Purpose: This study aimed to evaluate the accuracy of two different impression materials used with an open tray technique in case of splinted and unsplinted techniques. Materials and Methods: An impression was taken to a prototype with missing lower left second premolar, first and second molars. The impression was poured using transparent acrylic resin and two implants were inserted in parallelism in the area of missing lower second premolar and lower second molar and were fixed in place with the help of the self curing transparent acrylic resin.Twenty self cured acrylic resin custom made trays were fabricated with the help of 2mm thickness vacuum spacer. Two impression materials were used with two impression techniques using an open tray.Group (1): Unsplinted open tray technique which was further subdivided into two subgroups: subgroup A (vinylsiloxane ether) and subgroup B (polyether).Group (2): splinted open tray technique which was subdivided into two subgroups:subgroup A (VSXE) and subgroup B (polyether). All impressions were poured using type IV dental stone. For measurement purposes two points representing reference points were engraved on the master model around each implant through which the measurements were made. Four dimensions were measured using the stereomicroscope. Dimensions were measured on all the twenty five poured casts and the master model which was taken as a reference. All measurements were recorded and the data collected was tabulated and subjected to statistical analysis to detect the changes in dimensions in mm as well as the % of dimensional change for each produced cast.Conclusions: (1)Selecting the appropriate impression material and technique is important to achieve the optimal accuracy in transferring implant position and produce passively fitting restorations.(2)Vinylsiloxanether is more appropriate impression material than the polyether material in terms of least % of dimensional changes used with splinted and unsplinted techniques.(3)In terms of inter-abutment distance, unsplinted impression technique recorded with polyether, revealed the least dimensional changes compared to the splinted technique.