Comparison of subcutaneous inflammatory response induced by elastomeric orthodontic ligatures coated with silver and zinc oxide nanoparticles with control group on rats

Abstract

Background: Silver and zinc oxide (ZnO) nanoparticles have recently become common to coat
ligatures in order to take advantage of positive properties of nanoparticles, although there are
concerns about their cytotoxicity. This study tended to compare subcutaneous inflammatory
response induced by elastomeric orthodontic ligatures coated with silver and ZnO nanoparticles
with a control group in rats.
Materials and Methods: In this in vitro and animal cross‑sectional descriptive‑analytical study, silver
nanoparticles were synthesized by chemical reduction of silver nitrate solution in the presence of
sodium borohydride and ZnO nanoparticles by the same method and by chemical reduction of zinc
sulfate solution with sodium hydroxide and were coated on elastomeric ligatures. Subcutaneous
inflammation degrees were assessed after 15 and 30 days and were compared in the groups by
Kruskal–Wallis test and ordinal generalized estimation equation with exchangeable correlation
matrix. All tests were performed with a significance level (P = 0.05).
Results: There was a significant difference in terms of degrees of inflammation in the groups
coated with ZnO nanoparticles (P = 0.003) and silver nanoparticles (P = 0.04) compared to the
control group in 15‑ and 30‑day samples. Zinc nanoparticles caused 3.22 times more inflammation
than silver nanoparticles (P = 0.053). The decrease in inflammation was significant over time in all
groups (P = 0.001).
Conclusion: There was a significant more inflammation in the groups receiving ZnO and silver
nanoparticles compared to the control group in 15‑ and 30‑day samples. Silver nanoparticles are
probably safer than zinc nanoparticles for tissue and a better material to choose for antibacterial effects.
Key Words: Elastomeric ligatures, silver nanoparticles, subcutaneous inflammation, zinc oxide
nanoparticles