Maxfacts

A variety of conditions ranging from infection, unusual immune responses, unwanted effects of medications through to exposure to high-energy radiation can cause necrosis (cell death). In bone this appears as sequestration where mineralised bits of bone with no blood supply are being shed out through the lining of the mouth.

Tiny pieces can appear following infection – even after something relatively simple like a tooth extraction followed by a severe ‘dry socket’.

Rare responses to low grade irritation can cause a mixture of extra bone production and painful sequestration.

Medications such as antiresorptive agents (like the group of bisphosphonate drugs commonly prescribed to treat osteoporosis (brittle bones)) have been clearly shown to predispose to chemical osteonecrosis of the jaws (ONJ). In fact these drugs can also cause abnormalities of the mucosa of the mouth but are better known for causing bone necrosis.

Radiotherapy, in particular radical irradiation with high doses (over 60 Gy) and especially when combined with chemotherapy, can cause osteoradionecrosis (ORN) of the jaws and other target bones. The jaws are exceptionally vulnerable in having structures embedded in the bone that also transgress a contaminated mucosa (the lining of the mouth) – teeth or implants.