Accuracy of a chairside reverse scanbody workflow for a complete arch implant-supported prosthesis using four intraoral scanners versus a desktop scanner

Objectives: The aim of this study was to evaluate the accuracy of a chairside reverse scanbody workflow for a complete arch implant-supported prosthesis using four intraoral scanners (IOSs) and a desktop scanner.Material and Methods: A complete arch implant-supported interim prosthesis was designed and milled in poly-methylmethacrylate. Six reverse scanbodies (ScAnalog) were connected to the implant-prosthetic connections and twenty scans were made extraorally using four IOS devices (TRIOS 3, TRIOS 5, Primescan v.5.2, Medit i700W) and one desktop scanner (E4 RED). A coordinate machine (ATOS Q GOM) was used to assess the milling distortion. The scanbody positions were compared to the reference CAD design using metrology software. Linear and angular measurements per implant-prosthetic connection were considered for trueness and precision. Data were analyzed using one-way ANOVA and Bonferroni test.Results: Trueness values were 118.14 +/- 25.49 mu m for TRIOS 3, 84.62 mu m +/- 19.10 for TRIOS 5, 106.39 +/- 27.58 mu m for Primescan v.5.2, 120.25 +/- 27.44 mu m for Medit i700W and 65.36 +/- 4.66 mu m for E4 RED. Significant differ-ences in mean trueness values were found among IOS and E4 RED. Precision values were 108 +/- 55 mu m for TRIOS 3, 86 +/- 55 mu m for TRIOS 5, 104 +/- 55 mu m for Primescan v.5.2, 90 +/- 54 mu m for Medit i700W and 18 +/- 11 mu m for E4 RED. Significant differences in precision were found between IOS and E4 RED.Conclusions: A chairside reverse scanbody workflow with IOS remains less accurate compared to similar work-flow with a desktop scanner. Clinical significance: A chairside reverse scanbody workflow is a valuable alternative but the IOS device should be selected with caution because in the present study, only TRIOS5 was capable to achieve an accuracy below the clinical acceptable thresholds. The use of a desktop scanner remains the best choice for this clinical workflow. Additionally, the milling distortion of the interim prosthesis plays a major role in this reverse scanbody workflow and should be kept as low as possible.