title: Dimensional accuracy of upper complete denture bases: the effect of metallic flask closure methods.
abstract: OBJECTIVE
  To verify the dimensional accuracy of upper complete denture bases under the effect of different methods of metallic flask closure.
  
  
  METHODS
  Wax record bases were assigned to six groups: 1-2: traditional clamp; 3-4: RS system; and 5-6: flask with screws. Flasks were immediately polymerised or bench stored for 6 h prior to polymerisation. Resin base-cast sets were sectioned at regions corresponding to the canines, first molars and posterior palatal zone. Gap discrepancies were measured at five points: right and left ridge crests, palatal midline, and right and left marginal limits of the flanges. An optical micrometer was used for measurement purposes.
  
  
  RESULTS
  Data were submitted to anova, and the means compared by Tukey's test (alpha = 0.05). Results revealed significant differences in the flask closure technique, polymerisation time, section, and their interactions. Discrepancy values for the RS system and flask with screws were significantly lower than those related to the traditional clamp, regardless of whether resin polymerisation was immediate or delayed for 6 h.
  
  
  CONCLUSIONS
  Flask closure methods should be considered when the denture base stability and comfort of the patient are being assessed during clinical use of the dentures.
authors.affiliation: Department of Prosthodontics and Periodontics, Piracicaba Dental School, State University of Campinas, Sao Paulo, Brazil. rconsani@fop.unicamp.br
authors.forename: Rafael Leonardo Xediek
authors.initials: RL
authors.lastname: Consani
authors.forename: Marcelo Ferraz
authors.initials: MF
authors.lastname: Mesquita
authors.forename: Lourenço Correr
authors.initials: LC
authors.lastname: Sobrinho
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D003481:Cuspid; D003735:Dental Casting Technique / Q000295:instrumentation*; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases / Q000592:standards*; D003781:Denture Retention; D003827:Denture, Complete, Upper / Q000592:standards*; D006801:Humans; D008422:Materials Testing; D008963:Molar; D010159:Palate; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011312:Pressure; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water; D014885:Waxes / Q000737:chemistry
chemical_list: D003764:Dental Materials; D011108:Polymers; D014885:Waxes; D014867:Water; D019904:Polymethyl Methacrylate