Comparative analysis of direct and indirect implant impression techniques an in vitro study. An in vitro study

Implant impression and transfer of the implant position to a working cast for rehabilitative purposes not always represent a predictable reconstructive step. The variable results depend on the transfer technique utilized and on the accuracy of the impression materials. The aim of this study was to compare the accuracy of the direct and indirect impression techniques and to analyze the distortion of different impression materials. An edentulous acrylic resin mandible was used as reference model: in the cuspid position 2 laboratory analogs were inserted perpendicularly to the occlusal plane and fastened with resin. Two impressions for each indirect and direct recording techniques with 4 different impression materials were made. Polyvinyl siloxanes were used for the repositioning implant level method. Polyethers were used for the ''pick up'' impression technique. Analysis of cast distortion was measured computing the inter-implant position on the developed models compared to that of the master model. Measurements were recorded by a digital caliper. The results of this in vitro study demonstrate that the direct impression technique is preferable to the indirect one and that the Impregum polyether impression material is the most precise when used in association with a direct technique.