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 patternswere made and divided into three groups according to their crown height. In every group, wax patternswere invested in metal rings and paper ringswith three types investmentmaterial and castwith base metal alloys. Then the inside diameters of castingswere measured and analyzed by statistical package SPSS.Results Differences between groups invested with the three types of material were significant(P
