الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 104 |  |  |
| | | from | 104 | | |
Abstract
The purpose of this study was to evaluate the effect of sol-gel Nanosilica Coating on the Microleakage and the Color change of Zirconia Ceramics.
Eighty-five samples of commercially available zirconia ceramics were fabricated and divided into forty-five discs (8 mm in diameter) with thickness (1.2mm) They were divided into three groups (thermocycling aging – nano-silica surface treatment – and thermocycling aging with nano-silica surface treatment) to assess the color parameters, while the other forty samples were fabricated into crowns and divided into ( control group – thermocycling aging – nano-silica surface treatment – and thermocycling aging with nano-silica surface treatment) to perform a fully contoured crowns to assess the microleakage.
Initial color measurements were measured using a digital spectrophotometer based on CIE L*a*b* color system using a spectrophotometer. Standard permanent molar tooth preparation was conducted into a full veneer preparation.
Zirconia crowns were dipped into nano silica sol-gel material in groups of nano-silica and nano-silica with thermocycling aging surface treatment and processed to firing that were finally cemented on the prepared teeth using resin adhesive luting agent. Samples in aged group were subjected to 5000 thermal cycles then crown samples were sectioned to measure the microleakage.
Color measurements of all samples were measured again. Data were analyzed using two-way ANOVA followed by Bonferroni and paired sample t-tests with a significance level set at P=0.05.
the results showed that the Silica treated group showed the lowest microleakage record of 908.5 ± 83.88μm, followed by silica aging with mean of 908.5 ± 83.88μm. The mean of the control group with no surface treatment recorded with 1300.4 ± 79.37μm, followed by thermocycling treated group with the largest microleakage with mean of 2011.1 ± 111.7μm. Concerning color change the findings in this study revealed that the highest ΔE values among the three groups were noted in silica-aging group with values of ΔE=3.27 ± 0.72 while the lowest one was recorded for aging with values of ΔE=1.26 ± 0.29.
Nano-silica sol-gel surface treatment showed higher color change compared with thermocycling and low color change compared with silica treatment with thermocycling. Concerning microleakage, the nano-silica surface treatment showed lower microleakage compared with no surface treatment for zirconia surface.