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 referred 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.

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, 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 for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.

No abstract

No abstract

Pure titanium cast plate denture produced by Ohara's titanium casting system were inserted in eight patients. The pure titanium cast plate dentures enabled satisfactory fitness and had good adaptability to the mucosal surface. Furthermore, they are lighter in weight than conventional cast dentures. X-ray examination revealed some casting defects, but these defects were not serious enough to be conducive to damages. Follow-up observation of the patients with these dentures indicated no clinical problems. However, inadequate adhesiveness with resin was a technical problem encountered. Examination of the castability of pure titanium using this system showed that casting in the meshtype wax pattern failed to produce a complete form of mesh, while casting in the plate-type wax patterns produced a complete contour of the plates. X-ray examination of the plate cast, however, revealed some casting defects.