A limited laboratory study was made to compare the general appearance and accuracy of aluminum castings made from a standard pattern using three different investments. Three castings were made with each investment. Gray investment was used because recent studies and clinical experience have shown satisfactory results can be obtained with this material. Another hydrocal-bonded investment (investic) was used because this material may be desirable when aluminum is cast onto metal mold inserts. A phosphate-bonded investment (multivest) was used following the rapid jelling shell investment procedure because of the speed with which a casting can be obtained. Good castings of similar appearance were obtained with each investing material. The two hydrocal-bonded investments produced castings of similar accuracy when measured with a surface meter. Repeated measurements of one casting demonstrated that the fit of an aluminum denture base can be destroyed by careless polishing. An aluminum alloy was used to construct prosthetic appliances for clinical patients. These included a partial denture and a speech aid appliance which had wrought wire clasps, surgical splints, and a complete denture with an aluminum occlusal surface. The initial evaluation of these appliances is discussed and the other clinical observations are reported. (Author)
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