What is osteoradionecrosis (ORN) of the jaw?

ORN although rare, is a significant complication of radiation therapy (RT)used to treat head and neck cancers.It is commonly recognised as irradiated bone which becomes devitalised/dead and exposed through the overlying skin or mucosa without healing for 3 months in the absence of tumour recurrence. (Fig.1)

There are several theories regarding the development (pathogenesis) of ORN. One of the earliest theory was by Meyer (1970) who suggested that ORN arises from infection after local injury to irradiated bone and this became the foundation for the use of antibiotics with surgery to treat this condition. About a decade later in 1983, Marx proposed the hypoxic-hypocellular-hypovascular theory which formed the cornerstone for the use of hyperbaric oxygen (HBO) in managing ORN. However, the results of HBO in treating established ORN were not convincing and could not be validated.

The most recent findings on the pathogenesis of ORN published in 2004 (Delanian & Lefaix) revealed the damage to bone is caused by radiation induced fibrosis. Following this, new treatment was devised involving the combined use of pentoxifylline and tocopherol (Vitamin E), acting synergistically as potent antifibrotic agent.

Risk Factors

The following risk factors are recognised and have been reported:-

Rarely, ORN can also developed spontaneously without any obvious risk factors apart from history of RT involving the head and neck region.

Clinical Presentation

The signs and symptoms vary depending on the extent of the osteoradionecrosis which include:

• Pain  
• Swelling of the jaw/face
• Difficulty opening the mouth
• Presence of opening (fistula) on skin of face
• Altered sensation in the mouth or jaw
• Oral infection
• Jaw fracture not related to an accident or other trauma (pathological fracture)
• None healing sore, or ulcer, in the soft tissue of the mouth
• Exposed bone inside the mouth
• Dead bone sticking out through the oral mucosa
  

  Fig 1. Dead bone exposed through the ulcerated mucosa

Diagnosis

Any patient with previous history of RT of the head and neck presenting with signs and symptoms described earlier must be investigated thoroughly to confirm or rule out a diagnosis of ORN in order to allow definitive treatment. This will involve the following:

• Clinical examination
• Imaging (orthopantomogram, CT scan etc)
• Biopsy (to rule out recurrence of cancer in the affected site)

Preventing or reducing the risk of  ORN

All patients who will be undergoing radiation therapy (RT) of the head and neck region should be seen by a Dentist well versed with the care required, or a Dental Specialist (Special Needs Dentistry) before starting treatment for the following:

• Ccomplete and thorough oral and dental assessment involving not only clinical examination but also to include appropriate radiological investigations
• Comprehensive preventive dental treatment (fillings, extractions, root canal therapy, scaling, etc)
• Personalised preventive dental programme
  • Oral hygiene instructions according to individual needs (effective tooth brushing, use of interdental brush, flossing)
  • Diet counselling
  • Fluoride therapy (chair side and home care)

This patient will then be follow up during RT where they may develop oral mucositis and experience some degree of pain ranging from discomfort to severe painful sensation especially on eating. Patient will be taught how to manage the pain as well as maintain optimum oral hygiene where possible under such circumstances.

RT may also cause permanent damage to salivary glands resulting in life-long severe dry mouth that predispose patient  to rampant dental caries (a rapid progressive form of tooth decay) which may lead to tooth extraction. As such, on completion of RT the patient will be underclose and regular follow up for life with emphasis on the following:

• Personalised preventive dental programme (chairside and home care) – to be reinforced
• Early interceptive dental treatment where necessary
• Monitor for early signs of ORN to allow early intervention.
• Dry mouth management

Managing Osteoradionecrosis (ORN)

Treatment of ORN depends on the extent of bone involvement.Any dental infection if present should be treated with appropriate antibiotics. The treatment options may include:

• Medical treatment only (pentoxifylline and tocopherol)
• Combined medical and surgical treatment (involving removal of dead bone)
• Surgical treatment in the case of fracture or imminent fracture

Conclusion

Patients undergoing radiation therapy of the head and neck region involving the jaws are at risk of developing osteoradionecrosis. The oral and dental care of these patients are key to helping prevent or reduce the risk of osteoradionecrosis of the jaws.It begins before and continue during the radiation therapy, followed by life-long regular dental reviews on completion of radiation treatment with emphasis on preventive dental measures as well as early interceptive dental treatment.

 References

1. Epstein, J.B. (2003).Oral Cancer. In Greenberg, M.S. &Glick, M(Eds.)Burket’s Oral Medicine Diagnosis & Treatment(pp.194-234)(10th Ed). Hamilton.Ont: B.C Decker.
2. Lyons, A.&Ghazali, N. (2008). Osteoradionecrosis of the jaws: current understanding of its pathophysiology and treatment. Br J Oral MaxillofacSurg, 46, 653-660.
3. Madrid, C., Abarca, M.&Bouferrache,K. (2010). Osteoradionecrosis: An update. Oral Oncology, 46, 471-474.
4. Neville, B.W., Damm, D.D.,Allen, C.M. &Bouquot, J.E. (2002). Physical and Chemical Injuries. Oral & Maxillofacial Pathology(pp. 253-284) (2nd Ed.).Philadelphia: W.B.Sauders.