الفهرس 
Zirconia
Glass-infiltrated zirconia toughened aluminaOnly 14 pages are availabe for public view
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Abstract
One of the most difficult challenges in esthetic dentistry is obtaining
an exact color match between natural teeth and an artificial restoration
making the visual recognition of the inserted restoration a difficult task even
for well-trained eyes. The achievement of an all-ceramic esthetic restoration
that matches perfectly with adjacent teeth is the result of the interplay
between two important optical factors: on one hand, the masking capacity of
ceramics to block the background color, and on the other hand, the amount of
translucency of the ceramic that will allow the natural background color shine
throughout a translucent material and exhibit the most natural appearance.
Recent developments in ceramic technology and evolutionary treatment
methods have all increased the predictability of all-ceramic restorations. The
introduction of partially stabilized zirconium dioxide to the dental field
opened new design and application limits of all-ceramic restorations allowing
a minimum framework thickness of 0.5 mm with the remaining thickness of
the restoration used for building the ceramic veneer. In the oral environment,
all-ceramic materials are prone to aging. Aging can lead all-ceramic materials
to change color. Accelerated aging simulates the effects of long-term
exposure to environmental conditions through an artificial weathering process
that involves light exposure, temperature and humidity.
The purpose of this study was to compare color parameters and
translucency of zirconia samples veneered by different veneering techniques
in order to examine the effect of veneering techniques and materials on
esthetics of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) allceramic restorations, and to estimate color and translucency stability under
the effect of aging.Twenty five slice specimens (0.50 ± 0.01 mm thick) were fabricated
of IPS e.maxZirCAD core material, and ZL1 IPS e.maxZirLiner (0.10-mm
thick) was layered. The specimens were randomly divided into five groups
(n=5/group). group Ι (traditional layering technique) was veneered 0.60 mm
by condensing and sintering IPS e.max Ceram low-fusing nano-fluorapatite
veneering porcelain; group ΙΙ (High translucency fully anatomical technique)
was veneered 0.60mm by heat-pressing HT IPS e.maxZirPressfluorapatite
glass-ceramic ingots; GroupΙΙΙ(Low translucency fully anatomical technique)
was veneered 0.60mm by heat-pressing HT IPS e.maxZirPressfluorapatite
glass-ceramic ingots; group ΙѴ(High translucency CAD-ON technique) was
veneered 0.60mm by HT IPS e.max CAD lithium disilicate glass ceramic
blocks and GroupѴ (Low High translucency CAD-ON technique) was
veneered 0.60mm by HT IPS e.max CAD lithium disilicate glass ceramic
blocks . Color parameters (L∗, a∗, b∗) were measured with Vita easy shade
compact and translucency were calculated .Color difference (∆E) were
measured using restoration mode in Vita easy shade compact. One-way
analysis of variance (ANOVA) combined with Bonferroni’s post-hoc test
were used to analyze the data (α = 0.05).
The results of this study showed that change in veneering technique
affected both color and translucency of zirconia-based ceramic prostheses and
that aging had an effect on both color and translucency of zirconia-based
ceramic prostheses.