Hey L., two of my five kids have had this happen to them. My son fell on his brother's head and it turned his tooth dark gray. I took him in and he got a root canal. It traumatized him, and not much has in his 13 years. It never turned back, his new teeth came in perfect. Then my younger daughter was at the Blast in Eagan and fell down a level in the climbing thing and landed on her face. It turned her teeth gray. They've gone back and forth for over a year, but I did not do the root canal. They did an xray and there's no structural issues with the teeth. I go to Children's Dentistry in Burnsville, she was GREAT with my girls and they had to have a lot of work done.