Table 1.

Elastic and geometrical properties of the dentin–adhesive interface phases.

interface phases	elastic modulus (GPa)	thickness (μm)
composite	ca 30
adhesive	ca 5	2–5
peritubular dentina	26–30	0.6–1
intertubular dentinb	20	2–5
partially demineralized dentinc	13	variable
graded hybrid layerd	4–2	2–10
exposed collagend	<2	variable

^aBased upon measurements by Kinney et al. (1999).

^bBased upon measurements by Kinney et al. (1999) and Katz et al. (2001). The intertubular dentin modulus was measured to be 20 GPa by Kinney et al. (1999).

^cKatz et al. (2001) found that the intertubular dentin close to the interface has a lower modulus of 13 GPa due to partial demineralization during etching. Therefore, in the vicinity of the interface, the intertubular dentin is considered to have a modulus gradient from 13 GPa ramping up to 20 GPa.

^dBased upon measurements by Katz et al. (2003).