Influence of Implant Spatial Configuration on the Trueness of Complete-Arch Digital Implant Impressions: An In Vitro Study

Accurate, complete-arch digital implant impressions remain challenging because cumulative image stitching distortion may increase across geometrically complex edentulous arches. This in vitro study evaluated the influence of implant spatial configuration on the trueness of complete-arch digital implant impressions obtained using current-generation intraoral scanners. Three edentulous mandibular models representing different implant spatial configurations were fabricated: closely spaced parallel implants, widely distributed parallel implants, and angulated implants. Seven intraoral scanners (Trios 3, Trios 4, Trios 5, Medit i500, Primescan 1, Primescan 2, and Aoralscan 3) were evaluated. Ten scans were acquired per model and scanner, generating 210 STL datasets. A CAD replacement workflow based on scan body library geometries was performed prior to deviation analysis. Trueness was evaluated using root-mean-square (RMS) deviation values following iterative closest point alignment with reference datasets obtained using a laboratory scanner. Statistical analysis was performed using two-way ANOVA and post hoc comparisons (α=.05). Significant differences were observed among scanners (p< .001), implant configurations (p< .001), and their interaction (p< .001). Lower RMS deviation values were generally observed in the closely spaced implant configuration, whereas widely distributed implants demonstrated the highest deviations across most scanners. Primescan 1 and Primescan 2 exhibited lower RMS deviation values and smaller increases in distortion across geometrically complex configurations. The spatial configuration of implants significantly influenced the trueness of complete-arch digital implant impressions. Increased implant spatial complexity was associated with greater cumulative stitching distortion during intraoral scanning procedures. Scanner performance varied with implant configuration, suggesting differing resistance to cumulative distortion among current-generation intraoral scanners.