Digitization of Impression Materials

Objectives: The precision of dental impressions is an important factor for the fit of dental restorations. Aim of this study was to assess the accuracy of scans from different impression materials in a commercial impression scanner. STL (surface tesselation language) files created by the scanner were analyzed and compared to scans of the master model.
Methods: Impressions (n=7) of an artificial jaw model were made with different impression materials either in monophase or 1-step impression technique (FFS-1step: Flexitime Fast&Scan Heavy Tray Dynamix with Flexitime Fast&Scan Light Flow (Heraeus Kulzer); IPDuoQ-1step: Impregum Penta H DuoSoft Quick with Impregum Garant L DuoSoft Quick (3M); EXPHL-1step: exp. Polyether Heavy with exp. Polyether Light (3M); EXPML-1step: exp. Polyether Medium with exp. Polyether Light; FM-mono: Flexitime Monophase Pro Scan Dynamix (Heraeus Kulzer); IPSQ-mono: Impregum Penta Soft Quick (3M); EXP-mono: exp. Polyether Medium (3M)). The model and the impressions were digitized with a blue LED multiline scanner (D2000, 3Shape) and data exported as STL-files. The absolute mean differences of the impression scans to the model scan were calculated (geomagic, Geomagic Inc., USA). Variances of dedicated scannable impression materials and 3M polyether impression materials were statistically analyzed with 2-sample equivalence-tests for an equivalence interval from 0-20µm (Minitab17, Minitab Inc., USA).
Results: Tables below show differences of impression scans to master model scan. All impressions are equivalent.
Conclusions: All direct impression scans showed a high and clinically suitable accuracy and were statistically equivalent. With current LED line scanners, various types of impression materials can be digitized without any surface treatment for easy access to CAD/CAM workflow.