Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
R-curve response of human enamel. (a) Typical R-curve response of enamel for cracks growing from occlusal surface toward the DEJ (reprinted from Ref. [88] with permission from the publisher), (b) comparison of R-curve response of enamel for forward and reverse crack growth directions (reprinted from Ref. [88] with permission from the publisher).
