Histopathological safety evaluation of polyethylene glycol applied subcutaneously in mice

Polyethylene glycol is used as a non-aqueous solvent for a variety of medical agents. We believe it could also be used as a base component in root canal filling material and aimed to test the histological safety of subcutaneously injected polyethylene glycol. We injected polyethylene glycol subcutaneously into the dorsal area of 30 6-week-old anaesthetized male ddY mice. An equal number of mice were injected with propylene glycol as controls. One week, 3 weeks and 9 weeks after injection, the tissue surrounding the injection site was removed from 10 mice in each group and examined. We found no histopathological changes, degeneration, necrosis, foreign body reactions or granulation tissue proliferation in either group. Some inflammatory cell infiltration was observed in both groups. Based on these results, we believe that polyethylene glycol could be used safely as a base component of biomaterials for internal medical use, such as in root canal filling material.