Three Dimensional Printed Surgical Guides: Effect of Time on Dimensional Stability

Abstract Purpose To analyze, in vitro, the dimensional stability over time of 3D‐printed surgical guides. Materials and methods Ten surgical guides, manufactured by digital light processing 3D‐printing technology, were scanned immediately after post‐processing and then after 5, 10, 15, and 20 days. The corresponding standard tessellation language (STL) files were used for comparison with the reference CAD project. Mean absolute deviation (MAD) of the intaglio surface, axial, and linear deviations of the sleeves’ housings were measured. Generalized estimated equations models (α = 0.05) were used to investigate the effect of time. Results MAD of the teeth intaglio surface showed less variation (minimum: 0.002, maximum: 0.014 mm) than that of the mucosa (minimum: 0.026, maximum: 0.074 mm). Axial variations of the sleeves’ housings on the sagittal (minimum: –0.008°, maximum: –0.577°) and frontal plane (minimum: –0.193°, maximum: 0.525°) changed with similar patterns, but opposite trends (decreasing for the former). Linear deviations of center points of the sleeves’ housings had a shifting (minimum: –0.074, maximum: 0.02 mm) pattern with a decreasing tendency. Time after processing had a significant effect, either alone or nested with guides volume, on all outcomes of interest, except for MAD of the mucosa intaglio surface ( p < 0.001), which was significantly affected only by the time‐volume nested effect ( p = 0.012). Conclusions Within the limitations of the experimental design, postmanufacturing dimensional variations of surgical guides were statistically significant. Although limited, they are an additional source of variability affecting the overall accuracy of computer‐guided surgery. As such, they should be addressed by further research.