If you are asking that,will it pain while doing root canal treatment, then the answer will be no as ur dentist will give us local anaesthesia which will last for about 2-3 hours after that he/she will prescribe u some painkiller medicines to alleviate ur pain secondly it will not pain in future if the root canal treatment is done successfully.
Answer to your second question is again no,if it is other than wisdom tooth or very badly broken tooth
Third question's answer is that composite is one of the best material in dentistry,so if ur dentist does it successfully and if it is a standard quality, company composite then it will last almost for many many years.
Now coming to the care,u get the filling done after having intraoral x ray done and following all the postoperative instructions given by your dentist.
Regards!
Next Steps
Get the X ray done to decide outcome of the treatment.
Health Tips
Take a regular follow up of your dentist.