The main question would be are those teeth restorable or not. If more than 50 percent of crown structure is gone and less than two walls of the tooth are present then the tooth is not restorable. Post and core is a method to prolong the life of a weak tooth and it can be attempted depending on the amount of sound structure of tooth left. Preferably always cap the tooth post root canal to avoid this in the future.
Next Steps
visit dentist
Health Tips
crown if possible, or post and core and crown....in worse case extraction and replacement using either bridge or implant after evaluation of the case