Rhode Island Cancer and Oral Health Resource Guide

Medication-Related Osteonecrosis of the Jaw (MRONJ) and Osteoradionecrosis (ORN)

Provider Information

Exposed bone

   Conditions leading to exposed bone following cancer treatment are rare. They fall under two categories: medication-related osteonecrosis of the jaw, typically referred to as MRONJ, which can be related to use of high levels of a class of drugs called bisphosphonates, and osteoradionecrosis, typically referred to as ORN, which can be related to radiation therapy to the jaw bones.

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Description of MRONJ

   MRONJ is a rare but potentially serious disorder that can affect either the upper or lower jaw bones.  It is characterized by progressive death of the cells of the jaw.  “Exposed bone or bone that can be probed through an intraoral or extraoral fistula(e) in the maxillofacial region that has persisted for more than eight weeks.”  The process of cell death happens in the absence of any previous radiation, and in people who have taken either bisphosphonates, denosumab, or Romosozumab for osteoporosis or cancer.  These drugs inhibit the ability of osteoclasts to remodel the alveolar bone.  

  MRONJ usually presents as persistent exposed bone of the jaw after a tooth extraction or other trauma to the mouth.  The symptoms can range from mild to severe.  Mild might include inflammation of the gums in the setting of exposed bone.  More severe symptoms might include facial swelling, loose teeth, paresthesia, and even jaw fracture. 

    Patients that will be taking these drugs in the future should undergo a thorough dental exam and any necessary prophylactic treatment.  Patients already on bisphosphonates who are undergoing oral surgery may require additional consultation with their oncologist prior to surgical procedures (depending on their risk factors for MRONJ).  

    If a patient develops MRONJ, this is usually treated based on the severity of the disease.  Treatment for mild cases will include non surgical management with antimicrobial mouthwashes and oral antibiotics.  Moderate to severe cases will include sequestrectomy and in very rare cases; resection and reconstruction.  
One of the most important factors in the prevention of MRONJ is good at-home oral hygiene and regular dental exams and care.  This will help prevent the need for oral surgery which will reduce the risk of MRONJ.  
 
Description of ORN

   ORN is a rare condition characterized by exposed, dead (necrotic) bone of the jaws in patients who have previously received radiation to the head and neck for cancer treatment.  The radiation causes damage to the blood vessels that supply nutrients to the jaw bone, which can eventually lead to cell death.  The lower jaw is more frequently affected due to the poor blood supply as compared to the maxilla, but the maxilla can still be affected.  

   ORN can happen spontaneously, but more commonly it is a result of trauma to the jaw in a person who has received more than 60 Grays of radiation.  Trauma can be in the form of tooth extraction.  
What does ORN look like?

   ORN has a similar appearance to MRONJ and usually presents as persistently exposed bone of the jaw after a tooth extraction or other trauma to the mouth but is occasionally spontaneous.  The main difference is that patients with ORN have a history of being exposed to radiation to the head and neck.

Prevention of ORN

   Similarly to the prevention of MRONJ, the best prevention strategy is the management of dental conditions prior to radiation therapy.  The head and neck cancer board will typically consult with a dentist familiar with treating patients with head and neck cancer.  The dentist will then provide all necessary prophylactic dental treatment. 

   For patients who have already undergone radiation therapy to the head and neck, excellent home oral hygiene, and regular in-office hygiene care are extremely important to help prevent the need for invasive dental procedures.  Dry mouth (xerostomia) can also be caused by radiation.  Dry mouth can lead to more cavities, therefore the treating dentist can provide recommendations for saliva replacement therapy.  Fluoride can also play an important role in preventing cavities.  

Management of ORN

   ORN is usually grouped into 3 categories depending on the severity of the disease.  The grading and severity guide treatment modalities.  In more mild forms of the disease, management with antibiotic rinses, and oral antibiotics may be used with surgical debridement of necrotic bone.  In more severe forms, more invasive surgery is typically required to remove the dead bone, and in some cases, to reconstruct any post-surgical defects.  

   HBO (Hyperbaric oxygen) is a controversial treatment.  Some institutions use this as an adjunctive treatment to improve oxygen delivery to the necrotic area.  The efficacy of this has not been proven in clinical trials.

Grade                Description
I                          Soft tissue died, exposing the bone underneath it.
II                         Osteoradionecrosis that has not responded to treatment.
III                        Osteoradionecrosis affects the whole thickness of the bone, has caused a fracture or both.

For more information about MRONJ, ORN, and oral health, see these resources:
JOMS Info for Patients: MRONJ.  2021
https://cancer.ca/en/treatments/side-effects/osteoradionecrosis
American Association of Oral and Maxillofacial Surgeons’ Position Paper on Medication-Related Osteonecrosis of the Jaws—2022 Update