The effects of additive manufacturing technologies and finish line designs on the trueness and dimensional stability of 3D‐printed dies

Purpose To evaluate the effects of 5 manufacturing technologies and 2 finish line designs on the trueness and dimensional stability of 3D‐printed definitive dies at finish line regions under different storage conditions and time. Material and methods Preparation of light chamfer and round shoulder finish lines were adopted individually on two mandibular first molar typodont teeth and digitalized as standard tessellation language (STL) files. A total of 240 samples (192 AM definitive dies and 48 definitive conventional stone dies) in 20 groups (n = 12) were manufactured based on 2 finishing line designs (chamfer and shoulder), 5 manufacturing technologies (4 additively manufactured technologies and conventional stone die), and 2 storage conditions (light exposure and dark). The 4 additively manufactured (AM) technologies include a DLP 3D‐printer, an economic LED 3D‐printer, a CLIP 3D‐printer, and an SLA 3D‐printer. All the study samples were distributed into two storage conditions. Subsequently, samples were digitalized to STL files at 3 different time points (within 36 hours, 1‐month, and 3‐months). A surface matching software was used to superimpose the sample STL files onto the corresponding original STL files with the best‐fit alignment function. The trueness of each printed and stone definitive dies and their dimensional stabilities were measured by the root mean square (RMS, in mm). A linear mixed‐effects model was used to test the effects of the finish line design, manufacturing technology, storage condition, and storage time on RMS values (α = 0.05). Results While finish line designs had no significant effects [F(1, 220) = 0.85, p