| Research Abstract |
Using two kinds of PFM alloys, ISHIFUKU KIK HARD II (gold alloy, for short, KIK) and SHOFU UNI METAL (nickel-choromium alloy, for short, UMT), the adhesion test pieces having 10mm diameter and 4mm thickness and equipped with screw at another side, were cast using dental precision casting. The set of two test pieces were adhered by two kinds of dental adhesives, a phosphoric ester system, PANAVIA 21EX (for short, PX21) and 4-META system Super Bond C&B (for short, SB), and thickness of adhesive layr were changed about 30,230 and 430 mum. The specimens were immersed in distillled water at 37ﾟC for 1 day or 3 days, and then were applied vertical tension load to adhension interface, and static tension bonding strength were measured. And using servo pulse controller, 50Hz altenative tensile stress were applied vertically to the adhesion interface of the specimen, and bonding fatigue strength at 10^6 cycle (10^6 bonding fatigue strength) were measured by staircase method. In respect of the th
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ickness of adhesives (factor A), the immersion time of the specimens (factor B), kind of adhesives (factor C) and kind of alloys (factor D), the measuring values obtained were analized based on four-way analysis of variance and the effects of factors were evaluated.
The result may be summerized as follows. Static tension bonding strength (sigma_t) was in the range of 39-53MPa under 24 conditions. The 10^6 bonding fatigue strength (sigma_f) decreased in the range of 18-37MPa, and sigma_f・sigma_t^<-1> (ratio of 10^6 bonding fatigue strength to static bonding tensile strength) were ranged from 0.54 to 0.67. Using SB adhesives, the average effect (average of 12 different conbinations) of sigma_t was 46MPa and sigma_f was 32MPa. Using PX21 adhesives, they were 42MPa (sigma_t), and 24MPa (sigma_f), respectively. sigma_f and sigma_t of PX21 were smaller than SB's in both. When the immersion time of the specimens increased to 7days from 1day, sigma_t and sigma_f of SB increased, but using PX21, sigma_t increased slightly and sigma_f decreased conversly. In respect of the main effect of KIK and UMT alloys, sigma_t, was statistically highly significant, and they were 46MPa using UMT and 37MPa using KIK,respectively. Less
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