A New Method of Deflasking the Working Casts Using Static Splitting Agent after Curing

A new method of deflasking the cast has been developed to recover the denture easily without any deformation or fracture after curing. This new technique utilizes the mechanism of expansion based on hydration of an expansive agent with the main component of CaO. The method using static pressure, and mild splitting of the cast, was clinically applied instead of the conventional dynamic method. The maximum value of the expansive pressure was about 120Kg/cm2 in a metal cylinder using the agent with a 40% water content. In dental stone cylindrical models, the pressure was estimated to be 96Kg/cm2. No permanent set or fracture of the denture was observed in the experiment using eleven denture models. The maximum value of 6500μstrain during splitting with this agent was within the proportional limit of the resin. As the expansive pressure is produced gradually, this method is very efficient for removing the denture from the cast in clinical application.