The aim of this in vitro study was to evaluate the cytotoxic effects of the vasoconstrictor experimental gingival retraction agents (VEGRAs) in a dynamic setting. The strong cytotoxic effects of the astringent-based conventional gingival retraction agents (ACGRAs) on human gingival fibroblasts (HGFs) in vitro was our motivation to evaluate the biocompatibility of the vasoconstrictor-based experimental gingival retraction agents (VEGRAs) for the selected minimally invasive chemical agent. These agents were used to create three self-made retraction gels. Human gingival fibroblasts (HGFs) were treated with two groups of retraction agents: 1) three α- and β-adrenergic agents (VEGRA-αβ-s) based on 0.1%, 0.01% and 0.05% HCl-epinephrine, and 2) seven α-adrenergic agents (VEGRA-α-s), including two commercially available 0.05% HCl-tetrahydrozoline solutions, one 0.05% HCl-oxymetazoline solution, 10% HCl-phenylephrine solution, and three new self-made experimental 0.05% HCl-tetrahydro zoline-based gels. The methyl thiazolyl tetrazolium (MTT) colorimetric assay was performed to determine the oxidoreductive mitochondrial function after 3, 5, 10 min and 24 h of incubation. The cytotoxic effect, measured by cell viability lower than the 50% threshold, was not observed at any time period, even 24 h after application of 0.05% HCl-tetrahydrozolinebased self-manufactured retraction gels. High cell viability values of human gingival fibroblasts after the treatment with the three self-made 0.05% HCl-tetrahydrozoline- based gels may serve as a basis for further studies aimed at selecting the best retraction agents biocompatible with gingival margin tissues.

Department of Dental Materials Wroclaw Medical University Wroclaw Poland

Evaluating the Translucency, Surface Roughness, and Cytotoxicity of a PMMA Acrylic Denture Base Reinforced with Bioactive Glasses