I have gap between the front two teeth. I had the front two teeth shaved for a Zirconia crown. The doctor did not give any temporary crown. Now 2 days after the two teeth were shaved, one of them has a small hole in it which hurts when I touch it. The dentist says the pulp is exposed and I need root canal before the crown. But I don't have any cavities on the front teeth.Is root canal really necessary?