الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 183 |  |  |
| | | from | 183 | | |
Abstract
Objectives: To evaluate micro tensile bond strength before and after thermal cycling as well as surface topography before and after hydrofluoric acid etching of eight types of lithium disilicate glass ceramics and zirconia reinforced lithium silicate glass ceramics. Materials and Methods: 2 blocks with 10*10*4 mm dimensions were manufactured from the CAD/CAM glass ceramics (IPS Emax CAD, GC liSi CAD, Amber Mill, Cerec Tessera) and the pressable glass ceramics (IPS Emax Press, GC liSi Press, Amber Press master, Celtra Press) to be used to evaluate micro tensile bond strength to composite blocks with the same dimensions before and after 5000 cycles of thermal cycling. 5 blocks of the same materials with 10*10*3 mm dimensions were used to evaluate surface topography before and after hydrofluoric acid etching using contact profilometer and scanning electron microscope. One-way Anova test with Post Hoc Tukey tests and Repeated Measures ANOVA test were used for the statistical analyses (α = 0.05).Results: Lithium disilicate ceramic materials showed a significant differences (P˂0.001) on the mean micro tensile bond strength before and after thermal cycling except for IPS e.max Press .The tested ceramics also showed a significant differences (P˂0.001) in mean values of Ra and Rz roughness parameters before and after hydrofluoric acid etching .IPS e.max press material showed the highest mean micro tensile bond strength after thermal cycling (16.81 ± 2.79 MPa) as well as the highest mean Roughness parameter Ra after hydrofluoric acid etching (Ra 0.438 ± 0.084 μm). Amber Mill showed the lowest mean micro tensile bondXI strength value after thermal cycling (3.47 ± 0.72 MPa). GC intial LiSi press showed the lowest mean values of roughness parameters Ra (0.104 ± 0.005 μm) and Rz (0.825 ± 0.014 μm) after hydrofluoric acid etching. Conclusions: 1. Lithium disilicate glass ceramics produced using pressing technique have more resistance to thermal cycling than those produced using CAD/CAM processing technique. 2. Different lithium dislicate glass ceramic processing techniques and microstructure resulted in different patterns in response to hydrofluoric acid etching.