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.
Conclusion: It is recommended that the cast setting time should be 6-16 hours.