N-Acetylcysteine Modulates The Effects Of Composites On Human Gingival Keratinocytes

Objective. The aim of this study was to evaluate, if antioxidants, like N-Acetylcysteine, can modulate effects of composite eluates on human gingival keratinocytes.Methods. Composite samples of ceram.x (R) universal, Filtek (TM) Supreme XTE, and Admira (R) Fusion were stored 72 h in cell culture medium to prepare eluates, according to ISO 10993-12:2012. Human gingival keratinocytes were exposed to these eluates with or without 3 mM N-Acetylcysteine. Following cell observation by iCELLigence (R), exposure periods were deter-mined at 1d and 4d. Cell morphological analysis combined with live/dead staining was performed. Tissue-specific biomarkers of terminal differentiation, Involucrin and Filaggrin, were analyzed by indirect immunofluorescence (IIF) and Western blot (WB). qPCR profiling was performed on genes encoding for: inflammation, apoptosis, turn-over of extracellular matrix, adhesion, proliferation and differentiation. For statistical analysis one-way Anova was used (p < 0.05).Results. Cells exposed to N-Acetylcysteine exhibited morphological changes but no cell death. After adding 3 mM N-Acetylcysteine to HGK cultures, increased fluorescence intensity and protein amounts of Involucrin and Filaggrin indicated enhanced differentiation (p < 0.05). Gene expression was modulated by: (i) composition of the composite eluates, (ii) NAC and (iii) exposure time. Filtek (TM) Supreme XTE showed a significant increased gene expression in inflammatory genes (p < 0.05), which was amplified by the addition of NAC at 1d. Concerning exposure time, modulated gene expression showed eluate dependency, substantiated by Filtek (TM) Supreme XTE modulation at day 1 and Admira (R) Fusion at day 4.Significance. N-Acetylcysteine-emerging effects on gingival keratinocytes were threefold: (i) increase of differentiation, (ii) modulation of composite-related effects and (iii) in parts counteraction of eluate-induced effects. (C) 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.