Antibacterial activity and biocompability of zinc oxide and graphite particles as endodontic materials

Abstract

The aim of this work is to evaluate the antibacterial effect and biocompatibility of zinc oxide (ZnO) nanopaticles and graphite-type carbon (Gt) microparticles commercial powders. SEM analysis was performed to assess particles morphology. The antibacterial behavior was studied against Staphylococcus aureus (Staph. Aureus) (bacterial strain ATCC 29213) and TEM analysis of bacteria was performed to determine ultrastructural alterations; in addition, biocompatibility was evaluated in subcutaneous tissue of Wistar rats at 3, 7 and 28 d. ZnO and Gt powders exhibited antibacterial activity while TEM images of Staph. aureus showed membrane disruption followed by the release of internal content. Also, an electron-light region within the cytoplasm was observed for microorganisms treated with ZnO. Regarding biocompatibility, Gt samples induced a foreign body reaction response with presence of giant cells whereas ZnO samples showed fibroblastic connective tissue with chronic inflammatory cells and new small vessels. Also, collagen fibers and lack of capsule was observed by Trichome Masson stain. Thus, ZnO improved wound healing by enhancing tissue regeneration in contrast with calcium hydroxide control sample response which showed a fibrous tissue scar. Hence, ZnO nano-powder seems to be a potential material in the regenerative endodontic field.