Evaluation of the accuracy of conventional and digital impression techniques for angulated implants: an in vitro study

The aim of this in vitro study was to evaluate the accuracy of implant impressions obtained using open-tray, closed-tray and digital impression techniques for implants placed at different angulations and inter-implant distances in partially edentulous maxillary models. Two acrylic resin maxillary models simulating partial edentulism were fabricated. Each model contained four implants positioned with different angulations (0°, 17°, and 30°) and inter-implant distances (15.3 mm and 25.3 mm). Impressions were obtained using open-tray, closed-tray, and digital impression techniques ( n = 10 per group). Three-dimensional linear deviations of implant positions were measured using a photogrammetry-based system (PiC Dental System). Data were analyzed using multivariate analysis of variance (ANOVA), Shapiro–Wilk, and Mann–Whitney U tests (α = 0.05). Impression accuracy was significantly influenced by impression technique ( p < 0.001 ) and implant angulation ( p < 0.001 ), whereas inter-implant distance had no significant effect ( p = 0.18 ). No statistically significant difference was found between the open-tray and closed-tray techniques overall. For implants with 30° angulation, the open-tray technique demonstrated lower deviation values than both the closed-tray and digital techniques. The highest deviations were observed in digitally produced models associated with angulated implants. İmplant angulation should be considered when selecting an impression protocol for partially edentulous maxillary implant restorations, whereas inter-implant distance did not significantly affect impression accuracy under the conditions evaluated in this study.