Abstracts of the Academy of Dental Materials Annual ... - IsiRed

e48 dental materials 26S (2010) e1–e84
Table1–.
Ceramic Brand/ Number of firing cycles
manufacturer
1 4 7
CO-ZR Cerabien
ZR/Noritake
25.4 ± 3.0a 22.8 ± 1.8a 21.8 ± 2.2a DK Duceram
Kiss/Degudent
29.5 ± 1.8a 28.1 ± 3.0a,b 25.0 ± 2.2b EMAX E.max
ceram/Ivoclar
17.3 ± 1.4a 20.4 ± 2.1a 19.1 ± 0.8a VAL Vintage
AL/Shofu
27.0 ± 1.0a 27.0 ± 1.0a 26.5 ± 0.5a VH Vintage
Halo/Shofu
18.8 ± 4.1a 19.1 ± 2.9a 18.5 ± 1.9a VM7 VM7/Vita 17.0 ± 2.6a 19.4 ± 1.9a 17.6 ± 1.1a VM9 VM9/Vita 25.3 ± 1.0a 27.1 ± 2.2a 24.3 ± 2.1a VZR Vintage
ZR/Shofu
16.8 ± 1.1b 27.2 ± 0.6a 25.1 ± 0.8a * Within the same line, values followed by the same superscript are
statistically similar (p > 0.05).
standard cards as background: black (CIE L* = 24.58, a* = 0.27,
b* = 2.58) and white (CIE L* = 92.95, a*=−0.78, b* = 3.57). All measurements
were performed after 1, 4 and 7 firing cycles in the
diffuse reflectance mode (range of between 400 and 700 nm
and intervals of 10 nm). Fixed parameters were: illumination
of CIE D65 (day light, 6500 K) and observer at 2◦ . TP was determined
by: TP = [(L∗ b − L∗w )2 + (a∗ b − a∗w )2 + (b∗ b − b∗w )2 ] 1/2
, where
the subscripts b and w indicate the color of the background
(black and white, respectively). Results were analyzed by
ANOVA and Tukey’s test (˛ = 0.05).
Results: The mean TP value obtained for dental enamel
was 18.4 (±2.7). The values of TP as a function of the ceramic
material and number of firing cycles are shown in Table 1. The
results indicated that these materials can be divided in 3 distinct
groups: (a) those for which the TP was not significantly
affected by the multiple firing cycles and all values were similar
to that of the enamel (EMAX, VH and VM7), (b) those for
which TP was not significantly affected by the multiple firing
cycles but the values were statistically different from that of
the enamel (CO-ZR, VAL, and VM9); and (c) those for which
the TP values were significantly affected by the multiple firing
cycles (DK and VZR).
Conclusions: Only two materials showed the same translucency
level compared to dental enamel, regardless of the
number of firing cycles. The effect of multiple sintering cycles
on the TP values depended on the ceramic material studied.
doi:10.1016/j.dental.2010.08.109
102
Risks of ceramic veneer fracture under different occlusal loading
conditions
Y. Chaiyabutr 1 , J.C. Kois 1 , V. Isvilanonda 2
1 Kois Center, USA
2 University of Washington, USA
Objectives: This study used 2D finite element analysis to
investigate the risks of ceramic fracture and cement failures
on maxillary central incisors when different ceramic veneer
preparation designs and occlusal conditions were applied.
Materials and methods: The software ANSYS version 10.0
was used to develop a FEA mesh consisting of 23,974–42,291
elements and 73,037–128,941 nodes. Two different preparation
designs were tested: incisal shoulder finish line (FI) and
incisal shoulder finish line with a palatal chamfer margin (FIP).
The materials used in this study were pressable ceramics (IPS
Empress) and resin-based luting agents (RelyX Veneer). The
maximum principal stress ( max) in all models was calculated
from four interincisal load angulations: 90 ◦ , 120 ◦ , 135 ◦ and 160 ◦
to the long axis of the tooth. A 120-N, which is the maximum
human bite force for maxillary anterior teeth (Kumagai et al. J
Oral Rehabil 1999;26:932), was applied on the palatal surfaces
of ceramic veneers at 2 mm from the incisal edges. The risks of
ceramic fracture (RCF) were calculated by dividing the tensile
( max) stress (registered in material) by its tensile strength (TS)
as described in the literatures. The tensile and shear stresses
in the ceramic and resin cement interfaces were analyzed to
determine the risks of cement failures (RCEF).
Results:
Models Ceramic Cement Maximum crown
displacement
(mm)
max TS RCF max TS RCEF
FI-90 138.2 135.0 1.02 109.5 77.6 1.41 1.65
FIP-90 152.2 135.0 1.13 93.1 77.6 1.20 1.45
FI-120 125.5 135.0 0.93 74.5 77.6 0.96 1.36
FIP-120 113.1 135.0 0.84 45.2 77.6 0.58 1.14
FI-135 100.4 135.0 0.74 43.5 77.6 0.56 1.08
FIP-135 91.3 135.0 0.68 26.9 77.6 0.35 0.87
FI-160 94.6 135.0 0.70 13.9 77.6 0.18 0.44
FIP-160 85.1 135.0 0.63 12.0 77.6 0.15 0.35
Conclusions: Interincisal load angulation has effects on the
biomechanical behavior of ceramic veneers in terms of stress
distribution, risks of ceramic fracture and cement failures. In
most loading conditions, the shoulder finish line is susceptible
to tensile stress in ceramic 10–15% higher than the other
samples, suggesting higher risks of ceramic fracture. This
trend, however, excludes interincisal load angulation at 90 ◦ .
Increasing interincisal load angulation contributes to lower
tensile stress in cements, suggesting lower risks of cement
failures for both preparation designs. As the interincisal load
angle increases, the maximum displacement of the crown
decreases.
doi:10.1016/j.dental.2010.08.110
103
Shade match of two ceramic systems with 3D-Master
Toothguide
G. Corciolani, A. Vichi, M. Sedda, C. Goracci, M. Ferrari
University of Siena, Italy
Objectives: The purpose of this study was to test the ability
of two different dental porcelains to correctly reproduce
the selected color with reference to 3D-Master Toothguide by
using a clinical spectrophotometer.
Materials and methods: Two ceramic systems were
selected for this study, Vita Omega 900 and Vita VM13. Three
shades in Vita 3D-Master Toothguide were selected for each
system, 2M3, 3M2 and 4M2. 30 ceramic discs, 15 mm in diameter,
were fabricated with 2 different layering schemes (LS)