In vitro evaluation of the effect of auxiliary geometric device on measurement trueness and scanning time in full-arch implant impressions

This in vitro study aimed to evaluate the effect of clinically practical auxiliary geometric devices (AGD) on measurement trueness and scan time in full-arch implant-supported prostheses, focusing on different intraoral scanners (IOS) and implant angulations. Four implants were planned in an edentulous maxillary arch and divided into two groups based on posterior implant angulation: Model A (Parallel) and Model B (30°). Each model was evaluated under three auxiliary geometric devices (AGD) application types (std, agd1, agd2), and scanned using three different intraoral scanners (IOSs) [3Shape Trios 3 (T), Medit i700 (M), and Cerec Primescan (PS)], resulting in nine groups per model (n = 10). Scanning times and faulty scans were recorded. A conventional impression (CON) was taken as a control and digitized with a desktop scanner. Trueness was analyzed using Geomagic Control X, with statistical significance set at P < .05. Group B had higher RMS values than Group A (40.3 µm vs. 34.7 µm). T_std in Group A (51.4 µm) and T_std (53.1 µm) and Con (50.7 µm) in Group B exceeded the acceptable deviation limit. AGDs reduced deviations to acceptable levels in the Trios 3. The Primescan scanner had the shortest scanning times. AGD use, especially in T_agd2 and M_agd2, shortened scan times and eliminated erroneous scans. The use of AGD has a significant impact on scanners' scanning trueness and time.