الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 165 |  |  |
| | | from | 165 | | |
Abstract
Recently a new class of ceramics called resin nano ceramic, was introduced to the market. This category combines properties of both ceramics and composite materials. However, few studies were done on this new category to confirm its performance.
This in-vitro study compared the wear performance, surface roughness and microharndess of a resin nano ceramic (Lava Ultimate) to a lithium disilicate glass ceramic (IPS e.max CAD).
For wear performance test, two main groups; Test group 1: Lava Ultimate and Test group 2: IPS e.max CAD; were tested in the current study. Each group consisted of eight ceramic specimens and eight enamel antagonist. Ceramic specimens were cut in the form of slices of (14 mm x 12mm x 4.0 mm), from size ’14’ ceramic blocks. Concerning the enamel antagonists; mesio-palatal cusps of similar shape were isolated from intact maxillary 1st molars. In order to simulate the oral environment, ceramic specimens were subjected to mechanical brushing first, afterward they were tested against enamel antagonist. All specimens‟ weight were assessed before and after wear test using a sensitive balance. The amount of wear was determined on the basis of weight loss from the following equation: Wear (percent weight loss) = ΔW x 100/ W1.
Concerning surface roughness test; Qualitative and Quantitative analysis of the specimens and their antagonists were carried out before and after wear performance test using Atomic Force Microscopy (AFM). A comparison was made between the two groups using mean surface roughness (Ra) values and 3-D images.
As regard to Vickers microhardness test; specimens of Lava Ultimate (n=8) (group 3); and specimens of IPS e.max CAD (n=8) (group 4); were fabricated with the following dimensions: (12.0 mm x 6.0 mm x 4.0 mm). These specimens served as control group for baseline microharness values. Moreover, microhardness was evaluated for ceramic specimens of group 1 and group 2 after finishing the wear test. These values were compared to baseline values of control group.
Summary
97
After wear, Lava Ultimate showed higher material loss than IPS e.max CAD, however, the difference was not significant. Furthermore, Lava ultimate caused significantly less wear to the enamel antagonist than IPS e.max CAD. Concerning surface roughness, Lava Ultimate showed higher surface roughness before starting and throughout the test. Also the percentage of change of this resin nano ceramic material was higher during all the testing procedures. As for microhardness, IPS e.max CAD showed significantly higher microhardness values than Lava Ultimate. Furthermore, both Lava Ultimate and IPS e.max CAD microhardness values were not affected by the saliva and tooth slurry used during wear testing procedures. The values after wear were statistically not significant from baseline values.