Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain and explanation of the symptoms it is clear that there is reinfection in the tooth as you told that half of the root canal is missing so there is bacterial re-infection leading to
severe pain..
You should immediately
consult a dentist and get evaluated and get an xray done to rule out the status of the root canal filling and possible underlying infection and
Dental abscess formation..
As of now you can take antibiotic like Augmentin 625mg three times a day and Ultram [Tramadol 5O mg] three times a day,
Pantoprazole 4O mg once in morning empty stomach..
Avoid chewing from the affected side and also avoid intake of extreme hot and cold foods and liquids to prevent irritation..
After evaluation the dentist can either do a re-
root canal treatment or extraction depending upon the condition of tooth.
Hope this information helps..
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Thanks and regards..
Dr.Honey Nandwani Arora..