OBJECTIVEThe purpose of this study was to compare the compressive strength of phosphate-bonded investments.

METHODSThe three sorts of investments were mixed according to manufacturer's recommendation before poured in the molds. After heated up to 900 degrees C, every sample was mounted on a universal experimental machine to test its compressive strength in ambient.

RESULTSSignificant differences were found between the four groups(P < 0.01).

CONCLUSIONFrom the data above it is concluded that the compressive strength of X-20 Chrome Investment mixed with the special liquid was the highest.

Compressive Strength ; Dental Bonding ; Dental Casting Investment ; chemistry ; Dental Casting Technique ; instrumentation ; Materials Testing ; Phosphates ; chemistry

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