However the studies concerning the corrosion behaviour
of magnesium in biological environment and cytotoxicity of
magnesium are lacking. Recently, a number of studies have
been carried out to investigate the corrosion behaviour of
magnesium alloys in artificial physiological fluids and most
of them are Al containing Mg alloys [68]. Most alloying
elements will dissolve into the human body during the
magnesium alloy degradation, for example, when the
AZ91D magnesium alloy is used, the Al present in the alloy
would get into the human body, which might be hazardous,
from the health point of view. The magnesium alloy implants
are expected not to degrade until the healing is completed
and tissue growth has occurred. However it is unfortunate to
observe that magnesium and its alloys corrode too quickly at
the physiological pH of 7.2 to 7.4 as well as in physiological
media containing high concentrations of aggressive ions,
thereby loosing mechanical integrity before the tissues have