Well, these are some hard teeth or if we can say, ‘indurate teeth’.
Indurate, in simple words, means hardened.
Meaning of Indurate:
1. To make hard; harden.
2. To inure, as to hardship or ridicule.
3. To make callous or obdurate
Well, in a way we have trivialized matters here. Indurate is not really used to refer to hardened teeth but to those individuals who have become emotionally hardened because of the hardships they have faced.