Accuracy of implant impressions using various impression techniques and impression materials

Purpose: This in vitro study was to investigate the accuracy of two kinds of impression techniques (open and closed tray) with three impression materials (polyvinylsiloxane [PVS]/polyether [PE]/vinylsiloxanether [VSE]) on angulated implants. Materials and Methods: The reference model was a stainless steel die with six analogs placed at 0°, 10°, and 20° toward the center axis. Custom acrylic trays were made on a stone model replica of the reference die. A total of sixty samples of twenty each were made under each type of impression material. Each group was divided into open and closed tray groups. Two types of splinting were carried out in the open tray: Group 1 - with floss and pattern resin and Group 2 - with a plastic rod (coffee stirrer) and resin. Impressions were poured with Type IV stone to obtain experimental casts and were evaluated for positional accuracy by coordinate measuring machine in three dimensions (X, Y, and Z). Differences in measurements were analyzed using analysis of variance and Tukey′s test. Results: The lowest mean deviation was found in casts made from open tray splinted with floss and resin. There was also a significant difference in the measurements of PVS, PE, and VSE. Conclusion: VSE impression material yielded more accurate casts than those of PVS and PE. Splinting with floss and pattern resin was found to be more accurate than stirrer and resin.