IADR Abstract Archives
Flexural Mechanical Properties of Some Thermoplastic Resins for Flexible Denture
Objectives: Thermoplastic resins are widely used to fabricate flexible denture with non-metal clasp. The purpose of this study was to investigate the fleuxral mechanical properties of flexible denture materials, including ultimate flexural strength (FS), flexural modulus (FM),proportional limit (PL) and resilence (RS, area of elastic portion of stress-strain curve).
Methods: A total of six flexible denture materials are used in the experiment; three polyamides Flexident Regular (FR), Flexstar-V (FV), Valplast (VP), Rezen NF (RN), two acrylics Flexident AC (FA), Acrytone (AT). Six flexural specimens from each group were fabricated by injection molding methods under the respective manufacturer’s recommendation. A conventional heat-curing acryic resin (Vertex) specimens was prcessed as control. Both lengthwise surfaces were subjected to parallel machining using carborundum wheel to prepare them with dimensions of 10 x 3.3 x 65 mm. Specimen beams were finished by wet grinding using SiC paper (P1200) and then stored in distilled water at 37°C for 48 h before test. Flexural properties of specimens were measured by using a universal testing machine (Instron) at a loading speed of 5 mm/min in the water bath of 37°C according to international standards (ISO 20795-1, type 3). FS, FM, PL, and RS values were obtained from strain-stress curve using Bluehill 2 (Instron) program. FS values of thermoplastics were corrected accroding to ASTM D790. Data were analyzed ANOVA and post hoc test at P<0.05.
Results: Mean (FS, FM in MPa) values of flexible materials were as follows; FR (34, 612), FV (33, 611), VP (37, 694), RN (51, 1367), FA (49, 1416), AT (44, 1416), and control (78, 2538). Mean (PL in MPa, RS in mMN/m3) of specimens; FR (12, 0.11), FV (10, 0.09), VP (13, 0.11), RN (21, 0.16), FA (21, 0.16), AT (33, 0.39), and control (35, 0.25). The flexural strength and modulus of polyamide-based flexible denture (FR, FV, VP, RN) were significantly lower than that of heat-curing resin and even than PMMA-based materials (FA, AT). AT showed a significantly higher flexural resilience.
Conclusions: Thermoplastic acrylic resins (FA, AT) showed a higher flexural mechanical properties than polyamide resins, but FS and FM values of all thermplastic resins were less than the minimum requirement of ISO 20795 type 3 (65, 2000).
Methods: A total of six flexible denture materials are used in the experiment; three polyamides Flexident Regular (FR), Flexstar-V (FV), Valplast (VP), Rezen NF (RN), two acrylics Flexident AC (FA), Acrytone (AT). Six flexural specimens from each group were fabricated by injection molding methods under the respective manufacturer’s recommendation. A conventional heat-curing acryic resin (Vertex) specimens was prcessed as control. Both lengthwise surfaces were subjected to parallel machining using carborundum wheel to prepare them with dimensions of 10 x 3.3 x 65 mm. Specimen beams were finished by wet grinding using SiC paper (P1200) and then stored in distilled water at 37°C for 48 h before test. Flexural properties of specimens were measured by using a universal testing machine (Instron) at a loading speed of 5 mm/min in the water bath of 37°C according to international standards (ISO 20795-1, type 3). FS, FM, PL, and RS values were obtained from strain-stress curve using Bluehill 2 (Instron) program. FS values of thermoplastics were corrected accroding to ASTM D790. Data were analyzed ANOVA and post hoc test at P<0.05.
Results: Mean (FS, FM in MPa) values of flexible materials were as follows; FR (34, 612), FV (33, 611), VP (37, 694), RN (51, 1367), FA (49, 1416), AT (44, 1416), and control (78, 2538). Mean (PL in MPa, RS in mMN/m3) of specimens; FR (12, 0.11), FV (10, 0.09), VP (13, 0.11), RN (21, 0.16), FA (21, 0.16), AT (33, 0.39), and control (35, 0.25). The flexural strength and modulus of polyamide-based flexible denture (FR, FV, VP, RN) were significantly lower than that of heat-curing resin and even than PMMA-based materials (FA, AT). AT showed a significantly higher flexural resilience.
Conclusions: Thermoplastic acrylic resins (FA, AT) showed a higher flexural mechanical properties than polyamide resins, but FS and FM values of all thermplastic resins were less than the minimum requirement of ISO 20795 type 3 (65, 2000).