Dimensional accuracy of extrusion- and photopolymerization-based 3D printers: In vitro study comparing printed casts.

STATEMENT OF PROBLEM

Reliable studies comparing the accuracy of complete-arch casts from 3D printers are scarce.

PURPOSE

The purpose of this in vitro study was to investigate the accuracy of casts printed by using various extrusion- and photopolymerization-based printers.

MATERIAL AND METHODS

A master file was sent to 5 printer manufacturers and distributors to print 37 identical casts. This file consisted of a standardized data set of a maxillary cast in standard tessellation language (STL) format comprising 5 reference points for the measurement of 3 distances that served as reference for all measurements: intermolar width (IMW), intercanine width (ICW), and dental arch length (AL). The digital measurement of the master file obtained by using a surveying software program (Convince Premium 2012) was used as the control. Two extrusion-based (M2 and Ultimaker 2+) and 3 photopolymerization-based printers (Form 2, Asiga MAX UV, and myrev140) were compared. The casts were measured by using a multisensory coordinate measuring machine (O-Inspect 422). The values were then compared with those of the master file. The Mann-Whitney U test and Levene tests were used to determine significant differences in the trueness and precision (accuracy) of the measured distances.

RESULTS

The deviations from the master file at all 3 distances for the included printers ranged between 12 μm and 240 μm (trueness), with an interquartile range (IQR) between 17 μm and 388 μm (precision). Asiga MAX UV displayed the highest accuracy, considering all the distances, and Ultimaker 2+ demonstrated comparable accuracy for shorter distances (IMW and ICW). Although myrev140 operated with high precision, it displayed high deviations from the master file. Similarly, although Form 2 exhibited high IQR, it did not deviate significantly from the master file in the longest range (AL). M2 performed consistently.

CONCLUSIONS

Both extrusion-based and photopolymerization-based printers were accurate. In general, inexpensive printers were no less accurate than more expensive ones.