Can biting into a stone hard bread crust cause tooth sensitivity and slight afterache to liquid only in one tooth? does sensodyne help?

Possibly: Pain comes from a bruising of the nerve of the tooth sometimes. It is called either reversible pulpitis ( it will go away) or irreversible pulpitis ( it will not go away & root canal therapy may be necessary). Bruising may occur from a sharp blow such as a destructive bite( yes stone hard bread qualifies) . Sensodyne is for thermal sensitivity & may not remedy your condition.

Good answers: Also consider homeopathic hypericum for the sensitivity. See your dentist if it keeps up.

Yes: You have started a inflammatory process on the tooth called a pulpitis. It is most likely reversible, which means your tooth will eventually go back to normal. The inflammation is in the nerve and sensodyne can't help out there.