Retention | 合法醫療器材資訊網

2000年12月23日—TheRPIsystemisdesignedtoallowverticalrotationofadistalextensionsaddleintothedenture-bearingmucosaunderocclusalloading ...

Fig. 14[1]

Only the terminal third of an occlusally-approaching clasp (stippled section) should cross the survey line and enter the undercut area. If, in error, too much of the clasp arm engages the undercut, the high force required to move it over the maximum bulbosity will put a considerable strain on the fibres of the periodontal ligament and is likely to exceed the proportional limit of the alloy, thus distorting the clasp.

Fig. 15[2]

A gingivally approaching clasp contacts the tooth surface only at its tip. The remainder of the clasp arm ...