A new dental casting technique for production of void-free dental models

PURPOSE: An essential of successful dental prosthesis is dental models. Voids present in dental models decreases accuracy and strength. This study investigates void formation in models fabricated by a new technique. The technique described in the study was based upon increasing soaking time of gypsum powder in water. MATERIALS AND METHODS: Voids in hand mixed, hand mixed after a soaking time of 1.5 minutes and vacuum mixed samples were examined. The voids were counted via a stereomicroscope and diameters of voids were recorded in 2 categories (0.01-0.05mm, 0.051-0.1mm). The amounts of voids were compared between the samples prepared with 3 methods. RESULTS: The samples prepared by conventional hand mixing method had the highest total number of voids and smaller voids. There was no significant difference between the amount of voids in the samples prepared by soaking powder in water and by mixing under vacuum. CONCLUSION: Soaking gypsum powder in water for 1.5 minutes before mixing may be an alternative to mixing gypsum under vacuum to avoid void formation in dental models.