3D-Printed Models Dimensional Accuracy: a Function of Printing Angulation

Objectives: 3D-printing technology allows clinicians to fabricate models for various purposes. During the printing process, varying printing angles could alter model accuracy. This study compared linear dimensions across diagnostic models printed at different angles. We hypothesized that varying print angulation affects models’ dimensional accuracy.
Methods: A stereolithography (STL) file of a standardized maxillary arch was created following a modification of ISO-WD-20896-1. The file was printed at six different angulations 15^o , 30^o , 45^o , 60^o , 75^o , 90^o (n=10/angulation), and compared to a 0^o 3D-printed group (control). Measurements (a-b, b-c, c-d, a-d, a-c, b-d) were obtained by a trained investigator. Six linear measurements (Figure 1) across 10 3D-printed models were assessed for agreement with Kruskal-Wallis Test. One sample t-test was used to assess agreement between the reference 0^o STL-file and measurements taken with different angulations for each linear measurement.
Results: Linear measurements of each print did not differ across the 10 prints (p=.437). For the a-b linear measurement, significant differences were found between 0^o (32.30±0.1) and 45^o (32.14±0.9, p<.001). No significant differences were observed between the b-c linear measurements taken at different angulations. For the c-d linear measurement, significant differences were found between 0^o (32.29±0.1), 15^o (32.37±0.1, p=.004) and 75^o (32.42±0.1, p=.007). The a-d linear measurement showed significant differences between 0^o (32.93±0.1) and 15^o (32.86±0.1, p=.013), 30^o (32.67±0.1, p<.001), 45^o (32.64±0.1, p<.001), and 60^o (32.73±0.1, p<.001). For the a-c linear measurement, significant differences were found between 0^o (41.00±0.1), 30^o (40.91±0.1, p=.001), 45^o (40.81±0.1, p<.001), 60^o (40.94±0.1, p=.026). For the b-d linear measurement, significant differences were found between 0^o (40.98±0.1) and 45^o (40.85±0.1, p=.004).
Conclusions: Within the limitations of the study, the most accurate printing angulation compared to the 0^o group was the 90^o group, whereas the least accurate was the 45^o group. The linear measurement b-c was the most accurate among all groups.