title: Water Sorption and Flexural Strength of Thermoplastic and Conventional Heat-Polymerized Acrylic Resins.
abstract: OBJECTIVE
  The aim of this study was to assess and compare the water sorption and flexural strength of thermoplastic and conventional acrylic resins.
  
  
  METHODS
  Water sorption and flexural strength were compared between a thermoplastic modified polymethyl methacrylate (PMMA) denture base resin (group A) and a heat-polymerized PMMA acrylic resin (group B) as the control group (n=10). A three-point bending test was carried out for flexural strength testing. For water sorption test, 10 disc-shaped samples were prepared. After desiccating, the samples were weighed and immersed in distilled water for seven days. Then, they were weighed again, and desiccated for the second and third times. Differences between the mean values in the two groups were analyzed using Student's t-test.
  
  
  RESULTS
  The mean value of water sorption was 14.74±1.36 μg/mm(3) in group A, and 19.11±0.90 μg/mm(3) in group B; this difference was statistically significant (P< 0.001). The mean value of flexural strength was 88.21±8.63 MPa in group A and 77.77±9.49 MPa in group B. A significant difference was observed between the two groups (P= 0.019).
  
  
  CONCLUSIONS
  Flexural strength of group A was significantly higher than that of group B, and its water sorption was significantly lower. Thus, thermoplastic resins can be a suitable alternative to conventional PMMA acrylic resins as denture base materials.
authors.affiliation: Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Shahed University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Hemmati
authors.affiliation: Assistant Professor, Dental Research Center, Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Fariborz
authors.initials: F
authors.lastname: Vafaee
authors.affiliation: Resident of Prosthodontics, Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Hanif
authors.initials: H
authors.lastname: Allahbakhshi
keywords: Absorption; Strength, Acrylic resins, denture bases, Polymethyl methacrylate; Water