u/Agreeable_Common_674

Ive been experiencing pretty bad pain in one of my teeth (that had a filling done years ago) out of the blue. It all started when I had a particularly hot meal and ever since then Ive been very sensitive to hot food and having overall tooth pain on the daily. After looking at it clearly I found this slightly greyish tone on the bottom of this teeth with a darker hue in the middle of the teeth and searched google to find that it saying my tooth is already dead/dying. Im afraid theres a large hidden cavity in the inside of my teeth that isn't visible from the outside. Is this possible? Could anyone give me any information about my teeth before I go to the dentist next week?