Effect of flask closure method and post-pressing time on the upper denture base adaptation.
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.
Lira
Andréa F
AF
Piracicaba Dental School - Campinas State University, Piracicaba, SP, Brazil.
Consani
Rafael L X
RL
Mesquita
Marcelo F
MF
Correr-Sobrinho
Lourenço
L
Sinhoreti
Mario A C
MA
Henriques
Guilherme E P
GE
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
D000180:Acrylic Resins; D003764:Dental Materials; C488492:QC 20 (denture base resin); D014867:Water; D019904:Polymethyl Methacrylate