OBJECTIVETo compare the influence of different investment materials, methods and crown height on the cast shrinkage of full crowns made of dental base metal alloy.

METHODSAll 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.

RESULTSDifferences 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).

CONCLUSIONThe component of investment material and invested ring can affect the cast shrinkage of dental base metal alloy apparently.

Crowns ; standards ; Dental Alloys ; standards ; Dental Casting Investment ; Dental Casting Technique ; instrumentation ; Humans ; Inlay Casting Wax ; chemistry ; classification ; Materials Testing ; instrumentation ; methods ; Metal Ceramic Alloys ; standards ; Prosthesis Fitting