Human Gingival Fibroblast Response To Additively Manufactured Zirconia

To evaluate the biological responses of human gingival fibroblasts (HGFs) to zirconia fabricated through three additive manufacturing (AM) technologies - stereolithography (SLA), digital light processing (DLP), and material jetting (MJ) - with horizontal (0°) and vertical (90°) build orientations, in comparison with conventional subtractive manufacturing (SM) control. Square zirconia specimens (8 mm × 8 mm × 0.8 mm) were fabricated using SLA, DLP, and MJ technologies (0° and 90° orientations), and SM. Surface properties were analyzed via field-emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurement, and protein adsorption quantification. HGFs responses were evaluated, including cell cytotoxicity, viability, proliferation, morphology, adhesion, and migration. The differences in gene expression patterns of HGFs on MJ90, DLP90, and SM surfaces were investigated by ribonucleic acid sequencing (RNA-Seq) analysis. All AM-fabricated zirconia demonstrated good biocompatibility. Vertically oriented MJ90 and DLP90 specimens displayed anisotropic surface textures with lamellae or parallel bands, which aligned HGFs along a uniform direction. HGFs on MJ90 surfaces demonstrated the fastest directional migration, followed by DLP90. MJ90 also exhibited the highest cell adhesion density. RNA-Seq revealed up-regulated expression of soft-tissue-related genes in MJ90 and DLP90 compared to SM control, in which larger numbers of genes in MJ90 were identified than in DLP90. AM zirconia induced favorable HGF responses (≥SM controls), with MJ/DLP vertical orientations creating anisotropic surfaces that enhanced fibroblast alignment, adhesion, migration, potentially improving dental prosthesis soft-tissue integration.