Relative accuracy of intraoral photogrammetry and intraoral scanning with conventional scan‐body for full‐arch implants

PURPOSE: To compare the relative accuracy of intraoral photogrammetry (IPG) and intraoral scan (IOS) with conventional scan bodies (IOS-CB) for complete-arch implant impressions, using the conventional splinted open-tray impression digitized with a laboratory scanner (COT-LS) as the reference standard. MATERIALS AND METHODS: Twenty-six edentulous maxillary arches restored with four BioHorizons Tapered Internal implants supporting multiunit abutments were included. For each patient, three impressions were obtained: (1) a conventional splinted open-tray impression poured in type IV dental stone and scanned with a laboratory extraoral scanner to generate the COT-LS dataset; (2) an IOS-CB using the Aoralscan Elite, with scan bodies present from the outset of a single continuous scanning pass; and (3) an IPG scan using the same device in photogrammetry mode with dedicated scan flags mounted on the multiunit abutments. STL files were analyzed in Geomagic Control X, with the COT-LS dataset used as the reference. Relative accuracy was quantified as centroid-based linear deviation from COT-LS following best-fit alignment. Measurement reproducibility was assessed using intraclass correlation coefficients (ICC) from two independent examiners analyzing the same datasets. The IOS-CB and IPG datasets were superimposed to calculate linear and three-dimensional positional deviations (µm). A repeated-measures two-way ANOVA with Tukey post hoc testing was performed (p < 0.05). RESULTS: IPG demonstrated significantly lower deviations than IOS-CB in the full-arch, anterior right, and anterior left regions (p < 0.001). IOS-CB showed significantly lower deviations than IPG in both posterior right and posterior left regions (p < 0.001). The full-arch mean deviation was lower for IPG (39.2 µm) than IOS-CB (45.1 µm). All deviations for both techniques remained within the clinically acceptable threshold for passive fit. ICC values for measurement reproducibility exceeded 0.95 for both techniques. CONCLUSIONS: Within the limitations of this clinical study, IPG demonstrated a lower full-arch mean deviation than IOS-CB when evaluated against the COT-LS reference. However, as the inherent dimensional error of the COT-LS reference may approach or exceed the 5.9 µm between-technique difference, this finding should be considered hypothesis-generating rather than confirmatory evidence of a trueness advantage. Measurement reproducibility was high for both techniques (ICC >0.95).