الفهرس 
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Abstract
There is a new era in dentistry called elective cosmetic therapy. It is made possible by bonding small bits of tooth-colored restorative materials to teeth, and the long-term aesthetic and functional results are expected to be great.
The majority of fractures occur because the adhesive fails at the porcelain/cement interface, either by completely debonding or by breaking the restoration. With the help of adhesive bonding technology, dentists can now place a thin, brittle restorative material on the tooth that will not debond even when chewing normally. Additionally, ceramic restorations in the anterior zone became the norm because to the rising demand and desire in attaining ultimate esthetic. Imitation of the natural tooth’s color stability and translucency is crucial for all-ceramic indirect restorative materials to be successful in the long run. One of the most common reasons to repair cosmetic restorations is when their color changes or no longer matches the hue of the tooth structure around them.
Two primary objectives guided the experimental design of the present investigation. Firstly, we compared the optical qualities, specifically color stability and translucency parameter, both before and after the thermocycling artificial aging process. The second portion involved comparing the mechanical characteristics, namely the shear bond strength, before and after hydrofluoric acid etching and sandblasting, two surface treatment regimens, and the thermocycling process. Instead of using lithium disilicate glass ceramic, we are using new color-gradient monolithic zirconia.
One hundred twenty specimens, made from two distinct kinds of dental ceramics, with final dimensions of 10 mm width x 10 mm length and 0.5 mm thickness, were used in this investigation.
Based on the kind of dental ceramic, 60 samples were split into two groups, with shade A2 in the vita shade guide:
Advanced ceramic material: IPS e.max Html CAD
Ceramics from group B: IPS e.max Prime ZirCAD
Twenty samples for color, twenty for transparency, and eighty for shear bond strength made up each of the two primary groups’ three subgroups. Artificial aging was used as a criterion to further separate these three divisions into two categories. Lastly, the surface treatment type was used to separate the shear bond strength classes into two subclasses, each with ten samples.
The specimens were thermo-cycled using the THE-1100 SD Mechatronics thermo-cycler between 5OC and 55oC for 5000 cycles to mimic the oral cavity medium.
Before and after age, a spectrophotometer was used to measure the color parameters (hue, value, chroma) and translucency parameters for all samples. The values were represented in the CIELAB color space.
All surface-treated samples that had resin cement tags attached were subjected to a macro-shear bond strength test.
A one-way Student (Unpaired-sample) ”t” test was employed for intergroup comparison and statistical analysis of the tabulated results.After comparing zirconia ceramic with lithium disilicate glass ceramic, statistical analysis showed that there was no discernible variation in ΔE. In terms of the effect of thermocycling on the translucency parameter of the two ceramics, there was no discernible variation across all categories. In terms of translucency and shear bond strength, lithium disilicate ceramic outperformed the innovative color-gradient zirconia. When it came to treating lithium disilicate ceramic, HF acid etching and silanation had a much higher (mean±SD) value than sandblasting, but when it came to zirconia ceramic, sandblasting had a much higher (mean±SD) value than hydrofluoric acid etching.