Proximal plate in conventional circumferential cast clasp retention☆

Abstract 

Improper guiding planes are commonly used with conventional removable partial denture cast clasps. Short guiding planes with improper proximal plates decrease retention and cause repetitive traumatic movement of abutments. This article discusses the importance of guiding planes and proximal plates for conventional tooth-supported removable partial dentures with circumferential clasp. The retention force of the clasps was analyzed geometrically. If the guiding plane is short or the prepared surface is oblique, the contact between the proximal plate and the guiding plane or oblique plane diminishes at an early stage, which results in reduction of retention. The guiding plane should be parallel to the path of insertion and must be of a certain length for adequate retention. An elongated proximal plate that is parallel to the path of insertion may compensate for retention deficiency when an adequate guiding plane cannot be prepared. (J Prosthet Dent 2000;83:319-22.)