ABSTRACT
Objective To design a novel device with dynamic occlusal loads so as to investigate the influence of occlusal force on Ni release from Ni-Cr PFM alloys. Methods Based on the average force(45 N) and rate(80 cycles/min) of human mastication, a novel device with dynamic occlusal loads was designed to study the Ni release from three commonly used Ni-Cr PFM alloys (Shangchi, Stellite, BEGO) in the artificial saliva with pH 2.3 and pH 7.4, respectively. Results This novel device with dynamic occlusal loads worked well to simulate the average force and chewing cyclye. In the artificial saliva with pH 2.3, the amount of Ni release in Shangchi, Stellite and BEGO was 6.9(2.07) μg/cm2, 3.7(0.662) μg/cm2 and 5.88(1.57) μg/cm2, respectively; while in the artificial saliva with pH 7.0, the amount of Ni release in Shangchi, Stellite and BEGO was 0.272(0.059) μg/cm2, 0.144(0.014) μg/cm2 and 0.435(0.053) μg/cm2, respectively. For the same Ni-Cr PMF alloys, the amount of Ni release in the artificial saliva with pH 2.3 was much higher than that with pH 7.0 (P<0.01), showing statistical differences. Conclusions The device with dynamic occlusal loads could be used effectively to evaluate the influence of occlusal force on Ni release from Ni-Cr PFM alloys in vitro. The acid environment could obviously accelerate the Ni release from Ni-Cr PFM alloys. This study showed the amount of Ni release in Stellite was relatively lower than that in the other two alloys.