Background and Aim: One of the main goals in the fabrication of an implant-supported prosthesis is to build a superstructure with passive fitness. If this fails, it will lead to the failure of the implant components. This study aimed to investigate the effect of Duralay and Pattern Resin splinting materials on dimensional accuracy in the open tray impression technique. Materials and Methods:An edentulous acrylic model was developed. In the lateral teeth area, two implants (CMI, Neobiotech Co.) were placed perpendicularly and parallel to each other. The implants were cemented with cyanoacrylate. Pattern Resin (n=10) and Duralay (n=10) were used to splint the impression copings, and the impression was taken using the open tray technique. The main casts (20 pieces) were made with Vel-Mix type IV plaster using a vacuum mixer. The dimensional changes of each group were measured using a multi-axial coordinator. T-test was used to analyze the data. Result: The mean dimensional changes of implant position transfer at the x-axis were 5.04±0.37 μm for Duralay and 5.58±0.13 μm for Pattern Resin. The mean dimensional changes of implant position transfer at the y-axis were 7.01±0.49 µm for Duralay and 6.78±0.15 µm for Pattern Resin. The mean dimensional changes of implant position transfer at the z-axis were 7.62±0.71 µm for Duralay and 6.86±0.12 µm for Pattern Resin. T-test showed that the difference between the two groups was not statistically significant (P>0.05). Conclusion: According to the results, Duralay and Pattern Resin were not significantly different regarding dimensional changes in the open tray impression technique.