title: Effect of long-term water immersion on the fracture toughness of denture base and reline resins.
abstract: OBJECTIVE
  This study evaluated the fracture toughness (FT) of one denture base (Lucitone 550 - L) and four hard reline resins [Ufi Gel Hard (UH), Tokuyama Rebase II (TR), New Truliner (NT) and Kooliner (K)], and the effect of long-term water storage on this property.
  
  
  METHODS
  Forty specimens (40 × 8 × 4 mm) of each material were made, and FT was assessed after polymerisation (control of reliners), after 48 ± 2 h in water at 37°C (control of denture base resin) and after storage in water at 37°C for 7, 90 or 180 days (all materials). Data (MPa.m(1/2) ) were analysed by two-way anova and Games-Howell test (p = 0.05).
  
  
  RESULTS
  Resin L exhibited the highest FT mean values. After 180 days of storage, FT mean values of L (3.37), UH (1.53) and K (1.20) were higher than those of the other periods. FT mean values of NT decreased from control (1.63) to 7 days (1.30) and then remained constant. FT mean values of TR (1.13) were similar in all periods of analysis.
  
  
  CONCLUSIONS
  The denture base resin L showed higher FT mean values than the reline resins. Long-term water storage increased the FT of L, UH and K, reduced the FT of NT and did not influence the FT of TR.
authors: Department of Dental Materials and Prosthodontics, Araraquara Dental School, Unesp, University Estadual Paulista, Araraquara, SP, Brazil.
authors: Lívia Sertori
authors: LS
authors: Finoti
authors: Ana Lucia
authors: AL
authors: Machado
authors: Carolina De Andrade Lima
authors: CA
authors: Chaves
authors: Ana Cláudia
authors: AC
authors: Pavarina
authors: Carlos Eduardo
authors: CE
authors: Vergani
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D003822:Denture Liners; D003823:Denture Rebasing; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D058105:Polymerization; D012826:Silicone Elastomers / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D008689:Methacrylates; D012826:Silicone Elastomers; C483158:Ufi gel; C514244:tokuyama rebase fast II; D014867:Water; C103363:kooliner; C071514:truliner; C040291:Lucitone