Accuracy Of 3D-Printed And Milled CAD/CAM Models

Objectives: The objective of this in-vitro study was to compare the three-dimensional accuracy of a CAD simplified geometrical model fabricated by three different 3D printers and one milling machine.
Methods: A simplified CAD model (15 × 20 × 10 mm) was designed with 3D software. Twenty samples (total n= 100) were fabricated with each of the three 3D printers (2 enginering printers: ProJet6000 and Fortus450mc and one dental laboratory printer: FormLab2) and one milling machine (Zirkonzahn M1) with their respective resin materials approved for dental use (2 materials were used with the dental laboratory printer). The printed and milled specimens were then scanned and digitized with a laboratory scanner. Each respective .STL file was superimposed on the original CAD file for three-dimensional linear analysis and comparisons using the same software. One Way ANOVA on Ranks followed by Tukey test was used for statistical analyses and comparing the printing and milling machines in three different dimensions (x, y and z).
Results: The milled models were not statistically significantly different from the control (CAD model) in any of the three dimensions (x- 14.99±0.04, y- 20.00±0.05, x- 9.96±0.02) (p<0.05). All other printed groups were significantly different from the control in all dimensions except from Fortus450mc that was not statistically significantly different from the control in x-dimension (14.99±0.02)) and FormLab2 that was not different in z-dimension (10.02±0.08).
Conclusions: The milling machine is dimensionally more accurate than the 3D printers used in this study for the fabrication of a CAD model. Engineering printers are more accurate than a dental laboratory printer.