In vitro scan accuracy and time efficiency in various implant-supported fixed partial denture situations

Objectives: To compare the accuracy and time efficiency of different digital workflows in 3 implant-supported fixed partial denture situations. Methods: Three partially edentulous maxillary models with 2 implants (Model 1: implants at lateral incisor sites; Model 2: implants at right canine and first molar sites; Model 3: implants at right first premolar and first molar sites) were digitized (ATOS Capsule 200MV120, n=1) for reference scans. Test scans were performed for direct (Primescan (DDW-P) and Trios 3 (DDW-T)) and indirect (IDW) digital workflows (n=14). For IDW, stone casts (type IV) were obtained from vinylsiloxanether impressions and digitized (S600 Arti). The scan/impression and post processing times were recorded. Reference and test scans were superimposed (GOM Inspect) to calculate 3D point, inter-implant distance, and angular deviations. Kruskal-Wallis and Mann-Whitney tests were used for trueness and precision analyses (alpha=.05). Results: Tested workflows affected trueness (P <=.030) and precision (P<.001) of scans (3D point, inter-implant distance, and angular deviations) within models. DDW-P had the highest accuracy (3D point deviations) for models 1 and 3 (P <=.046). IDW had the lowest accuracy for model 2 (P<.01). DDW-P had the highest accuracy (inter-implant distance deviations) for model 3 (P <=.048). Direct digital workflow mostly led to lower angular deviations (P <=.040), and higher precision for models 2 (mesiodistal direction) and 3 (P<.001). The time for direct digital workflow was shorter (P<.001), DDW-P being more efficient than DDW-T (P=.008). Conclusion: Direct digital workflow was more accurate and efficient than indirect digital workflow in tested partial edentulism situations with 2 implants. Clinical significance: Tested intraoral scanners can be recommended for accurate and efficient impressions of anterior and posterior 3- or 4-unit implant-supported fixed partial dentures.