title: Effect of flask closure method and post-pressing time on the upper denture base adaptation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of flask-closure methods, post-pressing times and acrylic resins on denture base adaptation.
  
  
  METHODS
  The resins were flasked using a hydraulic press and closed with the traditional clamp or RS system. Conventional heat-cure resin was polymerised immediately or at 6 h post-pressing at 74 degrees C for 9 h. Rapid cycle heat-cure resin was polymerised in boiling water for 20 min. After cooling, the bases were deflasked and the sets of cast-base transversally sectioned in the regions distal to the canine, mesial to the first molar and in the posterior palatal zone. The adaptation was measured with an optical microscope (0.0005 mm) at five reference points for each section. Data were analysed using anova and Tukey's test (alpha = 0.05).
  
  
  RESULTS
  Traditional clamp and immediate post-pressing time improved base adaptation for conventional heat-cure resin. Both post-pressing times showed most accurate base adaptation for conventional heat-cure resin when the traditional clamp was used. Immediate post-pressing time improved base adaptation for conventional heat-cure resin and the 6-h delay in time was significant for the rapid cycle heat-cure resin.
  
  
  CONCLUSIONS
  Traditional clamp and immediate post-pressing time improved base adaptation for conventional heat-cure resin.
authors: Piracicaba Dental School - Campinas State University, Piracicaba, SP, Brazil.
authors: Andréa F
authors: AF
authors: Lira
authors: Rafael L X
authors: RL
authors: Consani
authors: Marcelo F
authors: MF
authors: Mesquita
authors: Lourenço
authors: L
authors: Correr-Sobrinho
authors: Mario A C
authors: MA
authors: Sinhoreti
authors: Guilherme E P
authors: GE
authors: Henriques
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003481:Cuspid; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D003779:Denture Design / Q000295:instrumentation* / Q000379:methods; D003827:Denture, Complete, Upper; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008963:Molar; D010159:Palate; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011312:Pressure; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; C488492:QC 20 (denture base resin); D014867:Water; D019904:Polymethyl Methacrylate