Osteoradionecrosis Flashcards
Describe radiotherapy as a management method for head and neck cancers
- Most commonly used in conjunction with surgery
- Can be used alone but usually in palliative setting
- Kills cancer cells and normal cells in field of radiation
What is osteoradionecrosis?
Exposed irradiated bone that fails to heal over a period of 3 months excluding areas of residual or recurrent tumour
Describe when the risk of ORN is at its greatest
- Radiation dose > 60 Gy
- From 10 days before to several years after surgery
- Malnourished / Immunocompromised patients
Describe the aetiology of ORN
- More common in mandible as poorer blood supply
- Initiation factor often extraction
- Affects approx. 7% of irradiated patients
- Risk thought to increase as dose increases
Describe 3 risk factors of a patient developing ORN
- Radiation related factors - Total dose / field size
- Trauma and surgery
- Drug use
Explain why smoking is a risk factor for ORN
Tends to dry out the mouth which reduces the chances of proper healing
Describe the pathogenesis of ORN
- Irradiated bone, periosteum and overlying soft tissue undergo inflammation and obliterative endarteritis
- Lead to cellular death, hypovasularity and fibrosis
- Radiated bed is hypocellular and devoid of fibroblasts, osteoblasts and osteocompetent cells
- Bone death due to alveolar necrosis
Describe the clinical features of ORN
Exposed bone in previously irradiated mouth with possibility of pain, discharge, external sinus or pathological fracture
Describe the radiological appearance of ORN
- Areas of large radiolucency present which can be ill defined
- Similar looking to recurrent tumour
Explain one pro and one con of the Notani Classification for ORN
Pro - Very straightforward and easy to understand
Con - Only discusses mandible which is draw back
When does a pathological fracture usually occur in the mandible if ORN is present?
Usually only get fracture if ORN has gone past inferior dental canal
What are the clinical features of Notani Grade I?
ORN confined to dentoalveolar bone
What are the clinical features of Notani Grade II?
ORN limited to dentoalveolar bone or mandible above the IDC or both
What are the clinical features of Notani Grade III?
ORN involving mandible below IDC, or pathological fracture, or skin fistula
Name 3 types of management for ORN
- Local debridement
- Ultrasound therapy
- Hyperbaric Oxygen Therapy (HBOT)
Describe 4 pharmacological agents used in the management of ORN
- Chlorhexidine mouthwash (10ml bd)
- Doxycycline (100mg od)
- Pentoxifylline (400mg bd)
- Tocopherol (1000 IU caps / 1000mg susp)
Describe local debridement as a management strategy for ORN
- Removing dead bone so exposed bone is vital
- Bony sequestra to remove sharp pieces of bone at the surface
Describe ultrasound therapy as a management strategy for ORN
- Improves vascular supply to the area
- Can only do when there is 0% chance of tumour being present as ultrasound therapy aids progression of tumour
- Limited to patients over 2 years from surgery
Describe HBOT as a management strategy for ORN
- Increases oxygen delivered to the area
- Reduction in hypoxia and increase in angiogenesis
Describe the action of the pharmacological agents which make up triple therapy treatment for ORN
Chlorhexidine - Antibacterial to prevent infection
Doxycycline - Anti fibrolytic and has high bone penetration properties
Pentoxifylline - Anti inflammatory
Tocopherol - Anti oxidant so removes free radicals causing ORN
Describe the key points in prevention of ORN
- Extract teeth with poor prognosis prior to radiotherapy (at least 2 weeks before)
- Ensure dentures fit well
- Avoid need for further extractions (check ups, OHI etc)
Describe the key points for GDPs with regards to prevention of ORN
- Very difficult to treat so prevention most important
- Highest risk post radiotherapy, then decreased slightly and as patient gets older, risk increases again
- Patient has big part to play with tooth brushing and cleaning (OHI)
- Dietary advice as taste will change due to reduced salivary flow so patients opt for higher sugar and salt content foods as they taste these better
