title: Fracture resistance of maxillary complete dentures subjected to long-term water immersion.
abstract: OBJECTIVE
  This study investigated the fracture resistance of maxillary acrylic resin complete dentures subjected to long-term water immersion.
  
  
  METHODS
  Maxillary acrylic resin complete dentures were fabricated from five denture base resins. Half of the dentures were stored in water for 50 h, and the other half were kept in water for 180 days before testing. Ten specimens were fabricated per group. The flexural load at the proportional limit (FL-PL) of the dentures was tested.
  
  
  RESULTS
  A two-way anova revealed a significant difference in FL-PL because of the denture base material variable. There were no significant differences in FL-PL because of the effect of water immersion and the interaction between the effect of water immersion and the denture base material. The FL-PLs of the dentures fabricated with the two conventional heat-processed resins, the pour-type autopolymerizing resin and the microwave energy-processed resin were not significantly different from each other; they were significantly higher than the light-activated resin in regard to their FL-PL.
  
  
  CONCLUSIONS
  The FL-PLs of the maxillary acrylic resin complete dentures did not change after long-tern water immersion, and the FL-PL of the denture fabricated from the light-activated resin was lower than those of the other materials.
authors.affiliation: Division of Removable Prosthodontics, Fukuoka Dental College, Fukuoka, Japan. ytakaha@college.fdcnet.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kaneyoshi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003819:Denture Bases; D003827:Denture, Complete, Upper; D006358:Hot Temperature; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D020366:Methylmethacrylate / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D008872:Microwaves; D055668:Photochemical Processes; D018583:Pliability; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D008689:Methacrylates; D008768:Methylmethacrylates; C507521:Palapress Vario; D011140:Polyurethanes; D014867:Water; C060386:Triad resin; C075051:Acron MC; C029824:urethane dimethacrylate luting resin; D020366:Methylmethacrylate; C040291:Lucitone; C009931:poly(ethylmethacrylate); D019904:Polymethyl Methacrylate