Evaluation of four digital methods in capturing complete-arch implant positions: Direct scanning, splinted scan bodies, three-dimensional-printed scan aids, and intraoral photogrammetry.
PURPOSE This study compared the trueness of four digital impression methods in capturing complete-arch implant positions. MATERIALS AND METHODS An edentulous mandibular model with four angled multi-unit abutment analogs was fabricated and digitized using a desktop scanner (Vinyl HR; Smart Optics) to create a reference dataset. An intraoral scanner (IOS) (Aoralscan Elite; Shining three-dimensional [3D]) equipped with intraoral photogrammetry (IPG) was used for the experimental scans. Four methods were evaluated: direct scanning without splinting (scan body [SB]), splinting scan bodies with light-polymerized acrylic resin (SP), scanning with custom 3D-printed scan aids (SAs), and IPG. A power analysis determined the need for 21 scans per group. Standard tessellation language files were imported into CAD software, converted into implant abutment replicas, and analyzed using 3D inspection software (Geomagic Control X; 3D Systems) to assess 3D, linear, and angular discrepancies. Trueness was analyzed with Kruskal-Wallis and one-way analysis of variance tests (α = 0.05), followed by post hoc analysis. RESULTS The SB group showed the highest 3D distortion, and the SP group exhibited the highest angular deviation. The IPG and SA groups had comparable linear and 3D deviation values without significant differences. IPG demonstrated the lowest angular distortion of all methods. The right posterior implant recorded the highest 3D distortion, whereas the right anterior implant exhibited the greatest angular deviation. CONCLUSIONS IPG and SA approaches yielded comparable results, except for angular distortion. These findings provide evidence for selecting optimal digital workflows in full-arch implant rehabilitation. Scan aids can enhance the performance of IOSs in acquiring complete-arch digital impressions, with trueness values approaching IPG systems.