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Updated: Jul 22, 2026
Accuracy in Dental Medicine, A New Way to Measure Trueness and Precision
Published on: April 29, 2014
[Accuracy of Conventional and Digital Impressions for Complete-Arch Implant-Supported Restorations]
1（ 610041） State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
Objective:
To evaluate the accuracy of conventional impression techniques, intraoral scanning, and two stereophotogrammetry systems (PIC and ICam4D) for complete-arch implant restorations, and to analyze the influence of varying interimplant distance and implant angulation on the accuracy of each impression method.
Methods:
A total of 6 edentulous maxillary all-on-four casts were fabricated with varying posterior implant parameters, including anterior-posterior (A-P) distances of 20 mm and 35 mm and distal implant angulations of 0°, 15°, and 25°. Impressions were obtained using conventional impression techniques, intraoral scanning, and two stereophotogrammetry systems (PIC and ICam4D). The three-dimensional deviations of the impression techniques were measured using reverse-engineering software to evaluate trueness and precision.
Results:
The accuracy of intraoral scanning technology exhibited a declining trend with increasing A-P distance and implant angulation. The maximum deviations in trueness and precision were observed in the posterior region with an A-P distance of 35 mm and a distal implant angulation of 25°, measuring (76.90 ± 43.32) μm and (99.43 ± 74.39) μm, respectively. The conventional impression techniques exhibited stable performance, with mean accuracy deviation values consistently falling below 50 μm. The ICam4D stereophotogrammetry system exhibited the highest precision across all conditions (P < 0.05). The maximum precision deviation for PIC system occurred in the right anterior region with an A-P distance of 20 mm and a distal implant angulation of 15° ([28.10 ± 18.73] μm), while the maximum trueness deviations for both PIC and ICam4D were observed in the anterior region with an A-P distance of 20 mm and a distal implant angulation of 25°, measuring (62.63 ±9.40) μm and (83.61 ± 1.76) μm, respectively. The PIC system showed better overall trueness than ICam4D did when distal implant angles were ≥ 15° (P < 0.05).
Conclusion:
For complete-arch implant rehabilitation, the accuracy of different impression methods varies depending on implant-related factors. The inter-implant distance and angulation were critical determinants of accuracy for intraoral scanning, whereas conventional impression techniques and the two stereophotogrammetry systems exhibited no clear correlation with these parameters.
