Hello, your mother's tooth has decay that has reached the nerves in the centre of the tooth.
In such cases the germs in the decay decay the nerves and so there is pain on chewing or food lodgement in the cavity or pain may even start on having hot or cold stuffs.
In such a situation a Root Canal Treatment (RCT) followed by a crown(covering) is needed to be done by an experienced dentist.
This way we can save the tooth.
Visit a dentist immediately
Next Steps
visit a dentist
Health Tips
do not have hot or cold foods, and avoid chewing from that side.