title: Polytetrafluorethylene added to acrylic resins: mechanical properties.
abstract: The addition of different polymers, such as polytetrafluorethylene (PTFE), to denture base resins could be an option to modify acrylic resin mechanical properties. This study evaluated the surface hardness, impact and flexural strength, flexural modulus and peak load of 2 acrylic resins, one subjected to a long and another subjected to a short polymerization cycle, which were prepared with or without the addition of 2% PTFE. Four groups were formed according to the polymerization cycle and addition or not of PTFE. Forty specimens were prepared for each test (10 per group) with the following dimensions: hardness (30 mm diameter x 5 mm thick), impact strength (50 x 6 x 4 mm) and flexural strength (64 x 10 x 3.3 mm) test. The results of the flexural strength test allowed calculating flexural modulus and peak of load values. All tests were performed in accordance with the ISO 1567:1999 standard. Data were analyzed statistically by ANOVA and Tukey's test with the level of significance set at 5%. No statistically significant differences (p>0.05) were found for surface hardness. Flexural strength, impact strength and peak load were significantly higher (p<0.05) for resins without added PTFE. The flexural modulus of the acrylic resin with incorporated 2% PTFE polymerized by long cycle was significantly higher (p<0.05) than that of the other resins. Within the limits of this study, it may be concluded that the addition of PTFE did not improve the mechanical properties of the evaluated acrylic resins.
authors.affiliation: Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Fabiana Gouveia
authors.initials: FG
authors.lastname: Straioto
authors.forename: Antonio Pedro
authors.initials: AP
authors.lastname: Ricomini Filho
authors.forename: Alfredo Júlio
authors.initials: AJ
authors.lastname: Fernandes Neto
authors.forename: Altair Antoninha
authors.initials: AA
authors.lastname: Del Bel Cury
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D055119:Elastic Modulus; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D018583:Pliability; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D011108:Polymers; D011138:Polytetrafluoroethylene; D019904:Polymethyl Methacrylate