Marginal fit analysis of CAD/CAM fabricated crown frameworks depending on the used materials

The aim of this study was to compare the marginal fits of crown frameworks of different materials when they were manufactured with the same CAD/CAM system and the same interior design (= identical process chain). The marginal gaps of titanium frameworks, cobalt chrome frameworks, zirconia frameworks and lithium disilicate frameworks were determined. The marginal fit of the specimens was measured on 24 points, marked on the master metal die, by using a digital microscope with 35x magnification. Titanium had with 46.92 µm a significantly smaller mean marginal gap than lithium disilicate (58.73 µm) and zirconium dioxide (68.25 µm). Another significant difference was found between the average fits of cobalt chrome (48.37 µm) and zirconium dioxide (68.25 µm). The average maximum values of titanium (91.53 µm), cobalt chrome (96.86 µm), lithium disilicate (100.22 µm) and zirconia (120.66 µm) had no significant differences. The averages of all marginal gaps were within the postulated clinical tolerance of 120 µm and the maximum values exceeded the tolerance limit in one case only slightly. Therefore all materials in this study appeared suitable for clinical use.2015-07-0