Influence of number and location of implants and data acquisition device on the accuracy of an app-based extraoral photogrammetry and noncalibrated implant scan body system.

STATEMENT OF PROBLEM: The accuracy of complete arch implant scans is highly dependent on the implant scanning technique used to capture the implant positions. The influence of the number and location of implants and data acquisition device on the performance of the including app-based extraoral photogrammetry (PG) and noncalibrated implant scan body (ISB) systems remains unknown. PURPOSE: The purpose of this in vitro study was to assess the influence of the number and location of implants (4 in the anterior and posterior or 6 implants) and data acquisition device on the trueness and precision of complete arch scans captured using an app-based extraoral PG and noncalibrated ISB system. MATERIAL AND METHODS: A stone cast with 6 implant abutment analogs (MultiUnit Abutment) was obtained. A laboratory scan was used to obtain the reference file. Three groups were created based on the number of implants: 6, 4 posterior, and 4 anterior implants of the reference cast. Three subgroups were developed based on the implant scanning technique and acquisition device used to capture the scans: app-based (T-Marker) with a tablet (iPad) or a smartphone (iPhone), and a noncalibrated ISB system (IOConnect) with an intraoral scanner (IOS) (i900) (n=30). The reference and experimental scans were imported into a program (DentalCAD) to design an implant-supported bar. The designs were imported into another program (Geomagic) to measure the linear and angular distances among the implants. The measurements obtained from the reference file were used as a control to calculate the discrepancies for each specimen. Two-way ANOVA and post hoc pairwise comparison tests were used to analyze trueness. The Levene test was used to analyze precision (α=.05). RESULTS: Linear trueness discrepancies were found among the groups (P=.016) and subgroups (P<.001), with a significant group×subgroup interaction (P=.006). Additionally, angular trueness discrepancies were found among the groups (P=.001) and subgroups (P<.001), with a nonsignificant group×subgroup interaction (P=.591). Overall, the 4-post group had the best linear (P=.013) trueness and precision (P=.017); the 4-post and 4-ant groups had the best angular trueness (P<.001). The IOConnect subgroup had the best linear trueness (P<.001), the T-iPhone had the best linear precision (P<.001), and the T-iPhone and T-iPad subgroups had the best angular trueness (P<.001) and precision (P<.001). Additionally, when a tablet was used, scanning a cast with 6 implants resulted in lower linear trueness than with 4 implants; however, no significant differences in linear or angular discrepancies were observed across implant numbers or locations when using a smartphone. CONCLUSIONS: The number and location of implants, data acquisition devices, and implant scanning technique impacted the trueness and precision of complete arch implant scans.