Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures

Abstract

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.

Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding

“…3). This is because the density of E-glass fiber (2.6 g/cm 3 ) is greater than that of polyamide-6 (1.13 g/cm 3 ). As expected, the experimental density of GFRTPs with varying fiber content agreed with the theoretical density obtained from the density of glass fiber and polyamide.…”

“…Polyamide-12 is proposed as a denture base material in dentistry because of its high impact strength, toughness, and resistance to fracture. However, the flexural strength, elastic modulus and rigidity are inferior to other NMCD materials such as polyester and polycarbonate 3,13) . In contrast, polyamide-6 is a particularly attractive class of polymer because of its competitive price, excellent strength and rigidity, low friction coefficient, and high dimensional stability and chemical and wear resistance, making it mostly used type of polyamide worldwide 18) .…”

“…GF-0, GF-5, GF-10, GF-20, GF-30, GF-40, and GF-50 recorded densities of 1.12±0.01, 1.18±0.05, 1.20±0.06, 1.25±0.01, 1.42±0.06, 1.52±0.04, and 1.58±0.03 g/cm 3 , respectively; the apparent density increased with increasing fiber content. GF-0, GF-5, GF-10, GF-20, GF-30, GF-40, and GF-50 had theoretical densities of 1.13, 1.16, 1.20, 1.27, 1.36, 1.46, and 1.58 g/cm 3 , respectively. The measured density, obtained based on Archimedes' principle, mostly agreed with the theoretical density obtained using the rule of mixtures.…”

“…where V f is the fiber volume content, Wf is the fiber weight content, ρf is the E-glass fiber density (2.6 g/cm 3 ), and ρm is the polyamide-6 matrix density (1.13 g/cm 3 ).…”

“…Removable partial dentures (RPDs) using resin-clasp retentive parts are defined as non-metal clasp dentures (NMCDs), and are often much more esthetically pleasing than conventional RPDs with metal clasps 2) . Generally, thermoplastic resins such as polyamide, polyester and polycarbonate have been used as NMCDs that can be injection-molded in one piece including clasps, minor and major connectors, and denture bases [2][3][4] . Several types of polyamides are most commonly used, having the longest history among the thermoplastic resins used for NMCDs 2) .…”