The objective of this study was to investigate the effects of eccentric cyclic loading on implant components using the internal joint system with titanium and zirconia abutments. Abutments were made of either pure titanium (Ti group) or zirconia (TZP group). Cyclic loading test was conducted according to the specifications of ISO 14801. Loading condition was at 2 points assuming axial load and eccentric load. The reverse torque value reduced after the eccentric load and reduced more in the TZP group than the Ti group. Marginal gap changed after eccentric loading, and was greater in the TZP group. In the TZP group, changes in configuration were observed in the implant body, and Ti was detected on the abutment surface. From the above, the eccentric load may have worse effects than axial loads. It was suggested that the TZP group was clinically disadvantageous compared to the Ti group.

The objective of this study was to clarify the fatigue behavior of hollow yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) specimens assuming its use for two-piece implants. The fatigue properties of a solid specimen (which simulated a one-piece implant) and 3 types of hollow specimens (which simulated two-piece implants) were evaluated. Specimens were either solid with a diameter of 4.0 mm (S) or hollow with an inner diameter of 3.0 mm and outer diameters of 4.0 mm (H0.5), 4.5 mm (H0.75), or 5.0 mm (H1.0). For each group, 25 specimens were prepared followed by blast and acid etch treatment. Static fracture and cyclic fatigue tests were conducted by modifying the methods provided in ISO6872. Fracture modes were determined by observing the surfaces under a scanning electron microscope. As a result, the cyclic fatigue load of S and H1.0 were similar, and hollow specimens with outer diameters greater than 0.75 mm displayed the ability to withstand molar occlusal forces.

Tungsten oxide/bismuth oxide composite thinˆlms prepared by multi target radio frequency (RF) reactive sputtering were investigated. X ray diŠraction measurements of the crystallinity of thinˆlms prepared at room temperature revealed amorphous structure. Although the compositional ratio of composite thinˆlms prepared at 50 W and 75 W of the RF power of the Bi target was almost the same, those prepared at 50 W were transparent, and had a much smaller optical absorption coe‹cient at 3.0 eV than those prepared at 75 W. Bi 4f spectra of these thinˆlms were measured by X ray photoelectron spectroscopy, and were analyzed by full width at half maximum of Bi 4f 7/2 peaks. As a result, the transparency is thought to be caused by the change of bonding state of Bi O. Electrochromic properties of the composite thinˆlms were also measured in 0.1 M H 2 SO 4 . Coloration of composite thinˆlms prepared at 20 W of the RF power of the Bi target changed reversibly from transparent to black and brown.