Bone is 1.6 to 1.8 times denser than soft tissue and therefore absorbs a larger amount of radiation than soft tissue. Radiation damages the blood vessels around and through the bone tissue, resulting in bone death. Radiation also interrupts the relationship between osteoclastic destruction and osteoblastic construction of bone tissue. Death of both of these types of bone cells leads to osteoporosis and osteonecrosis (bone death).
Bone death can occur between four months and three years of radiation-induced bone damage. There is no satisfactory treatment for this condition. Beginning in 1979, Dr. Robert Marx and other researchers demonstrated that osteoradionecrosis is a wound healing defect related to a chronic hypoxic state. In 1984, Marx published a study of 150 cases of osteoradionecrosis in the mandible. His HBOT treatment protocols became the standard for planning both the treatment of bone and soft tissue damage.
The 1990 Consensus Paper of the National Cancer Institute on the Oral Complications of Cancer Therapies states, “The treatment of ORN with antibiotics and surgical debridement frequently fails, with progressive involvement of the remaining mandible. The keystone of the treatment of ORN is the provision of adequate tissue oxygenation in the damaged bone. This is best done by using HBOT. In the event that dental extractions are required following radiation, meticulous surgical technique and antibiotic prophylaxis are necessary.”
The most common sites are where radiation has been given: the mandible (lower jawbone), the ribs and breastbone (usually following radiation for breast cancer), and the spinal column. The mandible is denser than the other facial bones and so absorbs more radiation. It also has less blood supply than many other bones. Damage to the mandible is the most commonly reported instance of radiation damage to bone. The mandible is often involved because head and neck cancers are common and radiation therapy in these cancers is very effective.
Most cases of mandibular osteoradionecrosis originate from tooth extraction after development of radiation caries. The trauma of tooth extraction causes a breakdown of gum tissue and subsequent progressive bone necrosis. Healing tissue cannot form a bridge over the dead bone, and the infection continues. The resolution rate is only about 8 % without the use of HBOT.
Antibiotics have been used for this condition but they are not particularly effective. It is now generally thought that infection does not play an important role. Hart and Strauss reported on the role of HBOT in radiation induced jaw damage. Out of 206 patients who received HBOT as an adjunct treatment, 72 % responded with excellent results, 10 % with good results and 15 % with fair results.56
At the University of Miami, Dr. Marx developed a treatment plan for radiation-induced bone damage. The first stage includes daily 90-minute HBOT at 2.4 ATA for 30 days. If there is improvement 10 more sessions are given. If there is no improvement, in the next stage dead tissue is removed to determine if and how much surgery is needed. Ten further HBOT treatments are given. If the patient doesn’t respond then surgery is done after 30 more treatments and then 10 more are given after the surgery. Dr. Marx has treated 268 patients over eight years and good results were obtained.57
Treatment of bone loss in women with bisphosphonate results in osteonecrosis of the jaw, which has been approved for HBOT. See recent research at Duke University.58