Three-Dimensional Accuracy of Printed Alveolar Casts

Abstract

Objective: The purpose of this in-vitro study was to evaluate the accuracy of 3D printed alveolar casts fabricated with three different 3D printers from digital scans on a reference typodont in the scenario of a maxillary veneer, two crowns, fixed dental prostheses and onlay. Material and Methods: A reference cast, prepared using a Kilgore K-2 typodont with various tooth preparations, was scanned using a Trios4 intra-oral scanner. This created an STL file that served as a digital reference for superimposition and the design of a digital alveolar cast. The digital cast was designed using (Exocad Dental CAD® 3.1 Rijeka) software, including movable dies and a cast base. This design was then exported as an STL file for 3D printing. Three 3D printers (Carbon DLS, Straumann P30+, Formlabs Form3b+) were used to print the alveolar casts, and all were cleaned and post-cured as per the manufacturers' instructions. The printed casts were then digitized using the same intra-oral scanner, and the resultant digitized casts were exported as STL files. Finally, the 3D deviations of each printed cast were calculated by superimposing the cast STL files onto the original digital reference cast using Geomagic Control X software. The software then determined the root mean square error for each clinical scenario. Results: The study observed significant differences between specific pairs of dental restorations in each category except for the veneers. For onlays, Carbon showed significantly lower RMS error compared to Formlabs® Form3b+ (P<0.001). In post-hoc comparisons, between Formlabs® Form3b+ and Straumann® P30+ (P=0.044). Similarly, Carbon exhibited significantly lower RMS error in the gold crown category than Formlabs® Form3b+ (P<0.001). For ceramic crowns, both Formlabs® Form3b+ and Carbon had significantly higher RMS error than Straumann® P30+ (P=0.004 and P=0.010, respectively). In fixed dental prostheses (FDP), Carbon had significantly less deviation than both Straumann® P30+ and Formlabs® Form3b+ (P<0.001). Notably, no significant differences were found among the veneers' RMS error values (P=0.055). Conclusion According to this study, the Continuous Liquid Interface Production (CLIP) printer exhibited higher accuracy compared to the Stereolithography (SLA) printer for onlays (P<0.001), gold crowns (P<0.001), and fixed dental prostheses (P<0.001). Also, the Continuous Liquid Interface Production (CLIP) printer exhibited higher accuracy compared to the Digital Light Processing (DLP) for fixed dental prostheses (P<0.001). On the other hand, the Digital Light Processing (DLP) exhibited higher accuracy compared to Continuous Liquid Interface Production (CLIP) the Stereolithography (SLA) printer for ceramic crowns (P=0.010), (P=0.004) respectively