Impact of exposure to commonly used carbamide peroxide on dental pulp stem cells

Background: This study investigated the contact between adult dental pulp stem cells (DPSCs) and carbamide peroxide (CP), a bleaching agent that is a popular choice for at-home whitening products, using an in vitro model. Objectives: The aim of this study was to evaluate the impact of exposure to different concentrations and timings of a commonly used peroxide-based home tooth-whitening product on DPSCs. Materials and methods: Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of carbamide peroxide (0.1%, 0.5%, and 1%). The effects of CP on DPSC proliferation and apoptosis were investigated by MTT assay and flow cytometry. Migration was investigated by micrographs of wound healing. An enzyme-linked immunosorbent assay (IL-6 and IL-8) was used to investigate the CP-stimulated cytokine production of DPSCs. Each experiment was performed three times with independent batches of DPSCs. Statistical analysis of the collected data was performed using one-way and twoway ANOVAs with the significance threshold set at p < 0.05. Tukey’s post hoc multiple comparison test was used to identify differences between groups. Results: Cell viability and adherence were lower in the CP-exposed cells compared to the non-stimulated cells, probably due to increased cell death (** p ≤ 0.01, **** p ≤ 0.0001). CP-stimulated DPSCs exhibited a dose-dependent release of IL-6 and IL-8 (**** p ≤ 0.0001). CP did not affect wound healing at any concentration tested. Conclusions: Human DPSCs were able to sense CP. Consequently, CP contributed significantly to cell apoptosis and local inflammatory responses through cytokine release.