Mechanical Properties of Polyamide Versus Different PMMA Denture Base Materials

Purpose: Polymethyl methacrylate (PMMA) resins are the most commonly used denture materials; however, they do not have a high flexural strength (FS). This study aimed to compare the mechanical properties of a polyamide-based, injection-molded denture material (Deflex) with another injection-molded PMMA base material (SR-Ivocap) and a conventional compression-molded PMMA (Meliodent). Materials and Methods: Flexural properties (deflection, bending strength, and bending modulus) of denture base materials were evaluated (n = 10). Specimens meeting International Standards Organization (ISO) specification number 20795-1 requirements were prepared (65 x 10 x 3 mm3). A three-point bending test was carried out on an Instron testing machine at a 5 mm/min crosshead speed. The Knoop hardness test was used to compare microhardness values. Data were analyzed using ANOVA, followed by REGWQ. Results: The group results, standard deviations, and statistical differences (p < 0.01) for Deflex, SR-Ivocap, and Meliodent were (A) flexural strength (MPa: 78.3 +/- 1.0,(a) 69.8 +/- 1.4,(b) 81.1 +/- 1(a)), (B) flexural modulus (GPa: 0.70 +/- 0.13,(a) 0.85 +/- 0.27,(a) 1.70 +/- 0.23(b)), (C) Knoop Hardness (kg/cm(2): 7.5 +/- 1.0,(a) 13.5 +/- 1.4, b 16.9 +/- 1.0(c)). Different superscript letters indicate significant difference. All Meliodent specimens fractured during flexural testing, but no Deflex specimens did. Conclusions: While polyamide denturematerial produced good fracture resistance, its modulus is not yet sufficiently high to be equal to standard PMMA materials. Clinical Implications. Polyamide has some attractive advantages, but will require modification to produce consistently better properties than current PMMA materials.