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

for each ceramic system, maintaining the overall total thickness
at 1.3 mm. The thicknesses of the layers were: metal
base disc 0.3 mm, opaque 0.15 mm, dentin opaque 0.35 mm
and 0.45 mm, dentin 0.5 mm and 0.7 mm, enamel 0.1 mm and
0.2 mm. The thickness of each layer was verified after each firing.
A clinical spectrophotometer (Vita Easyshade) was used
for color comparison in “Restoration” mode, which allows
comparing the instrument set color data with the measured
ones. The obtained �E values (differences between intended
and obtained shade) were statistically analyzed with a 3-way
ANOVA and the Tukey HSD test (˛ = 0.05).
Results:
Shade LS Ceramic �E Significance
2M3 1 VM13 0.98 (0.08) a
Omega 900 0.88 (0.08) a
2 VM13 1.40 (0.12) b
Omega 900 1.94 (0.09) c
3M2 1 VM13 1.06 (0.08) a
Omega 900 1.76 (0.05) c
2 VM13 1.48 (0.08) b
Omega 900 1.48 (0.04) b
4M2 1 VM13 0.96 (0.09) a
Omega 900 1.90 (0.07) c
2 VM13 1.42 (0.08) b
Omega 900 0.96 (0.11) a
Significance column = homogeneous subsets (Tukey HSD test
level = 0.05).
Interaction shade × LS × ceramic (F = 189.62, p < 0.001).
Conclusions: Both Vita VM13 and Vita Omega 900 ceramics
exhibited a close shade match with reference to the selected
shades of the Vita 3D Master Toothguide. The layering scheme
has influenced the final color of the restorations.
doi:10.1016/j.dental.2010.08.111
104
Precision of different transfer impression techniques in multiple
implants
F.L.G. Cruz 1 , J.C.B. de Faria 2 , F.P.P. Leite 1 , A.P.P. Leite 1 ,Mgam
Chaves 1 , L.R.S. Concílio 2 , A.C.C. Neves 2
1 Universidade Federal De Juiz De Fora, Brazil
2 Universidade de Taubaté, Brazil
Objectives: The aim of this study is to compare different
materials and techniques used in multiple implant transfer
impressions, measuring the gap between superstructure and
implants.
Materials and methods: Four external hexagonal implants
(Neodent, Curitiba, Brazil) were fixed in a master cast and
over a superstructure. Afterwards, the impressions were made
using polyether (Impregum, 3M Espe, Seefeld, Germany) and
condensation silicone (Speedex, Coltène AG, Altstatten SG,
Swiss), using open and closed tray techniques with splinted
and non-splinted implant transfers. Auto (Duralay) or photopolymerized
(Duolay) acrylic resin was used for the splints
dental materials 26S (2010) e1–e84 e49
and the implant transfers were splinted, or not, resulting in
sixteen groups with five casts in each. The space between
master superstructure and the implants was measured using
a microscope, with a precision of 0.0005 mm and data were
statistically analyzed by T test (=0.05) and Mann–Whitney.
Results: With regard to the impression material tested, no
significant differences were observed, with the exception of
the groups that used photopolymerized Duolay resin to splint
transfers (groups 7 and 15) (p = 0.012). Regarding splint material,
no significant differences were observed, except for the
groups that employed autopolymerized Duralay (group 4) and
photopolymerized Duolay (group 8) for the splint, and that
were subsequently re-splinted (p = 0.004) with autopolymerized
Duolay (group 5) and photopolymerized Duolay (group
7) (p = 0.012). When comparing the techniques with divided
and re-splinted techniques with non-divided techniques, no
significant differences were observed (group 3 × group 4 –
p = 0.158; group 5 × group 6 – p = 0.094; group 7 × group 8 –
p = 0.144; group 11 × group 12 – p = 0.331; group 13 × group 14
– p = 0.203; and group 15 × group 16 – p = 0.092).
Conclusions: The impression materials provided similar
results, favoring the use of condensed silicone due to its lower
cost. The autopolymerized acrylic resin was better than photopolymerized
resin for use in the splint implant transfers.
The techniques with splinted transfers or non-splinted transfers
provided similar results.
doi:10.1016/j.dental.2010.08.112
105
Effect of hydrothermal aging on zirconia crystal phases and
strength
R. Dittmann ∗ , E. Mecher, A. Schmalzl, T. Kuretzky
3M ESPE, AG, Seefeld, Germany
Objectives: Yttria-stabilized zirconia is a state of the art
material for all ceramic dental restorations. In humid atmosphere
tetragonal to monoclinic phase transformation can
slowly occur at the outer surface of the zirconia ceramic
(Chevalier et al. J Am Ceram Soc 1999;82(8):2150). The purpose
of this study was to investigate the phase transformation of
two dental zirconia materials due to hydrothermal accelerated
aging and the effect on biaxial fracture strength.
Materials and methods: Disks (d =14mm, t = 1.5 mm) were
prepared from Lava Frame zirconia (3M ESPE) and a commercial
available generic dental zirconia. The samples were
sintered according to the recommendations of the manufacturers,
grinded plane-parallel and final polished on one side
with a 1 �m diamond suspension. Afterwards all samples were
thermally etched at 1350 ◦ C for 30 min to avoid effects of phase
transformation induced by grinding and polishing.
Samples of both zirconia materials were split into two
groups (n = 15 each group). One group of each material was
characterized initially and the other group was hydrothermal
aged in a steam autoclave at 135 ◦ C, 2 bar for 5 h.
X-ray measurements were performed on n = 5 samples each
group in Bragg-Brentano geometry (Bruker D8 Discover) and
quantitative phase analysis were done by the Rietveld method
(Bruker TOPAS software). Biaxial fracture strength measure-