An in-vitro study to evaluate the accuracy of master casts obtained from different transfer impression techniques for a multi-unit implant restoration using two different impression materials evaluated by a 3-D optical scanner.

Abstract Background: The precise transfer of implant positions from the oral cavity to the working cast is critical for the passive fit of implant-supported prostheses. This study aimed to evaluate and compare the accuracy of master casts obtained through various impression techniques using two elastomeric materials—Polyvinyl Siloxane (PVS) and Polyether (PE)—assessed using a 3D optical scanning system (DWOS). Materials and Methods: An edentulous maxillary reference model with four internal connection implants was used. Forty impressions were made using custom trays and categorized into eight groups (n=5 each) based on impression technique (closed/open tray), coping modification (non-modified, sandblasted, or splinted), and impression material (PVS or PE). Master casts were fabricated from each impression, and positional accuracy of implant analogues was evaluated using a DWOS 3D scanner by measuring horizontal distances between implants 2–3 and 1–4. Statistical analysis was performed using one-way ANOVA. Results: The mean reference distances between implants 2–3 and 1–4 were 1.308" and 2.748", respectively. Although variations were observed across different groups, the differences in accuracy were not statistically significant. Splinted copings exhibited the highest accuracy, followed by sandblasted and non-modified copings. Polyether impressions showed slightly better agreement with the reference model, but the difference was not statistically significant. Conclusion: Within the limitations of this in vitro study, both PVS and PE impression materials yielded clinically acceptable accuracy in transferring implant positions. Non-splinted, non-modified impression copings provided comparable results, offering a simpler and more time-efficient approach. Further clinical studies are necessary to validate these findings under intraoral conditions.