Dense alumina aged in vivo.

Auger electron spectroscopy was used to investigate the relative concentration of the calcium impurity at the external and fracture surfaces of a dense alumina after in vivo exposure for 6, 12, and 23 weeks. The Ca concentration at the external surface initially decreased, reached a minimum at 12 weeks, and increased thereafter. These results, were compared with the flexural strength, which decreased nearly linearly from 6 to 23 weeks.