Fibroblast behavior on conventionally processed, milled, and printed occlusal device materials with different surface treatments.

Statement of Problem: Occlusal devices can be either conventionally processed, milled, or printed. However, little is known about the biocompatibility of 3D printing resin materials.
Purpose: The purpose of this in vitro study was to compare the viability and morphology of human gingival fibroblast cells (HFG-1) after cultivation on conventionally processed, milled, and printed occlusal device materials with different surface treatments.
Material and Methods: Disks of a conventionally processed (PalaXpress Clear [pP]), milled (Yamahachi PMMA Clear [sY]), and 2 different printed materials (Dental LT Clear Resin [aD]; Freeprint splint [aF]) were prepared. The surfaces of the specimens were finished by using 2 different treatments (unpolished and polished with P1200-grit silicon carbide paper). HGF-1 cells were cultivated on the specimens for 24 hours, and a viability assay was performed by using polystyrene disks as a control (n=9 disks per group). Cell morphology and the topography of the specimens were examined with scanning electron microscopy (n=3 disks per group). Two-way analysis of variance was applied to determine the effect of material and surface treatment followed by the post hoc Fisher least significant difference test (α=.05).
Results: Overall, material (P<.001) and surface treatment (P<.001) significantly influenced the viability of HGF-1 cells. The viability of cells on all specimens displayed mean values between 0.85 and 1.01 compared with the control except for unpolished aD (0.00 ±0.07) and aF (0.02 ±0.05) that had only a few cells with a round shape.
Conclusions: The behavior of HGF-1 cells on conventionally processed and milled specimens was similar and not dependent on the surface treatment. Unpolished printed specimens had a cytotoxic effect. However, after polishing, cell behavior was similar to that of the conventionally processed and milled specimens.
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