Accuracy of complete‐arch implant positions recorded by analog impressions, intraoral scanning, and extraoral and intraoral photogrammetry

PURPOSE: The purpose of this in vitro study was to compare the accuracy of analog impressions, intraoral scanning, extraoral photogrammetry, and intraoral photogrammetry in recording complete-arch implant positions. MATERIALS AND METHODS: A stainless-steel reference model representing an edentulous maxilla with six parallel implants and multiunit abutments was tested using two analog impression techniques; seven intraoral scanners with vertical scan bodies: Omnicam, Primescan, Trios 3, Trios 4, Trios 5, i700, and Aoralscan 3; three extraoral photogrammetry systems: PIC, iCam4D, and Tupel 3D; and one intraoral photogrammetry system: Aoralscan Elite (n = 10 per group). A coordinate-measuring machine measured the abutment center positions and axes on the reference model and analog stone casts, and a computer-aided design program measured the intraoral scanning and photogrammetry digital files. The inter-abutment distances and angles were compared to determine the accuracy of each technique. RESULTS: The analog groups recorded linear trueness of 39-47 µm (precision 17-18 µm) and angular trueness of 0.07°-0.08° (precision 0.02°-0.05°). The intraoral scanning groups recorded linear trueness of 78-141 µm (precision 18-83 µm) and angular trueness of 0.23°-0.71° (precision 0.05°-0.24°). The extraoral photogrammetry groups recorded linear trueness of 53-77 µm (precision 2-30 µm) and angular trueness of 0.22°-0.57° (precision 0.01°-0.05°). The intraoral photogrammetry recorded linear trueness of 15 µm (precision 6 µm) and angular trueness of 0.11° (precision 0.02°). CONCLUSIONS: Intraoral scanning demonstrated deviations (mean 101 µm) over twice that of analog impressions (mean 43 µm), while extraoral photogrammetry (mean 62 µm) and intraoral photogrammetry (mean 15 µm) demonstrated accuracy comparable or superior to analog impressions.