Should I go back to the dentist to have him correct an issue where food gets stuck between two crowns or is this normal?

I have two crowns on my lower back teeth where food (worse with steak/ chicken etc) always gets stuck between. When I floss, it's very hard to get the food out. The floss also catches on something on one of the crown's lower edges- like there is an overhang on the crown. Then, when I get the food out, the area is very sensitive to cold (like when I swish water around to clear the area). The dentist is aware of the part that catches on the floss, but did not seemed concerned enough to fix it.