Comparative accuracy of implant impressian procedures

In this study, four impression procedures were assessed for accuracy in a laboratary model thot simulated clinical practice. The accuracy af stone casts with brass implont onologs wos measured against a standard framework. The fit of the framework on the casts wos tested by manual and visual judgment and by microscopic measurement. The measurements supported the clinical judgments. When acrylic resin was used to splint transfer copings in an impressian, oil casts were acceptable ond were more accurate than the best of the two other procedures, which did not use an acrylic resin splint. When an impression material was used to orient the transfer capings, the accuracy was better if undercut copings remained in the impression. When impressions were made by removing an impression from smooth transfer copings and replacing the copings in the impression, the majority of casts were unacceptable.