# Size-Dependent Bioactivity of Silver Nanoparticles and Calcium Hydroxide Mixtures Against hDPSCs: An In Vitro Study

## TL;DR

This study shows that 10 nm silver nanoparticle mixtures and calcium hydroxide are most effective for promoting dental stem cell health and mineralization.

## Contribution

The study introduces size-dependent effects of silver nanoparticle mixtures on human dental pulp stem cells.

## Key findings

- 10 nm mixtures and calcium hydroxide showed highest cell viability and lowest ROS release.
- 10 nm mixtures and calcium hydroxide increased anti-inflammatory cytokines and mineralization.
- 2 nm and 5 nm mixtures reduced cell viability and caused morphological distortion.

## Abstract

This study aimed to assess the biocompatibility and bioactivity of three different silver nanoparticles (AgNPs) and calcium hydroxide [Ca(OH)2] mixtures against human dental pulp stem cells (hDPSCs). hDPSCs were treated with one of the following medicaments: 2 nm mixture, 5 nm mixture, 10 nm mixture, Ca(OH)2 alone, and triple antibiotic paste (TAP). Cell viability was evaluated using the Cell Counting Kit-8 and LIVE/DEAD Viability/Cytotoxicity Kit. Reactive oxygen species (ROS) were quantified using the 2′,7′-dichlorofluorescein diacetate redox probe. Transforming growth factor (TGF)-β1, interleukin (IL)-1β, tumor necrosis factor (TNF)-α>, and alkaline phosphatase (ALP) were quantified using enzyme-linked immunosorbent assays. Mineralization was assessed using Alizarin Red S staining. Data were compared across groups using the Kruskal–Wallis test and within groups using the Wilcoxon signed-rank test (p < 0.05). Ca(OH)2 alone and the 10 nm mixture demonstrated the highest cell viability and lowest ROS release (p < 0.05), while the 2 nm and 5 nm mixtures resulted in decreased viability and significant morphological distortion of the cells. Ca(OH)2 alone and the 10 nm mixture comparably demonstrated the highest production of anti-inflammatory cytokine TGF-β1 (p < 0.05), the lowest production of proinflammatory cytokines IL-1β and TNF-α (p < 0.05), and the highest ALP release and mineralization (p < 0.05). Within the limitations of this in vitro study, Ca(OH)2 alone and the 10 nm mixture improved hDPSCs’ viability, proliferation, differentiation, and mineralization. Both illustrated a significantly higher anti-inflammatory response by the residing stem cell population.