Cytotoxic Effects of Milled, 3D-Printed, and Conventional Methacrylate-Based Resins After Exposure to Denture Cleansers: A Preliminary In Vitro Screening Study

This study evaluated cellular responses to extracts of CAD/CAM-milled PMMA, 3D-printed methacrylate-based resin, and conventionally heat-polymerized PMMA after denture cleanser exposure. Specimens (MTT, n = 240; BrdU, n = 36) were assigned to Corega, chlorhexidine, Listerine, or distilled water. Following accelerated cumulative exposure (1825 min; not simulating clinical use), extracts were applied to human gingival fibroblasts. Cellular metabolic activity was assessed by MTT absorbance, DNA synthesis-associated proliferative activity by quantitative BrdU immunofluorescence, and morphology and F-actin organization qualitatively. Material and cleansing solution significantly affected MTT absorbance (both p < 0.001), with a significant interaction (p = 0.008). CAD/CAM-milled and 3D-printed materials exhibited higher MTT absorbance than conventional PMMA (p < 0.001 and p = 0.003, respectively), without a significant difference between them (p = 0.071). Distilled water yielded higher MTT absorbance than all cleansers (all p < 0.001). BrdU labeling showed a significant cleansing solution effect (p < 0.001) but no significant material effect or interaction. In this preliminary screening study, cleansing solution affected both metabolic and DNA synthesis-associated responses, whereas material differences were significant only for MTT absorbance. Mechanisms were not investigated; the milled material (TEMPO-CAD) is not primarily a denture base material, so findings should not be generalized.