Accuracy of intraoral optical scan versus stereophotogrammetry for complete-arch digital implant impression: an in vitro study

Purpose: To assess and compare the accuracies of intraoral scanners (IOS) and stereophotogrammetry (SPG) devices for complete-arch digital implant impressions. Methods: A 4-analog model was digitized using a desk scanner to obtain a reference file. Thirty test scans were conducted using the investigated IOS device, while an additional 30 scans were performed using the SPG device. Using the best-fit al-gorithm, the resulting 60 test files were aligned with the reference file. Linear (& UDelta;X, & UDelta;Y, and & UDelta;Z-axis) and angular deviations (& UDelta;ANGLE) were evaluated. Three-dimensional (3D) deviation was calculated based on the Euclidean distance (& UDelta;EUC). The analysis was stratified according to the scanning device and implant position. Fisher's F and t-tests were used to compare the variances and expected values of the two scanning systems. Results: IOS expressed a higher 3D (& UDelta;EUC) mean deviation than SPG (52.8 & mu;m vs. 33.4 & mu;m, P < 0.0001), with extreme measurements up to 181.9 & mu;m. A significantly higher standard deviation (SD) was associated with IOS (37.1 & mu;m vs. 17.7 & mu;m, P < 0.0001). Considering angular deviations, the IOS showed slightly higher angular mean deviations (& UDelta;ANGLE) than the SPG (0.28 & DEG; vs. 0.24 & DEG;, P = 0.0022), with extreme measurements of up to 0.73 & DEG;. The SPG SD values were significantly lower than the IOS SD values (0.14 & DEG; vs. 0.04 & DEG;, P < 0.0001). Conclusions: The SPG showed significantly higher 3D and angular accuracies for complete arch implant impressions, with consistent repeatability. IOS scanning revealed significantly higher extreme deviations exceeding the acceptable thresh-old value. Despite study limitations, SPG appears more feasible than IOS for complete-arch digital implant impressions.