الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 131 |  |  |
| | | from | 131 | | |
Abstract
SUMMARY
D
ental ceramics are considered chemically inert restorative materials. However, many factors such as the composition, microstructure, chemical properties of ceramic material, erosive or acidic agents, exposure time, and the temperature, mastication forces may influence the durability of dental ceramics.
The clinical performance of the new dental ceramics in such cases still unknown. Therefore, this study was designed to evaluate the effect of gastric acid on surface topography, chemical wear and translucency of three types of monolithic dental ceramics, as representative of currently used dental ceramics in a clinical setting: lithium disilicate glass-ceramic (IPS e.max CAD blocks), zirconia reinforced lithium silicate (Vita suprinity), Monolithic yttrium partially stabilized zirconia (bruxzir). The samples (14x12x1mm) were cut, sintered, finished, polished, glazed and cleaned before immersed in 5 ml of simulated gastric acid solution (hydrochloric acid (HCl) 0.06 M, 0.113% solution in deionized distal water, pH1.2) for 96h in a 37°c incubator. Samples were weighed by sensitive digital weighing scale accurate up to 0.0001 gm . VITA Easy shade Advance 4.0 was used for measuring translucency. roughness values were measured using profilometer (TR220 portable roughness Tester)before and after acid immersion . The measurement of ions and elements leached from 7each type of ceramic material is done by inductively coupled plasma optical emission spectroscopy (ICP-QQQ) .
The results revealed that erosion had significant effect on translucency, regarding the ceramic material there was significant difference between different materials. (IPS e.max) had the highest translucency followed by (Vita suprinity) then (Bruxzir). Regarding chemical erosion samples had a significantly higher translucency before chemical erosion.
The results also, showed that, there was a significant difference between different ceramic materials measured for roughness. Before chemical erosion, (Bruxzir) had the highest roughness value followed by (IPS e.max) and (Vita suprinity). After chemical erosion, (Vita suprinity) had the highest roughness value followed by (IPS e.max) then (Bruxzir) to be significantly different from other materials.
The results of wear measurments revealed that, according to ceramic material there was significant difference between different ceramic materials before chemical erosion, (Bruxzir) had the highest roughness value. Followed by (IPS e.max)and (Vita suprinity) with equal means. acid immersion indicated a weight loss with the Bruxzir bearing the higher % of weight reduction compared to e.max and Vita suprinity.
While, the results of ions analysis showed that there was a significant difference in release rates of the different ions among each material, it was obvious that the composition of ceramics strongly affects the surface dissolution.