A prospective randomized trial comparing hyperbaric oxygen and systemic antibiotics in the prevention of osteoradionecrosis was presented. The results indicated, in a high-risk population who required tooth removal in irradiated mandibles, that up-front hyperbaric oxygen produced an incidence of osteoradionecrosis of 5.4% as compared with the antibiotic group of 29.9% (P = .005). Hyperbaric oxygen should be considered a prophylactic measure when post-irradiation dental care involving trauma to tissue is necessary.