Factors affecting the retention and fit of gold castings.
A study was designed to simulate clinical conditions. Several factors were evaluated for effect on retention and fit (margin adaptation) of gold castings. Twenty-six castings (13 pairs) were made by different investigators using a standard preparation but with varying fabrication techniques. One of each pair of castings was made on a spaced die and one on an unspaced die. A significant difference in the postcementation retention was observed in the varying techniques of each investigator. Retentive values varied from 29 to 129 lbs. Complete seating of the castings during cementation was improved by the use of die spacer. Castings made on the spaced dies had more retention than corresponding unspaced castings. Die spacing has positive benefit when properly used. Moderate roughness of axial surfaces improves retention when zinc phosphate cement is used. Physical properties of restorative materials are important, but the individual technique and care of each investigator has a major effect on the ultimate fit and retention of the cast restoration.