In vivo evaluation comparison of noncalibrated implant scan body systems positioned following the arch shape or toward the center of the arch.

STATEMENT OF PROBLEM: Noncalibrated implant scan body (ISB) methods have been described for capturing implant positions. However, the accuracy of a recently introduced commercial noncalibrated ISB system, which can be positioned either following the arch shape or toward the center of the arch, remains unknown. PURPOSE: The purpose of this in vivo study was to compare the accuracy of complete arch implant scans recorded by using noncalibrated ISBs (Exact) aligned with the arch curvature, with and without the automatic identification of the ISB geometry, and a noncalibrated ISB system (Direct IP) positioned following the arch shape or toward the center of the arch. MATERIAL AND METHODS: A patient with 4 implant abutments participated in the study. To obtain the control file, 3 consecutive implant scans were obtained by using an extraoral photogrammetry system (Micron Mapper). Four groups were created depending on the scanning technique used to capture complete arch implant scans: noncalibrated ISBs aligned with the arch curvature without (Exact-noAI group) and with (Exact-AI group) the automatic identification of the ISB, and noncalibrated ISBs positioned following the arch shape (DIP-arch group) or oriented toward the center of the arch (DIP-center group) using an intraoral scanner (Sensa) (n=15). In the Exact-AI group, the corresponding ISBs were positioned into the implant abutments and connected with the splinting devices from a noncalibrated splinting system (Exact). In the Exact-noAI and Exact-AI groups, implant scans were obtained by disabling or enabling the automatic identification of the ISB geometry, respectively. In the DIP groups, the ISBs from a noncalibrated system (Direct IP) were positioned into the implant abutments following the arch shape or toward the center of the arch. The control and experimental scans were imported into a program (exocad) to design an implant-supported bar from each file. A reverse engineering program (Geomagic) was used to measure the Euclidean linear and angular distances among the implants of each bar. The mean of the measurements acquired in the control scans was used to measure scanning discrepancies with each experimental scan. One-way ANOVA and Games-Howell test Tukey tests were used to analyze linear trueness, and 1-way ANOVA and Tukey tests to analyze angular trueness. The Levene test was used to analyze precision (α=.05). RESULTS: Linear trueness differences were found among the groups (P=.003). The DIP-arch group obtained the worst linear trueness. The Levene test revealed linear precision discrepancies among the groups (P=.009). The DIP-center group obtained the best linear precision, whereas the DIP-arch had the worst linear precision. Additionally, angular trueness discrepancies were found among the groups (P=.018). The DIP-arch group obtained the best angular trueness among the groups tested. CONCLUSIONS: The noncalibrated ISB method impacted the accuracy of the complete arch implant scans recorded using the IOS tested.