Investment material and mold for dental use and burnout thereof

摘要

Dental investment materials for providing inexpensive dental investments which are free from the occurrence of cracks, crevices or breakage and can greatly reduce the metal casting time, dental casting molds using the same and a process for burning them. The dental investment material contains as the major components a calcined gypsum powder, a cristobalite powder and a quartz powder and additionally contains a gas permeability improving additive. In the dental investment prepared using such dental investment material, the thermal expansion can be dispersed and the steam pressure generated can be released effectively during calcination and burning.