Statement of problem: The layer thickness serves as a straightforward and controllable parameter to alter the mechanical properties of 3D-printed custom trays. However, how the printing layer thickness affects the mechanical properties of the trays is not fully understood.
Purpose: The purpose of this in vitro study was to investigate the effects and their underlying mechanisms and to optimize the mechanical properties through modulation of the printing layer thickness.
Material and methods: Polylactic acid (PLA) specimens were 3D-printed with 5 layer thicknesses from 0.1 mm to 0.5 mm. The bond, flexural, and tensile strengths were measured by using a universal test machine. Postfracture interfaces were examined by means of scanning electron microscopy. Additionally, the printing dimensional accuracy was estimated by measuring the size deviations between the printed and virtual specimens, and the printing times were recorded.
Results: With increasing PLA printing layer thickness, the tensile bond strength first increased and then decreased, peaking at a thickness of 0.4 mm. While the flexural and tensile strengths decreased, the printing dimensional accuracy remained constant from 0.1 mm to 0.4 mm and then decreased at 0.5 mm. The printing time sharply decreased as printing layer thickness increased.
Conclusions: Moderate layer thickness provided the best properties for 3D-printed custom trays.
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