IMPROVEMENT OF BONDING DURABILITY OF DENTAL NOBLE METAL ALLOYS

通过体外剪切试验评价了合金成分、底漆和热循环对银钯铜金合金粘结强度的影响。两种不同直径的圆盘试样由三种市售的（S12、S20和Castwell M.C.12）和四种实验性银-钯-铜-金合金（K1、K2、K3和K4）铸造而成，后者中的每一种含有超过20%的铜。样本未涂底漆或用金属调节剂（V-Primer）涂底漆，用粘合剂树脂（Super-Bond Opaque）粘合，然后进行剪切测试。结果表明，低铜的S12和S20合金显示出比Castwell合金更低的热循环后结合强度，无论是否应用调节剂。涂底漆的K1、K2、K3和K4合金的热循环后结合强度与Castwell合金的相同。对于除一组（S12，无热循环）外的所有组，通过使用金属表面调节剂提高了粘合强度。应用热应力显着降低未涂底漆组的粘结强度，而两个涂底漆组（K1和K2）的粘结强度不受热循环。理想的是使用20%铜的银-钯-铜-金合金，以实现与V-Primer调理剂和Super-Bond粘合剂的组合的持久粘合。

The influence of alloy composition, priming, and thermocycling on bond strength to silver-palladium-copper-gold alloy was evaluated in vitro by means of shear testing. Disk specimens with two different diameters were cast from three commercially available (S12, S20, and Castwell M.C.12) and four experimental silver-palladium-copper-gold alloys (K1, K2, K3, and K4), each of the latter containing copper more than 20%. Specimens were either unprimed or primed with a metal conditioner (V-Primer), bonded with an adhesive resin (Super-Bond Opaque), then shear testing was performed. The results showed that the low-copper S12 and S20 alloys showed lower post-thermocycling bond strength than the Castwell alloy regardless application of the conditioning agent. Post-thermocycling bond strengths of the primed K1, K2, K3 and K4 alloys were the same magnitude as that of the Castwell alloy. For all groups except for one (S12, without thermocycling), bond strength was elevated by use of the metal surface conditioner. Application of thermal stress drastically reduced bond strength of unprimed groups, whereas bond strength of the two primed groups (K1 and K2) was unaffected by thermocycling. It is desirable to use a 20%-copper silver-palladium-copper-gold alloy for achieving durable bonding with the combination of the V-Primer conditioner and the Super-Bond adhesive.