When u have done root canal Treatment to a tooth that means that tooth is dead,bcz aftr rct he cnt feel any pain or otr sensation,but cn be used to chewing.if u hv any pain that issue cn be due to many reasons like food getting struck btwm the cap and tooth surface or can even be badly dne rct,u shd meet Ur doctr so that he can take a x-ray of that tooth and tell Ur what's exactly the issue.if it's the rct done badly then re rct has to be done..
Next Steps
don't wory it can be sorted out