Clinical application of removable partial dentures using thermoplastic resin (non-metal clasp dentures)

Abstract

This position paper proposes a definition and naming standard for removable partial dentures (RPDs) using thermoplastic resin, and presents a guideline for clinical application. A panel of 14 experts having broad experience with clinical application of RPDs using thermoplastic resin was selected from members of the Japan Prosthodontic Society. At a meeting of the panel, “non-metal clasp denture” was defined as the generic name of RPDs with retentive elements (resin clasps) made of thermoplastic resin. The panel classified non-metal clasp dentures into two types: one with a flexible structure that lacks a metal framework and the other having a rigid structure that includes a metal framework. According to current prosthetic principles, flexible non-metal clasp dentures are not recommended as definitive dentures, except for limited cases such as patients with a metal allergy. Rigid non-metal clasp dentures are recommended in cases where patients will not accept metal clasps for esthetic reasons. Non-metal clasp dentures should follow the same design principles as conventional RPDs using metal clasps. Since the physical properties of thermoplastic-resin products vary greatly, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk of fracture than polymethylmethacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethylmethacrylate. Studies on the physical properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to reach a definitive conclusion at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be developed.