Accuracy of fit of digitally fabricated prototypes with different printers: A Comparative Study

Abstract

Aim: To test whether or not digitally fabricated (from two different 3D printers) prosthesis prototypes exhibit acceptable accuracy of fit on the master cast and compared the 3D printers in terms of accuracy of fit. Hypotheses: The digitally fabricated prosthesis prototypes (from two different 3D printers) generated from a complete digital workflow via the double digital scanning technique will exhibit acceptable accuracy of fit on the master cast. The Form 3b and Carbon M2 3D printers will be equally accurate in comparison to each other. Materials & Methods: A maxillary stone cast with 6 abutment-level implant analogs (SRA, Straumann) with adequate antero-posterior (AP) spread simulated a common clinical condition. This stone cast served as the master (reference) cast for taking digital impressions. A screw-retained prototypes prosthesis fabricated on the reference master cast following the Pro-Arch concept. The double digital scanning (DDS) technique was used to generate two STL files, then merged with the aid of CAD software into one master STL file. The master STL file was used to print digitally fabricated prototypes from 2 different printers (Form 3b+ and Carbon M2). Accuracy was evaluated in two methods: Radiographic assessment Radiographs were taken for each prototype to assess the accuracy of fit on each screw-retained abutment. Prior to taking each radiograph, the prototype was torqued to 15 Ncm to simulate the clinical scenario. Laboratory Analysis; Accuracy of Fit Assessment The accuracy of fit of the digitally generated prototype prostheses on the reference cast was tested. Two blinded clinicians tested the accuracy of the fit of the prosthesis on all prototypes using the screw-resistance test. Results: Out of the 62 digitally fabricated prototypes, 51 (82.26%) presented with accurate fit. The accuracy of fit ranged from 80.65% (25/31) for carbon m2 printer to 83.87% (26/31) for the form 3b lab printer. Conclusion: Digitally fabricated prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit while reducing the number of appointments and treatment time.