OBJECTIVETo investigate the elastic limit and relevant enclasp force of the non-precious metal casting clasp.

METHODSCasting clasp samples of five cobalt-chromium alloys and one 18 - 8 nickel-chromium alloy were made from prefabricated clasp wax by invesing, casting, sandblasting, and ultrasonic cleaning. The process of casting clasp samples deflected by loading and returned by unloading was tested and electric signals were collected by an omnipotent material machine. The analog electric signal was converted to digital signal by an analog to digital converter and stored in a computer. The elastic limit and the relevant enclasp force were analyzed using a relative software.

RESULTSThe elastic limit and the relevant enclasp force of the casting clasp made from the 18 - 8 nickel-chromium alloy were smallest and those of the clasps made from the cobalt-chromium alloys in various brands were different. The range of the elastic limit of the cobalt-chromium alloy casting clasp with the length of 5.0 mm in undercut was 0.28 mm-0.33 mm and the relevant enclasp force was 14.42 g-19.28 g.

CONCLUSIONSIn clinic, we should select the suitable undercut deepness wherein the cobalt-chromium alloy casting clasps, according to different brands of the casting alloy, undercut length, undercut slope, and the clasp thickness.