title: [Effects of investment materials on cast shrinkage of base metal alloys].
abstract: OBJECTIVE
  To compare the influence of different investment materials, methods and crown height on the cast shrinkage of full crowns made of dental base metal alloy.
  
  
  METHODS
  All of the 288 wax patterns were made and divided into three groups according to their crown height. In every group, wax patterns were invested in metal rings and paper rings with three types investment material and cast with base metal alloys. Then the inside diameters of castings were measured and analyzed by statistical package SPSS.
  
  
  RESULTS
  Differences between groups invested with the three types of material were significant(P < 0.01). There were significant difference between the groups investing with metal rings and paper rings(P < 0.01).
  
  
  CONCLUSIONS
  The component of investment material and invested ring can affect the cast shrinkage of dental base metal alloy apparently.
authors.affiliation: Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110002, China.
authors.forename: Zhenchun
authors.initials: Z
authors.lastname: Li
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
authors.forename: Fengyu
authors.initials: F
authors.lastname: Hao
mesh_terms: D003442:Crowns / Q000592:standards; D003722:Dental Alloys / Q000592:standards*; D003734:Dental Casting Investment; D003735:Dental Casting Technique / Q000295:instrumentation; D006801:Humans; D007283:Inlay Casting Wax / Q000737:chemistry* / Q000145:classification; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods; D016876:Metal Ceramic Alloys / Q000592:standards; D017755:Prosthesis Fitting
chemical_list: D003722:Dental Alloys; D003734:Dental Casting Investment; D016876:Metal Ceramic Alloys; D007283:Inlay Casting Wax