Tooth crack

Not quite a regular dental check-up, but...

I go right away when I feel sick.

They kept telling me to be careful because I kept developing small cracks each time.

There is no problem right now.

Eating hard foods or hot foods frequently

They say they don't know how long they can hold out.

Could it suddenly break like this?

I'm trying to be as restrained as possible, but

I felt suddenly scared.