Precision and trueness of maxillary crowded models produced by 2 vat photopolymerization 3-dimensional printing techniques

Abstract

This cross-sectional study aimed to analyze the precision and trueness of dental models produced using 2 rapid prototyping 3-dimensional printers. A digital crowded maxillary arch with a T-shaped base and 2 hemispheres of 2.5mm radius was printed 10 times with a stereolithography apparatus (SLA) and digital light processing (DLP) in the highest precision and minimum layer thickness (z-resolution) mode. The copies were scanned using the D710 3Shape desktop scanner and assessed for precision and trueness via arch superimpositions and hemisphere measurements. Mann-Whitney U tests were used to compare trueness and precision among printers. Hemisphere radius was compared with the reference measurement and between 3-dimensional printers using 1 sample and independent Student t tests, respectively (α=0.05). The root mean square values of arch superimpositions showed statistically significant differences between the 2 techniques, both for precision (P=0.011): SLA (46.8μm±13.5); DLP (111.1μm±71.9), and trueness (P=0.015): SLA (61.1μm±9.8); DLP (99.8μm±47.2). The color map model analysis indicated greater distortion on premolar and molar surfaces, with a higher range of contraction on the SLA and both contraction and expansion on the DLP. Anterior and posterior hemisphere radius registered increased values with DLP (1.7% and 0.49%) and reduced values with SLA (0.6% and 0.7%); however, only the anterior SLA hemispheres revealed a significant decrease from the reference value (P=0.037). In this study, the SLA printer was significantly different from the DLS printer, with the highest precision and trueness.