Figure 6. The Young’s modulus of dentin as measured by AFM indentation. The solid circles represent repeated measurements obtained in water over the course of several days. The open circles show measurements obtained in Hanks’ Balanced Salt Solution (HBSS). The water-stored specimens exhibited a rapid decline in modulus over 14 days. This decline was attributed to a loss of mineral from the near surface layer. The specimens stored in HBSS, in contrast, maintained relatively constant modulus values over the same time period. The error bars are the standard deviations of the means of several specimens. Data from Habelitz et al. (2002a).