Use of a cast flexible plate as a hinge substitute in a hinge-lock design removable partial denture framework

Purpose. The use of a hinge for a removable partial denture with an opening labial bow was replaced by the design and construction of a flexible plate incorporated as part of a cobalt-chromium casting. Methods. Three similar prostheses were constructed and tested in vitro on an endurance test machine. Each test piece completed 12,000 opening and closing operations without fracture, which a previous study showed is a probable life cycle of a typical removable partial denture with a hinged section. Results. This plate provided sufficient flexibility to allow functional operation of the removable partial denture by a patient.