanning
microscopy were presented in Table 2. These data suggested that the
interaction of different size of particle, pressure, time and angle promoted
different topograghic patterns on the monolithic zirconia ceramic surfaces.
The representative surface images showing differences of surfaces could be
observed from the reconstructed 3D images of Group A, B and Y in Fig. 7(a)
– 7(c). Mean surface roughness of specimens abraded with alumina particle
ranged from 0.33 ± 0.015 μm to 0.91 ± 0.055 μm. The control group (Fig.
7a) had the mean Sa of 0.07 ± 0.002 μm, while Group B had the smallest
32
Fig. 6(a). X-ray diffraction patterns obtained from Group A. Group A spectrum only has one t peak at 30.2°, and no m peak around 29° and 31° was observed.
Fig. 6(b). X-ray diffraction patterns obtained from Group Y. Group Y spectrum shows the m peaks around 29° and 31° and the broadened t peak.
t
m m
2θ (degree)
Inte
nsi
ty
Inte
nsi
ty
2θ (degree)
t
33
Fig. 6(c). X-ray diffraction patterns obtained from Group B, J and R.
t
m m
Inte
nsi
ty
2θ (degree)
34
Fig. 6(d). X-ray diffraction patterns obtained from Group M, N, O and Q which were abraded with 50 μm alumina particles.
m m
t
Inte
nsi
ty
2θ (degree)
35
Fig. 7. The representative confocal laser scanning microscopy images of the selected groups. (a) Control group; (b) the smallest Sa value among abraded groups – Group B; (c) the highest Sa value among abraded groups – Group Y.
36
value of 0.34 ± 0.007 μm and Group Y had the highest value of 0.91 ± 0.055
μm (Fig. 7c). The mean Sa values increased with larger particle size, higher
pressure, longer time, larger incidence angle except for Group B and C
(Both Sa = 0.34 μm).
Microscopic examination revealed the change of the topographic surfaces of
monolithic zirconia ceramics after airborne-particle abrasion with alumina
(Fig. 8). After airborne-particle abrasion with different particle sizes of
alumina, scanning electron microscopy observations revealed an increase in
surface roughness in accordance with the increase of Sa value. In control
group, no micro-retentive pattern could be detected (Fig. 8a and 8b). After
airborne-particle abrasion with 25 μm, the smooth surface was roughened
and polished pattern was no longer seen (Fig. 8c and 8d). This treatment
produced a coarse surface with grooves and sharp edges. With particle size
of 125 μm, strong abrasion conditions created a similar but more roughened
surface (Fig. 8e and 8f).
Fig. 9 shows the microstructural surface image of Group L obtained by
atomic force microscopy which exhibits the erosive wear facet and focal
surface profile. The ‘as-received’ surface of control group is shown in Fig.
10a, which exhibited a few small spikes. Fig. 10b shows the engraved
surface after abrasion with 125 μm, 4 bar, 20 seconds and 90° (Group Y).
37
Fig. 8. Scanning electron micrographs (the left sides magnification ×500 and the right sides ×5000) of zirconia surfaces; (a, b) Control group; (c, d) Group B which had the smallest mean Sa value; (e, f) Group Y which had the highest mean Sa value. The mean Sa values were 0.07 ± 0.002 μm, 0.34 ± 0.007 μm and 0.91 ± 0.055 μm, respectively.
38
Fig. 9. Alumina-abraded nanostructural image of erosive wear facet observed by atomic force microscopy, representative image of Group L.
Fig. 10. Representative microstructural images by atomic force microscopy. (a) Control group; (b) Group Y. Control group had the maximum height of 190.08 nm, but Group Y had the maximum height of 3262.85 nm.
39
3. 2. Shear bond strength of resin cement
3. 2. 1. Shear bond strength and effect of thermocycling
The mean and standard deviations of the shear bond strength in all groups
were listed in Table 4 and illustrated in Fig. 11(a)-11(c). Table 5 and Table 6
summarized the overall 4-factor ANOVA on the shear bond strength before
and after thermocycling. In this study, the mean shear bond strength of resin
cement ranged from 10.8 ± 2.52 MPa to 18.3 ± 3.64 MPa before
thermocycling and from 6.1 ± 2.84 MPa to 12.7 ± 3.38 MPa after
thermocycling. The control group showed the mean shear bond strength of
6.7 ± 1.92 MPa before thermocycling and 3.0 ± 1.12 MPa after
thermocycling. Airborne-particle abrasion significantly increased the bond
strength, while thermocycling decreased the bond strength of resin cement.
In thermocycling groups, strong shear bond strengths were observed in
groups abraded with 50 μm, 4 bar, 20 seconds in both 45° and 90° (Group P
and Q). On the other hand, weak shear bond strengths were observed in
groups abraded with 125 μm, 2 bar and 10 seconds in both angles (Group R
and S). Groups abraded with 50 μm exhibited significantly higher values on
a similar surface roughness level measured with 25 or 125 μm. The 3 main
factors (alumina particle size, pressure and time) affected the bond strength
with resin cement, however incidence angle did not.
40
Table 4. Means and standard deviations in parenthesis of the shear bond strength (MPa) of resin cement investigated before and after thermocycling
Group 0 thermocycles 5000 thermocycles
A (Control) 6.7 (1.92) 3.0 (1.12)
B 11.3 (3.73) 6.9 (3.56)
C 11.6 (2.77) 8.3 (2.36)
D 12.8 (1.76) 8.5 (3.87)
E 13.3 (4.42) 8.4 (2.07)
F 11.8 (3.40) 8.6 (2.57)
G 11.7 (1.62) 8.8 (2.97)
H 14.8 (2.46) 9.4 (2.80)
I 12.7 (3.44) 8.9 (2.62)
J 13.7 (3.88) 12.1 (2.57)
K 12.2 (2.12) 11.3 (2.61)
L 14.7 (3.94) 10.3 (2.07)
M 15.3 (3.13) 11.4 (2.82)
N 15.5 (2.08) 10.4 (2.56)
O 15.3 (3.78) 11.1 (2.28)
P 18.1 (4.41) 12.6 (3.73)
Q 18.3 (3.64) 12.7 (3.38)
R 10.8 (2.52) 6.1 (2.84)
S 10.8 (3.16) 6.2 (1.36)
T 11.3 (0.56) 10.6 (3.51)
U 12.0 (1.99) 11.1 (3.71)
V 12.0 (3.70) 9.4 (2.82)
W 11.5 (0.61) 10.4 (2.89)
X 12.6 (3.69) 9.9 (2.39)
Y 12.1 (2.07) 9.8 (2.52)
41
Fig. 11(a). Box-plot diagram comprising the shear bond strengths (MPa) of control group and groups abraded with 25 μm.
Group
Str
ength
(M
Pa)
42
Fig. 11(b). Box-plot diagram comprising the shear bond strengths (MPa) of control group and groups abraded with 50 μm.
Group
Str
ength
(M
Pa)
43
Fig. 11(c). Box-plot diagram comprising the shear bond strengths (MPa) of control group and groups abraded with 125 μm.
Group
Str
ength
(M
Pa)
44
Table 5. Summary of 4-way ANOVA for the shear bond strength before thermocycling conducted at each level of interacting factor
Source Sum of Square
Df Mean
Square F P
Size 613.7 2 306.9 37.7 .000
Pressure 114.8 1 114.8 14.1 .000
Time 164.0 1 164.0 20.2 .000
Angle 2.9 1 2.9 0.4 .551
Size × Pressure 62.0 2 31.0 3.8 .024
Size × Time 30.0 2 14.8 1.8 .165
Size × Angle 0.7 2 0.4 - .956
Pressure × Time 1.4 1 1.4 0.2 .677
Pressure × Angle 6.7 1 6.7 0.8 .366
Time × Angle 1.0 1 1.0 0.1 .724
Size × Pressure × Time 3.1 2 1.6 0.2 .826
Size × Pressure × Angle 10.9 2 5.4 0.7 .513
Size × Time × Angle 12.7 2 6.3 0.8 .461
Pressure × Time × Angle 9.1 1 9.1 1.1 .291
Size × Pressure × Time ×
Angle 2.0 2 1.0 0.1
.885
Error 1,830.3 225 8.1
Total 44,994.2 250
45
Table 6. Summary of 4-way ANOVA for the shear bond strength after thermocycling conducted at each level of interacting factor
Source Sum of Square
Df Mean
Square F P
Size 405.3 2 202.7 29.0 .000
Pressure 49.1 1 49.1 7.1 .008
Time 81.4 1 81.4 11.7 .001
Angle 5.3 1 5.3 0.8 .382
Size × Pressure 9.4 2 4.7 0.7 .510
Size × Time 40.8 2 20.4 2.9 .055
Size × Angle 0.5 2 0.2 - .968
Pressure × Time 9.2 1 9.2 1.3 .252
Pressure × Angle 0.4 1 0.4 0.1 .818
Time × Angle 1.1 1 1.1 0.2 .685
Size × Pressure × Time 144.9 2 72.5 10.4 .000
Size × Pressure × Angle 4.3 2 2.1 0.3 .737
Size × Time × Angle 7.9 2 3.9 0.6 .570
Pressure × Time × Angle 3.9 1 3.9 0.6 .455
Size × Pressure × Time ×
Angle 7.2 2 3.6 0.5
.597
Error 1,568.1 225 7.0
Total 15,106.4 250
46
Interaction of alumina particle size × pressure significantly affected the
shear bond strength before thermocycling, and interaction of particle size ×
pressure × time was statistically significant after thermocycling. This
finding meant that there was a certain combination of particle size ×
pressure × time for creating higher shear bond strength after aging treatment
process. Based on this study, these combinations were 50 μm, 4 bar and 20
seconds regardless of incidence angle.
Fig. 12 showed the representative SEM images of the fractured interfaces in
control group, Group R and Group Q, having the shear bond strengths of 3.0
± 1.12 MPa, 6.9 ± 3.56 MPa and 12.7 ± 3.38 MPa, respectively. In control
group (Fig. 12a and 12b), there were no remnant of resin cement on the
fractured surface. Group R (Fig. 12c and 12d), which had the lowest shear
bond strength (6.9 ± 3.56 MPa), showed adhesive failure mode at
zirconia/cement interface. Group Q (Fig. 12e and 12f), which had the
highest shear bond strength (12.7 ± 3.38 MPa), exhibited adhesive failure
mode with more remnants of the resin cement on zirconia surface.
47
Fig. 12. Scanning electron micrograghs (the left sides magnification ×30 and the right sides ×500) of zirconia surfaces; (a, b) Control group; (c, d) Group R which had the lowest shear bond strength to resin cement; (e, f) Group Q which had the highest shear bond strength to resin cement. The mean strength values after thermocycling were 3.0 ± 1.12 MPa, 6.9 ± 3.56 MPa and 12.7 ± 3.38 MPa, respectively.
48
4. DISCUSSION
The current investigation revealed a significant effect of several alumina
airborne-particle abrasion protocols on the flexural strength and
characteristics of monolithic zirconia ceramics. The flexural strength was
increased with higher pressure and longer time but was unaffected by the
incidence angle. In addition, the 2-way interactions containing the incidence
angle factor were all insignificant. However, the 3-way interaction and 4-
way interaction containing incidence angle factor were significant. This
means that the incidence angle factor is only significant in terms of the how
it affects the differences in the effects between other parameters. The
alumina particle size of 25 μm significantly increased the flexural strength,
while specimens treated with particle sizes of 50 and 125 μm were not
statistically different from the control group. The surface roughness,
transformed monoclinic contents and concentrated stress during airborne-
particle abrasion may have effects on the flexural strength of the monolithic
zirconia ceramics through multiple mechanisms. Therefore, the null
hypothesis that there is no difference in the flexural strength and
characteristics by modifying alumina airborne-particle abrasion protocols on
monolithic zirconia was rejected. In addition, the shear bond strength of the
alumina airborne-particle abraded monolithic zirconia surface after
thermocycling was significantly higher than that of the ‘as-received’
49
specimen. These results support the rejection of the null hypothesis that
shear bond strength of resin cement to the abraded monolithic zirconia
surface would not be different from that to a ‘as-received’ one, and that
thermocycling does not affect shear bond strength of resin cement to the
abraded surface.
In this study, airborne-particle abrasion provided a powerful method for
improvement of both flexural strength and bond strength of resin cement at
the cost of a somewhat lower degree of reliability. According to Kosmac et
al. [16], this finding is likely explained by considering two competing
factors influencing the strength of surface-treated Y-TZP ceramics. One is
residual surface compressive stresses which contribute to strengthening, and
the other is the mechanically-induced surface flaws which cause strength
degradation. Compressive stresses are formed due to t→m transformation,
which increase the flexural strength of zirconia ceramics by resisting crack
propagation [2, 16, 33, 34]. However, under clinical conditions where the
material is exposed to thermal and mechanical cycling in an aqueous
environment over long periods, fracture initiation at lower levels of applied
stress is enhanced [16]. The amount of tetragonal phase that is able to
transform to monoclinic under compression is one of the main features of
zirconia ceramics, because this determines the fracture toughness [48].
50
The variability in strength of ceramics is primarily due to the extreme
sensitivity to the presence of cracks of different sizes [49]. For a given
ceramic material, the distribution of crack size, shape, and orientation
differs from sample to sample. Thus, Weibull proposed two parameter
distribution functions to characterize the strength of brittle materials and the
Weibull distribution function is widely used to model or characterize the
flexural strength of various brittle materials including dental ceramics [44,
45, 49]. Strength variability is usually characterized using the Weibull
distribution, which is based on the premise that the weakest link in a body
determines to overall strength. It is also well described [45, 46] that such
measured strength changes due to differences in test specimen size and
configuration can be quantitatively predicted using Weibull parameters. The
distribution function relates the cumulative probability of failure under
stress to two parameters, the Weibull modulus (m) and the Weibull
characteristic strength (σ0). The Weibull modulus describes the relative
spread of strength values in the asymmetrical distribution, with high m
corresponding to less spread. On the other hands, a large value of Weibull
modulus ensures a smaller variability in strength estimation [44, 50, 51].
Large ranges of flexural strength and Weibull modulus values for zirconia
ceramics have been reported in the literature. For Y-TZP, the flexural
strength varies from 700 to 1200 MPa and the Weibull modulus from 10 to
18 [16, 18, 50, 52, 53].
51
In this study, the mean values of the monolithic zirconia characteristic
strength ranged from 1212 to 2827 MPa, and Weibull modulus from 7 to 20.
There were significant effects of airborne-particle size, notably the 25 and
50 μm particle sizes, on the flexural strength and Weibull characteristic
strength, which generally also resulted in a decrease in reliability in all but
two groups (Groups B and C). Interestingly, an increase in particle size (125
μm) produced a decrease in the flexural strength data and reliability (Table
2). Due to high stresses developed during abrasion with 125 μm particle size,
severe surface cracks were formed which likely reduced the strength and
reliability of the material [16, 54]. The effect of the large-sized particles on
the zirconia specimen may produce unstable flaws or substrate damage with
microcracks.
Low particle velocity with small size, low pressure and low angle has a
reduced rate of surface erosion [41], and hence it would appear that particles
at 45° are more likely to safely abrade brittle substrates in combination with
a low air stream pressure. At low velocity and relatively smaller particle
sizes (25 and 50 μm), a significant increase in Weibull modulus and
characteristic strength, representing an improvement in the reliability of the
flexural strength data, was observed with a decrease in the incidence angle,
whereas at high velocity and a 125 μm particle size, a decrease in the
Weibull modulus and characteristic strength of the specimens was observed.
52
When an abrasive particle is pressed against the surface of the monolithic
zirconia specimen, a contact stress field is generated which, for the various
airborne-particle abrasion protocols used here, was able to reach a
magnitude sufficient to induce the t→m transformation up to a depth of 10
μm, as shown in Fig. 4. In X-ray diffraction data, the amount of monoclinic
phase (XM) was increased with larger particle size, higher pressure, longer
time and larger incidence angle. This is consistent with various in vitro
studies which have shown that the amount of monoclinic phase produced
varied according to these four factors [17, 35, 40]. Interestingly, in this study,
the incidence angles factor took precedence over time factor in certain
groups (Groups G and H, Groups K and L, Groups O and P, Groups S and
T). Except the weakest conditions (Groups C and D) and the strongest
conditions (Groups W and X), the same trends for variation in the incidence
angle were shown over time under the same pressure conditions throughout
the X-ray diffraction spectra. In addition, the combination of the incidence
angle and the abrading time seemed more important than pressure in m
transformation phase. All groups with protocols that included 2 bar, 20
seconds and 90° parameters exhibited higher XM than those with protocols
that called for 4 bar, 10 seconds and 45°.
Sa data in our study suggest that the interaction of different size of particle,
pressure, time and angle promote different topographic patterns on the
53
monolithic zirconia ceramic surfaces. It is noteworthy that surface
roughness of groups with 10 seconds and 90° was similar to that of groups
with 20 seconds and 45° at the same pressure, and that the relative
monoclinic phase contents were similar in both groups. It is possible that
lower particle velocity may cause smaller surface fragments to be broken
thereby increasing surface roughness without introducing more detrimental
defects in spite of longer abrading time. With smaller particle sizes, it will
then be favorable to either increase the incidence angle and shorten the
abrading time or decrease the angle and extend the abrading time. When 125
μm-sized alumina was employed, the surface roughness (Sa) value increased
reflecting the relative “chipping” phenomenon at the zirconia surface.
Various in vitro studies have shown that airborne-particle abrasion with
alumina is an essential step in achieving a durable bond to high strength
ceramics [10, 13, 14, 26]. However, despite the increase in bond strength
between the resin cement and zirconia ceramics, the application of airborne-
particle abrasion on such ceramics is controversial due to the possible
introduction of flaws and microcracks [55, 56]. As expected, the application
of airborne-particle abrasion to monolithic zirconia specimens resulted in a
significant increase in shear bond strength, as observed in the values of
shear bond strength in both pre- and post-thermocycled specimens’
compared to the ‘as-received’ monolithic zirconia specimens. In bonding
54
with resin cement after thermocycling, the highest shear bond strength was
observed in groups abraded with 50 μm particles, whereas the lowest shear
bond strength in groups abraded with 125 μm. In other words, groups
abraded with 125 μm exhibited significantly lower shear bond strength
compared to the 50 μm abrasion-groups, despite having similar surface
roughness levels.
The difference in shear bond strength values of the two groups decreased
after thermocycling. This finding suggested that thermocycling significantly
reduces the shear bond strength regardless of alumina particle size in
airborne-particle abrasion. This result is in accordance with other studies
showing the relative insignificance of the particle size difference in abrasion
when the outcome of interest is the production of a durable bond between
Y-TZP and resin cement [10, 25, 57]. Moreover, these results indicate that,
while airborne-particle abrasion of monolithic zirconia produces superficial
irregularities corresponding to the certain abrasion protocol, the effect of
severe-sized undercuts is limited considering its contribution to the increase
of surface roughness. Ultimately, the recommended mean size of alumina
particle is 50 μm considering its ideal contribution to surface roughness and
monoclinic phase, providing optimal shear bond strength, and its cleaning
effect on the inner surface of restorations.
55
In this study, shear bond strengths were significantly decreased regardless of
the size of alumina particle for surface treatment after 5,000 thermocycles.
Interaction of particle size × pressure × time was not significant before
thermocycling; however, it became statistically significant after
thermocycling. This change may suggest that the interaction of the three
factors (particle size, pressure, time) maintains the long-term resin bond
strength of monolithic zirconia ceramics [57].
In short, the interaction between the abrasive particle and the substrate
surface clearly relies on complex interactions and cannot be explained by a
simple theoretical model. The alteration of the flaw population of the
specimen is often indiscriminate but may have dramatic effects on the
longevity of a restoration. Airborne-particle abrasion with alumina increases
the monolithic zirconia surface area and increases the surface area allowed,
to an even greater extent, for the reaction between the resin cement and
zirconia ceramics. This study suggests that airborne-particle abrasion with
mean particle size of 50 μm, 4 bars and 20 seconds in both angles of
incidence is effective for reliability of monolithic zirconia ceramics and for
strong and durable bond formation with resin cement.
This study is not without limitation; this study did not include a group with
a longer artificial aging time or comparison with other resin cements
56
containing different functional monomers, which could have affected the
bond strength of the monolithic zirconia ceramics. Such data would be
beneficial for estimating the long-term prognosis for monolithic zirconia
restoration. Further studies to determine how to reduce the monoclinic phase
and experiments using crown-shaped specimens of monolithic zirconia
ceramic are needed.
57
5. CONCLUSIONS
Airborne-particle abrasion with alumina modifies the initial flaw
distribution and transforms the crystal phase which affects the stability of
monolithic zirconia ceramics, and increases the shear bond strength with
resin cement. The recommended protocol based on this study is airborne-
particle abrasion with 50 μm alumina particles, 4 bar of pressure, and 20
seconds of application time either 45° or 90° incidence angles.
58
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APPENDIX
2
1. Raw data of fracture strengths (MPa) by 3-point bending test
No. Group
A B C D E F G H I
1 1314 1103 1226 1627 1624 1604 1959 2809 3000
2 1321 1254 1252 1408 1265 1516 1403 2722 2451
3 1349 1303 1239 1388 1678 2038 2109 2688 2194
4 1363 1217 1237 1459 1647 1550 1833 2697 2510
5 1412 1251 1100 1557 1727 1532 2116 3120 2490
6 1420 1153 1059 1477 1787 1503 2063 2532 2615
7 1432 1241 1047 1378 1325 1800 1842 2564 2765
8 1446 1353 1148 1352 1441 1725 2029 2419 2571
9 1459 1342 1101 1834 1532 1642 2014 3012 2461
10 1483 1211 1262 1749 1781 1869 1954 2889 2329
11 1536 1220 1150 1823 1453 1966 2434 2811 2558
12 1536 1203 1213 1485 1543 2070 1822 2357 2364
13 1559 1201 1165 1016 1789 1846 2390 2889 2470
14 1568 1264 1262 1396 1712 1340 2339 2016 2942
15 1610 1363 1215 1525 1589 1874 2397 2904 2592
Mean 1454 1245 1178 1498 1593 1725 2047 2695 2554
SD 94 73 74 207 165 219 275 283 215
3
No. Group
J K L M N O P Q
1 1918 1831 1405 1629 1573 1198 1397 1555
2 1922 1828 1689 1961 1390 1495 1166 1569
3 1558 1465 1524 1393 1419 1259 1764 1646
4 1706 1629 1540 1557 1548 1072 1395 1171
5 1607 1547 1754 1426 2047 1131 1187 1183
6 1759 1555 1766 2090 1622 1256 1655 1341
7 2075 1768 1510 1552 1985 1264 1285 1253
8 1726 1539 1700 1601 1350 1176 1295 1257
9 1550 1749 1510 1545 1449 1207 1137 1483
10 1798 1545 1662 1894 1629 1281 1715 1528
11 1529 1826 1458 2167 1405 1279 1555 1250
12 1776 1725 1983 1557 1722 1720 1089 1100
13 1482 2047 1393 1564 1400 1675 1261 1216
14 1526 1464 1371 1634 1470 1506 1287 1174
15 1518 1710 1428 1616 1517 1289 1148 1463
Mean 1697 1682 1580 1679 1568 1320 1356 1346
SD 179 165 174 235 210 191 220 177
No. Group
R S T U V W X Y
1 1314 1399 1629 1450 1339 1397 1602 1040
2 1210 1481 1348 1694 1594 1289 1504 1414
3 1152 1425 1409 1584 1117 1400 1225 1673
4 1362 1390 1458 1486 1530 1548 1688 1802
5 1241 1480 1387 1719 1350 1428 1597 1579
6 1221 1226 1361 1542 1455 1371 1702 1725
7 1341 1427 1274 1736 1506 1284 1531 1607
8 1534 1439 1336 1673 1552 1503 1638 1458
9 1477 1229 1371 1384 1219 1633 1871 1530
10 1370 1427 1338 1469 1485 1426 1528 1780
11 1176 1460 1199 1502 1139 1210 1623 1436
12 1252 1148 1333 1559 1409 1499 1844 1318
13 1455 1295 1762 1544 1557 1678 1354 1806
14 1229 1178 1490 1395 1454 1148 1867 1528
15 1610 1254 1450 1384 1475 1579 1694 1176
Mean 1330 1351 1410 1541 1412 1426 1618 1525
SD 138 116 139 120 150 152 179 226
4
2. Weibull distribution graphs. The slope is Weibull modulus (X-axis = ln(strength); Y-axis = lnln(1/(1-Pf)); Pf = failure probability)
Control group
5
(2) Airborne-particle abrasion with 25 μm alumina – Group B to I.
6
(3) Airborne-particle abrasion with 50 μm alumina – Group J to Q.
7
(3) Airborne-particle abrasion with 125 μm alumina – Group R to Y.
8
3. Raw data of surface roughness (Sa) estimated by confocal laser scanning microscopy
No. Group
A B C D E F G H I
1 0.067 0.345 0.339 0.343 0.387 0.481 0.546 0.597 0.650
2 0.068 0.304 0.373 0.336 0.364 0.474 0.530 0.607 0.633
3 0.071 0.332 0.313 0.315 0.408 0.512 0.556 0.549 0.624
Mean 0.069 0.339 0.342 0.331 0.386 0.489 0.544 0.584 0.636
SD 0.002 0.007 0.030 0.015 0.022 0.020 0.013 0.031 0.013
No. Group
J K L M N O P Q
1 0.407 0.494 0.495 0.600 0.534 0.546 0.604 0.637
2 0.470 0.485 0.523 0.616 0.542 0.579 0.608 0.710
3 0.445 0.499 0.494 0.636 0.566 0.604 0.623 0.671
Mean 0.441 0.493 0.504 0.617 0.547 0.576 0.612 0.673
SD 0.032 0.007 0.016 0.018 0.017 0.029 0.010 0.037
No. Group
R S T U V W X Y
1 0.454 0.462 0.564 0.562 0.738 0.904 0.870 0.966
2 0.436 0.45 0.576 0.602 0.729 0.897 0.798 0.891
3 0.429 0.425 0.567 0.576 0.755 0.874 0.865 0.859
Mean 0.440 0.446 0.569 0.580 0.741 0.892 0.844 0.905
SD 0.013 0.019 0.006 0.020 0.013 0.016 0.040 0.055
9
4. X-ray diffractometry graphs
(1) Control group
2θ (degree)
Inte
nsi
ty
10
(2) Airborne-particle abrasion with 25 μm alumina– Group B to I.
2θ (degree)
2θ (degree)
Inte
nsi
ty
Inte
nsi
ty
11
(3) Airborne-particle abrasion with 50 μm alumina – Group J to Q.
2θ (degree)
2θ (degree)
Inte
nsi
ty
Inte
nsi
ty
12
(4) Airborne-particle abrasion with 125 μm alumina – Group R to Y.
Inte
nsi
ty
Inte
nsi
ty
2θ (degree)
2θ (degree)
13
5. Raw data of shear bond strength before thermocycling with resin cement
No. Group
A B C D E F G H I
1 4.2 7.7 11.2 15.2 9.7 10.7 11.3 16.5 13.6
2 6.5 10.0 13.2 14.1 15.4 12.6 10.4 11.7 13.0
3 6.5 15.5 15.5 11.7 20.0 7.7 13.4 13.1 9.0
4 6.7 15.1 8.7 11.7 9.5 17.0 10.1 17.7 17.8
5 9.6 8.3 9.5 11.2 12.1 11.1 13.5 15.4 10.1
6 4.2 7.7 11.2 15.2 9.7 10.7 11.3 16.5 13.6
7 6.5 10.0 13.2 14.1 15.4 12.6 10.4 11.7 13.0
8 6.5 15.5 15.5 11.7 20.0 7.7 13.4 13.1 9.0
9 6.7 15.1 8.7 11.7 9.5 17.0 10.1 17.7 17.8
10 9.6 8.3 9.5 11.2 12.1 11.1 13.5 15.4 10.1
Mean 6.7 11.3 11.6 12.8 13.3 11.8 11.7 14.9 12.7
SD 1.92 3.73 2.77 1.76 4.42 3.40 1.62 2.46 3.44
No. Group
J K L M N O P Q
1 10.6 10.3 20.1 12.4 18.9 10.6 12.3 21.3
2 18.3 12.3 10.7 14.1 15.4 20.0 20.6 18.0
3 17.6 14.5 12.0 16.0 13.7 16.0 20.5 12.5
4 10.5 14.0 13.2 13.6 13.9 12.4 22.5 18.3
5 11.7 9.8 17.4 20.4 15.5 17.3 14.5 21.5
6 10.6 10.3 20.1 12.4 18.9 10.6 12.3 21.3
7 18.3 12.3 10.7 14.1 15.4 20.0 20.6 18.0
8 17.6 14.5 12.0 16.0 13.7 16.0 20.5 12.5
9 10.5 14.0 13.2 13.6 13.9 12.4 22.5 18.3
10 11.7 9.8 17.4 20.4 15.5 17.3 14.5 21.5
Mean 13.7 12.2 14.7 15.3 15.5 15.3 18.1 18.3
SD 3.88 2.12 3.94 3.13 2.08 3.78 4.41 3.64
14
No. Group
R S T U V W X Y
1 9.0 8.6 11.6 9.9 13.4 11.5 10.7 15.5
2 9.2 13.6 11.1 15.1 10.6 11.1 9.4 12.3
3 11.7 7.9 12.0 11.2 15.6 11.0 9.7 10.4
4 14.8 9.1 10.5 12.7 14.3 12.5 17.3 11.7
5 9.1 14.8 11.3 11.2 6.3 11.2 15.8 10.5
6 9.0 8.6 11.6 9.9 13.4 11.5 10.7 15.5
7 9.2 13.6 11.1 15.1 10.6 11.1 9.4 12.3
8 11.7 7.9 12.0 11.2 15.6 11.0 9.7 10.4
9 14.8 9.1 10.5 12.7 14.3 12.5 17.3 11.7
10 9.1 14.8 11.3 11.2 6.3 11.2 15.8 10.5
Mean 10.8 10.8 11.3 12.0 12.0 11.5 12.6 12.1
SD 2.52 3.16 0.56 1.99 3.70 0.61 3.70 2.07
15
6. Raw data of shear bond strength after thermocycling with resin cement
No. Group
A B C D E F G H I
1 3.6 4.8 5.8 12.0 9.4 8.2 11.1 7.3 9.6
2 4.3 2.4 10.6 12.9 11.0 11.5 6.1 7.0 12.7
3 3.3 10.0 10.8 4.1 8.6 6.3 12.0 9.2 7.6
4 2.2 10.9 8.2 7.7 7.2 6.1 5.3 14.0 8.8
5 1.5 6.2 6.2 5.6 5.6 11.1 9.3 9.7 5.6
6 3.6 4.8 5.8 12.0 9.4 8.2 11.1 7.3 9.6
7 4.3 2.4 10.6 12.9 11.0 11.5 6.1 7.0 12.7
8 3.3 10.0 10.8 4.1 8.6 6.3 12.0 9.2 7.6
9 2.2 10.9 8.2 7.7 7.2 6.1 5.3 14.0 8.8
10 1.5 6.2 6.2 5.6 5.6 11.1 9.3 9.7 5.6
Mean 3.0 6.9 8.3 8.5 8.4 8.6 8.8 9.4 8.9
SD 1.12 3.56 2.36 3.87 2.07 2.57 2.97 2.80 2.62
No. Group
J K L M N O P Q
1 10.8 6.8 13.1 7.4 13.1 8.3 8.3 16.7
2 14.7 13.2 8.5 13.9 11.7 13.0 15.6 12.6
3 14.3 13.0 9.3 11.7 11.9 12.6 15.9 9.3
4 8.5 11.8 12.0 9.9 7.3 8.9 14.5 15.5
5 12.4 11.9 8.8 14.1 8.1 12.6 8.9 9.5
6 10.8 6.8 13.1 7.4 13.1 8.3 8.3 16.7
7 14.7 13.2 8.5 13.9 11.7 13.0 15.6 12.6
8 14.3 13.0 9.3 11.7 11.9 12.6 15.9 9.3
9 8.5 11.8 12.0 9.9 7.3 8.9 14.5 15.5
10 12.4 11.9 8.8 14.1 8.1 12.6 8.9 9.5
Mean 12.1 11.3 10.3 11.4 10.4 11.1 12.6 12.7
SD 2.57 2.61 2.07 2.82 2.56 2.28 3.73 3.38
16
No. Group
R S T U V W X Y
1 3.8 8.4 8.4 7.7 11.1 13.1 11.8 12.5
2 6.1 5.2 7.3 14.8 4.5 7.8 7.7 7.1
3 10.9 5.2 11.6 9.6 11.5 10.1 7.5 9.0
4 5.3 6.6 16.2 8.1 9.7 13.7 9.5 12.5
5 4.3 5.6 9.5 15.4 10.1 7.5 12.8 8.1
6 3.8 8.4 8.4 7.7 11.1 13.1 11.8 12.5
7 6.1 5.2 7.3 14.8 4.5 7.8 7.7 7.1
8 10.9 5.2 11.6 9.6 11.5 10.1 7.5 9.0
9 5.3 6.6 16.2 8.1 9.7 13.7 9.5 12.5
10 4.3 5.6 9.5 15.4 10.1 7.5 12.8 8.1
Mean 8.4 8.6 9.8 10.3 9.5 10.1 10.7 10.5
SD 3.95 2.97 3.16 3.07 2.57 2.72 3.16 3.15
17
7. Statistical Results 4-way ANOVA and multiple comparison Sheffé test (α = .05) 1) Fracture strengths of monolithic zirconia specimens
Between-Subjects Factors
Value Label N
Size
1 25 120
2 50 120
3 125 120
4 Control 15
Pressure
1 2 bar 180
2 4 bar 180
3 Control 15
Time
1 10 s 180
2 20 s 180
3 Control 15
Angle
1 45° 180
2 90° 180
3 Control 15
18
Tests of Between-Subjects Effects Dependent Variable: strength
Source Type III Sum of
Squares df
Mean
Square F Sig.
Corrected Model 47331413.957a 24 1972142.248 59.639 .000
Intercept 587025775.613 1 587025775.613 17752.175 .000
Size 8702236.717 2 4351118.358 131.582 .000
Pressure 4848104.803 1 4848104.803 146.611 .000
Time 3724864.336 1 3724864.336 112.643 .000
Angle 11211.336 1 11211.336 .339 .561
Size × Pressure 20677986.906 2 10338993.453 312.660 .000
Size × Time 5909509.006 2 2954754.503 89.354 .000
Size × Angle 108795.139 2 54397.569 1.645 .194
Pressure × Time 353001.469 1 353001.469 10.675 .001
Pressure × Angle 126075.469 1 126075.469 3.813 .052
Time × Angle 3900.625 1 3900.625 .118 .731
Size × Pressure × Time 904131.439 2 452065.719 13.671 .000
Size × Pressure × Angle 257834.306 2 128917.153 3.899 .021
Size × Time × Angle 457854.717 2 228927.358 6.923 .001
Pressure × Time × Angle 348755.625 1 348755.625 10.547 .001
Size × Pressure × Time × Angle 588903.817 2 294451.908 8.904 .000
Error 11573738.000 350 33067.823
Total 1012104439.000 375
Corrected Total 58905151.957 374
a. R Squared = .804 (Adjusted R Squared = .790)
Estimated Marginal Means
Grand Mean
Dependent Variable: strength
Mean Std. Error 95% Confidence Interval
Lower Bound Upper Bound
1594.323a 9.390 1575.854 1612.792
a. Based on modified population marginal mean.
19
Post Hoc Tests
① Size
Multiple Comparisons Dependent Variable: strength
Scheffé
(I) Size (J) Size Mean
Difference (I-J) Std. Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
25
50 293.7333* 23.47617 .000 227.7855 359.6811 125 356.7917* 23.47617 .000 290.8439 422.7395 Control 363.1500* 49.80047 .000 223.2536 503.0464
50
25 -293.7333* 23.47617 .000 -359.6811 -227.7855 125 63.0583* 23.47617 .067 -2.8895 129.0061 Control 69.4167* 49.80047 .585 -70.4797 209.3131
125
25 -356.7917* 23.47617 .000 -422.7395 -290.8439 50 -63.0583* 23.47617 .067 -129.0061 2.8895 Control 6.3583* 49.80047 .999 -133.5381 146.2547
Control
25 -363.1500* 49.80047 .000 -503.0464 -223.2536 50 -69.4167* 49.80047 .585 -209.3131 70.4797 125 -6.3583* 49.80047 .999 -146.2547 133.5381
Based on observed means.
The error term is Mean Square (Error) = 33067.823.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
strength
Scheffé
Size N Subset
1 2
Control 15 1453.8667 125 120 1460.2250 50 120 1523.2833 25 120 1817.0167 Sig. .366 1.000
Means for groups in homogeneous subsets are isplayed. Based on observed means.
The error term is Mean Square (Error) = 33067.823.
a. Uses Harmonic Mean Sample Size = 43.636.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranted. c. Alpha = .05.
20
② Pressure
Multiple Comparisons Dependent Variable: strength
Scheffé
(I)
Pressure
(J)
Pressure
Mean Difference
(I-J) Std. Error Sig.
95% Confidence
Interval
Lower
Bound
Upper
Bound
2 bar 4 bar -232.0944* 19.16821 .000 -279.2149 -184.9740 Control 30.2611* 48.86954 .826 -89.8729 150.3951
4 bar 2 bar 232.0944* 19.16821 .000 184.9740 279.2149 Control 262.3556* 48.86954 .000 142.2215 382.4896
Control 2 bar -30.2611* 48.86954 .826 -150.3951 89.8729 4 bar -262.3556* 48.86954 .000 -382.4896 -142.2215
Based on observed means. The error term is Mean Square (Error) = 430.679.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
strength
Scheffé
Pressure N Subset
1 2
Control 15 1453.8667
2 bar 180 1484.1278
4 bar 180 1716.2222
Sig. .766 1.000
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 33067.823.
a. Uses Harmonic Mean Sample Size = 38.571.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
21
③ Time
Multiple Comparisons Dependent Variable: strength
Scheffé
(I) Time (J) Time Mean
Difference (I-J)
Std. Error Sig.
95% Confidence
Interval
Lower
Bound
Upper
Bound
10 s 20 s -203.4389* 19.16821 .000 -250.5593 -156.3185 Control 44.5889* 48.86954 .660 -75.5451 164.7229
20 s 10 s 203.4389* 19.16821 .000 156.3185 250.5593 Control 248.0278* 48.86954 .000 127.8938 368.1618
Control 10 s -44.5889* 48.86954 .660 -164.7229 75.5451 20 s -248.0278* 48.86954 .000 -368.1618 -127.8938
Based on observed means.
The error term is Mean Square (Error) = 430.679.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
strength
Scheffé
Time N Subset
1 2
Control 15 1453.8667
10 s 180 1498.4556
20 s 180 1701.8944
Sig. .561 1.000
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 33067.823.
a. Uses Harmonic Mean Sample Size = 38.571.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
22
④ Incidence angle
Multiple Comparisons Dependent Variable: strength
Scheffé
(I)
Angle
(J)
Angle
Mean Difference
(I-J) Std. Error Sig.
95% Confidence Interval
Lower
Bound
Upper
Bound
45° 90° -11.1611* 19.16821 .844 -58.2815 35.9593Control 140.7278* 48.86954 .017 20.5938 260.8618
90° 45° 11.1611* 19.16821 .844 -35.9593 58.2815Control 151.8889* 48.86954 .009 31.7549 272.0229
Control 45° -140.7278* 48.86954 .017 -260.8618 -20.593890° -151.8889* 48.86954 .009 -272.0229 -31.7549
Based on observed means.
The error term is Mean Square (Error) = 430.679.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
strength
Scheffé
Angle N Subset
1 2
Control 15 1453.8667
45° 180 1594.5944
90° 180 1605.7566
Sig. 1.000 .964
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 33067.823.
a. Uses Harmonic Mean Sample Size = 38.571.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed. c. Alpha = .05.
23
2) Shear bond strengths before thermocycling
Between-Subjects Factors
Value Label N
Size
1 25 80
2 50 80
3 125 80
4 Control 10
Pressure
1 2 bar 120
2 4 bar 120
3 Control 10
Time
1 10 s 120
2 20 s 120
3 Control 10
Angle
1 45° 120
2 90° 120
3 Control 10
24
Tests of Between-Subjects Effects Dependent Variable: Strength
Source Type III Sum
of Squares df
Mean
Square F Sig.
Corrected Model 1437.452a 24 59.894 7.363 .000
Intercept 22610.990 1 22610.990 2779.529 .000
Size 613.721 2 306.861 37.722 .000
Pressure 114.817 1 114.817 14.114 .000
Time 164.011 1 164.011 20.162 .000
Angle 2.904 1 2.904 .357 .551
Size × Pressure 61.961 2 30.981 3.808 .024
Size × Time 29.545 2 14.773 1.816 .165
Size × Angle .732 2 .366 .045 .956
Pressure × Time 1.411 1 1.411 .173 .677
Pressure × Angle 6.667 1 6.667 .820 .366
Time × Angle 1.014 1 1.014 .125 .724
Size × Pressure × Time 3.121 2 1.561 .192 .826
Size × Pressure × Angle 10.885 2 5.443 .669 .513
Size × Time × Angle 12.652 2 6.326 .778 .461
Pressure × Time × Angle 9.126 1 9.126 1.122 .291
Size × Pressure × Time × Angle 1.984 2 .992 .122 .885
Error 1830.336 225 8.135
Total 44994.220 250
Corrected Total 3267.788 249
a. R Squared = .440 (Adjusted R Squared = .380)
Estimated Marginal Means
Grand Mean
Dependent Variable: Strength
Mean Std. Error 95% Confidence Interval
Lower Bound Upper Bound
12.919a .180 12.564 13.275
a. Based on modified population marginal mean.
25
Post Hoc Tests
① Size
Multiple Comparisons Dependent Variable: Strength
Scheffé
(I) Size (J) Size
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
25
50 -2.8550* .45097 .000 -4.1253 -1.5847
125 .8950 .45097 .271 -.3753 2.1653
Control 5.8250* .95664 .000 3.1304 8.5196
50
25 2.8550* .45097 .000 1.5847 4.1253
125 3.7500* .45097 .000 2.4797 5.0203
Control 8.6800* .95664 .000 5.9854 11.3746
125
25 -.8950 .45097 .271 -2.1653 .3753
50 -3.7500* .45097 .000 -5.0203 -2.4797
Control 4.9300* .95664 .000 2.2354 7.6246
Control
25 -5.8250* .95664 .000 -8.5196 -3.1304
50 -8.6800* .95664 .000 -11.3746 -5.9854
125 -4.9300* .95664 .000 -7.6246 -2.2354
Based on observed means.
The error term is Mean Square (Error) = 8.135.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Size N Subset
1 2 3
Control 10 6.7000
125 80 11.6300
25 80 12.5250
50 80 15.3800
Sig. 1.000 .698 1.000
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 8.135.
a. Uses Harmonic Mean Sample Size = 29.091.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
26
② Pressure
Multiple Comparisons
Dependent Variable: Strength
Scheffé
(I)
Pressure
(J)
Pressure
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower
Bound
Upper
Bound
2 bar 4 bar -1.3833* .36821 .001 -2.2907 -.4760
Control 5.7867* .93876 .000 3.4734 8.0999
4 bar 2 bar 1.3833* .36821 .001 .4760 2.2907
Control 7.1700* .93876 .000 4.8568 9.4832
Control 2 bar -5.7867* .93876 .000 -8.0999 -3.4734
4 bar -7.1700* .93876 .000 -9.4832 -4.8568
Based on observed means.
The error term is Mean Square (Error) = 8.135.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Pressure N Subset
1 2
Control 10 6.7000
2 bar 120 12.4867
4 bar 120 13.8700
Sig. 1.000 .223
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 8.135.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
27
③ Time
Multiple Comparisons
Dependent Variable: Strength
Scheffé
(I)
Time
(J)
Time
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
10 s 20 s -1.6533* .36821 .000 -2.5607 -.7460
Control 5.6517* .93876 .000 3.3384 7.9649
20 s 10 s 1.6533* .36821 .000 .7460 2.5607
Control 7.3050* .93876 .000 4.9918 9.6182
Control 10 s -5.6517* .93876 .000 -7.9649 -3.3384
20 s -7.3050* .93876 .000 -9.6182 -4.9918
Based on observed means.
The error term is Mean Square (Error) = 8.135.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Time N Subset
1 2
Control 10 6.7000
10 s 120 12.3517
20 s 120 14.0050
Sig. 1.000 .118
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 8.135.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
28
④ Incidence angle
Multiple Comparisons
Dependent Variable: Strength
Scheffé
(I)
Angle
(J)
Angle
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower
Bound
Upper
Bound
45° 90° .2200 .36821 .837 -.6873 1.1273
Control 6.5883* .93876 .000 4.2751 8.9016
90° 45° -.2200 .36821 .837 -1.1273 .6873
Control 6.3683* .93876 .000 4.0551 8.6816
Control 45° -6.5883* .93876 .000 -8.9016 -4.2751
90° -6.3683* .93876 .000 -8.6816 -4.0551
Based on observed means.
The error term is Mean Square (Error) = 8.135.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Angle N Subset
1 2
Control 10 6.7000
90° 120 13.0683
45° 120 13.2883
Sig. 1.000 .962
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 8.135.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
29
3) Shear bond strengths after thermocycling
Between-Subjects Factors
Value Label N
Size
1 25 80
2 50 80
3 125 80
4 Control 10
Pressure
1 2 bar 120
2 4 bar 120
3 Control 10
Time
1 10 s 120
2 20 s 120
3 Control 10
Angle
1 45° 120
2 90° 120
3 Control 10
30
Tests of Between-Subjects Effects Dependent Variable: Strength
Source Type III Sum
of Squares df
Mean
Square F Sig.
Corrected Model 1207.001a 24 50.292 7.216 .000
Intercept 11288.656 1 11288.656 1619.757 .000
Size 405.304 2 202.652 29.078 .000
Pressure 49.142 1 49.142 7.051 .008
Time 81.434 1 81.434 11.685 .001
Angle 5.340 1 5.340 .766 .382
Size × Pressure 9.421 2 4.711 .676 .510
Size × Time 40.827 2 20.414 2.929 .055
Size × Angle .450 2 .225 .032 .968
Pressure × Time 9.204 1 9.204 1.321 .252
Pressure × Angle .368 1 .368 .053 .818
Time × Angle 1.148 1 1.148 .165 .685
Size × Pressure × Time 144.922 2 72.461 10.397 .000
Size × Pressure × Angle 4.260 2 2.130 .306 .737
Size × Time × Angle 7.862 2 3.931 .564 .570
Pressure × Time × Angle 3.901 1 3.901 .560 .455
Size × Pressure × Time × Angle 7.203 2 3.601 .517 .597
Error 1568.104 225 6.969
Total 25106.400 250
Corrected Total 2775.105 249
a. R Squared = .435 (Adjusted R Squared = .375)
Estimated Marginal Means
Grand Mean
Dependent Variable: Strength
Mean Std. Error 95% Confidence Interval
Lower Bound Upper Bound
9.451a .167 9.122 9.780
a. Based on modified population marginal mean.
31
Post Hoc Tests
① Size
Multiple Comparisons Dependent Variable: Strength
Scheffé
(I) Size (J) Size Mean
Difference (I-J)
Std.
Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
25
50 -3.0475* .41741 .000 -4.2233 -1.8717
125 -.7275 .41741 .388 -1.9033 .4483
Control 5.4825* .88547 .000 2.9883 7.9767
50
25 3.0475* .41741 .000 1.8717 4.2233
125 2.3200* .41741 .000 1.1442 3.4958
Control 8.5300* .88547 .000 6.0358 11.0242
125
25 .7275 .41741 .388 -.4483 1.9033
50 -2.3200* .41741 .000 -3.4958 -1.1442
Control 6.2100* .88547 .000 3.7158 8.7042
Control
25 -5.4825* .88547 .000 -7.9767 -2.9883
50 -8.5300* .88547 .000 -11.0242 -6.0358
125 -6.2100* .88547 .000 -8.7042 -3.7158
Based on observed means.
The error term is Mean Square (Error) = 6.969.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Size N Subset
1 2 3
Control 10 2.9800
25 80 8.4625
125 80 9.1900
50 80 11.5100
Sig. 1.000 .776 1.000
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 6.969.
a. Uses Harmonic Mean Sample Size = 29.091.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
32
② Pressure
Multiple Comparisons Dependent Variable: Strength
Scheffé
(I)
Pressure
(J)
Pressure
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower
Bound
Upper
Bound
2 bar 4 bar -.9050* .34082 .031 -1.7448 -.0652
Control 6.2883* .86891 .000 4.1472 8.4295
4 bar 2 bar .9050* .34082 .031 .0652 1.7448
Control 7.1933* .86891 .000 5.0522 9.3345
Control 2 bar -6.2883* .86891 .000 -8.4295 -4.1472
4 bar -7.1933* .86891 .000 -9.3345 -5.0522
Based on observed means.
The error term is Mean Square (Error) = 6.969.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Pressure N Subset
1 2
Control 10 2.9800
2 bar 120 9.2683
4 bar 120 10.1733
Sig. 1.000 .471
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 6.969.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
33
③ Time
Multiple Comparisons Dependent Variable: Strength
Scheffé
(I) Time (J) Time
Mean
Difference
(I-J)
Std. Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
10 s 20 s -1.1650* .34082 .003 -2.0048 -.3252
Control 6.1583* .86891 .000 4.0172 8.2995
20 s 10 s 1.1650* .34082 .003 .3252 2.0048
Control 7.3233* .86891 .000 5.1822 9.4645
Control 10 s -6.1583* .86891 .000 -8.2995 -4.0172
20 s -7.3233* .86891 .000 -9.4645 -5.1822
Based on observed means.
The error term is Mean Square (Error) = 6.969.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Time N Subset
1 2
Control 10 2.9800
10 s 120 9.1383
20 s 120 10.3033
Sig. 1.000 .288
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 6.969.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed
c. Alpha = .05.
34
④ Incidence angle
Multiple Comparisons Dependent Variable: Strength
Scheffé
(I)
Angle
(J)
Angle
Mean
Difference (I-J)
Std.
Error Sig.
95% Confidence Interval
Lower Bound Upper Bound
45° 90° -.2983 .34082 .682 -1.1382 .5415
Control 6.5917* .86891 .000 4.4505 8.7328
90° 45° .2983 .34082 .682 -.5415 1.1382
Control 6.8900* .86891 .000 4.7489 9.0311
Control 45° -6.5917* .86891 .000 -8.7328 -4.4505
90° -6.8900* .86891 .000 -9.0311 -4.7489
Based on observed means.
The error term is Mean Square (Error) = 6.969.
*. The mean difference is significant at the .05 level.
Homogeneous Subsets
Strength
Scheffé
Angle N Subset
1 2
Control 10 2.9800
45° 120 9.5717
90° 120 9.8700
Sig. 1.000 .921
Means for groups in homogeneous subsets are displayed. Based on observed
means. The error term is Mean Square (Error) = 6.969.
a. Uses Harmonic Mean Sample Size = 25.714.
b. The group sizes are unequal. The harmonic mean of the group sizes is used.
Type I error levels are not guaranteed.
c. Alpha = .05.
문 록
다양한 샌드블라스 건 단 지 코니아
물 레진 시 트 착강도에 미치는
과에 한 연
울 학 학원 치 과학과 치과보철학 공
(지도 수 훈)
문 지
연 : 지 코니아 보철물 간 안 레진시 트 착
하여 시행하는 샌드블라스 지 코니아 상 변 야 하고
아가 물 에 향 주 문에 샌드블라스 건 달리하여
단 지 코니아 물 레진시 트 착력 측 하여
건 가진 샌드블라스 프로 콜 시하고 한다.
재료 : 샌드블라스 건 – 알루미 (25, 50, 125㎛),
사 압력(2bar, 4bar), 사 각도(45°, 90°), 사 시간(10 , 20 )
달리하고 포함하여 25개 그룹 단 지 코니아
시편 비하 다. 시편 강도실험 하여 bar 태(45 × 3 ×
4mm) 시편 그룹당 15개씩 하여 에 한 건 로
샌드블라스 시행한 3 강도 시행하고 블 계수
특 강도 계산하 다. 또한 X 통한 단사 상 변 측 ,
공 주사 레 미경 한 거칠 측 , 원 력 미경
통한 찰, 라만 한 에 상 변 ,
주사 미경 통한 찰하 다. 동시에 원 태(Ø 9 ×
1mm) 시편 그룹당 20개씩 비하여 레진시 트 ( 비아 F2.0)
착 후에 각 그룹당 10개씩 2개 하 그룹 로 다시 한 후
한쪽만 5000 열순 시행하여 열순 과 후 레진시 트
결합강도 차 측 하여 비 하 다.
통계는 4개 변수 상 고려한 사원 산 통하여
하고 검 그룹 리 Sheffé 사후검
시행하여 동 집단 하 다 (α = .05)
결 과 : 블 포에 특 강도는 25㎛에 가 게 타났
같 내에 는 변태강 상과 미 재료 강도에 동시에
향 쳤다. 25㎛에 는 변태강 향 로 강도가 게
가하 50과 125㎛ 강도는 과 통계
견 지 않았다. 거칠 는 가 클수록, 압력 수록, 시간
수록, 각도가 클수록 가하 다. 단사 가 클수록, 압력
수록, 각도가 클수록 많 생하 지만 시간 차 는 크지 않았다.
라만 에 알루미늄 사 드 가 마찰시킨 에
단사 포비 에 가 울수록 많 재하 10㎛
후에 는 사라짐 보 다. 원 력 미경 통한 재료
찰 보 에 비해 실험 에 게는 10 , 많게는 18
상 로 들 찰할 수 었 주사 미경 통해
가 클수록, 압력 크고 시간 수록 거칠고 큰 틈과 철 가진
지 코니아 볼 수 었다. 레진 시 트 결합력 열순
후 50㎛에 가 게 타났 같 내에 시간
수록, 압력 수록 게 결합력 찰 었다.
크 , 압력, 시간, 각도 4개 각도 한 지 3개
가 강도 레진시 트 단강도 값에 는 향
미치는 것 로 타났다.
결 론 : 알루미 한 샌드블라스 단 지 코니아
결 변 시키고 결함 포 꾸어 강도
물 에 향 미쳤 레진시 트 결합강도 게
가시켰다. 실험에 하여 천 는 샌드블라스 건 각도
상 없 50㎛, 4 bar, 20 다.
주 어: 단 지 코니아, 강도, 상 변 , 결합강도, 레진시 트
학 : 2010-31187
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