effect of stone cast type on complete denture base adaptation

introduction: few researches have been conducted researches on the influence of the type of dental stone used for fabrication of casts on the adaptation of denture bases. the purpose of this study was to compare the effect of two types of stone casts on the accuracy of fit in complete denture bases. methods: using sixty fully replicated master casts obtained by duplicating a metal die representing an edentulous maxillary arch, 30 casts were poured in type iii dental stone and 30 made from type v dental stone. all dentures were completely waxed using a same thickness of base plate wax and teeth were made for the purpose of accuracy. following polymerization in the same working conditions, dentures were trimmed. after silicone injection between each denture and metal die was performed, weighing the elastomeric silicone layer was performed to study adaptation of dentures. metal die was used both before copying the casts and   after storing them in water for two months. results: the values ​​for silicone layer weight (in grams) in the group with dental stone type iii were greater than the values in type v  regardless of the studied period (both after polymerization and after water immersion for a period of two months) in the sample (p< 0.001). conclusion: the use of high expansion stone (type v) had improved the adaptation of denture bases.