Flexural Properties of Different Commercial Thermoplastic Resins for “Non-clasp Dentures”

Abstract

Purpose: To characterize the flexural properties of various commercial thermoplastic resins for non-clasp dentures.
Methods: Four different commercial thermoplastic resins for non-clasp dentures (polyamide resin: Lucitone FRS, polycarbonate resin: Reining, polyester resin: EstheShot, and acrylic resin: Acrytone) and thermally polymerized acrylic resin (Acron) as a control were used in this study. A three-point bending test of two types of test piece: one in the state as molded (drying type) and the other in the state as soaked in water for 30 days after molding (soaking type) was performed for plotting the stress-strain curve and calculating the flexural strength, flexural modulus, and 0.05% proof stress. Comparisons between the drying and soaking types in each resin as well as between different resins were performed based on the obtained data.
Results: The stress-strain curve revealed the brittleness of Acron as a control and the toughness of all thermoplastic resins for non-clasp dentures. The flexural strength of all but Reining was significantly lower than that of Acron. The flexural modulus of all of them was significantly lower than that of Acron. The 0.05% proof stress of EstheShot was significantly higher than that of the others. The flexural strength, flexural modulus, and 0.05% proof stress of Acrytone were significantly lower in the soaking type than in the drying type.
Conclusions: These results suggested that the flexural property of each material was dependent on the property of the resin to be used. Sufficient considerations are required with an understanding of the basic physical properties of the thermoplastic material to be used when selecting and designing non-clasp dentures.