Cytotoxicity effects of nanohybrid, bulk‑fill, and ormocer composites on dental pulp stem cells and human gingival fibroblast cells

Abstract

Background: Despite significant improvements in the physical and esthetic properties of modern
composite resins, there are still concerns about their biocompatibility. The aim of the current study
was to evaluate the toxicity of X‑tra fil, Grandio, and Admira Fusion composites on dental pulp
stem cells (DPSCs) and human gingival fibroblast (HGF) cells.
Materials and Methods: In this in vitro experimental study, 48 composite disks were made using
Grandio, Admira Fusion (2 mm high and 4 mm in diameter), and X‑tra fil (4 mm high and 4 mm in
diameter) composites and cured for 40 s. The composite blocks were then crushed with a sterile
mortar and dissolved in phosphate saline buffer solution. Tetrazolium salt (3-(4,5-dimethyl thiazol-2-
yl)-2,5 diphenyltetrazolium bromide (MTT_, neutral red (NR) assay, flow cytometry, and quantitative
real‑time polymerase chain reaction (RT‑PCR) tests (n = 5) were used to evaluate the toxicity of
the composites on two cell types (HGF, DPSCs). Data were analyzed using one‑way ANOVA test
followed by Newman–Keuls test. Level of significance was set at P < 0.05.
Results: According to the results of MTT test, only Grandio showed a significant cytotoxicity
in DPSCs, but in HGF cells, Grandio and X‑tra fil both showed a significant cytotoxicity. In NR
test, Grandio and X‑tra fil composites showed a significant cytotoxicity on both HGF and DPSC
cells. RT‑PCR test results on both DPSC and HGF cells indicated that bax gene expression in the
Grandio composite was significant. In this test, the nonexpression of the bcl2 gene in DPSCs was
significant in Grandio (100 and 200 μg/ml) and in X‑tra fil (200 μg/ml). All of the tests performed
in this study showed no significant toxicity of Admira fusion.
Conclusion: Admira Fusion is suitable for oral cells in terms of biocompatibility and can be used
as a suitable restorative material for deep restorations near the pulp or adjacent to the gums.
Key Words: Cells, composite resins, dental pulp, fibroblasts