Introduction: The success of endodontic treatment is related to the cleaning and elimination of microorganisms and their by-products present in root canals for periapical tissue repair. Objective: To verify the efficacy of ozone (O3) as an adjunct in the therapeutic protocol of Endodontics, aiming to assist in tissue repair of periapic lesions. Methods: This is a literature review, in which scientific articles were researched, from the last 10 years, using the databases of pubmed, scielo, vhl and EBSCOhost platforms, and applying the keywords: "Ozone", "Dentistry", "Endodontics" and "Complementary therapy". Results and Discussion: The applicability of O3 is directly dependent on the performance of the well-executed endodontic treatment, to determine the best way of presenting it, increasing its effectiveness. However, during the preparation of the conduits, ozone can be used in the form of gas, being used within them, with antimicrobial purpose, highlighting the oxidative property that allows better distribution of blood flow to the tissues involved, allowing the acceleration of healing in periapic and periodontal tissues in order to stimulate tissue repair. Ozonized water can be used within the root canal, assisting in disinfection of the conduits; and ozonized oil as an intracanal dressing, both of which can be used alone or together. Conclusion: Ozone therapy is an aggregator in endodontic therapy, since it has three forms of use and several important properties to be added to the treatment, highlighting its gaseous form for assisting in the acceleration of the healing of tissue and bone repair of periapic lesions.