Abstract
Mechanical and biological criteria have to be met in retaining the metal frame of a removable partial denture. Additionally, a removable partial denture is part of the occlusal interface by the clasps and the denture teeth. With respect to mechanical aspects, all rigid parts of the removable partial denture are of importance. However, as clasp arms tend to loose retention during long-term function, it is primarily the minor connectors and rigid clasp arms that provide stability and retention by friction with the guiding planes of the abutment teeth. With respect to biological aspects, comfort and cleansing ability are most important. Their functioning is enhanced by a low number of components crossing the marginal gingiva, such as minor connectors and infrabulge clasps. In the occlusal interface, occlusal interferences both in occlusion and during articular excursions should not be introduced by retainers or denture teeth.
