I had a trimming and root canal done on lower right incisor for putting on a dental cap for cosmetic purposes. There is no sign of infection and the tooth is pretty healthy even in X-rays. However, since the root canal was done 5-6 months ago, the tooth has been incredibly sensitive to touch and pressure that it hurts even if my tongue or lip touches against it. My dentist told me they'd fix the permanent cap once the pain subsides, but six months now and it shows no signs of improvement. I had no problem with my upper teeth with the same dental cap treatment for cosmetic purpose. Could anyone tell me what could be the reason and solution ?