title: [Exploration and classification in the amount of die stone of working cast model of denture restoration].
abstract: OBJECTIVE
  The objective of this study was to survey the amount of working cast model of denture restoration, and to calculate the amount of die stone powder of each working cast model, then to classify the working cast model, with the expectation to perfuse the working cast model in clinic according to this classification, and to achieve the goal of increasing quality of working cast model and saving materials.
  
  
  METHODS
  311 working cast models were selected to perfuse with three kinds of tray including small size, middle size and large size randomly in clinic. The amount of die stone powder of working cast model was calculated, and the data were analyzed using SPSS 13.0 software package. The mean values of the die stone powder was used to establish a classification, which was verified clinically.
  
  
  RESULTS
  The results showed that the working cast model of denture restoration could be divided into three kinds: small group (< or = 45 g), middle group (46-55 g) and large group (56-65 g). The samples for verification were all in the size of this classification of the amount of die stone powder.
  
  
  CONCLUSIONS
  There is a close relationship between the amount of die stone powder of working cast model and the size of the tray, the dental arch. By clinical application of the classification, quantitative control of standard water powder ratio, improvement of model qualities and saving of materials can be achieved.
authors.affiliation: Department of Prosthodontic, College of Stomatology, Fourth Military Medical University. Xi'an 710032, Shanxi Province, China. zhouligen_001@163.com
authors.forename: Li-Gen
authors.initials: LG
authors.lastname: Zhou
authors.forename: Tian-Wen
authors.initials: TW
authors.lastname: Guo
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Li
authors.forename: Li-Zhen
authors.initials: LZ
authors.lastname: Yin
mesh_terms: D003778:Dentures; D006801:Humans; D008953:Models, Anatomic; D003765:Models, Dental