Accuracy of different 3D printers for a digital model impression.

Objectives: The use of 3d printer to obtain digital models is getting more popular in the dental practice. These models are replacing the conventional poured stone casts. The objective of this research is to evaluate the accuracy of 3D models generated using intraoral scanner and printed with different 3D printers.
Methods: Digital impression of a half arch was obtained with an intraoral scanner (Trios, 3shape). Digital stereolithographic (STL) data were obtained from the 3shape software and 3D models were printed on 5 different 3D printers (n=5), with two different technologies: stereolithography (SLA) and digital light processing (DLP). The models printed using Form2 (Form Labs), Zenith D (Zenith), Moonray (Sprint Ray), Wanhao D7 Duplicator (Wanhao) and Straumann Cares P20 (Straumann) were scanned using a desktop scanner (D2000, 3Shape), and saved in .stl format. All STL records were superimposed and compared for precision (compared all different printed models from the same printer) and trueness (compared the printed models to the master model) using software Geomagic Control 2015 to evaluate the accuracy of each printer. The data were collected and submitted to statistical analyses ANOVA followed by tukey test (α=0.05).
Results: Precision for all printed models showed no statistically significant difference. The results showed that the Form2 - 30 µm (p<0.001) and P20 - 50µm (p<0.001) printers presented better results in trueness than Moonray - 70 µm (p<0.001), D7 Duplicator - 70 µm (p<0.001) and Zenith D - 70 µm (p<0.001).
Conclusions: In the present study all the 3d printers presented very little distortion varying from 30 to 70 µm compared to the original .stl file.