What is this osteoradionecrosis that hangs over the heads of some patients who’ve had radiotherapy?

I know osteo means bone and radio refers to radiotherapy and necrosis refers to dead tissue so ORN is death of bone due to radiotherapy.

Here is a definition of necrosis.”the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.”

"ORN is most commonly defined as exposed, irradiated, nonhealing bone of at least 2 to 3 months duration without evidence of tumor recurrence."

Don’t freak out though because although it is something to watch out for, it is rare. It affects sections of bone that can be removed if necessary. It’s hard to treat but there are options.

"Osteoradionecrosis is a rare side effect that develops some time after radiation therapy has ended. It usually occurs in the lower jaw, or mandible. The lower jaw is at risk of osteoradionecrosis because it has a limited blood supply. Very rarely, osteoradionecrosis can start in the upper jaw, or maxilla."

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Some of our people have had it and with my poor bottom teeth I am at risk. I stress however, that only a small percentage of radiotherapy patients get the condition. Careful treatment can prevent it.

In this blog post I want to explore it and describe it in layman’s terms, using the information from the Canadian Cancer Society website, the Oral Cancer Foundation website and a few others listed below with some of my own experience thrown in for good measure.

A first sign can be exposed bone as in the picture above from the OCF website.

ORN can happen spontaneously but mostly it is caused by trauma to the jaw that does not heal - that trauma is mostly caused by a tooth extraction. This is why patients are given Hyperbaric Oxygen Therapy before and after some extractions because HBO forces oxygen into the tissue and make the blood flow better.

Does HBO work once the bone is necrotic? I have not been able to find a definitive answer to this question but it looks as if it can in the earlier stages. 

What leads to some people getting this condition? Basically it is caused by the amount of radiation as well as some other factors. There's more of a risk if you had over 60 "grays" of radiation.  I have had only 42 grays (at the most) to the area of the mandible where the lower front teeth are on their last legs. Therefore I won’t need HBO for an extraction but there will still be a small risk.

(I wasn’t aware of how many grays I had been delivered until I came to the support group and heard people talking about it. I still had my appointment card and saw, yes, I had had 60 grays in the area where my tumour was.)

My dentist at Greenlane had to ring the radiation oncologist at ACH to find out how many grays were delivered outside the main field though. Patients are not generally given for their map of radiation. It would be nice to have.

Symptoms of osteoradionecrosis (from Canadian Cancer Society)

Symptoms can vary depending on the grade or extent of the osteoradionecrosis and include:

  • pain
  • swelling
  • a sore ... on the jaw
  • difficulty opening the jaw, or trismus
  • an abnormal opening, or fistula, between the jaw and the surface of the body
  • less feeling in the mouth or jaw, or even a complete loss of sensation in the area
  • infection
  • teeth that aren’t aligned properly, which is called malocclusion
  • jaw fracture not related to an accident or other trauma
  • exposed bone inside the mouth
  • bone sticking out through the skin, which is called sequestrum

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Treatment of osteoradionecrosis

Once the extent of osteoradionecrosis is known, your healthcare team can suggest ways to treat it. You will also be given antibiotics if there is an infection in the bone. Other treatment options may include the following measures.


Your doctor may need to do surgical debridement. This means removing dead or infected tissue from around a wound. Dead, or necrotic, bone may also need to be removed. This is called sequestrectomy.

Depending on where osteoradionecrosis develops and how far it progresses, your doctor may need to do surgery to help restore the area.

This may include microvascular reconstructive surgery to restore blood flow to the area.

Bone grafts may be needed to replace the sections of the jawbone that are removed. (I have also heard that titanium can be used.)

Hyperbaric oxygen therapy

Hyperbaric oxygen therapy involves breathing pure oxygen in a pressurized room. It is done in a special chamber where the pressure inside is higher than the normal pressure of the atmosphere. The higher pressure allows more oxygen to get into your blood, which can help heal damaged and infected tissues.

Hyperbaric oxygen therapy is used in combination with wound care and surgery. The treatment plan often includes 20 treatments before surgery and 10 more treatments after surgery. This treatment plan may be adjusted based on your personal situation and how well the osteoradionecrosis responds to the hyperbaric oxygen therapy.

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Prevention is better than cure

How can we lessen the chance of ORN occurring?

  • Extraction of potentially troublesome teeth prior to treatment
  • Good oral hygiene. See a hygienist if possible
  • Regular dental checkups
  • Good nutrition
  • No extractions without contact with radiation oncologist about need for HBO
  • Smoking cessation, limiting alcohol

As we know, prevention isn't always possible after radiation therapy. But after researching ORN, I am certainly going to take even better care of my mouth. 

Off to clean my teeth ...


  • The "gray" is a unit of radiation. Most of us had 60 grays over 6 weeks. Adjacent areas like my bottom front teeth, receive less. 
  • The risk of developing osteoradionecrosis increases when the dose of radiation received is greater than 60 grays. It is also higher if the bone treated with radiation is exposed.
  • ORN is not an infection in itself but can become infected. 

The following extract from the OCF page is too well-explained not to append here. 

Osteoradionecrosis develops as irradiation diminishes the bone’s ability to withstand trauma and avoid infection, and it can be facilitated by poor nutrition and hygiene. This process may be spontaneous or result from trauma, leading to non-healing soft tissue and bone lesions, followed by bone necrosis. The non-healing bone may become secondarily infected. All patients who are to receive chemo-radiation therapy should have unsalvageable teeth removed, periodontal health maximized, and fluoride therapy instituted prior to treatment. Osteoradionecrosis is an extremely serious complication for patients requiring tooth extraction after radiation therapy, and the risk does not appear to diminish with time (for the rest of his/her life the patient should never allow a dentist to extract a tooth after radiation therapy without consulting a radiation oncologist). The ability of the bony tissues to heal is compromised by hypovascularization.

Hypo = low, and vascular = relating to blood vessels so hypovascularisation (English s instead of American z) means lower than usual number of blood vessels - not enough blood supply. 


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