Printing accuracy, mechanical properties, surface characteristics, and microbial adhesion of 3D-printed resins with various printing orientations

Statement of problem: Printing orientation is an important decision in the initial steps of additive manufacturing, affecting printing accuracy and the mechanical properties of printed products. In addition, printing orientation determines the building direction of layers and the layer-by-layer configuration forming the surface geometry.

Purpose: The purpose of this in vitro study was to evaluate the effect of printing orientation on the printing accuracy, flexural strength, surface characteristics, and microbial response of 3D-printed denture base resin.

Material and methods: Specimens were printed with denture base polymethyl methacrylate (PMMA) in 3 printing orientations (0, 45, and 90 degrees). The printing error rate, flexural strength, roughness, hydrophilicity, surface energy, and response to Candida albicans (C. albicans) were evaluated.

Results: Specimens printed at a 90-degree orientation showed the lowest error rates for length (P<.001), and those printed at a 45-degree orientation showed statistically higher error rates for thickness than those of other groups (P<.001). Flexural strength increased in order of the specimens printed at orientation degrees of 90<45<0 with statistical significance. The 45-degree oriented specimens showed higher roughness and surface energy than those of other groups (P<.001). A higher proportion of C. albicans was found in the specimens printed at orientation degrees of 90<45<0 with statistical significance.

Conclusions: Printing orientation significantly influenced the printing accuracy, flexural strength, roughness, and response to C. albicans. Therefore, the printing orientation should be carefully decided to fabricate products with appropriate properties.