title: [Effect of different time intervals on the fracture strength of die stone materials].
abstract: OBJECTIVE
  To evaluate the fracture resistance of three types die stone materials at different time intervals.
  
  
  METHODS
  Maxillary master casts were made of ploymerized methyl methacrylate resins. Three types die stone materials were used. A total of 144 casts were prepared, separated and tested on the self-made testing machine at 0.5, 1.6 and 16 hours to measure the resistance to fracture.
  
  
  RESULTS
  The data were analyzed with ANOVA at alpha = 0.05 and n = 12. Results showed that the cast fracture strength was affected by cast material and setting time obviously.
  
  
  CONCLUSIONS
  It is recommended that the cast setting time should be 6-16 hours.
authors.affiliation: Department of Prosthodontics, Beijing Hospital for Stomatology, Capital University of Medical Sciences, Beijing 100050, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Luo
mesh_terms: D001696:Biomechanical Phenomena; D003764:Dental Materials; D003779:Denture Design; D013997:Time Factors
chemical_list: D003764:Dental Materials