In vitro degradation of cements: a comparison of three test methods.

Three in vitro tests were evaluated on the basis of their ability to predict the relative resistance of various types of luting cements to disintegration in the oral cavity. The tests were (1) weight loss, (2) reduction in size of cement films held between glass optical flats, and (3) reduction in transverse strength. Storage media evaluated were H2O and 0.1, 0.01, and 0.001 M HAc. These data were compared with previously obtained measurements on the in vivo disintegration rates of the same cements. The best correlation with in vivo disintegration was obtained by test No. 2 when the specimens were subjected to 0.01 M HAc.