Examination of the changes that non-toxic doses of antioxidant action ozone used in increasing osteogenic activity by dentists causes on rat liver tissues. The effects of ozone applications that are significant in mandibular bone defect therapies and oral and maxillofacial surgery practice on oxidant / antioxidant system in rat liver tissues are investigated by analyzing malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) parameters. While there were statistically significant reductions in MDA levels and SOD activities after 15 and 45 days long ozone applications on critical mandibular bone defect induced rat livers, statistically significant increases were observed in GSH levels and CAT activities (P <= 0.05). This is the first study where the effects of ozone therapies used in treatment of mandibular bone defect on liver tissue oxidant / antioxidant system in rats are scrutinized with the analysis of biochemical parameters. It was determined that ozone applications did not have any negative effects on liver tissue oxidant / antioxidant system and concurrently had positive effects on liver antioxidant system and to reveal the biochemical mechanism completely, further studies are needed.