The efficiency of an indirect retainer

Abstract

1 wo reports of recent prosthodontic research have dealt specifically with indirect retainers, but only in a general way. I, 2 Several other articles have mentioned indirect retainers as they relate to the design of an entire prosthesis”-“’ or their relative effect on abutment tooth movement.“-‘* Most reports4-1f1 that mention indirect retainers cite one or more of the following general principles: ( 1) They are needed in extension-base removable partial dentures; (2) they should be located as far from the primary fulcrum line as possible; (3) they should be placed on a positive rest seat, especially if on an anterior tooth; (4) they help in resisting rotational movement of the denture base away from the ridge and lateral movement of the restoration; and (5) they can take the form of an auxiliary occlusal rest, cingulum rest, embrasure hook, secondary Kennedy bar, or linguoplate. Few, if any, of the reported functions of indirect retainers have been studied, nor has their efficiency-particularly as it relates to resting on anterior teeth. The purpose of this study was twofold : ( 1) t o investigate the efficiency of indirect retainer design as it relates to anterior teeth and (2) to determine if the type of direct retainer design has any effect on the efficiency of indirect retainers.