title: Mechanical properties of injection-molded thermoplastic denture base resins.
abstract: OBJECTIVE
  To investigate the mechanical properties of injection-molded thermoplastic denture base resins.
  
  
  METHODS
  Four injection-molded thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were used in this study. The flexural strength at the proportional limit (FS-PL), the elastic modulus, and the Charpy impact strength of the denture base resins were measured according to International Organization for Standardization (ISO) 1567 and ISO 1567:1999/Amd 1:2003.
  
  
  RESULTS
  The descending order of the FS-PL was: conventional PMMA > polyethylene terephthalate, polycarbonate > two polyamides. The descending order of the elastic moduli was: conventional PMMA > polycarbonate > polyethylene terephthalate > two polyamides. The descending order of the Charpy impact strength was: polyamide (Nylon PACM12) > polycarbonate > polyamide (Nylon 12), polyethylene terephthalate > conventional PMMA.
  
  
  CONCLUSIONS
  All of the injection-molded thermoplastic resins had significantly lower FS-PL, lower elastic moduli, and higher or similar impact strength compared to the conventional PMMA. The polyamide denture base resins had low FS-PL and low elastic moduli; one of them possessed very high impact strength, and the other had low impact strength. The polyethylene terephthalate denture base resin showed a moderately high FS-PL, moderate elastic modulus, and low impact strength. The polycarbonate denture base resin had a moderately high FS-PL, moderately high elastic modulus, and moderate impact strength.
authors.affiliation: Division of Removable Prosthodontics, Fukuoka Dental College, Fukuoka, Japan.
authors.forename: Ippei
authors.initials: I
authors.lastname: Hamanaka
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D007267:Injections; D008422:Materials Testing; D055595:Mechanical Phenomena; D009757:Nylons / Q000737:chemistry; D018583:Pliability; D011076:Polycarboxylate Cement / Q000737:chemistry; D011093:Polyethylene Terephthalates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry*; D013450:Sulfones / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D009757:Nylons; D011076:Polycarboxylate Cement; D011093:Polyethylene Terephthalates; D011108:Polymers; D012117:Resins, Synthetic; D013450:Sulfones; C005506:polycarbonate; C040291:Lucitone; C045672:Reigning resin; D019904:Polymethyl Methacrylate