4 Retentive force characteristics of various partial denture retainers

Abstract

We evaluated the retentive force and energy of partial denture retainers using a tensile testing machine. We tested the RPI clasp, clasps with no guide plane (NP clasps), clasps with guide planes (GP clasps), the Magmax-C 600, the Magdome C, the cone crown telescope (Konus), the Bona 604, the Bona 604 A and the Rothermann. We measured the displacement before (DBP) and after (DAP) the peak retentive force, and calculated the retentive energy before (EBP) and after (EAP) the peak. The NP clasp had a larger retentive force, DBP and EBP than did the other clasps. This suggests that preparation of a guide plane reduces the load on the abutment tooth. Magnetic attachments had characteristics effective in preserving abutment teeth because of a shorter DBP and lower retentive energy. The Konus crown also had similar retentive properties, but a shorter DAP.