Gellért Levente Joós-Kovács, Bálint Vecsei, Szandra Körmendi, Judit Borbély, Péter Hermann
Department of Prosthodontics/Semmelweis University, Budapest
Introduction CAD/CAM (computer aided design/computer aided manufacturing) generated restorations offer two options for digitalization: direct and indirect ways. During indirect way conventional impression, mastercast and sectioned cast are made which can be digitized by laboratory scanners. This study follows the most commonly used indirect digitalization: scanning sectioned casts with optical laboratory scanner.
Aim To evaluate the accuracy of indirect CAD/CAM digitalization and virtual models produced by optical laboratory scanner
Method A polymethyl methacrylate (PMMA) cast was used as reference. A high-resolution industrial scanner (reference scanner) was used to create the virtual reference model. Polyvinyl-siloxane (PVS) impressions were made (n = 10) from the PMMA model. PVS impressions, mastercasts and sectioned casts were scanned by the reference scanner. A laboratory scanner (Straumann CS2Scan) was used to digitize the sectioned cast. The stereolithographic (STL) files of the impressions (n = 10), mastercasts (n = 10), sectioned casts (n = 10) and laboratory scanner files (n = 10) were exported. To enable virtual caliper measurements each file was compared to the reference.
Results Significant differences were observed according to tooth sizes between the steps of indirect CAD/CAM technology at all eight locations of interest. Significant differences were observed between all the indirect CAD/CAM digitalization steps considering arch distances. Distance between dies became larger after the impressions were poured with gypsum. Sectioning of the mastercast resulted shrinkage of the cast. Desktop scanner made virtual casts showed smaller distances compared to any of the previous steps values.
Conclusion Virtual models made by indirect CAD/CAM method can used to make dental prostheses. There are differences between the dimensions represented by the sectioned cast and the optical laboratory scanner made virtual cast. The scanning procedure influences the volume of dies. Software alignment and corrections influences the distance of the dies.
Doctoral School: Clinical Medicine
Program: Dental Research
Supervisor: Péter Hermann
E-mail address: email@example.com