Effect of Number and Angulation of Implants on Accuracy of Digital Impression in Completely Edentulous Arch.

Purpose: This study aims to evaluate the accuracy of the impression method using an intraoral scanner and the conventional method based on the implant number and angulation with multiple implants.

Materials and methods: Six implants were placed in the maxillary edentulous typodont using 3D modeling software. Eight implants were placed in another maxillary edentulous typodont. The implant placement angulation for each model was different. 3D designing and printing were performed to produce reference models. These models were scanned to obtain reference scan data (RSD). In the conventional impression method, reference models were used, and a gypsum model was produced. Scan data was obtained by the lab scanner (Group CI). Models were scanned and the scan data was obtained (Group IS). The distance and angulation deviation were compared.

Results: In models with six implants, except for the distance deviation in Model 6-20, the mean values of all distance and angulation deviations were lesser in Group CI than in Group IS (P < 0.05). In models with eight implants, except for the distance deviation in Model 8-20, the mean values of distance and angulation deviations were lesser in Group CI than in Group IS, and significant differences were observed between the two groups for Models 8-0, 8-10, and 8-20 (P < 0.05).

Conclusion: In cases where multiple implants are placed in the completely edentulous arch in vitro, conventional impressions are more accurate than intraoral scans. In the cases of lack of implant parallelism, intraoral scans can be used as a replacement for conventional impressions.