Evaluation of master cast techniques for multiple abutment implant prostheses

This study compared the accuracy of three techniques used to fabricate master casts for implant prostheses. A metal model with six implants and standard abutments and a matching template were fabricated. Impressions of the model were made in Impregum and cast in Die Keen. The casts were divided into three groups of 15 casts: group A--solid casts; group B--Pindex; and group C--Zeiser system. Each cast was visually evaluated for fit of the template. Positional accuracy of the abutments was numerically assessed using an optical comparator. Visual analysis showed that only casts sectioned with the Zeiser system allowed a passive fit of the template. Statistical analysis of numerical findings indicated that casts made with the Zeiser system were significantly more accurate than solid casts, which in turn were more accurate than those made with the Pindex system.