Osteonecrosis of the jaw: what do bisphosphonates do?

Osteonecrosis of the jaw is a new disease, partly caused by bisphosphonates. It is commonly assumed that the bisphosphonates somehow cause cell death (osteocyte necrosis) within the jawbone, which makes it prone to chronic infection. In this article, an alternative pathogenetic theory is suggested, based on the normal effect of bisphosphonates. According to the new theory, the bone is alive until it is injured and infected, and the reduced resorptive ability due to bisphosphonates hinders the formation of a fresh bone surface for re-establishment of bone cell coverage. The theories are compared, based on the recent, very scarce literature. None of them can be completely refuted, but the demonstration of living osteocytes within the lesion and the number of necessary assumptions speak against the theory of a primary, bisphosphonate-induced necrosis.