Hi Yee Ham,
I would say most patients take few days-weeks for proper healing of the tissues around the tooth. And even so, you should try not to use the tooth to eat hard food eg) nuts/ice etc. This is due to the fact that the tooth structure itself is already lessened, and forces overtime generates a wedging effect on the tooth, which may split it apart. Thus I would strongly advise you to avoid eating hard food as much as possible even after you have had your root canal treatment, as this would help to protect your tooth in the long run.
Yes, some patients do feel some discomfort due to the pressure from the file being pushed beyond the length of the tooth root. Generally a top up of local anaesthetic should be able to relieve the pain.
As for whether your tooth needs a crown, it highly depends on the dentist’s clinical judgement. I would usually crown the upper second premolar post root canal treatment to prevent risks of fracture from the wedging forces as previously mentioned. However there are always exceptions to every case eg) the patient’s bite, amount of tooth structure loss etc, and I would not be able to comment further as I have not seen you clinically.
Hope this answers your queries, and have a speedy recovery!
