Comparative Evaluation of the 3-Dimensional Implant Impression Accuracy between Conventional and Digital Impression Using Two Different Intraoral Scanners: An In Vivo Study

Abstract

Background: Accurate three-dimensional (3D) recording of implant positions is fundamental to achieving passive fit and long-term success of implant-supported prostheses. The growing adoption of digital intraoral scanners (IOS) necessitates rigorous clinical evaluation of their accuracy relative to established conventional methods. Purpose: To compare the 3D accuracy of implant impressions obtained with a conventional open-tray technique, the Primescan (Dentsply Sirona), and the Aoralscan 3 (Shining 3D) intraoral scanners under in vivo conditions. Materials and Methods: A standardised splinted open-tray reference model was fabricated for each patient and served as the control, scanned with a high-precision Zeiss ATOS 5 industrial scanner. Each patient additionally underwent one conventional polyvinyl siloxane (PVS) impression and two digital scans. All datasets were exported as STL files and superimposed using Zeiss Inspect 2025 reverse-engineering software. Inter-implant distance deviation, angular deviation, and 3D linear displacement were measured and compared using one-way ANOVA followed by Tukey post hoc tests (p < 0.05). Results: Statistically significant differences were observed for inter-implant distance (F = 18.776, p < 0.001) and angular deviation (F = 45.144, p < 0.001) among the three techniques. Primescan demonstrated the lowest mean deviations (inter-implant: 0.40 mm; angular: 0.68°), followed by Aoralscan 3 (0.67 mm; 1.07°), while conventional impressions showed the highest values (1.15 mm; 2.11°). Linear displacement did not differ significantly across groups (p > 0.05). Both digital systems performed within clinically acceptable thresholds. Conclusions: Digital impression techniques — particularly Primescan — produced superior accuracy compared with conventional impressions for inter-implant distance and angular parameters under clinical conditions. Both IOS systems offered clinically acceptable accuracy, supporting their selective use in implant prosthodontic workflows.